Extreme ultraviolet (EUV) discharge-based lamps for EUV lithography need to generate extremely high power in the narrow spectrum band of 13.5±0.135 nm. A simplified collisional-radiative model and radiative transfer solution for an isotropic medium were utilized to investigate the wavelength-integrated light outputs in tin (Sn) plasma. Detailed calculations using the Hebrew University-Lawrence Livermore atomic code were employed for determination of necessary atomic data of the Sn4+ to Sn13+ charge states. The result of model is compared with experimental spectra from a Sn-based discharge-produced plasma. The analysis reveals that considerably larger efficiency compared to the so-called efficiency of a black-body radiator is formed for the electron density ≃1018 cm−3. For higher electron density, the spectral efficiency of Sn plasma reduces due to the saturation of resonance transitions.

Extreme ultraviolet (EUV) discharge-based lamps for EUV lithography need to generate extremely high power in the narrow spectrum band of 13.5±0.135 nm. A simplified time-dependent collisional-radiative model and radiative transfer solution were utilized to investigate the wavelength-integrated Lyman-α line light outputs in a hydrogen-like lithium ion. The study reveals in particular that a steady-state or magnetically confined lithium plasma radiates in the desired spectrum band not less than 1 kW in 2π sr even at an ion density region as low as 1017 cm−3.

Articles you may be interested inA point-like source of extreme ultraviolet radiation based on a discharge in a non-uniform gas flow, sustained by powerful gyrotron radiation of terahertz frequency band High conversion efficiency mass-limited Sn-based laser plasma source for extreme ultraviolet lithography

There is increasing interest in extreme-ultraviolet (EUV) laser-based lamps for sub-10-nm lithography operating in the region of 6.6 nm. A collisional-radiative model is developed as a post-processor of a hydrodynamic code to investigate emission from resonance lines in Kr, Gd, and Tb ions under conditions typical for mass-limited EUV sources. The analysis reveals that maximum conversion efficiencies of Kr occur at 5×1010W/cm2, while for Gd and Tb it was ≃0.9%/2πsr for laser intensities of (2−5)×1012W/cm2.

In connection with fast heating in a laser produced plasma (LPP) extreme ultraviolet (EUV) source, the superheating behavior of bulk tin (Sn) at high heating rates is investigated. A constant temperature and pressure molecular dynamics simulation using modified Lennard-Jones and Coulomb potentials suitable for studying the liquid structure of Sn is employed in order to derive the caloric curves of the solid and liquid phases. The results have shown transient effects on the phase transitions. Superheating is observed during the melting and vaporizing processes. The velocity distribution of Sn particles against typical laser fluence in a LPP EUV light source has been numerically investigated using a simplified method including a one-dimensional, two-temperature, molecular dynamics, and steady-state ionization model. In the framework of our model, it was found that ejected Sn particles have a maximum velocity on the order of 10 to 40 km/ s in plasma created using a nanosecond pre-pulse neodymium-doped yttrium aluminum garnet (Nd:YAG, 1.06 lm) laser in EUV lithography experiments. V