Vertical type semiconductor device provided with an improved construction to greatly decrease device on-resistance without impairing breakdown

摘要

A vertical type semiconductor device is provided with an improved construction which greatly decreases the on-resistance without impairing the breakdown voltage thereof. In the fundamental DMOS cells that control a current to constitute the vertical semiconductor device, through-hole cells are arranged along the sides of a cell having a channel. The through-hole cell includes a through-hole extending from the surface of an n.sup.- -type drift region toward an n.sup.+ -type drain region, and also includes an n.sup.+ -type through-hole region that is formed by diffusing impurities from the inner wall of the through-hole which is continuous with the n.sup.+ -type drain region. A breakdown voltage of the element is maintained by the n.sup.- -type drift region between a p- type well region and the n.sup.+ -type through-hole region or the n.sup.+ -type drain region. Given the unique arrangement of the through-hole cells, the JFET resistance component becomes negligibly small between the DMOS cells neighboring along the sides of the cells despite the fact that the cells are finely formed, and a small on- resistance is exhibited.