Plasma processing apparatus and impedance adjustment method

Abstract

A plasma processing apparatus, for performing a plasma processing on a substrate to be processed by generating a plasma of the processing gas in an evacuable processing chamber, includes an impedance adjusting mechanism. The impedance adjusting mechanism is provided with a resonance circuit formed to allow a radio frequency current to flow into the first electrode; a variable impedance unit installed on a power feed line to the first electrode; a detector for detecting an apparatus state to be used to search a resonance point of the resonance circuit; and a controller for searching a resonance point of the resonance circuit by detecting a signal of the apparatus state of the detector while varying a value of the variable impedance unit in a state where the plasma is formed and then adjusting the value of the variable impedance unit at the resonance point to a reference value.

1 . A plasma processing apparatus for performing a plasma processing on a substrate to be processed by generating a plasma of the processing gas in an evacuable processing chamber, the apparatus comprising: 
 a first and a second electrode disposed to face each other in the processing chamber;    a radio frequency power supply unit for supplying a radio frequency power for generating a plasma to the first electrode;    a processing gas supply unit for supplying a processing gas into the processing chamber; and    an impedance adjusting mechanism for adjusting an impedance on the side of a plasma source,    wherein the impedance adjusting mechanism includes:    a resonance circuit formed to allow a radio frequency current to flow into the first electrode;    a variable impedance unit installed on a power feed line to the first electrode;    a detector for detecting an apparatus state to-be used to search a resonance point of the resonance circuit; and    a controller for searching a resonance point of the resonance circuit by detecting a signal of the apparatus state of the detector while varying a value of the variable impedance unit in a state where the plasma is formed and then adjusting the value of the variable impedance unit at the resonance point to a reference value.    
   
   
       2 . The plasma processing apparatus of  claim 1 , wherein the variable impedance unit is a variable capacitor.  
   
   
       3 . A plasma processing apparatus for performing a plasma processing on a substrate to be processed by generating a plasma of the processing gas in an evacuable processing chamber, the apparatus comprising: 
 a first and a second electrode disposed to face each other in the processing chamber, the first electrode being divided into an inner and an outer electrode;    a radio frequency power supply unit for supplying a radio frequency power for generating a plasma to the first electrode;    a processing gas supply unit for supplying a processing gas into the processing chamber; and    an impedance adjusting mechanism for adjusting an impedance on the side of a plasma source,    wherein the impedance adjusting mechanism includes:    a resonance circuit formed to allow a radio frequency current to flow into the inner electrode of the first electrode;    a variable impedance unit installed on a power feed line to the inner electrode or the outer electrode of the first electrode;    a detector for detecting an apparatus state to be used to search a resonance point of the resonance circuit; and    a controller for searching a resonance point of the resonance circuit by detecting a signal of the apparatus state of the detector while varying a value of the variable impedance unit in a state where the plasma is formed and then adjusting the value of the variable impedance unit at the resonance point to a reference value.    
   
   
       4 . The plasma processing apparatus of  claim 3 , wherein a value of the variable impedance unit corresponding to the reference value is a value of the variable impedance unit at the resonance point of the resonance circuit before cleaning, or a value of the variable impedance unit at a resonance point of the resonance circuit of another apparatus having a same structure whose impedance has been adjusted.  
   
   
       5 . A plasma processing apparatus for performing a plasma processing on a substrate to be processed by generating a plasma of the processing gas in an evacuable processing chamber, the apparatus comprising: 
 a first and a second electrode disposed to face each other, the first electrode being divided into an inner and an outer electrode;    a radio frequency power supply unit for supplying a radio frequency power for generating a plasma to the first electrode;    a processing gas supply unit for supplying a processing gas into the processing chamber; and    an impedance adjusting mechanism for adjusting an impedance on the side of a plasma source, wherein the impedance adjusting mechanism includes:    a resonance circuit formed to allow a radio frequency current to flow into the inner electrode of the first electrode;    a variable capacitor installed on a power feed line to the inner electrode of the first electrode;    a detector for detecting an apparatus state to be used to search a resonance point of the resonance circuit; and    a controller for searching a resonance point of the resonance circuit by detecting a signal of the apparatus state of the detector while varying a capacitance of the variable capacitor in a state where the plasma is formed and then adjusting a capacitance of the variable capacitor at the resonance point to a reference value.    
   
   
       6 . The plasma processing apparatus of  claim 5 , wherein a capacitance of the variable capacitor corresponding to the reference value is a capacitance of the variable capacitor at the resonance point of the resonance circuit before cleaning, or a capacitance of the variable capacitor at a resonance point of the resonance circuit of another apparatus having a same structure whose impedance has been adjusted.  
   
   
       7 . The plasma processing apparatus of  claim 3 , wherein the resonance circuit is formed by a line allowing a radio frequency current to flow from the power feed line of the outer electrode to the inner electrode and a line allowing a radio frequency current to sequentially flow via the power feed line of the outer electrode, the outer electrode, the power feed line of the outer electrode and the variable impedance unit to the inner electrode.  
   
   
       8 . The plasma processing apparatus of  claim 3 , wherein the detector for detecting the apparatus state is a voltage detector installed on the side of the second electrode.  
   
   
       9 . The plasma processing apparatus of  claim 3 , wherein the radio frequency power supply unit includes a radio frequency power supply and a matching unit for matching a load impedance to an internal or output impedance of the radio frequency power supply, and wherein the detector for detecting the apparatus state detects a capacitance of a capacitor in the matching unit.  
   
   
       10 . The plasma processing apparatus of  claim 3 , wherein the detector for detecting the apparatus state is a VI probe, installed on the side of the first or the second electrode, for detecting a current or a voltage of a plasma.  
   
   
       11 . The plasma processing apparatus of  claim 3 , further comprising a radio frequency power supply unit for attracting ions to the second electrode serving as a supporting electrode for supporting the substrate to be processed.  
   
   
       12 . The plasma processing apparatus of  claim 11 , wherein the radio frequency power supply unit for attracting ions has a radio frequency power supply and a matching unit for matching a load impedance to an internal or output impedance of the radio frequency power supply.  
   
   
       13 . The plasma processing apparatus of  claim 12 , wherein the detector for detecting the apparatus state is a voltage detector installed at the matching unit on the side of the second electrode.  
   
   
       14 . An impedance adjustment method in a plasma processing apparatus including an evacuable processing chamber accommodating therein a substrate to be processed; a first and a second electrode disposed to face each other in the processing chamber; and a radio frequency power supply unit for supplying a radio frequency power for generating a plasma to the first electrode; and a processing gas supply unit for supplying a processing gas into the processing chamber, in order to perform a plasma processing on the substrate to be processed by generating a plasma of the processing gas between the first and the second electrode, the method comprising the steps of: 
 installing a variable impedance unit on a power feed line of the first electrode;    installing a detector for detecting an apparatus state to be used to search a resonance point of a resonance circuit formed to allow a radio frequency current to flow into the first electrode;    searching the resonance point of the resonance circuit by detecting a signal of the apparatus state with the detector while varying a value of the variable impedance unit in a state where the plasma is generated; and    adjusting the value of the variable impedance unit at the resonance point to a reference value, thereby adjusting an impedance on the side of a plasma source.    
   
   
       15 . The impedance adjustment method of  claim 14 , wherein the variable impedance unit is a variable capacitor.  
   
   
       16 . An impedance adjustment method in a plasma processing apparatus including an evacuable processing chamber accommodating therein a substrate to be processed; a first and a second electrode installed to face each other in the processing chamber, the first electrode being divided into an inner and an outer electrode; and a radio frequency power supply unit for supplying a plasma forming radio frequency power to the first electrode; and a processing gas supply unit for supplying a processing gas into the processing chamber, in order to perform a plasma processing on the substrate to be processed by generating a plasma of the processing gas between the first and the second electrode, the method comprising the steps of: 
 installing a variable impedance unit on a power feed line to the inner or the outer electrode of the first electrode;    installing a detector for detecting an apparatus state to be used to search a resonance point of a resonance circuit formed to allow a radio frequency current to flow into the inner electrode of the first electrode;    searching the resonance point of the resonance circuit by detecting a signal of the apparatus state with the detector while varying a value of the variable impedance unit in a state where the plasma is generated; and    adjusting the value of the variable impedance unit at the resonance point to a reference value, thereby adjusting an impedance on the side of a plasma source.    
   
   
       17 . The impedance adjustment method of  claim 14 , wherein the value of the variable impedance unit corresponding to the reference value is a value of the variable impedance unit at the resonance point of the resonance circuit before cleaning, or a value of the variable impedance unit at a resonance point of the resonance circuit of another apparatus having a same structure whose impedance has been adjusted.  
   
   
       18 . An impedance adjustment method in a plasma processing apparatus including an evacuable processing chamber accommodating therein a substrate to be processed; a first and a second electrode installed to face each other in the processing chamber, the first electrode being divided into an inner and an outer electrode; and a radio frequency power supply unit for supplying a plasma forming radio frequency power to the first electrode; and a processing gas supply unit for supplying a processing gas into the processing chamber, in order to perform a plasma processing on the substrate to be processed by generating a plasma of the processing gas between the first and the second electrode, the method comprising the steps of: 
 installing a variable capacitor on a power feed line to the inner electrode of the first electrode;    installing a detector for detecting an apparatus state to be used to search a resonance point of a resonance circuit formed to allow a radio frequency current to flow into the inner electrode of the first electrode;    searching the resonance point of the resonance circuit by detecting a signal of the apparatus state with the detector while varying a capacitance of the capacitor in a state where the plasma is generated; and    adjusting a capacitance value of the variable capacitor at the resonance point to a reference value, thereby adjusting an impedance on the side of a plasma source.    
   
   
       19 . The plasma processing apparatus of  claim 18 , wherein the capacitance of the variable capacitor corresponding to the reference value is a capacitance of the variable capacitor at the resonance point of the resonance circuit before cleaning, or a capacitance of the variable capacitor at a resonance point of the resonance circuit of another apparatus having a same structure whose impedance has been adjusted.  
   
   
       20 . The impedance adjustment method of  claim 16 , wherein the resonance circuit is formed by a line allowing a radio frequency current to flow from the power feed line of the outer electrode to the inner electrode and a line allowing a radio frequency current to flow sequentially via the power feed line of the outer electrode, the outer electrode, the power feed line of the outer electrode and the variable impedance unit to the inner electrode.  
   
   
       21 . The impedance adjustment method of  claim 16 , wherein the detector for detecting the apparatus state is a voltage detector installed on the side of the second electrode.  
   
   
       22 . The impedance adjustment method of  claim 16 , wherein the radio frequency power supply unit includes a radio frequency power supply and a matching unit for matching a load impedance to an internal or output impedance of the radio frequency power supply, and wherein the detector for detecting the apparatus state detects a capacitance of a capacitor of the matching unit.  
   
   
       23 . The impedance adjustment method of  claim 16 , wherein the detector for detecting the apparatus state is a VI probe installed on the side of the first or the second electrode, for detecting a current or a voltage of a plasma.