Patent ID: 7276411
Filing Date: 2007-10-02
Classification: H01L

Abstract:
1. A process of fabricating a trench semiconductor device comprising: providing a semiconductor material; forming a trench in said semiconductor material, said trench extending from a surface of said semiconductor material into said semiconductor material; after forming said trench, directionally depositing a first oxide layer on said semiconductor material, said first oxide layer depositing preferentially on horizontal surfaces so as to form a thick portion in a bottom of said trench and a thin portion on a sidewall of said trench, said thick portion being thicker than said thin portion; after depositing a first oxide layer, depositing a polysilicon layer, said polysilicon layer filling said trench and overflowing said surface of said semiconductor material; removing a sufficient amount of said polysilicon layer such that a surface of said polysilicon layer is substantially coplanar with said surface of said semiconductor material, said removing comprising chemical-mechanical polishing; forming a second oxide layer over said surfaces of said polysilicon layer and said semiconductor material; forming a mask layer over said second oxide layer; and etching said second oxide layer through an opening in said mask layer so as to leave a portion of said second oxide layer overlying said surface of said polysilicon layer and a portion of said surface of said semiconductor material.