Nano analytical electron microscopy for materials and

Transcription

Autumn School on Materials Science
and Electron Microscopy 2005
Nano Analytical Electron Microscopy
for
Materials and Semiconductor Applications
W. Knoll
State of the Art
2200FS
at Oxford Materials,
University of Oxford
that has an in-column energy filter,
double Cs correctors
and will be equipped
with a Monochromator
2200FS Height requirement; 3110 mm
A Cs corrector height is 300 mm
Monochromated 2200FS increases its height
by 400mm
Total increase in height is 1000 mm for
Monochromated x Cs 2200FS.
Current state-of-the-art instrument capability

Analytical Probe sizes less than 0.1nm
TEM resolution 0.08nm or better
Holographic reconstructions less than 0.1nm
FEG: cold/thermal/Schottky
Energy resolution in EELS less than 20meV
- more typical values less than 100meV
- routine values of 700 – 800meV
- Monochromators help
EDS resolution less than 1 eV (1000meV)
CCD Camera images 4K x 4K (8K under development
at UCSD)
Contemporary computer control
- contemporary means TODAY
Directions for the future
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Computer control
Automation
Vacuum
In-situ capabilities
Reconstruction software
Remote control
Resolution
– Energy resolution
– Spatial resolution
1 - Outline
Investigating nanoscale needs improved instruments
1 Preparation of specimen
Specimen size
Portion of damaged surface
2 Elimination of specimen contamination
Specimen size
Portion of contaminant
3 Long time analysis
Specimen size
Signal from the specimen
2 - Matching environmental conditions
Improved HT and lens current Stability
Stability Goniometer Design
Improved vibration isolation
Improved acoustic resonance behavior
3 - Resulting Performance
HAADF image of Si (110) by JEM-2100F/STEM
HR-TEM image of Si(110) Dumbbell by JEM-2100F
Original image
Inverse FFT image
0.136 nm
SA-Diff
FFT
0.5nm
Inverse FFT
(after Masking)
{400} spot
TEM Study of Water in Carbon Nanotubes
Large diameter
MWNT
TEM images of MWNT containing a water plug
Upon e-beam heating, the plug shrank from (a) to © and disappeared in (d)
The position of water, gas and water menisci are indicated in (a)
A carbon internal cap is also indicated - apparently leaking and not blocking water motion
TEM Study of Water in Carbon Nanotubes
Small diameter
MWNT
(a) TEM image showing an empty CVD nanotube with inner diameter of 2.9 nm
(b) After autoclave treatment water is observed in the NT-channels
- but it does not show a meniscus at the water/gas interface
4 Applications to Ultrastructre
Semiconductor
STEM-Tomography
DRAM STEM SEM Image
3D reconstructed
series of SEM images
Tilting angle: -60° to +44° 4°
step
JEM-2500SE + JEM-9310FIB
used
5 - Energy Filtered Microscopy
JEOL In-Column Filter TEMs
- Application: Imaging -
Zero Loss Imaging
IL1
IL2
IL3
IL4
Specimen:Si[110]
Crossover
Image
Image
PL1
PL2
Spectrum
(Energy Slit)
Remove Plasmon Loss Electrons → Intensity is decreased,
but image quality is enhanced
Image quality improvement of 1 mm thick sectioned specimen
Un-filtered
0-loss filtered
δE ~20eV
Zero loss
Intensity (Arb. Unit)
Most Probable Loss (MPL) Imaging
0
100
200
300
Energy Loss (eV)
2um thickness
non-tilted
specimen
Diffraction Pattern Contrast Enhancement
Specimen:
NiMo alloy
UnFiltered
diffraction
UnFiltered
-1
0
G
1
Zero-loss
diffraction
Zero-Loss Filtered
-1
0
G
1
CBED Patterns from Si <111>
Unfiltered
Zero Loss filtered
Maximum takeoff angle 120 mrad
- Application: Spectroscopy -
Wide range of spectrum magnification change
B-K
C-K
Sampling resolution 0.0125 eV/pixel
JEM-2200FS
EELS and HR-TEM Images of Carbon Allotropes
Plasmon loss
C-K
TEM image
Carbon Black
Amorphous
5 nm
Graphite
5 nm
Diamond
Diamond
5 nm
JEM-2200FS
- Application: Energy Filtered Imaging -
Contrast tuning of trench capacitor
JEM-2200FS
Energy-loss Spectra of
Polyolefin/Polycarbonate Blend
s-Plasmon
Polyolefin
JEM-2200FS
p-Plasmon
s-Plasmon
Polycarbonate
Energy Filtered Images of
Polyolefin/Polycarbonate Blend
1 µm
Unfiltered
p-Plasmon Filtered
JEM-2200FS
6 - High Efficiency EDS Collection
Collection angle: 0.28 sr
No X-ray background
contribution from HCA
EDS Mapping
Memory head
HAADF
Ti
C
O
F
300 nm
Al
Clean X-ray background (better S/N) facilitates quantitative mapping.
Need better S/N for statistics? Use line scan.
Spatial drift-corrected mapping
Si
As doping:
25 keV, 5e15/cm2
No annealing process
256x256, x 300.000, 60 min
STEM
O
100 nm
EDS Mix
As
Drift Corrected High-Resolution EDS Mapping of
Plate like Precipitate in Al alloy
(a) Z-contrast
Time Difference
(b) Ag map 10 min
(c) Cu map 10 min
Incident beam // <110>matrix
(a) Z-contrast
(b’) Ag map 60 min
4 nm
(c’) Cu map 60 min
7 - Cs Correctors
Cs correctors, in addition to improving resolution, offer other significant
improvements and benefits. In STEM:
Wider gap – More room…larger tilt, in-situ experiments
Tilt insensitivity – coma is eliminated when Cs disappears. Tilt
tableaus are therefore commonly used to align the corrector in the
STEM mode
Interpretable images – less image delocalization (at interfaces, for
example), familiar contrast
More current – At least 10X improvement…mapping, EELS, small
probe analysis
Probe size vs. current
Sub Å EELS
3 Å EDS
Live ADF imaging
STEM Corrector Lens System
JEM-2200FS
CEOS GmbH
CL
CM
OL
IL
Ω filter
PL
STEM
Cs corrector
(Probe
forming)
CL
CM
OL
IL
Ω filter
PL
Ronchigram
Cs corrector off
11mrad (alpha)
Cs corrector on
40mrad (alpha)
STEM Cs Corrector
Corrected
Cs=0.005
mm
FWHM
0.105 nm
-0.5 -0.4 -0.3 -0.2 -0.1
0
0.1
0.2
0.3
0.4
nm
0.5
Cs Corrected HRSTEM image of Si(110)
(440)
(226)
0.096nm 0.082nm
(224)
0.11nm
(006)
0.0905nm
SrTiO3 <100>
2 nm
M. Kanno, R. Hynes, H. Sawada and M. Watanabe, Lehigh Univ.
Specimen courtesy of John Grazul, Cornell Univ.
β-Si3
4
STEM Cs Corrector
2 nm
Calculated
potential
Tri-rhenium carbonyl clusters on γ-alumina
HAADF of Alumina
with tri-rhenium
carbonyl clusters
deposited
V. A. Bhirud, M. J. Moses, D. A. Blom, L. F. Allard, T. Aoki, S. Mishina, C. K. Narula, and B. C. Gates
M&M Proc. 2005, Submitted
Final ADF image
e-
e-
Single atomic column detection
Er in SiC
Er-M lines
Data courtesy to Drs. D. Muller and U. Kaiser