US5631731A
Expired / Lapsed
US
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Method and apparatus for aerial image analyzer
Assignee: Nikon Precision Inc
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Filing: 1994-03-09
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Granted: 1997-05-20
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Expires: 2014-03-09
Abstract
Abstract A method and apparatus to analyze the aerial image of an optical system using a subwavelength slit. A slit configuration yields a higher signal-to-noise ratio than that achievable with a round aperture. The slit also allows the polarization of the aerial image to be analyzed. In an alternative embodiment a tunneling slit is used. The tunneling slit comprises an optically transparent ridge-like structure mounted to a substrate, the combined structure covered by a thin, planar metal film.
Inventors
- 👤 Michael R. Sogard
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-06 12:52
CPC Classifications
G; G01; G01J; G01J1/00; G01J1/42; G01J1/4257; G01J3/00; G01J3/02; G01J3/04; G01J4/00; G01Q; G01Q60/00; G01Q60/18; G01Q60/22; G03; G03F; G03F7/00; G03F7/70; G03F7/70216; G03F7/70358; G03F7/70483; G03F7/7055; G03F7/70566; G03F7/70591; G03F7/706
Claims Analysis
Total Claims: 43
Claim 1
Independent Claim
100 words
A method for optically analyzing the aerial image formed by an optical projection lithography system having a source of light and a light path, comprising: positioning a slit in a first plane, said first plane proximate an image plane of said optical lithography system, wherein said slit has an equivalent width less than the wavelength of said source of light; moving said slit across and within said first plane, wherein said movement is in a direction perpendicular to the length of said slit; and detecting the intensity of said light transmitted through said slit as a function of slit position.
Claim 2
Independent Claim
100 words
A method for optically analyzing the aerial image formed by an optical projection lithography system having a source of light and a light path, comprising: positioning a slit in a first plane, said first plane proximate an image plane of said optical lithography system, wherein said slit has an equivalent width less than the wavelength of said source of light; moving said slit across and within said first plane, wherein said movement is in a direction perpendicular to the length of said slit; and detecting the intensity of said light transmitted through said slit as a function of slit position.
Claim 3
Dependent Claim
20 words
The method of claim 1, wherein said slit has an equivalent slit length greater than the wavelength of said light.
Claim 4
Dependent Claim
15 words
The method of claim 1, wherein said slit has first and second parallel side walls.
Claim 5
Dependent Claim
40 words
The method of claim 1, wherein said slit has first and second non-parallel side walls, said first and second side walls defining a vee geometry, wherein said light is incident on the slit at a broadest region of the slit.
Claim 6
Dependent Claim
25 words
The method of claim 4, wherein an angle between each side wall and said light path is within the range of 30 to 60 degrees.
Claim 7
Dependent Claim
41 words
The method of claim 1, wherein said slit has first and second non-parallel side walls, said first and second side walls defining an inverted vee geometry, wherein said light is incident on the slit at a narrowest region of the slit.
Claim 8
Dependent Claim
25 words
The method of claim 6, wherein an angle between each side wall and said light path is within the range of 30 to 60 degrees.
Claim 9
Dependent Claim
12 words
The method of claim 1, wherein said slit is a tunneling slit.
Claim 10
Dependent Claim
57 words
The method of claim 8, said tunneling slit comprising: a substrate; a ridge supported by and extending from said substrate; and a metal film overlaying a first surface of said ridge and said substrate, wherein the thickness of the metal film covering the highest portion of said ridge is much less than the wavelength of said light.
Claim 11
Dependent Claim
14 words
The method of claim 9, wherein said ridge is manufactured from optically transparent material.
Claim 12
Dependent Claim
13 words
The method of claim 9, wherein said ridge is manufactured from fluorescent material.
Claim 13
Dependent Claim
15 words
The method of claim 9, wherein said substrate is the surface of a fluorescent detector.
Claim 14
Dependent Claim
12 words
The method of claim 9, wherein said substrate is a light pipe.
Claim 15
Independent Claim
116 words
A method for optically analyzing the aerial image of an optical projection lithography system having a source of light and a light path, comprising: positioning a plurality of slits in a first plane, said first plane proximate an image plane of said optical projection lithography system, wherein each individual slit of said plurality of slits has an equivalent width less than the wavelength of said light; moving said plurality of slits across and within said first plane, wherein said movement is in a direction perpendicular to the lengths of said plurality of slits; and detecting the intensity of said light transmitted through the plurality of slits as a function of position of said plurality of slits.
Claim 16
Independent Claim
116 words
A method for optically analyzing the aerial image of an optical projection lithography system having a source of light and a light path, comprising: positioning a plurality of slits in a first plane, said first plane proximate an image plane of said optical projection lithography system, wherein each individual slit of said plurality of slits has an equivalent width less than the wavelength of said light; moving said plurality of slits across and within said first plane, wherein said movement is in a direction perpendicular to the lengths of said plurality of slits; and detecting the intensity of said light transmitted through the plurality of slits as a function of position of said plurality of slits.
Claim 17
Dependent Claim
33 words
The method of claim 14, wherein the aerial image is characterized by a plurality of features having a particular separation and said plurality of slits is characterized by substantially the same particular separation.
Claim 18
Dependent Claim
18 words
The method of claim 14, wherein each individual slit of said plurality of slits is a tunneling slit.
Claim 19
Dependent Claim
124 words
An aerial image analyzer for performing self metrology of an optical projection lithography system having a source of light and a light path, comprising: a translation stage; a slit plate mounted to said translation stage and positioned in a first plane, said first plane proximate an image plane of said optical projection lithography system, wherein said slit plate contains at least one slit with an equivalent slit width of less than the wavelength of said light; a scanning mechanism coupled to said translation stage, wherein said scanning mechanism translates said slit plate across and within said first plane, said translation direction perpendicular to the length of said slit; and means for detecting the intensity of light in the near field of said slit plate.
Claim 20
Dependent Claim
124 words
An aerial image analyzer for performing self metrology of an optical projection lithography system having a source of light and a light path, comprising: a translation stage; a slit plate mounted to said translation stage and positioned in a first plane, said first plane proximate an image plane of said optical projection lithography system, wherein said slit plate contains at least one slit with an equivalent slit width of less than the wavelength of said light; a scanning mechanism coupled to said translation stage, wherein said scanning mechanism translates said slit plate across and within said first plane, said translation direction perpendicular to the length of said slit; and means for detecting the intensity of light in the near field of said slit plate.
Claim 21
Dependent Claim
15 words
The apparatus as recited in claim 17 wherein said scanning mechanism is a stepper motor.
Claim 22
Dependent Claim
15 words
The apparatus as recited in claim 17 wherein said translation stage is an x-y-z stage.
Claim 23
Dependent Claim
19 words
The apparatus as recited in claim 17 wherein said detecting means comprises a light pipe and a photomultiplier tube.
Claim 24
Dependent Claim
18 words
The apparatus as recited in claim 17 wherein said detecting means comprises a fluorescent material and a detector.
Claim 25
Dependent Claim
26 words
The apparatus of claim 17, wherein at least one slit of said slit plate has an equivalent length of greater than the wavelength of said light.
Claim 26
Dependent Claim
21 words
The apparatus of claim 17, wherein at least one slit of said slit plate has first and second parallel side walls.
Claim 27
Dependent Claim
46 words
The apparatus of claim 17, wherein at least one slit of said slit plate has first and second non-parallel side walls, said first and second side walls defining a vee geometry, wherein said light is incident on the slit at a broadest region of the slit.
Claim 28
Dependent Claim
25 words
The apparatus of claim 24, wherein an angle between each side wall and said light path is within the range of 30 to 60 degrees.
Claim 29
Dependent Claim
47 words
The apparatus of claim 17, wherein at least one slit of said slit plate has first and second non-parallel side walls, said first and second side walls defining an inverted vee geometry, wherein said light is incident on the slit at a narrowest region of the slit.
Claim 30
Dependent Claim
25 words
The apparatus of claim 26, wherein an angle between each side wall and said light path is within the range of 30 to 60 degrees.
Claim 31
Dependent Claim
18 words
The apparatus of claim 17, wherein at least one slit of said slit plate is a tunneling slit.
Claim 32
Dependent Claim
52 words
The apparatus of claim 28, wherein said tunneling slit comprises: a ridge; a substrate coupled to said ridge; and a metal film overlaying a first surface of said ridge and said substrate, wherein the metal film covering the highest portion of said ridge is much less than the wavelength of said light.
Claim 33
Dependent Claim
14 words
The apparatus of claim 29, wherein said ridge is manufactured from optically transparent material.
Claim 34
Dependent Claim
13 words
The apparatus of claim 29, wherein said ridge is manufactured from fluorescent material.
Claim 35
Dependent Claim
15 words
The apparatus of claim 29, wherein said substrate is a surface of a fluorescent detector.
Claim 36
Dependent Claim
12 words
The apparatus of claim 29, wherein said substrate is a light pipe.
Claim 37
Independent Claim
115 words
A method for optically analyzing the aerial image formed by an optical projection lithography system having a reticle, a source of light and a light path, comprising: replacing the reticle with a test pattern; positioning a slit in a first plane, said first plane proximate an aerial image plane of said optical lithography system, wherein said slit has an equivalent width less than the wavelength of said source of light; moving said slit across and within said first plane, wherein said movement is in a direction perpendicular to a long axis of said slit; and detecting the intensity of said light in a near field region of said slit as a function of slit position.
Claim 38
Independent Claim
115 words
A method for optically analyzing the aerial image formed by an optical projection lithography system having a reticle, a source of light and a light path, comprising: replacing the reticle with a test pattern; positioning a slit in a first plane, said first plane proximate an aerial image plane of said optical lithography system, wherein said slit has an equivalent width less than the wavelength of said source of light; moving said slit across and within said first plane, wherein said movement is in a direction perpendicular to a long axis of said slit; and detecting the intensity of said light in a near field region of said slit as a function of slit position.
Claim 39
Dependent Claim
13 words
The method of claim 34, wherein said test pattern is a line pattern.
Claim 40
Dependent Claim
25 words
The method of claim 35, wherein said line pattern is comprised of at least one line oriented parallel to said long axis of said slit.
Claim 41
Independent Claim
94 words
A method for optically analyzing the aerial image formed by an optical projection lithography system having a source of light and a light path, comprising: positioning a slit in a first plane, said first plane proximate an aerial image plane of said optical lithography system; moving said slit across and within said first plane, wherein said movement is in a direction perpendicular to a long axis of said slit; measuring the intensity of evanescent light transmitted by said slit as a function of slit position; and analyzing the intensity profile of said aerial image.
Claim 42
Independent Claim
94 words
A method for optically analyzing the aerial image formed by an optical projection lithography system having a source of light and a light path, comprising: positioning a slit in a first plane, said first plane proximate an aerial image plane of said optical lithography system; moving said slit across and within said first plane, wherein said movement is in a direction perpendicular to a long axis of said slit; measuring the intensity of evanescent light transmitted by said slit as a function of slit position; and analyzing the intensity profile of said aerial image.
Claim 43
Dependent Claim
31 words
The method of claim 37, further comprising the step of measuring the intensity of light transmitted by said slit with a magnetic vector parallel to said long axis of said slit.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 2000-05-19 | 2000-11-18 | 2001-05-20 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2004-05-19 | 2004-11-18 | 2005-05-20 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2008-05-19 | 2008-11-18 | 2009-05-20 | $7700.00 | Window Closed / Lapsed |