| Budget Amount *help |
¥1,300,000 (Direct Cost: ¥1,300,000)
Fiscal Year 2000: ¥500,000 (Direct Cost: ¥500,000)
Fiscal Year 1999: ¥400,000 (Direct Cost: ¥400,000)
Fiscal Year 1998: ¥400,000 (Direct Cost: ¥400,000)
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| Research Abstract |
We sometimes cannot measure the depth of a semiconductor trench hole by using interference spectroscopy when a trench diameters approach visible light wavelengths. When investigating the cause, the interference spectrum data using Gaussian beam irradiated the two-dimensional dielectric trench is obtained by the boundary element method and is analyzed by a continuous wavelet process. We used the silicon substrate as a dielectric in the visible light range. The FFT processing converts a horizontal frequency axis into a time axis, and the depth is obtained discretely by the multiplication of time and light velocity. In the wavelet processes, the frequency axis does not change, the vertical axis becomes scales (the reciprocal of continuous times), and the z-axis shows the signal strength. For Epolarized light with a cutoff property and an electric field in the groove direction, the depth is measured deeply by the FFT and is measured accurately by the wavelet by using the signals that appeared over the no cutoff frequencies. The E-light is advantageous to the deep groove measurement, because a small quantity of light leaks into the substrate. For the H polarized light with no cutoffs and the magnetic field component in the groove direction, a large quantity of light leaks into the substrate. The signal is obtained strongly by equalizing the groove' s width with the spot beam' s width, or by changing the viewing angle from the front viewing angle. The optimum wavelet function is needed because the scales information decreased when using wavelet process for the narrow frequency window. Finally, it is confirmed that the two-dimensional tapered dielectric trench figure can be measured by the wavelet analysis, because the cutoff widths correspond to a frequency in the E-light and the time reflected from each tapered part becomes larger for the higher frequencies.
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