# US 8,569,175 B2 · Method for dry chemical treatment of substrates and also use thereof > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 8,569,175 B2 - Document ID: US8569175B2 - Status: Granted - Kind: B2 - Application number: 12/096,271 - Filed: 2006-12-06 - Published: 2009-08-06 - Granted: 2013-10-29 - Earliest claimed: 2005-12-08 - Assignees: Fraunhofer-Gesellschaft zur Förderung der angewandten Forschung e.V. - Applicants: Stefan Reber; Gerhard Willeke - Inventors: Stefan Reber; Gerhard Willeke - Web page: https://patentgrep.com/patent/US8569175B2 ## CPC - C04B 41/91: involving the removal of part of the materials of the treated articles, e.g. etching - C03C 15/00: Surface treatment of glass, not in the form of fibres or filaments, by etching (etching or surface-brightening compositions, in general C09K13/00) - C04B 41/009: {characterised by the material treated} - C04B 41/5346: {Dry etching} - H10F 71/121: {The active layers comprising only Group IV materials} - H10P 36/03: {within silicon bodies} - H10P 70/12: {by dry cleaning only (H10P70/52 takes precedence)} - Y02E 10/547: Monocrystalline silicon PV cells - Y02P 70/50: Manufacturing or production processes characterised by the final manufactured product - Y10T 428/24479: including variation in thickness - C04B: LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE {(roofing granules E04D7/005)}; CERAMICS (devitrified glass-ceramics C03C10/00); REFRACTORIES; TREATMENT OF NATURAL STONE - C03C: CHEMICAL COMPOSITION OF GLASSES, GLAZES OR VITREOUS ENAMELS; SURFACE TREATMENT OF GLASS; SURFACE TREATMENT OF FIBRES OR FILAMENTS MADE FROM GLASS, MINERALS OR SLAGS; JOINING GLASS TO GLASS OR OTHER MATERIALS - 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 - Y10T: TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION ## Abstract The invention relates to a method for dry chemical treatment of substrates selected from the group comprising silicon, ceramic, glass, and quartz glass, in which the substrate is treated in a heated reaction chamber with a gas which contains hydrogen chloride as etching agent, and also to a substrate which can be produced in this way. The invention likewise relates to uses of the previously mentioned method. ## Claims ### Claim 1 Method for dry chemical treatment of a silicon substrate, in which the substrate is treated in a heated reaction chamber with an etching gas consisting of a chlorine-containing gas and/or a gas which contains at least one chlorine-containing compound and optionally H2 gas, characterised in that, during the treatment, cleaning of the substrate is effected in that the temperature is 700 to 1600° C. and the concentration of the chlorine-containing gas or chlorine-containing compound is in the range of 20 to 100% by volume, such that impurities and/or foreign atoms which are contained in the volume of the substrate are removed at least partially. ### Claim 2 (depends on 1) Method according to claim 1, wherein the foreign atoms are metal atoms. ### Claim 3 (depends on 1) Method according to claim 1, wherein the treatment temperature is 700 to 1000° C. in order to dissolve impurities which are present in the substrate in the form of precipitates. ### Claim 4 (depends on 1) Method according to claim 1, wherein the concentration of the etching gas is chosen such that foreign atoms located in the region of the surface of the substrate are converted into the corresponding chlorides. ### Claim 5 (depends on 1) Method according to claim 1, wherein the temperature and the concentration of the etching gas are coordinated to each other such that the diffusion rate of the foreign atoms in the direction of the substrate surface is greater than the etching rate for the substrate. ### Claim 6 (depends on 1) Method according to claim 1, wherein, during treatment, a surface layer of the substrate is etched isotropically and removed. ### Claim 7 (depends on 6) Method according to claim 6, wherein the surface layer is removed at a thickness in the range of 5 to 50 μm. ### Claim 8 (depends on 6) Method according to claim 6, wherein impurities and foreign atoms released during the etching are removed from the substrate by gas flow. ### Claim 9 (depends on 1) Method according to claim 1, wherein, during treatment, the surface of the substrate is textured isotropically. ### Claim 10 (depends on 1) Method according to claim 1 having the following steps a), b) and c) conducted continually in the same chamber: a) a substrate made of silicon is treated by gettering with an etching gas comprising a chlorine-containing gas or a gas which contains a chlorine-containing compound at a temperature in the range of 700 to 1600 ° C. in order to remove impurities and/or foreign atoms from the volume of the substrate, b) removal of a surface layer of the substrate in order to remove crystal damage on the surface of the substrate and c) isotropic texturing of the surface of the substrate, step a) being implemented before, after or at the same time as step b) or all the steps a) to c) being implemented at the same time. ### Claim 11 (depends on 10) Method according to claim 10, further comprising, after steps a), b) and c), in a step d), a layer made of silicon is deposited on the substrate by at least partial replacement of the etching gas for a deposition gas which contains chlorosilanes. ### Claim 12 (depends on 11) Method according to claim 11, further comprising, after step d), in a step e), an isotropic texturing of the layer deposited in step d) is effected in order to increase the light exploitation. ### Claim 13 (depends on 12) Method according to claim 12, further comprising, after step d), in a step f), a layer made of silicon is deposited by at least partial replacement of the etching gas for a deposition gas which contains chlorosilanes with complementary doping in order to produce a pn-transition, step f) being implemented before or after step e). ### Claim 14 Method for texturing a silicon wafer, in which a silicon wafer is treated in a heated reaction chamber with a texturing gas consisting of a chlorine-containing gas or a gas which contains at least one chlorine-containing compound and optionally H2 gas at a temperature of 900 to 1100 ° C., wherein the concentration of the chlorine-containing gas or chlorine-containing compound is in the range of 20 to 100% by volume. ### Claim 15 (depends on 10) A silicon substrate prepared by the method according to claim 10. ### Claim 16 (depends on 1) Method according to claim 1 for cleaning a volume of substrates, which volume of substrates are silicon wafers. ### Claim 17 (depends on 6) Method according to claim 6 wherein surface impurities are removed from the substrate. ### Claim 18 (depends on 6) Method according to claim 6 wherein crystal damage is removed from the substrate. ### Claim 19 (depends on 10) Method according to claim 10 wherein the substrate is a silicon wafer and the method produces a textured silicon wafer. ### Claim 20 (depends on 1) Method according to claim 1, wherein the foreign atoms are iron atoms. ### Claim 21 (depends on 6) Method according to claim 6, wherein the surface layer is removed at a thickness in the range of 10 to 20 μm.