| 摘要 |
PROBLEM TO BE SOLVED: To provide a preheat treatment capable of making fine adjustments to the size of an oxygen-precipitating nucleus, and to provide a silicon wafer with uniform BMD density which is obtained by the preheat treatment. SOLUTION: Wafers are sliced from one nitrogen-doped silicon single-crystal ingot, and the position of each wafer on the ingot is characterized, by associating the nitrogen density and the oxygen density contained in each wafer to each other. The wafers are classified into a group which is not to be subjected to a process, wherein a wafer at each position on the ingot is retained at a temperature lower than the treatment temperature, a group to be subject to this process under a single condition, and a group which is to be subjected to this process under two or more conditions. COPYRIGHT: (C)2009,JPO&INPIT
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