Semiconductor device

A semiconductor device comprising a semiconductor substrate and a first semiconductor element provided on the semiconductor substrate,

• the first semiconductor element including:
• a first semiconductor layer of a first conductivity type provided on the semiconductor substrate;
• a second semiconductor layer of the first conductivity type provided on the first semiconductor layer;
• a third semiconductor layer of the first conductivity type provided on the first semiconductor layer to be adjacent to the second semiconductor layer;
• a first insulating layer provided from a surface of the second semiconductor layer into an interior of the second semiconductor layer and from a surface of the third semiconductor layer into an interior of the third semiconductor layer;
• a first base region of a second conductivity type selectively provided on the surface of the second semiconductor layer;
• a first source region of the first conductivity type selectively provided on a surface of the first base region;
• a first gate electrode provided from a surface of the first insulating layer into an interior of the first insulating layer, the first gate electrode being adjacent to the first base region with the first insulating layer interposed;
• a first drift layer of the first conductivity type provided inside the second semiconductor layer under the first base region to extend from a surface of the first semiconductor layer toward the first base region side;
• a first drain region of the first conductivity type provided on the surface of the third semiconductor layer to oppose the first source region with the first insulating layer interposed;
• a first source electrode electrically connected to the first source region;
• and
• a first drain electrode electrically connected to the first drain region,
• a concentration of an impurity element of the first conductivity type included in the first drift layer being lower than a concentration of an impurity element of the first conductivity type included in the first semiconductor layer,
• the concentration of the impurity element of the first conductivity type included in the first drift layer being higher than a concentration of an impurity element of the first conductivity type included in the second semiconductor layer.