<title>Growth and characterization of shape memory alloy thin films for micropositioning and microactuation</title>

We have investigated the growth of TiNi shape memory alloy thin films at relatively low temperatures (below 150 degrees Celsius) by an ion beam sputter deposition process which is compatible with integrated circuit microfabrication technology. Films of thickness less than 5 micrometer have been deposited onto various substrates including silicon, glass and Kapton and generally exhibit shape memory characteristics without requiring high temperature annealing. Films covering areas up to 5 cm² have been grown and also TiNi microstructures having a range of minimum lateral dimensions down to approximately 100 micrometer have been fabricated. Temperature-time profiles measured during direct electrical Joule heating have been used to derive thermal parameters and monitor phase changes indicative of the two-way shape memory effect. The implications for speed of response by scaling shape memory alloy structures to micrometer dimensions are considered.