bluuebunny/crossref_metadata_2025_split huggingface dataset:
Ion Scattering Studies of Defects In Gan Thin Films on C-Oriented Sapphire
Authors: Holländer B. , Mantl S. , Mayer M. , Kirchner C. , Pelzmann A. , Kamp M. , Christiansen S. , Albrecht M. , Strunk H. P. 
Published: April 2011

ABSTRACTEpitaxial GaN films grown by metal organic vapour phase epitaxy (MOVPE) or gas source molecular beam epitaxy (GSMBE) have opened up new applications in short wavelength photonic devices as well as high-power and high-temperature devices. The large lattice mismatch of 14% between GaN and sapphire, which is frequently used as the substrate, and the different thermal expansion coefficients generally lead to high densities of structural defects. We investigate the defect structure of MOVPE- and GSMBE-grown GaN layers on sapphire by Rutherford backscattering and ion channeling measurements. Channeling along the c-axis revealed χmin-values as low as 1.2% even in samples with dislocation densities in the order of 109 cm−2. Channeling measurements along different crystal planes were performed in order to improve the sensitivity to dechanneling by crystalline defects. Angular yield scans around the c-axis indicate clearly the hexagonal symmetry of the GaN lattice. Dechanneling results were combined with transmission electron microscopy investigations (TEM). The results suggest that the dechanneling-cross-section of edge dislocations is about 4 times larger than the dechannelingcross-section of screw dislocations. screw dislocations.
A Semi-Analytical Interpretation of Transient Electron Transport in Gallium Nitride, Indium Nitride, and Aluminum Nitride
Authors: Foutz B. E. , O'Leary S. K. , Shur M. S. , Eastman L. F. 
Published: April 2011

ABSTRACTThe energy dependent momentum and energy relaxation times, and the effective single valley energy dependent effective mass, are extracted from Monte Carlo simulations of gallium nitride, indium nitride, and aluminum nitride. A simple semi-analytical energy model, which uses these dependencies, is in good agreement with the results of transient Monte Carlo simulations. Both the Monte Carlo and the semi-analytical simulations show that the overshoot effects are most pronounced when the electric field abruptly changes from a value below a critical field to one above. This is attributed to the relatively large difference between the effective energy and momentum relaxation times for such a variation of electric field. Our calculations indicate that gallium nitride and indium nitride should have the most pronounced transient effects. A calculation of the transit times as a function of the gate length shows that an upper bound for the maximum expected cut-off frequencies are 260 GHz and 440 GHz for 0.2 μm gallium nitride and indium nitride field effect transistors, respectively.
An Erda Study on Proton Migration Induced by Electric Potential in SrZrO3,SrCeO3 and BaCeO3 Oxides:Measurements of Proton Transport Number and Proton Diffusivity
Authors: Kunimatsu A. , Arai T. , Takahiro K. , Nagata S. , Yamaguchi S. , Akiyama Y. , Sata N. , Ishigame M. 
Published: April 2011

ABSTRACTMigration of protons dissolved in acceptor doped SrZrO3, SrCeO3 and BaCeO3 oxides has been examined under an applied electric potential over a range of temperature from 25 to 220°C. Protons which dissolved in these oxides migrated to the cathode, and they were trapped there when the cathode material had a good ability to getter the migrating hydrogen. The amount of hydrogen accumulated in the cathode could be measured by the ERDA method using a highenergy 4He beam. We measured the amount of hydrogen in the cathode while monitoring the dc current passed through the oxide specimen. The proton transport number was determined from the ratio of the number of hydrogen in the cathode to the total numbers of charge through the specimen. The diffusion coefficient of proton was evaluated using the proton transport number and proton concentration in the specimen.
A Two-Step Low-Temperature Process For A P-N Junction Formation Due To Hydrogen Enhanced Thermal Donor Formation In P-Type Czochralski Silicon
Authors: Job R. , Fahrner W. R. , Kazuchits N. M. , Ulyashin A. G. 
Published: April 2011

ABSTRACTThe incorporation of hydrogen into standard p-type Czochralski (Cz) silicon (≥1 Ωcm) by a 110 MHz plasma treatment at 260°C leads to the formation of an n-type region due to hydrogen enhanced thermal donor (TD) formation in hydrogenated regions of the wafer, if a subsequent annealing in air is applied at 450°C. Spreading resistance probe (SRP) and light beam induced current (LBIC) measurements were used for the experimental analysis. The p-n junction depth, i. e. the counter doping by TDs, depends on the initial doping level of the p-type substrate, and therefore on the post-hydrogenation annealing time. The penetration of the n-type region into the wafer bulk is driven by a rapid hydrogen diffusion. The essential process for a TD generation is the creation of metastable hydrogen molecular species around 260°C and their decay at 450°C.
Hydrogen in a-Si:H Deposited by 55 kHz PECVD
Authors: Budaguan B. G. , Aivazov A. A. 
Published: April 2011

ABSTRACTIn this work the mechanism of hydrogen incorporation and structural stability of a-Si:H films deposited by LF 55 kHz glow discharge in a wide range of technological parameters have been investigated. The analysis of plasma emission spectra and microstructure of films measured by IR spectroscopy and atomic force microscopy were carried out. It was shown that hydrogen desorption controls the growth rate in a wide range of substrate temperature (40–325°C ) and at low values of LF power (50–200W). At the same time the abnormal increase of hydrogen content due to ion-molecule surface reactions with the increase of substrate temperature was observed. The kinetics of hydrogen diffusion and thermodynamics of defect formation in a-SiH films were determined from modeling of differential scanning calorimetry data. It is concluded that the mechanism of hydrogen incorporation leads to formation of strong Sill bonds in the material bulk and to increase of structural stability with the increase of substrate temperature despite of the increase of hydrogen content.
Electronic Structure and Energetics of LaNi5, α-La2Ni10H and β-La2Ni10H14
Authors: Nakamura H. , Nguyen-Manh D. , Pettifor D. G. 
Published: April 2011

ABSTRACTThe electronic structure and energetics of LaNi5, its hydrogen solution (α-La2Ni10H) and its hydride (β-La2Ni10H14) were investigated by means of the tight-binding linear muffin-tin orbitals method within the atomic sphere approximation (TB-LMTO-ASA). Preferred site occupancy by the absorbed hydrogen atoms was investigated in terms of the charge density of the interstitial sites and the total energy, both of which indicate that the 6m site in the P6/mmm symmetry is the most preferred. A negative heat of formation of La2Ni10H14 was obtained from the total energy calculations.
Hydrogen Adsorption of Ruthenium: Isosteres of Solubility of Adsorbed Hydrogen
Authors: Zaginaichenko S. Yu. , Matysina Z. A. , Schur D. V. , Pishuk V. K. 
Published: April 2011

ABSTRACTThe theoretical investigation of solubility isosteres of adsorbed hydrogen has been performed for free face (0001) of crystals with hexagonal close-packed lattice A3 of Mg type. The face free energy has been calculated and its dependence on temperature, pressure, hydrogen concentration and character of hydrogen atoms distribution over surface interstitial sites of different type has been defined. The equations of thermodynamic equilibrium and solubility of adsorbed hydrogen have been defined. The plots of isosteres in the region of phase transition from isotropic to anisotropic state have been constructed and it has been established that in anisotropic state the order in distribution of hydrogen atoms over interstitial sites of different type must become apparent. Comparison of the theoretical isosteres with experimental for ruthenium has been carried out, the isotropic-anisotropic state transition can stipulate a stepwise and break-like change in isosteres.
Al Dual Damascene Technology for Multilevel Interconnects
Authors: Kikuta Kuniko 
Published: April 2011

ABSTRACTAs the device dimension decreases, the number of metal layers increases and the metal pitch decreases, Al dual damascene has been known to achieve low fabrication cost because the fabrication processes can be simplified by using Al sputter-filling technology and Al CMP. However, from the electrical characteristics and reliability point of view, it was not clear if the Al dual damascene is suitable for fine pitch metallization. In this paper, we compare via characteristics among W-plug, Al-plug and Al dual damascene for multilevel interconnects.We investigated the via resistance and electomigration characteristics. Al dual damascene was formed by Al hot sputtering to fill via and trench, and by subsequent Al-CMP. The electromigration lifetime for via holes with misalignment between the 1st and 2nd Al for dual damascene is larger than that for conventional Al plug. On the dual damascene structure, via holes are opened first, then 2nd metal trench are patterned. Even misalignment between the 1st via and the 2nd Al occurs, contact area for dual damascene become large because of making contact at both of the via top and the side wall of the 2nd Al. The electromigration lifetime is longer for dual damascene with misalignment, in compared with that for Al plug and W plug with misalignment. Via resistance for dual damascene is almost the same as the via resistance for Al plug, which is lower than W plug. Via yield for dual damascene with misalignment is better than that for Al plug and W plug.In conclusion, we compared W-plug, A plug and Al dual damascene for multilevel interconnects. Al dual damascene was found to be durable and reliable in structure and process against misalignment in terms of electromigtration lifetime and via resistance, as well as yield. Al dual damascene is the most promising technology for fine-pitch metallization.
Investigation of the Homovalent Impurity in Aluminum to Form Alloys With Enhanced Interconnect Reliability
Authors: Kailasam Sridhar K. , Murarka S. P. , Glicksman M. E. , Merchant S. M. 
Published: April 2011

ABSTRACTDiffusion-induced failures such as stress-induced voiding and electromigration (EM) are a major concern for interconnect metallization in silicon integrated circuits. The addition of solute elements to aluminum interconnects often leads to “blocking” of high diffusivity paths such as grain boundaries and thus to an improvement in the resistance to electromigration failure. This research investigates Al-In, Al-La, and Al-In-La alloys to improve interconnect EM resistance. The choice of these alloying elements is based on the fact that they have negligible solid solubility in aluminum and are homovalent. Lower solubilities may lead to grain boundary stuffing and hence to improved EM resistance. In addition, the homovalency minimizes the adverse effect on the metal resistivity from addition of impurities to aluminum. Multicomponent diffusion principles are used to tailor aluminum-based ternary alloy compositions which would exhibit the multicomponent effect of zero flux planes (ZFPs), or regions in the reaction zone of a diffusion couple where the flux of a component goes to zero. This study involves modeling the occurrence of ZFPs for aluminum in several diffusion couples of Al-In-La, thus limiting the bulk diffusive spreading of aluminum so that the electromigration behavior can be inhibited or eliminated. This paper presents our experimental findings and discusses the modeling approach to determine ternary alloys exhibiting ZFPs.
Simulators of Thin Film Deposition for Silicon Device Processing
Authors: Gilmer G. H. , Baumann F. H. , Rubia T. Diaz de la 
Published: April 2011

ABSTRACTWe discuss simulators of the deposition of metal films onto substrates containing vias and trenches. Our Monte Carlo simulations of Al are based on extensive first-principles and molecular dynamics (MD) data for atomic-level energetics and transport rates. We find that surface mobilities are highly anisotropic, and that this has a pronounced influence on film morphology. We have investigated the effects of faceting and grain boundary grooving on step coverage, together with the variation of morphology with deposition rate, temperature, and length scale. Mass transport across low index facets is extremely slow near equilibrium, and this can inhibit the smoothening of surfaces and the elimination of depressions during annealing. The MC model also predicts grain structures during polycrystalline film formation, and the generation of preferred crystallographic orientations (texture). We present MC simulations for a range of conditions, and provide comparisons with experiments on the sputter deposition of Al and TiN films. Results from the MC model are being incorporated into a continuum model based on level-set methods, and we expect that this will form the basis for a simulator that can efficiently explore a wide range of conditions.
Study of Factor and Interaction Effects During Programmed Rate Chemical Vapor Deposition of Aluminum
Authors: Yang D. , Jonnalagaddal R. , Rogers B. R. , Hillman J. T. , Foster R. F. , Cale T. S. 
Published: April 2011

ABSTRACTResults from a statistically designed experiment studying the effects of initial substrate temperature (A), precursor pulse time (B), diluent gas flow rate (C), and their interactions on film properties of programmed rate chemical vapor deposited aluminum are presented. Deposition rate, reflectivity, absolute and normalized roughness, and grain orientation were the response variables investigated. A two level, three factor (23) full factorial experimental design was used. Five center cell replicates were used to estimate cell standard deviations. The experiments were conducted using tri-isobutyl aluminum (TIBA) as the precursor in a lowpressure chemical vapor deposition (LPCVD) cold wall reactor. Effects were considered significant at the 95% confidence level. Initial substrate temperature (A) affected deposition rate and reflectivity. Diluent gas flow rate (C) affected deposition rate, normalized roughness and film texture. The precursor pulse time/diluent gas flow rate interaction (BC) affected film reflectivity and absolute surface roughness, while the initial substrate temperature/diluent gas flow rate interaction (AC) affected film texture.
Debonding of Interfaces in Multilayer Interconnect Structures
Authors: Lane Michael , Ni Winnie , Dauskardt Reiner H. , Ma Qing , Fujimoto Harry , Krishna Nety 
Published: April 2011

ABSTRACTThe reliability of microelectronic devices containing multilayer structures is profoundly influenced by the interfacial strength (adhesion) and resistance to fracture (debonding) of the many resulting bimaterial interfaces. Adhesion and consequent structural integrity are closely related to composition and processing conditions which determine key interfacial parameters, such as interfacial impurities, morphology and adjoining microstructures. Residual stresses, thermo-mechanical cycling and mechanical loading may drive time dependent fracture in these multilayer interconnect structures. Moisture present in the atmosphere and perhaps moisture present in the layers themselves can lead to premature failure and reduced lifetimes of these devices. We present unique data showing the effects of interface non-planarity on the interface fracture energy and the time-dependent delamination processes. Data is presented showing the effects of the phase angle of loading on the interface fracture energy and subcritical debonding processes. Behavior is rationalized in terms of the salient chemical reaction rate occurring at the debond tip. Implications for life prediction of devices are discussed.
Kinetics of the C49-C54 transformation in patterned and blanket TiSi2 films: a comparison.
Authors: Via F. La , Privitera S. , Grimaldi M. G. , Raineri V. , Galli M. , Marabelli F. , Iannuzzil M. , Miglio L. 
Published: April 2011

ABSTRACTThe kinetics of the C49-C54 polymorphic transformation in titanium disilicides thin films grown on amorphous Si substrate has been followed by sheet resistance and Infrared Spectroscopy measurements on both blanket samples and submicron lines. The transformation of a fine grained C49 films (davg=30 nm) into the C54 phase was complete after annealing for ∼300 s at a temperature of 700 °C in blanket samples and of 730 °C in submicron lines. The Avrami exponent decreases from n=3 in blanket films to n=l in stripes. The transformation time at a given temperature increases with decreasing linewidth in agreement with the nucleation density model. Infrared Spectroscopy shows no shift of the peaks of the C49 phonons going from blanket to patterned films, suggesting the lack of strain on TiSi2 patterned films. The different behavior between blanket and laterally limited samples has been explained in terms of the different surface energies.
Capacitance-Voltage, Current Voltage, and Thermal Stability of Copper Alloyed With Aluminum or Magnesium
Authors: Felipe T. Suwwan de , Murarka S. P. , Bedell S. , Lanford W. A. 
Published: April 2011

ABSTRACTCopper alloyed with small amounts of aluminum or magnesium has recently been suggested as a promising material for interconnect applications in silicon integrated circuits. This work reports the results of the investigation of the electrical (capacitance-voltage and current-voltage) stability of the metal-oxide-semiconductor capacitor made with copper-0.5 at. % aluminum and copper-2 at. % magnesium as metal, deposited on thermally oxidized silicon substrates. Effect of thermal treatment in vacuum ambient before and/or during the electrical testing was investigated. The resistance to oxidation of these alloys was also investigated. The results show that copper magnesium, after a thermal treatment of 350°C or higher, produces a passivating layer at the interfaces that has excellent corrosion resistance and very stable behavior in terms of capacitance-voltage and current-voltage measurements. Copper aluminum performed adequately, much better than pure copper but was inferior to copper magnesium.
Finite Element Modeling for Interconnect Materials and Structures
Authors: Bassman Lori , Pinsky Peter , Deal Michael 
Published: April 2011

ABSTRACTWe present a Back-End Simulation Tool (BEST) developed to address important issues for modeling polycrystalline and multi-layered interconnect materials. During the temperature cycles of interconnect fabrication, diffusion and mechanical equilibrium processes are coupled. Accurate simulation of these systems leads to very large problems, and it is therefore necessary to partition the problem using a staggered scheme. We have developed an unconditionally stable algorithm which is crucial to the success of this approach. We are also able to consider the coupled effect of an electromigration driving force in conducting materials. In order to predict effectively the deformations and stresses which occur in structures fabricated from these materials, our work addresses the multiple length scales which characterize the problem. The simulations span from interconnect level structures to detailed descriptions of grain boundaries and material interfaces using continuously spatially varying material properties. The formulation naturally enforces segregation of impurities or vacancies (for metal self-diffusion) to and across interfaces and to surfaces. Our solutions of the coupled physical problems with the explicit inclusion of grain and layer structures make this a tool for efficient evaluation of the properties and reliability of new interconnect materials and layered structures. We will show some applications of our model to technologically relevant examples including hillock formation and interface stresses.
A Simple Co Salicide Process Using Silicidation by N2/H2 RTA
Authors: Sekiguchi Mitsuru , Moriwaki Masaru , Fujii Shinji , Mayumi Shuichi 
Published: April 2011

ABSTRACTFor Co salicide process, a TiN cap layer is widely used to prevent oxidation of Co layers during silicidation by RTA. In this study, N2/H2 mixture ambient is used to eliminate the need for the TiN cap layer. The sheet resistance for the sample fabricated by N2 RTA without TiN cap layer shows large standard deviations for narrow N+ diffusion layers and shows 20% higher values and large standard deviations for P+ diffusion layers. On the other hand, the samples with N2/H2 RTA provides the same low and stable sheet resistance as those of the samples with TiN cap layer. XPS analysis shows that N2/H2 RTA suppresses oxidation of Co during the 1st RTA because of reduction by H2. B impurity in PMOS regions is known to retard silicidation of Co at 500°C. The retardation of silicidation seems to enhance oxidation of Co in PMOS regions by residual oxygen in the RTA chamber.
Process Windows of Titanium, Cobalt and Nickel Silicide In Deep Submicron Poly-Si Lines
Authors: Poon M. C. , Deng F. , Ho C. H. , Chan M. , Lau S. S. 
Published: April 2011

ABSTRACTLow resistivity (∼15μΩ-cm) TiSi2, CoSi2 and NiSi lines have been shown to be thermally stable and show no linewidth dependence after ∼850°C, 800°C and 700°C/1 hour annealing on poly-Si (B, As, and P-doped) with linewidths down to ∼0.43, 0.42 and 0.15 μm. Better thermal stability of silicides might be correlated to the larger poly grains formed after high dose implant and post-implant anneal.
High Resolution Auger Imaging Combined with Focused Ion Beam for the Investigation of Metal/GaAs Contacts in High Power Transistors
Authors: Etienne Patrick , Landesman Jean-Pierre , Wyczisk Frederic , Cassette Simone , Delage Sylvain 
Published: April 2011

ABSTRACTInspecting and understanding the thermal stability of metal contacts in the context of reliability testing on high power transistors (especially in the GaAs technology) often necessitates to view atomic concentration profiles at deep interfaces. One common method for this purpose is the combined Auger spectroscopy/ion etching technique, where the region to be investigated is etched sequentially (with a “low” etch rate, typically in the Å/second regime) and Auger electron spectra (AES) are recorded at each step of the etching process. The 3 major resolution drawbacks of this approach are first that it is time-consuming, second that the spatial resolution is limited (atomic profiles on contact regions with lateral dimensions smaller that I R~m are difficult to obtain) and third that the interface of interest is “smoothed” during the etch process. The third point yields atomic concentration profiles with an apparent inter-mixing, which sometimes hinders observation of the details of interest for the interface under investigation.We have used a different approach for this aspect of metal contact testing, in which the interface to be studied is first “revealed” by focused ion beam (FIB) micro-sectioning. After this preparation step, chemical images of the interface are directly obtained by high resolution Auger electron spectra mapping. The different operating conditions for the FIB process (orientation of the cross-section with respect to the transistor surface, preliminary procedures to eliminate residual roughness as well as surface contamination) have been optimized in order to produce Auger spectra free of any artifact. The approach is demonstrated on Au/GeNiAu ohmics contacts to the emitter electrode of GaAs-based hererostructure bipolar transistor, designed for high power amplification in the microwave regime. Ultimate spatial resolution of 20 to 30 nm on the Ayuger chemical images is demonstrated on an Auger microscope equipped with a Schottky field emitting tip.