US4933715A
Expired / Lapsed
US
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Method of detecting position of a mark
Assignee: Canon Inc
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Filing: 1989-01-25
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Granted: 1990-06-12
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Expires: 2009-01-25
Abstract
Abstract A mark detecting method and device suitably applicable to the alignment of a reticle in a semiconductor device manufacturing exposure apparatus, called a stepper, is disclosed. A mark is provided by repeated patterns having specific pitches. These patterns are set so that at least one pitch of the patterns differs, on a light-receiving surface of an image sensor which receives an image of the mark, from a multiple, by an integral number, of the sampling pitch (pitch of picture elements) of the image sensor. In one preferred form, the mark is formed by repeated patterns of a number N (≧2), wherein at least one pitch Pp of the patterns satisfies, on the light-receiving surface of the image sensor, a relationship Pp=(m+n/N)×Pix where m is an arbitrary number, n is an integral number which satisfies 1≦n≦N, and Pix is the sampling pitch of the image sensor. The image of such a mark is photoelectrically converted to thereby determine the position of the mark. With the proposed concept, any error which might be caused upon quantization of the mark image by the picture elements of the image sensor can be canceled or compensated at the time of calculation of the mark center. Therefore, the precision of the mark center detection can be improved.
Inventors
- 👤 Yuichi Yamada
- 👤 Naoki Ayata
- 👤 Hiroki Suzukawa
- 👤 Hideki Nogawa
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-03 00:45
CPC Classifications
G; G03; G03F; G03F9/00; G03F9/70
Claims Analysis
Total Claims: 12
Claim 1
Independent Claim
160 words
A method of detecting position of a mark, comprising the steps of: irradiating, with light from a light source, a mark formed on an object and being provided by repeated patterns; forming an image of the mark on an image pickup surface of an image sensor, by use of light from the object; photoelectrically converting the image of the mark with a predetermined sampling pitch defined by the image sensor; and calculating the position of the mark on the basis of a signal from the image sensor produced as a result of the photoelectric conversion; wherein at least one pitch Pp of the repeated patterns satisfies on the image pickup surface of the image sensor the following relationship Pp=(m+n/N)×Pix where N is an integral number not less than 2 and corresponds to the number of the patterns, m is an arbitrary number, n is an integral number that satisfies 1≦n<N, and Pix is the sampling pitch of the image sensor.
Claim 2
Independent Claim
160 words
A method of detecting position of a mark, comprising the steps of: irradiating, with light from a light source, a mark formed on an object and being provided by repeated patterns; forming an image of the mark on an image pickup surface of an image sensor, by use of light from the object; photoelectrically converting the image of the mark with a predetermined sampling pitch defined by the image sensor; and calculating the position of the mark on the basis of a signal from the image sensor produced as a result of the photoelectric conversion; wherein at least one pitch Pp of the repeated patterns satisfies on the image pickup surface of the image sensor the following relationship Pp=(m+n/N)×Pix where N is an integral number not less than 2 and corresponds to the number of the patterns, m is an arbitrary number, n is an integral number that satisfies 1≦n<N, and Pix is the sampling pitch of the image sensor.
Claim 3
Dependent Claim
34 words
A method according to claim 1, wherein the width of each pattern as measured on the image pickup surface of the image sensor is substantially equal to the sampling pitch of the image sensor.
Claim 4
Independent Claim
132 words
A method of detecting position of a mark, comprising the steps of: irradiating, with light from a light source, a mark formed on an object and being provided by repeated patterns; forming an image of the mark on an image pickup surface of an image sensor, by use of light from the object; photoelectrically converting the image of the mark with a predetermined sampling pitch as defined by the image sensor; and calculating the position of the mark on the basis of a signal from the image sensor produced as a result of the photoelectric conversion; wherein at least one pitch of the repeated patterns, upon the image pickup surface of the image sensor, is not equal to a multiple, by an integral number, of the sampling pitch of the image sensor.
Claim 5
Independent Claim
132 words
A method of detecting position of a mark, comprising the steps of: irradiating, with light from a light source, a mark formed on an object and being provided by repeated patterns; forming an image of the mark on an image pickup surface of an image sensor, by use of light from the object; photoelectrically converting the image of the mark with a predetermined sampling pitch as defined by the image sensor; and calculating the position of the mark on the basis of a signal from the image sensor produced as a result of the photoelectric conversion; wherein at least one pitch of the repeated patterns, upon the image pickup surface of the image sensor, is not equal to a multiple, by an integral number, of the sampling pitch of the image sensor.
Claim 6
Dependent Claim
34 words
A method according to claim 3, wherein the width of each pattern as measured on the image pickup surface of the image sensor is substantially equal to the sampling pitch of the image sensor.
Claim 7
Independent Claim
141 words
A method of detecting position of a mark, comprising the steps of: irradiating, with light from a light source, a mark formed on an object and being provided by repeated patterns; forming an image of the mark on an image pickup surface of an image sensor, by use of light from the object; photoelectrically converting the image of the mark with a predetermined sampling pitch defined by the image sensor; and calculating the position of the mark on the basis of a signal from the image sensor produced as a result of the photoelectric conversion; wherein at least one pitch of the repeated patterns differs from another pitch and wherein the difference in these pitches of the repeated patterns is, on the image pickup surface of the image sensor, equal to a half of the sampling pitch of the image sensor.
Claim 8
Independent Claim
141 words
A method of detecting position of a mark, comprising the steps of: irradiating, with light from a light source, a mark formed on an object and being provided by repeated patterns; forming an image of the mark on an image pickup surface of an image sensor, by use of light from the object; photoelectrically converting the image of the mark with a predetermined sampling pitch defined by the image sensor; and calculating the position of the mark on the basis of a signal from the image sensor produced as a result of the photoelectric conversion; wherein at least one pitch of the repeated patterns differs from another pitch and wherein the difference in these pitches of the repeated patterns is, on the image pickup surface of the image sensor, equal to a half of the sampling pitch of the image sensor.
Claim 9
Dependent Claim
34 words
A method according to claim 5, wherein the width of each pattern as measured on the image pickup surface of the image sensor is substantially equal to the sampling pitch of the image sensor.
Claim 10
Dependent Claim
122 words
A reticle for use in a semiconductor exposure apparatus, comprising: a base member; a pattern formed on said base member, to be printed on a semiconductor wafer by exposure; and a mark provided on said base member and being adapted to be observed by an image sensor, for positioning of said reticle with respect to a predetermined position, said mark having patterns of a number N which is an integral number not less than 2, wherein at least one pitch Pp of the patterns satisfies on an image pickup surface of the image sensor the following relationship Pp=(m+n/N)×Pix where m is an arbitrary number, n is an integral number that satisfies 1≦n<N and Pix is the sampling pitch of the image sensor.
Claim 11
Dependent Claim
122 words
A reticle for use in a semiconductor exposure apparatus, comprising: a base member; a pattern formed on said base member, to be printed on a semiconductor wafer by exposure; and a mark provided on said base member and being adapted to be observed by an image sensor, for positioning of said reticle with respect to a predetermined position, said mark having patterns of a number N which is an integral number not less than 2, wherein at least one pitch Pp of the patterns satisfies on an image pickup surface of the image sensor the following relationship Pp=(m+n/N)×Pix where m is an arbitrary number, n is an integral number that satisfies 1≦n<N and Pix is the sampling pitch of the image sensor.
Claim 12
Dependent Claim
34 words
A reticle according to claim 7, wherein the width of each pattern as measured on the image pickup surface of the image sensor is substantially equal to the sampling pitch of the image sensor.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1993-06-11 | 1993-12-11 | 1994-06-12 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1997-06-11 | 1997-12-11 | 1998-06-12 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2001-06-11 | 2001-12-11 | 2002-06-12 | $7700.00 | Window Closed / Lapsed |