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US4602981A
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Monitoring technique for plasma etching
Assignee: International Business Machines Corp
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Filing: 1985-05-06
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Granted: 1986-07-29
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Expires: 2005-05-06
Abstract
Abstract Plasma potential monitoring during a plasma etching process is accomplished by measuring the RF voltage at an electrode of, for example, a high pressure, high plasma density, symmetric single wafer reactor. The plasma potential is indicative of the plasma density, which has a high sensitivity to secondary electron emission from a wafer surface and yields both process etching endpoint and diagnostic information for a wide variety of processes and process conditions.
Inventors
- 👤 Lee Chen
- 👤 Gangadhara S. Mathad
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 12:29
CPC Classifications
H; H01; H01J; H01J37/00; H01J37/32; H01J37/32917; H01J37/32935
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
54 words
A method of monitoring the etching process within a plasma etching apparatus, comprising: measuring the RF voltage at an electrode of said etching apparatus, the RF voltage being a function of the plasma potential; and detecting changes in RF voltage as the RF voltage changes within said apparatus as the result of film-dependent changes.
Claim 2
Independent Claim
54 words
A method of monitoring the etching process within a plasma etching apparatus, comprising: measuring the RF voltage at an electrode of said etching apparatus, the RF voltage being a function of the plasma potential; and detecting changes in RF voltage as the RF voltage changes within said apparatus as the result of film-dependent changes.
Claim 3
Dependent Claim
52 words
The method of claim 1, further comprising: determining the endpoint of the etch process based upon changes in said RF voltage at the interface of an etch layer and an underlying layer on a wafer being etched; and terminating said etching process when said endpoint is obtained or a predetermined time thereafter.
Claim 4
Dependent Claim
22 words
The method of claim 1, further comprising: recording changes in said RF voltage during said etching process for process and system diagnostics.
Claim 5
Independent Claim
58 words
A method of detecting the passage from one layer to another layer on a wafer being etched in a plasma etching apparatus, said layers being different materials, comprising: measuring the RF voltage at an electrode of said plasma apparatus; and detecting a change in said RF voltage indicative of a change in plasma density at said another layer.
Claim 6
Independent Claim
58 words
A method of detecting the passage from one layer to another layer on a wafer being etched in a plasma etching apparatus, said layers being different materials, comprising: measuring the RF voltage at an electrode of said plasma apparatus; and detecting a change in said RF voltage indicative of a change in plasma density at said another layer.
Claim 7
Dependent Claim
15 words
The method of claim 4, wherein said two layers comprise silicon having different doping characteristics.
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) | 1989-07-28 | 1990-01-27 | 1990-07-29 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1993-07-28 | 1994-01-27 | 1994-07-29 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1997-07-28 | 1998-01-27 | 1998-07-29 | $7700.00 | Window Closed / Lapsed |