Also known as AES Auger SAM 1 Auger Electron Spectroscopy E KLL E K E L E L 2p 1s 2s 12 32 E f K L I L II L III Incident Beam Auger Electron E KLL 0 ID: 1021278
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1. Auger Electron Spectroscopy OverviewAlso known as: AES, Auger, SAM1
2. Auger Electron SpectroscopyEKLL = EK - EL - EL’2p1s2s1/23/2EfKLILIILIIIIncident BeamAugerElectronEKLL050010001500200025003000Kinetic Energy (eV)E N(E)E N(E) x 5EdN(E)/dECu LMMCu MNNAES Spectra of CuNote that Auger peaks are typically superimposed on a large background (see red and magenta spectra).For this reason Auger spectra are typically displayed in a differentiated mode as shown in the green spectrum.Detection limits for AES are approximately 0.1 atomic percent.2
3. Auger Electron and X-ray EmissionIncidentBeamAuger ElectronX-ray PhotonEnergy Dispersive X-ray Spectroscopy (EDX) Auger Electron EmissionIncident BeamIncident BeamAuger ElectronX-ray3
4. AES and EDXPrimary Electron BeamAuger ElectronsParticulate defectsAuger Analysis Volume (5-75 Å)Primary Electron BeamCharacteristic X-raysEDX Analysis Volume (<1 - 5 mm)AES Provides Superior Nanovolume Analysis CapabilitiesEDX minimum analysis area > 1 µm710 AES minimum analysis area 8 nm4
5. AES Analysis DepthMean Free Path: Mean distance electrons travel before undergoing inelastic scattering5
6. Analysis Depth – “Universal” Curve1101001000Energy (eV)1101001000λ (monolayers)nm analysis depthTypical Auger electron energies6
7. Auger Electron SpectroscopyAuger Electron Spectroscopy is an analytical technique that provides compositional information from the top few monolayers of a materialDetect all elements above HeDetection limits: 0.1 – 1 atomic %Surface sensitive: top 5-75 ÅSpatial resolution: < 60 Å probe size (PHI 710)7
8. What Information Does Auger Provide ?Surface composition at high spatial resolutionSecondary Electron ImagingProvides high magnification visualization of the sampleElemental analysis (spectra)Determines what elements are present & their quantityElemental imaging (mapping)Illustrates two-dimensional elemental distributionsHigh energy resolution spectra, imaging and depth profilingChemical state analysis for some materialsSputter depth profilingReveals thin film and interfacial composition8
9. PHI 710 Scanning Auger NanoProbe9
10. PHI 710: Analytical CapabilitiesNanoscale image resolutionImage registration for high sensitivityConstant sensitivity for all geometriesConstant sensitivity with tilt for insulatorsNano-volume depth profilingChemical state analysis10
11. PHI 710: High Spatial ResolutionLocations for Line ScansArea Analyzed4 nm Al LineAlGaAs Line Width (nm)AugerLineScansSample provided by Federal Institute for Materials Research and Testing (BAM)Berlin, Germany123424 hour stability test demonstrating exceptional image registryBAM-L200 Standard SampleGa Map 25 kV - 1 nA 256x256 pixelsAl Map 25 kV - 1 nA 256x256 pixels11
12. PHI 710: High Spatial Resolution4 nm Al Line00.050.100.150.200.250.300.35Distance (µm)IntensityGaAl (X3)BAM-L200 Standard Sample Line Scan #424 hour stability test demonstrating exceptional image registry12
13. PHI 710: Constant Sensitivity for All GeometriesPHI 710Coaxial Analyzer & Electron Gun Geometry02004006008001,0001,2001,4001,6001,8002,000-90-75-60-45-30-150153045607590Tilt Angle (degrees)Sensitivity (kcps)Sensitivity vs. Sample Tilt AngleCoaxial (CMA)Non-Coaxial (SCA)The CMA with coaxial electron gun provides high sensitivity at all sample tilt angles which is essential for insulator analysis and samples with topography13
14. PHI 710: CMA with Coaxial GeometrySecondary Electron ImageNi MapIn MapNo shadowingEvery pixel can be identified as part of a Ni sphere or as part of the In substrate.The Ni particles are complete spheres and the substrate fills in around the particles.Variations in In and Ni intensity provide meaningful compositional information.14
15. Non-Coaxial GeometrySecondary Electron ImageNi MapIn MapShadowingMany pixels are of unknown composition, apparently neither Ni balls nor In substrate. The Ni particles are not observed as complete spheres and very little of the substrate is seen.Variations in In and Ni intensity do not provide meaningful compositional information.15
16. PHI 710 High Energy Resolution ModeHow does the high energy resolution mode work?The CMA energy resolution is given as:ΔE / E = 0.5%An optics element placed between the sample surface and the entrance to the standard CMA retards the Auger electrons, reducing their energy, EFrom the energy resolution equation, if E is reduced, ΔE is also reduced and so is the Auger peak width; energy resolution is improvedThe CMA is not modified in any way and retains a 360º coaxial view of the sample relative to the axis of the electron gunUS Patent 12 / 705,26116
17. PHI 710 High Energy Resolution Mode710 Energy Resolution Specification 0.00.10.20.30.40.50.605001000150020002500Auger Peak Kinetic Energy (eV)ΔE / E (%)17
18. PHI 710 High Energy Resolution Mode136013701380139014001410-50050100150200250300350 1393.4 eV (Al metal)(Al oxide) 1386.9 eVKinetic Energy (eV)N(E) cpsAl KLL Spectra of Native Oxide on Al FoilEnergyResolution0.5 %0.1 %18
19. PHI 710 High Energy Resolution Mode Zn oxide Zn metal97098099010001010102010300 surface510th sputter cycle8.48.68.89.09.29.49.69.8x 105Kinetic Energy (eV)c/s Depth Profile of Zn Oxide on Zn19
20. PHI 710: Spectral Window ImagingBCSi MetalSilicideSi OxynitrideSi KLL Basis Spectra1608161216161620Kinetic Energy (eV)IntensityAComposite Si KLL160516151625Kinetic Energy (eV)IntensityPanel A shows the Si KLL spectrum from the sum of all pixel spectra in the Si KLL Auger image shown in panel B. Panel B shows the three Regions Of Interest (ROI) selected for creation of the basis spectra for Linear Least Squares (LLS) fitting of the Si KLL image data set. Panel C shows the three basis spectra with their corresponding chemical state identifications. Si KLL image with ROI areas20 µm20 µm In the spectral window imaging mode, a Si KLL spectrum is collected and stored for each image pixel.20
21. PHI 710: Spectral Window ImagingASEI20 µm20 µmBSi KLL (all Si) 20 µm20 µm SilicideC20 µm20 µm DSi Metal20 µm20 µm ESi Oxynitride20 µm20 µm Panel A shows a 200 µm FOV SEI of a semiconductor bond pad. Panel B shows the Si KLL peak area image from the area of panel A. Panels C, D and E show the chemical state images of silicide, elemental Si and Si oxynitride respectively. Panel F shows a color overlay of elemental silicon, silicide and silicon oxynitride images. FSi Chemical States20 µm20 µm21
22. PHI 710: Thin Film AnalysisWorld’s best Auger sputter depth profilingFloating column ion gun for high current, low voltage sputter depth profilingCompucentric Zalar Rotation™ minimizes sputtering artifacts and maximizes depth resolutionImage registration maintains field-of-view22
23. PHI 710: Low Voltage Depth Profiling0102030Sputter Time (min)IntensityAsGaAl500 eV Depth Profile0200400600800Sputter Time (min)IntensityAsAlGa100 eV Depth ProfileImproved Interface Definition with use of Ultra Low Ion EnergiesAlAs/GaAs Super Lattice Thin Film Structure23
24. PHI 710: Nanoscale Depth Profiling1P from the growth gas is detected on the surface of a Si nanowire60 nm Diameter Si Nanowire20 kV, 10 nA, 12 nm Beam100300500700Kinetic Energy (eV)IntensityOCSiPSurface Spectrum of NanowireSEIAtom %Si 97.5P 2.524
25. PHI 710: Nanoscale Depth Profiling500 V Ar sputter depth profiling shows a non-homogeneous radial P distributionThe data suggests Vapor-Solid incorporation of P rather than Vapor-Liquid-Solid P incorporationDepth Profile of the Si Nanowire25
26. PHI 710: Compucentric Zalar RotationIon BeamSampleAnalysisAreaZalar rotation is used to reduce or eliminate sputtering artifacts that can occur when sputtering at a fixed angle.Compucentric Zalar rotation depth profiling defines the selected analysis point as the center of rotation. This is accomplished by moving the sample in X and Y while rotating, all under software control.Micro-area Zalar depth profiling is possible on features as small as 10 µm with the 710’s automated sample stage.26
27. PHI 710: Compucentric Zalar RotationSputter Time (min)050100150200250300020406080100Atomic Concentration (%)OAl (oxide)Al (metal)SiCompucentric Zalar Depth Profile of 10 µm Via ContactSecondary Electron Image(Before Sputtering)27
28. PHI 710: Compucentric Zalar RotationDepth Profile Comparison With and Without Zalar RotationWithout Zalar RotationWith Zalar RotationSputter Time (min)050100150200250300020406080100Atomic Concentration (%)Al (metal)OAl (oxide)SiSputter Time (min)050100150200250300020406080100Atomic Concentration (%)OAl (oxide)Al (metal)Si28
29. PHI 710: Compucentric Zalar RotationWithout RotationWith RotationSE Images of 10 µm Via Contacts after Depth Profiling 29
30. PHI 710: Chemical State Depth ProfilingSample:Ni deposited on Si substrateAnnealed at 425°CAnalysis Conditions:As Received0.1% Energy Resolution10 kV-10 nA20 µm Area AverageSputter Conditions:500 V Argon1 x 0.5 mm rasterNo Zalar Rotation10° Sample TiltChemical State of Si ?Chemical State of Ni ?01020304050600100200300Sputter Time (min)Intensity (kcps)Ni LMMSi KLLLarge Area Elemental Depth Profile30
31. PHI 710: Chemical State Depth ProfilingSi from Ni layerSi from substrate01020304050600100200Sputter Time (min)Intensity (kcps)Si KLLFromNi layer1617.2 eV(silicide) From Si Substrate1616.5 eV(metal) 1610161516201625Kinetic Energy (eV)Normalized IntensitySi KLLLarge area Si chemical state depth profilescreated with Linear Least Squares (LLS) fitting0.1% Energy ResolutionSi basis spectra extracted from depth profile data setnickel silicide31
32. PHI 710: Chemical State Depth Profiling0.1% Energy Resolution Ni fromNi layerNi fromSi substrate01020304050600100200300Sputter Time (min)Intensity (kcps)Ni LMMNi fromNi layer846.2 eV(Ni-metal) Ni fromSi substrate844.8 eV(Ni-silicide) 830840850860Kinetic Energy (eV)Normalized IntensityNi LMMLarge area Ni chemical state depth profilescreated with LLS fittingNi basis spectra extracted from depth profile data setnickel silicide32
33. PHI 710: Chemical State Depth Profiling12SEM 20kV - 1nA500100015001.01.52.02.5Kinetic Energy (eV)Intensity (Mcps)SiNiSiSiSiCCNiPoint 1 Point 2 22 nm beam sizePoint 2Si fromSubstrate1616.5 eV(metal) Point 1Si fromMicrostructure1617.2 eV(silicide) 1610161516201625Kinetic Energy (eV)Normalized IntensitySi KLL SpectraMicrostructure observed in SEM image after depth profileSurvey Spectra0.1% Energy Resolution Nano-area spectra from selected areas showing islands of nickel silicide33
34. PHI 710: Chemical State Depth Profiling1212SEM 20 kV - 10 nA Auger Image Color Overlay 20 kV - 10 nANew area on Ni/Si sample with 12 nm removed – microstructures visible Nano-areas selected for analysisCompositional images show presence of silicide microstructures34
35. PHI 710: Chemical State Depth ProfilingNi/Si film chemical state depth profiling summary:The large area depth profiles unknowingly included heterogeneous distributions of nickel silicide microstructures that grew through imperfections in the Ni filmThe nano-area depth profile on the Ni film (off microstructures) shows nickel silicide only at the nickel / silicon interfaceChemical state depth profile frompoint #1 - on film (off microstructure)Created with LLS fitting in PHI MultiPak0204060801001201401601802000100200Sputter Depth (nm)Intensity (kcps)Si metalSi silicideNi metalNi silicide10 kV – 10 nA 22 nm beam size35
36. PHI 710 Scanning Auger NanoprobeMulti-Technique optionsEnergy Dispersive Spectroscopy (EDS or EDX)Backscatter Electron Detector (BSE)Electron Backscatter Diffraction (EBSD)Focused Ion Beam (FIB)The Complete Auger Solution 36
37. PHI 710 Chamber Layout for Options37
38. PHI 710 Scanning Auger NanoProbeComplete Auger Compositional Analysisfor Nanotechnology, Semiconductors, Advanced Metallurgy and Advanced Materials 38