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Tsukasa Hirayama

Publications and source records attributed to Tsukasa Hirayama.

8 recordsLinked to original sources
PubMed2005

Electron holographic observation of micro-magnetic fields current-generated from single carbon coil.

A carbon coil was evaluated for use as a micro-solenoid in a small magnetic device. A single carbon coil was lifted out of the aggregate using a tungsten fine probe in a focused ion beam (FIB) system and was wired to two small electrodes in the specimen holder of a transmission electron microscope (TEM). A direct current was supplied to the single carbon coil. A micro/nano-magnetic field generated from the coil was directly observed by electron holography. A computer simulation of electron holography was also done to quantitatively analyze the magnetic field. Details on the FIB technique, the electron holographic observation and the simulation are described.

Journal Article↗
PubMed2005

Amplitude-division three-electron-wave interference for observing pure phase objects having low spatial frequency.

A new interferometry is presented for direct visualization of pure phase objects having low spatial frequency, such as electromagnetic microfields. A thin crystal of silicon prepared using argon ion milling is installed at the standard specimen position. This silicon crystal works as an electron beam splitter and forms diffraction spots in the back focal plane. Using the objective aperture, [000], [111] and [111] spots are selected as coherent electron sources to illuminate the specimen located at the area-selecting aperture position. The lattice image of silicon is formed below the area-selecting aperture position by decreasing the electric current of the objective lens. Three defocused images of the specimen are observed in the fluorescent screen by overexciting the first intermediate lens. We have successfully visualized equipotential lines around a latex particle charged by electron beam irradiation. The computer-simulated image was consistent with the experimental image.

Journal Article↗
PubMed2004

Off-axis electron holography without Fresnel fringes.

A new method for forming an electron hologram without Fresnel fringes caused by an electron biprism is presented. Adding a fine filament to the ordinary setup for off-axis electron holography directly prevented Fresnel diffraction at the electron biprism and eliminated 70% of the phase error due to the Fresnel diffraction. This made it possible to obtain a hologram having uniform interference fringes, and to reconstruct a clear phase image of a weak electric-field.

Artifacts↗
PubMed2004

Electron holographic mapping of two-dimensional doping areas in cross-sectional device specimens prepared by the lift-out technique based on a focused ion beam.

Recently, electron holography has been successfully applied to analyze two-dimensional (2D) dopant distribution in semiconductor devices with high resolution and high sensitivity. The preparation of proper specimens is a fundamental step for the practical application of electron holography in the semiconductor industry. Therefore, it is important to explore a reliable and quick specimen preparation method. In our current work, we have tried to use the lift-out technique based on a focused ion beam, to fabricate cross-sectional CMOS device specimens for electron holographic observation. Using the lift-out technique, specimens with a large area and uniform thickness can be prepared directly from integrated circuit wafers in a very short time. Specimens with a complex and unknown dopant distribution were examined using off-axis electron holography. In the reconstructed phase images, the different 2D doping areas in a CMOS device, such as source, drain, well and substrate, were revealed successfully. The advantages and disadvantages of the technique are discussed.

Journal Article↗
PubMed2004

A new method for preparing plan-view TEM specimen of multilayered films using focused ion beam.

A new method is proposed for preparing plan-view specimens of a CeO(2)/Gd(2)Zr(2)O(7) multilayer on a metal substrate using focused ion beam milling. In the plan-view specimen, a membrane from the surface region of the CeO(2) to the Gd(2)Zr(2)O(7) layer was thinned to electron transparence so that the entire span of the multilayer can be observed in a single sample. The in-plane alignments of the CeO(2) layer and the Gd(2)Zr(2)O(7) layer were analysed using selected-area diffraction patterns (SADPs). The boundaries between the CeO(2) grains were also examined using SADPs.

Microscopy, Electron, Transmission↗
PubMed2004

Specimen preparation for high-resolution transmission electron microscopy using focused ion beam and Ar ion milling.

We have developed a focused ion beam (FIB)-Ar ion-milling technique for high-resolution transmission electron microscopy. A micrometresized specimen was mounted on a cross section of metal foil of a few micrometres thick, using FIB microsampling. Following this, a 2 degrees wedgeshaped part was made in the specimen using FIB. Finally, the specimen was milled using an Ar ion beam to remove the FIB-damaged layers. We applied the FIB-Ar ion milling technique to a CeO(2)/Gd(2)Zr(2)O(7) multilayer specimen, resulting in the crystal lattice fringes of both layers being clearly observable in comparison to a specimen finished using a Ga ion beam at an accelerating voltage of 10 kV.

Argon↗
PubMed2004

Direct observation of electrostatic microfields by four-electron-wave interference using two electron biprisms.

A new method has been developed for directly visualizing electromagnetic microfields in real time by the interference of four-electron waves obtained using a transmission electron microscope equipped with a field-emission gun and two electron biprisms. When one object wave and three reference waves interfere, equal-phase lines of the object wave are displayed as the intensity modulation of the interference fringes, in the manner same as in the three-electron-wave interference. The advantage of the four-electron-wave interference is that equal-phase lines are observed without precisely adjusting the angle between the two biprisms or rigorously controlling the fringe spacings of the two biprisms.

Holography↗