Radiation Effects on Emerging Electronic Materials and Devices

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Radiation Effects on Emerging Electronic
Materials and Devices
June 13/14, 2006
Radiation Effects in Emerging Materials Overview

• Leonard C. Feldman
• Vanderbilt University
• Department of Physics and Astronomy
• Vanderbilt Institute on Nanoscale Science and
  Engineering

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Radiation damage in emerging materials

• Gate Dielectrics
• i. High-k on Si
• HfO2/Si, HfSiO/Si - (w and w/o interlayer)
• ii. High-k on Ge HfDyO2/Ge
• iii. SiO2/Silicon carbide

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Other emerging materials i. Strained
silicon ii. SOI iii. SiGe


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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
MURI review June06
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Goals
The 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
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In situ photovoltage measurements using
femtosecond pump-probe photoelectron spectroscopy
and its application to metal-HfO2-Si structures 
Richard Haight IBM
Measures band-bending in an in-situ
configuration, without metal gate, yielding
intrinsic electronic structure
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HARMONIC LASER PHOTOEMISSION
High Harmonic Generation
Ar jet
Photon energies from 15-60 eV
800 nm 35fs
grating
parabolic mirror
TOF detector
e
e
Pump, 800 nm, 35fs
sample
High KE
Main Chamber
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Metal Gate for high-K MOS?
For ideal p-FET
at VG 0
Interface Fermi Level (EIFL)
Vacuum level
j
Sze Phys. Semi. Dev.
cSi

• But
• 1) Metal gate shows a similar problem
• EIFL ? Midgap
• 2) In addition, Vt instability charge trap?

EF
N-silicon
High WF Metal
HfO2
After anneal
Goal Understand the effect of thermal processes
on high-K oxide oxide-metal interface which
affect MOS properties
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• 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

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Rutgers CMOS Materials Analysis
Use high resolution physical and chemical
methods to examine new materials for radiation
induced effects and compare with Si/SiO2/poly-Si
stacks

• 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

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RBS CV of HfSiO/SiO2/p-Si films
Electrical characterization
Physical characterization
Total dielectric thickness from RBS 10 to 11 nm
Total dielectric thickness from CV 12 nm
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Electron Traps in Hf-based Gate Stacks

• G. Bersuker, C. Young, P. Lysaght,
• R. Choi, M. Quevedo-Lopez,
• P. Kirsch, B. H. Lee

SEMATECH
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Electron Trap Depth profile

• Factors affecting conversion of frequency to
  distance
• Capture cross sections decrease exponentially
  with depth
• Recombination rate is limited by the capture of
  holes

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Electron Trap Profile in High-k Layers

• Electron traps uniformly distributed across the
  high-k film thickness
• No significant difference in trap density between
  deposition methods and anneal ambients

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Differences Between the Trapping States in x-ray
and ?-Ray Irradiated Nano-crystalline HfO2, and
Non-crystalline Hf Silicates G. 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.
• Processing defects which act as traps for
  radiation generated carriers
• Defects created by the radiation itself.

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G. Lucovsky NCSU Electronic Structure
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spectroscopic studies of band edge electronic
structure
band edge defects - trapping
asymmetry n-type Si substrates
IMEC group/NCSU
defects ZrO2 (PC)? TiO2 (SXPS)?
e-traps 0.5 eV below HfO2 CB
h-traps 3 eV above HfO2 VB
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Damage fundamentals SiO2 vs HfO2
HfO2 CAP
HfO2 CAP
X-ray mass attenuation coefficient
Proton stopping power
For same capacitance ---- 6 times more thickness
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Silicon Carbide Collaboration Vanderbilt Sriram
Dixit, Sarit Dhar, S.T. Pantelides, John
Rozen Auburn J. Williams and group Purdue J.
Cooper and group
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Silicon Carbide and SiC/SiO2 Interfaces

• Silicon carbide as a radiation damage resistant
  material
• High temp, high power applications
• SiC-based neutron, charged particle detectors
  with improved radiation resistance
• 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-gap4H, 6H, 3C, Sia form of
spectroscopy
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SiC Power MOSFET
R Rchan Rintrinsic Rchan (mobility)-1
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Logistics MURI Collaborations
Samples, Processes, Devices Rutgers, Sematech,
NCSU
Materials Interface Analysis Rutgers, NCSU and
IBM
Theory Vanderbilt
Radiation Exposure Vanderbilt
Post-radiation Characterization Vanderbilt,
Sematech, NCSU, Rutgers and IBM
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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.

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1040 Overview Radiation Effects in Emerging
Materials Leonard Feldman, Vanderbilt
University 1100 Radiation Damage in SiO2/SiC
Interfaces Sriram Dixit, Vanderbilt
University 1120 Spectroscopic Identification of
Defects in Alternative Dielectrics Gerry
Lucovsky, North Carolina State University 1200 Lu
nch Room 106 100 Radiation Effects in Advanced
Gate Stacks Eric Garfunkel, Rutgers
University G. Bersuker, SEMATECH
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SiO2/SiC
RBS/CH SiO2 No carbon
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Interface State Density-----6H-4H Polytypes
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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