SEMICONDUCTOR DEVICE AND SEMICONDUCTOR STORAGE DEVICE

A semiconductor device includes a semiconductor substrate that includes a first surface and a second surface, a semiconductor region between the first and second surfaces, a first well region in the first surface and having one of a donor concentration and a acceptor concentration higher than the semiconductor region, a second well region between the first well region and the second surface and having a higher acceptor concentration than the semiconductor region, a third well region between the second well region and the second surface and having a higher donor concentration than the semiconductor region, a conductor surrounding at least a portion of the first well region along the first surface and extending from the first surface to the third well region in a first direction intersecting the first surface, and an insulator between the conductor and the first well region and between the conductor and the second well region.