Problem
Thin-film thickness: choosing a measurement
Which technique fits depends on the film: its thickness range, whether it is transparent, how many layers the stack has, how smooth it is and whether the sample may be cut. Optical and X-ray methods are non-destructive but rely on a model; a cross-section shows the layers directly and consumes the sample.
What usually has to be established
- The nominal thickness range and the number of layers
- Whether the film is transparent or absorbing, and on which substrate
- Whether thickness alone is enough, or density, roughness or optical constants are needed as well
Measurements
Where an investigation often starts.
A typical sequence, not a prescription. The Field Agent adapts it to your sample, what you observed and the decision the result must support.
Spectroscopic ellipsometryTransparent films
Fast and non-destructive for transparent and semi-transparent layers. It also gives the refractive index and can map uniformity across a wafer, but it needs an optical model.
X-ray reflectivityVery thin or dense films
Gives thickness, density and interface roughness from about a nanometre to a few hundred nanometres on flat, smooth samples, including metal layers.
Transmission electron microscopyWhen a direct image is needed
A cross-section shows every layer and interface at nanometre scale. The specimen is thinned and consumed, and it covers a very small area.
What to have ready
- Substrate, layer materials and the nominal stack
- Expected thickness of each layer
- Sample size and flatness
- How many samples, and whether one point or a map across the sample is needed
Potential Dutch facilities
20 facilities publish at least one of these measurements in Delft, Eindhoven, Amsterdam, Enschede, Groningen, Leiden, Maastricht, Nijmegen, Noordwijk, Petten, Utrecht and Wageningen.
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.