Koji Nakamae

Local field effects on voltage contrast in the scanning electron microscope

The local field effects on voltage contrast in the scanning electron microscope (SEM) mean that local fields generated by a non-uniform potential distribution on specimen surface cause a variation in the secondary electron (SE) detector current. It causes some errors in the voltage measurement. The authors present a theory to calculate the SE detector current in the presence of the local fields. In the calculation, they assume that the field distribution above the specimen surface (metal electrodes with 8 mu m width and 12 mu m separation) is two-dimensional. Analysed models are a conventional SEM detector system (model A), a retarding-field energy analyser with an extraction field (model B) and a high-resolution energy analyser with an extraction field (model C). The results show that the local field effects could not be neglected even in models B and C with strong extraction fields. The calculated values of local field effects in models A and B agree well with the experimental ones. The dependence of local field effects on the electrode geometry is equivalent to that on the extraction field, though this dependency is not so strong.

Rotation vector analysis of eye movement in three dimensions with an infrared CCD camera.

We have developed a new technique for analyzing the rotation vector of eye movement in three dimensions with an infrared CCD camera based on the following four assumptions; i) the eye rotates on a point; ii) the pupil edge is a circle; iii) the distance from the center of eye rotation to pupil circle remains unchanged despite the rotation; iv) the image of the eye by the CCD camera is projected onto a plane which is perpendicular to the camera axis. After taking digital images of voluntary circular eye movements, we first constructed a three-dimensional frame of reference fixed on the orbita of the subject wearing a goggle equipped with an infrared CCD camera, and determined the space coordinates of the center of eye rotation, the center of the pupil, and an iris freckle. We then took digital images of the eye movements during a saccade or vestibulo-ocular reflex (VOR) and analyzed the axis and angle of the eye movements by the trajectories of the center of the pupil and the iris freckle. Finally, Listings plane of saccade and the gain and the phase of VOR were obtained. The suitability of this technique is examined.

Analysis of the transit time effect on the stroboscopic voltage contrast in the scanning electron microscope

The transit time effect (TTE) on stroboscopic waveform measurements in the scanning electron microscope is analysed. Here the TTE means the voltage contrast variation due to the time-varying surface electric field near the measurement electrode. The results show that the TTE on waveform rise and fall times or amplitude measurements cannot be disregarded for waveforms with a time variation of the order of 100 ps or less. The TTE on pulse width measurements does not appear to be so large.

Function testing of bipolar ICs and LSIs with the stroboscopic scanning electron microscope

The functional testing of individual circuits is essential for device manufacturers when integrated circuits have not satisfied design specifications. What is required for the functional testing of modern high-density and fast IC and large scale integration (LSI) circuits is a method which has a time resolution in the subnanosecond region and a spatial resolution in the submicrometer region. Furthermore, the test probe must be easy to position on the circuit, and inspection should be possible without having to remove the passivation glass oxide. The authors show that all of these requirements can be satisfied by using a scanning electron microscope (SEM) in the stroboscopic voltage contrast mode. A microcomputer-controlled SEM allows the testing of internal circuit operations with a time resolution of 0.2 ns, a spatial resolution of 0.2 /spl mu/m, and a voltage resolution of 50 mV. Application to a bipolar hex-inverter IC, a quadruple-multiplexer IC, and a 1024 bit PROM in the megahertz region is reported to demonstrate the efficiency of the system.

A quantum watermarking scheme using simple and small-scale quantum circuits

A new quantum gray-scale image watermarking scheme by using simple and small-scale quantum circuits is proposed. The NEQR representation for quantum images is used. The image sizes for carrier and watermark are assumed to be

Measurements of deep penetration of low-energy electrons into metal-oxide-semiconductor structure

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Measurements of the energy dependence of electron beam assisted etching of, and deposition on, silica

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