LASSI - A Scanning Differential Ac Interferometer For Surface Profile And Roughness Measurement

G. Makosch

doi:10.1117/12.949176

21 March 1989 LASSI - A Scanning Differential Ac Interferometer For Surface Profile And Roughness Measurement

G. Makosch

Proceedings Volume 1009, Surface Measurement and Characterization; (1989) https://doi.org/10.1117/12.949176
Event: 1988 International Congress on Optical Science and Engineering, 1988, Hamburg, Germany

Abstract

LASSI (Laser Spot Scanning Interferometer) is a highly precise and versatile surface profilometer developed for various measurement applications in surface lapping, etching and polishing processes. The principle of measurement is based on a differential interferometer in which two parallel light beams split from a He-Ne laser are scanned across a sample surface. The phase difference of the reflected beams changes proportionally with the height variation between the two spots illuminated on the surface. In using a phase-locked method to determine the phase differences height variations of a surface can be measured with manometer precision. The range of applications of an instrument built on this principle encompasses step height, roughness, slope, and profile measurement of surface microtopographies. Special versions of this tool have also been developed for in situ monitoring of etch or deposition rates in sputter-etching and wet etching processes. In this paper, the principle of measurement will be described and some theoretical aspects of the measurement technique will be discussed. The various LASSI tools and their applications are reviewed.

Citation Download Citation

G. Makosch "LASSI - A Scanning Differential Ac Interferometer For Surface Profile And Roughness Measurement", Proc. SPIE 1009, Surface Measurement and Characterization, (21 March 1989); https://doi.org/10.1117/12.949176

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