Matched coefficient of thermal expansion for an electrostatic chuck

摘要

An apparatus and method are provided for selecting materials for forming an electrostatic clamp. The electrostatic clamp has a backing plate having a first coefficient of thermal expansion, wherein the backing plate provides structural support and rigidity to the electrostatic clamp. The electrostatic clamp further has a clamping plate having a clamping surface associated with contact with a workpiece, wherein the clamping plate has a second coefficient of thermal expansion associated therewith. The clamping plate is bonded, attached or grown to the backing plate, wherein minimal deflection of the clamping plate is evident across a predetermined temperature range. The first coefficient of thermal expansion and second coefficient of thermal expansion, for example, are substantially similar, and vary by no greater than a factor of three.

主权项

1. An electrostatic clamp for selectively maintaining a position of a workpiece, the electrostatic clamp comprising:
a backing plate for providing structural support and rigidity to the electrostatic clamp, wherein the backing plate has a first coefficient of thermal expansion associated therewith, wherein the backing plate consists of a metal, therein defining a metallic backing plate; and a clamping plate having a clamping surface configured to contact the workpiece, wherein the clamping plate has a second coefficient of thermal expansion associated therewith, wherein the clamping plate comprises a ceramic material, therein defining a ceramic clamping plate, wherein the clamping plate is bonded to the backing plate, and wherein the first coefficient of thermal expansion and second coefficient of thermal expansion are minimized, with a maximum difference determined by the geometry of the electrostatic clamp.