GB2079537A - A method for applying an anti-reflection coating and an electrode to a solar cell - Google Patents
A method for applying an anti-reflection coating and an electrode to a solar cell Download PDFInfo
- Publication number
- GB2079537A GB2079537A GB8121103A GB8121103A GB2079537A GB 2079537 A GB2079537 A GB 2079537A GB 8121103 A GB8121103 A GB 8121103A GB 8121103 A GB8121103 A GB 8121103A GB 2079537 A GB2079537 A GB 2079537A
- Authority
- GB
- United Kingdom
- Prior art keywords
- coating
- layer
- solar cell
- cell
- nickel
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Granted
Links
- 238000000576 coating method Methods 0.000 title claims description 45
- 239000011248 coating agent Substances 0.000 title claims description 44
- 238000000034 method Methods 0.000 title claims description 31
- PXHVJJICTQNCMI-UHFFFAOYSA-N Nickel Chemical compound [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 claims abstract description 52
- 229910052759 nickel Inorganic materials 0.000 claims abstract description 26
- 229910000679 solder Inorganic materials 0.000 claims abstract description 11
- 238000005530 etching Methods 0.000 claims abstract description 8
- 238000007772 electroless plating Methods 0.000 claims abstract description 3
- 210000004027 cell Anatomy 0.000 claims description 85
- 239000000243 solution Substances 0.000 claims description 18
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 claims description 16
- 230000000873 masking effect Effects 0.000 claims description 10
- 238000007747 plating Methods 0.000 claims description 8
- 239000000377 silicon dioxide Substances 0.000 claims description 8
- 229910044991 metal oxide Inorganic materials 0.000 claims description 7
- 150000004706 metal oxides Chemical class 0.000 claims description 7
- RTAQQCXQSZGOHL-UHFFFAOYSA-N Titanium Chemical compound [Ti] RTAQQCXQSZGOHL-UHFFFAOYSA-N 0.000 claims description 5
- 239000010936 titanium Substances 0.000 claims description 5
- 229910052719 titanium Inorganic materials 0.000 claims description 5
- NLXLAEXVIDQMFP-UHFFFAOYSA-N Ammonia chloride Chemical compound [NH4+].[Cl-] NLXLAEXVIDQMFP-UHFFFAOYSA-N 0.000 claims description 4
- 239000010426 asphalt Substances 0.000 claims description 4
- 229910052751 metal Inorganic materials 0.000 claims description 4
- 239000002184 metal Substances 0.000 claims description 4
- 239000005456 alcohol based solvent Substances 0.000 claims description 3
- 239000006117 anti-reflective coating Substances 0.000 claims description 3
- USFZMSVCRYTOJT-UHFFFAOYSA-N Ammonium acetate Chemical compound N.CC(O)=O USFZMSVCRYTOJT-UHFFFAOYSA-N 0.000 claims description 2
- 239000005695 Ammonium acetate Substances 0.000 claims description 2
- 229910021586 Nickel(II) chloride Inorganic materials 0.000 claims description 2
- 229940043376 ammonium acetate Drugs 0.000 claims description 2
- 235000019257 ammonium acetate Nutrition 0.000 claims description 2
- 235000019270 ammonium chloride Nutrition 0.000 claims description 2
- QMMRZOWCJAIUJA-UHFFFAOYSA-L nickel dichloride Chemical compound Cl[Ni]Cl QMMRZOWCJAIUJA-UHFFFAOYSA-L 0.000 claims description 2
- 238000012216 screening Methods 0.000 claims description 2
- 238000005507 spraying Methods 0.000 claims description 2
- DGAQECJNVWCQMB-PUAWFVPOSA-M Ilexoside XXIX Chemical compound C[C@@H]1CC[C@@]2(CC[C@@]3(C(=CC[C@H]4[C@]3(CC[C@@H]5[C@@]4(CC[C@@H](C5(C)C)OS(=O)(=O)[O-])C)C)[C@@H]2[C@]1(C)O)C)C(=O)O[C@H]6[C@@H]([C@H]([C@@H]([C@H](O6)CO)O)O)O.[Na+] DGAQECJNVWCQMB-PUAWFVPOSA-M 0.000 claims 1
- 229960001040 ammonium chloride Drugs 0.000 claims 1
- 230000001235 sensitizing effect Effects 0.000 claims 1
- 229910052708 sodium Inorganic materials 0.000 claims 1
- 239000011734 sodium Substances 0.000 claims 1
- 238000007598 dipping method Methods 0.000 abstract description 2
- 238000009713 electroplating Methods 0.000 abstract description 2
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 description 18
- 229910052710 silicon Inorganic materials 0.000 description 18
- 239000010703 silicon Substances 0.000 description 18
- KRHYYFGTRYWZRS-UHFFFAOYSA-N Fluorane Chemical compound F KRHYYFGTRYWZRS-UHFFFAOYSA-N 0.000 description 10
- GWEVSGVZZGPLCZ-UHFFFAOYSA-N Titan oxide Chemical compound O=[Ti]=O GWEVSGVZZGPLCZ-UHFFFAOYSA-N 0.000 description 6
- 230000008569 process Effects 0.000 description 6
- 238000000151 deposition Methods 0.000 description 5
- 238000004519 manufacturing process Methods 0.000 description 5
- 230000003595 spectral effect Effects 0.000 description 5
- 235000012431 wafers Nutrition 0.000 description 5
- 230000008901 benefit Effects 0.000 description 4
- 238000010438 heat treatment Methods 0.000 description 4
- 239000000203 mixture Substances 0.000 description 4
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Chemical compound O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 4
- 230000015572 biosynthetic process Effects 0.000 description 3
- 230000008021 deposition Effects 0.000 description 3
- 230000004907 flux Effects 0.000 description 3
- 239000007788 liquid Substances 0.000 description 3
- 239000000463 material Substances 0.000 description 3
- 229920002120 photoresistant polymer Polymers 0.000 description 3
- 238000012545 processing Methods 0.000 description 3
- 239000004408 titanium dioxide Substances 0.000 description 3
- 238000001771 vacuum deposition Methods 0.000 description 3
- 239000008367 deionised water Substances 0.000 description 2
- 229910021641 deionized water Inorganic materials 0.000 description 2
- FDWREHZXQUYJFJ-UHFFFAOYSA-M gold monochloride Chemical compound [Cl-].[Au+] FDWREHZXQUYJFJ-UHFFFAOYSA-M 0.000 description 2
- ORUIBWPALBXDOA-UHFFFAOYSA-L magnesium fluoride Chemical compound [F-].[F-].[Mg+2] ORUIBWPALBXDOA-UHFFFAOYSA-L 0.000 description 2
- 229910001635 magnesium fluoride Inorganic materials 0.000 description 2
- 230000003647 oxidation Effects 0.000 description 2
- 238000007254 oxidation reaction Methods 0.000 description 2
- 238000002310 reflectometry Methods 0.000 description 2
- 235000012239 silicon dioxide Nutrition 0.000 description 2
- 239000002904 solvent Substances 0.000 description 2
- 238000009987 spinning Methods 0.000 description 2
- 239000007921 spray Substances 0.000 description 2
- 238000009718 spray deposition Methods 0.000 description 2
- 238000010301 surface-oxidation reaction Methods 0.000 description 2
- UOCLXMDMGBRAIB-UHFFFAOYSA-N 1,1,1-trichloroethane Chemical compound CC(Cl)(Cl)Cl UOCLXMDMGBRAIB-UHFFFAOYSA-N 0.000 description 1
- DDFHBQSCUXNBSA-UHFFFAOYSA-N 5-(5-carboxythiophen-2-yl)thiophene-2-carboxylic acid Chemical compound S1C(C(=O)O)=CC=C1C1=CC=C(C(O)=O)S1 DDFHBQSCUXNBSA-UHFFFAOYSA-N 0.000 description 1
- GRYLNZFGIOXLOG-UHFFFAOYSA-N Nitric acid Chemical class O[N+]([O-])=O GRYLNZFGIOXLOG-UHFFFAOYSA-N 0.000 description 1
- 229910052581 Si3N4 Inorganic materials 0.000 description 1
- 229910003087 TiOx Inorganic materials 0.000 description 1
- 238000002835 absorbance Methods 0.000 description 1
- 239000002253 acid Substances 0.000 description 1
- 230000004888 barrier function Effects 0.000 description 1
- 239000008366 buffered solution Substances 0.000 description 1
- 238000003486 chemical etching Methods 0.000 description 1
- 239000003795 chemical substances by application Substances 0.000 description 1
- 239000008199 coating composition Substances 0.000 description 1
- 238000010276 construction Methods 0.000 description 1
- 239000000356 contaminant Substances 0.000 description 1
- 238000001816 cooling Methods 0.000 description 1
- 238000005520 cutting process Methods 0.000 description 1
- 238000000354 decomposition reaction Methods 0.000 description 1
- 230000001419 dependent effect Effects 0.000 description 1
- 238000009792 diffusion process Methods 0.000 description 1
- 239000007772 electrode material Substances 0.000 description 1
- 238000000313 electron-beam-induced deposition Methods 0.000 description 1
- 239000002803 fossil fuel Substances 0.000 description 1
- PCHJSUWPFVWCPO-UHFFFAOYSA-N gold Chemical compound [Au] PCHJSUWPFVWCPO-UHFFFAOYSA-N 0.000 description 1
- 239000010931 gold Substances 0.000 description 1
- 229910052737 gold Inorganic materials 0.000 description 1
- IZLAVFWQHMDDGK-UHFFFAOYSA-N gold(1+);cyanide Chemical compound [Au+].N#[C-] IZLAVFWQHMDDGK-UHFFFAOYSA-N 0.000 description 1
- 238000000227 grinding Methods 0.000 description 1
- 238000007737 ion beam deposition Methods 0.000 description 1
- 230000005012 migration Effects 0.000 description 1
- 238000013508 migration Methods 0.000 description 1
- 238000012544 monitoring process Methods 0.000 description 1
- 229910021421 monocrystalline silicon Inorganic materials 0.000 description 1
- 230000003287 optical effect Effects 0.000 description 1
- 238000002360 preparation method Methods 0.000 description 1
- 230000001105 regulatory effect Effects 0.000 description 1
- 239000004065 semiconductor Substances 0.000 description 1
- HQVNEWCFYHHQES-UHFFFAOYSA-N silicon nitride Chemical compound N12[Si]34N5[Si]62N3[Si]51N64 HQVNEWCFYHHQES-UHFFFAOYSA-N 0.000 description 1
- QGMRQYFBGABWDR-UHFFFAOYSA-N sodium;5-ethyl-5-pentan-2-yl-1,3-diazinane-2,4,6-trione Chemical compound [Na+].CCCC(C)C1(CC)C(=O)NC(=O)NC1=O QGMRQYFBGABWDR-UHFFFAOYSA-N 0.000 description 1
- 238000003892 spreading Methods 0.000 description 1
- 230000007480 spreading Effects 0.000 description 1
- 238000004544 sputter deposition Methods 0.000 description 1
- 230000003319 supportive effect Effects 0.000 description 1
- SDVHRXOTTYYKRY-UHFFFAOYSA-J tetrasodium;dioxido-oxo-phosphonato-$l^{5}-phosphane Chemical compound [Na+].[Na+].[Na+].[Na+].[O-]P([O-])(=O)P([O-])([O-])=O SDVHRXOTTYYKRY-UHFFFAOYSA-J 0.000 description 1
- 238000005979 thermal decomposition reaction Methods 0.000 description 1
- XOLBLPGZBRYERU-UHFFFAOYSA-N tin dioxide Chemical compound O=[Sn]=O XOLBLPGZBRYERU-UHFFFAOYSA-N 0.000 description 1
- 229910001887 tin oxide Inorganic materials 0.000 description 1
- HLLICFJUWSZHRJ-UHFFFAOYSA-N tioxidazole Chemical compound CCCOC1=CC=C2N=C(NC(=O)OC)SC2=C1 HLLICFJUWSZHRJ-UHFFFAOYSA-N 0.000 description 1
- 238000002834 transmittance Methods 0.000 description 1
- 230000000007 visual effect Effects 0.000 description 1
Classifications
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L31/00—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
- H01L31/02—Details
- H01L31/0224—Electrodes
- H01L31/022408—Electrodes for devices characterised by at least one potential jump barrier or surface barrier
- H01L31/022425—Electrodes for devices characterised by at least one potential jump barrier or surface barrier for solar cells
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L21/00—Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
- H01L21/02—Manufacture or treatment of semiconductor devices or of parts thereof
- H01L21/04—Manufacture or treatment of semiconductor devices or of parts thereof the devices having potential barriers, e.g. a PN junction, depletion layer or carrier concentration layer
- H01L21/18—Manufacture or treatment of semiconductor devices or of parts thereof the devices having potential barriers, e.g. a PN junction, depletion layer or carrier concentration layer the devices having semiconductor bodies comprising elements of Group IV of the Periodic Table or AIIIBV compounds with or without impurities, e.g. doping materials
- H01L21/28—Manufacture of electrodes on semiconductor bodies using processes or apparatus not provided for in groups H01L21/20 - H01L21/268
- H01L21/283—Deposition of conductive or insulating materials for electrodes conducting electric current
- H01L21/288—Deposition of conductive or insulating materials for electrodes conducting electric current from a liquid, e.g. electrolytic deposition
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L31/00—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
- H01L31/04—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof adapted as photovoltaic [PV] conversion devices
- H01L31/06—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof adapted as photovoltaic [PV] conversion devices characterised by potential barriers
- H01L31/068—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof adapted as photovoltaic [PV] conversion devices characterised by potential barriers the potential barriers being only of the PN homojunction type, e.g. bulk silicon PN homojunction solar cells or thin film polycrystalline silicon PN homojunction solar cells
- H01L31/0682—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof adapted as photovoltaic [PV] conversion devices characterised by potential barriers the potential barriers being only of the PN homojunction type, e.g. bulk silicon PN homojunction solar cells or thin film polycrystalline silicon PN homojunction solar cells back-junction, i.e. rearside emitter, solar cells, e.g. interdigitated base-emitter regions back-junction cells
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E10/00—Energy generation through renewable energy sources
- Y02E10/50—Photovoltaic [PV] energy
- Y02E10/547—Monocrystalline silicon PV cells
Landscapes
- Engineering & Computer Science (AREA)
- Computer Hardware Design (AREA)
- Microelectronics & Electronic Packaging (AREA)
- Power Engineering (AREA)
- Physics & Mathematics (AREA)
- Condensed Matter Physics & Semiconductors (AREA)
- General Physics & Mathematics (AREA)
- Sustainable Development (AREA)
- Life Sciences & Earth Sciences (AREA)
- Electromagnetism (AREA)
- Sustainable Energy (AREA)
- Manufacturing & Machinery (AREA)
- Chemical & Material Sciences (AREA)
- Crystallography & Structural Chemistry (AREA)
- Photovoltaic Devices (AREA)
- Chemically Coating (AREA)
Abstract
The surface 12 of a solar cell is coated with an anti-reflection layer 14, which is then masked to expose areas corresponding to the desired electrode pattern. The exposed parts of the anti-reflection layer are removed by etching, the exposed surface of the cell is sensitised and an electrode pattern 18 of nickel is applied by electroless plating. The mask is then removed and the electrodes thickened (20) by solder dipping or electroplating. <IMAGE>
Description
SPECIFICATION
A method for applying an anti-reflection coating to a solar cell
The present invention relates to solar cells and in particular to solar cells having an antireflection coating which is applied to the solar cell prior to electroding.
Photovoltaic devices such as silicon solar cells promise a viable alternative to non-replenishable fossil fuel energy generation. Light energy (photons) incident on a solar cell's surface must enter and be absorbed within the cell to be converted to electrical energy.
The efficiency of the solar cell is directly proportional to the amount of light absorbed by the cell.
Depending upon the particular cell fabrication process, the surface of the solar cell may be substantially reflective of light energy, reducing the solar cell's efficiency. Polished silicon, for example, may have a reflectivity of 40% in the spectral region of 0.35 and 1.2 microns. The problem is well recognized in the art and numerous solutions have been employed. A known effective technique for reducing the unwanted reflection is an antireflection layer in contact with the solar cell's surface. The anti-reflection (hereinafter A-R) layer is selected to coordinate its index of refraction, thickness and transmittance characteristics to surface reflection characteristics and the spectral region of interest.For silicon solar cells having a principal spectral absorbance between 0.35 and 1.2 microns, metal oxides such as tin oxide, titanium dioxide and magnesium fluoride are known anti-reflective coatings. Typically these oxide layers are applied to the cell's surface after the cell fabrication has been completed, coating virtually the entire cell surface including the cell's electrodes. Applying the A-R coating after the completion of the cell restricts the temperature at which the A-R coating may be applied or treated. In contrast to the typical coating sequence, the present invention teaches an
A-R coating method where an A-R layer precedes the electroding of the solar cell, avoiding the temperature limitations of the aforedescribed prior art process.The process is of further advantage in permitting electrical contact to the cell's electrode after the A-R coating, facilitating automated production of solar cells and solar panel assembly.
The art has generally recognized the advantage of exposing at least a portion of the solar cell's electrodes through the A-R coating. In
U.S. Patent 3,949,463, for example, Lindmayer et al teach a method for applying an A-R coating to a silicon solar cell where the A-R coating does not overcoat the cell's current collecting electrode. The technique is further exemplified in U.S. Patent 3,904,453 where Bevesz et al use photolithographic techniques in the formation of solar cell electrodes which are not overcoated with the cell's A-R coating.
The present invention concerns an improved solar cell having an A-R coating which is applied to the cell prior to constructing the cell's electrodes. Junction diffused silicon wafers are coated with an A-R layer by either spin-on coating or spray deposition, both techniques employing a heating of the cell at about 200 C to about 300 C. An electrode pattern is masked onto the A-R coated surface and the oxide is removed from the unmasked regions by chemical etching means to expose the solar cell's surface. The etched region is contacted with an electroless nickel sensitizer and plated with a layer of electroless nickel plating. The electrode pattern mask is then removed and the nickel plated electrodes are contacted with solder flux and molten solder which forms a layered nickel/soider electrode interdispersed through the A-R coating.The process taught herein permits heat treatment/heat processing of the
A-R coating and facilitates electrical connections to the A-R coated cell.
In the drawing, where like components are commonly designated, Figs. 1 to 3 illustrate cross-sectional views of the solar cell during successive steps in the fabrication technique of the present invention.
In Fig. 1, a silicon wafer 8 having a first type conductivity region 10 which may comprise P-type or N-type silicon, is diffused to form a region 12 of conductivity type opposite to that of region 10, forming a semiconductor junction otherwise termed a P-N (or
N-P) junction in the region of the interface between regions 10 and 12. The diffusion and junction forming processes are well known in the art. Furthermore, the present inventive A-R coating is operable for either N on P or P on N type cells. In a preferred embodiment, diffused layer 12 extends a relatively short distance into the wafer to form a shallow junction, less than about 0.5 microns in depth.
The diffused cell is then optionally etched in a buffered solution of hydrofluoric acid to remove surface oxidation and possible adsorbed contaminants. The cell is then coated with an A-R layer 14 comprising a metal oxide selected from titanium dioxide (TiOx), silicon dioxide (SiOx), magnesium fluoride, and silicon nitride. As recognized by those of the art, the precise oxidation state of the A-R layer 14 may vary dependent upon the metal oxide used and its preparation conditions; however, oxidation state variations are compensated for in adjusting the thickness of the layer to provide the desired optical properties of the A-R layer.
The formation of A-R layer 14 is, itself, known in the art, and may comprise the alternative techniques described hereinbelow.
The thickness and refractive index of the particular A-R coating utilized are approximated by the theoretical relationship for constructive interference in the A-R coating; d = A/4n where d is the approximate thickness of the
A-R layer, A is wavelength, and n is the refractive index of the A-R coating material.
Spin-On Coating: Layer 14 may be formed by applying an amount of spin-on coating material such as a solution of titanium and silica in alcohol based solvent, commercially available from Emulsiton Corporation under the trade name of "Titanium Silica Film C".
The coating is applied by the known technique of contacting the cell surface with the coating liquid and spinning the cell in commercial photoresist spinner means. Layer thickness is controlled by regulating the amount of liquid applied to the surface and the spinning speed which controls the centrifugal liquid spreading force. Approximate regulation of the layer thickness may be provided by monitoring the interference color of the layer, whereby a deep blue reflection color is indicia of an appropriate thickness for the
A-R coating. The spin-on coated layer is then densified by heat treating the cell at a temperature ranging from about 200 C to about 4004C for a time ranging from about 15 min.
to about 30 min.
Spray Deposition: The A-R layer may be fabricated by thermal decomposition of a solution containing a metal solute which will decompose to the desired metal oxide upon heating. Spraying (or misting) the solution onto a heated cell is a conventional deposition technique which provides a controlled growth of the metal oxide A-R layer. Particular spray solution compositions, spray rates and decomposition temperatures are known in the art and, as is the case with each of the A-R layer compositions recited herein, constitute no part of the present invention.
Vacuum Deposition: Several alternative vacuum deposition techniques are known for depositing metal oxide for forming the A-R coating including sputtering, electron beam and ion beam deposition. Although generally more costly, vacuum deposition techniques generally facilitate accurate control over layer thickness.
Each A-R layer construction technique taught herein requires elevated temperature processing which, for cells having electrodes previously constructed onto the cell's surface, may cause temperature damage to the electrode itself or migration of the electrode material into and through the junction barrier, particularly when the junction is of the shallow type where junction regions are relatively near the electrode surface.
The A-R coated surface is then masked to expose only that area of the cell surface which corresponds to the desired electrode pattern.
Accordingly a layer 16 may alternatively comprise a silk screened asphalt based ink mask patterned onto A-R layer 14 or a photoresist material which has been patterned by photolithographic means to provide a masking layer exposing a region of A-R layer 14 which corresponds to the desired electrode pattern.
The masked surface is then contacted with an etchant chosen to provide selective etching of the particular A-R coating composition employed. For example, where A-R coating 14 comprises a layer of Tit,, fabricated by heat treated spin-on deposition, an etching solution of buffered hydroflouric acid is used to selectively remove the A-R coating in the unmasked regions of the cell surface. Referring to Fig. 2, it is to be recognized that the etching solution is chosen to selectively etch the A-R coating in preference to the underlying silicon layer 12. Furthermore, the solution concentration of the etchant is selected to minimize etchant under-cutting of the mask.
Accordingly, the etching solution removes the unmasked regions of A-R layer 14 which correspond to the desired electrode pattern, exposing the underlying silicon surface 12'.
The cell is then prepared for plating by contacting at least the exposed silicon regions 12' with an electroless nickel sensitizer such as gold cyanide or gold chloride, for example.
The cell is then subjected to electroless nickel plating which comprises contacting at least the sensitized exposed silicon regions with an electroless nickel plating solution to electrolessly plate a layer of nickel 18 onto at least the sensitized exposed silicon surface 12'. Nickel layer 18 in the region contacting the formerly exposed silicon surface is about 0.1 microns in thickness.
Subsequent to the electroless nickel deposition, masking layer 16 is removed using a suitable solvent. The removal of masking layer 16 further removes stray nickel deposition which may at least partially overcoat masking layer 16. Referring to Fig. 3, the removal of masking layer 16 produces a cell having an
A-R coating 14 and an inter-dispersed electrode 18. In a preferred embodiment, the cell is heat treated at a temperature ranging from about 250"C to about 350"C to improve the adherence of the electroless nickel layer 18 to the underlying silicon 12.
Electrolessly deposited nickel layer 18 is insufficiently conductive to serve as a suitable current carrying electrode for most solar cell applications. Accordingly, a conduction supportive electrode layer 20 comprising a relatively high electronconductivity metal may be formed by solder dipping, electroplating or the like. In a preferred embodiment, the surface area of the cell comprising at least the nickel electrode 18 is contacted first with a solder flux agent and then with molten solder to form layer 20 comprising solder. In an alternative embodiment prior to the aforedescribed addition of a conduction supporting electrode layer, a generally circular outer circumferential region of both surfaces of the silicon cell is etched using an etchant comprising a mixture of hydrofluoric and nitric acids.This process of edge region etching reduces the probability of edge region leakage currents and is well known in the art. A suitable masking pattern, generally circular and slightly less in diameter than the generally circular solar cell may be used to confine the etching to the outer circumferential edge regions of the cell.
An ohmic electrode generally designated 22 may be formed concurrent to the formation of layers 18 and 20 comprising a first region 1 8' layer of electroless nickel and a second region layer 20' comprising solder for example. As taught with respect to layer 18, layer 22 may preferably be heat treated to increase its adherence to silicon layer 10.
As readily recognized from the teaching of the present specification, this invention is of advantage in permitting heat treatment of the cell after application of the A-R coating and of further advantage in facilitating electrical connection to the A-R coated cell. To assist one skilled in the art, the following example details a particular embodiment of the present invention.
Example
A 5.6 cm diameter N-type single crystal silicon wafer was diffused to form a P-N junction having a relatively shallow junction depth of about 0.3 microns. The diffused wafer was then cleaned in a solution of hydrofluoric acid to remove surface oxidation, rinsed in distilled deionized water, and blown dry. The cleaned cell was then placed on a photoresist spinner and, using an eye dropper, an amount of a solution of titanium/silica, commercially available from the Emulsitone Corporation located in Whippany, New
Jersey, was applied to the cell's junction surface. The solution was spin coated at approximately 3,500 rpm for about 10 seconds.
The cell was then heat treated at a temperature of about 200 C to cure and densify the
A-R coating. After cooling, the cell's coating was visually observed to be deep blue in color having a relatively hard, mar-resistant surface.
The A-R coated cell was then masked by silk screening an asphalt based ink, patterned to expose the A-R layer only in a region to correspond to the desired electrode pattern.
The mask pattern was baked at about 1 00 C to cure the asphalt based ink and assure the adherence of the mask during the subsequent processing steps. The desired electrode pattern was a central, tapered width bus, tapering from about 4 mm near one circumference of the cell to about 2 mm near the diametrically opposed circumference of the cell. Eighteen grid line electrodes, generally perpendicular to the bus and approximately equally spaced, were about 0.3 mm in width. The masked surface was then immersed in a dilute, buffered hydrofluoric acid etch comprising a well known etchant mixture of 15 parts by weight of ammonium fluoride and eight parts water, this being mixed in a ratio of 4 to 1 with hydrofluoric acid. The etchant removed the TiOX A-R layer in the exposed (unmasked) areas, exposing the underlying silicon layer.
Visual observance of the surface revealed virtually no undercutting or lifting of the mask.
The cell was then immersed in an electroless gold sensitizer comprising 50 ml hydrofluoric acid, 50 ml of 0.5% w/v of gold chloride and 900 ml of water which solution coated both the etched surface and the back of the cell (the N-type surface). The sensitized cell was then immersed in an electroless nickel plating solution comprising 65 gm ammonium acetate, 50 gm of ammonium chloride, 30 ml of nickel chloride and 10 gm of sodium hypophosphate. Electroless plating continued for about 10 minutes, whereafter the cell was rinsed in distilled deionized water and blown dry. The masking layer was then removed from the cell in a chloronated solvent such as
Inhibisol, a trade name of the Pentone Corporation of Tenafly, New Jersey.The removal of the mask also removed any stray nickel deposit, leaving essentially the desired grid pattern on the cell's top surface and an approximately full surface coverage of the bottom (Ntype) surface. The outer circumferential region of each surface was then ground to minimize leakage current paths through the cell's edge.
The cell was then heat treated at about 300 C for about 15 minutes to improve the adherence of the nickel to the silicon and alleviate edge grinding work damage. The cell was then immersed in solder flux and dipped into a molten solder bath which adhered to the nickel plated electrode areas of both surfaces, completing the fabrication of the cell.
The cell's reflectivity characteristics were determined using a Beckman Model 4tDK-1a spectrometer fitted with an integrating sphere for measuring total spectral and diffuse reflection. The cell having an A-R coating in accordance with the present invention had an average reflectance of about 3% in the spectral region of about .4 microns to about 1.1 microns as compared to a typical reflectance of 30% for conventionally prepared cells.
Claims (12)
1. A method of applying an anti-reflective coating and an electrode pattern to a solar cell surface, which comprises:
coating at least said surface with an antireflection layer of a metal oxide;
masking a portion of said coated surface to form an electrode pattern in at least a portion of said surface which remains unmasked;
etching said coating in the unmasked portion of said surface to remove said oxide coating;
sensitizing at least said etched region of
said solar cell surface;
electrolessly plating a layer comprising
nickel onto at least said sensitized region of
said solar cell surface;
removing said masking from said solar cell
surface whereby said nickel layer remains only
in said electrode pattern;
coating said nickel layer with a layer of
conduction supporting metal.
2. A method according to claim 1 wherein
said anti-reflection coating comprises an oxide
of titanium/silica.
3. A method according to claim 2 wherein
said anti-reflection oxide is formed by spin-on
coating said surface with a solution of titani
um/silica in an alcohol based solvent.
4. A method according to claim 3 wherein said spin-on coating is subsequently heat
treated at a temperature ranging from about 200go to about 400"C for a period ranging
from about 15 minutes to about 30 minutes.
5. A method according to claim 2 wherein said oxide coating is formed by spraying a
solution of titanium/silica in an alcohol based
solvent onto a heated cell surface.
6. A method according to any one of the
preceding claims wherein said masking com prises screening an asphalt based ink, coating
a portion of at least one surface of said solar
cell, which coating is patterned to expose an
area of said surface which corresponds to
expose an area of said surface which corre sponds to an electrode pattern for said solar
cell.
7 A method according to any one of the
preceding claims wherein said electroless
nickel plating comprises contacting at least said etched surface and a bottom surface of
said solar cell with an electroless plating solu
tion comprising ammonium acetate, ammon
ium chloride, nickel chloride and sodium hy
pophosphate.
8. A method according to claim 7 wherein
said plating produces a layer of nickel ranging
in thickness from about 0.08 microns to
about 1.2 microns.
9. A method according to claim 8 wherein said nickel layer is heat treated at a tempera
ture ranging from about 250 C to about 350 C for a time ranging from about 10
minutes to about 30 minutes.
10. A method according to any one of the preceding claims wherein said conduction
supporting metal comprises solder.
11. A method according to claim 1 sub
stantially as hereinbefore described with refer
ence to the Example.
12. A solar cell whenever an anti-reflective
coating and an electrode pattern have been
applied thereto by the method according to
any one of the preceding claims.
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US16741780A | 1980-07-11 | 1980-07-11 |
Publications (2)
Publication Number | Publication Date |
---|---|
GB2079537A true GB2079537A (en) | 1982-01-20 |
GB2079537B GB2079537B (en) | 1984-07-11 |
Family
ID=22607301
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
GB8121103A Expired GB2079537B (en) | 1980-07-11 | 1981-07-08 | A method for applying an anti-reflection coating and an electrode to a solar cell |
Country Status (9)
Country | Link |
---|---|
JP (1) | JPS5749279A (en) |
AU (1) | AU542589B2 (en) |
BE (1) | BE889579A (en) |
CA (1) | CA1164734A (en) |
DE (1) | DE3127156A1 (en) |
ES (1) | ES503827A0 (en) |
FR (1) | FR2486718B1 (en) |
GB (1) | GB2079537B (en) |
IT (1) | IT1137610B (en) |
Cited By (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
GB2132412A (en) * | 1982-12-08 | 1984-07-04 | Int Rectifier Corp | Improvements in or relating to methods of manufacture of semiconductor devices |
EP0236034A2 (en) * | 1986-03-03 | 1987-09-09 | AT&T Corp. | Selective electroless plating of vias in vlsi devices |
EP0778624A2 (en) * | 1992-07-15 | 1997-06-11 | Canon Kabushiki Kaisha | Photovoltaic device and method of manufacturing the same |
Families Citing this family (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
DE3242791A1 (en) * | 1982-11-19 | 1984-05-24 | Siemens AG, 1000 Berlin und 8000 München | METHOD FOR PRODUCING ELECTRICAL CONTACTS FORMING FINGER ELECTRODE STRUCTURES ON AMORPHOUS SILICON SOLAR CELLS |
US4594311A (en) * | 1984-10-29 | 1986-06-10 | Kollmorgen Technologies Corporation | Process for the photoselective metallization on non-conductive plastic base materials |
EP0325606B1 (en) * | 1987-07-07 | 1994-09-07 | Mobil Solar Energy Corporation | Method of fabricating solar cells with anti-reflection coating |
JPH02137482A (en) * | 1988-11-18 | 1990-05-25 | Canon Inc | Camera system |
Family Cites Families (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JPS5120277B2 (en) * | 1972-08-17 | 1976-06-23 | ||
US4171989A (en) * | 1976-01-27 | 1979-10-23 | Motorola, Inc. | Contact for solar cells |
US4241108A (en) * | 1978-10-10 | 1980-12-23 | Rca Corporation | Sprayable titanium composition |
-
1981
- 1981-04-10 CA CA000375170A patent/CA1164734A/en not_active Expired
- 1981-07-08 GB GB8121103A patent/GB2079537B/en not_active Expired
- 1981-07-09 DE DE19813127156 patent/DE3127156A1/en not_active Withdrawn
- 1981-07-10 ES ES503827A patent/ES503827A0/en active Granted
- 1981-07-10 FR FR8113692A patent/FR2486718B1/en not_active Expired
- 1981-07-10 BE BE0/205370A patent/BE889579A/en not_active IP Right Cessation
- 1981-07-10 AU AU72754/81A patent/AU542589B2/en not_active Ceased
- 1981-07-10 IT IT22882/81A patent/IT1137610B/en active
- 1981-07-11 JP JP56107612A patent/JPS5749279A/en active Pending
Cited By (6)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
GB2132412A (en) * | 1982-12-08 | 1984-07-04 | Int Rectifier Corp | Improvements in or relating to methods of manufacture of semiconductor devices |
EP0236034A2 (en) * | 1986-03-03 | 1987-09-09 | AT&T Corp. | Selective electroless plating of vias in vlsi devices |
EP0236034A3 (en) * | 1986-03-03 | 1990-03-21 | AT&T Corp. | Selective electroless plating of vias in vlsi devices |
EP0778624A2 (en) * | 1992-07-15 | 1997-06-11 | Canon Kabushiki Kaisha | Photovoltaic device and method of manufacturing the same |
EP0778624A3 (en) * | 1992-07-15 | 1998-04-08 | Canon Kabushiki Kaisha | Photovoltaic device and method of manufacturing the same |
US6214636B1 (en) | 1992-07-15 | 2001-04-10 | Canon Kabushiki Kaisha | Photovoltaic device with improved collector electrode |
Also Published As
Publication number | Publication date |
---|---|
ES8301556A1 (en) | 1982-12-01 |
IT1137610B (en) | 1986-09-10 |
JPS5749279A (en) | 1982-03-23 |
AU542589B2 (en) | 1985-02-28 |
ES503827A0 (en) | 1982-12-01 |
AU7275481A (en) | 1982-01-14 |
CA1164734A (en) | 1984-04-03 |
IT8122882A0 (en) | 1981-07-10 |
FR2486718B1 (en) | 1986-09-12 |
DE3127156A1 (en) | 1982-03-04 |
BE889579A (en) | 1982-01-11 |
FR2486718A1 (en) | 1982-01-15 |
GB2079537B (en) | 1984-07-11 |
Similar Documents
Publication | Publication Date | Title |
---|---|---|
US4359487A (en) | Method for applying an anti-reflection coating to a solar cell | |
US4361950A (en) | Method of making solar cell with wrap-around electrode | |
US4751191A (en) | Method of fabricating solar cells with silicon nitride coating | |
EP0531430B1 (en) | A method of making semiconductor components as well as a solar cell made therefrom | |
AU2490184A (en) | Method of fabricating solar cells | |
US4078945A (en) | Anti-reflective coating for silicon solar cells | |
US4612698A (en) | Method of fabricating solar cells | |
JPH07297429A (en) | Solar battery cell and its manufacture | |
DE19744197A1 (en) | Silicon solar cell or semiconductor device production | |
JP2955167B2 (en) | Solar cell manufacturing method | |
JPH0572114B2 (en) | ||
US4577393A (en) | Process for the production of a solar cell | |
US4691077A (en) | Antireflection coatings for silicon solar cells | |
JP3430068B2 (en) | Solar cell electrodes | |
CA1164734A (en) | Method for applying an anti-reflection coating to a solar cell | |
US4387116A (en) | Conditioner for adherence of nickel to a tin oxide surface | |
JP2989373B2 (en) | Method for manufacturing photoelectric conversion device | |
JP3238003B2 (en) | Method of manufacturing solar cell element | |
JP3676954B2 (en) | Photoelectric conversion element and manufacturing method thereof | |
JP2005167291A (en) | Solar cell manufacturing method and semiconductor device manufacturing method | |
JPS59178778A (en) | Solar battery and manufacture thereof | |
JPH0233980A (en) | Manufacture of solar cell | |
AU574431B2 (en) | Proton milling as a form of plating mask | |
JPS62108579A (en) | Manufacture of solar cell | |
JP2003303980A (en) | Solar cell and method for manufacturing the same |
Legal Events
Date | Code | Title | Description |
---|---|---|---|
PCNP | Patent ceased through non-payment of renewal fee |