US3631772A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method and apparatus for characterizing photoresist
Assignee: AT&T Inc
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Filing: 1969-07-09
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Granted: 1972-01-04
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Expires: 1989-07-09
Abstract
Abstract The margin for error in exposing photoresist during mask making is reduced by online use of a new test mask. The mask consists of a glass plate coated on one face with a gradient of deposited chromium. On the reverse face, in the direction of the gradient, a linear array of microtest patterns in chromium are deposited. Resolution capability and optimum exposure for a required resolution of circuit pattern and for a given batch of photoresist are determined by coating a sample wafer and exposing through the test mask.
Inventors
- 👤 Robert K Curran
- 👤 Robert E Kerwin
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-08 19:48
CPC Classifications
G; G03; G03C; G03C5/00; G03C5/02; G03F; G03F1/00; G03F1/38; G03F1/44; G03F7/00; G03F7/20; G03F7/70; G03F7/70483; G03F7/7055; G03F7/70558
Claims Analysis
Total Claims: 4
Claim 1
Independent Claim
19 words
A test mask in accordance with claim 1, wherein said granular matter and said microtest patterns are deposited chromium.
Claim 2
Dependent Claim
28 words
A test pattern in accordance with claim 1, wherein said coating comprises a plurality of contiguous, rectangular zones of chromium deposited in increasing concentrations with each successive zone.
Claim 3
Dependent Claim
39 words
A test pattern in accordance with claim 3, wherein the optical densities of the successive said zones vary from approximately zero for a first edge zone to about three for the opposite edge zone, each optical density being calibrated.
Claim 4
Dependent Claim
25 words
A test pattern in accordance with claim 3, wherein said microtest patterns are aligned linearly across said zones, one such pattern registering with each zone.
References Cited (Backward Citations)
US3236290A
Cited
US3381572A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1975-01-03 | 1975-07-05 | 1976-01-04 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1979-01-03 | 1979-07-05 | 1980-01-04 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1983-01-03 | 1983-07-05 | 1984-01-04 | $7700.00 | Window Closed / Lapsed |