| 摘要 |
PURPOSE: To prepare a monocrystalline silicon region isolated from a silicon substrate with a silicon dioxide substrate by selectively isolating the island of an epitaxial layer, for which a porous epitaxial layer is oxidized and slightly doped, from the substrate. CONSTITUTION: A comparatively thick layer 2 of silicon dioxide and the photolithographically patterned layer of photoregist 3 are formed on a monocrystalline silicon substrate 1, the silicon dioxide exposed in an area to form an epitaxial silicon island and substrate areas 4 and 6 matching it are removed. When the epitaxial growth reaches a plane sufficiently higher than the surface of the substrate 1, extremely slight doping of the same impurity type is performed. When the substrate 1 is made into anode, a current is conducted through severly doped layers 7 and 8 of hairy epitaxial structure, these layers are made porous and when the porous silicon under slightly doped epitaxial silicon regions 9 and 10 is sufficiently converted to the silicon dioxide dielectric, oxidization is completed. Thus, the epitaxial silicon region electrically isolated from the silicon substrate can be provided.
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