The use of sulfur-containing organic monolayer films improves adhesion between gold and silicon dioxide. The structures of these monolayers were analyzed using contact angle, ellipsometry, and XPS. The zone of adhesive failure was at or near the gold-monolayer interface.

The gettering effectiveness of various backside gettered polysilicon, silicon nitride, or poly + nitride film structures on n-type (100) Czochralski silicon wafers from a single ingot during simulated complementary-metal-oxide-semiconductor process cycles has been investigated by synchrotron section topography, breakdown voltage of 25-nm gate oxide, and minority carrier lifetime measurements. Interfacial structure was studied by cross-section transmission electron microscopy. Our studies show that for successful implementation of thin film backside gettering, good control of interactions between intrinsic gettering and thin film backside gettering during device processing cycles is critical. Thin film deposition generally increases oxygen precipitation. No extended defects propagate toward the bulk silicon. The structural and electrical quality of a denuded zone is found important. The best device yield (90%) is observed from the middle section wafers (with a 2 μm thick polysilicon backsurface coverage) which develop no recognizable bulk precipitates and stacking faults after the complete thermal cycles.

As the technology for diamond film preparation by plasma-assisted CVD and related procedures has advanced, Raman spectroscopy has emerged as one of the principal characterization tools for diamond materials. Cubic diamond has a single Raman-active first order phonon mode at the center of the Brillouin zone. The presence of sharp Raman lines allows cubic diamond to be recognized against a background of graphitic carbon and also to characterize the graphitic carbon. Small shifts in the band wavenumber have been related to the stress state of deposited films. The effect is most noticeable in diamond films deposited on hard substrates such as alumina or carbides. The Raman line width varies with mode of preparation of the diamond and has been related to degree of structural order. The Raman spectrum of hexagonal diamond (lonsdaleite) is distinct from that of the cubic diamond and allows it to be recognized.

The requirements for fitting bcc metals within the EAM format are discussed and, for comparative purposes, the EAM format is cast in a normalized form. A general embedding function is defined and an analytic first- and second-neighbor model is presented. The parameters in the model are determined from the cohesive energy, the equilibrium lattice constant, the three elastic constants, and the unrelaxed vacancy formation energy. Increasing the elastic constants, increasing the elastic anisotropy ratio, and decreasing the unrelaxed vacancy formation energy favor stability of a close-packed lattice over bcc. A stable bcc lattice relative to close packing is found for nine bcc metals, but this scheme cannot generate a model for Cr because the elastic constants of Cr require a negative curvature of the embedding function.

Silicon-on-insulator films were formed by ion implantation of oxygen and were treated with various annealing cycles at peak temperatures of 1150 °C, 1200 °C, and 1250 °C in a conventional diffusion furnace. The objective of this study was to examine the structural effects on samples with similar oxygen diffusion lengths (from 17 to 33 μm) achieved by annealing at different times and temperatures. The oxygen and silicon distributions, as well as the residual damage and precipitate size and distribution, were measured by Auger electron microscopy, Rutherford backscattering spectroscopy, and transmission electron microscopy. In agreement with previous findings, higher temperatures produced a larger and less defective, “precipitate-free” superficial Si region. The buried oxide layer thickened from 0.33 μm to a maximum of 0.43 μm as some precipitates were incorporated into the buried oxide while others adjacent to the buried oxide grew in size (up to 47 nm) and decreased in relative number. A new result of this systematic study of annealing conditions was that the peak temperature has a greater effect on the morphology and crystal quality of the superficial Si structure than does time at temperature. Structural changes for longer anneals at 1150 °C are not equivalent to shorter anneals at 1250 °C even though the diffusion length of oxygen for these treatments is the same.

It is suggested that the “supermodulus effect” observed for composition-modulated strained-layer superlattices may arise from the presence of the structurally disordered solid interfaces and not necessarily from electronic-structure effects. The latter are excluded by investigating the elastic properties of a so-called grain-boundary superlattice in which chemically identical materials are joined to form a three-dimensional superlattice. Both an embedded-atom-method and Lennard-Jones potential are employed in our zero-temperature atomistic calculations of the elastic constants and moduli of such a superlattice. They yield qualitatively similar results which, for large modulation wavelengths, can be represented by a mean-field model in which the interfacial regions are characterized by a set of effective elastic constants which are different from those of the bulk regions. The appearance of a maximum in the biaxial modulus and a minimum in the shear modulus is shown to arise from the interaction between interfaces. It is also shown that such extreme anomalies appear only in the moduli but not in the elastic constants of the grain-boundary superlattice.

It has recently been suggested that the rate of structural relaxations in amorphous chalcogenide glasses is inversely proportional to the viscosity and the latter obeys the Vogel-Tammann-Fulcher relationship. In this paper, Differential Scanning Calorimetry (DSC) and Thermomechanical Analysis (TMA) experiments examining the glass transformation in a–Se are reported which have been carried out over as wide range of heating rates as practically possible on the available instrumentation covering more than three decades of heating rate variation from r = 0.05 °C/min to r = 100 °C/min. The observed glass transformation temperatures in DSC and TMA ranged from 30 °C to 65 °C. The a–Se films were vapor deposited by thermal evaporation onto A1 substrates (at ∼70 °C) under identical conditions and well aged over an equal period of time so that all the films had an identical initial structure. Analysis of the glass transition temperature, Tg, vs heating rate, r, data obtained from the DSC endotherms shows that the structural relaxation rate is non-Arrhenius and can be described reasonably well by a Vogel expression of the form exp[–A/(T – T0)] which may have a weak structure dependent factor of the form exp[–c(H – HE)] where (H – HE) is the deviation of the structural enthalpy from its equilibrium value. It was found that a phenomenological single parameter Vogel description for the retardation time over the whole temperature range accessed leads to A and T0 values comparable with those obtained from the Vogel analysis of the viscosity-temperature data of Cukiermann and Uhlmann (1972), as well as the recent thermomicrohardness data of the present authors (1989). Furthermore, it is shown that the wide differences reported for the crystallization activation energy in a–Se can be readily interpreted by a viscosity limited crystallite growth rate. The Vogel interpretation is also found to be consistent with the temperature dependence of the mean dielectric relaxation time in the Debye loss observed by Abkowitz, Pochan, and Pochan (1980). It is suggested that in the elemental chalcogenide a–Se, the relaxation rate of enthalpy, microhardness, and dielectric polarization, as well as the crystallization rate, all scale inversely with the viscosity. TMA measurements, on the other hand, although still interpretable in terms of a Vogel behavior, did not indicate a softening behavior which paralleled the viscosity.

Previous workers have shown that germane does not decompose below 700 K on silica substrates. However, if the germane is irradiated with an ArF or KrF laser, germanium films will grow at temperatures down to 610 K. In the work reported here, the role of the laser in the growth process was explored. First, the species impinging on the substrate during ArF laser-assisted chemical vapor deposition (LCVD) were analyzed with a mass spectrometer. The analysis showed that when germane is irradiated with an ArF laser under growth conditions, digermane is formed in the gas phase. The digermane then impinges on the substrate and pyrolyses. Many other species have been reported previously to be formed transiently during the laser pulse. However, we were not able to detect any other species with a high enough flux onto the substrate to condense at an appreciable rate. Next, temperature programmed decomposition was used to see if photochemical decomposition of chemisorbed germane played an important role in film growth. It was found that a laser dose comparable to that needed for film growth did not produce an appreciable change in the decomposition spectra. Lastly, film growth studies were used to examine the role of the digermane formed by the laser in the film growth process. It was found that a mixture of germane and digermane will decompose on a silica substrate down to 580 K to produce a germanium film. The growth characteristics of the germane/digermane mixtures were virtually the same as those seen in LCVD. Thus, it appears that under the conditions used previously for LCVD, the main role of the ArF laser is to convert some of the germane source gas to digermane. It also has been found that under other conditions, one can grow germanium films down to at least 300 K via digermane photolysis.

The interface of a copper-sapphire couple that was irradiated with a nanosecond pulsed-exeimer laser was studied by transmission electron microscopy. Deposited layers of 30 or 100 nm thickness were laser treated with energy densities in the range of 0.5 to 0.75 J/cm2. Two different atmospheres were used during these treatments, viz., air or a mixture of argon-4 vol. % hydrogen. The copper film and a thin alumina layer were melted by the laser pulse. Two well differentiated regions could be observed in the modified layer. The region closer to the unmodified substrate consisted of epitaxially regrown alumina with crystallites misoriented up to 10° relative to the substrate sapphire orientation, while precipitate particles could be seen closer to the resolidified copper. The nature of the precipitates generated in the second region was dependent on the atmosphere present during the treatment. In air a trirutile-like compound was obtained which is either oxygen or copper deficient. In an argon atmosphere a compound having a hexagonal structure closely related to sapphire was observed, where copper substituted for some aluminum. These observations are in agreement with a previously developed mathematical model that predicts melting of a thin substrate layer.

Amorphous selenium (a-Se) colloid particles have been directly photodeposited onto insulating substrates. Scanning Electron Microscopy (SEM) supported by kinetic adsorption measurements reveals the origin of the photodeposition process. The studies show that film formation occurs through a sequence of particle precipitation, growth, and photoadsorption. A plastic flow and coalescence process creates a continuous monolayer before a fast deposition rate of Se on the deposited materials commences. Surface forces seem to have an important role in the creation of the morphological structures of the adsorbed particles.

Inert-gas markers, Rutherford backscattering, and x-ray diffraction were used to investigate solid-state interdiffusion in Ni/Zr and Au/Zr bilayer films as a function of temperature; microstructural studies during annealing were performed in situ, in a high-voltage electron microscope. Au, in contrast to Ni, is not an anomalously fast diffuser in crystalline Zr. Nevertheless, an amorphous product phase was found in both alloy systems for reaction temperatures  550 K; heterogeneous nucleation of the amorphous phase was observed in Au/Zr. The interdiffusion data reveal two distinct Arrhenius regimes, 330–∼470 K and ∼480–550 K, with quite different apparent activation enthalpies. These thermal interdiffusion results are compared with temperature dependent studies of ion-beam mixing in similar bilayer specimens. This comparison indicates that the enhanced efficiencies observed for ion-beam mixing above ∼480 K result from the as-prepared metastable microstructurc, and are not due to radiation-enhanced diffusion.

Implantation of nitrogen at 150 KeV and a dose of 1 ⊠ 1018/cm2 into (110) silicon results in the formation of an amorphized layer at the mean ion range, and a deeper tail of nitrogen ions. Annealing studies show that the amorphized layer recrystallizes into a continuous polycrystalline Si3N4 layer after annealing for 1 h at 1200 °C. In contrast, the deeper nitrogen fraction forms discrete precipitates (located 1μm below the wafer surface) in less than 1 min at this temperature. The arcal density of these precipitates is 5 ⊠ 107/cm2 compared with a nuclei density of 1.6 ⊠ 105/cm2 in the amorphized layer at comparable annealing times. These data suggest that the nucleation step limits the recrystallization rate of amorphous silicon nitride to form continuous buried nitride layers. The nitrogen located within the damaged crystalline silicon lattice precipitates very rapidly, yielding semicoherent crystallites of β–Si3N4.

The thermodynamic equilibrium of structures consisting of a thin film silicide (TiSi2 or CoSi2) on doped Si (with As or B) is investigated. Isothermal sections of the ternary phase diagrams for Ti–Si–B, Co–Si–B, Ti–Si–As, and Co–Si–As have been evaluated, indicating the stability of high B concentrations in Si underneath a CoSi2 layer, the instability of high As concentrations in Si underneath a CoSi2 layer, and of B and As concentrations underneath a TiSi2 layer. The obtained thermodynamic predictions agree very well with experimental results (i) on the redistribution of dopants during silicide formation, (ii) on the diffusion of dopants from an ion implanted silicide, and (iii) on the stability of highly doped regions underneath the silicide, both for the case of TiSi2 and CoSi2. It is shown that even though the inaccuracy of reported thermodynamic data is substantial, thermodynamic calculations provide a useful guidance and are consistent with the experimental results.

A simple expression for the Gibbs free energy of formation of a pure component or a eutectic alloy glass, relative to the stable crystalline phase (or phases) at the same temperature is deduced by use of thermodynamic arguments. The expression obtained is supposed to apply to both monocomponent and multicomponent liquid alloys that might become glasses from the supercooled liquid state, irrespective of the critical cooling rate needed to avoid crystallization.

A theory to predict the orientation of radio-frequency (rf) sputter-deposited MoS2 films with respect to the substrate surface is presented. Oxygen-containing species such as H2O and -OH are postulated to be active sites that force crystallites to form with their basal planes perpendicular to the surface. X-ray diffraction is used to determine the crystallite orientation in films deposited on smooth, rough, or oxidized Si surfaces, as well as on fused silica or gold surfaces. The results support the theory. To produce MoS2 films with their crystallite basal planes parallel to a substrate surface (which has been suggested to be the low friction orientation), the active sites must be removed from the substrate by, for instance, heating in vacuum.

The reactions of SiCl4 and GeCl4 with oxygen and oxides of nitrogen have been studied in a continuous flow system. SiCl4 is found to react with nitrous oxide at a considerably lower temperature (700 °C vs 1050 °C) than with oxygen. In both cases the formation of silicon oxychlorides (hexachlorodisiloxane and octachlorocyclo-tetrasiloxane) was observed for the first 300 °C after reaction initiates. Activation energies of 115 kcal/mole and 40 kcal/mole were determined for the reactions with oxygen and nitrous oxide, respectively (under conditions of 100-fold excess oxidizer). GeCl4 is also found to react with nitrous oxide at a lower temperature than with oxygen; however, in this case no oxychloride species were observed. Activation energies of 53 kcal/mole and 48.6 kcal/mole were determined for the reactions with oxygen and nitrous oxide, respectively (under conditions of 70-fold excess oxidizer). Reactions of GeCl4 with nitric oxide and nitrogen dioxide are also reported. The use of N2O as an oxidant in optical fiber fabrication processes is discussed.

Fourier transform infrared spectroscopy (FT–IR) forms the basis for determining the morphological composition of mixtures containing alpha, beta, and amorphous phases of silicon nitride. The analytical technique, involving multiple linear regression treatment of Kubelka-Munk absorbance values from diffuse reflectance measurements, yields specific percent composition data for the amorphous phase as well as the crystalline phases in ternary mixtures of 0–1% by weight Si3N4 in potassium bromide.

Mössbauer spectrometry and x-ray diffractometry were used to characterize the microstructural changes that occurred during the mechanical alloying of Fe and V powders, After 3 h of essentially no interatomic intermixing, an Fe–V alloy began to form. At first the chemical composition of this alloy was highly inhomogeneous, having large variations over distance scales of less than 100 Å. After about 24 h of ball milling, the alloy homogenized and then became at least partly amorphous.

Conditions have been developed for the preparation of ZnP2 and deposition of its stoichiometric thin films, using the flash evaporation technique. Structural properties of the ZnP2 obtained have been studied using x-ray diffraction, and chemical composition has been established by the polarography technique. Optical absorption of thin films of β–ZnP2 has been investigated over the range 1.2–3.2 eV. Analysis of thin film data showed that β–ZnP2 is a direct band gap material. The XPS and UPS of β–ZnP2 show a shift in binding energy (BE), which is due to transfer of electrons from zinc to phosphorus.

Microwave plasma assisted CVD diamond films have been studied by transmission electron microscopy. Cross-section TEM as well as plan-view TEM methods were used to investigate various structural defects formed in the films. It was found that diamond films contain a large number of stacking faults and twins which lie on the {111} planes in diamond. With an increase in methane concentration during the deposition process, the density of these defects increases and their dimensions become smaller. The tendency for forming these structural defects is of concern in developing tailored structures and properties of diamond films.