Method for dechucking a substrate

Abstract

A substrate support assembly and method for dechucking a substrate is provided. In one embodiment, a support assembly includes a substrate support having a support surface, a first set of lift pins and one or more other lift pins movably disposed through the substrate support. The first set of lift pins and the one or more lift pins project from the support surface when the pins are in an actuated position. When in the actuated position, the first set of lift pins project a longer distance from the support surface than the one or more other lift pins. In another aspect of the invention, a method for dechucking a substrate from a substrate support is provided. In one embodiment, the method includes the steps of projecting a first set of lift pins a first distance above a surface of a substrate support, and projecting a second set of lift pins a second distance above the surface of the substrate support that is less than the first distance.

1 . An apparatus for supporting a substrate, comprising: 
 a support assembly having a support surface;    a first set of lift pins comprising at least two lift pins having a flared end adapted to contact the substrate, the first set of lift pins disposed in and movable relative to the support assembly and extendable upwardly through the support assembly to a first distance above the support surface; and    a second set of lift pins comprising at least two lift pins having a flared end adapted to contact the substrate, the second set of lift pins disposed in and movable relative to the support assembly and extendable upwardly simultaneously with the first set of lift pins through the support assembly to a second distance above the support surface, wherein the second distance is less than the first distance and wherein the two sets of lift pins are adapted to simultaneously contact the substrate disposed on the support surface while the center of the substrate is bowed downwardly.    
   
   
       2 . The apparatus of  claim 1 , wherein the first set of lift pins have a length greater than a length of the second set of lift pins.  
   
   
       3 . The apparatus of  claim 1 , wherein the second set of lift pins are positioned radially inwards of the first set of lift pins.  
   
   
       4 . The apparatus of  claim 1 , wherein the first set of lift pins and the second set of lift pins comprise a ceramic material.  
   
   
       5 . The apparatus of  claim 1 , wherein the first set of lift pins are positioned on a perimeter of the support assembly.  
   
   
       6 . The apparatus of  claim 1 , wherein the first set of lift pins and the second set of lift pins simultaneously contact a lift surface of the apparatus when the center of the substrate is bowed downwardly.  
   
   
       7 . The apparatus of  claim 1 , wherein the support assembly is coupled to an actuator adapted to move the support assembly vertically and the first set of lift pins and the second set of lift pins are extended and retracted based on the vertical position of the support assembly.  
   
   
       8 . An apparatus for supporting a substrate in a chamber having a lid, sidewalls, and a bottom, the apparatus comprising: 
 a support assembly having a support surface and an underside opposite the support surface;    a first set of lift pins disposed in and movable relative to the support assembly and having a first end for supporting the substrate disposed proximate the support surface and a second end extending beyond the underside; and    a second set of lift pins disposed in and movable relative to the support assembly and having a first end for supporting the substrate disposed proximate the support surface and a second end extending beyond the underside, wherein the support assembly is adapted to move vertically within the chamber to displace the first and second sets of lift pins to a position where the first end of the first set of lift pins extends a first distance from the support surface and the first end of the second set of lift pins extends a second distance from the support surface, wherein the first distance is greater than the second distance.    
   
   
       9 . The apparatus of  claim 8 , wherein the second set of lift pins are positioned radially inwards of the first set of lift pins.  
   
   
       10 . The apparatus of  claim 8 , wherein the first end of the first set of lift pins and the first end of the second set of lift pins comprises a flared head adapted to contact the substrate.  
   
   
       11 . The apparatus of  claim 8 , wherein the second set of lift pins further comprises two lift pins positioned opposite a center of the support assembly.  
   
   
       12 . The apparatus of  claim 8 , wherein the first set of lift pins comprises at least three or more lift pins.  
   
   
       13 . The apparatus of  claim 8 , wherein the first set of lift pins and the second set of lift pins comprise a ceramic material.  
   
   
       14 . The apparatus of  claim 8 , wherein the support assembly further comprise comprises: 
 four sides bounding the support surface, wherein a respective pair of lift pins are positioned proximate each side of the support assembly.    
   
   
       15 . The apparatus of  claim 8 , wherein the first set of lift pins have a first length that is longer than a second length of the second set of lift pins.  
   
   
       16 . The apparatus of  claim 15 , wherein the first length is at least 2 mm longer than the second length.  
   
   
       17 . The apparatus of  claim 8 , wherein the first and second sets of lift pins, when respectively extended the first and second distances, simultaneously support the substrate.  
   
   
       18 . The apparatus of  claim 8 , wherein the first set of lift pins is adapted to extend to a third distance greater than the first distance and to support a substrate in a spaced-apart relation to the support surface while the second set of extended lift pins do not contact the substrate.  
   
   
       19 . An apparatus for supporting a substrate in a chamber having a lid, sidewalls, and a bottom, the apparatus comprising: 
 a rectangular support assembly having a support surface and an underside opposite the support surface;    a first set of lift pins movably disposed through a perimeter of the support assembly and movable relative to the support assembly, each of the first set of lift pins having a flared head for supporting the substrate disposed proximate the support surface and a second end extending beyond the underside; and    a second set of lift pins movably disposed through the support assembly radially inwards of the first set of lift pins and movable relative to the support assembly, each of the second set of lift pins having a flared head for supporting the substrate disposed proximate the support surface and a second end extending beyond the underside, wherein the support assembly is adapted to move vertically within the chamber to displace the first and second sets of lift pins to a position where the first end of the first set of lift pins extends a first distance from the support surface and the first end of the second set of lift pins extends a second distance from the support surface, wherein the first distance is greater than the second distance and the first set and second set of lift pins comprise a ceramic material.    
   
   
       20 . The apparatus of  claim 19 , wherein the first set of lift pins comprise at least eight lift pins.