Plasma immersion ion implantion apparatus and method

Abstract

A plasma immersion ion implant apparatus and method, and a plasma chamber, each configured to provide a uniform ion flux and to dissipate the effects of secondary electrons are disclosed. The invention includes a plasma chamber including a dielectric tophat configuration and a conductive top section that may be liquid cooled. In addition, the invention provides a radio frequency (RF) antenna configuration including an active antenna that is coupled to an RF source and a parasitic antenna that is not directly coupled to any RF source, but may be grounded. The RF antenna allows for tuning of the RF coupling.

1 . A plasma immersion ion implant apparatus comprising: 
 a plasma chamber configured to receive a process gas;    a radio frequency (RF) source configured to resonate radio frequency currents in a radio frequency antenna;    a radio frequency antenna including an active antenna surrounding the plasma chamber and coupled to the RF source and a parasitic antenna surrounding the plasma chamber and not directly coupled to any RF source; and    a platen for holding a target,    wherein electro-magnetic fields induced by the radio frequency currents are effective to pass into the plasma chamber and excite and ionize the process gas to generate plasma within the plasma chamber.    
   
   
       2 . The apparatus of  claim 1 , wherein the active antenna includes a horizontally-extending coil and the parasitic antenna includes a vertically-extending coil.  
   
   
       3 . The apparatus of  claim 1 , wherein the active antenna includes a vertically-extending coil and the parasitic antenna includes a horizontally-extending coil.  
   
   
       4 . The apparatus of  claim 1 , wherein the parasitic antenna includes a plurality of turns with one end grounded.  
   
   
       5 . The apparatus of  claim 4 , further comprising means for adjusting a number of turns of the parasitic antenna providing a parasitic effect.  
   
   
       6 . The apparatus of  claim 1 , wherein the parasitic antenna includes a plurality of turns with both ends floating.  
   
   
       7 . The apparatus of  claim 1 , wherein an inner diameter of each antenna is greater than a size of the target.  
   
   
       8 . The apparatus of  claim 1 , wherein the parasitic antenna is above and coaxial with the active antenna.  
   
   
       9 . The apparatus of  claim 1 , wherein at least one antenna is liquid cooled.  
   
   
       10 . The apparatus of  claim 9 , wherein the parasitic antenna is coupled to the plasma chamber via a thermally conductive elastomer.  
   
   
       11 . The apparatus of  claim 1 , wherein the plasma chamber includes: 
 a horizontal planar section positioned above the platen;    a vertical cylindrical section extending from the horizontal planar section; and    a top section coupled to the vertical cylindrical section.    
   
   
       12 . The apparatus of  claim 11 , wherein the horizontal planar section and vertical cylindrical section are dielectric, and the top section is conductive and grounded.  
   
   
       13 . The apparatus of  claim 12 , wherein the horizontal planar section and vertical cylindrical section are formed of a high purity ceramic material.  
   
   
       14 . The apparatus of  claim 13 , wherein the high purity ceramic material is >99.6% Al 2 O 3 , AlN, Yittria or YAG.  
   
   
       15 . The apparatus of  claim 12 , wherein the top section is formed of Al.  
   
   
       16 . The apparatus of  claim 11 , wherein the top section is liquid cooled.  
   
   
       17 . The apparatus of  claim 1 , further comprising a plasma igniter for introducing a strike gas into the plasma chamber to assist in igniting a plasma.  
   
   
       18 . The apparatus of  claim 1 , further comprising a gas source controller for maintaining a pressure of the plasma chamber at a predetermined value.  
   
   
       19 . The apparatus of  claim 1 , wherein the RF source operates at a low RF frequency.  
   
   
       20 . The apparatus of  claim 19 , wherein the low RF frequency is less than 27 MHz.  
   
   
       21 . The apparatus of  claim 19 , wherein the low RF frequency is 400 KHz, 2 MHz, 4 MHz or 13.56 Mhz.  
   
   
       22 . A method of plasma immersion ion implantation, the method comprising the steps of: 
 generating an ionic plasma by exposing a process gas to a radio frequency (RF) source via a first active coil;    tuning the ionic plasma by parasitically damping via a second parasitic coil that is not connected to any RF source; and    implanting a target using the ionic plasma by providing a negative voltage to the target.    
   
   
       23 . The method of  claim 22 , wherein the generating step further includes introducing a strike gas to the RF source.  
   
   
       24 . A plasma chamber comprising: 
 a horizontal planar dielectric section for positioning above a platen;    a vertical cylindrical dielectric section extending from the horizontal planar section; and    a liquid cooled top conductive section coupled to the vertical dielectric section.    
   
   
       25 . The plasma chamber of  claim 24 , wherein the top conductive section is grounded.  
   
   
       26 . The plasma chamber of  claim 24 , wherein the top conductive section is liquid cooled.  
   
   
       27 . The plasma chamber of  claim 24 , wherein the vertical dielectric section is configured to couple to, via a thermally conductive elastomer, a parasitic antenna that is not coupled to any radio frequency (RF) source.  
   
   
       28 . The plasma chamber of  claim 27 , wherein the parasitic antenna includes a plurality of turns with one end grounded.  
   
   
       29 . The plasma chamber of  claim 28 , further comprising means for adjusting a number of turns of the parasitic antenna providing a parasitic effect.  
   
   
       30 . The plasma chamber of  claim 27 , wherein the antenna is liquid cooled.  
   
   
       31 . The plasma chamber of  claim 24 , wherein the horizontal dielectric section is configured to support an active radio frequency antenna that is coupled to a radio frequency (RF) source.  
   
   
       32 . The plasma chamber of  claim 24 , further comprising a process gas inlet and a strike gas inlet.