Semiconductor device having IGBT and diode with field stop layer formed of hydrogen donor and helium

A method of manufacturing a semiconductor device, the method comprising:

• irradiating protons from a first main surface of a semiconductor substrate of a first conductivity type using a first predetermined depth as a range, forming a first semiconductor layer of the first conductivity type, the first semiconductor layer containing the protons and having a peak carrier concentration at the first predetermined depth;
• performing a first heat treatment, activating the protons;
• irradiating helium into the semiconductor substrate from the first main surface of the semiconductor substrate using a second predetermined depth that is deeper than the first predetermined depth as the range, thereby introducing lattice defects in the semiconductor substrate;
• and
• performing a second heat treatment to thereby adjust an amount of the lattice defects in the semiconductor substrate,
• wherein the second heat treatment includes forming a second semiconductor layer of the first conductivity type farther on a second main surface side of the semiconductor substrate than the first semiconductor layer, the second semiconductor layer containing protons and helium and contacting the first semiconductor layer.