problem solving and failure analysis by auger and esca m ... · pdf filematerials science...

Materials Sci ence & Technolog y1

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

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

Important Surface Phenomena

Surface analysis: methods

Lateral resolution

Surface analysis: physical processes

Ekin = hν - EB

Auger ESCA

Scanning Auger Microscope

ESCA-Microscope

ESCA-analysis method

Imaging ESCA:

ESCA-analysis method

C (1s) Photoelectron signal of PET: Determination of different chemical positions of C-atoms

Auger - ESCA

Lateral resolution:

Materials Sci ence & Technolog y

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

Coating on glass: depth profile coating 1

3 different coatings

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

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

Sensor: conductor tracks

Sensor: conductor tracks Process: ESCA – sputtering and measure signal for Cr

ESCA spectrum of SiO2 - layer

Fluorine !

Sensor: conductor tracks Process: ESCA – sputtering and measure signal for Cr

Transfer of specimen to Auger Microscope

NiCr-conductor track

Auger analysis:

SEM image

Auger-spectrum of NiCr-conductor track

Good sensor

Auger-spectrum of NiCr-conductor track

Defective sensor

Sulphur

Phosphorus

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

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

Auger depth profile new coil

Auger depth profile coloured coil

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

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

Application of ADLC-coatings

Coating: 60 nm ADLC on Si-substrate

Adhesion of ADLC

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)

SAM: SEM-image

α-phase: dark β-phase: white

SAM: O-map

SAM: Ti-map

α-phase: Ti-rich

SAM: Al-map

α-phase: Al-rich

SAM: Nb-map

Nb2O5 distribution on the surface of the TiAlNb-implant (above β-phase)

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

problem solving and failure analysis by auger and esca m ... · pdf filematerials science...

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