Analysis of Line-Edge Roughness Using EUV Scatterometry

Herrero, Analía Fernández; Scholze, Frank; Dai, Gaoliang; Soltwisch, Victor

doi:10.1007/s41871-022-00126-w

Cited by 8 publications

(3 citation statements)

References 30 publications

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“…9 In certain scenarios, shorter wavelengths toward EUV and x-rays would be desired for increased sensitivity to weak parameters of interest, roughness, precise shape analyses, or measurements of optically opaque materials. [10][11][12] In contrast, longer wavelengths in the infrared or terahertz would be beneficial for contactless electrical transport property characterization of patterned materials. 13,14 Although x-ray scattering 15 and mid-infrared ellipsometry 16 in-line tools have been demonstrated for CD metrology in 3D NAND channel holes, further tool developments are required to efficiently deploy them for metrology on patterned wafers in advanced logic manufacturing.…”

Section: Scatterometry Challenges and Strategiesmentioning

confidence: 99%

Spectral interferometry for fully integrated device metrology

Schmidt¹,

Medikonda²,

Rizzolo³

et al. 2023

J. Micro/Nanopattern. Mats. Metro.

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A spectral interferometry technique called vertical travelling scatterometry (VTS) is introduced, demonstrated, and discussed. VTS utilizes unique information from spectral interferometry and enables solutions for applications that are infeasible with traditional scatterometry approaches. The technique allows for data filtering related to spectral information from buried layers, which can then be ignored in the optical model. Therefore, using VTS, selective analyses of the topmost part of an arbitrarily complex stack are possible within a single metrology step. This methodology helps to overcome geometrical complexities and allows for focusing on parameters of interest through dramatically simplified optical modeling. Such model simplifications are specifically desired for back-end-of-line applications. Three examples are monitored discussed: (i) the critical dimensions (CDs) of a first metal level on top of nanosheet gate-all-around transistor structures, (ii) the thickness of an interlayer dielectric above embedded memory in the active area, and (iii) the CDs of trenches on top of tall stacks in the micrometer range comprising many layered dielectrics. It was found that, in all three cases, data filtering through VTS allowed for a simple optical model capable of delivering parameters of interest. The validity and accuracy of the VTS solution results were confirmed by extensive reference metrology obtained by traditional scatterometry, scanning electron microscopy, and transmission electron microscopy. Furthermore, it was shown that machine learning models trained with VTS filtered data can converge to a robust solution with a smaller dataset compared with models training with traditional scatterometry data.

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Section: Scatterometry Challenges and Strategiesmentioning

confidence: 99%

Spectral interferometry for fully integrated device metrology

Schmidt¹,

Medikonda²,

Rizzolo³

et al. 2023

J. Micro/Nanopattern. Mats. Metro.

View full text Add to dashboard Cite

show abstract

“…(AFM) provide high spatial and axial resolution but have limitations including slow data collection, potential sample damage and dependence on stringent measurement conditions, making them less ideal for in-line measurements. Scatterometry, a manufacturing metrology workhorse, is a non-imaging, model-based, optical technique that allows sub-nanometer measurements of isolated or periodic structures, optical constants, material properties or roughness [2,[7][8][9]. Coherent Fourier scatterometry (CFS) is an advanced scatterometry technique which captures the scattered field from multiple angles incident on the sample plane using a focused spot [10].…”

Section: Introductionmentioning

confidence: 99%

Multi-beam coherent Fourier scatterometry

Soman,

Horsten,

Scholte

et al. 2024

Meas. Sci. Technol.

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Inspection of surface and nanostructure imperfections play an important role in high-throughput manufacturing across various industries. This paper introduces a novel, parallelised version of the metrology and inspection technique: Coherent Fourier Scatterometry (CFS). The proposed strategy employs parallelisation with multiple probes, facilitated by a diffraction grating generating multiple optical beams and detection using an array of split detectors. The article details the optical setup, design considerations, and presents results, including independent detection verification, calibration curves for different beams, and a data stitching process for composite scans. The study concludes with discussions on the system's limitations and potential avenues for future development, emphasizing the significance of enhancing scanning speed for the widespread adoption of CFS as a commercial metrology tool.

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“…We model these measurements, using an finite element method (FEM) Maxwell solver 3 and feed the results into an optimization scheme with a combination of global and local peak findings algorithms, which eventually produce the looked-for parameters. 4 Roughness and imperfections can be included using approximations like the Debye-Waller factor 5,6 which damps the intensity of higher diffraction orders.…”

Section: Introductionmentioning

confidence: 99%

Pushing the boundaries of EUV scatterometry: reconstruction of complex nanostructures for next-generation transistor technology

Ciesielski

Lohr

Mertens

et al. 2023

Metrology, Inspection, and Process Control XXXVII

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EUV scatterometry can retrieve geometrical information from nanoscale grating structures through elastic scattering of EUV radiation and the evaluation of the diffraction intensities. Its geometry and energy range place it in between grazing incidence x-ray scattering (GISAXS) and optical critical dimension (OCD). PTB recently commissioned a new scatterometry setup for the EUV and soft x-ray region that can address sample areas below 100 × 100 μm size by using a comparably steep, grazing angle of incidence of up to 30°. At the same time, the full cone of exit angles of 30° can be detected such that also the higher orders can be recorded in scatterometry measurements. It has been commissioned at PTB’s monochromatic soft x-ray beamline at the synchrotron radiation facility BESSY II and can also be used for simultaneous x-ray fluorescence detection. Its great tunability and energy resolution allows to scan across absorption edges of the relevant semiconductor materials to increase the contrast between different materials. The nanoscale geometry of modern transistor designs features different materials and structure sizes in the single digit nanometer range. Using the information wealth of spectrally resolved scatterometry measurements from the new setup, we present data and first geometrical reconstructions of selected, complex, industry-relevant design studies. The geometrical reconstruction of these structures relies on precise measurements, modelling of the scattering process, and statistical data evaluation methods.

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Analysis of Line-Edge Roughness Using EUV Scatterometry

Cited by 8 publications

References 30 publications

Spectral interferometry for fully integrated device metrology

Spectral interferometry for fully integrated device metrology

Multi-beam coherent Fourier scatterometry

Pushing the boundaries of EUV scatterometry: reconstruction of complex nanostructures for next-generation transistor technology

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