Autofocusing system for a projecting exposure apparatus

Claim 2

An autofocusing system usable in a projection exposure apparatus having a projection optical system for projecting a pattern of a first object upon a second object having a light sensitive surface layer, said apparatus comprising: illumination means for illuminating a predetermined pattern of the second object without use of the projection optical system and by use of a light, in a direction which is inclined by a predetermined angle with respect to an optical axis of the projection optical system; an optical system for receiving light reflectively scattered by said predetermined pattern and passed through the projection optical system, said optical system forming an image of said predetermined pattern by use of the received light; light receiving means for photoelectrically converting the image of said predetermined pattern and for producing a signal corresponding to the state of the image of said predetermined pattern; and adjusting means for adjusting the positional relation between an imaging plane of the projection optical system and the second object with respect to the direction of the optical axis of the projection optical system, such that an imaging light from the projection optical system can be focused upon the second object.

Claim 3

An apparatus according to claim 1, wherein said illumination means includes a laser adapted to supply a laser light having a wavelength which is different from that of the imaging light from the projection optical system.

Claim 4

An apparatus according to claim 1, wherein said illumination means is arranged to illuminate said predetermined pattern of the second object in two different directions

Claim 5

An apparatus according to claim 2, wherein said optical system includes an aberration correcting optical arrangement effective to correct any chromatic aberration which may be caused by the projection optical system in relation to the laser light from said laser.

Claim 8

A method according to claim 5, wherein said mark pattern comprises a linear pattern elongated in a direction and wherein said mark pattern is illuminated in a direction perpendicular to the direction of elongation of said linear pattern.

Claim 9

A method according to claim 5, wherein said illumination step includes a first substep for illuminating said mark pattern in a first direction and a second substep for illuminating said mark pattern in a second direction different from the first direction.

Claim 10

A method according to claim 5, wherein, in said image forming step, the light scattered by an edge of said mark pattern is selectively extracted so that an image of the edge of said mark pattern is formed by use of the extracted light.

Claim 11

A method according to claim 5, wherein said illumination step includes: providing a laser adapted to supply a light of a wavelength different from that of light used for the projection exposure; and irradiating said mark pattern with the light from the laser, not by way of the projection optical system and in a direction which is inclined by a predetermined angle with respect to the direction of the optical axis of the projection optical system.

Claim 12

A method according to claim 9, wherein said image forming step includes: selectively applying, to the projection optical system, the light scattered by said mark pattern; directing the light passed through the projection optical system to a chromatic aberration correcting arrangement; and forming the image of said mark pattern by use of the chromatic aberration correcting arrangement.

Claim 15

A projection exposure apparatus for projecting a pattern of an original on a workpiece having a light sensitive surface layer through a projecting optical system, said apparatus comprising: a stage for carrying thereon a workpiece having a pattern formed thereon; illuminating means for illuminating, without using the projection optical system, the pattern of the workpiece by use of light in a direction inclined with respect to an optical axis of the projection optical system; detecting means for detecting an image of the pattern of the workpiece, formed through the projection optical system by light reflectively scattered by the pattern of the workpiece as illuminated by said illuminating means; and adjusting means responsive to a signal from said detecting means, for focusing an image of the pattern of the original as formed through the projection optical system on the workpiece.

Claim 16

A projection exposure apparatus for projecting a pattern of an original on a workpiece having a light sensitive surface layer through a projecting optical system, said apparatus comprising: a stage for carrying thereon a workpiece having a pattern formed thereon; illuminating means for illuminating, without using the projection optical system, the pattern of the workpiece by use of light in a direction inclined with respect to an optical axis of the projection optical system; detecting means for detecting an image of the pattern of the workpiece, formed through the projection optical system by light reflectively scattered by the pattern of the workpiece as illuminated by said illuminating means; and adjusting means responsive to a signal from said detecting means, for focusing an image of the pattern of the original as formed through the projection optical system on the workpiece.

Claim 17

An apparatus according to claim 12, wherein said adjusting means comprises driving means for displacing and focusing said stage in the direction of the optical axis of the projection optical system.

Claim 18

An apparatus according to claim 12, wherein said detecting means is adapted to detect contrast of the image of the pattern and to produce a signal related to the detected contrast.

Claim 19

An apparatus according to claim 12, wherein said detecting means comprises an imaging optical system for refocusing the image of the pattern as formed through the projection optical system on a predetermined image surface, and photoelectirc converting means for photoelectrically converting the refocused image.

Claim 20

An apparatus according to claim 15, wherein said imaging optical system is arranged to form first and second refocused images on first and second image surfaces spaced from each other, wherein said photoelectric converting means includes first photoelectric converting means for photoelectrically converting the refocused image as formed on the first image surface and second photoelectric converting means for photoelectrically converting the refocused image as formed on the second image surface, and wherein said detecting means is arranged such that, when the image of the pattern of the original is refocused with respect to the workpiece, said first and second photoelectric converting means produce different signals.

Claim 21

An apparatus according to claim 15, wherein said illuminating means illuminates the pattern of the workpiece with light having a wavelength different from that of light used for projection of the pattern of the original, and wherein said detecting means further comprises a corrective optical system disposed between the projection optical system and said imaging optical system and being adapted to correct chromatic aberration of the projection optical system with respect to the formation of the image of the pattern.

Claim 22

An apparatus according to claim 17, wherein said detecting means further comprises a mirror disposed between the original and the projection optical system, for reflecting the scattered light from the projection optical system towards said corrective optical system.

Claim 23

An apparatus according to claim 12, wherein said illuminating means comprises a plurality of lasers, providing laser beams for illumination of the pattern of the workpiece.

Claim 24

An apparatus according to claim 19, wherein the pattern of the workpiece is illuminated with the laser beams coming from the opposite sides of the projection optical system.

Claim 25

An apparatus according to claim 12, wherein said illuminating means includes a laser, providing a laser beam having a wavelength different from that of light used for projection of the pattern of the original, and wherein the pattern of the workpiece is illuminated with the laser beam.

Claim 26

An apparatus according to claim 12, wherein said illuminating means illuminates the pattern of the workpiece with a laser beam and wherein, when a numerical aperture of the projection optical system is denoted by NA and an angle of incidence of the laser beam with respect to the workpiece is denoted by B, the following relationship is satisfied: sin.sup.-1 NA+10°≦B.

Claim 29

A method according to claim 23, wherein the step of irradiating the object comprises projecting a laser beam to the object in a direction inclined by a predetermined angle with respect to the optical axis of the projection system, but not through the projection system.

Claim 30

An exposure apparatus having a projection system through which an exposure energy beam is focused on an object covered by an exposure energy sensitive layer and having a predetermined pattern thereon, such that a predetermined circuit pattern is printed on the object by the exposure of the sensitive layer with the exposure energy beam, the improvement comprising: irradiating means for irradiating the object with a radiation beam in a direction inclined by a predetermined angle with respect to an optical axis of the projection system, but not through the projection system and wherein the angle is predetermined such that the projection system receives substantially all of the radiation beam reflectively scattered by the predetermined pattern of the object, but receives substantially no beam reflected by the surface of the photosensitive layer; converting means for converting an image of the predetermined pattern of the object as formed by the reflectively scattered component of the radiation beam received by the projection system into a signal; and positioning means for relatively positioning a plane of focus of the exposure energy and the surface of the object in a predetermined positional relationship in response to the signal from said converting means.

Claim 31

An exposure apparatus having a projection system through which an exposure energy beam is focused on an object covered by an exposure energy sensitive layer and having a predetermined pattern thereon, such that a predetermined circuit pattern is printed on the object by the exposure of the sensitive layer with the exposure energy beam, the improvement comprising: irradiating means for irradiating the object with a radiation beam in a direction inclined by a predetermined angle with respect to an optical axis of the projection system, but not through the projection system and wherein the angle is predetermined such that the projection system receives substantially all of the radiation beam reflectively scattered by the predetermined pattern of the object, but receives substantially no beam reflected by the surface of the photosensitive layer; converting means for converting an image of the predetermined pattern of the object as formed by the reflectively scattered component of the radiation beam received by the projection system into a signal; and positioning means for relatively positioning a plane of focus of the exposure energy and the surface of the object in a predetermined positional relationship in response to the signal from said converting means.

Claim 32

An apparatus according to claim 25, wherein said irradiating means comprises means for providing a laser beam as the radiation beam having a wavelength different from that of the exposure energy beam.

Claim 33

An apparatus according to claim 26, wherein a relationship sin -1 NA+10°≦B is satisfied, wherein NA is the numerical aperture of the projection system and B is the predetermined angle.

Claim 36

A method according to claim 28, wherein the step of irradiating the object comprises projecting a laser beam to the object in a direction inclined by a predetermined angle with respect to the optical axis of the projection system, but not through the projection system.

Claim 37

A method according to claim 29, wherein a relationship sin 31 1 NA+10°≦B is satisfied, where NA is the numerical aperture of the projection system and B is the predetermined angle.