Thickness of SiO2 thin film on silicon wafer measured by dispersive white-light spectral interferometry

Spectral interferometry and reflectometry used to measure thin films

“…Recently, we used dispersive white-light spectral interferometry for measuring the thickness of SiO 2 thin film on a silicon wafer [10]. The technique utilizes a slightly dispersive Michelson interferometer with one of the mirrors replaced by the thin-film structure of known optical constants.…”

The effect of silicon substrate on thickness of SiO2 thin film analysed by spectral reflectometry and interferometry

“…The method determines the maximum-likelihood estimate of the thin-film thickness d that minimizes the figure-ofmerit function χ 2 , defined by The effect of silicon substrate on thickness of SiO 2 thin film analysed by spectral reflectometry and interferometry where λ i are wavelengths at which the fit was performed (450 to 900 nm). Theoretical values of the reflectance R(λ) were computed according to the well-known relations that take into account the known wavelength dependence for the refractive index of SiO 2 thin film [9,10] and the measured complex refractive index of the silicon substrate. Figure 1 demonstrates very good agreement between theory and experiment with the correlation coefficient as high as 0.99965 and the thin-film thickness d=280.1 nm.…”

“…The OPD ∆(λ) is used to construct for a chosen mirror position L = L 0 the nonlinear-like phase function δ(λ) given by the relation (2) where t eff is the effective thickness of a beam splitter cube [9][10][11] and δ 2 (λ) is the phase change on reflection from the mirror in the interferometer. To compensate for the phase change δ 2 (λ), a next measurement step with the reference sample used instead of the thin-film structure needs to be applied [11].…”

“…The experimental set-up used in the application of spectral reflectometry and interferometry to analyse the effect of silicon substrate on the thickness of SiO 2 thin film is the same as that shown in previous papers [9][10][11]. It consists of a white-light source: a halogen lamp HL-2000 (Ocean Optics) with launching optics, an optical fibre with a collimating lens, a bulk-optic Michelson interferometer with a cube beam splitter made of BK7 optical glass, a metallic mirror connected to a micropositioner, a thin-film structure, a microscope objective, micropositioners, a read optical fibre, a miniature fibre-optic spectrometer S2000 (Ocean optics), an A/D converter and a personal computer.…”

“…Recently, we used dispersive white-light spectral interferometry for measuring the thickness of SiO 2 thin film on a silicon wafer [9]. The technique utilizes a slightly dispersive Michelson interferometer with one of the mirrors replaced by a thin-film structure of known optical constants.…”