Improvements in or relating to electrostatic chucks

摘要

An electrostatic chuck (20) for holding a substrate (40) in a process chamber (50) comprises a base (25) supporting a resilient insulator (30). The insulator (30) comprises (i) an electrode (35) embedded therein; (ii) a top surface (34) with a peripheral edge (32); and (iii) cooling grooves (45) for holding coolant in the top surface (34), the tips (125) of the cooling grooves (45) and the peripheral edge (32) of the insulator (30) defining an edge gap (130) having a width w. The width w of the edge gap (130) is sized sufficiently small that the coolant in the grooves (45) cools the perimeter (120) of the substrate (40) held on the chuck (20). The insulator (30) is sufficiently thick that when a substrate (40) is electrostatically held on the chuck (20) and coolant is held in the cooling grooves (45), the insulator (30) in the edge gap (130) resiliently conforms to the substrate (40) so that substantially no coolant leaks out from the tips (125) of the cooling grooves (45). Preferably, the coolant grooves (45) do not cut into the electrode (35). Preferably, an edge barrier (140) is provided around a collar ledge (150) of the base (25) for forming a seal between the substrate (40) and the base (25) of the chuck (20), to reduce erosion of the insulator (30) in the process chamber (50). <IMAGE> <IMAGE>