Abstract: A method of processing a substrate 25 comprises placing the substrate 25 in a process zone and introducing process gas into the process zone through a gas distributor 35 through which energized gas may be introduced into the process zone. The method also comprises detecting radiation transmitted through the gas distributor 25, which may comprise a monocrystalline material portion. In another version, the gas distributor 25 comprises a thermal expansion isolator.

Abstract: A process chamber 15 for processing a semiconductor substrate comprising a support 20 for holding the substrate, a gas distributor 35 for distributing process gas into the process chamber, a gas energizer for energizing the process gas, and an exhaust 60 for exhausting process gas from the process chamber. The gas distributor 35 comprises monocrystalline material that provides increased erosion resistance and withstands high temperatures. Preferably, a thermal expansion isolator 115 supports the gas distributor 35 to allow portions of the gas distributor 35 to thermally expand different amounts. The gas distributor 35 can also comprise a transparent window 170 of solid material that transmits an light beam therethrough. Also, the gas distributor 35 can comprise a transparent portion facing the substrate 25 that allows light emissions from the energized gas to pass through without being reflected back onto the substrate.