Semiconductor Failure Analysis (FA) is the systematic process of identifying the physical root cause of device or circuit failure — using a hierarchy of destructive and non-destructive techniques to trace electrical failure to a specific defect at a specific location.
FA Flow
1. Electrical Characterization: Reproduce and characterize the failure mode (opens, shorts, parametric drift).
2. Non-Destructive Analysis: Package-level imaging before any decapsulation.
3. Decapsulation: Chemically remove package to expose die.
4. Photon Emission / OBIRCH: Locate hot spots or current anomalies on live die.
5. Physical Localization: FIB cross-section to reveal defect.
6. Defect Imaging: TEM, SEM for atomic-scale defect imaging.
7. Composition Analysis: EDX, SIMS, Auger to identify chemical root cause.
Key FA Techniques
SEM (Scanning Electron Microscopy):
- Nanometer-resolution surface imaging.
- Backscatter mode: Composition contrast.
- Secondary electron mode: Topography.
FIB (Focused Ion Beam):
- Gallium ion beam mills material with nanometer precision.
- Creates site-specific cross-sections through exact defect location.
- FIB-SEM: Combined tool — mill and image simultaneously.
- TEM sample preparation: FIB lifts out 100nm-thick lamella for TEM.
TEM (Transmission Electron Microscopy):
- Sub-angstrom resolution — images individual atoms.
- HRTEM: Crystal structure, defects, interfaces.
- STEM-EDX: Elemental mapping at atomic scale.
- Essential for sub-10nm defect characterization.
Photon Emission Microscopy (EMMI):
- Captures photons emitted from forward-biased junctions or hot carriers.
- Localizes gate oxide leakage, latch-up, ESD damage under live bias.
OBIRCH (Optical Beam Induced Resistance Change):
- Laser beam heats die; resistance change maps current flow.
- Localizes resistive shorts and buried metal defects.
Chemical Analysis
- EDX/EDS: Elemental analysis within SEM/TEM.
- Auger: Surface-sensitive elemental analysis.
- SIMS: Trace dopant/impurity profiling (ppm sensitivity).
Semiconductor failure analysis is the diagnostic backbone of quality and reliability engineering — rigorous FA drives yield improvement, process corrections, and design rule updates that prevent systematic failures from reaching customers.