Patent ID: 6294481
Filing Date: 2001-09-25
Classification: H01L

Abstract:
A method for manufacturing a semiconductor device, comprising:forming a film on a silicon substrate;sequentially etching the film and the silicon substrate to form an element isolating groove, an element forming region being surrounded by the element isolating groove and a residual part of the film on the element forming region;selectively etching a side wall of the residual part of the film to expose an upper end portion of the element forming region;forming a nitrogen doping mask on the silicon substrate, the nitrogen doping mask having an opening corresponding to the residual part of the film and having a width less than a width of the element forming region;forming a nitrogen doped region on the element forming region through the opening of the nitrogen doping mask;removing partially the nitrogen doping mask to expose a surface of the nitrogen doped region, the upper end portion of the element forming region and the upper side wall of the element forming region; andforming a gate insulating film on the exposed surface of the nitrogen doped region, the upper end portion of the element forming region and an upper side wall of the element forming region, by heat treatment in an atmosphere containing an oxidizing agent, a resulting thermal oxidation film having a first portion corresponding to the surface area of the nitrogen doped region and a second portion corresponding to the exposed upper end portion of the element forming region and the upper side wall of the element forming region, and the second portion having a thickness larger than a thickness of the first portion.