Hisashi Komaki

Preparation and properties of TiN and AlN films from alkoxide solution by thermal plasma CVD method

Abstract Single phase TiN and AlN films were prepared on a Si wafer from titanium tetra-etoxide and aluminum tri-butoxide solutions dissolved in ethanol and toluene, respectively, using an Ar/N 2 /H 2 radio-frequency (r.f.) inductive thermal plasma chemical vapor deposition (CVD) method. The films were characterized by X-ray diffraction, X-ray photoelectron spectroscopy, scanning electron microscopy, measurement of electrical resistivity and Vickers microhardness. Factors affecting the formation of the films (lattice parameter, chemical composition, oxygen/carbon content, and deposition rate of the films) were examined in terms of the N 2 flow rate (2.5–4.5 slm), substrate temperature (300–700°C), feed rate of the solution (0.025–0.3 ml/min), and the mole ratio of the alkoxide solution (1:1–1:3). The optimum conditions for preparation of TiN films produced a film 0.2–3 μm thick with an oxygen content of 8 at.% and a free carbon content of 4 at.%, showing an electrical resistivity of 370 μΩ cm. The optimum conditions for AlN films produced a film 0.3 μm thick containing 14 at.% oxygen and 8 wt.% carbon. The deposition rate of the TiN film was determined to be 30–35 nm/min. The Vickers microhardness of the TiN and AlN films was found to be 10±1 and 13±3 GPa, respectively.

Synthesis of high-Tc superconductive oxide films by plasma flash evaporation

We have been developing a thermal plasma flash evaporation method and applied it to the preparation of high- T c superconducting (HTSC) films. This method is characterized by high-rate deposition under a highly oxydizing atmosphere, resulting in the in situ formation of highly oriented YBa 2 Cu 3 O 7-x (YBCO) films with T c around 90 K. The fact that any twins have not been observed in the microstructure at this stage, suggests direct growth of orthorhombic YBCO without the tetragonal-to-orthorhombic (T-O) phase transformation in this method.