Theoretical EUV Spectrum of Near Pd-like Xe

author’s e-mail: [email protected] The extreme ultraviolet light source (EUVL) is being studied intensively toward its application in semiconductor technology [1]. Use of Mo/Si multilayer optics requires that the EUVL should produce emission at the 13.5 nm band with high efficiency (> 1%). Xe plasma has been considered as promising candidate, however, strong emission is usually obtained in the 11 nm band. The property of the spectrum should be understood to increase emission in the 13.5 nm band. The atomic structure of Xe ions is investigated using the HULLAC code [2]. Figure 1 shows the schematic level diagram of Xe, as representative of ions from Xe8+ to Xe15+, which have a similar level structure, with a ground configuration of 4dn. Each box in the figure indicates the configuration’s averaged state with its location and height corresponding to the averaged energy and width over the fine structure levels which belong to each configuration. The first group of excited states consists of configurations for which one electron is excited out of 4d subshell to form 4dn-1nl. The second group consists of those out of inner subshell, 4p, to form 4p54dnnl. In the case of Xe ions, the excitation energy between n = 4 and 5 shell is comparable to l-changing excitation energy within n = 4 shell. Therefore, emission lines in the transition array 4dn-14f – 4dn, 4p54dn+1 – 4p64dn, and 4dn-15p – 4dn overlap each other in the wavelength region from 10 to 18 nm. Figure 2 shows the calculated EUV emission Fig. 1 Schematic level diagram of Xe.