# US 2009/0260684 A1 · Solar cell, method of forming emitter layer of solar cell, and method of manufacturing solar cell > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2009/0260684 A1 - Document ID: US20090260684A1 - Status: Published application - Kind: A1 - Application number: 12/425,691 - Filed: 2009-04-17 - Published: 2009-10-22 - Earliest claimed: 2008-04-17 - Assignees: LG Electronics Inc. - Inventors: JaeSung YOU - Web page: https://patentgrep.com/patent/US20090260684A1 ## CPC - H10F 77/215: {Geometries of grid contacts} - B23K 26/066: by using masks - H10F 10/14: Photovoltaic cells having only PN homojunction potential barriers - H10F 10/146: {Back-junction photovoltaic cells, e.g. having interdigitated base-emitter regions on the back side} - H10F 71/121: {The active layers comprising only Group IV materials} - H10F 77/148: {Shapes of potential barriers} - Y02E 10/547: Monocrystalline silicon PV cells - Y02P 70/50: Manufacturing or production processes characterised by the final manufactured product - H10F: INORGANIC SEMICONDUCTOR DEVICES SENSITIVE TO INFRARED RADIATION, LIGHT, ELECTROMAGNETIC RADIATION OF SHORTER WAVELENGTH OR CORPUSCULAR RADIATION - B23K: SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM - Y02E: REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION - Y02P: CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS ## Abstract A method for forming emitter layer of a solar cell includes preparing a substrate including a first impurity of a first conductive type, diffusing a second impurity of a second conductive type opposite to the first conductive type in the substrate to form a first emitter portion of the emitter layer in the substrate, and selectively heating a portion of the first emitter portion, which corresponds to a position for forming at least one electrode, to form a second emitter portion. ## Claims ### Claim 1 A method for forming an emitter layer for a solar cell, the method comprising: preparing a substrate including a first impurity of a first conductive type; diffusing a second impurity of a second conductive type opposite to the first conductive type in the substrate to form a first emitter portion of the emitter layer in the substrate; and selectively heating a portion of the first emitter portion, which corresponds to a position for forming at least one electrode, to form a second emitter portion. ### Claim 2 (depends on 1) The method of claim 1, wherein the at least one electrode comprises a finger electrode and a bus electrode, and the second emitter portion is formed under the finger electrode. ### Claim 3 (depends on 1) The method of claim 1, wherein the forming of the first emitter portion comprises: supplying an impurity gas of the second conductive type in a diffusion furnace to diffuse an impurity included in the impurity gas in the substrate to form the first emitter portion; and generating an insulation layer including the impurity on the first emitter portion. ### Claim 4 (depends on 3) The method of claim 3, wherein the insulation layer is PSG (phosphorus silicate glass). ### Claim 5 (depends on 1) The method of claim 1, wherein the forming of the first emitter portion comprises: coating an impurity source including an impurity of the second conductive type on the substrate or printing a doping paste including the impurity of the second conductive type on the substrate; and heating the substrate with the coated impurity source or the printed doping paste to diffuse the impurity in the substrate to form the first emitter portion, and generating an insulation layer including the impurity on the first emitter portion. ### Claim 6 (depends on 5) The method of claim 5, wherein the insulation layer is PSG (phosphorus silicate glass). ### Claim 7 (depends on 3) The method of claim 3, wherein the forming of the second emitter portion comprises irradiating laser beams on the insulation layer, so that a portion of the first emitter portion underlying a portion of the insulation layer, on which the laser beams are irradiated, is heated. ### Claim 8 (depends on 5) The method of claim 5, wherein the forming of the second emitter portion comprises irradiating laser beams on the insulation layer, so that a portion of the first emitter portion underlying a portion of the insulation layer, on which the laser beams are irradiated, is heated. ### Claim 9 (depends on 7) The method of claim 7, wherein the laser beams have an irradiation width more than a width of the at least one electrode. ### Claim 10 (depends on 8) The method of claim 8, wherein the laser beams have an irradiation width more than a width of the at least one electrode. ### Claim 11 (depends on 7) The method of claim 7, wherein an irradiation position of the laser beams is moved by at least one of changing an emitting position of the laser beams and changing a position of the substrate. ### Claim 12 (depends on 8) The method of claim 8, wherein an irradiation position of the laser beams is moved by at least one of changing an emitting position of the laser beams and changing a position of the substrate. ### Claim 13 (depends on 1) The method of claim 1, wherein the second emitter portion has a sheet resistance less than a sheet resistance of the first emitter portion. ### Claim 14 (depends on 1) The method of claim 1, wherein the second emitter portion has an impurity concentration that is more than an impurity concentration of the first emitter portion. ### Claim 15 (depends on 1) The method of claim 1, wherein the second emitter portion has an impurity doped depth that is more than an impurity doped depth of the first emitter portion. ### Claim 16 (depends on 1) A method for manufacturing a solar cell, the method comprising: forming the emitter layer for the solar cell of claim 1; forming first electrodes connected to the first and second emitter portions, and a second electrode connected to the substrate, wherein the first electrodes comprise at least one finger electrode formed along the second emitter portion and at lease one bus electrode intersecting and connected to the at least one finger electrode. ### Claim 17 (depends on 16) The method of claim 16, wherein the selective heating includes at least one of laser beams irradiating the substrate along an extension direction of the at least one finger electrode. ### Claim 18 (depends on 16) The method of claim 16, wherein the first and second emitter portions are formed on a light receiving surface of the substrate. ### Claim 19 (depends on 16) The method of claim 16, wherein the second electrode is formed on an opposite surface of the substrate to the light receiving surface. ### Claim 20 (depends on 16) The method of claim 16, further comprising removing the insulation layer after the second emitter portion is formed. ### Claim 21 (depends on 16) The method of claim 16, further comprising forming an anti-reflection layer on the first and second emitter portions. ### Claim 22 (depends on 21) The method of claim 21, wherein the forming of the first and second electrodes comprises: applying a first electrode paste on the anti-reflection layer corresponding to the second emitter portion to form a pattern of the at least one finger electrode; and heating the substrate having the pattern of the at least one finger electrode. ### Claim 23 (depends on 22) The method of claim 22, wherein the forming of the pattern of the at least one finger electrode includes forming a pattern of at least one bus electrode to intersect the pattern of at least one finger electrode along with the pattern of the at least one finger electrode. ### Claim 24 (depends on 22) The method of claim 22, further comprising applying a second electrode paste on the substrate to form a pattern of the second electrode. ### Claim 25 (depends on 24) The method of claim 24, wherein the heating of the substrate heats the pattern of the second electrode along with the pattern of the at least one finger electrode. ### Claim 26 A solar cell, comprising: a substrate of a first conductive type; an emitter layer that is positioned on the substrate and is a second conductive type that is opposite to the first conductive type; first electrodes that are connected to the emitter layer; and a second electrode that is connected to the substrate, wherein the emitter layer comprises a first emitter portion and a second emitter portion, the first electrodes comprise a finger electrode, and a bus electrode intersecting and connected to the finger electrode, and the first emitter portion and the second emitter portion are positioned under the bus electrode. ### Claim 27 (depends on 26) The solar cell of claim 26, wherein the second emitter portion has an impurity concentration that is more than an impurity concentration of the first emitter portion. ### Claim 28 (depends on 26) The method of claim 26, wherein the second emitter portion has an impurity doped depth that is more than an impurity doped depth of the first emitter portion. ### Claim 29 (depends on 26) The solar cell of claim 26, wherein the finger electrode has a width of about 50 μm to 300 μm and the bus electrode has a width of about 1 mm to 3 mm. ### Claim 30 (depends on 26) The solar cell of claim 26, wherein the first emitter portion has a width that is more than a width of the finger electrode. ### Claim 31 (depends on 26) The solar cell of claim 26, wherein the second emitter portion has a thickness more than a thickness of the first emitter portion. ### Claim 32 (depends on 26) The solar cell of claim 26, further comprising an anti-reflection layer positioned on the emitter layer. ### Claim 33 (depends on 26) The solar cell of claim 26, further comprising a back surface field portion positioned between the substrate and the second electrode.