Semiconductor device

A semiconductor device, comprising a semiconductor substrate including:

• a drift layer of a first conduction type;
• a base layer and an anode layer of a second conduction type provided in a surface layer on one side of the drift layer;
• an emitter layer selectively provided in the base layer;
• and
• a collector layer of a second conduction type and a cathode layer of a first conduction type provided in a surface layer on the other side of the drift layer,
• the emitter layer, the base layer, the drift layer, and the collector layer providing an IGBT region that operates as an IGBT, and the anode layer, the drift layer, and the cathode layer providing a diode region that operates as a diode adjacent to the IGBT region, wherein:
• the semiconductor substrate further includes a guard ring of a second conduction type, the guard ring being provided in a surface layer of the drift layer in a peripheral region surrounding a device region where the IGBT region and the diode region are adjacent to each other, and the guard ring being applied with voltage having a same potential as the anode layer;
• and
• the cathode layer and the guard ring are positioned such as to satisfy L/d≥1.5, where L is a minimum value of a distance between the cathode layer and the guard ring as projected to a plane parallel to a surface of the semiconductor substrate, and d is a thickness of the semiconductor substrate.