Magnetron sputter deposition: Linking discharge voltage with target properties

The discharge voltage is perhaps the most accessible parameter of the magnetron sputter deposition process. As its value can be easily monitored, research reports generally contain its value. Nevertheless, the interpretation of the discharge voltage and/or its behavior, especially during reactive magnetron sputtering, is less straightforward. To understand its behavior, it is necessary to look into the details of the magnetron discharge, the processes occurring at the cathode (or target) and the influence of the important discharge parameters such as discharge current, magnet configuration, and discharge gas pressure. The influence of these parameters can be partially understood from a general formula. This formula, based on the original work of Thornton, shows that the discharge voltage behavior during reactive magnetron sputtering finds its origin in the formation of a compound layer on the target. The discharge voltage behavior depends strongly on the material properties of the compound layer which is formed.