Shielded gate mosfet and method of manufacturing the same

Abstract

The application provides a shield gate MOSFET and a preparation method thereof. The preparation method comprises the following steps: forming multiple groups of deep grooves in an epitaxial layer; forming a first gate oxide layer; forming a first polysilicon layer; forming a patterned first photoresist layer covering a source terminal leading-out area; removing the first polysilicon layer in the gate terminal leading-out area and the first gate oxide layer on the surface of the epitaxial layer; forming a second gate oxide layer; forming a patterned second photoresist layer covering the source terminal leading-out area; removing part of the second gate oxide layer in the deep groove of the gate terminal leading-out area; and forming a second polysilicon layer. The application forms the first photoresist layer / second photoresist layer covering the main groove and the auxiliary groove of the source terminal leading-out area, avoids the influence of wet etching of the first gate oxide layer / second gate oxide layer on the main groove used for source terminal leading-out in the subsequent process, avoids the side etching of the top side wall of the main groove, thereby avoiding the short connection of the source terminal and the gate terminal, and reducing the IGSS leakage.