mueller matrix scatterometry

**Mueller Matrix Scatterometry** is an **advanced form of optical scatterometry that measures the full 4×4 Mueller matrix of a sample** — capturing the complete polarization response (diattenuation, retardance, and depolarization) rather than just the ellipsometric parameters ($Psi, Delta$), providing richer information about structural asymmetries and complex profiles. **Mueller Matrix Advantages** - **16 Elements**: The 4×4 Mueller matrix has 16 elements — far more information than the 2 parameters ($Psi, Delta$) from standard ellipsometry. - **Symmetry Breaking**: Off-diagonal Mueller matrix elements are sensitive to structural asymmetries (line tilt, non-uniform profiles). - **Depolarization**: Depolarization from surface roughness, CD variation, or overlay errors can be measured directly. - **Cross-Polarization**: Cross-polarized elements reveal features invisible to co-polarized measurements. **Why It Matters** - **Asymmetric Profiles**: Detects line tilt, footing, and asymmetric sidewalls that standard ellipsometry misses. - **Overlay**: Mueller matrix elements are sensitive to overlay errors — enables advanced overlay metrology. - **Process Control**: Additional Mueller matrix elements provide more process-relevant information per measurement. **Mueller Matrix Scatterometry** is **the complete polarization portrait** — capturing every aspect of light-structure interaction for high-information metrology.