GROWTH AND CHARACTERIZATION OF SHAPE MEMORY ALLOY THIN FILMS FOR Si M1CROACTUATOR TECHNOLOGIES

摘要

NiTi thin film alloys have been grown by sequential multilayer deposition of Ni and Ti pure layers followed by metal interdiffusion by annealing. Short time (5 min) annealing of the deposited layers at 500℃ leads to alloying of Ni and Ti, provided that preferential oxidation of Ti is avoided. This has been achieved by capping of the layers with AlN. This constitutes a very efficient barrier, which prevents any oxygen contamination of the film, even for long time annealing in conventional furnaces. The structure of the processed films strongly depends on the temperature and time of the thermal process, obtaining Ni and Ti rich phases when the films are annealed at higher temperatures and/or during longer times. As-grown and processed films are analysed by X-ray Diffraction, in-depth Auger Electron Spectroscopy and X-ray Photoelectron Spectroscopy techniques. The obtained data corroborate the interest of the studied processes for the grown of NiTi thin films for the development of microactuator devices in Si technology.