Reaction data from quantum mechanics is used to simulate multiple cycles of atomic layer deposition
Many areas of nano-scale technology require conformal and stoichiometric thin films. Uniform and precisely-deposited films means improved efficiency and reliability of devices. Great progress has been made towards conformal thin films by using the smart chemistry of atomic layer deposition (ALD). ALD research concentrates on designing molecules (precursors) that can react so as to give the desired material in a conformal thin film. The unique feature of ALD is that reactions are self- limiting, which allows films to be deposited of thicknesses less than 2 nm. In our research, we simulate the reaction energetics and activation energies of the ALD chemical reactions so as to describe the essential mechanisms needed for successful ALD.
To simulate the growth of hafnium oxide (HfO2) through repeated chemical reactions over many ALD cycles, a 3D on-lattice Kinetic Monte Carlo (KMC) model has been developed. In this model, all atomistic reaction pathways computed with density functional theory (DFT) are implemented as reaction events on the lattice. The essential chemistry of the ALD reactions depends on the local environment at the surface.