A Study on Patterning Method of TiNi Shape Memory Thin Film

Abstract

To realize simple and powerful micro actuators, we have developed a new patterning method of TiNi shape memory alloy (SMA) thin films. This method supplies us attractive SMA micro structures from the viewpoint of aspect ratio. In the fabrication, we applied a lift-off process with a thick polymide mold layer and patterned a high aspect ratio SMA structure. The reason why we apply the lift-off process is that the structure's inner stress is lower than that obtained by wet or dry etching processes. By using this method, we have patterned structures of 20μm in width and 10μm in height. The aspect ratio of this structure is 0.5. The patterning accuracy is about 4μm. This process is useful to realize SMA micro actuators of TiNi thin films.