Papers by Author: Shigeru Kimura

Abstract: We measured the thermal expansion coefficients of 18R-LPSO phase and α-Mg phase in a Mg₉₇Zn₁Y₂ alloy polycrystal. This was achieved by using a Gandolfi camera, which was attached on a high precision diffractometer at SPring-8 BL40XU beamline. By using this system, fine diffraction data were obtained from a Mg₉₇Zn₁Y₂ polycrystal at 6 different temperatures between 90 and 450 K. We succeeded to determine cell parameters of 18R-LPSO phase and α-Mg phase separately in the Mg₉₇Zn₁Y₂ alloy polycrystal. The thermal expansion coefficients were determined from the refined cell parameters. The differences of the thermal expansion coefficients of 18R-LPSO phase and α-Mg phase in the Mg₉₇Zn₁Y₂ alloy were much smaller than those of single-phase 18R-LPSO and α-Mg polycrystals.

Abstract: Using X-ray microdiffraction (XRMD) and transmission electron microscopy (TEM) techniques, we have investigated the microscopic structure of Si(011)/Si(001) direct silicon bonding (DSB) substrates. XRMD was performed to measure the local lattice spacing and tilting in the samples before and after oxide out-diffusion annealing. Diffraction analyses for (022) lattice planes with two orthogonal in-plane directions of X-ray incidence revealed anisotropic domain textures in the Si(011) layer. Such anisotropy was also confirmed by TEM in the morphology at the Si(011)/Si(001) bonded interface. The anisotropic crystallinity is discussed on the basis of interfacial defect structures which are proper to the DSB substrate.

Abstract: The use of Si(011)/Si(001) direct silicon bonding (DSB) substrates is a key element of future complementary metal-oxide-semiconductor device technology. In the conventional bonding process, it is necessary to remove interfacial SiO2 to achieve direct atomic bonding. In this study, using X-ray microdiffraction and transmission electron microscopy, we investigate the structural changes caused by oxide out-diffusion annealing (ODA). It is revealed that crystallinity of the bonded Si(011) layer is degraded after low temperature ODA and gradually recovered with an increase in the ODA temperature and annealing time, which is well correlated with the interfacial SiO₂/Si morphology. Characteristic domain textures depending on the ODA temperature are also detected.

Abstract: We have developed new microdiffraction system at the SPring-8. This system uses a focused beam produced using a phase zone plate combined with a narrow slit, which makes a small focused beam that has a small angular divergence. Furthermore, we can use the two-dimensional x-ray CCD detector, which enable us to measure local reciprocal space maps at many points in a sample, that is, the distribution of strain fields and lattice tilts can be revealed in high-angular- and high-spatial-resolution.

Abstract: It has been reported that SiC/SiC composite has high strength and toughness, but is degraded when exposed in air at high temperatures due to the propagation of the crack made by the premature fracture of the SiO2 layer. The present work aimed to describe such a behavior with a computer simulation. For this aim, the shear lag - Monte Carlo simulation method was applied. The variation of strength of the composite as a function of thickness of the SiO2 layer and change of fracture morphology with progressing oxidation could be reproduced satisfactorily by this method.