Plasma processing with preionized and predissociated tuning gases and associated systems and methods

Abstract

Plasma processing systems and methods for using pre-dissociated and/or pre-ionized tuning gases are disclosed herein. In one embodiment, a plasma processing system includes a reaction chamber, a support element in the reaction chamber, and one or more cathode discharge assemblies in the reaction chamber. The reaction chamber is configured to produce a plasma in an interior volume of the chamber. The support element positions a microelectronic workpiece in the reaction chamber, and the cathode discharge assembly supplies an at least partially dissociated and/or ionized tuning gas to the workpiece in the chamber.

1 . A plasma reactor, comprising:
 a reaction chamber;   a support element in the chamber for carrying a microelectronic workpiece in a workpiece plane;   one or more cathode discharge assemblies in the chamber, wherein individual cathode discharge assemblies have a flow port configured to direct a tuning gas upwardly away from the workpiece plane, wherein the individual cathode discharge assemblies further include a cathode and an anode at or around an outer perimeter of the support element, the cathode and the anode configured to at least partially dissociate and/or ionize the tuning gas by an electrical field formed at least partially between the cathode and the anode; and   a power supply electrically coupled with the cathode discharge assemblies to control the electrical field that causes the dissociation and/or ionization of the tuning gas within the flow port.   
     
     
         2 . The reactor of  claim 1  wherein the individual cathode discharge assemblies include a cathode and an anode surrounding a portion of the flow port, and wherein the power supply is configured to control an electric field region defined by the cathode and the anode. 
     
     
         3 . The reactor of  claim 1 , further comprising a signal delivery device operably coupled with the power supply for automatically or semiautomatically controlling etching parameters at a surface of the workpiece via the power supply. 
     
     
         4 . The reactor of  claim 3  wherein the power supply comprises a first power supply and the support element includes a first electrode surface, and wherein the reactor further comprises:
 a gas distributor in the chamber, the gas distributor facing the support element, having a second electrode surface, and openings configured to direct a process gas into the chamber and toward the workpiece plane; and 
 a second power supply electrically coupled with the first and second electrodes for dissociating and/or ionizing the process gas, 
 wherein the signal delivery component is also operably coupled with the second power supply. 
 
     
     
         5 . The reactor of  claim 4  wherein the signal delivery component is operably coupled with the gas supply of the process gas and/or the gas supply of the tuning gas to control the rate of flow and/or the pressure of the process gas and/or the tuning gas in the chamber. 
     
     
         6 . A plasma reactor, comprising:
 a chamber having an interior volume for processing a workpiece; and   a cathode discharge assembly configured to supply a tuning gas to the interior volume of the chamber, the cathode discharge assembly having a flow port, a cathode, and an anode, wherein the cathode and the anode are located at or around an outer perimeter of a workpiece support that carries the workpiece inside the chamber and are configured to at least partially dissociate and/or ionize the tuning gas as the flow port delivers the tuning gas to the interior volume of the chamber.   
     
     
         7 . The reactor of  claim 6 , further comprising a gas distributor configured to supply a process gas to the interior volume of the chamber and provide an electrode surface for forming a plasma in the interior volume of the chamber via the process gas and the electrode surface, wherein the cathode discharge assembly is separate from the gas distributor. 
     
     
         8 . The reactor of  claim 7 , wherein the outer perimeter of the workpiece support is adjacent to the flow port of the cathode discharge assembly, and wherein the gas distributor is configured to direct the process gas downward toward the support and the cathode discharge assembly is configured to direct the tuning gas upward. 
     
     
         9 . The reactor of  claim 6  further comprising:
 a plurality of cathode discharge assemblies surrounding the outer perimeter of the workpiece support. 
 
     
     
         10 . The reactor of  claim 9  wherein the plurality of cathode discharge assemblies are disposed radially about the workpiece. 
     
     
         11 . The reactor of  claim 6  wherein the dissociated and/or ionized tuning gas includes a majority population of reactive chemical species that is larger than a minority population of nondissociated and/or nonionized chemical species. 
     
     
         12 . The reactor of  claim 11  wherein the majority population of reactive chemical species includes dissociated chemical species and/or ionized chemical species. 
     
     
         13 . The reactor of  claim 11  wherein the reactive chemical species etch an edge of the workpiece and/or passivate the edge of the workpiece. 
     
     
         14 . The reactor of  claim 6  wherein an edge of the workpiece is etched by the at least partially dissociated or ionized tuning gas while a surface of the workpiece is etched and/or passivated by a process gas supplied to the interior volume of the chamber by a gas distributor. 
     
     
         15 . The reactor of  claim 6  wherein the at least partially dissociated or ionized tuning gas is consumed primarily by reactions at an edge of the workpiece. 
     
     
         16 . The reactor of  claim 6  wherein the tuning gas at an outlet of the cathode discharge assembly has density on the order of 10 15  cm −3  or greater and electron energies on the order of 1-10 eV. 
     
     
         17 . The reactor of  claim 6  wherein an outlet of the cathode discharge assembly is annular.