SEMICONDUCTOR DEVICE AND SEMICONDUCTOR DEVICE FABRICATION METHOD

摘要

As an n--type drift layer which is disposed between a first primary face of a first conductive semiconductor substrate whereupon an MOS gate structure is formed and a second primary face which is on the opposite side from the first primary face, provided is a parallel p-n layer (20) of a structure wherein: n-type regions (1) and p-type regions (2) of a structure in which the length is longer in the direction which intersects primary faces of the substrate than the width of the direction which is parallel to the primary faces of the substrate are alternately arrayed in contact in the direction which is parallel to the primary faces of the substrate, and the p-n junctions between the n-type regions (1) and the p-type regions (2) are arrayed in the direction which intersects the primary faces of the substrate. Lower end parts (26) on the second primary face sides of the p-type regions (2) have a configuration in which high-concentration lower end parts of p-type low-concentration regions and low-concentration lower end parts of the p-type low-concentration regions are repeated at a prescribed pitch in the direction which is parallel to the primary faces of the substrate. The trade-off between turn-off loss and turn-off dv/dt is thus improved, and it is possible to provide a superjunction MOS semiconductor device with improved avalanche ruggedness.