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

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.