bluuebunny/crossref_metadata_2025 huggingface dataset:
Microstructure and Texture Evolution in Metals and Alloys during Intense Plastic Deformation
Authors: Zhilyaev Alexandre P. , McNelley Terry R. , Ruano Oscar A.
Published: April 2012

ntense plastic deformation is generally effective in producing grain refinement. IPD methods include equal channel angular pressing/extrusion (ECAP/ECAE), high-pressure torsion (HPT), accumulative roll bonding (ARB), and friction stir processing (FSP), among others. In this work, we summarize the main results on grain refinement by these processing methods and present our own data on microstructure and texture evolution in metals and alloys during ECAP, HPT and FSP. Whereas ECAP and HPT are usually performed with the work piece material initially at room temperature or even at liquid nitrogen temperature to enhance refinement, FSP involves a brief but complex thermomechanical cycle with peak temperatures up to 0.7 0.9 TMelt. Apparently, materials undergo dynamic recrystallization (DRX) during FSP. DRX also occurs also in metals and alloys of low TMeltdue to adiabatic heating during HPT performed at room temperature. The paper is devoted to revisiting of previous as well as new results and a comparative analysis of microstructure and texture evolution in commercially pure aluminum and selected pure metals and alloys during ECAP, HPT and FSP in order to illustrate the limits of grain refinement.
Modelling the Recrystallization Behaviour during Industrial Processing of Aluminium Alloys
Authors: Marthinsen Knut , Friis Jesper , Holmedal Bjørn , Skauvik Inge , Furu Trond
Published: April 2012

The microstructure evolution in commercial AlMgSi alloys during and after extrusion of a simple U-shaped profile has been modelled. The strain, strain rate and temperature along a set of particle paths are taken from FE-HyperXtrude simulations and used as input to the work hardening model ALFLOW, to predict the evolution of the subgrain size and dislocation density during deformation. As soon as the profile leaves the die, the subsequent recovery and recrystallization behaviour is modelled with the softening model ALSOFT. This procedure enables the modelling of recrystallization profiles, i.e. the fraction recrystallized through the wall thickness of the extruded profile. The sensitivity to chemistry (alloy composition), profile deflection and the cooling rate at the die exit has been investigated by means of a set of generic modelling cases.
Recrystallization during Annealing of a Cold Rolled Lean Duplex Stainless Steel
Authors: Herrera Clara , Ponge Dirk , Raabe Dierk
Published: April 2012

Duplex stainless steels (DSSs) are based on the Fe-Cr-Ni system and formed by ferrite (30-70%) and austenite. They have high tensile strength, good toughness and weldability and excellent corrosion resistance including stress-corrosion cracking and resistance to localized corrosion. The increase of the raw materials of the last years, there has been a motivation to develop new stainless steels with lower contents of nickel and molybdenum. Lean duplex stainless steels (LDSSs) are almost Mo free and nickel content lower than 4%. The lean duplex grades are expected to substitute not only 304/316 grades but also other duplex stainless steel grades. LDSSs are used for structural applications and for the less corrosion conditions such as liquor tanks and suction rolls. The aim of the present work was to study the kinetics of recovery and recrystallization of the lean duplex stainless steel 1.4362 during annealing treatment. The material was subjected to hot rolling and cold rolling of 70%, annealing treatment for different times at temperatures from 1000 to 1100°C and subsequently water quenched. Optical microscopy and electron back scattering diffraction (EBSD) were employed to study the evolution of the microstructure during the annealing treatment. After cold rolling austenite exhibited more strain hardening than ferrite. Consequently, the driving force of the austenite for recrystallization is higher. During annealing, recovery took place in ferrite, while the austenite remained nearly unrecovered until beginning of recrystallization. The layered grain morphology produced during cold rolling remained after the annealing treatment. The volume fraction of the phases did not show significant changes with the annealing time. Nevertheless, the volume fraction of austenite decline with an increasing of annealing temperature. After 60 seconds at 1100°C, annealing primary recrystallization had progressed in both phases, which show a bamboo-structure where the grain boundaries ran perpendicular to the phase boundaries. Grain growth progressed for longer annealing times. After 600 seconds, the bamboo-structure started to change for a more globular grain structure, pearl-structure. It continued and became more pronounced at longer annealing times. At lower temperatures, the recrystallization behavior is similar; however, the structure was refined. Recovery is favored by the high stacking fault energy of ferrite and the layered grain morphology. The lean duplex stainless steel 1.4362 shows a similar recrystallization kinetics compare with standard duplex stainless steels.
Assessment of the Stored Energy Evolution during Batch Annealing Process of Cold Rolled HSLA Steels
Authors: Fang Chao , Garcia C. Isaac , Choi Shi Hoon , DeArdo Anthony J.
Published: April 2012

Stored energy in deformed metals plays an important role during the annealing process by providing the initial driving force for recovery and recrystallization. Many direct or indirect measurement and calculation methods have been used to evaluate the amount and distribution of the stored energy in the past decades. The advent of relatively new analytical techniques such as Electron Back-Scattered Diffraction (EBSD) has permitted the development of mathematical models such as Sub-grain Method, Image Quality (IQ) Method and Taylor Factor Method etc., these new techniques have permitted a much better understanding of the annealing behavior of cold rolled steels. The sub-grain method based on the level of sub-grain structure is used in our study to quantify the stored energy distribution prior to and its evolution during the batch annealing process of cold rolled HSLA steels. Orientation dependent stored energy distribution maps at different annealing stages have been constructed and analyzed. The results of this study show that the stored energy increases with cold rolling reduction ratio and its distribution through the thickness of the steel sample is not uniform due to the inherit inhomogeneous deformation process. The stored energy was continuously consumed during annealing. The amount of γ-fiber was relatively lower than the α-fiber in the specific steel sample, which can have a strong effect on the available driving force for recovery and recrystallization. Hence other structural factors such as precipitation and/or solute drag might become more important in controlling the kinetic behavior of the steel during annealing.
Conditions for the Occurrence of Abnormal Grain Growth Studied by a 3 D Vertex Dynamics Model
Authors: Syha M. , Weygand D.
Published: April 2012

The conditions for the nucleation of abnormal grain growth were investigated using a three dimensional vertex dynamics model. Potentially abnormal growing grains characterized by their size and topological class, respectively and embedded in an isotropic grain ensemble were subjected to annealing varying their grain boundary properties. The simulation results indicate that the classical mean field approaches underestimate the role of the grain boundary energy advantage, while the impact of a mobility advantage is overestimated.
Recrystallization Kinetics and Texture Evolution during Annealing of Cold Rolled Fe-Mn-C Alloy
Authors: Lü Ya Ping , Molodov Dmitri A. , Gottstein Günter
Published: April 2012

The recrystallization behavior of 50% cold rolled Fe-22%Mn-0.376%C alloy during annealing at 560°C, 630°C and 700°C was investigated. Microhardness tests were applied for characterization of the recrystallization kinetics, X-ray diffraction and EBSD measurements were utilized to characterize the crystallographic texture and the grain microstructure. The obtained experimental data were evaluated in terms of the JMAK model. The obtained values of the Avrami exponent varied in the range between 0.70 and 1.37. The inhomogeneous grain microstructure after recrystallization is interpreted in terms of non-randomly distributed nuclei. Shear bands, lamellar lines intersecting with mechanical twins and grain boundaries with localized high misorientation gradients were identified to be preferential nucleation sites. No pronounced texture was observed after annealing at 630°C.
Annealing Behavior of Ferritic-Martensitic ODS-Eurofer Steel: Effect of Y2O3 Particles on Recrystallization
Authors: Sandim Hugo Ricardo Zschommler , Renzetti Reny Angela , de Oliveira Zimmermann Angelo José , Padilha Angelo Fernando , Möslang Anton
Published: April 2012

Reduced activation ferritic-martensitic steels are considered for future applications in fusion power plants. The thermal stability of two steels (ODS-Eurofer and Eurofer-97) was evaluated in cold-rolled samples annealed below 800°C. These grades have similar chemical compositions except for the presence of nanosized Y2O3particles in ODS-Eurofer steel. This nanosized dispersion is very effective to prevent recrystallization. On the other hand, full recrystallization occurs in Eurofer-97 steel when annealed above 700°C. The low volume fraction of recrystallized grains (< 0.1) in ODS-Eurofer steel annealed at 800°C can be explained by nucleation at prior grain boundaries and around large M23C6particles. Further growth of these nuclei is impeded by Zener drag and concurrent recovery. Static recovery is the main softening mechanism in the ODS-steel below 800°C.
Recrystallisation Behaviour of an Fe-Mn-C-Si-Al TWIP
Authors: Bracke Lieven , Cabañas-Poy Nieves
Published: April 2012

The static recrystallisation behaviour of cold rolled and annealed TWinning Induced Plasticity (TWIP) steels is important for its industrial production. The recrystallisation kinetics have been determined for an Fe-Mn-C-Si-Al TWIP steel using hardness measurements and microstructure analysis: it has been shown that recrystallisation progresses rapidly with increased annealing temperature. Recrystallisation was faster at higher cold reductions, and a smaller final grain size was observed at lower annealing temperatures. This indicates that the mechanism is nucleation dominated at lower temperatures; grain growth at higher temperatures appears similar for all reductions. The recrystallisation results in a crystallographic texture where the main components of the cold rolling texture are preserved in the final texture after annealing, although some randomisation was observed.
Recrystallisation Behaviour of Low Carbon Steel with and without Addition of Chromium
Authors: Gazder Azdiar A. , Bata Vladimir , Hazra Sujoy S. , Pereloma Elena V.
Published: April 2012

The effects of 0.74wt% Cr addition on the recrystallisation kinetics of low carbon (LC) steel was investigated using Vickers hardness testing, optical metallography and Electron Back-Scattering Diffraction (EBSD). Compared to the unalloyed steel, Cr addition significantly delays the time for recrystallisation and increases the JMAK pre-exponential factor (k) by an order of magnitude. During initial softening, EBSD returned similar orientations for nucleated and growing grain fractions in both steels. However with longer annealing times the micro-texture of recrystallised grains differs from their earlier counterparts. Overall, the effect of fine Cr carbides on grain boundary mobility in the LC-Cr steel causes variations in recrystallisation kinetics, grain morphology and micro-textures.
Nonlinear Migration of Faceted Boundaries and Nonstationary Grain Growth in Ceramics
Authors: Fisher John G. , Kang Suk Joong L.
Published: April 2012

Recent investigations suggest that general grain boundaries can be categorized into two types: rough (atomically disordered) and faceted (atomically ordered). This paper reports our recent investigations on the migration behaviour of faceted boundaries and its effect on grain growth in polycrystalline ceramics. A model experiment has been performed using bi-layer samples of polycrystals with different average grain sizes and single crystals of BaTiO3to study the migration behaviour of faceted boundaries. A non-linear relationship between grain boundary migration and the driving force for migration is revealed. Grain growth behaviour with respect to boundary faceting has also been studied in perovskites. The structural transition of boundaries between rough and faceted can be induced by changing oxygen partial pressure, adding dopants and changing temperature. The fraction of faceted boundaries was changed by changing oxygen partial pressure and donor doping. As the facet fraction decreased, the grain growth behaviour changed from stagnant and abnormal to normal. The different types of growth behaviour observed can be explained by the coupling effect of the maximum driving force for the boundary migration and the critical driving force for appreciable migration of faceted boundaries.
Studies on Softening Kinetics of Niobium Microalloyed Steel Using Stress Relaxation Technique
Authors: Miao Cheng Liang , Shang Cheng Jia , Zhang Guo Dong , Zhu Guo Hui , Zurob Hatem S. , Subramanian S.V.
Published: April 2012

Stress relaxation was studied in a series of low carbon, high Mn microalloyed steels containing 0.012, 0.06 and 0.1 wt% Nb. The stress-relaxation curves were modeled using a physically-based model that takes into account the time evolution of precipitation, recovery and recrystallization as well as their interactions. The results confirm that high Mn-high Nb design can offer distinct advantage over the low-Mn design for the application of near net shape processing.
3D Phase Field Simulation of Austenite Grain Growth in Microalloyed Linepipe Steel
Authors: Toloui Morteza , Militzer Matthias
Published: April 2012

Three dimensional (3D) phase field modelling is used to simulate austenite grain growth in X80 linepipe steel for thermal paths that are typical in the heat affected zone (HAZ). In the HAZ austenite grain growth is affected by pinning due to precipitates and their potential dissolution. Effective grain boundary mobilities are introduced that are consistent with strong pinning at lower temperatures and weak pinning at higher temperatures separated by the estimated dissolution temperature range of fine NbC precipitates. These mobility relationships are then used to describe austenite grain growth in bulk samples subjected to rapid heating and cooling conditions to replicate thermal cycles at various positions in the HAZ.
Magnetically Controlled Grain Growth in Cold Rolled Zinc
Authors: Günster Christoph , Molodov Dmitri A. , Gottstein Günter
Published: April 2012

The impact of a magnetic field on texture and microstructure evolution in Zn-1.1%Al was investigated. Specifically oriented cold rolled (85%) sheet specimens were annealed in a magnetic field of 17 Tesla at 340°C for 15, 30 and 90 minutes. X-ray diffraction and EBSD-measurements were utilized to characterize crystallographic texture and grain microstructure. The results confirmed that grain growth in magnetically anisotropic zinc can be substantially affected by a magnetic field. This manifested itself by significant changes in the development of the grain growth texture during magnetic annealing compared to annealing at zero field. The magnetically induced texture changes are caused by the generation of an additional magnetic driving force which arises from a difference in magnetic free energy density between differently oriented grains. The grain microstructure evolution was also essentially affected by a magnetic field such that grains with energetically favoured orientations grow faster and their fraction becomes larger, than that of grains with disfavoured orientations. The results will be also discussed with respect to the magnetically altered grain boundary character distribution.
Real-Space Analysis of Grain Boundary Fluctuations in Two Dimensional Colloidal Crystals
Authors: Skinner Thomas O.E. , Aarts Dirk G.A.L. , Dullens Roel P.A.
Published: April 2012

The characteristics of grain boundary motion and evolution are of fundamental importance in material science. Optical microscopy is used to analyse grain boundary fluctuations in two-dimensional colloidal crystals. Colloidal systems are particles (colloids) on the order of 1µm dispersed in a solvent where they display rich phase behaviour of colloidal 'crystal', liquid' and 'gas' phases. They are widely used as a model system to study many fundamental issues in condensed matter physics and statistical mechanics. The intrinsic slowness and increased length scales of colloidal systems make them an excellent model system to study grain boundaries as an analogy to atomic systems. Static and dynamic correlation functions are compared with capillary wave theory to calculate the grain boundary mobility and stiffness. These fundamental properties of grain boundaries determine the kinetics of curvature-driven grain growth.
Dynamic Recrystallization of Ferrite in a Low Carbon Steel with the (α+θ) Duplex Microstructures
Authors: Li Long Fei , Yang Wang Yue , Sun Zu Qing
Published: April 2012

Dynamic recrystallization (DRX) of ferrite in a low carbon steel with the (α+θ) duplex microstructures was investigated using hot compression tests in combination with SEM, TEM and EBSD, and the effect of the size of cementite particles was analyzed. The results indicated that during hot deformation of the low carbon steel DRX of ferrite took place and the increase in the average size of cementite particles was of benefit to DRX. The formation of DRX grains was attributed to particle stimulated nucleation (PSN), by the well development of the subgrain near cementite particles. At the beginning of hot deformation, DRX grains were mainly formed near cementite particles with the size of about 1μm or above. With the increase in the strain, such grains were also formed around pairs or groups of particles with the size of 0.5μm to 1μm.
Texture Formation by the Compression Deformation of AA5182 Aluminum Alloy at High Temperatures
Authors: Jeong Hyeon Mook , Okayasu Kazuto , Fukutomi Hiroshi
Published: April 2012

Texture formation of AA5182 for compressive deformation with a range of temperatures from 673K to 823K and strain rates from 5.0×10-4to 5.0×10-2s-1is experimentally investigated by EBSD technique and X-ray diffraction. Fiber textures are observed in all deformation conditions. Stress regions are divided into a low stress region (10~55MPa) and a high stress region (above 55MPa) on the basis of the relationship between stress and grain size. In the low stress region, it is found that the main component of the fiber texture is {001}(compression plane). In this case, the pole density at {001} is increased with increasing temperature at the same stress level. It is concluded that development of {001} component is attributed to grain boundary migration. For the high stress region, the main component of the fiber texture is {011}. It is considered that the formation of {011} component is attributed to the slip deformation by {111}<110> system.
Effect of Initial Grain Sizes on Strain Induced Boundary Migration
Authors: Natori Yoshiaki , Murakami Kenichi , Arai Satoshi , Kurosaki Yousuke , Mogi Hisashi , Homma Hotaka
Published: April 2012

Examination of the SIBM mechanism based on the dislocation substructure at the interior of the Goss oriented grain was carried out by changing the grain size prior to the temper rolling. The following results were obtained. 1) SIBM significantly increased Goss orientation during the eminent grain growth with the initial grain sizes from 18 to 55μm. 2) When the initial grain sizes were large, i.e. 37μm and 55μm, the rolling with the reduction beneath the critical value could not promote SIBM, even the normal grain growth could also be hindered. Consequently a proposal was made that the nucleation of the recovery appeared among substructure domains containing sluggish strain. There exists an adequate size of the domain which varies with the change both of the rolling reduction and the initial grain size.
Investigation of Deformed and Recrystallized Textures in Zirconium
Authors: Jedrychowski M. , Tarasiuk Jacek , Bacroix Brigitte , Wroński S. , Chaubet D.
Published: April 2012

The analysis of deformed and recrystallized zirconium, used in nuclear industry is presented. The main purpose of the present work is to describe and analyze changes in texture, microstructure and misorientation profile, which are observed during a complete thermomechanical treatment. Zirconium samples were channel compressed till various degrees of deformation. The samples were then annealed. In both deformed and recrystallized states, topological maps were measured using the well known EBSD (Electron Backscatter Diffraction) technique. The obtained data were necessary for further analysis which consisted of several approaches: quantification of textures, identification of principal components, volume fractions, misorientations, grain size and IQ histograms. For the misorientation analysis, several parameters have also been tested (ie. correlated misorientation profile, grain average misorientation, kernel, etc.). Based on this complete set of data a scenario is proposed to explain the observed microstructural evolutions.
Nucleation of Recrystallization in Mg Alloys during and after Hot Working
Authors: Barnett Matthew R. , Beer Aiden G.
Published: April 2012

Recrystallization nucleates at heterogeneities. The impact of this on local texture and stress-strain response in hot worked magnesium is considered in the present paper. Two aspects of bulge nucleation during dynamic recrystallization are considered.
The Influence of Subgrain Size on the Bainite Refinement for Steels
Authors: Wang Xue Min , Shang Cheng Jia , Yang S.W. , He Xin Lai
Published: April 2012

The relaxation-precipitation-controlling phase transformation (RPC) technique after deformation at non-recrystallization zone to refine the intermediate transformation microstructure has been simulated on a Gleeble-1500 thermo-simulator. The optical microscope, SEMTEMPTA(particle tracking autoradiography) technique to reveal the boron distribution were employed to study the variation of austenite grain size and subgrain size, the features of microstructure after RPC, precipitation and the evolution of dislocation configuration during the relaxation and the boron distribution. The results show that after relaxation at non-recrystallization zone, the subgrain formed inside an original austenite grain. With the relaxation time increasing, the size of the subgrains increased and the misorientation also increased. During the cooling after the relaxation the boron can also segregate at the boundaries of subgrains and the boron segregation can reveal the subgrains forming in deformed austenite before phase transformation. It has been found that during the relaxation strain induced precipitates occurs and these precipitates can pin the subgrain boundary and make it more stable. Comparing the subgrain size demonstrated by PTA with the optical microstructure a conclusion can be drawn that the packet of bainite generally cannot break through the boundaries of subgrains, so the subgrain appearing at the relaxation stage can confine the growth of the microstructure during the transformation in succeeding and the final bainite is refined.
Study on Resist Removal Using Electrolyzed Sulfuric Acid Solution in Comparison with SPM
Authors: Nagai Tatsuo , Yamakawa Haruyoshi , Uchida Minoru , Otsu Toru , Ikemiya Norihito , Morita Hiroshi
Published: April 2012

It is known that resist removal capability of SPM gradually deteriorates during the stripping process. The deterioration is theoretically explained to be the decrease in the concentration of sulfuric acid. On the contrary, in the case of electrolyzed sulfuric acid method, both concentrations of sulfuric acid and of peroxodisulfuric acid produced by electrolysis are kept constant, so that the resist removal capability is maintained for a long term even without addition of hydrogen peroxide. It is proved that resist patterned on φ300mm wafers and implanted at 1E14 atoms/cm2 can be removed using electrolyzed sulfuric acid solution without ashing process.
Using the Background Signal of a Light Scattering Tool for I/I Photo Resist Strip Optimization and Monitoring
Authors: Halder Sandip , Vos Rita , Wada Masayuki , Claes Martine , Kenis Karine , Mertens Paul W. , Dighe Prasanna , Radovanovic Sanda , Simpson Gavin , Sonnemans Roger
Published: April 2012

With the continuous decrease of feature size of semiconductor devices new process related challenges must be overcome continuously. One of the key issues for technology development is to have the proper metrology in place to evaluate the myriad process steps fast and accurately. Sometimes the mere existence of a particular metrology is not enough because of cost and throughput issues. The goal of this paper is to show that simply by monitoring the background signal of a light scattering tool, certain process optimizations and monitoring can be done much faster while bringing down the cost significantly. We focus particularly on post I/I strip optimization in this paper.
Wafer Edge Bead Cleaning with Laser Radiation and Reactive Gas
Authors: Elliott David J. , Chaplick Victoria M. , Degenkolb Eugene , Harte Kenneth , Millman Jr. Ronald P.
Published: April 2012

The purpose of this study is to investigate and optimize the process parameters for cleaning the top, bottom, and apex edges of silicon wafers using laser radiation and reactive gas. A secondary purpose is to conduct photoresist edge bead and post-etch polymer film removal (EBR) experiments to determine the minimum controllable edge exclusion in EBR processing to improve die yield. [ An overall purpose is to identify a robust and environmentally sound process for wafer edge cleaning and a hardware configuration (stand alone or track integrated) that can be cost effectively produced for device manufacturing.
Effects of Target Compliance on a High-Speed Droplet Impact
Authors: Sanada Toshiyuki , Ando Keita , Colonius Tim
Published: April 2012

High speed spray cleaning which utilize droplets impact has been used for removing contaminants from wafer surface. When a droplet impacts a solid surface at high speed, the contact periphery expands very quickly and liquid compressibility plays an important role in the initial dynamics and the formation of lateral jets. Impact results in high pressures that can clean or damage the surface. In this study, we numerically investigated a high speed droplet impacts on a solid wall. In order to compare the available theory and experiments, 1D, 2D and axisymmetric solutions are obtained. The generated pressures, shock speeds, and the lateral jetting mechanism are investigated; especially the effect of target compliance is focused.
Order Estimation of Physical Processes in Dynamics of Steam-Water Mixed Spray Cleaning Technique
Authors: Watanabe Masao , Sanada Toshiyuki , Mashiko Takashi , Hayashida Atsushi
Published: April 2012

We have been developing an innovative ultra-low environmental load cleaning technique by the use of steam-water mixed spray. We showed that this technique is quite effective in both cleaning and photo-resist stripping. We also found that the physical force associated with steam-water mixed spray is greater than that with air-water mixed spray; hence we proposed that the condensation plays an important role in this cleaning technique. In order to discuss further this mechanism, we perform the order estimation of physical processes in dynamics of liquid droplet moving in vapor flow impacting on a solid interface in this study. Results show that droplet impact velocity can be reduced while the droplet approaches to the solid surface. However, the vapor in the gap can condensate to either the liquid droplet or the solid surface with the velocity whose order of magnitude cannot be negligible compared to the impact velocity; hence the amount of vapor that should be pushed out from gap can be drastically reduced, This condensation results in the significant reduction of viscous force. This reduction of force with the existence of condensation reduces the impact velocity deceleration. Consequently significantly large impact pressure is generated.
Uniformity of Particle Removal by Aerosol Spray
Authors: Xu Xiu Mei , Pacco Antoine , Wada Masayuki , Leunissen Leonardus , Struyf Herbert , Mertens Paul W.
Published: April 2012

In this work the dynamics of particle removal by aerosol spray is investigated. Local dwell time of spray cleaning is calculated numerically from the process conditions, and some striking topological similarities between the particle removal efficiency and dwell time profiles are observed. The particle removal rates, defined as the normalized speed of particle removal, are not constant during a typical process, with the highest removal rate for the first tens of milliseconds and a temporal decay as time elapses. Increasing N2flow rate results in an enhancement in both the particle removal efficiency and the particle removal rate.
The Influence of the Angle of Incidence in Megasonic Cleaning
Authors: Brems Steven , Hauptmann Marc , Camerotto Elisabeth , Xu Xiu Mei , De Gendt Stefan , Heyns Marc M. , Mertens Paul W.
Published: April 2012

The megasonic cleaning efficiency is evaluated as a function of the angle of incidence of acoustic waves on a Si wafer. Acoustic Schlichting streaming alone is not able to remove nanoparticles smaller than 400 nm. It is shown that oscillating or collapsing behavior of bubbles are responsible for removing nanoparticles smaller than 400 nm during a cleaning process with ultrasound. Optimal particle removal efficiency is obtained around the angle of acoustic transmission of the silicon wafer.
Simultaneous Removal of Particles from Front and Back Sides by a Single Wafer Backside Megasonic System
Authors: Park Chan Geun , Sohn Hong Seong
Published: April 2012

In IC manufacturing, particle removal from a wafer's back side (BS) has become as important as that from the front side (FS). For example, during lithography, BS particles can cause a variation on the topside surface topography. This may result in a focus-spot failure due to the reduced process window for depth of focus (DOF) as shown in Fig. 1. This problem increases as the feature size decreases. BS particles may cause other problems in wet benches, where BS particles can be transferred to the adjacent front side of wafers. Fig. 2 shows these FS particles, which usually appear as flow or streak patterns on the wafer [.
The Importance of Cavitation Hysteresis in Megasonic Cleaning
Authors: Camerotto Elisabeth , de Gendt Stefan , Hauptmann Marc , Shamiryan Denis , Heyns Marc M. , Mertens Paul W. , Brems Steven
Published: April 2012

An improved fundamental understanding of the megasonic cleaning process is necessary to optimize cleaning efficiency and minimize the unwanted damage to fragile structures. Argon sonoluminescence (SL) measurements are done to achieve an improved insight in the collapse threshold and behavior of microbubbles. This paper reports on acoustic cavitation by means of Ar Sonoluminescence (SL) investigation achieved with a dedicated test cell, a photomultiplier tube (PMT) and a gasification system. The results show an increase in SL signal as a function of the applied acoustic power density. An increase in Ar concentration results in a decrease in SL signal. Furthermore, a clear hysteretic behavior in the SL signal is identified when ramping the acoustic power up and down. This hysteresis effect can be attributed to the nucleation of bubbles during the increasing branch of the power loop. Finally the time evolution of SL light after the switching on of the acoustic transducers revealed the existence of a delay time.
Development of a Megasonic System for Cleaning Flat Panel Display
Authors: Kim Hyun Se , Lee Yang Lae , Lim Eui Su , Elimelech Menachem
Published: April 2012

When fabricating flat panel displays (FPDs), cleaning process is important in the preparation of next steps. A megasonic system for cleaning FPD which can remove smaller particles with lower power and lower consumptions of chemical and UPW was designed and manufactured. The anti-resonance frequency of the lead zirconate titanate (PZT) actuator was measured, and the value was 992 kHz. The impedance graph of the cleaning system was analyzed using commercial finite element method (FEM) analysis software Ansys, and the obtained value was 992 kHz. This agreed well with the measured value of 989 kHz. The performance of the developed system was evaluated by comparing the acoustic pressures with the conventional product. As a result, the acoustic pressures of the developed system were three times larger than that of the commercial system (conventional type: 13.9 kPa, the developed one: 43.1 kPa). In addtion, the PRE test was performed and the 83% particles were removed using 64% reduced power and 80% reduced chemical consumptions.
Influence of Photoresist and BARC Selection on the Efficiency of a Post-Etch Wet Strip in BEOL Applications
Authors: Kesters Els , Lux Marcel , Pittevils Joris , Baeyens Jonas , Vereecke Guy , Baerts Christina , Shamiryan Denis , Struyf Herbert
Published: April 2012

All-wet processes are gaining a renewed interest for the removal of post-etch photoresist (PR) and Bottom AntiReflective Coating (BARC) in the back-end-of-line (BEOL) semiconductor manufacturing, as plasma ash, traditionally used to remove the PR and BARC layer after etch, cause damage to the low-k dielectric. This study investigates the modification of 193 nm post-etch PR and BARC layer by UV irradiation, that can be used as an intermediate step to enhance PR and BARC wet strip by O3/H2O.
Aqueous Fluoride Residue Removers for 32 nm and beyond Copper Ultra Low-κ Technologies
Authors: Westwood Glen , Pigliucci Anatolio , Oszinda Thomas , Leppack Susanne , Schaller Matthias
Published: April 2012

Mallinckrodt Baker, Inc. (MBI) has developed an aqueous fluoride-based cleaner (AFC1) that shows improved ultra-low k (ULK) and cobalt tungsten phosphide (CoWP) compatibility over dilute hydrofluoric acid (dHF) and a simple solvent based cleaner (SFC1). Performance and compatibility testing was performed with beaker tests at MBI and on 45 nm wafers by GLOBALFOUNDRIES. Our results indicate that AFC1 may be a good alternative to dHF for future Cu technologies.
Ultra-Fast In-Line Inspection for 3D SIC TSV Line - Bonding & Thinning
Authors: Guittet Pierre Yves , Markwort Lars , Savage Greg , Halder Sandip , Jourdain Anne
Published: April 2012

The number of consumer products requiring 3D stacked IC (3D SIC) is growing, and volume output is expected to start between 2011 and 2013. R&D centers and production sites are addressing the remaining obstacles to production for these new technologies. To enable fast production ramp, there is urgency to get enablers in place, including advanced, dedicated process control methods. Using an innovative high throughput inspection technology, we show ways to control future 3D SIC production lines, getting data from 100% of the wafers and providing defect classification for yield management.
High Efficiency Single Wafer Cleaning for Wafer Bonding-Based 3D Integration Applications
Authors: Dussault Don , Fournel F. , Dragoi V.
Published: April 2012

Current work describes development, testing and verification of a single wafer megasonic cleaning method utilizing a transducer design that meets the extreme particle neutrality, Particle Removal Efficiency (PRE), and repeatability requirements of production scale wafer bonding and other applications requiring extremely low particle levels.
Wet Chemical Cleaning of InP and InGaAs
Authors: Vos Rita , Arnauts Sophia , Conard Thierry , Moussa Alain , Struyf Herbert , Mertens Paul W.
Published: April 2012

In this work, the compatibility of InP and InGaAs in cleaning solutions commonly used in semiconductor manufacturing is investigated. Aqueous oxidizing cleans should be avoided as the substrates dissolve rapidly. Low pH solutions may impose some serious ES&H issues due to hydride evolution occurring upon acidic hydrolysis of the III-V material. However, acidic solutions are very efficient to remove the native oxide from the substrate. Complete oxide free surfaces are not achieved after wet cleaning due to the rapid oxidation of these materials in the atmosphere.
Yield Impact of Backside Metal-Ion Contamination
Authors: Carey Stephen , Knotter D. Martin , Ooms Eric , Boersma Johannes , van der Sar Elfried , Cop Robbert , Gerritzen Wim , van Zadelhoff Hans , Bouma Henk
Published: April 2012

Small amounts (~1010 atms of Fe) of metal-ion contamination remains on local spots on the backside of the wafer. During a thermal process step, 30% of this contamination is transferred to the front side of the wafer where it causes in some specific cases substrate degradation. The source of the contamination is stainless-steel wafer pins that are used in wafer handling on for example litho tracks. This contamination is printed onto the backside wafer surface where two cleaning steps were not able to remove it. Figure 1. Wafer test: 3 clusters of devices failing due to the tripod signal.
Assessment of a FOUP Conditioning Equipment for Advanced Semiconductor Application
Authors: Otto Michael , Rioufrays Sylvain , Favre Arnaud , Leibold Andreas , Altmann Roswitha , Gennaro S. , Dell'Anna R. , Canteri R. , Pfitzner Lothar
Published: April 2012

The effectiveness of a FOUP (Front Opening Unified Pod) conditioning test bench was tested with respect to the reduction of outgassing materials from FOUP materials and cleanroom compatibility. The equipment uses vacuum and heat to reduce volatile organic compounds from construction material and wafers. Five different analysis methods were used to asses the performance of the equipment with respect to organic, ionic and metal contamination. The experiments showed that the use of heat and vacuum has a positive effect on the organic contamination from FOUPs, and that the equipment is suitable for semiconductor applications in cleanroom environments.
Photovoltaics: The Renewable Energy Revolution Leading the Semiconductor Industry
Authors: Verlinden Pierre J.
Published: April 2012

The photovoltaic industry has maintained a rapid growth rate of more than 46% over the last 15 years. At the same time, the price of PV modules have continuously decreased to a point where PV is now at grid parity on the customer side of the meter in geographic areas with high incentives combined with high solar irradiation or high electricity price. The rapid growth rate of the PV industry is expected to continue and even accelerate as the regions with grid parity spread to more parts of the developed world. This is due to a combined reduction in the price of PV modules and an increase in the price electricity. Among all the different PV technologies, crystalline silicon solar cells have maintained a strong dominance of more than 82.5%. Thanks to extensive studies of silicon material properties, mechanisms of carrier recombination and the development of ultra-clean processing, the efficiency of silicon solar cells have reached more than 22% in large volume production and 25% in laboratory, and is approaching the theoretical maximum efficiency of silicon cells of about 29%.
Two-In-One Texturing and Polishing in One Solution
Authors: Prajapati Victor , John Joachim , Poortmans Jef , Mertens Robert P.
Published: April 2012

Texturing and polishing crystalline silicon in the PV industry are both time consuming and inefficient, the need for a streamlined solution is prevalent. To obtain high conversion efficiency surface decoupling is needed, one side0 of the wafer is ideally textured while the other is completely polished. The standard industrial process results in a total silicon loss of 40μm and a complete surface decoupling cycle time in the order of an hour from an as cut until diffusion ready. For an industrial wafer thickness of 180μm more than 20% of the silicon is lost. In addition to silicon loss, there are multiple wet processing steps needed for decoupling which are time consuming and hinder the high throughput manufacturing needed to achieve the ultimate goal of a low per watt peak price. The technique is proposed in this paper decouples the front and rear surfaces and utilizes in only one wet process step for both texturing and polishing. This process simplification leads to significant savings by decreasing costly cycle time, saving consumables and reducing the amount of silicon loss.
Surface Passivation for Si Solar Cells: A Combination of Advanced Surface Cleaning and Thermal Atomic Layer Deposition of Al2O3
Authors: Vermang Bart , Rothschild Aude , Kenis Karine , Wostyn Kurt , Bearda Twan , Racz A. , Loozen X. , John Joachim , Mertens Paul W. , Poortmans Jef , Mertens Robert P.
Published: April 2012

Thermal atomic layer deposition (ALD) of Al2O3 provides an adequate level of surface passivation for both p-type and n-type Si solar cells. To obtain the most qualitative and uniform surface passivation advanced cleaning development is required. The studied pre-deposition treatments include an HF (Si-H) or oxidizing (Si-OH) last step and finish with simple hot-air drying or more sophisticated Marangoni drying. To examine the quality and uniformity of surface passivation - after cleaning and Al2O3 deposition - carrier density imaging (CDI) and quasi-steady-state photo-conductance (QSSPC) are applied. A hydrophilic surface clean that leads to improved surface passivation level is found. Si-H starting surfaces lead to equivalent passivation quality but worse passivation uniformity. The hydrophilic surface clean is preferred because it is thermodynamically stable, enables higher and more uniform ALD growth and consequently exhibits better surface passivation uniformity.
Effect of Wet Cleanings on GST Surface: XPS Characterization
Authors: Votta Annamaria , Pipia Francesco , Ravizza Enrica , Spadoni Simona , Rossini Silvia , Brattico Lucilla , Alessandri Mauro
Published: April 2012

GST is an alloy composed by Ge, Sb, Te whose importance is increasing more and more in semiconductors manufacturing due to its usage in Phase Change Memories (PCM) architecture, as a charge storage element. As a consequence its integration in PCM architectures requires a deeper understanding of the effect that commonly used wet cleanings may have on the surface of the alloy.
Poly-Silicon Wet Removal for Replacement Gate Integration Scheme: Impact of Process Parameters on the Removal Rate
Authors: Sebaai Farid , Veloso Anabela , Claes Martine , Devriendt Katia , Brus Stephan , Absil Philippe , Mertens Paul W. , De Gendt Stefan
Published: April 2012

We report in this work some process optimization effort in performing poly silicon removal for replacement gate process integration. Successful wet poly silicon removal after dummy gate patterning is not only conditioned by suitable process conditions during wet removal but is also impacted by process steps prior to gate removal A thorough evaluation of the impact on poly removal from dopants or contaminants introduced in the poly silicon by previous processing is done, resulting in an optimized integration flow with successful poly removal. This work also shows that use of diluted TMAH chemistry instead of diluted ammonia in performing poly silicon removal provides better ability in removing poly silicon especially in narrow gate structures.
A Hybrid Dry-Wet Approach for Removal of a Dummy Polysilicon Gate in a Replacement Metal Gate Scheme
Authors: Hwang Guang Yaw , Liao J.H. , Tzou S.F. , Lin Mark , Yeh Autumn , Lou David , Chen Eason , Huang Weien , Kamarthy Gowri , Xu Kai Dong , Athayde Amulya
Published: April 2012

Beginning at the 45nm node, the semiconductor industry is moving to high-k gate dielectrics and metal gate electrodes for CMOS logic devices [. Although different approaches of building these devices are being pursued, most of the industry has consolidated behind a gate last approach, in which the transistor is built around a dummy poly polysilicon gate, which is subsequently removed and replaced with a metal gate. Current approaches to removing the dummy poly gate include plasma-based dry processes and liquid-phase wet etching.
Investigation of Wet Clean Induced Dielectric Surface Static Charge and its Impact on Gate Oxide Integrity
Authors: Lin Shun Wu , Chang Vincent S. , Yeh Matt , Houyang Eric
Published: April 2012

The static electricity of wet clean was characterized by contactless surface voltage measurement on silicon oxide dielectric in this study. The paper shows surface static charge at wafer center caused by a single wafer spin cleaning tool. Deionized water (DIW) rinse was verified as the critical step of inducing static charge. It was demonstrated by metal oxide semiconductor (MOS) capacitor that such serious dielectric static charge would degrade gate oxide integrity (GOI). With dissolved CO2to lower DIW resistance, surface static charge at wafer center is reduced and degraded GOI is restored as a result.
Effect of Drying Liquid on Stiction of High Aspect Ratio Structures
Authors: Kim Gyu Hyun , Cho Sung Hyuk , Han Ji Hye , Lee Young Bang , Roh Chi Hyeong , Hong Kwon , Park Sung Ki
Published: April 2012

In this paper, we studied stiction behavior of HAR pattern (line and space pattern) dependence on adhesion force with surface tension of drying liquid and surface contact angle. Surface tension effect was evaluated with various drying liquids such as IPA, ethanol and HFE (hydrofluoroether) chemical. Patterns treated by dHF, APM and surface modifier were introduced to investigate dependence of pattern collapse on contact angle. The high temperature D.I. water rinse followed by high temperatures drying using liquid with low surface tension was a most effective. Furthermore, surface modification method using HMDS (hexamethyldisilazane) chemical was also effective.
Non-Oxidizing Solvent-Based Strip of Ion Implanted Photoresist
Authors: Tsvetanova Diana , Vos Rita , Vanstreels K. , Radisic D. , Sonnemans R. , Berry III Ivan , Waldfried Carlo , Mattson David , de Luca J. , Vereecke Guy , Mertens Paul W. , Parac-Vogt T.N. , Heyns Marc M.
Published: April 2012

The removal of ion implanted photoresist (II-PR) after implantation of ultra shallow extension and halo regions is considered as one of the most challenging front-end-of-line (FEOL) processing steps for 32nm and beyond CMOS technology nodes. Commonly used resist strip processes such as fluorine-based dry plasma ash and hot sulfuric/peroxide mixtures induce unacceptable levels of oxidation and material loss [1-.
Bibliographic and physical organization of non-print materials: with special reference to Sri Lankan special libraries
Authors: Wijayaratne Anusha
Published: April 2012

Non-print materials are formats with special characteristics are need to be discussed in terms of bibliographic control and access but often overlooked An ever-increasing amount of information - covering educational and recreational interests - is being produced in a wide range of Non-print formats. As librarians our duty is to provide free and open access to all information regardless of format in which they are stored. This paper, which is based on a research titled ‘Organizing practices of non-print materials for access in special libraries of Sri Lanka', provides an overview of the availability of nonprint materials and situation of bibliographic and physical organization of non-print collections together with the librarians' attitudes towards media resources. DOI: http://dx.doi.org/10.4038/sllim.v1i2.433 Sri Lanka Journal of Librarianship & Information Management volume1, No.2 pp.69-81 The full text of this article is available on the NILIS website.