Papers by Keyword: Multi-Sputtering

Abstract: TiNi is well known as a typical shape-memory alloy, and is expected to be a promising material for micro actuators. In order to realize micro electro mechanical systems (MEMS) with this material, we have to get thin crystal film of the material, since the shape-memory property appears only when the structure is crystalline. In our previous studies we developed a new apparatus as well as a new deposition process for lowering the crystallization temperature by using ion irradiation. In addition, we have found that the deposited film by the process can be crystallized at very low temperature (below 473 K) without annealing but with simultaneous irradiation of Ar ions during sputter-deposition. In this study, we aim for the realization of crystallized TiNi film, which is deposited on Si substrate below 373 K substrate temperature. In order to realization the purpose, we have revealed the effect of Ar ion energy on lowering the crystallization temperature. The ion energy is measured with a quadrupole mass spectrometer (QMS) having an ion energy analyzer. The deposited TiNi films are examined with an X-ray diffraction (XRD). We found the plasma potential against the reactor chamber is important to be considered in the ion irradiation energy. The effects of ion energy for the crystallization of TiNi film are discussed.

Abstract: In order to fabricate two-dimensional micro actuators with shape memory alloy films, it is especially important to evaluate the anisotropy of transformation strain that is caused by texture. In this paper, microstructures of sputter-deposited TiNi films are examined. The films of 1 μm in thickness are sputter-deposited on Si(001) substrates by RF magnetron multi-sputtering system equipped with four separate confocal sources as well as with substrate heating. Pure Ti and Ni targets of 50 mm in diameter are used for the sources. The films deposited at ambient temperature have been generally amorphous. However, we find that some films which are deposited at 773K of substrate temperature are crystalline, when we appropriately choose sputtering parameters such as source voltage and the distance between a target and the substrate. X-ray powder diffraction and pole figure measurements reveal that these films are oriented with {110}B2 parallel or inclined at 45 degree to the substrate. Furthermore, we also find that crystallized film is deposited even at 673K of substrate temperature by applying pulse bias voltage to the substrate.