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The evolution of integrated single-wafer processing for high-temperature applications in the front end of the line (FEOL) occurred with the advancements in single-wafer rapid thermal processing and its acceptance as a manufacturing technology. The Integra RTCVD cluster tool for high-temperature applications features wafer cleaning, rapid thermal processing and single wafer chemical vapor deposition steps. The paper presents integrated vapor phase clean and RTCVD applications for FLASH memory gate stack and DRAM cell.

Shallow contact metallization of SiGeC was studied in anticipation of this alloys use in low power applications. It has been shown that in the solid state reaction of Co on (100) Si, that Co is the moving species with proper annealing conditions. This prevents the formation of Kirkendal voiding in certain device structures. This work studies the Co and Ti metallization of SiGeC. A bilayer of 44 nm of Co on 7 nm of Ti, were electron beam evaporated onto epitaxially grown Si0.77Ge0.21C0.02. The samples were rapid thermal processed at 600 and 900 °C for up to two minutes in a nitrogen ambient. The analysis techniques used were Rutherford backscattering spectrometry which included the used of the 4.27 MeV 12C(α,α) 12C resonance reaction, glancing angle x-ray diffraction, During annealing at all temperatures, Co diffused through the Ti layer and formed CoSi. This phase was confirmed by x-ray diffraction. The Co displaced the Ti to the surface. At 600 °C, Ge diffused to the surface layer, while at 900 °C it was rejected back into the original SiGeC. The sample annealed at 600 °C was subsequently annealed at 900 °C. The Ge in the surface layer was rejected from the surface layer, diffused across the CoSi and back into the SiGeC.

Samples of Si1-x-YGexCy were analyzed with a triple axis high resolution x-ray diffractometer to produce reciprocal space maps. Films with compositions of approximately Si0.77Ge0.20C0.01 vvith thicknesses ranging from 120 nm to 750 nm were found to be pseudomorphic with a tetragonal distortion, εT, near 1%. The tetragonal distortion in pseudomorphic samples with compositions near Si0.47Ge0.50C0.03 with thicknesses ranging from 61 nm to 115 nm was found to be near 2%. The strain increased linearly with Ge concentration even though the Ge:C ratio remained nearly constant. The strain in samples with similar compositions was not a function of thickness. These strain measurements correlated well with results from ion channeling analysis.

Thin heteroepitaxial films of Si1-x-yGexCy have been grown on (100)Si substrates using atmospheric pressure chemical vapor deposition at 550 and 700°C. The crystallinity, composition and microstructure of the SiGeC films were characterized using Rutherford backscattering spectrometry (ion channeling), secondary-ion-mass-spectrometry and cross-sectional transmission electron microscopy. SiGeC films with up to 2% C were grown at 700°C with good crystallinity and very few interracial defects, while misfit dislocations at the SiGe/Si interface were observed for SiGe films grown under the same conditions. This difference indicates that the presence of carbon in the SiGe matrix increases the critical thickness of the grown layers. SiGeC thin films (>110 nm) with up to 3.5% C were grown at 550°C with good crystallinity. The crystallinity of the films grown at lower temperature (550°C) was less sensitive to the flow rate of the C source (C2H4), which enabled growth of single crystal SiGeC films with higher C content.

Single crystal Si0.63Ge0.36C0.01 and amorphous Si0.65Ge0.27C0.08 layers have been oxidized in a wet ambient at 700 °C and 900 °C. The oxide growth has been studied using Rutherford backscattering spectrometry and transmission electron microscopy. A reference sample of Si0.63Ge0.37 was also oxidized in order to determine the influence of C on the oxidation behavior. The lower C content alloy behaved similar to the SiGe alloy. Uniform Si1-xGexO2 was obtained at 700 °C whereas SiO2 was formed at 900 °C, and Ge piled up underneath the oxide. In both cases, C was not detected in the oxide layer. The amorphous Si0.65Ge0.27C0.08 alloy behaved significantly different at both oxidation temperatures in comparison with the crystalline Si0.63Ge0.36C0.01 and Si0.63Ge0.37. Negligible oxidation occurred at 700 °C whereas SiO2 was obtained at 900 °C and the rejected Ge distributed uniformly throughout the SiGeC alloy. It is proposed that fast Ge diffusion during oxidation at 900 °C resulted from diffusion at grain boundaries, since crystallization of the amorphous SiGeC layer occurred in conjunction with oxidation, leading to nucleation of ∼5 nm nanocrystals.

Samples of austenitic 304L stainless steel have been irradiated with 3.4 MeV protons to atotal dose of 1 dpa. The microstructure of the irradiated stainless steel has been quantified by transmission electron microscopy and shown to be similar to that found in neutron-irradiated core components. Constant extension rate tensile tests have been performed at strain rates of 3x10−7 s−1 and 3x10−8 s−1 to strains of up to 27% at 23°C and 288°C. The resulting microstructures were characterized using electron and optical microscopy. Deformation of the unirradiated material is similar to that reported by others in previous work on austenitic steels, consisting of dislocation source activation and formation of dense dislocation networks with increasing strain. In the irradiated samples tested at 288°C, deformation consists of dislocation source activation at grain boundaries punching dislocations through the grain interior to the opposing grain boundaries. The dislocations create channels that are free of radiation-produced defects and on which dislocation motion is concentrated. Dislocations in the channels pile-up at the boundaries, creating regions of highly localized stress concentration at the grain boundary. The mechanism by which this stress is relieved is still unknown. Deformation at 23°C consists of the nucleation and propagation of microtwins across the width of the grains.

We studied interfacial phase formation between copper and copper-alloy films on SiO2 in order to understand how to improve adhesion. CuCr and CuTi alloy and bilayer films on SiO2 were annealed from 400-600°C for 30 min in an N2 + H2 (5%) ambient. The bilayer systems exhibited refractory metal migration from the interface to the surface where they oxidized. In the CuTi bilayer system, an oxidized interfacial Ti layer was observed. Both CuCr and CuTi alloy systems exhibited refractory metal segregation to the interface and surface. Rutherford backscattering spectrometry and Auger electron spectroscopy were used for elemental depth profiling.

Co-deposited Cu-Cr and Cu-Ti thin films were heated at various temperatures in an ammonia ambient in an environmental cell placed into the column of a transmission electron microscope (TEM). The reaction dynamics were observed in situ and recorded on a videotape using a TV camera with 1/30 second time resolution. Nitridation of chromium and titanium was accompanied by the nucleation and growth of copper particles starting at 370 and 580°C, respectively. It was found that in the Cu-Ti system at a temperatures regime of 370-400°C the growth rate behaves under a parabolic law; namely, the process is controlled by diffusion of Cu through the nitride matrix. However, for the Cu-Cr system at temperatures of 610-630°C two growth regimes were observed. In the initial growth stages, the surface reaction is rate-limiting, while for longer nitridation times, growth is diffusion-controlled.

Nitridation of Cu-Cr alloy films under an NH3 ambient was studied using in situ transmission electron Microscopy. Cu-Cr thin films (40–100 nm) were deposited on a single crystal NaCl substrate by electron beam coevaporation, and were heat treated up to 750°C at 2.5–3.0 Torr NH3. The films were also vacuum (10-6 Torr) annealed under the same conditions for comparison. Initial observation of Cu and Cr crystallization occurred at 470°C for both environmental conditions. The nitridation process of Cr to form CrN was observed initially at 580°C and was followed by evolution of faceted Cu grain growth in the CrN Matrix.

Three dimensional visualization of ion channeling spectra was obtained by computer graphics in order to observe the crystalline quality and the strain state of thin films. Pure (100)Si and Si1-xGex (x=0.10, 0.18) layers, epitaxially grown on (100)Si substrates, were channeled along the crystal axis with the 2 MeV He++ ion beam in a UHV target chamber. The data were interpolated using a standard bicubic tensor product B-spline surface with uniform knot sequences in x and y directions. With this modeling technique we have shown the orientation of the major planes in a diamond crystal and the angular displacement of the Ge signal in the SiGe epilayer relative to the Si substrate signal due to the presence of tetragonal distortion in the epilayer.

Co-deposited Cu/Ti thin films were heated at various temperatures in an ammonia ambient in an environmental cell fitted in to the column of transmission electron Microscope (TEM). The reaction dynamics was observed in situ and recorded on video using a TV camera with 1/30 sec. time resolution. The nitridation of titanium accompanied by nucleation and growth of copper particles started at 370°C. Ti2N formed at lower temperatures while TiN was formed above 400°C. The nucleation of crystals occurred simultaneously (within a Minute) throughout the film indicating no effect of electron beam on reaction process. The growth rate of copper particles was observed to vary slightly from one particle to another indicating varying growth rate for different facets.

Solid phase epitaxial regrowth of Sb implanted strained Si1−x Gex alloy layers is reported. Two sets of Si1–xGex alloys with compositions of x=0.08 and x=0.18, MBE grown on (100)Si substrates, were implanted at room temperature with Sb− ions at energies of 200 and 100 keV, respectively, and a dose of 1015cm−2. These alloys were heat-treated in a rapid thermal annealing system at temperatures of 525, 550 and 575°C for durations between 5 and 600 sec. The study of the solid phase epitaxial regrowth was performed by Rutherford backscattering in the channeling mode. The measurements show a significant difference in the regrowth mechanism between the two alloys. For the Si0.92Ge0.00 alloy a fast regrowth process (faster than for Sb implanted Si or Si implanted SiGe layers) occured with an activation energy of 2.92±0.2eV. For the Si0.02Ge0.10 alloy the regrowth took place in two steps: a) a very fast initial process over a short distance, b) a regrowth process of the majority of the amorphous layer.

Rate equations for thermally activated atomic exchange were used to calculate chemical diffusion coefficients for an initially disordered simple-cubic lattice and for a body-centered lattice with equilibrium long-range order. The results show that the chemical enhancement as a function of the enthalpy of mixing saturates, in contrast with results of conventional mean-field theories. Simulations in a disordered alloy agree with the calculations. The existence of longrange order is shown to increase the apparent activation energy for diffusion. The present theory is also shown to provide a simple method of calculating ordering kinetics and equilibrium longrange order, and good agreement with previous experiments and simulations is achieved.

We report a study of the microstructure and surface morphology of co-deposited Al-Ge films. At 200 °C and above, the terminal solid solutions are obtained, whereas at lower temperatures, metastable amorphous or crystalline phases coexist with the Al-rich terminal phase. For film thickness below 200 nm, lateral phase separation is observed with surface grooving which reflects the bulk microstructure. Analysis of the data with a model for the diffusion process shows that the results are consistent with a surface diffusion mechanism. For thicker films, there is a transition into a layered microstructure in which Al segregates to the surface. This transition is explained in terms of the surface and interfacial energies of the phases.

Solid-state amorphization rates have been measured for amorphous Ni1-cMc in contact with the crystalline terminal phase M, (M=Hf or Zr). The interdiffusion coefficient Dis found to depend on the composition of the amorphous phase, with higher Ni content resulting in a higher Dover the composition range Ni67Hf33 to Ni47Hf53. The common tangent composition at which the amorphous alloy is in metastable equilibrium with the terminal crystalline phase is found to be greater than 70 at.% Hf, which is considerably higher than previously reported values. This discrepancy is explained in terms of the interdiffusion coefficient's variation with composition.

The phase- and grain microstructure and surface morphology of Al-Ge films formed by electron beam co-deposition have been studied as a function of the deposition temperature. X-ray diffraction, scanning- and transmission electron microscopy with x-ray fluorescence analysis were used to characterize the films. At room temperature and above, crystalline, phase separated films are obtained. The phase dimensions and surface roughness were observed to increase with the deposition temperature and the dependence yields activation energies for atomic migration consistent with a surface diffusion mechanism. The surface roughness is observed to reflect the microstructure under the surface.

Interdiffusion in a two-dimensional compositionally modulated lattice has been studied by Monte-Carlo simulations. In the initial stages, the interdiffusion coefficient has been observed to change with time due to the development of short-range order simultaneously with the interdiffusion process. When the short-range order parameter approached its limiting value, the diffusion coefficient approached a constant value. The dependence of the interdiffusion coefficient on the modulation wavelength does not agree with the prediction of one-dimensional theories. For ordering alloy systems, the effective interdiffusion coefficient is positive, i.e., an initially present modulation decays in time, for all wavelengths.

We report measurements of interdiffusion in compositionally modulated amorphous Ni-Zr films. We show the dependence of the diffusion coefficient on the modulation wavelength and correlate it with the thermodynamic properties of the Ni-Zr system. A bulk interdiffusion coefficient is extrapolated from the data. Our values for the interdiffusivity in Ni55Zr45 are about three orders of magnitude lower than those obtained by other authors for similar alloys. Possible explanations are suggested.

We report the formation of single-phase amorphous Cu-Er and Ni-Er alloys in bulk form by cold-rolling of composites prepared from elemental foils. As for previously reported cases of metallic glass formation by solid-state reaction, the driving force for the reaction is the negative enthalpy of mixing of the constituent elements. It occurs during deformation close to room temperature. Amorphous Cu7 2 Er2 8 was also produced by high-energy ball-milling of the elemental powders as well as by sputtering and liquid quenching. The alloys obtained were characterized by means of differential scanning calorimetry and x-ray diffraction. The crystallization behavior observed and the radial distribution functions obtained showed good agreement between the alloys prepared by different methods.