Field-effect semiconductor device having a trench gate electrode and method of making the same

摘要

In a semiconductor device, a p-type base region (2) is provided in an n - -type substrate (1) to extend from a principal surface (1a) of the substrate in a perpendicular direction to the principal surface. An n + -type source region (3) extends in the p-type base region from the principal surface in the perpendicular direction, and an n + -type drain region (4) extends in the substrate separately from the p-type base region with a drift region (1c) interposed therebetween. A trench (5) is formed to penetrate the p-type base region from the n + -type source region in a direction (Y) parallel to the principal surface. A gate electrode (7) is formed in the trench through a gate insulating film (6). Accordingly, a channel region can be formed with a channel width in a depth direction of the trench when a voltage is applied to the gate electrode.