Source: http://www.google.com/patents/US8030118?ie=ISO-8859-1
Timestamp: 2014-09-22 20:22:46
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Matched Legal Cases: ['Application No. 200710193656', 'Application No. 2006', 'Application No. 2007101851256', 'Application No. 200710185124', 'Application No. 200710185123', 'Application No. 200710185124', 'Application No. 07020916', 'Application No. 07020917', 'Application No. 07020918', 'Application No. 07022106', 'Application No. 2006', 'Application No. 2006', 'Application No. 2006', 'Application No. 2006']

Patent US8030118 - Method for producing single crystal silicon solar cell and single crystal ... - Google PatentsSearch Images Maps Play YouTube News Gmail Drive More »Sign in<nobr>Advanced Patent Search</nobr>PatentsA method for producing a single crystal silicon solar cell including the steps of: implanting ions into a single crystal silicon substrate through an ion implanting surface thereof; closely contacting the single crystal silicon substrate and a transparent insulator substrate with each other via a transparent...http://www.google.com/patents/US8030118?utm_source=gb-gplus-sharePatent US8030118 - Method for producing single crystal silicon solar cell and single crystal silicon solar cellAdvanced Patent SearchPublication numberUS8030118 B2Publication typeGrantApplication numberUS 11/976,021Publication dateOct 4, 2011Filing dateOct 19, 2007Priority dateOct 30, 2006Also published asCN101174658A, CN101174658B, EP1921683A2, EP1921683A3, US20080099066, US20110290321Publication number11976021, 976021, US 8030118 B2, US 8030118B2, US-B2-8030118, US8030118 B2, US8030118B2InventorsAtsuo Ito, Shoji Akiyama, Makoto Kawai, Koichi Tanaka, Yuuji Tobisaka, Yoshihiro KubotaOriginal AssigneeShin-Etsu Chemical Co., Ltd.Export CitationBiBTeX, EndNote, RefManPatent Citations (46), Non-Patent Citations (30), Classifications (16), Legal Events (1) External Links: USPTO, USPTO Assignment, EspacenetMethod for producing single crystal silicon solar cell and single crystal silicon solar cellUS 8030118 B2Abstract A method for producing a single crystal silicon solar cell including the steps of: implanting ions into a single crystal silicon substrate through an ion implanting surface thereof; closely contacting the single crystal silicon substrate and a transparent insulator substrate with each other via a transparent electroconductive adhesive while using the ion implanting surface as a bonding surface; curing and maturing the transparent electroconductive adhesive into a transparent electroconductive film; applying an impact to the ion implanted layer to mechanically delaminate the single crystal silicon substrate to leave a single crystal silicon layer; and forming a p-n junction in the single crystal silicon layer.
In case of amorphous silicon solar cells, there is formed an amorphous silicon hydride film on a substrate by decomposing a silane gas by discharge in a vapor phase such as by a plasma CVD method, and diborane, phosphine, and the like as doping gases are added thereto, followed by simultaneous deposition thereof to simultaneously achieve a p-n junction formation process and a film-formation process, and followed by formation of electrodes and a protective film, thereby providing solar cell elements. In an amorphous silicon solar cell, since amorphous silicon as a direct transition type absorbs incident light, the amorphous silicon has a light absorption coefficient which is about one order higher than those of single crystal silicon and polycrystalline silicon (�Solar photovoltaic power generation�, p. 233, by Kiyoshi Takahashi, Yoshihiro Hamakawa and Akio Ushirokawa, Morikita Shuppan, 1980), thereby providing an advantage that a thickness of about 1 μm of an amorphous silicon layer will do which is about a hundredth of that of a crystal-based solar cell. Thus, expectation is significant for amorphous silicon solar cells capable of effectively utilizing resources, in view of the fact that the annual production volume of solar cells has recently exceeded 1 giga-watts in the world and the production volume will be further increased.
As such, there have been conducted various approaches for developing thin-film solar cells by utilizing silicon crystal-based materials (�Solar photovoltaic power generation�, p. 217, by Kiyoshi Takahashi, Yoshihiro Hamakawa, and Akio Ushirokawa, Morikita Shuppan, 1980). For examples there is deposited a polycrystalline thin-film on an alumina substrate, graphite substrate, or the like, by using a trichlorosilane gas, a tetrachlorosilane gas, or the like. The thus deposited film has a lot of crystal defects, and the conversion efficiency is low as it is. Thus, it is required to conduct zone melting to improve crystallinity, so as to increase the conversion efficiency (see JP-A-2004-342909, for example). However, even by conducting such a zone melting method, there has been still left an exemplary problem that photocurrent response characteristics in a longer wavelength range are lowered because crystal grain boundaries cause a leak current and shorten lifetimes of carriers.
Next, the single crystal silicon substrate 11 is closely contacted with the transparent insulator substrate 12 via a transparent electroconductive adhesive 15, while using the ion implanting surface 13 as a bonding surface (stage �c�).
Next, the transparent electroconductive adhesive 15 is cured and matured into a transparent electroconductive film 16, to bond the single crystal silicon substrate 11 and the transparent insulator substrate 12 to each other (stage �d�).
The curing method of the transparent electroconductive adhesive is not particularly limited, and is appropriately selected in conformity to the used materials. For example, it is possible to cure the transparent electroconductive adhesive to strongly bond the single crystal silicon substrate and the transparent insulator substrate to each other, by a method of once heating the transparent electroconductive adhesive to about 250� C. to thereby soften it and then cooling it again, a method of volatilizing a solvent of the adhesive, or the like. Only, this curing treatment is to be conducted under a temperature condition from a room temperature to about 250� C., and no heat treatments are conducted at 300� C. or higher. This is because, when a high-temperature heat treatment at 300� C. or higher is conducted in a state that the single crystal silicon substrate 11 and the transparent insulator substrate 12 are bonded to each other, there is a possibility of occurrence of heat distortion, cracks, debonding, and the like, due to a difference between thermal expansion coefficients of the substrates 11 and 12. In this way, avoidance of a high-temperature heat treatment at 300� C. or higher is also applicable, until completion of delaminative transference from the single crystal silicon substrate 11 in the stage �e� to be described later.
Next, there is applied an impact to the ion implanted layer 14 to mechanically delaminate the single crystal silicon substrate 11 thereat to leave a single crystal silicon layer 17 (stage �e�).
Next, there is formed a diffusion layer having a second conductivity type on the single crystal silicon layer 17, which conductivity type is different from a first conductivity type of the single crystal silicon substrate prepared in the stage �a�, thereby causing the single crystal silicon layer to comprise a silicon layer 21 having a first conductivity type and a silicon layer 22 having a second conductivity type so that a p-n junction is formed (stage �f�).
Note that it is possible to exemplarily conduct polishing called �touch polish� with an extremely small polishing stock removal of 5 to 400 nm, after forming the p-n junction in the above-described manner.
Next, electrodes 23 are formed on the surface of the single crystal silicon layer 17 at the side of the silicon layer 22 having the second conductivity type (stage �g�).
The single crystal silicon solar cell produced by the stages �a� through �g� is a single crystal silicon solar cell 31, which is free of occurrence of heat distortion, debonding, cracks, and the like upon production, which is thin and has an excellent uniformity of film thickness, which is excellent in crystallinity, and which has a single crystal silicon layer on a transparent insulator substrate.
Note that the remaining single crystal silicon substrate after delaminative transference of the single crystal silicon layer 17 therefrom in the stage �e�, can be again utilized as a single crystal silicon substrate 11, by conducting a treatment of polishing, smoothing, and removing the rough surface and the ion implanted layer after delamination, and by conducting an ion implantation treatment repeatedly. Since it is unnecessary in the method for producing a single crystal silicon solar cell of the present invention to heat the single crystal silicon substrate to a temperature of 300� C. or higher throughout the ion implantation stage to the delamination stage, there is no possibility that defects induced by oxygen are introduced into the single crystal silicon substrate. As such, it becomes possible to conduct delaminative transference as many as 100 or more times, in case of firstly adopting a single crystal silicon substrate having a thickness slightly less than 1 mm and setting the film thickness of a single crystal silicon layer 17 to be 5 μm.
Subsequently, there was formed a coating of tin oxide doped with antimony on the quartz glass substrate 12 by spraying; followed by application of an electroconductive material thereto, which electroconductive material included 80 wt % of electroconductive particles comprising indium tin oxide and having an averaged particle diameter of 1.0 μm, and a hydrolytic polycondensate of alkoxysilane and tetraalkoxysilane, as well as a solvent of isopropyl alcohol for dissolving them therein; thereby establishing a transparent electroconductive adhesive. The single crystal silicon 11 and the quartz glass substrate 12 were closely contacted with each other through this transparent electroconductive adhesive 15 (stage (�c�).
The thus bonded substrates were subjected to a heat treatment at 250� C. for 2 hours, and cooled down to a room temperature to thereby cure the transparent electroconductive adhesive 15 as a transparent electroconductive film 16, thereby strongly bonding the single crystal silicon 11 and the quartz glass substrate 12 to each other (stage �d�).
Next, there was blown a high pressure nitrogen gas onto the vicinity of the joining interface, followed by conduction of mechanical delamination for delaminating the single crystal silicon substrate in a manner to initiate the delamination from the blown surface (stage �e�). At this time, the delamination was conducted after suckingly attaching auxiliary substrates from the back to the single crystal silicon substrate and quartz glass substrate, respectively. Further, irradiation was conducted onto the delaminatedly transferred single crystal silicon by flash-lamp annealing under a condition that the surface of the single crystal silicon was momentarily brought to a temperature of 700� C. or higher, thereby healing hydrogen implantation damages.
Coated onto the whole surface of the single crystal silicon layer 17 was a diffusion paste containing ethyl cellosolve including phosphosilicate glass as a thickener, by screen printing. Irradiation was conducted thereto by a flash lamp such that the surface was momentarily heated to 600� C. or higher, thereby forming a p-n junction interface at a joining depth of about 1 μm (stage �f�).
This diffusion paste was subjected to removal and cleaning by hydrofluoric acid, acetone, and isopropyl alcohol, followed by formation of silver electrodes 23 by vacuum deposition and patterning (stage �g�). Subsequently, there was formed a collector electrode pattern of silver by a vacuum deposition method while adopting a metal mask. There was then formed a protective coating of silicon nitride over the surface by reactive sputtering, except for portions of pickup electrodes.
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No. 12/073,437; mailed Nov. 27, 2009.30Takahashi et al., "Solar photovoltaic power generation", Morikita Shuppan, pp. 217 & 233, 1980.Classifications U.S. Classification438/73, 438/455, 438/237, 438/458, 438/528, 257/E21.002International ClassificationH01L21/00Cooperative ClassificationY02E10/547, H01L31/022466, H01L31/1884, H01L31/1896, H01L31/068, Y02B10/10European ClassificationH01L31/068, H01L31/18J, H01L31/18R2Legal EventsDateCodeEventDescriptionNov 20, 2007ASAssignmentOwner name: SHIN-ETSU CHEMICAL CO., LTD., JAPANFree format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNORS:ITO, ATSUO;AKIYAMA, SHOJI;KAWAI, MAKOTO;AND OTHERS;REEL/FRAME:020147/0943;SIGNING DATES FROM 20071019 TO 20071023Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNORS:ITO, ATSUO;AKIYAMA, SHOJI;KAWAI, MAKOTO;AND OTHERS;SIGNING DATES FROM 20071019 TO 20071023;REEL/FRAME:020147/0943RotateOriginal ImageGoogle Home - Sitemap - USPTO Bulk Downloads - Privacy Policy - Terms of Service - About Google Patents - Send FeedbackData provided by IFI CLAIMS Patent Services©2012 Google