spectroscopic ellipsometry mapping

**Spectroscopic Ellipsometry (SE) Mapping** is the **application of spectroscopic ellipsometry at multiple positions across a wafer** — creating maps of film thickness, optical constants, and composition that reveal spatial uniformity of thin-film deposition processes. **How Does SE Mapping Work?** - **Multi-Point**: Measure ellipsometric spectra ($Psi(lambda), Delta(lambda)$) at a grid of points (e.g., 49 or 121 sites). - **Model Fitting**: Fit an optical model at each point to extract thickness, refractive index, and composition. - **Contour Maps**: Generate spatial maps of thickness, $n$, $k$, bandgap, and other parameters. - **Speed**: Modern automated tools measure a full wafer in minutes. **Why It Matters** - **Deposition Uniformity**: Maps CVD, PVD, and ALD film thickness uniformity across 300 mm wafers. - **Multi-Layer**: Measures multiple layers simultaneously (e.g., SiO$_2$/SiN/poly-Si stacks). - **Non-Destructive**: Completely non-contact, non-destructive — suitable for production monitoring. **SE Mapping** is **the thin-film uniformity scanner** — measuring thickness and optical properties across entire wafers for process control.