On the kinetics of spatial atomic layer deposition

Spatial atomic layer deposition (ALD) is a promising technology for high deposition rate and high-throughput ALD that can be used for roll-to-roll and large-area applications. In an ideal spatial ALD reactor, the design of the injector should be tuned to the deposition kinetics of the ALD reaction, requiring an in-depth knowledge of the dependencies of the growth per cycle (GPC) on the main kinetic parameters. The authors have investigated the deposition kinetics of spatial ALD of alumina from trimethylaluminum and H2O at atmospheric pressure. A kinetic model was developed, which describes the growth per cycle as a function of the main kinetic parameters. The observation of a vt time dependency in the GPC indicates that precursor diffusion to substrate is rate limiting. Next to a fundamental insight into the kinetics of atmospheric pressure spatial ALD, this model can be used for design optimization of new spatial ALD reactors. Furthermore, the model shows that the maximum alumina deposition rates obtainable with spatial ALD are in the order of several nm/s