US4582581A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Boron trifluoride system for plasma etching of silicon dioxide
Assignee: Honeywell International Inc
•
Filing: 1985-05-09
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Granted: 1986-04-15
•
Expires: 2005-05-09
Abstract
Abstract BF3 based mixtures for selectively etching thin layers of silicon dioxide over silicon for use in the plasma etch process for integrated circuits manufacture is disclosed. In the process, when trace amounts of formaldehyde are added to the etch system the rate on oxide inceases markedly. The effect on the silicon is not substantial. The optional addition of an inert diluent gas did not substantially change these results.
Inventors
- 👤 Marie C. Flanigan
- 👤 Stephen M. Bobbio
- 👤 Robert F. Aycock
- 👤 Ralph L. DePrenda
- 👤 Kenneth M. Thrun
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 18:33
CPC Classifications
H; H10; H10P; H10P50/00; H10P50/20; H10P50/28; H10P50/282; H10P50/283
Claims Analysis
Total Claims: 9
Claim 1
Independent Claim
74 words
A method of selectively etching silicon dioxide preferentially over silicon or polysilicon in an article containing a layer of silicon dioxide on an underlayer of silicon or polysilicon which comprises exposing said article to a plasma gas mixture discharge wherein the plasma comprises BF 3 and formaldehyde gas wherein the formaldehyde is derived by contacting the plasma gas with a source of formaldehyde and continuing said exposure until the silicon dioxide layer is penetrated.
Claim 2
Independent Claim
74 words
A method of selectively etching silicon dioxide preferentially over silicon or polysilicon in an article containing a layer of silicon dioxide on an underlayer of silicon or polysilicon which comprises exposing said article to a plasma gas mixture discharge wherein the plasma comprises BF 3 and formaldehyde gas wherein the formaldehyde is derived by contacting the plasma gas with a source of formaldehyde and continuing said exposure until the silicon dioxide layer is penetrated.
Claim 3
Dependent Claim
38 words
The method of claim 1 wherein the source of formaldehyde is introduced into the plasma gas from a polymeric composition containing the --OCH 2 -- n linkage wherein n has a value of from about 8 to 100.
Claim 4
Dependent Claim
12 words
The method of claim 1 wherein the source of formaldehyde is paraformaldehyde.
Claim 5
Dependent Claim
16 words
The method of claim 1 in which the gas mixture is diluted with an inert gas.
Claim 6
Dependent Claim
24 words
The methods any of claims 1, 2 or 3 where one of the aims of the oxide etch is to achieve a tapered profile.
Claim 7
Dependent Claim
33 words
A plasma etch gas for selectively etching silicon dioxide against silicon comprising BF 3 and formaldehyde where in the BF 3 gas is preconditioned by contacting said gas with a source of formaldehyde.
Claim 8
Dependent Claim
33 words
A plasma etch gas for selectively etching silicon dioxide against silicon comprising BF 3 and formaldehyde where in the BF 3 gas is preconditioned by contacting said gas with a source of formaldehyde.
Claim 9
Dependent Claim
14 words
The plasma etch gas of claim 6 wherein the source of formaldehyde is paraformaldehyde.
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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) | 1989-04-14 | 1989-10-14 | 1990-04-15 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1993-04-14 | 1993-10-14 | 1994-04-15 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1997-04-14 | 1997-10-14 | 1998-04-15 | $7700.00 | Window Closed / Lapsed |