Extended drain field effect transistor with trench gate(s) and method

Abstract

Disclosed are a semiconductor structure and method of forming the structure. The semiconductor structure includes an extended drain metal oxide semiconductor field effect transistor (EDMOSFET). The EDMOSFET includes, in the semiconductor layer, a body well, which has a source region therein, and a drain drift well, which abuts the body well and has a drain region therein. A trench gate structure is within the drain drift well positioned laterally between the body-drain drift junction and an internal shallow trench isolation (STI) region and the internal STI region is between the trench gate structure and the drain region. A primary gate structure is on the top surface of the semiconductor layer traversing the body-drain drift junction and optionally extending over the trench gate structure. Gate dielectric material physically separates gate conductor materials of the primary and trench gate structures. Optionally, the EDMOSFET includes more than one trench gate structure.