US4468260A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method for diffusing dopant atoms
Assignee: Ushio Denki KK
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Filing: 1983-03-29
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Granted: 1984-08-28
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Expires: 2003-03-29
Abstract
Abstract Dopant atoms are diffused into a silicon wafer by heating the entirety of the silicon wafer with the dopant atoms to a predetermined diffusing temperature in a short period of time, and more specifically, by applying light onto the silicon wafer under such conditions that the temperature difference between a central part of the silicon wafer and its peripheral part is maintained within 65° C. The above diffusion method permits to carry out diffusion of the dopant atoms into silicon wafers with high productivity but without inducing physical defects such as warping or slip lines. It requires a very short time period for effecting diffusion to a desired extent and it enables to make the depth of diffusion greater.
Inventors
- 👤 Tatsumi Hiramoto
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-27 22:02
CPC Classifications
H; H10; H10P; H10P32/00; H10P32/10; H10P32/14; H10P32/1408; H10P32/141; H10P32/1404; H10P32/1406; H10P32/17; H10P32/171; H10P34/00; H10P34/40; H10P34/42; H10P34/422
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
79 words
A method for diffusing dopant atoms into a silicon wafer, which method comprises heating the entirety of said silicon wafer with said dopant atoms to a predetermined diffusing temperature in a short period of time by applying light thereonto under such conditions that the temperature difference between a central part of said silicon wafer and a peripheral part thereof is maintained within 65° C., thereby causing said dopant to undergo thermal diffusion into the interior of said silicon wafer.
Claim 2
Independent Claim
79 words
A method for diffusing dopant atoms into a silicon wafer, which method comprises heating the entirety of said silicon wafer with said dopant atoms to a predetermined diffusing temperature in a short period of time by applying light thereonto under such conditions that the temperature difference between a central part of said silicon wafer and a peripheral part thereof is maintained within 65° C., thereby causing said dopant to undergo thermal diffusion into the interior of said silicon wafer.
Claim 3
Dependent Claim
58 words
A method as claimed in claim 1, wherein the light is applied from an upper and lower plane light sources disposed respectively above and below said silicon wafer and each of said plane light sources is constructed of a reflector and a number of halogen lamps arranged close to one another between said reflector and the silicon wafer.
Claim 4
Dependent Claim
44 words
A method as claimed in claim 2, wherein said plane light sources have areas wider than said silicon wafer and the application of the light is carried out while holding said silicon wafer in face-to-face relationship with central regions of said plane light sources.
Claim 5
Dependent Claim
38 words
A method as claimed in claim 2, wherein halogen lamps arranged along the peripheries of their corresponding plane light sources are closer to the level at which said silicon wafer is held, compared with the remaining halogen lamps.
Claim 6
Dependent Claim
32 words
A method as claimed in claim 2, wherein halogen lamps arranged along the peripheries of their corresponding plane light sources are operated with a power consumption greater than the remaining halogen lamps.
Claim 7
Dependent Claim
23 words
A method as claimed in claim 1, wherein the light is applied to said silicon wafer which is held within a transparent container.
Claim 8
Dependent Claim
41 words
A method as claimed in claim 1, wherein the application of the light is carried out while additionally heating the peripheral part of said silicon wafer by means of a subsidiary heater arranged along the peripheral part of said silicon wafer.
Claim 9
Dependent Claim
25 words
A method as claimed in claim 1, wherein said dopant atoms have in advance been introduced in said silicon wafer by the ion implantation process.
Claim 10
Dependent Claim
15 words
A method as claimed in claim 8, wherein the dopant atoms are aluminum or gallium.
Claim 11
Dependent Claim
23 words
A method as claimed in claim 1, wherein a material containing said dopant atoms have in advance been applied on said silicon wafer.
References Cited (Backward Citations)
US3589949A
Cited
US3627590A
Cited
US4016006A
Cited
US4001047A
Cited
US4012236A
Cited
US4170490A
Cited
US4415372A
Cited
US4370174A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1987-08-28 | 1988-02-27 | 1988-08-28 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1991-08-28 | 1992-02-27 | 1992-08-28 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1995-08-28 | 1996-02-27 | 1996-08-28 | $7700.00 | Window Closed / Lapsed |