14 September 1994 Small-spot thin-film thickness-measurements with Brewster's angle reflectometer
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A new small-spot, film-thickness measuring system operating near Brewster's angle, shows 0.1 Angstrom or 0.1% precision on SiO2 films in the 10-400 Angstrom range. The illuminating beam is focussed to a e-2 intensity diameter of 8 microns. The elliptical spot on the surface is easily placed in the center of test areas, such as a 50 micron square pad. The measurement technique takes into account the non Brewster's angle rays present within the focussed beam and the Gaussian intensity distribution of these rays. The resulting theoretical and experimental reflectance-vs.-film-thickness curves are shown to agree. Precision tests for various film-thicknesses are shown. Measurements are made in 2-3 seconds. Proper focussing and placement of the illuminating beam is achieved by autofocussing of a separate microscope viewing system.
© (1994) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Duane C. Holmes, Rodney P. Johnson, "Small-spot thin-film thickness-measurements with Brewster's angle reflectometer", Proc. SPIE 2337, Optical Characterization Techniques for High-Performance Microelectronic Device Manufacturing, (14 September 1994); doi: 10.1117/12.186643; https://doi.org/10.1117/12.186643

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