A model for surface and bulk chemistry during silicon etching in high plasma density inductively coupled reactors

Summary form only given. Low gas pressure, high plasma density etching tools are becoming predominant in industry for rapid, uniform small feature etching. In these reactors, surface reactions (both on the wafer and the walls) take on greater importance since the rate of volumetric collisions is smaller (low gas pressure) while the reactive fluxes to surfaces are larger. We have developed a Monte Carlo simulation to investigate surface reactions and the disposition of etching products in high plasma density reactors, and inductively coupled plasma (ICP) tools in particular. Time dependent electric fields and source functions for radicals and ions are obtained from a companion hybrid plasma equipment model. Monte Carlo techniques are then used to track the trajectories of radicals and ions, volumetric reactions and surface reactions. An etch model for poly-Si in chlorine chemistries based on the work of Dane and Mantei is implemented in which the local etch rate is proportional to the neutral radical fluxes and ion power flux. Predicted etching rates for poly-Si using chlorine chemistries will be compared to experiments performed in ICP reactors. The effect of the etchant on the plasma chemistry, and hence on the etch rate, will be discussed. A 3-dimensional visualization of fluxes of plasma species will be presented.