Invited Paper SE-WeM9
Stress and Strain in Polycrystalline Thin Films

Wednesday, October 22, 2008, 10:40 am, Room 204

Polycrystalline thin films on substrates usually are in a “stressed” state. In the presentation the two main methods for stress measurements, wafer curvature and X-ray lattice parameter measurements will be presented. Special attention will be given to the information that can be obtained by applying both techniques. This discussion will be followed by a discussion of recent results on stress in hard polycrystalline films. For Cr and CrN films, it has been shown that the stress is not uniform over the thickness of the film. High tensile stresses are observed near the substrate-film interface. Lower tensile stresses are observed further away from the interface. Moreover, it has been shown that the tensile stress is generated at the grain boundaries. In the case for which the deposition of the film is accompanied by an ion bombardment, a compressive stress is generated. The tensile- and compressive stresses in these films are independent and additive. For TiN films the situation is even more complicated. For TiN higher compressive stresses are observed close to the substrate-film interface. This effect is explained form the observation that for TiN, the evolution of the grain boundary density is accompanied by an evolution of the texture. Various texture components exhibit a different sensitivity to compressive stress generation by ion-peening.