Hollow laser self-confined plasma for extreme ultraviolet lithography and other applications

Abstract

Laser-produced plasma (LPP) devices are being developed as a light source for the extreme ultraviolet (EUV) lithography applications. One concern of such devices is to increase the conversion efficiency of laser energy to EUV light. A new idea based on the initiation and confinement of cumulative plasma jet inside a hollow laser beam is developed and simulated. The integrated computer model (HEIGHTS) was used to simulate the plasma behavior and the EUV radiation output in the LPP devices. The model takes into account plasma heat conduction and magnetohydrodynamic processes in a two-temperature approximation, as well as detailed photon radiation transport in 3D Monte Carlo model. The model employs cylindrical 2D version of a total variation-diminishing scheme (for the plasma hydrodynamics) and an implicit scheme with the sparse matrix linear solver (to describe heat conduction). Numerical simulations showed that the EUV efficiency of the proposed hollow-beam LPP device to be higher than the current standard devices.