Effect of thickness on microstructure and texture in Cu thin films for interconnects

Cu thin films are an attractive material for interconnects in future integrated circuits technologies. Due to their influence on the mechanical properties, microstructure and texture of thin film have become important topics in materials science. The effect of thickness on microstructure and texture in Cu thin films was investigated with EBSD (electron backscatter diffraction) and XRD (X-ray diffraction) techniques in the present work. The experimental results show that the average grain size is less than 250 nm and grain growth with the thickness increasing in Cu thin films. The volume fractions of both high-angle boundaries and Σ3 twin boundaries increase with the thickness increasing of Cu thin films. There exist stronger {111} fiber texture which has a decreased tendency with the thickness increasing of Cu thin films. It reveals the competition between the strain energy and surface/interface energy exist in Cu thin films. The microstructure and texture evolution with the thickness of Cu thin films was discussed with the theory of strain energy and surface/interface energy.