bluuebunny/crossref_metadata_2025_split huggingface dataset:
Erbium Doped Semiconductor Thin Films Prepared by Rf Magnetron Sputtering
Authors: Kim Hong Koo , Li Cheng Chung , Fang Xiao Ming , Solomon James , Nykolak Gerald , Becker Philippe C. 
Published: March 2011

ABSTRACTHighly Er-doped (∼ 1020 atoms/cm3) silicon and silica films were deposited by RF magnetron sputtering. Erbium was doped into the host material by co-sputtering technique. Deposited films (0.5 - 1.2 µm thick) were characterized by photoluminescence (PL), secondary ion mass spectroscopy (SIMS), and fluorescence decay measurements. Er-doped silica glass films show a strong, room-temperature luminescence at 1.54 µm wavelength. In contrast, Er-doped silicon films show a weak luminescence at room temperature. However, a big enhancement in the Er3+ luminescence was observed after a proper annealing, for example, 900 °C for 30 to 120 min in air ambient, resulting in the luminescence intensities comparable with that of the Er-doped silica films. This enhancement is attributed to the oxygen incorporation into the Si host film during the annealing, thus forming an Er-doped oxide layer on top of the film. The result suggests that Er-O bonding plays important role in forming optically active erbium ions. Erdoped, three-component silicate glass (SiO2 + A12O3 + MgO) films were also sputter deposited to investigate the dependence of Er3+ luminescence on the host material's composition. Even stronger luminescence was observed from the Er-doped, three component silicate glass films compared with the Er-doped SiO2 films.
Er3+-Doped Silicon Prepared by Laser Doping
Authors: Asatsuma T. , Dodd P. , Donegan J. F. , Lunney J. G. , Hegarty J. 
Published: March 2011

ABSTRACTWe have carried out an investigation of the laser doping of Si with rare-earth ions. In this technique a silicon surface coated with a thin layer of the rare-earth metal is melted with a pulsed laser, the dopant is mixed in the molten layer, and incorporated in the crystal during regrowth. Er was chosen for the main part of our work as it is the best characterized of the rare-earth ions in Si. Luminescence is observed around 1.54µm and is assigned to optical transitions on Er3+ ions. This preliminary study shows that this new technique is viable for the production of optically active Er3+ in Si.
Ic Compatible Processing of Si:Er for optoelectronics
Authors: Ren F. Y. G. , Michel J. , Sun-Paduano Q. , Zheng B. , Kitagawa H. , Jacobson D.C. , Poate J.M. , Kimerling L. C. 
Published: March 2011

ABSTRACTWe have fabricated the first Si:Er LED, operating at 300 K, based on an understanding of the Si-Er-O materials system. Er-doped Si (Si:Er) provides an exciting opportunity for the monolithic integration of Si based opto-electronics. In this paper, Er-Si reactivity, and Er diffusivity and solubility have been studied to establish Si:Er process compatibility with a silicon IC fabline. Er3 Si5 is the most stable silicid formed; and it can be oxidized into Er2O3 at high temperature under any oxidizing conditions. Among Er compounds, Er2O3 luminesces and Er3Si5 and ErN do not. The diffusivity of Er in Si is low and SIMS analysis yields a diffusivity D(Er) ∼ 10−12cm2/s at 1300 C and ∼ 10−15cm2/s at 900 C, and a migration enthalpy of δHm(Er) ∼ 4.6 eV. The equilibrium solubility of Er in Si is in the range of 1016 cm−3 at 1300 C. The Si:Er LED performance is compared with GaAs LEDs to demonstrate its feasibility.
Characterization of Two Electromigration Failure Modes In Submicron Vlsi
Authors: Atakov Em , Clement JJ. , Miner B. 
Published: March 2011

AbstractGrain-bondary erosion-type voids and transgranular slit-like voids are found to be two competing electromigration failure modes in VLSI interconnects. The effects of interconnect linewidth, microstructure, process variables and stress conditions on the two failure modes were studied.
Reliability Study of TiN/AlCu/TiN Interconnect in Submicron Cmos Process
Authors: Kuo Arthur T. , Choudhury Ratan , Hata William 
Published: March 2011

AbstractIn this paper, the effect of thin film deposition conditions on the multilayer interconnect reliability was studied. Experimental results indicated the most reliable TiN/AICu/TiN interconnect was obtained at the deposition temperature of 350 °C without any substrate bias. This observation was in close agreement with thin film characteristics such as resistivity, grain size and intermetallic formation seen for those deposition conditions. SEM pictures showed the anti-reflective coating (ARC) TiN film did successfully suppress inter-plane extrusion during electromigration test. The failure mechanism for electromigration was also revealed to be mass transport as the result of the grain boundary diffusion instead of catastrophic open failures. The stress migration studies found that TiN/AICu/TiN had superior stress migration resistance than AICu alone.
Effect of TiW As Adhesion Layer And Underlying Metal On Electromigration Characteristics of Tungsten Via Plugs
Authors: Gadepally Kamesh , Reddy Padala Krishna , Niew Siew , Merrill Richard , Lahri Rajeeva , Biswal Madan 
Published: March 2011

AbstractThe use of Tungsten plug technology to obtain good step coverage in vias and contacts is a well know fact. The effect of TiW as an adhesion layer between the plug and the overlying Aluminum is shown in this paper to have a significant impact on the electromigration characteristics of this scheme. A comparison between plug and non-plug technology is also made keeping the aspect ratios the same. Also discussed in this paper will be the effect of the first metal (Tungsten vs Aluminum) on electromigration characteristics. Constant current DC electromigration stressing was performed on via chains and the results are discussed. Discussed, also, are SEM cross sections (XSEM) of the stressed vias indicating the failure modes. An idealized metal scheme will be presented and discussed.
Stress Gradient and Relaxation Measurements in Al and Oxygen-Implanted al Films.
Authors: Besser Paul R. , Bader Stefan , Venkatraman Ramnath , Bravman John C. 
Published: March 2011

AbstractSynchrotron radiation has been used in the grazing incidence geometry to determine the stress gradients and stress relaxation in 0.6 μm thick Al uniform films. We have examined both pure Al and Al implanted with 3 at% oxygen. The films were cycled between 23°C and 400°C. The surface of the pure Al films was more highly stressed, on average, than the film as a whole, both in tension and in compression. In contrast, the surface of the oxygen-implanted film was relaxed relative to the average film stress in compression but was more stressed in tension. The larger gradient in stress in the implanted films reduces during subsequent thermal cycling. These differences are attributed to the microstructures of the films. The 0-implanted film develops a small, non-columnar grain structure and forms small AI2O3 particles during annealing. The small grain size allows diffusional relaxation to occur in compression, relieving the stress in areas close to the film surface.
Stress in Copper thin Films With Barrier Layers
Authors: Vinci Richard P. , Bravman John C. 
Published: March 2011

AbstractWafer curvature and grazing incidence x-ray scattering (GIXS) techniques were used to investigate the biaxial stresses induced in blanket Cu films during a thermal cycle to 460°C and back to room temperature. Cu was deposited by DC sputtering at ambient temperature. Several different barrier layer materials — SiO2, W, Ta, TiN, and Si3N4 — were used to compare any effect barrier choice might have on Cu microstructure evolution and mechanical behavior. Ta and Si3N4 encouraged a strong (111) Cu texture. A W barrier led to an untextured microstructure which underwent large, uneven grain growth during thermal cycling. Several samples were capped with a Ta layer which affected the stress behavior during cooling by inhibiting dislocation motion. An inverse relationship between strength and thickness was also documented.
Stress Mapping Near Simulated Defects in Thin Film Wiring Using X-ray Microbeam Diffraction
Authors: Dehaven Patrick , Goldsmith Charles 
Published: March 2011

AbstractThe stress distribution about a series of deliberately fabricated defects in a Cu/Ni/Au/Cr redundant metal stack deposited on a Cr/Cu/Cr serpentine has been studied via x-ray microbeam diffraction using the sin2 ψ, technique. Strong directional anisotropies in the stress were found for both the second level nickel and copper. The extent of nickel stress relaxation from the edge of a defect far exceeded that predicted by a simple metal on substrate model. The size of the defect did not appear to significantly influence the stress distribution in the second level metal; however, the data suggest that the linewidth may influence the magnitude of the stress along the length of a line when near a defect or other sharp discontinuity.
X-ray Determination and Finite-Element Modeling of Stress in Passivated Al-0.5%Cu Lines During Thermal Cycling.
Authors: Besser Paul R. , Mack Anne Sauter , Fraser David , Bravman John C. 
Published: March 2011

AbstractWe have measured the principal strain state of AI-0.5%Cu lines passivated with silicon nitride directly and used it to calculate the stress state. The stress was determined as the lines were thermally cycled from room temperature to 450°C. The general stress-temperature behavior shows good fundamental agreement with that calculated using finite-element methods, although the magnitude of the stresses measured with x-rays is less than that predicted by modeling due to stressinduced voiding in the lines. This is shown with a high voltage scanning transmission electron microscope (STEM) operated in the backscattering mode.
Electromigration Induced Resistance Changes in Passivated Aluminum Thin Film Conductors
Authors: Möckl U.E. , Lloyd J.R. , Arzt E. 
Published: March 2011

AbstractThe relative change in resistance due to electromigration was studied in thin (0.7 μm) film conductors of AI-0.5% Cu Alloy passivated with a 1 μm thick glass passivation using a sensitive AC bridge technique. In contrast to previous experiments performed on unpassivated structures where a roughly linear resistance increase was observed, a saturation value for the resistance increase was observed which was seen to be a function of temperature and the applied current density. The results were found to be consistent with a Shatzkes and Lloyd electromigration model.
Effect of Line Width on Electromigration of Textured Pure Aluminum Films
Authors: Knorr D.B. , Rodbell K.P. 
Published: March 2011

AbstractThree conditions of pure aluminum films were deposited, patterned into electromigration test structures, and annealed at 400°C for I hour. The grain size distribution was essentially the same for all conditions, but the textures were substantially different. Electromigration failure distributions were developed at 225°C and 1 MA/cm2for line widths of both 1.8 μm and 0.5 μm. Three conditions were tested at the wider line width while the strongest and weakest textures were evaluated in the narrow line width. Texture exerts a dominant effect at the wider line width where the lines are polycrystalline. The values of t50increase as texture becomes stronger although σ varies from <0.5 for strong textures to >1 for a bimodal failure distribution in the weakest texture. In the narrow lines, the texture effect is substantially reduced, and the failure distributions are bimodal with a few early fails followed by a monomodal distribution characterized by a low cr. The electromigration behavior is discussed in terms of both texture and the line width to grain size ratio.
Characterization of Oxides and Thin Films
Authors: Baikie Iain D. , Bruggink Gerrit H. 
Published: March 2011

AbstractUsing a new, high resolution, microscopic Scanning Kelvin Probe (SKP), work function topographies of metal, semiconductor and metal/semionductor surfaces have been studied in both Ultra-High-Vacuum (UHV) and air environments.The work function is a very sensitive indicator of surface and Interface condition and has been previously utilized to examine preparation methods, surface roughness, adsorption processes, thin film monitoring and residual surface contamination.Extension of the basic method, via Illumination of the semiconductor surface under the tip allows one to probe the local density of states (LDOS). Variations in LDOS can be used to monitor metal contamination, interface traps, bulk contamination, oxide imperfections, etc.Work function topographies generated in this fashion have application in quality control at all stages of the manufacturing process. The Kelvin method of measuring work function is non-contact and non-destructive, utilizing neither high fields nor large currents. It can be applied to a variety of environments ranging from UHV to air and at a wide range of temperatures.
The Effect of Cu Alloying on Al Alloy Thin Films: Microstructural Mechanisms That Enhance Electromigration Resistance
Authors: Frear D. R. , Michael J. R. , Romig A. D. 
Published: March 2011

AbstractThe microstructural evolution of unpatterned Al-2wt.%Cu thin films has been examined to elucidate the mechanism by which copper improves electromigration resistance. After annealing at 425°C and cooling to room temperature at a rate of approximately 1°C/min., the microstructure of the Al-Cu films consisted of 1 μm aluminum grains with θ-phase Al2Cu precipitates at grain boundaries and triple points. The grain size and precipitation distribution did not change with subsequent isothermal heat treatments in the temperature range of 200° to 400°C. Al-Cu thin films annealed at 400°C, a temperature just below the Al/Al+θ solvus, exhibited microstructures in which the aluminum grain boundaries were depleted in copper except for the presence of the pre-existing large, widely dispersed AI2Cu precipitates. Al-Cu thin films annealed at 200° to 300°C were enriched with copper at the aluminum grain boundaries. The large, widely dispersed Al2Cu precipitates remained after the lower temperature anneals. From these results, it is proposed that the presence of copper in aluminum thin films improves electromigration resistance due to the precipitation of a thin film of Al2Cu, or a substoichiometric precursor, along the grain boundaries. The grain boundary phase retards grain boundary diffusion in the thin films, thereby reducing total mass transport and improving electromigration resistance.
Microstructure, Damage and Resistance during Electromigration Life-Testing of Al-Cu Interconnects
Authors: Shih W.C. , Greer A.L. , Xu Y.Z. , Jones B.K. 
Published: March 2011

AbstractUnpassivated 1.4 mm long lines of Al-4wt.%Cu metallization have been successively imaged (by scanning electron microscopy) and electromigration stressed until failure. The resistance of lines, evolution of line microstructure and the development of electromigration damage are thus discontinuously recorded through the accelerated life-testing (260°C, 2 × 1010 A m-2). Correlations are made among microstructure evolution, electromigration damage development and line resistance. The probable mechanisms of damage development are discussed.
IN-SITU Analysis Of The Microstructure of Thermally Treated Thin Copper Films
Authors: Nucci J. , Neves H. , Shacham Y. , Eisenbraun E. , Zheng B. , Kaloyeros A. 
Published: March 2011

AbstractCopper thin films were deposited by sputtering, electron beam evaporation, and electroless plating onto nitride membranes for TEM analysis. The samples were heat treated in-situ from room temperature to 600 °C for structural and chemical analysis. The as-deposited and heat treated microstructures were investigated. Orientation changes with heat treatment and reactions among the sample layers were analyzed by electron diffraction. This work provides baseline information for a study of the thermal evolution of copper lines.
The Effect of Thermal History On Interconnect Reliability
Authors: Thompson C.V. 
Published: March 2011

AbstractThe reliability of interconnects is strongly affected by their thermal history, including the deposition temperature, the temperature at which patterned films are passivated, and the temperature and cooling rates of the final packaging processes. The thermal history affects the stress, the grain structure, and the distribution of alloy additions, such as Cu. All of these affect the reliability of interconnects, especially as it is limited by electromigration. The postpatterning thermal history is especially important. For example, it is post-patterning annealing which leads to the evolution of electromigration resistant bamboo-microstructures. In Al-Cu alloy interconnects, pre- and post-patterning anneals can also affect the distribution of Cu in solution and in precipitates. This too can affect interconnect reliability. Experiments and modeling concerned with these effects of thermal history will be reviewed and discussed.
Grain Growth in Al-(Cu, Pd, Nb) Thin Films
Authors: Mis J.D. , Rodbell K.P. 
Published: March 2011

AbstractThe microstructure of 1 μim thick Al films containing 0.5 and 2%Cu (weight percent), 0.3%Pd, and 0.3%Pd-0.3%Nb were investigated by transmission electron microscopy (TEM) and energy dispersive x-ray spectroscopy (EDS) as a function of isochronal and isothermal anneals. The grain size, grain size distribution, and precipitate morphology of these films was measured from 200 to 500ºC, with the activation energy for grain growth (Ea) determined for I h anneals at 200, 300, 400 and 500ºC. Normal grain growth was recorded for the A1Cu films annealed at temperatures ≤400ºC; however secondary grain growth occurred in the AI-2Cu film annealed for I h at 500ºC, with grains as large as 16 μm in diameter observed. Grain growth in the AI-0.3Pd films resulted in strongly bi-modal grain size distributions, with the onset ofsignificant grain growth retarded for I h anneals at temperatures ≤300ºC.The addition of Nb to the AI-0.3Pd film resulted in monomodal grain size distributions over the entire temperature range. The role of crystallographic texture on grain growth in thin films is discussed.
The Effect of Annealing on the Cu Distribution and AI2Cu Precipitation in Ai(Cu) Thin Films
Authors: Colgan E.G. , Rodbell K.P. , Vigliotti D.R. 
Published: March 2011

AbstractThe Cu distribution in AI(Cu) thin films has been examined in blanket and patterned samples as a function of annealing. The Cu concentration in the Al grains, measured at room temperature, closely follows the solubility at the anneal temperature when a high cooling rate is used (-100 or -200°C/min) from the annealing temperature. With fine lines, the room temperature Cu concentration follows the solubility at the anneal temperature only at low anneal temperatures, ≤350°C. With higher temperatureannealing, >400°C, the room temperature Cu concentration in the Al grains was substantially less than the solubility at the anneal temperature. These differences are attributed to the smaller grain size in fine lines, which reduces the distance to grain boundaries. With blanket films, the Θ-phase (Al2Cu) precipitate morphology depends on the Al grain size and annealing temperature. With small Al grains (100-300 nm), the Θ particles are small (100-200 nm) and round whereas with large Al grains (0.5-2μm), the precipitates are long and irregularly shaped. The morphology of the Θ precipitates is constrained by the Al grain size. With fine lines, having a bamboo structure, the Θ precipitates are “wedge” shaped along grain boundaries or span the width of the line. The electromigration lifetime was found to depend strongly on the heat treatment used, an increase of 3X in lifetime was obtained for samples rapidly cooled from a temperature above the solvus curve as compared with samples subjected to additional aging at low temperatures. This is believed to be dueto the different concentrations of Cu in solution and to the size and distribution of Θparticles in the patterned lines.
Corrosion and Protection of Thin Metallic Films
Authors: Brusic V. , Frankel G. S. 
Published: March 2011

AbstractWell known principles governing metallic corrosion are summarized in this paper. Severalelectrochemical techniques that are suitable for evaluation of corrosion reactions and mechanisms are discussed. The challenge of minimizing metallic degradation in processing, in storage and during operation is discussed with examples drawn from thin films used inthe electronics industry.
A Spectromicroscopic Study of Corrosion in AI-Cu-Si Metallization
Authors: Liang S. , Ray-Chaudhuri A.K. , Ng W. , Singh S. , Welnak J.T. , Cerrina F. 
Published: March 2011

AbstractSoft X-ray photoelectron spectromicroscopy has been employed to examine the microstructural chemistry of corrosion on thin films of AL-i%Cu-1%Si alloy. Cu-rich precipitates are formed after the film is annealed at around 320ºC Localized corrosion takes place around these precipitates, and circular microstructures have been observed. Energy distribution curves (EDCs) taken at specific points are analyzed and photoelectron images were obtained from different kinetic energies corresponding to the peaks in EDC. It was found that after corrosion the Al2Cu particles are revealed and distributed at the center of the corrosion structure with oxide as matrix, while the oxides form a ring-like band outside.
Agglomeration-Free Nanoscale Cobalt Silicide Film Formation Via Substrate Preamorphization
Authors: Pramanick S. , Patnaik B.K. , Rozgonyi G. A. 
Published: March 2011

AbstractWe have used preamorphization of silicon substrates as a process modification to suppress agglomeration during cobalt disilicide film formation. Planar, continuous and low resistivity (<21 μΩ-cm) silicide films less than 35 nm thick have been produced both on single crystal silicon and polysilicon. Nanoscale(<35 nm) silicide films are more susceptible to islanding phenomena since agglomeration is dependent onthe ratio of grain size to film thickness. Preamorphization prior to silicidation favorsa large increase in silicide nucleation rate, as well as reduction in critical nuclei size, both of which aid the formation of silicide with small grains. The resulting small grain silicides enable nanoscale films to remain below the critical grain size to thickness ratio for which thin films become morphologically unstable. An interphase void band which occurs between CoSi and CoSi2 layers, acts as a convenient diffusion marker and aids interpretation of the complex stability issues. Preamorphization prior to silicidation was also extended to heavily doped substrates to study the applicability of this approach for junctions and gate contacts. Silicidation of amorphized heavily boron doped substrates produces non uniform layers due to the collision of the advancing silicidation and SPE interfaces. A comparision of concurrent processing, i.e. simulatneous dopant activation and silicide formation, with conventional silicidation of Si+ preamorphized heavily doped(B) substrates is also presented.
Defects In GaAs Bulk Crystals and Multi-Layers Caused by In Diffusion
Authors: Werner P. , Liliental-Weber Z. , Swider W. , Sohn H. , Yau WaiFan , Baranowski J. , Weber E.R. 
Published: March 2011

AbstractThe objective of this work was to study by transmission electron microscopy the lattice defects in GaAs bulk crystals and heterostructures formed by In diffusion. In such samples hints for the existence of superconductivity have been found. Indium was found to move more than 100 μm into bulk GaAs during lh annealing at 550ºC (such conditions are typical for molecular beam epitaxy growth on GaAs wafers). This rapid diffusion is accompanied by the creation of dislocation networks and metallic In droplets that show evidence for lattice strain. To study the interaction of In with the GaAs lattice, In/GaAs multi-layers were grown by MBE at about 450ºC on a GaAs buffer layer. The interfaces of these structures showed misfit dislocations at islands of InAs besides the presence of lattice strain. Both types of samples showed microwave absorption signals typical for superconductivity. The most likely superconductive phases are small metastable inclusions, probably consisting of amorphous Ga or In.