Etching apparatus

Abstract

An etching method through which the resist-relative selection ratio is improved and the etching shape is also improved, is provided. In an etching method for etching an SiO 2 layer formed at a wafer W placed inside an airtight processing chamber 104 by inducing a processing gas into the processing chamber 104 , the processing gas contains at least C 5 F 8 and CH 2 F 2 and the flow rate ratio of C 5 F 8 and CH 2 F 2 in the processing gas is essentially within the range of 1/4≦(C 5 F 8 flow rate/CH 2 F 2 flow rate)≦1/2. Since the processing gas contains C 5 F 8 and CH 2 F 2 , the resist-relative selection ratio can be improved. In addition, by setting the flow rate ratio of C 5 F 8 and CH 2 F 2 essentially equal to or larger than 1/4, deformation of grooves due to longitudinal streaking or waviness can be eliminated, whereas by setting the flow rate ratio of C 5 F 8 and CH 2 F 2 essentially equal to or smaller than 1/2, deformation of grooves attributable to bowing can be eliminated.

What is claimed is;  
     
         1 . An etching method for etching an SiO 2  layer formed at a workpiece placed inside an airtight processing chamber by inducing a processing gas into said processing chamber, wherein: 
 said processing gas contains at least C 5 F 8  and CH 2 F 2  and the flow rate ratio of C 5 F 8  and CH 2 F 2  in said processing gas is essentially within a range of 1/4≦(C 5 F 8  flow rate/CH 2 F 2  flow rate)≦1/2.    
     
     
         2 . An etching method according to  claim 1 , wherein: 
 said processing gas further contains O 2 .    
     
     
         3 . An etching method according to  claim 2 , wherein: 
 the flow rates of C 5 F 8  CH 2 F 2  and O 2  in said processing gas essentially achieve a relationship expressed as: ((C 5 F 8  flow rate+CH 2 F 2  flow rate)/O 2  flow rate)=1.5/1.    
     
     
         4 . An etching method according to  claim 2 , wherein: 
 the flow rates of C 5 F 8  CH 2 F 2  and O 2  in said processing gas essentially achieve a relationship expressed as:0.5/1≦((C 5 F 8  flow rate+CH 2 F 2  flow rate)/O 2  flow rate)≦3/1.    
     
     
         5 . An etching method according to  claim 2 , wherein: 
 said processing gas further contains Ar.    
     
     
         6 . An etching method according to  claim 1 , wherein: 
 etching is performed under a condition expressed as (SiO 2  layer etching rate/photoresist etching rate)≧10.