x-ray scatterometry

**X-ray Scatterometry** is a **metrology technique that uses X-ray diffraction/scattering to measure the dimensions of nanoscale semiconductor structures** — X-rays' short wavelength (0.1-10 nm) provides sensitivity to sub-nanometer structural details that optical wavelengths cannot resolve. **X-ray Scatterometry Methods** - **CDSAXS**: Critical Dimension Small-Angle X-ray Scattering — measures CD, pitch, height, and profile from small-angle diffraction. - **XRR**: X-ray Reflectometry — measures film thickness and density from interference fringes. - **GISAXS**: Grazing Incidence Small-Angle X-ray Scattering — surface and near-surface nanostructure characterization. - **Sources**: Lab sources (rotating anode, liquid metal jet) or synchrotron radiation. **Why It Matters** - **No Model Ambiguity**: X-ray results are less model-dependent than optical OCD — more robust parameter extraction. - **Sub-Nanometer Sensitivity**: X-ray wavelengths probe atomic-scale features — essential for <3nm nodes. - **Buried Structures**: X-rays penetrate multiple layers — measure buried structures that optical methods cannot see. **X-ray Scatterometry** is **seeing with atomic resolution** — using X-ray scattering for model-robust measurement of the smallest semiconductor features.