bluuebunny/crossref_metadata_2025 huggingface dataset:
In-Line Temperature Monitoring of Rapid Thermal Annealing Processes
Authors: Oh Minseok , Nguyenphu Binh , Fiory Anthony T.
Published: April 2011

Process 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

Thin 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

In 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

Titanium (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

A 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

Powerful 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

The 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

The 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

Collimated 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

Experimental 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

Microstructure 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

The 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

The 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.
Microstructural Control of Internal Electromigration Failure in Narrow Al-Cu-Si Lines
Authors: Morris J.W. , Kim C. , Kang S.H.
Published: April 2011

Al-Cu lines of submicron width ordinarily have quasi-bamboo microstructures that contain both bamboo grains and polygranular segments. The usual mechanism of internal electro-migration failure in such lines involves the formation of a transgranular void across a bamboo grain at the upstream end of a long, polygranular segment. The voiding is preceded by the depletion of Cu from both the polygranular segment and the upstream bamboo grain. At least three metallurgical mechanisms are available to inhibit this failure mechanism and improve the useful lifetime of the line. First, the line can be annealed after patterning to break up long polygranular segments. Second, the line can be aged at relatively low temperature to stabilize the distribution of Cu and retard its depletion from polygranular segments. Third, the line can be subjected to reverse currents to restore the distribution of Cu and provide a Cu reservoir. Each of these methods has been demonstrated in the laboratory environment.
Control of the Microstructure of Al Metallization by Graphoepitaxy
Authors: Van Den Homberg Marc J.C. , Alkemade P.F.A. , Hurd J.L. , Leusink G.J. , Radelaar S.
Published: April 2011

Microstructure is an important factor determining the lifetime of Al metallization lines. Deposition conditions, substrate material, alloying elements, and anneal treatments are the key parameters that influence microstructure. In this work we explore the use of graphoepitaxy as a tool for additional control over the grain structure of metallization lines. Onto a submicrometer topography in SiO2 (viz., a large number of parallel grooves), a pure Al film is grown by dc magnetron sputtering, followed by an in situ rapid thermal anneal. The topography of the annealed Al is investigated by cross section SEM. It is observed that if it is heated up to its melting point, Al fills the grooves and leaves the ridges between the grooves uncovered. X-Ray Diffraction, TEM, and Backscatter Kikuchi Diffraction are used to determine the global as well as the local crystallographic orientation of the grains in the quenched aluminum. The analyses are performed for various anneal and cool down treatments. Depending on the treatment, the Al lines in the grooves are either polycrystalline with an almost perfect (111) texture, or single crystalline but with a gradual change of 0.067°/μm in orientation. In the latter case, there is no preferred orientation. The single crystalline Al lines will be used as a starting point for the fabrication of model systems for fundamental electromigration studies.
The Electromigration and Failure Behaviour in Layered Tungsten Via Structures
Authors: Elliott L.J. , Spooner T. , Rose J.H. , Shuman R.
Published: April 2011

This work investigated the electromigration and failure behaviour of layered tungsten vias. It has long been recognized that the flux divergence caused by the tungsten-aluminum interface is an area of high reliability risk. In an attempt to lower this risk, several process experiments were initiated. The thickness (500Å, 800Å, and 1200Å), composition (TiN and Ti), and etch and rinse rates of the underlaying layers of the tungsten plugs were varied. Test structures consisting of a chain of eight M1 to M2 vias were placed on electromigration testing. Their variability in lifetimes, resistance vs. time characteristics and failure behaviour is reported. The fail sites were characterized using TEM analysis and FIB cross-sections. Based on these results process improvements for improved reliability were developed.
XRD and Tem Characterization of Cathodic MnO2 and Discharge Products in the Li-MnO2 Cell
Authors: Shao Y. , Hackney S.A. , Cornilsen B.C.
Published: April 2011

The crystal structures of the undischarged, heat-treated electrolytic manganese dioxide (HEMD) and discharge products are characterized by high spatial resolution convergent beam electron diffraction (CBED). The results are compared with the x-ray diffraction (XRD) patterns characterized by broad, diffuse peaks. The CBED results for HEMD show that the starting cathodic material has the pyrolusite space group, but with a range of c/a ratios. The variability of the lattice parameter from grain to grain is found to coincide with the broadening on the low angle side of the XRD peaks. The CBED patterns of discharge products suggest a reduction range in c/a ratios and the formation of another phase.
Preparation and Properties of Manganese Dioxide/Polypyrrole Composites as an Active Material for Lithium Secondary Batteries
Authors: Kuwabata Susumu , Yoneyama Hiroshi
Published: April 2011

Composite powder of spinel LiMn2O4 and polypyrrole has been successfully prepared by injecting pyrrole into an HClO4 aqueous solution containing suspended LiMn2O4 powder which was used as an oxidizing agent for polymerization of pyrrole. The amount of LiMn2O4 in the composite increased with increasing the amount of the suspended oxide powder in the bath, whereas decrease in the amount of ClO4− dopant was observed. Charge-discharge tests of the resulting composite taken in a mixed solvent of propylene carbonate and 1,2-dimethoxyethane (1:1) containing 1 mol dm−3 LiClO4 revealed that polypyrrole of the composite worked well as an active material as well as a conducting network for the incorporated LiMn2O4 powder. Elemental analyses of the charged and discharged composites showed that Li+ cation alone was involved in the charge-discharge reactions of the LiMn2O4/PPy composite.
XPS Analysis of Lithium Surface and Modification of Surface State for Uniform Deposition of Lithium
Authors: Kanamura K. , Shiraishi S. , Takehara Z.
Published: April 2011

The surface modification of lithium deposited at various current densities in propylene carbonate containing 1.0 ml dm−3 LiCIO4 was performed by addition of various amount of HF into the electrolyte, in order to investigate the effect of the HF addition on the surface reaction of lithium. XPS and SEM analyses showed that the surface state of lithium was influenced by the concentration of HF and the electrodeposition current. These two parameters are related to the chemical reaction rate of the lithium surface with HF and the electrodeposition rate of lithium, respectively. The surface modification was highly effective in suppressing lithium dendrite formation when the chemical reaction rate with HF was greater than the electrochemical deposition rate of lithium.
Advanced Catalytic Electrode Development for Nickel-Hydrogen Batteries
Authors: Coates D. K. , Grindstaff B. K. , Hoofnagle P. S. , Chiappetti D. P.
Published: April 2011

Low catalyst loading gas diffusion membrane electrodes have been developed for spaceflight qualified nickel-hydrogen (NiH2) batteries. These electrodes involve the use of new electrode designs and innovative manufacturing methods. Supported catalysts, mixed catalysts and alternative catalyst systems have been developed to decrease catalyst loading levels, and therefore reduce electrode cost, without reducing performance or reliability. This advanced electrode technology has currently accumulated more than 13,000 charge/discharge cycles in real-time, low-earth-orbit (LEO) testing. The technology has been incorporated into several nickel-hydrogen spaceflight programs including the TUBSAT B spacecraft, built by the Technical University of Berlin and launched in January of 1994 aboard a Russian Cyclone rocket.
Recent Progress in the Development of a Lightweight Nickel Electrode
Authors: Britton Doris L.
Published: April 2011

The nickel-hydrogen (Ni-H2) cell is rapidly replacing nickel-cadmium (Ni-Cd) cell as the system of choice for aerospace applications where weight is crucial. The heavy-sintered nickel electrode used in this cell accounts for about 38% of the cell weight. The use of small diameter fiber nickel electrodes will reduce the weight and improve the specific energy of the state-of-the-art Ni-H2 cell by about 50%. One advantage of this small diameter nickel fiber material is the increase in the surface area available for the deposition of active material. Initial testing of this type of electrode is very promising. This electrode is also applicable to other nickel-based batteries, such as nickel-zinc, nickel-iron, and nickel-metalhydride, both for space and commercial applications.
Electrochemical Properties of Carbons Obtained From Precursors of Electrochemically Polymerized Polymers
Authors: Hashizume Kenichi , Tsutsup Miho , Kaneko Tomohiko , Otani Sugio , Yoshimura Susumu
Published: April 2011

Electrochemically polymerized polymers from pyrrole, fluoranthene and pyrene were heat-treated at temperatures between 600 to 3000 °C. The electrochemical properties of these heat-treated samples were examined by chronoamperometry using an electrolyte solution of IM LiClO4in propylene carbonate. Lithium doping capacities of carbons from fluoranthene and pyrrole polymer heat-treated at 3000 °C were 1.5 and 1.2 times that of the theoretical capacity of graphite as LiC6, respectively.
Characteristics of Mesophase Pitch-Based Carbon Fibers as Anode Materials for Lithium Secondary Cells
Authors: Tamaki Toshio
Published: April 2011

Mesophase pitch-based Carbon Fibers(MPCF) have been investigated as anode materials for lithium secondary cells by examining their physical and electrochemical properties. Discharge capacity and initial charge-discharge efficiency of the materials were studied in relation to the heat treatment temperatures of MPCF. Carbon fiber which was heat treated at about 3,000’C gave the highest discharge capacity(over 300mAh/g), good efficiency (92%) and superior current capability (600mA/g). Carbon fiber heat treated at less than 1,000·C, also has superior discharge capacity(over 500mAh/g) at the first cycle, however efficiency was relatively low. Some of the relationships between structure of MPCF and electrochemical properties are discussed below.
Electronic/Ionic Conductivity and Oxygen Diffusion Coefficient af the Sr-Fe-Co-O System
Authors: Ma B. , Park J.-H. , Segre C. U. , Balachandran U.
Published: April 2011

Oxides in the Sr-Fe-Co-O system exhibit both electronic and ionic conductivities. Recently, the Sr-Fe-Co-O system attracted great attention because of its potential to be used for oxygen-permeable membranes that can operate without electrodes or external electrical circuitry. Electronic and ionic conductivities of two compositions of the Sr-Fe-Co-O system, named SFC-1 and SFC-2, have been measured at various temperatures. The electronic transference number is much greater than the ionic transference number in SFC-1, whereas the electronic and ionic transference numbers are very similar in SFC-2. At 800°C, the electronic and ionic conductivities are ≈76 and ≈4 S•cm−1, respectively, for SFC-1; whereas, for SFC-2, the electronic and ionic conductivities are ≈10 and∼1S•cm−1, respectively. By performing a local fitting to the equation σ • T = Aexp(-Ea/ kT), we found that the oxide ion activation energies are 0.92 and 0.37 eV, respectively, for SFC-1 and SFC-2. The oxygen diffusion coefficient of SFC-2 is ≈ 9 x 10−7cm2/sec at 900°C.
Growth of Vacancy Clusters During Post-Irradiation Annealing of Ion Implanted Silicon,
Authors: van Veen A. , Schut H. , Rivera A. , Fedorov A.V.
Published: April 2011

Annealing experiments of deuterium implanted silicon have been performed while positron beam analysis was used for monitoring the cavity growth. The experiments indicate up to annealing temperature 500° C similar defect evolution for both the low dose of 1016 cm-2 as for a 3 times higher dose. At this temperature the deuterium stabilized vacancy clusters dissociate and only in the case of the high dose micro-cavities are formed. Monte Carlo simulations of vacancy cluster growth in silicon based on vacancy cluster dissociation energies, calculated with the Stillinger Weber potential, have been performed. The results indicate that for low initial defect concentrations vacancy clusters might be hindered to grow because the vacancy binding energy of the clusters does not increase monotonically with the cluster size. Only a high concentration guarantees that growth barriers will be overcome.
Effects of Arsenic Deactivation on Arsenic-Implant Induced Enhanced Diffusion in Silicon
Authors: Dokumaci O. , Law M.E. , Krishnamoorthy V. , Jones K.S.
Published: April 2011

The enhanced diffusion of boron due to high dose arsenic implantation into silicon is studied as a function of arsenic dose. The behavior of both the type-V and end-of-range loops is investigated by transmission electron microscopy (TEM). The role of arsenic deactivation induced interstitials and type-V loops on enhanced diffusion is assessed. Reduction of the boron diffusivity is observed with increasing arsenic dose at three different temperatures. The possible explanations for this reduction are discussed.
Growth of Si1-x.Snx Layers on Si by Ion-Beam-Induced Epitaxial Crystallization (Ibiec) and Solid Phase Epitaxial Growth (Speg)
Authors: Kobayashi N. , Hasegawa M. , Hayashi N. , Katsumata H. , Makita Y. , Shibata H. , Uekusa S.
Published: April 2011

Synthesis of metastable group-IV binary alloy semiconductor thin films on Si was achieved by the crystalline growth of Si1-xSnx layers using Sn ion implantation into Si(100) followed either by ion-beam-induced epitaxial crystallization (IBIEC) or solid phase epitaxial growth (SPEG). Si(100) wafers were implanted at room temperature with 110keV 120Sn ions to a dose of 1×1016 cm-2 (x=0.029 at peak concentration) and 2x1016 cm-2 (x=0.058 at peak concentration). By this process about 90nm-thick amorphous Si1-xSnx and about 30nm-thick deeper amorphous Si layers were formed. IBIEC experiments performed with 400keV Ar ions at 300–400°C have induced an epitaxial crystallization of the amorphous alloy layers up to the surface and lattice site occupation of Sn atoms for samples with the lower Sn concentration (LC). XRD analyses have revealed a partial strain compensation for the crystallized layer. Samples with the higher Sn concentration (HC) have shown an epitaxial crystallization accompanied by defects around the peak Sn concentration. SPEG experiments up to 750°C for LC samples have shown an epitaxial crystallization of the fully strained alloy layer, whereas those for HC samples up to 750°C have revealed a collapse of the epitaxial growth around the interface of the alloy layer and the Si substrate. Photoluminescence (PL) emission from both IBIEC-grown and SPEG-grown samples with the lower Sn concentration has shown similar peaks to those by ion-implanted and annealed Si samples with intense I1 or I1-related (Ar) peaks. Present results suggest that IBIEC has a feature for the non-thermal equilibrium fabrication of Si-Sn alloy semiconductors.
Structural Disorder in Hard Amorphous Carbon Films Implanted with Nitrogen Ions
Authors: Freire F.L. , Franceschini D.F. , Achete C.A. , Brusa R.S. , Mariotto G. , Karwasz G. P. , Canteri R.
Published: April 2011

Hard amorphous hydrogenated carbon films deposited by self-bias glow discharge were implanted at room temperature with 70 keV-nitrogen ions at fluences between 2.0 and 9.0×1016 N/cm2. The implanted samples were analyzed by Raman spectroscopy, SIMS and positron annihilation spectroscopy (Doppler broadening technique with the determination of the parameter S. For samples implanted with 2.0x1016 N/cm2 the S parameter follows the vacancies depth profile predicted by Monte Carlo simulation. For higher fluences we observed a reduction in the measured value of S. This result is discussed in terms of both hydrogen loss and structural modifications(increase of disorder at local scale and of the number of graphitic domains) induced in the carbon film by ion implantation.
Bombarding Effects of Gas Cluster Ion Beams on Sapphire Surfaces; Characteristics of Modified Layers and their Mechanical and Optical Properties
Authors: Takeuchi D. , Matsuo J. , Yamada I.
Published: April 2011

Gas cluster ions contain tens, hundreds or even more than thousands of atoms or molecules as ionized particles. It has been shown that the bombarding effects of gas cluster ions on solid surfaces are quite different from those by monomer ions and involve unique material processing characteristics. In order to make clear the bombarding effects, a study of surface modification of sapphire by Ar and CO2 gas cluster ion beams has been performed.
Thickness of the damaged layer and surface roughness produced on sapphire depends strongly on cluster ion energy. Damage layer thickness on a sapphire surface bombarded by 150 keV clusters with average size of about 3000 atoms was 40Å. No significant difference was observed in IR transmittance after cluster bombardment. Mechanical properties of sapphire surfaces can be changed by cluster irradiation at a dose of 1011 ions/cm2.
Suspended Conductive Polymer Bridges From Ion Implanted Polymers
Authors: Kaufmann James , Moss Mary G. , Wang Yongqiang , Giedd Ryan E.
Published: April 2011

Photolithographic processing capabilities of ion implanted polymer (IIP) films spin-coated onto silicon substrates were evaluated to determine the optimum conditions for producing stable, small geometry devices. Films which had a thickness approximately equivalent to or less than the mean range of ions in the polymer had good quality and stability, and could be patterned without change of conductivity to form small geometry resistors with dimensions of 10 to 50 micrometers. Sixteen-element, packaged resistor arrays were produced from ion implanted poly(styrene-acrylonitrile) films. High quality films with resistivities from 400 ohms/square to 10 megohms/square could be produced by the ion implantation technique. Suspended conducting polymer bridges were formed from IIP resistors by etching of a sacrificial layer underlying the IIP film. Electrical and mechanical properties of the bridges are presented.
Structural and Optical Properties of Rare-Earth Doped Lithium Niobate Waveguides Formed by Mev Helium Implantation
Authors: Herreros B. , Lifante G. , CussÓ F. , Kling A. , Soares J.C. , Da Silva M.F. , Townsend P.D. , Chandler P.J.
Published: April 2011

Results of investigations of optical waveguides formed by high energy helium implantation into lithium niobate codoped with 5 mol% MgO and 1 mol% Tm3+ or 1 mol% Er3+ are reported. A comparative study of structural and luminescence properties between implanted and untreated samples has been performed by means of Rutherford backscattering (RBS) combined with channeling and photoluminescence methods, respectively in order to investigate residual lattice damage and the incorporation of the optical active rare earths. For the case of Tm a full substitutional incorporation on the lithium site and a high crystal quality in both bulk and implanted waveguide material has been found. For Er doped lithium niobate the channeling results show a fraction of Er randomly incorporated or forming precipitates and a deterioration of the waveguide's lattice. The optical investigations show in both cases only a slight broadening of the emission lines of the rare earths in the waveguides compared to the bulk material.
Nanocrystal Formation Via Yttrium Ion Implantation into Sapphire
Authors: Hunt E. M. , Hampikian J. M. , Poker D. B.
Published: April 2011

Ion implantation has been used to form nanocrystals in the near surface of single crystal A12O3. The ion fluence was 5 x 1016 Y+/cm2, and the implant energies investigated were 100, 150, and 170 keV. The morphology of the implanted region was investigated using transmission electron microscopy, x-ray energy dispersive spectroscopy, Rutherford backscattering spectroscopy and ion channeling. The implantation causes the formation of an amorphous surface layer which contains spherical nanosized crystals with a diameter of ∼13 nm. The nanocrystals are randomly oriented and exhibit a face-centered cubic structure with a lattice pmeter of ∼4.1 A ± .02 A. Preliminary chemical analysis shows that these nanocrystals are rich in aluminum and yttrium and poor in oxygen relative to the amorphous matrix.
Residual Stress Control by Ion Beam Assisted Deposition
Authors: Was G. S. , Jones J. W. , Parfitt L. , Kalnas C.E. , Goldiner M.
Published: April 2011

The origin of residual stresses were studied in both crystalline metallic films and amorphous oxide films made by ion beam assisted deposition (IBAD). Monolithic films of AI2O3 were deposited during bombardment by Ne, Ar or Kr over a narrow range of energies, E, and a wide range of ion-to-atom arrival rate ratios, R and were characterized in terms of composition, thickness, density, crystallinity, microstructure and residual stress. The stress was a strong function of ion beam parameters and gas content and compares to the behavior of other amorphous compounds such as MoSix and WS12.2 With increasing normalized energy (eV/atom), residual stress in crystalline metallic films (Mo, W) increases in the tensile direction before reversing and becoming compressive at high normalized energy. The origin of the stress is most likely due to densification or interstitial generation. Residual stress in amorphous films (Al2O3, MoSix and WSi2.2) is initially tensile and monotonically decreases into the compressive region with increasing normalized energy. The amorphous films also incorporate substantially more gas than crystalline films and in the case of Al2O3 are characterized by a high density of voids. Stress due to gas pressure in existing voids explains neither the functional dependence on gas content nor the magnitude of the observed stress. A more likely explanation for the behavior of stress is gas incorporation into the matrix, where the amount of incorporated gas is controlled by trapping.
Low-Energy Deposition of High-Strength AI(O) Alloys From an ECR Plasma
Authors: Barbour J.C. , Follstaedt D.M. , Knapp J.A. , Marshall D.A. , Myers S.M. , Lad R.J.
Published: April 2011

References and Acknowledgments

Low-energy deposition of AI(O) alloys from an electron cyclotron resonance (ECR) plasma offers a scaleable method for the synthesis of thick, high-strength AI layers. This work compares alloy layers formed by an ECR-O2 plasma in conjunction with AI evaporation to O-implanted AI (ion energies 25–200 keV), and it examines the effects of volume fraction of AI2O3 phase and deposition temperature on the yield stress of the material. TEM showed the AI(O) alloys contain a dense dispersion of small y-AbOa precipitates (∼1 nm) in a fine-grain (10–100 nm) fee AI matrix when deposited at a temperature of ∼100°C, similar to the microstructure for gigapascal-strength O-implanted AI. Nanoindentation gave hardnesses for ECR films from 1.1 to 3.2 GPa, and finite-element modeling gave yield stresses up to 1.3 ± 0.2 GPa with an elastic modulus of 66 GPa ± 6 GPa (similar to pure bulk AI). The yield stress of a polycrystalline pure AI layer was only 0.19+0.02 GPa, which was increased to 0.87+0.15 GPa by implantation with 5 at.% O.
Hydrogen Etching Effects During Plasma Doping Processes and Impact on Shallow Junction Formation
Authors: Qin Shu , Bernstein James D. , Chan Chung
Published: April 2011

Hydrogen etching effects in plasma ion implantation (PII) doping processes alter device structure and implant dopant profile and reduce the retained implant dose. This has particular relevance to the shallow junction devices of ultra large scale integrated circuits (ULSI). Hydrogen etching of semiconductor materials including Si, poly-Si, SiO2, Al, and photoresist films have been investigated. The effects of varying different PII process parameters are presented. The experimental data show that the spontaneous etching by hydrogen radicals enhanced by ion bombardment is responsible for the etching phenomena. A computer simulation is used to predict the as-implanted impurity profile and the retained implant dose for a shallow junction doping when the etching effect is considered.
An Apparatus for Magnetron Sputter Coating and Plasma Immersion Ion Implantation
Authors: Ensinger W. , Hartmann J. , Klein J. , Usedom P. , Stritzker B. , Rauschenbach B.
Published: April 2011

A coating apparatus which combines two material modification techniques, sputter coating and plasma immersion ion implantation, is described. The plasma is generated by an electron cyclotron resonance microwave plasma source. In the upper part of the vacuum chamber, the plasma is confined in a magnetic field by means of a solenoid. In the lower part, a magnetron sputter cathode is mounted which is used for depositing thin films on the sample. The sample is clamped onto a water-cooled sample holder which can be moved in vertical direction. It is connected to a semiconductor-based high voltage pulse generator which provides negative voltage pulses. In this apparatus, a substrate can be pre-implanted by plasma immersion ion implantation, then it can be coated by sputtering. Finally, the sputtered film can be modified by another ion implantation step.
Using Electron Cyclotron Resonance Plasma for Depositing Epitaxial Titanium Nitride Thin Films
Authors: Murzin I.H. , Hayashi N. , Sakamoto I.
Published: April 2011

We have employed a 2.45 GHz electron cyclotron resonance (ECR) plasma source to deposit single-crystal thin films of titanium nitride onto MgO substrates of (100) orientation. During deposition the ECR plasma beam delivering a mixture of excited species of molecular and atomic nitrogen ions, strikes a substrate while an electron beam deposits on the same substrate species of titanium. We have studied the formation of films at substrate temperatures of 200, 400, and 600°C, as well as at room temperature. X-Ray diffraction (XRD) revealed that a cubic Bl phase of titanium nitride forms predominantly at all the temperatures explored. Both channeling and Rutherford backscattering spectroscopy (RBS) showed epitaxial layers forming at the temperature as low as 400°C. The minimum relative backscattering yield, χmin decreased as the temperature increased, with the best result of 7.3% obtained for the film deposited at 600°C. Biasing the substrates with either negative or positive voltage at room temperature directly affects film crystallography.
Deposition of High Quality SiO2 Films Using Teos by ECR Plasma
Authors: Sano K. , Tamamaki H. , Nomura M. , Wickramanayaka S. , Nakanishi Y. , Hatanaka Y.
Published: April 2011

SiO2 thin firms were fabricated in a remote electron cyclotron resonance (ECR) plasma by tctraethoxysilane (TEOS) as the silicon source. Oxygen was used as the plasma gas. A mesh was placed between the TEOS gas outlet and the substrate. In the present investigation a-SiO2 films were deposited with and without the mesh and film properties were studied comparatively. The deposition rate increased when the mesh was attached. The optimum deposition rate is observed when the mesh voltage was zero, that is the mesh was grounded. The deposition rates of both methods were also dependnt on the TEOS flow rate, applied microwave power and the substrate temperature. These three parameters have significant roles in controlling the film quality. Good quality SiO2 films can be obtained with a higher deposition rate when a mesh is attached.
Ion Beam Assisted Deposition of Si-Diamond-Like Carbon Coatings on Large Area Substrates
Authors: Fountzoulas Costas G.
Published: April 2011

Hard, low-friction silicon-containing diamond-like carbon coatings (Si-DLC), were formed by Ar+ ion beam assisted deposition (IBAD), on 5 in. diameter silicon wafers. The diffusion pump oil precursor (tetraphenyl-tetramethyl-trisiloxane: (C6H5)4(CH3)4Si3O2) was evaporated through seven, 3 mm diameter, closely packed apertures (multinozzle/multi-aperture container) arranged in a hexagonal pattern, approximately 5 mm apart according to mathematical model [1[ developed at ARL describing the spatial distribution of film deposition from nozzles and apertures onto inclined substrates.The ion energy was kept at 40 keV whereas the ion current density and the oil evaporation temperature were varied to produce hard, lubricious and adherent films. The multinozzle array allowed the relatively uniform (± 20%) coverage of the entire 5 in. substrate. The thickness and the microhardness of the films were measured along the rectilinear surface coordinates of the substrate area. Depending on the deposition parameters the standard deviation of the coating thicknesses and Knoop micro-hardness varied from 14 to 30 percent respectively over the substrate. This is a significant improvement from the previously used single nozzle set up where the standard deviation of the coating thickness was 50 to 100 percent for 2 in. diameter substrates. The Knoop microhardness and the sliding friction coefficient of these coatings ranged from 10,000 to 20,000 MPa and 0.04 to 0.2 respectively. These values are in agreement with our previously reported single nozzle results [2].
Thin Mo Films Deposited and Analyzed Using Sub-Kev Noble Gas Ions
Authors: Der Kuur Jan Van , Melker Ernst-Jan E. , Huijgen Tom P. , Hoondert Wilbert H.B. , Bekking Gerard T.W.M. , Den Beukel Arie Van , Thijsse Barend J.
Published: April 2011

Using He+ as probe particles, we have studied point defects in Mo thin films (5-1000 Å) deposited without and with Ar+ ion beam assistance (0.2–22 eV per Mo atom). It is found that the net effect of the ion beam is to produce rather than to annihilate point defects. Ar incorporation is only slight (-10-4). Annealing of the films leads to the thermal production of polyvacancies.
Growth of Tin Oxide Film Deposited by a Hybrjd Ion Beam
Authors: Choi W.K. , Cho J.S. , Song S.K. , Jung H.-J. , Jeon J.S. , Choi D. , Koh S.K.
Published: April 2011

Tin oxide thin films were grown on Si(100) substrates by a hybrid ion beam consisting of a partially ionized beam and a cold hollow cathode ion source. Tin metal particles were ionized and accelerated by a partially ionized ion beam source while oxygen gas was introduced or ionized oxygen was introduced upon the Si substrate. When oxygen gas was blown near the substrate during Sn metal evaporation, the composition of deposited tin oxide films revealed mainly Sn metal and SnO, whereas tin dioxide films with highly preferred orientation of SnO2<200 or SnO2<110 axis were successfully grown when ionized oxygen was assisted. The calculated value of the composition ratio of oxygen to Sn(O/Sn) by AES for the SnO2(200) film was approximately 1.98. Moreover, the binding energy of Sn 3d5/2 was determined to be at 486.74 eV by XPS measurement, and the result coincided well with that of standard SnO2 powder. Compared with two different deposition processes, ionized oxygen assistance during tin metal evaporation would be considered to effectively improve oxygen content for the formation of tin dioxide thin films.
Design of a Compact Negative Metal Ion Beam Source for Surface Studies
Authors: Park Y. , Ko Y.W. , Sohn M.H. , Kim S.I.
Published: April 2011

A compact negative metal ion beam source for direct low energy metal ion beam depositions studies in ultra high vacuum (UHV) environment, has been developed. The ion source is based on SKION's Solid State Ion Beam Technology. The secondary negative metal ion beam is effectively produced by primary cesium positive ion bombardment (negative ion yield varies from 0.1-0.5 for carbon). The beam diameter is in the range of 0.2∼3.0 cm depending on the focusing and ion beam energy. The ion source produces negative ion currents of about 0.8 mA/cm2. The energy spread of the ion beam is less then ±5% of the ion beam energy. The energy of negative metal ion beam can be independently controlled in the range of 10-300 eV. Due to the complete solid state ion technology , the source can be operated while maintaining chamber pressures of less then 10-10 Torr.
New Instrumentation in Argonne's Hvem-Tandem Facility: Expanded Capability for in Situ Ion Beam Studies+
Authors: Allen Charles W. , Funk Loren L. , Ryan Edward A.
Published: April 2011

During 1995, a state-of-the-art intermediate voltage electron microscope (IVEM) has been installed in the HVEM-Tandem Facility with in situ ion irradiation capabilities similar to those of the HVEM. A 300 kV Hitachi H-9000NAR has been interfaced to the two ion accelerators of the Facility, with a spatial resolution for imaging which is nearly an order of magnitude better than that for the 1.2 MV HVEM which dates from the early 1970s. The HVEM remains heavily utilized for electron- and ion irradiation-related materials studies, nevertheless, especially those for which less demanding microscopy is adequate. The capabilities and limitations of this IVEM and HVEM are compared. Both the HVEM and IVEM are part of the DOE funded User Facility and therefore are available to the scientific community for materials studies, free of charge for non-proprietary research.
Focused Ion Beam Metrology
Authors: Wagner A. , Blauner P. , Longo P. , Cohen S.
Published: April 2011

Focused Ion Beams offer a new method of measuring the size of polymer resist features on integrated circuits. The short penetration range of an ion relative to an electron is shown to offer fundamental advantages for critical dimension (CD) metrology. By confining the polymer damage to the very near surface, ion beams can induce less dimensional change than scanning electron microscopes during the measurement process. This can result in improved CD measurement precision. The erosion rate of polymers to various ion species is also presented, and we show that erosion is non-linear with ion dose. The use of FIB for forming resist cross sections is also demonstrated. An H20 gas assisted etching process for polymers has been developed, and is shown to significantly improve the quality of resist cross sections.