bluuebunny/crossref_metadata_2025_split huggingface dataset:
Synthetic Diamond Strength Enhancement Through High Pressure/High Temperature Annealing
Authors: Jackson W. E. , Webb Steven W. 
Published: April 2011

ABSTRACTAnnealing of low inclusion, single crystals of synthetic Type I diamond at 1200–1700°C and 50–60kbar, was observed to increase average crystal compressive fracture strength by as much as 20%. The increase in strength is associated with the healing of lattice dislocations, coalescence of small (< 400 nm) metal inclusions, and dissociation of aggregatenitrogen. Photoluminescence and FTIR spectroscopic data indicate H3 and “A”-type defect centers are unstable relative to NVx and “C”-type defect centers under the conditions of these experiments. Dissociation rate is greater in the (111) growth sector than in the (100). Changes in residual lattice strain of the samples could not be detected using Raman spectroscopy and optical microscopy. A model reaction of the type, 2V + N2V = NV2 + NV, in which N = nitrogen and V = vacancy (i.e., N2V = H3 center) is proposed which provides a qualitative thermodynamic understanding of the observations reported in this study consistent with previous results of other researchers. In addition, photoluminescence examination of smaller crystals produced from a quench of early stage non-equilibrium growth reveal a lower concentration of aggregate nitrogen than those quenched from late stage growth suggesting that nitrogen may aggregate via in situ annealing processes. Ultimately, understanding mechanisms to improve synthetic single crystal diamond strength will lead to improved tools which utilize such crystals (e.g., drill bits and saws for cutting stone and concrete) which constitute a market of ≈ $2b worldwide.
Processing-Microstructure-Tensile Property of Vapor Grown Carbon Fiber Reinforced Carbon Composite
Authors: Ting Jyh-Ming 
Published: April 2011

ABSTRACTIn contrast to the form in which other carbon fibers are produced, vapor grown carbon fiber (VGCF) is produced from gas phase precursors in the form of individual fibers of discrete lengths. VGCF can be harvested as a mat of semi-aligned, semicontinuous fibers, with occasional fiber branching and curling. The use of VGCF mats as reinforcement result in composites which exhibit unique microstructure and physical properties that are not observed in other types of carbon composites. This paper describes the processing of VGCF mats reinforced carbon composites, and its unique microstructure and properties. Utilization of fiber tensile properties, as well as thermal conductivity, in the composites is discussed. Comparison of experimental results from various VGCF composites to theory indicates that mechanical properties are more strongly affected by characteristics of VGCF mat than are thermal conductivity. The implications of this relationship favors applications for thermal management where structural demands are less stringent.
Deposition of Diamond-Like Carbon Films by PECVD
Authors: Park Kyu Chang , Chun Soo Chul , Song Kyo Jun , Park Min , Oh Myung Hwan , Choi Seong Soo , Park Jung Hae , Yang In Sang , Jang Jin 
Published: April 2011

ABSTRACTWe have studied the structural properties of hydrogenated carbon films deposited by plasma enhanced chemical vapor deposition (PECVD). The substrate holder in reaction chamber could be biased and be heated. The Raman peak intensity at 1350 cm−1 was increased by reducing CH4 flow rate. The film structure changed from soft a-C:H to hard carbon with decreasing CH4 flow rate, resulted from increased self-bias. The 1520 cm−1 peak shifts to higher frequency by reducing the CH4flow rate, probably resulted from the increased internal stress.
Effect of Microstructure in Metal Reinforced Composite CVD Diamond Films on Mechanical Properties
Authors: Hoehn J. W. , Bahr D. F. , Heberlein J. , Pfender E. , Gerberich W. W. 
Published: April 2011

ABSTRACTComparison of behavior observed during deadhesion of CVD diamond films and compositional analysis of their microstructure allows a correlation between microstructure and mechanical behavior to be made. Diamond films were grown in a DC Triple Torch Reactor using a mixture of methane and hydrogen on molybdenum substrates. To address the issue of voids at the interface, a metal binder was electroplated after the nucleation of individual diamond crystals on the substrates. The films were completed by growing a layer of diamond upon the composite layer. Interfacial composition and structure of the films are characterized by a x-ray, Auger, and Raman spectroscopy. A carbide may act to enhance the adhesion via chemical bonding between the substrate and film. Diffusion of the binder into the substrate and film is also important for mechanical properties and is confirmed by x-ray mapping. It is suggested that a diamond like carbon layer acts to enhance the adhesion of the film to the substrate.
Diamond-Like Carbon Deposition for Tribological Applications at Los Alamos National Laboratory
Authors: Walter K. C. , Nastasi M. , Kung H. , Kodali P. , Munson C. , Henins I. , Wood B. P. 
Published: April 2011

ABSTRACTDiamond-like carbon (DLC) films have been deposited on silicon using two deposition techniques. Both deposition techniques used acetylene (C2H2) plasmas as the carbon/hydrogen source. One technique, that is relatively well known, employs an rf-plasma with an associated self-bias on the substrate. DLC films have also been deposited using a pulsed-bias method. Coatings of various thickness have been deposited using both deposition methods, and various combinations of gas pressure and bias. Coating characteristics, such as composition, density, and sp3 content, of selected films will be presented. For each deposition technique, the correlation between coating characteristics, mechanical properties and tribological behavior is presented.
Correlations Between the Substrate Temperature, Properties and Tribological Performance of Sputter-Deposited Amorphous Carbon Films
Authors: Mounier E. , Juliet P. , Quesnel E. , Pauleau Y. , Dubus M. 
Published: April 2011

ABSTRACTAmorphous carbon films have been deposited on various grounded substrates by direct current (DC) magnetron sputtering from a graphite target in an argon discharge. The argon pressure and sputtering power density were fixed at 0.25 Pa and 2.65 W cm−2, respectively. The substrate temperature was varied from 50 to 350°C. The hydrogen content determined by ERDA and the electrical resistivity of films were found to be dependent on the base pressure in the deposition chamber and substrate temperature. The mass density of films evaluated from RBS data and compressive residual stresses in the films decreased with increasing substrate temperature from 2.2 to 1.4 g cm−3 and - 0.6 to - 0.2 GPa, respectively. The friction coefficient and wear rate of about 2-μm-thick carbon films deposited on polished stainless steel disks were determined by alumina ball-on-disk tribological measurements conducted in dry air under a load of 4.9 N with a sliding velocity of 10 m min−1 for 105 cycles. The tribological performance of carbon-coated disks are correlated with the deposition temperature and physical characteristics of carbon films.
Simulation of Uniformity and Lifetime Effects in Collimated Sputtering
Authors: Taita R. N. , Dewb S. K. , Tsaic W. , Hodul D. , Brett M. J. , Smy T. 
Published: April 2011

AbstractCollimated sputtering has been successful in providing good contact barriers for sub-half micron contacts with aspect ratios of 3 and greater. This approach does present drawbacks however, particularly in terms of reduced deposition rates and degraded film uniformity. The flux collected on the collimator leads to closing off of the cells, further reducing deposition rate on the wafer and limiting the life of the collimator. This paper demonstrates simulation of the filling of the collimator with different system configurations and pressures using the SIMSPUD vapor transport and SIMBAD thin film growth simulators. The model can determine collimator filling uniformity, blanket film uniformity, angular distribution of collimated sputter flux, and lifetime of the collimator. Given the target erosion profile, system geometry, and deposition rate, collimator lifetime can be predicted. The model indicates that for a 300 mm diameter source a drop in operating pressure from 0.67 Pa to 0.27 Pa has little effect on collimator life in terms of kWh, while increasing collimator life in terms of wafers by about 50%. The increase in the number of wafers processed comes at the expense of a small loss of uniformity.
In-Line Temperature Monitoring of Rapid Thermal Annealing Processes
Authors: Oh Minseok , Nguyenphu Binh , Fiory Anthony T. 
Published: April 2011

AbstractProcess control for rapid thermal annealing (RTA) steps in silicon integrated circuit manufacturing is highly dependent on the repeatability of wafer annealing temperatures. The heating lamps in RTA ovens are controlled by an infrared pyrometer in a feedback-control loop. Methods currently in production allow some variability in annealing temperature, owing to the variability of wafer backside emissivities and the fixed emissivity value used for each process recipe. To provide an independent in-situ temperature sensor with potentially improved accuracy, an RTA oven equipped with a ripple pyrometer was used for passive data collection. Results obtained over extensive wafer processing indicate that the ripple temperatures have a correlation with electrical tester data and that the ripple pyrometer repeatability is better than 3°C at 1 standard deviation.
Integrated Processing of Silicon Oxynitride Alloy Dielectrics by Plasma-Assisted Oxidation, Chemical Vapor Deposition, and On-Line Rapid Thermal Annealing
Authors: Hattangady S. V. , Niimi H. , Gandhi S. , Lucovsky G. 
Published: April 2011

AbstractThin film dielectrics have been prepared in a cluster processing system with chambers for plasma-assisted, rapid-thermal processing, and on-line Auger electron spectroscopy (AES). A low-thermal budget process for the formation of homogeneous silicon oxynitride (OXN) alloy films is presented. This Na2-based plasma-CVD process has (i) increased process latitude for the formation of N-rich alloys, and (ii) results in lower bonded-H concentrations, in comparison with a similar NH3-based process. Gate dielectric formation consists of (i) a 300°C plasma-assisted oxidation for removal of residual hydrocarbons, and formation of an Si-SiO2 interface protected by ∼0.5-0.6 nm of oxide, (ii) a 300°C plasma-assisted CVD of oxynitride films from N2O, N2, and SiH4, and (iii) a 30 s, 900°C post-deposition rapid-thermal anneal in an ambient that contains sufficient oxygen to prevent decomposition of the Si/SiO2 interface. On-line AES and off-line infrared (IR) spectroscopy have been used to characterize chemical bonding, showing that the deposited films are pseudo-binary alloys lying on a join-line from SiO2 and Si3N4 in a ternary composition diagram. Electrical characterization of MOS capacitors, consisting of O-OXN-O structures, using C-V techniques is discussed.
Gate Oxynitride Grown in N2O and Annealed in NO Using Rapid Thermal Processing
Authors: Sun S. C. , Chen C. H. , Lou J. C. , Yen L. W. , Lin C. J. 
Published: April 2011

AbstractIn this paper a new technique for the formation of high quality ultrathin gate dielectrics is proposed. Gate oxynitride was first grown in N2O and then annealed by in-situ rapid thermal NO-nitridation. This approach has the advantage of providing a tighter nitrogen distribution and a higher nitrogen accumulation at or near the Si-SiO2 interface than either N2O oxynitride or nitridation of SiO2 in the NO ambient. It is applicable to a wide range of oxide thickness because the initial rapid thermal N2O oxidation rate is slow but not as self-limited as NO oxidation. The resulting gate dielectrics have reduced charge trapping, lower stress-induced leakage current and significant resistance to interface state generation under electrical stress
A Process Model for Thin Film Deposition by Sputtering: Study for Bottom Coverage of Sub-Micron Contact Holes
Authors: Fang C. C. , Prasad V. 
Published: April 2011

ABSTRACTTitanium (Ti) is widely used to improve the contact resistance with the underlying substrate in contact or via filling applications. As the critical dimensions of the electronic devices fall below 0.5 micron and the aspect ratio of the contact holes increases, it becomes more difficult to obtain a good coverage at the bottom of the contact. In our continuing effort to develop a better technology for the metallization of sub-micron liners [1, 2] using the sputtering process, we have constructed a feature scale model and have initiated an extensive study on the coverage of the contact liners. Our objective is to search for an alternative process technique to replace the current, widely-used collimated sputtering with the help of a realistic model that accounts for all important deposition phenomena such as the effect of the working pressure and the ion bombardment. Since the mean free path of the deposited atoms, particularly in a low pressure system, is comparable to the surface feature of the substrate, particle methods are more appropriate for the modeling of thin film formation phenomena and predictions of microstructures than the continuum approach. This is specially true in the case of sputter-deposition. In this paper, a simple two dimensional molecular dynamics model is used to predict the growth of the thin film. It allows us to study the effects of the physical parameters such as working pressure and ion energy as well as the influence of the geometric configuration, e.g., distance between the target and the substrate and the size of the contact hole. Simulations for long-throw/low-pressure sputtering and ionized magnetron sputtering are presented together with the experimental results for collimated sputtering.
A Model for Texture Evolution in a Growing Film
Authors: Knuyt G. , Quaeyhaegens C. , D’Haen J. , Stals L. M. 
Published: April 2011

ABSTRACTA model for the texture evolution of a growing film was developed, where the tendency for the lowest possible surface energy was taken as the driving force. Two main directions were considered in the orientation distribution of the columns. An initially isotropic distribution was found to evolve to a bimodal one and finally to a distribution with a sharp peak around the orientation with the smallest surface energy. For specific initial conditions the texture turns over from one orientation to the other one. The calculated textures showed a continuous sharpening around orientations with a local or absolute minimum in the surface energy. Various calculated phenomena concerning the texture evolution could be observed on PVD deposited TiN coatings.
Computational Simulation of Photoluminescence and Reflectivity Spectra of a Strained Layer Superlattice
Authors: Di Blasio M. , Averous M. 
Published: April 2011

ABSTRACTPowerful mathematical tools have made it possible to simulate the optical spectra of strained layer superlattices. The results of these calculations are compared to experimental ones obtained on ZnS-ZnSe SLSs. The photoluminescence spectra is dominated by a single major peak with a long asymmetrical tail end or a secondary peak at lower energies. This secondary peak or tail end is attributed to the disorder within the superlattice. The PL spectra is simulated using a novel model based on the following parameters; the free exciton energy, the strain/stress state between the lattice constants, the probability of an occurrence of a dislocation, the probability that the dislocation generates and propagates and the critical thickness. The reflectivity simulation is also novel and is based on an impedance in a spatial dispersion model. It is essential to consider the strain that is induced in the SL, when the dielectric constant is dependent on the variation of the frequency near the fundamental transition energies. As a result only normal incidence is considered.
Emissivity of Rough Silicon Surfaces: Measurement and Calculations
Authors: Xu H. , Sturm J.C. 
Published: April 2011

ABSTRACTThe directional reflectance and approximate emissivity of rough silicon wafers were measured by reflection measurements using a single point detector and a broad area illumination source. Experiments were also performed to determine the cone angle of the incident light required to properly measure the emissivity of rough backsides. Based on surface roughness parameters acquired with an Atomic Force Microscope, reflectance calculations were performed within the framework of the Beckmann-Spizzichino model. The results are qualitatively consistent with experimental observations.
1D and 2D Monte Carlo Simulations of Pulsed Laser Ablation of Si/Ga Into Ar/O2with a Substrate
Authors: Capewell D. L. , Goodwin D. G. 
Published: April 2011

ABSTRACTThe Direct Simulation Monte Carlo (DSMC) method is applied to the problem of pulsed laser deposition in both ID and 2D axisymmetric simulations. A source of target atoms expands into a cylindrical volume containing a background gas at room temperature and pressures up to 100 mTorr in the presence of a diffusely reflecting substrate. At regular intervals, the density and temperature of each species are computed. Particle flux and energy per particle incident on the substrate are also monitored as functions of time. The simulation results qualitatively compare, well with experimental plume diagnostics, with measured film growth rates as a function of background gas pressure, and with measured changes in film growth stoichiometry resulting from the introduction of a background gas into a two-component PLD system.
Simulation of Uniformity and Lifetime Effects in Collimated Sputtering
Authors: Tait R.N. , Dew S.K. , Tsai W. , Hodul D. , Brett M.J. , Smyd T. 
Published: April 2011

ABSTRACTCollimated sputtering has been successful in providing good contact barriers for sub-half micron contacts with aspect ratios of 3 and greater. This approach does present drawbacks however, particularly in terms of reduced deposition rates and degraded film uniformity. The flux collected on the collimator leads to closing off of the cells, further reducing deposition rate on the wafer and limiting the life of the collimator. This paper demonstrates simulation of the filling of the collimator with different system configurations and pressures using the SIMSPUD vapor transport and SIMBAD thin film growth simulators. The model can determine collimator filling uniformity, blanket film uniformity, angular distribution of collimated sputter flux, and lifetime of the collimator. Given the target erosion profile, system geometry, and deposition rate, collimator lifetime can be predicted. The model indicates that for a 300 mm diameter source a drop in operating pressure from 0.67 Pa to 0.27 Pa has little effect on collimator life in terms of kWh, while increasing collimator life in terms of wafers by about 50%. The increase in the number of wafers processed comes at the expense of a small loss of uniformity.
Analytical and Numerical Modeling of Surface Morphologies in Thin Films
Authors: Genin François Y. 
Published: April 2011

ABSTRACTExperimental studies have shown that strains due to thermal expansion mismatch between a film and its substrate can produce very large stresses in the film that can lead to the formation of holes and hillocks. Based on a phenomenological description of the evolution of a solid surface under both capillary and stress driving forces and for surface and grain boundary self-diffusion, this article provides, for the first time, analytical and numerical solutions for surface profiles of model geometries in polycrystalline thin films. The results can explain a variety of surface morphologies commonly observed experimentally and are discussed to give some practical insights on how to control the growth of holes and hillocks in thin films.
Theory and Computer Simulation of Grain-Boundary and Void Dynamics in Polycrystalline Conductors
Authors: Maroudas Dimitrios , Pantelides Sokrates T. 
Published: April 2011

AbstractMicrostructure evolution in polycrystalline metallic thin films under stress and electric current underlies many reliability issues in microelectronics. This paper presents a quantitative analysis of grain-boundary and void dynamics based on the coupling between bulk and interfacial mass transport phenomena with elastic deformations and current stressing. The formation and growth of intergranular voids in bamboo-structure conductor lines due to stresses that develop during processing is analyzed. The analysis is aided by self-consistent simulation of bulk and grain-boundary diffusional processes using bicrystal models with elastic grains. A systematic analysis is presented of the morphological evolution of transgranular voids in aluminum lines under current densities that are typical of electromigration testing. The effects of the electric field and surface properties on the morphological stability of voids are examined and morphologies that bifurcate from rounded or wedge-like void shapes are predicted. The theoretical results are discussed in the context of experimental data for void propagation under electromigration conditions.
A Comparison of Electromigration in Bulk and Thin - Film Aluminum
Authors: Oates Anthony S. 
Published: April 2011

AbstractThe dominant mode of electromigration in polycrystalline Al thin - film conductors is along grain boundaries when the conductor width is significantly larger than the grain size. Integrated circuit feature sizes, however, have now decreased to the point where microstructures are no longer polycrystalline, but are near - bamboo. Electromigration must operate along pathways other than grain boundaries in the bamboo segments. Here drift velocity data is presented for bamboo microstructures with widths down to 0.6 μm and compared with drift data available in the literature for thin films with a variety of microstructures and bulk Al. Bamboo films show lower drift velocities and higher activation energies for drift than polycrystalline films. The data for bamboo microstructures is consistent with drift measurements performed on bulk Al indicating that the transport mechanism in bamboo films is identical to that in bulk Al.
Structural and Electrical Characterization of Si-Implanted TiN as a Diffusion Barrier for Cu Metallization
Authors: Mcarthur W.F. , Ring K.M. , Kavanagh K.L. 
Published: April 2011

AbstractThe feasibility of Si-implanted TiN as a diffusion barrier between Cu and Si was investigated. Barrier effectiveness was evaluated via reverse leakage current of Cu/TixSiyNz/Si diodes as a function of post-deposition annealing temperature and time, and was found to depend heavily on the film composition and microstructure. TiN implanted with Si28, l0keV, 5xl016ions/cm2 formed an amorphous ternary TixSiyNz layer whose performance as a barrier to Cu diffusion exceeded that of unimplanted, polycrystalline TiN. Results from current-voltage, transmission electron microscopy (TEM), and Auger depth profiling measurements will be presented. The relationship between Si-implantation dose, TixSiyNz structure and reverse leakage current of Cu/TixSiyNz/Si diodes will be discussed, along with implications as to the suitability of these structures in Cu metallization.