Ballistic deposition simulation of via metallization using a quasi-three-dimensional model

A quasi-three-dimensional ballistic deposition model for thin film growth by physical vapor deposition is described. This model incorporates three-dimensional incident flux distributions and shadowing effects, but simulates deposition through disc accretion in a two-dimensional plane. Results from the simulation of sputtered metal deposition over vias ranging from 0.5 to 3.0 μm width are presented and compared with two-dimensional simulation results. Step coverages are calculated and plotted as a function of via size. The use of a ballistic deposition program enables a density analysis of the simulated films. The simulated films display a drop in density of 22-27% for the films deposited on the via sidewalls, and this density drop is plotted versus via size for both the two-dimensional and three-dimensional simulations