Patent US4450042A successfully refreshed from Google Patents.
US4450042A
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Plasma etch chemistry for anisotropic etching of silicon
Assignee: Texas Instruments Inc
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Filing: 1982-07-06
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Granted: 1984-05-22
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Expires: 2002-07-06
Abstract
Abstract A plasma etch chemistry which allows a near perfectly vertical etch of silicon is disclosed. A Cl-containing compound such as BCl3 has Br2 added to it, readily allowing anisotropic etching of silicon. This is due to the low volatility of SiBr4. The silicon surface facing the discharge is subjected to ion bombardment, allowing the volatilization (etching) of silicon as a Si-Cl-Br compound. The Br which adsorbs on the sidewalls of the etched silicon protects them from the etching. This new plasma etch chemistry yields a very smooth etched surface, and the etch rate is relatively insensitive to the electrical conductivity of the silicon.
Inventors
- 👤 Andrew J. Purdes
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-26 17:13
CPC Classifications
H; H10; H10P; H10P50/00; H10P50/20; H10P50/24; H10P50/242; H10P50/26; H10P50/264; H10P50/266; H10P50/267; H10P50/268; Y; Y10; Y10S; Y10S438/00; Y10S438/963
Claims Analysis
Total Claims: 19
Claim 1
Independent Claim
75 words
The method for selectively etching a layer of a silicon-bearing material in an integrated circuit, comprising the steps of: providing a patterned masking material over said silicon-bearing material to expose only the areas of said silicon-bearing material which are to be etched; passing a gaseous mixture over said layer; and creating a plasma discharge in said gaseous mixture adjacent to said layer of silicon-bearing material; wherein said gaseous mixture comprises bromine and a chlorine-bearing species.
Claim 2
Independent Claim
75 words
The method for selectively etching a layer of a silicon-bearing material in an integrated circuit, comprising the steps of: providing a patterned masking material over said silicon-bearing material to expose only the areas of said silicon-bearing material which are to be etched; passing a gaseous mixture over said layer; and creating a plasma discharge in said gaseous mixture adjacent to said layer of silicon-bearing material; wherein said gaseous mixture comprises bromine and a chlorine-bearing species.
Claim 3
Independent Claim
78 words
The method for selectively etching a layer of a silicon-bearing material in an integrated circuit, comprising the steps of: providing a patterned masking material over said silicon-bearing material to expose only the areas of said silicon-bearing material which are to be etched; passing a gaseous mixture over said layer; and creating a plasma discharge in said gaseous mixture adjacent to said layer of silicon-bearing material; wherein said gaseous mixture comprises bromine, a fluorine-bearing species, and a chlorine-bearing species.
Claim 4
Independent Claim
78 words
The method for selectively etching a layer of a silicon-bearing material in an integrated circuit, comprising the steps of: providing a patterned masking material over said silicon-bearing material to expose only the areas of said silicon-bearing material which are to be etched; passing a gaseous mixture over said layer; and creating a plasma discharge in said gaseous mixture adjacent to said layer of silicon-bearing material; wherein said gaseous mixture comprises bromine, a fluorine-bearing species, and a chlorine-bearing species.
Claim 5
Dependent Claim
26 words
The method of claim 1, wherein said chlorine-bearing species is selected from the group consisting of: silicon tetrachloride, carbon tetrachloride, phosophorus trichloride, chlorine, and hydrogen chloride.
Claim 6
Dependent Claim
20 words
The method of claim 2, wherein said fluorine-bearing species is selected from the group consisting of tetrafluoromethane, hexafluoroethane, and octofluoropropane.
Claim 7
Dependent Claim
23 words
The method of claim 2, wherein said gaseous mixture comprises a gas selected from the group consisting of: trifluoromethane, trifluorochloromethane, difluorodichloromethane, and fluorotrichloromethane.
Claim 8
Dependent Claim
15 words
The method of claim 1, 2, or 3, wherein said silicon-bearing material comprises single-crystal silicon.
Claim 9
Dependent Claim
15 words
The method of claim 1, 2, or 3, wherein said silicon-bearing material comprises polycrystalline silicon.
Claim 10
Dependent Claim
17 words
The method of claim 7, wherein said polycrystalline silicon comprises both lightly doped and heavily doped portions.
Claim 11
Dependent Claim
15 words
The method of claim 1, 2, or 3, wherein said silicon-bearing material comprises silicon nitride.
Claim 12
Dependent Claim
16 words
The method of claim 1, 2, or 3, wherein said silicon-bearing material comprises a metal silicide.
Claim 13
Dependent Claim
28 words
The method of claim 10, wherein said silicide is selected from the group consisting of: titanium silicide, molybdenum silicide, tungsten silicide, tantalum silicide, palladium silicide, and nickel silicide.
Claim 14
Dependent Claim
19 words
The method of claim 1, 2, or 3, wherein gaseous mixture further comprises a concentration of an inert gas.
Claim 15
Dependent Claim
22 words
The method of claim 12 wherein the concentration of said inert gas is at least 3 times the concentration of said bromine.
Claim 16
Dependent Claim
23 words
The method of claim 1, 2, or 3, wherein said gaseous mixture has a pressure in the range of 50 to 1000 microns.
Claim 17
Dependent Claim
30 words
The process of claim 1, 2, or 3, wherein power is applied to said plasma at a power density in the range of 3 to 30 watts per square inch.
Claim 18
Dependent Claim
33 words
The process of claim 1, 2, or 3, wherein said gaseous mixture includes bromine, said bromine being supplied at a flow rate in the range of 5 to 50 standard cc per minute.
Claim 19
Dependent Claim
16 words
The process of claim 16, wherein the total pressure is in the neighborhood of 300 microns.
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) | 1987-05-22 | 1987-11-21 | 1988-05-22 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1991-05-22 | 1991-11-21 | 1992-05-22 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1995-05-22 | 1995-11-21 | 1996-05-22 | $7700.00 | Window Closed / Lapsed |