Mr. Bartlomiej W. Salski Profile

Bartlomiej W. Salski

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Publications (5)

Proceedings Article | 22 May 2009 Paper

Hybrid FDTD-Fresnel modeling of the scanning confocal microscopy

Bartlomiej Salski, Wojciech Gwarek

Proceedings Volume 7378, 737826 (2009) https://doi.org/10.1117/12.821824

KEYWORDS: Finite-difference time-domain method, Confocal microscopy, Image processing, 3D modeling, Scattering, 3D acquisition, 3D image processing, Objectives, Gaussian beams, Stereoscopy

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Proceedings Article | 23 March 2009 Paper

Overlay metrology for double patterning processes

Philippe Leray, Shaunee Cheng, David Laidler, Daniel Kandel, Mike Adel, Berta Dinu, Marco Polli, Mauro Vasconi, Bartlomiej Salski

Proceedings Volume 7272, 72720G (2009) https://doi.org/10.1117/12.814182

KEYWORDS: Overlay metrology, Double patterning technology, Semiconducting wafers, Diffraction, Scanners, Calibration, Metrology, Diffraction gratings, Spectroscopy, Polarizers

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The double patterning (DPT) process is foreseen by the industry to be the main solution for the 32 nm technology node and even beyond. Meanwhile process compatibility has to be maintained and the performance of overlay metrology has to improve. To achieve this for Image Based Overlay (IBO), usually the optics of overlay tools are improved. It was also demonstrated that these requirements are achievable with a Diffraction Based Overlay (DBO) technique named SCOL^TM [1]. In addition, we believe that overlay measurements with respect to a reference grid are required to achieve the required overlay control [2]. This induces at least a three-fold increase in the number of measurements (2 for double patterned layers to the reference grid and 1 between the double patterned layers). The requirements of process compatibility, enhanced performance and large number of measurements make the choice of overlay metrology for DPT very challenging. In this work we use different flavors of the standard overlay metrology technique (IBO) as well as the new technique (SCOL) to address these three requirements. The compatibility of the corresponding overlay targets with double patterning processes (Litho-Etch-Litho-Etch (LELE); Litho-Freeze-Litho-Etch (LFLE), Spacer defined) is tested. The process impact on different target types is discussed (CD bias LELE, Contrast for LFLE). We compare the standard imaging overlay metrology with non-standard imaging techniques dedicated to double patterning processes (multilayer imaging targets allowing one overlay target instead of three, very small imaging targets). In addition to standard designs already discussed [1], we investigate SCOL target designs specific to double patterning processes. The feedback to the scanner is determined using the different techniques. The final overlay results obtained are compared accordingly. We conclude with the pros and cons of each technique and suggest the optimal metrology strategy for overlay control in double patterning processes.

Proceedings Article | 22 March 2008 Paper

Diffraction based overlay metrology: accuracy and performance on front end stack

Philippe Leray, Shaunee Cheng, Daniel Kandel, Michael Adel, Anat Marchelli, Irina Vakshtein, Mauro Vasconi, Bartlomiej Salski

Proceedings Volume 6922, 69220O (2008) https://doi.org/10.1117/12.772516

KEYWORDS: Overlay metrology, Scatterometry, Semiconducting wafers, Diffraction, Chemical mechanical planarization, Silicon, Etching, Metrology, Scanners, Detection and tracking algorithms

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Proceedings Article | 18 June 2007 Paper

Differential signal scatterometry overlay metrology: an accuracy investigation

Daniel Kandel, Mike Adel, Berta Dinu, Boris Golovanevsky, Pavel Izikson, Vladimir Levinski, Irina Vakshtein, Philippe Leray, Mauro Vasconi, Bartlomiej Salski

Proceedings Volume 6616, 66160H (2007) https://doi.org/10.1117/12.725929

KEYWORDS: Overlay metrology, Scatterometry, Semiconducting wafers, Detection and tracking algorithms, Computer simulations, Silicon, Standards development, Electromagnetism, Metrology, Algorithms

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Proceedings Article | 18 June 2007 Paper

Enhancements to FDTD modeling for optical metrology applications

Bartlomiej Salski, Malgorzata Celuch, Wojciech Gwarek

Proceedings Volume 6617, 66170U (2007) https://doi.org/10.1117/12.726188

KEYWORDS: Finite-difference time-domain method, Modeling, Scattering, Diffraction gratings, Diffraction, Optical metrology, 3D modeling, Phase shifts, Microwave radiation, Antennas

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This paper presents Finite Difference Time Domain (FDTD) method based on discretised Maxwell curl equations and widely used in microwave circuit design - as a promising tool for new optical metrology purposes. We focus on periodic FDTD formulations for scattering problems. The interest in efficient full-wave modelling of periodic structures has arisen due to their increasing applications as slow wave transmission lines, photonic crystals, and metamaterials. Recently, new efforts have been made to incorporate the FDTD algorithms into the scatterometry overlay technology (SCOL) toolkit. In SCOL, multilayered grating targets on silicon wafers are illuminated with polarised light at a particular angle of incidence; reflected signal of the 0^th diffraction order is processed to extract the information about misalignment between grating layers. Since the illumination spot size typically covers tens or even hundreds of grating periods, direct 3D FDTD modelling of such an electrically large problem needs long computing times. The periodic FDTD algorithm discussed herein, built upon Floquet theorem, allows reduction of the modelling problem to one or just a few periods. As a consequence, it substantially speeds up the simulation. The incident wave is modelled as a plane wave. The reflected wave is extracted via near-to-far (NTF) transformation as in antenna analysis. We cross-calibrate the FDTD algorithm against other numerical techniques better established in optical metrology, like Rigorous Coupled Wave Analysis (RCWA). For a benchmark of multilayered rectangular grating composition illuminated with light within the 500 to 700 nm spectrum, we show that the FDTD and RCWA results for the 0^th diffraction order reflection coefficient are in excellent agreement. The FDTD approach is more flexible as it further allows quantitative characterisation of non-rectangular periodic structures, higher-order diffraction rays, and periodicity violation. This work was done in the framework of the SOCOT Consortium [18], sponsored by the European Commission under the IST 6^th Framework Programme, Contract No. 016403.

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