US4427516A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Apparatus and method for plasma-assisted etching of wafers
Assignee: AT&T Inc
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Filing: 1983-03-04
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Granted: 1984-01-24
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Expires: 2003-03-04
Abstract
Abstract In a plasma-assisted etching apparatus and method designed to pattern silicon dioxide in a plasma derived from a mixture of trifluoromethane and ammonia, surfaces in the reaction chamber are coated with a layer of silicon. Contamination of wafers during the etching process is thereby substantially reduced. In practice, this leads to a significant increase in the yield of acceptable chips per wafer.
Inventors
- 👤 Hyman J. Levinstein
- 👤 Frederick Vratny
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-02 00:19
CPC Classifications
H; H01; H01J; H01J37/00; H01J37/32; H01J37/32431; H01J37/32532; H01J37/32559; H01J37/34; H10; H10P; H10P50/00; H10P50/20; H10P50/28; H10P50/282; H10P50/283; H01J2237/00; H01J2237/20; Y; Y10; Y10S; Y10S156/00; Y10S156/914; Y10S156/917
Claims Analysis
Total Claims: 20
Claim 1
Independent Claim
68 words
Apparatus for low-contamination plasma-assisted dry etching of a layer of silicon dioxide formed on a wafer, said apparatus comprising a reaction chamber, means for establishing within said chamber an etching plasma derived from a mixture of trifluoromethane and ammonia gases, said chamber including surfaces exposed to said plasma, and a coating of silicon on at least the surfaces in the immediate vicinity of said layer to be etched.
Claim 2
Dependent Claim
68 words
Apparatus for low-contamination plasma-assisted dry etching of a layer of silicon dioxide formed on a wafer, said apparatus comprising a reaction chamber, means for establishing within said chamber an etching plasma derived from a mixture of trifluoromethane and ammonia gases, said chamber including surfaces exposed to said plasma, and a coating of silicon on at least the surfaces in the immediate vicinity of said layer to be etched.
Claim 3
Dependent Claim
27 words
An apparatus as in claim 1 wherein said coating comprises individual particles of monocrystalline or polycrystalline silicon fused together on said surfaces in a plasma spraying process.
Claim 4
Dependent Claim
24 words
An apparatus as in claim 2 further including a cathode electrode in said reaction chamber, and means mounting said wafer on said cathode electrode.
Claim 5
Dependent Claim
97 words
An apparatus as in claim 3 wherein said establishing means includes means for establishing the following conditions in said reaction chamber: a pressure of approximately 50 micrometers, a power density of approximately 0.16 watts per square centimeter at the surface of the layer to be etched, a gas flow into said chamber of approximately 96 volume percent trifluoromethane and 4 volume percent ammonia, a gas flow into said chamber of approximately 30 cubic centimeters per minute and a dc bias voltage of said cathode electrode with respect to a point of reference potential of approximately 600 volts.
Claim 6
Dependent Claim
107 words
Apparatus for low-contamination plasma-assisted dry etching of a layer of silicon dioxide on a wafer that is to be processed to form multiple integrated circuits, said apparatus comprising a reaction chamber, means for establishing within said chamber an etching plasma derived from a mixture of trifluoromethane and ammonia, means within said chamber for holding a number of wafers to be etched, said chamber having internal surfaces including surfaces of said holding means in the immediate vicinity of said wafers to be etched, and a coating of silicon formed on internal surfaces including at least the surfaces of said holding means in the immediate vicinity of said wafers.
Claim 7
Dependent Claim
107 words
Apparatus for low-contamination plasma-assisted dry etching of a layer of silicon dioxide on a wafer that is to be processed to form multiple integrated circuits, said apparatus comprising a reaction chamber, means for establishing within said chamber an etching plasma derived from a mixture of trifluoromethane and ammonia, means within said chamber for holding a number of wafers to be etched, said chamber having internal surfaces including surfaces of said holding means in the immediate vicinity of said wafers to be etched, and a coating of silicon formed on internal surfaces including at least the surfaces of said holding means in the immediate vicinity of said wafers.
Claim 8
Independent Claim
92 words
A method for fabricating VLSI devices by delineating fine-line patterns in a layer of silicon dioxide on a wafer in accordance with a process sequence that includes low-contamination plasma-assisted dry etching, said method comprising the steps of mounting said wafer to be etched in a reaction chamber at least some of whose surfaces, including surfaces in the immediate vicinity of said layer to be etched, are coated with a layer of silicon, introducing a mixture of trifluoromethane and ammonia gases into said reaction chamber, and establishing an etching plasma within said chamber.
Claim 9
Independent Claim
92 words
A method for fabricating VLSI devices by delineating fine-line patterns in a layer of silicon dioxide on a wafer in accordance with a process sequence that includes low-contamination plasma-assisted dry etching, said method comprising the steps of mounting said wafer to be etched in a reaction chamber at least some of whose surfaces, including surfaces in the immediate vicinity of said layer to be etched, are coated with a layer of silicon, introducing a mixture of trifluoromethane and ammonia gases into said reaction chamber, and establishing an etching plasma within said chamber.
Claim 10
Dependent Claim
28 words
A method as in claim 6 wherein a cathode electrode is included in said reaction chamber and said wafer to be etched is mounted on said cathode electrode.
Claim 11
Dependent Claim
95 words
A method as in claim 7 wherein said establishing step includes establishing the following conditions in said reaction chamber: a pressure of approximately 50 micrometers, a power density of approximately 0.16 watts per square centimeter at the surface of the layer to be etched, a gas flow into said chamber of approximately 96 volume percent trifluoromethane and 4 volume percent ammonia, a gas flow into said chamber of approximately 30 cubic centimeters per minute and a dc bias voltage of said cathode electrode with respect to a point of reference potential of approximately 600 volts.
Claim 12
Dependent Claim
62 words
Apparatus for low-contamination plasma-assisted dry etching of a layer of silicon dioxide formed on a water, said apparatus comprising a reaction chamber, means for establishing within said chamber an etching plasma derived from trifluoromethane, said chamber including surfaces exposed to said plasma, and a coating of silicon on at least the surfaces in the immediate vicinity of said layer to be etched.
Claim 13
Dependent Claim
62 words
Apparatus for low-contamination plasma-assisted dry etching of a layer of silicon dioxide formed on a water, said apparatus comprising a reaction chamber, means for establishing within said chamber an etching plasma derived from trifluoromethane, said chamber including surfaces exposed to said plasma, and a coating of silicon on at least the surfaces in the immediate vicinity of said layer to be etched.
Claim 14
Dependent Claim
27 words
An apparatus as in claim 9 wherein said coating comprises individual particles of monocrystalline or polycrystalline silicon fused together on said surfaces in a plasma spraying process.
Claim 15
Dependent Claim
24 words
An apparatus as in claim 10 further including a cathode electrode in said reaction chamber, and means mounting said wafer on said cathode electrode.
Claim 16
Dependent Claim
102 words
Apparatus for low-contamination plasma-assisted dry etching of a layer of silicon dioxide on a wafer that is to be processed to form multiple integrated circuits, said apparatus comprising a reaction chamber, means for establishing within said chamber an etching plasma derived from trifluoromethane, means within said chamber for holding a number of wafers to be etched, said chamber having internal surfaces including surfaces of said holding means in the immediate vicinity of said wafers to be etched, and a coating of silicon formed on internal surfaces including at least the surfaces of said holding means in the intermediate vicinity of said wafers.
Claim 17
Dependent Claim
102 words
Apparatus for low-contamination plasma-assisted dry etching of a layer of silicon dioxide on a wafer that is to be processed to form multiple integrated circuits, said apparatus comprising a reaction chamber, means for establishing within said chamber an etching plasma derived from trifluoromethane, means within said chamber for holding a number of wafers to be etched, said chamber having internal surfaces including surfaces of said holding means in the immediate vicinity of said wafers to be etched, and a coating of silicon formed on internal surfaces including at least the surfaces of said holding means in the intermediate vicinity of said wafers.
Claim 18
Independent Claim
87 words
A method for fabricating VLSI devices by delineating fine-line patterns in a layer of silicon dioxide on a wafer in accordance with a process sequence that includes low-contamination plasma-assisted dry etching, said method comprising the steps of mounting said wafer to be etched in a reaction chamber at least some of whose surfaces, including surfaces in the immediate vicinity of said layer to be etched, are coated with a layer of silicon, introducing trifluoromethane gas into said reaction chamber, and establishing an etching plasma within said chamber.
Claim 19
Independent Claim
87 words
A method for fabricating VLSI devices by delineating fine-line patterns in a layer of silicon dioxide on a wafer in accordance with a process sequence that includes low-contamination plasma-assisted dry etching, said method comprising the steps of mounting said wafer to be etched in a reaction chamber at least some of whose surfaces, including surfaces in the immediate vicinity of said layer to be etched, are coated with a layer of silicon, introducing trifluoromethane gas into said reaction chamber, and establishing an etching plasma within said chamber.
Claim 20
Dependent Claim
28 words
A method as in claim 13 wherein a cathode electrode is included in said reaction chamber and said wafer to be etched is mounted on said cathode electrode.
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) | 1987-01-23 | 1987-07-25 | 1988-01-24 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1991-01-23 | 1991-07-25 | 1992-01-24 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1995-01-23 | 1995-07-25 | 1996-01-24 | $7700.00 | Window Closed / Lapsed |