Process for the manufacture of solar cells
| Title: | Process for the manufacture of solar cells |
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| Patent Number: | 10453,986 |
| Publication Date: | October 22, 2019 |
| Appl. No: | 12/863355 |
| Application Filed: | April 28, 2008 |
| Abstract: | Solar cells are manufactured from P-type doped monocrystalline or polycrystalline silicon ingots by sawing wafers and applying an N-type doping. The wafers can be improved by etching them, especially in a plasma assisted process, with fluorine, carbonyl fluoride, SF6 or NF3. Hereby, the surface is roughened so that the degree of light reflection is reduced, cracks caused from the sawing operation are prevented from proliferation, and glass-like phosphorus-containing oxide coatings caused by phosphorus doping are removed. |
| Inventors: | Riva, Marcello (Hannover, DE) |
| Assignees: | SOLVAY FLUOR GMBH (Hannover, DE) |
| Claim: | 1. A method for manufacturing a solar cell from a silicon wafer having a phosphorus-containing glass-like coating, comprising a step of etching the silicon wafer to roughen the surface of said silicon wafer and to remove the phosphorus-containing glass-like coating with a mixture of only F 2 and nitrogen used as an etching gas; wherein the content of fluorine is from 1% by volume to 22% by volume. |
| Claim: | 2. The method according to claim 1 wherein the silicon wafer is monocrystalline. |
| Claim: | 3. The method according to claim 1 wherein the silicon wafer is polycrystalline. |
| Claim: | 4. The method according to claim 1 wherein the silicon wafer is P-type doped with N-type doped coating. |
| Claim: | 5. The method according to claim 1 wherein the silicon wafer having at least one crack is etched. |
| Claim: | 6. The method according to claim 1 , wherein etching is assisted by remote plasma. |
| Claim: | 7. The method according to claim 1 wherein contact electrodes are applied to the silicon wafer after etching. |
| Claim: | 8. The method according to claim 1 wherein two or more of the solar cells manufactured by said method are assembled to manufacture a solar panel. |
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| Other References: | Leonel R Arana, Nuria de Mas, Raymond Schmidt, Leksander J Franz, Martin A Schmidt and Klays F Jensen, “Isotropic etching of silicon in fluorine gas for MEMS micromachining”, Journal of MIcromechanics and Microengineering, 17 (Jan. 25, 2007), pp. 384-392. cited by examiner Rentsch, J., et al—“Industrial realization of dry plasma etching for psg removal and rear side emitter etching”, 2007, 22nd European Photovoltaic Solar Energy Conference & Exhibition; pp. 1340-1343; XP 002535054; 4 pgs. cited by applicant Tucci, M.—et al—“Dry NF3/O2 Plasma Texturing of Multi-Crystal Silicon”, 21st European Photovoltaic Solar Energy Conference, 2006, XP 007909059; pp. 1250-1253; 4 pgs. cited by applicant Perrin, Jerome, et al—“Mass Spectrometric Study of NF3 Plasma Etching of Silicon”, Plasma Chemistry and Plasma Processing, 1990, vol. 10, No. 4, pp. 571-587; 17 pgs. cited by applicant Loper, G. L., et al—“UV laser-generated fluorine atom etching of polycrystalline Si, Mo and Ti”, Applied Physics Letters, 1985, vol. 46, Issue 7, p. 654-656; 4 pgs. cited by applicant Holland, R.J., et a;—“Thermal & Photochemical Promotion of Silicon & Silicon Dioxide by Carbonyl Difluoride”, Journal of Applied Physics, 1986, vol. 60, Issue 7, pp. 2553-2557; 6 pgs. cited by applicant Loper, G.L., et al—“Fluorine atom production mechanisms from COF2 and NF3 in UV laser”, 1987, Photon, Beam, and Plasma Stimulated Chemical Processes at Surfaces Symposium held in Boston, Massachusetts, U.S.A., Mat. Res. Soc. Symp. Proc., vol. 75, Materials Research Society, pp. 385-393; 9 pgs. cited by applicant Loper, G. L., et al—“Mechanistic aspects of argon fluoride laser etching of Si and Mo with F atom precursors COF2 and NF3”, Proceedings—Electrochemical Society, 1988, vol. 88, Issue No. 10, pp. 130-142; 14 pgs. cited by applicant Conte, G., et al—“The Origin of Macroscopic and Microscopic Defects in a-Si1-xGex:H Alloys for Photovoltaic Applications”, 1988, Eighth E.C. Photovoltaic Solar Energy Conference. Proceedings of the International Conference (EUR 11780), pp. 701-705; vol. 1 of 2 volumes; 6 pgs. cited by applicant Jones, Gregory T., et al—“Automated Array Assembly Task In-depth Study of Silicon Wafer Surface Texturizing”, Science Tech. Aerosp. Report, Department of Energy / Jet Propulsion Lab. Contract No. 955266, Jul. 1979, N80-19618; 72 pgs. cited by applicant Walther, G. , et al—“COF2 as Environmentally Friend Plasma Process Gas for the Solar Industry”, 2008, Secon, 23rd European Photovoltaic Solar Energy Conference & Exhibition, Sep. 2008; 3 pgs. cited by applicant Rentsch, J., et al—“Plasma etching for industrial in-line processing of c-Si solar cells”, Institute of Electrical and Electronics Engineers—IEEE-: Proceedings of 3rd World Conference on Photovoltaic Energy Conversion, May 18, 2003; Joint conference of 13th PV Science & Engineering Conference, 30th IEEE PV Specialists Conference, 18th European PV Solar Energy Conference ; Osaka International Congress Center “Grand Cube”, Osaka, Japan, vol. 2, pp. 1376-1379; 4 pgs. cited by applicant Perrin, Jerome—Section 3.2.2 “Neutral molecule chemistry in etching”, p. 411-412, in “Plasma Processing of Semiconductors”, edited by P. F. Williams, Kluwer Academic Publishers,1997; 7 pgs. cited by applicant Nositschka, W. A., et al—“Dry PSG etching for multicrystalline silicon solar cells”, Photovoltaic Energy Conversion, 2003, Institute of Electrical and Electronics Engineers—IEEE, Proceedings of 3rd World Conference on Photovoltaic Energy Conversion, May 18, 2003, vol. 2, pp. 1348-1351, XP-002535055; 4 pgs. cited by applicant Nositschka, W.A., et al—“Texturisation of multicrystalline silicon solar cells by RIE and plasma etching”, Solar Energy Materials and Solar Cells, 2003, vol. 80, Issue 2, pp. 227-237, 11 pgs. cited by applicant Kastenmeier, B. E. E., et al—“Gas utilization in remote plasma cleaning and stripping applications”, Sep./Oct. 2000, J. Vacuum Sci. Technol. A., vol. 18, Issue 5, pp. 2102-2107; 6 pgs. cited by applicant Walther, G.—“Plasma Etching Technology”, presentation, Secon Semiconductor Equipment GmbH, May 2007; Austria; 20 pgs. cited by applicant U.S. Appl. No. 12/296,139, Anya Pischtiak, et al, filed Oct. 6, 2008. cited by applicant U.S. Appl. No. 12/808,718, Marcello Riva, filed Jun. 17, 2010. cited by applicant U.S. Appl. No. 13/496,498, Marcello Riva et al, filed Mar. 16, 2012. cited by applicant U.S. Appl. No. 13/504,096, Marcello Riva et al, filed Apr. 25, 2012. cited by applicant |
| Primary Examiner: | Nguyen, Cuong B |
| Accession Number: | edspgr.10453986 |
| Database: | USPTO Patent Grants |
| Language: | English |
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