IN-SITU MONITORING OF THIN FILM GROWTH USING A WIDE-BAND SCANNING MONOCHROMATOR.
AuthorVAN MILLIGEN, FRED JOSEPH.
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PublisherThe University of Arizona.
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AbstractTo augment the monitoring capabilities of a Balzers 760 coating chamber, we replaced the simple, single wavelength optical monitor with a wide-band scanning monochromator system which records transmission data over the visible region of the spectrum. The system is controlled by an IBM-PC. The same computer is also interfaced to a quartz crystal monitoring system which was purchased with the Balzers chamber. The scanning monochromator system required a new brighter light source to deliver sufficient signal to the detector array through the more complex, dispersive optical train. Above the chamber the filter and the photomultiplier pair were removed, and replaced by a flat mirror which diverts the beam horizontally into the scanning monochromator system. The beam passes first through a telescope-slit configuration onto a Jobin-Yvon holographic grating, built to disperse the 400-800 nm band of which we use approximately 360 nm. This reflective grating images the spectrum of the slit onto a Fairchild CCD array, which consists of 1728 elements. These elements are then averaged into 173 data points and recorded by the IBM-PC. The 173 data points allows us a wavelength resolution of about 2 nm. The IBM incorporates a Tecmar A/D board in accepting data from both the quartz crystal monitor and the scanning monochromator system. Although the system is capable of recording data at a faster rate, it is generally stored once every three seconds. This is adequate since at normal deposition rates this gives us information every 10 - 20 Angstroms of deposited material. The system has been used in several applications which will be discussed in this dissertation. They include in situ measurements of water adsorption into a film, derivation of optical constant profiles during the film deposition, both of which may lead us to a better understanding of the growth of a thin film. The monochromator has also been used to analyze the components of a multilayer coating by monitoring the film's transmission spectra while it was sputter-etched off. The extension of the system into the ultraviolet region of the spectrum and some future applications are also considered.
Degree ProgramOptical Sciences