Spectroscopic ellipsometry and interference reflectometry measurements of CVD silicon grown on oxidized silicon

摘要

Several samples of thin-film silicon grown on oxidized Si, both oxidized and unoxidized, have been examined using spectroscopic ellipsometry (SE) and constant angle reflection interference spectroscopy (CARIS). The SE data was fit to 5- or 6- layer models of the sample near surface region, using the optical functions of thin-film silicon determined from a previous work. Reasonable fits were obtained from samples containing amorphous Si (a-Si) or large-grain polycrystalline Si (p-Si), but fits to samples containing small-grain, undoped p-Si were poor unless a 8-15 nm surface roughness layer is included. Furthermore, the optical functions of p-Si:ud are not consistent from sample to sample. The optical functions determined from SE measurements were then used to interpret CARIS measurements, extracting the thicknesses of the films, which are then compared with the thicknesses obtained from SE.