ISO 20341:2003

Overview

ISO 20341:2003 specifies a standardized method for estimating depth resolution parameters in Secondary‑Ion Mass Spectrometry (SIMS) depth profiling using multiple delta‑layer reference materials. The standard defines procedures to quantify the three component parameters that describe a SIMS depth profile: the leading‑edge decay length, the trailing‑edge decay length, and the Gaussian broadening. It is intended for situations where the near‑surface region is in a steady state under primary‑ion bombardment and therefore does not apply to non‑steady‑state delta layers.

Key topics and requirements

• Depth resolution parameters: Procedures for estimating
  • Leading‑edge decay length (λL)
  • Trailing‑edge decay length (λT)
  • Gaussian broadening (σ)
• Reference materials: Requirements for multiple delta‑layer samples:
  • Matrix must remain constant during sputtering (constant matrix signals).
  • Flat, parallel delta layers and surface to avoid profile distortion.
  • Delta‑layer thickness much less than primary‑ion projected range.
  • Layer spacing such that valley intensity < 1% of peak.
  • Characterisation of layer thickness, position and interface roughness by cross‑section TEM, grazing incidence X‑ray reflectivity, MEIS, or equivalent.
• Measurement procedures:
  • Instrument setup per manufacturer/local procedures (ion species, energy, current, polarity, scan uniformity).
  • Acquire profiles with >10 data points in the top 20% of peak intensity and record down to <1% of maximum.
  • Subtract constant background if >1% of peak before fitting; convert sputter time to depth.
  • Full estimation: use non‑linear curve fitting of a convolution model (see Equation (4) in the standard) to extract λL, λT and σ.
  • Simpler options (Annex A): one‑ or two‑parameter estimates using semi‑log slopes of intensity vs. depth (require linear span of at least a factor 10 in intensity).
• Reporting: Test report must identify specimen, instrument, analysis conditions, reference material, method used (Equation (4) or Annex A), measured parameters for each layer, depths, and any deviations or unusual features.

Applications and users

ISO 20341:2003 is directly applicable to laboratories and professionals performing SIMS depth profiling, including:

• Surface analysis and materials characterization labs
• Semiconductor and thin‑film process development teams
• Quality control laboratories using delta‑layer reference materials
• Instrument manufacturers and calibration services
• Academic researchers studying interfaces, diffusion, ion‑beam mixing or sputter‑induced effects

This standard helps ensure reproducible, comparable measurements of SIMS depth resolution for device interfaces, dopant profiling, multilayer films and other nanoscale depth analyses.

Related standards and references

• Normative reference: ISO 18115:2001 (Surface chemical analysis - Vocabulary)
• Supporting literature cited in the standard: Dowsett et al. (1994) and Moon et al. (2000) for derivation and example fits.