SPECTROSCOPIC ELLIPSOMETRY ON THE MILLISECOND TIME SCALE FOR REAL-TIME INVESTIGATIONS OF THIN-FILM AND SURFACE PHENOMENA

Submonolayer sensitivity to thin-film nucleation and growth in real time on the millisecond scale has been achieved with a unique rotating polarizer multichannel ellipsometer. Continuous spectra in the ellipsometry angles {psi(h-upsilon),DELTA(h-upsilon)} consisting of approximately 50 points from h-upsilon = 1.5 to 4.3 eV have been obtained with acquisition and repetition times as short as 16 and 32 ms, respectively. As an example of the instrument capabilities, we present results for hydrogenated amorphous silicon (a-Si:H) growth on c-Si by plasma-enhanced chemical vapor deposition at a rate of 400 angstrom/min. In this example, the acquisition and repetition times are both 64 ms, and at this speed a precision in (psi,DELTA) of approximately 0.02-0.03-degrees is obtained under optimum conditions. We observe a-Si:H nucleation in the first 2 s of deposition, and detect relaxation of nucleation-induced surface roughness with submonolayer sensitivity.