Si was oxynitrized (and/or nitrized) in both helicon-wave-excited and inductively-coupled N2 or N2+Ar mixed plasma. Fairly good capacitance-voltage (C–V) characteristics were obtained after post-thermal annealing at 400°–500°C for 30 min in nitrogen ambient. X-ray photoelectron spectroscopic (XPS) measurements showed that chemically stoichiometric Si oxynitride, Si2 N2 O, was uniformly formed throughout the whole film thickness at a flow-rate ratio of N2 of 80% in a N2 + Ar mixed plasma (N2:Ar = 8:2). On the other hand, SiO2 was formed at the outer surface while Si2 N2O was formed in the middle portion of the film and near the interface between the grown film and Si, when the flow-rate ratio of N2 was less than about 80%. The growth rate and the degree of “nitridation" were maximum at flow-rate ratio of N2 of 80%. The leakage current in the film was found to be mainly the Fowler-Nordheim-type tunneling current.
The decompression stage of a relativistic heavy ion reaction is described within a Monte-Carlo-Time-Dependent-Hartree-Fock model suitable for quantum dynamical calculations. Temperature and compression effects lead to instabilities and nuclear disassembly. Low excited stable and high excited unstable fragments are generated. The model is based on a Monte-Carlo simulation. A statistical set of self-consistent Hartree calculations are performed. Systems with different particle number are studied. At critical break-up temperatures fragments are found in U-shaped spectra. Above the break-up threshold fast and small fragments are counted. Below the break-up threshold the excited matter shows vibrational modes. Density distributions are studied and evidence for volume dependent multifragmentation processes is obtained for most break-up temperatures. Mass spectra, multiplicities and momentum distributions are presented.
High-quality Si dioxide was successfully grown at room temperature using a magnetically excited plasma oxidation technique. Helicon waves were probably excited under the growth conditions used. Excellent capacitance-voltage characteristics were obtained after annealing of these oxide films in oxygen ambient for 15 min at 300°–500°C. The growth rate was somewhat low. However, the film thickness increased substantially with annealing. X-ray photoelectron spectroscopic studies indicated that high-quality Si oxides without suboxides were grown even at room temperature.
Good electrical quality Si oxynitride was successfully grown at room temperature using magnetically excited ( N2 + Ar) plasma. Si oxynitride, probably Si\SubtN\SubtO, was grown only when Ar was mixed with N2, while SiO\Subt was solely formed with N2 only. At the top surface of the grown film with mixed gas, SiO\Subt was always grown due to residual oxygen in N2 gas, so that the SiO\Subt/Si\Subt N2O structure was always obtained. Good capacitance-voltage characteristics were obtained although the growth rate was somewhat low. The ( N2 + Ar) plasma treatment after deposition of Si\SubsN\Subf powder on Si was also discussed.
Pulsed Fowler–Nordheim (FN) current stress resistance was investigated for the Si oxynitride grown in the helicon-wave excited N2–Ar plasma. The shift of the gate threshold voltage Vth increased with an increase in the pulse frequency for both polarities of the applied stress voltage. At low frequencies (<1 kHz), the Vth shift was larger for the negative gate-voltage stress than for the positive one. However, as the frequency exceeds about 1 kHz, the Vth shift become much higher for the positive stress than for the negative one. The Vth shift was smaller as the pulse duty ratio was larger. These findings could be explained with the surface–plasmon and avalanche breakdown models combined with the effect of the total amount of the injected carriers to the oxynitride from the Si substrate or the gate electrode. The effect of Ar ion etching during plasma processing on the FN stress resistance was also investigated. The Ar ion etching effect was found to be substantially reduced as the plasma-sheath width was large and Si oxynitride samples were grown under this condition. The mean time to failure was highly improved by the Si oxynitride samples grown under the condition of reduced Ar ion etching effect.
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