Patent ID: 8544483

Claim:
An apparatus for processing a microelectronic workpiece, comprising: a) a processing chamber including a workpiece support that is positioned within the processing chamber and onto which the workpiece is to be positioned during a process; b) a barrier plate comprising: i) an outer periphery; ii) an inside surface that overlies and covers the workpiece support, wherein a support surface of the workpiece support and the inside surface of the barrier plate provide a controlled fluid flow channel between the inside surface of the barrier plate and the workpiece support, wherein the flow channel has an outer periphery for fluid to flow in a radially outward direction relative to the inside surface of the barrier plate and the workpiece support; iii) an outside surface opposite the inside surface; and iv) an inner peripheral surface defining a pathway that provides fluid communication between the space adjacent to the outside surface and the space adjacent to the inside surface, wherein the pathway is configured so that fluid can flow through the barrier plate by way of the pathway and be introduced toward the workpiece support; and c) a plurality of nested baffles, wherein at least one nested baffle is independently moveable relative to one or more other nested baffles in a manner effective to selectively open and close at least one exhaust duct pathway associated with the at least one independently moveable nested baffle, wherein independent movement of the at least one nested baffle to close the at least one associated duct pathway reduces the volume occupied by the associated duct pathway, wherein independent movement of the at least one nested baffle to open the at least one associated duct pathway enlarges the volume occupied by the associated duct pathway, and wherein at least two nested baffles each have a flow control surface having an inner periphery that is positionable radially proximal to the outer periphery of the inside surface of the barrier plate to receive fluid flow from the outer periphery of the flow channel so that the flow control surface of a selected nested baffle guides fluid flow from the outer periphery of the flow channel into an open exhaust duct pathway associated with the selected nested baffle.