Semiconductor device and method for manufacturing the same

A semiconductor device, comprising:

• a first electrode,
• a first semiconductor region of a first conductivity type provided on the first electrode and electrically connected to the first electrode,
• a second semiconductor region of a second conductivity type provided on the first semiconductor region,
• a third semiconductor region of the first conductivity type provided on the second semiconductor region,
• an opening being arranged with a portion of the first semiconductor region, the second semiconductor region, and the third semiconductor region in a second direction perpendicular to a first direction, the first direction being from the first electrode toward the first semiconductor region, a side wall of the opening including a plurality of recesses and a plurality of protrusions alternately provided in the first direction, each one of the plurality of recesses being recessed from the opening toward the first semiconductor region in the second direction, and each one of the plurality of protrusions protruding from the first semiconductor region toward the opening in the second direction,
• a conductive portion provided inside the opening with an insulating portion interposed, and being arranged with the first semiconductor region in the second direction,
• a gate electrode provided inside the opening with the insulating portion interposed, and being arranged with the second semiconductor region in the second direction, and
• a second electrode provided on the third semiconductor region and electrically connected to the third semiconductor region.