Patent ID: 7479233
Filing Date: 2009-01-20
Classification: G03F,H01J,Y10T

Abstract:
1. A method of forming a mask used for the charged particle beam exposure made by employing an SOI substrate having a front-side silicon membrane and a back-side silicon layer with a silicon oxide film having a first internal stress interposed therebetween, comprising, sequentially, a step of partially removing the back-side silicon layer of said SOI substrate so as to form an opening as an exposed region; a step of partially removing the silicon oxide film at the portion exposed to the opening; a step of forming an etching stop layer having a lower internal stress than said first internal stress in the opening; a step of etching the front-side silicon membrane of said SOI substrate according to a pattern so as to form a mask pattern; and a step of removing said etching stop layer, wherein said etching stop layer is made of any one selected from the group consisting of Cr, Ta, Mo, W, and Zr and nitrides, oxides, and oxynitrides of theses metals.