Method of etching porous dielectric

Abstract

The present invention relates to methods of etching a porous dielectric. The method includes etching the film in a plasma etch chamber with CF 4 , H 2 and a noble gas, wherein the CF 4 to H 2 gas flow ratio is between 1.33:1 and 2.7:1 and the noble gas is greater than about 42% of the total gas flow to the plasma chamber.

1 . A method of etching a porous carbon-doped silicon dioxide type dielectric film including plasma etching the film in a plasma etch chamber with CF 4 , H 2  and a noble gas, wherein the CF 4  to H 2  gas flow ratio is between 1.33:1 and 2.7:1 and the noble gas is greater than about 42% of the total gas flow to the plasma chamber.  
   
   
       2 . A method as claimed in  claim 1  wherein the CF 4 :H 2  ratio is about 2:1.  
   
   
       3 . A method as claimed in  claim 1  wherein the noble gas is argon.  
   
   
       4 . A method as claimed in  claim 3  wherein argon is present at up to about 77% of the total gas flow to the plasma etch chamber.  
   
   
       5 . A method as claimed in  claim 1  wherein film temperature is in the range of 100° C. and 170° C.  
   
   
       6 . A method as claimed in  claim 1  wherein the chamber pressure is in the range 90 mT to 300 mT.  
   
   
       7 . A method as claimed in  claim 1  wherein the power supplied to the plasma is between 700 and 1000 Watts.  
   
   
       8 . A method as claimed in  claim 1  wherein the etch is terminated within the film.  
   
   
       9 . A method as claimed in  claim 8  wherein the film is within an interconnect structure.  
   
   
       10 . A method as claimed in  claim 1  wherein the plasma etch is forming an interconnect structure or other relevant structure in the film.  
   
   
       11 . A device incorporating a film as etched by the method of  claim 1.