Apparatus for improved low pressure inductively coupled high density plasma reactor

Abstract

A plasma reactor comprises an electromagnetic energy source coupled to a radiator through first and second variable impedance networks. The plasma reactor includes a chamber having a dielectric window that is proximate to the radiator. A shield is positioned between the radiator and the dielectric window. The shield substantially covers a surface of the radiator near the dielectric window. A portion of the radiator that is not covered by the shield is proximate to a conductive wall of the chamber. Plasma reactor operation includes the following steps. A plasma is ignited in a chamber with substantially capacitive electric energy coupled from the radiator. A variable impedance network is tuned so that the capacitive electric energy coupled into the chamber is diminished. The plasma is then powered with substantially magnetic energy.

1 . A plasma reactor, comprising: 
 an electromagnetic energy source;    a first impedance network operatively coupled to the electromagnetic energy source;    a radiator operatively coupled to the electromagnetic energy source by the first impedance network;    a second impedance network serially coupled to the radiator and operatively coupled to the electromagnetic energy source;    a chamber having a window that is proximate to the radiator and a conductive wall;    a shield, positioned between the radiator and the window, substantially covering a surface of the radiator near the window;    a portion of the radiator that is not covered by the shield is proximate to the conductive wall; and    wherein the first impedance network includes: 
 a first capacitor and a second, fixed capacitor serially connected between the electromagnetic energy source and the radiator,  
 an electrical connection between the first capacitor and the second capacitor, and  
 a third capacitor having a first plate connected at the electrical connection and having a second plate connected to ground.  
   
   
   
       2 . The plasma reactor of  claim 1 , wherein the electromagnetic energy source operates at a frequency of less than one hundred megahertz.  
   
   
       3 . The plasma reactor of  claim 1 , wherein the chamber comprises a dielectric liner.  
   
   
       4 . The plasma reactor of  claim 1 , wherein the second impedance network includes a variable capacitor.  
   
   
       5 . The plasma reactor of  claim 1 , wherein the chamber comprises a chamber adapted to hold a plasma that causes constituents of precursor gases in the chamber to form a material on a substrate in the chamber.  
   
   
       6 . The plasma reactor of  claim 1 , further comprising a plasma that removes material from a substrate placeable in the chamber.  
   
   
       7 . The plasma reactor of  claim 1 , further comprising a second electromagnetic energy source coupled to a wafer in the chamber.  
   
   
       8 . The plasma reactor of  claim 1 , wherein the radiator is a coil.  
   
   
       9 . The plasma reactor of  claim 8 , wherein the coil is a planar coil.  
   
   
       10 . The plasma reactor of  claim 1 , wherein the first impedance network comprises a variable impedance network.  
   
   
       11 . The plasma reactor of  claim 1 , wherein the first capacitor is a variable capacitor.  
   
   
       12 . The plasma reactor of  claim 1 , wherein the third capacitor is a variable capacitor.  
   
   
       13 . The plasma reactor of  claim 1 , wherein the third capacitor is a shunt capacitor.  
   
   
       14 . The plasma reactor of  claim 1 , wherein the window comprises a dielectric window.  
   
   
       15 . A plasma reactor, comprising: 
 a radio frequency energy source;    an impedance network;    a first capacitor;    a coil, operatively coupled to the radio frequency energy source by the impedance network and the first capacitor;    a chamber having a dielectric window that is proximate to the coil and having a conductive wall;    a shield, positioned between the coil and the dielectric window, substantially covering a surface of the coil near the dielectric window;    wherein a portion of the coil that is not covered by the shield is proximate to the conductive wall of the chamber; and    wherein the impedance network includes: 
 a second capacitor serially connected to the radio frequency energy source,  
 a third capacitor connected in parallel across the second capacitor and the radio frequency energy source, and  
 a fourth capacitor serially connected between the second capacitor and the coil.  
   
   
   
       16 . The plasma reactor of  claim 15 , wherein the radio frequency energy source operates at a frequency of less than one hundred megahertz.  
   
   
       17 . The plasma reactor of  claim 15 , wherein the chamber comprises a dielectric liner.  
   
   
       18 . The plasma reactor of  claim 15 , wherein the chamber comprises a chamber adapted to hold a plasma that causes constituents of precursor gases in the chamber to form a material on a substrate in the chamber.  
   
   
       19 . The plasma reactor of  claim 15 , further comprising a plasma that removes material from a substrate placeable in the chamber.  
   
   
       20 . The plasma reactor of  claim 15 , further comprising an electromagnetic energy source coupled to a substrate in the chamber.  
   
   
       21 . The plasma reactor of  claim 15 , wherein the coil is a planar coil.  
   
   
       22 . The plasma reactor of  claim 15 , wherein the shield comprises a Faraday shield.  
   
   
       23 . The plasma reactor of  claim 15 , wherein the impedance network is a variable impedance network.  
   
   
       24 . The plasma reactor of  claim 15 , wherein at least one of the first capacitor, second capacitor and the third capacitor is a variable capacitor.  
   
   
       25 . A plasma reactor, comprising: 
 a chamber having a dielectric window;    a radio frequency energy source;    a radiator positioned outside the chamber next to the dielectric window; and    an impedance network coupled between the radio frequency energy source and a first end of the radiator, and including: 
 a first capacitor and a second capacitor serially connected between the radio frequency energy source and the radiator, and  
 a third capacitor having a first plate connected to the electrical connection between the first capacitor and the second capacitor, and having a second plate connected to ground.  
   
   
   
       26 . The plasma reactor of  claim 25 , further including a second, variable impedance network connected between a second end of the radiator and ground.  
   
   
       27 . The plasma reactor of  claim 26 , wherein the second variable impedance network includes a variable capacitor connected between the second end of the radiator and ground.  
   
   
       28 . The plasma reactor of  claim 25 , wherein at least one of the first capacitor and the third capacitor is a variable capacitor.  
   
   
       29 . The plasma reactor of  claim 25 , wherein the second capacitor is a fixed shunt capacitor.  
   
   
       30 . A plasma reactor, comprising: 
 a chamber having a dielectric window;    a radio frequency energy source;    a radiator coil positioned outside the chamber next to the dielectric window;    a Faraday shield positioned between the dielectric window and the radiator coil; and    a first impedance network electrically coupled between the radio frequency energy source and a first location on the radiator coil, and having 
 a first capacitor and a second capacitor serially connected between the radio frequency energy source and the first location on the radiator, and  
 a third capacitor having a first plate connected to the electrical connection between the first capacitor and the second capacitor, and having a second plate connected to ground; and  
   a second, variable impedance network electrically coupled to a second location on the radiator coil, and having a fourth capacitor connected between the second location on the radiator coil and ground.    
   
   
       31 . The plasma reactor of  claim 30 , wherein the fourth capacitor is a variable capacitor.  
   
   
       32 . The plasma reactor of  claim 30 , wherein at least one of the first and third capacitors is a variable capacitor.  
   
   
       33 . The plasma reactor of  claim 30 , wherein the third capacitor is a fixed, shunt capacitor.  
   
   
       34 . The plasma reactor of  claim 30 , wherein the first impedance network is a variable impedance network.  
   
   
       35 . A plasma reactor, comprising: 
 an electromagnetic energy source;    a first impedance network operatively coupled to the electromagnetic energy source;    a radiator operatively coupled to the electromagnetic energy source by the first impedance network;    a second impedance network serially coupled to the radiator and operatively coupled to the electromagnetic energy source;    a chamber having a window that is proximate to the radiator and a conductive wall;    a shield, positioned between the radiator and the window, substantially covering a surface of the radiator near the window;    wherein a first impedance is set by the first impedance network and the second impedance network, the first impedance being adapted to enhance energy transfer from the radiator to the chamber to ignite a plasma; and    wherein a second impedance is set by the first impedance network and the second impedance network, the second impedance being adapted to sustain the plasma.    
   
   
       36 . The plasma reactor of  claim 35 , wherein the second impedance is further adapted to reposition a relatively high electric potential to a portion of the radiator that is electrically isolated from the chamber.  
   
   
       37 . The plasma reactor of  claim 35 , wherein the second impedance is further adapted to reposition a relatively high electric potential to a portion of the radiator that is unexposed by the shield.  
   
   
       38 . A plasma reactor, comprising: 
 an impedance network adapted to provide a first impedance and a second impedance;    an electromagnetic energy source;    a radiator operatively coupled to the electromagnetic energy source by the impedance network;    a chamber;    wherein the first impedance is adapted to enhance energy transfer from the radiator to the chamber to ignite a plasma; and    wherein the second impedance is adapted to sustain the plasma.    
   
   
       39 . A plasma reactor, comprising: 
 means for igniting a plasma with a first impedance between an electromagnetic source and a radiator; and    means for sustaining the plasma with a second impedance.