Showing papers by "Akira Kinbara published in 1992"

Process effects on structural properties of TiO2 thin films by reactive sputtering

Abstract: We have been investigating the growth of crystalline titanium dioxide films at deposition temperature between room temperature and about 400 °C. The films were prepared by a dc magnetron reactive sputtering on glass and Si(100) substrates. The structural properties of the films were analyzed by x‐ray diffractometry. The influence of total pressure, oxygen mole fraction in the mixture of Ar–O2, discharge current, and substrate temperature on the structural properties were studied. In addition to higher substrate temperature, low total pressure, high discharge current, and small oxygen mole fraction were shown to be preferable for growing anatase–rutile mixture films. Annealing of the films in air at 850 °C showed that anatase–rutile transformation strongly depends on the deposition temperature; the films deposited at temperature below 400 °C were converted to the anatase–rutile mixture films, and the films deposited at 400 °C to complete rutile films.

Formation of high adhesive and pure Pt layers on TiO2

Abstract: The formation of a high adhesive noble metal layer on an oxide layer has been investigated in the Pt/(Ti)/TiO2/SiO2/Si system, prepared in a vacuum evaporation apparatus. The thermosonic ball bonding test and the conventional pull test were successively applied to the evaluation of adhesion. The Ti inserted layer between the Pt and the TiO2 layer was found to improve the adhesion. A Ti layer of approximately 10 nm was found to be necessary for stronger adhesion. Auger electron spectroscopy (AES) depth profile results showed that a part of the Ti atoms in the inserted layer were segregated to the Pt surface from the interface by annealing at 1373 K for 30 min, while the rest of Ti atoms in the inserted layer remained and acted as a ‘‘glue’’ at the interface between the Pt and the TiO2 layer. It should be noted that Ti could not be detected in the Pt layer within the AES detection limits. Scanning electron microscope and energy dispersive x‐ray spectroscopy observations showed that Ti diffusion occurred through the grain boundaries of the Pt layer and Ti atoms appeared at surface grain boundaries on top of the Pt layer.

TiN film coatings on alumina radio frequency windows

Abstract: Thin films of TiN having low secondary electron emission (SEE) yields are coated on alumina rf windows in order to suppress the occurrence of multipactor. It is necessary to form films with a proper thickness in order to obtain a sufficient reduction of SEE as well as to avoid any excessive ohmic loss in conductive TiN films. For an optimization of the film thickness on an alumina surface, measurements of the SEE coefficients, and ohmic losses in the rf (S‐band) field were carried out. High‐power examinations of the coated windows were also performed. The results show that TiN films with a thickness of 0.5 nm or greater on alumina ceramics have SEE coefficients of less than unity at an incident energy of 10 keV. High‐power tests have revealed that the ‘‘going away’’ of TiN films is probably due to excessive ohmic losses taking place when the thickness is greater than 1.5 nm. It is concluded that optimized film thickness for window coatings is 0.5–1.5 nm.

Effects of different pretreatments on the surface structure of silicon and the adhesion of metal films

Abstract: Interface structures and adhesion to silicon after different surface pretreatments have been investigated for Ni(500–1000 nm)/Ti(250 nm) films prepared in a dc planar magnetron sputtering apparatus. In order to obtain high adhesion, a chemical pretreatment (with buffered HF) has been found to be favorable in comparison with a conventional Ar ion bombardment pretreatment (with cathodic voltage: 400 V). High resolution transmission electron microscopy (HRTEM) showed that there were two layers between Ti and Si in the case of Ar ion bombardment pretreatment. Energy dispersive x‐ray spectroscopy (EDS) and electron diffraction (ED) showed that they were amorphous Ti–Si alloy and amorphous Si containing Ar. Moreover, a peeling pattern, after the test with adhesive tape, could be found at the boundary between the amorphous Ti–Si alloy layer and the amorphous Si layer containing Ar by using x‐ray photoelectron spectroscopy (XPS). In the case of chemical pretreatment, only an amorphous Ti–Si alloy layer was observ...

Influence of Ion Beam Irradiation on the Structure and Properties of Dielectric Thin Films

Abstract: The changes in the structure and properties of MgF2 and ZnS films prepared by ion-beam-assisted deposition were investigated as a function of the power of argon ion beam irradiation. The refractive indices of MgF2 films in vacuum increased with the increase of the ion beam power, and the film density also increased slightly. It was also shown that, by the dynamic observation using Environmental Scanning Electron Microscope (ESEM), ion beam assistance increases the imperviousness to water of ZnS films. It was also observed that the wetting property for water of the film surface decreased due to ion beam assistance for both MgF2 and ZnS films.