A model for Al/sub 2/O/sub 3/ ALD conformity and deposition rate from oxygen precursor reactivity

The atomic layer deposition of alumina using TMA (trimethyl-aluminum) and O/sub 3/, O (atomic oxygen), or H/sub 2/O into high aspect ratio trenches is investigated. We determine the activation energy of the initial adsorption step by ab initio calculations and derive an effective sticking coefficient. We show that this quantity essentially determines the film conformity and deposition rate of self limiting ALD processes. Implementing this effective model into a custom feature scale simulator, coupled to a fluid dynamical reactor simulator, a consistent description of ALD on atomistic, feature, and reactor scale is obtained. With this multi scale approach it is possible for the first time to simulate film profile evolution during dielectric ALD into high aspect ratio trenches for future DRAM generations.