Etching method

Abstract

An etching method including: (a) providing a workpiece including a first region made of a first material and a second region made of a second material defining a recess, the first region filling the recess of the second region while covering the second region; (b) generating plasma of a first fluorocarbon gas to etch the first region until before exposing the second region; (c) generating plasma of a second fluorocarbon gas to form fluorocarbon deposits on the first region; (d) generating plasma of an inert gas to etch the first region by fluorocarbon radicals contained in the fluorocarbon deposits; and (e) repeating step (c) and step (d) one or more times until after exposing the second region. An etching rate of the first material of the first region is higher than that of the second material of the second region with respect to the second fluorocarbon gas.

What is claimed is: 
     
         1 . A plasma processing apparatus comprising:
 a processing container having at least one gas inlet and at least one gas outlet;   a substrate support in the processing container;   a plasma generator configured to generate a plasma in the processing container; and   a controller configured to cause:   (a) providing a substrate including a first region made of a first material and a second region made of a second material, the second region defining a recess, the first region filling the recess of the second region and covering the second region;   (b) generating a first plasma from a first fluorocarbon gas to etch the first region until before exposing the second region;   (c) generating a second plasma from a second fluorocarbon gas to form fluorocarbon deposits on the first region;   (d) generating a third plasma from a processing gas consisting essentially of an inert gas to etch the first region; and   (e) repeating (c) and (d) one or more times until after exposing the second region,   wherein during a sequence of (c) through (e), the first region is selectively etched with respect to the second region, and   wherein a material of the fluorocarbon deposits is different from a material of the first region.   
     
     
         2 . The plasma processing apparatus according to  claim 1 , wherein the first material includes silicon oxide, and the second material includes silicon nitride. 
     
     
         3 . The plasma processing apparatus according to  claim 1 , wherein the controller is further configured to cause:
 (f) generating a fourth plasma from a third fluorocarbon gas to etch the first region after (e).   
     
     
         4 . The plasma processing apparatus according to  claim 3 , wherein an etching rate in (f) is higher than an etching rate during the sequence of (c) through (e). 
     
     
         5 . The plasma processing apparatus according to  claim 3 , wherein (f) continuously etches the first region in the recess to a bottom of the recess. 
     
     
         6 . The plasma processing apparatus according to  claim 3 , further comprising a radio frequency bias power supply configured to apply a radio frequency bias power to the substrate support,
 wherein the radio frequency bias power in (f) is higher than a radio frequency bias power in (c).   
     
     
         7 . The plasma processing apparatus according to  claim 1 , wherein the first fluorocarbon gas is different from the second fluorocarbon gas in a ratio of a number of fluorine atoms to a number of carbon atoms. 
     
     
         8 . The plasma processing apparatus according to  claim 7 , wherein the ratio of the number of fluorine atoms to the number of carbon atoms is higher in the first fluorocarbon gas than in the second fluorocarbon gas. 
     
     
         9 . The plasma processing apparatus according to  claim 1 , wherein the substrate includes a mask formed on the first region providing an opening having a width wider than a width of the recess formed in the second region. 
     
     
         10 . The plasma processing apparatus according to  claim 1 , wherein the first fluorocarbon gas includes at least one of a CF 4  gas, and a C 4 F 8  gas, and the second fluorocarbon gas includes a C 4 F 6  gas. 
     
     
         11 . The plasma processing apparatus according to  claim 3 , further comprising DC power supply configured to apply a DC voltage to an upper electrode which faces the substrate support,
 wherein in (f), a negative voltage is applied to the upper electrode.   
     
     
         12 . The plasma processing apparatus according to  claim 1 , wherein, in (d), a high frequency power for generating plasma and a high frequency bias power are applied to a lower electrode that supports the substrate. 
     
     
         13 . The plasma processing apparatus according to  claim 12 , wherein the high frequency power ranges from 100 W to 500 W. 
     
     
         14 . The plasma processing apparatus according to  claim 12 , wherein the high frequency bias power ranges from 20 W to 300 W. 
     
     
         15 . The plasma processing apparatus according to  claim 1 , wherein, in (d), a flow rate of the inert gas ranges from 500 sccm to 1500 sccm. 
     
     
         16 . The plasma processing apparatus according to  claim 1 , wherein the controller is further configured to cause:
 (h) generating a fifth plasma from an oxygen-containing gas between (b) and (c).   
     
     
         17 . A plasma processing apparatus comprising:
 a processing container having at least one gas inlet and at least one gas outlet;   a substrate support in the processing container;   a plasma generator configured to generate a plasma in the processing container; and   a controller configured to cause:   (a) providing a substrate including a first region made of a first silicon-containing material and a second region made of a second silicon containing material that is different from the first silicon-containing material, the second region defining a recess, the first region filling the recess of the second region and covering the second region;   (b) generating a first plasma from a first fluorocarbon gas to etch the first region until before exposing the second region;   (c) generating a second plasma from a second fluorocarbon gas to form fluorocarbon deposits on the first region;   (d) generating a third plasma from an inert gas to etch the first region;   (e) repeating (c) and (d) one or more times until after exposing the second region; and   (f) generating a fourth plasma from a third fluorocarbon gas to etch the first region after (e).   
     
     
         18 . The plasma processing apparatus according to  claim 17 , wherein a radio frequency power in (b) and (f) is higher than a radio frequency power in (c). 
     
     
         19 . The plasma processing apparatus according to  claim 17 , further comprising a radio frequency bias power supply configured to apply a radio frequency bias power to the substrate support,
 wherein the radio frequency bias power in (b) and (f) is higher than a radio frequency bias power in (c).   
     
     
         20 . A plasma processing apparatus comprising:
 a processing container having at least one gas inlet and at least one gas outlet;   a substrate support in the processing container;   a plasma generator configured to generate a plasma in the processing container; and   a controller configured to cause:   (a) providing a substrate including a first region made of silicon oxide and a second region made of silicon nitride, the second region defining a recess, the first region filling the recess of the second region and covering the second region;   (b) generating a first plasma from a first fluorocarbon gas to etch the first region until before exposing the second region;   (c) generating a second plasma from a second fluorocarbon gas to form fluorocarbon deposits on the first region;   (d) generating a third plasma from an inert gas to etch the first region;   (e) repeating step (c) and step (d) one or more times until after exposing the second region;   (f) generating a fourth plasma from a third fluorocarbon gas to etch the first region after (e), and   wherein the first fluorocarbon gas is different from the second fluorocarbon gas