# US 8,772,067 B2 · Silicon substrate having textured surface, solar cell having same, and method for producing same > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 8,772,067 B2 - Document ID: US8772067B2 - Status: Granted - Kind: B2 - Application number: 13/823,470 - Filed: 2012-04-13 - Published: 2013-07-18 - Granted: 2014-07-08 - Earliest claimed: 2011-04-15 - Assignees: Panasonic Corporation - Applicants: Ichiro Nakayama; Tsuyoshi Nomura; Tomohiro Okumura; Mitsuo Saitoh; Hiroshi Tanabe; Yukiya Usui - Inventors: Ichiro Nakayama; Tsuyoshi Nomura; Tomohiro Okumura; Mitsuo Saitoh; Hiroshi Tanabe; Yukiya Usui - Web page: https://patentgrep.com/patent/US8772067B2 ## CPC - H10F 71/121: {The active layers comprising only Group IV materials} - H10F 10/14: Photovoltaic cells having only PN homojunction potential barriers - H10F 71/139: {using temporary substrates} - H10F 77/223: {for metallisation wrap-through [MWT] photovoltaic cells} - H10F 77/227: {for emitter wrap-through [EWT] photovoltaic cells, e.g. interdigitated emitter-base back-contacts} - H10F 77/703: {of the semiconductor bodies, e.g. textured active layers} - 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 - 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 The purpose of the present invention is to obtain a finer texture for a silicon substrate having a textured surface and thereby obtain a thinner silicon substrate for a solar cell. The invention provides a silicon substrate that has a thickness of 50 [mu]m or less and substrate surface orientation (111), and that has a textured surface on which a texture has been formed. Such a silicon substrate is produced by a process comprising a step (A) for preparing a silicon substrate that preferably has a thickness of 50 [mu]m or less and substrate surface orientation (111), and a step (B) for texturing by blowing etching as comprising a fluorine-containing gas onto the surface of the prepared silicon substrate. ## Claims ### Claim 1 A method of manufacturing a silicon substrate for a solar cell, comprising: a process A of preparing a silicon ingot having a substrate surface orientation (111); a process B of blowing an etching gas including a fluorine-containing gas to the substrate surface of the silicon ingot to form a textured surface; a process C of implanting a dopant to the textured surface to form a PN junction in a surface layer of the silicon ingot; a process D of implanting ions through the textured surface into the silicon ingot to form an ion-implanted layer; and a process E of dividing the silicon ingot at the ion-implanted layer by applying an impact to the silicon ingot in which the ion-implanted layer is formed to obtain a silicon substrate having a thickness of 50 μm or less. ### Claim 2 A method of manufacturing a silicon substrate for a solar cell, comprising: a process A of preparing a silicon ingot having a substrate surface orientation (111); a process D′ of implanting ions through the substrate surface into the silicon ingot to form an ion-implanted layer; a process B of blowing an etching gas including a fluorine-containing gas to the substrate surface of the silicon ingot to form a textured surface; a process C of implanting a dopant to the textured surface to form a PN junction in a surface layer of the silicon ingot; and a process E of dividing the silicon ingot at the ion-implanted layer by applying an impact to the silicon ingot in which the ion-implanted layer is formed to obtain a silicon substrate having a thickness of 50 μm or less. ### Claim 3 A method of manufacturing a silicon substrate for a solar cell, comprising: a process A of preparing a silicon ingot having a substrate surface orientation (111); a process B of blowing an etching gas including a fluorine-containing gas to the substrate surface of the prepared silicon ingot to form a textured surface; a process D″ of implanting ions through the textured surface into the silicon ingot to form an ion-implanted layer; a process C of implanting a dopant to the textured surface to form a PN junction in a surface layer of the silicon ingot; a process E of dividing the silicon ingot at the ion-implanted layer by applying an impact to the silicon ingot in which the ion-implanted layer is formed to obtain a silicon substrate having a thickness of 50 μm or less. ### Claim 4 (depends on 1) The method according to claim 1, wherein the fluorine-containing gas includes one or more gases selected from a group consisting of ClF3, XeF2, BrF3, BrF5, and NF3. ### Claim 5 (depends on 2) The method according to claim 2, wherein the fluorine-containing gas includes one or more gases selected from a group consisting of ClF3, XeF2, BrF3, BrF5, and NF3. ### Claim 6 (depends on 3) The method according to claim 3, wherein the fluorine-containing gas includes one or more gases selected from a group consisting of ClF3, XeF2, BrF3, BrF5, and NF3. ### Claim 7 (depends on 1) The method according to claim 1, wherein the etching gas further includes a gas that contains an oxygen atom in a molecule. ### Claim 8 (depends on 2) The method according to claim 2, wherein the etching gas further includes a gas that contains an oxygen atom in a molecule. ### Claim 9 (depends on 3) The method according to claim 3, wherein the etching gas further includes a gas that contains an oxygen atom in a molecule. ### Claim 10 (depends on 1) The method according to claim 1, wherein etching of the silicon substrate in the process B is performed under a reduced-pressure atmosphere. ### Claim 11 (depends on 2) The method according to claim 2, wherein etching of the silicon substrate in the process B is performed under a reduced-pressure atmosphere. ### Claim 12 (depends on 3) The method according to claim 3, wherein etching of the silicon substrate in the process B is performed under a reduced-pressure atmosphere. ### Claim 13 (depends on 1) The method according to claim 1, wherein a plurality of pyramid-shaped protrusions are formed in the textured surface, and a height of the protrusions is within a range of 100 nm to 1,500 nm. ### Claim 14 (depends on 2) The method according to claim 2, wherein a plurality of pyramid-shaped protrusions are formed in the textured surface, and a height of the protrusions is within a range of 100 nm to 1,500 nm. ### Claim 15 (depends on 3) The method according to claim 3, wherein a plurality of pyramid-shaped protrusions are formed in the textured surface, and a height of the protrusions is within a range of 100 nm to 1,500 nm. ### Claim 16 A method of manufacturing a silicon substrate for a solar cell, comprising: a process A of preparing a silicon ingot having a substrate surface orientation (111); a process B of blowing an etching gas including a fluorine-containing gas to the substrate surface of the silicon ingot to form a textured surface; a process C of irradiating the textured surface with a laser to form a hole therein; a process D of implanting a dopant to the textured surface to form a PN junction in a surface layer of the silicon ingot and an inner wall surface layer of the hole; a process E of implanting ions through the textured surface into the silicon ingot to form an ion-implanted layer; and a process F of dividing the silicon ingot at the ion-implanted layer by applying an impact to the silicon ingot in which the ion-implanted layer is formed to obtain a silicon substrate having a thickness of 50 μm or less. ### Claim 17 A method of manufacturing a silicon substrate for a solar cell, comprising: a process A of preparing a silicon ingot having a substrate surface orientation (111); a process E′ of implanting ions through the substrate surface into the silicon ingot to form an ion-implanted layer; a process B of blowing an etching gas including a fluorine-containing gas to the substrate surface of the silicon ingot to form a textured surface; a process C of irradiating the textured surface with a laser to form a hole therein; a process D of implanting a dopant to the textured surface to form a PN junction in a surface layer of the silicon ingot and an inner wall surface layer of the hole; and a process F of dividing the silicon ingot at the ion-implanted layer by applying an impact to the silicon ingot in which the ion-implanted layer is formed to obtain a silicon substrate having a thickness of 50 μm or less. ### Claim 18 A method of manufacturing a silicon substrate for a solar cell, comprising: a process A of preparing a silicon ingot having a substrate surface orientation (111); a process B of blowing an etching gas including a fluorine-containing gas to the substrate surface of the silicon ingot to form a textured surface; a process E″ of implanting ions through the textured surface into the silicon ingot to form an ion-implanted layer; a process C of irradiating the textured surface with a laser to form a hole therein; a process D of implanting a dopant to the textured surface to form a PN junction in a surface layer of the silicon ingot and an inner wall surface layer of the hole; and a process F of dividing the silicon ingot at the ion-implanted layer by applying an impact to the silicon ingot in which the ion-implanted layer is formed to obtain a silicon substrate having a thickness of 50 μm or less. ### Claim 19 (depends on 16) The method according to claim 16, wherein the fluorine-containing gas includes one or more gases selected from a group consisting of ClF3, XeF2, BrF3, BrF5, and NF3. ### Claim 20 (depends on 17) The method according to claim 17, wherein the fluorine-containing gas includes one or more gases selected from a group consisting of ClF3, XeF2, BrF3, BrF5, and NF3. ### Claim 21 (depends on 18) The method according to claim 18, wherein the fluorine-containing gas includes one or more gases selected from a group consisting of ClF3, XeF2, BrF3, BrF5, and NF3. ### Claim 22 (depends on 16) The method according to claim 16, wherein the etching gas further includes a gas that contains an oxygen atom in a molecule. ### Claim 23 (depends on 17) The method according to claim 17, wherein the etching gas further includes a gas that contains an oxygen atom in a molecule. ### Claim 24 (depends on 18) The method according to claim 18, wherein the etching gas further includes a gas that contains an oxygen atom in a molecule. ### Claim 25 (depends on 16) The method according to claim 16, wherein etching of the silicon substrate in the process B is performed under a reduced-pressure atmosphere. ### Claim 26 (depends on 17) The method according to claim 17, wherein etching of the silicon substrate in the process B is performed under a reduced-pressure atmosphere. ### Claim 27 (depends on 18) The method according to claim 18, wherein etching of the silicon substrate in the process B is performed under a reduced-pressure atmosphere. ### Claim 28 (depends on 16) The method according to claim 16, wherein a plurality of pyramid-shaped protrusions are formed in the textured surface, and a height of the protrusions is within a range of 100 nm to 1,500 nm. ### Claim 29 (depends on 17) The method according to claim 17, wherein a plurality of pyramid-shaped protrusions are formed in the textured surface, and a height of the protrusions is within a range of 100 nm to 1,500 nm. ### Claim 30 (depends on 18) The method according to claim 18, wherein a plurality of pyramid-shaped protrusions are formed in the textured surface, and a height of the protrusions is within a range of 100 nm to 1,500 nm.