ellipsization

Ellipsometry is an optical technique used to study the optical properties of thin films and surfaces. It is a non-destructive method that measures the change in polarization of light as it reflects from or transmits through a sample. The technique is called ellipsometry because the polarization state of light generally changes from linear to elliptical upon reflection or transmission from a sample.

The fundamental principle of ellipsometry is to measure two parameters, psi (Ψ) and delta (Δ), which describe the change in the polarization state of light. These parameters are related to the complex refractive index and thickness of the thin film. By analyzing these measured values, one can determine these optical properties.

The instrumentation for ellipsometry typically consists of a light source, a polarizer, a compensator (optional), a sample stage, and a detector. Light from the source is polarized, interacts with the sample, and the changes in its polarization are analyzed by the detector. Various configurations exist, including rotating analyzer ellipsometry, rotating retarder ellipsometry, and phase modulation ellipsometry, each offering different advantages in terms of speed and accuracy.

Ellipsometry is widely used in fields such as semiconductor manufacturing, materials science, optics, and biology. It is employed for characterizing dielectric layers, metallic films, semiconductors, organic layers, and more. Applications include monitoring film growth, determining film thickness, measuring refractive indices, and detecting surface contamination. The sensitivity of ellipsometry to very thin films, even down to a single atomic layer, makes it a powerful tool for nanoscale characterization.