radiation effects on emerging electronic materials and devices
DESCRIPTION
June 13/14, 2006. Radiation Effects on Emerging Electronic Materials and Devices. Radiation Effects in Emerging Materials Overview. Leonard C. Feldman Vanderbilt University Department of Physics and Astronomy Vanderbilt Institute on Nanoscale Science and Engineering. Gate. oxide. Si. - PowerPoint PPT PresentationTRANSCRIPT
Radiation Effects on Emerging Electronic Materials and Devices
Leonard C. FeldmanVanderbilt University
Department of Physics and AstronomyVanderbilt Institute on Nanoscale Science and Engineering
June 13/14, 2006
Radiation Effects in Emerging Materials
Overview
Gate
oxid
eSi
met
al
MOS Schematic
Gate Dielectricsi. High-k on Si:
HfO2/Si, HfSiO/Si - (w and w/o interlayer)ii. High-k on Ge: HfDyO2/Geiii. SiO2/Silicon carbide
MURI review June’06
Radiation damage in emerging materials
Other emerging materialsi. Strained siliconii. SOIiii. SiGe
Characterization: i. Electrical:
CV - Net charge
Photo-CV - Deep and slow states
I-V - Breakdown
ii. Optical:
Femto-second Pump-probe spectroscopy - alternate approach to charge quantification
iii. Atomic level spectroscopy:
Conductive tip AFM - identification of isolated leakage spots
X-ray absorption - defect selective
++
+ +
++
- -
- -
GoalsThe goals of this segment of the program are to identify and associate:
i) radiation induced electrical defects with particular physical (atomic and electronic) configurations
ii) to identify and elucidate new defects/traps that exist in emerging materials
Requires a strong coupling to theory
Requires strong coupling to sophisticated electrical
New materials also give new insights that feed-back to the traditional structures
In situ photovoltage measurements using femtosecond pump-probe photoelectron spectroscopy and its application to metal-HfO
2-Si structures
Richard HaightIBM
Measures band-bending in an in-situ configuration, without metal gate, yielding intrinsic electronic structure
800 nm ~35fs
HARMONIC LASER PHOTOEMISSION
TOF detector
sample
parabolic mirror
Main Chamber
grating
Ar jet
Pump, 800 nm, ~35fs
High Harmonic Generation
ee
High KE
Photon energiesfrom 15-60 eV
Laser field
Harmonic photon
p-FET
n-type
p+ p+
gate oxide
channel
Metal Gate for high-K MOS?
But
1) Metal gate shows a similar problem
EIFL Midgap
2) In addition, Vt instability: charge trap?
Goal: Understand the effect of thermal processes on high-K oxide & oxide-metal interface which affect MOS properties
Si
N-silicon
HfO2
High WF Metal
EF
For ideal p-FET
at VG= 0
Interface Fermi Level (EIFL)
Vacuum level
Sze: Phys. Semi. Dev.
After anneal
Advanced Gate Stacks and Substrate Engineering
Eric Garfunkel, Rutgers University
External interactions:
• Rich Haight, Supratik Guha – IBM• Gennadi Bersuker – Sematech
• M. Green - NIST• E. Gusev - Qualcomm• W. Tsai - Intel• J. Chambers - TI
Rutgers CMOS Materials Analysis
• Scanning probe microscopy – topography, surface damage, electrical defects
• Ion scattering: RBS, MEIS, NRA, ERD – composition, crystallinity, depth profiles, H/D
• Direct, inverse and internal photoemission – electronic structure, band alignment, defects
• FTIR, XRD, TEM• Electrical – IV, CV
• Growth – ALD, CVD, PVD
Use high resolution physical and chemical methods to examine new materials for radiation induced effects and compare with Si/SiO2/poly-Si stacks
Total dielectric thickness from RBS: ~10 to 11 nm
RBS & CV of HfSiO/SiO2/p-Si films
Physical characterization Electrical characterization
Total dielectric thickness from CV: ~12 nm
E0 = 1.4 MeV 4He
E1 = KE0
Electron Traps in Hf-based Gate Stacks
G. Bersuker, C. Young, P. Lysaght,
R. Choi, M. Quevedo-Lopez,
P. Kirsch, B. H. Lee
SEMATECH
Electron Trap Depth profile
0.0 0.6 0.8 1.0 1.20
10
20
30
40
50
60
701.1nm SiO
2/3nm HfO
2/TiN
Initial After 300s After 600s After 900sN
t [10
10/c
m2 ]
Probing Depth [nm]
nFET W/L = 10/1 mtr, t
f = 100 ns
Vamp
= 1.4 VV
base = -0.7 V
Vstress
= 2.4 V • Factors affecting conversion of frequency to distance:– Capture cross sections
decrease exponentially with depth
– Recombination rate is limited by the capture of holes
Electron Trap Profile in High- Layers
0 1 2 3 4 5
0
10
20
30
40
50
tr,t
f = 100 ns
PW = 100 s
Interfacial Layer/High-/Anneal ambient SiO
2/MOCVD HfO
2/N
2
HF-Last/MOCVD HfO2/N
2
SiO2/ALD HfO
2/N
2
HF-Last/NH3/ALD HfO
2/NH
3
Ntr
ap [
1012
/cm
2 ]
Distance from Gate [nm]
• Electron traps uniformly distributed across the high-k film thickness
• No significant difference in trap density between deposition methods and anneal ambients
Differences Between the Trapping States in x-ray and -Ray Irradiated Nano-crystalline HfO2, and Non-
crystalline Hf SilicatesG. Lucovsky, S. Lee, H. Seo, R.D. Schrimpf, D.M.
Fleetwood, J. Felix, J. Luning,, L.B. Fleming, M. Ulrich, and D.E. Aspnes
Aim: The correlation of electronically active defects in alternate dielectrics with spectroscopic/electronic details extracted primarily via (soft) x-ray spectroscopies.
i) Processing defects which act as traps for radiation generated carriers
ii) Defects created by the radiation itself.
G. Lucovsky
NCSU
Electronic Structure
spectroscopic studies of band edge electronic structure band edge defects - trapping asymmetry n-
type Si substrates
EOT~7 nm
IMEC group/NCSU
e-traps ~ 0.5 eV below HfO2 CB
h-traps ~ 3 eV above HfO2 VB
1000
104
0 2 4 6 8 10 12 14 16
6p
6s
O2pnb
O-vacancydefect
HfO2
SXPS 60 eV
ph
oto
ele
ctr
on
co
un
ts
binding energy (eV)
5d5/2
T2g
5d3/2
Eg
0.01
0.1
1
5 5.5 6 6.5 7 7.5 8 8.5 9
photon energy (eV)im
ag
inar
y p
art
of
die
lect
ric
co
nst
an
t (
2)
Eg (2 features)
band edge"defect state"
HfO2
S. Zollner,D. Triyoso
0
500
1000
1500
2000
2500
3000
3500
4000
4.5 5 5.5 6 6.5
ZrO2
V.V. Afanas'evA. Stesmans
photon energy (eV)
[ph
oto
co
nd
uc
tivi
ty]1
/2 (
arb
. u
nit
s) Eg band edge
feature
band edge"defect state"
negatively charged O-atom vacancy
0
500
1000
1500
2000
2500
3000
3500
4000
4.5 5 5.5 6 6.5
ZrO2
V.V. Afanas'evA. Stesmans
photon energy (eV)
[ph
oto
co
nd
uc
tivi
ty]1
/2 (
arb
. u
nit
s) Eg band edge
feature
band edge"defect state"
negatively charged O-atom vacancy
1000
104
0 2 4 6 8 10 12 14 16
ph
oto
ele
ctro
n c
ou
nts
binding energy (eV)
4p
3d3/2
Eg
3d5/2
T2g
O2pnb
4s
4p
TiO2
SXPS 60 eV
O-vacancydefect
defects: ZrO2 (PC): TiO2 (SXPS)
Damage fundamentals: SiO2 vs HfO2
Proton stoppingpower
X-ray mass attenuationcoefficient
For same capacitance ---- ~6 times more thickness
HfO2 =CAP
HfO2 =CAP
Silicon Carbide CollaborationVanderbilt: Sriram Dixit, Sarit Dhar, S.T.
Pantelides, John Rozen
Auburn: J. Williams and group
Purdue: J. Cooper and group
Silicon Carbide and SiC/SiO2 Interfaces
Silicon carbide as a radiation damage resistant material
i) High temp, high power applications
ii) SiC-based neutron, charged particle detectors with improved radiation resistance
iii) Materials improvements at all levels in recent years
SiC/SiO2(N) Interfaces
i) “Reveals” new, SiO2 radiation induced defects that fall within the SiC band-gap—4H, 6H, 3C, Si—a form of spectroscopy
N+ Source
Implanted P-Well
N- Drift Region
Oxide
SiO2Surface RoughnessDue to P-TypeImplant Anneal
SiC
MOSFETChannelResistance
Transition Layer
SiC
SiO2
Dangling Bonds
Si - Si Bonds
C - C Bonds
SiC Power MOSFET
N+ SubstrateN+ Substrate
GateSource (VSD)
N+
P base
Drain
N- drift region
SiO2
SiC
ISD
R = Rchan + Rintrinsic
Rchan ~ (mobility)-1
-----
Ev
Ec
sp3 hybrid sp3 hybrid
Bonding orbital
Antibonding orbital
Valence bands
Conduction bands
Logistics & MURI Collaborations
Samples, Processes, DevicesRutgers, Sematech, NCSU
Materials & Interface AnalysisRutgers, NCSU and IBM
Radiation ExposureVanderbilt
Post-radiation CharacterizationVanderbilt, Sematech, NCSU, Rutgers
and IBM
TheoryVanderbilt
Plans• Generation broader range of films and devices with high-K
dielectrics (HfO2) and metal gate electrodes (Al, Ru, Pt).• Interface engineering: SiOxNy (vary thickness and composition)• Expand physical measurements of defects created by high energy
photons and ions using SPM and TEM, in correlation with electrical methods.
• Develop quantitative understanding of behavior as a function of particle, fluence, energy
• Monitor H/D concentration and profiles, and effects on defect generation (by radiation) and passivation.
• Determine if radiation induced behavior changes with new channel materials (e.g., Ge, InGaAs), strain, or SOI
• Explore effects of processing and growth on radiation behavior.• Correlate with first principles theory.
10:40 Overview: Radiation Effects in Emerging Materials
Leonard Feldman, Vanderbilt University11:00 Radiation Damage in SiO2/SiC Interfaces
Sriram Dixit, Vanderbilt University11:20 Spectroscopic Identification of Defects in Alternative Dielectrics
Gerry Lucovsky, North Carolina State University12:00 Lunch – Room 1061:00 Radiation Effects in Advanced Gate Stacks
Eric Garfunkel, Rutgers UniversityG. Bersuker, SEMATECH
SiO1.99 0.02
SiO2.01 0.02
SiO1.99 0.02
SiO2.01 0.02
RBS/CH
SiO2
“No” carbon
SiO2/SiC
Interface State Density-----6H-4H Polytypes
Results
• Generated thin films with high-K dielectrics (HfO2) and metal gate electrodes (Al, Ru).
• Performed ion scattering, photoemission, internal photoemissions and inverse photoemission….on selected systems.
• Had samples irradiated by Vanderbilt group (Feldman)• Performed SPM measurements of defects on selected
systems