Influence of target temperature on crystallization and properties of NiTi thin film shape memory alloy

A new process parameter viz.; target temperature, has been introduced to decrease the composition variables between the target and substrate. A DC magnetron sputtering system has been used for the deposition of NiTi film from equiatomic NiTi target on silicon substrate. The target transitions from a low temperature value to a high temperature value (> 700 degreesC) during sputtering. The sputtered films were crystallized by heating to 500 degreesC for 10 minutes in situ prior to removal from the sputtering system. X-ray diffractogram shows that the film peaks correspond to martensite as well as austenite phases. The film developed under this process displays the two-way shape memory effect without post annealing. Electrical resistivity measurement reveals that there are three different phases present viz.; austenite, rhombohedral and martensite, which exists at different temperature ranges. The characteristic transformation temperatures determined by the electrical resistivity method are compared with those obtained with DSC thermograms.