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Hafnium oxide thin films were deposited using both the remote-plasma atomic layer deposition (RPALD) and direct-plasma atomic layer deposition (DPALD) methods. Metal-oxide semiconductor (MOS) capacitors and transistors were fabricated with HfO2 gate dielectric to examine their electrical characteristics. The as-deposited RPALD HfO2 layer exhibited an amorphous structure, while the DPALD HfO2 layer exhibited a polycrystalline structure. Medium-energy ion scattering measurement data indicate that the interfacial layer consisted of interfacial SiO2-x and silicate layers. This suggests that the change in stoichiometry with depth could be related to the energetic plasma beam used in the plasma ALD process, resulting in damage to the Si surface and an interaction between Hf and SiO2-x. The as-deposited RPALD HfO2 films had better interfacial layer characteristics, such as an effective fixed oxide charge density (Qf,eff) and interfacial roughness than the DPALD HfO2 films did. A MOS capacitor fabricated using the RPALD method exhibited an equivalent oxide thickness (EOT) of 1.8 nm with a Qf,eff=-4.2×1011 q/cm2 (where q is the elementary charge, 1.6022×10-19 C), whereas a MOS capacitor fabricated using the DPALD method had an EOT=2.0 nm and a Qf,eff=-1.2×1013 q/cm2. At a power=0.6 MV/cm, the RPALD n-type metal-oxide semiconductor field-effect transistor (nMOSFET) showed μeff=168 cm2/V s, which was 50% greater than the value of the DPALD nMOSFET (μeff=111 cm2/V s). In the region where Vg-Vt=2.0 V, the RPALD MOSFET drain current was about 30% higher than the DPALD MOSFET drain current. These improvements are believed to be due to the lower effective fixed charge density, and they minimize problems arising from plasma charging damage. [ABSTRACT FROM AUTHOR]

The electrical characteristics of n-GaN/nitrided-thin-Ga2O3/SiO2 and n-GaN/Si3N4 metal-insulator-semiconductor (MIS) capacitors have been compared, and the work-function difference [lowercase_phi_synonym]ms and effective dielectric-fixed charge density Qf,eff have been determined. Oxide samples showed lower interface trap level density Dit, lower leakage current, and better reproducibility compared to the nitride samples. The superior properties of the oxide samples are partially attributed to the nitrided-thin-Ga2O3 layer (∼0.6-nm-thick). [lowercase_phi_synonym]ms and Qf,eff were determined, respectively, as 0.13 V and 1.0×1012 q cm-2 in oxide and 0.27 V and -3.6×1011 q cm-2 in nitride samples using flatband voltage versus dielectric thickness data. True dielectric-fixed charge density and location of the major amount of fixed charge are discussed based on Qf,eff, Dit, and spontaneous polarization of n-GaN. [ABSTRACT FROM AUTHOR]

The electrical characteristics of n-GaN/nitrided-thin-Ga2O3/SiO2 and n-GaN/Si3N4 metal-insulator-semiconductor (MIS) capacitors were compared. Oxide samples showed lower interface trap level density D (sub it), lower leakage current, and better reproducibility compared to the nitride samples.

The characteristics of HfO2 films grown on Si substrates using a tetrakis-diethyl-amino-hafnium precursor by the remote plasma atomic layer deposition (RPALD) and direct plasma ALD (DPALD) methods were investigated by physical and electrical measurement techniques. The as-deposited HfO2 layer from RPALD exhibits an amorphous structure, while the HfO2 layer from DPALD exhibits a clearly visible polycrystalline structure. Medium energy ion scattering measurement results indicate that the interfacial layer consists of the interfacial SiO2-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 SiO2-x. The as-deposited HfO2 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 (EOT) of 1.8 nm with an effective fixed oxide charge density (Qf,eff) of ∼4.2×1011 q/cm2 and that for DPALD has a EOT (2.0 nm), and Qf,eff(∼-1.2×1013 q/cm2). [ABSTRACT FROM AUTHOR]

We investigated the effects of Al2O3 thickness on the suppression of parasitic substrate oxidation in HfO2–ultrathin-Al2O3–Si structures. The use of H2O as oxidizing agent in the atomic layer deposition (ALD) chemistry is considered key to preventing the formation of an SiOx interlayer during oxide deposition. An Al2O3 layer prepared with 10 cycles of atomic layer deposition (ALD, ∼0.74 nm) effectively suppressed substrate oxidation during rapid thermal annealing in N2 for 10 s below 800 °C. Parasitic oxidation was observed at 600 °C for samples with only five cycles or without Al2O3. Ultrathin Al2O3 films can be relevant for the integration of HfO2 as gate dielectric in silicon technology. [ABSTRACT FROM AUTHOR]

In most previous reports on Al-gated n-GaN/SiO2 metal oxide semiconductor (MOS) structures, the work-function difference between A1 and n-GaN (φms) has been chosen as 0 V by assuming that the work function of the A1 gate and n-GaN are both 4.1 eV. In this letter, φms is determined as ∼0.1 V using Al-gated n-GaN/nitrided-thin-Ga203/SiO2 MOS capacitors by measuring flatband voltage as a function of oxide thickness. Formation of an ultrathin (∼0.6-nm-thick) Ga203 layer on n-GaN prior to the deposition of SiO2 is important to prevent uncontrolled parasitic oxidation of the n-GaN surface and possibly reduces the interface dipole between n-GaN and SiO2. [ABSTRACT FROM AUTHOR]