Gigaphoton Inc. presents a Sn-LPP EUV light source for mask inspection tools. This light source uses a minimum-mass Sn droplet generator with an in-line Sn fuel supply system, a double-pulse laser irradiation scheme with precise shooting control and a debris mitigation technology with H2 buffer-gas flow. During 1500 hours of continuous operation, a brightness of 120W/mm2 sr at the plasma point, a stable EUV energy 3σ-value below 5% and a high availability of 99% have been obtained without reflectivity degradation of the EUV collector mirror. We are currently developing key components for higher repetition rate to further increase the brightness.
With the full-scale adoption of EUV exposure tools, the use of Metrology and Inspection systems adapted for EUV process evaluation is increasing. In particular, with the increased durability of Pellicle, the importance of actinic Metrology and Inspection systems is increasing, and EUV light sources with high brightness and high availability are required. Gigaphoton Inc. has been developing laser-produced plasma (LPP) EUV light sources using Sn droplet technology for exposure tool since 2000. Based on this accumulated LPP EUV source technology, we have developed a High-brightness and compact LPP EUV source for Metrology and Inspection systems. This newly developed light source is a SoCoMo (Source Collector Module) EUV light source with a built-in reflective mirror based on customer specifications. In addition, it features stable operation and a one-year maintenance-free structure, contributing to longterm stable operation of the inspection equipment. Currently this EUV light source has demonstrated a brightness of 120W/mm2sr at the plasma point at a repetition frequency of 20kHz without any decrease in reflectivity of the EUV collector mirror after 500 hours of operation.
Gigaphoton Inc. presents a Sn-LPP EUV light source for mask inspection tools. It is based on a minimum-mass Sn droplet generator with an in-line Sn fuel supply system, a double-pulse laser irradiation scheme with precise shooting control and a debris mitigation technology with H2 buffer-gas flow. A brightness of 120W/mm2 sr at the plasma point without reflectivity degradation of the EUV collector mirror after 500 hours continuous operation has been demonstrated with a very low EUV energy 3σ-value of 5%.
We report the development progress of key technologies for the Sn-LPP (Laser-produced-plasma) EUV light source system at Gigaphoton Inc. EUV light source systems have come to be used for a wide range of applications such as lithography exposure tools and inspection tools. In both applications, high power and high radiance together with high operation availability are required. To meet these requirements, we developed and optimized a long lifetime droplet generator, a pre-pulse irradiation scheme, laser-droplet shooting control and debris mitigation with hydrogen gas for lifetime extension of the EUV collector mirror. To achieve high operation availability, the collector mirror and the Sn droplet generator lifetime are the most important contributions. The collector mirror lifetime is mainly determined by the reflectivity degradation due to sputtering, implantation, and deposition by Sn ions, Sn atoms, Sn fragments, and hydrogen-induced blisters. The developed droplet generator with in-line Sn fuel feed system has demonstrated stable droplet generation for more than 1,300 hours in our EUV light source. An advanced pre-pulse technology achieved higher CE without increasing the energy of the Sn plasma. Our Sn mitigation scheme works efficiently for lower energy ions and lower fragment deposition rates. Our optimized in-situ shooting control system improved the EUV energy and dose error. With these technologies, we have demonstrated no reflectivity degradation (i.e. no fragment deposition) on EUV sample mirrors after 25 Billion pulse irradiation tests. The advanced capping layer has demonstrated to suppress blister formation.
Chipmakers have used cross-platform of both EUV exposure and ArF immersion multi-patterning exposure depending on cost effectiveness at each layer. ArF immersion exposure has been required lower linewidth roughness(LWR) to reduce cross matched machine overlay(xMMO) which is the overlay between the different platforms. ArF light sources essentially produce speckle as non-uniform intensity distribution resulting from interference effects generated within a beam. It leads to increase LWR, which results in increasing xMMO. The latest ArF immersion light source, GT66A is introduced a new optical pulse stretcher(OPS) that increases pulse duration to reduce speckle by 30% to improves LWR, which reduces xMMO. This technology will improve chip yield for chipmakers in the processes mixed ArF immersion exposure and EUV exposure.
Gigaphoton Inc. is developing a laser produced plasma (LPP) extreme ultra violet (EUV) light source for high-volumemanufacturing (HVM) semiconductor lithography. Original technologies and key components of this source include a high-power carbon dioxide (CO2) laser with 15ns pulse duration, a short wavelength solid-state pre-pulse laser with 10ps pulse duration, a highly stabilized small droplet (DL) target, a precise laser-DL shooting control system and debris mitigation technology with a magnetic field. In this paper, an update of the development progress of the total system and of the key components is presented.
Gigaphoton Inc. is developing a CO2-Sn-LPP EUV light source based on unique and original technologies including a high power CO2laser with 15 nanosecond pulse duration, a solid-state pre-pulse laser with 10 picosecond pulse duration, a highly stabilized droplet generator, a precise laser-droplet shooting control system and a debris mitigation system using a magnetic field. In this paper, an update of the development progress of our 250W CO2-Sn-LPP EUV light source and of the key components is presented.
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