oral presenation avs 2014 v3
Post on 23-Feb-2017
10 Views
Preview:
TRANSCRIPT
1
Surface reactions and interface evolution during the ALD of HfO2 on GaAs surfaces
studied by in situ ATR-FTIR
Liwang Ye, Theodosia Gougousi
Department of Physics University of Maryland, Baltimore County (UMBC),
Baltimore, MD 21250
University of Maryland, Baltimore County
2 University of Maryland, Baltimore County
Motivation
Atomic layer deposition (ALD) of high-κ on III-V has promising applications in MOSFET.
Poor quality native oxides are detrimental to MOSFET applications.
Interface self-cleaning has been widely observed.1
1. P. D. Ye et al. APL 83, 180 (2003), M. M. Frank et al. APL 86, 152904 (2005), D. Shahrjerdi et al. APL 92, 223501 (2008), L. Huang et al. APL 87, 252104 (2005), C.-H. Chang et al. APL 89, 242911 (2006),C. L. Hinkle et al. APL 92, 071901 (2008), Hackley et al. APL 92(16), 162902 (2008) , Suri et al. APL 96, 112905 (2010).
Gougousi et al. TSF 518, 2006 (2010)Gougousi et al. JES, 157(5), H551 (2010)
III-V semiconductor
Metal oxideNative oxide
III-V semiconductor
Before ALD After ALD
ALD
Motivation: understanding the “interface self-cleaning”
3
(1) Ligand exchange 3 HfL4 + 2 A2O3 → 3 HfO2 + 4 AL3L
(2) Precursor decomposition
N
CH 3
CH3
(3) Oxide conversion 4 GaAs + 3 As2O5 → 2 Ga2O3 + 3 As2O3 + 4 As
GaAsNative oxide
M
L
L L
L
GaAsNative oxide
DecompositionByproducts
M: Metal atom
L
N
CH 3
CH3
A= As or Ga or In
S. Klejna and S. D. Elliott, Chem. Mater. 26, 2427 (2014).
C. H. Chang et al. APL 89, 242911 (2006).
R. P. Vasquez et al. APL 42, 293 (1983).
University of Maryland, Baltimore County
4
Internal reflection element (IRE) (GaAs)
IR detector
IR source
Rotary vane pump
H2O
TDMAH FTIR Attenuated total reflection (ATR) cell
Pressure gauge
N2
In situ ATR-FTIR setup
.
Computer
D2O/H2
18O
Fixed volume
University of Maryland, Baltimore County
K. Li et al., JVSTA 25, 1389 (2007), K. Li et al., JPCC 114, 14061 (2010).
5
• Precursor: TDMAH and H2O
Experimental details: ALD process
University of Maryland, Baltimore County
1st T
DM
AH
1st H
2O
Time (min)0 3 4 5
N2 p
urge
and
sp
ectra
take
n1st Cycle
2nd CycleRea
ctor
pr
essu
re
N2 p
urge
and
sp
ectra
take
n
1 2
HfN
CH3
CH3
N
CH 3
CH3
N CH3
CH3
N
CH3
CH3
[Hf(N(CH3)2)4]
TDMAH
6
Abs
orba
nce
4000 3000 2000 1000
Wavenumber (cm-1)
2920& 2851
1630
1067
843
As-OH2O
CH
0.01
Abs
orba
nce
1000 700
Wavenumber (cm-1)
1067
843
As-O
0.01
Characterization of the GaAs starting surface
GaAs
Native oxide
GaAs
chemical oxide
Chemical oxide GaAs(100)
Native oxide GaAs(100)
Reference of the spectra are the HF etched GaAs surface. As-O region
University of Maryland, Baltimore County
M. Rei Vilar et al. Surf. Interface Anal. 37, 673 (2005).
Abs
orba
nce
4000 3500 3000 2500 2000 1500 1000
Wavenumber (cm-1)
147
0 1
410
157
2
277
7 2
855
363
0
324
0
8600.002
1st TDMAH
2nd H2O
20th TDMAH
20th H2O
1st H2O
2nd TDMAH
120
0 1
046
7
ALD of HfO2/CO GaAs(100) at 275°C
GaAs
chemical oxide
HfN(CH3)2(CH3)2N
H
O
H
O
HfN(CH3)2(CH3)2N
(CH3)2N N(CH3)2
CH3 stretch
OH
H
TDMAH
OH
H
chemical oxide
HfO2HfO2
CH3 -N=CH
2 (MMI)
Hf-OH
As-O removal
University of Maryland, Baltimore County
8
1200 1100 1000 900 800
HfO2/CO GaAs HfO2/HF GaAs
0.003
1 cycle
2 cycles
3 cycles
10 cycles
20 cycles
Interface self-cleaning during the ALD of HfO2 at 275 °C
The references for these spectra are their respective starting surfaces.
0.5
0.4
0.3
0.2
0.1
0.0
Are
a of
rem
oved
As-
O
20181614121086420
No. of cycles
As-O region As oxide removal during the deposition at 275 °C
Gradual removal of the arsenic oxide has been observed during the deposition
L. Ye and T. Gougousi, APL, 105, 121604 (2014).
Removed As-O
III-V semiconductor
HfO2chemical oxide
GaAs
ALD
University of Maryland, Baltimore County
Abs
orba
nce
Wavenumber (cm-1)
9
Interface self-cleaning during the ALD of HfO2 at 275°CA
bsor
banc
e
Wavenumber (cm-1)
The references for these spectra are their respective starting surfaces.
As-O region
L. Ye and T. Gougousi, APL, 105, 121604 (2014).
As-O-HfL : N(CH3)2
HfL
L L
L
As-O-As AsOHfL
L L
AsL
+
HfL
L L
L
As AsOHfL
L L H-L +
OH
(1)
(2)
Two possible reaction schemes.
University of Maryland, Baltimore County
1200 1100 1000 900 800
HfO2/CO GaAs HfO2/HF GaAs
0.003
1 cyc
2 cyc
3 cyc
10 cyc
20 cyc 1046
10
Effect of the deposition temperature on the interface self-cleaning
Abs
orba
nce
1200 1100 1000 900 800
Wavenumber (cm-1)
275 °C
200 °C
0.003 100 °C
250 °C
20 cycles of HfO2 ALD on “CO GaAs” (100) surface. The spectra have been referenced to the respective starting surfaces.
The arsenic oxide removal is enhanced at higher deposition temperatures.
Deposition temperature
Removed As oxides
Suri et al. APL 96, 112905 (2010).
University of Maryland, Baltimore County
11
1500 1000
860
0.002
157
2 1
470
141
0
104
6
Abs
orba
nce
Wavenumber (cm-1)
Interface self-cleaning during the ALD of HfO2 at 275 °C
HfO2/CO GaAsCH3-N=CH2
(MMI)
TDM
AH TD
MA
H TDM
AHTD
MA
HH 2O H 2O H 2O H 2O
0.20
0.15
0.10
0.05
0.00Pe
ak a
rea
20151050 Time (mins)
CH Stretch 1572 cm-1
University of Maryland, Baltimore County
1st TDMAH
2nd TDMAH1st H2O
2nd H2O3rd H2O
10th H2O
20th H2O
The reference for these spectra is the starting surface.
12
Possible reaction schemes for the production of MMI
Hf
N(C
H3) 2
N(C
H3) 2
+ OH
H2
Hf
OH
OH
+ HN(CH3)22(a)
Hf
OH
OH+ HN(CH3)2 + + H2N=CH2CH3 -
(b)
Hf
OH
OH
+ + HHN=CH2CH3-2 2(c)
Surface reaction schemes at H2O half cycle during the ALD of HO2 on GaAs surfaces.
University of Maryland, Baltimore County
J. P. A. M. Driessen et al. J. Electrochem. Soc., 148, G178 (2001),S. Salim et al. Chem. Mater. 7, 507 (1995).
13
Continuous removal of arsenic oxide during the first 20 ALD cycles has been observed.
Temperature dependence of the arsenic oxide removal has been confirmed.
Methylmethyleneimine (MMI) is produced during the H2O exposure and accumulates in the film.
Conclusions
University of Maryland, Baltimore County
top related