The inverted optical reflection microscope is a versatile technique to image samples with a resolution in the order of µm’s. The easy use and fast handling speed makes it ideal for quality control. The system is therefore frequently used during the preparation process of specimens (localization of defects, quality check of cross-sections and e-beam patterns...). Another typical application is the determination of dimensions (layer thicknesses, grain size…) in the micrometer range.
In order to improve the contrast or highlight certain structures several illumination/detection techniques can be used:
- Bright field: contrast due to absorbance of light.
- Dark field: contrast from light scattered by the sample.
- Polarization contrast: contrast comes from rotation of polarized light through the sample.
- Phase contrast: sample contrast comes from differences in refractive index
- Differential interference contrast: Differences in optical density will show up as differences in relief.