Method and apparatus of achieving high input impedance without using ferrite materials for rf filter applications in plasma

Abstract

Implementations of the present disclosure generally relate to methods and apparatus for generating and controlling plasma, for example RF filters, used with plasma chambers. In one implementation, a plasma processing apparatus is provided. The plasma processing apparatus comprises a chamber body, a powered gas distribution manifold enclosing a processing volume and a radio frequency (RF) filter. A pedestal having a substrate-supporting surface is disposed in the processing volume. A heating assembly comprising one or more heating elements is disposed within the pedestal for controlling a temperature profile of the substrate-supporting surface. A tuning assembly comprising a tuning electrode is disposed within the pedestal between the one or more heating elements and the substrate-supporting surface. The RF filter comprises an air core inductor, wherein at least one of the heating elements, the tuning electrode, and the gas distribution manifold is electrically coupled to the RF filter.

1 . An air core inductor, comprising:
 a first helical coil section having a number of coil turns; and   a second helical coil section having a number of coil turns and positioned to overlap the first helical coil section both axially and, wherein the first helical coil section and the second helical coil section share a common longitudinal axis and the wire of each helical coil section has a rectangular cross-section.   
     
     
         2 . The air core inductor of  claim 1 , further comprising:
 a third helical coil section positioned to overlap the second helical coil section both axially and radially, wherein the wire of the third helical coil section has a rectangular cross-section.   
     
     
         3 . The air core inductor  claim 1 , wherein the second helical coil section has an inner diameter slightly smaller than an outer diameter of the first helical coil section. 
     
     
         4 . The air core inductor of  claim 3 , wherein insulating material extends radially between the first helical coil section and the second helical coil section. 
     
     
         5 . The air core inductor of  claim 1 , wherein the first helical coil section and the second helical coil section are electrically and mechanically connected at one end of the sections. 
     
     
         6 . The air core inductor of  claim 1 , wherein the number of coil turns of the first helical coil section and the number of turns of the second helical coil section are the same. 
     
     
         7 . The air core inductor of  claim 1 , wherein the number of coil turns of the first helical coil section is greater than the number of coil turns of the second helical coil section. 
     
     
         8 . The air core inductor of  claim 1 , wherein the coil turns of the first helical coil section and the coil turns of the second helical coil section are wound in the same direction. 
     
     
         9 . The air core inductor of  claim 1 , further comprising an elongated non-magnetic core assembly, wherein the first helical coil section and the second helical coil section encircle the elongated non-magnetic core assembly. 
     
     
         10 . The air core inductor of  claim 1 , wherein the air core inductor has an air gap and the first helical coil section and the second helical coil section encircle the air gap. 
     
     
         11 . A substrate support assembly, comprising:
 a substrate support pedestal having a substrate-supporting surface;   a heating assembly comprising one or more heating elements disposed within the substrate support pedestal for controlling a temperature profile of the substrate-supporting surface;   a tuning assembly comprising a tuning electrode that is disposed within the substrate support pedestal; and   a radio frequency (RF) filter comprising an air core inductor, wherein at least one of the heating elements and the tuning electrode is electrically coupled to the RF filter, the air core inductor comprising:
 a first helical coil section having a number of coil turns; and 
 a second helical coil section having a number of coil turns and positioned to overlap the first helical coil section both axially and radially, wherein the first helical coil section and the second helical coil section share a common longitudinal axis and the wire of each helical coil section has a rectangular cross-section. 
   
     
     
         12 . The substrate support assembly of  claim 11 , further comprising:
 a third helical coil section positioned to overlap the second helical coil section both axially and radially, wherein the wire of the third helical coil section has a rectangular cross-section.   
     
     
         13 . The substrate support assembly of  claim 11 , wherein the second helical coil section has an inner diameter slightly smaller than the outer diameter of the first helical coil section. 
     
     
         14 . The substrate support assembly of  claim 13 , wherein insulating material extends radially between the first helical coil section and the second helical coil section. 
     
     
         15 . The substrate support assembly of  claim 11 , wherein the first helical coil section and the second helical coil section are electrically and mechanically connected at one end of the sections. 
     
     
         16 . The substrate support assembly of  claim 11 , wherein the air core inductor further comprises an elongated non-magnetic core assembly, wherein the first helical coil section and the second helical coil section encircle the elongated non-magnetic core assembly. 
     
     
         17 . The substrate support assembly of  claim 11 , wherein the air core inductor has an air gap. 
     
     
         18 . The substrate support assembly of  claim 17 , wherein the first helical coil section and the second helical coil section encircle the air gap. 
     
     
         19 . A substrate support assembly, comprising:
 a substrate support pedestal having a substrate-supporting surface;   a heating assembly comprising one or more heating elements disposed within the substrate support pedestal for controlling a temperature profile of the substrate-supporting surface;   a tuning assembly comprising a tuning electrode that is disposed within the substrate support pedestal; and   a radio frequency (RF) filter comprising an air core inductor, wherein the air core inductor comprises:
 a first helical coil section having a number of coil turns; 
 a second helical coil section having a number of coil turns and positioned to overlap the first helical coil section both axially and radially; and 
 a third helical coil section positioned to overlap the second helical coil section both axially and radially,
 wherein the wire of each of the first helical coil section, the section helical coil section, and the third helical coil section has a rectangular cross-section, 
 wherein the first helical coil section and the second helical coil section share a common longitudinal axis, 
 wherein at least one of the heating elements and the tuning electrode is electrically coupled to the RF filter, and 
 wherein the RF filter comprises at least two of the air core inductors connected in series. 
 
   
     
     
         20 . The substrate support assembly of  claim 19 , wherein the air core inductor further comprises an elongated non-magnetic core assembly, wherein the first helical coil section, the second helical coil section, and the third helical coil section encircle the elongated non-magnetic core assembly.