With the introduction of the NXE:3400B scanner, ASML has brought extreme ultraviolet lithography (EUV) to high-volume manufacturing (HVM). The high-EUV power of >200 W being realized with this system satisfies the throughput requirements of HVM, but also requires reconsideration of the imaging aspects of spectral purity, both from the details of the EUV emission spectrum and from the deep-ultraviolet (DUV) emission. We present simulation and experimental results for the spectral purity of high-power EUV systems and the imaging impact of this, both for the case of with and without a pellicle. Also, possible controls for spectral purity will be discussed, and an innovative method will be described to measure imaging impact of varying conversion efficiency (CE) and DUV. It will be shown that CE optimization toward higher source power leads to reduction in relative DUV content, and the small deltas in EUV source spectrum for higher power do not influence imaging. It will also be shown that resulting variations in DUV do not affect imaging performance significantly, provided that a suitable reticle black border is used. In summary, spectral purity performance is found to enable current and upcoming nodes of EUV lithography and to not be a bottleneck for further increasing power of EUV systems to well above 250 W.
With the introduction of the NXE:3400B scanner, ASML has brought EUV to High-Volume Manufacturing (HVM). The high EUV power of >200W being realized with this system satisfies the throughput requirements of HVM, but also requires reconsideration of the imaging aspects of spectral purity, both from the details of the EUV emission spectrum and from the DUV emission. This paper will present simulation and experimental results for the spectral purity of high-power EUV systems, and the imaging impact of this, both for the case of with and without a pellicle. Also, possible controls for spectral purity will be discussed, and a novel method will be described to measure imaging impact of varying CE and DUV. It will be shown that CE optimization towards higher source power leads to reduction in relative DUV content, that the small deltas in EUV source spectrum for higher power do not influence imaging. It will also be shown that resulting variations in DUV do not affect imaging performance significantly, provided that a suitable reticle black border is used. In short, spectral purity performance is not a bottleneck for increasing power of EUV systems to well above 250W.
Here we describe a new holographic recording method in which a separate reference wave is not required. Object
wave is split into two beams and one of them is spatially filtered to create a plane reference wave. This method
allows the use of low coherence light sources since pathlengths of the interfering waves are matched automatically
which will lead to holographic recording of objects at any distance rather easily. Optical setup will be discussed
and the experimental results will be presented.
KEYWORDS: Holograms, Convolution, Diffraction, 3D image reconstruction, Fourier transforms, Digital holography, Holography, Computing systems, Near field diffraction, Image restoration
In recent years the field of digital holography became an attractive research area following the developments of
CCD-arrays and an ever increasing computational power of computers. Here we investigate digital holography
reconstruction methods and compare them for the accuracy and the computational speed. In addition, possible
discrepancies in the calculation of the diffraction integral via fourier transform is clarified and it is compared
to convolution methods. The proper evaluation of discrete Fresnel diffraction equation is demonstrated by
creating artificial holograms and numerically reconstructing them. Simulation results and experimental work is
presented.
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