RC2

The J.A. Woollam RC2 is a spectroscopic ellipsometer used to measure the thicknesses and refractive indices of thin films.^[1]

It is an optical measurement tool for thin-film metrology at CMi.^[1]

Spectroscopic ellipsometry uses polarized light after interaction with a surface to determine refractive indices and thicknesses of thin films. In this method, linearly polarized light is directed at a material at a certain angle of incidence, separated into parallel and perpendicular components, and the reflected light becomes elliptically polarized.^[1]

The instrument estimates thickness from measurements of the ratio Rp/Rs, the reflection coefficients of the s- and p-components, with Ψ and Δ related to film thickness and refractive index. It does not directly measure refractive index or thickness; an algorithm is used to resolve those values from Ψ and Δ.^[1]

The system includes a xenon arc lamp light source, a wavelength range from 210 nm to 2500 nm, an X-Y-Z motorized stage, motorized Z and autofocus, and an automatic tilt alignment routine.^[1]

The system accepts wafers up to 200 mm and chips with a surface for measurement larger than the cross section of the incident beam.^[1]

It is used to study thin films in optical measurement workflows, including measurements on transparent or non-transparent films.^[1]

The instrument is used for dielectric and semiconductor films such as silicon dioxide, silicon nitride, polysilicon, and amorphous silicon.^[1]

It is also used for metallic films, with the note that the film generally needs to be very thin, and for organic layers such as carbon and photosensitive resists.^[1]