Fabrication of Microactuators Utilizing Sputter-deposited Ti-Ni Shape Alloy Thin Films

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Ti-Ni shape memory alloy thin films have been made on Si substrates. They were shape memorized and their transformation characteristics were measured. A Ti-Ni target was used. Shape memorization was conducted by widely varying heat-treatment temperature and time in order to investigate the effect of heat-treatment condition on the transformation characteristics. The transforamtion temperatures increased eith increasing heat-treatment temperature.Si substartes coated by a Ti-Ni film were.micromachined to fabricate microactuator structures. The actuator is composed of a 2.0 micrometer thick Ti-Ni film and a 1.0 micrometer thick SiO_2 film. The hight of the actuators was measured during heating and cooling by using a |azer beam technique. The actuator reached several tens micrometer upon cooling and became flat upon heating, and the movement was repeated by following thermal cycling. The Ms was 340 K, while the As was 360 K. They are well above the room temperature so that a 50 Hz response was achieved due to a good coolingjate. Variety of sizes of actuators were prepared and their actuator characteristics were measured, the size beins ranged between 100 and 1400 micrometers. The actuation distance was linealy corelated with the actuator size. This means that variety of applications will be possible by utilizing these actuators.