Surface photovoltage (SPV) measurements of lifetime and charge are used by the silicon industry for real-time, non-contact monitoring of alkalide and heavy metal contamination during IC processing. Information about contamination present at the surface or in the bulk of a silicon wafer is derived from their effects on measured electronic characterization. Identification and detection, with a sensitivity of ppq (107 cm'3), of Fe and Cr in the bulk of p-type silicon is possible via monitoring of their decomposition/pairing kinetics with boron. We will show the most important examples of the application of SPV to monitor critical IC processing steps. The allowable contamination thresholds in IC processing lines are a very strong function of technology and are different for various metals.

Extremely low concentrations of several technologically important elements (mainly lithium and boron) have been studied by a modified neutron depth profiling technique. Large angle coincidence spectroscopy using neutrons to probe solids with a thickness not exceeding several micrometers has proved to be a powerful analytical method with an excelent detection sensitivity. Depth profiles in the ppb atomic range are accessible for any solid material. A depth resolution of about 20 nanometers can be achieved.

We re-examine the technique of Scanning Transmission Electron Beam Induced Conductivity and report on the acquisition of remote contact EBIC images at 200keV showing variations in electrical activity within P-doped CdTe.

An unusual aspect of the pulsed laser deposition (PLD) process is that highly oriented (sometimes epitaxial) films of complex, multicomponent materials can often be prepared at low substrate temperatures. It is argued, using a simple model, that the arrival of even minor quantities of electronically excited species (Rydberg atoms and ions) can significantly affect the local surface temperature of the growing film. The present study experimentally confirms the existence of these energetic components in an ablation plume using a specially-modified time-of-flight quadrupole mass spectrometer. Ions as well as long-lived, excited state (Rydberg state) atoms were detected from laser ablation from a YBa2Cu307-5 (YBCO) target. Multiple peaks in the TOF profiles appear to derive from electron/ion recombination from higher charged species; the high kinetic energies observed are explainable from simple electrostatics involving localized holes trapped on the target surface.

The compositional profile of an interlayer inferred from Fresnel contrast data is usually determined assuming that the variation in the measured mean forward scattering potential is associated with changes in neutral atom scattering factor and atomic density. However, the technique is currently being applied to systems for which the form and the magnitude of the potential at the layer can be affected strongly by changes in ionicity. Here, we show how the analysis of ‘delta-doped’ layers in semiconductors, which contain thin layers of impurity ions at low concentrations, requires the analysis of not only the effect of strains on the density but also the contribution to the potential from charged ions surrounded by a wider spread of free carriers.

Observations of semiconductor superstructures with backscattered electrons in a scanning electron microscope have been used to revisit the concept of resolution of the backscattering imaging mode. It will be shown that the generation volume doesn't represent in itself a limit to the resolution, which depends only on the beam size and the signal to noise ratio.

Diamond is an attractive material for coating microfabricated metal and semiconductor field emitters, since it enhances the stability and emission characteristics of the emitter. In the present study, polycrystalline diamond thin films were grown on silicon and molybdenum field emitters by microwave plasma chemical vapor deposition, using the bias-enhanced nucleation technique. High resolution transmission electron microscopy (TEM) was used to analyze the morphology of the diamond film and the structure of the diamond/emitter interface. Electron diffraction patterns and high resolution images indicate the presence of a polycrystalline diamond film, as well as a polycrystalline SiC layer between the diamond film and the Si emitter. A carbide interlayer was also found to exist between the diamond and the Mo emitter surface. Parallel electron energy loss spectroscopy confirms the TEM identification of a polycrystalline diamond film.

The structure and density of amorphous S1O2 films grown by chemical vapor deposition (CVD) or thermal oxidation are studied by Fourier-transform infrared (FT-IR) absorption, neutron diffraction, and Rutherford backscattering (RBS) measurements. CVD oxides, formed in an atmospheric-pressure CVD reactor with a SiH4-O2 gas mixture at 400 °C, are compared with thermal oxides, grown at 980 °C in H2-O2 atmosphere. The average Si-O-Si bond angle deduced from the stretching frequency of FT-IR is found to be smaller in CVD oxides than in thermal oxides, and the density revealed by RBS measurements is found to be a little lower in CVD oxides than in thermal oxides. These differences are explained by the medium-range structural disorder revealed by FT-IR measurements as well as by neutron diffraction measurements. The medium-range structural disorder in CVD oxides is responsible for large silanol content in the oxides and is the origin in difference between CVD and thermal oxides.

The strain in SiGeC heteroepitaxial films grown on Si(100) substrates has been quantified using ion channeling. The films were grown both by combined ion beam and molecular beam epitaxy (CIMD) and chemical vapor deposition (CVD). Rutherford backscattering spectrometry (RBS) was used to quantify the Ge concentration as well as the film thickness, nuclear resonance elastic ion scattering was used to quantify the carbon concentration, and ion channeling was utilized to measure film quality. Channeling angular scans across an off normal major axis were used to quantify the strain. Part of the film was removed by using a solution of HF, HN03 and CH3COOH in order to obtain a reliable scan in the substrate. The results indicate that C may be compensating for the strain introduced by Ge.

Backside secondary ion mass spectrometry (SIMS) is employed to examine the Ge/Pd non-alloyed ohmic contact on InGaAs. 130 nm Ge/ 50 nm Pd contacts were deposited on an InP/InGaAs marker layer structure. The contacts were annealed for various times at 200°C and 325°C. Samples were mechanically and chemically thinned to facilitate sputter profiling from the backside, thereby avoiding problems such as roughening or non-uniformity of the metallic layers. Subsequent to depth profiling, additional anneals were performed on the thinned samples, and the samples were reexamined. Extensive reaction of Pd with InGaAs is observed on deposition. Little additional reaction occurs at 200°C. At 325°C, Pd is reclaimed from the reacted surface region, forming PdGe with some excess Ge at the interface. In-diffiision of Pd and Ge into InGaAs is observed at longer annealing times. The results are contrasted with prior studies on GaAs, InP, and InGaAs.

Optical second harmonic generation (SHG) of metal clusters supported on a dielectric substrate has been investigated. The SHG intensity was detected in situ as a function of cluster size during the nucleation of the particles at constant number density. SH radiation is detectable for particles as small as approximately 1 nm. In further experiments the chemisorption of oxygen on the surface of the metal particles was studied. The SHG signal strongly decreases as a function of oxygen coverage and disappears almost completely upon chemisorption of only one monolayer.

Real-time monitoring of surface cleanness in laser dry cleaning was investigated by monitoring the acoustic waves emitted from the substrate surface under pulsed laser irradiation. It is found that the acoustic wave from the surface under laser irradiation can reflect the surface condition, i.e., the surface cleanness. Besides the surface condition, the acoustic waveforms also depend on the substrate materials and laser pulse energies (intensities). The frequency spectrum obtained from the Fourier transform can provide clear indication for different surface cleanness. Removing of surface contaminants can generally result in weaker laser-induced acoustic wave and change in the frequency spectrum. The surface cleanness, therefore, can be monitored in real-time by detecting the amplitude and frequency of the acoustic wave during the laser cleaning process. This phenomenon provides the laser cleaning technique a real-time feedback during the cleaning process.

The extended x-ray absorption fine structure (EXAFS) above the Ta L3-edge on tantalum oxide capacitor films has been measured. Four kinds of tantalum oxide films were studied: as-deposited (amorphous), dry 02 annealed (crystalline), 02-plasma annealed (amorphous) and 2-step (02-plasma + dry O2) annealed (crystalline). From EXAFS analysis, differences in the local structures of tantalum oxide capacitor films, in terms of oxygen deficiency around Ta, were observed in the various annealed films. The leakage current characteristics of tantalum oxide capacitors correspond with the differences in the local structures around Ta. The discussion looks at the relationship between the leakage current characteristics and the local structures around Ta.

High resolution images of a block oxide, (Nb205)çi(W03)8, with and without a superposed carbon film are compared both energy filtered and including the inelastic scattering. The differences between the images are quantified on an absolute intensity scale and possible origins of the differences in atomic level contrast are assessed using multislice simulations.

The deposition of metal and compound films from ions rather than neutrals allows a high degree of control over the incident particle's direction and energy. Metal-rich plasmas have been produced using large magnetrons (30 cm dia., 20 kW) and in-flight ionization of the sputtered atoms by means of a dense, inductively coupled rf plasma. This plasma is generated by a multi-turn antenna inside the chamber located between the cathode and the sample. The nature of the deposition, including the ion-to-neutral ratio and the ion energy are controllable. Relative ionization of the metal has been measured at over 80%. Ion energy is controlled by a negative dc sample bias. Metal films of Cu and AlCu have been deposited on 200 mm Si wafers at room temperature into moderate aspect ratio wafer features with no voids. The features used are trenches and vias of width >3500A, and the technique has also been used to fill 2-level, “dual damascene” features. The films are highly (111) oriented and have low stress and low Ar content. The effects of ion direction as well as resputtering of the film topography are readily observed, and are consistent with computer model predictions. High quality TiN films (40 micro-Ohm-cm, gold colored) have also been deposited at room temperature into trenches and vias for applications as diffusion barriers.

A focussing grid broad beam Kaufman source, using argon ions on a target of nominal composition Nd2Fei4B has been employed to sputter deposit magnetic thin films of thicknesses ranging from 800 â to 1300 â on silicon-(lll) substrates at room temperature. These films were characterised for their composition depth profile by Rutherford Backscattering Spectroscopy, while x-ray diffraction was used to study the crystallographic structure. Due to a close match between (111) Si with (220) Nd2Fej4B lattice spacings, preferred crystallographic texturing was expected, and experimental results showed a greatly enhanced (220) texture. The degradation in magnetic properties was attributed to the presence of oxygen in the films as indicated by concentration depth profiles. It is premised that another significant role of oxygen may be to relieve the misfit strain across the interface by its incorporation within the Nd2Fej4B phase.

Very recently a new technique named multi-ion-bram reactive cosputtering(MIBRECS) was developed for preparing multi-component metal oxide thin films. Epitaxial or highly oriented (Pb,La) TiO3 thin films sputtered from pure metals of lead, titanium and lathanium were deposited by using this technique. In order to consummate the technique and to study the mechanism of reactive cosputtering, a general model of multi-ion-beam reactive cosputter-ing was proposed for the first time based on the well-known gas kinetics under stable sputtering circumstances, and a computer numerical simulation of the model was carried out with the parameters adopted in our experiments. The relationships among the sputtering ratioes of the targets, and the coverage ratioes of simple substances and oxides of the target metals on substrate surface with the total reactive gas flux and the densities of the sputtering ion beam were obtained respectively, and the hysteresis effect of the characteristic of reactive sputtering and the interactions during multi-ion-beam reactive cosputtering processes were also obtained. The numerical simulation results are at least qualitively in agreement with the experiments.

We report the results of a study of IR emissivity of aluminium films as a function of impurity level, film thickness and sputtering conditions. Preliminary work suggests that for a given level of film impurities and deposition conditions, the JJR emissivity can be minimized with a certain film thickness. The influence of impurity level, film thickness, and sputter pressure on IR emissivity has been correlated with the resistivity and the surface roughness (measured by atomic force microscopy). The results are discussed in the general context of the Drude theory with allowances for the observed roughness.

Oxides of hafnium, niobium, tantalum, and zirconium are deposited by ion beam sputtering of the pure metal targets using CO2 as working gas. The resulting thin films are amorphous, featureless smooth and of excellent adherence to semiconductor substrates. Despite a certain content of carbon they are highly transparent in the visible and near infrared wavelength range as determined by spectroscopic ellipsometry. Their wide range of refractive indices makes them suitable for multilayer optical filter design.

Silicon Carbide (SiC) formed by chemical vapor deposition (CVD) has the highest reflectivity in the extreme ultraviolet (EUV) of any currently used optical material. The high temperature required for the CVD process, however, limits its suitability for coating optical components. To address this problem thin films have been sputtered onto optical surfaces from CVD βSiC targets. These films, while having reflectivity lower than that of CVD SiC, are nonetheless the best coatings available for reflectance in the spectral region below 1000À. While the initial properties are good, the EUV reflectivity degrades with time after deposition. A relative decrease of about 25% is evident in the reflectivity at 920Â after 2.5 years, and about 85% of this change occurs in the first three months. In fact, a decrease is observed in the minutes following deposition. In this study the degradation is characterized and a mechanism is proposed. Efforts underway to reduce or eliminate the degradation are discussed.