SSRM (Scanning Spreading Resistance Microscopy) is a contact-mode AFM technique that measures local spreading resistance by pressing a hard conductive diamond tip into the sample — providing two-dimensional dopant profiles with sub-nanometer spatial resolution and six decades of dynamic range.

How Does SSRM Work?

• Tip: Hard, conductive doped diamond tip pressed into the sample with ~μN force.
• Measurement: Apply DC bias and measure the current -> spreading resistance $R = ho / (4a)$ where $a$ is the contact radius.
• Cross-Section: Map 2D cross-sections of devices by scanning across polished/cleaved surfaces.
• Calibration: Convert resistance to carrier concentration using staircase calibration samples.

Why It Matters

• Best Resolution: Sub-nanometer resolution for 2D dopant profiling — the highest-resolution electrical technique.
• Dynamic Range: 6+ decades (from $10^{14}$ to $10^{20}$ cm$^{-3}$) in a single measurement.
• FinFET Characterization: Essential for 3D dopant profiling of FinFETs, GAA-FETs, and nanoscale devices.

SSRM is the sharpest electrical probe — pushing a diamond nanotip into the sample to map dopant concentrations with unmatched resolution.