Etching method

Abstract

A method for selectively etching a first region made of silicon oxide with respect to a second region made of silicon nitride or another material different from that of the first region. The method includes a first step for generating, in a processing container housing a workpiece to be treated, a plasma of a treatment gas including a fluorocarbon gas, an oxygen-containing gas, and an inert gas, and forming a deposit including fluorocarbon on the object to be treated; and a second step for etching the first region with radicals of the fluorocarbon included in the deposit. The first step and the second step are executed repeatedly.

1 - 2 . (canceled) 
     
     
         3 . An etching method comprising:
 (a) providing a workpiece including a first region and a second region, in which the first region is made of silicon oxide and the second region is made of silicon nitride, in which the second region defines a recess and the first region fills and covers the second region, and in which a mask is located above the first region and the mask has an opening with an opening width larger than an opening width of the recess; and   (b) selectively etching the first region with respect to the second region with a plurality of steps comprising:
 (i) a first step of generating plasma from a processing gas containing a fluorocarbon gas, an oxygen-containing gas, and an inert gas in a processing container accommodating the workpiece to form a deposit containing fluorocarbon on the workpiece; 
 (ii) a second step of etching the first region with fluorocarbon radicals contained in the deposit; and 
 (iii) wherein the first step and the second step are repeatedly executed. 
   
     
     
         4 . The method of  claim 3 , wherein the etching of the second step is performed with a substantially oxygen-free processing gas. 
     
     
         5 . A method comprising:
 (a) providing a workpiece including a first region and a second region, in which the first region is made of a silicon-containing material and the second region is made of a material other than the silicon-containing material of the first region, in which the second region defines a recess, the first region fills the recess and covers the second region, and in which a mask is above the recess and the mask has an opening with an opening width larger than an opening width of the recess; and   (b) selectively etching the first region with respect to the second region with a first sequence comprising:
 (i) a first step of generating plasma from a processing gas containing a fluorocarbon gas, an oxygen-containing gas, and an inert gas in a processing chamber accommodating the workpiece to form a deposit containing fluorocarbon on the workpiece; 
 (ii) a second step of etching the first region with fluorocarbon radicals contained in the deposit; and 
   wherein the first sequence is repeatedly executed.   
     
     
         6 . The method of  claim 5 , wherein the first step includes:
 forming a fluorocarbon deposit by fluorocarbon plasma; and   reducing the fluorocarbon deposit by oxygen plasma.   
     
     
         7 . The method of  claim 6 , wherein the oxygen plasma reduces the fluorocarbon deposit at 1 nm/sec or less. 
     
     
         8 . The method of  claim 6 , wherein performance of the second step at least partially overlaps with performance of the first step. 
     
     
         9 . The method of  claim 5 , further including executing a second sequence including the first step and the second step having different processing times from each other. 
     
     
         10 . The method of  claim 9 , wherein a processing time of the first step in the first sequence is shorter than a processing time of the first step of the second sequence. 
     
     
         11 . The method of  claim 5 , wherein the first sequence is executed at a time when the second region is exposed. 
     
     
         12 . The method of  claim 5 , wherein etching is performed using oxygen active species before the first step such that an upper shoulder of the mask defining an upper end portion of the opening becomes a taper-shape. 
     
     
         13 . The method of  claim 9 , wherein high frequency bias power in the first step of the first sequence is higher than high frequency bias power in the first step of the second sequence. 
     
     
         14 . The method of  claim 9 , further including executing a third sequence including the first step and the second step having different power conditions from each other, and
 high frequency bias power in the second step of the third sequence is higher than high frequency bias power in the first and second sequences.   
     
     
         15 . A method according to  claim 5 , further including executing a second sequence including the first step and the second step, and wherein:
 the second sequence is executed a plurality of times; and   during each execution of the first sequence an amount by which the first region is etched is less than an amount by which the first region is etched during each execution of the second sequence.   
     
     
         16 . A method according to  claim 15 , wherein an execution time of each first sequence is set to be shorter than an execution time of each second sequence.