Plasma-enhanced chemical vapor deposition (PECVD) silicon nitride films deposited on both GaAs and Si substrates have been characterized by spectroscopic ellipsometry. The results indicate that such films consist of three constituents: Si3N4, voids, and amorphous silicon (α-Si). In addition, it is also observed that for typical deposition conditions there is an intervening layer of α-Si (on the order of 50–100 Å) between the nitride film and the semiconductor substrate. The thickness of this a-Si layer is found to depend on both the stoichiometry and the growth time of the nitride layer, leading to the conclusion that it is a result of excess Si diffusing from the growth surface through the nitride layer.

Silicon nitride films have been deposited with a single‐magnet electron‐resonance deposition system using nitrogen and silane as the reaction gases at substrate temperatures of 110°C and 300°C. The films are slightly nitrogen‐rich with no measurable Si‐H bonds measurable by Fourier Transform infrared spectroscopy and the concentration of hydrogen present as N‐H bonds increases with increasing SiH4/N2. The stress levels in the films can be controlled from tensile to compressive by decreasing the SiH4/N2 flow ratio and very low stress can be obtained with N‐H bond concentrations of 4 at. %. The optical bandgap for the layer with the lowest stress value (‐11.5 MPa), deposited at 300°C was 4.9 eV, as determined from a taue plot, and the waveguide loss at 632.8 nm was 2.3 dB/cm for 500 nm thick film deposited on fused silica.

Structural correlations at the Si(111)/Si3N4(0001) interface are studied using the molecular dynamics (MD) method. In the bulk, Si is described by the Stillinger-Weber potential and Si3N4 by an interaction potential which contains two-body (steric, Coulomb, electronic polarizabilities) and three-body (bond bending and stretching) terms. At the interface, the charge transfer from silicon to nitrogen is taken from LCAO electronic structure calculations. Using these Si, Si3N4 and interface interactions in MD simulations, the interface structure (atomic positions, bond lengths, and bond angles) is determined. Results for fracture in silicon are also presented.

Fracture in thin films of silicon nitride and alumina is investigated with large-scale multiresolution molecular-dynamics (MD) simulations on parallel computers. The simulations for alumina include dynamic charge transfer effects based on electronegativity equalization. Results for structural and dynamic correlations and the effects of temperature and orientation of film on fracture dynamics and morphology of fracture surfaces are presented.

The trapping properties of the Si-Si bond in Si3N4 and SiO2 were investigated. The MINDO/3 calculations show that the spin polarization of the Si-Si bond with a captured hole takes place in both SiO2 and Si3N4. The ESR (Electron Spin Resonance) measurements were made in Si3N4 with captured electrons and holes. The number of localized carriers was of two orders of magnitude larger than that used by others. The ESR signal of localized electrons and holes was not observed. A new mechanism of the antiferromagnetic ordering of localized electrons and holes in an insulator with a large concentration of traps is proposed. According to this mechanism, the antiferromagnetic ordering in Si3N4 may be caused by the resonance tunneling of localized spins through nonoccupied traps. We believe that the deep traps responsible for the electron and hole capturing in Si3N4 are the Si-Si bonds.

The advantage of SOI wafers for device manufacture has been widely studied. To be a real challenger to bulk silicon, SOI producers have to offer SOI wafers in large volume and at low cost. The new Smart‐Cut® SOI process used for the manufacture of the Unibond® SOI wafers answers most of the SOI wafer manufacturability issues. The use of Hydrogen implantation and wafer bonding technology is the best combination to get good uniformity and high quality for both the SOI and buried oxide layer. In this paper, the Smart‐Cut® process is described in detail and material characteristics of Unibond® wafers such as crystalline quality, surface roughness, thin film thickness homogeneity, and electric behavior.

In this work we show that annealing of silicon/silicon‐dioxide/silicon structures in forming gas (N2:H2; 95:5) above 500°C leads to spontaneous incorporation of mobile H+ ions in the buried SiO2 layer. We demonstrate that, unlike the alkali ions feared as killer contaminants in the early days, the space charge distribution of these mobile protons within the buried oxide layer can be very well controlled and easily rearranged with relatively high speed at room temperature. The hysteresis in the flat band voltage shift provides a unique vehicle to study proton kinetics in silicon dioxide thin films. It is further shown how this effect has great potential as the basis for a reliable nonvolatile FET memory device that is expected to be competitive with state‐of‐the‐art Si‐based memory technologies. The power of this novel device is its simplicity; it requires few processing steps, all of which are standard in Si integrated‐circuit fabrication.

The impact of two implant parameters, namely the implant substrate temperature and implant beam current, on the physical and electrical properties of SIMOX buried oxide are investigated. Three implant substrate temperatures, 540 °C, 590 °C, and 640 °C and three beam current, 45 mA, 55 mA, 65 mA, are investigated. Results from thermal conductivity and surface photovoltage measurements show no apparent differences between samples. Results from interface roughness shows a decreasing trend as the substrate temperature and beam current increases. For the samples with different implant temperatures, the high‐field conduction shows an opposite dependence for top‐interface versus substrate injection. This behavior can be explained by the conservation of silicon in the buried oxide. Correlation of surface photovoltage and high‐field conduction shows weak positive dependency while that of interface roughness and high‐field conduction shows dependency only when the sets of temperature variation and beam current variation are decoupled.

A new technique, referred to as the “n&k Method”, is used to characterize the thin films comprising Silicon-on-Insulator (SOI). With the “n&k Method”, a non-destructive robust measurement of the thickness of both the crystalline silicon top-layer and the buried oxide under-layer, the spectra of refractive index (n), and extinction coefficient (k), and the smoothness of the interfaces is established. The “n&k Method” determines these quantities simultaneously and without multiple solutions for thickness. The non-destructive measurement of interface roughness between the buried oxide under-layer and the silicon substrate is associated with the presence of silicon islands. The native oxide that forms on SOI is also detected and measured. No initial user's input for thickness and optical constants are required in order to obtain these results. The spectra of optical constants are measured accurately and reliably.

The effect of oxygen dose variation on the SIMOX SOI structure has been investigated extensively in this work. Keeping other implantation parameters constant, the dose has been varied from 0.2x1018cm–2 to 1.4xl018cm–2. Our studies show that a critical dose exists for a particular implant energy, below which a continuous buried oxide layer does not form. Further, the SiO2 precipitates enhance the pinning of defects in the as-implanted state which subsequently grow into threading dislocations. A dose window exists, where the dislocation density is a minimum.

The oxygen depth distribution in the as-implanted and annealed state has been studied using SIMS. HRXRD measurements have been performed to reveal the strain state as a function of dose variation. The defect microstructure has been investigated using PTEM, XTEM and Secco Etching. AFM studies show the quality of the Si surface and Si/BOX (Buried OXide) interface roughness. This work gives us a fundamental understanding of the evolution of the defect microstructure and strain from the as-implanted to the annealed state using independent implantation parameter control.

SIMOX wafers annealed at high temperature in argon or nitrogen ambient are compared in terms of film, oxide, interface, and device properties. This evaluation is conducted by correlating pseudo-MOSFET data in unprocessed wafers with the performance of n- and p-channel transistors. Characterization with the Ψ-MOSFET technique reveals a pile-up of nitrogen near the buried Si -SiO2 interface, where the electron mobility is degraded. MOSFET characteristics are dramatically affected by annealing in nitrogen with large shifts of front and back channel threshold voltages, enhanced leakage currents, and channel doping modification. Nitrogen-induced donors are suspected to be responsible for doping compensation in n-channels (leading to full-depletion mode operation) and overdoping in p-channels. By contrast to argon ambient, which has no major drawbacks, nitrogen ambient can be unsuitable for annealing of SIMOX wafers.

The effect of post-oxidation of the silicon-on-insulator structure produced by implantation of oxygen (SIMOX) upon neutral oxygen vacancies (O3=Si-Si=O3, “=” denotes bonds with three separate oxygens) in the buried oxide has been investigated. It is observed that the photoluminescence intensity from the vacancies and the thickness of buried oxide increase after the post-oxidation. An Ar plasma was used to expose the buried oxide in order to convert the vacancies to E'r (O3=Si, “” denotes an unpaired electron) centers which are detectable by electron-spin-resonance. The total number of E’ r centers was found to increase, which should suggest a similar increase in the number of the vacancies in the buried oxide. Similar measurements repeatedly done on the buried oxide by changing its thickness by etching revealed that the increased part of oxide by the post-oxidation contains the vacancies with a similar density to the original part of oxide, and that the post-oxidation scarcely affects the oxygen deficiency of the original part.

Wiring capacitance in a multilevel interconnecting structure for sub-quarter-micron ULSI devices has been studied using a simulator called SENECA1), which is developed by the Technical University of Vienna and Sony corporation, for optimizing the structure with low dielectric constant materials as interlevel dielectric layers. The simulation results suggest that an optimized structure model should have an ILD(Inter-Level Dielectrics) thickness of 0.7μm and a metal thickness of 0.4μm for sub-quarter-micron ULSI devices. The application of the low dielectric constant materials to the ULSI devices is examined and also discussed with focusing on feasibility and reliability issues. Calculated wiring capacitance is compared with actual capacitance based on the optimized structure. The 33.2% reduction of capacitance is obtained with using an organic film with dielectric constant of 2.4 in excellent accordance with the simulation.

In recent years, the problem of electrical resistance of vias and contact holes has become greater because a thin insulated layer formed at the interface of the hole has become a serious difficulty in the manufacture of ULSIs. In using conventional techniques of cross sectional analysis to examine the cause, only one cross section of the hole can be analyzed, therefore there is the problem that the two-dimensional interface layer formed cannot be analyzed exactly.

In this paper, we have developed a new observation method to inspect two dimensions of the layer formed locally at the interface of the holes. This new observation method gives the configuration, coverage, and element map of the interface layer because the full interface of holes can be inspected; therefore, the process margin can be discussed. The present technique is demonstrated in failure analysis of sub-half-micron vias filled with tungsten.

The hydridospherosiloxane cluster H8Si8012 has been physisorbed onto Si(111)-H and soft X-ray Si 2p core-level photoemission spectra obtained. The results of these experiments provide strong support for previous binding energy assignments of HSi03 moieties at -3.6 eV.

Ab initio Hartree-Fock and second-order Möller-Plesset theory calculations have been performed to investigate the stability of triply-coordinated 0+ centers in the Si-O-Si network of amorphous SiO2. The calculations reveal that the H+ ion binds with a bridging O center to form a very stable (De > 6 eV) trivalent O complex. Capture of an electron by the positively charged protonated complex, however, is predicted to immediately lead to the dissociation of the O-H bond. A relatively weaker, but stable bond is also formed between the bridging O atom and a +SiH3 ion.

In this study, we investigated the deposition temperature's affect on TEOS based Si02 properties and reaction mechanisms while changing the excitation frequency. We used a parallel-plate plasma reactor, and either 100 kHz or 13.56 MHz radio frequency to generate plasma. We found that 100 kHz plasma promotes SiO formation and improves the film properties at low deposition temperatures. We assume this to be due to the supplement of higher energy ions to the substrate surface in 100 kHz plasma. This in turn promotes the elimination reaction (condensation reaction) of OH that links to Si atoms as a terminator of surface SiO networks or precursor molecules.

With a newly constructed high temperature wafer curvature system, we measured significant viscous flow of thermal oxides at temperatures as low as 800°C. In-situ measurements were performed at temperatures between 800°C and 1100°C for wet and dry thermal oxide films of various thicknesses. We found that dry oxides have higher stresses and slower stress relaxation compared to wet oxides grown at higher temperatures. The viscosity of thermal oxide thin films was found to increase with time during relaxation and a structural relaxation process is suggested to explain this phenomenon.

This paper presents experimental studies in which N-atoms have been incorporated at Si-SiO2 interfaces by forming the interface and oxide film by a 300°C remote plasma assisted nitridation/oxidation process using N2O. Process dynamics have been studied by on-line Auger electron spectroscopy (AES) by interrupted plasma processing. Plasma-activated species have been identified by in-situ mass spectrometry (MS) and optical emission spectroscopy (OES). Based on AES studies using N2O, O2 and sequenced N2O and O2 source gases, reaction pathways for N-atom incorporation i) at and/or ii) removal from buried Si-SiO2 interfaces have been identified, and contrasted with reaction pathways for nitridation using conventional furnace processing. The active species for N-atom incorporation is NO+, and for oxide growth, O2.

The structure of a thermally grown SiO2 film on a crystalline 6H‐SiC substrate was investigated using X‐ray reflectivity and fourier‐transformed infrared attenuated total reflection (FTIR‐ATR). The density, surface roughness and interface roughness of thermal oxide on 6H‐SiC were obtained by X‐ray reflectivity. The TO mode and the LO mode of Si‐O‐Si stretching vibration from the thermal oxide film on 6H‐SiC were obtained from polarized ATR spectra. The local structure of SiO2 film near the SiO2 /SiC interface was discussed from the measurements, and the thermally grown SiO2 film on a 6H‐SiC substrate was found to have a structural transition layer with thickness below 10 nm near the SiO2/SiC interface.