Mueller polarimetry in the back focal plane

Martino, A. De; Hatit, S. Ben; Foldyna, Martin

doi:10.1117/12.708627

Cited by 19 publications

(12 citation statements)

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“…A sample prepared with identical sputtering conditions was also studied ex situ with a single wavelength (633 nm) angle resolved Mueller matrix polarimeter. The instrument applied a high numerical aperture (NA=0.95) microscope objective in a double pass configuration with its back focal plane imaged on a charge coupled device camera, allowing simultaneous measurements of reflected light at all azimuth angles and all angles of incidence below 62 • [20][21][22]. .…”

Section: Methodsmentioning

confidence: 99%

Real-time in situ Mueller matrix ellipsometry of GaSb nanopillars: observation of anisotropic local alignment

Nerbø¹,

Roy²,

Sondergard³

et al. 2011

Opt. Express

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The formation of GaSb nanopillars by low energy ion sputtering is studied in real-time by spectroscopic Mueller matrix ellipsometry, from the initial formation in the smooth substrate until nanopillars with a height of 200-300 nm are formed. As the nanopillar height increased above 100 nm, coupling between orthogonal polarization modes was observed. Ex situ angle resolved Mueller polarimetry measurements revealed a 180° azimuth rotation symmetry in the off-diagonal Mueller elements, which can be explained by a biaxial material with different dielectric functions εx and εy in a plane parallel to the substrate. This polarization coupling can be caused by a tendency for local direction dependent alignment of the pillars, and such a tendency is confirmed by scanning electron microscopy. Such observations have not been made for GaSb nanopillars shorter than 100 nm, which have optical properties that can be modeled as a uniaxial effective medium.

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Section: Methodsmentioning

confidence: 99%

Real-time in situ Mueller matrix ellipsometry of GaSb nanopillars: observation of anisotropic local alignment

Nerbø¹,

Roy²,

Sondergard³

et al. 2011

Opt. Express

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“…With current field aperture (3), the spot size can be decreased down to 10µm, using smaller aperture the spot size could be reduced to 5µm. The detailed description of the experimental set-up can be found elsewhere [1] In order to illustrate the interpretation of the experimental data the enlarged image of element M 34 is shown in Fig.3a. Normally the elements of Mueller matrix of isotropic sample should not depend on azimuthal angle in (s,p) frame.…”

Section: Experimental Set-upmentioning

confidence: 99%

Overlay measurements by Mueller polarimetry in the back focal plane

Novikova¹,

Fallet

Manhas

et al. 2011

SPIE Proceedings

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Angle resolved Mueller polarimetry implemented as polarimetric imaging of the back focal plane of a high NA microscope objective has already demonstrated a good potential for CD metrology 1 . In this paper we present the experimental and numerical results which indicate that this technique may also be competitive for measurements of the overlay error δ between two gratings at different levels. 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 µm wide. When overlay error δ = 0 the absolute value of Mueller matrix elements is invariant by matrix transposition. This symmetry breaks down when δ ≠ 0. As a result, we can define the following overlay estimator matrix: Ε = |Μ | − |Μ | t . The simulations show that matrix element E 14 is the most sensitive to the overlay error. In the experiments the scalar estimator of E 14 was defined by averaging the pixel values over specifically chosen mask. The scalar estimator is found to vary essentially linearly with δ for the overlay values up to 50 nm. Our technique allows entering quite small overlay marks (down to 5 µm wide). The only one target measurement is needed for each overlay direction. The actual overlay value can be determined without detailed simulation of the structure provided the two calibrated overlay structures are available for each direction.

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“…This set-up is inspired by an epi-illumination microscope [6] and by the former experimental set-up designed by Ben Hatit et al [7]. The device is made of two 'separate' blocks; illumination and imaging though the high-aperture microscope objective is used in both blocks, acting as both condenser and objective.…”

Section: Description Of the Devicementioning

confidence: 99%

Applications of Mueller polarimetry in the Fourier space for overlay characterization in microelectronics

et al. 2010

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We present a new optical technique using complete Mueller polarimetry in the back focal plane of a microscope objective to characterize the overlay defects in microelectronics industry. Exploiting the fundamental symmetries in the physics of periodic structures and polarized light and the redundancies in the angle-resolved images we prove that it is possible to measure overlay by this fast and non-destructive technique. The simulations of the one-dimensional structures have shown that the values of a chosen criterion exploiting the off-diagonal coefficients symmetries are proportional to the values of overlay defects and can reach 0.25 for a 25nm defect. The accuracy of the polarimeter used for this application becomes even more critical because it is directly linked to the overlay measurement. Beside the redundancies in the acquired data, the angular resolution allows us also to decouple the information along X and Y directions in the Fourier space. Due to this the overlay defect can be characterized and decomposed with respect to these two axes.We show that the proposed new technique is sensitive to both magnitude and sign of the shift. Thus, Mueller polarimetry in the Fourier space (MPFS) offers more parameters for the process quality control compared with conventional spectroscopic ellipsometry (SE). It means that MPFS should be more efficient than SE for the overlay characterization in microelectronic industry.

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Mueller polarimetry in the back focal plane

Cited by 19 publications

References 0 publications

Real-time in situ Mueller matrix ellipsometry of GaSb nanopillars: observation of anisotropic local alignment

Real-time in situ Mueller matrix ellipsometry of GaSb nanopillars: observation of anisotropic local alignment

Overlay measurements by Mueller polarimetry in the back focal plane

Applications of Mueller polarimetry in the Fourier space for overlay characterization in microelectronics

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