Hidekazu Kimura

Construction and commissioning of a 215-m-long beamline at SPring-8

Abstract The 215-m-long beamline has been constructed as the first medium-length beamline of SPring-8 for the purpose of R&D of imaging techniques, development of X-ray optics, computed tomography for mineral science, medical imaging, and X-ray topography. By using the long beamline, large field and spatially coherent beam can be obtained. Advantage of long beamline is successfully demonstrated by the preliminary experiment such as one-shot topograph of 300-mm-diameter silicon crystal.

Ulfrathin Tantalum Oxide Capacitor Process Using Oxygen‐Plasma Annealing

A highly reliable ultrathin tantalum oxide capacitor is fabricated by using oxygen-plasma annealing after the film deposition. A tantalum oxide film is deposited on a nitrided polycrystalline silicon surface using a mixture of pentaethoxy-tantalum [Ta(OC 2 H 5 ) 5 ] and oxygen gas. The films are annealed in an oxygen-plasma at less than 400 o C. The oxygen-plasma annealing greatly reduces the leakage current through tantalum oxide capacitors and produces better time-dependent dielectric breakdown characteristics than either dry O 2 annealing or two-step annealing (oxygen-plasma+dry O 2 annealings)

EXTENDED X-RAY ABSORPTION FINE STRUCTURE ANALYSIS OF THE DIFFERENCE IN LOCAL STRUCTURE OF TANTALUM OXIDE CAPACITOR FILMS PRODUCED BY VARIOUS ANNEALING METHODS

Extended x‐ray absorption fine structure (EXAFS) above the Ta L3 edge on tantalum oxide capacitor films has been measured. Tantalum oxide films were prepared by low‐pressure chemical vapor deposition (CVD) using a Ta(OC2H5)5 and O2 gas mixture. Four kinds of tantalum oxide films were studied: as‐deposited (amorphous), N2 annealed (crystalline), dry O2 annealed (crystalline), and O2‐plasma annealed (amorphous). From EXAFS analysis, differences in the local structures of tantalum oxide capacitor films, in terms of oxygen deficiency around Ta, were observed in the various annealed films. The leakage current characteristics of tantalum oxide capacitors correspond to the differences in the local structures around Ta.

X-ray diffraction study of undercooled molten silicon

The short-range order of molten silicon was investigated in a wide temperature range from 1893 K down to 1403 K, corresponding to an undercooling of 290 K. Energy-dispersive x-ray diffraction was used in combination with electromagnetic levitation. The structure factor and the pair correlation function were determined as a function of temperature from the experimental data. A small hump on the higher wave vector side of the first peak in the structure factor was observed at all temperatures. The position of the first peak in the pair distribution function shifted to shorter distances and its height increased gradually with decreasing temperature. No discontinuous behavior was observed in the entire temperature range investigated.

1-km beamline at SPring-8

A one-kilometer long synchrotron radiation beamline with an x- ray undulator source was completed at SPring-8. The beamline was planned to facilitate various applications of a wide-area coherent x-ray beam, development of bi-crystal x-ray interferometers for gravitational red-shift measurement and development of highly sensitive diagnostic methods of accelerator dynamics. This paper reports the structure of the long beamline as well as some selected first results including phase contrast imaging and diffraction imaging applications.

Early commissioning of the SPring-8 beamline for high resolution inelastic X-ray scattering

Abstract BL35XU of SPring-8 is dedicated to the investigation of sample dynamics on ∼meV energy scales using inelastic X-ray scattering and nuclear resonant scattering of synchrotron radiation. The beamline saw first light in February 2000. We briefly describe the beamline design and status. We include results from the early commissioning period, and from our program of instrumentation development, including backscattering monochromators and analyzer crystals.

X-ray phase-contrast imaging with submicron resolution by using extremely asymmetric Bragg diffractions

We have obtained x-ray phase-contrast images with high spatial resolution by using extremely asymmetric Si 111 Bragg diffractions near the critical angle of the total reflection. The x-rayimage could be magnified to 294 times in both vertical and horizontal directions. By using this x-ray microscopy system, we have observed clear phase-contrast images of a 0.7-μm-wide gold-line pattern.

Formation of Parallel X-Ray Microbeam and Its Application

We have developed a parallel X-ray microbeam of 7×5 µm2 in size with a small angular divergence, which aims high-resolution strain measurements in a very local area. The microbeam has been formed by compressing and collimating the X-rays from a third-generation undulator source using successive asymmetric reflections. Using this beam, we have evaluated the strain induced by field oxidation in silicon wafers by rocking curve measurements. We have observed that the lattice constant in the Si region near the oxide film edge is contracted and that in the SiO2/Si region is extended. The difference between these lattice constants is as small as about Δd/d~±5×10-6.

High-resolution microbeam x-ray diffractometry applied to InGaAsP/InP layers grown by narrow-stripe selective metal-organic vapor phase epitaxy

We measure the diffraction peaks of InGaAsP selective metal-organic vapor-phase epitaxial layers on 1.7-μm-wide InP stripe regions between a pair of SiO2 mask stripes. This is achieved by using an x-ray microbeam with low angular divergence and a narrow energy bandwidth that was produced through two-dimensional condensation of undulator radiation x rays from a synchrotron light source using successive asymmetric diffraction. The lattice strain is investigated by changing the SiO2 mask width from 4 to 40 μm. The rocking curves reveal clear peak shifts in the InGaAsP layers from the higher angle side to the lower angle side of the InP substrate peaks as the mask width increases.

Water-cooled first crystals for the SPring-8 x-ray undulator beamlines

In SPring-8, the first crystals with pin-post water path have widely used at x-ray undulator beamlines. The crystals have been fabricated by using metal diffusive bonding technique. Although the initial crystals had sufficient endurance for high heat load, deterioration of the performance due to the strain induced by the water pressure was observed. Newly designed crystal showed better diffraction properties. Some problems to be improved are also discussed.