# US 5,706,091 A · Apparatus for detecting a mark pattern on a substrate > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 5,706,091 A - Document ID: US5706091A - Status: Granted - Kind: A - Application number: 08/639,099 - Filed: 1996-04-26 - Granted: 1998-01-06 - Earliest claimed: 1995-04-28 - Assignees: Nikon Corporation - Inventors: Naomasa Shiraishi - Web page: https://patentgrep.com/patent/US5706091A ## CPC - G03F 9/7088: {Alignment mark detection, e.g. TTR, TTL, off-axis detection, array detector, video detection} - G03F 7/701: {Off-axis setting using an aperture} - G03F 7/70125: {Use of illumination settings tailored to particular mask patterns (details of setting means G03F7/70091)} - G03F 7/70191: {Optical correction elements, filters or phase plates for controlling intensity, wavelength, polarisation, phase or the like} - G03F 9/70: {for microlithography (measuring printed patterns for monitoring overlay G03F7/70633 or focus G03F7/70641; projection system adjustment G03F7/70258; position control G03F7/70775)} - G03F: PHOTOMECHANICAL PRODUCTION OF TEXTURED OR PATTERNED SURFACES, e.g. FOR PRINTING, FOR PROCESSING OF SEMICONDUCTOR DEVICES; MATERIALS THEREFOR; ORIGINALS THEREFOR; APPARATUS SPECIALLY ADAPTED THEREFOR; (phototypographic composing devices B41B; photosensitive materials or processes for photographic purposes G03C; electrophotography, sensitive layers or processes therefor G03G) ## Abstract Illuminating light at a pupil plane of an illumination optical system for illuminating a position detection mark on a substrate is limited to an annular area centered at an optical axis, and a member substantially blocks an image-forming light beam distributed over an area on a pupil plane of an image-forming optical system for forming an image of the position detection mark on an imaging device by receiving light generated from the mark, the area being in image-forming relation to the annular area on the pupil plane of the illumination optical system. Alternatively, a member gives a phase difference of approximately .pi./2 ›rad! between the image-forming light beam distributed over the area which is in image-forming relation to the annular area on the pupil plane of the illumination optical system and the image-forming light beam distributed over the area other than that area. ## Claims ### Claim 1 A position detecting apparatus comprising: an illumination optical system for illuminating a position detection mark on a substrate by illuminating light in a predetermined wave band; an image-forming optical system for forming an image of said position detection mark on an imaging device by receiving light generated from said position detection mark; an image processing system for calculating a position of said position detection mark on the basis of an image signal output from said imaging device; an illuminating light beam limiting member for limiting an illuminating light beam at a first plane in said illumination optical system, said first plane being practically in optical Fourier transform relation to said position detection mark, so that said illuminating light beam passes through only a substantially annular first area on said first plane which is centered at an optical axis of said illumination optical system; and a phase-contrast member for giving a phase difference between an image-forming light beam distributed over a substantially annular second area on a second plane in said image-forming optical system which second plane is practically in optical Fourier transform relation to said position detection mark, said second area being in image-forming relation to said first area, and an image-forming light beam distributed over an area on said second plane other than said second area. ### Claim 2 (depends on 1) A position detecting apparatus according to claim 1, further comprising a member for reducing the image-forming light beam distributed over said second area. ### Claim 3 (depends on 1) A position detecting apparatus according to claim 1, wherein said phase-contrast member is an optical filter which is placed at said second plane in said image-forming optical system to give a phase difference of approximately (2m+1).pi./2.+-..pi./4 ›rad! (m is an integer) between the image-forming light beam distributed over said second area and the image-forming light beam distributed over the area other than said second area. ### Claim 4 (depends on 1) A position detecting apparatus according to claim 1, wherein an outer radius r.sub.o and inner radius r.sub.i of said annular first area satisfy the following conditions: r.sub.i .gtoreq..lambda.2/(2.times.P) r.sub.o -r.sub.i .ltoreq..lambda.1/P where .lambda.1 is the shortest wavelength in a wave band of light beams contributing to formation of said image signal in said illuminating light, .lambda.2 is the longest wavelength in said wave band, and P is a period of said position detection mark. ### Claim 5 (depends on 1) A position detecting apparatus according to claim 1, wherein a numerical aperture NA.sub.o of said image-forming optical system satisfies the following condition: NA.sub.o .gtoreq.r.sub.o +.lambda.2/P where r.sub.o is an outer radius of said annular first area, P is a period of said position detection mark, and .lambda.2 is the longest wavelength in a wave band of light beams contributing to formation of said image signal in said illuminating light. ### Claim 6 (depends on 1) A position detecting apparatus according to claim 1, further comprising a member for retaining said phase-contrast member in such a manner that said phase-contrast member can be selectively inserted into and withdrawn from an optical path of said image-forming optical system. ### Claim 7 (depends on 6) A position detecting apparatus according to claim 6, further comprising a member for retaining said illuminating light beam limiting member in such a manner that said illuminating light beam limiting member can be selectively inserted into and withdrawn from an optical path of said illumination optical system. ### Claim 8 (depends on 1) A position detecting apparatus according to claim 1, further comprising an image forming device for forming an image of an index mark on said imaging device, so that a positional displacement between the image of said position detection mark and the image of said index mark is detected on the basis of an image signal output from said imaging device. ### Claim 9 (depends on 8) A position detecting apparatus according to claim 8, wherein said image forming device includes: an index board having said index mark; an illumination system for illuminating said index board by a light beam different from said illuminating light; and an image-forming system for forming an image of said index mark on said imaging device by receiving light generated from said index mark. ### Claim 10 (depends on 9) A position detecting apparatus according to claim 9, wherein said index board is placed at a plane in said image-forming optical system, said plane being practically conjugate to said substrate, and said image-forming optical system forms an image of said position detection mark on said index board and also forms an image of said position detection mark and an image of said index mark on said imaging device. ### Claim 11 (depends on 9) A position detecting apparatus according to claim 9, wherein said illumination system has a member for adjusting an intensity of the light beam illuminating said index mark in accordance with a change in light quantity of an image-forming light beam from said position detection mark which is incident on said imaging device. ### Claim 12 (depends on 1) A position detecting apparatus according to claim 1, wherein said illumination optical system includes a light source which emits broad-band light or multi-wavelength light. ### Claim 13 A position detecting apparatus comprising: an illumination optical system for illuminating a position detection mark on a substrate by illuminating light in a predetermined wave band; an image-forming optical system for forming an image of said position detection mark on an imaging device by receiving light generated from said position detection mark; an image processing system for calculating a position of said position detection mark on the basis of an image signal output from said imaging device; an optical member for controlling an intensity distribution of said illuminating light over a first plane in said illumination optical system, said first plane being practically in optical Fourier transform relation to said position detection mark, such that an intensity of the illuminating light in a substantially annular first area on said first plane which is centered at an optical axis of said illumination optical system is higher than that in another area on said first plane; and a phase-contrast member for giving a phase difference between an image-forming light beam distributed over a substantially annular second area on a second plane in said image-forming optical system which second plane is practically in optical Fourier transform relation to said position detection mark, said second area being in image-forming relation to said first area, and an image-forming light beam distributed over an area on said second plane other than said second area. ### Claim 14 (depends on 13) A position detecting apparatus according to claim 13, further comprising a member for reducing the image-forming light beam distributed over said second area. ### Claim 15 (depends on 13) A position detecting apparatus according to claim 13, wherein said phase-contrast member is an optical filter which is placed at a second plane in said image-forming optical system to give a phase difference of approximately (2m+1).pi./2.+-..pi./4 ›rad! (m is an integer) between the image-forming light beam distributed over said second area and the image-forming light beam distributed over the area other than said second area. ### Claim 16 (depends on 13) A position detecting apparatus according to claim 13, wherein an outer radius r.sub.o and inner radius r.sub.i of said annular first area satisfy the following conditions: r.sub.i .gtoreq..lambda.2/(2.times.P) r.sub.o -r.sub.i .ltoreq..lambda.1/P where .lambda.1 is the shortest wavelength in a wave band of light beams contributing to formation of said image signal in said illuminating light, .lambda.2 is the longest wavelength in said wave band, and P is a period of said position detection mark. ### Claim 17 (depends on 13) A position detecting apparatus according to claim 13, wherein a numerical aperture NA.sub.o of said image-forming optical system satisfies the following condition: NA.sub.o .gtoreq.r.sub.o +.lambda.2/P where r.sub.o is an outer radius of said annular first area, P is a period of said position detection mark, and .lambda.2 is the longest wavelength in a wave band of light beams contributing to formation of said image signal in said illuminating light. ### Claim 18 (depends on 13) A position detecting apparatus according to claim 13, wherein said optical member has a stop member with a light-blocking portion which substantially covers said another area on said first plane so that a light intensity in said another area is substantially zero. ### Claim 19 (depends on 13) A position detecting apparatus according to claim 13, wherein said optical member has an intensity distribution changing member for changing at least one of outer and inner radii of said annular first area. ### Claim 20 (depends on 19) A position detecting apparatus according to claim 19, wherein said intensity distribution changing member has a plurality of stop members which are different from each other in at least one of outer and inner radii of an annular aperture, and a member for retaining said stop members such that one of said stop members is placed in an optical path of said illumination optical system. ### Claim 21 (depends on 13) A position detecting apparatus according to claim 13, wherein said phase-contrast member changes at least one of a radial width and position of said annular second area in accordance with a change of at least one of outer and inner radii of said first area. ### Claim 22 A position detecting apparatus comprising: an illumination optical system for illuminating a position detection mark on a substrate by illuminating light in a predetermined wave band; an image-forming optical system for forming an image of said position detection mark on an imaging device by receiving light generated from said position detection mark; an image processing system for calculating a position of said position detection mark on the basis of an image signal output from said imaging device; a stop member wherein an illuminating light beam distributed over a substantially annular first area on a practical pupil plane of said illumination optical system can pass, said first area being centered at an optical axis of said illumination optical system; and a phase-contrast member for giving a phase difference between an image-forming light beam distributed over a substantially annular second area on a practical pupil plane in said image-forming optical system, said second area being in image-forming relation to said first area, and an image-forming light beam distributed over an area on said practical pupil plane other than said second area. ### Claim 23 A position detecting apparatus comprising: an illumination optical system for illuminating a position detection mark on a substrate by illuminating light in a predetermined wave band; an image-forming optical system for forming an image of said position detection mark on an imaging device by receiving light generated from said position detection mark; an image processing system for calculating a position of said position detection mark on the basis of an image signal output from said imaging device; a secondary light source forming member for forming a substantially annular secondary light source on a practical pupil plane of said illumination optical system, said secondary light source being centered at an optical axis of said illumination optical system; and a phase-contrast member for giving a phase difference between an image-forming light beam distributed over a substantially annular area on a practical pupil plane of said image-forming optical system, said substantially annular area being in image-forming relation to said secondary light source, and an image-forming light beam distributed over an area on said practical pupil plane other than said substantially annular area. ### Claim 24 A position detecting apparatus comprising: an illumination optical system for illuminating a position detection mark on a substrate by illuminating light in a predetermined wave band; an image-forming optical system for forming an image of said position detection mark on an imaging device by receiving light generated from said position detection mark; an image processing system for calculating a position of said position detection mark on the basis of an image signal output from said imaging device; an optical member for controlling a light intensity distribution over a practical pupil plane of said illumination optical system such that a light intensity in a substantially annular area which is centered at an optical axis of said illumination optical system is higher than that in an area on said practical pupil plane inside said substantially annular area; and a phase-contrast member for giving a phase difference between an image-forming light beam distributed over a substantially circular area on a practical pupil plane of said image-forming optical system, said substantially circular area being in image-forming relation to said inside area, and an image-forming light beam distributed over an area on said practical pupil plane other than said substantially circular area. ### Claim 25 A position detecting apparatus comprising: an illumination optical system for illuminating a position detection mark on a substrate by illuminating light in a predetermined wave band; an image-forming optical system for forming an image of said position detection mark on an imaging device by receiving light generated from said position detection mark; an image processing system for calculating a position of said position detection mark on the basis of an image signal output from said imaging device; an illuminating light beam limiting member for limiting an illuminating light beam at a first plane in said illumination optical system, said first plane being practically in optical Fourier transform relation to said position detection mark, so that said illuminating light beam passes through only a first area having a predetermined shape on said first plane; and a phase-contrast member for giving a phase difference between an image-forming light beam distributed over a second area on a second plane in said image-forming optical system which second plane is practically in optical Fourier transform relation to said position detection mark, said second area having a shape corresponding to said predetermined shape and being in image-forming relation to said first area, and an image-forming light beam distributed over an area on said second plane other than said second area. ### Claim 26 (depends on 25) A position detecting apparatus according to claim 25, wherein said first area comprises a plurality of portions. ### Claim 27 A position detecting apparatus comprising: an illumination optical system for illuminating a position detection mark on a substrate by illuminating light in a predetermined wave band; an image-forming optical system for forming an image of said position detection mark on an imaging device by receiving light generated from said position detection mark; an image processing system for calculating a position of said position detection mark on the basis of an image signal output from said imaging device; an optical member for controlling an intensity distribution of said illuminating light over a first plane in said illumination optical system, said first plane being practically in optical Fourier transform relation to said position detection mark, such that an intensity of said illuminating light in a first area having a predetermined shape on said first plane is higher than in another area on said first plane; and a phase-contrast member for giving a phase difference between an image-forming light beam distributed over a second area on a second plane in said image-forming optical system which second plane is practically in optical Fourier transform relation to said position detection mark, said second area having a shape corresponding to said predetermined shape and being in image-forming relation to said first area, and an image-forming light beam distributed over an area on said second plane other than said second area. ### Claim 28 A position detecting apparatus comprising: an illumination optical system for illuminating a position detection mark on a substrate by illuminating light in a predetermined wave band; an image-forming optical system for forming an image of said position detection mark on an imaging device by receiving light generated from said position detection mark; an image processing system for calculating a position of said position detection mark on the basis of an image signal output from said imaging device; a stop member wherein an illuminating light beam distributed over a first area on a practical pupil plane of said illumination optical system can pass, said first area having a predetermined shape; and a phase-contrast member for giving a phase difference between an image-forming light beam distributed over a second area on a practical pupil plane of said image-forming optical system, said second area having a shape corresponding to said predetermined shape and being in image-forming relation to said first area, and an image-forming light beam distributed over an area on said practical pupil plane other than said second area. ### Claim 29 A position detecting apparatus comprising: an illumination optical system for illuminating a position detection mark on a substrate by illuminating light in a predetermined wave band; an image-forming optical system for forming an image of said position detection mark on an imaging device by receiving light generated from said position detection mark; an image processing system for calculating a position of said position detection mark on the basis of an image signal output from said imaging device; a secondary light source forming member for forming a secondary light source on a practical pupil plane of said illumination optical system, said secondary light source having a predetermined shape; and a phase-contrast member for giving a phase difference between an image-forming light beam distributed over an area on a practical pupil plane of said image-forming optical system, said area having a shape corresponding to said predetermined shape and being in image-forming relation to said secondary light source, and an image-forming light beam distributed over an area on said practical pupil plane other than said area. ### Claim 30 A position detecting apparatus comprising: an illumination optical system for illuminating a position detection mark on a substrate by illuminating light in a predetermined wave band; an image-forming optical system for forming an image of said position detection mark on an imaging device by receiving light generated from said position detection mark; an image processing system for calculating a position of said position detection mark on the basis of an image signal output from said imaging device; an optical member for controlling a light intensity distribution over a practical pupil plane of said illumination optical system such that a light intensity in a first area having a predetermined shape is higher than that in a second area on said practical pupil plane which is different from said first area; and a phase-contrast member for giving a phase difference between an image-forming light beam distributed over an area on a practical pupil plane of said image-forming optical system, said area having a shape corresponding to said predetermined shape and being in image-forming relation to said first area, and an image-forming light beam distributed over an area on said practical pupil plane other than said area which is in image-forming relation to said first area.