Automatic feature selection in EUV scatterometry

Ansuinelli, Paolo; Coene, W.; Urbach, H. P.

doi:10.1364/ao.58.005916

Cited by 11 publications

(9 citation statements)

References 28 publications

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“…To distinguish it from the 2-θ scatterometer, we call this type of angular scatterometer a scattering-angle-resolved scatterometer (The 2-θ scatterometer can be regarded as an incidenceangle-resolved scatterometer). To ensure that there is enough scattering information available for accurate profile reconstruction of short-pitch structures, light sources with short illumination wavelengths, such as an extreme ultraviolet (EUV) light source [236][237][238][239] or an x-ray light source [240][241][242][243], can be employed in scattering-angle-resolved scatterometers.…”

Section: Scatterometric Setupsmentioning

confidence: 99%

“…In response to these challenges, future trends for optical scatterometry include the extension of illumination wavelengths to short or ultra-short ranges, such as EUV and x-rays [236][237][238][239][240][241][242][243], and making full use of light polarization [253,254] to improve measurement sensitivity. Also, since there is no single technique that can fully fulfill the measurement requirements (such as resolution, speed, precision) of a full set of structural parameters of a complex device, the combination or integration of multiple techniques, also known as hybrid or combined metrology, is an important trend that will extend the capability of current techniques [290,291].…”

Section: Future Trendsmentioning

confidence: 99%

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An insight on optical metrology in manufacturing

Shimizu

Chen

Kim

et al. 2020

Meas. Sci. Technol.

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Optical metrology is one of the key technologies in today's manufacturing industry. In this article, we provide an insight into optical measurement technologies for precision positioning and quality assessment in today's manufacturing industry. First, some optical measurement technologies for precision positioning are explained, mainly focusing on those with a multi-axis positioning system composed of linear slides, often employed in machine tools or measuring instruments. Some optical measurement technologies for the quality assessment of products are then reviewed, focusing on technologies for form measurement of products with a large metric structure, from a telescope mirror to a nanometric structure such as a semiconductor electrode. Furthermore, we also review the state-of-the-art optical technique that has attracted attention in recent years, optical coherence tomography for the non-destructive inspection of the internal structures of a fabricated component, as well as super-resolution techniques for improving the lateral resolution of optical imaging beyond the diffraction limit of light. This review article provides insights into current and future technologies for optical measurement in the manufacturing industry, which are expected to become even more important to meet the industry's continuing requirements for high-precision and high-efficiency machining.

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Section: Scatterometric Setupsmentioning

confidence: 99%

Section: Future Trendsmentioning

confidence: 99%

An insight on optical metrology in manufacturing

Shimizu

Chen

Kim

et al. 2020

Meas. Sci. Technol.

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“…As in the dimensional reconstructions of nanostructured surfaces by scatterometry in the soft X-ray and EUV spectral ranges [16]. Scatterometry problems are likely multi-modal [16,17], adjusting relevant optimization parameters such as the optical constants would automatically yield higher reliability. That is highly relevant for the scatterometry based metrology of Mo/Si MLMs, that are used in current EUV photomasks.…”

Section: Introductionmentioning

confidence: 99%

High-precision optical constant characterization of materials in the EUV spectral range: from large research facilities to laboratory-based instruments

Soltwisch

Glabisch

Andrle³

et al. 2022

37th European Mask and Lithography Conference

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Any modeling of an interaction between photons and matter is based on the optical parameters. The determination of these parameters, also called optical constants or refractive indices, is an indispensable component for the development of new optical elements such as mirrors, gratings, or lithography photomasks. Especially in the extreme ultraviolet (EUV) spectral region, existing databases for the refractive indices of many materials and compositions are inadequate or are a mixture of experimentally measured and calculated values from atomic scattering factors. Synchrotron radiation is of course ideally suited to verify such material parameters due to the tuneability of photon energy. However, due to the large number of possible compounds and alloys, the development of EUV laboratory reflectometers is essential to keep pace with the development of materials science and allow for inline or on-site quality control. Additionally, optical constants are also essential for EUV metrology techniques that aim to achieve dimensional reconstruction of nanopatterned structures with sub-nm resolution. For this purpose, we studied a TaTeN grating created on an EUV Mo/Si multilayer mirror, to mimic a novel absorber EUV photomask. We present here a first reconstruction comparison of these structures, measured by EUV scatterometry at the electron storage ring BESSYII and with a laboratory setup of a spectrally-resolved EUV reflectometer developed at RWTH Aachen University. Both approaches differ in several aspects reaching from setup size to spectral quality (brilliance, bandwidth and coherence) as well as the measured and simulated data.

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“…In the EUV range, many abundant elements' emission lines are found, thus making the EUV critical for spectroscopic studies, both terrestrial and celestial [1]- [3]. In the last two decades, EUV radiation has been utilized for scatterometry of nanostructures [4], [5], microscopy [7], ptychography [6], Magnetic Circular Dichroism (MCD) studies apart from other fields [8], [9]. In 2010, ASML's Extreme Ultraviolet Lithography (EUVL) systems using a wavelength of 13.5 nm with a Numerical Aperture (NA) of 0.25 were introduced [10].…”

Section: Introductionmentioning

confidence: 99%

“…Scatterometry is a robust noncontact and efficient solution for EUV photomasks metrology. Concerning periodic structures such as gratings, scatterometry is a powerful characterization method for inferring information about the structure's geometrical characteristics such as roughness, Sidewall Angle (SWA) and Critical Dimension (CD) [14] [15]. Being noncontact and efficient, scatterometry has advantages over other widely used EUV photomasks metrology approaches such as electron microscopy and Atomic Force Microscopy (AFM) [16].…”

Section: Introductionmentioning

confidence: 99%

Precise optical constants: determination and impact on metrology, simulation, and development of EUV masks

Saadeh

Mesilhy²,

Soltwisch

et al. 2022

Photomask Technology 2022

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The interaction of matter and light can be described based on optical constants, shortly called δ&β. These constants provide the fundamental basis for the design of any optical system. In the Extreme Ultraviolet (EUV) spectral range, however, the existing data for many materials or compounds is very sparse, non-existent or exhibit considerable discrepancies between different sources. This is further complicated since the scaling effects stipulate the optical response of a thin film to differ from bulk. Oxidation, impurities or interdiffusion significantly affect the optical response of a system to EUV radiation. For this reason, the Physikalisch-Technische Bundesanstalt (PTB) is establishing a new database in cooperation with other European partners. This database, designated as the Optical Constants Database (OCDB) can be accessed online freely (OCDB.ptb.de). This data collection shall support further development of various fields from new metrological techniques, like EUV scatterometry to computational lithography in the EUV. This is demonstrated exemplarily here by the interplay between δ&β and the dimensional parameters with respect to a structured TaTeN EUV photomask. It is equally important either direction, to derive structure parameters from the measured EUV scattering as vice versa to predict the EUV response from the geometrical structure. In addition, the impact of varying δ and β on the expected imaging performance will be investigated by simulating typical lithographic image metrics like Critical Dimension (CD), best focus position, image contrast (NILS) and non-telecentricity for the imaging of through pitch L/S and 16 nm vertical Lines with 32 nm pitch in a NA=0.55 scanner for TaTeN mask absorber as typical representatives of high-k absorber materialsand as an example of the effect on imaging simulation.

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Automatic feature selection in EUV scatterometry

Cited by 11 publications

References 28 publications

An insight on optical metrology in manufacturing

An insight on optical metrology in manufacturing

High-precision optical constant characterization of materials in the EUV spectral range: from large research facilities to laboratory-based instruments

Precise optical constants: determination and impact on metrology, simulation, and development of EUV masks

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