Patent US4345968A successfully refreshed from Google Patents.
US4345968A
Expired / Lapsed
US
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End point detection using gas flow
Assignee: MagnaChip Semiconductor Ltd
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Filing: 1981-08-27
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Granted: 1982-08-24
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Expires: 2001-08-27
Abstract
Abstract Apparatus and methods for end point detection during the plasma etching of integrated circuit wafers. Etching is conducted in a chamber subjected to the vacuum of a pump drawing at a constant volumetric gas flow rate. The etchant gases entering the chamber are regulated by a controller responsive to a feedback loop sensing pressures within the chamber. Changes in the chamber's chemical composition, which occur in time proximity to the end point of etching, affect the pressure and are detected as variations in the gas flow rates. Empirical results confirm the distinctiveness and repeatability which characterize the flow variations at the end point of etching.
Inventors
- 👤 Mary Ellen B. Coe
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 20:41
CPC Classifications
H; H01; H01J; H01J37/00; H01J37/32; H01J37/32917; H01J37/32935; H01J37/32431; H01J37/3244
Claims Analysis
Total Claims: 15
Claim 1
Independent Claim
147 words
A plasma etching system comprising: a plasma etching chamber; means for sensing the molar content within said chamber; a source of first etchant gas; means for coupling said first gas into said chamber; first means, for regulating the flow rate of said first gas through said means for coupling said first gas; means for extracting gases from said chamber, second means, for regulating the flow rate of gases through said means for extracting; control means, responsive to said means for sensing the molar content, for actuating said first and second means for regulating, so that one means for regulating maintains a substantially constant flow rate while the other means for regulating responds to said means for sensing the molar content; and means for sensing changes, in the means for regulating which responds to said means for sensing the molar content, to detect the end point of etching.
Claim 2
Dependent Claim
147 words
A plasma etching system comprising: a plasma etching chamber; means for sensing the molar content within said chamber; a source of first etchant gas; means for coupling said first gas into said chamber; first means, for regulating the flow rate of said first gas through said means for coupling said first gas; means for extracting gases from said chamber, second means, for regulating the flow rate of gases through said means for extracting; control means, responsive to said means for sensing the molar content, for actuating said first and second means for regulating, so that one means for regulating maintains a substantially constant flow rate while the other means for regulating responds to said means for sensing the molar content; and means for sensing changes, in the means for regulating which responds to said means for sensing the molar content, to detect the end point of etching.
Claim 3
Dependent Claim
26 words
The system recited in claim 1, wherein said control means actuates said other means for regulating to maintain a substantially constant molar content in said chamber.
Claim 4
Dependent Claim
18 words
The system recited in claim 2, wherein said means for sensing the molar content comprises a pressure sensor.
Claim 5
Dependent Claim
18 words
The system recited in claim 3, wherein said second means for regulating maintains said substantially constant flow rate.
Claim 6
Dependent Claim
83 words
The system recited in claim 4, further comprising: a source of second etchant gas; means for coupling said second gas into said chamber; third means, for regulating the flow rate of said second gas through said means for coupling said second gas; and wherein said control means for actuating also actuates said third means for regulating the flow rate so that changes detected by said pressure sensor are substantially offset by composite changes in the flow rates of said first and second gases.
Claim 7
Dependent Claim
29 words
The system recited in claim 5, wherein said control means for actuating regulates the flow rates of said first and second gases to maintain a fixed proportion by volume.
Claim 8
Dependent Claim
20 words
The systems recited in claims 4 or 6, wherein said second means for regulating is a constant displacement vacuum pump.
Claim 9
Dependent Claim
17 words
The system recited in claim 7, wherein said means for sensing changes comprises a gas flow meter.
Claim 10
Dependent Claim
31 words
The system recited in claim 8, wherein said gas flow meter generates a time plot of the flow rate suitable for detecting flow rate changes corresponding to the termination of etching.
Claim 11
Independent Claim
82 words
A method for determining the end point of plasma etching, comprising: coupling a plasma etching chamber to a source of vacuum and a source of etchant gas; regulating either the inlet gas flow rate or the gas flow rate to said source of vacuum, while holding the other substantially constant, to maintain a fixed molar content within said chamber; and sensing the time related change of said regulated gas flow during the progression of etching to detect transitions between substantially steady levels.
Claim 12
Independent Claim
82 words
A method for determining the end point of plasma etching, comprising: coupling a plasma etching chamber to a source of vacuum and a source of etchant gas; regulating either the inlet gas flow rate or the gas flow rate to said source of vacuum, while holding the other substantially constant, to maintain a fixed molar content within said chamber; and sensing the time related change of said regulated gas flow during the progression of etching to detect transitions between substantially steady levels.
Claim 13
Dependent Claim
19 words
The method recited in claim 10, wherein said fixed molar content is represented by the pressure within said chamber.
Claim 14
Dependent Claim
145 words
An etching system comprising: an etching chamber; means for sensing the molar content within said chamber; a source of first etchant gas; means for coupling said first gas into said chamber; first means, for regulating the flow rate of said first gas through said means for coupling said first gas; means for extracting gases from said chamber, second means, for regulating the flow rate of gases through said means for extracting; control means, responsive to said means for sensing the molar content, for actuating said first and second means for regulating, so that one means for regulating maintains a substantially constant flow rate while the other means for regulating responds to said means for sensing the molar content; and means for sensing changes, in the means for regulating which responds to said means for sensing the molar content, to detect the end point of etching.
Claim 15
Dependent Claim
145 words
An etching system comprising: an etching chamber; means for sensing the molar content within said chamber; a source of first etchant gas; means for coupling said first gas into said chamber; first means, for regulating the flow rate of said first gas through said means for coupling said first gas; means for extracting gases from said chamber, second means, for regulating the flow rate of gases through said means for extracting; control means, responsive to said means for sensing the molar content, for actuating said first and second means for regulating, so that one means for regulating maintains a substantially constant flow rate while the other means for regulating responds to said means for sensing the molar content; and means for sensing changes, in the means for regulating which responds to said means for sensing the molar content, to detect the end point of etching.
References Cited (Backward Citations)
US4160690A
Cited
US4283249A
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1985-08-23 | 1986-02-22 | 1986-08-24 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1989-08-23 | 1990-02-22 | 1990-08-24 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1993-08-23 | 1994-02-22 | 1994-08-24 | $7700.00 | Window Closed / Lapsed |