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Notes: The thermal stability, microstructure, and electrical properties of xZrO2⋅(100−x)SiO2 (ZSO) and xHfO2⋅(100−x)SiO2 (HSO) (x=15%, 25%, 50%, and 75%) binary oxides were evaluated to help assess their suitability as a replacement for silicon dioxide gate dielectrics in complementary metal–oxide–semiconductor transistors. The films were prepared by chemical solution deposition using a solution prepared from a mixture of zirconium, hafnium, and silicon butoxyethoxides dissolved in butoxyethanol. The films were spun onto SiOxNy coated Si wafers and furnace annealed at temperatures from 500 to 1200 °C in oxygen for 30–60 min. The microstructure and electrical properties of ZSO and HSO films were examined as a function of the Zr/Si and Hf/Si ratio and annealing temperature. The films were characterized by x-ray diffraction, mid- and far-Fourier transform infrared (FTIR), Rutherford backscattering spectroscopy, and Auger electron spectroscopy. At ZrO2 or HfO2 concentrations ≥50%, phase separation and crystallization of tetragonal ZrO2 or HfO2 were observed at 800 °C. At ZrO2 or HfO2 concentrations ≤ 25%, phase separation and crystallization of tetragonal ZrO2 or HfO2 were observed at 1000 °C. As the annealing temperature increased, a progressive change in microstructure was observed in the FTIR spectra. Additionally, the FTIR spectra suggest that HfO2 is far more disruptive of the silica network than ZrO2 even at HfO2 concentrations ≤25%. The dielectric constants of the 25%, 50%, and 75% ZSO films were measured and were observed to be less than the linear combination of ZrO2 and SiO2 dielectric constants. The dielectric constant was also observed to increase with increasing ZrO2 content. The dielectric constant was also observed to be annealing temperature dependent with larger dielectric constants observed in nonphase separated films. The Clausius–Mossoti equation and a simple capacitor model for a phase separated system were observed to fit the data with the prediction that to achieve a dielectric constant larger than 10 doping concentrations of ZrO2 would have to be greater than 70%. © 2001 American Institute of Physics.

Notes: Hafnium oxides and hafnium silicate films were investigated as a possible replacement for the SiO2 gate dielectric. Hafnium oxide films were formed by reactive sputtering from a single Hf oxide target in a predominantly Ar atmosphere containing small additions of oxygen. Hafnium silicates were made by adding a He-diluted silane gas for Si incorporation. By changing the silane gas flow, different Si atomic concentrations were incorporated into the Hf oxide films. Depositions were performed with the substrate held at temperatures of 22 °C and 500 °C. The chemical composition of the films was determined with nuclear techniques. Optical reflectivity was used to measure the optical band gap. The film morphology was investigated by transmission electron microscopy (TEM) and the electrical properties were measured with capacitance–voltage and current–voltage measurements using aluminum gate capacitors. TEM and electrical measurement showed that a SiO2 interfacial layer of about 3 nm formed at the Si interface due to the oxidizing sputter ambient. This precluded the growth of Hf based high-K films with small equivalent thickness. After correction for the interfacial oxide layer, the dielectric constant was found to decrease from about 21 for Hf oxide to about 4–5 for the Hafnium silicates with low Hf content (3 at. % Hf and 32 at. % Si). The optical band gap was found to increase from 5.8 eV for Hf oxide to about 7 eV for the silicate films. After annealing at 1000 °C followed by a 300 °C postmetallization anneal, negligible flat band voltage shift were measured on hafnium silicate films and good interface passivation was observed. However, leakage currents increased due to the high temperature processing. © 2001 American Institute of Physics.

Notes: We demonstrate the potential for ultrathin aluminum-oxide films as alternate gate dielectrics for Si complementary metal–oxide–semiconductor technology. Films are deposited in ultrahigh vacuum utilizing atomic beams of aluminum and oxygen on Si(100) surfaces. We show device-quality Si(100)/Al2O3 interfaces with interfacial trap densities in the 1010 cm−2 eV−1 range, and with leakage current densities five orders of magnitude lower than what is observed in SiO2 insulators at the same equivalent electrical thickness. As-grown films possess an amorphous-to-microcrystalline structure, depending upon the deposition temperature, and any interfacial layers between the Si(100) and Al2O3 layer are 〈∼0.5 nm. © 2001 American Institute of Physics.

Notes: Hole injection into silicon dioxide films from the polycrystalline-silicon anode or from the anode/oxide interface is demonstrated to unequivocally occur for any case where electrons are present in the oxide conduction band and where the average electric field in the oxide exceeds 5 MV/cm (thick-film limit) or the voltage drop across the oxide layer is at least 8 V (thin-film limit). The hole generation is directly shown to be related to the appearance of hot electrons with kinetic energies greater than 5 eV in the oxide conduction band near the anode region. Monte Carlo simulations confirm that the electron energy distribution at the anode is the controlling variable and that hot hole injection occurs mostly over the anode/oxide energy barrier. © 1996 American Institute of Physics.

Notes: Remote hydrogen plasma exposure is used to study the transport of atomic hydrogen, H0, through reoxidized-nitrided oxides and SiO2 and to quantify H0-induced degradation of their interfaces with silicon. It is directly demonstrated that (1) H0 is extremely reactive and produces large numbers of interface states; (2) the transport of H0 to the silicon/oxide interface is strongly suppressed in reoxidized-nitrided oxides; and (3) this suppression of the H0 transport is mainly responsible for the much slower interface degradation of reoxidized-nitrided oxides during high-field, hot-electron stress as compared to thermal oxide.

Notes: We have developed an electron lithography method, hot electron emission lithography, which is capable of printing integrated circuits with an exposure time of only a few seconds. The basic design and fabrication of the patterned electron emitting mask made by standard metal–oxide–semiconductor technology will be discussed, and its applicability in a simple 1:1 e-beam stepper will be demonstrated. Patterns with a minimum feature size of 160 nm have been printed successfully. Further improvements in resolution to 50 nm appear to be possible. © 1998 American Institute of Physics.

Notes: Leakage currents introduced in the low-field, direct-tunneling regime of thin oxides during high-field stress are related to defects produced by hot-electron transport in the oxide layer. From these studies, it is concluded that the "generation'' of neutral electron traps in thin oxides is the dominant cause of this phenomenon. Other mechanisms due to anode hole injection or oxide nonuniformities are shown to be unrealistic for producing these currents. Exposure of thin oxides to atomic hydrogen from a remote plasma is shown to cause leakage currents similar to those observed after high-field stress, supporting the conclusion that these currents are related to hydrogen-induced defects. © 1995 American Institute of Physics.

Notes: Degradation of silicon dioxide films is shown to occur primarily near interfaces with contacting metals or semiconductors. This deterioration is shown to be accountable through two mechanisms triggered by electron heating in the oxide conduction band. These mechanisms are trap creation and band-gap ionization by carriers with energies exceeding 2 and 9 eV with respect to the bottom of the oxide conduction band, respectively. The relationship of band-gap ionization to defect production and subsequent degradation is emphasized. The dependence of the generated sites on electric field, oxide thickness, temperature, voltage polarity, and processing for each mechanism is discussed. A procedure for separating and studying these two generation modes is also discussed. A unified model from simple kinetic relationships is developed and compared to the experimental results. Destructive breakdown of the oxide is shown to be correlated with "effective'' interface softening due to the total defect generation caused by both mechanisms.

Notes: Based on theoretical studies of tunneling current phenomenon, a method for measuring barrier heights in metal–oxide–semiconductor structures is illustrated. Using this method, barrier heights associated with the Al2O3 gate dielectric films are investigated. Also, the main conduction mechanism in Al2O3 gate dielectric films is identified to be tunneling. © 2002 American Institute of Physics.