bluuebunny/crossref_metadata_2025_split huggingface dataset:
Growth and Electronic Properties in Hot Wire Deposited Nanocrystalline Si Solar Cells
Authors: Muthukrishnan Kamal , Dalal Vikram , Noack Max 
Published: April 2011

AbstractWe report on the growth and properties of nanocrystalline Si:H grown using a remote hot wire deposition system. Unlike previous results, the temperature of the substrate is not significantly affected by the hot filament in our system. The crystallinity of the growing film and the type of grain structure was systematically varied by changing the filament temperature and the degree of hydrogen dilution. It was found that high hydrogen dilution gave rise to random nucleation and <111> grain growth, whereas lower hydrogen dilution led to preferable growth of <220> grains. Similarly, a high filament temperature gave rise to preferential <111> growth compared to lower filament temperature. The electronic properties such as defect density and minority carrier diffusion length were studied as a function of the degree of crystallinity. It was found that the lowest defect density was obtained for a material which had an intermediate range of crystallnity, as determined from the Raman spectrum. Both highly amorphous and highly crystalline materials gave higher defect densities. The diffusion lengths were measured using a quantum efficiency technique, and were found to be the highest for the mid-range crystalline material. The results suggest that having an amorphous tissue surrounding the crystalline grain helps in passivating the grain boundaries.
CMP Active Diamond Characterization and Conditioner Wear
Authors: Borucki Leonard , Zhuang Rumin , Zhuang Yun , Philipossian Ara , Rikita Naoki 
Published: April 2011

ABSTRACTUsing a pad substitute material, we measure the number of active or working diamonds on a conditioner and find that it is generally a small fraction of the total number on the disc. The number of active diamonds also increases with the applied load and varies somewhat with sliding direction. However, even among the active diamonds, most do relatively little cutting. A few diamonds on a disc do most of the deep bulk cutting, a larger fraction skim the higher areas of the pad surface and most of the diamonds on the disc apparently merely help to support the load. While all of the diamonds that make contact, cutting or otherwise, may show evidence some of mechanical wear, wear of the small number of deep bulk cutting diamonds may be responsible for declining cut rates and for surprisingly low observed conditioner lifetimes.
Determining Pad-Wafer Contact using Dual Emission Laser Induced Fluorescence
Authors: Gray Caprice , Rogers Chris , Manno Vincent P. , White Robert , Moinpour Mansour , Anjur Sriram 
Published: April 2011

ABSTRACTIt is becoming increasingly clear that understanding the small scale polishing mechanisms operating during CMP requires knowledge of the nature of the pad-wafer contact. Dual Emission Laser Induced Fluorescence (DELIF) can be used to study the fluid layer profile between the polishing pad and the wafer during CMP. Interactions between the polishing pad surface and the wafer can then be deduced from the fluid layer profile. Previous investigations of pad-wafer interactions using DELIF include in-situ measurements of average fluid layer thickness and asperity layer compressibility, surface roughness measurements and polishing pad rebound into etched wells. In this paper, DELIF is used to determine pad-wafer contact, the point at the fluid film thickness goes to zero. We present a technique and some preliminary data for instantaneous measurement of in-situ pad-wafer contact using DELIF. The imaging area is 1.30×1.74 mm with a resolution of 2.5 μm/pixel. At this magnification, some regions imaged contain contact, whereas others do not. For the contact regions discussed in this paper, contact percentage varies from 0.07% to 0.27% on a Cabot Microelectronics D100 polishing pad. The asperity contact area increases with applied load, which was varied from 0.28 to 3.1 psi.
Fundamentals of Post-CMP Cleaning
Authors: Park Jin-Goo , Kim Tae-Gon 
Published: April 2011

ABSTRACTPost CMP cleaning is necessary for contaminant removal after CMP process. The zeta potential of slurry particle and substrate has been considered to be a critical factor in terms of particle adhesion and removal. The fundamental research such as the calculation and measurement of adhesion forces between slurry particle and wafer surfaces can enhance the understanding of cleaning mechanism and development of cleaning process. The presence of more than two different materials during CMP introduces new defects at the materials interface, corrosion and severe scratches. Device specific chemistry and cleaning process should be introduced and developed for future and current CMP. The highest particle removal efficiency is observed when using cleaning solutions that yields the lowest adhesion force. The effect of frictional and adhesion forces attributed to slurry particles on the quality of Cu surfaces was experimentally investigated during metal CMP process. The magnitude of the adsorption of the organic acid on the slurry particle surfaces can have a significant effect on the frictional behavior as well as the adhesion force. Higher particle adhesion forces resulted in higher friction and might induce defects such as particle contamination and scratches on the polished surface after polishing. The magnitude of particle adhesion force on wafer surfaces in slurries can be directly related to the frictional forces and polished surface quality during CMP process. As low k and poly or bare silicon polishing introduced in fabrication process, the hydrophobicity of these surfaces could affect the defects after polishing. The control of wettability during and after polishing becomes more important in reducing the defects. The organic particles are major defects during metal and poly silicon CMP which may be caused by the surface reaction of organic sources with surfaces.
Measurement of Interactions between Abrasive Silica Particles and Copper, Titanium, Tungsten and Tantalum
Authors: Burtovyy Ruslan , Tregub Alex , Moinpour Mansour , Buehler Mark , Luzinov Igor 
Published: April 2011

ABSTRACTColloidal probe technique has been widely employed to measure the adhesion between micro- and nanosize objects using atomic force microscopy (AFM). However, majority of studies concerns model systems, which do not incorporate real abrasive particles. The approach applied allows measuring adhesion between real CMP nanoparticles and different surfaces. Thin polymer film with high affinity to the particles was used to anchor the particles to a surface. Hollow glass bead (20-30 μm) representing flat surface was attached to soft AFM cantilever. Application of large hollow bead and the cantilever with small spring constant allows measuring the interactions with high sensitivity. Titanium, tungsten and tantalum metals were sputtered on the bead surface. The effect of different factors such as pH value, concentration and type of a surfactant on adhesion between surfaces of metals and silica slurry has been studied. Character and intensity of interactions at the moment of contact have been evaluated from experimental force-distance curves.
Screening Study on Frictional Force Analysis in Relation to Silica Abrasive and Slurry Properties
Authors: Zhuang Yun , Sampurno Yasa Adi , Sudargho Fransisca , Steward Geoff , Barthel Herbert , Mayer Erwin-Peter , Gottschalk-Gaudig Torsten , Stintz Michael , Kaetzel Uwe , Nogowski Andre , Goldstein Michael , Philipossian Ara 
Published: April 2011

ABSTRACTIn this study, different amounts of standard fumed silica and fumed silica contaminated by coarse particles was added as powder to a standard copper CMP slurry to investigate their effects on large particle count, mean particle size, slurry viscosity, frictional force during wafer polishing, and copper removal rate. Standard silica powder consisted of the same particles used in the standard slurry while contaminated silica powder consisted of the same particles used in the standard slurry and additional large size particles. Large particle count analysis indicated that slurry dispersion itself generated large size particles in the slurries. The addition of 0.3% and 1% contaminated silica to the standard slurry caused significant increases in large particle count, and the mean particle size increased with the amount of contaminated silica added to the standard slurry. The slurry viscosity generally increased with the amount of standard and contaminated silica added to the standard slurry under the shear rate of 100 s−1. The standard slurry and slurries added with 0.3% and 1% contaminated silica were used to polish 200-mm blanket copper wafers on the APD-500 polisher that has the unique ability to measure frictional force in real time during polishing. The coefficient of friction increased with the amount of contaminated silica added to the standard slurry. In general, the removal rates for the slurry added with 1% contaminated silica were higher than the standard slurry and slurry added with 0.3% contaminated silica.
Effect of Wettability of Poly Silicon on CMP Behavior
Authors: Kang Young-Jae , Kang Bong-Kyun , Kim In-Kwon , Park Jin-Goo , Hong Yi-Koan , Han Sang-Yeob , Yun Seong-Kyu , Yoon Bo-Un , Hong Chang-Ki 
Published: April 2011

ABSTRACTThe hydrophobicity of poly Si is reported to introduce different polishing behavior with careful control of post CMP cleaning process. The purpose of this study was to investigate the effect of poly Si wettability on its CMP behavior. The adhesion force of polymeric particle on the poly Si wafer surfaces was measured in the KOH solution (pH 11) as a function of solution A concentration. Adhesion force decreased and saturated as a function of concentration of solution A. The change of surface wettability affects not only the polishing rates but also the level of contamination on wafer because the interactions between particles and substrates are dependent on the wettability of the surface. Also, hydrophobic poly Si surfaces attracted much more pad particles with water marks than hydrophilic
On a Particle-Augmented Mixed Lubrication Approach to Predicting CMP
Authors: Higgs C. Fred , Terrell Elon J , Kuo Michael , Bonivel Joseph , Biltz Sarah 
Published: April 2011

ABSTRACTChemical mechanical polishing (CMP) is a process commonly used to planarize or polish thin film surfaces to enable stacking of additional levels to enhance lithographic patterning of wafers. It is used to make surfaces atomically smooth and is also an interim step in integrated circuit (IC) manufacturing. CMP is an example of a tribological regime called Particle-Augmented Mixed Lubrication (PAML) as named by the authors. PAML occurs when two surfaces in relative motion under load are partially separated by an intervening fluid-particle mixture. The load is supported by both asperities and fluid, and the interface is further complicated by the addition of nanoparticles. PAML involves four core components that must be modeled integrally—fluid mechanics, particle dynamics, contact mechanics, and material removal (wear). This work introduces the fundamental tenets of PAML, and describes how it is an effective first principle multi-physics approach to modeling CMP. By inputting the artificial random topographies for the pad and wafer with their actual mechanical properties, the PAML modeling simulation results predict the instantaneous material removal as the wear volume caused by particle-induced wear. These discrete instantaneous material removal events lead to the cumulative wear seen during CMP over a short time. Although only a small fraction of the time of the actual CMP process, tests of 120μs show that the cumulative material removal occurring over the entire simulation is approximately 0.012μm3. This work suggests that a generalized multi-physics modeling simulation of the CMP process is plausible.
Dissolution Kinetics of Nickel in Lead-free Sn-Bi-In-Zn-Sb Soldering Alloys
Authors: Barmak Katayun , Berry David C. , Khoruzha Vira G. , Meleshevich Kostyantyn A. , Dybkov Vasyl I. 
Published: April 2011

AbstractThe dissolution process of nickel in liquid Pb-free 87.5% Sn-7.5% Bi-3% In-1% Zn-1% Sb and 80% Sn-15% Bi-3% In-1% Zn-1% Sb soldering alloys has been investigated by the rotating disc technique at 250-450°C. The temperature dependence of the nickel solubility in the solders obeys a relation of the Arrhenius type cs = 4.94 × 102 exp (-39500/RT) % for the former alloy and cs = 4.19 × 102 exp (-40200/RT)% for the latter, where R is in J mol-1 K-1 (8.314 J mol-1 K-1) and T in K. The solubility values of nickel in the alloys differ considerably, while the dissolution rate constants are rather close. The data presented can be used to evaluate (i) the thickness of the dissolved portion of the solid nickel material during soldering, (ii) the extent of saturation of a solder with nickel and (iii) the effect of dissolution on the growth rate of intermetallic layers at the Ni-solder interface.
Arsenic in ZnO and GaN: Substitutional Cation or Anion Sites?
Authors: Wahl Ulrich , Correia Joao Guilherme , Rita Elisabete , Marques Ana Claudia , Alves Eduardo , Soares Jose Carvalho , Isolde Collaboration The 
Published: April 2011

AbstractModifying the properties of ZnO and GaN by means of incorporating arsenic impurities is of interest in both of these semiconductors, although for different reasons. In the case of ZnO, the group V element As has been reported in the literature as one of the few p-type dopants in this technologically promising II-VI compound. However, there is an ongoing debate whether the p-type character is due to As simply replacing O atoms or to the formation of more complicated defect complexes, possibly involving As on Zn sites [1]. In the case of GaN, the incorporation of high concentrations of As has been studied with respect to the formation of GaAs(x)N(1-x) alloys and the related modification of the GaN band gap and its luminescence behaviour. It has been suggested that As in GaN is amphoteric, with its lattice site preference depending on the doping character of the material, i.e. mostly substitutional Ga in p-type but also substitutional N in n-type [2].We have determined the lattice location of implanted As in ZnO and GaN by means of conversion electron emission channeling from radioactive 73As. In contrast to what one might expect from its nature as a group V element, we find that As does not occupy substitutional O sites in ZnO but in its large majority substitutional Zn sites [3]. Arsenic in ZnO is thus an interesting example for an impurity in a semiconductor where the major impurity lattice site is determined by atomic size and electronegativity rather than its position in the periodic system. The results are different in the case of As implanted into GaN, where we found roughly half of the implanted As atoms occupying Ga and the other half N sites. The amphoteric character of As therefore certainly plays a role in explaining the extreme difficulties in growing high quality GaAs(x)N(1-x) alloys with values of x above a few percent.A preliminary report will also be given on ongoing emission channeling lattice location experiments using radioactive 124Sb in ZnO and GaN.
Predominance of Alternate Diffusion Mechanisms for the Interstitial-Substitutional Impurity Gold in Silicon
Authors: Li Hui , Li Na , Joshi Subhash M. , Tan Teh Y. 
Published: April 2011

AbstractIt is well known that Au indiffusion in Si is dominated by the Kick-Out mechanism governed by Si self-interstitials, with negligible contribution from the Frank-Turnbull mechanism governed by vacancies. In this paper we present modeling and simulation results to show that the Frank-Turnbull mechanism actually dominates Au outdiffusion in Si.
Electronic structure of Cd, In, Sn substitutional Defects in GaSe
Authors: Rak Zsolt , Mahanti Subhendra D , Mandal Krishna C , Fernelius Nils C 
Published: April 2011

AbstractAb initio electronic structure calculations within density functional theory have been carried out in pure GaSe and GaSe doped with substitutional impurities (Cd, In and Sn) at the Ga site in order to understand the nature of the defect states and how they depend on the nominal valence of these three impurities. We find that Cd impurity introduces a defect state located between 0.1 – 0.18 eV above the valence band, in good agreement with photoluminescence peaks seen at 0.13 eV and 0.18 eV. Using both experimental and theoretical effective mass parameters we show that effective mass model fails to describe these acceptor states. Sn changes the single particle density of states (DOS) near the bottom of the conduction band, and gives rise to resonant states deep in the valence band. In, on the other hand, behaves like Ga, it does not make noticeable change in the DOS of the host GaSe crystal.
Stress Effects on As Activation in Si
Authors: Ahn Chihak , Dunham Scott T 
Published: April 2011

AbstractWe studied stress effects on As activation in silicon using density functional theory. Based on lattice expansion coefficient, we calculated formation energy change due to applied stress and plotted the stress dependence of AsmV concentration. We found that biaxial stress results in minimal impact on As activation, which is consistent with experimental observation by Sugii et al. [J. Appl. Phys. 96, 261 (2004)], who found no significant change in As activation under tensile stress.
Low-Energy Irradiation Damage in Single-Walled Carbon Nanotubes
Authors: Suzuki Satoru , Kobayashi Yoshihiro 
Published: April 2011

AbstractWe show that low-energy (20 eV–20 keV) electron or photon irradiation extinguishes the characteristic physical and chemical properties of single-walled carbon nanotubes, indicating that the irradiation damages the nanotubes. The irradiation-induced defects convert the electric properties of metallic SWNTs to semiconducting, and the nominal bandgap can be tuned simply by the irradiation dose. The defects also have the following interesting properties. The damage and recovery are reversible, indicating that the number of carbon atoms is preserved. The damage and recovery strongly depend on the diameter, suggesting that the damage is prominent in a rolled up graphene sheet, but not in a planar one. The activation energy of the defect healing is so small, depending on the diameter, that the defects can be healed even at room temperature or below.
Gettering Effect in Low and High Density Structural Defect Regions of the Cast Multi-Crystalline-Silicon Wafer
Authors: Park Yongkook , Lu Jinggang , Rozgonyi G. A. 
Published: April 2011

AbstractTwo cast multi-crystalline silicon (mc-Si) sister wafers before and after solar cell processing were investigated to explore the gettering effect in low and high density structural defect regions. For the processed wafer, the minority carrier recombination lifetime was correlated to the structural defect distribution. For the low density region of as-grown wafer, Cr impurities were 3.28x1013cm-3 and they were reduced to 1.74×1012cm−3 for the processed wafer. The isolated Cr impurities dissolved from the precipitates at 900°C which is the typical gettering temperature in the solar cell processing are getterd effectively in the low density regions. Our current understanding for the gettering effect in the high density regions is that the segregated Cr impurities at defect sites are not released to the silicon matrix at 900°C resulting in the poor gettering effect.
In-situ Infrared Absorption Monitoring of Atomic Layer Deposition of Metal Oxides on Functionalized Si and Ge Surfaces
Authors: Dai Min , Kwon Jinhee , Ho Ming-Tsung , Wang Yu , Rivillon Sandrine , Li Meng , Chabal Yves Jean , Boleslawski Marek 
Published: April 2011

AbstractThe nature of the interface between Si and Ge substrates and high-k dielectrics often controls the performance of MOSFET devices. Precleaning and/or chemical functionalization of the surfaces can dramatically affect the formation of an interfacial layer. We have used in-situ IR spectroscopy to probe the relevant interfaces during ALD growth for a variety of surface treatments, including H- and Cl-termination, and nitridation. This paper focuses on understanding of the mechanisms for interfacial SiO2 (or GeOx) formation during HfO2 growth using tetrakis-ethylmethylamidohafnium (TEMAH) as the metal precursor and water or ozone as the oxygen precursor. We find that impurities arising from incomplete ligand elimination during growth (e.g. OH for H2O processing and CO- and NO-containing species for O3 processing) are incorporated into the HfO2 film during growth. Upon annealing, most of these species react, but can also migrate to the interface. Nitridation of Si and Ge surfaces will in general prevent SiO2 or GeOx formation but can also affect the growth rate.
Preparation of Substrates for IBAD-MgO Coated Conductors
Authors: Matias Vladimir , Hänisch Jens , Rowley E. John , Sheehan Chris , Clem Paul G. , Kumasaka Noriyuki , Kodaka Ichiro 
Published: April 2011

AbstractWe examine the influence of various substrate preparation procedures for ion-beam assist deposition (IBAD) texturing of MgO. IBAD-MgO nano-texturing is very sensitive to the nucleation surface, and surface roughness has an important influence on the texture of the MgO layer. We studied Hastelloy C-276 metal alloy as the substrate. The untreated substrate is leveled by either electropolishing, mechanical polishing or solution deposition. All three methods are applied to continuously moving tapes in long lengths. The RMS surface roughness decreases from 20-50 nm for the untreated substrate to 0.5 nm, 0.3 nm and 1 nm respectively. The in-plane and out-of plane crystalline alignment of the MgO layer improves as the roughness is decreased below 2 nm.
AC Current Driven Flux Dynamics in YBCO Coated Conductors
Authors: Lucarelli Andrea , Yang Ran , Luepke Gunter , Levin George , Haugan Timothy , Barnes Paul 
Published: April 2011

AbstractWe present a time-resolved magneto-optical imaging study of YBa2Cu3O7-δ coated conductors in alternating current regime. The evolution of the magnetic flux density distribution in the superconducting samples is imaged at small steps of the phase of the applied AC current. The flux penetration during the phase evolution is inhomogeneous due to the grain structure of the coated conductor. A quantitative analysis of the images show how grain boundary network affects the overall behavior of the flux and current density evolution.
Pattern Transfer Process Using Innovative Polymers in Combined Thermal and UV Nanoimprint Lithography (TUV-NIL)
Authors: Brunetti Francesca , Harrer Stefan , Scarpa Giuseppe , Lugli Paolo , Kubenz Mike , Schuster Christine , Reuther Freimut 
Published: April 2011

ABSTRACTWe performed combined thermal and ultraviolet nanoimprint lithography (TUV-NIL) using a recently developed nanoimprint polymer (mr-NIL 6000 from Micro Resist technology GmbH) and achieved an imprinted feature size of 50 nm. We used commercially available 2-inch-diameter transparent quartz molds (NIL Technology, Denmark and Obducat, Sweden) comprising 150 nm to 190 nm-deep features of various shapes and aspect ratios with lateral dimensions ranging between 50 nm and 300 nm. The imprint polymer was spun onto a silicon substrate, covered with an oxide layer. After the TUV-NIL step, residual polymer layers at the bottom of the imprinted features were removed by oxygen plasma etching. Imprinted patterns were then transferred into the silicon oxide layer underneath by reactive ion etching (RIE). In a final step the residual polymer was stripped off the silicon oxide surface in an oxygen asher. All imprinted features as well as the corresponding pattern transfer results showed good surface and sidewall characteristics.