Growth, Structure and Stress of DC Magnetron Sputtered TiB₂ Thin Films

Abstract

TiB₂ is a very hard refractory compound that strongly resists erosion and shows metallic luster and good electrical conductivity. It has potential applications in protective coating systems. This paper investigates the microstructure and stresses of as-deposited TiB₂ thin films ranging from 2000 °A to 4000 °A thick produced by dc magnetron sputtering as a function of sputtering power and Ar pressure. Three power levels: 100, 400, 600 W, and four pressures: 3, 5, 8, and 12 mTorr were used. X-ray diffraction studies indicate that two types of crystalline structure are formed: a randomly oriented fine crystalline structure and a coarser grained (001) textured structure, depending on the sputtering power and pressure. As-deposited stresses at different powers all show a transition from compression to tension as the Ar pressure increases. The relationship between the processing parameters, microstructure and residual stresses is discussed. The effects of the deposition power and pressure on the residual stress transition of TiB₂ thin films are clearly mapped out by 3-D and contour maps.