bluuebunny/crossref_metadata_2025 huggingface dataset:
Forming of Biocompatible Materials in the Semi-Solid State
Authors: Kertész Levente , Liewald Mathias
Published: March 2009

Semi-solid processing of materials provides advantages of both forging and casting. Experiments
with high-melting and biocompatible alloys aiming at a “near-net-shape” production technology
recently have been conducted. Advanced trials showed, that processing of such materials by
means of semi-solid forming deliver a huge potential for feasible workpiece shapes and drastically
reduces machining time and subsequent surface treatment efforts.
In contrast to semi-solid forming of aluminium alloys at relatively low temperature levels any processing
of high-melting point alloys in the semi-solid state is much more challenging due to higher
forming temperature. Commonly used tool materials provoke high wear rates due to wetting, bonding
and melting processes which finally result in a very short tool life time. Thus, more apt materials
and composites for forming tools and dies which can withstand corrosion, wear, tear and extreme
changes in temperatures have to be found. The development of new design concepts for long-living
close-to-production tools based on such new materials will be a future goal.
Study of SiCp/AZ61 Composites
Authors: Yan Hong , Lingli Shi Bao , Pan Wei
Published: March 2009

SiCp/AZ61 composites were fabricated by a semi-solid stirring method. The effects of
volume fraction of SiC particles, stirring temperature and stirring time on the mechanical properties
of SiCp/AZ61composites were studied with an orthogonal experimental method. The results
indicate that volume fraction of SiC particles has a remarkable influence on the mechanical
properties of SiCp/AZ61 composites, the second were stirring time and stirring temperature. In this
experiment condition, the optimum technological parameters of SiCp/AZ61 composites fabricated
by semi-solid stirring method were volume fraction of SiC particles 6%, stirring temperature 595°C
and stirring time 5 min. Fractographies show that the fracture morphology of SiCp/AZ61
composites with volume fraction of SiC particles 6% is brittle.
A Control of Microstructure of A356 Alloy by Sequential Semi-Solid Process
Authors: Lim Sung Chul , Lee Hai Joong , Kang Jang Won , Lee Sang Kil , Kim Kyung Hoon , Lee Hyo Soo , Kwon Hyouk Chon
Published: March 2009

The study on rheocasting has been conducted based on examination for destruction, growth,
ripening of solid state in accordance with various changes in cooling. And flow characteristics of
slurry for high liquid range rather than practical use has gotten attention. However, the characteristics
of existing rheocasting and thixocasting are better mechanical property than competing process die
casting but it’s competitiveness as automotive or electric electronic parts which cost of product is
important. And productivity also has been decreased. Because die-casting techniques has been
advanced such as vacuum, mold auto temperature control etc. Most of the work reported at this
conference concerned the semi-solid processing of low melting point alloys, and in particular light
alloys of aluminum and magnesium. Therefore, the aim of this study is to devise the original strength
of semi-solid process by sequential semi-solid process. The size of primary solid particle and the
degree of sphericity as a function of the variation in cooling rate, stirring speed, and holding time were
observed. By applying electromagnetic stirring, primary solid particles became finer and rounder
relative to as-cast sample. With this background, this research conducted electromagnetic stirring
through slurry deliverance of sequential process through A356 alloy electromagnetic stirring pump
(30Hz, 130A) with Sequential Semi-Solid Process device to assess the microstructures, primary
particle size, degree of sphericity change in A356 alloy in accordance of solid-fraction, stirring speed,
and stirring maintenance time.
Characterization of Mushy Zone of ZWx2 (x=2, 4, 6) Magnesium Alloys
Authors: Huang Z.H. , Chen Rongshi , Han En-Hou
Published: March 2009

The potentials of Mg-Al system alloys for semi-solid forming have been extensively
evaluated these years. In the present studies, mushy zone properties of the Mg-Zn system alloys, i.e.
ZWx2 (x=2, 4, 6), are characterized and analyzed by using cooling curve thermal analysis method and
continuous torque measurement technique. The results show that Tn1 (first characteristic temperature
of primary crystal nucleation), Tn2 (second characteristic temperature of primary crystal nucleation)
and Tch (temperature of dendritic coherency) decrease with the increasing of zinc content, and the
temperature difference of (Tn1-Tn2) almost remains constant, while the temperature difference of
(Tn2-Tch) changes dramatically when Zn content increases to 6wt.%; The results also show that the fs-cc
(solid fraction of dendritic coherency) of ZWx2 alloys ranges from 0.4 to 0.51 while ZW22 and
ZW62 alloys having higher fs-ch and ZW42 alloy having the lowest fs-ch; also, strength of alloys in
mushy zone does not develop until a certain fraction solid( corresponding to the dendrite coherency
point) is reached. The results obtained by cooling curve thermal analysis method and continuous
torque measurement techniques are comparable to each other.
Numerical Modeling of Die Filling of Semi-Solid A356 Aluminum Alloy
Authors: Foroughi A. , Aashuri Hossein , Narimannezhad A. , Khosravani Ali , Kiani M.
Published: March 2009

Computer base and simulation technique have been applied for modeling the semi-solid
die filling and part of the solidification process of aluminum A356 alloy. A fairly simple one-phase
rheological model has been implemented into a fluid flow finite element software Procast, to solve
the partial differential equations. This model is purely viscous nature and is implemented in the
power law cut-off model of Procast. The constitutive parameters of this model were determined for
a rheocast A356 alloy. Using these parameters and comparing the simulation results with
experimental data showed good correlation with the model prediction. The designed die for
rheocasting was applied for the production of a small propeller with thin section.
Process Window Determination for Thixoextrusion Processes Using a Steel Alloy
Authors: Knauf Frederik , Baadjou René , Hirt Gerhard
Published: March 2009

A direct semi-solid bar extrusion process is characterised by inserting a feed stock in a
container and extruding through a forming die with a punch. Compared to conventional bar
extrusion the use of semi-solid material complicates the process due to the requirement of
solidification of the material. To achieve the solidification of the semi-solid bar, different basic tool
concepts are presented. With a combination of these concepts experiments were carried out using
the steel alloy X210CrW12 to detect the influence of the most influencing parameters press
velocity, extrusion channel diameter, length and geometry. Numerical simulations enable a better
understanding of the process mechanics like temperature development in the billet and forming die
as well as the material flow in the deformation zone.
Numerical Simulation of Semi-Solid Roll Strip-Casting Process for AZ91D Magnesium Alloy
Authors: Du Zhi Ming , Xie Shui Sheng , Wu Ping , Zhang Yan Ying
Published: March 2009

High quality magnesium alloy sheets with non-dendritic microstructure can be
manufactured by the technique which incorporates semi-solid processing with continuous roll stripcasting.
In particular, the process is believed to be cost-effective in mass production of magnesium
sheet products. The processing parameters, such as roll speed and temperature, have significant
influence on roll strip-casting process. In this paper, the commercial software, DEFORM-3D, for
deformation simulation of bulk materials was used to carry out the simulation of roll strip-casting
process for AZ91D magnesium alloy in semi-solid state, and the distribution of equivalent stress,
equivalent strain and temperature was obtained. Based on the results, the optimization of processing
parameters was discussed.
Deformation Behavior of Aluminum Alloy during Semi-Solid Compression
Authors: Du Zhi Ming , Zhang Xiao Hua , Wang Qiong , Luo Shou Jing
Published: March 2009

By semi-solid aluminum alloy compression test, deformation mechanism of semi-solid
aluminum alloy was investigated, the thixotropic strength existing in semi-solid aluminum alloy was
verified and the influences of temperature and strain rate on the deformation mechanism and
thixotropic strength were discussed. The results show that there are 4 stages in the process of
compression deformation for semi-solid aluminum alloy: stress swift growth stage, stress drop stage,
steady stress stage and stress gradual growth stage. The semi-solid billet has a thixotropic strength,
which is sensitive to temperature and strain rate. The higher the temperature or the higher the strain
rate is, the smaller the thixotropic strength of the semi-solid alloy.
Study on Thixo-Extrusion of Semi-Solid Aluminium
Authors: Neag Adriana , Favier Véronique , Bigot Régis , Frunză Dan
Published: March 2009

Thixo-extrusion processing could become an important technique to extend the range and
complexity of extruded profiles. This work presents the results of thixo-extrusion process applied
on aluminium alloy and they were carried out with both computer numerical simulation and
experimental methods. The thixo-extrusion set-up was made. Backward extrusion tests were
particularly studied and simulated using Forge 2005 software. The constitutive equation used for
these simulations is based on a micro-macro model for the semi-solid evolution. The constitutive
equation parameters were identified due to comparisons of the simulated load-displacement
responses with experimental ones for backward extrusion tests on 7075 semi-solid aluminium alloy,
for different temperatures.
Simulation of Temperature Field during Semi-Solid Magnesium Alloy Produced by Casting-Rolling Technology
Authors: Zhang Song Yang , Geng Mao Peng , Xie Shui Sheng
Published: March 2009

The temperature fields during semi-solid magnesium alloy produced by casting-rolling
technology has been simulated by finite element method on the basis of ANSYS. The temperature
fields for different conditions were obtained, which is consistent with the experimental results.
Results show that there is a high temperature field in the casting and rolling zone. The temperature
fluctuates from the center to edge of the strip near the entry of the casting and rolling zone. but The
temperature decreases gradually from the center to edge of the strip near the exit of the casting and
rolling zone. There are some remarkable effects of the temperature of the casting and rolling, the
velocity of the casting and rolling, the gap of two roll, the cooling of the roll and the diameter of the
roll on the temperature field, which are in agreement with the experimental results.
Study on Thixo-Forging of AZ61 Wrought Magnesium Alloy
Authors: Yan Hong , Zhou Bing Feng , Pan Wei
Published: March 2009

The semi-solid AZ61 wrought magnesium alloy was fabricated by mechanical stirring
method. Thixo-forging set-up were designed and made. The traditional forging and thixo-forging
processes of AZ61 magnesium alloy were studied with both computer numerical simulation and
experimental methods. The constitutive model of semi-solid AZ61 alloy was established in our prior
literature. The differences between traditional forging and thixo-forging processes were analyzed.
Results indicated that smaller load and uniform strain & stress were acquired in thixo-extrusion
process. Simulation results were good agreement with experimental ones.
Development of Adapted Heat Treatments for Steels out of the Semi-Solid State after Thixoforming
Authors: Dziallach Sebastian , Püttgen Wolfgang , Bleck Wolfgang
Published: March 2009

The process of thixoforming incorporates a series of forming processes in the semi-solid
state, which can be categorized between the conventional processes of forging and casting and
combines the advantages of these processes. Thixoforming of steels in the semi-solid state, requires
round, solid particles (globulites) in a liquid matrix which is deformed with low forming forces. In
order to achieve laminar material flow and to produce segregation-free components, the material
must fulfil diverse criteria. First, the melting interval should be as large as possible for an easy
temperature regulation. Next, low solidus and liquidus temperatures are advantageous regarding
tool loading. Additionally, thixoformable steels should show a melting behaviour that is finegrained
and globular. Furthermore, these steels should possess low contents of intraglobular liquid
phase fractions.
This paper gives a survey of the current state of steel Thixoforming and deals with the development
of adaptive heat treatment strategies. Regarding the structure formation and the development of
suitable heat treatment strategies, the once semi-solid state yields new structures that can be applied
in ways not previously possible with conventional hardening processes. New microstructures and
up to date unknown better mechanical properties can be adjusted with an optimised heat treatment
strategy. By this, new fields of application for thixo-materials can be entered and also advanced
procedures for special applications can be established. For example the steel X210CrW12 leads to a
very hard material with high wear-resistance, which can be used at higher temperatures than the
conventional hardened material. In general, new generic microstructures after thixoforming results
in unexpected favourable mechanical properties. Problems arise with respect to segregation and
pores which resulting in inhomogeneous property distributions.
Steel Thixoforging: Heat Exchange Impact on the Mechanical and Metallurgical Features of Thixoforged Samples
Authors: Becker Eric , Cezard Pierre , Bigot Régis , Langlois Laurent , Favier Véronique , Pierret Jean Christophe
Published: March 2009

Steel thixoforging process combines the advantages of performing parts having highly
complex shapes and good mechanical properties. These advantages result from the shear thinning
flow behaviour of semi-solids due to microstructure changes during the material deformation. Many
parameters such as steel grade, raw speed, slug temperature, tool temperature influence the steel
thixoforging process. In this work, we are interested in analysing the influence of thermal
conditions as well as ram speed on the flow behaviour and the microstructure of the final parts. To
do so, thixo-extrusion tests on a high speed hydraulic press were performed on C38 steels using
different ram speeds and different temperatures for the tools. The temperature is measured in the die
close to the tool-material interface during the whole process. Correlations between the temperature
measurements, the flow profile and the microstructure are discussed. Using the Finite Element code
Forge2005, these thixo-extrusion tests are simulated. Using an inverse method, some parameters
used in the thermal exchange modelling are identified by successive comparisons between
calculated and measured temperatures within the die.
Influence of Parameters during Induction Heating Cycle of 7075 Aluminium Alloys with RAP Process
Authors: Vaneetveld G. , Rassili Ahmed , Atkinson H.V.
Published: March 2009

Thixoforging involves shaping alloys with a globular microstructure in the semi-solid
state. To reach this kind of material, the Recrystallisation and Partial Melting (RAP) process can be
used to obtain a globular microstructure from extruded material with liquid penetrating the
recrystallised boundaries. Induction heating is used to apply the RAP process to slugs. One of the
benefits of using this method of heating is the fast heating rate (20°C/s). This paper will help to
improve heating parameters by showing their influence on 7075 aluminium alloy recrystallisation.
These parameters are the heating rate; heating frequencies-power; presence or not of protective gas;
position of the slug in the inductor; energy stored inside the slug; oxide layer on the slug side;
chamfer of the slug upper corner.
Basic Study on Thixo-Co-Extrusion of Multi-Layer Tube with Al/Mg Alloys
Authors: Wang Kai Kun , Zhang Peng , Du Yan Mei , Pan Zeng , Li Hong Gao
Published: March 2009

Thixo-forming is in the forefront of metal processing technology in the 21st century. The
research on thixo-co-extrusion of multi-layer tube as extension and development of the semi-solid
forming technology is a completely new processing method for the composite material forming and
is of great significance, in which different semi-solid billets (slurries) are extruded at the same time
to form multi-layer tubes. In this study, different sizes of column-shaped and ring-shaped billets of
Al/Mg alloys were firstly prepared by using specially designed molds. Then they were reheated by
electric-resistance furnace，microstructures from different heating laws were investigated. Lastly,
FEM simulation on thixo-co-extrusion of double-layer tube with A356/AZ91 was conducted.
Fabrication of Rheological Material of A356 Aluminum Alloy by Electromagnetic Stirring through Vacuum Pump
Authors: Kim H.H. , Lee S.M. , Kang C.G.
Published: March 2009

This study demonstrates fabricating rheological material by EMS system attached
vacuum pump, in order to improve mechanical properties of rheoforged products by removing
defects such as porosity and oxides arising from rheological forging process. The billet fabricated
by EMS in vacuum pressure reduced formation of oxides and porosities of the inner material. The
billet fabricated by EMS in vacuum pressure below 56 cm/Hg remarkably reduced porosities,
comparing to the EMS in atmospheric pressure.
Effect of Volume Fraction Solid and Injection Speed on Mechanical Properties in New Type Semi-Solid Injection Process
Authors: Omura Naoki , Murakami Yuichiro , Li Ming Jun , Tamura Takuya , Miwa Kenji
Published: March 2009

We have developed new type semi-solid injection process, that is, runner-less injection
process which can obtain high material yield of about 90% for magnesium alloy. In this process,
alloy billets are heated to the semi-solid temperature in the injection cylinder and are injected into a
permanent mold. In order to investigate the effects of volume fraction solid and injection speed on
microstructure and mechanical properties of AZ91D magnesium alloy injected into the permanent
mold, semi-solid forming testing machine which has the same system as a runner-less injection
machine, has been made on an experimental basis. The magnesium billet precisely controlled at
given temperature has been injected into a permanent mold with two kinds (slow and high) of speed
and plate-like specimens with each fraction solid have been fabricated. Microstructure has been
observed by optical microscopy and X-ray computerized tomography (CT) scanner. Mechanical
properties have been measured by tensile test. The effects of volume fraction solid of the alloy
slurry and injection speed on mechanical properties have been clarified.
Weldability of SSM Rheo Processed Aluminum Alloy A356
Authors: Govender Gonasagren , Ivanchev L. , Burger H.P. , Knutsen R.D. , Kunene G.
Published: March 2009

CSIR-Rheo technology process which involves the preparation of metal slurry direct
from liquid alloys by stirring and cooling was applied for treatment of Al-7%Si-0.35%Mg alloy,
A356, to the Semi-Solid Metal state. Plates were cast in steel moulds with a 50 Ton High Pressure
Die Casting machine. Heat treatments T4 and T6 were given to the samples. Butt laser welding was
performed on the heat treated and as fabricated plates (F). Tensile properties, hardness profile,
microstructure of the weld, heat affected zone and base metal were examined. Some comments on
outcomes of the research are included.
The Effect of Si Content on the Mechanical Properties of Rheocast Al Components Using the RHEOMETALTM Process
Authors: Cao Hai Ping , Granath Olof , Wessen Magnus
Published: March 2009

The RHEOMETALTM process is a commercially used semi-solid process for production
of high integrity cast components. The process differs from most other semi-solid casting processes
in that temperature control is not necessary during processing and large amount of slurry with
required solid fraction can be quickly produced. The simplicity of this process has led to a large
commercial interest during the last year.
This work is based on an investigation regarding the variation of as-cast mechanical properties for
secondary Al-Si based alloys (~2.5 % Cu) with a Si content varying from 4.55 to 8.90 % using the
RHEOMETALTM process. The purpose was to find the most suitable Al-Si alloy for rheocasting, in
comparison with the common HPDC-alloy A380 (EN-AC46000). It was found that lower Si
containing alloys exhibited better elongation but slightly lower yield strength. The alloy containing
5.39 wt% Si showed the highest ultimate tensile strength in this investigation. The lower Si
containing alloys also demonstrated better feedability in the rheocasting process, which is contrary
to what normally is found for normal liquid casting processes. Based on the results in this
investigation it is recommended to use an alloy containing about 5-7 wt% Si for rheocasting
purposes.
Theory and Technology of Semisolid Metal Molding
Authors: Czerwinski Frank
Published: March 2009

Fundamentals of semisolid metal molding, including the particulate feedstock,
methods of its generation and features that make it useful for processing, are outlined.
Melting characteristics of the feedstock under sole influence of heat are considered, covering
a wide range of microstructural and microchemical factors, believed to be of importance at
high temperatures. The generation of the thixotropic slurry within the injection molding
system and its solidification behaviour are accompanied by detailed features of the molded
structures and their correlation with properties of net-shape components. In addition to
conventional techniques the novel processing concepts including near-liquidus molding,
semisolid extrusion molding as well as the alloy and composite generation in a semisolid
state are described. An update on commercialization progress is completed by a
characterization of the modern equipment used for process implementation with broad
references to metal die casting and plastics injection molding.
Fabrication of Csf/Mg Composites Using Extrusion Directly Following Vacuum Infiltration - Part 2: Forming Process Study
Authors: Qi Le Hua , Zhou Ji Ming , Su Li Zheng , Ouyang Hai Bo , Li He Jun
Published: March 2009

Extrusion directly following vacuum infiltration is a special forming technique that
combines the advantages of liquid metal infiltration and semisolid extrusion. The major advantages of
this process are elimination of porosity and shrinkage, good surface finish, good dimensional
accuracy, high strength to weight ratio and near net shaping. Magnesium matrix composites are
fabricated usually through stirring casting, powder forming, injecting deposition, liquid metal
infiltration or die casting at present time. However few investigations on magnesium matrix
composite are conducted for the specific characteristics of magnesium alloy, such as high chemical
activity and easy oxidation. The present paper is focused on Csf/Mg composites obtained via
infiltration of porous short carbon fiber preform by liquid Magnesium. The complete experiment
setup is designed and fabricated by ourselves, which include the forming molds, the unit for melting
the magnesium, the unit for vacuuming and the monitoring and collecting system of forming process
parameters. In this method the whole experiment setup is vacuumed firstly. Then the pressurized
nitrogen is used to infiltrate the magnesium melt through a porous preform of short carbon fibers.
After the infiltration completed, the punch of the press extrude the magnesium-infiltrated preform out
of the forming die to form the tubes or bars. X-ray diffraction (XRD), optical and SEM microscopes
were used to characterize the infiltration and the microstructure of fabricated composites. The
compression test was used to characterize the mechanical properties of fabricated composites. The
results show that the preform was infiltrated thoroughly by melt magnesium and the fabricated Csf/Mg
composites have excellent mechanical properties compared with the magnesium alloys. Csf/Mg
composites should be very promising candidates for automobile parts and portable electronic
appliance parts in the future.
Analysis of Robustness of Vibration Control System for a Magnetically Supported Shaft
Authors: Mystkowski Arkadiusz , Gosiewski Zdzisław
Published: March 2009

Analysis of robustness of active magnetic bearing system is carried out in the paper. All
of the most important acceptable levels of robustness are established. Rigid body model of a rotor is
used for controller design, stability and analysis of robustness. Advanced tools for robust control are
applied. The μ-synthesis is used to design a μ robust controller to stabilize the shaft that is
supported magnetically. The influence of robust control on the sensitivity of plant with an
uncertainty dynamics is shown. The influence of dynamic uncertainty on the robustness level of
closed-loop system is considered. Small gain theorem and robustness theorem for an active
magnetic bearing are investigated. Finally, the experimental results confirm the analytical
investigations of the robust control of vibrations.
Enhancing the Accuracy of MRI-Compatible Robots with an Optical Tracking System
Authors: Junttila Petri , Nevala Kalervo , Kroneld Petter
Published: March 2009

Magnetic resonance imaging (MRI) is currently a widely used technology for obtaining a
three-dimensional image of a patient’s internal structures. This study examines the measurement
properties of an optical tracking system utilised in the MRI room. The results were used to assess
the suitability of the device to be used as a part of the control system of a surgical robot. The
position and orientation of the instrument, MRI scanner and the patient are measured using an
optical tracking system in the MRI room. The measurement data can be used to display the
instrument used as a part of the image of the patient. The optical tracking system used in the MRI
room can also be considered as a part of the control system of a robot located in the room. When
considering such use, the operations of the measuring device in different measurement conditions
must be known. In terms of robot control, it is important to know the deviation attributed to
measurement when defining the translation vector and orientation between two trackers. Five
measurement series were carried out using the measurement device to examine the deviation in the
translation vector and orientation data between two trackers. The distance and position between the
trackers were changed between the measurement series. During the measurement series, the
measurement device was moved to different distances from the trackers and the translation vector
and orientation between the trackers were defined on the basis of the measurement results obtained.
The measurements showed that the deviation of the translation vector did not significantly change
as the measurement distance increased, but the deviation of orientation data between different
trackers increased significantly. Deviation in the translation vector increased as the distance
between trackers increased, but deviation in orientation did not change significantly.
Control of Mobile Crane by Means of Fuzzy Logic Controller
Authors: Pędrak Tomasz , Kłosiński Jacek
Published: March 2009

Modern computer technology and knowledge on building of mathematical models enable
creation of models of control systems. These systems can be created for different objects without
any need to build real scientific test stands in the initial stage of investigations. It, in turn, enables
an essential limitation of the costs as well as performance of fast analysis of usability of the defined
methods. This approach constitutes a big improvement in a whole process of designing of such a
system.
Uncertainty Modeling in Robust Control of Active Magnetic Suspension
Authors: Mystkowski Arkadiusz , Gosiewski Zdzisław
Published: March 2009

Stabilization of a plant in case of uncertainty parameters and unmodeled dynamics are
the main problems considered in this paper. A robust control of motion of a rigid shaft that is
supported by magnetic bearings was used as an example. The dynamics of the active magnetic
suspension system is characterized by instability and uncertainty. The uncertainty is modeled as an
additive and multiplicative. Robust controller H∞ was designed for the defined plant with the
uncertainty models. The robust controller assures high quality of control despite the uncertainty
models. Robust control of vibrations of a rigid rotor is confirmed by experimental studies. A digital
signal processor is used to execute the control algorithm in real time.
Investigation of Alloy Elements Transfer in Arc Facing by High Carbon and Chromium Content Electrodes
Authors: Varnauskas Valentinas , Valiulis Algirdas Vaclovas , Rudzinskas Vitalijus
Published: March 2009

Consistent patterns for transfer of chromium and carbon from the electrode coating into
the fused metal, impact of their amounts on transfer of other alloying elements into the alloy are
considered. Respective compositions of electrode coatings are made so, that Cr content in coated
layers would change from 2 % up to 40 % (content of C ~ 3 %). At research of transfer of carbon
patterns, the compositions of electrode coatings are made so, that C content in coated layers would
change from 0.1 % up to 4 % (content of chromium in this case is approximately 20 %). In both
cases the content of other alloying elements remain in a settled level (Si ~ 2 %, Mn ~ 1.1 %, Ti
~ 0.5 %, B ~ 0.6 %).
The Influence of Selected Powder Fillers on the Tribological Properties of Composite Materials for Dental Fillings
Authors: Mystkowska Joanna , Dąbrowski Jan Ryszard
Published: March 2009

The aim of this study was to determine the influence of powder fillers on the tribological
properties of composite materials used for dental fillings. The investigated composites contain a
fluoridated filler (based on Ba-Sr-Al-P-Na-silicate glass fillers) as a fluoride source as well as
different powder fillers (friction modifiers) e.g. silicon nitride (Si3N4), boron nitride (BN),
polyethylene (PE), polytetrafluoroethylene (PTFE). Composite disks were photo-cured and tested
for wear against harder stainless-steel counterface. Wear tests were carried out by means of special
tribotester in the presence of phosphate buffer as a lubricant. Influence of the load and filler
contents on the friction coefficients and wear were estimated. The interaction between the filler
particles and organic matrix and its influence on the tribological behavior of prepared specimens
were observed. Organic powder fillers (PE, PTFE) reduced the friction coefficient and the wear of
tested composite materials for dental fillings. Inorganic friction modifiers (Si3N4, BN) did not
exhibit this effect.
Modeling of Magnetic Attraction Force of Electromagnetic Module in a Relative Base – Air-Gap – Absolute Base System
Authors: Huścio Tomasz , Falkowski Krzysztof
Published: March 2009

In this paper a formula of estimation of magnetic attraction force in the relative base –
air-gap – absolute base system is presented. The attraction force of the relative base (forcer) to the
ferromagnetic absolute base (stator) is a result of the attraction of permanent magnets, which are the
components of the electromagnetic modules. The physical model and mathematical description of
the particular electromagnetic module are presented.
Highly Sensitive Detection of Inorganic Contamination
Authors: Beckhoff Burkhard , Nutsch Andreas , Altmann Roswitha , Borionetti G. , Pello C. , Polignano Maria Luisa , Codegoni Davide , Grasso Salvo , Cazzini Elena , Bersani M. , Lazzeri P. , Gennaro S. , Kolbe Michael , Müller Matthias , Kregsamer P. , Posch Florian
Published: March 2009

As the detection of inorganic contaminants is of steadily increasing importance for the improvement of yields in microelectronic applications, the aim of one of the joint research activity within the European Integrated Activity of Excellence and Networking for Nano- and Micro-Electronics Analysis (ANNA, site: www.ANNA-i3.org) is the development and assessment of new methodolo¬gies and metrologies for the detection of low concentration inorganic contaminants in silicon and in novel materials. A main objective consist in the benchmarking of various analytical techniques avail¬able in the laboratories of the participating ANNA partners, including the improvement of the res¬pective detection limits as well as the quantitation reliablity of selected analytical techniques such as total-reflection x-ray fluorescence (TXRF) analysis.
Metallic Contamination Control in Leading-Edge ULSI Manufacturing
Authors: Shimazaki Ayako , Sakurai Hiroki , Iwase Masao , Yoshimura Reiko , Tada Tsukasa
Published: March 2009

Contamination control has become a high-centered issue for the fabrication yield, performance and reliability of leading-edge ULSI devices. With the progress of sizing down dimensions in higher-density devices, complicated device structures and various novel electronic materials have been introduced, particularly in the latest devices such as CMOS and nonvolatile memory LSIs (Table I). On the other hand, high productivity is a necessity when you consider QTAT (quick turnaround time) and cost-effective flexible ULSI manufacturing lines. Therefore, effective contamination control coupled with adequate protocol has become essential in such production lines. The point of the protocol is minimization of damage caused by impurity metals diffused from these novel electronic materials [1-5].
Molybdenum Contamination in Silicon: Detection and Impact on Device Performances
Authors: Codegoni Davide , Polignano Maria Luisa , Caputo Daniele , Riva Andrea , Blot Emmanuel , Coulon David , Maillot Philippe , Pic Nicolas
Published: March 2009

In this paper, a case of molybdenum contamination from wet cleaning is discussed, and various techniques are compared for their ability to detect molybdenum. In addition, the impact of this sort of contamination on the electrical results of a bipolar device is studied.
Reduction of Airborne Molecular Contamination on 300 mm Front Opening Unified POD (FOUP) and Wafers Surface by Vacuum Technology
Authors: Maquin Philippe , Kambara Hisanori
Published: March 2009

With decreasing critical size of micro-electronic fabrication imposed by ITRS today, Front Opening Unified Pod (FOUP) has been designed to transport the silicon wafers in the 300 mm semiconductor fab to decrease the particles contamination, without taking the Airborne Molecular Contamination (AMC) and moisture problems into account. Various methods of AMC decontamination methods has been introduced in past, such as purging mini-environment with nitrogen, however the efficiency of its yield improvement capacity has not been proven. An ultimate AMC decontamination method with vacuum decontamination and passivation technology shows a very good efficiency on the AMC removal mechanism, with a direct impact on the yield improvement.
Study of the Volatile Organic Contaminants Absorption and their Reversible Outgassing by FOUPs
Authors: Fontaine Hervé , Cetre Sylviane , Veillerot Marc , Danel Adrien
Published: March 2009

Today, the use of Pods or FOUPs (Front Opening Universal Pod) in IC manufacturing leads to specific molecular contamination issues related to the enclosed environment made with porous polymers (mainly PEEK, PC and PP) that constitute these containers. Indeed, such materials are known to outgass airborne molecular contaminants (AMC), especially polymers additives [1,2]. They are also able to absorb volatile compounds present in their atmosphere coming from the connection to an equipment or from the release of wafers just processed [3,4]. As a result, a reversible outgassing of species previously trapped in plastic is possible. This is especially critical in presence of wafers sensitive to the released contaminants leading then to potential detrimental impacts. This cross-contamination scheme was clearly evidenced for volatile acids in presence of Cu layers leading to corrosion issues [4].
Impact of Megasonic Activation with Different Chemistries on Silicon Surface in Single Wafer Tool
Authors: Briend Guillaume , Besson Pascal , Salvetat Thierry , Petitdidier Sébastien
Published: March 2009

More and more, 300mm manufacturing promotes a single wafer tool approach in FEOL cleaning. Previously, we reported an advanced surface preparation process based on dilute HF/HCl/DIW and O3/HCl/DIW chemistries coupled with megasonic activation during the ozone step only, on a 300mm single-wafer platform [1]. As throughput consideration implies shorter process time, the activation of megasons during the whole cleaning step could be of interest for very small particle removal efficiency. Nevertheless, extending megasonic activation to the entire process sequence leads to degraded results on silicon surface. Indeed, damages are created at 90 and 65nm defect inspection levels when megasonic activation is used in the presence of both HF species and on hydrophobic silicon surface. In this paper, we demonstrate that the megasonic activation (Megs) generates randomly and locally oxidized species which may be the main cause of damages in the presence of HF chemistry. Additional characterizations are performed to understand this problem (haze inspections, ATR analysis and contact angle measurements).
Application of Single-Wafer Wet Cleaning Prior to Epitaxial SiGe Process
Authors: Sano Kenichi , Wada Masayuki , Leys Frederik E. , Loo Roger , Hikavyy Andriy , Mertens Paul W. , Snow James , Izumi Akira , Miya Katsuhiko , Eitoku Atsuro
Published: March 2009

Strained silicon engineering was first used at the 90-nm node. Nowadays, a series of techniques has seen wide-spread use and many derivatives are available because of their ease of integration and cost-effective features [ , ]. As a main part of stressor technique, embedded SiGe-S/D technology is reported to improve the pMOSFET drive current [ , ].
Silicon Surface Preparation and Passivation by Vapor Phase of Heavy Water
Authors: Pap Andrea E. , Nényei Zsolt , Battistig Gábor , Bársony István
Published: March 2009

The well known wet chemical treatments of the silicon surface and its native oxidation in air cause a high density of interface states, which predominantly originate from dangling bonds strained bonds or from bonds, between adsorbates and silicon surface atoms. Therefore, a number of wet-chemical treatments have been developed for ultraclean processing in order to produce chemically and electronically passivated surfaces [1]. The saturation of dangling bonds by hydrogen removes the surface states and replaces them by adsorbate-induced states, which influence the surface band-bending [2]. The first thermal hydrogen desorption peak from a hydrogen passivated Si surface in vacuum or inert gas ambient can be detected at around 380°C [3,4]. Simultaneously the combination of the hydrogen atoms of neighboring dihydrides generates a pair of dangling bonds. At around 480-500°C dangling bonds are generated on the silicon surface by desorption of the remaining hydrogen [5]. At that moment the silicon surface becomes extremely reactive.
The Influence of Standing Waves on Cleaning with a Megasonic Nozzle
Authors: Janssens Tom , Doumen G. , Halder S. , Wostyn Kurt , Mertens Paul W. , Straka Joachim
Published: March 2009

A non uniform sound field distribution can be a problem in a megasonic cleaning system, since a higher sound intensity can cause damage, while areas exposed to a lower intensity will be insufficiently cleaned. These non uniformities can be the result of sound field reflection, leading to standing waves, and the interference related to the near field. In a single wafer tool with a transducer facing the wafer a small height difference will have a large impact on the cleaning efficiency if standing waves are present. Here we study the impact of the wafer transducer height in a cleaning system using a megasonic nozzle above a rotating wafer.
Chemical and Mechanical Analysis of HDIS Residues Using Auger Electron Spectroscopy and Nanoindentation
Authors: Kadavanich Andreas V. , Shim Sang Hoon , Meyer Harry M. , Savas Stephen E. , Lara-Curzio Edgar
Published: March 2009

Photoresist stripping after ion implantation at high dosages (>1E15 atoms/cm2) is the most challenging dry strip process for advanced logic devices. Such high-dose implant stripping (HDIS) frequently leaves residues on the wafers after dry strip, unless fluorine chemistries are employed in the stripping plasma. Silicon loss requirements at sub-45nm nodes generally preclude such aggressive stripping chemistries. Instead, a wet clean is used to remove residues. However, the nature of the residues is not well understood, and are believed to usually contain some of the cross-linked, carbonized organic polymer formed in the implant [1]. In this paper we present chemical and mechanical data on HDIS residues produced from oxidizing and reducing chemistry strip processes.
Stripping and Cleaning of High-Dose Ion-Implanted Photoresists Using a Single-Wafer, Single-Chamber Dry/Wet Hybrid System
Authors: Kim Y.J. , Lee J.H. , Seo K.J. , Yoon C.R. , Roh E.S. , Cho J.K. , Hattori T.
Published: March 2009

Stripping high-dose ion-implanted (HDI) photoresists is considered as one of the most challengeable processes in the semiconductor manufacturing due to the difficulty of both removing crust (or carbonized layer) formed during the ion implantation and preventing the silicon recess after subsequent cleaning. The HDI photoresists are conventionally removed by using a two-step process, low-pressure plasma ashing in a single-wafer tool followed by SPM-based wet stripping in a batch immersion tool. Alternative HDI-resist strip methods have been proposed, such as a combination of physical-force pretreatments followed by more traditional wet cleaning steps [1], a SPM-based all-wet process at extremely high temperature (≥ 200°C) [2], and supercritical CO2 combined with chemical additive formulations [3].
Post Ion-Implant Photoresist Stripping Using Steam and Water: Pre-Treatment in a Steam Atmosphere and Steam-Water Mixed Spray
Authors: Sanada Toshiyuki , Watanabe Masao , Hayashida Atsushi , Isago Yoichi
Published: March 2009

It is well-known that ion-implant doses greater than 5E14 atoms/cm2 can create an amorphous carbon-like layer “crust”, and also that this crust is extremely difficult to dissolve with wet chemicals. In practice, a combination of dry plasma ashing and wet chemical removal is used to eliminate the photoresist. In this study, a novel photoresist stripping technique is proposed. We have improved wet vapor photoresist stripping technique [1] using the mixture of high-speed steam flow and purified water droplets. Relatively low pressure clean steam is mixed with purified water in the nozzle, and sprayed on a photoresist coated Si wafer. We have also developed a pre-treatment method in a chamber with keeping both temperature and humidity constant, in order to strip post ion-implanted photoresit. The most significant feature of this proposed technique is that we use water only; hence we are able to strip photoresist without chemicals.
Surface Energy and Wetting Behaviour of Plasma Etched Porous SiCOH Surfaces and Plasma Etch Residue Cleaning Solutions
Authors: Ahner Nicole , Schaller Matthias , Bartsch Christin , Baryschpolec Eugene , Schulz Stefan E.
Published: March 2009

The removal of plasma etch residues by wet cleaning is an alternative or additional process to plasma processes, which are known to degrade low-k and ultralow-k dielectric materials. Besides Cu/low-k compatibility wetting is an important issue for wet cleaning. Surface energy of solid and liquid is the key to understand the wetting behaviour. In this study we examined the energetic character of plasma etched/stripped solid surfaces, etch polymers and several cleaning solutions by contact angle measurements. The results show, that variations of the etching process can heavily change the energetic character of the solid. Calculating the surface energies of solid and liquid provides the possibility to make a prediction if a cleaning liquid will wet the surface which has to be cleaned.
Recyclable Fluorine-Based Cleaning Solvents for Resist Removal
Authors: Okamoto Hidekazu , Namatsu Hideo
Published: March 2009

The development of new functional cleaning agents is strongly required for leading-edge LSI fabrication, such as resist removal process without any damage to low-k materials. For example, as excessive acid cleaning agents would damage such materials. Consequently, a low damage cleaning technique with no collapsing fine structures is also desirable. On the other hand, the concept of recycle of cleaning agents is an urgent issue for the reduction of cleaning cost. Therefore, both cleaning ability and easy recyclable function are essential for next generation cleaning agents. Fluorine-based cleaning agents have been widely used for cleaning, rinsing and drying process in the electronics industry. Asahi Glass Corporation (AGC) has commercialized various fluorine-based cleaning agents as AC-series (Hydrofluorocarbon: HFC) and AE-series (Hydorofluoroether: HFE). Typical properties of these compounds are summarized in Table I. Here we report the application of fluorine-based cleaning agents to ArF resist removal and the evaluation of the recycles.
Advances in Test Wafer Reclaim Technology – Wet Stripping Porous Low-k Films with No Substrate Damage
Authors: Robson Mark , Fletcher Kristin A. , Jiang Ping , Korzenski Michael B. , Upham A. , Haigh Jr. T. , Hsieh Thomas J.C.
Published: March 2009

In semiconductor processing, test wafers are used as particle monitors, film thickness monitors for deposition and oxide growth measurements, dry/wet etch rate monitors, CMP monitors, as well as characterizing new and existing equipment and processes. Depending on fab size and capacity, monthly test wafer usage can be tens of thousands or more. Due to the ever increasing demand for silicon between the IC and solar markets and the high cost of 300mm wafers, chip manufacturers are increasing their efforts to reduce overall spending on silicon - currently by far the largest non equipment related cost [1]. One approach taken by many chip makers is the concept of extending the usable life of test wafers by re-using them as many times as possible through a reclaim process.
Borderless via Clean Study for Minimizing Al-Cu Loss in 58nm Flash Devices
Authors: Chen Cheng Kuen , Yu Pi Chun , Lee Ming Hsiu , Wu Chih Ning , Matsuo Hiroshi
Published: March 2009

The borderless (BDL) vias landing on the metal lines were demanded in high-density flash memory devices due to the reduced die size, compared with non-borderless (NBDL) vias. IMD material recess in un-landed via dry etching and the Al-Cu metal line undercut caused by post-etch cleaning may lead to via resistance Rv high and EM reliability issue. In this work, the Al-Cu loss mechanism in BDL-via cleaning by using amine- and fluoride-based chemicals were studied in 58nm flash devices. We found that the Al-Cu undercut can be minimized in HDA containing solvent by controlling the formation of Al2O3/Al/HDA gel-like material to the less amounts; the shorter HDA processing time with sufficient IPA rinse generated the thinner gel-like layer leading to the less Al-Cu undercut in DIW rinse step. For TMAH/H2O2-containing semi-aqueous solution, the metal contained etched-residues can be removed by reaction of OH- with Al to form dissolved Al(OH)4-; addition of H2O2 will form a oxidized passivation layer on the metal surface to prevent from metal corrosion. On the other hand, the Al/Al2O3 contained polymer was removed by fluoride-based solvent or DSP+ through the reaction with [F-] to form the DIW-dissolved AlFx by-products; while the dilute H2SO4 and H2O2 in DSP+ will oxidize Al to form Al2O3 that will be further etched by HF, the severe Al-Cu undercut was found in DSP+.