bluuebunny/crossref_metadata_2025_split huggingface dataset:
Poly-crystalline Ge thin films prepared by RF sputtering method for thermo photo voltaic application
Authors: Hoshi Daisuke , Nakamura Isao , Isomura Masao 
Published: June 2019

AbstractThe poly crystalline Ge films were prepared by the RF sputtering method with Ar and Ar-H2 mixture gases. The crystallization temperature increases from 400 °C to 500 °C due to the H2 introduction into the sputtering gases. On the other hand, the H2 introduction decreases the absorption coefficients in the long wavelength region corresponding to lower energy values than the energy gap of Ge, although much higher absorption coefficients are observed in the case of the Ar sputtering. Probably, the gap state density decreases due to the hydrogen termination of dangling-bonds in the grain-boundaries. The (220) preferential orientation is stressed and the highest Hall mobility is obtained with 75% of the gas flow ratio [Ar/ (Ar+H2)]. The preferential growth probably causes higher quality Ge films.
Mechanical Properties of Porous MSQ Films: Impact of the Porogen Loading and Matrix Crosslinking.
Authors: Ciaramella F. , Jousseaume V. , Maitrejean S. , Rémiat B. , Verdier M. , Passemard G. 
Published: June 2019

AbstractSemiconductor industry needs a continuously improvement of integrated circuits performance and an increase of integrated density on silicon. The 2004 ITRS Roadmap underlines the need of dielectric material for ILD with dielectric constant (k) lower than 3 for the 90 nm node and than 2.4 for the 45 nm node. In this work, porous films with k value lower than 2.2 were processed using a porogen approach. Firstly, a material composed of a methylsilsesquioxane (MSQ) matrix and of organic nanoparticles (called porogen) is deposited and baked. Then, this composite is thermally cured to allow the porogens degradation and matrix crosslinking. Different k values were obtained by varying the porogen loading in the composite. Mechanical properties of composite and porous films (before and after porogen removal respectively) were investigated using nanoindentation and FTIR analysis for different porogen loadings (between 0 and 40 %). The composite modulus is higher than the porous film modulus for high porogen loading. This result is interpreted in term of matrix crosslinking. Mechanical properties were also modelized using foam mechanical models. For high porosity level, the best Young modulus fitting is obtained with tetrakaidecaedric cells, which seems in good agreement with porosity morphology.
A Study of Impact Reliability of Lead-free BGA Balls on Au/Electrolytic Ni/Cu Bond Pad
Authors: Ou Shengquan , Xu Yuhuan , Tu K. N. , Alam M. O. , Chan Y. C. 
Published: June 2019

AbstractThe most frequent failure of wireless, handheld, and movable consumer electronic products is an accidental drop to the ground. The impact may cause interfacial fracture of wire-bonds or solder joints between a Si chip and its packaging module. Existing metrologies, such as ball shear, and pull test cannot well represent the shock reliability of the package. In this study, a micro-impact machine is utilized to test the impact reliability of three kinds of lead-free solders: 99Sn1Ag, 98.5Sn1Ag0.5Cu and 97.5Sn1Ag0.5Cu1In (hereafter called Sn1Ag, Sn1Ag0.5Cu, and Sn1Ag0.5Cu1In). The effect of thermal aging on the impact toughness is also evaluated in this study. We find a ductile-to-brittle transition in SnAg (Cu) solder joints after thermal aging. The impact toughness is enhanced by the thermal aging. This is a combination effect of the growth of intermetallic compound (IMC) at the interface provided strong bonding, and the softening of the solder bulk during the thermal aging absorbed more energy during plastic deformation.
Nanoporous Materials Integration Into Advanced Microprocessors
Authors: Todd Ryan E. , Labelle Cathy , Nitta Satya , Fuller Nicholas C.M. , Bonilla Griselda , McCullough Kenneth , Taft Charles , Lin Hong , Simon Andrew , Simonyi Eva , Malone Kelly , Sankarapandian Muthumanickam , Dunn Derren , Zaitz Mary Ann , Cohen Steve , Klymko Nancy , Moon Bum Ki , Li Zijian , Li Shuang , Yan Yushan , Liu Junjun , Ho Paul S. 
Published: June 2019

AbstractFuture microprocessor technologies will require interlayer dielectric (ILD) materials with a dielectric constant (κ-value) less than 2.5. Organosilicate glass (OSG) materials must be nanoporous to meet this demand. However, the introduction of nanopores creates many integration challenges. These challenges include 1) integrating nanoporous films with low mechanical strength into conventional process flows, 2) managing etch profiles, 3) processinduced damage to the nanoporous ILD, and 4) controlling the metal/nanoporous ILD interface. This paper reviews research to maximize mechanical strength by engineering optimal pore structures, controlling trench bottom roughness induced by etching and understanding its relationship to pore size, repairing plasma damage using silylation chemistry, and sealing a nanoporous surface for barrier metal (liner) deposition.
Determining Pore Structure and Growth Mechanisms in Templated Nanoporous Low-k Films
Authors: Peng Hua-Gen , Vallery Richard S. , Liu Ming , Frieze William E. , Gidley David W. , Yim Jin-Heong , Jeong Hyun-Dam , Kim Jongmin 
Published: June 2019

AbstractTemplating is one of the most popular methods for generating nanocomposite and nanoporous films and the resultant pore size and pore interconnection length depend strongly on porogen concentration/porosity among other factors. Positronium Annihilation Lifetime Spectroscopy (PALS) analysis has been performed on a series of films produced using increasing concentrations of a type of cyclodextrin (CD) porogen in a modified silsesquioxane host matrix. PALS reveals the relationship between the resulting pore structure (both size and interconnection length) and porosity, which can be used to deduce pore shape. At low porogen concentration, isolated pores are resolved, but the pore size is consistent with a cluster of two or three CD molecules, rather than an individual one. As the porosity increases, the aggregation of the porogen domains appears to be more 3-dimensional (pseudo-random) with gradual increase in pore size. Computer simulations using a random pore growth model show consistent trends for pore size growth, but the agreement is poor for interconnection length. It is a key demonstration of the usefulness of PALS in untangling the fundamental pore structure and its evolution in porosity. PALS characterization of porosity provides novel feedback in the understanding and design of nanoporous materials.
Thermal Oxidation of Cu Interconnects Capped with CoWP
Authors: Gambino J. , Smith S. , Mongeon S. , Meatyard D. , Chen F. , DeHaven P. 
Published: June 2019

AbstractThe thermal oxidation of Cu interconnects, at 350°C in air, has been studied as a function of thickness of a CoWP capping layer. For thin CoWP layers (25 nm), a thick oxide layer (200 nm) is formed which is mainly composed of Cu20. For thick CoWP layers (50 nm), the oxide layer is much thinner (36 nm) and is mainly composed of CoO. For both CoWP thicknesses, depletion of the underlying Cu is often observed after oxidation and whisker growth is often observed on the surface. The results are consistent with an oxidation mechanism where metal is the dominant diffusing species. For thin CoWP layers, Cu diffuses more quickly to the surface than Co, and therefore mainly Cu oxides are formed. For thick CoWP layers, the Cu diffusion to the surface is greatly reduced, and as a result, mainly Co oxides are formed. These results indicate that CoWP is not a good barrier for thermal oxidation, so high temperature exposure to oxidizing ambients must be minimized during processing of integrated circuits where CoWP is used instead of a dielectric barrier.
Effect of Microstructure and Dielectric Materials on Stress-Induced Damages in Damascene Cu/Low-k Interconnects
Authors: Joo Young-Chang , Paik Jong-Min , Jung Jung-Kyu 
Published: June 2019

AbstractThe line width dependence of stress in damascene Cu was examined experimentally as well as with a numerical simulation. The measured hydrostatic stress was found to increase with increasing line width. The larger stress in an interconnect with large dimension is attributed to the larger grain size, which induce higher growth stress in addition to thermomechanical stress. A stress model based on microstructure was constructed and the contribution of the growth and thermal stress of the damascene lines were quantified using finite element analysis. It was found that the stress of the via is lower than that of wide lines when both the growth stress and thermal stress were considered. This stress gradient between via and line, which is the driving force of vacancy diffusion, is larger when the low-k with lower stiffness and higher thermal expansion is used for dielectric layer. For this reason, the Cu/low-k can be more vulnerable to stress-induced voiding.
Material Reliability and Integration Issues of Polyimide and Benzocyclobutene Interlayer Dielectric Materials
Authors: Zantye Parshuram B. , Kumar Ashok , Gopalkrishnan R. , Balakumar S. 
Published: June 2019

AbstractThe constant push for decreasing the Resistance-Capacitance (RC) delay has led to the implementation of Multilevel Metallization (MLM) scheme for interconnect wiring, Cu as the wiring material and low ê materials as Interlayer Dielectric (ILD). Polymeric materials are being explored to replace SiO2 based ILD materials in the next generation ICs. Several reliability and integration challenges arise during integration of the candidate polymeric ILD when they are subjected to planarization by Chemical Mechanical Polishing (CMP). In this research, we have performed a comparative study of certain candidate low ê materials: 1) undoped SiO2 (standard), 2) Polyimide and 3) Benzocyclobutene (BCB). We have studied the impact of reduction in dielectric constant on the mechanical and tribological properties, and the CMP performance of these ILD materials. The adverse effect of shear and mechanical abrasion due to decreased mechanical properties of the low ê materials induced numerous defects during CMP.
Effect of Current Direction on the Reliability of Different Capped Cu Interconnects
Authors: Gan C. L. , Lee C. Y. , Cheng C. K. , Gambino J. 
Published: June 2019

AbstractThe reliability of Cu M1-V1-M2-V2-M3 interconnects with SiN and CoWP cap layers was investigated. Similar to previously reported results, the reliability of CoWP capped structures is much better than identical SiN capped structures. However, it was also observed that the reliability of CoWP capped interconnects was independent of the direction of electrical current flow. This phenomenon is different from what was observed for SiN capped structures, where M2 lines with electron current flow in the upstream configuration (“via-below”) have about three times larger median-time-to-failure than identical lines in the downstream configuration (“viaabove”). This is because the Cu/SiN interface is the preferential void nucleation site and provides the fastest diffusion pathway in such an architecture. Failure analysis has shown that fatal partially-spanned voids usually had formed directly below the via for “via-above” configuration, and fully-spanned voids occurred in the lines above the vias for “via-below” configuration.On the other hand, failure analysis for CoWP-coated Cu structures showed that partiallyspanned voids below the via do not cause fatal failures in the downstream configuration. This is because the CoWP layer is conducting, and thus able to shunt current around the void. As a result, a large fully-spanning void is required to cause a failure, just like the upstream configuration. Thus the lifetime of an interconnect with a conducting cap layer is independent of whether the current is flowing upstream or downstream.
Vertical integration of hydrogenated amorphous silicon devices on CMOS circuits
Authors: Wyrsch N. , Miazza C. , Ballif C. , Shah A. , Blanc N. , Kaufmann R. , Lustenberger F. , Jarron P. 
Published: June 2019

AbstractMonolithic integration of sensing devices usually requires sharing the CMOS chip floor space between sensors and their readout electronics. Vertical integration of the sensor on top of the electronics allows one to have the full chip area dedicated to sensing. For light detection, the deposition of hydrogenated amorphous silicon (a-Si:H) photodiodes on top of CMOS readout circuits offers several advantages compared to standard CMOS imagers. The issues regarding the design of a-Si:H photodiodes, their integration and the influence of the CMOS chip design (i.e. its surface morphology) on a-Si:H diode performance are discussed. Examples of TFA sensors for vision and particle detection are also presented.
Rf Hollow Cathode Plasma Jet Depopsition of BaxSR1-XTI03 Films
Authors: Ianno N.J. , Soukup R.J. , Hubička Z. , Olejnčcek J. , Ŝíchová H. 
Published: June 2019

AbstractAn initial study of the RF hollow cathode plasma jet deposition of BaxSr1-xTiO3 has been performed. Deposition occurred from a single composite nozzle consisting of BaTiO3 and SrTiO3 at substrate temperatures on the 500-550 C range. It has been shown that film composition can be easily controlled by the nozzle composition as well as other deposition parameters. The as-deposited films exhibit clear BSTO peaks with grain size on the order of 30nm.
Growth of Uniform Nickel Wire Arrays
Authors: Yang Kun , Yeh W. J. 
Published: June 2019

AbstractNickel nanowire arrays with high aspect ratio and large packing densities have been grown in thin nanochannel glass templates by an electrochemical deposition method. The templates were polished and etched for enough time to obtain parallel, uniform, hollow channels. One of surfaces of templates was then deposited with copper to provide an electrode. The pH value of NiSO4 aqueous solution was 1 to 2 and the deposition potential was chosen to be –1.2 V versus the saturated Calomel electrode. Obtained nickel wires were circular, each approximately 80 – 160 nm in diameter and 150 μm long, depending on the diameter of nanochannel. Finally, scanning electron microscopy has been used to characterize the nanostructures. Magnetic properties of the nickel wire arrays have been also investigated by using a superconducting quantum interference device magnetometer (SQUID).
Use of Ferrofluid Patterns as Diffusion Masks
Authors: Halverson Derek , Yellen Ben , Kalghatgi Sameer , Friedman Gary 
Published: June 2019

AbstractA novel method of dynamically and selectively controlling the diffusion of molecules using aggregation of ferrofluid is proposed. This method can be used to mask specific locations on a surface for combinatorial chemistry or to restrict diffusion of molecules in selected areas in a microfluidic device. This method works by using the controlled aggregation of stabilized 10nm diameter iron oxide particles (ferrofluid) to slow the diffusion of molecules in a similar manner as to how a porous media restricts diffusion. Dynamic aggregate formation is controlled by a magnetic pattern on a substrate in conjunction with an external field. The external magnetic field bias applied to the system causes ferrofluid to aggregate only in designated areas around the magnetic patterns thereby slowing diffusion through the areas where the aggregate clouds have formed.
Wafer Scale Nanopatterning and Nanomaterials Synthesis of Functional Nano Probes for Atomic Force Microscopy
Authors: Ye Qi Laura , Cassell Alan M. , Liu Hongbing , Meyyappan M. 
Published: June 2019

AbstractThe key hurdle in nanoscience and nanotechnology is the large-scale integration of nanoscale materials with micron scale electronics and structures to form functional devices and sensors. We have developed an innovative bottom-up wafer scale fabrication method that combines nanopatterning and nanomaterials synthesis with traditional silicon micromachining technologies. We have achieved nano-micro integration through catalyst nanopatterning and registration at wafer scale and through effective nanocatalyst protection and release before and after microfabrication. Our wafer scale fabrication process has produced 244 carbon nanotube (CNT) probes per 4-inch silicon wafer with control over the CNT location, diameter, length, orientation, and crystalline morphology. CNT probes with diameters of 40-80 nm and lengths of 2-6 μm are found to be functional nano probes for atomic force microscopy (AFM) imaging. In this paper, we will address our nano probe design and fabrication considerations in detail. CNT tip locations and diameters are defined by e-beam lithography. CNT length, orientation, and crystalline quality are controlled by the plasma enhanced chemical vapor deposition (PECVD) method. With effective catalyst protection schemes, this fabrication process is very similar to the conventional approach for fabricating wafer-scale silicon AFM probe tips. Process control is feasible and the overall yield is greatly improved. Our method and technology can be easily adapted to many other nanomaterials (nanotubes and nanowires) synthesis and processes for their rational design, fabrication, and integration in their applications.
Effect of substrate deformation in the nanowire/nanotube bending test
Authors: Chan Wingkin , Wang Yong , Li Jianrong , Zhang Tong-Yi 
Published: June 2019

AbstractThe present work analyses the effect of substrate deformation during the nanowire/nanotube bending test. An individual nanowire or nanotube is treated as a linear isotropic continuum. The substrate deformation is modeled by two coupled springs and the spring compliances arefunctions of the nanowire/nanotube diameter, and the Young moduli of the nanowire/nanotube and the substrates. An atomic potential is used to determine the adhesion between the nanowire/nanotube and its substrate. Consequently, a simple three dimensional Finite Element (FE) model is built to calculate the spring compliances. The load-displacement relation, which takes into account of substrate deformation, is derived in a closed form, which can be reduced to the load-displacement relations based on the simply-supported ends and the built-in ends. The numerical results indicate that the substrate deformation has a great influence on the determination of the Young modulus of a nanowire/nanotube from the bending test. The nanobridge test on carbon nanotubes is taken as an example to demonstrate the feasibility of the developed method.
Theory of large-scale electronic structure calculation and nanoscale mechanical property in fracture behavior of silicon
Authors: Hoshi Takeo , Takayama Ryu , Iguchi Yusuke , Fujiwara Takeo 
Published: June 2019

AbstractSeveral theories and program codes were developed for large-scale atomistic simulations with fully quantum mechanical description of electron systems. The fundamental concepts are generalized Wannier state and Krylov subspace. Test calculations were carried out with upto 106 atoms using a standard workstation. How electronic state is described in large-scale calculation was demonstrated on Si(001)-(2×1) surface. As a practical application, cleavage fracture of silicon was simulated with 10-nm-scale samples for investigating its nanoscale mechanical behavior. Discussions are focused on the unstable (001) cleavage mode and the stable (experimentally observed) (111)-(2×1) cleavage mode. As well as elementary surface reconstruction, step formation and bending in cleavage path were observed. These results were compared with experiments, such as scanning tunneling microscope (STM).
Precessing of 2024 Al /W Composites Prepared by Powder Metallurgy
Authors: Yang Zhimin , Yang Jian , Lian Youyun , Mao Changhui 
Published: June 2019

AbstractIn this work, the 2024 Al/W composites were fabricated by powder metallurgy. W powders and gas-atomized 2024 Al aluminum powder were milled by ball milling with different milling parameters. The mixtures were consolidated by vacuum hot press under a pressure of 400MPa and then hot-extruded for a higher density. A T6 heat treatment was carried out for the samples, which consisted of solution treating at temperature 470-500, water quenching and artificial aging at 1900 for 8h. The microstructure of as-milled mixture powders and the composites were investigated by combination of X-ray diffraction (XRD) and Field Emission Scanning Electron Microscopy (FESEM). The microstructure and its relationship with the mechanical properties of the composites were also investigated. The results show the milling-energy is a key factor for the processing of the composite. For the samples with high energy milling, Al atoms dissolved into W lattice gradually and finally formed a W solution after 6 hours milling, which can cause the a large amount of precipitation of WAl12, WAl5 in the following hot pressing process. With appropriate processing parameters, the tensile strength of the composite can reach 480 MPa.
Computational Modeling and Design of Adaptive Thin-Film Composite Coatings
Authors: Pearson James Deon , Zikry Mohammed A. , Rezvanian Omid 
Published: June 2019

AbstractThe tailoring of thin film coatings comprised of high strength constituents, such as diamond like carbon and partially stabilized zirconia and ductile constituents, such as gold and molybdenum is investigated by new microstructurally-based finite-element techniques for applications related to the wear, durability, and performance of these coatings over a broad range of temperatures and loading conditions. The effects of contact transfer films, grain-shape sizes and distributions, grain-boundary structure and sliding, texture, and strength are used to determine the optimal thin film coating compositions. Comparisons are made with experimental measurements and observations, and guidelines for optimal thin film composite coatings are proposed.
Simulation of Dislocation Relaxation in FCC Metals
Authors: Kogure Yoshiaki , Sakieda Kei , Kosugi Toshio , Nozaki Tadatoshi 
Published: June 2019

Abstract Motion of edge dislocation in copper crystals is investigated by means of molecular dynamics simulation. The embedded atom method potential was used in the simulation. Configuration and motion of dislocations are graphically demonstrated in 3-dimentional model. Change of mean potential energy during the dislocation motion is also investigated.
Lattice Dynamics and Thermodynamics of Bcc Vanadium at High Pressures
Authors: Sha Xianwei , Cohen R. E. 
Published: June 2019

AbstractWe investigate the lattice dynamics and thermodynamics of nonmagnetic bcc vanadium as a function of temperature and pressure, using the first principles linear response linear-muffin-tin-orbital method. The calculated phonon density of states (DOS) show strong temperature dependence, different from inelastic neutron scattering measurements where the phonon DOS show little change from room temperature up to 1273 K. We obtain the Helmholtz free energy including both electronic and phonon contributions and calculate various equation of state properties such as the bulk modulus and the thermal expansion coefficient. A detailed comparison has been made with available experimental measurements.