stress-strain calibration

**Stress-Strain Calibration** in semiconductor metrology is the **establishment of quantitative relationships between measurable spectroscopic shifts and mechanical stress/strain** — enabling techniques like Raman spectroscopy and XRD to serve as precise, non-destructive stress measurement tools. **Key Calibration Relationships** - **Raman (Si)**: $Deltaomega = -1.8$ cm$^{-1}$/GPa for biaxial stress. $Deltaomega = -2.3$ cm$^{-1}$/GPa for uniaxial <110> stress. - **XRD (Bragg)**: $epsilon = -cot heta cdot Delta heta$ — lattice strain from diffraction peak shift. - **PL (Band Gap)**: Deformation potentials relate band gap shift to strain components. - **Calibration Samples**: Externally strained samples with known stress (four-point bending, biaxial pressure). **Why It Matters** - **Quantitative Stress**: Converts spectroscopic observables into engineering stress values (GPa, MPa). - **Process Integration**: Calibrated stress measurements guide strained-Si, SiGe, and stress liner engineering. - **Multi-Technique**: Cross-calibration between Raman, XRD, and wafer curvature ensures consistency. **Stress-Strain Calibration** is **the Rosetta Stone for spectroscopic stress** — translating peak shifts into quantitative engineering stress values.