# US 8,465,909 B2 · Self-aligned masking for solar cell manufacture > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 8,465,909 B2 - Document ID: US8465909B2 - Status: Granted - Kind: B2 - Application number: 12/916,993 - Filed: 2010-11-01 - Published: 2011-05-05 - Granted: 2013-06-18 - Earliest claimed: 2009-11-04 - Assignees: Varian Semiconductor Equipment Associates, Inc. - Applicants: Nicholas P. T. Bateman; Helen L. Maynard; Benjamin B. Riordon; Christopher R. Hatem; Deepak Ramappa - Inventors: Nicholas P. T. Bateman; Helen L. Maynard; Benjamin B. Riordon; Christopher R. Hatem; Deepak Ramappa - Web page: https://patentgrep.com/patent/US8465909B2 ## CPC - 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} - H10P 30/22: using masks - 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 - H10P: GENERIC PROCESSES OR APPARATUS FOR THE MANUFACTURE OR TREATMENT OF DEVICES COVERED BY CLASS H10 - 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 Various methods of utilizing the physical and chemical property differences between amorphized and crystalline silicon are used to create masks that can be used for subsequent implants. In some embodiments, the difference in film growth between amorphous and crystalline silicon is used to create the mask. In other embodiments, the difference in reflectivity or light absorption between amorphous and crystalline silicon is used to create the mask. In other embodiments, differences in the characteristics of doped and undoped silicon is used to create masks. ## Claims ### Claim 1 A method of performing a patterned implant in a crystalline substrate, comprising: performing a first patterned implant configured to create an amorphous portion of said substrate, wherein a crystalline portion of said substrate remains; using a difference in a physical or chemical property between said amorphous and crystalline portions to create a mask over one of said crystalline portion or said amorphous portion; and performing a second patterned implant, using said mask created based on said difference to implant a region not covered by said mask. ### Claim 2 A method of performing a patterned implant in a crystalline substrate, comprising: performing a first patterned implant configured to create an amorphous portion of said substrate, wherein a crystalline portion of said substrate remains; applying a photoresist to a surface of said substrate; applying light in a predetermined frequency range to said surface at a predetermined intensity level, whereby said intensity level is insufficient to set said photoresist; using the reflectivity of said substrate to augment said applied light, wherein an amount of light reflected by said amorphous portion is greater than an amount of light reflected by said crystalline portion, wherein the amount of light reflected by one of said portions, when added to said applied light is capable of setting said photoresist, and wherein the amount of light reflected by the other of said portions, when added to said applied light is incapable of setting said photoresist; removing photoresist which was not set; and exposing said substrate to a second implant, wherein said photoresist masks one of said amorphous portion or said crystalline portion from said second implant. ### Claim 3 (depends on 2) The method of claim 2, wherein said photoresist comprises a positive photoresist, and said positive photoresist masks said amorphous portion from said second implant. ### Claim 4 (depends on 2) The method of claim 2, wherein said photoresist comprises a negative photoresist, and said negative photoresist masks said crystalline portion from said second implant. ### Claim 5 (depends on 2) The method of claim 2, wherein said photoresist is applied at a thickness related to the predetermined frequency range of said light applied to said surface. ### Claim 6 (depends on 2) The method of claim 2, wherein said photoresist is applied at a thickness between 80 nm and 500 nm. ### Claim 7 (depends on 2) The method of claim 2, wherein said predetermined frequency range comprises 100 nm to 2000 nm. ### Claim 8 (depends on 2) The method of claim 2, wherein said photoresist is selected from the group consisting of H-line, I-line, wide-band, deep-UV, or any photoactive film where light alters its properties. ### Claim 9 A method of performing a patterned implant in a crystalline substrate, comprising: performing a first patterned implant configured to create an amorphous portion of said substrate, wherein a crystalline portion of said substrate remains; applying a thermal polymer to a surface of said substrate; applying light in a predetermined frequency range to said substrate at a predetermined intensity level to heat said substrate; using the energy absorption of said substrate to heat said polymer, wherein said energy absorption of said amorphous portion is greater than said energy absorption of said crystalline portion such that said amorphous region is sufficiently heated to set said thermal polymer and said energy absorption of said crystalline portion is insufficient to set said thermal polymer; removing said thermal polymer which was not set; and exposing said substrate to a second implant, wherein said thermal polymer masks said amorphous portion from said second implant. ### Claim 10 (depends on 9) The method of claim 9, wherein said thermal polymer is applied at a thickness between 100 nm and 50 μm. ### Claim 11 (depends on 9) The method of claim 9, wherein said predetermined frequency range comprises infrared light. ### Claim 12 (depends on 9) The method of claim 9, wherein said thermal polymer is selected from the group consisting of polyamides and melamine formaldehyde. ### Claim 13 (depends on 9) The method of claim 9, where said light is applied to said surface of said substrate. ### Claim 14 (depends on 9) The method of claim 9, wherein said substrate comprises a back side, opposite said surface, and wherein said light is applied to said back side of said substrate.