Scanning Capacitance Microscopy (SCM) is a nanoscale metrology technique that maps carrier concentration in semiconductors by measuring local capacitance variations with an AFM-based probe.

What Is SCM?

• Principle: Metal-coated AFM tip forms MOS capacitor with sample
• Resolution: 10-20nm lateral, sub-nm depth sensitivity
• Output: dC/dV signal proportional to carrier concentration
• Applications: 2D dopant profiling, junction delineation, failure analysis

Why SCM Matters

As transistors shrink, understanding nanoscale dopant distribution becomes critical. SCM provides non-destructive 2D carrier imaging impossible with bulk techniques.

<svg viewBox="0 0 468 340" xmlns="http://www.w3.org/2000/svg" style="max-width:100%;height:auto" role="img"><rect x="0" y="0" width="468" height="340" rx="12" fill="#0d1117"/><g font-family="ui-monospace,SFMono-Regular,Menlo,Consolas,&quot;Liberation Mono&quot;,monospace" font-size="14"><text xml:space="preserve" x="20" y="31.7"><tspan fill="#c9d1d9">SCM Operating Principle:</tspan></text><text xml:space="preserve" x="20" y="50.7"><tspan fill="#c9d1d9">       AFM Probe (metal-coated tip)</tspan></text><text xml:space="preserve" x="20" y="69.7"><tspan fill="#c9d1d9">              </tspan><tspan fill="#6e7681">│</tspan></text><text xml:space="preserve" x="20" y="88.7"><tspan fill="#c9d1d9">              ●</tspan><tspan fill="#6e7681">───</tspan><tspan fill="#c9d1d9"> AC bias applied</tspan></text><text xml:space="preserve" x="20" y="107.7"><tspan fill="#c9d1d9">              </tspan><tspan fill="#6e7681">│</tspan></text><text xml:space="preserve" x="20" y="126.7"><tspan fill="#c9d1d9">    </tspan><tspan fill="#6e7681">┌─────────▼─────────┐</tspan></text><text xml:space="preserve" x="20" y="145.7"><tspan fill="#c9d1d9">    </tspan><tspan fill="#6e7681">│</tspan><tspan fill="#c9d1d9">     Oxide         </tspan><tspan fill="#6e7681">│</tspan></text><text xml:space="preserve" x="20" y="164.7"><tspan fill="#c9d1d9">    </tspan><tspan fill="#6e7681">├───────────────────┤</tspan></text><text xml:space="preserve" x="20" y="183.7"><tspan fill="#c9d1d9">    </tspan><tspan fill="#6e7681">│</tspan><tspan fill="#c9d1d9">  Depletion region </tspan><tspan fill="#6e7681">│←</tspan><tspan fill="#c9d1d9"> Width varies with doping</tspan></text><text xml:space="preserve" x="20" y="202.7"><tspan fill="#c9d1d9">    </tspan><tspan fill="#6e7681">│</tspan><tspan fill="#c9d1d9">    (varies)       </tspan><tspan fill="#6e7681">│</tspan></text><text xml:space="preserve" x="20" y="221.7"><tspan fill="#c9d1d9">    </tspan><tspan fill="#6e7681">├───────────────────┤</tspan></text><text xml:space="preserve" x="20" y="240.7"><tspan fill="#c9d1d9">    </tspan><tspan fill="#6e7681">│</tspan><tspan fill="#c9d1d9">    Substrate      </tspan><tspan fill="#6e7681">│</tspan></text><text xml:space="preserve" x="20" y="259.7"><tspan fill="#c9d1d9">    </tspan><tspan fill="#6e7681">└───────────────────┘</tspan></text><text xml:space="preserve" x="20" y="278.7"><tspan fill="#c9d1d9">    </tspan></text><text xml:space="preserve" x="20" y="297.7"><tspan fill="#c9d1d9">High doping </tspan><tspan fill="#6e7681">→</tspan><tspan fill="#c9d1d9"> small depletion </tspan><tspan fill="#6e7681">→</tspan><tspan fill="#c9d1d9"> high capacitance</tspan></text><text xml:space="preserve" x="20" y="316.7"><tspan fill="#c9d1d9">Low doping  </tspan><tspan fill="#6e7681">→</tspan><tspan fill="#c9d1d9"> large depletion </tspan><tspan fill="#6e7681">→</tspan><tspan fill="#c9d1d9"> low capacitance</tspan></text></g></svg>

SCM vs. Other Profiling: