Atomic Layer Deposition (ALD) is receiving increased attention lately because of its ability to produce ultra-thin, and conformal film structures using sequential self-limiting surface reactions. Simulation of an ALD process is difficult because of periodic pulsing of reactants and purge gases in short intervals. A comprehensive model for ALD should include gas phase transport, transient boundary conditions, adsorption/desorption and surface reactions. The present work focuses on predicting deposition rates of thin film diffusion barriers - deposition of TiN in an ALD reactor using TiCl_4, and NH_3 as reactants. Adsorption, desorption, and surface reaction steps are characterized using heterogeneous reaction mechanisms. The simulation results shed light on effect of geometrical and process parameters on precursor adsorption on the wafer surface, whether the precursors completely purge over the specified purge time, and quantify TiN growth rate dependence on pulse times.
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