Source-body self-aligned method of a vertical double diffused metal oxide semiconductor field effect transistor

Abstract

A source-body self-aligned method of a VDMOSFET is provided. A pad layer and an unoxidized material layer are sequentially formed on an epitaxial layer on a semiconductor substrate. A lithography process is then carried out for patterning. Later, a thermal oxidation process is employed such that the unoxidized material layer is oxidized to form oxidation layers. Then, a source ion implantation process is performed, and a wet etching is used to remove the oxidation layers before successively employing a body ion implantation process. By using the process method disclosed in the present invention, it achieves to form the source region and the body region which are self-aligned. Meanwhile, since process complexity of the invention is relatively low, process uniformity and process cost can be optimally controlled. In addition, the invention achieves to reduce channel length and on-resistance, thereby enhancing the reliability effectively.