US3620850A
Expired / Lapsed
US
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Oxygen annealing
Assignee: Fairchild Semiconductor Corp
•
Filing: 1970-03-25
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Granted: 1971-11-16
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Expires: 1990-03-25
Abstract
Abstract A method for varying the surface charge density of a semiconductor device including the steps of heating the device prior to metallization at a temperature between 500* C. and 1,250* C. in dry oxygen and then cooling the device to a temperature below about 500* C. prior to the direct application of a metal layer to the device without an additional heating step.
Inventors
- 👤 Bruce E Deal
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-02 22:12
CPC Classifications
H; H10; H10P; H10P14/00; H10P14/60; H10P14/63; H10P14/6302; H10P14/6304; H10P14/6306; H10P14/6308; H10P14/6309; H10D; H10D99/00; H10P14/6322; H10P14/65; H10P14/6516; H10P14/6529; Y; Y10; Y10S; Y10S438/00; Y10S438/91
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
41 words
A method of claim 1 wherein said device is cooled to said temperature below about 500* C. in less than about 15 seconds in order to obtain a surface charge density characteristic of the temperature at which the device was heated.
Claim 2
Dependent Claim
90 words
A method according to claim 1 wherein the resulting surface charge density Qss is related to the time for heating the device and the temperature as given in the following table for both P-and N-type silicon: Oxygen Annealing P-Type N-Type Temp. Time Qss/q Qss/q C. Min. (cm 2 X 1011) (cm 2 X 1011) 1,250 2 2.3 1.4 1,200 2 2.7 1.8 1,100 5 3.8 2.7 1,000 10 4.9 3.7 900 15 6.0 4.7 800 30 7.3 5.8 700 45 8.7 7.0 600 60 10.2 8.5 500 90 11.9 10.0
Claim 3
Dependent Claim
41 words
A method according to claim 1 wherein said cooling is carried out over a period of at least one minute in order to obtain a surface charge density characteristic of a temperature lower than that at which the device was heated.
Claim 4
Dependent Claim
28 words
A method according to claim 4, wherein the time in which the device is cooled to below 500* C. is in the range of 1 to 30 minutes.
Claim 5
Dependent Claim
46 words
A method according to claim 1 wherein the cooling times, cooling rates and resulting surface charge density are as follows: Cooling Time Cooling Rate Qss/q (Sec.) (In./Min.) (cm 2 X 1011)6 240 3.1 10 126 3.9 30 42 6.7 60 21 6.7168 7.5 10.0 2,040 0.6210.6
Claim 6
Dependent Claim
28 words
A method according to claim 1, wherein the silicon dioxide is prepared by oxidation of silicon with wet oxygen at a temperature in the range of 550*-1,200* C.
Claim 7
Dependent Claim
11 words
A semiconductor device prepared according to the method of claim 7.
References Cited (Backward Citations)
US3384829A
Cited
US3336661A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1974-11-15 | 1975-05-17 | 1975-11-16 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1978-11-15 | 1979-05-17 | 1979-11-16 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1982-11-15 | 1983-05-17 | 1983-11-16 | $7700.00 | Window Closed / Lapsed |