PHI VersaProbe III Scanning XPS Microprobe

Announcing the latest in PHI's line of scanning XPS microprobe instruments - the VersaProbe III. This multi-technique instrument builds on our industry-leading patented scanning microprobe technology and dual beam charge neutralization and takes it to a higher level.

Features of the VersaProbe III:

  • New Low Energy Inverse Photoemission Spectroscopy (LEIPS)
  • New REELS (Reflection Electron Energy Loss Spectroscopy)
  • New Analyzer input lens with 2-3 times higher sensitivity for all analysis conditions
  • New Multi-channel detector for faster elemental and chemical imaging
  • New Angle dependent technology for +/- 5 degree solid angle collection for ADXPS measurements
  • Improved Hot/cold stage providing temperatures of -140° C to +600° C
  • New Dedicated hot sample platen operating up to 800° C
  • New 4-contact transferable sample mount for in-situ controlled potential experiments
  • New UPS design for increased sensitivity and improved energy resolution
  • Improved Auger performance providing higher energy resolution and better signal to noise

Micro-Focused Scanning X-ray Source

The core technology of the VersaProbe III is PHI's patented, monochromatic, micro-focused, scanning x-ray source which provides excellent large area and superior micro-area spectroscopy performance. Spectroscopy, depth profiling and imaging can all be performed over the full range of x-ray beam sizes including the minimum x-ray beam size of less than 10 µm. Unique features this technology provides include:

  • Micro-focused, raster scanned x-ray beam
  • X-ray beam induced secondary electron imaging
  • XPS images with spectra at each pixel for retrospective chemical analysis
  • Point or multi-point spectroscopy
  • Point or multi-point thin film analysis

Large Area Spectroscopy

Turnkey Auto Analysis

  • Point and click analysis area definition
  • Robust Auto-Z sample alignment at all spot sizes
  • No-tune dual beam charge neutralization
  • Move without concern from insulator to conductor in auto analysis sequences

Fully Automated Unattended Analysis

Micro Area Spectroscopy

Superior Micro Area Performance

  • Point and click analysis area definition
  • Robust Auto-Z sample alignment
  • No-tune dual beam charge neutralization
  • Move without concern from insulator to conductor in auto analysis sequences

Sputter Depth Profiling

Optimized Configuration

  • Micro-focused x-ray beam
  • High sensitivity spectrometer
  • High performance floating column argon ion gun
  • Turnkey dual beam charge neutralization
  • Compucentric Zalar Rotation™
  • Micro-area sputter depth profiling
  • Multi-point sputter depth profiling

Organic Sputter Depth Profiling

  • Optional 10 and 20 kV C60 ion guns
  • Optional 20 kV Ar2500+ gas cluster ion gun
    • Mass filtered cluster ion sources
    • Bend in ion column to stop neutrals

Multi-Technique Test Chamber

Integrated Optional Accessories

The VersaProbe III test chamber is designed to accept multiple photon and ion sources that are focused at a common point on the sample and controlled from the SmartSoft-VersaProbe user interface.

  1. Scanning x-ray source
  2. Sample introduction chamber
    Optional intro/prep chamber
  3. Argon sputter ion gun
  4. Electron energy analyzer
  5. Optical Microscope
  6. Five axis automated sample manipulator
    Optional hot / cold version shown
  7. LN2 dewar for sample cooling
  8. Optional sample preparation chambers
  9. Optional C60 sputter ion gun
  10. Optional UV light source for UPS
  11. Optional dual anode x-ray source
  12. Optional electron gun for SAM
  13. Optional 20 kV Ar2500+ gas cluster ion gun

SmartSoft-VersaProbe

SmartSoft

Whether you are a casual user or an expert, the work flow driven UI and enhanced feature set will increase your productivity.

  • Intuitive single window user interface
  • Session tabs guide you through the analysis process
  • Integrated sample platen management
  • Point and click analysis area definition on saved images
  • User friendly queuing of multiple analysis tasks
  • Multi-point analysis and sputter depth profiling within an imaged area
  • Fully integrated control of optional accessories

MultiPak Data Reduction Software

Data Reduction for XPS and AES

PHI MultiPak is the most comprehensive data reduction and interpretation software package available for electron spectroscopy. The tasks of spectral peak identification, extracting chemical state information, quantification, and detection limit enhancement are addressed with an array of powerful and easy-to-use software tools for spectra, line scans, images and sputter depth profiles. MultiPak can be used on the instrument PC to process data in real time or on an off line PC for report generation.

Advanced Data Reduction Tools

  • Auto peak identification
  • XPS chemical state database
  • XPS spectral deconvolution
  • Quantitative analysis
  • Non-linear least squares fitting
  • Linear least squares fitting
  • Target factor analysis
  • Retrospective chemical imaging
  • Batch mode data processing

SXI Demo Video

LEIPS (Low Energy Inverse Photoemission Spectroscopy)

LEIPS - Key Features

  • Obtain information on the unoccupied electronic energy levels
  • Measurement of the electron affinity of the sample
  • Low damage analysis of organic matter
  • Measurement at same location of XPS and UPS

Principles of LEIPS

UPS (Ultraviolet Photoelectron Spectroscopy) and LEIPS energy diagrams for a semiconductor are shown in Figure 1 below. Similar to UPS, LEIPS has the relationship  = Ek + Eb between photon energy (hν), electron kinetic energy (Ek), and electronic binding energy (Eb) measured relative to the vacuum level. However, LEIPS reverses the role of photons and electrons, so one can determine the energy of unoccupied (conduction) levels, not obtainable with UPS.

Features of LEIPS

Inverse photoemission spectroscopy (IPES) measures light generated by irradiating a sample with electrons. LEIPS is very different from conventional IPES and measures near ultraviolet light using low energy electrons of 5 eV or less.  For this reason, electron beam damage to organic samples is dramatically reduced.  On the VersaProbe III, the low energy electron beam is set to a fixed energy and the sample bias is adjusted to sweep the net energy of the bombarding electrons.  Generated ultraviolet light of 5 eV or less is selected by a band pass filter on the atmosphere side of the belljar and detected with a photomultiplier tube.  A plot is then generated of the photon signal intensity (at a fixed energy band pass filter on the detector) vs. net kinetic energy of the bombarding electrons.  Since the photodetector is located outside the belljar, it is easy to select the light energy by replacing the band pass filter.  The low-energy electron gun can also be used as a neutralization gun on the VersaProbe III.

Measurement of Electron Affinity by LEIPS

In LEIPS, the energy (hν) of the detected photons can be changed by changing the band pass filter of the photodetector. When plotting the rising (onset) energy against the band pass energy for each filter, there is a linear correlation, and extrapolation of the line to zero kinetic energy of the bombarding electron yields the electron affinity, as shown in Figure 3. Obtaining the electron affinity is difficult with conventional IPES.

 

Figure 3. (left) LEIPS spectrum of copper phthalocyanine thin film sample (10 nm film on ITO) measured with 3 different band pass filters (BPF) (right) Plot of the rising (onset) energy of the LEIPS spectrum vs. the band pass filter energy.  Extrapolating to zero onset energy yields the electron affinity.

Low Damage Analysis of Organic Matter

A comparison of the degree of electron beam damage on a thin film C60 sample using LEIPS electron energies and conventional IPES energies is shown in Figure 4. When the sample was irradiated with 10 eV electrons, equivalent to conventional IPES, the spectral shape changed, indicating that electronic damage had occurred. On the other hand, in the LEIPS measurement using 5 eV of electron energy, there is no change in the spectrum after extensive measurement time, suggesting that no sample damage has occurred.

Figure 4. LEIPS spectrum of a C60 thin film sample measured at an electron energy of: (left) less than 5 eV with LEIPS, (right) 10 eV, similar to conventional IPES

Analysis Example

Measurement of Both the Occupied and Unoccupied Electronic Energy Levels of a Sample

From the energy of the occupied (valence) level obtained by UPS and the energy of the unoccupied (conduction) level obtained by LEIPS, the whole picture of the band structure can be understood (Figure 5).  By combining these two complementary techniques, LEIPS and UPS, it is possible to know the level of both electrons and vacancies in a semiconductor sample. In addition, the ionization potential can be obtained from the highest occupied molecular orbital (HOMO) of the UPS measurement, and electron affinity can be obtained from the lowest unoccupied molecular orbital (LUMO) of the LEIPS measurement. From the difference in those two values, the semiconductor band gap energy can be calculated.

Measurement at the Same Location for LEIPS, XPS, and UPS

In the VersaProbe III, LEIPS, UPS, Argon and GCIB ion beams, and neutralization beams are all aligned to the XPS measurement position.  This allows for comprehensive evaluation of organic semiconductor materials.

Comparison Table

 
Item  LEIPS  A Conventional Inverse
Photoemission Spectroscopy
 Measurement
 position sample
 Measure same point as XPS, UPS
 Ar gun, cluster ion sputtering source can also irradiate the same position
 Measurement at different position from XPS, UPS
 Sample transport required before and after measurement
 Energy or electrons  ≤ 5 eV
 Low Damage to organic material
 10 eV
 Damage to organic material is large
 Energy selection  Can exchange bandpass filter in
 the atmosphere
 The band pass filter in the ultra-high vacuum
 chamber needs to be vented
 Energy Resolution

 ≤ 0.45 eV
Minimal damage to organic material with high resolution during long acquisitions

 0.6 eV
 Significant damage to organic material in high energy resolution (long acquisitions required)

REELS (Reflection Electron Energy Loss Spectroscopy)

REELS - Key Features

  • Analyze the electronic state and bonding state of the surface
  • Band gap measurement of semiconductors
  • Compare the relative contents of hydrogen
  • Discrimination of sp2 / sp3 bond of carbon

Analysis Example

Band Gap Measurement by REELS

REELS spectrum of SiO  thermal oxide film (25 nm) on Si wafer The peak rises from the energy 8.8 eV lower than the incident electron, and the band gap (* 1) of the SiO 2 film  can be known.

Evaluation of Hydrogen Content in Organic Films by REELS

Due to the rebound effect of hydrogen atoms, hydrogen-derived energy loss peak appears. You can compare the relative contents of hydrogen from the intensity of this peak.

Evaluation of Diamond Like Carbon (DLC) Film by REELS

The diamond (sp 3) and graphite (sp 2) can be used as a reference to determine the bonding state of various DLC films (* 2). By removing the surface contamination without damaging by the  gas cluster ion gun (GCIB), it is possible to analyze the carbon material more precisely.

Principle of REELS

The energy loss spectrum of the backscattered electrons generated by irradiating the sample with electrons reflects the excitation energy generated on the surface and its frequency. From the energy loss spectrum of reflected electrons, it is possible to analyze the electronic state of the surface such as the bonding state of atoms and the band gap.

Structure of REELS

REELS measurement can be made by selecting one of the two electron guns as an option of VersaProbe III. Both electron guns can perform REELS measurement with high energy resolution of 0.5 eV or less according to FAT mode (constant energy resolution).

Electron Gun for REELS

It is a newly developed electron gun with excellent cost performance for REELS measurement. 
You can irradiate stable electrons from hundreds up to 2 kV.

Scanning Electron Gun for Auger Analysis

When Auger option is selected, REELS measurement is possible with scanning electron gun for Auger analysis. 
REELS analysis can be done by specifying the measurement part from the SEM image. 
(Please contact the domestic sales department for details)

Features & Accessories

Standard Features

  • Scanned, micro-focused, monochromatic x-ray beam
  • X-ray beam induced secondary electron imaging
  • Dual beam charge neutralization
  • Large area XPS
  • Micro-area XPS
  • Chemical state imaging with 128 data channels
  • Sputter depth profiling
  • Floating column argon ion gun
  • Compucentric Zalar rotation
  • Angle dependent XPS
  • Five axis automated sample manipulator
  • 25 mm and 60 mm diameter sample holders

Optional Accessories

  • 10 kV C60 ion gun
  • 20 kV C60 ion gun
  • 20 kV Ar2500+ gas cluster ion gun
  • 100 nm Scanning AES
  • UV light source for UPS
  • Dual anode, achromatic x-ray source
  • Sample transfer vessel
  • Hot / Cold sample manipulator
  • Custom sample preparation chambers

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