US5100504A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method of cleaning silicon surface
Assignee: Mitsubishi Electric Corp
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Filing: 1991-03-07
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Granted: 1992-03-31
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Expires: 2011-03-07
Abstract
Abstract In the first step, a silicon oxide film (21) on a silicon surface (22) is etched away using a CHF 3 gas. After the silicon oxide film is removed, organic matter (23) of the C x F y group remains on the silicon surface. In the second step, the organic matter (23) is etched away using a NF 3 gas. The silicon oxide film (21) is etched in preference to underlying silicon (22) by using the CHF 3 gas. A F radical is easily formed from the NF 3 gas used for removing the organic matter (23). At the time of forming this F radical, no residue is formed which makes the silicon surface (22) dirty. Consequently, a clear silicon surface (22) is obtained.
Inventors
- 👤 Kenji Kawai
- 👤 Toshiaki Ogawa
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 16:26
CPC Classifications
H; H10; H10P; H10P70/00; H10P70/10; H10P70/12; H10P70/125
Claims Analysis
Total Claims: 10
Claim 1
Independent Claim
126 words
A method of removing a silicon oxide film (21) on a silicon surface (22) to obtain a clean surface, comprising the steps of: etching away the silicon oxide film (21) on the silicon surface (22) using a gas which leaves C x F y organic matter (23) on said silicon surface (22) during said etching away, said gas having a silicon oxide etch rate which is greater than its silicon etch rate and consisting essentially of a CHF 3 gas or a mixed gas of C m F n and H 2 , and etching away said organic matter (23) remaining on the silicon surface using at least one of a NF 3 gas and a F 2 gas after removing said silicon oxide film (21).
Claim 2
Independent Claim
126 words
A method of removing a silicon oxide film (21) on a silicon surface (22) to obtain a clean surface, comprising the steps of: etching away the silicon oxide film (21) on the silicon surface (22) using a gas which leaves C x F y organic matter (23) on said silicon surface (22) during said etching away, said gas having a silicon oxide etch rate which is greater than its silicon etch rate and consisting essentially of a CHF 3 gas or a mixed gas of C m F n and H 2 , and etching away said organic matter (23) remaining on the silicon surface using at least one of a NF 3 gas and a F 2 gas after removing said silicon oxide film (21).
Claim 3
Dependent Claim
31 words
The method according to claim 1, wherein the step of removing said silicon oxide film and the step of removing said organic matter are achieved in the same reaction chamber (11).
Claim 4
Dependent Claim
54 words
The method according to claim 2, wherein a step of introducing an inert gas into said reaction chamber (11) and discharging a gas for removing said silicon oxide film outside of said reaction chamber (11) is included between the step of removing said silicon oxide film and the step of removing said organic matter.
Claim 5
Dependent Claim
20 words
The method according to claim 2, wherein the etching conducted in said same reaction chamber (11) is reactive ion etching.
Claim 6
Dependent Claim
31 words
The method according to claim 1, wherein the step of removing said silicon oxide film and the step of removing said organic matter are achieved in different reaction chambers (11, 31).
Claim 7
Dependent Claim
61 words
The method according to claim 5, wherein said silicon oxide film is removed by reactive ion etching, and said organic matter is removed by photo chemical etching wherein irradiation of the at least one of a NF 3 gas and a F 2 gas causes dissociation of the at least one of a NF 3 gas and a F 2 gas.
Claim 8
Dependent Claim
27 words
The method according to claim 1, wherein an inert gas is mixed with a gas for removing said organic matter so as to adjust the etching rate.
Claim 9
Independent Claim
117 words
A method of removing a silicon oxide film (21) on a silicon surface (22) to obtain a clean surface, comprising the steps of: etching away the silicon oxide film (21) on the silicon surface (22) using a gas which leaves C x F y organic matter (23) on said silicon surface (22) during said etching away, said gas having a silicon oxide etch rate which is greater than its silicon etch rate and consisting essentially of a CHF 3 gas or a mixed gas of C m F n and H 2 , and etching away said organic matter (23) remaining on the silicon surface using a F 2 gas after removing said silicon oxide film (21).
Claim 10
Independent Claim
117 words
A method of removing a silicon oxide film (21) on a silicon surface (22) to obtain a clean surface, comprising the steps of: etching away the silicon oxide film (21) on the silicon surface (22) using a gas which leaves C x F y organic matter (23) on said silicon surface (22) during said etching away, said gas having a silicon oxide etch rate which is greater than its silicon etch rate and consisting essentially of a CHF 3 gas or a mixed gas of C m F n and H 2 , and etching away said organic matter (23) remaining on the silicon surface using a F 2 gas after removing said silicon oxide film (21).
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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) | 1995-03-31 | 1995-09-30 | 1996-03-31 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1999-03-31 | 1999-09-30 | 2000-03-31 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2003-03-31 | 2003-09-30 | 2004-03-31 | $7700.00 | Window Closed / Lapsed |