choice of ald precursors for microelectronics and...
TRANSCRIPT
Choice of ALD Precursors for Microelectronics and Nanoelectronics
Roy G. Gordon Harvard University Chemical Laboratories, Cambridge, MA 02138, USA [email protected] (617)495-4017
We review ALD processes that are applicable to the scaling of microelectronic devices to smaller dimensions, as well as to potential structures for future nanoelectronics. Effective candidate materials are given (in parenthesis) for each of the functions listed below:
High-k dielectric on Si (GdScO3)
High-k dielectric on Ge (HfOxNy)
High-k dielectric on GaAs (GdxGa1-xO3)
High-k dielectric on noble metals (Ta2O5)
Thermally stable metal gates (HfN, TaN)
Replacement metal gates (Ru, WN, CoSi2, NiSi)
Source/drain contacts (CoSi2, NiSi)
Pre-metal dielectric (carbon-doped silica)
Sealing the surfaces of porous low-k dielectrics (carbon-doped silica)
Copper diffusion barriers (WN)
Copper adhesion layers (Ru, Co)
Copper seed layers (Cu)
MRAM (Fe, Co, Ni, Ru, MgO)
Insulation for through-die interconnects (doped SiO2)
Coaxial gated transistors on single-walled carbon nanotubes (any high-k/metal combination, following non-covalent functionalization with NO2)
The most effective ALD precursors will be discussed for each of these applications. The considerations for each choice are volatility, thermal stability, reactivity, melting point and scalability of chemical synthesis.
Har
vard
Uni
vers
ity
Cho
ice
of A
LD P
recu
rsor
s fo
rM
icro
elec
tron
ics
and
Nan
oele
ctro
nics
Roy
G. G
ordo
nHa
rvar
d Un
iver
sity
Cam
brid
ge, M
A
Har
vard
Uni
vers
ity
Hig
h-k
Die
lect
rics
Mor
e St
able
Pre
curs
ors
for Z
ircon
ium
and
Haf
nium
Firs
t Pre
curs
ors
for A
LD o
f GdS
cO3
Inte
rcon
nect
s
ALD
/ C
VD R
uthe
nium
Glu
e La
yers
ALD
Cop
per S
eed
Laye
rs
Elec
trop
latin
g on
Cu
/ Ru
/ WN
Out
line
Har
vard
Uni
vers
ity
Hig
h-k
HfO
2or
ZrO
2w
ith v
ery
low
ele
ctric
al le
akag
e is
nee
ded
Why
Mor
e St
able
Hfa
nd Z
rPre
curs
ors?
Car
bon
impu
rity
in fi
lms
incr
ease
s le
akag
e
Ther
mal
dec
ompo
sitio
n of
org
anic
pre
curs
ors
adds
C to
film
s
Ther
mal
dec
ompo
sitio
n de
stro
ys u
nifo
rmity
and
con
fom
ality
Dep
ositi
on T
~ 4
00 o C
nee
ded
for H
fAlO
xw
ith A
LD A
l 2O3
Kno
wn
Hfp
recu
rsor
s de
com
pose
too
quic
kly
(exc
ept H
fCl 4,
whi
ch m
akes
non
-con
form
al fi
lms)
Har
vard
Uni
vers
ity
Cou
ple
met
hyla
min
e w
ith a
n al
kyln
itrile
and
depr
oton
ate
with
but
yllit
hium
:
Synt
hesi
s of
HfT
etra
-Am
idin
ates
2 H
2NC
H3
+ R
CN
1) L
a(C
F 3SO
3)3
2) B
uLi
NN
LiR
H3C
CH
3
Rea
ct th
e lit
hium
sal
t with
haf
nium
chl
orid
e:
+ H
fCl 4
CH
3
N
NC
H3
R
H3C
N
N CH
3R
CH
3N
N CH
3R
CH
3
N
NH
3C
R
Hf
NN
LiR
H3C
CH
3
Har
vard
Uni
vers
ity
X-ra
y st
ruct
ure
of
Zr(is
obut
yl2-
amd)
4
Stru
ctur
e of
a Z
rTet
ra-A
mid
inat
e
Zr1
N2 N1
N4
C1
N3A
C14
A
Har
vard
Uni
vers
ity
TG d
ata
for
Hf(M
e 2-a
md)
4
Prop
ertie
s of
a H
fAm
idin
ate
Hig
h th
erm
al s
tabi
lity:
No
resi
due
afte
r TG
No
chan
ge o
f NM
R a
fter h
eatin
g at
250
o C fo
r 1 w
eek
Har
vard
Uni
vers
ity
Mel
ting
Poin
ts o
f HfA
mid
inat
es
CH
3
N
NC
H3
R
H3C
N
N CH
3R
CH
3N
N CH
3R
CH
3
N
NH
3C
R
Hf
246
<20
CH
2CH
2CH
3
251
80C
H2C
H3
221
171
CH
3
TG T
½o C
Mel
ting
Poi
nt,o
CR
R =
CH
2CH
2CH
3(p
ropy
l) is
a li
quid
Hfp
recu
rsor
R =
CH
3(m
ethy
l) is
the
mos
t vol
atile
; so
lubl
e in
hyd
roca
rbon
s fo
r use
in d
irect
liqu
id in
ject
ion
ALD
exp
erim
ents
in p
rogr
ess
Har
vard
Uni
vers
ity
Adv
anta
ges
of G
dScO
3as
hig
h-di
elec
tric
Hig
h di
elec
tric
cons
tant
(k~2
2) fo
r am
orph
ous
pha
se
Sha
rp in
terfa
ce w
ith s
ilico
n, a
nd n
o lo
w-k
inte
rlaye
r
Sta
ys a
mor
phou
s an
d do
esn’
t for
mal
loys
with
Sio
r Ge
afte
r res
pect
ive
S/D
act
ivat
ion
proc
esse
s
Con
duct
ion
band
offs
et w
.r.t S
iis
abou
t 2-2
.5eV
,
help
ing
to a
chie
ve lo
w le
akag
e
Har
vard
Uni
vers
ity
Am
idin
ate
Prec
urso
rs fo
r Gd
and
Sc
M
NN
NN
NN
R2
R1
R2
R2
R1
R1
R3
R3
R3
The
Rn
are
typi
cally
alk
yl g
roup
s: e
thyl
, iso
prop
yl, e
tc.
The
choi
ces
of R
naf
fect
the
reac
tivity
, sta
bilit
y an
d vo
latil
ity.
Har
vard
Uni
vers
ity
Som
e A
mid
inat
e Li
gand
s
CN
CN
C
CH
3C
H3
H3C H
3C
H3C
CH
3
CH
3
tert
-but
yl2-
acet
amid
inat
e
CH
NC
NH
C
CH
3
H3C H
3C
CH
3
CH
3
isop
ropy
l 2-ac
etam
idin
ate
CN
CN
H2
C
CH
3C
H3
H3C H
3CC
H3
ethy
l-ter
t-but
yl-a
ceta
mid
inat
e
Increasing ligand bulk
H2
CN
CN
H2
C
CH
3
C H2
CH
3
C H2
H3C
n-pr
opyl
2-ac
etam
dina
te
Har
vard
Uni
vers
ity
dd
mm
mm
n-pr
opyl
2
Bi
LaPr
Gd
YLu
ScR
uTi
VC
rG
aA
l
dd
mm
Et-te
rt-B
u
dm
mm
mm
mm
mm
mm
isop
ropy
l 2
dm
mm
mm
mc
tert
-but
yl2
Incr
easi
ng s
ize
of m
etal
ato
m
Increasing ligand bulk
m =
mon
omer
d =
dim
erc
= to
o cr
owde
d to
mak
e
Stru
ctur
es o
f Met
al(II
I) A
mid
inat
es
=> C
an’t
mak
e pr
ecur
sor i
f lig
ands
are
too
bulk
y fo
r a m
etal
=> D
imer
sar
e ne
arly
as
vola
tile
as m
onom
ers
Har
vard
Uni
vers
ity
rn-
prop
yl2
Bi
LaPr
Gd
YLu
ScR
uTi
VC
rG
aA
l
rr
Et-t B
u
rr
rr
rs
ss
sn
isop
ropy
l 2
rn
nn
nn
tert
-but
yl2
Incr
easi
ng s
ize
of m
etal
ato
m
Increasing ligand bulk
s =
slow
reac
tion
r = ra
pid
reac
tion
n =
no re
actio
n
Rea
ctiv
ity o
f Met
al(II
I) A
mid
inat
es w
ith H
2O
=> T
oo b
ulky
liga
nds
slow
or s
top
reac
tions
Har
vard
Uni
vers
ity
Pre
curs
ors
for G
dScO
3A
LD
Tris
Tris
-- diis
opro
pyla
ceta
mid
inat
odi
isop
ropy
lace
tam
idin
ato
Gad
olin
ium
(III)
G
adol
iniu
m (I
II)
Gd(
NG
d(N
22CC88HH
1717)) 33
Gd(
Gd(
ii Pr
Pr --
amd)
amd)
33
Bub
bler
Tem
p. :
140
Bub
bler
Tem
p. :
140
ºº CC
Ther
mal
ly S
tabl
e to
320
Th
erm
ally
Sta
ble
to 3
20 ºº
CC
Tris
Tris
-- die
thyl
acet
amid
inat
odi
ethy
lace
tam
idin
ato
Sca
ndiu
m (I
II)
Sca
ndiu
m (I
II)
Sc(
NS
c(N
22CC66HH
1313)) 33
Sc(
Et
Sc(
Et -- a
md)
amd)
33
Bub
bler
Tem
p. :
140
Bub
bler
Tem
p. :
140
ºº CC
Ther
mal
ly S
tabl
e to
350
Th
erm
ally
Sta
ble
to 3
50 ºº
CC
Bot
h pr
ecur
sors
nuc
leat
e w
ell o
n hy
drog
enat
ed
Bot
h pr
ecur
sors
nuc
leat
e w
ell o
n hy
drog
enat
ed S
iS
i sur
face
ssu
rface
san
d sh
ow h
igh
reac
tivity
with
Han
d sh
ow h
igh
reac
tivity
with
H22O
.O
.N
o ne
ed fo
r che
mic
al o
xide
inte
rlaye
r to
initi
ate
grow
thN
o ne
ed fo
r che
mic
al o
xide
inte
rlaye
r to
initi
ate
grow
th
NN
N
N
Gd
N
N
NN
N
N
Sc
N
N
Har
vard
Uni
vers
ity
ALD
of G
dScO
3fil
ms
Line
ar g
row
th ra
teLi
near
gro
wth
rate
~ 2.
0 ~
2.0
ÅÅ/c
ycle
/cyc
le
Slig
htS
light
inhi
bitio
n (~
10 c
ycle
s) o
n H
Fin
hibi
tion
(~10
cyc
les)
on
HF --
last
last
SiSi
0102030405060
010
020
030
0N
umbe
r of C
ycle
s
Physical Thickness (nm)
Flow
Flow
-- thro
ugh
type
tube
reac
tor
thro
ugh
type
tube
reac
tor
Sub
stra
te te
mpe
ratu
re 3
10
Sub
stra
te te
mpe
ratu
re 3
10
CC
1cyc
le :
1cyc
le :
Sc
Sc
HH22OO
Gd
Gd
HH22OO
Pur
geP
urge
Pur
geP
urge
Pur
geP
urge
Pur
geP
urge
Har
vard
Uni
vers
ity
Stru
ctur
al P
rope
rtie
s of
GdS
cO3
Film
s
Stoi
chio
met
ry o
f a 2
5nm
thic
k fil
m b
y R
BS:
St
oich
iom
etry
of a
25n
m th
ick
film
by
RB
S:
Gd
Gd 11
ScSc1.
071.
07OO
33w
ith 1
:1 d
osin
g of
w
ith 1
:1 d
osin
g of
Gd
Gd
and
Scan
d Sc
XRD
and
TEM
indi
cate
the
film
s ar
e XR
D a
nd T
EM in
dica
te th
e fil
ms
are
amor
phou
sam
orph
ous
as d
epos
ited
and
stay
am
orph
ous
up to
950
as
dep
osite
d an
d st
ay a
mor
phou
s up
to 9
50 ºº CC
1.0
1
.5
2.0
Ene
rgy
( MeV
)
40 30 20 10 0
Cha
nnel
400
600
800
100
0
120
0
140
0
NormalizedYieldG
d
Sc
O
Sim
ulat
ion
Sim
ulat
ion
Har
vard
Uni
vers
ity
Adv
anta
ges
of W
N a
s a
Gat
e M
etal
Exc
elle
nt d
iffus
ion
barr
ier f
or o
xyge
n an
d m
etal
ato
ms
Can
be
etch
ed e
asily
Goo
d th
erm
al s
tabi
lity
Goo
d ad
hesi
on to
oxi
des
as w
ell a
s m
etal
s
Har
vard
Uni
vers
ityALD
of T
ungs
ten
Nitr
ide,
WN
NH
3ga
s is
use
d as
a c
o-re
acta
nt
Gro
wth
Rat
e at
385
ºC ~
2.0
Å/ c
ycle
Res
istiv
ity o
f W a
fter a
nnea
l > 7
50 ºC
~ 1
0-4-c
m
Pre
curs
or :
Bis
(tert-
buty
limid
o)bi
s-(d
imet
hyla
mid
o)tu
ngst
en(V
I)
Vap
or p
ress
ure
~ 37
mTo
rrat
30
ºCLi
quid
at r
oom
tem
pera
ture
J. S
. Bec
ker a
nd R
. G. G
ordo
n, A
ppl.
Phys
. Let
t. 82
, 223
9 (2
003)
WN
N
N N
Har
vard
Uni
vers
ity
HR
XTEM
of a
WN
/ G
dScO
3/ S
iSta
ck
Film
s ar
e ve
ry u
nifo
rm o
ver a
wid
e ar
ea.
Film
s ar
e ve
ry u
nifo
rm o
ver a
wid
e ar
ea.
GdS
cOG
dScO
33isis
amor
phou
s a
s de
posi
ted.
am
orph
ous
as
depo
site
d.
Inte
rface
s ar
e sh
arp
and
smoo
th.
Inte
rface
s ar
e sh
arp
and
smoo
th.
Har
vard
Uni
vers
ity
WN
/ G
dScO
WN
/ G
dScO
33/ / S
iSi
(100
) Cap
acito
rs(1
00) C
apac
itors
Elec
tric
al P
rope
rtie
s of
a L
ow E
OT
Film
EOT
~ 1
nm
Flat
band
Volta
ge~
+0.3
5 V
Hys
tere
sis
V <
60 m
VLe
akag
e C
urre
nt d
ensi
ty a
t 1V
~ 1
0-3A
/cm
2
Har
vard
Uni
vers
ity
Equ
ival
ent O
xide
Thi
ckne
ss v
s.
Phy
sica
l Thi
ckne
ss
~ 21
.5,
inte
rfaci
al la
yer ~
1.5
~
21.5
, in
terfa
cial
laye
r ~ 1
.5 ÅÅ
012345
05
1015
2025
Thic
knes
s (n
m)
EOT (nm)
Har
vard
Uni
vers
ity
Fixe
d C
harg
e D
ensi
ty a
ndW
ork
Func
tion
of W
N
0
0.1
0.2
0.3
0.4
12
34
5E
OT
(nm
)
Vfb (V)
Fixe
d C
harg
e D
ensi
ty ~
2.4
x 1
0Fi
xed
Cha
rge
Den
sity
~ 2
.4 x
101
111cmcm
-- 22
Wor
k Fu
nctio
n of
WN
~ 4
.6
Wor
k Fu
nctio
n of
WN
~ 4
.6 e
VeV(( m
idga
pm
idga
pm
etal
)m
etal
)
VFB
=M
S-Q
ft ox
/Kox
0
Har
vard
Uni
vers
ity
Inte
rface
Tra
p D
ensi
ty
by C
ondu
ctan
ce M
etho
d
Inte
rface
Tra
p D
ensi
ty ~
2.8
x 1
0In
terfa
ce T
rap
Den
sity
~ 2
.8 x
101
111cmcm
-- 22eVeV
-- 11
0.0E
+00
4.0E
-09
8.0E
-09
1.2E
-08
1.6E
-08
2.0E
-08 1.0E
+04
1.0E
+05
1.0E
+06
(1/s
)
Gp / (S s/cm2)
0.55
0.05
0.45
0.15
0.35
0.25
Cp
Cox
Gp
Equ
ival
ent c
ircui
t fo
r the
Gat
e C
apac
itor
VVGG
max
5.2p
it
Gq
D
Har
vard
Uni
vers
ity
Leak
age
Cur
rent
vs.
EO
T
leak
age
curr
ent ~
10
leak
age
curr
ent ~
10--
33A
cm
A c
m-- 22
at E
OT
= 1
nmat
EO
T =
1 nm
leak
age
curr
ent ~
10
leak
age
curr
ent ~
10--
77A
cm
A c
m-- 22
at E
OT
= 2
nmat
EO
T =
2 nm
~ 10
~ 10
44tim
es lo
wer
than
SiO
times
low
er th
an S
iO22
1.E-
09
1.E-
08
1.E-
07
1.E-
06
1.E-
05
1.E-
04
1.E-
03
1.E-
02
1.E-
01
1.E+
00
1.E+
010.
51.
52.
53.
5
EOT
(nm
, 1V
Gat
e Vo
ltage
)
Curremt Density (A/cm2)
GdS
cO3
SiO
2
`` `
Har
vard
Uni
vers
ity
Sum
mar
y of
GdS
cO3
Ultr
athi
nam
orph
ous
GdS
cO3
film
s w
ere
depo
site
d on
H
F-la
st S
isub
stra
tes
by A
LD u
sing
Gd
and
Sc
amid
inat
e pr
ecur
sors
.
ALD
WN
/ G
dScO
3ga
te s
tack
s sh
ow p
rom
isin
g el
ectri
cal p
rope
rties
for f
utur
e M
OS
FET
and
DR
AM
ap
plic
atio
ns•
Hig
h (k
~ 21
.5) a
nd L
ow E
OT
(~ 1
nm
)•
Low
leak
age
curr
ent (
< 1
0-3
A/c
m2
at 1
V fo
r EO
T ~
1 nm
) •
Rea
sona
bly
low
fixe
d ch
arge
and
inte
rfac
e tr
ap d
ensi
ty
Har
vard
Uni
vers
ity
Ru(
amid
inat
e) p
recu
rsor
stru
ctur
ede
posi
tion
cond
ition
sPr
oper
ties
of R
uthe
nium
film
sco
nfor
mal
and
com
plet
e co
vera
gesm
ooth
sur
face
low
resi
stan
cest
rong
adh
esio
n to
WN
Cop
per s
eed
laye
rsco
nfor
mal
and
com
plet
e co
vera
gelo
w re
sist
ance
elec
troc
hem
ical
dep
ositi
on o
f Cu
surv
ive
CM
P of
Cu
Out
line
of C
u / R
u/ W
N fo
r Int
erco
nnec
ts
Har
vard
Uni
vers
ity
Ta, R
uan
d C
o al
l hav
e th
ese
requ
ired
prop
ertie
s:
•Low
sol
ubili
ty in
cop
per
•Str
ong
inte
rfac
ial a
dhes
ion
to c
oppe
rTa
>6
J m
-2
Ru
~4 J
m-2
Co
>30
J m
-2
•Low
ele
ctric
al re
sist
ivity
Ta 1
3.4
-cm
Ru
7.4
-cm
Co
5.8
-c
m
Mot
ivat
ion
for u
sing
Rut
heni
um o
r Cob
alt
inst
ead
of T
anta
lum
as
an a
dhes
ion
laye
r
Tant
alum
has
low
adh
esio
n to
CVD
or A
LD c
oppe
r
Har
vard
Uni
vers
ity
RuPr
ecur
sor R
u(t B
u-am
d)2(
CO
) 2
Ru1
N3 N4
N1
N2
C2
C1
C5
O1
C6
O2
Mol
ecul
ar s
truc
ture
by
x-ra
y cr
ysta
llogr
aphy
•vap
or p
ress
ure
>0.0
5 To
rr a
t 130
ºC
•low
eva
pora
tion
resi
due
0.14
% b
y TG
•air
and
moi
stur
e st
able
Che
mic
al fo
rmul
a
NN
Ru
NN
OC
CO
Har
vard
Uni
vers
ity
Ru(
t Bu-
amd)
2(C
O) 2
R
u+
+2
CO
ALD
/CVD
of R
u
Con
ditio
ns:
•Bub
bler
: 130
ºC•S
ubst
rate
: 200
-30
0 ºC
•co-
reac
tant
: NH
3
•Pre
ssur
e: 1
~ 2
Tor
r
=> M
ostly
sur
face
con
trol
led
CVD
, onl
y pa
rtly
ALD
•~1.
5 A
ngst
rom
/cyc
le a
t 300
o C
N NNN
•No
satu
ratio
n of
gro
wth
/cyc
le
Har
vard
Uni
vers
ity
Hig
h C
onfo
rmal
ity o
f ALD
/CVD
Ru/
WN
/SiO
2
45 n
m
40 n
m
40 n
m
50 n
m80
% c
onfo
rmal
in tr
ench
w
ith 4
0:1
aspe
ct ra
tio
Smoo
th fi
lms:
by
AFM
< 2
% rm
sro
ughn
ess
Har
vard
Uni
vers
ity
Elec
tric
al C
ondu
ctiv
ity o
f CVD
Ru
/ SiO
2
23
45
67
2030405060708090100
Resistivity (-cm)
Thic
knes
s (n
m) C
VD
Ru
PV
D R
u M
odel
Con
duct
ivity
mat
ches
pur
e R
ufil
ms
sput
tere
d on
to T
a
Gra
in B
ound
ary
Scat
terin
g M
odel
/0
= 1+
1.5{
R/(1
-R)}
(/ g
)
whe
re th
e av
erag
e gr
ain
size
g is
es
timat
ed a
s th
e fil
m th
ickn
ess
scat
terin
g co
effic
ient
for e
lect
rons
at
grai
n bo
unda
ries
R =
0.5
8
bulk
sca
tterin
g le
ngth
=
10 n
m
bulk
resi
stiv
ity0
= 7.
1 -c
m
Har
vard
Uni
vers
ity
2 nm
ALD
/CVD
Ru
com
plet
ely
cove
rs W
N
•no
pin
hole
s se
en b
y ve
rtic
al T
EM:
•an
etc
h so
lutio
n H
2O2/N
H4O
H,
whi
ch n
orm
ally
dis
solv
es a
WN
fil
m w
ithin
one
min
ute,
doe
s no
t et
ch th
e W
N u
nder
a 2
nm
Ru
film
eve
n af
ter o
ne h
our.
•R
ufil
ms
are
stro
ngly
adh
eren
t to
fres
hly-
depo
site
d W
N
adhe
sion
ene
rgy
~ 4
J/m
2by
4-p
oint
ben
d te
st.
Har
vard
Uni
vers
ity
Nuc
leat
ion
of C
u(3n
m) o
n R
u(2n
m) /
WN
(3nm
) / S
i 3N4
Vert
ical
TEM
sho
ws
com
plet
e co
vera
ge
Che
mic
al te
st fo
r com
plet
enes
s of
co
vera
ge b
y co
pper
:
Ru
cata
lyze
s H
2O2
deco
mpo
sitio
n ra
pidl
y fo
rmin
g bu
bble
s of
oxy
gen
Cu
bubb
les
very
slo
wly
Cu
/ Ru
also
bub
bles
ver
y sl
owly
Zhen
gwen
Li a
nd R
oy G
. Gor
don,
Che
m. V
ap. D
epos
ition
200
6,12
, 435
–441
Har
vard
Uni
vers
ity
Elec
tric
al R
esis
tanc
e of
ALD
Cu
on R
u
ALD
Cu
resi
stiv
ity m
atch
es p
ure
sput
tere
d C
ufil
msa
(a) R
ossn
agel
, S.;
Kua
n, T
.; J.
Vac
. Sci
. Tec
h. B
22, 2
40 (2
004)
Con
tinuo
us la
yer j
ust 3
Cu
atom
s th
ick!
110
010203040506070 Cu resistivity (ohm cm)
Cu
thic
knes
s (n
m)
ALD
Cu
PVD
Cu
Gra
in B
ound
ary
Scat
terin
g M
odel
/0
= 1+
1.5{
R/(1
-R)}
(/ g
)
whe
re th
e av
erag
e gr
ain
size
g is
es
timat
ed a
s th
e fil
m th
ickn
ess
scat
terin
g co
effic
ient
for e
lect
rons
at
grai
n bo
unda
ries
R =
0.3
bulk
sca
tterin
g le
ngth
=
39 n
m
bulk
resi
stiv
ity
0=
1.7
-cm
Har
vard
Uni
vers
ity
Cu(
3nm
)/Ru(
2nm
)/WN
(2nm
) has
sh
eet r
esis
tanc
e ~
50
/sq
Suita
ble
for e
lect
ropl
atin
g42
nm
SEM
of c
oppe
r film
at b
otto
m
of h
ole
with
asp
ect r
atio
40:
1an
d >
90%
ste
p co
vera
ge
Har
vard
Uni
vers
ity
Elec
trop
late
d by
Tom
P. M
offa
t
CM
P by
Chr
istia
n W
itt
SEM
by
Dan
iel J
osel
l, N
IST
Bef
ore
CM
P
Afte
r CM
P
=> A
dhes
ion
stro
ng
enou
gh to
sur
vive
CM
P
Cu
Cu
SiO
2
SiO
2
Har
vard
Uni
vers
ity
ALD
of S
iO2
pore
sea
lant
/ W
N b
arrie
r / R
ugl
ue /
Cu
seed
•Ex
tend
able
to th
e en
d of
the
road
map
•N
o de
posi
tion
on c
ham
ber w
alls
=>
no c
ham
ber c
lean
ing
•N
o pl
asm
a da
mag
e to
sub
stra
tes
•Si
mpl
ified
equ
ipm
ent d
esig
n be
caus
e no
pla
sma
need
ed
Har
vard
Uni
vers
ity
Met
als:
Boo
yong
Lim
, Ant
tiR
ahtu
, Jin
-Seo
ngPa
rk
Nic
kel:
P. V
enka
tesw
ara
Rao
, Kyo
ung
Kyo
ung --
ha
ha K
im
Cop
per,
Cob
alt:
Zhen
gwen
Li, S
ean
Bar
ry, D
on K
eun
Lee
Rut
heni
um: H
uazh
iLi,
Titta
Aal
tone
n
Met
al N
itrid
es: J
ill B
ecke
r, Se
igiS
uh, E
sthe
r Kim
, Kyo
ung
Kyo
ung --
ha
ha K
im
Met
al o
xide
s: D
enni
s H
ausm
ann,
Phi
lippe
de
Rou
ffign
ac, J
in-S
eong
Park
,K
youn
gK
youn
g --ha
ha
Kim
, Leo
Rod
rigue
z, M
ike
Cou
lter
TEM
: Dam
on F
arm
er; S
EMA
TEC
H
Adh
esio
n m
easu
rem
ents
: Joo
stVl
assa
k, Y
oubo
Lin
DR
AM
tren
ches
sup
plie
d by
Infin
eon
Supp
orte
d in
par
t by
the
US
Nat
iona
l Sci
ence
Fou
ndat
ion
Ack
now
ledg
emen
ts
Har
vard
Uni
vers
ity
In-s
itu D
epos
ited
WN
Gat
e vs
. Ex
-situ
Dep
osite
d Pt
Gat
e
In-s
ituW
N g
ate
stac
k sh
ows
18%
in
crea
se in
cap
acita
nce
0.00
0.40
0.80
1.20
1.60
-1.0
0.0
1.0
2.0
3.0
Gat
e Vo
ltage
(V)
Gate Capacitance (F/cm2)
Pt G
ate
WN
Gat
e