Bipolar punch-through semiconductor device and method for manufacturing such a semiconductor device

A method of manufacturing a bipolar diode having a drift layer of a first conductivity type on a cathode side and an anode layer of a second conductivity type on an anode side opposite to the cathode side, the anode layer including an anode contact layer and an anode buffer layer, wherein the second conductivity type is different from the first conductivity type, the method comprising the following manufacturing steps in the following order:

• (a) providing a low-doped wafer of the first conductivity type, the wafer having a first side and a second side opposite to the first side, wherein part of the wafer of unamended doping concentration in the finalized diode forms the drift layer;
• (b) applying first ions to the wafer on the second side;
• (c) diffusing the first ions into the wafer up to a first depth;
• (d) applying second ions to the wafer on the second side;
• (e) creating the anode buffer layer by diffusing the first and second ions into the wafer such that a total doping concentration is achieved between 8.0*1015 and 2.0*1016 cm−3 cm in a second depth of 5 μm and between 1.0*1014 up to 5.0*1014 cm−3 in a third depth of 15 μm;
• (f) applying third ions to the wafer on the second side;
• and
• (g) creating the anode contact layer by diffusing the third ions into the wafer up to a fourth depth of at most 5 μm,
• wherein all depths are measured from the second side.