We studied the interaction of Bis-diethylaminosilane (SiH2[N(C2H5)2]2, BDEAS) with a hydroxylized Si (001) surface for SiO2 thin-film growth using density functional theory (DFT). BDEAS was adsorbed on the Si surface and reacted with the H atom of hydroxyl (-OH) to produce the di-ethylaminosilane (-SiH2[N(C2H5)2], DEAS) group and di-ethylamine (NH(C2H5)2, DEA). Then, DEAS was able to react with another H atom of -OH to produce DEA and to form the O-(SiH2)-O bond at the inter-dimer, inter-row, or intra-dimer site. Among the three different sites, the intra-dimer site was the most probable when it came to forming the O-(SiH2)-O bond.

In this paper, we proposed a new high-rate oblique deposition method using two sputtering sources to obtain SiO2 films for a liquid crystal alignment layer. One sputtering source that operates in a metal mode supplies Si atoms to a substrate, and the other source that operates in an oxide mode supplies oxygen radicals to a substrate. To reduce the gas pressure of a deposition chamber and make the two sputtering sources operate in different modes, the sputtering sources were separated from the deposition chamber with stainless meshes, and Ar and oxygen gases were introduced separately through the two sputtering sources, i.e., Ar gas was introduced through the Si supply source and oxygen gas was introduced through the oxygen radical source. When Ar gas of 30 sccm and oxygen gas of 4 sccm were introduced into the system, the gas pressure of the deposition chamber was maintained below 1.7 mTorr and the films deposited at an incidence angle of more than 70 showed an elongated inclined columnar structure. Under this condition, a deposition rate of 30 nm/min was realized even at an incidence angle above 70, where most of the Si atoms incident to the substrate were supplied by the Si supply source and the oxygen radical source supplied oxygen radicals and promoted the oxidation of the film.

The physical origin of stress-induced leakage currents (SILC) in ultra-thin SiO2 films is described. Assuming a two-step trap-assisted tunneling process accompanied with an energy relaxation process of trapped electrons, conditions of trap sites which are origin of SICL are quantitatively found. It is proposed that the trap site location and the trap state energy can be explained by a mean-free-path of hole in SiO2 films and an atomic structure of the trap site by the O vacancy model.

Hetero-interface properties of SiO2/4H-SiC on (0001), (11-20), and (03-38) crystal orientations are presented. Epitaxial growth on new crystal orientations, (11-20) and (03-38), is described by comparing with the growth on (0001). Using thermal oxidation with wet oxygen, metal-oxide-SiC (MOS) structure was fabricated. From high-frequency capacitance-voltage characteristics measured at 300 K and 100 K, the interface properties were characterized semi-quantitatively. The interface state density was precisely determined using the conductance method for the MOS structure at 300 K. The new crystal orientations have the lower interface state density near the conduction band edge than (0001). From the characteristics of inversion-type planar MOSFETs, higher channel mobilities were obtained on (03-38) and (11-20) than on (0001). The cause of the difference in the channel mobility is speculated by the difference bond configuration of the three crystal orientations.

Gallium nitride (GaN) is one of the wurtzite-type materials and has semiconducting properties. Crystallinities of GaN thin films are usually poor when they are directly grown on polycrystalline metal-foils which are expected as substrates for realizing novel giant microelectronic devices. Improvements of crystal orientations of GaN thin films grown on such polycrystalline metal-foils are tried by using several kinds of intermediate layers. Aluminum nitride (AlN), GaN, silicon dioxide (SiO2) and Si are chosen as materials for the intermediate layers. The crystal orientations of GaN thin films grown by inserting the SiO2 and Si intermediate layers with adequate thicknesses are markedly improved, while those grown on the AlN or GaN intermediate layers are not improved. These differences are not caused by the kinds of the materials used for the intermediate layers but by differences in their crystallinities.

The effect of the silicone vapor on the reliability of the micro-motor was examined. Adsorbed silicone was decomposed to SiO2 by heating due to the discharge between brush and commutator surface. It was found that the operation time until the failure was extremely shortened by the formation of SiO2. The existence of the maximum operation time until the failure was found as depending on the number of revolution. For the higher revolution, many amounts of SiO2 accumulated by the decomposition of the silicone shorten the operation time. For lower revolution, as the torque of the motor reduces, the operation time also shortens. Therefore, the maximum operation time exists for optimum revolution.

We demonstrated apertureless scanning near-field optical microscopy using a small protrusion (a simple 500-nm-diameter polystyrene particle) on a flat glass substrate as a probe. We designed a small sample stage to operate with the particle probe. It is a 40-µm-diameter circular stage, fabricated from an optical fiber by Hydrofluoric acid (HF) etching. In this paper, we present the first atomic force microscope and scanning near-field optical microscope images obtained with such a probe. We also discuss schemes for probe-sample distance control in this novel form of apertureless scanning near-field optical microscopy.

We report, in this paper, on a combined process of photo-oxidation and PECVD using TEOS and O2 gases to produce an SiO2 gate insulator for poly-Si TFTs. Light of 172 nm-wavelength from a Xe excimer lamp generates active oxygen radicals efficiently and selectively without producing ozone. These oxygen radicals efficiently oxidize silicon. In contrast to plasma oxidation, photo-oxidation offers the ability to produce gate oxides without ion bombardment. Oxide-silicon interfaces with interface trap densities of 2-3 1010 cm-2 eV-1 were obtained by photo-oxidation at 200-300. A stack structure was produced using 4.3-nm-thick photo-oxide topped with a 40-nm-thick PECVD oxide film deposited at 300. This stack structure without annealing exhibited excellent interface behavior and the same J-E characteristics as a 100-nm-thick PECVD film annealed at 600.

Electroluminescence (EL) under alternating-current (ac) operation is first reported for n+-polysilicon/SiO2/p-Si MOS capacitors with 50 nm Si-implanted SiO2. Visible EL can be observed with the naked eye in the dark. The ac operation by pulse-wave distinctly enhances the EL intensity and its lifetime. The pulse frequency affects the EL spectrum and thus the EL color. A model of EL mechanism is proposed for the Si-implanted MOS EL device, which has a possibility of visible light emitting device.

SiO2-added Ba ferrite (BaM:SiO2) films were prepared using BaFe12Si0.18Ox targets. BaM:SiO2 films exhibited perpendicular coercivity Hc⊥ of over 4.2 kOe and squareness ratio of 0.83, although saturation magnetization Ms decreased by about 15%. The angular dependence of coercivity Hc and remanent coercivity Hr were investigated to explain the magnetization reversal mechanism. Intergranular interactions in the films were also evaluated. The magnetization reversal mode of Ba ferrite films with and without SiO2 additives is not coherent rotation but appears to be the curling mode. The origin of the high coercivity of BaM:SiO2 films is different from that of Al-substituted Ba ferrite films. It seemed that SiO2 additives and the defects caused by them decreased Ms and prevented the expansion of reversed domains in the magnetization reversal process, similarly to some pinning effects, and caused high Hc⊥ of 4.2-5.1 kOe in BaM:SiO2 films.

Silicone contamination due to SiO2 caused by decomposition of silicone vapor is recognized as an undesirable phenomenon in electrical contact applications. The effects of silicone vapor adsorbed on the contact surface were examined by using micro relay contacts. The amount of SiO2 formed by the decomposition of silicone vapor is expected to depend on the amount of silicone vapor adsorbed on the contact surface. Hence, first of all, an increase in the thickness of the film from the adsorbed silicone vapor as a function of exposure time was clarified for the static state of the surface. The thickness of the film of adsorbed silicone vapor increased in proportion to exposure time and saturated at a thin monolayer. Moreover, in this exposure period, the thickness was affected by the concentration of the silicone vapor. After the thickness of the molecular layer saturated, the thickness of the layer was not influenced by the concentration of the silicone vapor. Next, from these results obtained by examination of exposure in the static state, the following is deducible. The silicone molecule adsorbs easily on the contact surface during the opening period of making and breaking contacts as well as in the static state. As the time the contacts are open determines the exposure time, the amount of adsorbed silicone molecules depends on the switching rate (operation per second). Contact failure due to increases in contact resistance might be affected by the switching rate in a silicone environment. Accordingly, contact resistance characteristic was examined over a wide range of switching rates. It was found that number of operations up to contact failure was affected markedly by the switching rate. Namely, the number of operations up to contact failure decreases as the switching rate increases. However, once a very thin layer such as the monolayer has formed, the film thickness ceases to grow. Accordingly, after the very thin layer is formed, the occurrence of contact failure does not depend on the concentration of silicone and the switching rate.

Photonic crystals have optical properties characterized by photonic bandgap, large anisotropy and high dispersion, which can be applied to various optical devices. We have proposed an autocloning method for fabricating 2D or 3D photonic crystals and are developing novel structures and functions in photonic crystals. The autocloning is an easy process based on the combination of sputter deposition and sputter etching and is suitable for industry. We have already demonstrated devices or functions such as polarization splitters and surface-normal waveguides. In this paper, we describe our latest work on photonic crystals utilizing the autocloning technology. Phase plates and polarization selective gratings for optical pick-ups are demonstrated utilizing TiO2/SiO2 photonic crystals. The technology to introduce CdS into 3D photonic crystals is also developed and photoluminescence from the introduced CdS is observed, which is the first step to realize luminescent devices with 3D confinement or high polarization controllability.

Peculiar patterns of SiO2 contamination around the periphery of the contact trace caused by silicone vapor under switching at the boundary of 1.6 W were confirmed. For micro relays, the electrical power conditions are restricted to lower level. Therefore, it is important to ascertain the upper limit of the electrical power conditions for normal operation. The peculiar pattern is important as it is recognized as the first stage of the origination of contact failure. Causes of this pattern were discussed from the viewpoints of temperature distribution in the contact trace, molten metallic bridge, micro arc discharge, and supply of silicone vapor with oxygen. It is proposed that during the closing contacts, as maximum Joule heating occurs at the periphery of the true contact area and silicone vapor with oxygen is easily supplied at the periphery, SiO2 grows around the contact trace. For the opening contacts, as the bridge or micro arc appears, silicone vapor with oxygen is supplied only outside of the contacts. Thus SiO2 is formed mainly around the periphery of the trace. Moreover, SiO2 was scattered radially depending on the sputtering of molten metal under rupture of the bridge. Therefore, the peculiar pattern forms as a result.

Degradation of metal-oxide-semiconductor field-effect transistors (MOSFETs) reliability such as the relative transconductance reduction by plasma exposure is evaluated. The linear region peak transconductance (gm) decreases with antenna ratio (exposed antenna area/gate area) due to the plasma-induced Si-SiO2 interface state generation. The Si-SiO2 interface-related gm reduction which is defined as (gm0gm)/gm, where gm0 is the initial value of gm, decreases as the gate oxide thickness decreases. It is also found that the decreasing amount of gm depends on the conduction current from the plasma. The correlation between the (gm0gm)/gm and the plasma-induced reduction of charge-to-breakdown of the gate oxide with a constant current stress (ΔQBD) is observed, and the result shows that the gm reduction of nMOSFET during the plasma process is severe to the plasma-induced damage compared with the gate oxide breakdown.

We studied the selective epitaxy of GaAs grown by a technique called pulsed-jet epitaxy. Pulsed-jet epitaxy is a kind of atomic layer epitaxy (ALE) based on low-pressure metalorganic vapor-phase epitaxy (MOVPE). We compared growth behavior and layers grown by ALE and MOVPE. During ALE we supplied trimethylgallium (TMGa) and arsine (AsH3) alternately; however, during MOVPE we supplied TMGa and AsH3 simultaneously. At a growth temperature of 500, we obtained a better growth selectivity using ALE than using MOVPE. The lateral thickness profile of the ALE-grown GaAs layer at the edge of SiO2 mask was uniform. In contrast, the MOVPE growth rate was enhanced near the mask edge. Using ALE, we selectively grew GaAs epilayers even at mask openings with submicron widths. Scanning electron microscopy revealed that the ALE selectively grown structures had an uniform thickness profile, though the facets surrounding the structures depended on the orientation of mask stripes. After MOVPE, however, the (001) surface of the deposited layer was not flat because of the additional lateral diffusion of the growth species from the gas phase and/or the mask surface and some crystal facets. The experimental results show that, using ALE, we can control the shape of selectively grown structures. Selective epitaxy by ALE is a promising technique for fabricating low-dimensional quantum effect devices.

This paper describes a nondestructive measurement method for complex permittivity of dielectric material at pseudo microwave frequencies. The resonator used in this study has a cylindrical cavity filled with a sapphire material of a well known complex permittivity. The resonator is divided into two parts at the center. A dielectric substrate specimen is clamped with these halves. Relative permittivity εand loss tangent tan δ of the specimen are obtained at 3 GHz using the TE011 resonance mode. The accuracy of the present method is evaluated through the comparison of the measured values by the new method with those at around 10 GHz by the conventional empty cavity resonator method. The errors of measurements are smaller than 1% and 1105 for εand tan δ, respectively.

This paper describes the formation of ultra-thin tantalum oxide capacitors, using rapid thermal nitridation (RTN) of the storage-node polycrystalline-silicon surface prior to low-pressure chemical vapor deposition of tantalum oxide, using penta-ethoxy-tantalum [(Ta(OC2H5)5) and oxygen gas mixture. The films are annealed at 600-900 in dry O2 atmosphere. Densification of the as-deposited film by annealing in dry O2 is indispensable to the formation of highly reliable ultra-thin tantalum oxide capacitors. The RTN treatment reduces the SiO2 equivalent thickness and leakage current of the tantalum oxide film, and improves the time dependent dielectric breakdown characteristics of the film.

Two kinds of nitrided ultrathin (510 nm) SiO2 films were formed on the silicon (100) face using rapid thermal NH3-nitridation (RTN) and rapid thermal N2O-oxynitridation (RTON) technologies. The MOS capacitors with RTN SiO2 film showed that by Fowler-Nordheim (F-N) electron injection, both electron trap density and low-field leakage increase by the NH3-nitridation. In addition, the charge-to-breakdown (QBD) value decreases owing to NH3-nitridation. By contrast, RTON SiO2 films exhibited extremely low electron trap density, almost no increase of the leakage current, and large QBD value above 200C/cm2. The oxide film composition was evaluated by secondary ion mass spectroscopy (SIMS). The chemical bonding states were also examined by Fourier transform-infrared reflection attenuated total reflectance (FT-IR ATR) and X-ray photoelectron spectroscopy (XPS) measurements. These results indicate that although a large number of nitrogen (N) atoms are incorporated by the RTN and RTON, only the RTN process generates the hydrogen-related species such as NH and SiH bounds in the film, whereas the RTON film indicates only SiN bonds in bulk SiO2. From the dielectric and physical properties of the oxide films, it is considered that the oxide wearout by high-field stress is the result of the electron trapping process, in which anomalous leakage due to trap-assisted tunneling near the injected interface rapidly increases, leading to irreversible oxide failure.

A glass precursor resist (GPR) is designed on the basis of an idea of conversion of organosilicon polymer to an inorganic substance by lithographic procedure. Developed chemical amplification resist system is composed of poly (di-t-butoxysiloxane) and a photoacid generator. It has a high sensitivity of 1.6 µC/cm2, a resolution of 0.2 µm and an extremely high O2-RIE durability compared with bottom resist. Exposed film changed into silicate glass, and it was confirmed by IR spectra.

Reaction mechanisms in remote plasma CVD (in which plasma excitation of source meterials and film deposition are spatially separated) of SiO2 using activated oxygen species and pure silane (SiH4) were discussed in two destinct cases in a viewpoint of vapor phase reactions. Under high pressures of 50500 mTorr, activated oxygen species and SiH4 could collide with each other many times in the vapor phase. SiH4 was decomposed by chemical reactions due to the collisions generating chemically active precursors such as SiHn (0n3) for film deposition. Nearly stoichiometric films with low hydrogen content were obtained at low temperatures of around 300. Under a pressure of 5 mTorr, the oxygen species and SiH4 could scarcely collide with each other due to a long mean free path resulting no decomposition of SiH4. Insufficient surface reactions between relatively stable SiH4 and activated oxygen species yielded many O-H bonds in deposited films. Electrical properties of the films and the interfaces of SiO2/Si were characterized.