Overview
EN ISO 23216:2022 (identical to ISO 23216:2021) specifies a standardized, non‑destructive method - spectroscopic ellipsometry - for determining the optical properties of amorphous carbon films. The standard defines how to measure and report the key optical constants, refractive index (n) and extinction coefficient (k), and provides an optical classification scheme in the n‑k plane that can act as a process fingerprint for different amorphous carbon types.
Key topics and requirements
- Scope: Applies to amorphous carbon films deposited by ionized evaporation, sputtering, arc deposition, plasma‑assisted CVD, hot filament techniques and similar methods. Excludes films modified with metals or silicon, films with composition gradients through thickness, paints and varnishes.
- Specimen: Films should be homogeneous; recommended substrate is a mirror‑finished Si wafer. Film thickness range: 0.02 µm to 5 µm.
- Apparatus: Light source (halogen lamp and blue LED), detector and spectrometer covering 450–950 nm, photomultiplier/CCD/PDA options, ellipsometry software, goniometer and sample stage.
- Test conditions (recommended): wavelength range 450–950 nm, angle of incidence ~70°, spot size >500 µm × 500 µm, measurement duration ~5 s. Use n and k values at or close to 550 nm for classification.
- Procedure: Specimen cleaning and storage, sample positioning, data acquisition and optical modelling to extract n, k and thickness. Test conditions and modelling parameters must be recorded in the test report.
- Classification: Provides an n‑k plane classification method (normative annex) to distinguish graphite‑like, polymer‑like, glass‑like and diamond‑like amorphous carbon types based on measured optical constants.
Applications and practical value
- Quality control & process monitoring: Fast, repeatable, non‑destructive measurement for production lines and R&D.
- Coating identification: Optical fingerprinting on Si wafers helps identify coating type and verify deposition processes.
- Product development: Guides selection of amorphous carbon types for wear‑resistant, biomedical or optical applications by correlating optical constants with material structure.
- Industrial sectors: Automotive, tooling, biomedical devices, optics and semiconductor industries that use hard, protective or functional carbon coatings.
Who should use this standard
- Coating manufacturers, materials scientists, QC laboratories, surface engineering teams, and contract testing labs implementing or validating spectroscopic ellipsometry for amorphous carbon films.
Related standards and context
- EN ISO 23216:2022 is the CEN adoption of ISO 23216:2021, prepared by ISO/TC 107 (Metallic and other inorganic coatings). Users should reference national implementations and report conformity per local standards body guidance.
Keywords: EN ISO 23216:2022, ISO 23216:2021, spectroscopic ellipsometry, amorphous carbon films, refractive index n, extinction coefficient k, n‑k plane, optical properties, Si wafer, film thickness, quality control.
