Abstract
The effects of the thickness of the sputtered Cu thin films and the substrate material on the residual stresses and mechanical properties of Cu thin films were investigated. The thickness of Cu thin films was varied in the range of 0.5 to 3 μm. The substrate material was a glass (Cu/glass specimen) or a single crystal Si (Cu/Si specimen). The specimens that PTFE was inserted as a middle layer were prepared for the Si substrate (Cu/PTFE/Si specimen). Residual stresses of Cu thin films were measured using a synchrotron radiation source. The hardness and elastic modulus of Cu thin films were measured using a nanoindentation method. The crystallite size of Cu thin films was evaluated by micro-beam X-ray analysis. The tendencies of the residual stress against the thickness of Cu thin films were greatly different depending on the substrate material. The crystallite size of Cu/PTFE/Si was smaller than that of Cu/glass. This fact corresponds to the result that the hardness of Cu/PTFE/Si is higher than that of Cu/glass. The elastic modulus and hardness decreased with increasing the indentation depth. Therefore, it is considered that the mechanical properties have a certain depth distribution in the direction of the thin films.
