US4251285A
Expired / Lapsed
US
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Diffusion of dopant from optical coating and single step formation of PN junction in silicon solar cell and coating thereon
Assignee: Westinghouse Electric Corp
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Filing: 1979-08-14
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Granted: 1981-02-17
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Expires: 1999-08-14
Abstract
Abstract The PN juncture in a silicon chip and an oxide coating on its surface are simultaneously formed from clear solution derived from titanium alkoxides, water, alcohol, a suitable acid, and a P or N dopant compound by partial hydrolysis and polymerization. The solution is applied to the surface of a silicon chip. The chip is then heated which converts the solution to a solid oxide coating which meets the antireflective optical film requirements and induces the migration of the dopants into the chip, forming a PN junction in the chip. The method also provides deep and uniform junction formation or diffusion without resulting in excessive carrier concentration.
Inventors
- 👤 Bulent E. Yoldas
- 👤 Lubomyra A. Yoldas
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 17:53
CPC Classifications
H; H10; H10F; H10F71/00; H10F77/00; H10F77/30; H10F77/306; H10F77/311; H10F77/315; H10P; H10P32/00; H10P32/10; H10P32/14; H10P32/1408; H10P32/17; H10P32/171; Y; Y02; Y02E; Y02E10/00; Y02E10/50; Y10; Y10S; Y10S252/00; Y10S252/95
Claims Analysis
Total Claims: 23
Claim 1
Independent Claim
62 words
A method of doping silicon comprising forming a coating on said silicon from an alkoxide solution partially hydrolyzed with water, where at least 40% of said coating is titania, said coating containing a dopant selected from the group consisting of boron and phosphorus, and heating said coated silicon above the diffusion temperature of said dopant, thereby diffusing said dopant into said silicon.
Claim 2
Independent Claim
62 words
A method of doping silicon comprising forming a coating on said silicon from an alkoxide solution partially hydrolyzed with water, where at least 40% of said coating is titania, said coating containing a dopant selected from the group consisting of boron and phosphorus, and heating said coated silicon above the diffusion temperature of said dopant, thereby diffusing said dopant into said silicon.
Claim 3
Dependent Claim
17 words
A method according to claim 1 wherein said silicon is N-type and said dopant is P type.
Claim 4
Dependent Claim
11 words
A method according to claim 2 wherein said dopant is boron.
Claim 5
Dependent Claim
16 words
A method according to claim 3 wherein said temperature is about 850° to about 1100° C.
Claim 6
Dependent Claim
18 words
A method according to claim 1 wherein said dopant is diffused to a depth greater than 1 micron.
Claim 7
Dependent Claim
20 words
A method according to claim 1 wherein said coating on said silicon is greater than 100 square centimeters in area.
Claim 8
Dependent Claim
24 words
A method according to claim 1 wherein at least two different coatings containing different dopants are applied to separate well-defined areas of said silicon.
Claim 9
Dependent Claim
20 words
A method according to claim 1 wherein said coating is antireflective and said silicon is part of a photovoltaic cell.
Claim 10
Dependent Claim
144 words
The clear solution which results from mixing ingredients comprising: (A) alkoxide having the general formula M(OR) n where M is selected such that an oxide coating formed from this solution is selected from the group consisting of 40 to 100% TiO 2 , 0 to 25%, SiO 2 , and up to 15% of another metal oxide of a metal which forms an alkoxide, and mixtures thereof, R is alkyl from C 1 to C 6 , and n is the valence of M; (B) about 1.7 to about 8 moles of water per mole of alkoxide; (C) sufficient alcohol to give a solid content of about 0.1 to about 15%; (D) a sufficient amount of a suitable acid to prevent cloudiness; and (E) about 1% to about 50% of a dopant compound selected from the group consisting of boron and phosphorus containing compounds.
Claim 11
Dependent Claim
144 words
The clear solution which results from mixing ingredients comprising: (A) alkoxide having the general formula M(OR) n where M is selected such that an oxide coating formed from this solution is selected from the group consisting of 40 to 100% TiO 2 , 0 to 25%, SiO 2 , and up to 15% of another metal oxide of a metal which forms an alkoxide, and mixtures thereof, R is alkyl from C 1 to C 6 , and n is the valence of M; (B) about 1.7 to about 8 moles of water per mole of alkoxide; (C) sufficient alcohol to give a solid content of about 0.1 to about 15%; (D) a sufficient amount of a suitable acid to prevent cloudiness; and (E) about 1% to about 50% of a dopant compound selected from the group consisting of boron and phosphorus containing compounds.
Claim 12
Independent Claim
198 words
A method of simultaneously doping a silicon chip and forming an oxide coating on its surface comprising: (A) preparing the clear solution which results from mixing ingredients comprising: (a) alkoxide having the general formula M(OR) n where M is selected such thut an oxide coating formed from this solution is selected from the group consisting of 40 to 100% TiO 2 , 0 to 25% SiO 2 , and up to 15% of another metal oxide of a metal which forms an alkoxide, and mixtures thereof, R is alkyl from C 1 to C 6 , and n is the valence of M; (b) about 1.7 to about 8 moles of water per mole of alkoxide; (c) sufficient alcohol to give a solid content of about 0.1 to about 15%; (d) a sufficient amount of a suitable acid to prevent cloudiness; and (e) about 1% to about 50% of a P or N dopant compound selected from the group consisting of boron and phosphorus containing compounds; (B) applying said solution to the surface of said chip; and (C) heating said chip to convert said solution to a solid coating and to diffuse said dopant into said silicon chip.
Claim 13
Independent Claim
198 words
A method of simultaneously doping a silicon chip and forming an oxide coating on its surface comprising: (A) preparing the clear solution which results from mixing ingredients comprising: (a) alkoxide having the general formula M(OR) n where M is selected such thut an oxide coating formed from this solution is selected from the group consisting of 40 to 100% TiO 2 , 0 to 25% SiO 2 , and up to 15% of another metal oxide of a metal which forms an alkoxide, and mixtures thereof, R is alkyl from C 1 to C 6 , and n is the valence of M; (b) about 1.7 to about 8 moles of water per mole of alkoxide; (c) sufficient alcohol to give a solid content of about 0.1 to about 15%; (d) a sufficient amount of a suitable acid to prevent cloudiness; and (e) about 1% to about 50% of a P or N dopant compound selected from the group consisting of boron and phosphorus containing compounds; (B) applying said solution to the surface of said chip; and (C) heating said chip to convert said solution to a solid coating and to diffuse said dopant into said silicon chip.
Claim 14
Dependent Claim
26 words
A method according to claim 10 wherein said dopant compound is selected from the group consisting of boron alkoxides, phosphoric alkoxides, phosphoric acid, and boric acid.
Claim 15
Dependent Claim
24 words
A method according to claim 10 wherein said silicon chip is N-doped and said dopant compound contains boron, whereby a P/N junction is formed.
Claim 16
Dependent Claim
22 words
A method according to claim 12 wherein said heating is at about 850° to about 1100° C. in the absence of oxygen.
Claim 17
Dependent Claim
16 words
A coated silicon chip containing a P/N juncture prepared according to the method of claim 12.
Claim 18
Dependent Claim
21 words
A coated silicon chip according to claim 14 wherein said coating is about 600 to about 750A thick and is antireflective.
Claim 19
Dependent Claim
34 words
A coated silicon chip according to claim 15 wherein said oxide coating includes B 2 O 3 , SiO 2 , or mixtures thereof so as to produce an index of refraction of 2.
Claim 20
Dependent Claim
20 words
A silicon solar cell having a P/N juncture and an antireflective coating prepared according to the method of claim 12.
Claim 21
Dependent Claim
14 words
A method accordng to claim 10 wherein said M ion is about 100% Ti.
Claim 22
Dependent Claim
51 words
A method according to claim 10 wherein said dopant compound is introduced from an alcohol solution of a boron alkoxide hydrolyzed with up to about 1.5 moles of water per mole of alkoxide, and said alcohol solution is added to a titania based solution derived from titanium akoxides, water, and acid.
Claim 23
Dependent Claim
24 words
A method according to claim 10 wherein excess dopant is used so that the resulting coating has an index of refraction of about 2.
References Cited (Backward Citations)
US4101351A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1984-02-17 | 1984-08-18 | 1985-02-17 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1988-02-17 | 1988-08-18 | 1989-02-17 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1992-02-17 | 1992-08-18 | 1993-02-17 | $7700.00 | Window Closed / Lapsed |