Semiconductor device and manufacturing method thereof

A manufacturing method of a semiconductor device, comprising:

• forming a first electrode in a lower portion of a trench which is formed on a semiconductor layer and on a first insulating film between the first electrode and the semiconductor layer;
• forming a second insulating film that covers an inner surface of an upper portion of the trench;
• removing the second insulating film on a side wall of the upper portion of the trench to leave a portion of the second insulating film on the first electrode;
• forming a third insulating film on the side wall of the upper portion of the trench;
• and
• forming a second electrode on the first electrode in an inner portion of the second insulating film.

A semiconductor device comprising:

• a semiconductor layer;
• a first electrode that is provided in a first trench in the semiconductor layer;
• a second electrode that is provided in the first trench on the first electrode in the semiconductor layer, the second electrode including a protruding portion extending toward the first electrode;
• a first insulating film that is provided between the first electrode and the semiconductor layer;
• a second insulating film that is provided between the first electrode and the protruding portion;
• and
• a third insulating film that is provided between the second electrode and the semiconductor layer,
• wherein the second insulating film has a hydrogen concentration that is greater than a hydrogen concentration of the third insulating film.