ISO 23131-3:2026

Overview

ISO 23131-3:2026 – Ellipsometry - Part 3: Transparent Single Layer Model is an international standard published by the International Organization for Standardization (ISO). It defines a method, using ellipsometric measurements and analysis, to determine the layer thickness (d) and optical properties-specifically the refractive index (n) or dielectric constant (ε₁)-of transparent single layers where the extinction coefficient (k) is zero within a given spectral region. This document is crucial for laboratories and industries where the precise measurement of transparent thin films is required, supporting high-quality material characterization and process control.

Key Topics

• Ellipsometric Principles: Utilizes phase-sensitive reflection of polarized light to derive information about thin film structure and properties. The core measurements are the ellipsometric transfer quantities Ψ (amplitude information) and Δ (phase information).
• Transparent Single Layer Model: Assumes the layer has negligible absorption and scattering (k = 0), homogeneity, isotropy, well-defined interfaces, and planarity with respect to the measurement system.
• Model Assumptions: Includes guidelines related to material and layer stability, absence of additional interfacial or surface layers, negligible roughness and inhomogeneity, and precise angle of incidence.
• Measurement Uncertainty: Details the evaluation of measurement uncertainty for layer thickness and optical constants, emphasizing the importance of model accuracy, system calibration, and the fit quality between measured and simulated ellipsometric data.
• Validation and Fit Quality: Describes fit procedures for determining layer thickness and refractive index, validation of applied constants, and interpretation of fit quality using statistical analysis.

Applications

ISO 23131-3:2026 is widely relevant across industries and research fields where transparent thin film layers are critical, including:

• Semiconductor Manufacturing: Non-invasive measurement of ultra-thin dielectric layers for quality assurance and process optimization.
• Optical Coatings: Characterization of anti-reflection and protective coatings used in precision optics and photonics.
• Material Science: Research and development of new transparent materials where accurate knowledge of layer thickness and refractive index is essential.
• Surface and Interface Analysis: Measurement and validation of transparent reference layers in calibration routines and the development of certified reference materials.
• Quality Control: Routine verification of layer properties in industrial production environments, ensuring compliance with strict tolerance requirements.

Ellipsometry, as standardized in this document, is recognized for its high sensitivity and accuracy-detecting sub-nanometer variations in film thickness and subtle changes in optical constants.

Related Standards

• ISO 23131 – Ellipsometry - Principles: Provides the foundational concepts and methodologies for ellipsometric measurements.
• ISO 23131-2:2026 – Ellipsometry - Part 2: Bulk Material Model: Covers measurement and analysis for bulk materials using ellipsometry.
• ISO/IEC Guide 98-3 – Uncertainty of Measurement (GUM:1995): Outlines general requirements and best practices for expressing measurement uncertainty applicable across all parts of ISO 23131.

Implementing ISO 23131-3:2026 ensures robust, reproducible results when determining transparent single layer thickness and optical properties, supporting advanced quality control and research in materials characterization, semiconductor processing, and thin film technology.

Keywords: ISO 23131-3:2026, ellipsometry standard, transparent single layer model, layer thickness measurement, thin film refractive index, optical constants, dielectric constants, measurement uncertainty, material characterization, thin film metrology.