Gas-phase silicon atoms in silane chemical vapor deposition: Laser-excited fluorescence measurements and comparisons with model predictions

Laser-excited fluorescence was used to detect gas-phase silicon atoms during chemical vapor deposition from silane. Relative Si densities were measured as a function of height above the susceptor, susceptor temperature, amount of H2 added to the He carrier gas, and total pressure. The Si atom density decreased both upon addition of H2 and as the total pressure was lowered below ∼100 Torr. Comparisons of these measurements with the model developed by Coltrin, Kee, and Miller [J. Electrochem. Soc. 131, 425 (1984)] show that the model predicts the qualitative behavior of the experimental Si atom profiles over a wide range of experimental conditions. Addition of a mechanism for particulate nucleation to the model may resolve some of the discrepancies between model and experiment.