bluuebunny/crossref_metadata_2025 huggingface dataset:
Friction Characteristics with Pin-on-Disc Friction Test on Microstructured Surface Using Whirling Electrical Discharge Texturing
Authors: Lertphokanont Vitchuda , Sato Takayuki , Oi Masahiro , Ota Minoru , Yamaguchi Keishi , Egashira Kai
Published: September 2014

A microstructured surface was created on a steel surface by whirling electrical discharge texturing (WEDT) since it was considered that the microstructures could act as lubricant reservoirs to assist the formation of a lubricating film, resulting in reduced friction. In this study, friction tests under engine oil were carried out over a range of loads and sliding speeds. In addition, the surface characteristics of the microstructured surface were also investigated to optimize the friction characteristics of the textured surface through pin-on-disc friction tests. It was found that under the mixed lubrication condition near the boundary condition, textured surfaces with texture-area ratio of approximately 6% and a mean crater diameter of 35 μm were considered as the optimal conditions for reducing the friction coefficient. However, a texture-area ratio of approximately 4% and a mean crater diameter of 35 μm were considered as the optimal conditions for reducing the friction coefficient under the mixed lubrication condition near the elastohydrodynamic lubrication condition. It was considered that when the normal load decreased, the lubrication region changed from the mixed lubrication condition to the hydrodynamic lubrication condition, which meant that the actual contact surface area decreased. The decrease in the actual contact surface area with decreasing texture-area ratio led to a reduction in the friction coefficient. Finally, it was clarified that the friction coefficient was reduced under the optimized conditions of the microstructured surface through a pin-on-disc friction test.
Long-Duration Frictional and Wear Performance of the Diamond/DLC Bilayered Film under Water-Lubricating Condition
Authors: Chen Su Lin , Shen Bin , Sun Fang Hong
Published: September 2014

In the present study, the long-duration frictional and wear performance of the MCD/DLC (Micro-crystalline Diamond / Diamond-like Carbon) bilayered film are investigated under water-lubricating conditions. All friction tests are carried out on a rotation “ball-on-plate” tribotester where the MCD/DLC is slid against with a Φ 6.0 mm Si3N4ball and the whole sliding contact is immersed in deionized water during the sliding process. A full factorial experimental plan is conducted with four sliding velocities ranging from 0.126 to 0.503 m/s and four normal loads from 2 to 8 N. The duration of each sliding process is 24 h. For the sake of comparability, conventional MCD and NCD (nanocrystalline Diamond) films are also adopted under each sliding condition. The results show that the stable coefficient of friction (COF) of MCD/DLC film is ranging from 0.025 to 0.12 under the water-lubricating condition, comparable with the NCD film but much lower than that of single-layered MCD film; in contrast, the top-layered DLC film does not show beneficial effect on enhancing the sliding stability of single-layered diamond films. Moreover, its specific wear rate is estimated at the level of 10-8mm3N-1m-1, higher than that of MCD or NCD films. The sliding interface is under boundary lubrication condition, high normal load causes more prominent mechanical interactions between two contacted surfaces and thus produces a smoother and cleaner equilibrium sliding interface, which finally results in the decreasing tendency of stable COF as the load rises. Comparatively, the sliding velocity does not exhibit evident influence on the stable COF of the MCD/DLC film.
Tribological Analysis of Oxide Scales during Cooling Process of Rolled Microalloyed Steel
Authors: Jiang Zheng Yi , Yu Xiang Long , Zhao Jing Wei , Zhou Cun Long , Huang Qing Xue , Luo Guang Zheng , Linghu Ke Zhi
Published: September 2014

The composition and phase transformation of oxide scale in cooling process (after hot rolling) of rolled microalloyed steels affect tribological features of rolled strip and downstream process, and the produced steel surface quality. In this study, physical simulation of surface roughness transfer during cooling process with consideration of ultra fast cooling (UFC) was carried out in Hille 100 experimental rolling mill, the obtained oxide scale was examined with SEM to show its surface and phase features. The results indicate that the surface roughness of the oxide scale increases as the final cooling (coiling) temperature increases, and the flow rate of the introduced air decreases. The cracking of the surface oxide scale can be improved when the cooling rate is 20 °C/s, the strip reduction is less than 12 %, and the thickness of oxide scale is less than 15 μm, independent of the surface roughness. A cooling rate of more than 70 °C/s can increase the formation of retained wustite and primary magnetite precipitates other than the precipitation of α-iron. This study is helpful in optimising the cooling process after hot rolling of microalloyed steels to obtain quality surface products.
A Wear Simulation of the Fixed Soft Abrasive Film Based on Discrete Element Method
Authors: Zhou Zhao Zhong , Feng Kai Ping , Yuan Ju Long
Published: September 2014

A new polishing method by using fixed soft abrasive film is proposed to polish the end-face of the optic fiber connector. In order to study the wear property of the fixed soft abrasive film, the Particle Flow Code program was employed to simulate the interaction of surface topography. The discrete element model of the optic fiber connector and the fixed soft abrasive film were established. Through the interaction of the surface of two models, the process of contact and friction between the fixed soft abrasive film and the end-face of the optic fiber connector could be simulated. Simulation results showed that the main factors affecting the wear of the fixed soft abrasive film were pressure and speed, which mainly affected the normal stress and the tangential stress respectively. And the wear of the surface was mainly related to pressure and speed. The greater the speed and pressure were, the more serious wear of the fixed soft abrasive film was.
Effect of Cyclic Heating on the Hardened Layer Properties Generated by Plunge Cylindrical Grinding
Authors: Nguyen Thai , Liu Mei , Zhang Liang Chi , Wu Qiong , Sun Da Le
Published: September 2014

This paper investigates the effect of the grinding-induced cyclic heating on the hardened layer properties generated in plunge cylindrical grinding. It was found that by increasing the number of grinding cycles, the hardened layer becomes thicker. The cyclic grinding stressing together with the heating initiates a plastic deformation zone of a highly oriented microstructure. The surface residual stresses of the layer are compressive. Under a lower infeed rate, the tempering of the hardened layer material will occur more severely.
Study on the Flow Pressure of Mass in Centrifugal Disc Finishing
Authors: Matsumoto Yuji , Yamaguchi Tomomi , Kitajima Koichi , Yamamoto Akihiro , Takahashi Shinji
Published: September 2014

A pressure sensor is developed to explain the finishing mechanism in centrifugal disc finishing. The distributions of the flow pressure of mass in the radial direction and the height direction of the barrel are investigated. The flow pressure of mass is higher in the lower layer near the disc than in the upper layer, regardless of the finishing conditions. In the upper layer of the mass and near the side wall of the barrel, the flow pressure of the mass of the wet process is higher than that of the dry process. However, the stock removal of the dry process is larger than that of the wet process.
Development of Non-Contact Classifying Systems by Use of Acoustic Levitation
Authors: Inada Tomohiro , Zhou Li Bo , Shimizu Jun , Ojima Hirotaka , Ito Takuya
Published: September 2014

The phenomenon that bubbles or particles are suspended at the node position of a standing wave of sound is known as acoustic levitation and has recently been applied in the fields of semiconductors, aerospace, and biology [1-3]. By using this phenomenon in this study, a new classification method has been proposed, and a device has been developed to sort objects in accordance with their densities. Unlike the conventional methods as such as centrifugal particle separation or magnetic separation, this method can separate fine particles both of metal and non-metal and without contact easily only using acoustic power. First, we derived the acoustic radiation pressure to be applied to the object from King’s theory, and then we designed and developed a twin-transducer system to apply the required levitation force. The distributions of sound pressure and particle velocity were then visualized. Finally, a series of experiments was conducted to show the capability of classifying the fine abrasive SiO2 particles and fine iron particles (φ = 50 μm).
Simulation of Chip Formation Behavior during Single Diamond Grains Grinding by CEL Method
Authors: Dai Chen Wei , Xu Jiu Hua , Ding Wen Feng , Dai Jian Bo , Fu Yu Can
Published: September 2014

The grain orientation plays a great important role during single grain grinding. Single grain grinding simulation could offer an insight into the material removal behavior. However, grinding simulation with FE methods has problems arising from large deformations at the chip root and negative rake angles of the grain. In this work, a coupled Eulerian-Lagrangian method (CEL) is used to model the grinding behavior of single diamond grain in different orientations. The influence of the grain orientations on the grinding forces, grinding process (sliding, ploughing and cutting) and critical undeformed chip thickness are analyzed. The force ratio shows great accordance with the analytical calculation data. The simulation results show that the chip generates quickly and the special grinding force is relatively small when the diamond particle is in octahedral orientation (111)-(100). The workpiece material flows to the side and front owing to the pressing of cutting crystal face. The swelling of the material is generated beside the abrasive grain. The range and height of swelling are increased gradually and kept invariant after chip formation. The deformation of workpiece material contacting with grain edge is very severe. Therefore the biggest residual stress appears at the grain edge of the groove.
Effect of Surface Profile on the Material Removal Rate Distribution in CMP Process
Authors: Zhou Ping , Cai Ji Qing , Li Zhi Wei , Kang Ren Ke , Jin Zhu Ji
Published: September 2014

Material removal rate (MRR) distribution is a major concern in CMP process. In the published literatures, both experimental and theoretical research, MRR distribution is given without considering the surface profile of wafer. In this paper, the effect of surface profile on the MRR is analyzed based on the Preston equation and the contact pressure distribution calculated by the mixed lubrication model. It is found that the MRR distribution is dramatically affected by the profile of wafer surface, and whatever the polishing pad is conditioned in situ, the MRR distribution will be uniform at last. In addition, the wear of the pad surface induces a decrease of MRR.
Estimation of Grinding Cycle Time Taking into Account Specific Grinding Force
Authors: Yamada Takazo , Lee Hwa Soo , Miura Kohichi
Published: September 2014

In the grinding process, due to the elastic deformations of grinding machine and grinding wheel, the ground depth of cut is smaller than the applied depth of cut. Consequently, the ground depth of cut has to be controlled in spark-out grinding process. However, the cycle time in spark-out grinding process is not easy to be estimated. From such a viewpoint, in this study, using specific grinding force obtained by measured grinding force in the first spark-out pass, a calculating method of the real ground depth in continuous pass process is proposed. And, this method is experimentally evaluated.
Chemical Mechanical Polishing of Soft-Brittle Cadmium Zinc Telluride Wafers Using a Developed Environment-Friendly Solution
Authors: Zhang Zhen Yu , Wang Bo , Song Ya Xing
Published: September 2014

A novel chemical mechanical polishing (CMP) solution was developed. The CMP solution developed consisted of mainly silica, hydrogen peroxide, and malic acid. CMP solution is environment-friendly, which is different from those used in conventional CMP, consisting of acids or organic solvents. Fixed abrasive waterproof paper of alumina with mesh size of 3000 was used as lapping tool, to avoid embedding of free abrasives on soft cadmium zinc telluride (CdZnTe or CZT) surfaces employed in traditional lapping processes. The diameter of silica was varied from several tens of nanometers to 100 nanometers. Surface roughness Ra, and PV achieved using fixed abrasive lapping and developed CMP solution are 0.6 nm and 6.3 nm, respectively. The polished CZT surface was cleaned by deionized water and dried using compressed air, to avoid damages induced by conventional physical wiping and ultrasonic cleaning on soft-brittle CZT wafers.
Smoothed Particle Hydrodynamics Simulations for Ultrasonic Machining of Different Workpiece Materials
Authors: Wang Jing Si , Shimada Keita , Mizutani Masayoshi , Kuriyagawa Tunemoto
Published: September 2014

The material removal in ultrasonic machining (USM) is based on brittle fracturing of workpiece materials. The properties and fracture behavior are different for varied materials, and they would have an influence on the machining performance of USM. The smoothed particle hydrodynamics (SPH) method was used to simulate the USM process for different workpiece materials. Three typical hard and brittle materials, i.e. silicon carbide (SiC), alumina (Al2O3), and glass will be used as the workpiece materials. Experiments are also conducted for comparing with the simulation results. Through this study, the material fracturing processes for different work materials are shown visually using the SPH method, which is very useful for USM study.
Production of Fe-Al Alloy Coat on Steel Block by Scanning Laser Beam
Authors: Nunobiki Masayuki , Harada Yasunori , Okuda Koichi
Published: September 2014

Recently, the demand for long life to industrial products has risen. The high strength alloy coating on necessary part can decrease a manufacturing cost for life prolongation. This study proposes a laser surface alloying method to form an Fe-Al alloy coating on a carbon steel. By laser heating to an Al foil stuck on the steel, the mutual diffusion proceeds and the Fe-Al alloy grows. The material property of the generated alloy is greatly different according to a heat treatment temperature. For example, Fe3Al grows at 950 °C or more, and it has high toughness. A furnace heating effects the properties of inside of base material negatively. A high-frequency heating is not suitable for a local surface reforming. The laser processing is suitable for a local surface reforming. A defocused CO2 laser was irradiated to the Al foil stuck on the steel block by the shot lining in various processing conditions. The metal structures of the laser irradiated area was observed, to search for the suitable processing conditions for alloy coating. It was clarified that a local Fe-Al alloy coat was able to be formed without change of the properties of base material by high speed laser scanning.
Influence of Limited Efficiency and Competition of Vacancy Sinks/Sources on the Diffusion-Controlled Intermediate Phase Growth
Authors: Gusak Andriy , Kornienko Semen , Storozhuk Nadiya , Zaporozhets Tetyana
Published: September 2014

Kinetics and structural evolution of the intermediate phase layer formation during reactive diffusion is revisited. Main new input is an account of limited efficiency of vacancy sinks/sources at the moving interfaces and in the bulk, leading to nonequilibrium vacancy concentration gradients. Competition of the two types of vacancy sinks/sources is studied – K-sinks (providing Kirkendall lattice shift) and F-sinks (Frenkel-Kirkendall voids formation). Reactive diffusion with limited vacancy sources/sinks power in isothermal regime as well as in adiabatic SHS-regime is considered.
Atomic Migration Studies with X-Ray Photon Correlation Spectroscopy
Authors: Stana Markus , Ross Manuel , Sepiol Bogdan
Published: September 2014

The new technique of atomic-scale X-ray Photon Correlation Spectroscopy (aXPCS) makesuse of a coherent X-ray beam to study the dynamics of various processes in condensed matter systems.Particularly atomistic migration mechanisms are still far from being understood in most of intermetallicalloys and in amorphous systems. Special emphasis must be given to the opportunity to measureatomistic diffusion at relatively low temperatures where such measurements were far out of reach withpreviously established methods. The importance of short-range order is demonstrated on the basis ofMonte Carlo simulations.
Impurity Diffusion in Highly-Ordered Intermetallic Compounds Studied by Nuclear Quadrupole Interactions
Authors: Collins Gary S. , Wang Qiao Ming , Bevington John P.
Published: September 2014

Diffusion of impurity atoms depends on the sublattices occupied, active diffusion mechanisms, and jump frequencies to neighboring sites. The method of perturbed angular correlation of gamma rays (PAC) has been applied over the past decade to study impurity diffusion through measurement of nuclear quadrupole interactions (NQI) at nuclei of 111In/Cd probe atoms. Extensive measurements have been made on highly-ordered compounds having the L12 crystal structure, including In3R, Sn3R, Ga3R, Al3R and Pd3R phases (R= rare-earth element). Measurements in thermal equilibrium at high temperature served to determine lattice locations of 111In parent probe-atoms, through characteristic NQIs, and to measure diffusional jump-frequencies of 111Cd daughter probe-atoms, through relaxation of the NQI. This paper summarizes results of the jump-frequency measurements and relates them to the conventional diffusivity that can be determined, for example, from penetration profiles of tracer species. In spite of chemical similarities of the series of rare-earth phases studied, remarkably large variations in jump frequencies have been observed especially along series of In3R and Pd3R phases. Most phases appear as “line compounds” in binary phase diagrams, but large differences in site-preferences and jump-frequencies were observed for samples prepared to have the opposing limiting phase boundary compositions. Comparisons of jump-frequencies measured at opposing boundary compositions can give insight into the predominant microscopic diffusional mechanisms of the impurity. A change in diffusion mechanism was proposed in 2009 to explain jump-frequency systematics for In3R phases. An alternative explanation is proposed in the present paper based on site-preferences of 111Cd daughter probes newly observed along the parallel Pd3R series. The diffusivity can be expressed as the product of a jump-frequency such as measured in these studies and a correlation factor for diffusion that depends on the diffusion mechanism. The correlation factor can be modeled for the L12 structure and diffusion sublattice of interest using a five-frequency model originally proposed for metals. Although the correlation factor is an essential parameter for the diffusion of impurities, it has never been measured. It is suggested that values of the correlation factor can be determined feasibly by combining results of jump-frequency measurements such as the present ones with diffusivity measurements made for the same host-impurity systems.
Effect of Difference of Tool Rotation Direction on Forming Limit in Friction Stir Incremental Forming
Authors: Otsu Masaaki , Katayama Yosuke , Muranaka Takayuki
Published: September 2014

An effect of tool rotation direction on forming limit in friction stir incremental forming was studied. A 3-axes NC milling machine and a hemispherical tool which with a diameter of 6 mm made of high speed steel was used for forming. The thickness of commercial A5052-H34 aluminum sheet was 0.5 mm. The forming tool was moved from the outside to inside in a pitch of 0.5 mm spirally, and the sheets were formed into frustum of pyramid shape. Formability evaluated by minimum wall angle of the pyramid was investigated by changing a tool rotation rate, tool feed rate and tool path direction. When the tool paths were clockwise and counter clockwise, they were defined to “advancing direction” and “retreating direction” as well as in friction stir welding, respectively. From the experimental results, forming limits by both rotation directions of advancing and retreating were almost the same, however, the range of formable working conditions in advancing direction was slightly wider than that in retreating direction. Evaluating the forming limits in relative velocity between the tool surface and the sheet, no difference of forming limit was obtained between forming in advancing direction and retreating directions.
Analysis of the Helical-Wedge Rolling Process for Producing a Long Stepped Shaft
Authors: Pater Zbigniew
Published: September 2014

Helical-wedge rolling (HWR) is a forming process wherein the wedges are helically wound on the roll face. Developed at the Lublin University of Technology (Poland), the HWR process has been successfully applied to produce balls. The present paper describes an example of application of the HWR process for producing a long stepped shaft. The design of the process is discussed and the tools necessary for its realization are described. The developed rolling concept was positively verified by a numerical simulation. The distributions of effective strains and temperatures in a shaft are given, and the variations in forming forces and torques are presented. Particular emphasis is given to the problem of production accuracy of the shaft.
Effect of Viscoelasticity of PVA Brush on Friction during Post-CMP Cleaning: A Guideline for Nodule Configuration
Authors: Hara Y. , Sanada T. , Fukunaga A. , Hiyama H.
Published: September 2014

The application of new materials and three-dimensional structures are being used to achieve next-generation semiconductor devices. Hence, the role of the chemical-mechanical planarization (CMP) process has gained importance. Polyvinyl acetal (PVA) brushes are widely used as scrubbers during post-CMP cleaning. However, the mechanisms of brush scrubber cleaning are still a matter of debate because direct observation is difficult. Many researchers have proposed the removal mechanisms that operate during brush cleaning based on investigations of the forces acting on particles, friction, and the lubrication characteristics. Hydrodynamic drag forces and direct contact between the brush and the particles have been proposed as cleaning mechanisms [1–5]. Philipossian et al. [6] and Sun et al. [7] focused on the brush design and suggested that the existence of nodules or eccentricity of the roller brush had a significant effect on the friction. The friction system between the roller brush and the surface is complex because of the collision of nodules with the surface. Hence, the shapes of the nodules have been designed through trial and error. In this study, we focus on the friction of a single nodule to investigate the role of nodules in roller brush cleaning. The normal and friction forces are measured during brush sliding. In particular, we focus on the viscoelastic properties of a PVA brush and discuss its effects on friction.
Understanding the Formation of Circular Ring Defects in Post-CMP Cleaning
Authors: Hsu Ping , Luo Roger , Berar Pascal
Published: September 2014

Ring type defects are considered to come from scratches by large particles or agglomerated particles during brush scrubbing process on wafers in Post Cu CMP (chemical mechanical polishing) cleaning [1]. However, the mechanism for circular ring defects to appear on wafers still remains a puzzle. Our studies indicated that pH variation during the PCMP process might have a significant effect on altering the surface charge and triggering particle agglomeration. The extent and distribution of particle agglomeration were theoretically and experimentally investigated by zeta potential and particle size analyzer. The results from these studies can provide framework for formulation development to reduce or eliminate ring type defects after PCMP process and improve device yield and performance.
Particle Measurement with a Liquid-Borne Particle Counter: Analytical Figures of Merit
Authors: Liu Shi , Liu Bin
Published: September 2014

Particle contamination is one of the major concerns in semiconductor industry as it can reduce device yield, device quality and device reliability [1]. Liquid-borne particle counters (particle counters) are widely used to measure particle levels in water, chemicals, and other process liquids. In conjunction with sonication in ultrapure water and/or other liquids, these counters are also used to measure particle levels on surfaces of wafers and/or chamber parts to determine the cleanliness of wafer/part surface and to evaluate and improve surface cleaning processes. They have become indispensable tools in semiconductor surface cleaning processes [2].
Catalyst Assisted Low Temperature Pre Epitaxial Cleaning for Si and SiGe Surfaces
Authors: Dhayalan Sathish Kumar , Hikavyy Andriy , Loo Roger , Wostyn Kurt , Kenis Karine , Shimura Yosuke , Rosseel Erik , Profijt Harald B. , Maes Jan Willem , Douhard Bastien , Vandervorst Wilfried
Published: September 2014

Novel scaling approaches such as sGe channels on strain relaxed SiGe buffers, source/drain (S/D) stressors for FINFETs are usually grown using epitaxial process. Prior to the epitaxial growth, the starting surface should be free from oxygen and organic impurities. If not, these impurities would act as nucleating centres for defect formation resulting in defective epi growth. Conventionally, the wafers are HF dipped and then subjected to in-situ hydrogen bake at a temperature of 800°C in order to remove the above said impurities present on the wafer surface [1]. However, subjecting the strain relaxed SiGe to such high temperature baking would lead to roughening/islanding and subjecting the fins to high temperature baking might result in severe surface reflow [2]. As a result, the device performance would be adversely affected.
Detection of HO2•/O2•- Radicals Formed in Aqueous Solutions Irradiated with Megasonic Waves Using a Cavitation Threshold (CT) Cell Set-Up
Authors: Han Zhen Xing , Wu Bing , Brown Ian , Beck Mark , Raghavan Srini
Published: September 2014

Acoustic cavitation, especially transient cavitation, in solutions is accompanied by a number of physical and chemical effects. Due to high temperature and pressure conditions inside bubbles at their collapse, excitation of various species as well as formation of radicals occurs in solution [1-4]. Water molecules excited by megasonic irradiation typically dissociate to hydrogen and hydroxyl radicals (H• and OH•) [5]. The hydroxyl radical is a strong oxidant while the hydrogen radical has reducing properties. In presence of O2 in the solution, H• reacts with O2 to form hydroperoxyl (HO2•) radicals, which act as a reducing as well as a (weak) oxidizing agent [6]. Dissociation of hydroperoxyl radicals result in the formation of superoxide anion radicals (O2•-) as follows [6]:
Photo Lithography - Surface Preparation Interactions
Authors: Garnier Philippe
Published: September 2014

More than one third of process operations consist in surface preparations in the integrated circuits’ manufacturing. Most of them are directly or indirectly linked with photo lithography. This paper deals with these interactions.
Effect of Downstream Plasma Treatment on Dissolution of Fluorocarbon Polymer in Organic Solvents
Authors: Le Quoc Toan , Kesters E. , Devonport J. , Holsteyns F. , De Gendt S.
Published: September 2014

In back-end of line (BEOL), the fluorinated polymer deposited on dielectric sidewalls during patterning [1,2] must be removed prior to subsequent processing steps to achieve good adhesion and coverage of materials (metals) deposited in the etched features. However, it is known that this type of fluorocarbon polymer is chemically inert to many existing wet clean solutions, including aqueous solutions such as fluoride ion-containing or highly alkaline solutions, and solvent mixtures. Exposure of the polymer to UV irradiation of selective wavelengths and doses significantly modifies the polymer film, which results in substantial removal ability in a subsequent wet clean process [2-3].
HF-Last Wet Clean in Combination with a Low Temperature GeH4-Assisted HCl In Situ Clean Prior to Si0.8Ge0.2-on-Si Epitaxial Growth
Authors: Wostyn Kurt , Dhayalan Sathish K. , Hikavyy Andriy , Loo Roger , Douhard Bastien , Moussa Alain , Rondas Dirk , Kenis Karine , Mertens Paul W. , Holsteyns Frank , De Gendt Stefan , Profijt Harald B.
Published: September 2014

Epitaxial growth requires a clean starting surface for the growth of a high-quality crystalline layer. For epitaxy on Si, an HF-last wet clean followed by an in-situ high-temperature hydrogen bake is the reference pre-epi clean sequence to obtain an oxygen-free surface [1, 2]. The temperature required to remove all residual oxygen also makes the surface atoms mobile, resulting in reflow. The high temperatures used during the H2-bake can also result in intolerable doping profile changes. A lower temperature pre-epi clean sequence is required to avoid this reflow, especially when moving away from Si. In addition the high temperatures needed during a H2-bake would result in the relaxation of high mobility channels, e.g. strained Si1-xGex or III-V materials [3]. Several low temperatures pre-epi cleaning solutions have been proposed in the past, e.g. GeH4-assisted H2-bake [4] or more recently, a GeH4-assisted HCl clean [5]. In this study we looked at the interaction between HF-last wet clean and the in-situ GeH4-assisted HCl clean prior to Si0.8Ge0.2-on-Si epitaxy.
Industrial Challenges of TiN Hard Mask Wet Removal Process for 14nm Technology Node
Authors: Iwasaki Akihisa , Courouble Kristell , Lippy Steven , Buisine Fabrice , Ishikawa Hidekazu , Cooper Emanuel , Kennedy Evelyn , Zoll Stephane , Broussous Lucile
Published: September 2014

TiN Hard Mask (TiN-HM) integration scheme has been widely used for BEOL patterning in order to avoid ultra low-k (ULK) damage during plasma-ash process [1]. As the technology node advances, new integration schemes have to be used for the patterning of features below 80 nm pitch with 193 nm immersion lithography. In particular, thicker TiN-HM is necessary in order to ensure Self-Aligned-Via (SAV) integration which resolves via-metal short yield and TDDB issues caused by Litho-Etch-Litho-Etch (LELE) misalignment [2, 3]. The Cu filling process is significantly more difficult if the thick TiN is not removed because of the high aspect ratio of the structures. Moreover, with the use of TiN hard mask, a time-dependent crystal growth (TiCOF) residue may forms between line etch and metal deposition [4, 5], also hindering copper filling. Post-Etch-Treatment after line etching is one solution to the problem but N2plasma is not efficient enough to suppress the residue completely [6], and the CH4treatment proposed in [5] may be difficult to implement for 14 nm node, thus an efficient wet strip and clean provides a better solution.
TiN Metal Hardmask Residue Removal Formulation Development for Advanced Porous Low-K and Cu Interconnect Application
Authors: Cui Hua
Published: September 2014

TiN metal hardmask has been used to improve etch selectivity to low-k materials and thereby gain better profile control. For 14 nm and smaller technology nodes, it is required that the TiN hardmask is completely removed in order to improve the aspect ratio for subsequent reliable metal deposition. Thus, a chemical cleaning formulation with high TiN etch selectivity toward Cu and low-k is required.
Nuclear Magnetic Resonance Spectroscopy of Trace Organic Impurities Extracted from a Corrosion Inhibitor and a Semiaqueous Residue Remover
Authors: Westwood Glenn
Published: September 2014

Within the next ten years, advanced semiconductor manufacturing will move into the sub-10 nm regime [1]. At these dimensions, there is concern that molecular scale impurities (≤ 1 nm diameter) within cleaning chemistries will have an increasing impact on wafer cleanliness, device yield, and performance. Considering that these impurities may be on the same size scale as some of the active ingredients, this will raise significant challenges for solution developers in terms of impurity identification and prevention. Herein, we will describe our efforts to better understand the impurities within a semi-aqueous residue remover (RR). This work has primarily focused on identifying trace water-insoluble impurities not readily detectable by standard impurity characterization techniques, such as gas and liquid chromatography. The first part of this project involves a proof of concept study of isolating known impurities from a corrosion inhibitor (CI), and the second part of this study is the identification of unknown impurities within RR and the identification of the source of these impurities.
Impact of Fe and Cu Surface Contamination on High Efficiency Solar Cell Processes
Authors: Buchholz Florian , Wefringhaus Eckard
Published: September 2014

In wafer-based silicon solar cell technology cleaning of silicon surfaces has so far been treated without much interest – the cheapest, simple solution, which means mostly rinsing with or dipping into diluted acids (HCl, HF), was the best. Whatever worked was rarely further investigated. Hence, not much work has been published in the field of contamination control and cleaning process optimization and development. With solar cell efficiencies increasing and processes becoming more and more sensitive, the interest in quality control and optimization of cleaning processes is rising.
Ozone Base Cleaning: Impact on High Efficiency Interdigitated Back Contact Solar Cells
Authors: O’Sullivan B.J. , Haslinger M. , Singh S. , Bearda T. , Debucquoy Maarten , Szlufcik J.
Published: September 2014

Interdigitated back contacted (IBC) silicon solar cells have long been shown as high conversion efficiency solar cells, with values as high as 25.0% reported by Sunpower [1]. Such high efficiencies are enabled by the cell structure, with the absence of front side metal shading, which can then be optimised from optical and passivation perspectives. High bulk lifetime silicon and a low series resistance metallisation scheme can also enhance the efficiencies. Other advantages include the easier module incorporation given both metal contacts are located on the rear of the cell.
Rapid Determination of Organic Contaminations on Wafer Surfaces
Authors: Meyer Sylke , Timmel Sebastian , Hagendorf Christian
Published: September 2014

Irrespective of the semiconductor type and technology, organic contaminations on wafer surfaces have a detrimental impact on subsequent manufacturing steps and/or the device function. Therefore, it is of great interest to have a quick and reliable tool to detect those contaminations with sufficient sensitivity. In this study we investigated and optimized two methods which have the potential for in-line analytics since they are fast and simple: contact angle measurement and total organic carbon (TOC) determination. We present data on silicon wafer surfaces; however, the techniques may be suitable for all other wafer surfaces, too.
Surface Cleaning and Passivation of Chalcogenide Thin Films Using S(NH4)2 Chemical Treatment
Authors: Buffiere Marie , El Mel Abdel Aziz , Lenaers Nick , Brammertz Guy , Zaghi Armin E. , Meuris Marc , Poortmans Jef
Published: September 2014

Chalcopyrite ternary and kesterite quaternary thin films, such as Cu (In,Ga)(S,Se)2and Cu2ZnSn (S,Se)4generically referred to as CIGSSe and CZTSSe, respectively, have become the subject of considerable interest and study for semiconductor devices in recent years [1,2]. These materials are of particular interest for use as an absorber layer in photovoltaic devices. In thin film solar cells, the p-type CIGSSe or CZTSSe layer is combined with an n-type semiconductor thin film such as CdS buffer layer to form the p-n heterojunction of the device. The synthesis process of the CIGSSe or CZTSSe absorber layer requires temperatures ranging between 400 and 600 °C to form the photoactive chalcopyrite or kesterite phases [3,4]. During the synthesis process, the formation of trace amounts of binary/ternary compositions (i.e., undesirable secondary or impurity phases consisting of selenides, oxides, carbonates, etc.) may occur. These trace amounts of impurity phases may form at the nascent absorber surfaces, which could negatively affects the photovoltaic conversion efficiencies of solar cells [5-7]. Therefore, prior to the deposition of the CdS buffer layer, there is a need to clean the CIGSSe or CZTSSe surfaces to remove any possible traces of such impurities.
Wet Etch Rate Behavior of Poly-Si in TMAH Solution at Various Ambient Gas Conditions
Authors: Lin Euing , Guo Ted , Chien C.C. , Chang M.H. , Yu Wesley , Yang N.H. , Lin J.F. , Wu J.Y. , Robb Kenneth M. , Baldaro Alessandro , Other A.N.
Published: September 2014

As the demand for greater speed in semiconductor devices continues, a typical method of increasing charge mobility is to maximise the silicon strain at the depletion region in p-type transistors through the implementation of “Sigma Cavity” structures in the bulk silicon on either side of the gate structure. These structures, when filled, exhibit a uniaxial strain in the depletion region thus, increasing the charge transport speed [1]. The shape of the Sigma Cavity structure is important in maximising the strain in this region, thus strict control of the shape dimensions is imperative to the electrical performance of the device.
Platelet count to splenic diameter ratio and splenoportal index as non-invasive screening tools in predicting esophageal varices in patients with liver cirrhosis
Authors: Wadhwa Rajesh Kumar , Abbas Zaigham , Mujahid Hasan Syed , Luck Nasir Hasan , Younus Mahira , Anis Sabiha , Mubarak Muhammed
Published: September 2014

Background: Esophageal varices (EVs) are serious consequences of liver cirrhosis. Several studies have evaluated the possible non-invasive markers for the diagnosis of EVs to reduce the number of endoscopic procedures in patients with cirrhosis but without varices. This study was performed to evaluate the diagnostic performance of two such parameters (platelet count to splenic diameter ratio and splenoportal index) for the detection of EVs. Materials and Methods: A total of 111 patients with liver cirrhosis were analyzed after performing upper gastrointestinal endoscopy and non-invasive tests including platelet count and ultrasound abdomen including Doppler study. Appropriate statistical tests were applied to compare the non-invasive tests with the gold standard of endoscopy. Results: Of 111 liver cirrhotics, 80 (72.1%) were male and 31 (27.9%) were female. EVs were present in 68 (61.3%) patients and absent in 43 (38.7%) patients. In platelet count to splenic diameter ratio, a cut-off value of 1014 was obtained, which gave a sensitivity of 75.0%, specificity of 65.1%, positive predictive value (PPV) of 77.3%, negative predictive value (NPV) of 62.2% and diagnostic accuracy of 71.2%. In the splenoportal index, a cut-off value of 3.5 cm/s was obtained, which gave a sensitivity of 79.4%, specificity of 72.0%, PPV of 81.8%, NPV of 68.8% and diagnostic accuracy of 76.5% for the diagnosis of EVs. Conclusions: The platelet count to spleen diameter ratio and splenoportal index are non-invasive and fairly accurate alternatives in identifying the presence or absence of EVs in patients with compensated cirrhosis.
Comparison between corticosteroid injection and surgery in the treatment of trigger finger
Authors: Amiri Aref Hosseinian , Fatemeh Shirani , Mohammad Hosein Kariminasab
Published: September 2014

Background: Trigger finger is a common problem encountered in rheumatologic practice that causes a triggering or locking that may produce an uncomfortable sensation. There are various methods of treatment, ranging from conservative management to surgical release. Aim: To determine the effectiveness of corticosteroid injection and percutaneous release in terms of symptomatic relief, patient satisfaction and complications. Materials and Methods: In this prospective study, 50 patients who presented with trigger finger Grades 2 and 3 were randomized into two groups. One group received corticosteroid injection and, in the other group, percutaneous release was performed. These patients were then assessed weekly over a period of 6 weeks and their progress was noted. Results: Thirty cases (60%) were female and 20 cases (40%) were male. The age of the patients in this study was 40-65 years (mean: 48 years). Twenty-three cases (46%) were manual workers, 17 cases (34%) were semi-professionals and 10 cases (20%) were housewives. Most of the patients had involvement of the dominant hand (62%) and non-dominant hand involved in 38% of the cases. The most common presenting symptom was pain with triggering. In both groups, significant improvement in pain and triggering occurs in the first 2 weeks, but there was better improvement of pain and triggering in the corticosteroid group after 2 weeks. In terms of swelling of the digits, no difference was noted during the course of the treatment in the two groups. The corticosteroid group of patients had a complication rate of 6% and in the second group, the percutaneous group, had an 18% complication rate. There were a total of 12 patients who had recurrence (recurrence rate 24%): five (41.6%) cases in the first or corticosteroid group and seven (58.3%) cases in the surgery group. Conclusion: The group of patients treated with corticosteroid had a better relief of pain and triggering and had a lower complication rate. The recurrence was equal in both groups.
Acute esophageal necrosis in a patient with end-stage renal disease on hemodialysis
Authors: Osama Butt Muhammad , Luck Nasir Hassan , Mujahid Hassan Syed , Abbas Zaigham , Mubarak Muhammed
Published: September 2014

Spontaneous acute esophageal necrosis (AEN) has been reported to be extremely rare. The condition is defined as a dark pigmentation of the esophagus associated with histologic mucosal necrosis. The exact pathogenesis is still unknown, but several etiologies have been suggested including ischemia, gastric outlet obstruction, hypersensitivity to antibiotics, gastric volvulus and viral infection. We herein present a case of a middle-aged man with end-stage renal disease who presented with AEN following a hemodialysis session. Its diagnosis and management are discussed with reference to the pathogenesis of the condition.
Parallelization of an Implicit Algorithm for Multi-Dimensional Particle-in-Cell Simulations
Authors: Petrov George M. , Davis Jack
Published: September 2014

The implicit 2D3V particle-in-cell (PIC) code developed to study the interaction of ultrashort pulse lasers with matter [G. M. Petrov and J. Davis, Computer Phys. Comm. 179, 868 (2008); Phys. Plasmas 18, 073102 (2011)] has been parallelized using MPI (Message Passing Interface). The parallelization strategy is optimized for a small number of computer cores, up to about 64. Details on the algorithm implementation are given with emphasis on code optimization by overlapping computations with communications. Performance evaluation for 1D domain decomposition has been made on a small Linux cluster with 64 computer cores for two typical regimes of PIC operation: “particle dominated”, for which the bulk of the computation time is spent on pushing particles, and “field dominated”, for which computing the fields is prevalent. For a small number of computer cores, less than 32, the MPI implementation offers a significant numerical speed-up. In the “particle dominated” regime it is close to the maximum theoretical one, while in the “field dominated” regime it is about 75-80 % of the maximum speed-up. For a number of cores exceeding 32, performance degradation takes place as a result of the adopted 1D domain decomposition. The code parallelization will allow future implementation of atomic physics and extension to three dimensions.
A Cultural Reading of a Chinese White-Collar Workplace Bestseller and its Filmic Adaptation: Li Ke’s A Story of Lala’s Promotion and Go Lala Go!
Authors: Cai Shenshen
Published: September 2014

In 2007, Li Ke’s novel A Story of Lala’s Promotion (Du Lala Shengzhi Ji) became a bestseller among Chinese white-collar workers in foreign-owned (Western) companies and struck a chord with the Chinese middle class. The novel revolves around office politics, Western company culture and the white-collar lifestyle, the ‘shelved ladies’ phenomenon and middle-class aesthetics. To decipher the embedded cultural codes of this book, this study undertakes a textual analysis of the plots of A Story of Lala’s Promotion and its filmic adaptation, Go Lala Go! (Du Lala Shengzhi Ji dir. Xu Jinglei, 2010). This paper conducts a trans-media adaption study (from fiction to film) to examine three interrelated themes in the novel and the film. First, focusing on the influence of Western corporate culture on Chinese white-collar workers under economic globalisation, the widely circulating rules of Western workplaces are interpreted, clarifying the acculturating process of Western culture over its Chinese counterpart. The paper further explains that on the platform provided by foreign companies, and with the influence and training of Western corporate culture, intelligent and diligent young Chinese aspirational women struggle and realise their dreams in the workplace. Second, employing a feminist perspective, an attempt is made to address the situation of contemporary Chinese white-collar women represented by the contemporary social phenomenon of the ‘shelved ladies’, which also serves as an emblem of female independence and individualism. Third, through an analysis of the filmic adaptation, which focuses on the white-collar female’s lifestyle and consumption habits, the paper also highlights the contemporary Chinese population’s pursuit of a middle-class identity and aesthetic that mirrors the overwhelming consumerism of post-socialist China.