Patent ID: 7524371

Claim:
A method for manufacturing a defect-free silicon single crystal by the CZ method, comprising the steps of: disposing a heat shield plate to surround the silicon single crystal and cylindrical cooler around the silicon single crystal inside the heat shield plate and adjusting an amount of radiant heat radiated onto the silicon single crystal; and by adjusting a pulling speed of the silicon single crystal, a rotation speed of a crucible that stores molten silicon and a rotation speed of the silicon single crystal, and an output ratio of a multi-heater separated into at least two parts in the longitudinal direction of the silicon single crystal disposed around the crucible, controlling a temperature gradient on a side surface of the silicon single crystal in the longitudinal direction of the silicon single crystal, a height of a solid-liquid interface, and an oxygen concentration in the longitudinal direction of the silicon single crystal, to manufacture a defect-free silicon single crystal, wherein the rotation speed of the crucible is set to 0.5 rpm or more 1 rpm or less, the output of a lower part of the multi-heater in the longitudinal direction is changed depending on the position of the silicon single crystal in the longitudinal direction so as to control the oxygen concentration of the silicon single crystal to a predetermined value, the pulling speed of the silicon single crystal is increased in a first portion of a pulling up of the silicon single crystal as compared with a latter portion thereof, and a distance between a lower edge of the heat shield plate and a surface of the molten silicon is increased when the silicon single crystal is raised in the longitudinal direction in response to the pulling up of the silicon single crystal.