Method of inspecting silicon carbide semiconductor device

A method of inspecting a silicon carbide semiconductor device having a semiconductor chip containing silicon carbide;

• a first semiconductor region of a first conductivity type, provided in the semiconductor chip;
• a second semiconductor region of a second conductivity type, provided between a first surface of the semiconductor chip and the first semiconductor region;
• a plurality of third semiconductor regions of the first conductivity type, each selectively provided between the first surface of the semiconductor chip and the second semiconductor region;
• a gate insulating film provided in contact with a portion of the second semiconductor region between the first semiconductor region and one of the third semiconductor regions;
• a gate electrode provided on the second semiconductor region via the gate insulating film;
• a first electrode electrically connected to the second semiconductor region and the third semiconductor regions;
• and a second electrode provided on a second surface of the semiconductor chip, the method comprising:
• energizing a parasitic diode by inputting a first pulse signal having a first duty cycle, as a first process, the parasitic diode being formed by a pn junction between the second semiconductor region and the first semiconductor region;
• passing a predetermined first current through the semiconductor chip in a direction from the second electrode to the first electrode by inputting a second pulse signal, and measuring a first voltage applied to the second electrode and positive with respect to the first electrode while the second pulse signal is ON, as a second process;
• terminating input of the first pulse signal, thereby terminating energization of the parasitic diode, as a third process;
• calculating, as a fourth process, a first difference between two measured values of the first voltage obtained at different times after the first process but before the third process, by performing the second process on the semiconductor chip, the semiconductor chip having generated heat due to the first process;
• and
• identifying the semiconductor chip for which the first difference is within a first predetermined range to be a conforming product, as a fifth process.