Semiconductor device with internal channel stopper

Claim 1

A semconductor device comprising a semiconductor body of relatively high resistivity and of one type conductivity, an epitaxial layer of relatively high resistivity and of one type conductivity on the body forming a semiconductor-semiconductor interface, at least two separated highly doped buried layers of relatively low resistivity and of the opposite type conductivity located at the semiconductor-semiconductor interface and extending into the substrate and into the epitaxial layer, a first circuit element including an active zone built into the epitaxial layer over one of the opposite type buried layers, a second circuit element including an active zone built into the epitaxial layer over the other of the opposite type buried layers, regions of the one type epitaxial layer separating and isolating the circuit elements, and an isolating region of relatively low resistivity and of the one conductivity type located at the semiconductor-semiconductor interface and extending into the substrate and into the epitaxial layer completely between the two opposite type buried layers to prevent the occurrence of a parasitic channel of the opposite conductivity type between the latter along the interface, all of said buried layers having a maximum dopant concentration in the body in the vicinity of the semiconductor-semiconductor interface and a decreasing dopant concentration in the direction of the epitaxial layer surface.