Transcript The Making of Silicon Wafers

Silicon Wafer Production Process
Silica (SiO2)
Semiconductor or solar grade silicon
is made from silica as the raw
material through multi-production
steps. Silica is the most abundant
material in the earth’s crust.
Refining / Reduction
Elemental metallic silicon is made
by the carbothermic reduction
method in an electric furnace. Its
purity is around 99% which is still
too low for use as semiconductor
grade silicon.
(Si02 + 2CSi +2CO)
Ultra-pure polysilicon Rod
Elemental silicon is again formed by the
Siemens method. This rod is a polycrystal,
but its purity is an astonishing
99.999999999% called “eleven-nines.” A
purity of “nine-nines is acceptable for solar
grade polysilicon.(HiSCl3+H2Si + 3HCl)
Electronic-grade rod
Silicon Wafer
Uses
Solar cells
Devices that
convert photons
from the sun (solar
light) into electricity.
Semiconductor
Devices
ICs, LSIs, VLSIs
and discrete
devices are the
foundation of
today’s and
tomorrow’s
advanced
electronic devices.
Silicon Wafer
Flatness, particles,
scratches, contaminations
and other wafer
deformations are the main
concerns in the wafer
process. The purity of the
chemicals, water and the
cleanliness of the process
are key factors in
production.
Polishing
Wafers are
polished over
and over again
to get a mirrorlike finish using
a mechanochemical
process
Solar Grade rod
Single Crystal Silicon Ingot
A dislocation-free single crystal ingot with
definite orientation is grown from the melt of
polysilicon by Czochralski (CZ), modified CZ,
or a Multicrystalline casting process. In all
processes, a small amount of agent (B, P,
So, As) is doped to regulate resistivity and
conductivity type.
CZ Single Crystal Ingot
Slicing
Single crystal silicon ingot is
sliced into wafers using a
diamond saw.