# US 9,039,833 B2 · Method for the production of solar grade silicon > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 9,039,833 B2 - Document ID: US9039833B2 - Status: Granted - Kind: B2 - Application number: 13/203,493 - Filed: 2010-02-25 - Published: 2011-12-15 - Granted: 2015-05-26 - Earliest claimed: 2009-02-26 - Applicants: Harsharn Tathgar - Inventors: Harsharn Tathgar - Web page: https://patentgrep.com/patent/US9039833B2 ## CPC - C01B 33/021: Preparation (chemical coating from the vapour phase C23C16/00) - C01B 33/037: Purification (by zone-melting C30B13/00) - C30B 17/00: Single-crystal growth onto a seed which remains in the melt during growth, e.g. Nacken-Kyropoulos method (C30B15/00 takes precedence) - C30B 21/00: Unidirectional solidification of eutectic materials - C30B 29/06: Silicon - C01B: NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; {METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C} - C30B: SINGLE-CRYSTAL GROWTH (by using ultra-high pressure, e.g. for the formation of diamonds, B01J3/06); UNIDIRECTIONAL SOLIDIFICATION OF EUTECTIC MATERIAL OR UNIDIRECTIONAL DEMIXING OF EUTECTOID MATERIAL; REFINING BY ZONE-MELTING OF MATERIAL (zone-refining of metals or alloys C22B); PRODUCTION OF A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE (casting of metals, casting of other substances by the same processes or devices B22D; working of plastics B29; modifying the physical structure of metals or alloys C21D, C22F); SINGLE CRYSTALS OR HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; AFTER-TREATMENT OF SINGLE CRYSTALS OR A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE (for producing semiconductor devices or parts thereof H10); APPARATUS THEREFOR ## Abstract The present invention relates to a method for the preparation of solar grade silicon comprising crystallization of large high purity silicon crystals in a hyper eutectic binary or ternary alloy containing silicon, or a refined silicon melt, wherein small silicon crystals are added to the melt and the resulting large silicon crystals are separated from the melt. The separation may be performed by centrifugation or filtration. ## Claims ### Claim 1 A semi-continuous process for the formation, separation and melting of large and pure silicon crystals of a size of 1-5 mm, wherein a prepurified binary or ternary hypereutectic alloy containing Si melt is transferred to a furnace having a temperature gradient from top to bottom, small and pure silicon crystals of a size of 100-200 μm are then added to the melt in the furnace and grow due to the temperature difference until the melt in the furnace reaches eutectic composition, whereupon the melt is transported from the furnace and brought to the hypereutectic state, is then returned to the furnace and the process is repeated until an amount of large (1-5 mm) Si crystals has been formed. ### Claim 2 (depends on 1) The process according to claim 1, wherein the prepurification and the provision of the melt to hypereutectic state is performed in a first furnace connected to the furnace used in the said method. ### Claim 3 (depends on 1) The process according to claim 1, wherein the alloy is a binary Al—Si alloy. ### Claim 4 (depends on 2) The process according to claim 2, wherein the alloy is a binary Al—Si alloy. ### Claim 5 (depends on 1) The process according to claim 1, whereby the melt containing large (1-5 mm) silicon crystals obtained in the furnace is transferred to a centrifugal kept just above the eutectic temperature of the melt, whereupon the crystals are pushed towards the walls of the centrifugal and Si containing melt will remain in the middle thereof and is decanted from the centrifugal. ### Claim 6 (depends on 2) The process according to claim 2, whereby the melt containing large (1-5 mm) silicon crystals obtained in the furnace is transferred to a centrifugal kept just above the eutectic temperature of the melt, whereupon the crystals are pushed towards the walls of the centrifugal and Si containing melt will remain in the middle thereof and is decanted from the centrifugal. ### Claim 7 (depends on 1) The process according to claim 1, wherein the crystals obtained are re-melted and cast as ingots to be used in the solar grade silicon. ### Claim 8 (depends on 2) The process according to claim 2, wherein the crystals obtained are re-melted and cast as ingots to be used in the solar grade silicon. ### Claim 9 (depends on 5) The process according to claim 5, wherein the crystals obtained are re-melted and cast as ingots to be used in the solar grade silicon. ### Claim 10 An apparatus for the preparation of solar grade silicon, the apparatus comprising: a first furnace; and a second furnace connected to the first furnace; wherein the apparatus is arranged to allow a binary or ternary hypereutectic alloy containing silicon melt to be made in the first furnace and transferred to the second furnace; wherein the second furnace is arranged to have a temperature gradient with a higher temperature at the top of the furnace and a lower temperature at the bottom of the furnace and is arranged to be fed with pure silicon crystals of a size of 100-200 μm which grow in the melt to form larger (1-5 mm) silicon crystals; and wherein the apparatus is arranged to pump melt from the second furnace to the first furnace through a ceramic filter when the melt in the second furnace reaches eutectic composition.