US4314595A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method of forming nondefective zone in silicon single crystal wafer by two stage-heat treatment
Assignee: Toshiba Corp
•
Filing: 1980-01-08
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Granted: 1982-02-09
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Expires: 2000-01-08
Abstract
Abstract A silicon single crystal wafer is subjected to two-stage heat treatment. In the first-stage it is heated at a temperature within the range of between 500° C. and 1,000° C. Subsequently the thus heated wafer is heated at a temperature higher than that at the first stage. Thus, a nondefective zone is formed in the surface region of the wafer, and the interior zone of the wafer becomes rich in micro defects capable of gettering impurities such as heavy metals.
Inventors
- 👤 Kazuhiko Yamamoto
- 👤 Yoshiaki Matsushita
- 👤 Masaru Kanamori
- 👤 Kazutoshi Nagasawa
- 👤 Naotsugu Yoshihiro
- 👤 Seigo Kishino
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-31 05:11
CPC Classifications
H; H10; H10P; H10P36/00; H10P36/20; Y; Y10; Y10S; Y10S148/00; Y10S148/024
Claims Analysis
Total Claims: 15
Claim 1
Independent Claim
118 words
A method of forming a nondefective zone in a silicon single crystal wafer comprising: a first-stage heat treatment of heating the wafer for ten (10) to one hundred (100) hours at a temperature within the range of between 500° C. and 1000° C. to form a number of defect-causing nuclei within the wafer; and a second-stage heat treatment of heating the thus treated wafer at a temperature higher than that used in the first-stage, thereby converting the surface region of the wafer into a nondefective zone and forming a micro defect-rich zone at the interior center region of the wafer, the defect-causing nuclei being mainly involved in the formation of the micro defects in the second-stage heat treatment.
Claim 2
Independent Claim
118 words
A method of forming a nondefective zone in a silicon single crystal wafer comprising: a first-stage heat treatment of heating the wafer for ten (10) to one hundred (100) hours at a temperature within the range of between 500° C. and 1000° C. to form a number of defect-causing nuclei within the wafer; and a second-stage heat treatment of heating the thus treated wafer at a temperature higher than that used in the first-stage, thereby converting the surface region of the wafer into a nondefective zone and forming a micro defect-rich zone at the interior center region of the wafer, the defect-causing nuclei being mainly involved in the formation of the micro defects in the second-stage heat treatment.
Claim 3
Dependent Claim
27 words
The method according to claim 1, wherein the first-stage heat treatment is carried out at a temperature within the range of between 700° C. and 900° C.
Claim 4
Dependent Claim
27 words
The method according to claim 1, wherein the second-stage heat treatment is carried out at a temperature within the range of between 1,000° C. and 1,300° C.
Claim 5
Dependent Claim
27 words
The method according to claim 3, wherein the second-stage heat treatment is carried out at a temperature within the range of between 1,000° C. and 1,150° C.
Claim 6
Dependent Claim
19 words
The method according to claim 1, wherein the first-stage heat treatment is carried out for 10 to 100 hours.
Claim 7
Dependent Claim
19 words
The method according to claim 5, wherein the first-stage heat treatment is carried out for 16 to 64 hours.
Claim 8
Dependent Claim
19 words
The method according to claim 1, wherein the second-stage heat treatment is carried out for 10 to 100 hours.
Claim 9
Dependent Claim
19 words
The method according to claim 7, wherein the second-stage heat treatment is carried out for 16 to 64 hours.
Claim 10
Independent Claim
29 words
The method according to any of claims 1 to 8, wherein the first-stage heat treatment is carried out under a reducing atmosphere, a neutral atmosphere or an oxidizing atmosphere.
Claim 11
Independent Claim
29 words
The method according to any of claims 1 to 8, wherein the second-stage heat treatment is carried out under a reducing atmosphere, a neutral atmosphere or an oxidizing atmosphere.
Claim 12
Independent Claim
120 words
A method of forming a nondefective zone in a silicon single crystal wafer comprising: a first-stage heat treatment of heating the wafer for ten (10) to one hundred (100) hours at a temperature within the range of between 500° C. and 800° C. to form a number of defect causing nuclei within the wafer; and a second-stage heat treatment of heating the thus treated wafer at a temperature higher than that used in the first-stage, thereby converting the surface region of the wafer into a nondefective zone and forming a micro defect-rich zone at the interior center region of the wafer, the defect causing nuclei being mainly involved in the formation of the micro defects in the second-stage heat treatment.
Claim 13
Independent Claim
120 words
A method of forming a nondefective zone in a silicon single crystal wafer comprising: a first-stage heat treatment of heating the wafer for ten (10) to one hundred (100) hours at a temperature within the range of between 500° C. and 800° C. to form a number of defect causing nuclei within the wafer; and a second-stage heat treatment of heating the thus treated wafer at a temperature higher than that used in the first-stage, thereby converting the surface region of the wafer into a nondefective zone and forming a micro defect-rich zone at the interior center region of the wafer, the defect causing nuclei being mainly involved in the formation of the micro defects in the second-stage heat treatment.
Claim 14
Dependent Claim
27 words
The method according to claim 1, wherein the second-stage heat treatment is carried out at a temperature within the range of between 1,000° C. and 1,150° C.
Claim 15
Independent Claim
31 words
The method according to any of claims 1, 11, or 12, wherein both the first-stage and second-stage heat treatments are carried out under either a reducing atmosphere or a neutral atmosphere.
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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) | 1985-02-08 | 1985-08-10 | 1986-02-09 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1989-02-08 | 1989-08-10 | 1990-02-09 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1993-02-08 | 1993-08-10 | 1994-02-09 | $7700.00 | Window Closed / Lapsed |