Heights simulation and optimization of laser produced plasma EUV sources

Summary form only given. Advanced lithography in the development of next generation computer chips are based on production of EUV and beyond EUV photon radiation. Plasma sources for these photons emission are created using laser beams irradiating solid or liquid matter in different configurations, i.e., plates, droplets, and jets. Optimizing laser produced plasma (LPP) devices includes maximizing conversion efficiency (CE) of laser energy to the EUV photons output, EUV source size to provide efficient photons collection by mirrors system, and protection of the optical system from damage by debris. We utilized our HEIGHTS package to model in full 3D the complex processes involved in producing the 13.5 nm photons. The developed models address and integrate several major areas: laser absorption in target materials, vapor/plasma evolution and magneto hydrodynamic (MHD) processes, thermal conduction in material and plasma, atomic physics and plasma opacities, detailed photon transport, and interaction between plasma/radiation and target material in full 3D target geometry. The design of the existing multilayer Mo/Si mirrors system determines the maximum possible size of EUV source. While usually LPP devices provide small source sizes that satisfy optical etendue system requirements, CO₂ laser systems with large spot size and long pulse duration may impose difficulty in EUV photons collection. The Monte Carlo model for radiation transport in HEIGHTS package permits to determine the detail spatial and temporal evolution of the location and intensity of EUV photons source. We analyzed and optimized EUV source size, location, and intensity for various laser beam parameters such as laser wavelength, intensity, pulse duration, and beam spot size. We predicted that the differences in hydrodynamic evolutions and geometrical confinement processes are the main cause for the differences in the CE between the planar and spherical targets, and the influence of this effect- on EUV source size.