Effects of hydrogen surface pretreatment of silicon dioxide on the nucleation and surface roughness of polycrystalline silicon films prepared by rapid thermal chemical vapor deposition

Abstract

It is well known that Si surface treatment is crucial for low-temperature Si epitaxy. Although considerable work exists which is aimed at elucidating the effects of Si surface pretreatments on Si epitaxy, little is known about the effects of SiO2 surface pretreatments for polycrystalline silicon (poly-Si) growth. We report on a study of SiO2 surface pretreatment effects on poly-Si nucleation and film surface roughness using a low energy hydrogen ion beam (200 eV) and H2 gas annealing (850 °C) in a rapid thermal chemical vapor deposition system. In situ real-time ellipsometry was used to monitor the surfaces during pretreatment and observe the nucleation. The microstructure and surface roughness of the deposited poly-Si films are determined by analysis of in situ spectroscopic ellipsometry (SE) and atomic force microscopy (AFM) measurements. Hydrogen ion beam pretreatment was found to produce higher nuclei density and a smoother poly-Si surface than nonpretreated substrates, and the opposite was found for hydrogen gas annealing giving lower nuclei density and rougher poly-Si.