STEP-COVERAGE SIMULATION FOR TETRAETHOXYSILANE AND OZONE ATMOSPHERIC-PRESSURE CHEMICAL-VAPOR-DEPOSITION

A simulation model for atmospheric pressure (AP) CVD has been developed using one-dimensional diffusion and mass conservation equations. The model was applied to trench step-coverage of the tetraethoxysilane (TEOS) and 03 CVD, in which it was not necessary to consider lateral diffusion because of narrow (and deep) trenches. For nondoped silicate glass (NSG), the step-coverage of a 4.5 aspect ratio trench showed a good fit if a sticking probability of 0.0039 was assumed for the 0.6% ozone (in oxygen) deposition and of 0.0026 for the 6% ozone deposition (both 400-degrees-C). The reaction rate constant was compared with the diffusion mass-transfer coefficient, and the reaction proved to be limited by diffusion of the reactant, TEOS, which directly participated in the CVD reaction. For the 2 m/o phosphosilicate glass (PSG) step-coverage, which had a slight overhang, the model matched the obtained results well only when an active growth species with a high sticking probability of 1.0 was added to the growth species of nondoped oxide. This analytical simulation method satisfactorily explains the experimental data.