Silicon carbide semiconductor device, power converter, method of manufacturing silicon carbide semiconductor device, and method of manufacturing power converter

A silicon carbide semiconductor device, comprising:

• a drift layer formed of silicon carbide, having a first conductivity type;
• a body region provided on the drift layer, having a second conductivity type different from the first conductivity type;
• a source region provided on the body region, having the first conductivity type;
• a gate insulating film provided inside at least one gate trench reaching a position deeper than the body region in a depth direction, facing the body region and the source region, the gate trench having a width direction perpendicular to the depth direction;
• a gate electrode provided inside the gate trench, facing the body region with the gate insulating film interposed therebetween;
• a source electrode electrically connected to the source region;
• a trench bottom protective layer being in contact with a bottom portion of the gate trench, having the second conductivity type with an impurity concentration higher than that of the body, region;
• a depletion suppressing layer provided between a side surface of the gate trench and the drill layer in the width direction, being in contact with a side surface of the trench bottom protective layer, extending from a lower portion of the body region up to a position deeper than the bottom portion of the gate trench, having the first conductivity type, and having an impurity concentration of the first conductivity type higher than that of the drift layer, and
• a high impurity concentration region disposed between the body region and the depletion suppressing layer in the depth direction, being in contact with the drift layer, having the first conductivity type, and having an impurity concentration of the first conductivity type higher than that of the drift layer,
• wherein the impurity concentration of the first conductivity type of the depletion suppressing layer is reduced as the distance from the side surface of the gate trench becomes larger, and
• an impurity concentration of an entirety of the drift layer is lower than that of an entirety of the depletion suppressing layer.