In situ stress measurements in zirconium and zirconium oxide films prepared by direct current sputtering

The evolution of stress during growth of thin zirconium and zirconium oxide films deposited from a metallic target using direct current magnetron sputtering has been analyzed in situ. The oxygen flow during the deposition was varied to obtain films with different stoichiometries ranging from metallic zirconium to fully stoichiometric zirconium oxide. The stresses in the metallic films depend strongly on the pressure during deposition. Films created at low pressure possess tensile stresses in the beginning of growth, which turn highly compressive with increasing film thickness. Films created at high pressures show only tensile stresses similar to evaporated metals of low mobility. The transition between metallic and oxidic zirconium films has been analyzed. The compressive stresses in the metallic film turn tensile once low amounts of oxygen are let into the chamber. This behavior is related to a structural change of the zirconium film, which was confirmed by x-ray analysis. Upon further increasing oxygen flow, the tensile stresses turn compressive again.