Patent ID: 7776708
Filing Date: 2010-08-17
Classification: H01L

Abstract:
1. A method for manufacturing a semiconductor device, said method comprising the steps of: providing a semiconductor device substrate; forming a polysilicon filled trench in said substrate; not oxidizing polysilicon in the polysilicon filled trench; forming over said polysilicon filled trench and said substrate a composite layer stack that comprises a layer of nitride as a top layer; applying a mask and etch process to form a plasma enhanced chemical vapor deposition (PECVD) oxide cap layer over said nitride layer and over said polysilicon filled trench; applying a mask and etch process to etch said composite layer stack in at least one location that is adjacent to said polysilicon filled trench; applying a field oxide process to portions of said substrate that are accessible through said etched portions of said composite layer stack; removing unetched portions of said composite layer stack that are not located under said PECVD oxide cap layer; and forming a gate oxide layer over said substrate and said field oxide portions and said PECVD oxide cap layer.