Simulation of density variation and step coverage for a variety of via/contact geometries using SIMBAD

The two-dimensional simulation by ballistic deposition of sputtered metal deposited over a 1.5-μm step and a large variety of vias and contacts is presented. The sizes of the vias and contacts are varied from 1 to 3 μm, and three different sidewall topographies are simulated. In addition, simulated film growth over a stacked via/contact is presented. The step coverage of each film is determined, and surface profiles are provided at different growth intervals. The use of SIMBAD, a ballistic deposition technique, provides information unattainable through the use of conventional film deposition simulations. In addition to the step coverage available from conventional simulations, density profiles of the simulated films are produced and the columnar microstructure is analyzed. Finally, conclusions are inferred as to the quality of real films deposited over each via geometry