Dry etching method

Abstract

In a dry etching method for isotropically etching each of SiGe layers selectively relative to each of Si layers in a laminated film composed of the Si layers and SiGe layers alternately and repeatedly laminated, the each of the SiGe layers is plasma-etched with pulse-modulated plasma using NF 3 gas.

1 . A dry etching method for isotropically etching each of SiGe layers selectively relative to each of Si layers in a laminated film composed of the Si layers and SiGe layers alternately and repeatedly laminated, the method comprising the step of plasma-etching each of the SiGe layers with pulse-modulated plasma using NF 3  gas. 
     
     
         2 . The dry etching method according to  claim 1  further comprising the step of mixing the NF 3  gas with any one of O 2  gas, N 2  gas, CO 2  gas, and CO gas. 
     
     
         3 . A dry etching method for isotropically etching each of SiGe layers selectively relative to each of Si layers in a laminated film composed of the Si layers and SiGe layers alternately and repeatedly laminated, the method comprising the step of plasma-etching each of the SiGe layers with pulse-modulated plasma using fluorocarbon gas. 
     
     
         4 . The dry etching method according to  claim 3  wherein the fluorocarbon gas is any one of CF 4  gas, CHF 3  gas, CH 2 F 2  gas, and CH 3 F gas. 
     
     
         5 . The dry etching method according to  claim 4  further comprising the step of mixing the fluorocarbon gas with any one of O 2  gas, N 2  gas, CO 2  gas, and CO gas. 
     
     
         6 . The dry etching method according to  claim 1  wherein a duty ratio of pulse-modulation is 50% or less. 
     
     
         7 . A dry etching method for isotropically etching each of SiGe layers selectively relative to each of Si layers in a laminated film composed of the Si layers and SiGe layers alternately and repeatedly laminated, the method comprising the step of forming a groove having a predetermined depth on the laminated film with continuous plasma and then plasma-etching each of SiGe layers with pulse-modulated plasma using NF3 gas or fluorocarbon gas.