Method of making a hf ldmos structure with a trench type sinker

Abstract

A method of forming an HF power device. The method includes forming a semiconductor layer as a first conductive type on a semiconductor substrate; etching the semiconductor layer forming a first trench; doping an impurity in the neighborhood of the first trench forming a first impurity layer; burying a conduction film into the first trench; etching the semiconductor layer forming a second trench; forming a field oxide film buried into the second trench; forming a gate electrode on a surface of the semiconductor layer; forming a source on the surface of the semiconductor layer; forming a drain area on the surface of the semiconductor layer; forming an LLD area on the surface of the semiconductor layer between the drain area and the gate electrode; forming a first metal electrode; and forming a second metal electrode electrically connected to the LDD area.