US4148133A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Polysilicon mask for etching thick insulator
Assignee: Unisys Corp
•
Filing: 1978-05-08
•
Granted: 1979-04-10
•
Expires: 1998-05-08
Abstract
Abstract An improved method is disclosed for etching the thick field insulator films of silicon-oxy-nitride, during the fabrication process of metal oxide semiconductor (MOS) devices, wherein a polycrystalline silicon etch mask is used in conjunction with an acid etchant to etch the gate and interconnect openings through the thick field insulator to the source, gate and chain regions of the MOS devices for a memory array.
Inventors
- 👤 Leroy J. Kochel
- 👤 Harvey W. Kalweit
- 👤 Arthur D. Gonzales
- 👤 Clyde L. Church
- 👤 Paul H. Ou-Yang
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-29 13:58
CPC Classifications
H; H10; H10P; H10P50/00; H10P50/73; H10D; H10D30/00; H10D30/01; H10D30/021; H10D30/027; H10P14/00; H10P14/60; H10P14/66; H10P14/662; H10P50/20; H10P50/28; H10P50/282; H10P50/283; H10W; H10W20/00; H10W20/01; H10W20/071; H10W20/081; H10W20/082; H10D64/00; H10D64/01; H10D64/013; H10D64/01302; H10D64/01332; H10D64/01336; H10D64/01346; Y; Y10; Y10S; Y10S438/00; Y10S438/942; Y10S438/945
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
106 words
An improved method for etching a field insulator in a metal oxide semiconductor fabrication process, comprising: providing a silicon substrate having an insulator formed over said substrate; forming a layer of polycrystalline silicon over said field insulator; etching a plurality of openings through said layer of polycrystalline silicon to form a mask for etching said field insulator; etching said field insulator to expose portions of said substrate; oxidizing said layer of polycrystalline silicon and the exposed portions of said substrate and said regions of second conductivity type; stripping said oxidized layer of polycrystalline silicon from said field insulator and from said exposed portions of said substrate.
Claim 2
Dependent Claim
106 words
An improved method for etching a field insulator in a metal oxide semiconductor fabrication process, comprising: providing a silicon substrate having an insulator formed over said substrate; forming a layer of polycrystalline silicon over said field insulator; etching a plurality of openings through said layer of polycrystalline silicon to form a mask for etching said field insulator; etching said field insulator to expose portions of said substrate; oxidizing said layer of polycrystalline silicon and the exposed portions of said substrate and said regions of second conductivity type; stripping said oxidized layer of polycrystalline silicon from said field insulator and from said exposed portions of said substrate.
Claim 3
Dependent Claim
23 words
A method as set forth in claim 1, wherein said etching and stripping is performed with an etchant of the fluoric acid group.
Claim 4
Dependent Claim
14 words
A method as set forth in claim 1, wherein said field insulator is silicon-oxy-nitride.
Claim 5
Dependent Claim
18 words
A method as set forth in claim 1, wherein said field insulator is in excess of 1 micron.
Claim 6
Independent Claim
164 words
A method for fabricating an insulated metal gate MOS transistor, comprising: providing a silicon substrate of one conductivity type containing a source and a drain region of a second conductivity type in said substrate and having a silicon-oxy-nitride field insulator formed over said substrate; forming a layer of polycrystalline silicon over said field insulator; etching a plurality of openings through said layer of polycrystalline silicon to form a mask for etching said field insulator; etching said field insulator to expose portions of said substrate and said source and drain regions; oxidizing said layer of polycrystalline silicon and the exposed portions of said substrate and said source and drain regions; stripping said oxidized layer of polycrystalline silicon from said field insulator and from said exposed portions of said substrate and said source and drain regions; forming a gate insulator overlying the substate between the source and drain regions; and selectively depositing a metal over the exposed source and drain regions and the gate insulation structure.
Claim 7
Independent Claim
164 words
A method for fabricating an insulated metal gate MOS transistor, comprising: providing a silicon substrate of one conductivity type containing a source and a drain region of a second conductivity type in said substrate and having a silicon-oxy-nitride field insulator formed over said substrate; forming a layer of polycrystalline silicon over said field insulator; etching a plurality of openings through said layer of polycrystalline silicon to form a mask for etching said field insulator; etching said field insulator to expose portions of said substrate and said source and drain regions; oxidizing said layer of polycrystalline silicon and the exposed portions of said substrate and said source and drain regions; stripping said oxidized layer of polycrystalline silicon from said field insulator and from said exposed portions of said substrate and said source and drain regions; forming a gate insulator overlying the substate between the source and drain regions; and selectively depositing a metal over the exposed source and drain regions and the gate insulation structure.
Claim 8
Dependent Claim
18 words
A method as set forth in claim 5 wherein the field insulator is in excess of 1 micron.
References Cited (Backward Citations)
US3475234A
Cited
US3753807A
Cited
US3966501A
Cited
US3940288A
Cited
US3898105A
Cited
US3886000A
Cited
US4062707A
Cited
US4039358A
Cited
US4050967A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1982-04-09 | 1982-10-09 | 1983-04-10 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1986-04-09 | 1986-10-09 | 1987-04-10 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1990-04-09 | 1990-10-09 | 1991-04-10 | $7700.00 | Window Closed / Lapsed |