Bipolar epitaxial cascode with low-level base connection

A semiconductor device with a semiconductor body provided with a first and a second bipolar transistor in a cascode configuration with collector, base and emitter regions which form pn junctions with one another which extend parallel to a main surface of the semiconductor body, said semiconductor body comprising

• a semiconductor substrate of a first conductivity type which forms the collector region of the first transistor and is provided with a connection electrode on a first main surface of the substrate;
• a first semiconductor region of the second, opposite conductivity type adjoining the substrate and forming the base region of the first transistor;
• a second semiconductor region of the first conductivity type adjoining the first region and forming the emitter region of the first transistor and forming the collector region of the second transistor;
• a third semiconductor region of the first conductivity type adjoining the second region and more weakly doped than the second region;
• a fourth semiconductor region of the second conductivity type adjoining the third region and a second main surface of the semiconductor body and forming the base region of the second transistor, which fourth semiconductor region is provided with a connection electrode;
• and
• a fifth semiconductor region of the first conductivity type adjoining the fourth region and the second main surface of the semiconductor body and forming the emitter region of the second transistor, said fifth region being provided with a connection electrode;
• characterized in that a depression is provided in the second main surface of the semiconductor body which cuts through the second, third, and fourth regions and laterally bounds these regions, while a connection electrode for the first region, which forms the base region of the first transistor, is provided in the depression.