VASE Ellipsometer
Manufacturer: J. A. Woollam
The Variable Angle Spectroscopic Ellipsometer (VASE®) is a totally automated, thin film characterization system that uses high-precision angle, and a wide spectral range (240 to 1700 nm). It has a vertical sample mounting, automated sample mapping, and focused spot size. Some of the key benefits are: highest precision and accuracy of any spectroscopic ellipsometer, totally automated angle of incidence, nondestructive materials analysis, easily characterize all types of materials: semiconductors, dielectrics, polymers, metals, multilayers, and more.
The VASE has an optional Auto Retarder™, which is a patented measurement technique that provides the most accurate data. Most types of ellipsometers have data regions where they are less sensitive. The Auto Retarder overcomes this for any sample. The Auto Retarder increases the flexibility of the VASE®. It allows measurement of delta from 0° to 360° with no problem areas. This is very beneficial for samples such as transparent films on transparent substrates, where it is difficult to find angles of incidence with delta away from 0° or 180°. The Auto Retarder also allows more complex measurements. It has been successfully used with anisotropic samples and to measure the sample depolarization. Complicated structures require the most accurate data, which is what you get with the Auto Retarder.
Upon analysis, the surface of the test sample, the reflected light, with its polarization altered by the properties of the sample, passes through the analyzer and an optical interference filter.
Interpretation of the data yields the optical constants of the material or, if the material surface is film-covered, the thickness and optical constants of the film.
The system and software were upgraded along with new film libraries in 2023.