Ellipsometers are high-precision opto-electronic measuring devices that are used to determine the optical properties (such as refractive index and extinction coefficient) of materials and to measure the thickness of ultra-thin layers. The basis is the change in the polarisation state of light when it is reflected on a surface. Material parameters or the layer thickness can be derived from this change. Modern systems combine classic ellipsometry with imaging technologies, allowing not only averaged values but also lateral structures and spatially resolved analyses to be recorded.

The Nanofilm EP3 is an auto-zeroing imaging ellipsometer that has been specially developed for the precise characterisation of thin films. The optical system is based on an internal solid-state laser with a wavelength of 532 nm and a maximum output power of 50 mW. The ellipsometer thus achieves a resolution of 0.001° for delta and psi with an absolute accuracy of 0.01°. The relative thickness can be determined with an accuracy of up to 0.001 nm, while the absolute thickness accuracy is less than 0.1 nm.

Highly sensitive CCD cameras with resolutions of 640 × 480, 768 × 572 or up to 1380 × 1024 pixels are used for imaging. Samples are captured using motorised goniometers with an incidence angle range of 40° to 90° and an angular resolution of 0.001°. Sample positioning can be performed both manually and automatically. The device has a travel range of up to 100 mm in the X/Y direction and more than 10 mm in the Z direction.

The EP3View software is available for using the ellipsometer, which is supported by additional tools such as AnalysR for evaluation. It is operated via a graphical user interface with functions for imaging, mapping, angular and wavelength spectra as well as modelling the measurement data.

Its combination of high-resolution ellipsometry, spatially resolved imaging and spectral flexibility makes it a versatile tool for materials research, semiconductor technology and thin-film analysis.