Overview
EN ISO 23131:2022 - Ellipsometry: Principles (ISO 23131:2021) defines a standardized method for using ellipsometry to determine optical and dielectric constants and layer thicknesses in the UV‑VIS‑NIR spectral range. Endorsed by CEN and adopted as a European standard, it is intended for stand‑alone measuring systems used in at‑line production control, quality assurance, and material development by accredited test laboratories. The standard also requires that the presentation of measurement uncertainty follow ISO/IEC Guide 98‑3 (GUM).
Key Topics and Requirements
- Scope and applicability: Covers spectroscopic ellipsometry for thin films and bulk materials within the UV‑VIS‑NIR range; applicable to standalone instruments used in industrial and laboratory environments.
- Raw data and measurands: Emphasizes storing ellipsometric transfer quantities Ψ (Psi) and Δ (Delta) as the primary raw data for analysis and reporting.
- Measurement arrangement: Describes optical/metrological setup (polarizer–compensator–sample–analyzer, P‑C‑S‑A) and boundary conditions for sample and instrument.
- Model‑based analysis: Reinforces that ellipsometry is an indirect, model‑correlated technique - optical constants and layer thicknesses are derived by parameterized fitting of Ψ and Δ.
- Performance and verification: Includes procedures for device adjustment and calibration checks (e.g., straight line measurement, angle checks, reference samples) and documentation of experimental boundary conditions.
- Reporting and uncertainty: Requires presentation of measurement uncertainty in accordance with ISO/IEC Guide 98‑3 and storage/reporting compatible with accreditation expectations (e.g., ISO/IEC 17025).
- Limitations and sensitivity: Notes high precision of Ψ and Δ and potential layer‑thickness sensitivity (~0.1 nm under ideal conditions), while highlighting accuracy dependence on model quality and sample homogeneity/isotropy.
Applications and Users
Who benefits from EN ISO 23131:2022:
- Accredited test laboratories performing standardized ellipsometric analyses.
- Production and quality‑assurance teams in semiconductor, coatings, optics, and thin‑film industries for at‑line process control.
- Material scientists and R&D groups conducting optical property or layer‑structure characterization.
- Instrument manufacturers and service providers implementing calibration, verification, and software reporting features.
Practical uses:
- Determining refractive index, extinction coefficient, dielectric function.
- Measuring single and multi‑layer thicknesses (transparent, semi‑transparent, effective media).
- Establishing traceable, auditable measurement workflows for product release and specification compliance.
Related Standards
- ISO 23131:2021 (original international text) - adopted as EN ISO 23131:2022.
- ISO/IEC Guide 98‑3 (GUM) - uncertainty of measurement.
- References to accreditation practice such as ISO/IEC 17025 are relevant for reporting and laboratory competence.
Keywords: EN ISO 23131:2022, ellipsometry, UV‑VIS‑NIR, optical constants, dielectric constants, layer thickness, at-line production control, quality assurance, measurement uncertainty.