DMOS TRANSISTOR HAVING A TRENCH GATE ELECTRODE AND METHOD OF MAKING THE SAME

摘要

A trench DMOS transistor cell (110) is provided, which is formed on a substrate (111) of a first conductivity type. A body region (115a, 115b), which has a second conductivity type, is located on the substrate. At least one trench extends through the body region and the substrate. An insulating layer (117) lines the trench. The insulating layer includes first (125) and second (127) portions that contact one another at an interface (129). The first portion of the insulating layer has a layer thickness greater than the second portion. The interface is located at a depth above a lower boundary (133) of the body region. A conductive electrode (118) is formed in the trench so that it overlies the insulating layer. A source region (116b, 116c) of the first conductivity type is formed in the body region adjacent to the trench.