Patent US3751248A successfully refreshed from Google Patents.
US3751248A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method of selective multilayered etching
Assignee: AT&T Inc
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Filing: 1971-12-27
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Granted: 1973-08-07
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Expires: 1991-12-27
Abstract
Abstract A method for selectively etching a workpiece to different depths with a single multicolored photomask. In particular, the multicolored mark is used to selectively expose separate layers of photoresist. The separatelayers of photoresist are developed, and then selectively removed after performing a desired masking function. This method is particularly useful in fabricating resistor-conductor patterns for integrated circuits.
Inventors
- 👤 J Goell
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-24 15:47
CPC Classifications
H; H10; H10P; H10P95/00; G; G03; G03F; G03F7/00; G03F7/004; G03F7/09; G03F7/095; G03F7/20; G03F7/2022; H10N; H10N97/00
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
28 words
The method according to claim 1 wherein the structure is exposed to different colored light beams by shining white light through a multicolored filtering mask onto the workpiece.
Claim 2
Dependent Claim
24 words
The method according to claim 1 wherein said separating material is a subtractive filter material which can be removed to remove the overlying photoresist.
Claim 3
Dependent Claim
43 words
The method according to claim 1 wherein said alternate layers of photoresist and separating material comprise a layer of green-sensitive photoresist disposed on said workpiece, a layer of blue subtractive filter material and a layer of blue-sensitive photoresist disposed on the filter layer.
Claim 4
Dependent Claim
29 words
The method according to claim 4 wherein said workpiece comprises a dielectric substrate having a thin film of resistive material and a thin film of conductive material disposed thereupon.
Claim 5
Dependent Claim
29 words
The method according to claim 1 wherein said separating material is a transparent material which allows the overlying layer of photoresist to be removed without removing the underlying layer.
Claim 6
Dependent Claim
42 words
The method according to claim 1 wherein said alternate layers of photoresist and separating material comprise a layer of blue-sensitive photoresist disposed on said workpiece, a separating layer of transparent material and a layer of green-sensitive photoresist disposed on the separating layer.
Claim 7
Dependent Claim
28 words
The method of claim 7 wherein said workpiece comprises a dielectric substrate having a thin film of resistive material and a thin film of conductive material disposed thereupon.
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) | 1976-08-06 | 1977-02-05 | 1977-08-07 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-08-06 | 1981-02-05 | 1981-08-07 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-08-06 | 1985-02-05 | 1985-08-07 | $7700.00 | Window Closed / Lapsed |