Method and apparatus for electron beam processing of substrates

摘要

Embodiments of the invention generally provide an electron beam substrate processing system. In one embodiment, the present invention provides an electron beam substrate processing system where a spindle shaft used to rotate substrates during processing includes two encoder wheels. One encoder wheel is configured to provide a rotational speed data signal to a rotational speed control system. Another encoder wheel is configured to provide a pattern generator clock signal at a higher frequency than the rotational speed data signal to a pattern generator. In one embodiment of the present invention, at least one of the encoder wheels is positioned adjacent the substrate to minimize torsional and differential movements between the at least one encoder wheel and the substrate.