Lifetime Calculations on Collector Optics from Laser Plasma Extreme Ultraviolet Sources with Minimum Mass

Abstract

An ion flux and its kinetic energy spectrum are obtained using a self similar spherically symmetric fluid model of expansion of a collisionless plasma into vacuum. According to the ion flux and energy distribution, the collector optical lifetime is estimated by knowledge of the sputtering yield of conventional Mo/Si multilayer coatings for the CO2 and Nd:YAG pulsed-laser produced plasmas based on the minimum mass tin droplet target without debris mitigation. The results show that the longer wavelength of the CO2 laser produced plasma light source is more suitable for extreme ultraviolet lithography than Nd:YAG laser in respect of fast ion debris induced sputtering damage to the collector mirror.

Time and space resolved visible spectroscopic imaging CO2 laser produced extreme ultraviolet emitting tin plasmas

“…Recently, much effort has been devoted to developing an efficient and clean laser produced plasma (LPP) light source at 13.5 nm for next generation extreme ultraviolet (EUV) lithography in the semiconductor industries. [1][2][3] The strong unresolved transition arrays of tin centered near 13.5 nm offer a promising source of EUV radiation for the next generation of lithography. [4][5][6][7] Therefore, measurements of the plasma density and temperature are essential in order for us to obtain a better understanding of the tin plasma behavior over time and space, which is one of the keys to successfully producing the radiation source, as well as offering a reference for numerical simulations used to study and optimize these phenomena.…”