Abstract
Non-interferometric phase retrieval from the intensity measurements in Coherent Fourier Scatterometry (CFS) is presented using a scanning focused spot. Formulae to determine the state of polarization of the scattered light and to retrieve the phase difference between overlapping scattered orders are given. The scattered far field is rigorously computed and the functionality of the method is proved with experimental results.
Highlights
In conventional incoherent optical scatterometry (IOS), light from an incoherent source interacts with the scatterer and the diffracted far field intensity map is recorded [1, 2]
The distribution in phase map is dependent upon the geometrical parameters of the grating and the bias
The phase dependency on the geometrical parameters can be used in grating reconstruction in addition to the intensity data
Summary
In conventional incoherent optical scatterometry (IOS), light from an incoherent source interacts with the scatterer and the diffracted far field intensity map is recorded [1, 2]. We show how the phase difference between overlapping diffracted orders of the grating for two orthogonal states of polarization can be retrieved. We derive an analytic phase relationship between the diffracted orders of the reflected far field in terms of intensities acquired for different scan positions within a single period of the grating. In the remainder of this paper, we assume that the state of polarization, the amplitude and the phase of the incident field have been determined. This means that aiξ (ξi, ηi) and aiη (ξi, ηi) are known complex functions of position (ξi, ηi) in the pupil (except for an overall constant phase). In the remainder of this paper we assume that 1 ≤ F ≤ 2 but, the analysis can be extended to other values of F when more orders overlap
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More From: Journal of the European Optical Society-Rapid Publications
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