Reverse conducting power semiconductor device and method for manufacturing the same

A reverse conducting power semiconductor device comprising:

• a semiconductor wafer having a first main side and a second main side opposite to the first main side;
• a plurality of thyristor cells;
• a freewheeling diode;
• and
• a plurality of local lifetime control regions including radiation induced recombination centers;
• wherein each of the plurality of thyristor cells comprises, in an order from the first main side to the second main side:
• a thyristor cathode layer of a first conductivity type;
• a base layer of a second conductivity type different from the first conductivity type, wherein a first p-n junction is formed between the base layer and the thyristor cathode layer;
• a drift layer of the first conductivity type forming a second p-n junction with the base layer;
• a thyristor anode layer of the second conductivity type separated from the base layer by the drift layer;
• a gate electrode arranged lateral to the thyristor cathode layer and forming an ohmic contact with the base layer;
• a thyristor cathode electrode arranged on the first main side and forming an ohmic contact with the thyristor cathode layer;
• and
• a thyristor anode electrode arranged on the second main side and forming an ohmic contact with the thyristor anode layer;
• wherein the freewheeling diode comprises:
• a diode anode layer of the second conductivity type disposed at the first main side, the diode anode layer forming a third p-n junction with the drift layer and being separated from the base layer by the drift layer;
• a diode anode electrode disposed at the first main side and electrically connected to the diode anode layer;
• a diode cathode layer of the first conductivity type disposed at the second main side, the diode cathode layer being electrically connected to the drift layer;
• and
• a diode cathode electrode disposed on the second main side and forming an ohmic contact with the diode cathode layer;
• wherein the diode anode layer comprises a plurality of first diode anode layer segments that are stripe-shaped in an orthogonal projection onto a plane parallel to the second main side, a longitudinal main axis of each first diode anode layer segment extending in a lateral direction away from a lateral center of the semiconductor wafer, wherein lateral relates to a direction parallel to the second main side;
• wherein each first diode anode layer segment has a first lateral width in a direction perpendicular to its longitudinal main axis;
• wherein each local lifetime control region is stripe-shaped and arranged within a corresponding one of the first diode anode layer segments in the orthogonal projection such that a longitudinal main axis of each local lifetime control region extends along the longitudinal main axis of the corresponding one of the first diode anode layer segments;
• wherein each local lifetime control region has a second lateral width that is at least 300 μm less than the first lateral width of the corresponding one of the first diode anode layer segments;
• wherein the diode cathode layer comprises a plurality of diode cathode layer segments;
• wherein each diode cathode layer segment is stripe-shaped and arranged within a corresponding one of the stripe-shaped first diode anode layer segments in the orthogonal projection such that a longitudinal main axis of each diode cathode layer segment extends along the longitudinal main axis of the corresponding one of the first diode anode layer segments;
• and
• wherein each diode cathode layer segment has a third lateral width that is at least 300 μm less than the second lateral width of a corresponding one of the local lifetime control regions.

A method for manufacturing a reverse conducting power semiconductor device that includes a plurality of thyristors and a freewheeling diode, the method comprising:

• providing a semiconductor layer of a first conductivity type, the semiconductor layer having a first side and a second side opposite to the first side, wherein a doping concentration of the semiconductor layer corresponds to a doping concentration of a drift layer in the reverse conducting power semiconductor device;
• providing a first mask layer on the first side of the semiconductor layer, the first mask layer comprising first openings;
• selectively applying a dopant of a second conductivity type to the first side of the semiconductor layer through the first openings of the first mask layer for forming base layers and a diode anode layer of the freewheeling diode;
• forming a second mask layer on the first side, the second mask layer having second openings;
• selectively applying radiation onto the first side through the second openings in the second mask layer for forming local lifetime control regions including radiation induced recombination centers in the semiconductor layer;
• forming a thyristor cathode layer on the first side;
• forming a thyristor anode layer and a diode cathode electrode on the second side;
• and
• forming a diode cathode layer on the second side;
• wherein the second openings comprise stripe-shaped openings that are laterally aligned with regions of the semiconductor layer in which first diode anode layer segments are formed such that, in an orthogonal projection onto a plane parallel to the first side, each second opening is arranged within a projection area of a corresponding one of the first diode anode layer segments, the stripe-shaped openings having a lateral width that is at least 200 μm less than a first lateral width of a corresponding one of the first diode anode layer segments at all positions along a longitudinal main axis of the corresponding one of the first diode anode layer segments.