US4198262A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Solar cell manufacture
Assignee: Siemens Solar Industries LP
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Filing: 1979-03-29
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Granted: 1980-04-15
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Expires: 1999-03-29
Abstract
Abstract A method for manufacturing solar cells from a silicon wafer having a p-n junction therein and front and back contacts thereon, the improvement comprising washing said wafer with a buffered hydrofluoric acid solution having a pH of from about 3.5 to about 6.5 and containing from about 2 to about 10 weight percent hydrofluoric acid based on the total weight of the solution.
Inventors
- 👤 Charles F. Gay
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-02 05:17
CPC Classifications
H; H10; H10F; H10F77/00; H10F77/20; H10F77/206; H10F77/211; H10F71/00; H10F71/121; Y; Y02; Y02E; Y02E10/00; Y02E10/50; Y02E10/547; Y02P; Y02P70/00; Y02P70/50
Claims Analysis
Total Claims: 5
Claim 1
Independent Claim
117 words
In a method for manufacturing solar cells from a silicon wafer having a p-n junction therein, wherein front and back electrical contacts are formed on said wafer by metallization, said back contact material being chosen so that it penetrates said p-n junction and forms a low resistance ohmic contact through said junction, the improvement comprising washing said electrical contact-bearing wafer with a buffered hydrofluoric acid solution having a pH of from about 3.5 to about 6.5 and containing from about 5 to about 10 weight percent hydrofluoric acid based on the total weight of said solution for a time sufficient to reduce the series resistance of said wafer and to improve the solderability of said electrical contacts.
Claim 2
Dependent Claim
117 words
In a method for manufacturing solar cells from a silicon wafer having a p-n junction therein, wherein front and back electrical contacts are formed on said wafer by metallization, said back contact material being chosen so that it penetrates said p-n junction and forms a low resistance ohmic contact through said junction, the improvement comprising washing said electrical contact-bearing wafer with a buffered hydrofluoric acid solution having a pH of from about 3.5 to about 6.5 and containing from about 5 to about 10 weight percent hydrofluoric acid based on the total weight of said solution for a time sufficient to reduce the series resistance of said wafer and to improve the solderability of said electrical contacts.
Claim 3
Dependent Claim
27 words
A method according to claim 1 wherein said silicon wafer originally contains boron and phosphorous is diffused into said boron containing wafer to establish said p-n junction.
Claim 4
Dependent Claim
45 words
A method according to claim 1 wherein said buffered solution contains from about 5 to about 40 weight percent based on the total weight of said solution of a buffering agent selected from the group consisting of ammonium bifluoride and ammonium fluoride, and combinations thereof.
Claim 5
Dependent Claim
45 words
A method according to claim 2 wherein said buffered solution contains from about 5 to about 40 weight percent based on the total weight of said solution of a buffering agent selected from the group consisting of ammonium bifluoride and ammomium fluoride, and combinations thereof.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1983-04-15 | 1983-10-15 | 1984-04-15 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1987-04-15 | 1987-10-15 | 1988-04-15 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1991-04-15 | 1991-10-15 | 1992-04-15 | $7700.00 | Window Closed / Lapsed |