High impedance rf filter for heater with impedance tuning device

Abstract

Embodiments provide a plasma processing apparatus, substrate support assembly, and method of controlling a plasma process. The apparatus and substrate support assembly include a substrate support pedestal, a tuning assembly that includes a tuning electrode that is disposed in the pedestal and electrically coupled to a radio frequency (RF) tuner, and a heating assembly that includes one or more heating elements disposed within the pedestal for controlling a temperature profile of the substrate, where at least one of the heating elements is electrically coupled to an RF filter circuit that includes a first inductor configured in parallel with a formed capacitance of the first inductor to ground. The high impedance of the RF filters can be achieved by tuning the resonance of the RF filter circuit, which results in less RF leakage and better substrate processing results.

1 . A method of processing a substrate, comprising:
 generating a radio frequency (RF) plasma in a process volume of a processing chamber;   controlling an impedance of a tuning circuit, wherein controlling the impedance includes minimizing the impedance of a tuning electrode disposed within a substrate supporting pedestal to ground; and   reducing RF coupling between a heater element disposed within the substrate supporting pedestal and the generated RF plasma, wherein the reducing the RF coupling comprises electrically coupling an RF filter circuit that comprises a first inductor in parallel with a first capacitance to the heater element.   
     
     
         2 . The method of  claim 1 , wherein the RF filter circuit is disposed within a grounded enclosure. 
     
     
         3 . The method of  claim 2 , further comprising:
 positioning the first inductor relative to a grounded surface of the grounded enclosure to form the first capacitance.   
     
     
         4 . The method of  claim 1 , wherein minimizing the impedance of the tuning electrode comprises adjusting a variable capacitor configured in parallel with a second inductor. 
     
     
         5 . The method of  claim 4 , wherein the variable capacitor is further configured in series with a third inductor. 
     
     
         6 . The method of  claim 4 , wherein the minimized impedance of the tuning circuit is less than an impedance of the RF filter circuit. 
     
     
         7 . The method of  claim 4 , wherein the heater element controls a temperature profile across a surface of the substrate supporting pedestal. 
     
     
         8 . The method of  claim 4 , wherein the tuning electrode is disposed closer to a surface of the pedestal than the heating element. 
     
     
         9 . A method of processing a substrate, comprising:
 providing an alternating current power to one or more heating elements disposed in a substrate support;   generating a radio frequency (RF) plasma in a process volume of a process chamber; and   adjusting a capacitance of a variable capacitor disposed in an RF tuner coupled to a tuning electrode in the substrate support, the variable capacitor terminated to ground through a first inductor.   
     
     
         10 . The method of  claim 9 , wherein the adjusting the capacitance of the variable capacitor reduces an impedance of the RF tuner. 
     
     
         11 . The method of  claim 10 , wherein the adjusting the capacitance of the variable capacitor controls a current flow through the tuning electrode disposed in the substrate support in the process volume. 
     
     
         12 . The method of  claim 11 , wherein the capacitance of the variable capacitor is adjusted based on a sensor of the RF tuner, and wherein a first terminal of the sensor coupled directly to the tuning electrode. 
     
     
         13 . The method of  claim 9 , wherein adjusting the capacitance of the variable capacitor comprises controlling an RF current through the tuning electrode. 
     
     
         14 . The method of  claim 13 , wherein adjusting the capacitance of the variable capacitor further comprises controlling plasma uniformity in the process volume. 
     
     
         15 . A plasma processing apparatus, comprising:
 a chamber body and a powered gas distribution manifold enclosing a process volume;   a pedestal disposed in the process volume, the pedestal having a substrate supporting surface and a stem extending below the substrate supporting surface;   a heating assembly; and   a controller configured to perform one or more operations, the one or more operations comprising:
 generating a radio frequency (RF) plasma in the process volume; 
 controlling an impedance of a tuning circuit, wherein controlling the impedance includes minimizing the impedance of a tuning electrode disposed within a substrate supporting pedestal to ground; and 
 reducing RF coupling between a heater element disposed within the substrate supporting pedestal and the generated RF plasma, wherein the reducing the RF coupling comprises electrically coupling an RF filter circuit that comprises a first inductor in parallel with a first capacitance to the heater element. 
   
     
     
         16 . The plasma processing apparatus of  claim 15 , wherein minimizing the impedance of the tuning electrode comprises adjusting a variable capacitor configured in parallel with a second inductor. 
     
     
         17 . The plasma processing apparatus of  claim 15 , wherein the tuning circuit comprises a variable capacitor. 
     
     
         18 . The plasma processing apparatus of  claim 17 , wherein controlling the impedance of the tuning circuit comprises:
 controlling a capacitance of the variable capacitor.   
     
     
         19 . The plasma processing apparatus of  claim 18 , wherein the minimized impedance of the tuning circuit is less than an impedance of the RF filter circuit. 
     
     
         20 . The plasma processing apparatus of  claim 18 , wherein the tuning electrode is disposed closer to a surface of the pedestal than the heating element.