A method of processing a workpiece includes introducing an optical
absorber material precursor gas into a chamber containing the workpiece,
generating an RF oscillating toroidal plasma current in a reentrant path
that includes a process zone overlying the workpiece by applying RF
source power, so as to deposit a layer of an optical absorber material on
the workpiece, and exposing the workpiece to optical radiation that is at
least partially absorbed in the optical absorber layer.