Experiment Measurement of indices and thickness by Ellipsometry

Ellipsometry is a non-destructive optical measurement technique widely used in the industrial field (thickness measurements, optical properties, ...) This lab session provides a didactic, theoretical, and practical approach to ellipsometry. The provided equipment can also be used for other types of studies (glass reflection, Brewster effect, polarization...). **This product was developed in collaboration with the LCP-A2MC laboratory in Metz** **Topics covered:** - Principle of ellipsometry and particularly extinction ellipsometry - Light polarization, identification of the fast and slow axes of a phase retardation plate - Determination of the ellipsometric angles of a material, optical alignment method - Measurement of the refractive indices of a silicon substrate (n and k), a metal, and glass - Measurement of the refractive index (n) and thickness (e) of a SiO2 layer deposited on a silicon substrate - Variation of n and e during a change in wavelength - Demonstration, via the software, of the influence of a measurement error on the values of n, k, and e **Principles and objectives:** Ellipsometry is an optical technique based on measuring the change in the polarization state of a light beam after reflection on a surface. This modification depends on the surface being studied. Thus, for a given wavelength and angle of incidence, it is possible to determine the ellipsometric angles of a material and deduce its characteristics (refractive indices n and k, thickness e). Extinction ellipsometry is based on finding the minimum of light reflected by adjusting the angles of a polarizer and an analyzer. The objective of the proposed setup is to assemble and adjust a didactic ellipsometer to determine the indices and thickness of different samples (silicon substrate, SiO2 monolayer on silicon substrate, aluminum, glass) and analyze the consequences of varying the wavelength and angle of incidence.

Composition:
▪ 1 precision goniometric stage with 1 minute of arc and a grid holder
▪ 2 swinging arms for holding components
▪ 1 set of 4 study samples
▪ 1 green laser 532nm - 1mW with circular symmetry, power supply (ref.205157)
▪ 1 red laser diode 650nm - 1mW with circular symmetry, power supply (ref.205151)
▪ 2 linear polarizers oriented in the horizontal plane in a graduated and rotatable mount (ref.204651)
▪ 1 circular polarizer in a graduated and rotatable mount (ref.202655)
▪ 1 quarter wave plate in a graduated and rotatable mount (ref.202378)
▪ 1 laser power meter with remote probe on a rod (ref.295969+204612)
▪ 1 illuminated magnifier (ref.204752)
▪ 1 dedicated calculation software
▪ 1 set of experiment instructions