Method of producing high-quality silicon single crystals

Abstract

A method of producing high-quality and large-diameter single crystals by the Czochralski method is disclosed which can provide wafers with a minimized number of such grown-in defects as dislocation clusters and laser scattering tomography defects. Specifically, it is a method of producing silicon single crystals which comprises carrying out the crystal pulling while maintaining the solid-melt interface during pulling in the shape of an upward convex with the central portion of the interface being higher by at least 5 mm than the peripheral region thereof and while applying a magnetic field, and optionally in addition to the above, while maintaining the temperature gradient in the direction of axis of pulling in the peripheral region at a level lower than that in the central portion in the range of from the melting point to 1,200° C. In this case, it is desirable that the portion of the single crystal surface lying at least 50 mm above the melt surface be shielded from direct radiant heat from the heater and/or crucible wall, that a horizontal magnetic field of 0.08 to 0.3 T be applied in parallel with the melt surface or a cusped magnetic field showing an intensity of 0.02 to 0.07 T at a crucible wall site on the melt surface be applied and that the crucible be rotated at a speed of not more than 5 min and the single crystal at a speed of not less than 13 min .