| abstract |
A gas distribution system for semiconductor processing includes a contoured surface to achieve a desired gas distribution on the backside of a showerhead. The system can include one or more gas supplies opening into a plenum between a baffle plate and a temperature-controlled support member. The baffle plate can have a nonuniform thickness and geometry-controlled openings to achieve a desired gas distribution. In one arrangement the baffle plate is conical in shape with uniform diameter holes extending different distances through the baffle plate to achieve a uniform pressure of gas through outlets in a planar bottom surface of the baffle plate. In another arrangement, the holes have progressively larger diameters in a direction away from the location of the centrally located gas supply outlet. The shape of the baffle plate and/or configuration of the holes can be designed to achieve a desired gas pressure distribution. |