APPARATUS FOR PULLING UP SINGLE CRYSTAL

摘要

PROBLEM TO BE SOLVED: To produce a high-quality single crystal high in withstand voltage of oxide film in high productivity in an apparatus for pulling up a single crystal by a so-called Czochralski(CZ) method for producing a semiconductor single crystal such as silicon. SOLUTION: A radiation screen 1 is divided into at least three or more heat insulating members and a part of the heat insulating members are made detachable so that the heat insulating performances of the radiation screen 1 can be partially changed. The heat insulating members comprises two or more members different in heat insulating performances. The radiation screen 1 divided into the three or more heat-insulating members consists of an upper end part 6, an intermediate part and a lower end part 5. The intermediate part has lower heat insulating performances than those of the upper end part and the lower end part. A temperature zone between about 1,000 deg.C and 1,200 deg.C is enlarged to prolong a passage time at the intermediate part.