Patent US4786166A successfully refreshed from Google Patents.
US4786166A
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Determination of focal plane for a scanning projection aligner
Assignee: Avago Technologies International Sales Pte Ltd
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Filing: 1987-06-01
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Granted: 1988-11-22
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Expires: 2007-06-01
Abstract
Abstract An improved pattern of lines (26, 28) is placed on a wedged substrate (18) used to locate the focal plane of a scanning projection aligner. This pattern replaces the conventional array of microscopic resolution targets with large regions of microscopic lines and spaces. When printed, in- and out-of-focus conditions are macroscopically apparent due to the presence or absence of photoresist (14). Desired quantities conventionally determined from microscopic data, such as location of the best focus plane, astigmatism, mask-to-wafer parallelism, mirror aberrations and misalignments, are macroscopically determined in accordance with the invention.
Inventors
- 👤 Catherine G. Kroko
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-09 22:19
CPC Classifications
G; G03; G03F; G03F7/00; G03F7/70; G03F7/70483; G03F7/70591; G03F7/706; G03F7/70605; G03F7/70616; G03F7/70641; G03F9/00; G03F9/70; G03F9/7003; G03F9/7023; G03F9/7026
Claims Analysis
Total Claims: 13
Claim 1
Independent Claim
90 words
A method of determining the location of the best focus surface of a scanning projection resist/aligner system having minimum resolvable features, comprising: (a) exposing an image in a resist layer formed on a polished side of a wafer through a wedged mask patterned with a plurality of opaque lines and clear spaces of widths nearly the size of the minimum resolvable features of the resist/aligner system; (b) developing the resist; and (c) determining the location of the best focus "plane" or surface by selecting the center of the resulting patterns.
Claim 2
Independent Claim
90 words
A method of determining the location of the best focus surface of a scanning projection resist/aligner system having minimum resolvable features, comprising: (a) exposing an image in a resist layer formed on a polished side of a wafer through a wedged mask patterned with a plurality of opaque lines and clear spaces of widths nearly the size of the minimum resolvable features of the resist/aligner system; (b) developing the resist; and (c) determining the location of the best focus "plane" or surface by selecting the center of the resulting patterns.
Claim 3
Dependent Claim
32 words
The method of claim 1 wherein said center of said resulting pattern is displaced by a known amount by said wedged mask, thus defining said location of said surface of best focus.
Claim 4
Dependent Claim
103 words
A mask pattern arrangement to be placed on a conventional wedged mask substrate for use in a scanning projection aligner having minimum resolvable features and a condenser/optics system, which when patterned in a resist layer on a wafer, allows quick macroscopic evaluation of the optical condition of the aligner, the mask pattern comprising: (a) a plurality of opaque lines and clear spaces of width nearly the size of the minimum resolvable feature of the aligner; and (b) wherein the pattern is arranged in stripes across the wedged mask so that each stripe will provide information about one segment of the aligner condenser/optics system.
Claim 5
Dependent Claim
103 words
A mask pattern arrangement to be placed on a conventional wedged mask substrate for use in a scanning projection aligner having minimum resolvable features and a condenser/optics system, which when patterned in a resist layer on a wafer, allows quick macroscopic evaluation of the optical condition of the aligner, the mask pattern comprising: (a) a plurality of opaque lines and clear spaces of width nearly the size of the minimum resolvable feature of the aligner; and (b) wherein the pattern is arranged in stripes across the wedged mask so that each stripe will provide information about one segment of the aligner condenser/optics system.
Claim 6
Dependent Claim
31 words
The arrangement of claim 3 wherein said stripes contain either (a) alternating sets of sagittal and tangential lines and spaces or (b) alternating sets of horizontal and vertical lines and spaces.
Claim 7
Dependent Claim
19 words
The arrangement of claim 3 wherein said stripes are partitioned or otherwise divided to provide a scale for measurement.
Claim 8
Dependent Claim
32 words
The arrangement of claim 3 wherein said location of the centers of the resulting patterns, when compared to each other and to a specified range form characteristic patterns belying specific machine problems.
Claim 9
Dependent Claim
25 words
The arrangement of claim 3 wherein said lines and spaces vary from about 1 to 25% above the minimum resolvable feature of the aligner/resist system.
Claim 10
Dependent Claim
17 words
The arrangement of claim 3 wherein said opaque lines on the mask comprise chrome or anti-reflective chrome.
Claim 11
Dependent Claim
55 words
The arrangement of claim 3 wherein the wafer is completely covered with stripes of lines and spaces so that the entire mirror or lens portions employed in printing can be characterized with respect to problems resulting from focus, astigmatism, system misalignments, aberrations and mechanical alignment of all relevant surfaces without the aid of a microscope.
Claim 12
Independent Claim
100 words
A method of diagnosing and characterizing a lens in a scanning projection aligner comprising (a) forming a plurality of stripes of resist on a polished side of a flat wafer, said stripes comprising alternating strips of sagittal and tangential lines or horizontal and vertical lines formed by exposure through a similarly-patterned wedges mask; (b) developing the resist to macroscopically define a region in each stripe at best focus, (c) determining the centers of each said region; and (d) comparing the location of said centers with a predetermined specification for each stripe and with the location of centers of other stripes.
Claim 13
Independent Claim
100 words
A method of diagnosing and characterizing a lens in a scanning projection aligner comprising (a) forming a plurality of stripes of resist on a polished side of a flat wafer, said stripes comprising alternating strips of sagittal and tangential lines or horizontal and vertical lines formed by exposure through a similarly-patterned wedges mask; (b) developing the resist to macroscopically define a region in each stripe at best focus, (c) determining the centers of each said region; and (d) comparing the location of said centers with a predetermined specification for each stripe and with the location of centers of other stripes.
References Cited (Backward Citations)
No citation records indexed.
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1991-11-22 | 1992-05-23 | 1992-11-22 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1995-11-22 | 1996-05-23 | 1996-11-22 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1999-11-22 | 2000-05-23 | 2000-11-22 | $7700.00 | Window Closed / Lapsed |