Patent US4257826A successfully refreshed from Google Patents.
US4257826A
Expired / Lapsed
US
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Photoresist masking in manufacture of semiconductor device
Assignee: Texas Instruments Inc
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Filing: 1979-10-11
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Granted: 1981-03-24
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Expires: 1999-10-11
Abstract
Abstract A semiconductor integrated circuit such as an MOS random access memory or RAM is made by standard N-channel silicon gate manufacturing methods but using positive photoresist for successive masking steps by re-exposure of the photoresist. In making ion implants for threshold adjustment, the positive photoresist is deposited and exposed using a first mask which defines the channel areas of transistors which are to have one threshold voltage; upon developing, the channel areas will be bare so a first implant will penetrate only these channel areas. Then, without stripping the photoresist, another exposure using a second mask defines the channel areas of transistors which are to have another threshold voltage. After the photoresist is developed a second time, another implant will penetrate the channel areas defined by the second mask as well as the first.
Inventors
- 👤 Samuel Matalone, Jr.
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-06 11:26
CPC Classifications
H; H10; H10B; H10B12/00; H10B12/01; H10B12/02; H10B12/05; H10P; H10P76/00; H10P76/20; H10P76/204; H10P76/2041; Y; Y10; Y10S; Y10S438/00; Y10S438/942; Y10S438/948
Claims Analysis
Total Claims: 14
Claim 1
Independent Claim
94 words
A method of making a semiconductor device including transistors comprising the steps of applying a layer of photosensitive masking material on a face of a semiconductor body, exposing first areas of said layer to radiation, developing the layer to remove said first areas, performing a processing operation including ion implant on said face using the remaining layer as a mask, exposing second areas of the layer to radiation, developing the layer to remove the second areas, and performing another processing operation including ion implant on said face using the remaining layer as a mask.
Claim 2
Independent Claim
94 words
A method of making a semiconductor device including transistors comprising the steps of applying a layer of photosensitive masking material on a face of a semiconductor body, exposing first areas of said layer to radiation, developing the layer to remove said first areas, performing a processing operation including ion implant on said face using the remaining layer as a mask, exposing second areas of the layer to radiation, developing the layer to remove the second areas, and performing another processing operation including ion implant on said face using the remaining layer as a mask.
Claim 3
Dependent Claim
14 words
A method according to claim 1 wherein the photosensitive masking material is positive photoresist.
Claim 4
Dependent Claim
12 words
A method according to claim 2 wherein the radiation is ultraviolet light.
Claim 5
Independent Claim
98 words
A method of making a semiconductor device wherein the semiconductor device includes transistors, comprising the steps of applying a layer of photosensitive masking material on a face of a semiconductor body, exposing first areas of said layer to radiation, developing the layer to remove said face using the remaining layer as a mask, exposing second areas of the layer to radiation, developing the layer to remove the second areas, and performing another processing operation on said face using the remaining layer as a mask, the processing operations being ion implants which adjust the threshold voltages of such transistors.
Claim 6
Independent Claim
98 words
A method of making a semiconductor device wherein the semiconductor device includes transistors, comprising the steps of applying a layer of photosensitive masking material on a face of a semiconductor body, exposing first areas of said layer to radiation, developing the layer to remove said face using the remaining layer as a mask, exposing second areas of the layer to radiation, developing the layer to remove the second areas, and performing another processing operation on said face using the remaining layer as a mask, the processing operations being ion implants which adjust the threshold voltages of such transistors.
Claim 7
Dependent Claim
22 words
A method according to claim 4 wherein the semiconductor body is P-type silicon, and sources and drains of the transistors are N-type.
Claim 8
Dependent Claim
14 words
A method according to claim 4 wherein the photosensitive masking material is positive photoresist.
Claim 9
Dependent Claim
12 words
A method according to claim 6 wherein the radiation is ultraviolet light.
Claim 10
Independent Claim
94 words
A method of making a semiconductor device comprising the steps of applying a layer of photosensitive masking material on a face of a semiconductor body, exposing first areas of said layer to radiation, developing the layer to remove said first areas, altering said face at said first areas using the remaining layer as a mask by a processing operation, exposing second areas of the layer to radiation, developing the layer to remove the second areas, and altering said face at said second areas using the remaining layer as a mask by another processing operation.
Claim 11
Independent Claim
94 words
A method of making a semiconductor device comprising the steps of applying a layer of photosensitive masking material on a face of a semiconductor body, exposing first areas of said layer to radiation, developing the layer to remove said first areas, altering said face at said first areas using the remaining layer as a mask by a processing operation, exposing second areas of the layer to radiation, developing the layer to remove the second areas, and altering said face at said second areas using the remaining layer as a mask by another processing operation.
Claim 12
Dependent Claim
27 words
A method according to claim 8, wherein the semiconductor device includes transistors, and the processing operations are ion implants which adjust the threshold voltages of such transistors.
Claim 13
Dependent Claim
14 words
A method according to claim 8 wherein the photosensitive masking material is positive photoresist.
Claim 14
Dependent Claim
12 words
A method according to claim 10 wherein the radiation is ultraviolet light.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1984-03-23 | 1984-09-22 | 1985-03-24 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1988-03-23 | 1988-09-22 | 1989-03-24 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1992-03-23 | 1992-09-22 | 1993-03-24 | $7700.00 | Window Closed / Lapsed |