Transcript From silica to silicon wafer v2.1 en

FROM SILICA
TO SILICON WAFER
The Silicon Single Crystal
and
Wafers Manufacturing
Version 2.1 En
Silicon V2.1 En
VPS
This presentation was prepared for the needs of the company ON Semiconductor with the aim to
approximate the production principles of single crystal silicon ingots and silicon wafers.
The manufacturing process details, pictures and video clips come from the company TEROSIL, a.s.
based in Roznov pod Radhostem, Czech Republic, we appreciate their friendly help in compiling the
presentation.
In our effort to continuously improve our products we thank you in advance for your comments, which
will help us in the preparing of further versions.
Piestany, August 2001
VPS s.r.o., P.O. Box B-11, Partizanska 31, 921 01 Piestany 1, Slovak Republic
tel., fax.: +421 33 7730151, email: [email protected]
Silicon V2.1 En
2
Controlling the Presentation
Mouse Control
Video
A click of the left mouse button, unless the
cursor is on a control button or on a video,
moves the presentation one step forward.
If there is a video on the slide, it is in the
brown frame, similarly to the picture below. By
locating the cursor on the video, the shape of
the cursor will change to  character. Clicking
on the left mouse button will start the video.
Clicking the left mouse on the running video
will stop it.
Keyboard Control
The N key has the same function as the left
mouse button (independent of the cursor
position). The P key has the opposite
function, it means one step backward. Press
Esc to finish the presentation.
Control Buttons on the Picture
By locating the cursor on a button, the shape
of the cursor will be changed into  character.
Clicking the left mouse will stimulate its
function then.
transition to the slide Contents
return to the last displayed slide
next slide
end of presentation
Silicon V2.1 En
If you do not notice an animation action
press the P key (Previous) and then start
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3
Contents
Introduction
What is Inside an Electronic Device?
Silicon
Silicon - the Structure
Silicon - Inside the Single Crystal
Crystalline Defects
Doping
Silicon Wafer
Silicon Obtaining
Polycrystalline Silicon
Czochralski Crystal Growth
Czochralski Puller
Crystal-Melt Interface
Oxygen and Carbon in Silicon Crystal
Segregation Coefficient
Single Crystal Ingot
Ingot Shaping and Testing
Cropped Ingot
Wafer Manufacturing
Wafer Edge Grinding
Double-Sided Lapping
Stress Relief Etching
Etching Machine
Backside Treatment
CVD Equipment
Polishing
Polishing Machine
Chemical Cleaning
Inspection
Scrubbing
Final Inspection
Epitaxy
Epitaxial Reactor
Epitaxial Layer Characteristics
Appendix
Clean Rooms
Some Special Units
Clicking on this box will navigate you to
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Silicon V2.1 En
4
Introduction
The company TEROSIL, a.s., located in
Roznov pod Radhostem, Czech Republic, is
producer of silicon single crystals, wafers and
epitaxial layers for microelectronic device
fabrication.
TEROSIL, a.s. is a non wholly owned
subsidiary of ON Semiconductor, global
supplier of high-performance broadband and
power management integrated circuits and
standard semiconductors.
Silicon V2.1 En
5
What is Inside an Electronic Device?
The
If
This
webasic
small
remove
material
piece
the of
black
of
matter
a material
chip
is is
called
a from
semiconductor
chip.
the After
package,
ansilicon.
we can see the
enlargement
weleads
can see
leading
its structure.
up to a small piece of
matter inside which the whole function of an
electronic device proceeds.
Silicon V2.1 En
6
Silicon
Silicon does
is available
not occur
in great
naturally
abundance
in its elemental
on the Earth.
state.The
It occurs
Earth in
is
made up offorms,
compound
approximately
the principal
40%ones
iron (Fe),
being28%
silicates
oxygen
and(O
quartz.
2) and
14,5% silicon.
Quartz
(SiO2) is
Inthe
theprimary
Earth´s source
crust, silicon
of silicon
is even
in thethe
semiconductor
second most
abundant element - the crust contains 28% of silicon.
industry.
Melting point
1 413°C
Boiling point
2 355°C
Density
2 332 kg/m3
Hardness
7 on Mohs´s scale
Energy bandgap
Eg = 1,12 eV
Atomic density
5 . 1022 atom/cm3
Silicon V2.1 En
Elements of the Earth
Si
Other
Fe
O2
7
Silicon - the Structure
It is
Silicon
If
Each
wenecessary
move
silicon
is a chemical
crystallographic
aatom
copy
to add
has
of element
this
that
four
structure
structure
silicon
neighbors,
fromis
has
the
by
diamond
1/4
which
group
of the
itIV
in thelattice.
type
main
forms
appropriate
diagonal,
Periodic
a bond
properties
It with.
istable.
both
based
thefor
on
original
semiconductor
a faceand
centered
the shifted
chips
cubic
structure
atoms
only
when
form
- the
aacube
diamond
atoms
withinatoms
type
the whole
lattice.
in itsvolume
verticesofand
the
in theare
chip
wall
arranged
centers.exactly according to this
structure. Such and arrangement is called
single crystal. A view of a fictitious observer
inside the silicon single crystal looks like the
following picture.
28,0885
Si
14
2,33 g/cm3
Silicon
Silicon V2.1 En
8
Silicon - Inside the Single Crystal
Silicon V2.1 En
9
Crystalline Defects
In screw
Any
An
A
fact,
atom
additional
edge
imperfection
variety
dislocation
dislocation
missing
atom
of defects
from
in occupying
can
the
appears
the
crystalline
be
does
regular
described
as
aexist.
site
if an
crystal
structure
inbetween
Defect
extra
as atomic
site
plane
is
visualization
gives
considered
regular
layers
has
rise
been
partly
sites
tocan
aainserted
defect.
vacancy.
iscut
be
called
with
A
defect
an
into
scissors
achieved
intersticial.
thecan
crystal.
and
byinfluence
selective
shifted each
the
etching
electrical
other.
of silicon
and mechanical
surface. The
properties
crystalline
of a
crystal. To
defects
could
demonstrate
then appear
various
like demonstrated
kinds of crystalline
on thedefects a
simplified crystalline structure is used (not silicon).
microphotograph.
Silicon V2.1 En
Vacancy
Edge dislocation
Interstitial
Screw dislocation
10
The range
Presence
Physically,
Only
a very
ofof
boron
small
some
dopant
presence
amount
chemical
concentration
ofcauses
elements
a dopant
used
a different
is
- dopants
sufficient
in themechanism
semiconductor
infor
silicon,
doping
of
can
silicon.
electric
14 to
20
3. Silicon
substantially
current
The
industry
unittransfer
is
of 10
a influence
dopant
in 10
silicon
concentration
the
of than
dopant
silicon
phosphorus
atoms/cm
electric
is the number
conductivity.
or
arsenic.
of dopant
lattice
Silicon
Boron,
itself
atoms
doped
22 atoms/cm
3usually
3. forwith
phosphorus,
with
per
contains
unit
boron
volume
5.10
is arsenic
called
of silicon,
the
and
P-type
antimony
.
silicon
given
arewhile
especially
in #atoms/cm
siliconused
doped
this
purpose.
phosphorus,
arsenic or antimony is called the N-type one.
B
Boron
IV.A
30.97376
V.A
15
28.0855
P
Phosphorus
14
Si
Silicon
74,9216
33
As
Arsenic
121.75
51
Sb
(Negative)
5
III.A
Conductivity type N
10,81
(Positive)
Conductivity type P
Doping
Antimony
Silicon V2.1 En
11
Silicon Wafer
Secondary Flat
P <100>
Primary Flat
<111>
Silicon V2.1 En
A chip
For
The
that
silicon
crystallographic
conductivity
wafers
next
isreason,
very
slides
wafer
aresmall,
fabricated
will
many
(P
is provide
or
round-shaped.
just
orientation,
N)
chips
atype
by
few
deeper
are
cutting
and
square
processed
in aThe
respect
details
from
silicon
millimeters.
diameters
aof
to
wafer
athe
It would
together
of
crystallographic
monocrystalline
silicon
100,wafer
125,
be
in one
difficult,
150
surface,
manufacturing
slice
orientation
silicon
mmifof
or
not
iscylinder
semiconductor
important
more
even
are
process.
are
impossible,
encoded
pulled
commonly
for the
from
- silicon
in
wafer
to
amolten
used.
produce
wafer.
A
properties.
relative
silicon
100 mm
At
inposition
each
special
the
wafer
Inend
practice,
chip
of
equipment.
is
ofprimary
individually.
about
thethe
process
half
orientations
andofsecondary
millimeter
the wafer
according
is
flat
thick.
cut
onup
to
into pictures
Already
the
each
individual
wafer.
the wafer
The
are
chips.
used
top
material
side
andofthey
issilicon
doped
are wafer
classified
and itisishighly
Pasor
N-type or
<111>
polished.
then.
<100>.
<100>
12
Silicon Obtaining
Quartz
Although
At
Metallurgical
the very
highly
first
grade
step
pure,
silicon
the
thisquartz
silicon
is notsand
pure
doesisenough
not
transformed
formfor
the
into thecrystal
semiconductor
single
silicon.
lattice.
technology.
This silicon,
It is known
Thus
known
as
it is
as
a converted
polycrystalline
metallurgical
to
grade silicon,
trichlorsilane
silicon
or polysilicon.
(SiHCl
is obtained
by chemical
can be cleaned
reactionbyof
3), which
quartz
distillation,
The
polycrystalline
with and
carbon
then(C).
electronic
this trichlorsilane
grade silicon,
is reacted
the
with hydrogen
next
slide will show
(H2) to
how
produce
it lookshighly
like, is
purified
the raw
electronicforgrade
material
single
silicon.
crystal production.
SiO2 + 2C
Si + 2CO
Metallurgical grade silicon
Si + 3HCl
SiHCl3 + H2
Trichlorosilane
Trichlorosilane cleaning
SiHCl3 + H2
Silicon V2.1 En
Si + 3HCl
Electronic grade silicon
13
Polycristalline Silicon
Silicon V2.1 En
14
Chapter 1 Overview
Introduction
What is Inside an Electronic Device?
Silicon
Silicon - the Structure
Silicon - Inside the Single Crystal
Crystalline Defects
Doping
Silicon Wafer
Silicon Obtaining
Polycrystalline Silicon
Czochralski Crystal Growth
Czochralski Puller
Crystal-Melt Interface
Oxygen and Carbon in Silicon Crystal
Segregation Coefficient
Single Crystal Ingot
Ingot Shaping and Testing
Cropped Ingot
Silicon V2.1 En
Wafer Manufacturing
Wafer Edge Grinding
Double-Sided Lapping
Stress Relief Etching
Etching Machine
Backside Treatment
CVD Equipment
Polishing
Polishing Machine
Chemical Cleaning
Inspection
Scrubbing
Final Inspection
Epitaxy
Epitaxial Reactor
Epitaxial Layer Characteristics
Appendix
Clean Rooms
Some Special Units
15
Czochralski Crystal Growth
Onthe
Reachnig
The
Both
In
1918,
this
the
goal
crystallographic
polysilicon
pull
crystal
the
final
initial
enclosed
rate
Czochralski
growing
isthe
phase,
to
isphase,
isdesired
progressively
transform
then
charge
video,
crystal
the
the
decreased
orientation
described
diameter
pull
ispull
there
raw
and
melted
speed
rate
grown
materials
the
are
aand
of
is
in
crucible
is
"shoulder"
process
the
the
high
and
the
increased
the
particular
seed
into
quartz
pulled
to
diameter
rotate
in
maintain
awill
is
which
silicon
out
tobe
asofa
single
adapted
crucible.
a
formed
the
indicated
reduce
phases
small
crystal
melt.
crystal
crystal.
the
on
diameter
ofby
The
The
by
athe
is
crystal
growing
single
arrows.
increased
crystal
is
critical
The
growing
pulled
for
diameter.
quartz
crystal
crystal.
the
seed
The
process
from
crystal
to
growing
melt
crucible
ingot
the
isaItWhen
then
parameters
melt.
desired
has
is
shape.
growth
consumed,
crystal.
dipped
is
to
the
Since
loaded
be
size.
crystal
process.
chosen
This
into
then
that
This
with
the
must
body
this
in
the
method
polysilicon
accordance
silicon
procedure
second
be
therefore
is
removed
controlled
melt.
part
has
the
is
(see
from
to
The
of
been
called
crucible
are
the
photo)
the
seed
the
significally
final
initial
necking
melt
temperatures,
lifts
isand
silicon
growth
rotated
atoquick
the
and
keep
refined
wafer
dopant.
is
its
and
temperature
melt
called
purpose
the
orientation
and
simultaneously
level
A
pull
crowning.
remain
seed
rate,
is
at to
the
the
the
most popular
crystal
required.
pulled-up
eliminate
rotation
same
change
height.
isis
rates
also
dislocations
from
induced.
method
and
loaded
thelow
melt.
A thin
in
to
from
pressure
the
A
produce
"tail"
crystal
the
puller.
on
crystal.
argon
high
grows
the crystal
ambient.
quality
at theend
single
crystals. the
interface
reduces
following
impactthe
of thermal
crystallographic
shock onstructure
the rest of
the crystal.
seed.
Quartz crucible
Seed chuck rotation
Seed
Shoulder
chuck
Seed
Neck
Crown
Graphite crucible
(susceptor)
Body
Tail
Melt
Graphite heater
Crucible shaft
Crucible rotation
Silicon V2.1 En
16
Czochralski Puller
Argon inlet
A graphite
Finally,
The
An
isolation
quartz
lift
whole
Czochralski
(seed
the heating
system
last
crucible
valve
chuck
part
puller
allows
is
element
is
of
and
placed
the
supported
the
schematical
cable)
access
component
heat
isinplaced
vacuum
zone
holds
to
by upper
drawing
ais
around
the
graphite
containing
a
chamber
thermal
seed
chamber
can
the
crucible
and
be
the
with
shield
siliconkeeping
which
graphite
eliminating
growing
water-cooled
while
compared
serves
melt.
crystal
crucible
with
the
The
jacket.
simultaneously
the
heat
real
during
crucible
- controled
susceptor.
equipment
losses.
Monitoring
thematerial
process
ambient
aspicture
system
the
must
enabling
heat
innext.
lower
be
(pyrometer
susceptor.
chosen
the
vacuum
such
and
that itcrucibles
Both
controlled
camera)
chamber.
reacts
and
pullvery
computer
rate
areslowly
placed
and control
rotation.
with
on athe
the
graphite
melt.
growth
The
shaft
process.
only
enabling
material
the
rotation
thatand
canlifting.
be used is quartz.
Quartz crucible
Seed chuck
rotation
Cable
Seed chuck
Camera
(diameter control)
Isolation valve
Graphite crucible
Visor
Graphite heater
Thermal shield
Optical
pyrometer
Crucible shaft
Water
cooled jacket
To vacuum
pump
Electric current lead-in
Silicon V2.1 En
Crucible rotation
17
Crystal-Melt Interface
Melt
A
The
During
good
fundamental
area
crystallization
flows
crystal
control
between
are growth,
also
of process
the
takes
the
generated
temperature
the
melt
place
behind
melt
and
by
at
flow
crystal
the
the
atpattern
the
rotation
crystal-melt
growth
has
interface
to
inof
of
be
the
athe
between
maintained
interface.
crucible
crystal
involves
and
plays
the
The
the
atcrystal
the
an
shape
crucible
the
important
silicon
transformation
and
of the
and
the
freezing
role
interface
by
melt
pulling
ofis
point.
crystal-melt
of
crucial.
directly
aofliquid
This
theAisinto
good
thea
solid. Toof
control
coldest
influences
interface
crystal.
region
During
grow
shape
the
theheat
acrystalline
in
crystal
and
crystal,
the
flow
dopant
melt,
growth,
throughout
the
perfection
otherwise
atoms
variation.
a combination
of
the
and
solidification
the
The
interface
the
liquid
of is
must
the
will
impurity
spontaneous
crystal
occur
critical
organize
and
distribution
incondition
crucible
other
melt
themselves
parts
flow
rotation
throughout
fororiginates
that.
as well.
as
is they
used
the
Heat
from
become
section.
toinputs
generate
temperature
part
The
and the
of
the solid.melt
outputs
concave
differences
desired
must
shape
This
inflow
be
the
underlines
helps
monitored
-melt
right
to- bottom
left
remove
the
and
bottom
importance
picture.
be
dislocations
regulated
picture.
of good
and
to is
controlproper
insure
maintained
of the
during
process
crystal
thegrowth.
at
crystal
the interface
body growth.
between the
melt and the crystal.
Crystal
cross
section
(black)
Crystal - melt interface
Melt
Heat flow
Crystal rotation
Melt flow
Convex crystal-melt interface
Heat input
Heat output
no rotation
Silicon V2.1 En
Melt flow
Concave crystal-melt interface
Crucible rotation
18
Oxygen and Carbon in Silicon Crystal
Traces of
Oxygen
Carbon
impurities
isother
the most
impurities
originate
common
are
from
impurity
also
the
present
polysilicon
in silicon
in the
crystal.
charge
crystal.
Its
and
main the
from
Their
source
concentration
reaction
is thebetween
crucible
is lowerthe
material
than
graphite
that- quartz
ofheating
carbon
(SiO
element
and
they
2). This
surface
and
accumulate
silicon
is inmonoxide
in
contact
the melt
with
evaporated
residue
the silicon
leftfrom
inmelt.
the
thecrucible.
The
melt.
reaction
Carbon
between
has
muchthe
lower
silicon
concentration
melt and the
than
crucible
oxygen
produces
in the crystal.
silicon
monoxide (SiO). Most of the silicon monoxide evaporates
from the melt surface but a small quantity stays in the
melt.
CO, CO2
SiO
SiO + 2C
SiC + CO
CO, CO2
SiO
SiO
SiO
SiO
Quartz crucible
Graphite heater
Graphite crucible
Silicon V2.1 En
19
Segregation Coefficient
Element
Dopant Concentration/Resistivity
vs. Ingot Length (example)
10
dopants
metals
The
One
In
For
Most
the
example,
dopant
of
ofcrystal
the
elements
key
concentration
growth
phosphorus
operations
have
process,
segregation
has
in
in the
crystal
there
a crystal
segregation
coefficient
are
pulling
will
twois
be
phases
coefficient
less
the
introduction
lowest
thanatunity.
the
of
at 0,35.
the
interface
Due
oftop
aThat
to
specific
end
this,
-is,
the
and
near
only
amount
solid
thethe
ahighest
crystal
part
interface,
of of
dopant
and
at the
into liquid
the
dopant
bottom
the is
concentration
end
crystal.
melt.
integrated
of the
Between
The
ingot.
dopant
into
in the
the
An is
crystal
example
two
crystal.
added
phases,
will
The
to
ofbe
the
arest
0,35is
polysilicon
redistribution
times
rejected
dopant
the
concentration
back
concentration
charge
of
into
thethe
ordopant
melt
profile
melt.
of in
phosphorus
takes
Itthe
along
results
crucible.
place.
crystal
in in
dopant
This
the
is is
measured
melt.
accumulation
illustrated
Therefore,
on
in term
the
in the
in
graph
oforder
melt
a segregation
below.
as
to crystal
achieve
Heavy
coefficient
growth
ametals
given
as a ratio
dopant
proceeds.
have
very
level
of
low
Inconcentrations
in
turn,
segregation
thebecause
crystal, the
coefficients
the
of the
dopant
concentration
dopant
which
in
the twoinphases.
concentration
increases
results
further
in the
in melt,
the
material
melt
the has
purification.
dopant
to be
concentration
appropriately
increases
in the
higher.
crystal as well.
Segregation
Coefficient
0,000008
0,000025
0,00003
0,0004
0,0007
0,023
0,07
0,3
0,35
0,8
1,25
Fe
Au
Ni
Cu
N
Sb
C
As
P
B
O
CSOLID
8
Segregation Coefficient: k =
CLIQUID
resistivity
8
7
6
6
800
0
200
C(p) = C0(1-p)k-1
400
600
Resistivity [mWcm]
Concentration [1019cm-3]
concentration
CSOLID = 3,5 x 1018 cm-3
CLIQUID = 1,0 x 1019 cm-3
L [mm]
p - normalized length (p = 1 for Lmax)
k - segregation coefficient
Silicon V2.1 En
20
Single Crystal Ingot
Silicon V2.1 En
21
Chapter 2 Overview
Introduction
What is Inside an Electronic Device?
Silicon
Silicon - the Structure
Silicon - Inside the Single Crystal
Crystalline Defects
Doping
Silicon Wafer
Silicon Obtaining
Polycrystalline Silicon
Czochralski Crystal Growth
Czochralski Puller
Crystal-Melt Interface
Oxygen and Carbon in Silicon Crystal
Segregation Coefficient
Single Crystal Ingot
Ingot Shaping and Testing
Cropped Ingot
Silicon V2.1 En
Wafer Manufacturing
Wafer Edge Grinding
Double-Sided Lapping
Stress Relief Etching
Etching Machine
Backside Treatment
CVD Equipment
Polishing
Polishing Machine
Chemical Cleaning
Inspection
Scrubbing
Final Inspection
Epitaxy
Epitaxial Reactor
Epitaxial Layer Characteristics
Appendix
Clean Rooms
Some Special Units
22
Ingot Shaping and Testing
During
The
Crystallographic
pulled
crystal
photograph
the cropping
ingot
section
of
is
orientation
cut
finished
isofplaced
into
the crystal,
individual
silicon
ofinthe
thecylinder
single
agrinding
few
sections.
thin
crystal
axis
machine
slices
This
iscylinder
given
are
operation
and
removed
by
with
the
theflat
isseed
for
is
called
testing.
machine
orientation.
on
the cropping.
next
Usually
grinds
To
slide.
identify
resistivity
down
Each the
section
a radial
crystal
profiles,
iscrystallographic
examided
until
oxygen
the target
and
for defects.
carbon
orientation
diameter
Also,
ofofthe
the
ends ofathe
concentration
cylinder
crystal
isflat
reached.
ingot
isand
ground
are
crystallographic
removed.
into it. Knowing
defects
the orientation,
are tested. the
Theposition
set of
slices
of
the allows
flat is accurately
to verify the
determined
variation of
bymeasured
X-ray diffraction.
parameters.
X-ray source
Detector
Silicon V2.1 En
23
Cropped Ingot
Silicon V2.1 En
24
Chapter 3 Overview
Introduction
What is Inside an Electronic Device?
Silicon
Silicon - the Structure
Silicon - Inside the Single Crystal
Crystalline Defects
Doping
Silicon Wafer
Silicon Obtaining
Polycrystalline Silicon
Czochralski Crystal Growth
Czochralski Puller
Crystal-Melt Interface
Oxygen and Carbon in Silicon Crystal
Segregation Coefficient
Single Crystal Ingot
Ingot Shaping and Testing
Cropped Ingot
Silicon V2.1 En
Wafer Manufacturing
Wafer Edge Grinding
Double-Sided Lapping
Stress Relief Etching
Etching Machine
Backside Treatment
CVD Equipment
Polishing
Polishing Machine
Chemical Cleaning
Inspection
Scrubbing
Final Inspection
Epitaxy
Epitaxial Reactor
Epitaxial Layer Characteristics
Appendix
Clean Rooms
Some Special Units
25
Wafer Manufacturing
The damage
When
first
saw
cutting
step
is made
comes
in
wafers
the
of production
afrom
from
thinthe
astainless
crystal,
fact
of silicon
that
itsteel
issawing
desired
wafers
withprocess
afrom
tohole
a crystal
in
make
is
really
the a
center.
flat
aingot
form
cut
Aisof
at
nickel
sawing.
grinding.
a specific
matrix
A graphite
The
angle
withdamage
imbedded
with
beam
respect
exists
is diamond
attached
to the
to the crystal
particles
crystal
wherever
orientation
isthe
plated
with
blade
around
an
and
comes
adhesive
to waste
the
in contact
inner
toashold
little
edge
with
the
material
ofthe
wafer
thecrystal.
blade.
as
after
the saw
This
possible
Therefore,
diamond-nickel
blade
with
theahas
damaged
minimum
cut
matrix
through
material
of provides
damage
thehas
ingot.
of
ato
surface
the
bewafers.
removed
which
is used
For
in
the
that
subsequent
to
the
cutblade
the silicon
is
steps.
cooled
ingot.
Onand
the rinsed
enclosed
by water
video,with
surfactant.
there
is a shot of sawing process.
VIDEO 352 x 288
Stainless steel core
Silicon
Nickel matrix with
imbedded diamond
Damage
particles
Silicon V2.1 En
26
Wafer Edge Grinding
Aftergrinding
The
wafer
sawing,
is placed
wheel
the wafers
isona vacuum
disc
have
with
anchuck
groove
edgeand
with
of
sharp corners.
slowly
desired
turned
"bulletas
nose"
The
theedge
grinding
shape
is ground
ofwheel,
wafertowhich
edge.
form is
a
There
bullet
rotating
are
embedded
shaped
at highedge.
diamond
speed,
This
isparticles
increases
forced against
in edge
the groove.
the
strength
wafer
edge.
and make the edges less prone to
chipping in later processing.
High speed
Low speed
Silicon V2.1 En
27
Double-Sided Lapping
Theabrasive
During
An
next
silicon
lapping,
step
wafers
slurry
inwafers
wafer
in
(aluminium
carriers
production
are placed
and
oxide
the
is
in Al
called
abottom
O3
and
2carrier
lapping.
are
suspended
lapping
driven
plate
Purpose
between
inare
water
visible
of two
this
withcast
on
step
surfactant)
the
iron
is double
tomade
make
is fed
sided
lapping
wafer
to the
surfaceThe
plates.
wafers
planetary
surface
smooth,
lapper
carrier
asflat
video.
they
isand
thinner
are
Toparallel.
see
moved
than
thethe
wafers
between
wafersthe
allowingplates.
lapping
movement
both
thesides
upper
This of
removes
lapping
the wafer
plate
thetosilicon
be
is lifted
lapped
and
for
simultaneously.
leaves
demonstration.
behind aAt
more
the end
uniform
of the
surface.
video there
Wafers
is
are complete
the
very flat because
machinethe
during
lapping
the plates
lappingare
extremely flat.
process.
Lapping plate
Slurry
Carrier
VIDEO 352 x 288
Wafer
Gearing
Lapping plate
Silicon V2.1 En
28
Stress Relief Etching
In both
Since
One
Another
The
figure
method
lapping
forms
form
below
of
of
allows
etching
etching
etching,
shows
only
the
used
aalkaline
to
relative
wafers
remove
on silicon
and
is the
the
acid,
bulk
use
of an
wafers
comparison
there
thealkaline
are
saw
is acid
advantages
damage
ofhydroxide,
etching.
the etch
and
and
Arates
always
common
such
disadvantages
ofasleaves
a potassium
typical
mixture
a thin
to
uniform
hydroxide
used
acid
choosing
and
forlayer
acid
aa(KOH).
typical
specific
etching
of damage,
alkaline
Inform.
this
is HNO
method,
The
some
etch.
and
other
It the
can
HF.
onwafers
be
the
3 table
method
are
Sometimes,
seen
bottom
dipped
that
left
must
the
side
inadditional
KOH
be
acid
shows
used
etch
andto
chemicals
acontinues
water
comparison.
remove
mixture
the
are
to etch
added
for
damage
about
to
silicon
The
the
picture
2
mixture
wafer
minutes.
from
ofatlapping.
to
aachemical
make
The
high mixture
rate
This
theetching
reaction
for
damage
is
asusually
long
equipment
more
needs
asatthe
to beare
elevated
controllable.
two
and
chemical
removed
kept
temperature
In
inbath
while
any
contact.
iscase,
causing
on
ofTherefore
the
about
thenext
as
acid
100°C.
little
slide.
etching
the acid
Then
additional
the
process
etch
wafers
must
is damage
be
aare
vigorous
controlled
dipped
as process
possible.
into
very
a DI
closely
which
water
Typically,
to
needs
bath
end
the
to
chemical
stop
tight
up
with
anyanremaining
control
etching
acceptable
as it has
is used.
reaction.
no
wafer.
self limiting
properties.
Alkaline Etching
Si + H2O + 2KOH
K2SiO3 + 2H2
Acid Etching
3Si + 4HNO3 + 18HF
3H2SiF6 + 4NO + 8H2O
Si + 4HNO3 + 6HF
H2SiF6 + 4NO2 + 4H2O
Relative etching rates vs. time
Acid
Gives a surface that
contains etch pits
Gives a smooth
surface
Constant etch rates
over life of bath
Etch rate varies
Self limiting, easy to
control
No self limiting, hard
to control accurately
Does not release
EHS hazard
Releases gases that
must be scrubbed
Acid
Etch rate
Alkaline
Alkaline
Time (Stock Removal)
Silicon V2.1 En
29
Etching Machine
Silicon V2.1 En
30
Backside Treatment
A batch
For
Silicon
Polysilicon
wafers
dioxide
of silicon
on
thatthe
can
are
wafers
backside
be
highly
used
indoped
carrier
prevents
as a backseal.
and
prepared
out
are
going
The
diffusing
for
deposition
layer
to go
as
is through
well
deposited
is on
as getters
the
a high
on
bottom
the
temperature
heavy
wafer
picture.
metals
by You
process,
chemical
from
can
see
the abulk
avapor
chemical
layer
of deposition.
the
is deposited
vapor
wafer. deposition
Normally
The
onoxide
the back
a acts
silane
side 4of
strictly
(SiH
equipment
) source
as
theawafer
on
sealant.
is
the
used
tonext
prevent
for
slide.
polysilicon
the dopant from
out diffusing.
deposition.
Oxide Deposition
SiH4 + O2
420°C
Polysilicon Deposition
SiH4 620°C
Silicon V2.1 En
SiO2 + 2H2
Si + 2H2
31
CVD Equipment
Silicon V2.1 En
32
Polishing
The
One
A
polishing
purpose
video
of theshows
polishing
pad
of wafer
isthe
mounted
techniques
wafers
polishing
on
unloading
the
isisto
bottom
the
produce
template
right
plate.
after
a very
The
smooth,
mounting
soft
polishing.
insert
flat,
method.
Aispolishing
necessary
damage
Theequipment
free
wafers
to hold
silicon
are
the
is
surface.
situated
wafers
shown The
in
on
inplace
the
a round
polishing
template
when
next
slide.
the attached
step
wafers
is, are
unlike
onmounted
a carrier
lapping,
to
and
atheset
polishing
on a soft
chemical/mechanical
polyurethane
equipment
with
insert
the surface
inprocess.
the template.
facing
Thisdown.
difference
The insert
The bottom
is
has
thea
reason
porous
plate
and
polishing
structure.
carriersproduces
When
are rotating
theawafer
much
around
issmoother
pressed
their own
against
final
axis.
surface
the
water
than
soaked
lapping.
insert, it is held against it.
Slurry for Silicon Polishing
The polishing slurry consists of
silica (silicon dioxide, SiO2)
particles in aqueous suspension
with an organic alkali
and a surfactant.
Wafer
Carrier
Slurry
Insert
Template
Polishing pad
Bottom plate
Silicon V2.1 En
33
Polishing Machine
Silicon V2.1 En
34
Chemical Cleaning
At the
After
The
most
chemical
the
previous
this
time
wafers
cleaning,
common
commonly
of chemical
cleaning
steps
have
the
method
some
used
been
wafer
operation
cleaning,
method
metals
of
polished,
surface
cleaning
is
the
may
to
complemented
wafers
remove
is
they
still
the
freehave
wafers
remain
of
have
aa
large
after
thin
particles
on
by
contaminants,
megasonic
the
native
polishing
number
wafer
is oxide
the
surface.
of
cleaning.
is
however
SC1
contaminants
a
layer
wet
(Standard
The
on
cleaning
small
Megasonic
top
cleaning
and
amount
on
Clean
consisting
the
agent
waves
1)
surface.
contaminants
ofsolution.
particles
for
of
are
the
In
general,
several
are
This
metal
acoustic
may
mostly
mixture
be
contaminants
chemical
still
these
waves
on
present.
istop
contaminants
the
ofsteps.
of
very
hot
is
the
aNH
high
The
oxide
mixture
frequency
first
are
or
and
of
one
particles,
embedded
HCl
H2is
O(about
and
a in
hot
organic
water.
Hwithin
O2 in
4OH
2
21
residuals
mixture
it.
Ammonium
water.
MHz).
The
The
video
The
This
role
ofand
on
sulfuric
waves
of
mixture
hydroxide
right
the
metallic
subsequent
exert
acid
shows
is known
ions.
under-etches
and
forces
a hydrogen
cleaning
The
as
step,
on
SC2
chemical
particles
diluted
particles
line
(Standard
peroxide
and
cleaning
onawafer
shot
is designed
called
hydrofluoric
attached
Clean
surface
into
thePiranha.
2).and
megasonic
to
The
the
to
acid,
help
mixture
remove
It
surface
to
decomposes
is cleaning
detach
to oxidizes
etch
them.
andthem.
out
eliminates
bath.
virtually
and
the native
reacts
attractive
any
oxide
with
organics
and
on the wafer
polishing
forces.
metals
on
Hydrogen
slurry
thesurface
silicon
residuals.
peroxide
surface
into carbon
is and
oxidizing
dioxide
removes
agent
and
them.
to
water.
grow thin clean oxide layer on the wafer surface,
which makes it hydrophilic and prevents particles
re-deposition.
Particle
Organic residual
Metallic ion
Native SiO2
VIDEO 352 x 288
H2SO4 + H2O2 (130°C)
H2O + HF
H2O + NH4OH + H2O2 (70°C)
H2O + HCl + H2O2 (70°C)
Silicon V2.1 En
35
Inspection
After
A
The
measure
measurement
total
video
the wafers
indicator
shows
of theof
have
ashape
reading
the
non-contact
been
consistency
deformation
(TIR)
polished
automatic
is aofand
of
a wafer
a cleaned,
wafer is
they are
warp.
thickness
measurement
inspection
Warp
ready
isline.
is
total
the
that
to thickness
be
measure
is inspected.
only concerned
variation
of maximum
During
(TTV).
with
the
difference
the
It is
front
inspection
between
the
side
difference
of a the
wafer.
process,
highest
between
The the
way
and
the
resistivity
this
lowest
maximum
measurement
location
and and
geometrical
of the
is
parameters
centerline
minimum
made
is by
thickness
ofreference
are
a wafer
measured
ofwith
to
a wafer.
a respect
plane
by non-contact
that
to reference
is parallel to
methods.
plane
the
vacuum
defined
chuck
by three
that pedestals
the wafer is
near
mounted
the wafer
on.
edge.
The
TIR is the difference between the height of
the highest peak and the deepest valley on the
front of the wafer.
VIDEO 352 x 288
Wafer centerline
Wafer
Wafer
Tmax
hmax
Dmax
Tminh
Dmin
min
Reference
plane
Vacuum
chuck
Warp
TTV
TIR==(D
T
hmax
T
hmin
max -- D
min) / 2
Silicon V2.1 En
36
Scrubbing
Wafer
The
During
wafers
scrubbing
the scrubbing
are cleaned
with aqueous
thetoPVA
remove
brush
ammonium
particles
is very and
metal contamination
hydroxide
effective
for
(NH
particle
removal.
but after
across
After
inspection
the
DIwafer
water
may
surface
rinse
have
4OH) flows
anremove
to
and
increased
drying the
wafers
number
particles.
are of
prepared
Simultaneously
particlesfor
onfinal
the the
inspection
surface
again.
brushing
and
packaging.
The
is scrubbing
made by polyvinil
has to be
alcohol
used for
(PVA)
finalfibers
mechanical/chemical
which
Both
the
do scrubbing
not scratchand
the
cleaning.
the
wafer
subsequent
when brought
final into
direct contact
inspection
arewith
realized
the wafer
in clean
surface.
rooms of class 10.
The video on right shows a scrubbing operation.
Silicon V2.1 En
VIDEO 352 x 288
37
Final Inspection
Wafer Diameter:
TTV:
TIR:
WARP:
100, 125, 150 mm
< 5 µm
< 4 µm
< 30 µm
(typical for 100 mm wafers)
Particles >0,5 µm
Metal Contamination:
<5
 3x1010 atoms/cm2
for more specification: www.terosil.com
Silicon V2.1 En
38
Chapter 4 Overview
Introduction
What is Inside an Electronic Device?
Silicon
Silicon - the Structure
Silicon - Inside the Single Crystal
Crystalline Defects
Doping
Silicon Wafer
Silicon Obtaining
Polycrystalline Silicon
Czochralski Crystal Growth
Czochralski Puller
Crystal-Melt Interface
Oxygen and Carbon in Silicon Crystal
Segregation Coefficient
Single Crystal Ingot
Ingot Shaping and Testing
Cropped Ingot
Silicon V2.1 En
Wafer Manufacturing
Wafer Edge Grinding
Double-Sided Lapping
Stress Relief Etching
Etching Machine
Backside Treatment
CVD Equipment
Polishing
Polishing Machine
Chemical Cleaning
Inspection
Scrubbing
Final Inspection
Epitaxy
Epitaxial Reactor
Epitaxial Layer Characteristics
Appendix
Clean Rooms
Some Special Units
39
Epitaxy
For
Epitaxy
The
After
If
there
particular
process
result
theare
issurface
the
ofany
proceeds
the
applications
growth
phosphine
process
etching
ofatthe
is
high
isthere
(PH
finished,
silicon
from
temperature
a
molecules
alayer
few
need
thetoon
silicon
tens
toabout
the
present,
form
silicon
1200
a
3)is
layerphosphorus
wafer
°C.
chloride
the
micrometers
Hydrogen
of
surface.
high
(SiHCl
resistivity
thick
flows
The
vapors
epitaxial
layer
past
material
dope
are
has
thelayer.
introduced.
the
incandescent
theon
growing
same
top ofSiHCl
epitaxial
lower
silicon
3)atoms
3 reacts
resistivity
crystallographic
wafers.
with
layer.
On
the
present
Boron
enclosed
When
material.
compounds
hydrogen
hydrogen
properties
video,
Theatepitaxial
there
chloride
can
a as
high
be
are
thetemperature.
used
growth
is
the
substrate,
added,
shots
forisdoping
used
itofbut
starts
The
thefor
itascan
this
purpose.
have
reacting
result
well.
wafers
aofloading
different
with
this reaction
silicon
on
dopant
a and
susceptor
areconcentration
itfree
etches
silicon
andthe
their
atoms
wafer
or unloading.
even
surface
that
different
settle
dopant.
away.
on
You
the
can
Itsilicon
is
also
important
see
wafer
thesurface
tocontrol
remove
following
board
all the
of its
an
contaminants
crystal
epitaxial
lattice
or
surface defects of the silicon structure.
structure.
reactor.
H
Cl
Cl Si H
H
H Cl
H Cl
H
H Cl
H
P H
H
Silicon V2.1 En
H Cl
H
H
Cl
Cl Si H
Cl
Si
Si
Si P
Si
Si
H
VIDEO 320 x 240
H
Cl
H Cl Si H
H Cl
H Cl
40
Epitaxial Reactor
N2
H2
HCl
SiHCl3
PH3
At this extremely
Epitaxial
During
the
reactor
process,
ishigh
an
the
equipment
temperature,
chamber for
with
the
the
the
process
growth
wafersofis
the epitaxial
flushed
proceeds
with
in the
nitrogen
layer.
way
Silicon
described
and hydrogen.
wafers
onare
theIn
loaded
slide
the Epitaxy.
on a
graphite
hydrogen
The
susceptor
block
environment
-with
susceptor.
wafers
the is
susceptor
The
cooled
susceptor
down
with is
wafers
then
placed
and
is
insidenitrogen
warmed
after
a quartz
up byflushing
the
glass
induction
bell-shaped
it is taken
heating
out
chamber.
at
from
thethe
Around
the chamber,ofthere
temperature
chamber.
about
is 1200°C.
an induction heating coil.
B2H6
gas exhaust
Silicon V2.1 En
41
Epitaxial Layer
Characteristics
Wafer Diameter:
Epi Layer Thickness:
Epi Layer Resistivity:
100, 150 mm
3 - 50 µm
3 - 50 Wcm
for more specification: www.terosil.com
Silicon V2.1 En
42
Chapter 5 Overview
Introduction
What is Inside an Electronic Device?
Silicon
Silicon - the Structure
Silicon - Inside the Single Crystal
Crystalline Defects
Doping
Silicon Wafer
Silicon Obtaining
Polycrystalline Silicon
Czochralski Crystal Growth
Czochralski Puller
Crystal-Melt Interface
Oxygen and Carbon in Silicon Crystal
Segregation Coefficient
Single Crystal Ingot
Ingot Shaping and Testing
Cropped Ingot
Silicon V2.1 En
Wafer Manufacturing
Wafer Edge Grinding
Double-Sided Lapping
Stress Relief Etching
Etching Machine
Backside Treatment
CVD Equipment
Polishing
Polishing Machine
Chemical Cleaning
Inspection
Scrubbing
Final Inspection
Epitaxy
Epitaxial Reactor
Epitaxial Layer Characteristics
Appendix
Clean Rooms
Some Special Units
43