Laser produced plasma sources for nanolithography—Recent integrated simulation and benchmarking

Abstract

Photon sources for extreme ultraviolet lithography (EUVL) are still facing challenging problems to achieve high volume manufacturing in the semiconductor industry. The requirements for high EUV power, longer optical system and components lifetime, and efficient mechanisms for target delivery have narrowed investigators towards the development and optimization of dual-pulse laser sources with high repetition rate of small liquid tin droplets and the use of multi-layer mirror optical system for collecting EUV photons. We comprehensively simulated laser-produced plasma sources in full 3D configuration using 10-50 lm tin droplet targets as single droplets as well as, for the first time, distributed fragmented microdroplets with equivalent mass. The latter is to examine the effects of droplet fragmentation resulting from the first pulse and prior to the incident second main laser pulse. We studied the dependence of target mass and size, laser parameters, and dual pulse system configuration on EUV radiation output and on atomic and ionic debris generation. Our modeling and simulation included all phases of laser target evolution: from laser/ droplet interaction, energy deposition, target vaporization, ionization, plasma hydrodynamic expansion, thermal and radiation energy redistribution, and EUV photons collection as well as detail mapping of photons source size and location. We also simulated and predicted the potential damage to the optical mirror collection system from plasma thermal and energetic debris and the requirements for mitigating systems to reduce debris fluence. The debris effect on mirror collection system is analyzed using our three-dimensional ITMC-DYN Monte Carlo package. Modeling results were benchmarked against our CMUXE laboratory experimental studies for the EUV photons production and for debris and ions generation. V

Scaling mechanisms of vapour/plasma shielding from laser-produced plasmas to magnetic fusion regimes

“…These processes interplay with target thermodynamics evolution, vapour/plasma plume thermo-and hydrodynamics, and plasma radiation. Our analysis and simulations of LPP devices showed the importance of integrated self-consistent modelling of all processes involved in benchmarking actual experiments and LPP devices [7]. Modelling of target evaporation considers detailed kinetic processes on the target surface and takes into account the possibility of recondensation [11].…”

“…The HEIGHTS package includes models for 3D description of energy deposition, vapour/plasma shielding cloud formation/evolution and magnetohydrodynamic (MHD) processes, thermal conduction in material and in plasma, atomic physics processes and resulting opacities, detailed photon radiation transport (RT), and the interaction between the plasma/radiation and the target material. We extensively benchmarked and utilized the package in modelling and optimization of LPP sources for extreme ultraviolet (EUV) lithography, the current leading method for the manufacturing of next-generation computer chips [6,7]. We considered several lasers, materials and target configurations to develop efficient sources for EUV photon production.…”

“…We considered several lasers, materials and target configurations to develop efficient sources for EUV photon production. In the processes of optimization, the shielding effect of the plasma produced from small liquid tin droplets (leading target material for EUV production) and the resulting EUV source performance were investigated in great detail [7]. For example, we studied the effect of various laser parameters and wavelengths on the conversion efficiency (EUV photon yield versus incident laser energy) of such devices and found that CO 2 lasers having a longer wavelength, regardless of pulse intensity have several advantages over Nd : YAG lasers.…”

Efficient Monte Carlo Simulation of Heat Conduction Problems for Integrated Multi-Physics Applications

“…Examples include modeling of large plasma devices such as in magnetic and inertial fusion research [1], laser-produced plasma devices [2], and nuclear fission power plants [3]. This wide research area covers a range of applications basically from nanoparticle formation devices up to the hydrodynamics of star evolution.…”

Mechanisms of carbon dimer formation in colliding laser-produced carbon plasmas

“…Laser-produced plasmas (LPPs) at moderate laser intensities have garnered much interest in a diverse expanse of applications including laser induced breakdown spectroscopy (LIBS) for material composition and detection analysis, pulsed laser deposition (PLD) for thin film deposition, development of photon sources with various energies for a wide range of applications such as EUV and x-ray sources for advanced nanolithography and biomedical applications, and simulation of plasma/wall interactions during transient events in magnetic fusion reactors. [1][2][3][4][5] The research on colliding plasmas has witnessed increased interest over the past decade due to their distinct characteristics and plasma chemistry which set them apart from conventional single plume LPPs. Colliding plasmas are currently a subject of interest in several plasma fields where their unique nature can give rise to optimal conditions for nanostructure formation 6 and EUV photon emission 7,8 or can lead to hard contamination of the chamber environment in an inertial fusion device.…”