Patent ID: 7323048
Filing Date: 2008-01-29
Classification: C30B

Abstract:
1. A method for producing a single crystal with pulling the single crystal from a raw material melt in a chamber by Czochralski method, wherein when growing the single crystal, where a pulling rate is defined as V (mm/min), a temperature gradient of the crystal at the vicinity of solid-liquid interface at a central portion of the crystal is defined as Gc (° C./mm), and a temperature gradient of the crystal at the vicinity of solid-liquid interface at a peripheral portion of the crystal is defined as Ge (° C./mm) during growing a straight body of the single crystal, during pulling the single crystal, the temperature gradient Gc of the crystal at the central portion of the crystal and the temperature gradient Ge of the crystal at the peripheral portion of the crystal are controlled by changing a distance between a melt surface of the raw material melt and a heat insulating member provided in the chamber so as to oppose to the surface of the raw material melt, thereby ΔG=|(Gc−Ge)| which is difference between the temperature gradient Gc at the central portion of the crystal and the temperature gradient Ge at the peripheral portion of the crystal is 0.5° C./mm or less, and also V/Gc (mm 2 /° C.·min) which is a ratio of the pulling rate V and the temperature gradient Gc at the central portion of the crystal is controlled so that a single crystal including a desired defect region is grown.