Photoresist thickness measurement using laser-induced fluorescence.
A technique is proposed to measure the thickness of a small area of photoresist film on a substrate. This technique uses the fluorescence (peak wavelength, ~600 nm) induced in the film by a focused laser beam (wavelength, 497 nm). An initial calibration line is obtained by comparing several thicknesses and their related fluorescence. The film's thickness is then determined from its fluorescence signal. The laser spot size and the accuracy of this measurement have also been estimated.
Kimura
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Takami
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