Kinetics and conformality of TiN films from TDEAT and ammonia

Abstract

We propose a heterogeneous reaction mechanism which is consistent with experimental observations of the kinetics of metal-organic chemically vapor deposited TiN films from tetrakisdiethylaminotitanium (TDEAT) and ammonia. The proposed mechanism includes the readsorption of diethylamino radicals, which are formed as a byproduct of the deposition reaction. We use film profiles in holes on patterned wafers, in addition to available growth rate data from flat wafer experiments, to estimate parameter values for a kinetic expression derived from the proposed mechanism. EVOLVE, a low pressure deposition process simulator, is used to estimate the value of the adsorption parameter for the adsorbing reaction byproduct. Reactant partial pressures at the wafer surface are estimated simultaneously. Step coverage depends on both the spatially dependent TDEAT sticking factor and the value of the adsorption parameter for the inhibiting byproduct. The byproduct inhibition model can explain the observed kinetics as well as the film conformality; however, film profiles calculated using a simple sticking factor model (first order reaction model) matched experimental profiles almost as well. In this simple model, the step coverage of TDEAT sourced films depends on the sticking factor of the depositing species, which may be formed by homogeneous reactions. The activation energy estimated using the byproduct inhibition model is about 2300 cal g −1 mol −1.