US4275094A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Process for high pressure oxidation of silicon
Assignee: Fujitsu Ltd
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Filing: 1978-10-30
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Granted: 1981-06-23
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Expires: 1998-10-30
Abstract
Abstract A process for high pressure oxidation of silicon comprising the steps of inserting silicon wafers and an oxidizing substance into a quartz capsule sealing the quartz capsule gas-tightly by fusing, and heating the quartz capsule to generate a high pressure oxidizing atmosphere therein and to form an oxide film on the silicon wafers without a flow of the oxidizing atmosphere. In a case where water is used as the oxidizing substance, the water is frozen and the inside space of the quartz capsule is exhausted before the sealing operation. Furthermore, in a case where an oxidizing gas, e.g. oxygen gas, is used as the oxidizing substance, if the pressure of the gas is higher than the ambient pressure, the quartz capsule is cooled to decrease the gas pressure to a pressure below the ambient pressure before the sealing operation.
Inventors
- 👤 Mikio Takagi
- 👤 Mamoru Maeda
- 👤 Hajime Kamioka
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 21:14
CPC Classifications
H; H10; H10P; H10P14/00; H10P14/60; H10P14/63; H10P14/6302; H10P14/6304; H10P14/6306; H10P14/6308; H10P14/6309; C; C30; C30B; C30B33/00; C30B33/005; H10P14/6322
Claims Analysis
Total Claims: 15
Claim 1
Independent Claim
95 words
A process for high pressure oxidation of silicon with high uniformity of the oxide thickness comprising the steps of: inserting a quartz vessel containing a predetermined amount of water into a quartz capsule in the form of a tube with one end closed; spacing silicon wafers apart from each other in said quartz capsule; evacuating said quartz capsule; sealing said quartz capsule gas-tightly by fusing; and heating said quartz capsule to an elevated temperature to generate a high pressure steam therein and to form an oxide film on said silicon wafers with said high uniformity.
Claim 2
Dependent Claim
95 words
A process for high pressure oxidation of silicon with high uniformity of the oxide thickness comprising the steps of: inserting a quartz vessel containing a predetermined amount of water into a quartz capsule in the form of a tube with one end closed; spacing silicon wafers apart from each other in said quartz capsule; evacuating said quartz capsule; sealing said quartz capsule gas-tightly by fusing; and heating said quartz capsule to an elevated temperature to generate a high pressure steam therein and to form an oxide film on said silicon wafers with said high uniformity.
Claim 3
Dependent Claim
30 words
A process according to claim 1 wherein said quartz capsule is cooled with a cooling agent, preferably liquid nitrogen, to freeze said water in the vessel before said evacuating step.
Claim 4
Dependent Claim
23 words
A process according to claim 1 wherein the air in said quartz capsule is replaced with dry nitrogen gas before said evacuating step.
Claim 5
Dependent Claim
32 words
A process according to claim 1 wherein said sealing operation comprises steps of inserting a quartz plug into said quartz capsule, and fusing said quartz capsule and plug gas-tightly by a flame.
Claim 6
Dependent Claim
11 words
The process of claim 4, said flame compromising an oxyhydrogen flame.
Claim 7
Dependent Claim
70 words
A process according to claim 1 wherein the pressure of said generated steam in said quartz capsule at said elevated temperature is predetermined by the quantity of said enclosed water in accordance with the formula: ##EQU2## wherein P is the pressure in the capsule, T is the elevated temperature and W is the quantity of the enclosed water per each 1000 cm 3 of the inside volume of the capsule.
Claim 8
Dependent Claim
30 words
A process according to claim 1 wherein said elevated temperature is from 500° to 1200° C. and said generated pressure is from more than 1 to 20 kg/cm 2 .
Claim 9
Dependent Claim
14 words
The process of claim 7, said elevated temperature being from 800° to 1000° C.
Claim 10
Dependent Claim
16 words
The process of claim 7, said generated pressure being from 3 to 8 kg/cm 2 .
Claim 11
Dependent Claim
28 words
A process according to claim 1 wherein said spacing comprises standing said silicon wafers on edge on a quartz holder at intervals of from 2 to 10 mm.
Claim 12
Dependent Claim
32 words
A process according to claim 1 wherein said water comprises a liquid selected from the group consisting of distilled water and a water solution of 0.1 to 10 mol % hydrochloric acid.
Claim 13
Dependent Claim
27 words
The process of claim 1 comprising placing at least 50 of said wafers in said quartz capsule at intervals in the range from 2 to 10 mm.
Claim 14
Dependent Claim
22 words
The process of claim 1 comprising forming said oxide on said wafers to have a uniformity in thickness of ±2% or better.
Claim 15
Dependent Claim
44 words
The process of claim 1 comprising placing at least 50 of said wafers in said quartz capsule at intervals in the range from 2 to 10 mm, and forming said oxide on said wafers to have a uniformity in thickness of ±2% or better.
References Cited (Backward Citations)
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US4002512A
Cited
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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) | 1984-06-22 | 1984-12-22 | 1985-06-23 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1988-06-22 | 1988-12-22 | 1989-06-23 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1992-06-22 | 1992-12-22 | 1993-06-23 | $7700.00 | Window Closed / Lapsed |