| 摘要 |
PURPOSE:To reduce a leaking current and to improve withstand voltage, by forming a porous semiconductor surrounding each element region, and transforming said porous semiconductor into an insulator. CONSTITUTION:A high concentration p<+> type layer 7 is formed on a p type silicon substrate 6, then an n type epitaxial layer 8 is formed. With an insulating film 9 as a mask, n type impurities are diffused, and a high concentration n<+> type layer 10 is formed. After the insulating film 9 has been removed, an n type epitaxial layer 11 is further formed. An insulating film 12 is formed on an n type layer 11. With this film as a mask, p type impurities are diffused so as to reach the p<+> type layer 7 and the n<+> type region 10, and a high concentration p<+> type layer 13 is formed. Then, anodizing processing is performed on the substrate, and the p<+> type regions 13 and 7 are transformed into porous silicon. Thereafter, thermal oxidation treatment is performed, and the porous silicon is transformed into silicon oxide 15. Thus the semiconductor island region surrounded by the insulating film can be obtained. |
