Structure and properties of electrocodeposited Cu-Al₂O₃ nanocomposite thin films

Nanocomposite thin films which consist of 50 nm Al₂O₃ nanoparticles in a copper metal matrix were deposited on a silicon wafer. The thickness of the nanocomposite thin films was about 3 microns and the volume density of the nanoparticles was between 3% and 5%. The films were synthesized using electrocodeposition. The grain size of the nanocomposite film was significantly smaller than the grain size of control films of pure copper. Electron backscatter diffraction (EBSD) experiments indicate that neither the nanocomposite thin films nor the control films exhibits a crystallographic texture. Nanoindentation experiments show that the hardness of the nanocomposite thin film is approximately 25% higher than the hardness of the control films of pure copper. A prototype of a microchannel array in the nanocomposite thin film was made using standard microelectromechanical (MEMS) fabrication technology. It is expected that the enhanced mechanical properties exhibited by nanocomposite thin films have the potential to improve the reliability of various MEMS devices which rely on thin metal films. The results presented herein lay the groundwork for future studies in which the size, volume density, morphology, distribution as well as type of nanoparticle in the nanocomposite will be systematically and independently varied in order to optimize mechanical properties. Copyright © 2005 by ASME.