Etching method

Abstract

Disclosed is a method for etching an etching target layer which contains silicon and is provided with a metal-containing mask thereon. The method includes: generating plasma of a first processing gas containing a fluorocarbon gas in a processing container that accommodates the etching target layer and the mask to form a fluorocarbon-containing deposit on the mask and the etching target layer; and generating plasma of a second processing gas containing an inert gas in the processing container to etch the etching target layer by radicals of the fluorocarbon contained in the deposit. A plurality of sequences, each including the generating the plasma of the first processing gas and the generating the plasma of the second processing gas, are performed.

What is claimed is: 
     
         1 . A plasma processing apparatus comprising:
 a processing container configured to process a substrate having an etching target layer formed with a mask thereon, and having one or more gas inlets and one or more gas outlets;   a substrate support configured to hold the substrate;   a focus ring configured to surround an edge of the substrate;   a radio frequency power source configured to generate plasma from a first gas or a second gas supplied through the one or more gas inlets in the processing container;   a controller configured to cause:
 forming a deposit on the mask, the etching target layer, and the focus ring by a first plasma generated from the first gas; and 
 etching the etching target layer using radicals generated by exposing the deposit to a second plasma generated from the second gas different from the first plasma, 
 wherein, in the etching the etching target layer, the generated radicals react with the etching target layer to form reaction products, and the reaction products are exhausted through the one or more gas outlets, and 
 wherein in the etching the etching target layer, the second gas is supplied in the processing container without supplying the first gas. 
   
     
     
         2 . The plasma processing apparatus according to  claim 1 , wherein the exposing the deposit to the second plasma further comprises removing material from the deposit formed by the first plasma, to generate the radicals from the deposit. 
     
     
         3 . A plasma processing apparatus comprising:
 a processing container configured to process a substrate having an etching target layer formed with a mask thereon, and having one or more gas inlets and one or more gas outlets;   a substrate support configured to hold the substrate;   a focus ring configured to surround an edge of the substrate;   a radio frequency power source configured to generate plasma from a first gas or a second gas supplied through the one or more gas inlets in the processing container;   a controller configured to cause:
 a first step of forming a deposit on the mask, the etching target layer, and the focus ring by a first plasma generated from the first gas, wherein in the first step deposition is dominant over etching with respect to the etching target layer exposed to the first plasma; and 
 a second step of etching the etching target layer using radicals generated by exposing the deposit to a second plasma generated from the second gas different from the first plasma, 
 wherein, in the etching the etching target layer, the generated radicals react with the etching target layer to form reaction products, and the reaction products are exhausted through the gas outlet. 
   
     
     
         4 . The plasma processing apparatus according to  claim 3 , wherein the exposing the deposit to the second plasma further comprises removing material from the deposit formed by the first plasma, to generate the radicals from the deposit. 
     
     
         5 . The plasma processing apparatus according to  claim 3 , wherein a radio frequency power supplied from the radio frequency power source to the first step and the second step is different from each other. 
     
     
         6 . The plasma processing apparatus according to  claim 3 , further comprising a bias power source configured to supply a bias power to the substrate support,
 wherein an amount of the bias power supplied in the first step is smaller than the amount of the bias power supplied in the second step.   
     
     
         7 . The plasma processing apparatus according to  claim 3 , wherein the etching target layer is a silicon-containing layer. 
     
     
         8 . The plasma processing apparatus according to  claim 7 , wherein the silicon-containing layer includes a plurality of films. 
     
     
         9 . The plasma processing apparatus according to  claim 3 , wherein the mask is a metal-containing mask. 
     
     
         10 . The plasma processing apparatus according to  claim 3 , wherein the mask includes a first region provided with a relatively large opening and a second region provided with a relatively small opening. 
     
     
         11 . The plasma processing apparatus according to  claim 3 , wherein the focus ring is made of a material different from the mask. 
     
     
         12 . The plasma processing apparatus according to  claim 3 , wherein the plasma processing apparatus is a capacitively-coupled plasma etching apparatus. 
     
     
         13 . The plasma processing apparatus according to  claim 12 , further comprising:
 an upper electrode configured to face the substrate support; and   a voltage source configured to draw plus ions that exist in a processing space of the processing container into the upper electrode.   
     
     
         14 . The plasma processing apparatus according to  claim 3 , wherein a single inert gas is supplied in the first step, and a plurality of inert gases is supplied in the second step. 
     
     
         15 . The plasma processing apparatus according to  claim 3 , wherein the first gas includes a fluorocarbon gas, and the second gas includes an inert gas. 
     
     
         16 . he plasma processing apparatus according to  claim 15 , wherein in the first step, a C/F ratio of the fluorocarbon gas is 0.5 or more. 
     
     
         17 . The plasma processing apparatus according to  claim 15 , wherein the fluorocarbon gas is C 4 F 8  or C 4 F 6 . 
     
     
         18 . The plasma processing apparatus according to  claim 1 , wherein the controller is further configured to cause repeating the forming and the etching for a predetermined of time. 
     
     
         19 . The plasma processing apparatus according to  claim 3 , wherein the controller is further configured to cause repeating the forming and the etching for a predetermined of time.