Thickness and transmission of thin films on foils

In cooperation with the Fraunhofer Institute for Assembly and Packaging Technologies for Microsystems, a thin film measurement device for determining the thickness of polycarbonate films on acrylic foils was developed.

Here the challenge was to be able to analyze the highly structured sample given the small difference of the layers’ refractive index in the visible spectral range. In order to scan the layer thickness over an area of 200 x 200 mm, the foil must lay flat on the sample holder. A specially designed sample holder with a vacuum sucking mechanism was used to avoid wrinkling of the foil sample. In addition to the thickness measurement, the transmission characteristics of the foil could be determined.

Design features of the thin film measurement device:
- 100 µm spot size for measurement within the sample structures
- integrated camera-system for positioning the measurement spot or identifying the sample structure
- integrated, pulsed xenon light source for broadband sample illumination
- sample stage with sinter overlay for foil suction
- separated scan system: x-direction by translational stage, y-direction by measurement head translation

- allowing for simultaneous transmission measurement