Process and apparatus for controlling the reactive deposit of coatings on substrates by means of magnetron cathodes

摘要

A reaction gas is admitted in the immediate vicinity of a target on the cathode and a plasma is generated between the target and a substrate to be coated. The intensity of the spectral line of a target material is measured, and is used to provide a first signal with a relatively short time constant to a controller via a first control circuit. A property of the finished coating is sensed after the substrate leaves the coating zone, and is used to provide a second signal with a relatively long time constant to the controller via a second control circuit. The controller uses the combined signals to regulate the admission of the reaction gas so that a pre-established property of the finished coating is kept substantially constant.