Semiconductor device having isolation regions

Claim 1

A semiconductor device comprising a semiconductor substrate; a semiconductor epitaxial layer overlying one face of said semiconductor substrate; a groove extending from a main surface of said epitaxial layer into said semiconductor substrate through said epitaxial layer and dividing said epitaxial layer into a plurality of island parts; a first insulating film formed on the surface of said groove and on the surfaces of said island parts; a semiconductor layer, serving as an electrode to provide a fixed potential, formed on said first insulating film so as to continuously extend over said groove and said plural island parts, said semiconductor layer filling said groove so as to have its surface substantially flat; a plurality of holes, corresponding to circuit elements formed in each of the island parts, formed in said semiconductor layer, leaving a remaining semiconductor layer which continuously extends over said groove and said plural island parts except for said holes; a second insulating film formed on said remaining semiconductor layer; and electrode layers for circuit elements which are formed in each of said island parts, said electrode layers being formed on said second insulating film so as to extend over a portion of said semiconductor layer into the corresponding hole of said semiconductor layer.