US3597045A
Expired / Lapsed
US
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Automatic wafer identification system and method
Assignee: International Business Machines Corp
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Filing: 1969-06-30
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Granted: 1971-08-03
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Expires: 1989-06-30
Abstract
Abstract A method and system for the identification of semiconductor wafers. A code in the form of selected recognition symbols is inscribed in circuit-free regions or kerf areas of the wafer. In a separate operation, complex spatial filters of the entire set of recognition symbols are formed in spaced locations on a photographic medium. To detect whether a particular symbol has been inscribed in the wafer, the symbols within the wafer are cross-correlated with the complex spatial filters on the medium. The matching of a symbol with the complex spatial filter of that symbol produces a recognition spot of light behind the filter. A photodetector associated with each filter detects the light output when a match occurs.
Inventors
- 👤 Einar S Mathisen
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-24 11:53
CPC Classifications
G; G02; G02B; G02B27/00; G02B27/42; G02B27/46; H; H10; H10W; H10W46/00; H10W46/201
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
120 words
A method of identifying a semiconductor wafer comprising the steps of: forming spaced complex spatial filters of each one of a set of different recognition symbols on a photographic medium, each filter formed in a separate location of said medium; developing said photograpHic medium; forming selected ones of said symbols in an area of said wafer; illuminating said area of the wafer with a plurality of monochromatic, coherent beams of light at different angles, thereby modulating said beams with information representative of said recognition symbols; cross-correlating said modulated beams with the set of complex spatial filters of said symbols; detecting recognition spots of light formed when a recognition symbol in the wafer matches the complex spatial filter of the symbol.
Claim 2
Independent Claim
120 words
A method of identifying a semiconductor wafer comprising the steps of: forming spaced complex spatial filters of each one of a set of different recognition symbols on a photographic medium, each filter formed in a separate location of said medium; developing said photograpHic medium; forming selected ones of said symbols in an area of said wafer; illuminating said area of the wafer with a plurality of monochromatic, coherent beams of light at different angles, thereby modulating said beams with information representative of said recognition symbols; cross-correlating said modulated beams with the set of complex spatial filters of said symbols; detecting recognition spots of light formed when a recognition symbol in the wafer matches the complex spatial filter of the symbol.
Claim 3
Dependent Claim
26 words
A method according to claim 1 wherein said subset of recognition symbols are formed in circuit-free areas of at least one unit cell of said wafer.
Claim 4
Dependent Claim
21 words
A method according to claim 1 wherein said subset of recognition symbols are formed in the kerf area of said wafer.
Claim 5
Dependent Claim
132 words
A method according to claim 1 wherein forming spaced complex spatial filters comprises the steps of: illuminating a transparency of first said symbol with a plurality of beams of light directed at different angles, the beams being diffracted by and diverging from said transparency; illuminating a first location on said photographic medium with a first one of said diffracted beams; illuminating said photographic medium with an off-axis plane reference beam to interfere with said diffracted beam, thereby forming a complex spatial filter of said first symbol at said first location on the medium; forming complex spatial filters at other locations, respectively, by illuminating transparencies of the symbols, respectively, with said diffracted beams, illuminating said other locations with other ones of the beams, respectively, and illuminating said medium with said plane reference beam.
Claim 6
Dependent Claim
34 words
A method according to claim 4 wherein all of said diffracted beams except the beam illuminating the photographic medium to form each spatial filter are blocked off from the medium by an opaque mask.
Claim 7
Dependent Claim
14 words
A method according to claim 1 wherein the wafer is reflective to said light.
Claim 8
Dependent Claim
67 words
A method according to claim 6 wherein illuminating the area of the wafer containing said symbols with said plurality of beams of light comprises the steps of: transforming a source of monochromatic, coherent light into a collimated beam; forming said plurality of beams from said collimated beam; directing said beams to said area of the wafer, thereby causing said beams to reflect and diverge from the wafer.
Claim 9
Dependent Claim
49 words
A method according to claim 1 wherein cross-correlating the modulated beams with the set of complex spatial filters comprises the steps of: performing Fourier transforms on said beams; illuminating each said complex spatial filter on said medium with one of said beams, a single beam illuminating a single filter.
Claim 10
Independent Claim
219 words
A system for reading out simultaneously a subset of a set of recognition symbols inscribed in a semiconductor wafer, each subset containing more than one symbol comprising: a source of coherent, monochromatic light reflective to said wafer; an optical system for converting said light source into a plurality of collimated beams and for directing said beams at different angles to illuminate the portion of the wafer containing all said symbols; a first lens positioned to receive said beams reflected from said wafer and for forming optical images of said symbols; a photographic medium positioned on the side of said lens away from the wafer and containing a separate complex spatial filter for each one of the entire set of said recognition symbols, each filter formed in a separate location on said medium, each of said beams from said first lens illuminating said medium, a single beam illuminating a single complex spatial filter for cross-correlating said beams with said filters; a second lens positioned on the side of said medium away from said first lens for transforming the energy resulting from said cross-correlating to spots of light; means located at the output plane of said second lens for detecting said spots of lIght formed when a recognition symbol inscribed in the wafer matches a complex spatial filter of the symbol.
Claim 11
Independent Claim
219 words
A system for reading out simultaneously a subset of a set of recognition symbols inscribed in a semiconductor wafer, each subset containing more than one symbol comprising: a source of coherent, monochromatic light reflective to said wafer; an optical system for converting said light source into a plurality of collimated beams and for directing said beams at different angles to illuminate the portion of the wafer containing all said symbols; a first lens positioned to receive said beams reflected from said wafer and for forming optical images of said symbols; a photographic medium positioned on the side of said lens away from the wafer and containing a separate complex spatial filter for each one of the entire set of said recognition symbols, each filter formed in a separate location on said medium, each of said beams from said first lens illuminating said medium, a single beam illuminating a single complex spatial filter for cross-correlating said beams with said filters; a second lens positioned on the side of said medium away from said first lens for transforming the energy resulting from said cross-correlating to spots of light; means located at the output plane of said second lens for detecting said spots of lIght formed when a recognition symbol inscribed in the wafer matches a complex spatial filter of the symbol.
References Cited (Backward Citations)
CH451571A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1974-08-02 | 1975-02-01 | 1975-08-03 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1978-08-02 | 1979-02-01 | 1979-08-03 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1982-08-02 | 1983-02-01 | 1983-08-03 | $7700.00 | Window Closed / Lapsed |