On the Mechanisms of SiO2 Thin-Film Growth by the Full Atomic Layer Deposition Process Using Bis(t-butylamino)silane on the Hydroxylated SiO2(001) Surface

With the continuing miniaturization of electronic devices, the atomic layer deposition (ALD) technique has become the preferred choice for the deposition of dense, conformal thin films. Efficient precursors that enable low-temperature deposition processes are of critical importance to ensure high-quality thin films with low impurity levels. Herein, we present a first-principles study on a full cycle of an ALD process using bis(t-butylamino)silane (BTBAS) as the precursor for developing a SiO2 thin film on the hydroxylated SiO2(001) surface with ozone as the oxidizing agent. Two possible deposition pathways were systematically studied. One leads to crystalline growth of the film, and the other gives rise to disordered growth layers. Detailed elementary processes on the surface of the substrate and the associated energetics were examined. We show that the crystalline growth pathway is thermodynamically more favorable, but the disordered growth pathway is kinetically more facile. Given enough time to settle, the BTBAS molecule will fully react with the substrate, leaving essentially few impurities on the surface. Our results suggest that BTBAS is a highly efficient precursor for growing dense and conformal SiO2 thin films with the ALD technique.