Abstract: An area (7a) on epitaxial layer 2a) is doped negatively (n). A thick oxide layer (16) is grown around an active area of a bipolar transistor (BIP) and field effect transistor (FET). The active area is oxidized to an oxide layer (19) which is coated with a polycrystalline silicon layer (20a). A weak positive LDD doping, is carried out in an area (P) between this silicon layer (20a) and the silicon dioxide layer (16). A heavily negative doping (n+) is carried out on one side of the polycrystalline layer (20a) for constituting emitter (E) of the bipolar transistor (BIP). Its collector consists of the doped epitaxial layer (7a) which is connected to a polycrystalline layer (20c) on the silicon dioxide layer (16). A heavy, positive doping (p+) is carried out on the other side of the polycrystalline layer (20a) to constitute collector/emitter of the (FET), which is connected to the bipolar transistor (BIP) in a Darlington circuit.

Abstract: An epitaxial layer (2a) is grown on a substructure (1) of semiconductor material, an area (7a) on said layer being doped negatively (n). A thick oxide layer (16) is grown around an area which is the active area of a bipolar transistor (BIP) and field effect transistor (FET). The active area is oxidized to an oxide layer (19) which is coated with a polycrystalline silicon layer (20a). A weak positive doping, so-called LDD doping, is carried out in an area (P) between this silicon layer (20a) and the silicon dioxide layer (16). A heavily negative doping (n+) is carried out on one side of the polycrystalline layer (20a) for constituting emitter (E) of the bipolar transistor (BIP). Its collector consists of the doped epitaxial layer (7a) which is connected to a polycrystalline layer (20c) on the silicon dioxide layer (16).