The characteristics of HfO 2 films grown on Si substrates using a tetrakis-diethyl-amino-hafnium precursor by the remote plasma atomic layer deposition ͑RPALD͒ and direct plasma ALD ͑DPALD͒ methods were investigated by physical and electrical measurement techniques. The as-deposited HfO 2 layer from RPALD exhibits an amorphous structure, while the HfO 2 layer from DPALD exhibits a clearly visible polycrystalline structure. Medium energy ion scattering measurement results indicate that the interfacial layer consists of the interfacial SiO 2−x and silicate layers. These results suggested that the stoichiometric change in the depth direction could be related to the energetic reactant in a state of plasma used in the plasma ALD process, resulting in damage to the Si surface and interactions between Hf and SiO 2−x . The as-deposited HfO 2 films using RPALD have the better interfacial layer characteristics than those using DPALD. A metal-oxide-semiconductor capacitor fabricated using the RPALD method exhibits electrical characteristics such as equivalent oxide thickness ͑EOT͒ of 1.8 nm with an effective fixed oxide charge density ͑Q f,eff ͒ of ϳ4.2 ϫ 10 11 q/cm 2 and that for DPALD has a EOT ͑2.0 nm͒, and Q f,eff ͑ϳ−1.2ϫ 10 13 q/cm 2 ͒.

The interfacial characteristics of gate stack structure of HfO2 dielectrics on strained Si0.7Ge0.3 deposited by atomic-layer deposition were investigated. An interfacial layer including GeOx layers was grown on a SiGe substrate, and the thickness of the GeOx layer at the interfacial layer was decreased after the annealing treatment, while SiO2 layer was increased. The ∼50-Å-thick HfO2 film with an amorphous structure was converted into a polycrystalline structure after rapid annealing at temperature of over 700 °C for 5 min. The interfacial silicate layer was effectively suppressed by GeOx formation, while the silicate layer was formed after the annealing treatment. GeOx formation in an as-grown film resulted in a decrease in the accumulation capacitance and an increase in the oxide trap charge.

The characteristics of nitrided HfO2 films suggest that the diffusion of Si from the Si substrate to the film surface is induced by annealing in an NH3 ambient and that the incorporation of N is closely related to the diffusion of Si. Changes in the core-level energy state of the N 1s peaks of nitrided HfO2 films indicate that the quantity of N incorporated into the film drastically increases with increasing annealing temperature, especially at temperatures over 900°C. The incorporated N is mostly bonded to Si that diffused from the Si substrate into the film, while some N is incorporated to HfO2 at high annealing temperature. Some molecular N2 is generated in the film, which is easily diffused out after additional annealing. Moreover, the chemisorbed N in the film is not completely stable, compared to that at the interfacial region: i.e., the N in the film predominantly out diffuses from the film after additional annealing in a N2 ambient.

The characteristics of N-incorporated HfO2–Al2O3 alloy films (HfAlO) were investigated by high-resolution x-ray photoelectron spectroscopy (XPS), near-edge x-ray absorption fine structure (NEXAFS), medium-energy ion scattering (MEIS), and capacitance–voltage measurements. The core-level energy states, Hf4f and Al2p peaks of a 15Å thick film showed a shift to lower binding energy, resulting from the incorporation of nitrogen into the films. Absorption spectra of the OK edge of HfAlO were affected mainly by the Al2O3 in the film, and not by HfO2 after nitridation by NH3 annealing. The NEXAFS of NK edge and XPS data related to the chemical state suggested that the incorporated N atom is dominantly bonded to Al2O3, and not to HfO2. Moreover, MEIS results implied that there is a significant incorporation of N at the interface between the alloy film and Si. The incorporation of N effectively suppressed the leakage current without an increase in interfacial layer thickness, while the interfacial state of the N-incorporated films increased somewhat.

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