US4264409A
Expired / Lapsed
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Contamination-free selective reactive ion etching or polycrystalline silicon against silicon dioxide
Assignee: International Business Machines Corp
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Filing: 1980-03-17
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Granted: 1981-04-28
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Expires: 2000-03-17
Abstract
Abstract Disclosed is an improved Reactive Ion Etching (RIE) technique for etching polycrystalline silicon or single crystal silicon as must be done in Very Large Scale Integration (VLSI) using silicon technology. It teaches the use of an etch gas that consists of a mixture of silicon tetrafluoride (SiF4) and chlorine (Cl2) diluted with inert gas. This etch gas allows an RIE process which combines the very desirable features of selectivity (high Si/SiO2 etch rate ratio), directionality which creates vertical sidewalls on the etched features and contains no contaminants which can cause yield problems in VLSI circuits. Vertical side walls means no mask undercutting, hence zero etch bias.
Inventors
- 👤 Lawrence E. Forget
- 👤 Robert A. Gdula
- 👤 Joseph C. Hollis
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 21:13
CPC Classifications
H; H10; H10P; H10P50/00; H10P50/20; H10P50/26; H10P50/264; H10P50/266; H10P50/267; H10P50/268; H10P50/24; H10P50/242
Claims Analysis
Total Claims: 9
Claim 1
Independent Claim
113 words
A method for selective directional and contamination-free reactive ion etching of silicon against insulator mask comprising: providing a silicon body having a mask thereon composed of a material which will remain substantially unaffected by a SiF 4 and Cl 2 plasma; subjecting the unmasked regions of said silicon body to an R.F. plasma consisting essentially of X parts SiF 4 , Y parts Cl 2 , and Z parts of inert gas wherein X+Y+Z is essentially one hundred, X+Y is less than about 25 parts, and X and Y are respectively greater than zero; and continuing the subjective step until the desired etching is completed whereat said silicon body is substantially contamination free.
Claim 2
Independent Claim
113 words
A method for selective directional and contamination-free reactive ion etching of silicon against insulator mask comprising: providing a silicon body having a mask thereon composed of a material which will remain substantially unaffected by a SiF 4 and Cl 2 plasma; subjecting the unmasked regions of said silicon body to an R.F. plasma consisting essentially of X parts SiF 4 , Y parts Cl 2 , and Z parts of inert gas wherein X+Y+Z is essentially one hundred, X+Y is less than about 25 parts, and X and Y are respectively greater than zero; and continuing the subjective step until the desired etching is completed whereat said silicon body is substantially contamination free.
Claim 3
Dependent Claim
12 words
The method of claim 1 wherein said silicon body is monocrystalline silicon.
Claim 4
Dependent Claim
15 words
The method of claim 1 wherein said silicon body is a layer of polycrystalline silicon.
Claim 5
Dependent Claim
13 words
The method of claim 1 wherein said mask is composed of silicon dioxide.
Claim 6
Dependent Claim
16 words
The method of claim 1 wherein X has a magnitude between about 1.5 and 20 parts.
Claim 7
Dependent Claim
18 words
The method of claim 5 wherein the said X and Y is between about 2 and 25 parts.
Claim 8
Dependent Claim
11 words
The method of claim 1 wherein the inert gas is helium.
Claim 9
Dependent Claim
11 words
The method of claim 1 wherein the inert gas is argon.
References Cited (Backward Citations)
US4211601A
Cited
US4213818A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1984-04-27 | 1984-10-27 | 1985-04-28 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1988-04-27 | 1988-10-27 | 1989-04-28 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1992-04-27 | 1992-10-27 | 1993-04-28 | $7700.00 | Window Closed / Lapsed |