| 摘要 |
PURPOSE:To enable an element wafer having a highly resistive layer to be formed easily and to solve a problem of impurity compensation, by directly bonding semiconductor substrates each having a high concentration impurity layer of the same conductivity type for forming the element wafer. CONSTITUTION:A mirror polished and highly resistive n<-> type Si substrate (first semiconductor substrate) 11 has an n<+> type layer diffused on its polished surface. This substrate 11 and an n<+> type Si substrate (second semiconductor substrate) 13 also mirror polished are degreased on their polished surfaces, washed with water and spinner dried. Subsequently, their polished surfaces are adhered to each other in a clean atmosphere of Class 1 or lower and heat treated at a temperature of about 1,000-1,200 deg.C, whereby an n<->-n<+> wafer is obtained. If required, the side of the n<-> type Si substrate 11 is polished to obtain a preselected thickness of the n<-> layer, a p<+> type layer 14 is formed by diffusion and electrodes 15 and 16 are provided to produce a p-n<->-n<+> diode. According to this method, any defective bond in the bond area will be prevented from affecting in any way by the n<+> type layer 12 covering the defective part.
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