Patent ID: 11885038
Assignee: SUMCO CORPORATION
Field: Surface technology, coating (Chemistry)
Classification: CPC C | IPC C

Claim 0:
1. A manufacturing method of monocrystalline silicon, comprising:
determining in advance as predetermined conditions, pull-up conditions for achieving a desired value of an oxygen concentration of the monocrystalline silicon when in a right-handed XYZ Cartesian coordinate system defining a center of a surface of a silicon melt as an origin, a vertically upward direction as a positive direction of a Z axis, and a direction in which a horizontal magnetic field is applied as a positive direction of a Y axis, a direction of a convection flow as viewed in a negative direction of the Y axis is a predetermined direction that is one of a clockwise direction and an anticlockwise direction;
applying the 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 the center of the surface and is not in parallel with the central magnetic field line on the horizontal magnetic field as viewed vertically from above;
estimating the direction of the convection flow in the silicon melt in a plane orthogonal to the 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; and
pulling up the monocrystalline silicon, wherein
in the clockwise direction, the convection flow flows in an ascending direction on a left side with respect to the central magnetic field line and flows in a descending direction on a right side with respect to the central magnetic field line,
in the anticlockwise direction, the convection flow flows in the ascending direction on the right side with respect to the central magnetic field line and flows in the descending direction on the left side with respect to the central magnetic field line,
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 as viewed vertically from above,
the first measurement point is located in a negative direction of an X axis with respect to the second measurement point in the XYZ Cartesian coordinate system,
in the estimating of the direction of the convection flow, the direction of the convection flow is estimated to be fixed in the clockwise direction 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 in the anticlockwise direction when the temperature at the first measurement point is lower than the temperature at the second measurement point,
when the estimated direction of the convection flow is not the 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 to fix the direction of the convection flow in the predetermined direction, subsequently the temperatures at the first measurement point and the second measurement point are measured and the direction of the convection flow is estimated,
when the estimated direction of the convection flow is the predetermined direction, the monocrystalline silicon is pulled up on a basis of the predetermined conditions while the intensity of the horizontal magnetic field is kept at 0.2 tesla or more and the direction of the convection is fixed in the predetermined direction.