| 摘要 |
PROBLEM TO BE SOLVED: To recycle a quartz crucible, which has been used for growing a silicon single crystal, into that of a quality level equal to the quality of a new crucible. SOLUTION: Foreign matters stuck on the inner surface of a used quartz crucible are removed by cleaning the inner surface with an acid solution. Then, after removing the foreign matters, the inner surface is subjected to heat treatment at >=1600 deg.C in order to recover the inner surface from the cristobalited state to the amorphous state.
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