HfO2 Atomic Layer Deposition Using HfCl4 ∕ H2O : The First Reaction Cycle

Abstract

The growth behavior and film quality of deposited by atomic layer deposition (ALD) using depends on the hydroxylation of the exposed surface. In this work, we investigate the dependence of the first chemisorption reaction at on the OH density of the silicon surface. We observe that the hydroxyl density, and hence the Hf deposition, on wet oxides depends on the initial preparation as well as on the stabilization time in the ALD reactor. A good understanding of the initial nucleation behavior is necessary because wet oxides are used in complementary metal–oxide–semiconductor transistors as surface pretreatment for aggressively scaled gate dielectrics. Moreover, the chemisorption reaction is used to estimate the hydroxylated fraction of these surfaces by means of theoretical models. Finally, the temperature dependence of the OH density, as available in the literature, is applied to gain insight into the stoichiometry of the chemisorption reaction.