A substrate processing system including a processing chamber, a substrate holder configured to hold and rotate a substrate about an axis perpendicular to a working surface of the substrate; an electron emitter adapted to emit a first electron beam directed at a first surface of a peripheral region of the substrate, the first electron beam having a first beam energy and a first beam current sufficient to vaporize material from the first surface of the peripheral region of the substrate; an airflow system configured to direct a flow of gas across the working surface of the substrate; and an exhaust system configured to collect the gas comprising the material vaporized from the peripheral region.