<s>
A	O
hardmask	B-Algorithm
is	O
a	O
material	O
used	O
in	O
semiconductor	O
processing	O
as	O
an	O
etch	O
mask	O
instead	O
of	O
a	O
polymer	O
or	O
other	O
organic	O
"	O
soft	O
"	O
resist	O
material	O
.	O
</s>
<s>
Hardmasks	B-Algorithm
are	O
necessary	O
when	O
the	O
material	O
being	O
etched	B-Algorithm
is	O
itself	O
an	O
organic	O
polymer	O
.	O
</s>
<s>
This	O
arises	O
,	O
for	O
instance	O
,	O
in	O
the	O
patterning	O
of	O
low-κ	B-Algorithm
dielectric	I-Algorithm
insulation	O
layers	O
used	O
in	O
VLSI	O
fabrication	O
.	O
</s>
<s>
Polymers	O
tend	O
to	O
be	O
etched	B-Algorithm
easily	O
by	O
oxygen	O
,	O
fluorine	O
,	O
chlorine	O
and	O
other	O
reactive	O
gases	O
used	O
in	O
plasma	B-Algorithm
etching	I-Algorithm
.	O
</s>
<s>
Use	O
of	O
a	O
hardmask	B-Algorithm
involves	O
an	O
additional	O
deposition	O
process	O
,	O
and	O
hence	O
additional	O
cost	O
.	O
</s>
<s>
First	O
,	O
the	O
hardmask	B-Algorithm
material	O
is	O
deposited	O
and	O
etched	B-Algorithm
into	O
the	O
required	O
pattern	O
using	O
a	O
standard	O
photoresist	O
process	O
.	O
</s>
<s>
Following	O
that	O
the	O
underlying	O
material	O
can	O
be	O
etched	B-Algorithm
through	O
the	O
hardmask	B-Algorithm
.	O
</s>
<s>
Finally	O
the	O
hardmask	B-Algorithm
is	O
removed	O
with	O
a	O
further	O
etching	B-Algorithm
process	O
.	O
</s>
<s>
Hardmask	B-Algorithm
materials	O
can	O
be	O
metal	O
or	O
dielectric	O
.	O
</s>
<s>
Silicon	O
based	O
masks	O
such	O
as	O
silicon	O
dioxide	O
or	O
silicon	O
carbide	O
are	O
usually	O
used	O
for	O
etching	B-Algorithm
low-κ	B-Algorithm
dielectrics	I-Algorithm
.	O
</s>
<s>
For	O
this	O
material	O
,	O
metal	O
or	O
amorphous	O
carbon	O
hardmasks	B-Algorithm
are	O
used	O
.	O
</s>
<s>
The	O
most	O
common	O
metal	O
for	O
hardmasks	B-Algorithm
is	O
titanium	O
nitride	O
,	O
but	O
tantalum	O
nitride	O
has	O
also	O
been	O
used	O
.	O
</s>
