This result is related to large-area magnetron sputtering technology using cylindrical, rotatable targets. One of the major issues in large area coating technology is the deposition of thin films at a very high homogeneity, e. g. for certain multiple-Ag based solar control coatings for architectural glazing, film thickness deviations of less than 1% are demanded.

It is furthermore known, that - due to target erosion - the process characteristics of a magnetron sputtering source are gradually changing throughout its lifetime. Thus, regular calibration is required to maintain stable process conditions within a production campaign.

To overcome these problems we present a new coating technology concept for a cylindrical rotatable sputtering source with a build-in measurement equipment for the target erosion rate. This measurement equipment is realized as a secondary, planar D.C. sputtering cathode operating under pure Argon at a defined sputtering rate.

The material of the secondary cathode is partially removed by the sputtering process of the primary cathode and afterwards the remaining fraction of the secondary material is measured by X-ray fluorescence. By maintaining a constant X-ray fluorescence signal the erosion rate of the magnetron can be kept on a constant level.