Isolated DMOS IC technology

Claim 1

Integrated circuit apparatus comprising: a lightly doped semiconductor substrate of a first conductivity type having a top surface; a covering layer of lightly doped semiconductor material of the first conductivity type, having a top surface and overlying and being contiguous to the top surface of the substrate and defining an interface where the substrate and the covering layer meet; a heavily doped buried layer of a second conductivity type adjacent to a portion of the substrate-covering layer interface; an isolation region in the covering layer that is substantially annular in shape and extends substantially from the buried layer to the top surface of the covering layer, with the isolation region being heavily doped and of the second conductivity type, wherein the buried layer, the isolation region and the top surface of the covering layer define and bound an enclosed region of the covering layer that has a top surface and is electrically isolated from the substrate and from the remainder of the covering layer; a body region of the second conductivity type and of substantially annular shape, positioned within said enclosed region of said covering layer adjacent said isolation region; a first heavily doped region, of the first conductivity type and of substantially annular shape, positioned within the body region and spaced apart from said isolation region; a second heavily doped region, of the first conductivity type, positioned within said enclosed region and spaced apart from the body region; an oxide layer overlying said top surface of said covering layer; a gate region of doped semiconductor material, positioned within the oxide layer, overlying a portion of the first heavily doped region of the first conductivity type and extending toward the second heavily doped region of the first conductivity type, the gate region being substantially annular in shape; a third heavily doped region, of the first conductivity type, positioned within said covering layer outside said isolation region and said enclosed region; a first electrode electrically coupled to said isolation region, to the body region and to the first heavily doped region of the first conductivity type; a second electrode electrically coupled to the second heavily doped region of the first conductivity type; a third electrode electrically coupled to the third heavily doped region of the first conductivity type; and an electrical contact to the gate region.