ROTATING-COMPENSATOR MULTICHANNEL ELLIPSOMETRY - APPLICATIONS FOR REAL-TIME STOKES VECTOR SPECTROSCOPY OF THIN-FILM GROWTH

A multichannel spectroscopic ellipsometer based on the rotating-compen sator principle was developed and applied to measure the time evolutio n of spectra (1.5-4.0 eV) in the normalized Stokes vector of the light beam reflected from the surface of a growing film. With this instrume nt, a time resolution of 32 ms for full spectra is possible. Several a dvantages of the rotating-compensator multichannel ellipsometer design over the simpler rotating-polarizer design are demonstrated here. The se include the ability to: (i) determine the sign of the p-s wave phas e-shift difference Delta, (ii) obtain accurate Delta values for low el lipticity polarization states, and (iii) deduce spectra in the degree of polarization of the light beam reflected from the sample. We have d emonstrated the use of the latter spectra to characterize instrument e rrors such as stray light inside the spectrograph attached to the mult ichannel detector. The degree of polarization of the reflected beam ha s also been applied to characterize the time evolution of light scatte ring during the nucleation of thin film diamond by plasma-enhanced che mical vapor deposition, as well as the time evolution of thickness non uniformities over the probed area of the growing diamond film. In this article, a detailed description of calibration and data reduction for the new instrument is provided. Future applications of this instrumen t are expected for real time characterization of film growth and etchi ng on patterned surfaces for microelectronics and on thick transparent substrates for large area displays and photovoltaics. (C) 1998 Americ an Institute of Physics. [S0034-6748(98)03004-4].