Density functional theory was employed to investigate atomic layer deposition (ALD) mechanism of zirconia on Si(100)-2×1 surface with single and double hydroxyl groups. The ZrO₂ ALD process using ZrCl₄ and H₂O as precursors involves two alternate deposition half-reactions: ZrCl₄ and H₂O half-reactions. Both the half-reactions proceeded through an analogous trapping-mediated mechanism. Compared to the singly hydroxylated Si surfaces, the neighboring hydroxyl of the doubly hydroxylated Si surfaces has a major effect on ZrCl₄ half-reaction, especially the formation of ZrCl₄ intermediate complex, and a minor effect on H₂O half-reaction. Both ZrCl₄ and H₂O half-reactions were found to follow a similar reaction pathway with IRC method. In addition, the intermediate stability was lowered as the surface temperature was raised. However, increasing temperature also enlarged the dissociation free energy barrier, which in turn resulted in increased desorption of adsorbed precursors.

Key words: atomic layer deposition, density functional theory, high-k gate dielectric, zirconia