US4460416A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method for fabricating in-situ doped polysilicon employing overdamped gradually increasing gas flow rates with constant flow rate ratio
Assignee: Unisys Corp
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Filing: 1982-12-15
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Granted: 1984-07-17
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Expires: 2002-12-15
Abstract
Abstract A method of fabricating a film of in-situ doped polycrystalline silicon having a surface that is free of microscopic hillocks includes the steps of providing a deposition chamber and a wafer therein on which the film is to be fabricated and introducing one gas containing silicon atoms and another gas containing dopant atoms into said chamber with respective flow rates; wherein the respective flow rates are gradually increased in an overdamped fashion over a start-up time interval of at least one minute from zero to respective steady state values while simultaneously the ratio of the respective flow rates is kept within 25% of the ratio of said steady state values.
Inventors
- 👤 Casimir J. Wonsowicz
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-03 09:02
CPC Classifications
H; H10; H10P; H10P14/00; H10P14/40; H10P14/416; C; C23; C23C; C23C16/00; C23C16/22; C23C16/24; C23C16/44; H10P14/20; H10P14/24; H10P14/34; H10P14/3402; H10P14/3404; H10P14/3411; H10P14/3438; H10P14/3441; H10P14/3442
Claims Analysis
Total Claims: 18
Claim 1
Independent Claim
112 words
A method of fabricating a film of in-situ doped polycrystalline silicon having a surface that is free of microscopic hillocks, said method including the steps of: providing a deposition chamber and a wafer therein on which said film is to be fabricated; and introducing one gas containing silicon atoms and another gas containing dopant atoms into said chamber with respective flow rates; wherein said respective flow rates are gradually increased in an overdamped fashion over a start-up time interval of at least one minute from zero to respective steady state values while simultaneously the ratio of said respective flow rates is kept within 25% of the ratio of said steady state values.
Claim 2
Independent Claim
112 words
A method of fabricating a film of in-situ doped polycrystalline silicon having a surface that is free of microscopic hillocks, said method including the steps of: providing a deposition chamber and a wafer therein on which said film is to be fabricated; and introducing one gas containing silicon atoms and another gas containing dopant atoms into said chamber with respective flow rates; wherein said respective flow rates are gradually increased in an overdamped fashion over a start-up time interval of at least one minute from zero to respective steady state values while simultaneously the ratio of said respective flow rates is kept within 25% of the ratio of said steady state values.
Claim 3
Dependent Claim
21 words
A method according to claim 1 wherein the inside of said chamber is maintained at a temperature of 675° C.-725° C.
Claim 4
Dependent Claim
25 words
A method according to claim 2 wherein said respective flow rates are increased from zero to their respective steady state values in an exponential fashion.
Claim 5
Dependent Claim
21 words
A method according to claim 3 wherein said one gas is SiH 4 and said another gas is PH 3 .
Claim 6
Dependent Claim
29 words
A method according to claim 4 wherein said steady state flow rate of SiH 4 is at least ten times said steady state flow rate of PH 3 .
Claim 7
Dependent Claim
30 words
A method according to claim 5 wherein the inside of said chamber is maintained at a pressure of less than one torr while said gases are being introduced into it.
Claim 8
Independent Claim
115 words
A method of fabricating a film of in-situ doped polycrystalline material having a surface that is free of microscopic hillocks, said method including the steps of: providing a deposition chamber and a wafer therein on which said film is to be fabricated; and introducing one gas into said chamber which contains atoms of said polycrystalline material and simultaneously introducing another gas into said chamber which contains dopant atoms for said polycrystalline material; wherein said gases are introduced at respective flow rates which increase in a gradual fashion over a start-up time interval from zero to respective steady state values such that the ratio of said flow rates varies by no more than a predetermined fraction.
Claim 9
Independent Claim
115 words
A method of fabricating a film of in-situ doped polycrystalline material having a surface that is free of microscopic hillocks, said method including the steps of: providing a deposition chamber and a wafer therein on which said film is to be fabricated; and introducing one gas into said chamber which contains atoms of said polycrystalline material and simultaneously introducing another gas into said chamber which contains dopant atoms for said polycrystalline material; wherein said gases are introduced at respective flow rates which increase in a gradual fashion over a start-up time interval from zero to respective steady state values such that the ratio of said flow rates varies by no more than a predetermined fraction.
Claim 10
Dependent Claim
21 words
A method according to claim 7 wherein the inside of said chamber is maintained at a temperature of 675° C.-725° C.
Claim 11
Dependent Claim
29 words
A method according to claim 7 wherein said respective flow rates are limited during said start-up time interval to not overshoot said steady state values by more than 25%.
Claim 12
Dependent Claim
25 words
A method according to claim 7 wherein said respective flow rates are increased from zero to their respective steady state values in an exponential fashion.
Claim 13
Dependent Claim
16 words
A method according to claim 9 wherein said start-up time interval is at least one minute.
Claim 14
Dependent Claim
21 words
A method according to claim 7 wherein said one gas is SiH 4 and said another gas is PH 3 .
Claim 15
Dependent Claim
29 words
A method according to claim 7 wherein said steady state flow rate of SiH 4 is at least ten times said steady state flow rate of PH 3 .
Claim 16
Dependent Claim
30 words
A method according to claim 7 wherein the inside of said chamber is maintained at a pressure of less than one torr while said gases are being introduced into it.
Claim 17
Independent Claim
109 words
A method of fabricating a film of material having a surface that is free of microscopic hillocks, said method including the steps of: providing a deposition chamber and a wafer therein on which said film is to be fabricated; and introducing one gas into said chamber which contains atoms of one type and simultaneously introducing another gas into said chamber which contains atoms of another type; wherein said gases are introduced at respective flow rates which increase from zero to respective steady state values in an overdamped fashion while the ratio of said flow rates is confined to stay within 25% of the ratio of said steady state values.
Claim 18
Independent Claim
109 words
A method of fabricating a film of material having a surface that is free of microscopic hillocks, said method including the steps of: providing a deposition chamber and a wafer therein on which said film is to be fabricated; and introducing one gas into said chamber which contains atoms of one type and simultaneously introducing another gas into said chamber which contains atoms of another type; wherein said gases are introduced at respective flow rates which increase from zero to respective steady state values in an overdamped fashion while the ratio of said flow rates is confined to stay within 25% of the ratio of said steady state values.
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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) | 1987-07-17 | 1988-01-16 | 1988-07-17 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1991-07-17 | 1992-01-16 | 1992-07-17 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1995-07-17 | 1996-01-16 | 1996-07-17 | $7700.00 | Window Closed / Lapsed |