A low cost method for producing bi- axially textured metal films, which are expected to have characteristics similar to single crystals, has been developed by scientists at ETH Zurich.
Low energy ion irradiation of uni-axially textured films results in a selective sputtering process which leads to the formation of nanocrystals that have the same out-of-plane and in-plane crystallographic orientation. Bi-axially textured films can be obtained through epitaxial growth on these nanocrystals.
Reliability is a key issue in micro- and nanosystems. The most common causes of material failure, including fatigue, creep, and electro-migration, are strongly related to the microstructure of the materials.
Single crystal materials are known to show higher reliability and performance compared to their polycrystalline counterparts, but they require high-cost processing techniques.
The development of a low-cost method that can produce single crystal materials is expected to be of considerable interest. The technology has the potential for enhancing the reliability of micro- and nano-systems.
Fibre-textured films can be selectively sputtered away by means of a low energy ion beam until nanocrystals that all have the same crystallographic orientations are left. This nanocrystal formation then acts as the seedbed for the subsequent deposition of fresh material, resulting in the laying down of bi-axially textured film. Repetition of these two steps allows for the growth of continuous biaxially textured films.