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

It is well known that Si surface treatment is crucial for low-temperat ure Si epitaxy. Although considerable work exists which is aimed at el ucidating the effects of Si surface pretreatments on Si epitaxy, littl e is known about the effects of SiO2 surface pretreatments for polycry stalline silicon (poly-Si) growth. We report on a study of SiO2 surfac e pretreatment effects on poly-Si nucleation and film surface roughnes s using a low energy hydrogen ion beam (200 eV) and H-2 gas annealing (850 degrees C) in a rapid thermal chemical vapor deposition system, I n situ real-time ellipsometry was used to monitor the surfaces during pretreatment and observe the nucleation. The microstructure and surfac e 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 produ ce higher nuclei density and a smoother poly-Si surface than nonpretre ated substrates, and the opposite was found for hydrogen gas annealing giving lower nuclei density and rougher poly-Si. (C) 1996 American In stitute of Physics.