Overlay measurements by Mueller polarimetry in back focal plane

Abstract

International audienceAngle resolved Mueller polarimetry implemented as polarimetric imaging of a back focal plane of a high NA microscope objective has already demonstrated a good potential for CD metrology. Here we present the experimental and numerical results indicating that this technique may also be competitive for the measurements of overlay error delta. A series of samples of superimposed gratings with well controlled overlay errors have been manufactured and measured with the angle resolved Mueller polarimeter. The overlay targets were 20-mu m wide. When the overlay error is delta is equal to 0, absolute values of elements of real 4x4 Mueller matrix M are invariant by matrix transposition. Otherwise this symmetry breaks down. Consequently, we define the following overlay estimator matrix as E = |M| - |M|(t). The simulations show that matrix element E-14 is the most sensitive to the overlay error. The scalar estimator of E-14 was calculated by averaging the pixel values over a specifically chosen mask. This estimator is found to vary linearly with d for overlay values up to 50 nm. Our technique allows entering small overlay marks (down to 5-mu m wide). Only one target measurement is needed for each overlay direction. The actual overlay value can be determined without detailed simulation of the structure provided two calibrated overlay structures are available for each direction

Angle-Resolved Cathodoluminescence Imaging Polarimetry

“…23,24 In this letter we introduce a novel technique to access full polarization information in cathodoluminescence spectroscopy. Based on a polarization analysis method previously demonstrated in optical microscopes, [25][26][27][28] we integrate a rotating-plate polarimeter in the detection path of the angle-resolved CL setup. Using the Mueller matrix formalism for the light collection system, we determine the Stokes parameters for CL emission, that is, all parameters required to completely describe the polarization state of the light, which can be polarized, partially polarized or totally unpolarized.…”

Angle-Resolved Polarimetry of Antenna-Mediated Fluorescence

“…Here we show that by measuring the angleresolved full polarization state of the emission it is possible to separate direct emission from emission mediated by a photonic structure and, therefore, to estimate the structure-emitter coupling. We use a k-space polarimeter that combines a Fourier microscope with a polarimeter [25,[27][28][29], to retrieve the Stokes parameters (S 0 , S 1 , S 2 and S 3 ) of fluorescence emitted in the vicinity of bullseye antennas and spirals [19][20][21]30]. The Stokes parameters allow us to calculate the ratio of polarized to unpolarized light, to separate those contributions to the total intensity and to calculate the electric field components that describe the polarized part [31][32][33].…”

Broadband light scattering and photoluminescence enhancement from plasmonic Vogel's golden spirals

“…Dark field and Fourier microscopy measurements suggest that the spirals are diffractive structures that consist of essentially uncoupled scatterers. For further confirmation, we perform k-space Stokes polarimetry [18][19][20][21]. Fig.…”

“…In this article, we study fluorescence enhancement from plasmonic Vogel's golden spirals. To this end, we first unravel the optical response of spirals using darkfield microscopy and k-space Stokes polarimetry [18][19][20][21]. We take into account the polarization response that is not available in Ref.…”