Plasma processing apparatus and control method thereof

Abstract

In a plasma processing apparatus for processing an object to be processed by generating plasma in a processing chamber: a first electrode is arranged in the processing chamber and a second electrode is arranged to face the first electrode in the processing chamber; a first and a second power systems include a first and a second power supplies for supplying a first and a second powers to the first and the second electrodes, respectively; and a control unit controls both or either one of the first and the second power systems so as to apply a preprocessing voltage to the second electrode for a time period before plasma processing is performed on the object.

What is claimed is:  
     
         1 . A plasma processing apparatus for processing an object to be processed by generating a plasma in a processing chamber, comprising: 
 a first electrode installed in the processing chamber;    a second electrode arranged to face the first electrode in the processing chamber;    a first power system including a first power supply for supplying a first power to the first electrode;    a second power system including a second power supply for supplying a second power to the second electrode; and    a control unit for controlling the first and the second power systems,    wherein the control unit controls both or either one of the first and the second power systems so as to apply a preprocessing voltage for a time period before plasma processing is performed on the object in the processing chamber, the preprocessing voltage being higher than a voltage applied to the second electrode during the plasma processing of the object.    
     
     
         2 . The plasma processing apparatus of  claim 1 , wherein the first power system includes a first matching unit for matching impedances of a first power supply side and a first electrode side and the second power system includes a second matching unit for matching impedances of a second power supply side and a second electrode side, 
 wherein the control unit adjusts reactances of both or either one of the first and the second matching units to generate the preprocessing voltage applied to the second electrode.    
     
     
         3 . The plasma processing apparatus of  claim 1 , wherein the control unit adjusts power levels and output timings of the first and the second powers respectively outputted from the first and the second power supplies to generate the preprocessing voltage applied to the second electrode.  
     
     
         4 . A control method of a plasma processing apparatus, which includes a first electrode arranged in a processing chamber, a second electrode arranged to face the first electrode in the processing chamber, a first power supply for supplying a first power to the first electrode and a second power supply for supplying a second power to the second electrode, 
 wherein a preprocessing voltage is applied to the second electrode for a time period before plasma processing is performed on an object to be processed in the processing chamber, the preprocessing voltage being higher than a voltage applied to the second electrode during the plasma processing of the object.    
     
     
         5 . The control method of  claim 4 , wherein the preprocessing voltage applied to the second electrode is generated by adjusting reactances of both or either one of a first matching unit and a second matching unit, the first matching unit matching impedances of a first power supply side and a first electrode side and the second matching unit matching impedances of a second power supply side and a second electrode side.  
     
     
         6 . The control method of  claim 4 , wherein the preprocessing voltage applied to the second electrode is generated by adjusting power levels and output timings of the first and the second powers respectively outputted from the first and the second power supplies.  
     
     
         7 . A control method of a plasma processing apparatus, which includes a first electrode arranged in a processing chamber, a second electrode arranged to face the first electrode in the processing chamber, a first power supply for supplying a first power to the first electrode and a second power supply for supplying a second power to the second electrode, the control method comprising the steps of: 
 performing a plasma processing process on an object to be processed under a first plasma forming condition by generating a plasma in the processing chamber by applying high frequency powers to the electrodes; and    performing, prior to the above step, a plasma processing preparation process for generating a plasma for a time period under a second plasma forming condition, which is different from the first plasma forming condition.    
     
     
         8 . The control method of  claim 7 , wherein a preprocessing voltage applied to the second electrode during the plasma processing preparation process is higher than a voltage applied to the second electrode during the plasma processing process.  
     
     
         9 . The control method of  claim 8 , wherein the preprocessing voltage applied to the second electrode is generated by adjusting power levels and output timings of the first and the second powers respectively outputted from the first and the second power supplies.