| 摘要 |
PROBLEM TO BE SOLVED: To provide a silicon wafer which is a low-oxygen silicon wafer, has a DZ layer of an uniform thickness on a surface layer, and has an IG layer inside the wafer. SOLUTION: The low-oxygen silicon wafer is low-temperature heat-treated at 550-800 deg.C and high-temperature heat-treated at 1,000-1,200 deg.C after a oxygen- precipitation core is produced in the wafer. Thereby, the oxygen in the surface layer of the wafer is diffused from the wafer surface to the outside, the oxygen- precipitation core is stabilized (more than a critical core), and the DZ layer is produced. When the wafer is then heated at 750-1,100 deg.C, oxygen is trapped by the oxygen-precipitation core inside the wafer, and an oxygen deposit grows. As the result, the IG layer 12 is formed. Thus, even if in the low-oxygen silicon wafer 10, the DZ layer 11 having an uniform width in the direction of thickness is formed on the surface layer of the wafer, and the wafer where the IG layer 12 is formed inside is attained.
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