Plasma etching method, plasma etching apparatus and computer-readable storage medium

Abstract

Provided are a plasma etching method, a plasma etching apparatus and a computer-readable storage medium capable of plasma-etching a silicon-containing antireflection coating film (Si-ARC) with a high etching rate and a high selectivity while suppressing damage (roughness) of an ArF photoresist. In the plasma etching method, a Si-containing antireflection film 102 located under an ArF photoresist 103 formed on a substrate is etched by plasma of a processing gas while using the ArF photoresist as a mask. A gaseous mixture containing a CF 3 I gas, an O 2 gas, and a CF-based gas and/or a CHF-based gas is used as the processing gas, and a DC voltage is applied to the upper electrode.

1 . A plasma etching method for etching a Si-containing antireflection film under an ArF photoresist formed on a substrate by using plasma of a processing gas while using the ArF photoresist as a mask, the plasma etching method being performed by a plasma etching apparatus including a lower electrode installed in a processing chamber and configured to mount the substrate; an upper electrode installed in the processing chamber so as to face the lower electrode; a processing gas supply unit configured to supply the processing gas into the processing chamber; and a high frequency power supply configured to apply a high frequency power between the lower electrode and the upper electrode, the method comprising:
 applying a DC voltage to the upper electrode while using a gaseous mixture containing a CF 3 I gas, an oxygen gas, and a CF-based gas and/or a CHF-based gas as the processing gas.   
     
     
         2 . The plasma etching method of  claim 1 , wherein the DC voltage applied to the upper electrode is in a range of about −1000 V to about −300 V. 
     
     
         3 . The plasma etching method of  claim 1 , wherein the processing gas is a gaseous mixture containing a CF 4  gas, a CF 3 I gas and an oxygen gas, and
 a ratio of a CF 3 I gas flow rate to a sum of a CF 4  gas flow rate and the CF 3 I gas flow rate (flow rate of the CF 3 I gas/(flow rate of the CF 4  gas+flow rate of the CF 3 I gas) is in a range of about 0.1 to about 0.3.   
     
     
         4 . The plasma etching method of  claim 2 , wherein the processing gas is a gaseous mixture containing a CF 4  gas, a CF 3 I gas and an oxygen gas, and
 a ratio of a CF 3 I gas flow rate to a sum of a CF 4  gas flow rate and the CF 3 I gas flow rate (flow rate of the CF 3 I gas/(flow rate of the CF 4  gas+flow rate of the CF 3 I gas) is in a range of about 0.1 to about 0.3.   
     
     
         5 . The plasma etching method of  claim 1 , wherein a high frequency bias power of about 100 W to about 300 W is applied to the lower electrode. 
     
     
         6 . The plasma etching method of  claim 1 , wherein a treatment process for performing a treatment of the ArF photoresist is performed prior to etching the Si-containing antireflection film. 
     
     
         7 . The plasma etching method of  claim 6 , wherein the treatment process is a plasma process in which a H 2  gas, a mixture of a H 2  gas and a N 2  gas or a mixture of a H 2  gas and an Ar gas is used as a processing gas,
 the processing gas is excited into plasma, and   the plasma acts on the ArF photoresist.   
     
     
         8 . A plasma etching apparatus comprising:
 a lower electrode installed in a processing chamber and configured to mount a substrate;   an upper electrode installed in the processing chamber so as to face the lower electrode;   a processing gas supply unit configured to supply a processing gas into the processing chamber;   a high frequency power supply configured to apply a high frequency power between the lower electrode and the upper electrode; and   a controller configured to control a gaseous mixture containing a CF 3 I gas, an oxygen gas, and a CF-based gas and/or a CHF-based gas to be supplied from the processing gas supply unit as the processing gas, and a DC voltage to be applied to the upper electrode from a DC power supply when a Si-containing antireflection film under an ArF photoresist formed on the substrate is etched by plasma of the processing gas while using the ArF photoresist as a mask.   
     
     
         9 . A computer-readable storage medium that stores therein a computer-executable control program, wherein, when executed, the control program controls a plasma etching apparatus to carry out a plasma etching method as claimed in  claim 1 .