Patent ID: 6153008
Filing Date: 2000-11-28
Classification: C30B,Y10T

Abstract:
Method for pulling a silicon single crystal, and said silicon single crystal having a crystallization boundary region, comprising the steps ofpulling the silicon single crystal from a silicon melt at a pull rate V selected in such a way that the ratio V/G has the value of 1.3*10.sup.-3 cm.sup.2 min.sup.-1 K.sup.-1 .+-.10%, and G is an axial temperature gradient in the silicon single crystal in the region of the crystallization boundary and in order to improve a radial homogeneity of G;providing a heat shield annularly surrounding said silicon single crystal and having a lower edge; and connecting an element to the lower edge of the heat shield,said element annularly surrounding the silicon single crystal and said element having a face directed at the silicon single crystal, and said element face annularly surrounding the silicon single crystal substantially level with the crystallization boundary; andthermally affecting the silicon single crystal by using said element surrounding said crystal substantially level with the crystallization boundary region; andsaid thermally affecting comprises having heat radiation radiating from said silicon single crystal and the silicon melt to said face of said element; andreflecting said heat radiation from the silicon single crystal and the silicon melt back to the crystallization boundary region using said face of the element;thereby avoiding any substantial variation in the axial temperature gradient in the region of the crystallization boundary in the radial direction.