The development of suitable radiation sources for extreme ultraviolet lithography (EUVL) is a major challenge. For the optimization of these sources and for the determination of the parameters needed for the system design and the system integration these sources have to be characterized in terms of the absolute in-band power, the spectral distribution in the EUV spectral region and the out-of-band spectral regions, the spatial distribution of the emitting volume and the angular distribution of the emission. For improving the lifetime of such sources, generally accepted as one key risk with EUVL, another task, the debris emitted from sources under development has to be investigated. Therefore, JENOPTIK Mikrotechnik GmbH is co-operating with the Laser Laboratorium Goettingen, the Physikalisch-Technische Bundesanstalt (PTB) and the AIXUV GmbH in developing ready-for-use metrology tools for EUVL source characterization and optimization. The set of the tools employed for EUV-source characterization is presented in detail as well as concepts for calibration and measurement procedures.
Rainer Lebert, Christian Wies, Bernhard Jaegle, Larissa Juschkin, Ulrich Bieberle, Manfred Meisen, Willi Neff, Klaus Bergmann, Konstantin Walter, Oliver Rosier, Max Schuermann, Thomas Missalla
Compact, flexible laboratory sources offer advanced flexibility in developing components for EUV-lithography by supplementing beamlines at storage rings. Hence, they are the basis for transferring EUV-metrology and technology to individual, industrial and university R&D labs. Laboratory sources have features similar to the sources planned for EUVL production on one hand and offer high flexibility like storage ring beamlines on the other hand.
Discharge based EUV sources offer some flexibility, which allow for tuning of the spectral and spatial characteristics of their emission. Depending on the system complexity sources can be supplied in various forms ranging from low budget semi-manual systems over OEM components to fully automatic stand-alone sources. As power scaling has been demonstrated by just adding higher power generators and cooling, these sources can be matched to various levels of flux requirements.
AIXUV’s discharge based EUV-sources have been used as beamline supplement for tasks closely connected with the development of EUV-Lithography. Examples are: development of tools for EUV source characterization (prototype testing, qualification and calibration), “in-band-EUV” open frame resist exposure, reflectometry of EUV mask blanks and EUV mirrors and for basic research using XUV radiation as thin film analytics and EUV microscopy.
utilizing a laser-based source for the generation of 13nm radiation. The EUV plasma is produced by focusing a Nd:YAG laser into a pulsed xenon or oxygen gas jet. The alternate use of these two target gases accomplishes either an intense broad-band (Xe) or a less intense narrow-band line emission (O2) at 13nm.
Different types of nozzles were tested in order to optimize the emitted radiation with respect to maximum EUV intensities, small source dimensions and pulse-to-pulse stabilities. The investigation of these crucial source parameters was performed with specially designed EUV pinhole cameras, utilizing evaluation algorithms developed for standardized laser beam characterization. In addition, a rotatable pinhole camera was developed which allows spatially and angular resolved monitoring of the soft X-ray emission characteristics. With the help of this camera a strong angular dependence of the EUV intensity was found, indicating reabsorption of the EUV radiation in the surrounding gas. The results were compared with Rayleigh scattering measurements for visualization of the target gas density.
The development of suitable radiation sources is a major challenge for extreme ultraviolet lithography (EUVL). For the optimization of these sources and for the determination of the parameters needed for the system design and the system integration these sources have to be characterized in terms of the absolute in-band power, the spectral distribution in the EUV spectral region and the out-band spectral regions, the spatial distribution of the emitting volume and the angular distribution of the emission. Also the source debris has to be investigated. Therefore, JENOPTIK Mikrotechnik GmbH is co-operating with the Laser Laboratorium Goettingen, the Physikalisch-Technische Bundesanstalt (PTB) and the AIXUV GmbH in developing ready-for-use metrology tools for EUVL source characterization and optimization. The set of the tools employed for EUV-source characterization is presented in detail as well as concepts of for calibration and measurement procedures.
Generation of extreme ultraviolet (EUV) radiation from solid targets is studied and a compact EUV source for small-scale lithographic applications and EUV metrology is development. This source is based on a transfer of conventional x-ray tube technology into the EUV spectral range. As in an ordinary x-ray tube, electrons are generated by a tungesten filament and accelerated in a high-voltage electric field towards a solid target. In the demonstrated "EUV tube" beryllium and silicon targets are used to generate radiation at 11.4 nm and 13.5 nm, respectively. The absolute converstion efficiencies into EUV photons are measured. At 13.5 nm an EUV power of 34μW or 2×1012 photon/s (in 2% bandwidth and a solid angle of 2π sr) is demonstrated. Prospects for a further power scaling of the EUV source are discussed.
Generation of extreme ultraviolet (EUV) radiation from solid targets is studied and a compact EUV source for small-scale lithographic applications and EUV metrology is developed. This source is based on a transfer of conventional x-ray tube technology into the EUV spectral range. As in an ordinary x-ray tube, electrons are generated by a tungsten filament and accelerated in a high-voltage electric field toward a solid target. In the demonstrated "EUV tube" beryllium and silicon targets are used to generate radiation at 11.4 and 13.5 nm, respectively. The absolute conversion efficiencies into EUV photons at 13.5 nm are measured. Prospects for a further power scaling of the EUV source are discussed.
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