bluuebunny/crossref_metadata_2025_split huggingface dataset:
Rare-Earth Doping by Ion Implantation and Related Techniques
Authors: Brown Ian G. 
Published: March 2011

ABSTRACTSome metal plasma techniques have been developed that provide a convenient means for the doping of semiconductor hosts with rare-earths. These plasma and ion beam tools are based on the application of vacuum arc discharges for the formation of dense rare-earth plasmas which then can be used in a number of ways for doping and otherwise introducing the rare-earths into substrate materials. At the low energy end of the spectrum, the streaming metal plasma can be used for the deposition of thin films, and if more than one plasma source is used then of multilayer structures also. Or by building the vacuum-arc rare-earth plasma generator into an ion source configuration, high current ion beams can be produced for doing high energy ion implantation; alternatively the substrate can be immersed in the streaming rare-earth plasma and by using appropriately phased high voltage substrate pulsing and pulsed plasma generation, plasma immersion ion implantation can be done. Between these two limiting techniques – low energy plasma deposition and high energy ion implantation – a spectrum of hybrid methods can be utilized for rare earth doping. We've made a number of plasma and ion sources of this kind, and we've doped a wide range of substrates with a wide range of rare-earths. For example we've implanted species including Sc, Y, La, Ce, Pr, Nd, Sm, Gd, Dy, Ho, Er and Yb into host materials including Si, GaAs, InP and more. The implantation dose can range from a low of about 1013 cm−2 up to as high as about 1017 cm−2, and the ion energy can be varied from a few tens of eV up to about 200 keV. Here we review these vacuum-arc-based plasma methods for rare-earth doping, describing both the tools and techniques that are available and the applications to which we've put the methods in our laboratory.
Er-Doping in Silicon by Pulsed Laser Irradiation
Authors: Nakashima Kenshiro 
Published: March 2011

ABSTRACTErbium ions were successfully doped in silicon by pulsed laser irradiation above the threshold laser energy density. Photoluminescence peaks at 1.54, 1.59 and 1.64 µm from Er-optical centers were observed after annealing of Er-doped samples. The intensity of the 1.54 µm Er-emission band increased upon increase in the laser energy density, and then gradually decreased after reaching the maximum, due to the laser sputtering of the silicon substrate. Oxygen atoms, which were unintentionally codoped with Er-ions, were found to be distributed in the same region as in Er-ions, and were suggested to play roles to activate Er-optical centers. The maximum concentration of Er-ions doped in the solid state regime were estimated to be the order of 1018 cm−3 by the Rutherford backscattering measurements.
Oxygen-Enhanced 1.54µm Photoluminescence of Er+3 In Silicon
Authors: D'avitaya F. Arnaud , Campidelli Y. , Chroboczek J.A. , Favennec P.N. , L'haridon H. , Moutonnet D. , Wasiela A. 
Published: March 2011

ABSTRACTFavennec et al. (Jap. J. Appl. Phys. 29, L524, 1990) reported that the 1.54µm photoluminescence of Si implanted with Er+3 is activated by oxygen impurities. We observe a significant enhancement in the luminescence in Er-doped silicon epitaxial layers MBE-grown with intentional oxygen contamination. The PL is shown to be a bulk property of the material as it persisted after a partial layer removal by wet etching.
Modelling Electromigration and Induced Stresses In Aluminum Lines
Authors: Kirchheim R. 
Published: March 2011

AbstractThe various equations used by different authors for describing electromigration are compiled. All of them can be derived from a general equation which is based on a vacancy model. During the derivation of simplified versions of the general equations assumptions have to be made and their effect on concentration profiles and/or electromigration stresses developing as a function of time are discussed. Consequences with respect to Blech's experiment or the current exponent in Black's equation are taken into consideration and a simple explanation is provided for the beneficial effect of a (111) texture on the reliability of Al-lines.
Electromigration Damage in Fine Al Alloy Lines due To Interfacial Diffusion
Authors: Hu C-K. , Small M.B. , Rodbell K.P. , Stanis C. , Mazzeo N. , Blauner P. , Rosenberg R. , Ho P.S. 
Published: March 2011

AbstractBoth electromigration lifetime experiments and experiments of the drift velocity type have been conducted with the alloys: Al(2% Cu), Al(O.5% Cu,O.3% Zr), and Al(0.3% Pd,O.3% Nb) also with structures with two wiring levels of Ti/Al(0.5 - 4 % Cu)/Ti interconnected with W studs. The latter structure and these structures in general, are representative of present applications, which contain Al alloy/W interfaces. In all cases it was found that the mass transport along the line's edges played a role in their damage formation, which was at least as great as grain boundary diffusion. It is postulated that the results obtained using the traditional test structure, which has reservoirs of metal alloy at each electrode and is conducted at a single level, have been misinterpreted as indicating that flux divergence at triple junctions were critical failure sites for on-chip interconnections. These present results show that the material in the electrode pads of the conventional structure can resupply material to the lines. A direct experimental comparison of the two structural types is made to demonstrate the point.
The Effect of Thermally Induced Stresses on Electromigration Lifetime Of Near-Bamboo Interconnects
Authors: Korhonen M.A. , BØrgesen P. , Brown D.D. , Li Che-Yu 
Published: March 2011

AbstractThermal stresses may affect significantly electromigration induced open failures in nearbamboo interconnect structures ending in W-vias. Based on a physical model, we investigate the thermal stress effects on void nucleation, on early failures due to grain boundary diffusion, and on longer term bulk diffusion dominated failures. It is shown that thermal stress is all important as far as early failures are concerned. In particular, during accelerated tests and service, the early failures, when occur, arise due to stress and current directed grain boundary diffusion along grain clusters. In the accelerated test, bulk diffusion dominated void growth at vias determines the long term failures while during service bulk diffusion contribution is usually negligibly small within time frames of practical interest. Because the dominant failure mechanisms change, the extrapolation from the accelerated tests to the service conditions is not straight-forward.
Microstructural Mechanism of Electromigration Failure In Narrow Interconnects
Authors: Kim Choongun , Selister S. I. , Morris J. W. 
Published: March 2011

AbstractMicrostructural studies of electromigration failure were performed on A1-2Cu-1Si interconnects with 1.3 μm width. The lines were tested to failure under controlled conditions after pre-aging for various times at three different temperatures. Examination of the microstructure of the failure sites suggests that the lines fail at the bamboo grains that terminate the longest polygranular segments in the line. Transgranular slit voids form after Cu has been swept from the grain that fails. Hence, pre-aging lines to create a more stable distribution of Cu lengthens the time required to sweep Cu and significantly increases the time to failure. The optimal microstructure has a maximum intragranular density of stable θ precipitates. In this case transgranular slit failure is suppressed, and the bamboo grain fails by diffuse thinning to rupture.
Evidence of The Electromigration Short-Length Effect in Aluminum-Based Metallurgy With Tungsten Diffusion Barriers
Authors: Filippi Ronald G. , Biery Glenn A. , Wood Michael H. 
Published: March 2011

AbstractSeveral phenomena related to the short-length effect were observed during lifetime measurements of a two-level structure consisting of Ti-AICu-Ti stripes connected by interlevel tungsten (W) stud-vias. A linear increase in resistance was followed by a resistance change with time that approached zero. The threshold product is not a constant at 250 °C for stripe lengths of 30, 50 and 100 μm. The sigma of the lognormal distribution increased as the current density decreased and/or as the fail criterion increased. The lifetime, or t50, at relatively small current densities did not obey Black's empirical equation. Rather, the lifetime data obeyed a modified version of this equation that includes a critical current density, jc, as a new parameter. This critical current density is strongly dependent on the fail criterion, but is independent of temperature in the range 210-250 °C.
On the Interface Properties and Deep Level Defects in Ta2O5 Grown on Si by Plasma Enhanced Liquid Source-Cvd
Authors: Murawala P.A. , Sawai N. , Tatsuta T. , Tsuji O. , Fujita Sz. , Fujita Sg. 
Published: March 2011

AbstractWe report, for the first time, on interface properties of the Ta2O5-Si system and on the deep level defects in Ta2O5 grown by plasma enhanced liquid source chemical vapor deposition (PE-LS-CVD) using Ta(OC2Hs)5. The capacitance voltage (C–V) measurement performed on Au/Ta2O5/n, p-Si MOS diodes resulted in very well defined C-V charactristics which compares well with the ideal C-V curve. The flat band voltage is as low as 0.15 V and the minimum density of the interface state is about 2.7 × 1011 cm−2 ev−1. In order to examine deep level defects in Ta2O5, we investigated variations of flat band voltage under application of high stress electric field (10MV/cm), by which hot carriers are injected in to deep levels. This charge transfer process results in increase of charges in Ta2O5 oxide which is attributed to the equivalent deep level defect densities, which is found to be of the order of 2 × 1011 cm−2 in the Ta2O5-Si system. These results strongly suggest low interface states and deep levels in the PE-LS-CVD grown Ta2O5-Si system, which may be brought about by low decomposed-carbon impurities in the film, confirmed by AES in our previous reports. These films can play a vital role as thin capacitors in I.C. technology.
Stress-Induced Voiding Vs Temperature and Passivation Thickness IN AI-0.5%Cu-2%Si, AI-0.5%Cu AND Al-i%Si
Authors: Sullivan T. D. , Miller L. A. 
Published: March 2011

AbstractStress-induced voiding in microelectronics chips has been reported to exhibit a variety of dependencies on temperature and on passivation stress. The dependence of line failure is reported here at four different temperatures (150, 225, 285, and 315 °C) for AI-0.5%Cu-2%Si, AI-0.5%Cu and AI-1%Si lines with passivation thicknesses (silicon oxide or silicon nitride) ranging from 0.1 to 2.5 times the metal thickness. Failure distributions change in a complex manner with changing passivation thickness, and with temperature for a specific passivation thickness, raising questions on the validity of using the conventional median time to failure (t50) and lognormal slope (σ) to project field failure rates from data generated by accelerated life testing.
Strain Relaxation and In-Situ Observation of Voiding in Passivated Aluminum alloy Lines
Authors: Besser Paul R. , Marieb Thomas N. , Bravman John C. 
Published: March 2011

AbstractStrain relaxation in passivated Al-0.5% Cu lines was measured using X-ray diffraction coupled with in-situ observation of the formation and growth of stress induced voids. Samples of 1 μm thick Al-0.5% Cu lines passivated with Si3N4 were heated to 380°C, then cooled and held at 150°C. During the test, principal strains along the length, width, and height of the line were determined using a grazing incidence x-ray geometry. From these measurements the hydrostatic strain in the metal was calculated and strain relaxation was observed. The thermal cycle was duplicated in a high voltage scanning transmission electron microscope equipped with a backscattered electron detector. The 1.25 μm wide lines were seen to have initial stress voids. Upon heating these voids reduced in size until no longer observable. Once the samples were cooled to 150°C, voids reappeared and grew. The measured strain relaxation is discussed in terms of void and θ-phase (Al2Cu) formation.
Mechanical Stress Effects on Electromigration Voiding in a Meandering Test Stripe
Authors: Lowry Lynn E. , Tai Beverly H. , Mattila J. , Walsh LH. 
Published: March 2011

AbstractEarlier experimental findings concluded that electromigration voids in these meandering stripe test structures were not randomly distributed and that void nucleation frequently occurred sub-surface at the metal/thermal oxide interface. The data showed a strong correlation between void area, void growth rate and stripe segment length [1]. The influence of mechanical stress on electromigration damage in these test structures has been examined by applying tensile stresses to both passivated and unpassivated samples. The stress distributions are calculated using finite element analysis for each of the test conditions. The resulting impact on electrornigration voiding, as well as mechanical stress voiding, and lateral hillock formation is discussed.
A Calorimetric Evaluation of Peel Adhesion
Authors: Farris Richard. J. , Goldfarb Jay. L. 
Published: March 2011

AbstractPeeling of flexible poly(ethylene terephthalate), PET, and elastic steel films, adhesively bonded with a pressure sensitive adhesive layer, was analyzed from a thermodynamic perspective with the intent of determining how the energy expended in separating the bonded materials is consumed. The mechanical work expended and the heat dissipated during peeling were simultaneously measured using deformation calorimetry. For the PET backing material, which has a demonstrated capacity to store deformation energy as latent internal energy, most, but not all, of the peel energy was dissipated as heat. When perfectly elastic steel films were peeled, all of the peel energy was dissipated as heat, proving that no latent internal energy is stored in the adhesive layer during peeling and suggesting that the internal energy change of peeling adhesive backed with PET film was stored as latent internal energy in the PET backing. The stored latent internal energy in the peeled PET was measured using solution calorimetry. The thermodynamics of tensile drawing for PET was studied using deformation calorimetry, solution calorimetry, differential scanning calorimetry and thermomechanical analysis.
Non-Destructive Evaluation of Strains and Voiding in Passivated copper Metallizations
Authors: Vinci Richard P. , Marieb Thomas N. , Bravman John C. 
Published: March 2011

AbstractStress induced voiding in passivated Cu lines was investigated by x-ray strain analysis and in-situ high voltage scanning electron microscope (HVSEM) techniques. Cu lines on a Ta underlayer and Cu lines on an Al underlayer were patterned by a trilayer liftoff technique and passivated with Si3N4. For direct observation of stress voiding, specimens were heated to 350°C in the HVSEM and then cooled and held at 150°C. Identical samples were subjected to the same thermal cycle for strain state determination using x-ray techniques. The hydrostatic stress state at each temperature was calculated from the measured strains. Few initial voids were observed after passivation in either sample. After heating to 350°C and cooling to the dwell temperature, no new voiding was seen in the Ta/Cu lines. Measured hydrostatic strains were half those measured in the Al/Cu lines. Heavy voiding was observed in the Al/Cu lines after cooling to the dwell temperature.
Grain Boundary Sliding in Thin Substrate-Bonded al Films
Authors: Prieler M. , Bohn H.G. , Schilling W. , Trinkaus H. 
Published: March 2011

AbstractA systematic investigation of the anelastic relaxation of thin Al films on Si substrates has been carried out. It was found that both the relaxation in bulk and thin film material can be explained by a model involving glide of grain boundaries (GBs). The mass transport necessary for the glide occurs via GB diffusion in the thin films and via lattice diffusion in the bulk material the different behavior being due to the more of two orders of magnitude smaller grains in the films. Internal friction thus provides a technique to measure diffusional parameters of GB diffusion in thin films.
Dispersion Strengthening of Al Films by Oxygen Ion Implantation
Authors: Bader S. , Flinn P.A. , Arzt E. , Nix W.D. 
Published: March 2011

AbstractFinely dispersed, stable Al-oxide particles were produced in Al films on Si substrates by oxygen ion implantation. A laser reflow technique was employed to vary the grain structure of some of the films. Transmission electron microscopy (TEM) was used to characterize the oxide particles and the grain size in the films, and a wafer curvature technique was employed to study the influence of microstructure on the deformation properties as a function of temperature.For coarse grained laser reflowed films, ion implantation increased the strength considerably, both in compression and in tension. Weak beam TEM techniques showed that the strengthening is most likely caused by attractive interactions between dislocations and particles. As-deposited and ion implanted films showed a stable grain size of only 0.35 μm after annealing, which caused significant softening to occur in compression, especially at high temperature. However these films showed very high stresses in tension at temperatures below 130°C. In these films the presence of the oxide particles stabilizes the small grain size and this causes a weakening effect which can be attributed to diffusion controlled grain boundary relaxation mechanisms. The high tensile stresses at temperatures below 130°C can be explained by direct and indirect particle strengthening.
Effects of Confinement on Plastic Deformation in Passivated Al Films
Authors: Anderson S.G.H. , Yeo I.-S. , Ho P.S. , Ramaswami S. , Cheung R. 
Published: March 2011

AbstractWafer curvature measurements of a trilayer (SiO2 / AlSiCu / Si) structure are compared to that predicted by a weighted sum of individual measurements of SiO2 and AISiCu films on Si, and significant differences are found to exist for temperatures above 200°C. A straightforward analysis of the stresses in each layer has been modeled using an extension of a model by Feng et al. which assumes uniform plastic deformation throughout the Al. The modeling results suggest a straightforeward method for determining stresses in deformable thin films that are confined by elastic overlayers. A comparison of the stress-temperature behavior for unpassivated and passivated AISiCu films reveals that the confined films exhibit less plastic deformation and both higher tension and compression during thermal cycling.
The Influence of Mechanical Stress on Hot-Carrier Degradation in Mosfet's
Authors: Wolf Ingrid De , Bellens Rudi , Groeseneken Guido , Maes Herman E. 
Published: March 2011

AbstractNon-uniform hot-carrier degradation in n-channel polycide-gate MOSFET's with different thicknesses of the poly-Si film, and in p-channel polycide-gate MOSFET's with TiSi2- or CoSi2-gate-silicide, is studied. The n-MOSFET's with the thinnest poly-Si film, show an increased interface trap generation, while the influence of the gate-silicide material on the degradation behaviour of the p-MOSFET's is found to be very small. The results are evaluated in terms of the effect of mechanical stress on the degradation characteristics: favourable for compressive mechanical stress and unfavourable for tensile stress. A correlation with stress measurements by micro-Raman spectroscopy is made.
Temperature Dependence of the l/f Noise in Heat-Treated Films of Al And Al-Cu
Authors: Biery Glenn A. , Smith Richard G. , Ficalora Peter J. 
Published: March 2011

AbstractThe 1/f noise in heat-treated Al and AI-Cu thin films was investigated at a current density of 20 mA/μm2 from approximately RT to 200 C. The results were consistent with the Dutta-Dimon-Hom model, i.e., the noise is the result of a collection of two-state systems. From the temperature dependence of the noise, a modified Dutta-Dimon-Hom model was used to extract the energy of formation, ΔHf, and the energy of migration, ΔHm, of the noise process. The development as well as simulations of this model will be discussed. It will be shown that ΔHm can be determined through investigation of the temperature at which the noise magnitude peaks for many frequencies. It will also be shown that ΔHf can be determined by investigation of the temperature at which the noise magnitude peaks and the temperature at which a, the negative of the logarithmic slope of the power spectral density, passes through 1. For both the Al and Al-Cu films, ΔHm was approximately 0.7 eV. The results also indicated that ΔHf was ≤ 0.1 eV for the Al films, and only slightly higher, i.e., 0.1 - 0.2 eV, for the Al-Cu films. The temperature at which cx passes through I was similar for both the Al and AI-Cu films. These results strongly suggest that the l/f noise is caused by the motion of Al atoms along the grain boundaries.
Modeling 1/f noise using a simple physical model based on vacancy motion
Authors: Klonais N. S. , Cottle J. G. 
Published: March 2011

AbstractA computer model is presented and used to simulate the motion of vacancies in a crystalline lattice. The lattice is modeled as a resistive array connected in series/parallel with vacancies represented as elements of high resistance in the array. Time series and spectra are generated by allowing the vacancies to move and these are consistent with actual waveforms produced by thin metal films. Simulation of temperature change yields dependencies similar to those predicted by Dutta and Horn (1979). By varying the density of vacancies the model predicts a variable Hooge parameter that saturates to a constant beyond a critical value.
The Finite Electromigration Boundary Value Problem
Authors: Lloyd J.R. , Kitchin J. 
Published: March 2011

AbstractThe solution to the finite electromigration boundary value problem has been obtained for the case of a blocking boundary downstream and a constant vacancy concentration upstream. The results are similar to the solution to the semi-infinite problem [1] except in the vicinity of the steady state. Consequences of achieving a “sub-threshold” steady state profile are discussed.
Evolution of Electromigration-Induced Voids in Single Crystalline Aluminum Lines with Different Crystallographic Orientations
Authors: Joo Young-Chang , Thompson Carl V. 
Published: March 2011

AbstractTransgranular slit-like voiding has been observed to cause fatal defects in electromigration- or stress migration-damaged Al submicron interconnects. To study the morphology and crystallographic characteristics of transgranular voids, we have tested single crystalline Al lines with various textures and in-plane orientations. Lines with (100), (110), and (111) textures were found to have triangular erosion voids along their edges. These voids were generally bound by {111} facets. While triangular erosion voids are frequently found in the lines, not all lead to failure of the lines. Some lines fail due to narrow, slit-like voids which are bound by {111} planes and lie along either <110> or <112> in-plane directions, depending on the orientations of the crystals relative to the orientations of the lines. Some of the slit-like voids are initiated along the erosion void facets. Similar void morphologies are observed in both unpassivated and passivated lines. Some of the lines have very large voids at the negative pad implying that voids are mobile. Through continued studies of the failure rates and failure morphologies of single crystalline lines, the mechanisms of transgranular failure of polycrystalline lines should be clarified.