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Problem Solving and Failure Analysis by Auger and ESCA
M. Roth
Empa Duebendorf
Lecture «Advanced Materials and Structures» Institute of Metals Research, Shenyang, October 21-23, 2013
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Surface Analysis
Problems at surfaces and interfaces Surface Analysis: Methods Auger-Electron-Spectroscopy (AES, SAM) X-ray-Photoelectron-Spectroscopy (XPS, ESCA) Case studies: - Heat-protection coatings on architectural glasses (ESCA) - Damaged pressure sensors (ESCA + SAM) - Surface contamination on HF-reciever coils (SAM) - Adhesion of diamond-like carbon coatings (SAM) - Development of biocompatible coatings (SAM) Conclusions
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Important Surface Phenomena
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Surface analysis: methods
Lateral resolution
Info
rmat
ion
dept
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Surface analysis: physical processes
Ekin = hν - EB
Auger
ESCA
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Auger ESCA
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Scanning Auger Microscope
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ESCA-Microscope
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ESCA-analysis method
Imaging ESCA:
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ESCA-analysis method
C (1s) Photoelectron signal of PET: Determination of different chemical positions of C-atoms
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Auger - ESCA
Lateral resolution:
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Coatings for heat protection glasses
Object: Glass for buildings Material: SiNa-Oxide Problem: Identification of the heat protection coatings Information: Complex coating system (total thickness: ca. 70 nm) Analysis: ESCA – depth profile analysis
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Coating on glass: depth profile coating 1
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Coating on glass: depth profile coating 2
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Coating on glass: depth profile coating 3
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Coatings for heat protection glasses
3 different coatings
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Coatings for heat protection glasses
Object: Glass for buildings Material: SiNa-Oxide Problem: Identification of the heat protection coatings Analysis: ESCA – depth profile analysis Result: Complex coating system (total thickness: ca. 70 nm) - First layer: Sn-Oxide - Ti-Oxide (In-Oxide) - Ag (3 nm !) - ZnCr-Oxide - Sn-O-N - (ZnCr-Oxide) - SiNa-Oxide (glass) Goal: Reflection of IR-radiation
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Damaged pressure sensors
Object: Pressure sensor Material: SiO2 – substrate material with Ni/Cr – conductors Problem: Zero point drift Analysis: ESCA– and Auger measurements at defective and good sensors
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Sensor: conductor tracks
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Sensor: conductor tracks Process: ESCA – sputtering and measure signal for Cr
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ESCA spectrum of SiO2 - layer
Fluorine !
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Sensor: conductor tracks Process: ESCA – sputtering and measure signal for Cr
Transfer of specimen to Auger Microscope
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NiCr-conductor track
Auger analysis:
SEM image
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Auger-spectrum of NiCr-conductor track
Good sensor
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Auger-spectrum of NiCr-conductor track
Defective sensor
Sulphur
Phosphorus
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Damaged pressure sensors
Object: Pressure sensor Material: SiO2 – substrate material with Ni/Cr – conductors Problem: Zero point drift Analysis: ESCA– and Auger measurements at defective and good sensors Result: 1) Removal of SiO2–layer: ESCA – sputtering 2) Analysis of SiO2–layer: 1 – 2 % F 3) SEM: higher roughness of defective sensor 4) Auger–analysis: Cl, S, P on conductor NiCr – passive layer is destroyed by corrosion
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Surface contamination
Object: High frequency recieving coil for nuclear magnetic resonance spectroscopy (NMR) Material: Superconductor, coated with 1 µm Cu and 0.2 µm Rhodium Problem: Colouring of the surface (after 2-3 months) Distortion of NMR signal Analysis: AES-depth profile analysis at coloured and good (new) coils
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Auger depth profile new coil
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Auger depth profile coloured coil
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Surface contamination
Object: High frequency recieving coil for nuclear magnetic resonance (NMR) spectroscopy Material: Superconductor, coated with 1 µm Cu and 0.2 µm Rhodium Problem: Colouring of the surface (after 2-3 months) Distortion of NMR signal Analysis: AES-depth profile analysis at coloured and good (new) coils Result: 1) New coil: - AES-depth profile: S in Rhodium layer (ca. 15%) 2) Coloured coil: - AES-depth profile: S + Cu in Rhodium Layer ca. 4 % Cl at the surface Formation of Cu2S and CuS compounds, which are instable against Chlorine and humidity
Degradation of the Rhodium Layer
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Thin film technology / adhesion
Object: Dry bearings in machinery components Material: Coatings from amorphous diamondlike carbon Fabrication: Plasma enhanced CVD (at ≤ 200 oC) Properties: - high hardness (4000 – 6000 HV) - high elasticity - low coefficient of friction - ADLC/steel: µ = 0.09; ADLC/ADLC: µ = 0.02 – 0.04 - very high chemical stability - high heat conduction - thermal stability until 250 oC Problem: Adhesion of ADLC on substrate Analysis: AES-depth profile at the interface coating/substrate - detection of trace elements - analysis of precipitates
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Application of ADLC-coatings
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Coating: 60 nm ADLC on Si-substrate
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Adhesion of ADLC
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Adhesion of ADLC
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Surface analysis for biological applications
Biological reactions on an implant strongly depend on the first atomic layers Characterization of the top surface (nm) with good lateral resolution On metal implants like artificial hip joints the surface consists of an oxide layer Corrosion protection Bioreaction Example: Ti-6Al-7Nb implant alloy Al-rich oxide regions above the α-phase Nb-rich oxide regions above the β-phase Research: Alloy development Surface conditioning (control of oxide layer, thickness, etc.) Coating (diamond-like carbon)
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SAM: SEM-image
α-phase: dark β-phase: white
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SAM: O-map
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SAM: Ti-map
α-phase: Ti-rich
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SAM: Al-map
α-phase: Al-rich
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SAM: Nb-map
Nb2O5 distribution on the surface of the TiAlNb-implant (above β-phase)
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Summary 1) Surface analysis: SAM: - depth 0.5-3 nm, lateral 30 nm - SEM-images - element mapping - depth profiles - fracture device in UHV ESCA: - depth 0.5-3 nm, lateral 10 000 nm - chemical information (valence) - depth profiles 2) Failure analysis = problem solving Use first basic (cheaper) methods a) SEM/EDX or microprobe (EPMA), chem. Analysis b) SAM, ESCA (and SIMS, SNMS) 3) Costs: - all methods of analysis are available - automation: control and data acquisition by computer - equipment with high reliability - analysis together with customer