Spreading Resistance Analysis : SRA

Principle

Spreading Resistance Analysis (SRA) is a powerful method to evaluate depth profiles of carrier concentrations in semiconductors. Upon the graded slope of sample, two probes are swept along the slope to measure the spreading resistance in depth. Then, the resistivity profiles would be converted to carrier concentration profiles using a calibration coefficient. Being combined with atomic concentration profiles obtained by SIMS, SRA results could provide activated impurity ratios of dopant in the sample.

Estimation ofcarrier concentration
ρ : Resistivity
μ : Carrier mobility
q : Elementary charge
N : Carrier concentration
  • Sample size: 50×100 um squares – several mm squares
  • Carrier concentration range: 1×1013 – 1×1020 cm-3
  • Depth range: 100 nm – mm
  • We can provide wide range carrier profiles, such as ultra shallow junctions or deeper junctions, choosing an appropriate gradient angle.
Depth profile of carrier concentration