Plasma processing apparatus and plasma processing method

Abstract

In a plasma processing apparatus which includes a chamber ( 1 ) equipped with a wafer stage ( 3 ) for mounting thereon a substrate ( 2 ) to be processed, and which processes the substrate ( 2 ) by exposure to a plasma ( 4 ), a photon detection sensor ( 5 ) for measuring an ultraviolet-light-induced current is placed on a circumferential portion of a substrate mounting surface ( 3 a ) of the wafer stage ( 3 ) so that the occurrence of an abnormal discharge can be detected, in real time, from a change in the output of the photon detection sensor ( 5 ).

1 . A plasma processing apparatus comprising: 
 a chamber equipped with a wafer stage for mounting thereon a substrate to be processed;    a means for providing plasma on said substrate mounted on said wafer stage; and    a photon detection sensor for measuring an ultraviolet-light-induced current placed on a circumferential portion of a substrate mounting surface of said wafer stage.    
   
   
       2 . A plasma processing apparatus as claimed in  claim 1 , wherein said photon detection sensor comprises a semiconductor substrate, an insulating film formed over said semiconductor substrate, an electrode layer embedded in said insulating film, a means for applying a bias voltage to said electrode layer, and a means for detecting a current flowing in said electrode layer.  
   
   
       3 . A plasma processing apparatus as claimed in  claim 2 , wherein said photon detection sensor further comprises a second electrode formed on said insulating film.  
   
   
       4 . A plasma processing apparatus as claimed in  claim 1 , wherein a plurality of said photon detection sensors are arranged around the circumferential portion of said substrate mounting surface of said wafer stage.  
   
   
       5 . A plasma processing method for processing a substrate, comprising: 
 providing a plurality of photon detection sensors, each for measuring an ultraviolet-light-induced current, on a wafer stage provided within a plasma chamber;    providing said substrate to be processed on said wafer stage,    performing plasma processing in said plasma chamber in which said photon detection sensors and said substrate to be processed are placed, and    monitoring an output current from each of said photon detection sensors while said plasma processing is being performed.    
   
   
       6 . A plasma processing method as claimed in  claim 5 , wherein when a spike-like current drop different from a steady-state current is observed during the monitoring of said photon detection sensors, said spike-like current drop is recognized as indicating the occurrence of an abnormal discharge.  
   
   
       7 . A plasma processing apparatus as claimed in  claim 2 , wherein a plurality of said photon detection sensors are arranged around the circumferential portion of said substrate mounting surface of said wafer stage.  
   
   
       8 . A plasma processing apparatus as claimed in  claim 3 , wherein a plurality of said photon detection sensors are arranged around the circumferential portion of said substrate mounting surface of said wafer stage.