High temperature cathode for plasma etching

Abstract

The present invention generally is a cathode suitable for use in high temperature plasma etch applications. In one embodiment, the cathode includes a ceramic electrostatic chuck secured to a base. The base has cooling conduits formed therein. A rigid support ring is disposed between the chuck and the base, thereby maintaining the chuck and the base in a spaced-apart relation.

1 . A plasma processing cathode comprising:
 a base having cooling conduits formed therein;   a ceramic electrostatic chuck secured to the base; and   a rigid support ring disposed between the electrostatic chuck and the base, the support ring maintaining the electrostatic chuck to the base in a spaced-apart relation.   
   
   
       2 . The cathode of  claim 1  further comprising a gas distribution ring disposed between the base and chuck. 
   
   
       3 . The cathode of  claim 2  further comprising:
 a gas passage formed through the base; and   a gas feed formed through the electrostatic chuck, wherein the passage and feed are not aligned but fluidly coupled through the gas distribution ring to define a gas delivery path, wherein gas delivery path extends through the gas distribution ring.   
   
   
       4 . The cathode of  claim 3  further comprising:
 a ceramic baffle disk disposed in the gas delivery path.   
   
   
       5 . The cathode of  claim 4 , wherein the gas distribution ring further comprises:
 a bore having the baffle disk disposed therein.   
   
   
       6 . The cathode of  claim 1  further comprising:
 a gas passage formed through the base;   a gas feed formed through the electrostatic chuck, wherein the passage and feed are not aligned but fluidly coupled through the gas distribution ring to define a gas delivery path; and   a ceramic baffle disk disposed in the gas delivery path.   
   
   
       7 . The cathode of  claim 1  further comprising:
 a flat annular spreader plate disposed in a gap defined between the electrostatic chuck and the base.   
   
   
       8 . The cathode of  claim 7 , wherein the annular spreader plate is in contact with the base and spaced-apart from the electrostatic chuck. 
   
   
       9 . The cathode of  claim 1  further comprising:
 a clamp ring securing the electrostatic chuck to the base, the clamp ring having at least two thermal chokes disposed in series between portions of the clamp ring touching the electrostatic chuck and the base.   
   
   
       10 . The cathode of  claim 1  further comprising:
 a stem coupled to the electrostatic chuck and extending through the base;   a sleeve disposed through the stem, wherein a first gap defined between the stem and base is greater than a second gap defined between the stem and sleeve; and   a seal disposed between a lower end of the stem and the base, the seal sealing the first gap.   
   
   
       11 . The cathode of  claim 10 , wherein the base further comprises:
 a channel coupling the stem coupled to the electrostatic chuck and extending through the base, the channel venting the first gap through the base.   
   
   
       12 . A plasma processing cathode comprising:
 a base having cooling conduits formed therein;   a ceramic electrostatic chuck disposed on the base, the electrostatic chuck having a plurality of gas feeds extending from a bottom surface of the electrostatic chuck facing the base to a top surface the electrostatic chuck;   a rigid support ring disposed between the electrostatic chuck and the base, the support ring maintaining the bottom of the electrostatic chuck and the base in a spaced-apart relation;   a fluid distribution ring disposed between the base and the electrostatic chuck, a bottom of the fluid distribution ring spaced from the base to define an annular channel, the fluid distribution ring having a plurality of gas passages configured to direct gas through the fluid distribution ring from the channel to the electrostatic chuck; and   ceramic baffles disposed in the gas passages.   
   
   
       13 . The cathode of  claim 12 , wherein at least one of the ceramic baffles further comprises:
 a disk-like body having upper and lower surfaces; and   cross channels formed in the upper and lower surfaces.   
   
   
       14 . The cathode of  claim 12 , wherein at least one of the ceramic baffle further comprises:
 a disk-like body having a perimeter; and   notches formed in the perimeter.   
   
   
       15 . The cathode of  claim 12  further comprising:
 an annular spreader plate disposed in a gap defined between the electrostatic chuck and the base, wherein the annular spreader plate is in contact with the base and spaced-apart from the electrostatic chuck.   
   
   
       16 . The cathode of  claim 12  further comprising:
 a stem coupled to the electrostatic chuck and extending through the base;   a sleeve disposed through the stem, wherein a first gap defined between the stem and base is greater than a second gap defined between the stem and sleeve; and   a seal disposed between a lower end of the stem and the base, the seal sealing the first gap.   
   
   
       17 . A plasma processing cathode comprising:
 a base having cooling conduits formed therein;   a ceramic electrostatic chuck secured to a top surface of the base;   a rigid support ring disposed between the electrostatic chuck and the base, the support ring maintaining a lower surface of the electrostatic chuck spaced-apart from the top surface of the base;   a flat annular spreader plate disposed radially inward of the support ring in a gap defined between the lower surface of the electrostatic chuck and the upper surface of the base; and   a seal providing seal between the electrostatic chuck and the base outward of the spreader plate, the seal sealingly permitting radial movement of the electrostatic chuck relative to the plate.   
   
   
       18 . The cathode of  claim 17  further comprising:
 a gas passage formed through the base;   a gas feed formed through the electrostatic chuck, wherein the passage and feed are not aligned but fluidly coupled through the gas distribution ring to define a gas delivery path, and   a ceramic baffle disk disposed in the gas delivery path.   
   
   
       19 . The cathode of  claim 17  further comprising:
 a stem coupled to the electrostatic chuck and extending through a cylinder in the base, an inside diameter of the cylinder configured to maintain a first gap between the stem and the base;   a sleeve disposed through the stem, wherein the first gap is greater than a second gap defined between the stem and sleeve; and   a seal disposed between a lower end of the stem and the base, the seal sealing the first gap.   
   
   
       20 . The cathode of  claim 17  further comprising:
 a fluid distribution ring disposed between the base and the electrostatic chuck, a bottom of the fluid distribution ring spaced from the base to define an annular channel, the fluid distribution ring comprising:   a stepped bore formed on a top surface facing the electrostatic chuck, the bore receiving the baffle therein;   a gas passage having a first end breaking into the stepped bore and a second end breaking through the bottom of the fluid distribution ring and exposed to the annular channel.