# US 12,180,078 B2 · Process for producing polycrystalline silicon > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 12,180,078 B2 - Document ID: US12180078B2 - Status: Granted - Kind: B2 - Application number: 17/613,073 - Filed: 2019-05-21 - Published: 2022-08-18 - Granted: 2024-12-31 - Earliest claimed: 2019-05-21 - Assignees: Wacker Chemie AG - Applicants: Wacker Chemie AG - Inventors: Paul Bönisch; Piotr Filar - Web page: https://patentgrep.com/patent/US12180078B2 ## CPC - C01B 33/035: by decomposition or reduction of gaseous or vaporised silicon compounds in the presence of heated filaments of silicon, carbon or a refractory metal, e.g. tantalum or tungsten, or in the presence of heated silicon rods on which the formed silicon is deposited, a silicon rod being obtained, e.g. Siemens process - C01B: NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; {METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C} ## Abstract Method for producing polycrystalline silicon by inducing reaction gas, which in addition to hydrogen contains silane and/or at least one halosilane, into a reaction space of a vapour deposition reactor. The reaction space comprises at least one filament rod heated by the passage of current and on which by means of deposition silicon is deposited to form a polycrystalline silicon rod. A determination of morphology of the silicon rod during deposition at a rod temperature a first resistance R1 of the silicon rod is determined by R 1 = U I where U is a voltage between two ends of the silicon rod and I is a current strength, and a second resistance R2 is determined by R 2 = ρ ⁢ L A were ρ is a resistivity of silicon, L is a length of the silicon rod and A is a cross-sectional area of the silicon rod. A morphology index M is calculated from the ratio R1/R2. ## Claims ### Claim 1 A method for producing polycrystalline silicon, comprising: introducing a reaction gas, which in addition to hydrogen contains silane and/or at least one halosilane, into a reaction space of a vapour deposition reactor, wherein the reaction space comprises at least one filament rod which is heated by way of the passage of current and on which by means of deposition silicon is deposited to form a polycrystalline silicon rod, wherein in a morphology determination step the determination of the morphology of the silicon rod during the deposition at a rod temperature TS wherein a first resistance value Ry of the silicon rod is determined according to R 1 = U I wherein U is a voltage between two ends of the silicon rod and I is a current strength; wherein a second resistance value R2 of the silicon rod is determined according to R 2 = ρ ⁢ L A wherein ρ is a resistivity of silicon, L is a length of the silicon rod, and A is a cross-sectional area of the silicon rod; and wherein a morphology index M is calculated from the ratio R1/R2, wherein the deposition is controlled by varying at least one parameter selected from the group comprising U, I, surface temperature TOF, reaction gas composition and standard volume flow rate in such a way that M has a value from 1 to 1.8, wherein U is in a range from 50 to 500 V, wherein I is in a range from 500 to 4500 A, wherein TOF is in a range from 950 to 1200° C., wherein the standard volume flow rate of the reaction gas is 1500 to 9000 m3/h and the reaction gas prior to entry into the reactor contains hydrogen in a proportion of 50% to 90%, and wherein TS is the surface temperature TOF of the silicon rod or the arithmetic mean of two or more surface temperatures TOF of the same or different silicon rods. ### Claim 2 (depends on 1) The method of claim 1, wherein the index M has a value from 1.2 to 1.6. ### Claim 3 (depends on 1) The method of claim 1, wherein the index M is kept constant during the deposition; or wherein the index M is determined continuously during the entire deposition or discontinuously at various points in time in the deposition; or wherein the index M is determined in discretized form in a time interval corresponding to a specified growth in the diameter of the silicon rod. ### Claim 4 (depends on 1) The method of claim 1, wherein the determination of the cross-sectional area A of the silicon rod at least one diameter of the silicon rod and/or at least one diameter of at least one other silicon rod is determined. ### Claim 5 (depends on 1) The method of claim 1, wherein the length L of the silicon rod is 2 to 8 m. ### Claim 6 (depends on 1) The method of claim 1, wherein the voltage U is in a range from 55 to 250 V. ### Claim 7 (depends on 1) The method of claim 1, wherein the current strength I is in a range from 1500 to 4000 A. ### Claim 8 (depends on 1) The method of claim 1, wherein the temperature of the rod surface TOF is in a range from 1000 to 1150° C. ### Claim 9 (depends on 1) The method of claim 1, wherein the reaction gas prior to entry into the reactor contains hydrogen in a proportion of 60% to 80%. ### Claim 10 (depends on 1) The method of claim 1, wherein the standard volume flow rate of the reaction gas is from 3000 to 8000 m3/h. ### Claim 11 (depends on 1) The method of claim 1, wherein the length L of the silicon rod is 3 to 7 m. ### Claim 12 (depends on 1) The method of claim 1, wherein the length L of the silicon rod is 4 to 6.6 m. ### Claim 13 (depends on 1) The method of claim 1, wherein the length L of the silicon rod is 5.6 to 6.4 m. ### Claim 14 (depends on 1) The method of claim 1, wherein the voltage U is in a range from 60 to 100 V; or wherein the current strength/is in a range from 2500 to 3500 A. ### Claim 15 Method for producing polycrystalline silicon, comprising: introducing a reaction gas, which in addition to hydrogen contains silane and/or at least one halosilane, into a reaction space of a vapour deposition reactor, wherein the reaction space comprises at least one filament rod which is heated by way of the passage of current and on which by means of deposition silicon is deposited to form a polycrystalline silicon rod, wherein for the determination of the morphology of the silicon rod during the deposition at a rod temperature TS wherein a first resistance value Ry of the silicon rod is determined according to R 1 = U I where U is a voltage between two ends of the silicon rod and I is a current strength; wherein a second resistance value R2 of the silicon rod is determined according to R 2 = ρ ⁢ L A wherein ρ is a resistivity of silicon, L is a length of the silicon rod and A is a cross-sectional area of the silicon rod; and wherein a morphology index M is calculated from the ratio R1/R2, wherein the deposition is controlled by varying at least one parameter selected from the group comprising U, I, surface temperature TOF, reaction gas composition and standard volume flow rate in such a way that for the production of a polysilicon type B M has a value of 1.2 to 1.4, or a polysilicon type C M has a value of 1.4 to 1.7, or a polysilicon type D M has a value of greater than 1.7, wherein U is in a range from 50 to 500 V, I is in a range from 500 to 4500 A, TOF is in a range from 950 to 1200° C., the standard volume flow rate of the reaction gas is 1500 to 9000 m3/h and the reaction gas prior to entry into the reactor contains hydrogen in a proportion of 50% to 90%, and wherein TS is the surface temperature TOF of the silicon rod or the arithmetic mean of two or more surface temperatures TOF of the same or different silicon rods. ### Claim 16 (depends on 15) The method of claim 15, wherein the index M has a value from 1 to 1.8. ### Claim 17 (depends on 15) The method of claim 15, wherein the index M is kept constant during the deposition; or wherein the index M is determined continuously during the entire deposition or discontinuously at various points in time in the deposition; or wherein the index M is determined in discretized form in a time interval corresponding to a specified growth in the diameter of the silicon rod. ### Claim 18 (depends on 15) The method of claim 15, wherein the determination of the cross-sectional area A of the silicon rod at least one diameter of the silicon rod and/or at least one diameter of at least one other silicon rod is determined. ### Claim 19 (depends on 15) The method of claim 15, wherein the length L of the silicon rod is 2 to 8 m; or wherein the voltage U is in a range from 55 to 250 V; or wherein the current strength I is in a range from 1500 to 4000 A; or wherein the temperature of the rod surface TOF is in a range from 1000 to 1150° C. ### Claim 20 (depends on 15) The method of claim 15, wherein the reaction gas prior to entry into the reactor contains hydrogen in a proportion of 60% to 80%; or wherein the standard volume flow rate of the reaction gas is from 3000 to 8000 m3/h.