Real-time spectroscopic ellipsometry from 1.5 to 6.5 eV

A rotating polarizer multichannel ellipsometer has been optimized for operation well into the ultraviolet (UV) spectral range. Key modifications to previous instrument designs include (i) a tandem in-line Xe/D₂ source configuration for usable spectral output from 1.5 (827 nm) to 6.5 eV (191 nm), (ii) MgF₂ Rochon polarizers for high transmission in the UV and (iii) a spectrograph with a grating blazed at 250 nm and two stages of internally-mounted order-sorting filters. The resulting multichannel ellipsometer provides 132 point spectra in the ellipsometric parameters (ψ, Δ) over the range from 1.5 to 6.5 eV with a minimum acquisition time of 24.5 ms. As an example of the application of this instrument, real-time spectroscopic ellipsometry (SE) is reported for the analysis of a hexagonal boron nitride thin film deposition by radio-frequency magnetron sputtering onto a silicon wafer substrate.