<s>
Semiconductor	B-Architecture
device	I-Architecture
fabrication	I-Architecture
is	O
the	O
process	O
used	O
to	O
manufacture	O
semiconductor	O
devices	O
,	O
typically	O
integrated	O
circuits	O
(	O
ICs	O
)	O
such	O
as	O
computer	O
processors	O
,	O
microcontrollers	O
,	O
and	O
memory	O
chips	O
(	O
such	O
as	O
NAND	O
flash	O
and	O
DRAM	O
)	O
that	O
are	O
present	O
in	O
everyday	O
electrical	O
and	O
electronic	O
devices	O
.	O
</s>
<s>
It	O
is	O
a	O
multiple-step	O
photolithographic	B-Algorithm
and	O
physico-chemical	O
process	O
(	O
with	O
steps	O
such	O
as	O
thermal	B-Algorithm
oxidation	I-Algorithm
,	O
thin-film	O
deposition	O
,	O
ion-implantation	O
,	O
etching	B-Algorithm
)	O
during	O
which	O
electronic	O
circuits	O
are	O
gradually	O
created	O
on	O
a	O
wafer	B-Architecture
,	O
typically	O
made	O
of	O
pure	O
single-crystal	O
semiconducting	O
material	O
.	O
</s>
<s>
The	O
fabrication	B-Architecture
process	I-Architecture
is	O
performed	O
in	O
highly	O
specialized	O
semiconductor	B-Algorithm
fabrication	I-Algorithm
plants	I-Algorithm
,	O
also	O
called	O
foundries	B-Algorithm
or	O
"	O
fabs	B-Algorithm
"	O
,	O
with	O
the	O
central	O
part	O
being	O
the	O
"	O
clean	O
room	O
"	O
.	O
</s>
<s>
In	O
more	O
advanced	O
semiconductor	O
devices	O
,	O
such	O
as	O
modern	O
14/10/7	O
nm	O
nodes	O
,	O
fabrication	B-Architecture
can	O
take	O
up	O
to	O
15	O
weeks	O
,	O
with	O
11	O
–	O
13	O
weeks	O
being	O
the	O
industry	O
average	O
.	O
</s>
<s>
Production	O
in	O
advanced	O
fabrication	B-Architecture
facilities	O
is	O
completely	O
automated	O
and	O
carried	O
out	O
in	O
a	O
hermetically	O
sealed	O
nitrogen	O
environment	O
to	O
improve	O
yield	O
(	O
the	O
percent	O
of	O
microchips	O
that	O
function	O
correctly	O
in	O
a	O
wafer	B-Architecture
)	O
,	O
with	O
automated	O
material	O
handling	O
systems	O
taking	O
care	O
of	O
the	O
transport	O
of	O
wafers	B-Architecture
from	O
machine	O
to	O
machine	O
.	O
</s>
<s>
Wafers	B-Architecture
are	O
transported	O
inside	O
FOUPs	B-Algorithm
,	O
special	O
sealed	O
plastic	O
boxes	O
.	O
</s>
<s>
All	O
machinery	O
and	O
FOUPs	B-Algorithm
contain	O
an	O
internal	O
nitrogen	O
atmosphere	O
.	O
</s>
<s>
The	O
insides	O
of	O
the	O
processing	O
equipment	O
and	O
FOUPs	B-Algorithm
is	O
kept	O
cleaner	O
than	O
the	O
surrounding	O
air	O
in	O
the	O
cleanroom	B-Application
.	O
</s>
<s>
Fabrication	B-Algorithm
plants	I-Algorithm
need	O
large	O
amounts	O
of	O
liquid	O
nitrogen	O
to	O
maintain	O
the	O
atmosphere	O
inside	O
production	O
machinery	O
and	O
FOUPs	B-Algorithm
,	O
which	O
are	O
constantly	O
purged	O
with	O
nitrogen	O
.	O
</s>
<s>
In	O
some	O
cases	O
this	O
allows	O
a	O
simple	O
die	O
shrink	O
of	O
a	O
currently	O
produced	O
chip	O
design	O
to	O
reduce	O
costs	O
,	O
improve	O
performance	O
,	O
and	O
increase	O
transistor	B-Application
density	O
(	O
number	O
of	O
transistors	B-Application
per	O
square	O
millimeter	O
)	O
without	O
the	O
expense	O
of	O
a	O
new	O
design	O
.	O
</s>
<s>
Early	O
semiconductor	O
processes	O
had	O
arbitrary	O
names	O
such	O
as	O
HMOS	O
III	O
,	O
CHMOS	O
V	O
.	O
Later	O
each	O
new	O
generation	O
process	O
became	O
known	O
as	O
a	O
technology	O
node	O
or	O
process	O
node	O
,	O
designated	O
by	O
the	O
process	O
’s	O
minimum	O
feature	O
size	O
in	O
nanometers	O
(	O
or	O
historically	O
micrometers	O
)	O
of	O
the	O
process	O
's	O
transistor	B-Application
gate	O
length	O
,	O
such	O
as	O
the	O
"	O
90	O
nm	O
process	O
"	O
.	O
</s>
<s>
However	O
,	O
this	O
has	O
not	O
been	O
the	O
case	O
since	O
1994	O
,	O
and	O
the	O
number	O
of	O
nanometers	O
used	O
to	O
name	O
process	O
nodes	O
(	O
see	O
the	O
International	O
Technology	O
Roadmap	O
for	O
Semiconductors	O
)	O
has	O
become	O
more	O
of	O
a	O
marketing	O
term	O
that	O
has	O
no	O
relation	O
with	O
actual	O
feature	O
sizes	O
or	O
transistor	B-Application
density	O
(	O
number	O
of	O
transistors	B-Application
per	O
square	O
millimeter	O
)	O
.	O
</s>
<s>
Initially	O
transistor	B-Application
gate	O
length	O
was	O
smaller	O
than	O
that	O
suggested	O
by	O
the	O
process	O
node	O
name	O
(	O
e.g.	O
</s>
<s>
For	O
example	O
,	O
Intel	O
's	O
former	O
10	B-Algorithm
nm	I-Algorithm
process	I-Algorithm
actually	O
has	O
features	O
(	O
the	O
tips	O
of	O
FinFET	O
fins	O
)	O
with	O
a	O
width	O
of	O
7nm	B-Algorithm
,	O
so	O
the	O
Intel	O
10	B-Algorithm
nm	I-Algorithm
process	I-Algorithm
is	O
similar	O
in	O
transistor	B-Application
density	O
to	O
TSMC	O
's	O
7	B-Algorithm
nm	I-Algorithm
process	I-Algorithm
.	O
</s>
<s>
GlobalFoundries	O
 '	O
12	O
and	O
14nm	B-Algorithm
processes	O
have	O
similar	O
feature	O
sizes	O
.	O
</s>
<s>
An	O
improved	O
type	O
of	O
MOSFET	B-Architecture
technology	O
,	O
CMOS	B-Device
,	O
was	O
developed	O
by	O
Chih-Tang	O
Sah	O
and	O
Frank	O
Wanlass	O
at	O
Fairchild	O
Semiconductor	O
in	O
1963	O
.	O
</s>
<s>
CMOS	B-Device
was	O
commercialised	O
by	O
RCA	O
in	O
the	O
late	O
1960s	O
.	O
</s>
<s>
RCA	O
commercially	O
used	O
CMOS	B-Device
for	O
its	O
4000-series	O
integrated	O
circuits	O
in	O
1968	O
,	O
starting	O
with	O
a	O
20µm	O
process	O
before	O
gradually	O
scaling	O
to	O
a	O
10	B-Algorithm
µm	O
process	O
over	O
the	O
next	O
several	O
years	O
.	O
</s>
<s>
Samsung	B-Application
Electronics	O
,	O
the	O
world	O
's	O
largest	O
manufacturer	O
of	O
semiconductors	O
,	O
has	O
facilities	O
in	O
South	O
Korea	O
and	O
the	O
US	O
.	O
</s>
<s>
TSMC	O
,	O
the	O
world	O
's	O
largest	O
pure	O
play	O
foundry	B-Algorithm
,	O
has	O
facilities	O
in	O
Taiwan	O
,	O
China	O
,	O
Singapore	O
,	O
and	O
the	O
US	O
.	O
</s>
<s>
Qualcomm	O
and	O
Broadcom	O
are	O
among	O
the	O
biggest	O
fabless	B-Algorithm
semiconductor	I-Algorithm
companies	I-Algorithm
,	O
outsourcing	O
their	O
production	O
to	O
companies	O
like	O
TSMC	O
.	O
</s>
<s>
For	O
example	O
,	O
GlobalFoundries	O
 '	O
7	O
nm	O
process	O
is	O
similar	O
to	O
Intel	O
's	O
10	B-Algorithm
nm	O
process	O
,	O
thus	O
the	O
conventional	O
notion	O
of	O
a	O
process	O
node	O
has	O
become	O
blurred	O
.	O
</s>
<s>
Additionally	O
,	O
TSMC	O
and	O
Samsung	B-Application
's	O
10nm	B-Algorithm
processes	O
are	O
only	O
slightly	O
denser	O
than	O
Intel	O
's	O
14nm	B-Algorithm
in	O
transistor	B-Application
density	O
.	O
</s>
<s>
They	O
are	O
actually	O
much	O
closer	O
to	O
Intel	O
's	O
14nm	B-Algorithm
process	O
than	O
they	O
are	O
to	O
Intel	O
's	O
10nm	B-Algorithm
process	O
(	O
e.g.	O
</s>
<s>
Samsung	B-Application
's	O
10nm	B-Algorithm
processes	O
 '	O
fin	O
pitch	O
is	O
the	O
exact	O
same	O
as	O
that	O
of	O
Intel	O
's	O
14nm	B-Algorithm
process	O
:	O
42nm	O
)	O
.	O
</s>
<s>
As	O
of	O
2019	O
,	O
14	B-Algorithm
nanometer	I-Algorithm
and	O
10	B-Algorithm
nanometer	I-Algorithm
chips	O
are	O
in	O
mass	O
production	O
by	O
Intel	O
,	O
UMC	O
,	O
TSMC	O
,	O
Samsung	B-Application
,	O
Micron	O
,	O
SK	O
Hynix	O
,	O
Toshiba	O
Memory	O
and	O
GlobalFoundries	O
,	O
with	O
7	B-Algorithm
nanometer	I-Algorithm
process	O
chips	O
in	O
mass	O
production	O
by	O
TSMC	O
and	O
Samsung	B-Application
,	O
although	O
their	O
7nanometer	O
node	O
definition	O
is	O
similar	O
to	O
Intel	O
's	O
10	B-Algorithm
nanometer	I-Algorithm
process	O
.	O
</s>
<s>
The	O
5	B-Algorithm
nanometer	I-Algorithm
process	O
began	O
being	O
produced	O
by	O
Samsung	B-Application
in	O
2018	O
.	O
</s>
<s>
As	O
of	O
2019	O
,	O
the	O
node	O
with	O
the	O
highest	O
transistor	B-Application
density	O
is	O
TSMC	O
's	O
5nanometer	O
N5	O
node	O
,	O
with	O
a	O
density	O
of	O
171.3million	O
transistors	B-Application
per	O
square	O
millimeter	O
.	O
</s>
<s>
In	O
2019	O
,	O
Samsung	B-Application
and	O
TSMC	O
announced	O
plans	O
to	O
produce	O
3	B-Algorithm
nanometer	I-Algorithm
nodes	O
.	O
</s>
<s>
GlobalFoundries	O
has	O
decided	O
to	O
stop	O
the	O
development	O
of	O
new	O
nodes	O
beyond	O
12	O
nanometers	O
in	O
order	O
to	O
save	O
resources	O
,	O
as	O
it	O
has	O
determined	O
that	O
setting	O
up	O
a	O
new	O
fab	B-Algorithm
to	O
handle	O
sub-12nm	O
orders	O
would	O
be	O
beyond	O
the	O
company	O
's	O
financial	O
abilities	O
.	O
</s>
<s>
,	O
Samsung	B-Application
is	O
the	O
industry	O
leader	O
in	O
advanced	O
semiconductor	O
scaling	O
,	O
followed	O
by	O
TSMC	O
and	O
then	O
Intel	O
.	O
</s>
<s>
This	O
is	O
a	O
list	O
of	O
processing	O
techniques	O
that	O
are	O
employed	O
numerous	O
times	O
throughout	O
the	O
construction	O
of	O
a	O
modern	O
electronic	O
device	O
;	O
this	O
list	O
does	O
not	O
necessarily	O
imply	O
a	O
specific	O
order	O
,	O
nor	O
that	O
all	O
techniques	O
are	O
taken	O
during	O
manufacture	O
as	O
,	O
in	O
practice	O
the	O
order	O
and	O
which	O
techniques	O
are	O
applied	O
,	O
are	O
often	O
specific	O
to	O
process	O
offerings	O
by	O
foundries	B-Algorithm
,	O
or	O
specific	O
to	O
an	O
integrated	B-Algorithm
device	I-Algorithm
manufacturer	I-Algorithm
(	O
IDM	O
)	O
for	O
their	O
own	O
products	O
,	O
and	O
a	O
semiconductor	O
device	O
may	O
not	O
need	O
all	O
techniques	O
.	O
</s>
<s>
All	O
equipment	O
needs	O
to	O
be	O
tested	O
before	O
a	O
semiconductor	B-Algorithm
fabrication	I-Algorithm
plant	I-Algorithm
is	O
started	O
.	O
</s>
<s>
Additionally	O
steps	O
such	O
as	O
Wright	B-Algorithm
etch	I-Algorithm
may	O
be	O
carried	O
out	O
.	O
</s>
<s>
When	O
feature	O
widths	O
were	O
far	O
greater	O
than	O
about	O
10	B-Algorithm
micrometres	O
,	O
semiconductor	O
purity	O
was	O
not	O
as	O
big	O
of	O
an	O
issue	O
as	O
it	O
is	O
today	O
in	O
device	O
manufacturing	O
.	O
</s>
<s>
As	O
devices	O
become	O
more	O
integrated	O
,	O
cleanrooms	B-Application
must	O
become	O
even	O
cleaner	O
.	O
</s>
<s>
Today	O
,	O
fabrication	B-Algorithm
plants	I-Algorithm
are	O
pressurized	O
with	O
filtered	O
air	O
to	O
remove	O
even	O
the	O
smallest	O
particles	O
,	O
which	O
could	O
come	O
to	O
rest	O
on	O
the	O
wafers	B-Architecture
and	O
contribute	O
to	O
defects	O
.	O
</s>
<s>
The	O
ceilings	O
of	O
semiconductor	O
cleanrooms	B-Application
have	O
fan	O
filter	O
units	O
(	O
FFUs	O
)	O
at	O
regular	O
intervals	O
to	O
constantly	O
replace	O
and	O
filter	O
the	O
air	O
in	O
the	O
cleanroom	B-Application
;	O
semiconductor	O
capital	O
equipment	O
may	O
also	O
have	O
their	O
own	O
FFUs	O
.	O
</s>
<s>
The	O
workers	O
in	O
a	O
semiconductor	B-Architecture
fabrication	I-Architecture
facility	O
are	O
required	O
to	O
wear	O
cleanroom	B-Application
suits	O
to	O
protect	O
the	O
devices	O
from	O
human	O
contamination	O
.	O
</s>
<s>
To	O
prevent	O
oxidation	O
and	O
to	O
increase	O
yield	O
,	O
FOUPs	B-Algorithm
and	O
semiconductor	O
capital	O
equipment	O
may	O
have	O
a	O
hermetically	O
sealed	O
pure	O
nitrogen	O
environment	O
with	O
ISO	O
class	O
1	O
level	O
of	O
dust	O
.	O
</s>
<s>
FOUPs	B-Algorithm
and	O
SMIF	B-Algorithm
pods	O
isolate	O
the	O
wafers	B-Architecture
from	O
the	O
air	O
in	O
the	O
cleanroom	B-Application
,	O
increasing	O
yield	O
because	O
they	O
reduce	O
the	O
number	O
of	O
defects	O
caused	O
by	O
dust	O
particles	O
.	O
</s>
<s>
Also	O
,	O
fabs	B-Algorithm
have	O
as	O
few	O
people	O
as	O
possible	O
in	O
the	O
cleanroom	B-Application
to	O
make	O
maintaining	O
the	O
cleanroom	B-Application
environment	O
easier	O
,	O
since	O
people	O
,	O
even	O
when	O
wearing	O
cleanroom	B-Application
suits	O
,	O
shed	O
large	O
amounts	O
of	O
particles	O
,	O
especially	O
when	O
walking	O
.	O
</s>
<s>
A	O
typical	O
wafer	B-Architecture
is	O
made	O
out	O
of	O
extremely	O
pure	O
silicon	O
that	O
is	O
grown	O
into	O
mono-crystalline	O
cylindrical	O
ingots	O
(	O
boules	B-Algorithm
)	O
up	O
to	O
300mm	O
(	O
slightly	O
less	O
than	O
12inches	O
)	O
in	O
diameter	O
using	O
the	O
Czochralski	O
process	O
.	O
</s>
<s>
These	O
ingots	O
are	O
then	O
sliced	O
into	O
wafers	B-Architecture
about	O
0.75mm	O
thick	O
and	O
polished	O
to	O
obtain	O
a	O
very	O
regular	O
and	O
flat	O
surface	O
.	O
</s>
<s>
In	O
semiconductor	B-Architecture
device	I-Architecture
fabrication	I-Architecture
,	O
the	O
various	O
processing	O
steps	O
fall	O
into	O
four	O
general	O
categories	O
:	O
deposition	O
,	O
removal	O
,	O
patterning	O
,	O
and	O
modification	O
of	O
electrical	O
properties	O
.	O
</s>
<s>
Deposition	O
is	O
any	O
process	O
that	O
grows	O
,	O
coats	O
,	O
or	O
otherwise	O
transfers	O
a	O
material	O
onto	O
the	O
wafer	B-Architecture
.	O
</s>
<s>
Available	O
technologies	O
include	O
physical	O
vapor	O
deposition	O
(	O
PVD	O
)	O
,	O
chemical	B-Algorithm
vapor	I-Algorithm
deposition	I-Algorithm
(	O
CVD	B-Algorithm
)	O
,	O
electrochemical	O
deposition	O
(	O
ECD	O
)	O
,	O
molecular	B-Algorithm
beam	I-Algorithm
epitaxy	I-Algorithm
(	O
MBE	O
)	O
,	O
and	O
more	O
recently	O
,	O
atomic	O
layer	O
deposition	O
(	O
ALD	O
)	O
among	O
others	O
.	O
</s>
<s>
Deposition	O
can	O
be	O
understood	O
to	O
include	O
oxide	O
layer	O
formation	O
,	O
by	O
thermal	B-Algorithm
oxidation	I-Algorithm
or	O
,	O
more	O
specifically	O
,	O
LOCOS	B-Application
.	O
</s>
<s>
Removal	O
is	O
any	O
process	O
that	O
removes	O
material	O
from	O
the	O
wafer	B-Architecture
;	O
examples	O
include	O
etch	O
processes	O
(	O
either	O
wet	O
or	O
dry	O
)	O
and	O
chemical-mechanical	B-Algorithm
planarization	I-Algorithm
(	O
CMP	O
)	O
.	O
</s>
<s>
Patterning	O
is	O
the	O
shaping	O
or	O
altering	O
of	O
deposited	O
materials	O
,	O
and	O
is	O
generally	O
referred	O
to	O
as	O
lithography	B-Algorithm
.	O
</s>
<s>
For	O
example	O
,	O
in	O
conventional	O
lithography	B-Algorithm
,	O
the	O
wafer	B-Architecture
is	O
coated	O
with	O
a	O
chemical	O
called	O
a	O
photoresist	O
;	O
then	O
,	O
a	O
machine	O
called	O
an	O
aligner	O
or	O
stepper	B-Algorithm
focuses	O
a	O
mask	B-Algorithm
image	O
on	O
the	O
wafer	B-Architecture
using	O
short-wavelength	O
light	O
;	O
the	O
exposed	O
regions	O
(	O
for	O
"	O
positive	O
"	O
resist	O
)	O
are	O
washed	O
away	O
by	O
a	O
developer	O
solution	O
.	O
</s>
<s>
Modification	O
of	O
electrical	O
properties	O
has	O
historically	O
entailed	O
doping	B-Algorithm
transistor	B-Application
sources	O
and	O
drains	O
and	O
polysilicon	O
(	O
originally	O
by	O
diffusion	B-Algorithm
furnaces	I-Algorithm
and	O
later	O
by	O
ion	O
implantation	O
)	O
.	O
</s>
<s>
These	O
doping	B-Algorithm
processes	O
are	O
followed	O
by	O
furnace	O
annealing	O
or	O
,	O
in	O
advanced	O
devices	O
,	O
by	O
rapid	O
thermal	O
annealing	O
(	O
RTA	O
)	O
to	O
activate	O
the	O
dopants	O
.	O
</s>
<s>
Modification	O
of	O
electrical	O
properties	O
now	O
also	O
extends	O
to	O
the	O
reduction	O
of	O
a	O
material	O
's	O
dielectric	O
constant	O
in	O
low-κ	B-Algorithm
insulators	I-Algorithm
via	O
exposure	O
to	O
ultraviolet	O
light	O
in	O
UV	O
processing	O
(	O
UVP	O
)	O
.	O
</s>
<s>
Modification	O
is	O
frequently	O
achieved	O
by	O
oxidation	O
,	O
which	O
can	O
be	O
carried	O
out	O
to	O
create	O
semiconductor-insulator	O
junctions	O
,	O
such	O
as	O
in	O
the	O
local	B-Application
oxidation	I-Application
of	I-Application
silicon	I-Application
(	O
LOCOS	B-Application
)	O
to	O
fabricate	O
metal	B-Architecture
oxide	I-Architecture
field	I-Architecture
effect	I-Architecture
transistors	I-Architecture
.	O
</s>
<s>
FEOL	O
processing	O
refers	O
to	O
the	O
formation	O
of	O
the	O
transistors	B-Application
directly	O
in	O
the	O
silicon	O
.	O
</s>
<s>
The	O
raw	O
wafer	B-Architecture
is	O
engineered	O
by	O
the	O
growth	O
of	O
an	O
ultrapure	O
,	O
virtually	O
defect-free	O
silicon	O
layer	O
through	O
epitaxy	O
.	O
</s>
<s>
In	O
the	O
most	O
advanced	O
logic	O
devices	O
,	O
prior	O
to	O
the	O
silicon	O
epitaxy	O
step	O
,	O
tricks	O
are	O
performed	O
to	O
improve	O
the	O
performance	O
of	O
the	O
transistors	B-Application
to	O
be	O
built	O
.	O
</s>
<s>
Another	O
method	O
,	O
called	O
silicon	B-Algorithm
on	I-Algorithm
insulator	I-Algorithm
technology	O
involves	O
the	O
insertion	O
of	O
an	O
insulating	O
layer	O
between	O
the	O
raw	O
silicon	B-Architecture
wafer	I-Architecture
and	O
the	O
thin	O
layer	O
of	O
subsequent	O
silicon	O
epitaxy	O
.	O
</s>
<s>
This	O
method	O
results	O
in	O
the	O
creation	O
of	O
transistors	B-Application
with	O
reduced	O
parasitic	O
effects	O
.	O
</s>
<s>
In	O
dynamic	O
random-access	O
memory	O
(	O
DRAM	O
)	O
devices	O
,	O
storage	O
capacitors	O
are	O
also	O
fabricated	O
at	O
this	O
time	O
,	O
typically	O
stacked	O
above	O
the	O
access	O
transistor	B-Application
(	O
the	O
now	O
defunct	O
DRAM	O
manufacturer	O
Qimonda	O
implemented	O
these	O
capacitors	O
with	O
trenches	O
etched	O
deep	O
into	O
the	O
silicon	O
surface	O
)	O
.	O
</s>
<s>
This	O
occurs	O
in	O
a	O
series	O
of	O
wafer	B-Architecture
processing	O
steps	O
collectively	O
referred	O
to	O
as	O
BEOL	O
(	O
not	O
to	O
be	O
confused	O
with	O
back	O
end	O
of	O
chip	B-Architecture
fabrication	I-Architecture
,	O
which	O
refers	O
to	O
the	O
packaging	B-Algorithm
and	O
testing	O
stages	O
)	O
.	O
</s>
<s>
The	O
insulating	O
material	O
has	O
traditionally	O
been	O
a	O
form	O
of	O
SiO2	O
or	O
a	O
silicate	O
glass	O
,	O
but	O
recently	O
new	O
low	B-Algorithm
dielectric	I-Algorithm
constant	I-Algorithm
materials	O
are	O
being	O
used	O
(	O
such	O
as	O
silicon	O
oxycarbide	O
)	O
,	O
typically	O
providing	O
dielectric	O
constants	O
around	O
2.7	O
(	O
compared	O
to	O
3.82	O
for	O
SiO2	O
)	O
,	O
although	O
materials	O
with	O
constants	O
as	O
low	O
as	O
2.2	O
are	O
being	O
offered	O
to	O
chipmakers	B-Algorithm
.	O
</s>
<s>
High-κ	B-Algorithm
dielectrics	I-Algorithm
may	O
be	O
used	O
instead	O
.	O
</s>
<s>
The	O
various	O
metal	O
layers	O
are	O
interconnected	O
by	O
etching	B-Algorithm
holes	O
(	O
called	O
"	O
vias	O
"	O
)	O
in	O
the	O
insulating	O
material	O
and	O
then	O
depositing	O
tungsten	B-Application
in	O
them	O
with	O
a	O
CVD	B-Algorithm
technique	O
using	O
tungsten	B-Application
hexafluoride	O
;	O
this	O
approach	O
can	O
still	O
be	O
(	O
and	O
often	O
is	O
)	O
used	O
in	O
the	O
fabrication	B-Architecture
of	O
many	O
memory	O
chips	O
such	O
as	O
dynamic	O
random-access	O
memory	O
(	O
DRAM	O
)	O
,	O
because	O
the	O
number	O
of	O
interconnect	O
levels	O
can	O
be	O
small	O
(	O
no	O
more	O
than	O
four	O
)	O
.	O
</s>
<s>
More	O
recently	O
,	O
as	O
the	O
number	O
of	O
interconnect	O
levels	O
for	O
logic	O
has	O
substantially	O
increased	O
due	O
to	O
the	O
large	O
number	O
of	O
transistors	B-Application
that	O
are	O
now	O
interconnected	O
in	O
a	O
modern	O
microprocessor	B-Architecture
,	O
the	O
timing	O
delay	O
in	O
the	O
wiring	O
has	O
become	O
so	O
significant	O
as	O
to	O
prompt	O
a	O
change	O
in	O
wiring	O
material	O
(	O
from	O
aluminum	O
to	O
copper	O
interconnect	O
layer	O
)	O
and	O
a	O
change	O
in	O
dielectric	O
material	O
(	O
from	O
silicon	O
dioxides	O
to	O
newer	O
low-κ	B-Algorithm
insulators	I-Algorithm
)	O
.	O
</s>
<s>
As	O
the	O
number	O
of	O
interconnect	O
levels	O
increases	O
,	O
planarization	O
of	O
the	O
previous	O
layers	O
is	O
required	O
to	O
ensure	O
a	O
flat	O
surface	O
prior	O
to	O
subsequent	O
lithography	B-Algorithm
.	O
</s>
<s>
Without	O
it	O
,	O
the	O
levels	O
would	O
become	O
increasingly	O
crooked	O
,	O
extending	O
outside	O
the	O
depth	O
of	O
focus	O
of	O
available	O
lithography	B-Algorithm
,	O
and	O
thus	O
interfering	O
with	O
the	O
ability	O
to	O
pattern	O
.	O
</s>
<s>
CMP	O
(	O
chemical-mechanical	B-Algorithm
planarization	I-Algorithm
)	O
is	O
the	O
primary	O
processing	O
method	O
to	O
achieve	O
such	O
planarization	O
,	O
although	O
dry	O
etch	O
back	O
is	O
still	O
sometimes	O
employed	O
when	O
the	O
number	O
of	O
interconnect	O
levels	O
is	O
no	O
more	O
than	O
three	O
.	O
</s>
<s>
The	O
highly	O
serialized	O
nature	O
of	O
wafer	B-Architecture
processing	O
has	O
increased	O
the	O
demand	O
for	O
metrology	O
in	O
between	O
the	O
various	O
processing	O
steps	O
.	O
</s>
<s>
Wafer	B-Architecture
test	O
metrology	O
equipment	O
is	O
used	O
to	O
verify	O
that	O
the	O
wafers	B-Architecture
have	O
n't	O
been	O
damaged	O
by	O
previous	O
processing	O
steps	O
up	O
until	O
testing	O
;	O
if	O
too	O
many	O
dies	O
on	O
one	O
wafer	B-Architecture
have	O
failed	O
,	O
the	O
entire	O
wafer	B-Architecture
is	O
scrapped	O
to	O
avoid	O
the	O
costs	O
of	O
further	O
processing	O
.	O
</s>
<s>
Virtual	B-Algorithm
metrology	I-Algorithm
has	O
been	O
used	O
to	O
predict	O
wafer	B-Architecture
properties	O
based	O
on	O
statistical	O
methods	O
without	O
performing	O
the	O
physical	O
measurement	O
itself	O
.	O
</s>
<s>
The	O
percent	O
of	O
devices	O
on	O
the	O
wafer	B-Architecture
found	O
to	O
perform	O
properly	O
is	O
referred	O
to	O
as	O
the	O
yield	O
.	O
</s>
<s>
Manufacturers	O
are	O
typically	O
secretive	O
about	O
their	O
yields	O
,	O
but	O
it	O
can	O
be	O
as	O
low	O
as	O
30%	O
,	O
meaning	O
that	O
only	O
30%	O
of	O
the	O
chips	O
on	O
the	O
wafer	B-Architecture
work	O
as	O
intended	O
.	O
</s>
<s>
Process	B-Algorithm
variation	I-Algorithm
is	O
one	O
among	O
many	O
reasons	O
for	O
low	O
yield	O
.	O
</s>
<s>
As	O
an	O
example	O
,	O
In	O
December	O
2019	O
,	O
TSMC	O
announced	O
an	O
average	O
yield	O
of	O
~	O
80%	O
,	O
with	O
a	O
peak	O
yield	O
per	O
wafer	B-Architecture
of	O
>90	O
%	O
for	O
their	O
5nm	B-Algorithm
test	O
chips	O
with	O
a	O
die	O
size	O
of	O
17.92mm2	O
.	O
</s>
<s>
The	O
number	O
of	O
killer	O
defects	O
on	O
a	O
wafer	B-Architecture
,	O
regardless	O
of	O
die	O
size	O
,	O
can	O
be	O
noted	O
as	O
the	O
defect	O
density	O
(	O
or	O
D0	O
)	O
of	O
the	O
wafer	B-Architecture
per	O
unit	O
area	O
,	O
usually	O
cm2	O
.	O
</s>
<s>
The	O
fab	B-Algorithm
tests	B-Algorithm
the	I-Algorithm
chips	I-Algorithm
on	I-Algorithm
the	I-Algorithm
wafer	I-Algorithm
with	O
an	O
electronic	O
tester	O
that	O
presses	O
tiny	O
probes	O
against	O
the	O
chip	O
.	O
</s>
<s>
Currently	O
,	O
electronic	O
dye	O
marking	O
is	O
possible	O
if	O
wafer	B-Architecture
test	O
data	O
(	O
results	O
)	O
are	O
logged	O
into	O
a	O
central	O
computer	O
database	O
and	O
chips	O
are	O
"	O
binned	O
"	O
(	O
i.e.	O
</s>
<s>
The	O
resulting	O
binning	O
data	O
can	O
be	O
graphed	O
,	O
or	O
logged	O
,	O
on	O
a	O
wafer	B-Architecture
map	O
to	O
trace	O
manufacturing	O
defects	O
and	O
mark	O
bad	O
chips	O
.	O
</s>
<s>
This	O
map	O
can	O
also	O
be	O
used	O
during	O
wafer	B-Architecture
assembly	O
and	O
packaging	B-Algorithm
.	O
</s>
<s>
eFUSEs	B-Device
may	O
be	O
used	O
to	O
disconnect	O
parts	O
of	O
chips	O
such	O
as	O
cores	O
,	O
either	O
because	O
they	O
did	O
n't	O
work	O
as	O
intended	O
during	O
binning	O
,	O
or	O
as	O
part	O
of	O
market	O
segmentation	O
(	O
using	O
the	O
same	O
chip	O
for	O
low	O
,	O
mid	O
and	O
high-end	O
tiers	O
)	O
.	O
</s>
<s>
Chips	O
are	O
also	O
tested	O
again	O
after	O
packaging	B-Algorithm
,	O
as	O
the	O
bond	B-Algorithm
wires	I-Algorithm
may	O
be	O
missing	O
,	O
or	O
analog	O
performance	O
may	O
be	O
altered	O
by	O
the	O
package	O
.	O
</s>
<s>
Usually	O
,	O
the	O
fab	B-Algorithm
charges	O
for	O
testing	O
time	O
,	O
with	O
prices	O
in	O
the	O
order	O
of	O
cents	O
per	O
second	O
.	O
</s>
<s>
In	O
certain	O
designs	O
that	O
use	O
specialized	O
analog	O
fab	B-Algorithm
processes	O
,	O
wafers	B-Architecture
are	O
also	O
laser-trimmed	O
during	O
testing	O
,	O
in	O
order	O
to	O
achieve	O
tightly	O
distributed	O
resistance	O
values	O
as	O
specified	O
by	O
the	O
design	O
.	O
</s>
<s>
Good	O
designs	O
try	O
to	O
test	O
and	O
statistically	O
manage	O
corners	O
(	O
extremes	O
of	O
silicon	O
behavior	O
caused	O
by	O
a	O
high	O
operating	O
temperature	O
combined	O
with	O
the	O
extremes	O
of	O
fab	B-Algorithm
processing	O
steps	O
)	O
.	O
</s>
<s>
Device	O
yield	O
or	O
die	O
yield	O
is	O
the	O
number	O
of	O
working	O
chips	O
or	O
dies	O
on	O
a	O
wafer	B-Architecture
,	O
given	O
in	O
percentage	O
since	O
the	O
number	O
of	O
chips	O
on	O
a	O
wafer	B-Architecture
(	O
Die	O
per	O
wafer	B-Architecture
,	O
DPW	O
)	O
can	O
vary	O
depending	O
on	O
the	O
chips	O
 '	O
size	O
and	O
the	O
wafer	B-Architecture
's	O
diameter	O
.	O
</s>
<s>
Yield	O
degradation	O
is	O
a	O
reduction	O
in	O
yield	O
,	O
which	O
historically	O
was	O
mainly	O
caused	O
by	O
dust	O
particles	O
,	O
however	O
since	O
the	O
1990s	O
,	O
yield	O
degradation	O
is	O
mainly	O
caused	O
by	O
process	B-Algorithm
variation	I-Algorithm
,	O
the	O
process	O
itself	O
and	O
by	O
the	O
tools	O
used	O
in	O
chip	O
manufacturing	O
,	O
although	O
dust	O
still	O
remains	O
a	O
problem	O
in	O
many	O
older	O
fabs	B-Algorithm
.	O
</s>
<s>
Automation	O
and	O
the	O
use	O
of	O
mini	O
environments	O
inside	O
of	O
production	O
equipment	O
,	O
FOUPs	B-Algorithm
and	O
SMIFs	B-Algorithm
have	O
enabled	O
a	O
reduction	O
in	O
defects	O
caused	O
by	O
dust	O
particles	O
.	O
</s>
<s>
Device	O
yield	O
must	O
be	O
kept	O
high	O
to	O
reduce	O
the	O
selling	O
price	O
of	O
the	O
working	O
chips	O
since	O
working	O
chips	O
have	O
to	O
pay	O
for	O
those	O
chips	O
that	O
failed	O
,	O
and	O
to	O
reduce	O
the	O
cost	O
of	O
wafer	B-Architecture
processing	O
.	O
</s>
<s>
Yield	O
can	O
also	O
be	O
affected	O
by	O
the	O
design	O
and	O
operation	O
of	O
the	O
fab	B-Algorithm
.	O
</s>
<s>
"	O
Killer	O
defects	O
"	O
are	O
those	O
caused	O
by	O
dust	O
particles	O
that	O
cause	O
complete	O
failure	O
of	O
the	O
device	O
(	O
such	O
as	O
a	O
transistor	B-Application
)	O
.	O
</s>
<s>
There	O
is	O
no	O
universal	O
model	O
;	O
a	O
model	O
has	O
to	O
be	O
chosen	O
based	O
on	O
actual	O
yield	O
distribution	O
(	O
the	O
location	O
of	O
defective	O
chips	O
)	O
For	O
example	O
,	O
Murphy	O
's	O
model	O
assumes	O
that	O
yield	O
loss	O
occurs	O
more	O
at	O
the	O
edges	O
of	O
the	O
wafer	B-Architecture
(	O
non-working	O
chips	O
are	O
concentrated	O
on	O
the	O
edges	O
of	O
the	O
wafer	B-Architecture
)	O
,	O
Poisson	O
's	O
model	O
assumes	O
that	O
defective	O
dies	O
are	O
spread	O
relatively	O
evenly	O
across	O
the	O
wafer	B-Architecture
,	O
and	O
Seeds	O
's	O
model	O
assumes	O
that	O
defective	O
dies	O
are	O
clustered	O
together	O
.	O
</s>
<s>
Smaller	O
dies	O
cost	O
less	O
to	O
produce	O
(	O
since	O
more	O
fit	O
on	O
a	O
wafer	B-Architecture
,	O
and	O
wafers	B-Architecture
are	O
processed	O
and	O
priced	O
as	O
a	O
whole	O
)	O
,	O
and	O
can	O
help	O
achieve	O
higher	O
yields	O
since	O
smaller	O
dies	O
have	O
a	O
lower	O
chance	O
of	O
having	O
a	O
defect	O
,	O
due	O
to	O
their	O
lower	O
surface	O
area	O
on	O
the	O
wafer	B-Architecture
.	O
</s>
<s>
However	O
,	O
smaller	O
dies	O
require	O
smaller	O
features	O
to	O
achieve	O
the	O
same	O
functions	O
of	O
larger	O
dies	O
or	O
surpass	O
them	O
,	O
and	O
smaller	O
features	O
require	O
reduced	O
process	B-Algorithm
variation	I-Algorithm
and	O
increased	O
purity	O
(	O
reduced	O
contamination	O
)	O
to	O
maintain	O
high	O
yields	O
.	O
</s>
<s>
Metrology	O
tools	O
are	O
used	O
to	O
inspect	O
the	O
wafers	B-Architecture
during	O
the	O
production	O
process	O
and	O
predict	O
yield	O
,	O
so	O
wafers	B-Architecture
predicted	O
to	O
have	O
too	O
many	O
defects	O
may	O
be	O
scrapped	O
to	O
save	O
on	O
processing	O
costs	O
.	O
</s>
<s>
Once	O
tested	O
,	O
a	O
wafer	B-Architecture
is	O
typically	O
reduced	O
in	O
thickness	O
in	O
a	O
process	O
also	O
known	O
as	O
"	O
backlap	B-Algorithm
"	O
,	O
"	O
backfinish	O
"	O
or	O
"	O
wafer	B-Algorithm
thinning	I-Algorithm
"	O
before	O
the	O
wafer	B-Architecture
is	O
scored	O
and	O
then	O
broken	O
into	O
individual	O
dies	O
,	O
a	O
process	O
known	O
as	O
wafer	B-Algorithm
dicing	I-Algorithm
.	O
</s>
<s>
Plastic	O
or	O
ceramic	O
packaging	B-Algorithm
involves	O
mounting	O
the	O
die	O
,	O
connecting	O
the	O
die	O
pads	O
to	O
the	O
pins	O
on	O
the	O
package	O
,	O
and	O
sealing	O
the	O
die	O
.	O
</s>
<s>
Tiny	O
bondwires	B-Algorithm
are	O
used	O
to	O
connect	O
the	O
pads	O
to	O
the	O
pins	O
.	O
</s>
<s>
Traditionally	O
,	O
these	O
wires	O
have	O
been	O
composed	O
of	O
gold	O
,	O
leading	O
to	O
a	O
lead	B-Algorithm
frame	I-Algorithm
(	O
pronounced	O
"	O
leed	O
frame	O
"	O
)	O
of	O
solder-plated	O
copper	O
;	O
lead	O
is	O
poisonous	O
,	O
so	O
lead-free	O
"	O
lead	B-Algorithm
frames	I-Algorithm
"	O
are	O
now	O
mandated	O
by	O
RoHS	O
.	O
</s>
<s>
Chip	B-Algorithm
scale	I-Algorithm
package	I-Algorithm
(	O
CSP	O
)	O
is	O
another	O
packaging	B-Algorithm
technology	O
.	O
</s>
<s>
A	O
plastic	B-Algorithm
dual	I-Algorithm
in-line	I-Algorithm
package	I-Algorithm
,	O
like	O
most	O
packages	O
,	O
is	O
many	O
times	O
larger	O
than	O
the	O
actual	O
die	O
hidden	O
inside	O
,	O
whereas	O
CSP	O
chips	O
are	O
nearly	O
the	O
size	O
of	O
the	O
die	O
;	O
a	O
CSP	O
can	O
be	O
constructed	O
for	O
each	O
die	O
before	O
the	O
wafer	B-Architecture
is	O
diced	O
.	O
</s>
<s>
The	O
packaged	O
chips	O
are	O
retested	O
to	O
ensure	O
that	O
they	O
were	O
not	O
damaged	O
during	O
packaging	B-Algorithm
and	O
that	O
the	O
die-to-pin	O
interconnect	O
operation	O
was	O
performed	O
correctly	O
.	O
</s>
<s>
Many	O
toxic	O
materials	O
are	O
used	O
in	O
the	O
fabrication	B-Architecture
process	I-Architecture
.	O
</s>
<s>
poisonous	O
compounds	O
,	O
such	O
as	O
arsine	O
,	O
phosphine	O
,	O
tungsten	B-Application
hexafluoride	O
and	O
silane	O
.	O
</s>
<s>
The	O
high	O
degree	O
of	O
automation	O
common	O
in	O
the	O
IC	O
fabrication	B-Architecture
industry	O
helps	O
to	O
reduce	O
the	O
risks	O
of	O
exposure	O
.	O
</s>
<s>
Most	O
fabrication	B-Architecture
facilities	O
employ	O
exhaust	O
management	O
systems	O
,	O
such	O
as	O
wet	O
scrubbers	O
,	O
combustors	O
,	O
heated	O
absorber	O
cartridges	O
,	O
etc.	O
,	O
to	O
control	O
the	O
risk	O
to	O
workers	O
and	O
to	O
the	O
environment	O
.	O
</s>
