| 摘要 |
PURPOSE:To remarkably improve the radiation resistant properties without deteriorating insulating ability, by providing a hollow element isolation region surrounded by the wall of an Si oxide film, so that the hollow region virtually acts as an air insulating body. CONSTITUTION:A highly doped P-type polycrystalline Si layer 5 is thermally oxidized, whereby a thin Si oxide film 6 is formed on the surface thereof. Photoresist is applied on the whole surface of the oxide film 6 and a lattice- shaped through hole 8 is opened in the film 6. The substrate is wholly dipped in solution of a solvent, hydrazine so that melt of the polycrystalline Si layer 5 is started. A melting process of the polycrystalline layer 5 progresses under sufficient control until a hollow is defined in place of the layer 5. The element isolation region thus hollowed surrounds the trapezoidal substrate 1, and virtually acts as an air insulating body, whose insulating ability depends little on the Si oxide film on the walls thereof. Accordingly, it is possible to improve radiation resistivity without deteriorating element isolating ability by making the oxide film thin.
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