AXIS Ultra

1
AXIS Ultra

• An Overview of the Instrument

2
Introduction
Analyser entrance slit plate
Lens V7
Electrostatic Lens
Lens V6
Lens V5
Lens V4
Apertures for definition of spot size
Lens V2
Scan Plates
Charge Neutraliser
Sample
Magnetic Lens
Magnetic immersion lens
3
Ultra Spectrometer

• Spectral Mode
• Standard input lens
• Electrons dispersed between inner and outer
  hemisphere, using standard spectrometer
• Common detector plane

4
Ultra Spectrometer

• Image Mode
• Standard input lens
• Electrons pass through outer hemisphere into
  SMA back to detector plane
• Parallel image maintained
• Fast, real time image

5
The Spherical Mirror Analyser

• First Investigated by Sar-El in 1966 and later by
  Tremblay and Roy 1983 and Diamon 1987
• Consists of two concentric hemispheres
• Object and Image within inner hemisphere
• Spherical aberration is zero
• First order energy dispersion zero at image
  position

Outer Hemisphere
Inner hemisphere
Object
Image
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Imaging properties of the spherical mirror

• Two places where no first order radial dependence
  of trajectory on position in image
• Energy dispersion maximum at the second

Energy dispersion
Object
Image
Object
Image
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Energy Analysis in the Spherical Mirror

• Baffle with an aperture within the mirror field
  transmits only a small range of energies

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XPS Imaging with the Kratos Ultra

• Parallel images achieved in seconds
• Variable FOV gt2mm - 100mm
• Spherical Mirror Analyser (SMA) works in FAT mode
• Spatial resolution lt 3mm

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Variable FOV - Real Time Imaging of Au grid
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ExamplesCu grid

• Cu grid
• horizontal bars 20mm
  
• vertical bars 40mm
• Parallel images acquired in 1,5,10 20s
• Fast photoelectron images allow sample alignment
• As sample moves image moves!!

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XPS Imaging of 5 um Cu Grid

• Example to follow!
• 2 min acquisition shows excellent contrast
• Retrospective line scans possible
• gives 25mm pitch
• Edge measurement (80-20)
• 2.2mm spatial resolution

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XPS Imaging of 5 mm bars
2.2 um edge
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XPS Imaging of Layered Materials
Al alloy
Ti layer 8 um
Al/SiC matrix

• Survey of sample in cross-section showed Ti

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Parallel images and small spot data
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Ti Layer Summary

• Ti 2p image acquired in 3 min!
• Retrospective line scan shows 10mm layer
• Spectra acquired from 8mm layer
• example of multipoint spectroscopy
• good signal to background from lt 10 mm area

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What is multi-spectral imaging?

• MCP and SMA used for spectroscopy!
• FAT mode of SMA allows constant DE
• Area limited by spatial resolution (3mm)
• Many areas from one image may be used

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Multi-spectral imaging
Spectra reconstructed from small area eg (lt10 mm)
Energy (eV)
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Spectra from Images

• Record a sequence of images over any energy range
• Sum intensity of pixels within defined area to
  obtain spectral info.
• SiO/Si ring structure
• 10?m defined area in oxide and metal region
• High resolution spectra

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Example Si/SiO2

• Patterned SiO2 on Si wafer
• Multi-spectral imaging acquired through Si 2p
  peak
• Images show complementary SiO2 and Si enriched
  areas
• Si 2p spectra reconstructed from lt 10 um areas
• Note Dark areas are covered by photoresist

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Chemical state images SiO2 ? Si
Si
Decreasing BE
SiO2
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Spectra from Images
Si oxide image
Si metal image
10 um spot size
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Example Au dots on Si

• 5mm Au dots on Si
• Image acquired in 2 mins
• Multi-spectral imaging performed through Au 4f7/2
  peak
• lt 1eV resolution obtained from lt 5mm!

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Au 4f7/2 image and spectra
Medium magnification Au 4f image acquired in 120
secs.
Au 4f spectrum generated Au from 5mm area of
image
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Ag 3d3/2 with Spherical MirrorAnalyser
Spectrum generated from parallel image using the
Spherical Mirror Analyser. At 10eV pass energy,
the Ag 3d5/2 spectrum generated using the SMA lt
0.49eV FWHM
At 20eV pass energy, the Ag 3d5/2 spectrum
generated using the SMA lt 0.49eV FWHM