# US 9,040,409 B2 · Methods of forming solar cells and solar cell modules > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 9,040,409 B2 - Document ID: US9040409B2 - Status: Granted - Kind: B2 - Application number: 14/213,316 - Filed: 2014-03-14 - Published: 2014-09-18 - Granted: 2015-05-26 - Earliest claimed: 2013-03-15 - Assignees: Applied Materials, Inc. - Applicants: Applied Materials, Inc. - Inventors: Prabhat Kumar; Michael P. Stewart; Kalyan Rapolu; Lin Zhang; Hari K. Ponnekanti - Web page: https://patentgrep.com/patent/US9040409B2 ## CPC - H10F 77/211: {for photovoltaic cells} - H02S 40/22: Light-reflecting or light-concentrating means (directly associated with the PV cell or integrated with the PV cell H10F77/42) - H10F 10/166: the Group IV-IV heterojunctions being heterojunctions of crystalline and amorphous materials, e.g. silicon heterojunction [SHJ] photovoltaic cells - H10F 19/85: Protective back sheets - Y02E 10/52: PV systems with concentrators - H10F: INORGANIC SEMICONDUCTOR DEVICES SENSITIVE TO INFRARED RADIATION, LIGHT, ELECTROMAGNETIC RADIATION OF SHORTER WAVELENGTH OR CORPUSCULAR RADIATION - H02S: GENERATION OF ELECTRIC POWER BY CONVERSION OF INFRARED RADIATION, VISIBLE LIGHT OR ULTRAVIOLET LIGHT, e.g. USING PHOTOVOLTAIC [PV] MODULES (obtaining electrical energy from radioactive sources G21H1/12; light sensitive inorganic semiconductor devices H10F; light sensitive organic semiconductor devices H10K30/00; thermoelectric devices H10N10/00; pyroelectric devices H10N15/00) - Y02E: REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION ## Abstract Embodiments of the present invention are directed to processes for making solar cells by simultaneously co-firing metal layers disposed both on a first and a second surface of a bifacial solar cell substrate. Embodiments of the invention may also provide a method forming a solar cell structure that utilize a reduced amount of a silver paste on a front surface of the solar cell substrate and a patterned aluminum metallization paste on a rear surface of the solar cell substrate to form a rear surface contact structure. Embodiments can be used to form passivated emitter and rear cells (PERC), passivated emitter rear locally diffused solar cells (PERL), passivated emitter, rear totally-diffused (PERT), “iPERC,” Crystalline Reduced-cost Aluminum Fire-Through (CRAFT), pCRAFT, nCRAFT or other high efficiency cell concepts. ## Claims ### Claim 1 A method of manufacturing a solar cell device, comprising: removing an amount of a first conductive material from a region of a formed electrical contact structure formed on a surface of a substrate to expose at least a portion of an inter-diffused region formed in the surface of the substrate; depositing a second conductive material on the region of the formed electrical contact structure; and bonding a first conductive element to the second conductive material by delivering an amount of energy to the region and the second conductive material. ### Claim 2 (depends on 1) The method of claim 1, wherein the first conductive material comprises a conductive layer formed from a metal paste that was heated to form at least a portion of the electrical contact structure, wherein the conductive layer was formed prior to removing the amount of the first conductive material. ### Claim 3 (depends on 2) The method of claim 2, wherein the first conductive material comprises aluminum. ### Claim 4 (depends on 2) The method of claim 2, wherein the metal paste comprises metal particles. ### Claim 5 (depends on 4) The method of claim 4, wherein the metal particles comprise a material selected from the group consisting of aluminum or silver. ### Claim 6 (depends on 1) The method of claim 1, wherein removing the amount of the first conductive material comprises delivering a flow of an abrading material to the region of the electrical contact structure. ### Claim 7 (depends on 6) The method of claim 6, wherein the abrading material has a hardness that is greater than the first conductive material. ### Claim 8 (depends on 7) The method of claim 7, wherein the substrate comprises a second material, and the hardness of the abrading material is less than the hardness of the second material. ### Claim 9 (depends on 8) The method of claim 8, wherein the second material comprises silicon or a silicon-aluminum alloy. ### Claim 10 (depends on 1) The method of claim 1, wherein the depositing a second conductive material comprises: delivering an amount of the second conductive material to the region; and delivering energy to the second conductive material using ultrasonic energy, thermal energy or electromagnetic radiation from a laser. ### Claim 11 (depends on 1) The method of claim 1, wherein the second conductive material comprises an element selected from a group consisting of Pb, Sn, Ag, Bi, In, Sb, Ti, Mg, Ga, or Ce. ### Claim 12 (depends on 1) The method of claim 1, further comprising: depositing a metal paste on the surface of the substrate; and heating the metal paste in a processing environment to form the electrical contact structure, wherein the metal paste comprises metal particles that comprise aluminum. ### Claim 13 (depends on 12) The method of claim 12, wherein processing environment comprises heating the metal paste in air to cause the metal particles to densify. ### Claim 14 (depends on 1) The method of claim 1, further comprising: depositing a metal paste on the surface of the substrate; heating the metal paste in a processing environment to form the electrical contact structure, wherein the metal paste comprises metal particles. ### Claim 15 (depends on 14) The method of claim 14, wherein the metal particles comprise a metal selected from the group of copper (Cu), silver (Ag), gold (Au), tin (Sn), cobalt (Co), rhenium (Rh), nickel (Ni), zinc (Zn), lead (Pb), palladium (Pd), molybdenum (Mo) and aluminum (Al). ### Claim 16 (depends on 14) The method of claim 14, wherein the metal particles comprise silver. ### Claim 17 A method of manufacturing a solar cell device, comprising: forming an electrical contact structure on a surface of a solar cell substrate by heating a metal paste that is disposed on a surface of a solar cell substrate, wherein the metal paste comprises aluminum; removing a portion of the electrical contact structure to expose at least a portion of an inter-diffused region formed in the surface of the solar cell substrate when forming the electrical contact structure, wherein removing the portion of the electrical contact structure comprises delivering a flow of an abrading material to the portion of the electrical contact structure; and depositing a conductive material on the exposed inter-diffused region. ### Claim 18 (depends on 17) The method of claim 17, further comprising: bonding a first conductive element to the conductive material by delivering an amount of energy to the deposited conductive material, wherein the conductive material comprises an element selected from a group consisting of Pb, Sn, Ag, Bi, In, Sb, Ti, Mg, Ga, or Ce. ### Claim 19 (depends on 17) The method of claim 17, wherein the abrading material has a hardness that is greater than the material in the electrical contact structure. ### Claim 20 (depends on 19) The method of claim 19, wherein the substrate comprises a second material, and the hardness of the abrading material is less than the hardness of the second material.