Surface chemistry as data for level-set simulation of etching and deposition
Level-set simulators of etching and deposition move the surface with a velocity that depends on adsorbate coverages. These coverages are usually computed from balances solved and coded by hand for each chemistry, whereas voxel-based Monte Carlo profile simulators read the reaction mechanism as data. For the open-source level-set simulator ViennaPS, this work presents a surface model whose rate laws, Jacobian and velocity are derived from a reaction file and evaluated with ray-traced fluxes. Steady-state coverages are obtained with Newton's method and transient coverages with a conservative integrator. One compiled model is applied to eight chemistries for chemical vapour deposition, selective epitaxy, plasma etching, sputtering and atomic layer deposition. It reproduces a hand-written silicon etch model to seven significant digits at a single point and within the Monte Carlo noise in a masked trench. In a high-aspect-ratio cavity, alumina conformality is determined by a trimethylaluminium reaction probability within the measured range.