SiNx-Submikrometerschichten – Parameteroptimierung –

SiN_x-submicrometer coatings – Optimization of the film properties – The influence of the deposition conditions on the properties of SiN_x-coatings was investigated. The characterized SiN_x-coatings were deposited by the help of reactive magnetron sputtering. Gas pressure and film thickness were varied. Scanning electron microscopic views of the cross sections show a columnar structure varying with the deposition parameters. The different structures are comparable to the known structure zone models. There is a transition from dense structures to open columnar structures with increasing gas pressure. The Microstructure of coatings also changes with increasing film thickness. Especially deposition conditions promoting shadowing effects lead to a large growth of the column diameter with increasing thickness. The intrinsic stresses and the ultramicrohardness of the coatings change with changing gas pressure, too. Dense structures have high intrinsic stresses and a high hardness while coarse columnar structures have low intrinsic stresses and a low hardness. The influence of the deposition parameters on wear behaviour and adhesion of the SiN_x-coatings was investigated by cavitation tests. Dense coatings with high intrinsic stresses show adhesion failures, and coatings with lower stresses and coarse columnar structures fail because of their lower intrinsic stability. Thus, there is an optimum gas pressure, at which the best properties are reached. It can be shown that with decreasing film thickness adhesion increases.