Real-time characterization of film growth on transparent substrates by rotating-compensator multichannel ellipsometry

A multichannel spectroscopic ellipsometer in the fixed-polarizer-sample-rotating-compensator-fixed-analyzer (PSC(R)A) configuration has been developed and applied for real-time characterization of the nucleation and growth of thin films on transparent substrates. This rotating-compensator design overcomes the major disadvantages of the multichannel ellipsometer in the rotating-polarizer-sample-fixed-analyzer (P(R)SA) configuration while retaining its high speed and precision for the characterization of thin-film processes in real time. The advantages of the PSC(R)A configuration include (i) its high accuracy and precision for the detection of low-ellipticity polarization states that are generated upon reflection of linearly polarized light from transparent film-substrate systems, and (ii) the ability to characterize depolarization of the reflected light, an effect that leads to errors in ellipticity when measured with the P(R)SA configuration. A comparison of the index of refraction spectra for a glass substrate obtained in the real-time PSC(R)A mode in 2.5 s and in the ex situ fixed-polarizer-fixed-compensator-sample-rotating-analyzer (PCSA(R)) mode in ~10 min show excellent agreement, with a standard deviation between the two data sets of 8 x 10(-4), computed over the photon energy range from 1.5 to 3.5 eV. First, we describe the PSC(R)A ellipsometer calibration procedures developed specifically for transparent substrates. In addition, we describe the application of the multichannel PSC(R)A instrument for a study of thin-film diamond nucleation and growth on glass in a low-temperature microwave plasma-enhanced chemical vapor deposition process.