Photovoltaic Silicon Wafer _ SUMCO CORPORATION
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Transcript of Photovoltaic Silicon Wafer _ SUMCO CORPORATION
Photovoltaic Silicon Wafer
Photovoltaic Silicon Wafer | SUMCO CORPORATION http://www.sumcosi.com/english/products/solar/index.html
1 of 3 6/21/2012 4:38 PM
SUMCO CORPORATION is an EPIA MemberEuropean Photovoltaic Industry Association (EPIA) is the world's largest
Photovoltaic (PV) is one of the promising solutions to environmental and energy resource
problems that have become more serious each year.
A solar cell is a type of semiconductor that directly converts sunlight into electricity by the
photovoltaic effect.
Solar cells consist of many types depending on the materials and structures and are used in
different ways depending on the characteristics.
The manufacturing methods and general structures of multi-crystalline silicon solar cells will be
introduced.
SUMCO mass-produces high quality silicon wafers using a new proprietary technology known as
the “Electromagnetic Casting Method”.
SUMCO wishes to contribute to human living and our environment through photovoltaic silicon
wafers.
Photovoltaic Silicon Wafer | SUMCO CORPORATION http://www.sumcosi.com/english/products/solar/index.html
2 of 3 6/21/2012 4:38 PM
Photovoltaic Silicon Wafer
The enormous number of automobiles and the number of electrical appliances in households and
offices are increasing energy consumption. A large part of energy depends on fossil fuels, such as
petroleum and coal, which generate CO2 (carbon dioxide) during combustion. The problem of global
warming from CO2 emissions makes people to pay attention to the utilization of renewable energy,
such as photovoltaic energy.
The photovoltaic energy is acquired by a power generation system that directly converts sunlight into
electricity using solar cells.
Fossil fuels, such as petroleum and coal, have the problems of the emission of CO2 and the
depletion of the natural resource. On the other hand, photovoltaic energy using the inexhaustible
energy of sunlight is one of the promising solutions for environmental and energy resource problems
that are becoming more serious every year. The advantages are the complete lack of CO2
emissions, which is believed to cause global warming, and cleanliness and friendliness to the earth.
The photovoltaic energy system is a power generation system where demand is expected to increase
most rapidly.
Fig.1 : Trends in total CO2 emissions and CO2 emissions per person in Japan
In 2005, total CO2 emissions were 1,291 million tons, and CO2 emissions per person were
10.1 tons. These values show that total CO2 emissions increased by about 13% and CO2
emissions per person by about 9% in comparison with data from 1990. In order to protect
our environment, the reduction of CO2 emissions may be the most urgent task.
Source: National Institute for Environmental Studies
Why PV is attracting attention now ? | SUMCO CORPORATION http://www.sumcosi.com/english/products/solar/why.html
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Fig.2 : Total supply of primary energy in
FY2007 in Japan
It is said that the CO2 emitted during the
combustion of fossil fuels such as petroleum is
one of the causes of global warming. Our life is
highly dependent on fossil fuels, which occupy
about 85% of the total energy supply. Since
resources such as petroleum are not limitless,
we are concerned about the lack of such
resources in the future. It is believed to be
necessary to promote the introduction of renewable energy, such as photovoltaic energy, to
decrease the degree of dependence on fossil fuels.
Source: Agency for Natural Resources and Energy
Japan's land area is about 380,000 km² and occupies about 0.3% of the world's land area. If we
were to pave all of the land area of Japan with solar cells, they would cover about 30% of the total
power consumption in the world.
Why PV is attracting attention now ? | SUMCO CORPORATION http://www.sumcosi.com/english/products/solar/why.html
2 of 3 6/21/2012 4:38 PM
Copyright © 2010 SUMCO CORPORATION All Rights Reserved.
Why PV is attracting attention now ? | SUMCO CORPORATION http://www.sumcosi.com/english/products/solar/why.html
3 of 3 6/21/2012 4:38 PM
Photovoltaic Silicon Wafer
A solar cell is a type of semiconductor that directly converts sunlight into electricity. Almost all
semiconductors use single-crystalline silicon as the raw material, and many current solar cells now
use crystalline silicon.
SUMCO supplies silicon wafers for solar cells along with silicon wafers for semiconductors all over
the world.
The most popular solar cells at present use silicon, which is also used for semiconductors.
Exposure of silicon to light generates holes with an electrically positive property and electrons with a
negative property. This is called the photovoltaic effect. However, simply generating electrons and
holes does not allow taking out electricity, and they also disappear immediately.
There are two types of silicon: p-type silicon in which holes gather and n-type silicon in which
electrons gather. A solar cell consists of piled p- and n-type silicon layers. Therefore the generated
holes is attracted by the p-type silicon layer, and the electrons is attracted by the n-type silicon layer.
Thus the condition is the same as that of the + and - sides of a battery.
Each surface of the p-type silicon and n-type silicon is provided with an electrode for taking out the
electricity generated by the solar cell. The connection of electrical wires to the electrodes enables
the use of electric energy. Although it may seem difficult to understand because of the unfamiliar
terms, the mechanism is extremely simple where exposure to light generates electricity.
Mechanisms of photovoltaic energy | SUMCO CORPORATION http://www.sumcosi.com/english/products/solar/structure.html
1 of 2 6/21/2012 4:39 PM
Copyright © 2010 SUMCO CORPORATION All Rights Reserved.
Mechanisms of photovoltaic energy | SUMCO CORPORATION http://www.sumcosi.com/english/products/solar/structure.html
2 of 2 6/21/2012 4:39 PM
Photovoltaic Silicon Wafer
Solar cells consist of many types in addition to those that use crystalline silicon, depending on the
materials and structures; solar cells are used in different ways depending on the characteristics.
The most popular solar cells at present are crystal-based silicon solar cells using mono-crystalline or
multi-crystalline silicon. Crystal-based silicon has been used in solar cells from the beginning. A
silicon ingot is sliced into wafers as thin as about 0.2 mm on which the solar cells are created.
Although mono-crystalline silicon has high conversion efficiency (efficiency to convert sunlight into
electrical energy), the disadvantage is the high production cost. On the other hand, multi-crystalline
silicon has the advantages that it is cheaper and suitable for mass production.
SUMCO manufactures multi-crystalline silicon wafers proven to have high quality and stability for a
long period of time.
Copyright © 2010 SUMCO CORPORATION All Rights Reserved.
Types and features of solar cells | SUMCO CORPORATION http://www.sumcosi.com/english/products/solar/characteristic.html
1 of 1 6/21/2012 4:40 PM
Photovoltaic Silicon Wafer
We will introduce methods for manufacturing multi-crystalline silicon solar cell.
How to manufacture silicon solar cells | SUMCO CORPORATION http://www.sumcosi.com/english/products/solar/process.html
1 of 4 6/21/2012 4:40 PM
How to manufacture silicon solar cells | SUMCO CORPORATION http://www.sumcosi.com/english/products/solar/process.html
2 of 4 6/21/2012 4:40 PM
Multi-crystalline silicon wafer Solar cell Photovoltaic module (Solar panel)
Solar cell:
Silicon wafer where solar cell functions are created.
Photovoltaic module (Solar panel):
Combined and arrayed solar cells protected by transparent resin and strengthened glass to
make it an integral body.
Also called a solar panel.
Photovoltaic array:
Combined and connected photovoltaic modules.
A photovoltaic energy system can be easily maintained and controlled because of the simple
function of receiving light to generate power. In addition, it emits no exhaust gas or noise, but it can
be installed only if the land receives a sufficient amount of sunlight. Further construction by
combining modules allows changing the system size depending on the installation area.
Inverter/Protector:
An inverter converts DC (direct current) from the solar cells to AC (alternative current). The
How to manufacture silicon solar cells | SUMCO CORPORATION http://www.sumcosi.com/english/products/solar/process.html
3 of 4 6/21/2012 4:40 PM
power company supplies AC power.
Distribution Panel:
Distributes power to the wiring in the house.
Watt-hour meter:
Measures power purchased from the power company and power sold to the power company.
Generally, two meters are required for these cases.
Copyright © 2010 SUMCO CORPORATION All Rights Reserved.
How to manufacture silicon solar cells | SUMCO CORPORATION http://www.sumcosi.com/english/products/solar/process.html
4 of 4 6/21/2012 4:40 PM
Photovoltaic Silicon Wafer
SUMCO has developed an electromagnetic casting method that enables stable manufacturing of
high quality multi-crystalline silicon ingots. It is a quite unique technology which we are proud of.
1. Raw silicon
“Eleven-nines”(purity 99.999999999%) silicon is used as a raw
material
2. Electromagnetic casting method
Raw silicon is molten from high frequency induction heating using induction coils. The high
frequency induction heating system allows an object to induce electric current using the same
principle as an IH heater. Since the electromagnetic force generated by the induction coil provides
molten silicon with the force directed toward the center, the liquid silicon can maintain high purity
without making contact with the crucible. By lowering the ingot slowly, the liquid silicon cools
gradually and crystallizes.
SUMCO's unique technologies | SUMCO CORPORATION http://www.sumcosi.com/english/products/solar/original.html
1 of 3 6/21/2012 4:42 PM
3. Square multi-crystalline silicon ingots
The ingot manufactured by the electromagnetic casting method
is the largest silicon crystal for solar cells in the world with a
length of 7,000 mm.
4. Multi-wire saw
A multi-wire saw capable of cutting four silicon blocks
simultaneously is used to ensure wafer quality and productivity
that is state-of-the-art for the industry
5. Cleaning
The sliced wafers are carefully washed in a two-step process consisting of an initial wash and a
finishing wash.
6. Inspection
To ensure that stringent customer standards are met, each wafer product is inspected by an
experienced inspector who is a specialist in the field.
SUMCO's unique technologies | SUMCO CORPORATION http://www.sumcosi.com/english/products/solar/original.html
2 of 3 6/21/2012 4:42 PM
The electromagnetic casting method is a process by which high frequency induction inside a cooling
crucible is conducted to melt raw silicon and use powerful electromagnetic energy to suspend the
molten silicon and form ingots continuously. This enables high quality silicon ingots to be
manufactured without the molten silicon ever coming in contact with the crucible.
Advantages of silicon wafer manufactured by the electromagnetic casting method
Continuous casting process improves uniformity and maintains quality.
Small variations in the conversion efficiency can provide stable performance and quality.
High resistance to breakage of the wafer enables a reduction in thickness, leading to the
saving of raw materials.
SUMCO's silicon wafers demonstrate these excellent features and are highly evaluated by the
customer as easy-to-use wafers.
Copyright © 2010 SUMCO CORPORATION All Rights Reserved.
SUMCO's unique technologies | SUMCO CORPORATION http://www.sumcosi.com/english/products/solar/original.html
3 of 3 6/21/2012 4:42 PM
Photovoltaic Silicon Wafer
Photovoltaic power generation uses an extremely clean, cheap power generation method and needs
no fossil fuels as required in thermal power generation and emits no waste gas such as CO2
emissions during power generation. In the past, since fossil fuel was mined in large quantities and
supplied at low cost, the relatively high cost of solar cells restricted the speed of growth. However,
possible depletion of fossil fuel resources and price increases as well as serious environmental
issues made people pay more attention to photovoltaic energy. The promotion of the expansion of
the solar cell market will contribute to a reduction in the cost of solar cells, leading to a significant
increase in demand.
Fig.3 : Shipments of solar cells by Japanese vendors
Source: Japan Photovoltaic Energy Association (JPEA)
Although environmental and energy resource issues are important, the problem with renewable
energy in the form of photovoltaic energy is that the cost of introduction is high. In order to promote
the use of photovoltaic energy, many countries are implementing a variety of support measures. The
primary measures promoting the use of renewable energy are as follows:
Expanding PV market | SUMCO CORPORATION http://www.sumcosi.com/english/products/solar/market.html
1 of 3 6/21/2012 4:43 PM
Cash subsidies or loans at low interest rates as support for the purchase and installation of
photovoltaic energy systems
Purchase of generated power at favorable prices
Cost of installation is tax deductable
Obligatory installation in public buildings and large facilities
Obligatory use of renewable energy such as photovoltaic energy
In the face of the severe recession in the world economy, many countries will implement a policy to
develop renewable energy and environmental technology in order to stimulate the economy and
increase employment because the growth of renewable energy-related industries is expected to
create jobs and have a positive effect on the economy.
Primary measures for the use of renewable energy and environmental policy
Measures for promoting the use of
photovoltaic energyEnvironmental policies
Japan
Cash subsidies for installation cost
(70,000 yen per kilowatt per house and
50% of the cost for public institutions)
along with an income tax deduction for
part of the installation cost. Surplus
photovoltaic power to be purchased at
about 24 yen per 1 kWh. Studying the
purchase of surplus power at a price
nearly twice the current amount.
Electric power suppliers are obliged to
use renewable energy-related electric
power at more than a specific ratio
corresponding to the sold electric
energy.
Cabinet council decided to implement
a low carbon society creation action
plan where the primary purpose is to
increase the number of photovoltaic
energy system installations to 40 times
the current number by 2030. In
addition, studying the promotion of
investment in the development and use
of energy-saving technologies and
products to restrict CO2 emissions as
well as the creation of targeted
employment for more than 800,000
people in the next five years through
the growth of environment-related
industries.
United
States
Deduction of 30% of the cost of
introduction of photovoltaic energy
system from income or corporate tax,
and cash subsidy for introduction in 38
states. Each state determines the
introduction target or provides support
and assistance measures.
Proposal for the investment of 150
billion dollars in the environment and
energy industries in the next 10 years
to create employment for 5 million
people.
GermanyPurchasing generated power at a
favorable price (feed-in tariff).
The number of employees working in
renewable energy-related industries,
Expanding PV market | SUMCO CORPORATION http://www.sumcosi.com/english/products/solar/market.html
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Measures for promoting the use of
photovoltaic energyEnvironmental policies
Purchasing price is 35 to 47 euro cents
per 1 kWh depending on system size
and installers. Loan at low interest rate
and tax deduction are also available.
including photovoltaic energy, is
currently 250,000. Further reductions
in CO2 emissions, including the
obligation to use green electric power
to create employment for an additional
500,000 people.
* These information is correct as of March 2009
The amount of solar energy striking the earth is very large and
inexhaustible. It would be wonderful if human beings could
create electricity, which is very important for living comfortably,
from clean solar cells.
SUMCO wishes to contribute to human living and our
environment through photovoltaic silicon wafers.
Links
European Environment Agency (EEA) (New Window)
Agency for Natural Resources and Energy (ANRE) (New Window)
Greenhouse Gas Inventory Office of JAPAN (New Window)
New Energy and Industrial Technology Development Organization (NEDO) (New Window)
European Photovoltaic Industry Association (EPIA) (New Window)
Japan Photovoltaic Energy Association (JPEA) (New Window)
Copyright © 2010 SUMCO CORPORATION All Rights Reserved.
Expanding PV market | SUMCO CORPORATION http://www.sumcosi.com/english/products/solar/market.html
3 of 3 6/21/2012 4:43 PM
Product Lineup
SUMCO supplies all kinds of silicon products for the semiconductor industry, ranging from single
crystal silicon ingots to polished, epitaxial and SOI wafers. The high quality products meeting our
customers' needs are made from raw materials with ultra-high purity under attentive quality control.
Single Crystal Silicon Ingots
Polished Wafers (PW)
Annealed Wafers
Epitaxial Wafers (EW)
Junction Isolated Wafers (JIW)
Silicon-On-Insulator (SOI) Wafers
Reclaimed Polished Wafers (RPW)
Specifications of Silicon Wafers
Single Crystal Silicon Ingots
High quality silicon ingots are produced by the method of Czochralski
(CZ) or Magnetic field applied Czochralski (MCZ) up to 300 mm in
diameter.
Polished Wafers (PW)
Polished wafers have excellent flatness and cleanliness by polishing
chemically and mechanically the wafers sliced out of silicon ingot. The
external gettering layer could be produced on the back surface of the
polished wafers as option.
Annealed Wafers
The polished wafers annealed in hydrogen or argon atmosphere have the improved crystalline
perfection of surface.
Product Lineup | SUMCO CORPORATION http://www.sumcosi.com/english/products/lineup.html
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Epitaxial Wafers (EW)
A thin single silicon crystal layer is deposited on the
polished wafer by chemical vapor deposition. Epitaxial
wafers have superior crystalline perfection.
Junction Isolated Wafers (JIW)
Junction Isolated Wafers are epitaxial wafers with
buried layers which are produced with the patterns of
IC meeting customers' designs by using
photolithography, ion-implantation, thermal diffusion
technology and so on.
Silicon-On-Insulator (SOI) Wafers
Silicon-On-Insulator (SOI) wafers are developed to
realize the new generation of semiconductor devices
which require larger scale integration (LSI) level, lower
power consumption, faster operating speed and/or
higher reliability. Three types of SOI wafers are
produced as follows.
Reclaimed Polished Wafers (RPW)
SUMCO has also reclaim-process for used wafers to return high-quality reclaimed wafers to
customers.
Specifications of Silicon Wafers
Type Polished Annealed Epitaxial Junction SOI Wafer
Product Lineup | SUMCO CORPORATION http://www.sumcosi.com/english/products/lineup.html
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Wafer Wafer WaferIsolated
Wafer
Diameter (mm)
100
125
150
200
300
−
125
150
200
300
100
125
150
200
300
100
125
150
200
−
−
−
150
200
−
Direction of crystal <100> , <111> , <110>
Elements added for
type and resistivity
control
B (Boron), P (Phosphorus), Sb (Antimony), As (Arsenic)
Copyright © 2010 SUMCO CORPORATION All Rights Reserved.
Product Lineup | SUMCO CORPORATION http://www.sumcosi.com/english/products/lineup.html
3 of 3 6/21/2012 4:44 PM