We present a comprehensive characterization of laser-produced tin (Sn) plasmas relevant to extreme ultraviolet (EUV) lithography using a multi-diagnostic suite integrated into the new experimental platform, "SparkLight". Tin plasmas are generated by irradiating a continuously moving tin-coated wire with laser pulses (1064 nm, 10 ns, up to $5.7\times10^{10}$ W/cm$^2$) and probed via coherent Thomson scattering, laser interferometry, and EUV emission spectroscopy. Thomson scattering measurements reveal electron temperatures and densities that decay with distance from the target. Densities derived from Thomson scattering are cross-validated against laser interferometry, showing excellent agreement. Correlating the results of these laser diagnostics with spatially resolved EUV spectroscopy suggests that the bulk of useful EUV emission originates within 150 $μ$m of the target and is generated under suboptimal plasma conditions. This work demonstrates a practical integrated approach for plasma characterization in EUV source development.
The nanoparticle charging processes along with background spatial-temporal plasma profile have been investigated with 3DPIC simulation in a pulsed EUV exposure environment. It is found that the particle charge polarity (positive or negative) strongly depends on its size, location and background transient plasma conditions. The particle (100 nm diameter) charge reaches steady state in a single pulse (20 us) within the EUV beam in contrast to particles outside the beam that requires multiple pulses. The larger the particle size, the less number of pulses are required to reach steady state. It is…
Generation of high-power pulses of extreme ultraviolet radiation from multi-charged tin plasma are of great interest to many applications. We studied the electric potential distribution in the discharge gap in kind formed double layer. The local plasma heating by electron beam, formed in the double layer, leads to generation of peak radiation pulses and as a result to an increase in the radiation power.
EUV Lithography is the technology of choice for High-Volume Manufacturing (HVM) of sub-10nm lithography. One of the challenges is to enable in-situ cleaning of functional surfaces such as sensors, fiducials and interferometer mirrors without opening the scanner tool. Thermally created hydrogen radicals have been successfully used for this purpose. These sources have a limited cleaning speed and relatively high thermal load to the surface being cleaned. Here we present an alternative plasma-based technique to simultaneously create hydrogen radicals and hydrogen ions. This results in significant…
Resolving the Blueshift in Calculations of the EUV Spectrum of Multiply Charged Tin Ions
Advanced Research Center for Nanolithography (ARCNL)（先进纳米光刻研究中心）；Department of Physics and Astronomy, and LaserLaB, Vrije Universiteit Amsterdam（阿姆斯特丹自由大学物理与天文系及激光实验室）；Pawsey Supercomputing Research Centre（珀西超级计算研究中心）；School of Physics, University of New South Wales（新南威尔士大学物理学院）
In the past years, EUV lithography scanner systems have entered High-Volume Manufacturing for state-of-the-art Integrated Circuits (IC), with critical dimensions down to 10 nm. This technology uses 13.5 nm EUV radiation, which is shaped and transmitted through a near-vacuum H2 background gas. This gas is excited into a low-density H2 plasma by the EUV radiation, as generated in pulsed mode operation by the Laser-Produced Plasma (LPP) in the EUV Source. Thus, in the confinement created by the walls and mirrors within the scanner system, a reductive plasma environment is created that must be und…
We review the results of the 1st Extreme Ultraviolet (EUV) Light Sources Code Comparison Workshop, which was held online on 3rd November 2020. The goal of this workshop was to provide a platform for specialists in EUV light source plasma modeling to benchmark and validate their numerical codes using well-defined case studies. Eight institutions spanning four countries contributed data to the workshop. Two topics were addressed, namely (i) the atomic kinetics and radiative properties of tin plasmas under EUV-generating conditions and (ii) laser absorption in a fully ionized, one-dimensional hyd…
Enhanced Extreme Ultraviolet Emission from Laser-heated Blow-Off Tin Plasmas
Pacific Northwest National Laboratory（太平洋西北国家实验室）；Prism Computational Sciences（棱镜计算科学公司）；Center for Energy Research, University of California San Diego（加州大学圣地亚哥分校能源研究中心）
In the past years, EUV lithography scanner systems have entered High-Volume Manufacturing for state-of-the-art Integrated Circuits (IC), with critical dimensions down to 10 nm. This technology uses 13.5 nm EUV radiation, which is transmitted through a near-vacuum H2 background gas, imaging the pattern of a reticle onto a wafer. The energetic EUV photons excite the background gas into a low-density H2 plasma. The resulting plasma will locally change the near-vacuum into a conducting medium, and can charge floating surfaces and particles, also away from the direct EUV beam. This paper will discu…
Advanced Research Center for Nanolithography（先进纳米光刻研究中心）；Industrial Focus Group XUV Optics, MESA+ Institute for Nanotechnology, University of Twente（特温特大学MESA+纳米技术研究所XUV光学工业聚焦小组）；Department of Physics and Astronomy, and LaserLaB, Vrije Universiteit（自由大学物理与天文学系及LaserLaB实验室）；Zernike Institute for Advanced Materials, University of Groningen（格罗宁根大学泽尔尼克高级材料研究所）
Experimental spectroscopic studies are presented, in a 5.5--25.5nm extreme-ultraviolet (EUV) wavelength range, of the light emitted from plasma produced by the irradiation of tin microdroplets by 5-ns-pulsed, 2-$μ$m-wavelength laser light. Emission spectra are compared to those obtained from plasma driven by 1-$μ$m-wavelength Nd:YAG laser light over a range of laser intensities spanning approximately $0.3-5 \times 10^{11}$Wcm$^{-2}$, under otherwise identical conditions. Over this range of drive laser intensities, we find that similar spectra and underlying plasma charge state distributions ar…
Optimization of EUV output by experimentally validated radiation-hydrodynamic simulations across a broad laser parameter space
Institute of Laser Engineering, The University of Osaka（大阪大学激光工程研究所）；National Institute for Fusion Science（国立研究开发法人核融合科学研究所）；Kansai Institute for Photon Science, National Institutes for Quantum Science and Technology（量子科学技术研究机构光子科学关西研究所）；Faculty of Engineering, Osaka Metropolitan University（大阪公立大学工学部）；Center for Materials Under eXtreme Environment, (CMUXE), School of Nuclear Engineering, Purdue University（普渡大学核工程学院极端环境材料中心）；Graduate School of Advanced Science and Engineering, Hiroshima University（广岛大学先进理工学研究科）
40% boost in extreme ultraviolet conversion efficiency via simultaneous dual-beam 2-μm laser irradiation
Utsunomiya University（宇都宫大学）；RIKEN Center for Advanced Photonics, RIKEN（理化学研究所先进光子学研究中心）；The University of Tokyo（东京大学）；Tohoku University（东北大学）；University College Dublin（都柏林大学学院）；Hiroshima University（广岛大学）
The emission properties of tin plasmas, produced by the irradiation of preformed liquid tin targets by several-ns-long 2-$μ$m-wavelength laser pulses, are studied in the extreme ultraviolet (EUV) regime. In a two-pulse scheme, a pre-pulse laser is first used to deform tin microdroplets into thin, extended disks before the main (2$μ$m) pulse creates the EUV-emitting plasma. Irradiating 30- to 300-$μ$m-diameter targets with 2-$μ$m laser pulses, we find that the efficiency in creating EUV light around 13.5nm follows the fraction of laser light that overlaps with the target. Next, the effects of a…
Laser-produced plasma (LPP) induced during irradiation of a liquid tin droplet with diameter of 150 um and 180 um by CO2 laser pulse with various pulse durations and energies is considered. The two-dimensional radiative magnetohydrodynamic (RMHD) plasma code is used to simulate the emission and plasma dynamics of multicharged ion tin LPP. Results of simulations for various laser pulse durations and 75-600 mJ pulse energies with Gaussian and experimentally taken temporal profiles are discussed. It is found that if the mass of the target is big enough to provide the plasma flux required (the con…
