US4502915A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Two-step plasma process for selective anisotropic etching of polycrystalline silicon without leaving residue
Assignee: Texas Instruments Inc
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Filing: 1984-01-23
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Granted: 1985-03-05
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Expires: 2004-01-23
Abstract
Abstract The disclosure relates to a two-step for selective anisotropic etching of polycrystalline silicon having a silicon dioxide base thereunder and an exposed opposing face with contaminants thereon including silicon dioxide without leaving a residue wherein the silicon is initially etched with a non-selective etchant for a distance below all contaminants and then an etchant used is a highly anisotropic selective polycrystalline silicon etchant.
Inventors
- 👤 Duane E. Carter
- 👤 Rhett B. Jucha
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-09 14:39
CPC Classifications
H; H10; H10P; H10P50/00; H10P50/20; H10P50/26; H10P50/264; H10P50/266; H10P50/267; H10P50/268
Claims Analysis
Total Claims: 21
Claim 1
Independent Claim
50 words
A method of etching polycrystalline silicon disposed over an insulating base and having contaminants extending to the surface of the silicon face opposite said base, comprising the steps of: (a) etching said face with a substantially non-selective etchant, and (b) etching said face with an etchant selective to polycrystalline silicon.
Claim 2
Independent Claim
50 words
A method of etching polycrystalline silicon disposed over an insulating base and having contaminants extending to the surface of the silicon face opposite said base, comprising the steps of: (a) etching said face with a substantially non-selective etchant, and (b) etching said face with an etchant selective to polycrystalline silicon.
Claim 3
Dependent Claim
46 words
The method of claim 1 wherein said non-selective etchant is taken from the class consisting of chloro-fluorocarbon, fluoro-boro carbon and fluorocarbon based etchants and wherein said selective etchant is taken from the class consisting of chlorine-containing etchants, bromine-containing etchants, chloride-containing etchants, bromide-containing etchants and combinations thereof.
Claim 4
Dependent Claim
21 words
The method of claim 1 wherein said non-selective etch extends to a depth of about 1500 Angstrom units from said face.
Claim 5
Dependent Claim
21 words
The method of claim 2 wherein said non-selective etch extends to a depth of about 1500 Angstrom units from said face.
Claim 6
Dependent Claim
25 words
The method of claim 1 wherein said non-selective etchant is a fluorocarbon containing etchant and said selective etchant is composed of HCl, HBr and He.
Claim 7
Dependent Claim
25 words
The method of claim 2 wherein said non-selective etchant is a fluorocarbon containing etchant and said selective etchant is composed of HCl, HBr and He.
Claim 8
Dependent Claim
25 words
The method of claim 3 wherein said non-selective etchant is a fluorocarbon containing etchant and said selective etchant is composed of HCl, HBr, and He.
Claim 9
Dependent Claim
25 words
The method of claim 4 wherein said non-selective etchant is a flurocarbon containing etchant and said selective etchant is composed of HCl, HBr and He.
Claim 10
Dependent Claim
17 words
The method of claim 5 wherein the ratio of HCl to HBr by volume is about 5:1.
Claim 11
Dependent Claim
17 words
The method of claim 6 wherein the ratio of HCl to HBr by volume is about 5:1.
Claim 12
Dependent Claim
17 words
The method of claim 7 wherein the ratio of HCl to HBr by volume is about 5:1.
Claim 13
Dependent Claim
17 words
The method of claim 8 wherein the ratio of HCl to HBr by volume is about 5:1.
Claim 14
Dependent Claim
15 words
The method of claim 5 wherein the non-selective etchant comprises CCl 2 F 2 .
Claim 15
Dependent Claim
15 words
The method of claim 6 wherein the non-selective etchant comprises CCl 2 F 2 .
Claim 16
Dependent Claim
15 words
The method of claim 7 wherein the non-selective etchant comprises CCl 2 F 2 .
Claim 17
Dependent Claim
15 words
The method of claim 8 wherein the non-selective etchant comprises CCl 2 F 2 .
Claim 18
Dependent Claim
15 words
The method of claim 9 wherein the non-selective etchant comprises CCl 2 F 2 .
Claim 19
Dependent Claim
15 words
The method of claim 10 wherein the non-selective etchant comprises CCl 2 F 2 .
Claim 20
Dependent Claim
15 words
The method of claim 11 wherein the non-selective etchant comprises CCl 2 F 2 .
Claim 21
Dependent Claim
15 words
The method of claim 12 wherein the non-selective etchant comprises CCl 2 F 2 .
References Cited (Backward Citations)
US4211601A
Cited
JPS577936A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1988-03-04 | 1988-09-03 | 1989-03-05 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1992-03-04 | 1992-09-03 | 1993-03-05 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1996-03-04 | 1996-09-03 | 1997-03-05 | $7700.00 | Window Closed / Lapsed |