  We have developed a simulation tool to model self-limited processes such as
atomic layer deposition and atomic layer etching inside reactors of arbitrary
geometry. In this work, we have applied this model to two standard types of
cross-flow reactors: a cylindrical reactor and a model 300 mm wafer reactor,
and explored both ideal and non-ideal self-limited kinetics. For the
cylindrical tube reactor the full simulation results agree well with analytic
expressions obtained using a simple plug flow model, though the presence of
axial diffusion tends to soften growth profiles with respect to the plug flow
case. Our simulations also allowed us to model the output of in-situ techniques
such as quartz crystal microbalance and mass spectrometry, providing a way of
discriminating between ideal and non-ideal surface kinetics using in-situ
measurements. We extended the simulations to consider two non-ideal
self-limited processes: soft-saturating processes characterized by a slow
reaction pathway, and processes where surface byproducts can compete with the
precursor for the same pool of adsorption sites, allowing us to quantify their
impact in the thickness variability across 300 mm wafer substrates.
