A 3-DIMENSIONAL MODEL FOR LOW-PRESSURE CHEMICAL-VAPOR-DEPOSITION STEP COVERAGE IN TRENCHES AND CIRCULAR VIAS

A general analytical model has been developed to calculate particle transport and spatial step coverage evolution within 2-dimensional and 3-dimensional microelectronic device structures during low-pressure chemical vapor deposition. The model can account for spatially dependent nonunity reactive "sticking probabilities," anisotropic source fluxes, and trench "shadowing" effects. There is no restriction on the initial and evolving shape of the structure. Model results are compared to direct Monte Carlo simulations for step coverage on rectangular trenches, and are found to more accurately describe the observed experimental step coverages during phosphorous-doped silicon dioxide glass film deposition. We present here, for the first time, detailed calculations of step coverage in circular vias for a wide range of reactive sticking probabilities.