US4465552A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method of selectively etching silicon dioxide with SF6 /nitriding component gas
Assignee: Honeywell International Inc
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Filing: 1983-08-11
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Granted: 1984-08-14
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Expires: 2003-08-11
Abstract
Abstract A gaseous mixture of SF 6 and a nitriding component such as NH 3 is disclosed as an effective selective SiO 2 etchant for use in either the plasma or reactive ion etch process. By adding NH 3 to the SF 6 , which is a known effective plasma etchant for silicon or poly-silicon, the silicon etch rate decreases while the oxide rate is effectively constant. At about 14% nitriding gas component, the rates are equivalent and for higher nitriding gas fractions, the silicon dioxide rate dominates. The optional addition of an inert diluent gas did not substantially change these results. The addition of hydrogen to the gaseous SF 6 /nitriding component mixture retards the etch rate on silicon still further and may increase the selectivity.
Inventors
- 👤 Stephen M. Bobbio
- 👤 Marie C. Flanigan
- 👤 Kenneth M. Thrun
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-27 09:37
CPC Classifications
H; H10; H10P; H10P50/00; H10P50/20; H10P50/28; H10P50/282; H10P50/283
Claims Analysis
Total Claims: 13
Claim 1
Independent Claim
66 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 low pressure plasma gas mixture discharge wherein the plasma comprises SF 6 and a nitriding component in the gaseous phase and continuing said exposure until the silicon dioxide layer is penetrated.
Claim 2
Independent Claim
66 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 low pressure plasma gas mixture discharge wherein the plasma comprises SF 6 and a nitriding component in the gaseous phase and continuing said exposure until the silicon dioxide layer is penetrated.
Claim 3
Dependent Claim
11 words
The method of claim 1 wherein the nitriding component is ammonia.
Claim 4
Dependent Claim
13 words
The method of claim 1 wherein hydrogen is added to the plasma gas.
Claim 5
Dependent Claim
13 words
The method of claim 2 wherein hydrogen is added to the plasma gas.
Claim 6
Dependent Claim
36 words
The plasma etching method as recited in claim 1 wherein silicon dioxide is etched selectively against silicon further characterized in that the ratio of SF 6 to NH 3 is respectively about 17:3 to about 1:2.
Claim 7
Dependent Claim
16 words
The method of claim 1 in which the gas mixture is diluted with an inert gas.
Claim 8
Dependent Claim
19 words
The method of claim 6 wherein the inert gas is selected from the group consisting of argon and helium.
Claim 9
Dependent Claim
29 words
The method of claim 1 wherein the plasma gas mixture incorporates hydrogen in a proportion by partial pressures to the nitriding component of from about 7:3 to about 1:2.
Claim 10
Dependent Claim
23 words
The method of claim 8 wherein the nitriding component is ammonia and the proportion by partial pressure to hydrogen is 3:7 to 2:1.
Claim 11
Dependent Claim
29 words
A plasma etch gas for selectively etching silicon dioxide against silicon comprising a mixture of at least about 14 percent by partial pressure NH 3 in SF 6 .
Claim 12
Dependent Claim
29 words
A plasma etch gas for selectively etching silicon dioxide against silicon comprising a mixture of at least about 14 percent by partial pressure NH 3 in SF 6 .
Claim 13
Dependent Claim
26 words
A plasma etch gas according to claim 10 containing hydrogen in a proportion by partial pressure to the nitrogen-containing compound from about 7:3 to about 1:2.
References Cited (Backward Citations)
US4330384A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1987-08-14 | 1988-02-13 | 1988-08-14 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1991-08-14 | 1992-02-13 | 1992-08-14 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1995-08-14 | 1996-02-13 | 1996-08-14 | $7700.00 | Window Closed / Lapsed |