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15-3020-3010-1510-15
10-158-95-6k
Lanthanide OxidesHfSixOy
ZrO2, HfO2Al2O3
HfSixOyNzNO stackHfAlxOyMaterial
15-3020-3010-1510-15
10-158-95-6k
Lanthanide OxidesHfSixOy
ZrO2, HfO2Al2O3
HfSixOyNzNO stackHfAlxOyMaterial
Choice of high-kk value less than 50 is desirable forsuppression of short channel effects
High-k Gate Dielectric Candidates
●●●●
●●●● Gas or liquidat 1000 K
●●●●H
○○○○Radio activeHe
●●●● ●●●● ●●●● ●●●● ●●●● ●●●●Li Be B C N O F Ne①①①① ●●●● ●●●● ●●●● ●●●●Na Mg Al Si P S Cl Ar
②②②② ①①①① ①①①① ①①①① ①①①① ①①①① ①①①① ①①①① ①①①① ①①①① ①①①① ●●●● ●●●● ●●●● ●●●●K Ca Sc Ti V Cr Mn Fc Co Ni Cu Zn Ga Ge As Se Br Kr●●●● ①①①① ①①①① ①①①① ①①①① ①①①① ●●●● ①①①① ①①①① ①①①① ①①①① ①①①① ●●●● ●●●●Rh Sr Y Zr Nb Mo Tc Ru Rb Pd Ag Cd In Sn Sb Te I Xe●●●● ③③③③ ①①①① ①①①① ①①①① ①①①① ①①①① ●●●● ●●●● ●●●● ●●●● ①①①① ①①①① ○○○○ ○○○○ ○○○○Cs Ba ★★★★ Hf Ta W Re Os Ir Pt Au Hg Tl Pb Bi Po At Rn○○○○ ○○○○ ○○○○ ○○○○ ○○○○ ○○○○ ○○○○ ○○○○Fr Ra ☆☆☆☆ Rf Ha Sg Ns Hs Mt
○○○○La Ce Pr Nd PmSmEu GdTb Dy Ho Er TmYbbbb Lu○○○○ ○○○○ ○○○○ ○○○○ ○○○○ ○○○○ ○○○○ ○○○○ ○○○○ ○○○○ ○○○○ ○○○○ ○○○○ ○○○○ ○○○○Ac Th Pa U Np Pu Am Cm Bk Cf Es Fm Md No Lr
★★★★
☆☆☆☆
Candidates Exp Reported
②
③
Unstable at Si interfaceSi + MOX M + SiO2①①①①
Si + MOX MSiX + SiO2
Si + MOX M + MSiXOY
●●●●
●●●● Gas or liquidat 1000 K
●●●●H
○○○○Radio activeHe
●●●● ●●●● ●●●● ●●●● ●●●● ●●●●Li Be B C N O F Ne①①①① ●●●● ●●●● ●●●● ●●●●Na Mg Al Si P S Cl Ar
②②②② ①①①① ①①①① ①①①① ①①①① ①①①① ①①①① ①①①① ①①①① ①①①① ①①①① ●●●● ●●●● ●●●● ●●●●K Ca Sc Ti V Cr Mn Fc Co Ni Cu Zn Ga Ge As Se Br Kr●●●● ①①①① ①①①① ①①①① ①①①① ①①①① ●●●● ①①①① ①①①① ①①①① ①①①① ①①①① ●●●● ●●●●Rh Sr Y Zr Nb Mo Tc Ru Rb Pd Ag Cd In Sn Sb Te I Xe●●●● ③③③③ ①①①① ①①①① ①①①① ①①①① ①①①① ●●●● ●●●● ●●●● ●●●● ①①①① ①①①① ○○○○ ○○○○ ○○○○Cs Ba ★★★★ Hf Ta W Re Os Ir Pt Au Hg Tl Pb Bi Po At Rn○○○○ ○○○○ ○○○○ ○○○○ ○○○○ ○○○○ ○○○○ ○○○○Fr Ra ☆☆☆☆ Rf Ha Sg Ns Hs Mt
○○○○La Ce Pr Nd PmSmEu GdTb Dy Ho Er TmYbbbb Lu○○○○ ○○○○ ○○○○ ○○○○ ○○○○ ○○○○ ○○○○ ○○○○ ○○○○ ○○○○
①①①① ①①①① ①①①① ●●●● ●●●●Rh Sr Y Zr Nb Mo Tc Ru Rb Pd Ag Cd In Sn Sb Te I Xe●●●● ③③③③ ①①①① ①①①① ①①①① ①①①① ①①①① ●●●● ●●●● ●●●● ●●●● ①①①① ①①①① ○○○○ ○○○○ ○○○○Cs Ba ★★★★ Hf Ta W Re Os Ir Pt Au Hg Tl Pb Bi Po At Rn○○○○ ○○○○ ○○○○ ○○○○ ○○○○ ○○○○ ○○○○ ○○○○Fr Ra ☆☆☆☆ Rf Ha Sg Ns Hs Mt
○○○○La Ce Pr Nd PmSmEu GdTb Dy Ho Er TmYbbbb Lu○○○○ ○○○○ ○○○○ ○○○○ ○○○○ ○○○○ ○○○○ ○○○○ ○○○○ ○○○○ ○○○○ ○○○○ ○○○○ ○○○○ ○○○○Ac Th Pa U Np Pu Am Cm Bk Cf Es Fm Md No Lr
★★★★
☆☆☆☆
CandidatesCandidates Exp Reported
②
③
Unstable at Si interfaceSi + MOX M + SiO2①①①①
Si + MOX MSiX + SiO2
Si + MOX M + MSiXOY
Other options?
R. Hauser, IEDM Short Course, 1999
Band offsets for High-k dielectrics on Si6
4
2
0
-2
-4
-6
1.1
3.52.4
0.3 -0.10.8 1.4 1.5
2.82.3 1.5
4.4
1.83.0
2.3
3.4 3.3 3.44.9
2.63.4
Si
SiO2
Si3N4
Ta2O5
BaTiO3
BaZrO3
ZrO2HfO2
Al2O3
Yb2O3
ZrSiO4
La2O3
2.3
2.6c
* C Estimates.
Ener
gy (e
V)
6
4
2
0
-2
-4
-6
1.1
3.52.4
0.3 -0.10.8 1.4 1.5
2.82.3 1.5
4.4
1.83.0
2.3
3.4 3.3 3.44.9
2.63.4
Si
SiO2
Si3N4
Ta2O5
BaTiO3
BaZrO3
ZrO2HfO2
Al2O3
Yb2O3
ZrSiO4
La2O3
2.3
2.6c
* C Estimates.
Ener
gy (e
V)
参考文献: J.Robertson Journal of Non-Crystalline Solids 303(2002) P98
Experimental data by XPS by Prof. T. Hattori
0 10 20 30 40 50Dielectric Constant
4
2
0
-2
-4
-6
SiO2
Ban
d D
isco
ntin
uity
[eV]
Si
kB *φ : Figure of Merit of High-kInsulating Films on Semiconductors Barcelona June 18-20, 2003
Our Molecular Beam Deposition System
Back pressure: ~10-10 TorrDuring deposition:~10-9~10-7 Torr
Deposition rate:0.1~1 nm/min
IP
La2O3target
E-gun
Substrate
RP
Deposition Ch.
Loading Ch.
TSP
TMP
Transfer rod
n-Si
La2O3
Al
2 nm
n-Si
La2O3
Al
2 nm
Cross sectional TEM images for Al/La2O3/n-Si. 400oC depo., 400oC RTA in N2.
Physical thickness= 2 nm
EOT = 0.6 nm
Tox Electrical Equivalent vs. Current Density
From IEDM 2000, IEDM 2001, SSDM 2001 and VLSI Symp. 2001(Advanced Program)
10-10
10-6
10-2
102
0.5 1.0 1.5
HfO2NH3+HfO2HfSiONZrO2Zr-SilicateAl2O3NH3+ZrO2Zr-Al-Si-O
Pr2O3Nd2O3Sm2O3Gd2O3Dy2O3
Ta2O5NH3+Al2O3/ZrO2
La2O3SiO2Nitrided SiO2Tox Electrcal Equivalent (nm)
Curr
ent
Den
sity
(A/
cm2 )
23.326.127.09.6216.915.6
17.0
RelativeDielectri
cConstant
0.8080.7850.7840.3910.8700.823
0.806
Vfb[V]
0.1230.0810.083
-0.7000.2570.165
0.123
∆Vfb[V]
2.77e-67.27e-63.04e-71.37e-59.51e-73.09e-6
1.06e-2
Leakage
[A] @1VEOT[nm]
Annealing(5min)
1.280400oC1.443300oC
3.103400oC1.617300oC
200oC
200oC
1.106N2
1.762
1.760
O2
without
CalcfbsilicongateCalcfbfuncfittedfb VWWVWV ,,, +−=∆+∆=
0
1
2
-1.5 -1 -0.5 0 0.5
as-depo300℃400℃450℃
Cap
acita
nce
(µF/
cm2 )
Voltage (V)
10-8
10-6
10-4
10-2
100
102
-1 -0.5 0 0.5 1
Cur
rent
Den
sity
(A/c
m2 )
Voltage (V)
as-depo.
300 oC
400 oC
450 oC
Preliminary results
Dry N2 annealing
Densification: goodVfb shift: problemBeing solved by PM anneal
ID - VD Characteristics ( Lg = 2.5 µm )Chemical Oxide, Deposition Temp. = 250oC,
Lg = 2.5 µm, W = 27 µm, EOT = 3.0 nm
Lg
W
0
20
40
60
80
100
120
140
160
0 0.5 1 1.5 2 2.5 3 3.5 4
Dra
in C
urre
nt I D
(µA
/µm
)
Drain Voltage VD (V)
Vg = 0 V
Vg = 1.5 V
Vg = 1.0 V
Vg = 0.5 V
Lg/W = 2.5/27 µm
n+ Source n+ Drain
Gate
Electrical Characteristics – Mobility µeff
100
1000
10-1 100
Effec
tive M
obilit
y µeff
(cm2 /V
-s)
Effective Field εeff
(MV/cm2)
La2O3 (EOT = 3nm)Universal Curve
High effective mobility of nearly the same to the universal curve was obtained with EOT = 3nm La2O3 gate dielectrics.
Flicker noise at Vds=100mV
10-23
10-22
10-21
10-20
10-19
10-18
10-17
101 102 103 104
1μA2.5μA5μA10μA25μA50μA100μA
S ID (A2 /Hz)
Frequency (Hz)
WxL=27μmx2.5μm
1/f
Results and Discussion (6)LF Noise – Comparation with SiO2
1.E-13
1.E-12
1.E-11
1.E-10
1.E-09
1.E-08
1.E-01 1.E+00 1.E+01 1.E+02 1.E+03
f=100Hzf=100Hzf=100Hz
(gm/Id)2 (V-2)10-0 101 102 10310-1
10-9
10-10
10-11
10-12
10-13
10-8
S ID/I d2
(1/H
z)
La2O3 (WL=27µmx2.5µm)SiO2 (WL=50µmx2.5µm)
La2O3 (WL=54µmx2.5µm)
f = 100HzVd = 0.1V
The normalized noise spectrum of n-type MISFET’s with La2O3gate dielectrics is about one order in magnitude higher than that of SiO2 obtained from thermal oxidation.
The oxides become hydroxide and carbonate in H2O and CO2ambient.
Absorption of moisture and CO2
Ln2O3
n-Si(100)
Ln2O3
n-Si(100)
Ln2(CO3)3
Ln2O3 + H2O → Ln2O3・H2O
Ln2O3 + H2O → 2(LnOOH)
2Ln(OH) + H2O → 3Ln2(OH)3
Ln2O3
n-Si(100)
Ln2(OH)3
n-Si(100)
Ln2O3 + 2CO2 →Ln2(CO3)3
hydroxide carbonate
※Ln:Lanthanide
Experimental apparatusTemperature: ~20oCHumidity: 80%Humidification time:
0 ~120 hrs
ThermometerHygrometer
Samples
Ultra pure water
acryl(PMMA)or glass(PYREX)
*PMMA : CH2C(CH)3COOCH3
glass(PYREX)
acryl(PMMA)
1Yb2O3Gd2O3Dy2O3
ZrO2SiO2
1 2Lu
2O
3Eu
2O
3Sm2O3
Pr2O
3La
2O
3
CET120hrs
/CETfresh
CET
120hrs /CET
Fresh
Change of CET for all studied
Absorption test in case of acryl apparatus
after the Al electrode formation for Pr2O3.
n-Si(100)
Al electrode
High-k film
moisture
with electrode C-V
n-Si(100)High-k film
~~ ~~ ~~ ~~~~ ~~
0
0.5
1
1.5
-2 -1 0 1
Fresh24hrs (with electrode)
Cap
acita
nce
(µF/
cm2 )
Voltage (V)
Pr2O3 / n-Si(100)
R.T.-depo
RTA : N2600oC
研究目的
Lu2O3
La2O3
Si
Lu2O3
Si
La-Silicate
Si
Lu2O3
Si
silicate
phase separate
SiO2
RTA
RTA
Ref. S.Ohmi, et al., J. Electrochem. Soc., 150, F134(2003)H.Nohira et al., J. Appl. Surf. Sci., 216(2003)
La2O3
Lu2O3
La2O3
Si
Lu2O3
Si
La-Silicate
Si
Lu2O3
Si
silicate
phase separate
SiO2
RTA
RTA
Ref. S.Ohmi, et al., J. Electrochem. Soc., 150, F134(2003)H.Nohira et al., J. Appl. Surf. Sci., 216(2003)
La2O3
Lu2O3
Si substrate
La2O3
RTALu2O3
La-Silicate
Stack(Lu2O3/La2O3)
La2O3で界面層成長と微結晶化を抑えるLu2O3で膜全体silicateを抑え、耐湿性を向上 誘電率を保ちつつリーク電流を抑制
µeff = 163 [cm2V-1s-1] (EOT = 2.05 nm)
0
10
20
30
40
50
0 1 2
I D [µ
A/µ
m]
VD [V]
W = 54 µm
-0.5V
VG = 1.1V
0.9V
-0.1V
L = 10 µm
0.7V
0.1V0.3V
0.5V
-0.3V
dott line : La
2O
3
10-8
10-7
10-6
10-5
10-4
10-3
0
0.5
1
1.5
2
2.5
3
-1.5 -1 -0.5 0 0.5 1I D
[A]
g m [µ
S/µm
]
VG [V]
W = 54 µm
S = 80 mV/dec
L = 10 µm Vd = 0.1 V
dott line : La2O3
S = 160 mV/dec
積層構造(Lu2O3/La2O3/n-Tr)の作製
ID-VD Characteristics ID - VG Characteristics
nMIS 250oC堆積, annealed at 400oC, Al電極を使用
O2300→O2400でより改善がみられ、同条件のLa2O3と比較して、良好な特性が得られた
Lu2O3のののの耐湿性耐湿性耐湿性耐湿性によりによりによりにより、、、、電気特性電気特性電気特性電気特性がががが改善改善改善改善したしたしたした
Conduction Modes and Expressions
*Thermionic Current, **Direct Tunneling Current,***Space-Charge-Limited Current : single trap level for shallow (7) and deep (8) distributio
Mode
Bulk-
Limite
d
Expression
DT**F-N
Schottky*
Poole
SCLC***
( ) 21ln EJ ∝( ) EJ ∝ln
( ) TTJ 1ln 2 −∝
( ) EEJ 1ln 2 ∝(weak) TJ 2∝
EJ ∝
( ) TJ 1ln −∝( ) EEJ ∝ln
(1)(2)(3)
(5)
(6)(7)
2EJ ∝(8)
Bulk-
Free
( ) E J αln
P-F ( ) 21ln EEJ ∝
(4)Ohmic ( ) TJ 1ln −∝
Al Electrode Case – Leakage Current
Q.EOT 1.54 nmO.TOX 4.7nmRDC 11.9
-2 -1 0Vg [V]
0.0
500.0n
1.0u
1.5u
2.0u
Cg [F
/cm^2
]
1MHz(R)1MHz(F)HF
Cg [F
/cm2 ]
Measured
Calculated
1E-05
1E-04
1E-03
1E-02
-1.0 -0.5 0.0 0.5 1.0Vg [V]
|Jg| [A
/cm2 ]
J0J40J80OV0OV40OV80SQS0SQS40SQS80PF0PF40PF80
0 oC40 oC80 oC
Ohmic
P-F
VFB VG=0V
ReverseField
SCLC(Shallow)
2003.11.30.修正
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