Impact of coherence length on the field of view in dark-field holographic microscopy for semiconductor metrology: theoretical and experimental comparisons

Messinis, Christos; Tenner, Vasco T.; Boer, Johannes F. de; Witte, Stefan; Boef, Arie den

doi:10.1364/ao.379236

Cited by 6 publications

(4 citation statements)

References 27 publications

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“…In addition to the intensity profiles, the holographically reconstructed intensities, which are used in DHM to calculate OV, depend on the visibility function γ of the fringes in the FoV. This results in a finite spatial extent of the reconstructed intensity in the FoV, as presented in earlier work on DHM 19 . Since we calibrate the illumination profile with DHM, we also calibrate and correct the visibility at the same time.…”

Section: Discussionmentioning

confidence: 99%

“…This results in a finite spatial extent of the reconstructed intensity in the FoV, as presented in earlier work on DHM. 19 Since we calibrate the illumination profile with DHM, we also calibrate and correct the visibility at the same time. One important outcome of the illumination beam profile correction is the robustness against target positioning errors.…”

Section: Discussionmentioning

confidence: 99%

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Illumination spot profile correction in digital holographic microscopy for overlay metrology

Adhikary,

van Gardingen-Cromwijk,

de Wit

et al. 2023

J. Micro/Nanopattern. Mats. Metro.

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Background: Precise, accurate, and fast overlay (OV) metrology is an important step in semiconductor device manufacturing. With the increasing demand for better OV over a larger range of different process layers, the optics used in OV metrology tools become more complex, bulky, and expensive. OV, which is to be measured with sub-nanometer precision, is susceptible to many small imperfections in the measurement system.Aim: We present a dark-field digital holographic microscope (DHM) that measures the complex field of the OV targets using simple optics, followed by computational algorithms to correct for hardware imperfections. With the setup, we aim to correct the effects of the absolute intensity of the illumination beam as well as the spatial profile.Approach: The spatial profiles of two oblique illumination beams for diffraction based OV metrology are calibrated using large gratings as calibration targets using DHM, and thereafter OV target images are corrected by the calibrated illumination spot profiles.Results: OVs are calculated for test targets with known OV values, and illumination spot correction removes errors originating from intensity imbalance and intensity variation. Conclusion:We present an optical OV measurement method that is more robust against non-uniform illumination beams using simple calibration steps.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Illumination spot profile correction in digital holographic microscopy for overlay metrology

Adhikary,

van Gardingen-Cromwijk,

de Wit

et al. 2023

J. Micro/Nanopattern. Mats. Metro.

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“…Furthermore, fluorescence microscopy could become a new metrology tool for the characterization of photoresist patterning since it is a noninvasive technique, as opposed to scanning electron microscopy (SEM), and can offer molecular resolution by means of super-resolution fluorescence imaging techniques . In fact, the accurate metrology of the ever-decreasing printed features is becoming a major challenge, and the research on optical-based alternative methods to SEM is currently being pursued . Second, extended aromatic structures have lower electronic band gaps, which provide higher valence band energies than the precursor MOC.…”

Section: Introductionmentioning

confidence: 99%

“…19 In fact, the accurate metrology of the ever-decreasing printed features is becoming a major challenge, and the research on optical-based alternative methods to SEM is currently being pursued. 20 Second, extended aromatic structures have lower electronic band gaps, which provide higher valence band energies than the precursor MOC. Therefore, doping with an extended aromatic carboxylate is expected to lower the ionization potential of the MOCs.…”

Section: ■ Introductionmentioning

confidence: 99%

Fluorescent Labeling to Investigate Nanopatterning Processes in Extreme Ultraviolet Lithography

Hilbers

Lugier

et al. 2021

ACS Appl. Mater. Interfaces

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Extreme ultraviolet (EUV) lithography uses 13.5 nm light to reach the sub-20 nm resolution. However, the process of pattern formation induced by this high-energy light is not wellunderstood. In this work, we provide an inorganic EUV photoresist with fluorescence properties by introducing a carbazole derivative as a ligand, and we study its effect on the patterning process. Using the fluorescence properties, changes in the emission of the material after EUV exposure could be tracked by means of spectroscopy and microscopy. The resist sensitivity was substantially reduced by the incorporation of the carbazole benzoate ligands, which is attributed to hole trapping and steric hindrance. After EUV irradiation of the resist films, infrared, UV−visible absorption, and fluorescence spectroscopies showed that the carbazole units were still mostly intact, although their fluorescence intensity was lowered. Our work shows that fluorescent labeling can provide relevant mechanistic insights in the patterning process of resists, potentially with a molecular resolution.

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Diffraction-based overlay metrology using angular-multiplexed acquisition of dark-field digital holograms

et al. 2020

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In semiconductor device manufacturing, optical overlay metrology measures pattern placement between two layers in a chip with sub-nm precision. Continuous improvements in overlay metrology are needed to keep up with shrinking device dimensions in modern chips. We present first overlay metrology results using a novel off-axis dark-field digital holographic microscopy concept that acquires multiple holograms in parallel by angular multiplexing. We show that this concept reduces the impact of source intensity fluctuations on the noise in the measured overlay. With our setup we achieved an overlay reproducibility of 0.13 nm and measurements on overlay targets with known programmed overlay values showed good linearity of R2= 0.9993. Our data show potential for significant improvement and that digital holographic microscopy is a promising technique for future overlay metrology tools.

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Impact of coherence length on the field of view in dark-field holographic microscopy for semiconductor metrology: theoretical and experimental comparisons

Cited by 6 publications

References 27 publications

Illumination spot profile correction in digital holographic microscopy for overlay metrology

Illumination spot profile correction in digital holographic microscopy for overlay metrology

Fluorescent Labeling to Investigate Nanopatterning Processes in Extreme Ultraviolet Lithography

Diffraction-based overlay metrology using angular-multiplexed acquisition of dark-field digital holograms

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