Scm

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.

SCM Operating Principle: AFM Probe (metal-coated tip) │ ●─── AC bias applied │ ┌─────────▼─────────┐ │ Oxide │ ├───────────────────┤ │ Depletion region │← Width varies with doping │ (varies) │ ├───────────────────┤ │ Substrate │ └───────────────────┘ High doping → small depletion → high capacitanceLow doping → large depletion → low capacitance

SCM vs. Other Profiling:
| Method | Resolution | Quantitative | Sample Prep |
|--------|------------|--------------|-------------|
| SCM | 10-20nm | Semi-quant | Cross-section |
| SSRM | 1-5nm | Yes | Cross-section |
| SIMS | 1nm depth | Yes | Destructive |

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