Method · ELLIPS
Spectroscopic ellipsometry in the Netherlands, Belgium and Germany
Film thickness and optical constants inferred from a model fitted to changes in light polarisation. What it answers, what it cannot establish on its own, what a laboratory will ask, and how many Dutch, Belgian and German facilities publish it.
What it answers
- How thick is a transparent or semi-transparent film, and what are its refractive index and extinction coefficient?
- How uniform is the thickness across a wafer or substrate?
- Did a process step change the optical constants of a layer?
What it cannot establish alone
- Give a unique thickness and refractive index for every unknown stack; correlated parameters need constraints or independent measurements.
- Determine chemical identity directly from a fitted optical model.
- Resolve every layer beneath an optically opaque film, or characterise rough and strongly scattering surfaces with a simple flat-layer model.
- Describe coating uniformity from a single spot; this requires measurements at several positions.
Before you contact a laboratory
What a laboratory will ask.
A laboratory can say whether it can help only when these are known. Unknowns are fine; say so.
- Substrate, layer order, expected materials and approximate thicknesses.
- Known optical properties, transparency or absorption range, and any independent thickness measurement.
- Sample size, flatness, roughness and whether the back surface can contribute reflections.
- Required wavelengths and whether a single position or a map is needed.
A question a laboratory can answer
We grow 100–150 nm silicon oxide films on silicon and need thickness and refractive index at 633 nm, measured at nine points across a 100 mm wafer.
Potential Dutch, Belgian and German facilities
17 facilities publish spectroscopic ellipsometry capability in Delft, Eindhoven, Aachen, Amsterdam, Berlin, Ghent, Greifswald, Groningen, Ilmenau, Liège, Louvain-la-Neuve, Namur, Noordwijk and Rüsselsheim am Main.
Leads are based on published capabilities; current suitability and availability must be confirmed with the laboratory.
Describe your sample and question. The first answer is free and needs no account; laboratory names are shown in a free workspace.
Problems where it helps
- Thin-film thickness: choosing a measurementEllipsometry, X-ray reflectivity or a cross-section? How film type, thickness range and stack decide the measurement, and what to prepare.