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EP0323242A2 Expired / Lapsed EP ⏱️ 0.0 years remaining

Method and apparatus for aligning two objects, and method and apparatus for providing a desired gap between two objects

Assignee: Toshiba Corp
•
Filing: 1988-12-28
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Granted: —
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Expires: 2008-12-28
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Abstract

Abstract A first diffraction grating (15) is formed on a mask (13), and a second diffraction grating (16) is formed on a wafer (12). Two light beams having slightly different frequencies interfere with each other and are diffracted as they travel through the first diffraction grating (15), are reflected by the second diffraction grating (16), and again pass through the first diffrac­tion grating (15). As a result, they change into thrice diffracted light beams. The diffracted light beams are combined into a detection light beam which has a phase shift φ A representing the displacement between the wafer (12) and the mask (13), or a phase shift φ G representing the gap between the wafer (12) and the mask (13). The detection light beam is converted into a detection signal (34). The phase difference between the detection signal (34) and a reference signal (36) having no phase shifts are calculated, thus determining phase shift φ A or φ G . The displacement or the gap is determined from the phase shift. In accordance with the displacement or the gap, the wafer and the mask are aligned to each other, or the gap between them is adjusted to a desired value. Since the detection signal is generated from diffracted light beams, its S/N ratio is sufficiently great. Therefore, the displacement or the gap is deter­mined with high precision. In addition, it is possible with the invention to perform the aligning of the wafer (12) and the mask (13) and the adjusting of the gap therebetween, simultaneously.

Inventors

  • 👤 Yoriyuki C/O Patent Division Toshiba Ishibashi
  • 👤 Ryoichi C/O Patent Division Toshiba Hirano
  • 👤 Kyoji C/O Patent Division Toshiba Yamashita

Bibliographic Details

Application Number —
Jurisdiction EP
Data Source google_patents
Last Synchronized 2026-11-02 09:12
CPC Classifications
G; G03; G03F; G03F9/00; G03F9/70; G03F9/7049; G03F9/7003; G03F9/7023

Claims Analysis

Total Claims: 144
Claim 1
Independent Claim 411 words
A method of aligning first and second objects opposing each other, said first object (13) having a first diffraction grating (15) formed on that surface which opposes said second object (12), and said second object (12) having a second diffraction grating (16) formed on that surface which opposes said first object (13), said method characterized by comprising the steps of: emitting from a light source (17) a first light beam (20) having a frequency f1 and a second light beam (21) having a frequency f2, where f1 is not equal to f2; applying the first and second light beams (20, 21) onto one of first and second diffraction gratings (15, 16) so that the first and second light beams interfere with each other and are diffracted by the first diffrac­tion grating (15) and a second diffraction grating (16), whereby the first light beam (20) is changed into at least twice diffracted light beams having the frequency f1, and the second light beam (21) is changed into at least twice diffracted light beams having frequency f2, two beams of arbitrary same order of the diffracted light beams which have frequencies f1 and f2 and are interfering each other, and two beams of specified same order of the diffracted light beams which have frequen­cies f1 and f2 and a phase shift φ A which corresponds to a displacement between the first and second objects (12, 13); detecting and converting, by a first sensor means (33), the two beams of the specified same order into a beat signal, i.e., a detection signal (34) having a fre­quency Δf (= |f2-f1|) and the phase shift φ A ; applying a third light beam having the frequency f1 and being in phase with the first light beam, and a fourth light beam having frequency f2, being in phase with the second light beam, and interfering with the third light beam; detecting and converting, by a second sensor (36) means, said third and fourth light beams into a beat signal, i.e., a reference signal (37) having a frequency Δf (= |f2-f1|); calculating a phase difference between the detec­tion signal (34) and the reference signal (37), thereby to determine the phase shift φ A and thus the displace­ment between said first and second objects (12, 13); and adjusting said first and second objects (12, 13) relative to each other in accordance with the displace­ment, thereby to align said first and second objects (12, 13) with respect to each other.
Claim 2
Independent Claim 411 words
A method of aligning first and second objects opposing each other, said first object (13) having a first diffraction grating (15) formed on that surface which opposes said second object (12), and said second object (12) having a second diffraction grating (16) formed on that surface which opposes said first object (13), said method characterized by comprising the steps of: emitting from a light source (17) a first light beam (20) having a frequency f1 and a second light beam (21) having a frequency f2, where f1 is not equal to f2; applying the first and second light beams (20, 21) onto one of first and second diffraction gratings (15, 16) so that the first and second light beams interfere with each other and are diffracted by the first diffrac­tion grating (15) and a second diffraction grating (16), whereby the first light beam (20) is changed into at least twice diffracted light beams having the frequency f1, and the second light beam (21) is changed into at least twice diffracted light beams having frequency f2, two beams of arbitrary same order of the diffracted light beams which have frequencies f1 and f2 and are interfering each other, and two beams of specified same order of the diffracted light beams which have frequen­cies f1 and f2 and a phase shift φ A which corresponds to a displacement between the first and second objects (12, 13); detecting and converting, by a first sensor means (33), the two beams of the specified same order into a beat signal, i.e., a detection signal (34) having a fre­quency Δf (= |f2-f1|) and the phase shift φ A ; applying a third light beam having the frequency f1 and being in phase with the first light beam, and a fourth light beam having frequency f2, being in phase with the second light beam, and interfering with the third light beam; detecting and converting, by a second sensor (36) means, said third and fourth light beams into a beat signal, i.e., a reference signal (37) having a frequency Δf (= |f2-f1|); calculating a phase difference between the detec­tion signal (34) and the reference signal (37), thereby to determine the phase shift φ A and thus the displace­ment between said first and second objects (12, 13); and adjusting said first and second objects (12, 13) relative to each other in accordance with the displace­ment, thereby to align said first and second objects (12, 13) with respect to each other.
Claim 3
Dependent Claim 26 words
The method according to claim 1, characterized in that said first object is an exposure mask (13), and said second object is a semiconductor wafer (12).
Claim 4
Dependent Claim 25 words
The method according to claim 1, characterized in that said first diffraction grating (15) has a one-­dimensional pattern consisting of a plurality of parallel stripes.
Claim 5
Dependent Claim 18 words
The method according to claim 3, characterized in that said second diffraction grating (16) has a checkered pattern.
Claim 6
Dependent Claim 44 words
The method according to claim 3, characterized in that said second diffraction grating (16) has a two-dimensional pattern consisting of a first set of parallel stripes and a second set of parallel stripes intersecting at right angles with the strips of the first set.
Claim 7
Dependent Claim 62 words
The method according to claim 4, characterized in that said first and second objects (12, 13) are moved relative to each other in an x axis, and said first diffraction grating (15) is arranged such that said stripes extend parallel to a y axis intersecting at right angles with the x axis and existing in the same plane as the x axis.
Claim 8
Dependent Claim 58 words
The method according to claim 6, characterized in that the orders of said at least twice diffracted light beams are nth in the x axis and rth in the y axis and, thus, represented as (n, r), where n and r are integers; and said two light beams of the specified same order are of (0, r) order.
Claim 9
Dependent Claim 118 words
The method according to claim 6, characterized in that said first diffraction grating (15) is a light-­permeating one, said second diffraction grating (16) is a light-reflecting one, so that said first and second light beams (20, 21) pass through said first diffraction grating (15) and diffracted thereby, are reflected and diffracted by said second diffraction grating (16), and then pass through said first diffraction grating (15) and diffracted by it, whereby said first light beam (20) is changed into thrice diffracted light beams having the frequency f1, and said second light beam (21) is changed into thrice diffracted light beams having the frequency f2; and said at least twice diffracted light beams include these thrice diffracted light beams.
Claim 10
Dependent Claim 110 words
The method according to claim 8, characterized in that said first and second light beams (20, 21) are applied to a point (31) on said first diffraction grating (15), said beams extending in a second plane (102), being symmetrical with respect to a line (28), and inclining to the line (28) at angle ±α, said second plane (102) inclining at angle β to a first plane (101) extending at right angles to the y axis, said line (28) extending in the second plane (102) and at right angles to the x axis, and the point (31) being a intersection point which the line (28) intersects with the first grating (15).
Claim 11
Dependent Claim 54 words
The method according to claim 9, characterized in that said angle ±α is sin⁻¹(±m₀λ/Px), where m₀ is an integer, λ is the standard wavelength of said first and second light beams (20, 21), and Px is a pitch at which the strips of said first diffraction grating (15) are arranged in the x axis.
Claim 12
Dependent Claim 14 words
The method according to claim 9, characterized in that said angle β is 0°.
Claim 13
Dependent Claim 57 words
The method according to claim 9, characterized in that the stripes of said first diffraction grating (15) are spaced apart in the x axis at regular inter­vals, and the squares of said second diffraction grating (16) are spaced apart in the x axis at the same regular intervals as the stripes of the first diffraction grating (15).
Claim 14
Dependent Claim 105 words
The method according to claim 12, charac­terized in that said thrice diffracted light beams have orders nth order in the x axis and rth in the y axis, i.e., (n, r) order, where n and r are integers, said orders being defined with respect to an origin (0, 0) which is a point on an z′ axis extending in a third plane (103) which is symmetrical to the second plane (102) with respect to the first plane (101); and said two light beams of the specified same order are of the (0, r) order which is identical to that of said thrice diffracted light beams.
Claim 15
Dependent Claim 55 words
The method according to claim 1, characterized in that said first and second light beams (20, 21) are applied to said second diffraction grating (16) through a projection lens (40) located between said first and second objects (12, 13), after said first and second light beams have been diffracted by said first diffrac­tion grating (15).
Claim 16
Dependent Claim 65 words
The method according to claim 1, characterized in that a projection lens (40) is located between said first and second objects (12, 13), so that the first and second light beams (20, 21) are applied to said second diffraction grating through the projection lens (40), are reflected and diffracted thereby, and then are transferred to said first diffraction grating (15) through the projection lens (40).
Claim 17
Dependent Claim 49 words
The method according to claim 1, characterized in that said third and fourth light beams have each two components, respectively, which are divided from said first and second light beams (20, 21), after said first and second light beams (20, 21) have been transferred to the first grating (15).
Claim 18
Dependent Claim 34 words
The method according to claim 16, charac­terized in that said two components are those components of said first and second light beams (20, 21) which have been reflected by said first diffraction grating (15).
Claim 19
Dependent Claim 66 words
The method according to claim 16, charac­terized in that said two light beams of the specified same order travel in a first path until they reach said first sensor means (33), and said two components travel in a second path until they reach said second sensor means (36), and said first and second paths are located close to each other and are substantially equal in length.
Claim 20
Dependent Claim 36 words
The method according to claim 1, characterized in that said third and fourth light beams have each two beams of the same order other than the specified order of said at least twice diffracted light beams.
Claim 21
Dependent Claim 73 words
The method according to claim 19, charac­terized in that said two light beams of the specified order travel in a first path until they reach said first sensor means (33), said two beams of the same order other than the specified order travel in a second path until they reach said second sensor means (36), and said first and second paths are located close to each other and are substantially equal in length.
Claim 22
Dependent Claim 103 words
The method according to claim 1, characterized in that said third and fourth light beams have each two components, respectively, which are divided from said first and second light beams (20, 21) before said first and second light beams are transferred to said first diffraction grating (15); said two light beams of the specified same order travel in a first path until they reach said first sensor means (33); said two components travel in a second path until they reach said second sensor means (36); and said first and second paths are located close to each other and are substantially equal in length.
Claim 23
Independent Claim 429 words
An apparatus for aligning first and second objects opposing each other, said first object (13) having a first diffraction grating (15) formed on that surface which opposes said second object (12), and said second object (12) having a second diffraction grating (16) formed on that surface which opposes said first object (13), said apparatus characterized by comprising: light source means (17) for emitting a first light beam (20) having a frequency f1 and a second light beam (21) having a frequency f2, where f1 is not equal to f2; first light-applying means for applying the first and second light beams (20, 21) onto one of first and second diffraction gratings (15, 16) so that the first and second light beams interfere with each other and are diffracted by the first diffraction grating (15) and a second diffraction grating (16), whereby the first light beam (20) is changed into at least twice dif­fracted light beams having the frequency f1, and the second light beam (21) is changed into at least twice diffracted light beams having frequency f2, two beams of arbitrary same order of the diffracted light beams which have frequencies f1 and f2 and are of interfering each other, and two beams of specified same order of the diffracted light beams which have frequencies f1 and f2 and a phase shift φ A which corresponds to a displacement between the first and second objects (12, 13); first sensor means (33) for detecting and convert­ing, the two light beams of the specified same order into a beat signal, i.e., a detection signal (34) having a frequency Δf (= |f2-f1|) and the phase shift φ A ; second light-applying means for applying a third light beam having the frequency f1 and being in phase with the first light beam, and a fourth light beam having frequency f2, being in phase with the second light beam, and interfering with the third light beam; second sensor means (36) for detecting and convert­ing, by a second sensor means, said third and fourth light beams into a beat signal, i.e., a reference signal (37) having a frequency Δf (= |f2-f1|); calculator means (38) for calculating a phase dif­ference between the detection signal (34) and the reference signal (37), thereby to determine the phase shift φ A and thus the displacement between said first and second objects (12, 13); and position-adjusting means (39) for moving said first and second objects (12, 13) relative to each other in accordance with the displacement, thereby to align said first and second objects (12, 13) with respect to each other.
Claim 24
Independent Claim 429 words
An apparatus for aligning first and second objects opposing each other, said first object (13) having a first diffraction grating (15) formed on that surface which opposes said second object (12), and said second object (12) having a second diffraction grating (16) formed on that surface which opposes said first object (13), said apparatus characterized by comprising: light source means (17) for emitting a first light beam (20) having a frequency f1 and a second light beam (21) having a frequency f2, where f1 is not equal to f2; first light-applying means for applying the first and second light beams (20, 21) onto one of first and second diffraction gratings (15, 16) so that the first and second light beams interfere with each other and are diffracted by the first diffraction grating (15) and a second diffraction grating (16), whereby the first light beam (20) is changed into at least twice dif­fracted light beams having the frequency f1, and the second light beam (21) is changed into at least twice diffracted light beams having frequency f2, two beams of arbitrary same order of the diffracted light beams which have frequencies f1 and f2 and are of interfering each other, and two beams of specified same order of the diffracted light beams which have frequencies f1 and f2 and a phase shift φ A which corresponds to a displacement between the first and second objects (12, 13); first sensor means (33) for detecting and convert­ing, the two light beams of the specified same order into a beat signal, i.e., a detection signal (34) having a frequency Δf (= |f2-f1|) and the phase shift φ A ; second light-applying means for applying a third light beam having the frequency f1 and being in phase with the first light beam, and a fourth light beam having frequency f2, being in phase with the second light beam, and interfering with the third light beam; second sensor means (36) for detecting and convert­ing, by a second sensor means, said third and fourth light beams into a beat signal, i.e., a reference signal (37) having a frequency Δf (= |f2-f1|); calculator means (38) for calculating a phase dif­ference between the detection signal (34) and the reference signal (37), thereby to determine the phase shift φ A and thus the displacement between said first and second objects (12, 13); and position-adjusting means (39) for moving said first and second objects (12, 13) relative to each other in accordance with the displacement, thereby to align said first and second objects (12, 13) with respect to each other.
Claim 25
Dependent Claim 26 words
The apparatus according to claim 22, charac­terized in that said first object is an exposure mask (12), and said second object is a semiconductor wafer (13).
Claim 26
Dependent Claim 25 words
The apparatus according to claim 22, charac­terized in that said first diffraction grating (15) has a one-dimensional pattern consisting of a plurality of parallel stripes.
Claim 27
Dependent Claim 18 words
The apparatus according to claim 24, charac­terized in that said second diffraction grating (16) has a checkered pattern.
Claim 28
Dependent Claim 44 words
The apparatus according to claim 24, charac­terized in that said second diffraction grating (16) has a two-dimensional pattern consisting of a first set of parallel stripes and a second set of parallel stripes intersecting at right angles with the strips of the first set.
Claim 29
Dependent Claim 62 words
The apparatus according to claim 25, charac­terized in that said first and second objects (12, 13) are moved relative to each other in an x axis, and said first diffraction grating (15) is arranged such that said stripes extend parallel to a y axis intersecting at right angles with the x axis and existing in the same plane as the x axis.
Claim 30
Dependent Claim 58 words
The apparatus according to claim 27, charac­terized in that the orders of said at least twice diffracted light beams are nth in the x axis and rth in the y axis and, thus, represented as (n, r), where n and r are integers; and said two light beams of the spe­cified same order are of (0, r) order.
Claim 31
Dependent Claim 118 words
The apparatus according to claim 27, charac­terized in that said first diffraction grating (15) is a light-permeating one, said second diffraction grating (16) is a light-reflecting one, so that said first and second light beams (20, 21) pass through said first diffraction grating (15) and diffracted thereby, are reflected and diffracted by said second diffraction grating (16), and then pass through said first diffrac­tion grating (15) and diffracted by it, whereby said first light beam (20) is changed into thrice diffracted light beams having the frequency f1, and said second light beam (21) is changed into thrice diffracted light beams having the frequency f2; and said at least twice diffracted light beams include these thrice diffracted light beams.
Claim 32
Dependent Claim 116 words
The apparatus according to claim 29, charac­terized in that said first light-applying means includes a means for applying said first and second light beams (20, 21) to a point (31) on said first diffraction grating (15), said beams extending in a second plane (102), being symmetrical with respect to a line (28), and inclining to the line (28) at angle ±α, said second plane (102) inclining at angle β to a first plane (101) extending at right angles to the y axis, said line (28) extending in the second plane (102) and at right angles to the x axis, and the point (31) being a intersection point which the line (28) intersect with the first grating.
Claim 33
Dependent Claim 53 words
The apparatus according to claim 30, characterized in that said angle ±α is sin⁻¹ (±m₀λ/Px), where m₀ is an integer, λ is the standard wavelength of said first and second light beams, and Px is a pitch at which the strips of said first diffraction grating (15) are arranged in the x axis.
Claim 34
Dependent Claim 14 words
The apparatus according to claim 30, charac­terized in that said angle β is 0°.
Claim 35
Dependent Claim 57 words
The apparatus according to claim 30, charac­terized in that the stripes of said first diffraction grating (15) are spaced apart in the x axis at regular intervals, and the squares of said second diffraction grating (10) are spaced apart in the x axis at the same regular intervals as the stripes of the first diffrac­tion grating (15).
Claim 36
Dependent Claim 105 words
The apparatus according to claim 33, charac­terized in that said thrice diffracted light beams have orders nth order in the x axis and rth in the y axis, i.e., (n, r) order, where n and r are integers, said orders being defined with respect to an origin (0, 0) which is a point on an z′ axis extending in a third plane (103) which is symmetrical to the second plane (102) with respect to the first plane (101); and said two light beams of the specified same order are of the (0, r) order which is identical to that of said thrice diffracted light beams.
Claim 37
Dependent Claim 57 words
The apparatus according to claim 22, charac­terized in that said first and second light beams (20, 21) are applied to said second diffraction grating (16) through a projection lens (40) located between said first and second objects (12, 13), after said first and second light beams (20, 21) have been diffracted by said first diffraction grating (15).
Claim 38
Dependent Claim 65 words
The apparatus according to claim 22, charac­terized in that a projection lens (40) is located bet­ween said first and second objects (12, 13), so that the first and second light beams (20, 21) are applied to said second diffraction grating through the projection lens (40), are reflected and diffracted thereby, and then are transferred to said first diffraction grating (15) through the projection lens (40).
Claim 39
Dependent Claim 49 words
The apparatus according to claim 22, charac­terized in that said third and fourth light beams have each two components, respectively, which are divided from said first and second light beams (20, 21), after said first and second light beams (20, 21) have been transferred to the first grating (15).
Claim 40
Dependent Claim 34 words
The apparatus according to claim 37, charac­terized in that said two components are those components of said first and second light beams (20, 21) which have been reflected by said first diffraction grating (15).
Claim 41
Dependent Claim 66 words
The apparatus according to claim 37, charac­terized in that said two light beams of the specified same order travel in a first path until they reach said first sensor means (33), and said two components travel in a second path until they reach said second sensor means (36), and said first and second paths are located close to each other and are substantially equal in length.
Claim 42
Dependent Claim 36 words
The apparatus according to claim 22, charac­terized in that said third and fourth light beams have each two beams of the same order other than the spe­cified order of said at least twice diffracted light beams.
Claim 43
Dependent Claim 73 words
The apparatus according to claim 40, charac­terized in that said two light beams of the specified order travel in a first path until they reach said first sensor means (33), said two beams of the same order other than the specified order travel in a second path until they reach said second sensor means (36), and said first and second paths are located close to each other and are substantially equal in length.
Claim 44
Dependent Claim 102 words
The apparatus according to claim 22, charac­terized in that said third and fourth light beams have each two components, respectively, which are divided from said first and second light beams (20, 21) before said first and second light beams are transferred to said first diffraction grating (15); two light beams of the specified same order travel in a first path until they reach said first sensor means (36); said two com­ponents travel in a second path until they reach said second sensor means (36); and said first and second paths are located close to each other and are substan­tially equal in length.
Claim 45
Independent Claim 417 words
A method of setting a gap between first and second objects opposing each other, said first object (13) having a first diffraction grating (51) formed on that surface which opposes said second object (12), and said second object (12) having a second diffraction grating (52) formed on that surface which opposes said first object (13), said method characterized by comprising the steps of: emitting from a light source (17) a first light beam having a frequency f1 and a second light beam having a frequency f2, where f1 is not equal to f2; applying the first and second light beams (20, 21) onto one of first and second diffraction gratings (51, 52) so that the first and second light beams (20, 21) interfere with each other and are diffracted by the first diffraction grating (51) and a second diffraction grating (52), whereby the first light beam (20) is changed into at least twice diffracted light beams having the frequency f1, and the second light beam (21) is changed into at least twice diffracted light beams having frequency f2, two beams of arbitrary same order of the diffracted light beams which have frequencies f1 and f2 and are interfering each other, and two beams of specified same order of the diffracted light beams which have frequencies f1 and f2 and a phase shift φ G which corresponds to a gap between the first and second objects (12, 13); detecting and converting, by a first sensor means (33), the two light beams of the specified same order into a beat signal, i.e., a detection signal (53) having a frequency Δf (= |f2-f1|) and the phase shift φ G ; applying a third light beam having the frequency f1 and being in phase with the first light beam, and a fourth light beam having frequency f2, being in phase with the second light beam, and interfering with the third light beam; detecting and converting, by a second sensor (36) means, said third and fourth light beams into a beat signal, i.e., a reference signal (37) having a frequency Δf (= |f2-f1|); calculating a phase difference between the detec­tion signal (53) and the reference signal (37), thereby to determine the phase shift φ G and thus the displace­ment between said first and second objects (12, 13); and adjusting said first and second objects (12, 13) relative to each other in accordance with the gap, thereby to set the gap between said first and second objects (12, 13) to a desired value.
Claim 46
Independent Claim 417 words
A method of setting a gap between first and second objects opposing each other, said first object (13) having a first diffraction grating (51) formed on that surface which opposes said second object (12), and said second object (12) having a second diffraction grating (52) formed on that surface which opposes said first object (13), said method characterized by comprising the steps of: emitting from a light source (17) a first light beam having a frequency f1 and a second light beam having a frequency f2, where f1 is not equal to f2; applying the first and second light beams (20, 21) onto one of first and second diffraction gratings (51, 52) so that the first and second light beams (20, 21) interfere with each other and are diffracted by the first diffraction grating (51) and a second diffraction grating (52), whereby the first light beam (20) is changed into at least twice diffracted light beams having the frequency f1, and the second light beam (21) is changed into at least twice diffracted light beams having frequency f2, two beams of arbitrary same order of the diffracted light beams which have frequencies f1 and f2 and are interfering each other, and two beams of specified same order of the diffracted light beams which have frequencies f1 and f2 and a phase shift φ G which corresponds to a gap between the first and second objects (12, 13); detecting and converting, by a first sensor means (33), the two light beams of the specified same order into a beat signal, i.e., a detection signal (53) having a frequency Δf (= |f2-f1|) and the phase shift φ G ; applying a third light beam having the frequency f1 and being in phase with the first light beam, and a fourth light beam having frequency f2, being in phase with the second light beam, and interfering with the third light beam; detecting and converting, by a second sensor (36) means, said third and fourth light beams into a beat signal, i.e., a reference signal (37) having a frequency Δf (= |f2-f1|); calculating a phase difference between the detec­tion signal (53) and the reference signal (37), thereby to determine the phase shift φ G and thus the displace­ment between said first and second objects (12, 13); and adjusting said first and second objects (12, 13) relative to each other in accordance with the gap, thereby to set the gap between said first and second objects (12, 13) to a desired value.
Claim 47
Dependent Claim 26 words
The method according to claim 43, charac­terized in that said first object is an exposure mask (13), and said second object is a semiconductor wafer (12).
Claim 48
Dependent Claim 25 words
The method according to claim 43, charac­terized in that said first diffraction grating (51) has a one-dimensional pattern consisting of a plurality of parallel stripes.
Claim 49
Dependent Claim 18 words
The method according to claim 45, charac­terized in that said second diffraction grating (52) has a one-dimensional pattern.
Claim 50
Dependent Claim 44 words
The method according to claim 45, charac­terized in that said second diffraction grating (52) has a two-dimensional pattern consisting of a first set of parallel stripes and a second set of parallel stripes intersecting at right angles with the strips of the first set.
Claim 51
Dependent Claim 46 words
The method according to claim 46, wherein the stripes of said one-dimensional pattern (51) extend parallel to the y axis, and said second diffraction grating (52) is arranged such that the stripes extend parallel to the x axis intersecting with the y axis at right angles.
Claim 52
Dependent Claim 58 words
The method according to claim 46, charac­terized in that the orders of said at least twice diffracted light beams are nth in the x axis and rth in the y axis and, thus, represented as (n, r), where n and r are integers; and said two light beams of the spe­cified same order are of (n, ±1) order.
Claim 53
Dependent Claim 118 words
The method according to claim 48, charac­terized in that said first diffraction grating (51) is a light-permeating one, said second diffraction grating (52) is a light-reflecting one, so that said first and second light beams (20, 21) pass through said first diffraction grating (51) and diffracted thereby, are reflected and diffracted by said second diffraction grating (52), and then pass through said first diffrac­tion grating (51) and diffracted by it, whereby said first light beam (20) is changed into thrice diffracted light beams having the frequency f1, and said second light beam (21) is changed into thrice diffracted light beams having the frequency f2; and said at least twice diffracted light beams include these thrice diffracted light beams.
Claim 54
Dependent Claim 110 words
The method according to claim 49, charac­terized in that said first and second light beams (20, 21) are applied to a point (31) on said first diffrac­tion grating (51), said beams extending in a second plane (102), being symmetrical with respect to a line (28), and inclining to the line (28) at angle ±α, said second plane (102) inclining at angle β to a first plane (101) extending at right angles to the y axis, said line (28) extending in the second plane (102) and at right angles to the x axis, and the point (31) being a inter­section point which the line (28) intersects with the first grating (51).
Claim 55
Dependent Claim 52 words
The method according to claim 51, charac­terized in that said angle ±α is sin⁻¹(±m₀λ/Px), where m₀ is an integer, λ is the standard wavelength of said first and second light beams, and Px is a pitch at which the strips of said first diffraction grating (51) are arranged in the x axis.
Claim 56
Dependent Claim 14 words
The method according to claim 51, charac­terized in that said angle β is 0°.
Claim 57
Dependent Claim 48 words
The method according to claim 51, charac­terized in that the stripes of said first diffraction grating (51) are spaced apart in the x axis at regular intervals, and the stripes of said second diffraction grating (52) are spaced apart in the y axis at the same regular intervals.
Claim 58
Dependent Claim 92 words
The method according to claim 54, charac­terized in that said thrice diffracted light beams have orders nth order in the x axis and rth in the y axis, i.e., (n, r) order, where n and r are integers, said orders being defined with respect to an origin (0, 0) which is a point on an z′ axis extending in a third plane (103) which is symmetrical to the first plane (101) with respect to the second plane (102); and said two light beams of the specified same order have (n, ±1) order.
Claim 59
Dependent Claim 55 words
The method according to claim 43, charac­terized in that said first and second light beams (20, 21) are applied to said second diffraction grating (52) through a projection lens (40) located between said first and second objects (12, 13), after said first and second light beams have been diffracted by said first diffraction grating (51).
Claim 60
Dependent Claim 65 words
The method according to claim 43, charac­terized in that a projection lens (40) is located be­tween said first and second objects (12, 13), so that the first and second light beams (20, 21) are applied to said second diffraction grating through the projection lens (40), are reflected and diffracted thereby, and then are transferred to said first diffraction grating (15) through the projection lens (40).
Claim 61
Dependent Claim 49 words
The method according to claim 43, charac­terized in that said third and fourth light beams have each two components, respectively, which are divided from said first and second light beams (20, 21), after said first and second light beams (20, 21) have been transferred to the first grating (51).
Claim 62
Dependent Claim 34 words
The method according to claim 58, charac­terized in that said two components are those components of said first and second light beams (20, 21) which have been reflected by said first diffraction grating (15).
Claim 63
Dependent Claim 66 words
The method according to claim 58, charac­terized in that said two light beams of the specified same order travel in a first path until they reach said first sensor means (33), and said two components travel in a second path until they reach said second sensor means (36), and said first and second paths are located close to each other and are substantially equal in length.
Claim 64
Dependent Claim 36 words
The method according to claim 43, charac­terized in that said third and fourth light beams have each two beams of the same order other than the spe­cified order of said at least twice diffracted light beams.
Claim 65
Dependent Claim 102 words
The method according to claim 61, charac­terized in that said first diffraction grating (51) has a one-dimensional pattern consisting of stripes extending parallel to a y axis, and said second diffrac­tion grating (52) has a one-dimensional pattern con­sisting of stripes extending parallel to an x axis intersecting with the y axis at right angles, said at least twice diffracted light beams are nth in the x axis and rth in the y axis and, thus, represented as (n, r), where n and r are integers; and said two beams of same order other than the specified order are of (0, r) order.
Claim 66
Dependent Claim 142 words
The method according to claim 61, charac­terized in that said first diffraction grating (51) is a light-permeating one, said second diffraction grating (52) is a light-reflecting one, so that said first and second light beams pass through said first diffraction grating (51) and diffracted thereby, are reflected and diffracted by said second diffraction grating (52), and then pass through said first diffraction grating and diffracted by it, whereby said first light beam (20) is changed into thrice diffracted light beams having the frequency f1, and said second light beam (21) is changed into thrice diffracted light beams having the frequency f2; said at least twice diffracted light beams include these thrice diffracted light beams; and said two beams of same order other than the specified order are of the predetermined order which is identical to that of said thrice diffracted light beams.
Claim 67
Dependent Claim 101 words
The method according to claim 61, charac­terized in that said first and second light beams (20, 21) are applied to said second diffraction grating (52) through a projection lens (40) located between said first and second objects (12, 13) after said first and second light beams have been diffracted by said first diffraction grating (51), whereby said diffraction grat­ing converts said first and second light beams (20, 21) into twice diffracted light beams having frequencies f1 and f2; and said two beams of same order other than the specified order are of the same order as these twice diffracted light beams.
Claim 68
Dependent Claim 73 words
The method according to claim 61, charac­terized in that said two light beams of the specified order travel in a first path until they reach said first sensor means (33), said two beams of the same order other than the specified order travel in a second path until they reach said second sensor means (36), and said first and second paths are located close to each other and are substantially equal in length.
Claim 69
Dependent Claim 103 words
The method according to claim 43, charac­terized in that said third and fourth light beams have each two components, respectively, which are divided from said first and second light beams (20, 21) before said first and second light beams are transferred to said first diffraction grating (51); said two light beams of the specified same order travel in a first path until they reach said first sensor means (33); said two components travel in a second path until they reach said second sensor means (36); and said first and second paths are located close to each other and are substan­tially equal in length.
Claim 70
Independent Claim 437 words
An apparatus for setting a gap between first and second objects opposing each other, said first object (13) having a first diffraction grating (51) formed on that surface which opposes said second object (12), and said second object (12) having a second diffraction grating (52) formed on that surface which opposes said first object (13), said apparatus charac­terized by comprising: light source means for emitting from a light source (17) a first light beam having a frequency f1 and a second light beam having a frequency f2, where f1 is not equal to f2; first light-applying means for applying the first and second light beams (20, 21) onto one of first and second diffraction gratings (51, 52) so that the first and second light beams (20, 21) interfere with each other and are diffracted by the first diffraction grating (51) and a second diffraction grating (52), whereby the first light beam (20) is changed into at least twice diffracted light beams having the frequency f1, and the second light beam (21) is changed into at least twice diffracted light beams having frequency f2, two beams of arbitrary same order of the diffracted light beams which have frequencies f1 and f2 and are interfering each other, and two beams of specified same order of the diffracted light beams which have frequen­cies f1 and f2 and a phase shift φ G which corresponds to a gap between the first and second objects (12, 13); first sensor means (33) for detecting and con­verting, the two light beams of the specified same order into a beat signal, i.e., a detection signal (53) having a frequency Δf (= |f2-f1|) and the phase shift φ G : second light-applying means for applying a third light beam having the frequency f1 and being in phase with the first light beam, and a fourth light beam having frequency f2, being in phase with the second light beam, and interfering with the third light beam; second sensor means (36) for detecting and convert­ing, by a second sensor means, said third and fourth light beams into a beat signal, i.e., a reference signal (37) having a frequency Δf (= |f2-f1|); calculator means (38) for calculating a phase dif­ference between the detection signal (53) and the reference signal (37), thereby to determine the phase shift φ G and thus the displacement between said first and second objects (12, 13); and gap-adjusting means (54) for moving said first and second objects (12, 13) relative to each other in accor­dance with the gap, thereby to set the gap between said first and second objects (12, 13) to a desired value.
Claim 71
Independent Claim 437 words
An apparatus for setting a gap between first and second objects opposing each other, said first object (13) having a first diffraction grating (51) formed on that surface which opposes said second object (12), and said second object (12) having a second diffraction grating (52) formed on that surface which opposes said first object (13), said apparatus charac­terized by comprising: light source means for emitting from a light source (17) a first light beam having a frequency f1 and a second light beam having a frequency f2, where f1 is not equal to f2; first light-applying means for applying the first and second light beams (20, 21) onto one of first and second diffraction gratings (51, 52) so that the first and second light beams (20, 21) interfere with each other and are diffracted by the first diffraction grating (51) and a second diffraction grating (52), whereby the first light beam (20) is changed into at least twice diffracted light beams having the frequency f1, and the second light beam (21) is changed into at least twice diffracted light beams having frequency f2, two beams of arbitrary same order of the diffracted light beams which have frequencies f1 and f2 and are interfering each other, and two beams of specified same order of the diffracted light beams which have frequen­cies f1 and f2 and a phase shift φ G which corresponds to a gap between the first and second objects (12, 13); first sensor means (33) for detecting and con­verting, the two light beams of the specified same order into a beat signal, i.e., a detection signal (53) having a frequency Δf (= |f2-f1|) and the phase shift φ G : second light-applying means for applying a third light beam having the frequency f1 and being in phase with the first light beam, and a fourth light beam having frequency f2, being in phase with the second light beam, and interfering with the third light beam; second sensor means (36) for detecting and convert­ing, by a second sensor means, said third and fourth light beams into a beat signal, i.e., a reference signal (37) having a frequency Δf (= |f2-f1|); calculator means (38) for calculating a phase dif­ference between the detection signal (53) and the reference signal (37), thereby to determine the phase shift φ G and thus the displacement between said first and second objects (12, 13); and gap-adjusting means (54) for moving said first and second objects (12, 13) relative to each other in accor­dance with the gap, thereby to set the gap between said first and second objects (12, 13) to a desired value.
Claim 72
Dependent Claim 26 words
The apparatus according to claim 67, charac­terized in that said first object is an exposure mask (13), and said second object is a semiconductor wafer (12).
Claim 73
Dependent Claim 25 words
The apparatus according to claim 67, charac­terized in that said first diffraction grating (51) has a one-dimensional pattern consisting of a plurality of parallel stripes.
Claim 74
Dependent Claim 18 words
The apparatus according to claim 69, charac­terized in that said second diffraction grating (52) has a one-dimensional pattern.
Claim 75
Dependent Claim 43 words
The apparatus according to claim 69, charac­terized in that said second diffraction grating (52) has a two-dimensional pattern consisting of a first set of parallel stripes and a second set of parallel stripes intersecting at right angles with strips of the first set.
Claim 76
Dependent Claim 48 words
The apparatus according to claim 70, charac­terized in that the stripes of said one-dimensional pat­tern (51) extend parallel to the y axis, and said second diffraction grating (52) is arranged such that the stri­pes extend parallel to the x axis intersecting with the y axis at right angles.
Claim 77
Dependent Claim 58 words
The apparatus according to claim 72, charac­terized in that the orders of said at least twice diffracted light beams are nth in the x axis and rth in the y axis and, thus, represented as (n, r), where n and r are integers; and said two light beams of the spe­cified same order are of (n, ±1) order.
Claim 78
Dependent Claim 118 words
The apparatus according to claim 72, charac­terized in that said first diffraction grating (51) is a light-permeating one, said second diffraction grating (52) is a light-reflecting one, so that said first and second light beams (20, 21) pass through said first diffraction grating (51) and diffracted thereby, are reflected and diffracted by said second diffraction grating (52), asnd then pass through said first diffrac­tion grating (51) and diffracted by it, whereby said first light beam (20) is changed into thrice diffracted light beams having the frequency f1, and said second light beam (21) is changed into thrice diffracted light beams having the frequency f2; and said at least twice diffracted light beams include these thrice diffracted light beams.
Claim 79
Dependent Claim 117 words
The apparatus according to claim 73, characterized in that said first light-applying means includes a means for applying said first and second light beams (20, 21) to a point (31) on said first diffraction grating (51), said beams extending in a second plane (102), being symmetrical with respect to a line (28), and inclining to the line (28) at angle ±α, said second plane (102) inclining at angle β to a first plane (101) extending at right angles to the y axis, said line (28) extending in the second plane (102) and at right angles to the x axis, and the point (31) being a intersection point which the line (28) intersect with the first grating (51).
Claim 80
Dependent Claim 52 words
The apparatus according to claim 75, charac­terized in that said angle ±α is sin⁻¹(±m₀λ/Px), where m₀ is an integer, λ is the standard wavelength of said first and second light beams, and Px is a pitch at which the strips of said first diffraction grating (51) are arranged in the x axis.
Claim 81
Dependent Claim 14 words
The apparatus according to claim 75, charac­terized in that said angle β is 0°.
Claim 82
Dependent Claim 48 words
The apparatus according to claim 75, charac­terized in that the stripes of said first diffraction grating (51) are spaced apart in the x axis at regular intervals, and the stripes of said second diffraction grating (52) are spaced apart in the y axis at the same regular intervals.
Claim 83
Dependent Claim 92 words
The apparatus according to claim 78, charac­terized in that said thrice diffracted light beams have orders nth order in the x axis and rth in the y axis, i.e., (n, r) order, where n and r are integers, said orders being defined with respect to an origin (0, 0) which is a point on an z′ axis extending in a third plane (103) which is symmetrical to the first plane (101) with respect to the second plane (102); and said two light beams of the specified same order have (n, ±1) order.
Claim 84
Dependent Claim 55 words
The apparatus according to claim 67, characterized in that said first and second light beams (20, 21) are applied to said second diffraction grating (52) through a projection lens (40) located between said first and second objects (12, 13), after said first and second light beams have been diffracted by said first diffraction grating (51).
Claim 85
Dependent Claim 65 words
The apparatus according to claim 67, charac­terized in that a projection lens (40) is located bet­ween said first and second objects (12, 13), so that the first and second light beams (20, 21) are applied to said second diffraction grating through the projection lens (40), are reflected and diffracted thereby, and then are transferred to said first diffraction grating (15) through the projection lens (40).
Claim 86
Dependent Claim 49 words
The apparatus according to claim 67, charac­terized in that said third and fourth light beams have each two components, respectively, which are divided from said first and second light beams (20, 21), after said first and second light beams (20, 21) have been transferred to the first grating (51).
Claim 87
Dependent Claim 32 words
The apparatus according to claim 82, wherein said two components are those components of said first and second light beams (20, 21) which have been reflected by said first diffraction grating (15).
Claim 88
Dependent Claim 66 words
The apparatus according to claim 82, charac­terized in that said two light beams of the specified same order travel in a first path until they reach said first sensor means (33), and said two components travel in a second path until they reach said second sensor means (36), and said first and second paths are located close to each other and are substantially equal in length.
Claim 89
Dependent Claim 36 words
The apparatus according to claim 67, charac­terized in that said third and fourth light beams have each two beams of the same order other than the spe­cified order of said at least twice diffracted light beams.
Claim 90
Dependent Claim 102 words
The apparatus according to claim 85, charac­terized in that said first diffraction grating (51) has a one-dimensional pattern consisting of stripes extend­ing parallel to a y axis, and said second diffraction grating (52) has a one-dimensional pattern consisting of stripes extending parallel to an x axis intersecting with the y axis at right angles, said at least twice diffracted light beams are nth in the x axis and rth in the y axis and, thus, represented as (n, r), where n and r are integers; and said two beams of same order other than the specified order are of (0, r) order.
Claim 91
Dependent Claim 143 words
The apparatus according to claim 85, charac­terized in that said first diffraction grating (51) is a light-permeating one, said second diffraction grating (52) is a light-reflecting one, so that said first and second light beams pass through said first diffraction grating (51) and diffracted thereby, are reflected and diffracted by said second diffraction grating (52), and then pass through said first diffraction grating (51) and diffracted by it, whereby said first light beam (20) is changed into thrice diffracted light beams having the frequency f1, and said second light beam (21) is changed into thrice diffracted light beams having the frequency f2; said at least twice diffracted light beams include these thrice diffracted light beams; and said two beams of same order other than the specified order are of the predetermined order which is identical to that of said thrice diffracted light beams.
Claim 92
Dependent Claim 101 words
The apparatus according to claim 85, charac­terized in that said first and second light beams (20, 21) are applied to said second diffraction grating (52) through a projection lens (40) located between said first and second objects (12, 13), after said first and second light beams have been diffracted by said first diffraction grating (51), whereby said diffraction grating converts said first and second light beams (20, 21) into twice diffracted light beams having frequencies f1 and f2; and said two beams of same order other than the specified order are of the same order as these twice diffracted light beams.
Claim 93
Dependent Claim 73 words
The apparatus according to claim 85, charac­terized in that said two light beams of the specified order travel in a first path until they reach said first sensor means (33), said two beams of the same order other than the specified order travel in a second path until they reach said second sensor means (36), and said first and second paths are located close to each other and are substantially equal in length.
Claim 94
Dependent Claim 103 words
The apparatus according to claim 67, charac­terized in that said third and fourth light beams have each two components, respectively, which are divided from said first and second light beams (20, 21) before said first and second light beams are transferred to said first diffraction grating (51); said two light beams of the specified same order travel in a first path until they reach said first sensor means (33); said two components travel in a second path until they reach said second sensor means (36); and said first and second paths are located close to each other and are substan­tially equal in length.
Claim 95
Independent Claim 554 words
A method of aligning first and second objects opposing each other, and also setting a gap between first and second objects opposing each other, said first object (13) having a first diffraction grating (71) formed on that surface which opposes said second object (12), and said second object (12) having a second diffraction grating (72) formed on that surface which opposes said first object (13), said method charac­terized by comprising the steps of: emitting from a light source (17) a first light beam (20) having a frequency f1 and a second light beam (21) having a frequency f2, where f1 is not equal to f2; applying the first and second light beams (20, 21) onto one of first and second diffraction gratings (15, 16) so that the first and second light beams interfere with each other and are diffracted by the first diffrac­tion grating (71) and a second diffraction grating (72), whereby the first light beam (20) is changed into at least twice diffracted light beams having the frequency f1, and the second light beam (21) is changed into at least twice diffracted light beams having frequency f2, two beams of arbitrary same order of the diffracted light beams which have frequencies f1 and f2 and are interfering each other, two beams of first specified same order of the diffracted light beams which have fre­quencies f1 and f2 and a phase shift φ A which corre­sponds to a displacement between the first and second objects (12, 13), and two beams of second specified same order of the diffracted light beams which have frequen­cies f1 and f2 and a phase shift φ G which corresponds to a gap between the first and second objects (12, 13); detecting and converting, by a first sensor means (33A), the two light beams of the first specified same order into a beat signal, i.e., a displacement detection signal (81A) having a frequency Δf (= |f2-f1|) and the phase shift φ A ; detecting and converting, by a second sensor means (33G), the two light beams of the second specified same order into a beat signal, i.e., a gap detection signal (81G) having a frequency Δf (= |f2-f1|) and the phase shift φ G ; applying a third light beam having the frequency f1 and being in phase with the first light beam, and a fourth light beam having frequency f2, being in phase with the second light beam, and interfering with the third light beam; detecting and converting, by a third sensor means (36), said third and fourth light beams into a beat signal, i.e., a reference signal (37) having a frequency Δf (= |f2-f1|); calculating a phase difference between the dis­placement detection signal (81A) and the reference signal (37), thereby to determine the phase shift φ A and thus the displacement between said first and second objects (12, 13); calculating a phase difference between the gap detection signal (81G) and the reference signal (37), thereby to determine the phase shift φ G and thus the displacement between said first and second objects (12, 13); and adjusting said first and second objects relative to each other in accordance with the displacement and the gap, thereby to align said first and second objects (12, 13) with respect to each other, and also to set the gap to a desired value.
Claim 96
Independent Claim 554 words
A method of aligning first and second objects opposing each other, and also setting a gap between first and second objects opposing each other, said first object (13) having a first diffraction grating (71) formed on that surface which opposes said second object (12), and said second object (12) having a second diffraction grating (72) formed on that surface which opposes said first object (13), said method charac­terized by comprising the steps of: emitting from a light source (17) a first light beam (20) having a frequency f1 and a second light beam (21) having a frequency f2, where f1 is not equal to f2; applying the first and second light beams (20, 21) onto one of first and second diffraction gratings (15, 16) so that the first and second light beams interfere with each other and are diffracted by the first diffrac­tion grating (71) and a second diffraction grating (72), whereby the first light beam (20) is changed into at least twice diffracted light beams having the frequency f1, and the second light beam (21) is changed into at least twice diffracted light beams having frequency f2, two beams of arbitrary same order of the diffracted light beams which have frequencies f1 and f2 and are interfering each other, two beams of first specified same order of the diffracted light beams which have fre­quencies f1 and f2 and a phase shift φ A which corre­sponds to a displacement between the first and second objects (12, 13), and two beams of second specified same order of the diffracted light beams which have frequen­cies f1 and f2 and a phase shift φ G which corresponds to a gap between the first and second objects (12, 13); detecting and converting, by a first sensor means (33A), the two light beams of the first specified same order into a beat signal, i.e., a displacement detection signal (81A) having a frequency Δf (= |f2-f1|) and the phase shift φ A ; detecting and converting, by a second sensor means (33G), the two light beams of the second specified same order into a beat signal, i.e., a gap detection signal (81G) having a frequency Δf (= |f2-f1|) and the phase shift φ G ; applying a third light beam having the frequency f1 and being in phase with the first light beam, and a fourth light beam having frequency f2, being in phase with the second light beam, and interfering with the third light beam; detecting and converting, by a third sensor means (36), said third and fourth light beams into a beat signal, i.e., a reference signal (37) having a frequency Δf (= |f2-f1|); calculating a phase difference between the dis­placement detection signal (81A) and the reference signal (37), thereby to determine the phase shift φ A and thus the displacement between said first and second objects (12, 13); calculating a phase difference between the gap detection signal (81G) and the reference signal (37), thereby to determine the phase shift φ G and thus the displacement between said first and second objects (12, 13); and adjusting said first and second objects relative to each other in accordance with the displacement and the gap, thereby to align said first and second objects (12, 13) with respect to each other, and also to set the gap to a desired value.
Claim 97
Dependent Claim 26 words
The method according to claim 91, charac­terized in that said first object is an exposure mask (13), and said second object is a semiconductor wafer (12).
Claim 98
Dependent Claim 25 words
The method according to claim 91, charac­terized in that said first diffraction grating (71) has a one-dimensional pattern consisting of a plurality of parallel stripes.
Claim 99
Dependent Claim 24 words
The method according to claim 93, charac­terized in that said second diffraction grating (72) has a checkered pattern (72-1) and a one-dimensional pat­tern (72-2).
Claim 100
Dependent Claim 44 words
The method according to claim 93, charac­terized in that said second diffraction grating (72) has a two-dimensional pattern consisting of a first set of parallel stripes and a second set of parallel stripes intersecting at right angles with the strips of the first set.
Claim 101
Dependent Claim 84 words
The method according to claim 94, charac­terized in that said first and second objects (12, 13) are moved relative to each other in an x axis, said first diffraction grating (71) is arranged such that said stripes extend parallel to a y axis intersecting at right angles with the x axis and existing in the same plane as the x axis, and said second diffraction grating (72) is arranged such that the stripes of said one-­dimensional pattern (72-2) extend parallel to the x axis.
Claim 102
Dependent Claim 167 words
The method according to claim 96, charac­terized in that the at least twice diffracted light beams includes light beams diffracted by said first diffraction grating (71) and the checkered pattern (72-1) of said second diffraction grating (72) and used for detecting the displacement, and light beams diffracted by said first diffraction grating (71) and the one-dimensional pattern (72-2) of said second diffraction grating (72) and used for detecting the gap; said diffracted light beams used for detecting the displacement and the gap are of nth order in the x axis and rth order in the y axis and, thus, represented as (n, r), where n and r are integers; said two light beams of the first specified same order are of (0, r) order which is identical to that of the diffracted light beams for detecting the displacement; and said two light beams of the second specified same order are of (n, ±1) order which is identical to that of the diffracted beams for detecting the gap.
Claim 103
Dependent Claim 257 words
The method according to claim 96, charac­terized in that said first diffraction grating (71) is a light-permeating one, said second diffraction grating (72) is a light-reflecting one having a checkered pat­tern (72-1), so that said first and second light beams (20, 21) pass through said first diffraction grating (71) and diffracted thereby, are reflected and diffract­ed by said second diffraction grating (72), and then pass through said first diffraction grating (71) and diffraction by it, whereby said first light beam (20) is changed into thrice diffracted light beams of frequency f1 for detecting the displacement, and said second light beam (21) is changed into thrice diffracted light beams of frequency f2 for detecting the displacement; and said at least twice diffracted light beams include two thrice diffracted light beams for detecting the displacement; said first diffraction grating (7) is a light-­permeating one, said second diffraction grating (72) is a light-reflecting one having a one-dimensional pattern (72-1), so that said first and second light beams (20, 21) pass through said first diffraction grating (71) and diffracted thereby, are reflected and diffracted by said second diffraction grating (72), and then pass through said first diffraction grating (71) and diffracted by it, whereby said first light beam (20) is changed into thrice diffracted light beams of frequency f1 for detecting the gap, and said second light beam (21) is changed into thrice diffracted light beams of frequency f2 for detecting the gap; and said at least twice diffracted light beam include two thrice diffracted light beams for detecting the gap.
Claim 104
Dependent Claim 110 words
The method according to claim 98, charac­terized in that said first and second light beams (20, 21) are applied to a point (31) on said first diffrac­tion grating (71), said beams extending in a second plane (102), being symmetrical with respect to a line (28), and inclining to the line (28) at angle ±α, said second plane (102) inclining at angle β to a first plane (101) extending at right angles to the y axis, said line (28) extending in the second plane (102) and at right angles to the x axis, and the point (31) being a inter­section point which the line (28) intersects with the first grating (71).
Claim 105
Dependent Claim 54 words
The method according to claim 99, charac­terized in that said angle ±α is sin⁻¹(±m₀λ/Px), where m₀ is an integer, λ is the standard wavelength of said first and second light beams (20, 21), and Px is a pitch at which the strips of said first diffraction grating (71) are arranged in the x axis.
Claim 106
Dependent Claim 14 words
The method according to claim 99, charac­terized in that said angle β is 0°.
Claim 107
Dependent Claim 119 words
The method according to claim 99, charac­terized in that the stripes of said first diffraction grating (71) are spaced apart in the x axis at regular intervals, and the squares of said checkered pattern (72-1) of said second diffraction grating (72) are spaced apart in the x axis at the same regular intervals as the stripes of the first diffraction grating (71); and those squares of said checkered pattern (72-1) of said second diffraction grating (72) are spaced apart in the y axis at regular intervals, and the stripes of the one-dimensional pattern (72-2) of said second diffrac­tion grating (72) are spaced apart in the y axis at dif­ferent regular intervals from the squares of said checkered pattern (72-1).
Claim 108
Dependent Claim 144 words
The method according to claim 99, charac­terized in that said thrice diffracted light beams of two kinds have orders nth order in the x axis and rth in the y axis, i.e., (n, r) order, where n and r are inte­gers, said orders being defined with respect to an ori­gin (0, 0) which is a point on an z′ axis extending in a third plane (103) which is symmetrical to the first plane (101) with respect to the second plane (102); said two light beams of the first specified same order are of the (0, r) order which is identical to that of said thrice diffracted light beams for detecting the dis­placement; and said two light beams of the second spe­cified same order are of the (n, ±1) order which is identical to that of said thrice diffracted light beams for detecting the gap.
Claim 109
Dependent Claim 55 words
The method according to claim 91, charac­terized in that said first and second light beams (20, 21) are applied to said second diffraction grating (72) through a projection lens (40) located between said first and second objects (12, 13), after said first and second light beams have been diffracted by said first diffraction grating (71).
Claim 110
Dependent Claim 66 words
The method according to claim 91, charac­terized in that a projection lens (40) is located bet­ween said first and second objects (12, 13), so that the first and second light beams (20, 21) are applied to said second diffraction grating (72) through the projec­tion lens (40), are reflected and diffracted thereby, and then are transferred to said first diffraction grating (71) through the projection lens (40).
Claim 111
Dependent Claim 48 words
The method according to claim 91, charac­terized in that said third and fourth light beams have each two components, respectively, which are divided from said first and second light beams (20, 21), after said first and second light beams (20, 21) have been transferred to the first grating.
Claim 112
Dependent Claim 34 words
The method according to claim 106, charac­terized in that said two components are those components of said first and second light beams (20, 21) which have been reflected by said first diffraction grating (15).
Claim 113
Dependent Claim 90 words
The method according to claim 106, charac­terized in that said two light beams of the first spe­cified same order travel in a first path until they reach said first sensor means (33A), said two light beams of the second specified same order travel in a second path until they reach said second sensor means (33G), said two components travel in a third path until they reach said third sensor means (36), and said first, second, and second paths are located close to one another and are substantially equal in length.
Claim 114
Dependent Claim 39 words
The method according to claim 91, charac­terized in that said third and fourth light beams have each two beams of the same order other than the first and second specified order of said at least twice diffracted light beams.
Claim 115
Dependent Claim 103 words
The method according to claim 109, charac­terized in that said first diffraction grating (71) has a one-dimensional pattern consisting of stripes extending parallel to a y axis, and said second diffrac­tion grating (72) has a one-dimensional pattern (72-2) consisting of stripes extending parallel to an x axis intersecting with the y axis at right angles, said at least twice diffracted light beams are nth in the x axis and rth in the y axis and, thus, represented as (n, r), where n and r are integers; and said two beams of same order other than the specified order are of (0, r) order.
Claim 116
Dependent Claim 142 words
The method according to claim 109, charac­terized in that said first diffraction grating (71) is a light-permeating one, said second diffraction grating (72) is a light-reflecting one, so that said first and second light beams (20, 21) pass through said first diffraction grating (71) and diffracted thereby, are reflected and diffracted by said second diffraction grating (72), and then pass through said first diffrac­tion grating and diffracted by it, whereby said first light beam is changed into thrice diffracted light beams having the frequency f1, and said second light beam is changed into thrice diffracted light beams having the frequency f2; said at least twice diffracted light beams include these thrice diffracted light beams; and said two beams of same order other than the specified order are of the predetermined order which is identical to that of said thrice diffracted light beams.
Claim 117
Dependent Claim 100 words
The method according to claim 109, charac­terized in that said first and second light beams are applied to said second diffraction grating (72) through a projection lens (40) located between said first and second objects (12, 13), after said first and second light beams have been diffracted by said first diffrac­tion grating (71), whereby said diffraction grating (71) converts said first and second light beams (20, 21) into twice diffracted light beams having frequencies f1 and f2; and said two beams of same order other than the spe­cified order are of the same order as these twice diffracted light beams.
Claim 118
Dependent Claim 97 words
The method according to claim 109, charac­terized in that said two light beams of the first spe­cified order travel in a first path until they reach said first sensor means (33A), said two light beams of the second specified order travel in a second path until they reach said second sensor means (33G), said two beams of the same order other than the specified order travel in a third path until they reach said third sen­sor means (36), and said first, second, and second paths are located close to one other and are substantially equal in length.
Claim 119
Dependent Claim 129 words
The method according to claim 91, charac­terized in that said third and fourth light beams have each two components, respectively, which are divided from said first and second light beams (20, 21) before said first and second light beams (20, 21) are trans­ferred to said first diffraction grating; said two light beams of the first specified same order travel in a first path until they reach said first sensor means (33A), said two light beams of the second specified same order travel in a second path until they reach said second sensor means (33G), said two components travel in a third path until they reach said third sensor means (36); and said first, second, and second paths are located close to one other and are substantially equal in length.
Claim 120
Independent Claim 573 words
An apparatus for aligning first and second objects opposing each other, and also setting a gap between first and second objects opposing each other, said first object (13) having a first diffraction grating (71) formed on that surface which opposes said second object (12), and said second object (12) having a second diffraction grating (72) formed on that surface which opposes said first object (13), said apparatus characterized by comprising: light source means (17) for emitting from a light source a first light beam (20) having a frequency f1 and a second light beam (21) having a frequency f2, where f1 is not equal to f2; first light-applying means for applying the first and second light beams (20, 21) onto one of first and second diffraction gratings (15, 16) so that the first and second light beams interfere with each other and are diffracted by the first diffraction grating (71) and a second diffraction grating (72), whereby the first light beam (20) is changed into at least twice diffracted light beams having the frequency f1, and the second light beam (21) is changed into at least twice diffract­ed light beams having frequency f2, two beams of arbi­trary same order of the diffracted light beams which have frequencies f1 and f2 and are interfering each other, two beams of first specified same order of the diffracted light beams which have frequencies f1 and f2 and a phase shift φ A which corresponds to a displacement between the first and second objects (12, 13), and two beams of second specified same order of the diffracted light beams which have frequencies f1 and f2 and a phase shift φ G which corresponds to a gap between the first and second objects (12, 13); first sensor means (33A) for detecting and con­verting the two light beams of the first specified same order into a beat signal, i.e., a displacement detection signal (81A) having a frequency Δf (= |f2-f1|) and the phase shift φ A ; second sensor means (33G) for detecing and con­verting the two light beams of the second specified same order into a beat signal, i.e., a gap detection signal (81G) having a frequency Δf (= |f2-f1|) and the phase shift φ G ; second light-applying means for applying a third light beam having the frequency f1 and being in phase with the first light beam, and a fourth light beam having frequency f2, being in phase with the second light beam, and interfering with the third light beam; third sensor means (36) for detecting and convert­ing said third and fourth light beams into a beat signal, i.e., a reference signal (37) having a frequency Δf (= |f2-f1|); calculator means (38A) for calculating a phase dif­ference between the displacement detection signal (81A) and the reference signal (37), thereby to determine the phase shift φ A and thus the displacement between said first and second objects (12, 13); calculator means (38G) for calculating a phase dif­ference between the gap detection signal (81G) and the reference signal (37), thereby to determine the phase shift φ G and thus the displacement between said first and second objects (12, 13); and position-adjusting means (39, 54) for moving said first and second objects relative to each other in accordance with the displacement and the gap, thereby to align said first and second objects (12, 13) with respect to each other, and also to set the gap to a desired value.
Claim 121
Independent Claim 573 words
An apparatus for aligning first and second objects opposing each other, and also setting a gap between first and second objects opposing each other, said first object (13) having a first diffraction grating (71) formed on that surface which opposes said second object (12), and said second object (12) having a second diffraction grating (72) formed on that surface which opposes said first object (13), said apparatus characterized by comprising: light source means (17) for emitting from a light source a first light beam (20) having a frequency f1 and a second light beam (21) having a frequency f2, where f1 is not equal to f2; first light-applying means for applying the first and second light beams (20, 21) onto one of first and second diffraction gratings (15, 16) so that the first and second light beams interfere with each other and are diffracted by the first diffraction grating (71) and a second diffraction grating (72), whereby the first light beam (20) is changed into at least twice diffracted light beams having the frequency f1, and the second light beam (21) is changed into at least twice diffract­ed light beams having frequency f2, two beams of arbi­trary same order of the diffracted light beams which have frequencies f1 and f2 and are interfering each other, two beams of first specified same order of the diffracted light beams which have frequencies f1 and f2 and a phase shift φ A which corresponds to a displacement between the first and second objects (12, 13), and two beams of second specified same order of the diffracted light beams which have frequencies f1 and f2 and a phase shift φ G which corresponds to a gap between the first and second objects (12, 13); first sensor means (33A) for detecting and con­verting the two light beams of the first specified same order into a beat signal, i.e., a displacement detection signal (81A) having a frequency Δf (= |f2-f1|) and the phase shift φ A ; second sensor means (33G) for detecing and con­verting the two light beams of the second specified same order into a beat signal, i.e., a gap detection signal (81G) having a frequency Δf (= |f2-f1|) and the phase shift φ G ; second light-applying means for applying a third light beam having the frequency f1 and being in phase with the first light beam, and a fourth light beam having frequency f2, being in phase with the second light beam, and interfering with the third light beam; third sensor means (36) for detecting and convert­ing said third and fourth light beams into a beat signal, i.e., a reference signal (37) having a frequency Δf (= |f2-f1|); calculator means (38A) for calculating a phase dif­ference between the displacement detection signal (81A) and the reference signal (37), thereby to determine the phase shift φ A and thus the displacement between said first and second objects (12, 13); calculator means (38G) for calculating a phase dif­ference between the gap detection signal (81G) and the reference signal (37), thereby to determine the phase shift φ G and thus the displacement between said first and second objects (12, 13); and position-adjusting means (39, 54) for moving said first and second objects relative to each other in accordance with the displacement and the gap, thereby to align said first and second objects (12, 13) with respect to each other, and also to set the gap to a desired value.
Claim 122
Dependent Claim 26 words
The apparatus according to claim 115, charac­terized in that said first object is an exposure mask (13), and said second object is a semiconductor wafer (12).
Claim 123
Dependent Claim 25 words
The apparatus according to claim 115, charac­terized in that said first diffraction grating (71) has a one-dimensional pattern consisting of a plurality of parallel stripes.
Claim 124
Dependent Claim 24 words
The apparatus according to claim 117, charac­terized in that vsaid second diffraction grating (72) has a checkered pattern (72-1) and a one-dimensional pattern (72-2).
Claim 125
Dependent Claim 44 words
The apparatus according to claim 117, charac­terized in that said second diffraction grating (72) has a two-dimensional pattern consisting of a first set of parallel stripes and a second set of parallel stripes intersecting at right angles with the strips of the first set.
Claim 126
Dependent Claim 84 words
The apparatus according to claim 118, charac­terized in that said first and second objects (12, 13) are moved relative to each other in an x axis, said first diffraction grating (71) is arranged such that said stripes extend parallel to a y axis intersecting at right angles with the x axis and existing in the same plane as the x axis, and said second diffraction grating (72) is arranged such that the stripes of said one-­dimensional pattern (72-2) extend parallel to the x axis.
Claim 127
Dependent Claim 166 words
The apparatus according to claim 120, charac­terized in that at least twice diffracted light beams include light beams diffracted by said first diffraction grating (71) and the checkered pattern (72-1) of said second diffraction grating (72) and used for detecting the displacement, and light beams diffracted by said first diffraction grating (71) and the one-dimensional pattern (72-2) of said second diffraction grating (72) and used for detecting the gap; said diffracted light beams used for detecting the displacement and the gap are of nth order in the x axis and rth order in the y axis and, thus, represented as (n, r), where n and r are integers; said two light beams of the first specified same order are of (0, r) order which is identical to that of the diffracted light beams for detecting the displacement; and said two light beams of the second specified same order are of (n, ±1) order which is identical to that of the diffracted beams for detecting the gap.
Claim 128
Dependent Claim 257 words
The apparatus according to claim 120, charac­terized in that said first diffraction grating (71) is a light-permeating one, said second diffraction grating (72) is a light-reflecting one having a checkered pattern (72-1), so that said first and second light beams (20, 21) pass through said first diffraction grating (71) and diffracted thereby, are reflected and diffracted by said second diffraction grating (72), and then pass through said first diffraction grating (71) and diffraction by it, whereby said first light beam (20) is changed into thrice diffracted light beams of frequency f1 for detecting the displacement, and said second light beam (21) is changed into thrice diffracted light beams of frequency f2 for detecting the dis­placement; and said at least twice diffracted light beams include two thrice diffracted light beams for detecting the displacement; said first diffraction grating (71) is a light-­permeating one, said second diffraction grating (72) is a light-reflecting one having a one-dimensional pattern (72-1), so that said first and second light beams (20, 21) pass through said first diffraction grating (71) and diffracted thereby, are reflected and diffracted by said second diffraction grating (72), and then pass through said first diffraction grating (71) and diffracted by it, whereby said first light beam (20) is changed into thrice diffracted light beams of frequency f1 for detecting the gap, and said second light beam (21) is changed into thrice diffracted light beam of frequency f2 for detecting the gap; and said at least twice diffracted light beam include two thrice diffracted light beams for detecting the gap.
Claim 129
Dependent Claim 117 words
The apparatus according to claim 122, charac­terized in that said first light-applying means includes a means for applying said first and second light beams (20, 21) to a point (31) on said first diffraction grating (71), said beams extending in a second plane (102), being symmetrical with respect to a line (28), and inclining to the line (28) at angle ±α, said second plane (102) inclining at angle β to a first plane (101) extending at right angles to the y axis, said line (28) extending in the second plane (102) and at right angles to the x axis, and the point (31) being an intersection point which the line (28) intersect with the first grating (71).
Claim 130
Dependent Claim 55 words
The apparatus according to claim 123, charac­terized in that said angle ±α is sin⁻¹ (±m₀λ/Px), where m₀ is an integer, λ is the standard wavelength of said first and second light beams (20, 21), and Px is a pitch at which the strips of said first diffraction grating (71) are arranged in the x axis.
Claim 131
Dependent Claim 14 words
The apparatus according to claim 123, charac­terized in that said angle β is 0°.
Claim 132
Dependent Claim 119 words
The apparatus according to claim 123, charac­terized in that the stripes of said first diffraction grating (71) are spaced apart in the x axis at regular intervals, and the squares of said checkered pattern (72-1) of said second diffraction grating (72) are spaced apart in the x axis at the same regular intervals as the stripes of the first diffraction grating (71); and those squares of said checkered pattern (72-1) of said second diffraction grating (72) are spaced apart in the y axis at regular intervals, and the stripes of the one-dimensional pattern (72-2) of said second diffrac­tion grating (72) are spaced apart in the y axis at dif­ferent regular intervals from the squares of said checkered pattern (72-1).
Claim 133
Dependent Claim 144 words
The apparatus according to claim 126, charac­terized in that said thrice diffracted light beams of two kinds have orders nth order in the x axis and rth in the y axis, i.e., (n, r) order, where n and r are inte­gers, said orders being defined with respect to an ori­gin (0, 0) which is a point on an z′ axis extending in a third plane (103) which is symmetrical to the first plane (101) with respect to the second plane (102); said two light beams of the first specified same order are of the (0, r) order which is identical to that of said thrice diffracted light beams for detecting the dis­placement; and said two light beams of the second spe­cified same order are of the (n, ±1) order which is identical to that of said thrice diffracted light beams for detecting the gap.
Claim 134
Dependent Claim 55 words
The apparatus according to claim 115, charac­terized in that said first and second light beams (20, 21) are applied to said second diffraction grating (72) through a projection lens (40) located between said first and second objects (12, 13), after said first and second light beams have been diffracted by said first diffraction grating (71).
Claim 135
Dependent Claim 66 words
The apparatus according to claim 115, charac­terized in that a projection lens (40) is located be­tween said first and second objects (12, 13), so that the first and second light beams (20, 21) are applied to said second diffraction grating (72) through the projec­tion lens (40), are reflected and diffracted thereby, and then are transferred to said first diffraction grating (71) through the projection lens (40).
Claim 136
Dependent Claim 48 words
The apparatus according to claim 115, charac­terized in that said third and fourth light beams have each two components, respectively, which are divided from said first and second light beams (20, 21), after said first and second light beams (20, 21) have been transferred to the first grating.
Claim 137
Dependent Claim 34 words
The apparatus according to claim 130, charac­terized in that said two components are those components of said first and second light beams (20, 21) which have been reflected by said first diffraction grating (15).
Claim 138
Dependent Claim 90 words
The apparatus according to claim 130, charac­terized in that said two light beams of the first spe­cified same order travel in a first path until they reach said first sensor means (33A), said two light beams of the second specified order travel in a second path until they reach said same second sensor means (33G), said two components travel in a third path until they reach said third sensor means (36), and said first, second, and second paths are located close to one another and are substantially equal in length.
Claim 139
Dependent Claim 39 words
The apparatus according to claim 115, charac­terized in that said third and fourth light beams have each two beams of the same order other than the first and second specified order of said at least twice diffracted light beams.
Claim 140
Dependent Claim 103 words
The apparatus according to claim 133, charac­terized in that said first diffraction grating (71) has a one-dimensional pattern consisting of stripes extend­ing parallel to a y axis, and said second diffraction grating (72) has a one-dimensional pattern (72-2) con­sisting of stripes extending parallel to an x axis intersecting with the y axis at right angles, said at least twice diffracted light beams are nth in the x axis and rth in the y axis and, thus, represented as (n, r), where n and r are integers; and said two beams of same order other than the specified order are of (0, r) order.
Claim 141
Dependent Claim 142 words
The apparatus according to claim 133, charac­terized in that said first diffraction grating (71) is a light-permeating one, said second diffraction grating (72) is a light-reflecting one, so that said first and second light beams (20, 21) pass through said first diffraction grating (71) and diffracted thereby, are reflected and diffracted by said second diffraction grating (72), and then pass through said first diffrac­tion grating and diffracted by it, whereby said first light beam is changed into thrice diffracted light beams having the frequency f1, and said second light beam is changed into thrice diffracted light beams having the frequency f2; said at least twice diffracted light beams include these thrice diffracted light beams; and said two beams of same order other than the specified order are of the predetermined order which is identical to that of said thrice diffracted light beams.
Claim 142
Dependent Claim 100 words
The apparatus according to claim 133, charac­terized in that said first and second light beams are applied to said second diffraction grating (72) through a projection lens (40) located between said first and second objects (12, 13), after said first and second light beams have been diffracted by said first diffrac­tion grating (71), whereby said diffraction grating (71) converts said first and second light beams (20, 21) into twice diffracted light beams having frequencies f1 and f2; and said two beams of same order other than the spe­cified order are of the same order as these twice diffracted light beams.
Claim 143
Dependent Claim 97 words
The apparatus according to claim 133, charac­terized in that said two light beams of the first spe­cified order travel in a first path until they reach said first sensor means (33A), said two light beams of the second specified order travel in a second path until they reach said second sensor means (33G), said two beams of the same order other than the specified order travel in a third path until they reach said third sen­sor means (36), and said first, second, and second paths are located close to one other and are substantially equal in length.
Claim 144
Dependent Claim 129 words
The apparatus according to claim 115, charac­terized in that said third and fourth light beams have each two components, respectively, which are divided from said first and second light beams (20, 21) before said first and second light beams (20, 21) are trans­ferred to said first diffraction grating; said two light beams of the first specified same order travel in a first path until they reach said first sensor means (33A), said two light beams of the second specified same order travel in a second path until they reach said second sensor means (33G), said two components travel in a third path until they reach said third sensor means (36); and said first, second, and second paths are located close to one other and are substantially equal in length.

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