Mask etch plasma reactor having an array of optical sensors viewing the workpiece backside and a tunable element controlled in response to the optical sensors

摘要

A plasma reactor has an array of passages extending through its workpiece support pedestal from a bottom thereof that forms a two-dimensional array of openings in the support surface. The reactor further includes a plurality of optical fibers, each fiber extending through a respective one of the passages. Optical sensing apparatus is coupled to the output ends of the optical fibers and is responsive in the range of wavelengths. The reactor further includes a tunable element capable of changing a two-dimensional etch rate distribution across the surface of a workpiece supported on the pedestal, and a process controller connected to receive information from the optical sensing apparatus and to transmit control commands to the tunable element.