Semiconductor device and a process for producing a semiconductor device

Claim 1

A semiconductor device having an active region having a predetermined depth and including region carriers, comprising: a semiconductor substrate having a main surface; a defect-free surface region being formed continuously at said main surface of said semiconductor substrate, said defect-free surface region having a bottom face which is non-uniform in depth when measured from said main surface, said bottom face being determined by a first conducting region having a first depth measured from said main surface of said defect-free surface region and a second conducting region having a second depth deeper than that of the first depth; a plurality of semiconductor elements, formed in said defect-free surface region, each depth of said semiconductor elements being non-uniform when measured from said main surface, said semiconductor elements having a conductivity type opposite to that of said semiconductor substrate; and a bulk-defect region having the same conductivity type as that of said semiconductor substrate, formed substantially continuously in said semiconductor substrate and under said defect-free surface region, said bulk-defect region having an upper face adjacent said bottom face of said defect-free region and positioned at a non-uniform depth when measured from said main surface at which said defect-free region is formed, said non-uniform depth of the upper face of said bulk defect region corresponding to the non-uniform depth of said semiconductor elements, the upper face of said bulk-defect region being positioned at a third depth which is spaced at a predetermined distance from the bottom face of said first conducting region and being positioned at a fourth depth which is spaced at a predetermined distance from the bottom face of said second conducting region, and said fourth depth being deeper than said third depth when measured from said main surface of said defect-free surface region.