| Utilizing their shape memory effect (SME), Titanium-nickel (TiNi) shape memory alloy (SMA) films have the potential to become high performance actuating materials for microelectromechanical systems (MEMS) due to their ability to generate large forces with large power-to-volume ratio, high recoverable strain, low power consumption, biocompatible property, and long lifetime. This dissertation studies their actuating characteristic, manufacturing process, microfabricating technology, and applications in MEMS.Based on the actuating mechanism of SMA, two new concepts which are called process-uncontrollability and quasi process-controllability, and a design idea which is called element-interconnection used to achieve quasi process-controllability of SMA microactuators, are presented. Founded on element-interconnected design, a model of microtweezer actuated by SMA thin film, which can adjust its gripping force output, is investigated. Subsequently, two kinds of basal movable element models actuated by SMA are studied, they are bidirectional bending beam element which can yield bending deflection, and linear actuating element with linear displacement output. Correspondingly, two micromachines, made of SMA bidirectional bending elements and linear actuating elements according to element-interconnection idea, are studied, and their kinematical equations are founded, respectively.Concerning producing processes of TiNi SMA. thin films, cold rolling of thin wires and DC magnetron sputtering are studied. Two TiNi SMA films at thickness of 75 ?m and 90 u m were obtained by rolling, and their reverse martensitic transformation peak temperatures (A*) were measured at 35? and 109? by differential scanning calorimetry (DSC) , respectively. Without any supplementary method, a Ti-rich alloy target (Ti-48at%Ni) were used to enrich Ti content in films during sputtering. As the first step, TiNi thin film is deposited on a glass substrate by sputtering, and annealed at 600? in a vacuum furnace. Its transformation temperature (A*) is 75 ? determined by DSC. Whereafter, the surface micro-morphology of both sides of TiNi SMA thin film deposited on glass was investigated by atomic force microscope (AFM), and thedifference of morphology between the two sides is observed. It has been shown that, in the growing surface of sputtered TiNi film, the trend of grain to accumulating along the normal direction like a column is clearly observed, and the grain is very loose which resulted in more microcavities, but in the surface facing to glass substrate, grain is so compact that there are hardly microcavities. In order to optimize parameters of sputter-depositeing used to manufacture silicon-based TM films in the next step, the dissertation analyses and explains the difference between the two surfaces of sputtered TiNi film from sputtering factors. In succession, TiNi thin film is deposited on single-crystal silicon substrate using optimized parameters utilizing sputtering, and its transformation temperature (A*) is 72 ? indicated by DSC curve after being annealed in an ultra-high vacuum (UHV) chamber. In addition, the composition of the silicon-based TiNi film was analyzed by an energy dispersive X-ray spectroscopy (EDS), and the Ti content in the film is approximately 51at%. Besides, the interface between silicon and amorphous TiNi thin film deposited by high power (2000W) DC magnetron sputtering has been investigated using EDS and X-ray diffraction (XRD). Bidirectional diffusion between silicon and TiNi thin film has been exhibited in EDS linescan curves, along with mapping distribution micrographs. Moreover, a ternary titanium nickel silicide-NisTi2Si, is formed during sputtering deposition, which is determined by XRD analysis.Apropos of micromanufacturing technologies of silicon-based MEMS correlative to TiNi SMA, patterning of TiNi thin film is one of the key processes, In order to photoetch thicker TiNi films (more than 10 ? m) deposited on silicon for developing a new microactuator, lift-off process was investigated for patter...
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