Etching method

Abstract

A method for selectively etching a first region of silicon oxide with respect to a second region of silicon nitride, includes: preparing a target object including the first region and the second region in a processing chamber of a plasma processing apparatus; and generating a plasma of a processing gas containing a fluorocarbon gas and a rare gas in the processing chamber. In the generating the plasma of the processing gas, a self-bias potential of a lower electrode on which the target object is mounted is greater than or equal to 4V and smaller than or equal to 350V and a flow rate of the rare gas in the processing gas is 250 to 5000 times of a flow rate of the fluorocarbon gas in the processing gas.

What is claimed is: 
     
         1 . A method comprising:
 (a) providing a target object including a first region containing silicon oxide and a second region containing silicon nitride in a processing chamber of a plasma processing apparatus; and   (b) generating a plasma from a processing gas containing a fluorocarbon gas and a rare gas in the processing chamber,   wherein in (b), a self-bias potential of a lower electrode is greater than or equal to 4V and smaller than or equal to 350V and a flow rate of the rare gas is 250 to 5000 times a flow rate of the fluorocarbon gas in the processing gas.   
     
     
         2 . The method of  claim 1 , wherein in (b), a first gas including a fluorocarbon gas and a rare gas is supplied from a first gas source into the processing chamber and a second gas including only a rare gas or including a fluorocarbon gas and a rare gas at a volume ratio different from a volume ratio of the first gas is supplied from a second gas source into the processing chamber. 
     
     
         3 . The method of  claim 1 , wherein in (b), a gaseous mixture of a fluorocarbon gas and a rare gas is supplied from a single gas source into the processing chamber. 
     
     
         4 . The method of  claim 1 , wherein the rare gas is argon gas. 
     
     
         5 . The method of  claim 1 , wherein the processing gas further includes oxygen gas. 
     
     
         6 . The method of  claim 1 , wherein the second region includes a recess and the first region fills the recess and covers the second region,
 the method further comprising:   executing a sequence one or more times to etch the first region in a period including a time when the second region is exposed,   wherein the sequence includes:
 generating a plasma of a processing gas including a fluorocarbon gas in the processing chamber and forming a deposit containing fluorocarbon on the first region and the second region; and 
 generating a plasma of an inert gas in the processing chamber. 
   
     
     
         7 . The method of  claim 6 , wherein the sequence further includes:
 generating a plasma of a processing gas including an oxygen-containing gas and an inert gas.   
     
     
         8 . The method of  claim 1 , wherein the target object includes
 a substrate;   a protruding region formed on the substrate;   the second region covers the protruding region and includes a recess;   the first region fills the recess and covers the second region;   an organic film formed on the first region;   an anti-reflection film formed on the organic film; and   a resist mask formed on the anti-reflection film.   
     
     
         9 . The method of  claim 8 , the method further comprising:
 (c) etching the anti-reflection film through an opening of the resist mask by generating a plasma from a second processing gas in the processing chamber.   
     
     
         10 . The method of  claim 9 , wherein the second processing gas contains a fluorocarbon gas. 
     
     
         11 . The method of  claim 9 , the method further comprising:
 (d) etching the organic film through an opening of the anti-reflection film by generating a plasma from a third processing gas in the processing chamber.   
     
     
         12 . The method of  claim 11 , wherein the third processing gas includes hydrogen gas and nitrogen gas, or oxygen gas. 
     
     
         13 . The method of  claim 11 , further including, after (b), etching the first region through an opening of the organic film which is formed by (d). 
     
     
         14 . A processing apparatus, comprising:
 a processing chamber having a gas inlet and a gas outlet;   a plasma generator; and   a controller configured to cause:   (a) providing a target object including a first region containing silicon oxide and a second region containing silicon nitride; and   (b) generating a plasma from a processing gas containing a fluorocarbon gas and a rare gas,   wherein in (b), a self-bias potential of a lower electrode is greater than or equal to 4V and smaller than or equal to 350V and a flow rate of the rare gas is 250 to 5000 times of a flow rate of the fluorocarbon gas in the processing gas.