SiO2 etching in inductively coupled C2F6 plasmas: surface chemistry and two-dimensional simulations

A surface chemistry model was developed to understand the mechanism of etch ing or deposition on silicon dioxide surfaces exposed to a high density C2F 6 plasma. The surface chemistry model in combination with a gas phase plasm a chemistry model was implemented in the Modular Plasma Reactor Simulator ( MPRES) to study oxide etching and uniformity under typical processing condi tions. Simulation results on etch rate and uniformity as a function of oper ating conditions were consistent with experimental data. The transition fro m polymerization to etching as the ion bombardment energy (bias power) was increased was also captured by the simulation. Under low pressure condition s (several mtorr) the ion flux peaked at the wafer center while the neutral flux peaked at the wafer edge. Under such conditions, the oxide etch rate was highest at the edge. This supports the conclusion that, at such low pre ssures, oxide etching is ion driven but neutral dominated. (C) 2000 Elsevie r Science S.A. All rights reserved.