US4249970A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method of boron doping silicon bodies
Assignee: International Business Machines Corp
•
Filing: 1979-08-20
•
Granted: 1981-02-10
•
Expires: 1999-08-20
Abstract
Abstract An open diffusion method of doping a silicon body with boron. In a first open diffusion heating step, a boron glass is deposited upon the silicon body with a silicon-rich boron phase (SiB6) formed beneath the glass where deposition is directly on silicon. The boron glass and SiB6 layer are formed by exposing the silicon body to a gas mixture containing a predetermined boron quantity and boron and oxygen in a predetermined quantitative ratio. Etching steps then permit the removal of the boron glass without deleteriously affecting the SiB6 layer or underlying silicon, or uncontrollably affecting any SiO2 masking layers. In a second heating step, at least a part of the boron from the SiB6 layer is driven into the silicon in an inert or oxidizing atmosphere.
Inventors
- 👤 Marian Briska
- 👤 Klaus P. Thiel
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 18:10
CPC Classifications
C; C30; C30B; C30B31/00; C30B31/02; H; H10; H10P; H10P32/00; H10P32/10; H10P32/12; H10P32/17; H10P32/171; H10P50/00; H10P50/20; H10P50/28; H10P50/282; H10P50/283; Y; Y10; Y10S; Y10S257/00; Y10S257/918
Claims Analysis
Total Claims: 13
Claim 1
Independent Claim
141 words
A method of doping a silicon body through diffusion of boron, comprising the steps of: exposing said body to a gas mixture including BBr 3 and O 2 with said gas mixture formed at the coating temperature of BBr 3 and O 2 as contained in a flowing carrier gas such that the molar ratio of O 2 :BBr 3 lies between 20 and 65 so as to thereby form a boron glass layer over said body with a silicon-rich boron layer being formed between said glass layer and body in selected areas of said body; removing said boron glass layer so formed without adversely affecting said silicon-rich boron layer; and heating said body so that at least a portion of the boron from said silicon-rich boron layer is driven into said silicon body to thereby selectively dope said silicon body.
Claim 2
Independent Claim
141 words
A method of doping a silicon body through diffusion of boron, comprising the steps of: exposing said body to a gas mixture including BBr 3 and O 2 with said gas mixture formed at the coating temperature of BBr 3 and O 2 as contained in a flowing carrier gas such that the molar ratio of O 2 :BBr 3 lies between 20 and 65 so as to thereby form a boron glass layer over said body with a silicon-rich boron layer being formed between said glass layer and body in selected areas of said body; removing said boron glass layer so formed without adversely affecting said silicon-rich boron layer; and heating said body so that at least a portion of the boron from said silicon-rich boron layer is driven into said silicon body to thereby selectively dope said silicon body.
Claim 3
Dependent Claim
45 words
The method as set forth in claim 1 wherein said step of removing said boron glass layer comprises the steps of: partially removing said layer in diluted hydrofluoric acid, treating said layer in hot nitric acid, and finally removing said layer in diluted hydrofluoric acid.
Claim 4
Dependent Claim
82 words
The method as set forth in claim 2 wherein said step of partially removing said glass layer comprises immersing said body for 10 seconds in hydrofluoric acid diluted with water in a ratio of 1:10, said step of treating said layer comprises immersing said body for 10 minutes in concentrated nitric acid heated to 95° C., and said step of finally removing said layer comprises immersing said body for 30 seconds in hydrofluoric acid diluted with water in a ratio of 1:10.
Claim 5
Dependent Claim
30 words
The method as set forth in claim 1 wherein said exposing step takes place between 850° C. and 950° C. and said heating step takes place in an oxidizing atmosphere.
Claim 6
Dependent Claim
35 words
The method as set forth in claim 1 wherein said exposing step takes place between 950° C. and 1000° C. with a minimum of oxygen and said heating step takes place in an inert atmosphere.
Claim 7
Dependent Claim
28 words
The method as set forth in claim 5 wherein during said exposing step said body is briefly exposed to a gas mixture containing oxygen as well as boron.
Claim 8
Dependent Claim
14 words
The method as set forth in claim 7 wherein said inert atmosphere is argon.
Claim 9
Dependent Claim
147 words
In a process of doping silicon bodies through diffusion of boron, the improvement comprising: exposing said bodies in a reaction tube to a gas mixture including BBr 3 and O 2 with said BBr 3 added in an amount between approximately 15 and 30 milligrams/minute and said oxygen added in an amount as related to the amount of BBr 3 added to give a molar ratio of O 2 :BBr 2 between 20 and 65 such that a boron glass layer is formed over each of said bodies with a silicon-rich boron layer being formed between said glass layer and corresponding body in unmasked areas of said body; removing said boron glass layer from said bodies without adversely affecting said silicon-rich boron layer; and heating said bodies so that at least a portion of the boron from said silicon-rich boron layer is driven into said silicon bodies.
Claim 10
Dependent Claim
147 words
In a process of doping silicon bodies through diffusion of boron, the improvement comprising: exposing said bodies in a reaction tube to a gas mixture including BBr 3 and O 2 with said BBr 3 added in an amount between approximately 15 and 30 milligrams/minute and said oxygen added in an amount as related to the amount of BBr 3 added to give a molar ratio of O 2 :BBr 2 between 20 and 65 such that a boron glass layer is formed over each of said bodies with a silicon-rich boron layer being formed between said glass layer and corresponding body in unmasked areas of said body; removing said boron glass layer from said bodies without adversely affecting said silicon-rich boron layer; and heating said bodies so that at least a portion of the boron from said silicon-rich boron layer is driven into said silicon bodies.
Claim 11
Dependent Claim
48 words
The process as set forth in claim 8 wherein said reaction tube has an inner diameter of approximately 10 cm and wherein said gas mixture is transported in a carrier gas having a forward flow between 2 and 5 liters/minute and a backflow between 0.5 and 1 liter/minute.
Claim 12
Dependent Claim
19 words
The process as set forth in claim 9 wherein argon is used as said carrier gas and stabilization gas.
Claim 13
Dependent Claim
61 words
The method as set forth in claim 8 including exposing said bodies in a reaction tube at a temperature of approximately 875° C. to a gas mixture including 3.2 liters of argon/minute and 0.08 liters of oxygen/minute for approximately 15 minutes and then to said gas mixture with an additional 0.08 liters of argon/minute added to it for approximately 20 minutes.
References Cited (Backward Citations)
US3066052A
Cited
US3542609A
Cited
US3577287A
Cited
US3753809A
Cited
US3676231A
Cited
US3806382A
Cited
US4149915A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1984-02-10 | 1984-08-11 | 1985-02-10 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1988-02-10 | 1988-08-11 | 1989-02-10 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1992-02-10 | 1992-08-11 | 1993-02-10 | $7700.00 | Window Closed / Lapsed |