Patent ID: 6054367
Filing Date: 2000-04-25
Classification: H01L

Abstract:
A method of forming a semiconductor device comprising the steps of:(a) providing a silicon substrate of a first conductivity type having an electrically insulating layer thereon with a first mask over said electrically insulating layer;(b) performing a first implantation step by implanting an impurity of said first conductivity type into said substrate in unmasked regions of said substrate;(c) masking said substrate except for a region immediately adjacent said first mask with a second mask;(d) implanting an impurity of said first conductivity type into said substrate in the unmasked regions of said substrate immediately adjacent said first mask to provide a region of higher impurity concentration in said unmasked region of said substrate immediately adjacent said first mask;(e) causing some of said impurity of said first conductivity type to extend laterally in said substrate beneath said first mask;(f) removing said second mask;(g) oxidizing the exposed portion of said substrate with said first mask thereon to form an electrically insulating layer on said substrate terminating in a bird's beak region extending beneath said first mask with said region of higher impurity concentration of impurities extending along said bird's beak both beneath and external to said first mask; and(h) completing fabrication of a semiconductor device on said substrate.