Feature scale simulation studies of TEOS-sourced remote microwave plasma-enhanced chemical vapor deposition of silicon dioxide: Role of oxygen atom recombination

Experimental data and feature scale simulations are combined to test a kinetic model proposed for remote microwave plasma-enhanced chemical vapor deposition (RμPECVD) of silicon dioxide from tetraethylorthosilicate (TEOS) and oxygen. The constitutive relationships used are refinements of those developed for the direct capacitively coupled rf PECVD of SiO₂, using TEOS and oxygen. We discriminate between a first order and a second order oxygen atom recombination reaction on the surface of the feature based on simulation results obtained using EVOLVE, a physically based low pressure simulator. We then use film profiles inside features to estimate the oxygen atom flux to the water surface and the kinetic parameters used in the rate expressions for the deposition reaction and the oxygen atom recombination reaction. Results indicate that under the conditions of our experiments, the thermally activated oxygen atom recombination reaction on the growing silicon dioxide surface is second order in oxygen atoms. This recombination reaction consumes reactive oxygen and leads to gradients in oxygen atom flux in the feature. Because this surface reaction is thermally activated, the magnitude of the gradient increases as the water surface is increased, which results in significant degradation of step coverage.