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Simultaneous Real Time Spectroscopic Ellipsometry and Reflectance for Monitoring Semiconductor and Thin Film Preparation
Published online by Cambridge University Press: 22 February 2011
Abstract
This paper describes an expansion of the capabilities of real time spectroscopic ellipsometry (SE) that results from simultaneous measurement of a reflectance spectrum RA along with the two spectra in the ellipsometric angles (Ψ,δ). RA provides information complementary to (Ψ,δ), but until now has not been exploited in real time spectroscopic applications. Earlier, we have developed a novel rotating-polarizer multichannel ellipsometer for real time studies of thin film growth that utilizes a photodiode array (PDA) detector for highspeed acquisition of (Ψ,δ) spectra. Employing this instrument with a 12.5 Hz polarizer rotation rate, three-parameter (3-p) data sets {Ψ(hv,t), δ(hv,t), RA(hv,t); 1.4≤hv≤4.5 eV} can now be obtained with a time resolution as short as 40 ms during film growth. A resilient new analysis approach based on mathematical inversion and least-squares fitting is described to interpret the 3-p data set. The 3-p approach has been successful in characterizing plasmaenhanced chemical vapor deposition (PECVD) of amorphous semiconductors, and provides the film dielectric functions and thicknesses independently at each time during film growth. RA(hV) exhibits deviations from the spectrum predicted in successful modeling of (Ψ,δ) spectra alone. These deviations result from diffuse light scattering by particulates in the plasma. We show how additional information can be extracted from the spectral dependence of the scattering loss.
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- Copyright © Materials Research Society 1994
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