Inductively coupled plasma apparatus

Abstract

Methods and apparatus for plasma processing are provided herein. In some embodiments, a plasma processing apparatus includes a process chamber having an interior processing volume; a first RF coil disposed proximate the process chamber to couple RF energy into the processing volume; and a second RF coil disposed proximate the process chamber to couple RF energy into the processing volume, the second RF coil disposed coaxially with respect to the first RF coil, wherein the first and second RF coils are configured such that RF current flowing through the first RF coil is out of phase with RF current flowing through the RF second coil.

1 . A plasma processing apparatus, comprising:
 a process chamber having an interior processing volume;   a first RF coil disposed proximate the process chamber to couple RF energy into the processing volume;   a second RF coil disposed proximate the process chamber to couple RF energy into the processing volume, the second RF coil disposed coaxially with respect to the first RF coil; and   a phase shifter coupled to either the first or second RF coil to shift the phase of the RF current flowing therethrough such that that RF current flowing through the first RF coil is out of phase with RF current flowing through the second RF coil.   
     
     
         2 . The apparatus of  claim 1 , wherein the phase shifter shifts the phase of the RF current such that the RF current flowing through the first RF coil is about 180 degrees out of phase with RF current flowing through the RF second coil. 
     
     
         3 . The apparatus of  claim 1 , wherein the first RF coil and the second RF coil are wound in the same direction. 
     
     
         4 . The apparatus of  claim 1 , wherein the first RF coil is wound in a first direction and wherein the second RF coil is wound in a second direction opposite the first direction. 
     
     
         5 . A plasma processing apparatus, comprising:
 a process chamber having an interior processing volume;   a first RF coil disposed proximate the process chamber to couple RF energy into the processing volume;   a second RF coil disposed proximate the process chamber to couple RF energy into the processing volume, the second RF coil disposed coaxially with respect to the first RF coil; and   one or more blocking capacitors coupled to at least one or the first or second RF coil to shift the phase of the RF current flowing therethrough such that RF current that flows through the first RF coil is out of phase with RF current that flows through the second RF coil.   
     
     
         6 . The apparatus of  claim 5 , wherein the one or more blocking capacitors shift the phase of the RF current such that the RF current flowing through the first RF coil is about 180 degrees out of phase with RF current flowing through the RF second coil. 
     
     
         7 . The apparatus of  claim 5 , wherein the first RF coil and the second RF coil are wound in the same direction. 
     
     
         8 . The apparatus of  claim 5 , wherein the first RF coil is wound in a first direction and wherein the second RF coil is wound in a second direction opposite the first direction. 
     
     
         9 . A method of forming a plasma, comprising:
 providing an RF signal through a first RF coil;   providing the RF signal through a second RF coil coaxially disposed with respect to the first RF coil such that the RF signal flows through the second coil out of phase with respect to the flow of the RF signal through the first coil, wherein at least one of a phase shifter or one or more blocking capacitors are used to shift the phase of the RF signal such that the RF signal flowing through the first RF coil is out of phase with RF signal flowing through the second RF coil; and   forming a plasma by coupling the RF signal provided by the first and second RF coils to a process gas disposed in a process chamber.   
     
     
         10 . The method of  claim 9 , wherein the RF signal flowing through the first and second RF coils are about 180 degrees out of phase. 
     
     
         11 . The method of  claim 9 , wherein the first RF coil and the second RF coil are wound in the same direction. 
     
     
         12 . The method of  claim 9 , wherein the first RF coil is wound in a first direction and wherein the second RF coil is wound in a second direction opposite the first direction.