UNIFORMITY OF DEPOSITED FILM THICKNESS ON A UNEVEN SURFACE BY DIRECT SIMULATION MONTE-CARLO

In CVD reactions, the reactant molecules are activated by energy sourc es to yield film-forming precursors above a substrate. These active pr ecursors collide on the surface and deposit the desired film. The meth od of direct simulation Monte Carlo is applied to emulate one or two p recursors, which undergo intermolecular collisions in the gas phase li ke hard spheres, and reflect or deposit on the surface according to th eir sticking probabilities. The coverage uniformity in a trench is imp roved if the sticking probability of precursor is small, the aspect ra tio of rectangular trench is small, or the opening angle of wide-mouth trench is large. The minimum film thickness always occurs at the bott om corner of trench. The thickness uniformity is more influenced by th e species with the larger sticking coefficient in a system of two film -forming species at the same concentration. The uniformity will be enh anced if the species with the lower sticking coefficient has a higher number density. Finally, the film growth of silicon carbide in a trenc h is closely simulated by the method developed.