Plasma processing method for working the surface of semiconductor devices

Abstract

A plasma processing method is provided of processing a sample having a silicon nitride layer with high accuracy of size in anisotropy and excellent selectivity to a silicon oxide layer as underlayer. A mixed atmosphere of chlorine gas containing no fluorine with aluminum is converted into plasma in a plasma etching processing chamber and the sample having the silicon nitride layer is etched by using the plasma.

1 . A plasma processing apparatus for selectively etching a silicon nitride layer on a silicon oxide layer formed on a substrate as a sample, using plasma, said apparatus comprising: 
 a vacuum vessel;    a sample stage constituting an electrode, for mounting said sample;    a power supply for applying a radio-frequency bias voltage to said sample stage; and    means for supplying a halogen-containing gas into said vacuum vessel,    wherein an aluminum-containing material is disposed in a part or the entire surface exposed to said plasma in said vacuum vessel.    
   
   
       2 . A plasma processing apparatus according to  claim 1 , 
 wherein said aluminum-containing material is grounded.    
   
   
       3 . A plasma processing apparatus according to  claim 1 , 
 wherein said aluminum-containing material is disposed around an outer periphery of said sample stage in a ring-like form.    
   
   
       4 . A plasma processing apparatus according to  claim 3 , 
 wherein a ring made of silicon as a main component is disposed on an upper portion of said aluminum-containing material.    
   
   
       5 . A plasma processing apparatus according to  claim 3 , 
 wherein said halogen-containing gas is chlorine gas or hydrogen bromide gas.    
   
   
       6 . A plasma processing apparatus for selectively etching a silicon nitride layer on a silicon oxide layer formed on a substrate as a sample, using plasma, said apparatus comprising: 
 a vacuum vessel;    a sample stage constituting an electrode, for mounting said sample;    a power supply for applying a radio-frequency bias voltage to said sample stage;    means for supplying a halogen-containing gas into said vacuum vessel; and    means for supplying an aluminum-containing gas into said vacuum vessel.    
   
   
       7 . A plasma processing apparatus for selectively etching a silicon nitride layer on a silicon oxide layer formed on a substrate as a sample, using plasma, said apparatus comprising: 
 a vacuum vessel;    a sample stage constituting an electrode, for mounting said sample;    a power supply for applying a radio-frequency bias voltage to said sample stage;    means for supplying a halogen-containing gas into said vacuum vessel; and    means for supplying a silicon-containing gas into said vacuum vessel.