Patent US4744666A successfully refreshed from Google Patents.
US4744666A
Expired / Lapsed
US
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Alignment detection optical system of projection type aligner
Assignee: Hitachi Ltd
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Filing: 1986-07-16
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Granted: 1988-05-17
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Expires: 2006-07-16
Abstract
Abstract In an alignment detection optical system designed to observe an alignment pattern of a mask and an image of an alignment pattern of a wafer formed on the alignment pattern of the mask by a projection lens in a projection type aligner, there is provided a spatial filter designed to select only the reflected light having a desired reflection angle from the light reflected by the alignment pattern composed of steps formed on a surface of the wafer.
Inventors
- 👤 Yoshitada Oshida
- 👤 Naoto Nakashima
- 👤 Toshihiko Nakata
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-07 08:47
CPC Classifications
G; G03; G03F; G03F9/00; G03F9/70; G03F9/7065; G03F9/7049
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
125 words
An alignment detection optical system which is designed to observe an alignment pattern of a mask and an image of an alignment pattern of a wafer formed on the alignment pattern of the mask by a projection lens in order to make the alignment between the mask and the wafer in a projection type aligner, said detection optical system is provided with a spatial filter disposed at a position which is out of the conjugate relation to said alignment pattern of the wafer and between the image, of said alignment pattern of the wafer and an image sensor for detecting said image and said spatial filter has a transmittivity variable in the lateral direction of said alignment pattern but not variable in the longitudinal direction.
Claim 2
Dependent Claim
125 words
An alignment detection optical system which is designed to observe an alignment pattern of a mask and an image of an alignment pattern of a wafer formed on the alignment pattern of the mask by a projection lens in order to make the alignment between the mask and the wafer in a projection type aligner, said detection optical system is provided with a spatial filter disposed at a position which is out of the conjugate relation to said alignment pattern of the wafer and between the image, of said alignment pattern of the wafer and an image sensor for detecting said image and said spatial filter has a transmittivity variable in the lateral direction of said alignment pattern but not variable in the longitudinal direction.
Claim 3
Dependent Claim
18 words
An alignment detection optical system defined in claim 1, wherein said spatial filter is a liquid crystal filter.
Claim 4
Dependent Claim
37 words
An alignment detection optical system defined in claim 1, wherein said system is further provided with a mirror to deflect the illumination light, the incident angle of incoming illumination light being variable by oscillation of said mirror.
Claim 5
Dependent Claim
16 words
An alignment detection optical system defined in claim 1, wherein said spatial filter comprises a polarizer.
Claim 6
Dependent Claim
129 words
An alignment detection optical system which is designed for observing an alignment pattern of a mask and an image of an alignment pattern of a wafer formed on the alignment pattern of the mask by a projection lens in order to effect alignment between the mask and the wafer in a projection type aligner, said detection optical system having a polarizer disposed in the Fraunhofer field of the illumination light reflected by said alignment pattern of the wafer and between the image of said alignment pattern of the wafer and an image sensor to detect said image, said polarizer being disposed so that only a part of the diffracted light within a desired spatial frequency range can be selectively detected out of the diffracted light from said alignment pattern.
Claim 7
Dependent Claim
129 words
An alignment detection optical system which is designed for observing an alignment pattern of a mask and an image of an alignment pattern of a wafer formed on the alignment pattern of the mask by a projection lens in order to effect alignment between the mask and the wafer in a projection type aligner, said detection optical system having a polarizer disposed in the Fraunhofer field of the illumination light reflected by said alignment pattern of the wafer and between the image of said alignment pattern of the wafer and an image sensor to detect said image, said polarizer being disposed so that only a part of the diffracted light within a desired spatial frequency range can be selectively detected out of the diffracted light from said alignment pattern.
References Cited (Backward Citations)
US4362389A
Cited
US4641035A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1991-05-17 | 1991-11-16 | 1992-05-17 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1995-05-17 | 1995-11-16 | 1996-05-17 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1999-05-17 | 1999-11-16 | 2000-05-17 | $7700.00 | Window Closed / Lapsed |