Wafer chuck having thermal plate with interleaved heating and cooling elements

Abstract

A workpiece chuck includes a thermal plate assembly which includes both heating and cooling capability. The heating element can be a resistive heater in a coiled configuration disposed in a plane. The cooling can be performed via a cooling fluid circulated through cooling tubes which are also disposed in a coiled configuration in a plane. The plane of the heating element and the cooling tubes can be the same plane, and that plane can be a center plane of the thermal plate assembly. By locating the heating and cooling in the same plane, uniform heating and cooling are achieved. Also, by locating the heating element and cooling tubes in the center of the thermal plate, distortions such as doming and dishing in the thermal plate are eliminated such that the wafer can be held extremely flat on the chuck. The heating element and cooling tubes are coiled in an interleaved fashion to provide uniform heating and cooling while allowing them to simultaneously occupy the same plane.

1 . A thermal control apparatus for a workpiece chuck, the thermal control apparatus comprising: 
 a heating element disposed in a heating plane; and    a cooling element disposed in a cooling plane; wherein    the heating plane and the cooling plane are the same plane.    
   
   
       2 . The thermal control apparatus of  claim 1 , wherein the heating element comprises a resistive heating element in a coil configuration within the heating plane.  
   
   
       3 . The thermal control apparatus of  claim 1 , wherein the cooling element comprises at least one tube for circulating cooling fluid, the tube being configured in a coil configuration in the cooling plane.  
   
   
       4 . The thermal control apparatus of  claim 3 , wherein the heating element comprises a resistive heating element in a coil configuration within the heating plane.  
   
   
       5 . The thermal control apparatus of  claim 4 , wherein the heating element is electrically isolated from the thermal plate assembly.  
   
   
       6 . The thermal control apparatus of  claim 5 , wherein the isolation impedance is over 100 Gigohms.  
   
   
       7 . The thermal control apparatus of  claim 4 , wherein the resistive heating element and the tube are disposed in a plane in coil configurations interleaved with each other.  
   
   
       8 . The thermal control apparatus of  claim 4 , wherein the plane in which the resistive heating element and the tube are disposed is a center plane of the thermal control apparatus halfway between a top surface of the thermal control apparatus and a bottom surface of the thermal control apparatus.  
   
   
       9 . The thermal control apparatus of  claim 1 , wherein the heating plane and the cooling plane lie in a center plane of the thermal control apparatus halfway between a top surface of the thermal control apparatus and a bottom surface of the thermal control apparatus.  
   
   
       10 . The thermal control apparatus of  claim 1 , further comprising a housing enclosing the heating element and the cooling element, the housing being made from a cast metal.  
   
   
       11 . The thermal control apparatus of  claim 10 , wherein the metal comprises aluminum.  
   
   
       12 . The thermal control apparatus of  claim 10 , wherein the metal is pure aluminum.  
   
   
       13 . The thermal control apparatus of  claim 10 , wherein the metal is an alloy with low thermal distortion.  
   
   
       14 . The thermal control apparatus of  claim 1 , wherein the thermal control apparatus is a layer of the workpiece chuck.  
   
   
       15 . The thermal control apparatus of  claim 14 , wherein the heating element comprises a resistive heating element in a coil configuration within the heating plane.  
   
   
       16 . The thermal control apparatus of  claim 14 , wherein the cooling element comprises at least one tube for circulating cooling fluid, the tube being configured in a coil configuration in the cooling plane.  
   
   
       17 . The thermal control apparatus of  claim 16 , wherein the heating element comprises a resistive heating element in a coil configuration within the heating plane.  
   
   
       18 . The thermal control apparatus of  claim 17 , wherein the resistive heating element and the tube are disposed in a plane in coil configurations interleaved with each other.  
   
   
       19 . The thermal control apparatus of  claim 17 , wherein the plane in which the resistive heating element and the tube are disposed is a center plane of the thermal control apparatus halfway between a top surface of the thermal control apparatus and a bottom surface of the thermal control apparatus.  
   
   
       20 . The thermal control apparatus of  claim 14 , wherein the heating plane and the cooling plane lie in a center plane of the thermal control apparatus halfway between a top surface of the thermal control apparatus and a bottom surface of the thermal control apparatus.  
   
   
       21 . The thermal control apparatus of  claim 14 , further comprising a housing enclosing the heating element and the cooling element, the housing being made from a cast metal.  
   
   
       22 . The thermal control apparatus of  claim 21 , wherein the metal comprises aluminum.