Papers by Author: Hitoshi Habuka

Abstract: 4H-silicon carbide epitaxial film was etched using chlorine trifluoride gas. The etch rate of C-face at 2-100 % and at various temperatures was 0.8 – 10 μm min^-1, which was comparable to those of the silicon carbide substrates. The surface morphology observed after the etching was very smooth, in contrast to that of the substrate showing many pits.

Abstract: The in situ cleaning process of a silicon carbide epitaxial reactor was developed using chlorine trifluoride gas for removing the film-type silicon carbide deposition formed on a susceptor. By adjusting the etching temperature to less than 330 °C, the formed silicon carbide films could be removed without significant damage to the susceptor.

Abstract: The silicon carbide CVD reactor cleaning process was studied by means of detaching silicon carbide particles, which was formed on the silicon carbide coated carbon susceptor surface during the silicon carbide film deposition. The contact points between the particles and the susceptor surface were etched using chlorine trifluoride gas at temperatures lower than 290 °C for 120 min. During this process, the carbon susceptor covered with the silicon carbide coating film suffered from little damage while achieving cleaning.

Abstract: A SiC dry etcher using chlorine trifluoride (ClF₃) gas was evaluated, particularly about the etching rate distribution. At 100%, the etching rate was high in the center region and was low in the outer region. However, that at 20% showed the opposite profile. This difference was considered to be due to the chlorine trifluoride gas distribution which was built above the gas distributor.

Abstract: A SiC dry etching reactor using chlorine trifluoride (ClF₃) gas was designed and evaluated with the help of numerical calculations and experimental results. The etching rate was about 16 μm/min when the ClF₃ gas concentration, the total flow rate and the SiC substrate temperature were 90%, 0.3 slm and 500 °C, respectively. The gas stream above the substrate surface was concluded to significantly affect the etching rate profile.

Abstract: The C-face (0001) 4H-SiC surface morphology produced by etching using chlorine trifluoride gas was studied, focusing on the influence of the off-orientation. The etching pit at the 4^o off-oriented surface was formed at a temperature higher than 973 K, which was higher than 623 K for the on-axis surface. At 1073 K, the hexagonal-shaped etching pits were observed after the etching at the chlorine trifluoride gas concentration of less than 3 %. In the temperature range lower than 900 K, the mirror surface could be maintained after the etching. Thus, the mirror surface and the pitted surface are expected to be formed on the 4^o off-oriented surface by means of appropriately adjusting the parameters, such as the temperature and the chlorine trifluoride gas concentration.

Abstract: A floating zone (FZ) silicon wafer produced from a Czochralski (CZ) single-crystal ingot was subjected to prolonged annealing at a high temperature. Precipitates were formed in a N2(70%)+O2(30%) ambient atmosphere. The precipitate regions manifested themselves as dark concentric rings in the X-ray topographs. According to the results of cross-sectional transmission electron microscopy observations and energy-dispersive X-ray spectroscopy elemental analyses, nitrogen was distributed throughout the precipitate regions, while oxygen was rich in the periphery of the regions. A high concentration of nitrogen was also directly detected by secondary ion mass spectrometry in the mid-depth of the wafer in the precipitate regions. Electron diffraction analysis of the precipitates showed that their phase was α-Si3N4.

Abstract: The silicon carbide thin film formation process, completely performed at room temperature, was developed by argon plasma and a chemical vapor deposition using monomethylsilane gas. Silicon-carbon bonds were found to exist in the obtained film, the surface of which could remain specular after exposure to hydrogen chloride gas at 800 oC. The silicon dangling bonds formed at the silicon surface by the argon plasma are considered to react with the monomethylsilane molecules at room temperature to produce the amorphous silicon carbide film.

Abstract: The etch pits on the C-face 4H-SiC substrate was produced by chlorine trifluoride gas at various temperatures. The etch pit density showed the comparable value to the current dislocation density level of the Si-face 4H-SiC, when the etching was performed around 713 K. Thus, the etch pit density obtained by this technique is expected to reveal the crystal quality.

Abstract: The etch pit density produced on the C-face 4H-SiC substrate using chlorine trifluoride gas at various temperatures was evaluated. Because the etch pit density formed at the substrate temperature of 713 K showed the comparable value to the current dislocation level of the Si-face 4H-SiC, the etch pit density obtained by this technique is considered to have a relationship with the crystal quality.