Tsutomu Komoda

Study on the Structure of Evaporated Gold Particles by Means of a High Resolution Electron Microscope

The structure of evaporated gold particles were examined through the (111) lattice image observation. The results obtained confirmed Inos analysis (1966) that the particles are of multiple-twin structure and have external shapes of either decahedron or icosahedron. It was also found that the structures are already completed at the initial stage of deposition when the particle size in smaller than 20A, but the particles no longer keep their initial structures when they grow beyond about 150A in size. Neither gaps nor dislocations were observed in the particle image; instead, lattice images were found to be composed of lines not exactly parallel to each other, but slightly diverging outwards. These observed facts suggest that the particle nucleus consisting of several atoms forms the smallest unit of either decahedron or icosahedron and growth proceeds layer by layer of atoms on the nucleus.

Tunneling acoustic microscope

A new type of microscope, which is based upon both a scanning tunneling microscope (STM) and a technique for detecting acoustic waves, is described. An acoustic wave generated in a STM’s sample, by vibration of its tip, is detected by a piezoelectric transducer coupled to the sample. The amplitude of the acoustic wave corresponds to the strength of the force interaction between the tip and the sample, and is sensitive to tip‐sample spacing. We have been successful in keeping the spacing constant by using a new feedback loop that holds this amplitude constant without tunneling. This method enhances the features of the STM without reducing its functions and enables simultaneous use of both force interactions and tunneling current to investigate the properties of samples. Topographies taken by the new feedback system and tunneling current images are shown.

The direct observation of the long period of the ordered alloy CuAu (II) by means of electron microscope

According to the electron diffraction studies on ordered alloys such as CuAu(II) (1), Cu3Pt (2), Ag3Mg (3), Cu3Pd (4), Au3Mn (5), Au4Zn (6) and Au3Zn (6), it was revealed that they possess superlattices consisting of anti-phase domains with definite size in a stable state. For example, CuAu(II) has a one-dimensional anti-phase domain structure characterized by the first kind of out-of-step, as shown in Fig. 1, while Cu3Pd has a two-dimensional anti-phase domain structure characterized by combination of the first kind and the second kind of out-of-step.

Electron Microscopic Observation of Crystal Lattices on the Level with Atomic Dimension

Many electron micrographs showing various lattice images were obtained from single crystal gold films. Many of them showed more than two sets of lattice images side by side or/and crossing to each other, e.g. (200), (020) and (220) crossing to each other. To obtain such images the crystal must be oriented so that Bragg reflections are simultaneously excited for all the lattice planes to be imaged. A new tilted illumination method developed by the present author was used to minimize the chromatic aberration for each of the lattice images. The astigmatism and specimen drift were eliminated along any directions, although for images along only one direction those in the same direction may be allowed. Double films of gold-gold and gold-copper were also studied. They showed moire fringes besides lattice images.

Anti-Phase Domains in Gold-Copper-Zinc Ordered Alloys Revealed by Electron Microscope

Using thin evaporated films of gold-copper-zinc ternary ordered alloys, the line-up of anti-phase domains has been observed as parallel lines on transmission electron micrographs of bright field, down to a domain size of about 8A. The lattice modulation accompanying anti-phase domains, i.e. the periodic error of lattice spacing or scattering factor with the same period as a domain size, has again been verified to play an important role in forming the satellites around the direct spot on a diffraction pattern, and hence, in forming the parallel lines on electron-microscopic images. Two-thirds of the intensity of the satellites have been estimated in the present alloy films to arise from the modulation, and the rest probably from double diffraction.

Variably shaped electron beam lithography system, EB55: II Electron optics

A variably shaped electron beam exposure system (EB55) with a high exposure rate is developed for direct beam lithography of 0.5 μm patterns. The electron beam column consists of seven magnetic lenses. The projection lens is specially designed to minimize deflection aberations and beam landing angle deviation on the wafer. The column design facilitates a shortened distance between the object and its image plane. Accelerating voltage is 30 kV due to decreased Coulomb interaction and proximity effect. In a shaped beam system, the electron gun should have a wide emission angle, high brightness, and large crossover size. A square rod type LaB6 cathode is developed for this purpose. The shaped beam is vector scanned by electrostatic deflection plates and electromagnetic coils. The scanning area is 2.6 mm square and the maximum beam size is 5.10 μm square. The size change unit is 0.02 μm. A beam current density higher than 10 A/cm2 is obtained with a small beam covergence angle. A shape edge slope smaller than ...

Off-Axis Electron Micro-Holography

An electron micro-hologram is recorded with an off-axis arrangement, using an electron bi-prism as the beam splitter and a pointed cathode as the rotationally symmetric coherent electron source. An image with a resolution of about 20 A is reconstructed with He–Ne laser light (λ=6328 A). A scattered wave from the object and a direct reference beam are superposed together by means of an electron bi-prism placed behind the back focal plane of the objective lens of an electron microscope. The quality of the image reconstructed from a hologram obtained with objective over-focused is better than that of the image reconstructed from a hologram obtained with objective under-focused.

A high‐speed, high‐precision electron beam lithography system (electron optics)

A variably shaped electron beam exposure system HL‐600 has been developed for both direct wafer writing and mask making. It was designed as a high‐throughput tool to cover lithography requirements down to a 0.5 μm linewidth. To achieve this high‐throughput capability, many newly developed techniques were adopted in the electron optics and in the control electronic circuits. The simplified electron beam column consists of only four magnetic lenses. The magnetic deflection for main field scanning was enlarged so as to reach up to 6.5 mm sq in order to reduce the overhead time associated with work stage movement. In addition, the design of an objective lens system with a small aberration, and an algorithm for deflection aberration correction were developed. Automatic measurement of defocusing and astigmatism aberrations at a number of sample points were performed by taking through focusing, and the third order polynomial correction function of deflection was determined. As a result, the edge resolution for t...

A high speed, high precision electron beam lithography system (system design)

A variably shaped electron beam lithography system HL‐600 has been developed for use in a semiconductor factory. HL‐600 was for high throughput. It is capable of direct wafer writing at high speed and also capable of mask writing at high accuracy. A very high speed beam control circuit has been developed. The pattern data were decomposed through the pipeline digital circuit. The settling time of the DA converter was shortened to 100 ns at full scale. An automated loader and wafer prealigner have been developed minimizing operator intervention. The specially designed computer and software system allow background processing pattern data during exposure. One of the most distinctive features of HL‐600 is the mode changing function. The large deflection mode guarantees writing of ten 4‐in. wafers per hour and the small deflection mode can accurately write submicron patterns. The mode change can be carried out immediately without special adjustment. This paper describes the system configuration in detail.

4.5 Electron Microscopes and Microscopy in Japan: 4.5A Electron Microscope Development at Hitachi in the 1940s

Publisher Summary Electron microscope history began at Hitachi. Hitachi took part in a development project of the Japan Society for Promotion of Science, to build electron microscopes in Japan. The first instrument was designed by K. Kasai and was handed over to B. Tadano for experiment. They were experienced cathode-ray oscillograph engineers. This was coincident with Knoll and Ruska, who developed the first electron microscope in the 1930s. They also were cathode-ray oscillograph engineers. The first electron microscope at Hitachi was completed in 1941 and was named HU-1. Later, in 1941, K. Kasai and B. Tadano started designing the next electron microscope, based on the precious data and knowledge obtained from the HU-1. This instrument was completed in 1942, and it was called HU-2. The HU-2 had many superior points over the HU-1. High-voltage stability, mechanical stability against vibration, and electron optical lens performance were some of them. It was easy to record images at several ten thousand times.