Method for manufacturing semiconductor device

Abstract

A method for manufacturing a semiconductor device comprises etching a semiconductor substrate having an insulation film as mask using a mixed gas composed of HBr and CHF3, thereby having a reaction product composed of the semiconductor substrate and reaction gas to be adhered gradually on the side walls of the mask, and as a result creating a trench having a sufficient roundness formed to the upper end portion thereof.

1 . A method for manufacturing a semiconductor device comprising the steps of: 
 forming a multilayer film including an insulation film on a semiconductor substrate;    forming a resist mask by patterning a resist applied on said multilayer film;    etching said multilayer film using said resist mask;    removing said resist mask after completing said etching; and    processing said semiconductor substrate to create a trench utilizing said multilayer film having removed said resist as mask.    
     
     
         2 . A method for manufacturing a semiconductor device comprising forming a multilayer film including an insulation film on a semiconductor substrate, subsequently patterning a resist to create a resist mask, subsequently etching said multilayer film, subsequently removing said resist mask, and subsequently processing said semiconductor substrate to create a trench utilizing as mask said multilayer film having removed of said resist mask.  
     
     
         3 . A method for manufacturing a semiconductor device comprising the steps of: 
 forming a mask layer having openings corresponding to element isolation regions on a semiconductor substrate;    etching said semiconductor substrate utilizing said mask layer as mask to form upper end portions of a trench in tapered shape; and    etching said semiconductor substrate utilizing said mask layer as mask to form the main trench portion.