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IMPLANTATION TECHNOLOGYByOnyekanne Maria Chinyerem
(40389)Onwudiwe Killian ( 40505 )Ebunu Abraham ( 40501 )Department
Of Material Science And Engineering Course: Energy StorageLecturer:
Professor Esidor NtsoenzokJanuary 2017African University Of Science
and Technology Abuja
26/01/20171
OUTLINEIon implantation overviewDescription of an Implanter and
Working principleInnovations in implanter technologyPIII comparison
with standard implantersApplications of implanters in semiconductor
and non semi conductor materialsInnovative application
proposalsSummary and Conclusion Appreciation
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Background and IntroductionION IMPLANTATION: what is it ?
!!!!!process by which energetic impurity atoms can be introduced
into single crystal substrate in order to change its electronic
propertiesIn this process the ions are accelerated to high energies
and allowed to impact the silicon surfaces. Because of inherent
energy they penetrate into the lattice and are placed inside the
silicon lattice. low-temperature technique for the introduction of
impurities (dopants) into semiconductors and offers more
flexibility than diffusion.
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Background and IntroductionThe idea was proposed by Shockley in
1954, but used for mass production only after late 1970s. Before
ion implantation, doping is achieved by diffusion into the bulk
silicon from gaseous source above surface, or pre-deposited
chemical source on wafer surface.This approach lacks the
flexibility and control required by CMOS processing, and ion
implantation quickly gained popularity for the introduction of
dopant atoms.Modern ion implanters were originally developed from
particle accelerator technology. Their energy range spans 100eV to
several MeV (a few nms to several microns in depth range). The
implantation is always followed by a thermal activation
(600-1100oC).
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IMPLANTERS
i26/01/20175
DISCRIPTIONSTypical ion implantation parameters:Ion: P, As, Sb,
B, In, ODose: 1011 - 1018 cm-2Ion energy: 1 - 400 keV Uniformity
and reproducibility: 1%Temperature: room temperatureIon flux:
1012-1014 cm-2s-1The implanter basisIon sourceMass
analyzer/spectrometerIon acceleratorNeutral beam trapBeam
scannersWaferFaraday cup.
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WORKING PRINCIPLESIon source: Desired ion of the dopant species
are generated from ionization of eitherGas/sputtered solidArsine
(AsH3), Arsenic Penta fluoride (AsF5), phosphine (PH3), di borane
(B2H6), boron tri fluoride (BF3). Ionization is achieved by
displacing one or two electrons to give positive ions, since most
mass spectrometer works with positive ions. This process is carried
out at a voltage of ab0ut 25Kv-40Kv
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Mass analyzer/spectrometer26/01/20178
Ion accelerator: The ions that makes it through the mass
spectrometer are been accelerated with a certain voltage (0-175Kv)
to ensure the beam of ions travel with a particular kinetic energy.
Since the ions will be travelling through a vacuum, acceleration is
done to increase the kinetic energy of the ions so that they can
make through the vacuum. It is necessary the ions travel through a
vacuum to avoid interaction with oxygen, so as not to cause any
reaction.Neutral beam trap
The neutral beam trap is composed of an electrostatic charge
bars that allow neutral charges to pass freely, while the
positively charged are deflected on to the wafer.26/01/20179
Awafer, also called a slice or substrate, is a thin slice of
semiconductor material, such as a crystallinesilicon, used in
electronics for the fabrication of integrated circuits and in
photovoltaics for conventional,wafer-based solar cells.Wafers are
formed of highly pure (99.9999999% purity),nearly defect-free
singlecrystalline material.One process for forming crystalline
wafers is known as czochralski growthinvented by the Polish chemist
Jan czochralski.A boule of pure mono crystalline material is hence
formed, sliced and polished to form wafers.
Wafer:Beam scanning:The focused ion beam is scanned over the
wafer in a highly controlled manner in order to achieve uniform
doping.26/01/201710
26/01/201711Faraday cup.For each positive ion that enters the
faraday cup, an electron is drawn from ground through the current
meter to neutralize the positive charge of the ion. The magnetic
field stops outside the secondary electrons from entering and
secondary electrons produced inside from exitingThe faraday cup is
arranged in a process chamber and beam line, corresponding to an
ion beam shooting position
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Advantages of ion implantationExtremely accurate dose
controlTailor made and well controlled doping profile large
range-of doses-1011 to 1016/cm2 Low Temperature process Wide choice
of masking materials (Oxide, PR, Metal) Clean environment (Mass
separation, vacuum) Non-Equilibrium process (conc. Excess of S.S.
limit)Disadvantages of ion implantationHighly sophisticated and
costly. Damage to semiconductor. Dopant redistribution during
AnnealingPhotoresist heating and hard to strip
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Innovations Advanced ion implantation technology: takes full
advantage of doping and defect engineering approaches such as
device leakage, contact resistance, device and process variability
and of precision materials modification opportunities. It is
necessary that advanced implant tools for sub 20nm node incorporate
a variety of novel features and capabilities
Safe delivery source (SDS) technology : this is used for the low
pressure storage and dispersing of arsine and phosphine to ion
implanters
Ion implantation with scanning probe alignment: A scanning probe
instrument which integratesion beamswith the imaging and alignment
function of apiezo resistivescanning probe in high vacuum. The
beampasses through several apertures and is accurately set by a
hole in the cantilever of the scanning probe.
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15Improved single ion implantation with scanning probe alignment
:Improved technique for deterministic placement of
singledopantatoms by singleion implantationwith scanning probe
alignment. Ions are generated in amicrowavedrivenion source,mass
analyzed in a Wien filter, and impinge on spin readout devices
after alignment of theion beamto regions of interest with a
noncontact scanning force microscopeSource: Michael Llg et al,
2012: improved single ion implantation with scanning probe
alignment, journal of vacuum science and technology B
Innovation contd.
16Single wafer mechanical scan ion implanter: This makes use of
spot beam technology with ionized molecules which maximizes the
throughput potential and produces uniform implants with fast setup
time and with superior angle control
PIII, What is it?Plasma immersion ion implantation (PIII) is a
material modification technique for treating the near-surface
regions of materials by implanting energetic ions from a plasma
which surrounds the sample.A number of different terms are used,
such asplasma source ion implantation (PSII), plasma ion
implantation (PII),plasma immersion implantation (PII),
plasma-based ion implantation (PBII), plasma implantation (PI or
p-technique),plasma doping (also PLAD) and Ionclad.
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WORKING
PRINCIPLEShttp://www.sdsenc.in/sable/1386/exploitation-bentonite/
(source: W. Ensinger 1998)26/01/201718The vacuum chamber can be
of two types diode and triode type depending upon whether the power
supply is applied to the substrate as in the former case or to the
perforated grid as in the latter.Plasma source/generator: electron
cyclotron, helicon plasma source, capacitively coupled plasma
source, inductively plasma source, DC glow discharge and metal
vapour arc ( for metallic species
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The plasma envelopes the sample. The sample is negatively
biased. Ions from the plasma are accelerated and implanted into the
sample.
26/01/201719Accelerated ion is extracted from plasma using high
voltage pulsed DC or pure DC supply and targeting them to the
substrate or electrode (cathode for electropositive plasma and
anode for electronegative plasma) with semiconductor wafer placed
over it so as to implant it with suitable dopants.By means of a
pumping system and a gas feed system, an atmosphere of a working
gas at a suitable pressure is created, then a plasma is generated
Sample holder: The sample to be treated is placed on a sample
holder in a vacuum chamber. The sample holder is connected to a
high voltage power supply and is electrically insulated from the
chamber wall.
Conventional Ion Implantation (CII) Verses Plasma Immersion Ion
Implantation (PIII)
Ion Source
Target Beam ScannerIon BeamAnalyzing Magnet
PumpingIon Beam Implantation using an Accelerator
Plasma Immersed Ion Implantation (PBII, PIII)
Plasma Source
Pumping
High Voltage Pulser
+-Target
Difficult to implant to a large area or a complicated shaped
targetFor a large area or a complicated shape target.Simple system
structure is another good point.But,Not easy to process the target
with a narrow hole, trench, etc., or inside of a pipe.Non single
ion implantation is another demerit
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21PropertiesStandard implanterPlasma immersion ion
implanterHazardousNot easily operated , is sophisticated and not
easy to maintainSystem is relatively easy to operate and
maintain.
EconomicalThe CII technique is a sophisticated line of sight
process where a sample can be doped at room temperatureCapital
investment and running cost are substantially lessTime
ConsumingProcess time is dependent of sample size and its surface
areaProcess time is independent of sample size and its surface
area.FlexibleAny shape, size and weight of sample cannot be
processedAny shape, size and weight of sample can be processed.
Versatile: Multiple processes cannot be carried out like
implantation, deposition, etching, etc., Multiple processes can be
carried out like implantation, deposition, etching, etc., and not
just semiconductor or metals, even insulating samples can be
treated.
High Throughput: Number of samples cannot be processed at the
same timeNumber of samples can be processed at the same time
Temperature.Room temperature processLow- temperature
process.
22PropertiesStandard implanterPlasma immersion ion
implanterUniformity: The sample surface cannot be implanted
ensuring uniform dose rate with good conformity.The sample surface
can be implanted ensuring uniform dose rate with good
conformity.
ImplantationImplantation of multiple species with multiple
charges is not possible in the same system Implantation of multiple
species with multiple charges is possible in the same system
DRAWBACKSAs no mass separation is possible, there are always
chances of implantation of undesired impurities present in the
plasma into the target, in addition to the desired
dopants.Secondary electrons limit the efficiency and generate
x-rays. Accurate in situ dose monitoring is tough. Implant energy
distribution is inhomogeneous.
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Applications of ion implantationDopingNitrogen or other ions can
be implanted into a tool steel target (drill bits, for example).
prosthetic devices such as artificial joints, it is desired to have
surfaces very resistant to both chemical corrosion and wear due to
friction.ion beam mixing, i.e. mixing up atoms of different
elements at an interface.High speed mosfet.Metal parts on heart
valves are ion implanted by carbon to make them
biocompatibleRadioisotopes are implanted in prosthesis for
localized radiotherapy
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Application of PIIIMicro electronics (plasma
doping/PLAD)Biomaterials (surgical implants, bio and blood
compatible materials)Plastics (grafting, surface adhesion)
metallurgy (hard coatings and tribology)Thin metallic coatings on
polymeric surfaces example in electronic circuits, sensors,
electromagnetic shielding and flexible reflecting
surfaces26/01/201725
Innovative applicationsOne source multi element surface
treatment of materials : where hardening and surface finishing of a
particular material can be carried out using different ions of
different elements with a single machine, by ionizing at a
particular time, the atoms of the required element. This reduces
the need for several equipment in several applications.
Dose controlled coating of materials: where the particular dose
for a given surface area can be accurately determined to influence
the desired characteristics and properties onto the substrate
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Summary and ConclusionPlasma Immersion Ion Implantation is a
potential alternative that circumvents the limitations of
conventional ion implantation, such as the requirements of low ion
beam current, complicated target handling, non-uniform implantation
profile and ion beam scanning complexity for implantation of
three-dimensional targets. On account of the maturity and its
simplicity, it is believed that the PIII process technology will
find many more applications in the surface modification and
semiconductor industry. Reliable and non-expensive equipment is
still one of the key issues.
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References[1] S.B. Felch et al., Ion implantation for
semiconductor devices: the largest use of industrial accelerators,
Proceeding of PAC2013, Pasadena, CA USA, ISBN 978-3-95450-138-0.
http://accelconf.web.cern.ch/accelconf/pac2013/papers/weyb2.pdf
23/01/17
http://www.epj-onferences.org/articles/epjconf/pdf/2016/10/epjconf_MINOS2015_01002.pdf
23/01/17http://accelconf.web.cern.ch/accelconf/pac2013/talks/weyb2_talk.pdf
23/01/17
http://www-inst.eecs.berkeley.edu/~ee143/fa10/lectures/Lec_08.pdf
23/01/17
Professor N. Esidor, [2017], Lecture Note: Material for Energy
and Storage, AUST.Andre Anders , Lawrence Berckeley Laboratory;
Handbook of Plasma Immersion ion implantation and Deposition
28https://en.wikipedia.org/wiki/Plasma-immersion_ion_implantation
26/01/2017https://en.wikipedia.org/wiki/Ion_implantation 26/01/2017
Dushyant Gupta. Plasma Immersion Ion Implantation (PIII) Process
Physics ANDTechnology
Thanks So Much For Listening26/01/201729
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