Applications of high resolution XPS & AES Kratos AXIS UltraDLD The small spot, parallel imaging, multi-technique photoelectron spectrometer Dr Chris Blomfield

Kratos Analytical Ltd Kratos headquarters Manchester UK service/sales centres New York, Tokyo, Singapore, Frankfurt

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All featuring common Axis technology Virtual probe Magnetic lens 1969 ES-100 ES-200 ES-300 XSAM series HS 1984 2004 AXIS Nova AXIS UltraDLD 2003 AXIS Ultra 1997 AXIS 165 1994 AXIS HSi 1991 ES-100 launched 1969 XSAM series 1980-90 Axis series launched 1995 Axis HS 3 detectors 35 Axsi HSi 5 detectors 40 Axis 165 8 detectors 45 Axis Ultra imaging 195 Axis Nova 40 Total units 355 All featuring common Axis technology Virtual probe Magnetic lens Coaxial charge neutraliser Spectral resolution and sensitivity

What is the surface? What happens at surfaces is extremely important in a vast range of applications from environmental corrosion to medical implants. A surface can be thought of as the interface between different phases (solid, liquid or gas). We can think of the surface as the top layer of atoms but in reality the state of this layer is very much influenced by the 2 – 10 atomic layers below it (~0.5 – 3 nm). Surface modification treatments are often in the range of 10 – 100 nm thick. >100 nm can be thought of as the bulk. Surface analysis encompasses techniques which probe the properties in all these ranges.

Surface Analysis - Techniques Available Properties and reactivity of the surface will depend on: bonding geometry of molecules to the surface physical topography chemical composition chemical structure atomic structure electronic state No one technique can provide all these pieces of information. However, to solve a specific problem it is seldom necessary to use every technique available. photons ions electrons EMISSION TRANSMISSION Interaction with material EXCITATION

Surface Analysis - Techniques Available Analytical Technique Signal Measured Elemental Range Depth Resolution Surface info. SIMS Secondary Ions H-U 5 - 30 Å Chemical composition (secondary ion mass spectrometry) Chemical structure TOF-SIMS Secondary Ions H-U, Large Organic 2000 Å (Scanning Mode) Adsorbate bonding (time-of-flight SIMS) Molecules / Cluster Ions TEM Transmitted Electrons X-Rays Na-U EDX N/A (transmission electron microscopy) FE-SEM, EDX Backscattered or Na-U 1 - 5 micrometres (field emission SEM) Secondary Electrons and X-Rays ISS Ions H- U monolayer atomic structure (ion scattering spectroscopy) chemical composition AES/SAM Auger Electrons Li-U 1 - 5 nm chemical composition (Auger electron spectroscopy, scanning Auger microscopy) ESCA/XPS Photoelectrons Li-U 1 – 10 nm chemical composition (electron spectroscopy for chemical analysis, X-ray photoelectron spectroscopy) chemical structure RAIRS IR photons organic, some inorganics monolayer Adsorbate bonding (reflection-absorption infra-red spectroscopy) STM - solid surfaces upper most atoms physical topography (scanning tunnelling microscopy) Analytical Technique Signal Measured Elemental Range Depth Resolution Surface info,

Surface Analysis - Techniques Available

Surface Sensitivity of XPS Penetration depth of the X-ray radiation is 102-103 nm. However, the surface sensitivity of XPS arises from the short distance the photoelectrons can travel in the solid before suffering inelastic scattering. The average distance from the surface a photoelectron can travel without energy loss is defined as the inelastic mean free pathlength (IMFP), λ. Sampling depth, d, defined as the average distance from the surface for which 95% of photoelectrons are detected, d = 3λ. d Photoelectrons out X-rays in d = 3λ

What information do we get from XPS? Surface sensitivity - photoelectron signal from first 1-10 layers of atoms and molecules. Identification of all elements (except H & He) at concentrations >0.1atomic%*. Quantitative determination of the elemental composition. Information about the chemical state (molecular environment) of the element. Non-destructive analysis, including depth profiles, from the top 10 nm. Destructive depth profiles of inorganic materials for 100s of nm. Lateral variations in surface composition at >3µm resolution. ‘Finger printing’ of materials using valance band. *Sensitivity - a sample with a surface of size 1 cm2 - this will have ca. 1015 atoms in the surface layer. In order to detect the presence of impurity atoms present at the 1% level, a technique must be sensitive to ca. 1013 atoms. Contrast this with a spectroscopic technique used to analyse a 1 cm3 bulk liquid sample i.e. a sample of ca. 1022 molecules. The detection of 1013 molecules in this sample would require 1 ppb (one part-per-billion) sensitivity - very few techniques can provide anything like this level of sensitivity.

The X-ray Photoelectron Spectroscopy Experiment Prof. Kai Siegbahn, Uppsala University, pioneered the technique of XPS, producing the first well defined spectrum in 1954 & was awarded a Noble prize for his work in 1981. Since then the basic building blocks of the X-ray photoelectron spectrometer have not changed. However, UHV technology and electronics have improved! X-ray source UHV analysis chamber Electron energy analyser Electron detector sample

The Photoelectron Spectrum – Surveys/Wide Scans Which elements are present and how much have we got? O 1s O KLL Auger C 1s Cu LMM Auger Cu 2p The energy of the photoelectron peak is indicative of the element from which it originated. The number of electrons (peak area) is related to the elemental concentration. Both photoemission and Auger peaks observed in a spectrum. Peaks are superimposed on a rising background, due to inelastically scattered photoelectrons. N 1s Cl 2s Cl 2p Cu 3s Cu 3p

The Photoelectron Spectrum – High Resolution What chemical state are the elements in? O 1s C 1s O KLL Auger O 1s C 1s High resolution spectra show the subtle shifts in energy of photoelectrons originating form different chemical environments.

Chemical State Information The binding energy of an electron is dependent on the atomic orbital the electron occupies and the chemical environment of the atom. The variation of binding energy of a specific photoemission peak provides information on the chemical state of the atom or ion. Valence electron, low binding energy Core level electron, high binding energy

Chemical State Information Typical binding energies for C 1s photoemission peaks from organic materials functional group binding energy (eV) hydrocarbon C-H, C-C 285.0 amine C-N 286.0 alcohol, ether C-O-H, C-O-C 286.5 fluorocarbon C-F 287.8 carbonyl C=O 288.0 2F bound to a carbon -CH2CF2- 290.6 3F bound to a carbon -CF3 293-294 Typical chemical shifts for O 1s photoemission peaks from organic materials carbonyl -C=O, O-C=O 532.2 alcohol, ether -O-H, O-C-O 532.8 ester C-O-C=O 533.7

Quantitative Surface Analysis of Poly(ethylene tetraphthalate) - PET Large Area Survey Peak Position FWHM Raw Area RSF Atomic Atomic Mass BE (eV) (eV) (CPS) Mass Conc % Conc % C 1s 282.000 3.181 1988710.0 0.278 12.011 74.54 68.73 O 1s 530.000 3.623 2089951.0 0.780 15.999 25.46 31.27 O KLL

Quantitative Surface Analysis of Poly(ethylene tetraphthalate) - PET Chemical State Information -(-O-C- -C-O-CH2-CH2-)- = O n 2 3 1 C 1s region C1 O2 O1 O 1s region O(1) 530.8eV 49 at% O(2) 532.1eV 53 at% C(1) 285.0eV 61 at% C(2) 286.5eV 21 at% C(3) 289.2eV 18 at% C3 C2

Monochromated vs non-monochromated X-ray source Monochromated Al Kα excited Ag spectrum Ag 3d Ag 3d5/2 Ag 3d3/2 Ag 3p3/2 FWHM 0.46 eV Ag 3p1/2 Ag 3s Non-monochromated Mg Kα excited Ag spectrum Ag 3d5/2 Ag MNV Auger Ag 3d Ag 3d3/2 FWHM 0.97 eV Ag 3p3/2 Ag 3p1/2 Ag 3s satellite satellite Things to note: loss of rising background, narrower peaks, loss of satellite peaks, movement of Auger peaks

Beyond Large Area Spectroscopy <10 nm thin film thicker layer or multilayers heterogeneous surface angle resolved XPS depth profile parallel imaging selected area spectroscopy

AXIS UltraDLD 240 instruments installed Unique DLD detector technology 128 channel snap shot 3um parallel imaging 15um small spot Research grade performance energy resolution < 0.45eV sensitivity and therefore detection limits Flexible multi-technique configuration XPS, UPS, AES, ISS Large selection of sample preparation

Axis Ultra performance 80eV 40eV 20eV 10eV 5eV

Instrument overview 1 Al monochromatic source 1. 2. 3. 4. 5. 6. 8. 7. 1 Al monochromatic source 2 Mg/Al achromatic source 3 Low energy floating ion gun 4 165mm radius HSA & SMA 5 Transfer lens & aperture/iris 6 TMP 250 l/s for STC Options 7 10 kV Field emission source 8 UPS lamp

Configuration 1. 2. 3. 4. 6. 5. 7. 8. 9. 1 Al monochromatic source 2 Mg/Al achromatic source 3 Low energy floating ion gun 4 CCTV camera port (not shown) 5 Magnetic lens 6 Ion pump offset from SAC 7 TMP 250 l/s for STC Options 8 10 kV Field emission source 9 UPS lamp

Si 2p Spectrum – pass energy 5 eV Peak height 5403 cps Peak fitted spectrum Si 2p3/2 Si 2p1/2 FWHM Si 2p3/2 0.367 eV oxides Native oxide

Ag Fermi edge - RT – pass energy 5 eV Ag EF < 250meV Large area (700 x 300 microns) Ag 3d5/2 Fermi Edge spectrum recorded at 5 eV pass energy and 600 W X-ray power. 16% - 84% Edge resolution = 0.233 eV

Ag 3d5/2 – pass energy 5 eV Ag 3d5/2 peak resolution (FWHM) = 0.445 eV, ~250KCPS

High sensitivity means high detection limits or fast analysis time

Typical high sensitivity available Improved detection limits <0.05% allow analysis of low concentrations of elements Al-Zn-In anodes are used to protect marine steel structures from corrosion. study with XPS of the active In element reveals surface segregation to a maximum of 4% over 1 year exposure

Low concentration In 3d quantification In 3d3/2 used for quantification Overlap with Ca 2s

XPS shows surface concentration of In during corrosion Cut anode surface used to represent bulk XPS In 0.02wt% GDOES In 0.0185wt% As cast anode surface ~1wt% In Corrosion tests show an increase to 4wt% over 1 year simulated corrosion

Analysis of insulators

Origin of Charge Neutralisation Electrons Magnetic Lens Pole Piece (2) Charge balance plate (-ve potential) (1) Filament (3) Low Energy Electron Trajectory in the Magnetic Field Sample 1) Electrons are thermionically emitted from the charge neutraliser filament. 2) Negative potential of the charge balance plate forces the charge neutralisation electrons towards the sample. There is no direct line of sight of the filament with the sample. 3) The low energy electrons are confined by the magnetic field of the magnetic immersion lens, following an oscillating path between sample and charge balance plate. 4) As sample develops a positive charge, charge neutralisation electrons are attracted to the surface.

Neutralisation of Rough Samples 200 microns 800 microns C 1s spectrum from wood fibres The sample of wood pulp fibres shown in the optical image to the right would traditionally be an extremely difficult sample to charge neutralise. However, as demonstrated by the excellent resolution on the C 1s spectrum poses no problem with the AXIS co-axial charge neutraliser.

Charge Neutralization Fully automatic system standard parameter for 99% of samples Simple software electron only source No Ar* ions Works on topographic samples There are only three parameters to define for the charge neutralisation system. Normal user operation of neutraliser

Neutralization of Rough Samples Kratos neutralisation system - electrons following a spiral path Collimated electrons or ions from a low energy electron/ion source + + + + + + + + + + + + rough sample surface For a rough sample, parts of the surface may be shadowed from neutralisation electrons originating from a collimated electron gun so that the sample will only be partially neutralised. This is overcome by the Kratos charge neutralisation system, where the low energy electrons reach the sample from all directions as a result of their spiral trajectory

Neutralization of Insulating samples XPS performance on insulators for the UltraHSA is guaranteed by specification defined using a polymer. The standard used is PET (polyethylene terephthalate) which has the chemical structure shown. The specifications are defined as the cps from the CC,CH component at 285eV and the FWHM of the ester component ( C-C(=O)-O- ) at ca.289 eV. Sensitivity of CC,CH component (cps) FWHM of ester peak (eV) resn 700x300um 110um 0.68eV 16,000 2,500 1.0eV 135,000 12,000 1.3eV 200,000 20,000 area

PET performance data

Effect of PE on measured data Clear loss of chemical resolution evidenced in carbonyl peak 10 eV PE FWHM = 0.68eV 40eV PE FWHM = 0.83 eV

Neutralization of Rough Samples 200 microns 800 microns C 1s spectrum from wood fibres The sample of wood pulp fibres shown in the optical image to the right would traditionally be an extremely difficult sample to charge neutralize. However, as demonstrated by the excellent resolution on the C 1s spectrum poses no problem with the AXIS co-axial charge neutralizer.

XPS Analysis of Plasma Deposited Coatings Survey spectrum of plasma treated nylon confirming a large amount of surface F incorporation. Quantification of the XPS spectra gave 55% Fluorine on the surface. A high resolution C 1s spectrum recorded at 10 eV pass energy demonstrates the excellent spectral resolution achieved on these irregular, highly insulating samples. The resolution allows confident identification of many of the chemical functionalities present: C-H; C-CF/C-CO2; C-CFn/C-O; C-F/C=O; CF-CFn/CO2; CF2; and CF3.

XPS Analysis of Plasma Deposited Coatings Overlay of C 1s spectra recorded from the wet chemical fluorosolvent treated fabric before washing, after 5 washes and after 5 washes and ironing. Wet chemical treatment 5 Washes 5 washes + ironing High resolution C 1s spectrum of wet chemical fluorosolvent treated nylon after 1 wash and 5 washes demonstrating loss of surface coating

Small area analysis

The Selected Area Aperture

Selected Area Aperture The selected area aperture is used to define a small analysis area at the surface. There are two approaches that may be adopted to allow XPS analysis from areas in the micron range. One approach is ti insert an aperture into the electrostatic lens column, as shown in the figures below, to forma virtual probe at the surface. An alternative approach is to use a focussed excitation source with the transfer lens collecting photoelectrons from the irradiated area. Selected area spectroscopy and mapping is descried in greater detail in technical note MO224 (available from Kratos Analytical). 110mm analysis area 27mm analysis area Selected area apertures Angle defining iris Analyser entrance slit Electrostatic lens column

AXIS Electron Optics : Selected Area and Scanned Imaging Plan view of sample x y Selected area apertures Angle defining iris Analyser entrance slit Beam scanning plates, x & y 27mm analysis area Fixed x,y voltage applied to scan plates to deflect analysis position to defined position on sample. Scanning x,y voltage applied to scan plates to deflect analysis position over defined area of sample to generate a map.

Plasma modification and Patterning Substrate : Polystyrene with surface modified by exposure to CFx containing plasma. TEM grid then used as a mask and sample reintroduced into a plasma chamber. Substrate and grid exposed to C-O, C-N containing plasma. Can pattern be observed? What further information can be extracted from the images? PS CFx functional groups PS C-O,C-N functional groups

Plasma modification and Patterning As the sample was a clear polymer sheet with thin plasma modified layer there was nothing to see optically. A large area (300x700um) survey spectrum acquired from the sample showed photoelectron peaks from fluorine, oxygen, nitrogen and carbon. A quick parallel image corresponding to the fluorine gave a well resolved grid pattern. To better characterise the chemistry of the surface small spot spectra were acquired. - Large area (300x700um) survey scan from patterned area F 1s O 1s N 1s C 1s - F 1s parallel image for 60 sec.

Defining the selected area spectrum position The parallel image is used to define the position for the small spot spectra by simply clicking with the mouse and importing the position into the acquisition software shown to the right. The virtual probe is deflected to the defined position using the beam scanning plates. CF3 CF2 CC,CH CO,CN

Imaging XPS

The Spherical Mirror Analyser (SMA)

Parallel Imaging Mode of AXIS Ultra Outer hemisphere of HSA Charge neutraliser Spherical mirror analyser (SMA) Hemispherical analyser (HSA) Magnetic lens Sample Selected area aperture Objective lens Delayline detector Retarding projector lens Objective lens produces magnified photoelectron image I1 Projector lens produces image I2 retards to pass energy E0 Magnification at detector variable from <5x to >100x Field of view on sample from >2mm to <100mm Lateral resolution to <2mm Operation in FAT mode and provides energy resolution comparable to HSA. I1 I2

SMA and Parallel Imaging Fast Parallel XPS Imaging as the sample is moved, so the photoelectron image moves. Lateral Resolution specification < 3 mm Fixed analyser transmission (FAT) mode energy resolution constant at all binding energies. good energy resolution at all binding energies. ‘Real time’ chemical state XPS imaging ability to differentiate between elements in different chemical states.

Variable Field of View - Real Time Imaging of Au grid 800 mm fov 400 mm fov 400 mm fov 2 mm fov 200 mm fov Au images acquired in less than 60 secs. Field of view (f.o.v.) changed by selecting predefined lens modes for a specific magnification. The new f.o.v. is displayed within seconds.

XPS Imaging of 5 mm Cu Bars 2.2 mm edge 25mm from centre of bars After acquisition of the image a line scan can be generated. The line-scan can be processed to provide edge measurements, giving an indication of lateral resolution

Fast real-time imaging Au finder grid Parallel images acquired in 5,10, 20 and 60 seconds Fast photoelectron images allow easy sample alignment As sample moves … image moves!!

Large area fast parallel imaging 3.2 x 3.2mm image 7um spatial resolution 300 sec total acquisition time 1.6 x 1.6mm image 3um spatial resolution 300 sec total acquisition time

Spectra from Images With AXIS Ultra The experiment requires the acquisition of a sequence of images over any energy range. 300 - 270eV with 0.2 eV steps corresponding to C 1s region. 30 sec per image - total acquisition 75 mins Sum intensity of pixels within defined area to obtain spectral information form that area Set of images as a function of Binding Energy (eV) x (mm) y(mm) 256x256 pixels 270eV 300eV

Spectra from images As generated It is possible to use the image dataset to reconstruct a spectrum. The example below shows a spectrum generated from a single pixel (blue) using the raw images. When the noise has been removed from the image dataset using the PCA approach a much more convincing spectrum is shown. This spectrum was defined from a single pixel 1.4 x 1.4um area ! It is possible to generate a spectrum from any of the 256 x 256 pixels on the imaged area – over 65,500 spectra !! As generated spectrum generated from significant PCA components

Spectra from Images C 1s spectrum generated from 5x5 pixels -CF2 CC,CH CO C=O -CF2 -CF3 After generating spectrum from images it is then possible to deconvolute the data and fit with components. An image may then be generated corresponding to a specific component. Has the advantage that peak shifts may be accommodated in by the model. Integrating area under the peak allows chemical state images show relative concentrations.

Quantitative Elemental and Chemical State Imaging CH, CC CO, CN C=O CF2 -CF3 Fluorine Nitrogen Oxygen

Large area imaging – image stitching

CdTe / CdS / ZTO / CTO / glass stack ZTO (ZnSnO) CTO (CdSnO) CdS CdTe Approximate thickeness / nm 20 1000-350 XPS imaging used for film continuity

NREL CIGS Sample : XPS images 100 mm In photoelectron image 90 sec acquisition 100 mm Na photoelectron image 240 sec acquisition

NREL CIGS Sample : XPS stitched images In XPS image (9x4) stitch Na XPS image 1mm 1mm

NREL CIGS Sample : XPS stitched images Overlay of In (9x4) stitched image (red) and Na (9x4) stitched image (blue)

NREL CIGS Sample : selected area XPS Na 1s Cu 2p O KLL In MNN In 3p O 1s In 3d Na KLL C 1s Se 3p Se LMM Se 3d Na 2s Ga 3d / In 4d 27um selected area XPS 100 mm defect substrate

Angle resolved XPS

Angular Dependence of XPS photoelectrons photoelectrons X-rays X-rays d d d ~ 8-10 nm

Si wafer with native oxide Carbon Si Oxide Si Bulk 0° to sample normal Bulk Sensitive 70° to sample normal Surface Sensitive Si 2p1/2 Si 2p3/2 Si Hydroxide Si oxide

Si wafer with native oxide Si sample with native oxide was not cleaned prior to analysis. Sample tilted from 0° through 70° with steps of 10° The contribution from Si oxide and Si hydroxide convoluted components have been combined.

MEMs Depth Profile Reconstruction for Si wafer with native oxide

‘Banana Shaped’ SAM Molecules Sample A – 14-F-P-11a Sample B – 14-P-F-11a Chemical Formula – C59H69FO10 HF used for the removal of native oxide on Si wafer. Hydrogen terminated Si-surface covalently reacts with alkene chain end to form strong Si-C bonds Detailed studies using AFM, water contact angle and ATR-FTIR techniques have shown that the monolayer is densely packed and well ordered.

‘Banana Shaped’ SAM Molecules Sample A – 14-F-P-11a Sample B – 14-P-F-11a

MEMs Depth Profile Reconstruction – Sample A

MEMs Depth Profile Reconstruction – Sample B

MEMs Depth Profile Reconstruction – Depth Distribution of Fluorine Sample A Sample B

XPS depth profiling - inorganics Accepted standard technique for analysis of inorganic samples Improvements in small spot XPS mean small etch craters can be used Etch rates in the range of 1 – 50nm min-1 (Ta2O5) Recent advances in ion gun technology have lead to lower primary ion energies for improved interface resolution.

Al2O3-Mg2F-SiO2-Si 250V beam energy Al 2p F 1s Mg 2p Si Oxide Si Elemental

Multilayer sample 750 V Ar+ Etch conditions: 750 V, 3 x 3 mm raster, 60 s etch cycles. Etch rate on Ta2O5: 2.3 nm/min Acquisition: 10 s snapshot spectra, cycle time 2min 50 s Total acquisition time: ~14 hours width of last Al layer fwhm 63nm width of 1st Al layer fwhm 58nm

Multilayer sample 750 V Ar+ Example of 10s Ga 2p snapshot spectra 110 µm are of analysis surface layer 1 layer 3 layer 5

SiC/Si : high resolution snapshot spectra Si 2p region Si (elemental) Si (carbide) Si (oxide)

SiC/Si : Elemental depth profile Oxygen Silicon Carbon 750 V Ar+ ions 3x3mm rastered crater

SiC/Si : Si chemical state depth profile Si (elemental) Si (carbide) 1 surface 3 SiC/Si interface Si (elemental) Si (oxide) Si (carbide) Si (oxide) Si (elemental) Si (oxide) Si (carbide) 2 SiC sub-surface 4 bulk Si (elemental) Si (elemental) Si (carbide) 1 2 3 4

Auger electron spectroscopy - AES

FE-Auger Electron Source Field emission electron source and ion pump shown here in situ on an AXIS Ultra.

Hi Magnification SEM with Linescan 5 microns 266 nm resolution measured using 80% - 20% line scan from SiO2 / Si sample.

Si KLL Auger spectra Si KLL oxide Si KLL elemental

Si wide scan Auger spectra

O KLL Auger map and SEM 20 microns

Atmospheric corrosion of nickel SEM images The atmospheric corrosion of nickel in a rural atmosphere – the formation of sulfate-containing corrosion products with a characteristic dendritic morphology. I.Odnevall & C. Leygraf J.Electrochem. Soc., vol 144, No. 10, October 1997, 3518-3525

Atmospheric corrosion of nickel AES after light etch substrate Ni Ni X Ni O C X dendrite O S Ni Ni Ni AES spectra show the presence of sulfur in the dendritic structure only. C

Atmospheric corrosion of nickel AES maps S (p-b) map O (p-b) map Ni (p-b) map The images shown are peak - background maps.

Duplex stainless steel UNS S32750 SEM & AES In duplex stainless steels the alloying elements are not uniformly distributed between the two phases (austenite and ferrite). For example Cr and Mo partition to the ferrite phase and Ni and N to the austenite. austenite - light Fe Cr Fe Cr Fe X Ni C Ni ferrite X austenite ferrite - dark Cr ferrite Cr Fe Fe Fe The sample was etched to remove the surface oxide before the SEM and AES were acquired. There was a slight difference in the Cr intensity between the two areas. Cr and Ni maps were acquired to investigate any spatial differences in their concentrations. C Ni Ni M. Femenia, J. Panl & C. Leygraf J.Electrochem. Soc., 151, (10) B581-B585 (2004)

Duplex stainless steel UNS S32750 AES maps Cr p-b map Ni p-b map The Cr concentration is highest in the ferrite where the Ni concentration is lowest (austenite). The N concentration should be highest in the austenite region. Further AES spectra, with longer acquisition times, were recorded to try and detect the low level of nitrogen present.

SEM Image of 1 micron Au Pattern on integrated IC An SEM image of the Au pattern was recorded using a 30 micron field of view.

SEM Image of 1 micron Au Pattern Line scan used to measure one of the Au lines from the SEM image

Auger Spectroscopy Au MNN Al KLL Au OPP O KLL C KLL S LMM Auger spectra were recorded from on one of the pads (red) and the substrate (blue) Al LMM

Back Scattered Image of 1 micron Au Pattern Sample was then etched and a back scattered image recorded with a 10 micron field of view.

Auger Maps Auger maps were recorded of the Au MNN and Al KLL peaks. Images displayed below are peak minus background maps recorded using 64 x 64 pixels and 100 ms dwell time. Total time for each image was 410 seconds (820 seconds for peak and background). Al KLL Map Au MNN Map

Auger Maps Overlay of Au MNN and Al KLL peak minus background maps recorded using 150 x 150 pixels and 50 ms dwell time.

Auger Maps: 100nm spatial resolution 100 nm 80/20 resolution measured across a feature in Auger mapping mode.

Corrosion Pit: Cu on Au An SEM image of a corrosion pit was recorded using a 400 micron field of view.

Auger Spectroscopy In corrosion pit Outer ring Corrosion pit Au MNN Auger spectra were recorded from in the corrosion pit (left) and the outer ring (right) Cu LMM Cl LMM O KLL S LMM Au NOO

Auger Maps Au MNN Map Cl KLL Map S LMM Map Cu LMM Map

Sample 4 : Auger Maps Overlay of Au (red), Cu (green) and Cl (blue) peak minus background Auger maps

SEM Image of Corrosion Pit following an etch An SEM image of a corrosion pit was recorded following an Ar ion etch

Auger Spectroscopy of corrosion product Auger spectrum recorded from the corrosion product Cu LMM Cl LMM O KLL

Ultra Violet Photon Source Optimized for maximum He (I) or He (II) (or Ne (l)/Ne (ll)) output. 1mm diameter guide to give a maximum lamp current of 37mA at17.5W Minimum step size energy scale is 0.25meV in UPS mode.

Ag 4d reference data: UPS >1.5MCPS Ag EF = 95 meV.

Ag 4d reference data: UPS Hi (II) Ag 4d

XPS/UPS of synthetic diamond Optical image of synthetic diamond

XPS/UPS of DLC Element O 1s C 1s rel. atomic conc. 30.8 70.2 O 1s C 1s O KLL

In-situ heating of DLC sample Sample heated to 450°C to reduce contamination Heating and cooling controlled directly from software

Post annealing Element O 1s C 1s rel. atomic conc. (% 1.3 98.7 C KLL O KLL

Φ= 4.15eV Heated Diamond Sample – He (I) UPS EO= 17.8eV Φ= 21.22eV – (17.8eV – 0.73eV) Φ= 4.15eV EF = 0.73eV

Small area XPS and XPS imaging Teflon tube Silicon containing plasma

Plasma treated polymer tube : survey spectra scanned spectra plasma treated end of tube cut end of tube Si 2p Si 2s C 1s N 1s O 1s F 1s F KLL O KLL survey spectra from 110um analysis area

Concentration line scan by 110um, classic small area analysis Several mm’s Plasma

Plasma treated polymer tube : high resolution spectra scanned spectra N 1s region Si 2p1s region plasma treated end of tube cut end of tube C 1s region

Plasma treated polymer tube : high resolution spectra CC,CH C-O/C-N C=O/CF CF2 CF3 plasma treated end bulk polymer end representative C 1s spectra as a function of position from the end of the tube

Plasma treated polymer tube : Chemical state images CC,CH (peak-background) parallel image at 285eV 120 sec acquisition CF2 (peak-background) parallel image at 292eV 120 sec acquisition overlay of CC,CH (red) with CF2 (green) parallel images

Plasma treated polymer tube : elemental images 800 mm2 field of view CF2 (peak-background) F 1s (peak-background) 120 sec acquisition 60 sec acquisition

Plasma treated polymer tube : chemical state & elemental images 400 mm2 field of view CC,CH (peak-background) parallel image at 285eV 180 sec acquisition CF2 (peak-background) parallel image at 292eV 180 sec acquisition F 1s (peak-background) parallel image at 689eV 90 sec acquisition

Plasma treated polymer tube : selected area spectroscopy 400 mm2 field of view Analysis position Atomic Concn   %   Fluorine Oxygen Nitrogen Carbon Silicon Point 1 45.87 4.66 1.74 45.34 2.39 Point 2 27.33 9.87 6.11 50.07 6.72 55um analysis area p1 (substrate) p2 (plasma polymer) F 1s O 1s N 1s C 1s Si 2p Si 2s

Plasma treated polymer tube : selected area spectroscopy 400 mm2 field of view 2 1 55um analysis point 1 55um analysis point 2 F-Si (inorganic) C-F2 - organic CC,CH C-O/C-N C=O/CF CF2 CF3

Stitched images - 12 x 800 mm2 field of view F 1s image 30 sec per image Total acquisition time 5 mins open, plasma treated end cut end of tube Si concentration F concentration

Quantitative imaging and multivariate analysis Value can be added to XPS images by the use of multivariate analysis methods Here a disc shape specimen of ASTM F 138 stainless steel, shown in the optical image above was machined, electropolished and laser marked. The area of interest is shown in the expanded view with the blue box indicting the area imaged with XPS.

Medical grade stainless steel Fe 2p images Sum of pixels (raw data) Fe 2p3/2 Acquire Fe 2p3/2 multi-spectral images 720-698eV, 0.25eV steps, 30 s per image Cr 2p multi-spectral images, 0.25eV steps, 30 s per image Fe 2p images 719eV 710eV (oxide) 706.5eV (metal) 700eV background binding energy

Fe 2p3/2 region abstract factors (1) Mean AF (2) Maximum variance (3) (4) Acquire Fe 2p3/2 multi-spectral images 720-698eV, 0.25eV steps, 30 s per image Cr 2p multi-spectral images, 0.25eV steps, 30 s per image Process: Convert image dataset to 256 x 256 spectra at a pixel SVD sort / reduced PCA to order AF’s Construct images from the first 2 abstract factors

Raw & SVD/reduced PCA processed data Summed pixel intensity from 256x256 pixels Raw data SVD/reduced PCA processed Fit components to processed data corresponding to Fe oxide and Fe metal Single pixel spectrum from metallic region Single pixel spectrum from oxide region

Quantitative Cr and Fe images Chromium relative atomic concentration image Iron (metal) relative atomic concentration image Cr image (red) shows enhanced concentration at the edge of the laser marked area Cr rich region at ‘corrosion front’ Fe metal (green) across entire sample but much lower concentration on laser marked area oxide layer thicker in laser marked area attenuates the Fe metallic signal

Pixel grouping False colour range used to assign pixels Fe 2p 3/2 METAL OXIDE False colour range used to assign pixels Raw pixels then summed to give “true” spectra from oxide and metal region

Monomers used to generate sample array Image stitching – high spatial resolution over large image areas Monomers used to generate sample array glass slide poly(hydroxyethyl methacrylate) (pHEMA) Acrylate, diacrylate, dimethylacrylate and triacrylate combinations (as above) 1:40pm BO+PS+AS+SS TuA1 Room 201 “High throughput surface chemical analysis of polymer microarrays: Wettability, protein adsorption and cell response” D.G. Anderson, S. Levenberg & R. Langer Nature Biotechnology 22 (7) 863-866

Quantitative elemental stitched images 2mm Fluorine (peak-background) Oxygen (peak-background) Carbon (peak-background) Quantitative elemental images corrected for transmission function and RSF Thermal scale now indicates relative atomic concentration at a pixel - each pixel represents 6.25um on the surface

Quantitative elemental stitched images Fluorine 11.4 at% 0 at% 90.6 at% 60.8 at% Carbon Oxygen 32.5 at% 7.1 at% 2mm

10 reasons why Axis Ultra is best selling XPS Only instrument to offer 0.48eV @ 400,000CPS Excellent performance on insulators < 0.68eV PET Largest analyser 165mm radius DLD – pulse counting quantitative parallel imaging DLD – snapshot mode 128 data channels Fully automated control of all spot sizes Electron only charge neutralisation system Smallest analysis area 15um Two analysers optimised for imaging and spectroscopy Electrostatic deflection system for small area spectroscopy