Time exposure performance of Mo-Au Gibbsian segregating alloys for extreme ultraviolet collector optics
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Successful implementation of extreme ultraviolet (EUV) lithography depends on research and progress toward minimizing collector optics degradation from intense plasma erosion and debris deposition. Thus studying the surface degradation process and implementing innovative methods, which could enhance the surface chemistry causing the mirrors to suffer less damage, is crucial for this technology development. A Mo-Au Gibbsian segregation (GS) alloy is deposited on Si using a dc dual-magnetron cosputtering system and the damage is investigated as a result of time dependent exposure in an EUV source. A thin Au segregating layer is maintained through segregation during exposure, even though overall erosion in the Mo-Au sample is taking place in the bulk. The reflective material, Mo, underneath the segregating layer is protected by this sacrificial layer, which is lost due to preferential sputtering. In addition to theoretical work, experimental results are presented on the effectiveness of the GS alloys to be used as potential EUV collector optics material.Keywords:
Extreme Ultraviolet Lithography
Extreme ultraviolet
Ultraviolet
Degradation
X-ray optics
Optical coating
Extreme ultraviolet (EUV) photoresists are known to outgas during exposure to EUV radiation in the vacuum environment. This is of particular concern since some of the outgassed species may contaminate the nearby EUV optics and cause a loss of reflectivity and therefore throughput of the EUV exposure tools. Due to this issue, work has been performed to measure the species and quantities that outgas from EUV resists. Additionally, since the goal of these measurements is to determine the relative safety of various resists near EUV optics, work has been performed to measure the deposition rate of the outgassed molecules on Mo/Si-coated witness plate samples. The results for various species and tests show little measurable effect from resist components on optics contamination with modest EUV exposure doses.
Extreme Ultraviolet Lithography
Extreme ultraviolet
Outgassing
Optical coating
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An experimental setup that directly reproduces extreme ultraviolet (EUV) lithography relevant conditions for detailed component exposure tests is described. The EUV setup includes a pulsed plasma radiation source, operating at 13.5 nm; a debris mitigation system; collection and filtering optics; and an ultra-high vacuum experimental chamber, equipped with optical and plasma diagnostics. The first results, identifying the physical parameters and evolution of EUV-induced plasmas, are presented. Finally, the applicability and accuracy of the in situ diagnostics is briefly discussed.
Extreme Ultraviolet Lithography
Extreme ultraviolet
Vacuum chamber
Ultraviolet
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The cosiderable progress in the development of extreme ultraviolet (EUV) sources such as laser-produced plasma, discharge-produced plasma, high-harmonic generation, X-ray laser, Synchrotron radiation, X-ray free electron laser will create new scientific research field and new industrial technology field. These EUV sources research have also led to progress in the development of EUV optical devices such as multilayer mirrors. This paper reviews the briefly history and recent results of multilayer optics for EUV.
Extreme Ultraviolet Lithography
Extreme ultraviolet
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The Mo/Si multilayer mirrors used for extreme ultraviolet (EUV) lithography can become contaminated during exposure in the presence of some hydrocarbons [1-3]. Because this leads to a loss in the reflectivity of the optics and throughput of the exposure tools, it needs to be avoided. Since photoresists are known to outgas during exposure to EUV radiation in a vacuum environment, the careful choice of materials is important to preserving the EUV optics. Work therefore has been performed to measure the species and quantities of molecules that outgas from EUV resists when exposed to EUV radiation [4-7].
Extreme Ultraviolet Lithography
Outgassing
Extreme ultraviolet
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Extreme Ultraviolet Lithography
Extreme ultraviolet
Ultraviolet
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The absorption of extreme-ultraviolet (EUV) pellicle could be the most critical problem because the EUV source power is still not good enough for achieving mass production. We found that the transmission loss due to the EUV pellicle could be compensated through proper optical proximity correction (OPC) of a pellicled mask. Patterning results of OPCed masks with different transmission pellicles are shown for various 1D and 2D patterns. From the results, it is clearly shown that we do not need to increase the dose to avoid the throughput loss even if a pellicle which has 80 % one-pass transmission is used. Therefore, the EUV pellicle manufacturing would be much easier because we can use much thicker film with higher absorption.
Extreme Ultraviolet Lithography
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Realization (probability)
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Scatterometry, the analysis of light diffracted from a periodic structure, is a versatile metrology for characterizing periodic structures, regarding critical dimension (CD) and other profile properties. For extreme ultraviolet (EUV) masks, only EUV radiation provides direct information on the mask performance comparable to the operating regime in an EUV lithography tool. With respect to the small feature dimensions on EUV masks, the short wavelength of EUV is also advantageous since it increases the sensitivity for small structural details. Measurements using PTB's EUV reflectometer at the storage ring BESSY II showed that it is feasible to derive information on the absorber line profile in periodic areas of lines and spaces by means of rigorous numerical modeling with the finite element method (FEM). A prototype EUV mask with fields of nominally identical lines was used for the measurements. In this contribution we correlate the scatterometry data to CD-SEM and surface nano probe measurements of the line profiles as provided by the mask supplier. We discuss status of the determination of CD and side-wall geometry by scatterometry using rigorous FEM calculations of EUV diffraction and directions for further investigations.
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We have demonstrated a hybrid extreme ultraviolet (EUV) multilayer mirror for 6.x nm radiation that provides selective suppression for infrared (IR) radiation. The mirror consists of an IR-transparent LaN∕B multilayer stack which is used as EUV-reflective coating and antireflective (AR) coating to suppress IR. The AR coating can be optimized to suppress CO2 laser radiation at the wavelength of 10.6 μm, which is of interest for application in next-generation EUV lithography systems.
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Extreme ultraviolet
Anti-reflective coating
Optical coating
Ultraviolet
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We present our results of coating a first set of optical elements for an extreme-ultraviolet (EUV) lithography system. The optics were coated with Mo-Si multilayer mirrors by dc magnetron sputtering and characterized by synchrotron radiation. Near-normal incidence reflectances above 65% were achieved at 13.35 nm. The run-to-run reproducibility of the reflectance peak wavelength was maintained to within 0.4%, and the thickness uniformity (or gradient) was controlled to within ±0.05% peak to valley, exceeding the prescribed specification. The deposition technique used for this study is an enabling technology for EUV lithography, making it possible to fabricate multilayer-coated optics to accuracies commensurate with atomic dimensions.
Extreme Ultraviolet Lithography
Extreme ultraviolet
Optical coating
X-ray optics
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Extreme ultraviolet (EUV) radiation from laser-produced plasma has been studied for mass-production of the next generation semiconductor devices with EUV lithography. A full set of experimental databases are provided for a wide range of parameters of lasers and targets. These data are utilized directly as a technical guide-line for EUV source system design in the industry as well as used to benchmark the radiation hydrodynamic code, including equation-of-state solvers and advanced atomic kinetic models, dedicated for EUV plasma predictions. Present status of the LPP EUV source studies is presented.
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