Semiconductor device and manufacturing method

A semiconductor device comprising:

• a semiconductor substrate having a transistor section and a diode section, wherein
• both the transistor section and the diode section each have:
• a drift region of a first conductivity-type provided inside the semiconductor substrate, and
• a base region of a second conductivity-type provided above the drift region inside the semiconductor substrate,
• inside the semiconductor substrate, a lifetime control region including lifetime killers is provided below the base region from at least a part of the transistor section to the diode section, and
• in the transistor section, a threshold value adjusting section for adjusting a threshold value of the transistor section is provided overlapping the lifetime control region as seen from an upper surface of the semiconductor substrate, the threshold value adjusting section includes a thickened portion Wgi of a gate insulating film in a gate trench section adjacent to the base region, the thickened portion having a dielectric constant less than or equal to 0.9 times a remaining portion of the gate insulating film in the gate trench section.