# US 11,305,378 B2 · Wafer alignment with restricted visual access > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 11,305,378 B2 - Document ID: US11305378B2 - Status: Granted - Kind: B2 - Application number: 16/773,759 - Filed: 2020-01-27 - Published: 2020-05-21 - Granted: 2022-04-19 - Earliest claimed: 2013-12-19 - Assignees: SunPower Corporation - Applicants: SunPower Corporation - Inventors: Thomas Pass - Web page: https://patentgrep.com/patent/US11305378B2 ## CPC - B23K 26/032: {using optical means} - H10F 55/10: wherein the radiation-sensitive semiconductor devices control the electric light source, e.g. image converters, image amplifiers or image storage devices - H10F 71/00: Manufacture or treatment of devices covered by this subclass (patterning processes to connect thin photovoltaic cells in integrated devices, or assemblies of multiple devices, having photovoltaic cells H10F19/33; manufacture or treatment of encapsulations or containers for integrated devices, or assemblies of multiple devices, having photovoltaic cells H10F19/80; manufacture or treatment of integrated devices, or assemblies of multiple devices, comprising at least one element in which radiation controls the flow of current H10F39/00) - H10F 71/134: {Irradiation with electromagnetic or particle radiation} - H10P 72/0606: {Position monitoring, e.g. misposition detection or presence detection} - H10P 72/53: {using optical controlling means} - G03F 9/7084: {Position of mark on substrate, i.e. position in (x, y, z) of mark, e.g. buried or resist covered mark, mark on rearside, at the substrate edge, in the circuit area, latent image mark, marks in plural levels} - G03F 9/7088: {Alignment mark detection, e.g. TTR, TTL, off-axis detection, array detector, video detection} - H10F 77/254: {comprising a metal, e.g. transparent gold} - Y02E 10/50: Photovoltaic [PV] energy - 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 - 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 - G03F: PHOTOMECHANICAL PRODUCTION OF TEXTURED OR PATTERNED SURFACES, e.g. FOR PRINTING, FOR PROCESSING OF SEMICONDUCTOR DEVICES; MATERIALS THEREFOR; ORIGINALS THEREFOR; APPARATUS SPECIALLY ADAPTED THEREFOR; (phototypographic composing devices B41B; photosensitive materials or processes for photographic purposes G03C; electrophotography, sensitive layers or processes therefor G03G) - Y02E: REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION ## Abstract Wafer alignment with restricted visual access has been disclosed. In an example, a method of processing a substrate for fabricating a solar cell involves supporting the substrate over a stage. The method involves forming a substantially opaque layer over the substrate. The substantially opaque layer at least partially covers edges of the substrate. The method involves performing fit-up of the substantially opaque layer to the substrate. The method involves illuminating the covered edges of the substrate with light transmitted through the stage, and capturing a first image of the covered edges of the substrate based on the light transmitted through the stage. The method further includes determining a first position of the substrate relative to the stage based on the first image of the covered edges. The substrate may be further processed based on the determined first position of the substrate under the substantially opaque layer. ## Claims ### Claim 1 A non-transitory machine-accessible storage medium storing instructions executable by a computing device to perform: supporting a substrate over a stage; forming a substantially opaque layer over the substrate, the substantially opaque layer at least partially covering edges of the substrate, wherein forming the substantially opaque layer over the substrate comprises placing a metal sheet over the substrate; performing fit-up of the substantially opaque layer to the substrate, wherein the substantially opaque layer extends beyond the edges of the substrate outside of a perimeter of the substrate following the fit-up, wherein performing fit-up comprises applying pressure to the metal sheet; illuminating the at least partially covered edges of the substrate with light transmitted through the stage; capturing a first image of the at least partially covered edges of the substrate based on the light transmitted through the stage; determining a first position of the substrate relative to the stage based on the first image of the at least partially covered edges; processing the substrate based on the determined first position of the substrate under the substantially opaque layer, wherein processing the substrate based on the determined first position comprises applying a laser to at least the metal sheet or a metal layer of the substrate; capturing a second image of the at least partially covered edges of the substrate after said applying the laser; and determining a second position of the substrate relative to the stage based on the second image of the at least partially covered edges. ### Claim 2 (depends on 1) The non-transitory machine-accessible storage medium of claim 1, wherein capturing the first image of the at least partially covered edges of the substrate comprises capturing the first image through one or more substantially transparent windows in the stage. ### Claim 3 (depends on 1) The non-transitory machine-accessible storage medium of claim 1, wherein capturing the first image of the at least partially covered edges of the substrate comprises capturing the first image through the stage. ### Claim 4 (depends on 1) The non-transitory machine-accessible storage medium of claim 1, wherein capturing the first image of the at least partially covered edges comprises capturing the first image with an image sensor located below the stage. ### Claim 5 (depends on 1) The non-transitory machine-accessible storage medium of claim 1, wherein illuminating the at least partially covered edges of the substrate with light transmitted through the stage comprises illuminating with dark field illumination. ### Claim 6 (depends on 1) The non-transitory machine-accessible storage medium of claim 1, wherein illuminating the at least partially covered edges of the substrate comprises illuminating the at least partially covered edges with one or more light sources located in the stage. ### Claim 7 (depends on 1) The non-transitory machine-accessible storage medium of claim 1, wherein illuminating the at least partially covered edges of the substrate comprises illuminating the at least partially covered edges with one or more light sources located below the stage. ### Claim 8 (depends on 1) The non-transitory machine-accessible storage medium of claim 1, wherein capturing the first image comprises capturing an image of each of the at least partially covered edges of the substrate. ### Claim 9 (depends on 1) The non-transitory machine-accessible storage medium of claim 1, wherein capturing the first image comprises capturing an image of each of a plurality of comers of the substrate. ### Claim 10 A non-transitory machine-accessible storage medium storing instructions executable by a computing device to perform: supporting a substrate over a stage; forming a substantially opaque layer over the substrate, the substantially opaque layer at least partially covering edges of the substrate, wherein forming the substantially opaque layer over the substrate comprises placing a metal sheet over the substrate; performing fit-up of the substantially opaque layer to the substrate, wherein the substantially opaque layer extends beyond the edges of the substrate outside of a perimeter of the substrate following the fit-up, wherein performing fit-up comprises applying pressure to the metal sheet; illuminating the at least partially covered edges of the substrate with light transmitted through the stage; capturing a first image of the at least partially covered edges of the substrate based on the light transmitted through the stage; determining a first position of the substrate relative to the stage based on the first image of the at least partially covered edges; processing the substrate based on the determined first position of the substrate under the substantially opaque layer, wherein processing the substrate based on the determined first position comprises applying a laser to at least the metal sheet or a metal layer of the substrate; patterning the metal sheet; capturing a second image of the at least partially covered edges of the substrate after patterning the metal sheet; determining a second position of the substrate relative to the stage based on the second captured image of the at least partially covered edges; and trimming the patterned metal sheet. ### Claim 11 (depends on 10) The non-transitory machine-accessible storage medium of claim 10, wherein capturing the first image of the at least partially covered edges of the substrate comprises capturing the first image through one or more substantially transparent windows in the stage. ### Claim 12 (depends on 10) The non-transitory machine-accessible storage medium of claim 10, wherein capturing the first image of the at least partially covered edges of the substrate comprises capturing the first image through the stage. ### Claim 13 (depends on 10) The non-transitory machine-accessible storage medium of claim 10, wherein capturing the first image of the at least partially covered edges comprises capturing the first image with an image sensor located below the stage.