scanning microwave microscopy

**SMM** (Scanning Microwave Microscopy) is a **technique that combines an AFM with a vector network analyzer (VNA)** — measuring the complex reflection coefficient ($S_{11}$) at the AFM tip-sample junction to quantitatively map capacitance, dopant concentration, and dielectric properties at the nanoscale. **How Does SMM Work?** - **Setup**: AFM tip + VNA operating at 1-20 GHz. - **$S_{11}$ Measurement**: Measure the complex reflection coefficient at each scan point. - **Calibration**: Use calibration standards to convert $S_{11}$ to quantitative capacitance. - **Doping Profile**: Capacitance is related to the local depletion region -> doping concentration. **Why It Matters** - **Quantitative**: Unlike MIM (qualitative), SMM with VNA calibration provides quantitative doping and capacitance values. - **Non-Destructive**: No sample preparation beyond cross-sectioning (for depth profiling). - **2D Dopant Profiling**: Can map 2D dopant distributions in FinFET cross-sections and advanced devices. **SMM** is **quantitative microwave nano-imaging** — using calibrated VNA measurements to extract real capacitance and dopant values at the nanoscale.