Thickness Measurements of Silicon Films Using Partial Coherence Interferometry

摘要

An optical system composed of a Michelson interferometer, a short coherencelength edge-emitting light emitting diode (ELED), and a fiber-optic-coupler probe has been described and used to measure the thickness of thin silicon charge-coupled device (CCD) films. The measurement precision for samples with a thickness of the order of 10 micrometers is better than 0.1 micrometer and the range of thickness that can be measured can be from a few micrometers to hundreds of micrometers if a suitable source is used. The fiber probe assembly is adaptable for remote in situ measurements of samples within an etching chamber, and the measurement results can be used to control the sample etching process. The fiber probe also allows for localized measurements at selected positions across the area of the sample, and these results can be used for control of thickness uniformity.