Substrate support with multiple embedded electrodes

Abstract

A method and apparatus for biasing regions of a substrate in a plasma-assisted processing chamber are provided. Biasing of the substrate, or regions thereof, increases the potential difference between the substrate and a plasma formed in the processing chamber thereby accelerating ions from the plasma towards the active surfaces of the substrate regions. A plurality of bias electrodes herein are spatially arranged across the substrate support in a pattern that is advantageous for managing uniformity of processing results across the substrate.

1 . A substrate processing system comprising a substrate support assembly, the substrate support assembly comprising:
 a metal base having a substrate support disposed thereon, the substrate support comprising a plurality of electrodes, wherein
 each of the plurality of electrodes is spaced apart from a substrate supporting surface of the substrate support by a first layer of dielectric material, 
 the plurality of electrodes are spaced apart from the metal base by a second layer of dielectric material, 
 each of the plurality of electrodes is isolated from a different one of the plurality of electrodes by a portion of dielectric material, 
 a first electrode and a second electrode of the plurality of electrodes are each electrically coupled to a voltage source of a pulsed DC bias system, 
 the pulsed DC bias system is configured to simultaneously deliver a first pulsed DC voltage to the first electrode and a second pulsed DC voltage to the second electrode, 
 the second electrode of the plurality of electrodes is disposed radially outward from and at least partially surrounds the first electrode, and 
 one of the plurality of electrodes is coupled to a chucking power supply for electrically clamping a substrate to the substrate supporting surface of the substrate support. 
   
     
     
         2 . The substrate processing system of  claim 1 , wherein the pulsed DC bias system is configured to adjust one or more characteristics of the first pulsed DC voltage relative to one or more characteristics of the second pulsed DC voltage. 
     
     
         3 . The substrate processing system of  claim 2 , wherein the one or more characteristics of the first and second pulsed DC voltages include pulse frequency, duty cycle, polarity, pulse duration, or a combination thereof. 
     
     
         4 . The substrate processing system of  claim 2 , further comprising an RF power supply for forming a capacitively coupled plasma in a processing volume of the substrate processing system. 
     
     
         5 . The substrate processing system of  claim 1 , wherein the first layer of dielectric material has a thickness between about 5 μm and about 300 μm. 
     
     
         6 . The substrate processing system of  claim 1 , wherein the one of the plurality of electrodes that is coupled to the chucking power supply comprises a metal mesh. 
     
     
         7 . The substrate processing system of  claim 1 , wherein the first electrode and the second electrode are concentrically disposed about a center of the substrate supporting surface of the substrate support. 
     
     
         8 . The substrate processing system of  claim 7 , wherein the first electrode has a substantially circular shape in a plane parallel to the substrate supporting surface. 
     
     
         9 . The substrate processing system of  claim 7 , wherein the second electrode is disposed proximate to a circumferential edge of the substrate support. 
     
     
         10 . The substrate processing system of  claim 7 , wherein
 the substrate supporting surface comprises a plurality of protrusions, and   one or more gas conduits formed through the substrate support are in fluid communication with a space at the substrate supporting surface that is formed between plurality of protrusions.   
     
     
         11 . The substrate processing system of  claim 10 , wherein the one or more gas conduits are fluidly coupled to an inert gas source. 
     
     
         12 . The substrate processing system of  claim 11 , wherein one or more fluid conduits formed in the metal base are fluidly coupled to a coolant source. 
     
     
         13 . The substrate processing system of  claim 12 , wherein the substrate support is thermally coupled to the metal base by an adhesive layer interposed therebetween. 
     
     
         14 . The substrate processing system of  claim 1 , wherein the voltage source comprises a high voltage DC power supply and one or more first switches for converting a static DC voltage from the high voltage DC power supply to the first pulsed DC voltage. 
     
     
         15 . A method for processing a substrate, comprising:
 (a) positioning the substrate on a substrate support disposed in a processing volume, the substrate support comprising a plurality of electrodes, wherein
 the substrate support is disposed on a metal base, 
 each of the plurality of electrodes is spaced apart from a substrate supporting surface of the substrate support by a first layer of dielectric material, 
 the plurality of electrodes are spaced apart from the metal base by a second layer of dielectric material, 
 a first electrode and a second electrode of the plurality of electrodes are each electrically coupled to a voltage source of a pulsed DC bias system, and 
 the second electrode of the plurality of electrodes at least partially surrounds a portion of the first electrode; 
   (b) forming a plasma within the processing volume;   (c) applying a chucking voltage to one of the plurality of electrodes to electrically clamp the substrate to the substrate support; and   (d) applying, by use of the pulsed DC bias system, a first pulsed DC voltage to the first electrode and a second pulsed DC voltage to the second electrode.   
     
     
         16 . The method of  claim 15 , further comprising:
 (e) adjusting one or more characteristics of the first pulsed DC voltage relative to one or more characteristics of the second pulsed DC voltage.   
     
     
         17 . The method of  claim 16 , wherein (e) adjusting one or more characteristics of the first pulsed DC voltage relative to the one or more characteristics of the second pulsed DC voltage comprises changing one or more of a pulse frequency, duty cycle, polarity, or a pulse duration of the first pulsed DC voltage, the second pulsed DC voltage, or both. 
     
     
         18 . The method of  claim 15 , wherein the plasma is formed through capacitively coupling an RF power to a processing gas disposed in the processing volume. 
     
     
         19 . The method of  claim 15 , wherein the first electrode and the second electrode are concentrically disposed about a center of the substrate supporting surface. 
     
     
         20 . The method of  claim 19 , wherein the second electrode is disposed proximate to a circumferential edge of the substrate support.