| 摘要 |
PURPOSE: To form an insulation layer beneath an epitaxial silicon by growing a defect-free silicon epitaxially. CONSTITUTION: A multilayer structure including a first p<++> silicon layer 12 is grown on a substrate wafer 10 by low temperature epitaxy and then an intrinsic silicon layer 14, a second p<++> silicon layer 16 and a p-silicon layer 18 are formed sequentially thereon. Subsequently, trenches 24, 26 are made through the p-silicon layer 18, the second p<++> silicon layer 16 and the intrinsic silicon layer 14 into the first p<++> silicon layer 12. When etching is continued for a time long enough to remove the underside of the p<++> silicon layer thoroughly, the intrinsic silicon layer 14 is removed and an air gap is provided between first and second p<++> silicon layers. Finally, insulation layers of silicon oxide are formed above and below the air gap by oxidation process.
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