High-frequency transistor with low internal capacitance and low thermal resistance

Claim 1

A high-frequency transistor comprising a semiconductor body of silicon having a highly-doped substrate of a first conductivity type, a more weakly-doped epitaxial layer of the first conductivity type on said substrate, a layer-shaped base region of a second conductivity type opposite to that of the first provided in the epitaxial layer, a pattern of silicon oxide at least partly countersunk into the epitaxial layer and subdividing the base region into a number of mutually-separated base zones, and conducting layers located partly on the isolating pattern for interconnecting said base zones, at least one emitter zone of the first conductivity type being provided in each base zone, the conducting layers each comprising a silicon layer of the second conductivity type, thin oxide layers extending into the base zone and covering at least an edge of each conducting layer, and the emitter zones being laterally bounded by said thin oxide layers such that in projection the edge of the silicon layer is about the thickness of the thin oxide layers away from the emitter zone.