Dielectric material separated-type, high breakdown voltage semiconductor circuit device, and production method thereof

Abstract

A dielectrically isolated semiconductor device of high reliability is provided by realizing a fine and deep element isolating region which can prevent dislocation of an oxide film as an insulation layer by oxidation-induced stress. The dielectrically isolated semiconductor device includes an SOI substrate supporting an active element layer deeper than an expanded distance of a depletion layer subjected to the highest voltage applied to the device, and an element isolating region which encloses the active element layer. The element isolating region contains a deep trench which comes into contact with the insulation layer, and which is filled with n heavily doped layers on both side walls, second insulation films each adjacent to the n heavily doped layer and a polycrystalline semiconductor layer formed between the second insulation films.