Semiconductor IC structure including isolated devices in a single substrate and method for fabricating same

Claim 1

A semiconductor IC structure including a pluralty of devices formed in a substrate and isolated from one another, comprising: a semiconductor base layer for a first conductivity type; a semiconductor substrate of the first conductivity type epitaxially formed on said base layer; a buried layer of a second conductivity type formed in the boundary between said substrate and said base layer; first and second wells of the second conductivity type extending from one surface of said substrate to reach different edges of said buried layer to define an isolated first zone of the first conductivity type in said substrate; at least one third well of the second conductivity type extending from said one surface of said substrate; an emitter- and base-contact region of the second conductivity type formed in said first well; a collector region of the second conductivity type formed in said first zone, said buried layer and said first zone serving as emitter and base regions, respectively; a base-contact and collector region of the first conductivity type formed in said second well; an emitter region of the first conductivity type formed in said second well, said second well serving as a base region; a drain region and a source region both of the first conductivity type formed in a spaced relation in one of said at least one third well; and a first gate formed on a first insulating layer on the surface of said one third well; whereby at least an IIL device and a first conductivity type channel MOS device are constituted in said substrate.