US5268069A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Safe method for etching silicon dioxide
Assignee: International Business Machines Corp
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Filing: 1992-06-08
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Granted: 1993-12-07
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Expires: 2012-06-08
Abstract
Abstract Anhydrous ammonium fluoride is used as a safe source of hydrogen fluoride for etching native or other silicon dioxide layers from silicon substrates. Heating the anhydrous ammonium fluoride above its sublimation temperature results in the generation of hydrogen fluoride gas which etches the silicon dioxide. Controlled amounts of water vapor are used during the etch reaction to ensure complete etching of the thin oxide layers down to within hundredths of a monolayer and to achieve precise etch rate control.
Inventors
- 👤 Jonathan D. Chapple-Sokol
- 👤 Richard A. Conti
- 👤 David E. Kotecki
- 👤 Andrew H. Simon
- 👤 Manu Tejwani
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-28 18:17
CPC Classifications
H; H10; H10P; H10P70/00; H10P70/10; H10P70/12; H10P50/00; H10P50/20; H10P50/28; H10P50/282; H10P50/283; H10P70/125
Claims Analysis
Total Claims: 22
Claim 1
Independent Claim
103 words
A method of etching or cleaning of silicon dioxide, comprising: placing a silicon substrate having a silicon dioxide layer formed thereon into an etch chamber; supplying a quantity of anhydrous ammonium fluoride in said etch chamber or in a chamber in close proximity to said etch chamber and connected therewith; heating said anhydrous ammonium fluoride above a temperature of sublimation for said anhydrous ammonium fluoride to create a gaseous specie which is transported to and etches said silicon dioxide on said silicon substrate; and preventing formation of an ammonium fluoride film on said silicon dioxide on said silicon substrate during said heating step.
Claim 2
Independent Claim
103 words
A method of etching or cleaning of silicon dioxide, comprising: placing a silicon substrate having a silicon dioxide layer formed thereon into an etch chamber; supplying a quantity of anhydrous ammonium fluoride in said etch chamber or in a chamber in close proximity to said etch chamber and connected therewith; heating said anhydrous ammonium fluoride above a temperature of sublimation for said anhydrous ammonium fluoride to create a gaseous specie which is transported to and etches said silicon dioxide on said silicon substrate; and preventing formation of an ammonium fluoride film on said silicon dioxide on said silicon substrate during said heating step.
Claim 3
Dependent Claim
19 words
A method as recited in claim 1 wherein said gaseous specie created during said heating step is hydrogen fluoride.
Claim 4
Dependent Claim
21 words
A method as recited in claim 1 wherein said heating step heats said anhydrous ammonium fluoride to 100° C. or more.
Claim 5
Dependent Claim
30 words
A method as recited in claim 1 further comprising the step of maintaining said silicon substrate at a temperature below said temperature required for sublimation of said anhydrous ammonium fluoride.
Claim 6
Dependent Claim
30 words
A method as recited in claim 1 further comprising the step of maintaining said silicon substrate at a temperature above said temperature required for sublimation of said anhydrous ammonium fluoride.
Claim 7
Dependent Claim
35 words
A method as recited in claim 1 further comprises the step of modulating the temperature of said anhydrous ammonium fluoride above and below said sublimation temperature, whereby the delivery of said gaseous specie is regulated.
Claim 8
Dependent Claim
37 words
A method as recited in claim 1 further comprising the step of depositing a layer of material on said silicon substrate immediately after said layer of silicon dioxide has been removed and before any silicon dioxide regrowth.
Claim 9
Dependent Claim
21 words
A method as recited in claim 1 further comprising the step of providing quantities of water vapor within said etch chamber.
Claim 10
Dependent Claim
22 words
A method as recited in claim 8 further comprising the step of removing quantities of water vapor from within said etch chamber.
Claim 11
Dependent Claim
22 words
A method as recited in claim 1 further comprising the step of removing quantities of water vapor from within said etch chamber.
Claim 12
Independent Claim
104 words
A method of etching or cleaning of silicon dioxide, consisting of: placing a silicon substrate having a silicon dioxide layer formed thereon into an etch chamber; supplying a quantity of anhydrous ammonium fluoride in said etch chamber or in a chamber in close proximity to said etch chamber and connected therewith; heating said anhydrous ammonium fluoride above a temperature of sublimation for said anhydrous ammonium fluoride to create a gaseous specie which is transported to and etches said silicon dioxide on said silicon substrate; and preventing formation of an ammonium fluoride film on said silicon dioxide on said silicon substrate during said heating step.
Claim 13
Independent Claim
104 words
A method of etching or cleaning of silicon dioxide, consisting of: placing a silicon substrate having a silicon dioxide layer formed thereon into an etch chamber; supplying a quantity of anhydrous ammonium fluoride in said etch chamber or in a chamber in close proximity to said etch chamber and connected therewith; heating said anhydrous ammonium fluoride above a temperature of sublimation for said anhydrous ammonium fluoride to create a gaseous specie which is transported to and etches said silicon dioxide on said silicon substrate; and preventing formation of an ammonium fluoride film on said silicon dioxide on said silicon substrate during said heating step.
Claim 14
Independent Claim
92 words
A method of etching or cleaning of silicon dioxide, comprising: placing a silicon substrate having a silicon dioxide layer formed thereon into an etch chamber; providing quantities of water vapor within said etch chamber; supplying a quantity of anhydrous ammonium fluoride in said etch chamber or in a chamber in close proximity to said etch chamber and connected therewith; and heating said anhydrous ammonium fluoride above a temperature of sublimation for said anhydrous ammonium fluoride to create gaseous specie which is transported to and etches said silicon dioxide on said silicon substrate.
Claim 15
Independent Claim
92 words
A method of etching or cleaning of silicon dioxide, comprising: placing a silicon substrate having a silicon dioxide layer formed thereon into an etch chamber; providing quantities of water vapor within said etch chamber; supplying a quantity of anhydrous ammonium fluoride in said etch chamber or in a chamber in close proximity to said etch chamber and connected therewith; and heating said anhydrous ammonium fluoride above a temperature of sublimation for said anhydrous ammonium fluoride to create gaseous specie which is transported to and etches said silicon dioxide on said silicon substrate.
Claim 16
Dependent Claim
27 words
A method as recited in claim 12 wherein said step of providing quantities of water is performed prior to said step of heating said anhydrous ammonium fluoride.
Claim 17
Dependent Claim
26 words
A method as recited in claim 12 wherein said step of providing quantities of water is performed during said step of heating said anhydrous ammonium fluoride.
Claim 18
Independent Claim
93 words
A method of etching or cleaning of silicon dioxide, comprising: placing a silicon substrate having a silicon dioxide layer formed thereon into an etch chamber; removing quantities of water vapor from within said etch chamber; supplying a quantity of anhydrous ammonium fluoride in said etch chamber or in a chamber in close proximity to said etch chamber and connected therewith; and heating said anhydrous ammonium fluoride above a temperature of sublimation for said anhydrous ammonium fluoride to create gaseous specie which is transported to and etches said silicon dioxide on said silicon substrate.
Claim 19
Independent Claim
93 words
A method of etching or cleaning of silicon dioxide, comprising: placing a silicon substrate having a silicon dioxide layer formed thereon into an etch chamber; removing quantities of water vapor from within said etch chamber; supplying a quantity of anhydrous ammonium fluoride in said etch chamber or in a chamber in close proximity to said etch chamber and connected therewith; and heating said anhydrous ammonium fluoride above a temperature of sublimation for said anhydrous ammonium fluoride to create gaseous specie which is transported to and etches said silicon dioxide on said silicon substrate.
Claim 20
Dependent Claim
23 words
A method as recited in claim 15 wherein said step of removing quantities of water from within said etch chamber is repeated periodically.
Claim 21
Independent Claim
101 words
A method of etching or cleaning of silicon dioxide, comprising: placing a silicon substrate having a silicon dioxide layer formed thereon into an etch chamber; providing quantities of water within said etch chamber; supplying a quantity of anhydrous ammonium fluoride in said etch chamber or in a chamber in close proximity to said etch chamber and connected therewith; heating said anhydrous ammonium fluoride above a temperature of sublimation for said anhydrous ammonium fluoride to create gaseous specie which is transported to and etches said silicon dioxide on said silicon substrate; and removing quantities of water vapor from within said etch chamber.
Claim 22
Independent Claim
101 words
A method of etching or cleaning of silicon dioxide, comprising: placing a silicon substrate having a silicon dioxide layer formed thereon into an etch chamber; providing quantities of water within said etch chamber; supplying a quantity of anhydrous ammonium fluoride in said etch chamber or in a chamber in close proximity to said etch chamber and connected therewith; heating said anhydrous ammonium fluoride above a temperature of sublimation for said anhydrous ammonium fluoride to create gaseous specie which is transported to and etches said silicon dioxide on said silicon substrate; and removing quantities of water vapor from within said etch chamber.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
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| 3.5 Years (Year 4) | 1996-12-06 | 1997-06-07 | 1997-12-07 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2000-12-06 | 2001-06-07 | 2001-12-07 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2004-12-06 | 2005-06-07 | 2005-12-07 | $7700.00 | Window Closed / Lapsed |