Rate control for vacuum co-deposition of thin film cermets

In vacuum co-deposition of thin cermet resistor films it has been found that the electrical properties are sensitive to deposition rates, thus needing a two-channel rate controller. The requirements of such an instrument are outlined and alternative systems are briefly compared, resulting in the choice of a digital data processor and step feedback control. A detailed description of the logic and circuit design of the instrument built is presented along with a brief discussion of the operational limitations and difficulties. Possible extensions of the instrument to other needs are considered.