Dry etching method of high-k film

Abstract

An object of the invention is to provide a dry etching method of a metal oxide High-k film having etching characteristics which achieve a small etching rate difference and a small profile difference between open area and dense area while keeping a high selectivity to a polysilicon underlying film. In the method of dry-etching a High-k film by using a plasma, a small amount of fluorocarbon gas having a high carbon ratio is added to a BCl 3 gas mixed with a rare gas.

1 . A dry etching method of a High-k film, comprising the step of adding a fluorocarbon-based gas to a gas mixture of a rare gas and a BCl 3  gas in a plasma-etching of a metal oxide film made by bonding a metal and oxide. 
   
   
       2 . The dry etching method of a High-k film according to  claim 1 , wherein a metal constituting the metal oxide film includes at least one metal selected from the group consisting of Al, Hf, Zr, Ta and Si. 
   
   
       3 . The dry etching method of a High-k film according to  claim 1 , wherein the metal oxide film is constituted by a stacked film made of at least one selected from the group consisting of Al 2 O 3 , HfO 2 , ZrO 2 , AlHfO and Ta 2 O 5 . 
   
   
       4 . The dry etching method of a High-k film according to  claim 1 , wherein the fluorocarbon-based gas is a gas mixture containing at least one selected from the group consisting of C 2 F 4 , C 3 F 8 , C 4 F 8 , C 4 F 6  and C 5 F 8 . 
   
   
       5 . The dry etching method of a High-k film according to  claim 1 , wherein the rare gas is a gas mixture containing at least one selected from the group consisting of He, Ne, Ar, Kr and Xe. 
   
   
       6 . The dry etching method of a High-k film according to  claim 1 , wherein, in the gas mixture, a flow-rate ratio of the fluorocarbon-based gas to the BCl 3  gas ranges from 2% to 5%.