RESIDUAL-STRESSES IN NITRIDE HARD COATINGS PREPARED BY MAGNETRON SPUTTERING AND ARE EVAPORATION

Nitride hard coatings such as TiN or (Ti,Al)N produced by magnetron sp uttering and are evaporation processes are characterized by large comp ressive stresses up to - 15 GPa. In the case of magnetron sputtering t he highest stress values can be observed at high bias voltages and low substrate temperatures. Coatings produced by are evaporation, exhibit high compressive stresses even in the case of no bias voltage. The st resses are also influenced by substrate temperatures. In both cases th e growing layer is bombarded with accelerated particles. However, ther e are differences in the kinds of particles. We assume that in the cas e of sputtering Ar ions and in the case of are evaporation metal ions with high kinetic energy push nitrogen atoms from regular lattice site s into tetrahedral holes of the rock salt type lattice and occupy the previous nitrogen sites. During are evaporation the formation of vacan cies (Frenkel defects) is also possible. Both effects, the incorporati on of argon or metal atoms on nitrogen sites and the nitrogen intersti tials, produce high compressive residual stresses. During annealing in terstitial nitrogen diffuses to inner boundaries or to the surface. Hi gh residual stresses are decreased.