Modeling at the ALD reactor scale
Understanding ALD Through Modeling

We have reviewed a number of phenomena typical of ALD that can be described at the atomic scale. Nevertheless, equally important aspects occur at other scales and require different theoretical frameworks. In particular, gas-phase transport from the reactor inlet (precursor reservoirs and ALD valves) to the surfaces to be coated can occur over distances on the order of decimeters or meters. The homogeneity, thickness, and composition of the films must be controlled over dimensions that are themselves on the order of centimeters. Furthermore, deposition may occur inside micrometer-scale trenches or pores, requiring control at the mesoscopic scale, which entails an understanding of flow in geometries that are both complex and multidimensional.

Fluid transport processes are modeled by solving the governing equations of fluid mechanics—the Navier-Stokes equations—coupled...