Abstract
In this thesis, the high-κ oxides of Al2O3 and HfO2 are investigated on Si, InGaAs, Pt, PtOx, and TiN substrates by atomic layer deposition. First, in Chapter 2, we apply the methodology based on the fundamental benefits of ALD to control the Al2O3- and HfO2-ALD process on the H-terminated Si substrate. Growth kinetics, uniformity, composition, deposition rate, and step coverage were optimized to get the best electrical properties of ALD-Al2O3 and -HfO2 films for logic and memory applications. According to the optimization of bulk properties, the ultrathin Al2O3 and HfO2 capacitors were investigated to improve the interfacial properties, e.g., the EOT of IL and Dit, by moderate PDA temperature. Finally, Al2O3 and HfO2 composite structure were investigated. Second, in Chapter 3, an interfacial self-cleaning phenomenon is found in the atomic layer deposition of HfO2 on In0.15Ga0.85As/ GaAs substrate, using Hf(NCH3C2H5)4, i.e. TEMAH, and H2O as the precursors. The native oxides of InGaAs were all satisfactorily removed from the interface through ligand exchange (substitution) reactions with the TEMAH precursor. This relieves the Fermi-level pinning in the HfO2/ InGaAs heterostructure, as verified by the clear transition from accumulation to depletion in high-frequency capacitance-voltage relations and inversion in quasistatic measurement. A very low leakage current was also found from the metal-oxide-semiconductor (MOS) capacitors of Au/ Ti/ HfO2/ InGaAs. Finally, in Chapter 4, ultrathin Al2O3 and HfO2 conformal films of ~7.3 nm thick were successfully grown by atomic layer deposition (ALD) on Pt electrodes in-situ treated with hydrous plasma. The x-ray photoelectron spectroscopy reveals that the Pt surface can be effectively modified to Pt(OH)2 by the hydrous-plasma treatment. This improves the growth of the oxide films and reduces the leakage in the Al2O3 and HfO2 capacitors. The enhancement of chemisorption reactivity of the hydroxylated surface of Pt is responsible for the improvements in the growth and electrical properties of the ALD films.