Method and apparatus for clearing short-circuited, high-voltage cathodes in a sputtering chamber

摘要

A method and apparatus for vaporizing any flakes of sputtering target material which short circuit high voltage cathodes during the sputtering of a coating on a substrate such as nuclear fuel pellet positioned in the vacuum chamber of a sputtering device. A separate low voltage, high current auxiliary power source is used to evaporate the shorting flakes. The present method and apparatus reduces the process recovery time in the event of a shorting flake from as long as 6 hours down to as little as 5 minutes without compromising the purity of the sputtered coating. The auxiliary power source may be an ac source which is preferably connected in series with the shorting flake so that current from the ac source will cease as soon as the shorting flake is evaporated. A ballast and/or short circuit indicating device may also be provided in series with the ac source in order to limit the ac current and in order to indicate the presence of shorting flakes. The system may be automated to automatically determine conditions indicative of the existence of a shorting flake and to thereupon automatically initiate a shorting flake evaporation cycle.