# US 2014/0196779 A1 · Multi-junction solar cells with through-substrate vias > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2014/0196779 A1 - Document ID: US20140196779A1 - Status: Published application - Kind: A1 - Application number: 14/213,334 - Filed: 2014-03-14 - Published: 2014-07-17 - Earliest claimed: 2012-04-06 - Assignees: Solar Junction Corporation - Applicants: Solar Junction Corporation - Inventors: ONUR FIDANER; MICHAEL WEST WIEMER - Web page: https://patentgrep.com/patent/US20140196779A1 ## CPC - H10F 77/219: {Arrangements for electrodes of back-contact photovoltaic cells} - H10F 10/142: comprising multiple PN homojunctions, e.g. tandem cells - H10F 10/161: comprising multiple PN heterojunctions, e.g. tandem cells - H10F 10/172: comprising multiple PIN junctions, e.g. tandem cells - 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 77/223: {for metallisation wrap-through [MWT] photovoltaic cells} - Y02E 10/544: Solar cells from Group III-V materials - Y02E 10/548: Amorphous 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 Multi junction solar cells and methods for making multi junction solar cells are disclosed. Back-contact-only multi junction solar cells wherein the side facing the sun, is capable of withstanding environments for use in space are disclosed. ## Claims ### Claim 1 A multi junction solar cell device comprising: an electrically conductive semiconductor substrate with at least one multi junction solar cell element formed in an epitaxial region grown thereon; a plurality of cap regions formed on top of the epitaxial region; a plurality of through-substrate via heads corresponding to each of the plurality of cap regions formed on a back surface of the substrate; through-substrate vias that extend through the substrate from each of the plurality of cap regions to the corresponding through-substrate vias heads; conductive metal within the through-substrate vias and electrically connecting each of the plurality of cap regions to the corresponding through-substrate via heads; an electrically insulating liner disposed on the walls of each of the through-substrate vias insulating the substrate and the epitaxial region from the conductive metal inside the through-substrate vias; an optical cover material disposed upon an optically transparent adhesive material directly above each of the plurality of through-substrate via heads; and a back metal, patterned with a back metal pattern, in ohmic contact with the back surface of the electrically conductive semiconductor substrate, and electrically isolated from the through-substrate via heads. ### Claim 2 (depends on 1) The multi junction solar cell device of claim 1, comprising: a patterned insulating layer on the back surface of the substrate; and metal regions comprising contact pads on the patterned insulating layer such that the metal regions are in direct electrical contact to the conductive metal inside the through-substrate vias and not electrically connected directly to the semiconductor substrate or to the back metal. ### Claim 3 (depends on 2) The multi junction solar cell device of claim 2, wherein the contact pads are patterned to form a patterned back contact such that multiple contact pads are electrically interconnected. ### Claim 4 (depends on 3) The multi junction solar cell device of claim 3, wherein the patterned back contact and the back metal are patterned in an interdigitated back contact pattern. ### Claim 5 (depends on 1) The multi junction solar cell device of claim 1, comprising metal gridlines along cap regions that extend from exposed metal of the through-via region on the top side of the device. ### Claim 6 (depends on 1) The multi junction solar cell device of claim 1, wherein materials forming the device do not contain silver metal. ### Claim 7 (depends on 1) The multi junction solar cell device of claim 1, wherein the through-substrate via head comprises a planar metal region disposed upon a cap region defined during front-end processing such that the via metal is electrically connected to the cap region through the planar metal region. ### Claim 8 (depends on 1) The multi junction solar cell device of claim 1, wherein the through-substrate via head comprises: a metal region deposited on the cap region; and a dielectric material encircled by the cap region; wherein the dielectric material acts as an etch stop layer during etching of through-substrate vias and is removed prior to via metal deposition. ### Claim 9 A method of forming a through-substrate via head comprising: providing a substrate having an epitaxial region grown thereon and a plurality of cap regions formed on top of the epitaxial region; depositing a photoresist region on the plurality of cap regions; etching a plurality of through-substrate vias from a backside of the substrate and using the photoresist region as an etch stop layer; depositing an electrically insulating liner within each of the plurality of through-substrate vias; removing the photoresist region to expose the plurality of cap regions; and depositing metal within the through-substrate vias to connect the plurality of cap regions. ### Claim 10 (depends on 9) The method of claim 9, wherein the optical cover material is bonded to the top surface prior to a substrate thinning step. ### Claim 11 A multi junction solar cell device comprising: a semi-insulating semiconductor substrate having a back surface; an epitaxial region overlying the semi-insulating semiconductor substrate; an electrically conductive semiconductor region between the substrate and the epitaxial region; at least one multi junction solar cell element formed in the epitaxial region, the epitaxial region being grown on the electrically conductive semiconductor region; a cap region overlying the epitaxial region; though-wafer vias that extend from the cap region to the back surface of the substrate; the cap region being shaped according to a cap pattern including collars around the through-wafer vias; conductive metal within the through-wafer vias and electrically connected to the cap patterned collars; an electrically insulating liner on the walls of the through-wafer vias insulating the conductive metal inside the through-wafer vias from at least the epitaxial region and from the conductive semiconductor region; an optical cover material disposed upon an optically transparent adhesive material directly above the through-substrate via heads formed on top of the epitaxial region; and a back metal on the back surface of the substrate in electrical contact with the conductive metal in the through-wafer vias. ### Claim 12 (depends on 11) The multi junction solar cell device of claim 11, comprising metal gridlines along cap regions that extend from exposed metal of the through-via region. ### Claim 13 (depends on 11) The multi junction solar cell device of claim 11, wherein materials forming the device do not contain silver metal. ### Claim 14 A multi junction solar cell device comprising: an electrically conductive semiconductor substrate with at least one multi junction solar cell element formed in an epitaxial region grown thereon; a plurality of cap regions formed on top of the epitaxial region; through-substrate vias that extend from the plurality of cap regions to a back surface of the substrate; conductive metal within the through-substrate vias and electrically connected to the plurality of cap regions; an electrically insulating liner disposed on the walls of the through-substrate vias insulating the substrate and the epitaxial region from the conductive metal inside the through-wafer vias; a through-substrate via head that electrically connects the conductive metal within the through-substrate vias with the plurality of cap regions, henceforth called; a temporary carrier substrate bonded directly above the through substrate via heads formed on top of the epitaxial region; and a back metal, patterned with a back metal pattern, in ohmic contact with the back surface of the electrically conductive semiconductor substrate, and electrically isolated from the conductive metal within the through-substrate vias. ### Claim 15 (depends on 14) The multi junction solar cell device of claim 14, wherein the through-substrate via head comprises a planar metal region disposed upon a cap region defined during front-end processing such that the via metal is electrically connected to the cap region through the planar metal region. ### Claim 16 (depends on 14) The multi junction solar cell device of claim 14, wherein the through-substrate via head comprises: a metal region deposited on the cap region; and a dielectric material encircled by the cap region; wherein the dielectric material acts as an etch stop layer during etching of through-substrate vias and is removed prior to via metal deposition. ### Claim 17 A method of forming a multi junction solar cell device, comprising: providing an electrically conductive semiconductor substrate with at least one multi-junction solar cell element formed in an epitaxial region grown thereon, and a plurality of cap regions formed on top of the epitaxial region; bonding a cover glass on top of the substrate and the plurality of cap regions; thinning the substrate; etching through-substrate vias from a back surface of the substrate; forming a patterned dielectric layer on the back surface of the substrate; and forming electrical connection between the patterned cap region and the back metal contacts pads with conductive metal inside the through-substrate vias, such that the contact pads are not directly electrically connected to the semiconductor substrate. ### Claim 18 A method of forming a multi junction solar cell device, comprising: providing an electrically conductive semiconductor substrate with at least one multi-junction solar cell element formed in an epitaxial region grown thereon, and a patterned cap region formed on top of the epitaxial region; bonding a polymer cover on top of the substrate and the patterned cap region; thinning the substrate; etching through-substrate vias from a back surface of the substrate; forming a patterned dielectric layer on the back surface of the substrate; forming a plurality of back metal contact pads; and forming electrical connection between the patterned cap region and the back metal contacts pads with conductive metal inside the through-substrate vias, such that the contact pads are not directly electrically connected to the semiconductor substrate.