Abstract: An integrated semiconductor circuit includes a substrate, an epitaxial layer having transistor base regions, a first and a second (11) insulating oxide layer, and a protective layer. The first oxide layer carries heavily doped polycrystalline layers, including an electric contact layer, a screening layer and a connecting layer. The connecting layer electrically connects the screening layer to the epitaxial layer, through the electric contact layer. The screening layer prevents the occurrence of inversion and parasite components in the epitaxial layer between the base regions. The polycrystalline layer arrangement is simple and can be produced in a common process step. The arrangement is able to withstand high temperatures and enables the second insulating layer to be readily applied.