Plasma processor and plasma processing method

Abstract

An RF power (Bottom RF) from a radio-frequency power source 12 is turned off (t 5 ) and the supply of a He gas 14 to a back face of a wafer W is stopped (t 5 ) when an end point detector 17 (EPD) detects an end point (t 5 ), and a high-voltage DC power source 13 (HV) is turned off (t 6 ) under the condition in which an RF power (Top RF) from a radio-frequency power source 11 is controlled to fall within a range in which etching does not progress and plasma discharge can be maintained (t 5 ). This process enables the inhibition of the adhesion of particles while an etching amount is accurately controlled.

What is claimed is:  
     
         1 . A plasma processing apparatus comprising: 
 a step of fixing a wafer via an electrostatic chuck;    a step of applying a first radio-frequency power having a first frequency and a second radio-frequency power having a second frequency lower than the first frequency to thereby plasma-processing the wafer;    a step of maintaining plasma discharge within a range in which the plasma processing does not progress after the plasma processing is finished;    a step of stopping supply of a coolant gas supplied to a back face of the wafer via the electrostatic chuck;    a step of stopping application of a direct-current voltage to the electrostatic chuck; and    a step of stopping the plasma discharge after stopping the application of the direct-current voltage.    
     
     
         2 . A plasma processing apparatus as set forth in  claim 1 , 
 wherein, in the step of maintaining the plasma discharge, when the plasma processing is finished, the application of the second radio-frequency power is stopped and the first radio-frequency power is controlled so as to maintain the plasma discharge within the range in which the plasma processing does not progress.    
     
     
         3 . A plasma processing apparatus as set forth in  claim 1 , 
 wherein, in the step of maintaining the plasma discharge, when the plasma processing is finished, the application of the first radio-frequency power is stopped and the second radio-frequency power is controlled so as to maintain the plasma discharge within the range in which the plasma processing does not progress.    
     
     
         4 . A plasma processing apparatus as set forth in  claim 1 , 
 wherein, in the step of maintaining the plasma discharge, when the plasma processing is finished, the first radio-frequency power and the second radio-frequency power are controlled so as to maintain the plasma discharge within the range in which the plasma processing does not progress, and    wherein, in the step of stopping the plasma discharge, the application of the second radio-frequency power is stopped after the application of the first radio-frequency power is stopped.    
     
     
         5 . A plasma processing apparatus as set forth in  claim 1 , 
 wherein, in the step of maintaining the plasma discharge, when the plasma processing is finished, the second radio-frequency power is maintained as it is and the first radio-frequency power is controlled so as to maintain the plasma discharge within the range in which the plasma processing does not progress, and    wherein, in the step of stopping the plasma discharge, the application of the second radio-frequency power is stopped after the application of the first radio-frequency power is stopped.    
     
     
         6 . A plasma processing apparatus as set forth in any one of  claim 1  to  claim 5 , 
 wherein, the first radio-frequency power is applied to a top electrode and the second radio-frequency power is applied to a bottom electrode.  
 
     
     
         7 . A plasma processing apparatus as set forth in any one of  claim 1  to  claim 5 , 
 wherein the first radio-frequency power and the second radio-frequency power are applied to a bottom electrode.  
 
     
     
         8 . A plasma processing method, comprising: 
 applying a first radio-frequency power having a first frequency and a second radio-frequency power having a second frequency lower than the first frequency to thereby perform plasma processing,    wherein the first radio-frequency power is applied after the second radio-frequency power is applied.    
     
     
         9 . A plasma processing method as set forth in  claim 8 , further comprising: 
 stopping the application of the second radio-frequency power after the application of the first radio-frequency power is stopped.    
     
     
         10 . A plasma processing method as set forth in  claim 8  or  claim 9 , 
 wherein the first radio-frequency power is applied to a top electrode and the second radio-frequency power is applied to a bottom electrode.  
 
     
     
         11 . A plasma processing method as set forth in  claim 8  or  claim 9 , 
 wherein the first radio-frequency power and the second radio-frequency power are applied to a bottom electrode.  
 
     
     
         12 . A plasma processing apparatus comprising: 
 an electrostatic chuck to fix a wafer on a susceptor;    a direct current voltage source to apply a direct current voltage to said electrostatic chuck;    a plasma generating unit to generate plasma in a chamber;    a plasma discharge control unit to maintain plasma discharge within a range in which the plasma processing does not progress, after the plasma processing is finished; and    a direct current voltage stopping unit to stop the application of the direct current voltage to the electrostatic chuck at a certain point in time during which the plasma discharge is maintained.    
     
     
         13 . A plasma processing apparatus as set forth in  claim 12 , 
 wherein said plasma generating unit includes: a top electrode; a bottom electrode; a top power applying unit to apply a radio-frequency power to the top electrode; and a bottom power applying unit to apply a radio-frequency power to the bottom electrode,    wherein said plasma discharge control unit maintains the plasma discharge within the range in which the plasma processing does not progress, and controls the application of the radio-frequency power to the bottom electrode to be stopped after controlling the application of the radio-frequency power to the top electrode to be stopped.    
     
     
         14 . A plasma processing apparatus as set forth in  claim 12 , 
 wherein said plasma generating unit includes: a top electrode; a bottom electrode; a first power applying unit to apply a first radio-frequency power having a first frequency to the top electrode; and a second power applying unit to apply a second radio-frequency power having a second frequency lower than the first frequency to the top electrode, and    wherein said plasma discharge control unit maintains the plasma discharge within the range in which the plasma processing does not progress, and controls the application of the second radio-frequency power to be stopped after controlling the application of the first radio-frequency power to be stopped.    
     
     
         15 . A plasma processing apparatus as set forth in  claim 12 , further comprising: 
 a coolant gas supply unit to supply a coolant gas to a back face of the wafer via said electrostatic chuck; and    a coolant gas stopping unit to stop the supply of the coolant gas before the application of the direct current voltage to said electrostatic chuck is stopped, after the plasma processing is finished.