<s>
The	O
lift-off	B-Algorithm
process	O
in	O
microstructuring	O
technology	O
is	O
a	O
method	O
of	O
creating	O
structures	O
(	O
patterning	O
)	O
of	O
a	O
target	O
material	O
on	O
the	O
surface	O
of	O
a	O
substrate	B-Architecture
(	O
e.g.	O
</s>
<s>
wafer	B-Architecture
)	O
using	O
a	O
sacrificial	O
material	O
(	O
e.g.	O
</s>
<s>
It	O
is	O
an	O
additive	O
technique	O
as	O
opposed	O
to	O
more	O
traditional	O
subtracting	O
technique	O
like	O
etching	B-Algorithm
.	O
</s>
<s>
photoresist	O
)	O
,	O
deposited	O
on	O
the	O
surface	O
of	O
the	O
substrate	B-Architecture
.	O
</s>
<s>
This	O
is	O
done	O
by	O
etching	B-Algorithm
openings	O
through	O
the	O
layer	O
so	O
that	O
the	O
target	O
material	O
can	O
reach	O
the	O
surface	O
of	O
the	O
substrate	B-Architecture
in	O
those	O
regions	O
,	O
where	O
the	O
final	O
pattern	O
is	O
to	O
be	O
created	O
.	O
</s>
<s>
The	O
target	O
material	O
is	O
deposited	O
over	O
the	O
whole	O
area	O
of	O
the	O
wafer	B-Architecture
,	O
reaching	O
the	O
surface	O
of	O
the	O
substrate	B-Architecture
in	O
the	O
etched	O
regions	O
and	O
staying	O
on	O
the	O
top	O
of	O
the	O
sacrificial	O
layer	O
in	O
the	O
regions	O
,	O
where	O
it	O
was	O
not	O
previously	O
etched	O
.	O
</s>
<s>
After	O
the	O
lift-off	B-Algorithm
,	O
the	O
target	O
material	O
remains	O
only	O
in	O
the	O
regions	O
where	O
it	O
had	O
a	O
direct	O
contact	O
with	O
the	O
substrate	B-Architecture
.	O
</s>
<s>
Depending	O
on	O
the	O
resist	O
various	O
methods	O
can	O
be	O
used	O
,	O
such	O
as	O
Extreme	B-Algorithm
ultraviolet	I-Algorithm
lithography	I-Algorithm
-	O
EUVL	B-Algorithm
or	O
Electron	B-Architecture
beam	I-Architecture
lithography	I-Architecture
-	O
EBL	B-Architecture
.	O
</s>
<s>
Target	O
material	O
(	O
usually	O
a	O
thin	O
metal	O
layer	O
)	O
is	O
deposited	O
(	O
on	O
the	O
whole	O
surface	O
of	O
the	O
wafer	B-Architecture
)	O
.	O
</s>
<s>
This	O
layer	O
covers	O
the	O
remaining	O
resist	O
as	O
well	O
as	O
parts	O
of	O
the	O
wafer	B-Architecture
that	O
were	O
cleaned	O
of	O
the	O
resist	O
in	O
the	O
previous	O
developing	O
step	O
.	O
</s>
<s>
Lift-off	B-Algorithm
is	O
applied	O
in	O
cases	O
where	O
a	O
direct	O
etching	B-Algorithm
of	O
structural	O
material	O
would	O
have	O
undesirable	O
effects	O
on	O
the	O
layer	O
below	O
.	O
</s>
<s>
Lift-off	B-Algorithm
is	O
a	O
cheap	O
alternative	O
to	O
etching	B-Algorithm
in	O
a	O
research	O
context	O
,	O
which	O
permits	O
a	O
slower	O
turn-around	O
time	O
.	O
</s>
<s>
Finally	O
,	O
lifting	O
off	O
a	O
material	O
is	O
an	O
option	O
if	O
there	O
is	O
no	O
access	O
to	O
an	O
etching	B-Algorithm
tool	O
with	O
the	O
appropriate	O
gases	O
.	O
</s>
<s>
There	O
are	O
3	O
major	O
problems	O
with	O
lift-off	B-Algorithm
:	O
</s>
<s>
If	O
this	O
problem	O
occurs	O
,	O
unwanted	O
parts	O
of	O
the	O
metal	O
layer	O
will	O
remain	O
on	O
the	O
wafer	B-Architecture
.	O
</s>
<s>
Also	O
,	O
it	O
is	O
possible	O
that	O
the	O
metal	O
has	O
adhered	O
so	O
well	O
to	O
the	O
parts	O
that	O
should	O
remain	O
that	O
it	O
prevents	O
lift-off	B-Algorithm
.	O
</s>
<s>
Also	O
,	O
it	O
is	O
possible	O
that	O
these	O
ears	O
will	O
fall	O
over	O
on	O
the	O
surface	O
,	O
causing	O
an	O
unwanted	O
shape	O
on	O
the	O
substrate	B-Architecture
.	O
</s>
<s>
If	O
the	O
ears	O
remain	O
on	O
the	O
surface	O
,	O
the	O
risk	O
remains	O
that	O
these	O
ears	O
will	O
go	O
through	O
different	O
layers	O
put	O
on	O
top	O
of	O
the	O
wafer	B-Architecture
and	O
they	O
might	O
cause	O
unwanted	O
connections	O
.	O
</s>
<s>
It	O
is	O
very	O
difficult	O
to	O
remove	O
these	O
particles	O
after	O
the	O
wafer	B-Architecture
has	O
dried	O
.	O
</s>
<s>
Lift-off	B-Algorithm
process	O
is	O
used	O
mostly	O
to	O
create	O
metallic	O
interconnections	O
.	O
</s>
<s>
There	O
are	O
several	O
types	O
of	O
lift-off	B-Algorithm
processes	O
,	O
and	O
what	O
can	O
be	O
achieved	O
depends	O
highly	O
on	O
the	O
actual	O
process	O
being	O
used	O
.	O
</s>
<s>
Very	O
fine	O
structures	O
have	O
been	O
used	O
using	O
EBL	B-Architecture
,	O
for	O
instance	O
.	O
</s>
<s>
The	O
lift-off	B-Algorithm
process	O
can	O
also	O
involve	O
multiple	O
layers	O
of	O
different	O
types	O
of	O
resist	O
.	O
</s>
