ellipsometrit

Ellipsometry is an optical technique used to study the optical properties of thin films and surfaces. It measures the change in polarization of light upon reflection from or transmission through a sample. Specifically, it analyzes the ratio of the Fresnel reflection coefficients for light polarized parallel and perpendicular to the plane of incidence. This ratio is commonly expressed as psi (Ψ) and delta (Δ), which are the two primary parameters measured by an ellipsometer.

The technique is highly sensitive to very thin layers, down to the sub-nanometer scale. By analyzing the measured Ψ and Δ values, one can determine various properties of the sample, including film thickness, refractive index, extinction coefficient, and surface roughness. The interpretation of ellipsometric data typically involves fitting the experimental results to optical models that describe the sample's structure.

Ellipsometry finds applications in a wide range of fields. In semiconductor manufacturing, it is crucial for in-situ monitoring of thin film deposition and etching processes. It is also used in materials science for characterizing dielectric layers, metallic films, and organic coatings. In research, it plays a role in studying optical constants of novel materials, surface modifications, and the optical response of complex nanostructures. The technique can be performed in various configurations, including spectroscopic ellipsometry (measuring over a range of wavelengths) and rotating analyzer ellipsometry (rapid data acquisition).