STTR PHASE I: A Fiber-Optic Probe for In-Situ Measurement of Thin Film Deposition

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*** 9632155 Johnson This Phase I STTR project will combine laser and white light sources in a single diagnostic instrument compatible with high temperature processes, immune to electromagnetic noise (a byproduct of rf wafer heating), and free of the requirement for precise optical alignment. The basic concept of the fiber-optic monitor has been demonstrated I in rudimentary pulsed laser experiments on a silicon nitride reactor at Brown University; Ion Optics Inc. has successfully extracted real-time layer composition from white-light reflectance spectra. Phase I will extend this earlier work to a practical dual-source configuration that is fast and accurate enough to track thin-film growth at rates typical of advanced devices. The performance of virtually all modem opto-electronic devices depends critically upon the ability to grow multi-layered, thin-film structures whose composition and thickness is precisely controlled. In production-scale deposition processes, monitoring and adjustment cannot be done in real time. Ion Optics Inc. will overcome the problem with a dual-light-source, fiber-optic, thickness and composition monitor operating simultaneously as an interferometer (measuring growth rate) and as a reflectometer (measuring composition and total thickness). A major advantage of such an instrument is its ability to provide the data needed to make instantaneous composition changes during growth to compensate for the effects of diffusion. Diffusion is an important factor when very thin adjacent layers of dissimilar composition must be deposited at relatively high temperature, as is the case for multiple quantum well devices. This project will result in reasonably priced, easy to use thickness and composition monitors. Another version of these optoelectronic devices would compete with quartz deposition gauges. ***