Multiscale computational fluid dynamics modeling of spatial thermal atomic layer etching

Abstract

Spatial atomic layer deposition and etching processes have emerged to reduce the overall process time while maintaining the conformity of thin films by functioning continuously. This research constructs an multiscale computational fluid dynamics (CFD) model with a dynamic mesh that combines a microscopic kinetic Monte Carlo algorithm of the film etching with a CFD simulation of the gas phase for the spatial thermal atomic layer etching of Al2O3. Using this model, we evaluate the effect that design and operation variables including the gap distance, purge and precursor gas flow rates, substrate velocity, and vacuum pressure have on the substrate film etching per cycle and uniformity. Numerical results suggest that small gap distances with sufficiently high N2 flow are desired to accomplish effective precursor separation for reactor configuration and the process operation requires low substrate velocities and low vacuum pressures to achieve optimal film quality and conformance.