Silicon dioxide (SiO 2) films deposited using Atomic Layer Deposition (ALD) technique from tris(dimethylamino)silane (TDMAS) and ozone as precursors on Si(100) surfaces at room temperature were investigated by infrared absorption spectroscopy with a multiple internal reflection geometry. TDMAS dissociatively adsorbs on OH sites of hydroxylated Si surfaces and ozone irradiation is effective to remove the hydroaminocarbon adsorbates introduced during the TDMAS adsorption. After the ozone treatment, treatments with H 2O vapor at substrate temperatures around 160°C allow regeneration of OH sites for the TDMAS adsorption. The TDMAS adsorption and the ozone treatment at room temperature followed by the H 2O treatment at 160 °C enable the cyclic deposition of SiO 2. I-V measurements performed on MOS capacitors with SiO 2 films reveal that the deposited films have breakdown electric fields in the range 3-11 MV/cm. These measurements together with C-V measurements indicate that the present ALD technique is suitable for the deposition of SiO 2 films for MOS capacitors.