# US 2020/0399780 A1 · Method of estimating convection pattern of silicon melt, method of estimating oxygen concentration of silicon single crystal, method of manufacturing silicon single crystal, and raising device of silicon single crystal > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2020/0399780 A1 - Document ID: US20200399780A1 - Status: Published application - Kind: A1 - Application number: 16/975,563 - Filed: 2019-02-27 - Published: 2020-12-24 - Earliest claimed: 2018-02-28 - Assignees: Sumco Corporation - Applicants: Sumco Corporation - Inventors: Wataru SUGIMURA; Ryusuke YOKOYAMA; Toshiyuki FUJIWARA; Toshiaki ONO - Web page: https://patentgrep.com/patent/US20200399780A1 ## CPC - C30B 15/26: using television detectors; using photo or X-ray detectors - C30B 15/305: {Stirring of the melt} - C30B 15/14: Heating of the melt or the crystallised materials - C30B 15/16: by irradiation or electric discharge - C30B 15/20: Controlling or regulating (controlling or regulating in general G05) - C30B 29/06: Silicon - C30B 30/04: using magnetic fields - 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 A convection pattern estimation method of a silicon melt includes: applying a horizontal magnetic field of 0.2 tesla or more to a silicon melt in a rotating quartz crucible with use of a pair of magnetic bodies disposed across the quartz crucible; before a seed crystal is dipped into the silicon melt to which the horizontal magnetic field is applied; measuring temperatures at a first and second measurement points positioned on a first imaginary line that passes through a center of a surface of the silicon melt and is not in parallel with a central magnetic field line of the horizontal magnetic field as viewed vertically from above; and estimating a direction of a convection flow in a plane in the silicon melt orthogonal to the direction in which the horizontal magnetic field is applied on a basis of the measured temperatures of the first and second measurement points. ## Claims ### Claim 1 A convection pattern estimation method of a silicon melt used for manufacturing monocrystalline silicon, the method comprising: applying a horizontal magnetic field having an intensity of 0.2 tesla or more to the silicon melt in a rotating quartz crucible; before a seed crystal is dipped into the silicon melt applied with the horizontal magnetic field, measuring temperatures at a first measurement point and a second measurement point both positioned on a first imaginary line that passes through a center of a surface of the silicon melt and is not in parallel with a central magnetic field line on the horizontal magnetic field as viewed vertically from above; and estimating a direction of a convection flow in the silicon melt in a plane orthogonal to a direction in which the horizontal magnetic field is applied, on a basis of the measured temperatures at the first measurement point and the second measurement point. ### Claim 2 (depends on 1) The convection pattern estimation method according to claim 1, wherein the first measurement point and the second measurement point are located across a second imaginary line that passes through the center of the surface of the silicon melt and is in parallel with the central magnetic field line of the horizontal magnetic field as viewed vertically from above. ### Claim 3 (depends on 1) The convection pattern estimation method according to claim 1, wherein the first measurement point is located in a negative direction of an X axis with respect to the second measurement point in a right-handed XYZ Cartesian coordinate system defining a center of the surface of the silicon melt as an origin, a vertically upward direction as a positive direction of a Z axis, and a direction in which the horizontal magnetic field is applied as a positive direction of a Y axis, and in the estimating of the direction of the convection flow, as viewed in a negative direction of the Y axis, the direction of the convection flow is estimated to be fixed clockwise when the temperature at the first measurement point is higher than the temperature at the second measurement point, and the direction of the convection flow is estimated to be fixed anticlockwise when the temperature at the first measurement point is lower than the temperature at the second measurement point. ### Claim 4 (depends on 1) The convection pattern estimation method according to claim 1, wherein provided that a distance from the center of the surface of the silicon melt to the first measurement point is denoted as R1, a distance from the center to the second measurement point is denoted as R2, and a radius of an inner diameter of the quartz crucible is denoted as RC, the first measurement point satisfying a formula (1) below and the second measurement point satisfying a formula (2) below are measured, 0.375≤R1/RC<1 (1) 0.375≤R2/RC<1 (2). ### Claim 5 (depends on 1) An oxygen concentration estimation method comprising: conducting the convection pattern estimation method according to claim 1; and estimating an oxygen concentration in a straight body of monocrystalline silicon to be pulled up, on a basis of a prepared relationship between the direction of the convection flow and an oxygen concentration of the monocrystalline silicon, and the direction of the convection flow estimated by the convection pattern estimation method. ### Claim 6 (depends on 1) A manufacturing method of monocrystalline silicon, comprising: conducting the convection pattern estimation method according to claim 1; and pulling up the monocrystalline silicon, wherein in the pulling up of the monocrystalline silicon, when the estimated direction of the convection flow is not a predetermined direction, the intensity of the horizontal magnetic field is lowered to less than 0.01 tesla and subsequently increased to 0.2 tesla or more, and subsequently temperatures at the first measurement point and the second measurement point are measured, when the estimated direction of the convection flow is the predetermined direction, the monocrystalline silicon is pulled up on a basis of predetermined pull-up conditions while the intensity of the horizontal magnetic field is kept at 0.2 tesla or more. ### Claim 7 (depends on 5) A manufacturing method of monocrystalline silicon, comprising: conducting the oxygen concentration estimation method of the monocrystalline silicon according to claim 5; and pulling up the monocrystalline silicon, wherein in the pulling up of the monocrystalline silicon, the monocrystalline silicon is pulled up while the intensity of the horizontal magnetic field is kept at 0.2 tesla or more and at least one of a flow rate of inert gas flowing in a chamber of a pull-up device, an internal pressure of the chamber and a rotation speed of the quartz crucible is adjusted on a basis of the estimated oxygen concentration. ### Claim 8 A pull-up device of monocrystalline silicon, comprising: a quartz crucible; magnetic-field applying portions located across the quartz crucible and configured to apply a horizontal magnetic field to a silicon melt in the quartz crucible; and a temperature sensor configured to measure temperatures at a first measurement point and a second measurement point both positioned on a first imaginary line that passes through a center of a surface of the silicon melt and is not in parallel with a central magnetic field line on the horizontal magnetic field. ### Claim 9 (depends on 8) The pull-up device of the monocrystalline silicon according to claim 8, wherein the first measurement point and the second measurement point are located across a second imaginary line that passes through the center of the surface and is in parallel with the central magnetic field line of the horizontal magnetic field. ### Claim 10 (depends on 8) The pull-up device of the monocrystalline silicon according to claim 8, wherein the temperature sensor measures the first measurement point satisfying a formula (3) below and the second measurement point satisfying a formula (4) below, provided that a distance from the center of the surface of the silicon melt to the first measurement point is denoted as R1, a distance from the center of the surface of the silicon melt to the second measurement point is denoted as R2, and a radius of an inner diameter of the quartz crucible is denoted as RC, 0.375≤R1/RC<1 (3) 0.375≤R2/RC<1 (4). ### Claim 11 (depends on 8) The pull-up device of the monocrystalline silicon according to claim 8, wherein the temperature sensor comprises: a pair of reflectors provided inside a chamber in which the quartz crucible is provided, and each configured to reflect corresponding one of radiation lights from the first measurement point and the second measurement point; and a pair of radiation thermometers provided outside the chamber and configured to receive the radiation lights reflected on the respective reflectors and measure temperatures at the first measurement point and the second measurement point. ### Claim 12 (depends on 11) The pull-up device of the monocrystalline silicon according to claim 11, wherein the pair of reflectors are positioned such that a distance from a lower end of each of the reflectors to the surface of the silicon melt is in a range from 600 mm to 5000 mm. ### Claim 13 (depends on 11) The pull-up device of the monocrystalline silicon according to claim 11, wherein the pair of reflectors each have a reflection surface, and the reflection surface is positioned such that an angle of the reflection surface to a horizontal plane is in a range from 40 degrees to 50 degrees. ### Claim 14 (depends on 8) The pull-up device of the monocrystalline silicon according to claim 8, further comprising: a convection pattern estimation portion configured to estimate a direction of a convection flow in the silicon melt in a plane orthogonal to a direction in which the horizontal magnetic field is applied, on a basis of the temperatures at the first measurement point and the second measurement point measured by the temperature sensor. ### Claim 15 (depends on 14) The pull-up device of the monocrystalline silicon according to claim 14, further comprising: a pull-up controller configured to lower an intensity of the horizontal magnetic field to less than 0.01 tesla and subsequently increase the intensity of the horizontal magnetic field to 0.2 tesla or more and to control the temperature sensor to measure temperatures at the first measurement point and the second measurement point when the direction of the convection flow estimated by the convection pattern estimation portion is not a predetermined direction, and configured to pull up the monocrystalline silicon on a basis of predetermined pull-up conditions while the intensity of the horizontal magnetic field is kept at 0.2 tesla or more when the direction of the convection flow estimated by the convection pattern estimation portion is the predetermined direction. ### Claim 16 (depends on 14) The pull-up device of the monocrystalline silicon according to claim 14, further comprising: a storage configured to store a relationship between the direction of the convection flow and an oxygen concentration of the monocrystalline silicon; an oxygen concentration estimation portion configured to estimate an oxygen concentration in a straight body of the pulled up monocrystalline silicon on a basis of the direction of the convection flow estimated by the convection pattern estimation portion and the relationship stored in the storage; and a pull-up controller configured to adjust at least one of a flow rate of inert gas flowing in a chamber, an internal pressure of the chamber and a rotation speed of the quartz crucible on a basis of the oxygen concentration estimated by the oxygen concentration estimation portion while the intensity of the horizontal magnetic field is kept at 0.2 tesla or more, and to pull up the monocrystalline silicon.