Patent ID: 7597756
Filing Date: 2009-10-06
Classification: C30B,H01L,Y02E,Y02P,Y10T

Abstract:
1. A method of making a monocrystalline or a multicrystalline material blank by a vertical-gradient-freeze method, said method comprising the steps of: a) providing a fixed crucible having side faces and corner areas, said fixed crucible having a rectangular cross section with four corners, a top end and a bottom end, if viewed in a longitudinal direction extending from the bottom end to the top end; b) providing a heating jacket disposed around the crucible, said heating jacket comprising a plurality of heating elements disposed on the side faces of the crucible, said heating elements having a meandering course in the longitudinal direction or perpendicular thereto; c) melting material for the monocrystalline or the multicrystalline material blank in the fixed crucible; d) forming a temperature gradient from the top end to the bottom end in the crucible to initiate crystal growth in the material melted in step c) starting from the bottom end of the crucible by means of a heating device; e) suppressing heat flow perpendicular to the longitudinal direction of the crucible by a controlled heating of the heating jacket disposed around the crucible; and f) providing increased heat output of the heating elements at inversion zones of the meandering course at the corner areas of the rectangular cross section in comparison to heat output at other areas not at the comer areas of the rectangular cross section and/or decreasing a distance between a wall of the crucible and the heating elements at the inversion zones of the meandering course at the comer areas of the rectangular cross section.