| 摘要 |
PURPOSE:To provide an SOI substrate of thick wall wherein occurrence of crystal defect, mainly consisting of OSF, is prevented. CONSTITUTION:The first silicon wafer which well act as an active layer for forming a semiconductor element is of interstitial oxygen concentration 16ppm or below. On its coupling side, a silicon oxide film is formed by thermal- oxidation, and the silicon oxide film of the first silicon wafer and the second silicon wafer which will act as a supporting member are directly piled together, and then coupling thermal treatment at high temperature is done, thus a coupling wafer is obtained. Then, by cutting and grinding the first silicon wafer side of the caupling wafer, a so called thick SOI substrate of 5mum or thicker which contains single crystal silicon layer with no contained OSF is obtained an the second silicon wafer with a silicon oxide film in between.
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