Temperature controlled substrate support assembly

Abstract

A temperature controlled substrate support assembly used for processing a substrate in a vacuum chamber of a semiconductor processing apparatus. The substrate support assembly comprises a top plate for supporting the substrate. A base plate is disposed below the top plate wherein the base plate comprises a cavity in an upper surface of the base plate. A cover plate is disposed between the top plate and the base plate. At least one thermoelectric module is in the cavity in the upper surface of the base plate wherein the at least one thermoelectric module is in thermal contact with the top plate and the base plate, and the at least one thermoelectric module is maintained at atmospheric pressure.

What is claimed is: 
     
         1 . A temperature controlled substrate support assembly for processing a substrate in a vacuum chamber of a semiconductor processing apparatus comprising:
 a top plate configured to support the substrate;   a base plate disposed below the top plate wherein the base plate comprises a cavity in an upper surface of the base plate;   a cover plate enclosing the cavity and disposed between the top plate and the base plate; and   at least one thermoelectric module in the cavity in the upper surface of the base plate wherein the at least one thermoelectric module is in thermal contact with the top plate and the base plate, and the at least one thermoelectric module is maintained at atmospheric pressure.   
     
     
         2 . The temperature controlled substrate support assembly of  claim 1 , wherein (a) the at least one thermoelectric module comprises alternating p-type and n-type semiconductor elements which are in electrical contact and which operate according to the Peltier effect; (b) upwardly extending bosses are located in the cavity in the upper surface of the base plate; and/or (c) electrically insulating layers cover respective upper and lower surfaces of the at least one thermoelectric module. 
     
     
         3 . The temperature controlled substrate support assembly of  claim 2 , wherein (a) the electrically insulating layers on the upper and lower surface of the at least one thermoelectric module are bonded to the cover plate and the base plate with an adhesive; (b) the electrically insulating layer on the upper surface of the at least one thermoelectric module forms a vacuum seal with the upwardly extending bosses and an outer wall on the upper surface of the base plate; and/or (c) each upwardly extending boss of the base plate includes a vertically extending hole configured to receive a lift pin and/or deliver backside helium gas to the top plate surface. 
     
     
         4 . The temperature controlled substrate support assembly of  claim 1 , wherein (a) the top plate comprises an electrostatic chuck having at least one electrostatic electrode embedded in a layer of dielectric material; and/or (b) the base plate comprises fluid channels through which a temperature controlled fluid circulates. 
     
     
         5 . The temperature controlled substrate support assembly of  claim 1 , wherein the lower surface of the at least one thermoelectric module is bonded to an upper surface of the cavity in the base plate with solder or a low melting point alloy. 
     
     
         6 . The temperature controlled substrate support assembly of  claim 1 , wherein at least two thermoelectric modules are arranged in the cavity such that each thermoelectric module in the cavity forms a respective temperature control zone on the top plate. 
     
     
         7 . The temperature controlled substrate support assembly of  claim 6 , wherein each thermoelectric module forms a respective temperature control zone on the top plate wherein the temperature control zones include a center temperature control zone with one or more surrounding temperature control zones forming an annular formation, a grid formation, a radial formation, an azimuthal formation, a polar formation, or a nonpolar formation. 
     
     
         8 . The temperature controlled substrate support assembly of  claim 1 , further comprising a plurality of sensors corresponding with temperature control zones across the top plate, each sensor operable to output a signal representative of the temperature of each respective temperature control zone. 
     
     
         9 . The temperature controlled substrate support assembly of  claim 8 , further comprising a controller for receiving a signal from each sensor and for adjusting the power delivered to each thermoelectric module of each temperature control zone based on a set point or a feedback control loop for each temperature control zone. 
     
     
         10 . The temperature controlled substrate support assembly of  claim 1 , wherein (a) the cover plate comprises an inner cover plate and an outer annular cover plate; and/or (b) the cover plate is formed from aluminum, copper, pryolytic graphite, a ceramic material, or aluminum coated pyrolytic graphite. 
     
     
         11 . The temperature controlled substrate support assembly of  claim 10 , wherein the cover plate has a thickness of about 0.5 to 4 millimeters. 
     
     
         12 . The temperature controlled substrate support assembly of  claim 2 , wherein the cover plate comprises downwardly extending bosses corresponding to the upwardly extending bosses of the base plate wherein the downwardly extending bosses and the upwardly extending bosses have aligned holes configured to receive lift pins and/or deliver backside helium gas and the upwardly extending bosses and corresponding downwardly extended bosses are configured to provide an RF current path within the temperature controlled substrate support assembly. 
     
     
         13 . The temperature controlled substrate support assembly of  claim 1 , wherein the base plate includes heat transfer pipes configured to increase the thermal conductance between the at least one thermoelectric module in the cavity and fluid channels included in the base plate through which a temperature controlled fluid circulates; and wherein (a) the base plate includes a heat transfer plate disposed above the heat transfer pipes and below the at least one thermoelectric module; or (b) the base plate includes a heat transfer sheet disposed in the cavity wherein each heat transfer pipe is attached to the heat transfer sheet. 
     
     
         14 . The temperature controlled substrate support assembly of  claim 13 , wherein the heat transfer pipes include a fluid selected from the group consisting of water, ammonia, and ethanol. 
     
     
         15 . The temperature controlled substrate support assembly of  claim 13 , wherein (a) the heat transfer plate is formed of copper; or (b) the heat transfer sheet is formed of copper, aluminum, pryolytic graphite, or aluminum coated pyrolytic graphite. 
     
     
         16 . A method of manufacturing a substrate support assembly for controlling a temperature of a substrate during plasma processing comprising:
 bonding a lower surface of at least one thermoelectric module to a surface within a cavity in an upper surface of a base plate;   bonding a lower surface of an upper electrically insulating layer included on an upper surface of the at least one thermoelectric module to a cylindrical wall defining the cavity in the upper surface of the base plate and to upwardly extending bosses within the cavity, wherein the bonded lower surface of the upper electrically insulating layer forms a vacuum seal with the cylindrical wall and the upwardly extending bosses and the cavity is open to the atmosphere through a surface of the cavity within the upper surface of the base plate; and   bonding an upper surface of the upper electrically insulating layer to a cover plate.   
     
     
         17 . The method of  claim 16 , wherein (a) the lower surface of the at least one thermoelectric module is bonded to the surface within the cavity in the upper surface of the base plate with soldering or a low melting point alloy; or (b) the lower surface of the at least one thermoelectric module is bonded to a lower electrically insulating layer, and a lower surface of the lower electrically insulating layer is bonded to the surface within the cavity in the upper surface of the base plate. 
     
     
         18 . The method of  claim 16 , further comprising (a) drilling vertical holes in a surface of the base plate and inserting a heat transfer pipe in each drilled hole in the base plate, wherein an upper surface of each heat transfer pipe is flush with the surface of the base plate wherein each hole is drilled; and/or (b) installing a heat transfer plate in the substrate support assembly wherein the heat transfer plate is disposed above the heat transfer pipes and below the at least one thermoelectric module, the heat transfer plate configured to uniformly distribute heat among the plurality of thermoelectric devices and the heat transfer pipes. 
     
     
         19 . A method of processing a substrate in a semiconductor processing system comprising the temperature controlled substrate support assembly of  claim 1  and a vacuum processing chamber enclosing the substrate support assembly, the method comprising the steps of:
 supplying current to the at least one thermoelectric module in heat transfer contact with the top plate to control the temperature of one or more zones across the top plate surface; and 
 controlling the current supplied to the at least one thermoelectric module so as to control the temperature across the top plate surface and to provide a desired temperature distribution across the substrate during processing of the substrate. 
 
     
     
         20 . The method of  claim 19 , wherein the top plate further comprises at least one electrostatic electrode embedded therein and the substrate comprises a wafer, the processing comprising plasma etching or chemical vapor deposition.