The thermal oxidation of amorphous silicon-boron alloy (prepared by low pressure chemical vapor deposition) with boron contents ranged from 0–40% at a temperature range of 25- 700 °C has been carried out. Crystalline silicon and polycrystalline boron have also been studied for comparison purposes. The resultant thin oxide overlayers were characterized by X-ray photoelectron spectroscopy. It was found that both the oxidation of Si and of B are enhanced by mixing of the two elements. The oxidation of boron is significantly slower than silicon. During oxidation of silicon-boron alloy, preferential oxidation of silicon occurs at the oxide/bulk interface and the silicon oxide overlayer advances into the bulk faster than the boron oxide.

Breakdown voltage, static current-voltage, spectroscopic ellipsometry (SE), electrolyte electroreflectance (EER) and high resolution transmission electron microscopic (HRTEM) studies of thermally grown thin films of SiO2 on silicon (800°C - dry) are reported here. The investigation of the electrical properties of these films lead us to suggest the criteria for determining the breakdown voltage of these 20nm thick SiO2 films. The Fowler-Nordheim tunneling contribution to current conduction mechanisms in SiO2 has been considered in evaluating these criteria. SE, EER & HRTEM studies have been performed on SiO2 films of thicknesses in the range of 1–20 nm. These studies lead us to determine the thickness of the non-stoichiometric silicon-rich oxide existing at the Si-SiO2 interface. EER studies show that the relative surface state densities for different film thicknesses can be determined. The role of the transition region in determining the dielectric strength of thin SiO2 films is discussed.

While low levels of optical absorption are easily measured in SiO2 bulk samples or optical fibers, we present here a method of detirmining low levels of absorption in thin films of SiO2. Films are deposited on top of high reflectivity multi-layer miriors, and absorption is derived from the time decay in a resonant cavity of threj mirrorsgt 633 nm. Absorption coefficients on the order of 1 cm−1. (k = 10−5) can be measured in films as thin as 100 Angstroms.

With this method, we find that absorption at 633 nm can be induced in SiO2 films by exposing them to a He-Ne plasma discharge. Although the plasma radiation (>10 eV) is absorbed near the SiO2 surface, the plasma-induced absorption is uniform within the SiO2 film. This was shown by plasma irradiation of SiO2 films of 4arying thickness, together with computer calgulation of the optical properties of multilayer thin films. Similar absorption behavior has been reported in SiO2 optical fibers and may be due here to DIA (Drawing-Induced Aisorption) centers or NBOHCs (Non-Bridging Oxygen Hole Centers).

The self-consistent electronic structures and total energies for the crystalline α-SiO2 and β-Si3N4 are studied by means of the first-principles orthogonalized linear combination of atomic orbitals method. The calculated band structures are compared with the earlier non-self consistent results. The total energies in the local density approximation are evaluated as a function of lattice parameters. Reasonable values of equilibrium lattice constants and cohesive energies are obtained but the bulk modulus for α-SiO2 is overestimated.

Till now the only effective method of direct determination of structural parameters has been X-ray diffraction structural analysis. This method applied to crystalline materials has proved a great success and applied to noncrystalline substances like for example inorganic glasses, is becoming more and more successful.

Beginning with the W. Ostwald proposition /1913/ carried out by W. Friedrich /1913/ and P. Debye /1915/ through the papers by B.E. Warren et al. /1934–1942/ or by E.A. Poray-Koshits et al. /1934–1942/ till the most recently published papers devoted to structural studies of noncrystalline /amorphous/ materials we follow a significant progress in technology and methodology of these studies.

The resulting significant improvement to the accuracy of results yields much more accurate structural models of non-crystalline materials.

Polysilicon films with high oxygen content (SIPOS) have been prepared by LPCVD. These films have a two-phase structure with silicon crystallites surrounded by amorphous oxide, as confirmed by TEM and HRTEM measurements. Increasing the ratio of nitrous oxide to silane, R, during growth allows us to vary the oxygen concentration. Contrary to expectation, we observe a region where conduction increases as R is increased from 1 to 10. This can be accounted for by deviations from monotonicity in the dependence of silicon volume fraction on R. We also observe some influence of the SIPOS/silicon interface on conduction.

High quality, 20 to 30 nm thick SiO2 films were grown using rapid thermal oxidation techniques. Metal-oxide-semiconductor (MOS) capacitors formed with these oxides were characterized electrically using low and high frequency capacitance measurements. The effects of post oxidation annealing (POA) ambient, temperature and duration on the initial oxide properties and the radiation response of the MOS capacitors were determined. The addition of a small amount of O2 to the POA ambient significantly reduced the radiation induced hole trapping and interface state creation, particularly for the higher POA temperatures. In addition, annealing and reirradiation experiments were carried out and showed that both the trapped charge and interface state buildup were completely reversible after anneals at 400°C. This repeatability argues against interface state creation models which involve irreversible changes in the atomic arrangements near the interface.

The degradation and charge build-up of thermally grown silicon diozide layers (with thicknesses varying between 20 and 40 nm) during various stress experiments was investigated. The slow trapping instability generated during charge injection was demonstrated to originate from initially present hole traps. The generation of electron traps in the oxide layer close to the non-injecting interface during high-field stressing was established both for Al-gate and poly-Si gate structures. No evidence could be found for the generation of hole traps during high-field stressing. No bulk oxide charges were detected after a high-field stress, but only unstable near-interface charge trapping was evidenced.

A new spin resonance spectrum has been observed with electron paramagnetic resonance in thermal oxides grown on (111) silicon. Our analysis indicates that this new spectrum consists of two isotropic resonances. One resonance has a g-value of 2.0026 and a linewidth (FWHM) of 1.2 G (labeled SL8); the other resonance has a g-value of 2.0029 and a linewidth (FWHM) of 5 G (labeled SL9). These spectra might be due to impurity contamination resulting from the oxidation process and associated with defects at interior surfaces. The SL8 resonance in particular appears to be located within the as-grown thermal oxide. The effects of 60Co gamma irradiation and annealing in either hydrogen or ammonia on these spectra are also presented in this paper.

We report parameter-free self-consistent calculations of structural properties for the oxygen vacancy in silicon-dioxide using new oxygen pseudopotentials and quantum molecular dynamics simulations. Results challenge the accepted identification of the oxygen vacancy with the paramagnetic E1′ center. Bonding of the adjacent silicon atoms occurs sufficiently strongly for all charge states to inhibit the asymmetric distortion which would be required for correspondence with the E1′ center.

We have performed electronic structure studies on two neutral oxygen vacancies in crystalline silicon dioxide. The idealized beta-crystobalite structure has been used as a model for the host perfect crystal. The calculations have been carried out by representing the host-defect system as a large cluster of atoms which is properly. embedded into the host crystal, with a Gaussian orbital basis used to describe the electronic states of the host and defect systems. The local density approximation with and without the self-interaction correction has been used in these calculations.

We study the behavior of the spatial and energetical distribution of the slow Si-SiO2 interface states ( i.e. the defects located in the strained SiO2 layer near the interface) when the Metal-oxide-semiconductor (MOS) structure is submitted to a high field electrons injection from the Si substrate. We have analysed the creation kinetics of these slow states in order to compare with the behavior of the fast interface states which are better studied. We demonstrate that the fast interface states are more rapidly generated than the slow states and that the creation kinetics of fast states reach a saturation at lower injected charge. We also find that the fast interface states generation is independent from the energetical location of the states in the Si bandgap. For the generation of slow states, we observe a weak dependence on the energetical location of the defects in the SiO2 bandgap, and a strong dependence on the depth location from the Si-SiO2 interface.

The effects of the heat treatment of Si covered with a thermally-grown ˜50 nm overlayer of SiO2 were probed by means of measurements of positron annihilation characteristics obtained with a variable-energy positron beam. From measurements at elevated temperature (˜500°C) it was observed that positrons implanted overlapping the SiO2/Si interface decay from a state with properties distinctively different from the state in Si and in SiO2. The nature of the annihilation characteristics indicates the presence of open volume defects.

A newly developed optical surface characterization technique using the diffuse scattered light of two laser beams will be presented. The method determines root-mean-square roughness values (RMS) of surfaces down to 1 Å and corresponding correlation lengths in the submicron area.

Interfaces between two kind of substrate, a bulk silicon wafer and a laser-recrystallized Silicon-On-Insulator (SOI), and its thermally grown oxide have been studied. High resolution transmission electron microscopy (HRTEM) of cross sectional specimen shows that the roughness at the interface is atomically flat and nearly uniform for the bulk single crystal silicon and silicon oxide, while being nonuniform and rough as much as 20 nm height for the recrystallized silicon and silicon oxide interface. Consideration of interface between recrystallized silicon and silicon oxide, and the oxide surface above, the observed roughness at the interface is due to original grain boundaries of polycrystalline silicon which was used as the material for the laser recrystallized silicon formation. It is also discussed HRTEM of the interface between polycrystalline silicon and silicon oxide.

Fresnel fringe contrast analysis and high resolution electron microscopy are used in conjunction to measure compositional and structural changes across the Si/SiOx interface with atomic resolution.

The magnitude of the dipole moment at the Si-SiO2 interface resulting from partial charge transfer that takes place upon the formation of interface bonds has been calculated. The charge transfer occurs because of the difference in electronegativity between silicon atoms and SiO2 molecules which are present across the interface. Results obtained for (100) and (111) silicon substrates indicate that the magnitude of the interface dipole moment is dependent on substrate orientation and the interface chemistry. Dipole moments at the Si-SiO2 and gate-SiO2 interfaces should be included in the definition of the flatband voltage VFB of MOS structures. CV-based measurements of the metal-semiconductor workfunction difference φms on (100) and (111) silicon oxidized in dry oxygen and metallized with Al agree with the predictions of this model. Other types of interface dipoles and their processing dependence are briefly discussed.

Kinetic data are provided for oxidation of Ge+-ion implanted Si over a range of temperature and oxidation ambient. Oxidation rates were enhanced in implanted Si and, over most of the range studied, found to be consistent with a modified reaction at the oxide/Si interface. However, this reaction is shown to be more complex than in virgin Si and could not be represented by a single activation energy. An anomalous behavior is exhibited at low-temperature for steam oxidation. This behavior is characterized and the mechanisms which are responsible are discussed.

We have studied oxidation of various Si samples including: Ge implanted Si, CVD and MBE grown Si(0.4–4% Ge) alloys, and MBE grown Si-Si(Ge) superlattices. The samples were oxidized in pyrogenic steam (800–1000°C, atmospheric pressure) and at low temperature and high pressure (740°C, 205 atm of dry O2). The oxidized samples were analyzed with RBS/channeling and ellipsometry.

An enhanced oxidation rate was seen for all Ge doped samples, compared with rates for pure Si. The magnitude of the enhancement increased with decreasing oxidation temperature. For steam oxidations the Ge was segregated from the oxide and formed an epitaxial layer at the Si-SiO2 interface; the quality of the epitaxy was highest for the highest oxidation temperatures. For high pressure oxidation the Ge was trapped in the oxide and the greatest enhancement in oxidation rate (>100%) was observed.

A new coating process of silicon dioxide (SiO2) “LPD” process, has been developed recently. Silicon dioxide (SiO2) film can be deposited on any substrate at the room temperature by immersing in hexafluorosilicic acid (H2SiF6).

In this study, physical and chemical properties of the “LPD- SiO2” film were investigated by using XPS, IR, ellipsometry, and etch rate measurement. The properties of this film deposited at the room temperature were almost the same as those of plasma CVD. The “LPD-SiO2” film without annealing was contained traces of F and OH. However, by annealing, F and OH were rapidly evaporated from the film and the film was getting densified.

As the “LPD-SiO2” film deposited at the room temperature showed very good results of chemical etching rate and of step coverage, it is expected that it is possible to use this “LPD- SiO2” film in the wide range of industrial area.