Study of influence of pre-pulse power on xe capillary discharge EUV source

At present, extreme ultraviolet lithograph (EUVL), which used 13.5nm (2% bandwidth) emission as the source, has been researched extensively to achieve 22nm node or even below. In this paper, we use the Al₂O₃ capillary discharge Z pinch technology to generate high density and high temperature Xe plasma and achieve Xe¹⁰⁺ 13.5nm emission. By comparing the discharge current and the spectra for main-pulse power discharge and pre-main-pulse power discharge respectively under the different discharge voltage and Xe flow rate, we analysis the influence of the pre-pulse power on the Xe plasma EUV emission and the discharge stability. The results show that the pre-pulse power can increase the discharge stability. Although the spectra are basically the same as that by main-pulse power only. The Xe gas cannot be broken down under the flow rate of 7.0sccm by main-pulse power only. And the gas pressure is too high to generate enough 13.5nm emission. On the other hand, for pre-main-pulse power, the Xe gas can be breakdown even the gas flow rate is decreased to 0.2sccm. The results show that the optimum flow rate of Xe to generate 13.5nm emission is 0.4sccm.