Patent US5279705A successfully refreshed from Google Patents.
US5279705A
Expired / Lapsed
US
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Gaseous process for selectively removing silicon nitride film
Assignee: Dainippon Screen Manufacturing Co Ltd
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Filing: 1991-11-22
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Granted: 1994-01-18
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Expires: 2011-11-22
Abstract
Abstract A process for selectively removing a silicon nitride film from a silicon layer surface having both a silicon oxide film thereon, and a silicon nitride film, includes the steps of: preparing a gas including at least hydrogen fluoride vapor, and supplying the gas to the silicon layer surface while maintaining the temperature of the silicon layer surface within a predetermined range that is higher than that of the gas. The gas includes a predetermined oxidizing agent, for example, HNO 3 , O 3 , H 2 O 2 , HClO, HClO 3 , HNO 2 , O 2 , H 2 SO 4 , Cl 2 or Br 2 . The temperature of the silicon layer surface is maintained at 10° C. to 90° C., preferably 15° C. to 60° C., more preferably 20° C. to 45° C. higher than the temperature of the gas.
Inventors
- 👤 Masato Tanaka
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 05:03
CPC Classifications
H; H10; H10P; H10P50/00; H10P50/20; H10P50/28; H10P50/282; H10P50/283; H10P72/00; H10P72/04; H10P72/0402; H10P72/0418; H10P72/0421
Claims Analysis
Total Claims: 17
Claim 1
Independent Claim
81 words
A process of selectively removing a silicon nitride film from a silicon layer surface on which both a silicon oxide film and a silicon nitride film are formed, said process comprising the steps of: preparing a gas including at least hydrogen fluoride vapor and an predetermined oxidizing agent in gas phase; and supplying said gas to said silicon layer surface while maintaining the temperature of said silicon layer surface within a range that is higher than the temperature of said gas.
Claim 2
Dependent Claim
81 words
A process of selectively removing a silicon nitride film from a silicon layer surface on which both a silicon oxide film and a silicon nitride film are formed, said process comprising the steps of: preparing a gas including at least hydrogen fluoride vapor and an predetermined oxidizing agent in gas phase; and supplying said gas to said silicon layer surface while maintaining the temperature of said silicon layer surface within a range that is higher than the temperature of said gas.
Claim 3
Dependent Claim
32 words
The process according to claim 1, wherein said oxidizing agent is selected from the group consisting of nitric acid, ozone, hydrogen peroxide, hypochlorous acid, chloric acid, oxygen, sulfuric acid, chlorine, and bromine.
Claim 4
Dependent Claim
30 words
The process according to claim 1, wherein said step of supplying said gas to said silicon layer surface includes the step of directing ultraviolet light to said silicon layer surface.
Claim 5
Dependent Claim
30 words
The process according to claim 2, wherein said step of supplying said gas to said silicon layer surface includes the step of directing ultraviolet light to said silicon layer surface.
Claim 6
Dependent Claim
51 words
The process according to claim 1, wherein said step of: preparing said gas includes the steps of preparing a hydrofluoric acid solution of a predetermined composition, and producing said gas which has a predetermined temperature including hydrogen fluoride and water vapor by maintaining said hydrofluoric acid solution at a predetermined temperature.
Claim 7
Dependent Claim
55 words
The process according to claim 5, wherein said silicon oxide film includes a silicon thermal oxide film, said hydrofluoric acid solution is of an azeotropic composition, and said temperature of said silicon layer surface is maintained within a range that is approximately 2° C. to approximately 64° C. higher than the temperature of said gas.
Claim 8
Dependent Claim
35 words
The process according to claim 6, wherein said temperature of said silicon layer surface is maintained within a range that is approximately 10° C. to approximately 40° C. higher than the temperature of said gas.
Claim 9
Dependent Claim
35 words
The process according to claim 7, wherein said temperature of said silicon layer surface is maintained within a range that is approximately 20° C. to approximately 30° C. higher than the temperature of said gas.
Claim 10
Dependent Claim
57 words
The process according to claim 1, wherein said oxidizing agent includes nitric acid, and said step of preparing said gas includes the steps of: mixing hydrofluoric acid of a predetermined concentration with nitric acid of a predetermined concentration at a predetermined volume percentage, and producing said gas by evaporating said mixture of hydrofluoric acid and nitric acid.
Claim 11
Dependent Claim
46 words
The process according to claim 9, wherein said silicon oxide film includes a silicon thermal oxide film, and said temperature of said silicon layer surface is maintained within a range that is approximately 10° C. to approximately 90° C. higher than the temperature of said gas
Claim 12
Dependent Claim
35 words
The process according to claim 10, wherein said temperature of said silicon layer surface is maintained within a range that is approximately 15° C. to approximately 60° C. higher than the temperature of said gas.
Claim 13
Dependent Claim
35 words
The process according to claim 11, wherein said temperature of said silicon layer surface is maintained within a range that is approximately 20° C. to approximately 45° C. higher than the temperature of said gas.
Claim 14
Dependent Claim
74 words
The process according to claim 1, wherein said oxidizing agent includes nitric acid, and said step of preparing said gas includes the steps of: preparing separately hydrofluoric acid vapor of a predetermined concentration and nitric acid vapor of a predetermined concentration, and conveying said hydrofluoric acid vapor and said nitric acid vapor, respectively, by carrier gas, and mixing said hydrofluoric acid vapor and said nitric acid vapor at a predetermined carrier gas flow rate.
Claim 15
Dependent Claim
17 words
The process according to claim 13, wherein said gas comprises approximately 40% to approximately 90% nitric acid.
Claim 16
Dependent Claim
17 words
The process according to claim 14, wherein said gas comprises approximately 40% to approximately 60% nitric acid.
Claim 17
Dependent Claim
17 words
The process according to claim 14, wherein said gas comprises approximately 70% to approximately 80% nitric acid.
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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) | 1997-01-17 | 1997-07-19 | 1998-01-18 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2001-01-17 | 2001-07-19 | 2002-01-18 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2005-01-17 | 2005-07-19 | 2006-01-18 | $7700.00 | Window Closed / Lapsed |