Systems and methods for providing shunt cancellation of parasitic components in a plasma reactor

Abstract

Systems and methods for negating an impedance associated with parasitic capacitance are described. One of the systems includes a plasma chamber having a housing. The housing includes a pedestal, a showerhead situated above the pedestal to face the pedestal, and a ceiling located above the showerhead. The system further includes a radio frequency (RF) transmission line coupled to the plasma chamber for transferring a modified RF signal to the showerhead. The system includes a shunt circuit coupled within a pre-determined distance from the ceiling. The shunt circuit is coupled to the RF transmission line for negating the impedance associated with the parasitic capacitance within the housing.

1 . A system for negating an impedance associated with parasitic capacitance, comprising:
 a plasma chamber having a housing, wherein the housing includes:
 a pedestal; 
 a showerhead situated above the pedestal to face the pedestal; and 
 a ceiling located above the showerhead; 
   a radio frequency (RF) transmission line coupled to the plasma chamber for transferring a modified RF signal to the showerhead; and   a shunt circuit coupled within a pre-determined distance from the ceiling, wherein the shunt circuit is coupled to the RF transmission line for negating the impedance associated with the parasitic capacitance within the housing.   
     
     
         2 . The system of  claim 1 , wherein the shunt circuit is coupled to a ground potential at one end and is coupled to the RF transmission line at another end. 
     
     
         3 . The system of  claim 1 , wherein the shunt circuit is coupled to the housing at one end to be coupled to a ground potential and is coupled to the RF transmission line at another end. 
     
     
         4 . The system of  claim 1 , wherein the shunt circuit is coupled to the ceiling at one end to be coupled to a ground potential and is coupled to the RF transmission line at another end. 
     
     
         5 . The system of  claim 1 , wherein the shunt circuit includes an inductor coupled in parallel to a variable capacitor. 
     
     
         6 . The system of  claim 1 , wherein the shunt circuit includes an inductor. 
     
     
         7 . The system of  claim 1 , further comprising:
 a motor coupled to the shunt circuit;   a processor coupled to the motor, wherein the motor is configured to control the motor to change a capacitance of the shunt circuit to increase the impedance associated with the parasitic capacitance.   
     
     
         8 . The system of  claim 1 , further comprising:
 a motor coupled to the shunt circuit;   a processor coupled to the motor, wherein the processor is configured to control the motor to increase the impedance until a parameter measured by a probe is within a pre-determined range.   
     
     
         9 . The system of  claim 1 , wherein the housing includes a side wall, wherein the showerhead is coupled to the side wall to be supported by the side wall. 
     
     
         10 . A shunt circuit comprising:
 a variable capacitor; and   an inductor coupled in parallel with the variable capacitor to form a first end and a second end,   wherein the first end is coupled to a radio frequency (RF) transmission line coupled between an impedance matching circuit and a showerhead of a plasma chamber, wherein the second end is coupled to a housing of the plasma chamber, wherein the variable capacitor and the inductor are configured to negate an impedance associated with the parasitic capacitance within the housing.   
     
     
         11 . The shunt circuit of  claim 10 , wherein the second end is coupled to a ceiling of the housing of the plasma chamber to be coupled to a ground potential. 
     
     
         12 . The shunt circuit of  claim 10 , wherein the variable capacitor is coupled to a motor to change a capacitance of the variable capacitor until a parameter at an output of the impedance matching circuit is within a pre-determined range, wherein the RF transmission line is coupled to the output of the impedance matching circuit. 
     
     
         13 . The shunt circuit of  claim 12 , wherein the motor is coupled to a processor, wherein the processor is coupled to a probe for receiving a measurement of the parameter from the probe. 
     
     
         14 . The shunt circuit of  claim 13 , wherein the probe is coupled to the output of the impedance matching circuit. 
     
     
         15 . The shunt circuit of  claim 10 , wherein the housing includes a side, wherein the showerhead is coupled to the side to be supported by the side. 
     
     
         16 . A multi-station processing tool comprising:
 a radio frequency (RF) generator configured to generate an RF signal;   an impedance matching circuit coupled to the RF generator to receive the RF signal to output a modified RF signal; and   a power splitter coupled to the impedance matching circuit to distribute power of the modified RF signal to output a plurality of modified RF output signals;   a first station coupled to a first output of the power splitter via a first RF transmission line to receive a first one of the modified RF output signals;   a second station coupled to a second output of the power splitter via a second RF transmission line to receive a second one of the modified RF output signals;   a first shunt circuit coupled to the first RF transmission line to negate an impedance associated with a parasitic capacitance associated with the first station; and   a second shunt circuit coupled to the second RF transmission line to negate an impedance associated with a parasitic capacitance associated with the second station.   
     
     
         17 . The multi-station processing tool of  claim 16 , wherein the first station has a first housing and the second station has a second housing, wherein the first shunt circuit has an end coupled to the first housing to be coupled to a ground potential of the first station and has another end coupled to the first RF transmission line, wherein the second shunt circuit has an end coupled to the second housing to be coupled to a ground potential of the second station and has another end coupled to the second RF transmission line. 
     
     
         18 . The multi-station processing tool of  claim 16 , wherein the first station has a first housing and the second station has a second housing, wherein the first shunt circuit has an end coupled to a ceiling of the first housing to be coupled to a ground potential of the first station and has another end coupled to the first RF transmission line, wherein the second shunt circuit has an end coupled to a ceiling of the second housing to be coupled to a ground potential of the second station and has another end coupled to the second RF transmission line. 
     
     
         19 . The multi-station processing tool of  claim 16 , wherein the first shunt circuit includes an inductor coupled in parallel with a capacitor, wherein the second shunt circuit includes an inductor coupled in parallel with a capacitor. 
     
     
         20 . The multi-station processing tool of  claim 16 , wherein the first shunt circuit includes an inductor, wherein the second shunt circuit includes an inductor.