High-space resolution imaging plate analysis of extreme ultraviolet (EUV) light from tin laser-produced plasmas

Christopher S A Musgrave; Takehiro Murakami; Teruyuki Ugomori; Kensuke Yoshida; Shinsuke Fujioka; Hiroaki Nishimura; Hironori Atarashi; Tomokazu Iyoda; Keiji Nagai

doi:10.1063/1.4978526

High-space resolution imaging plate analysis of extreme ultraviolet (EUV) light from tin laser-produced plasmas

Rev Sci Instrum. 2017 Mar;88(3):033506. doi: 10.1063/1.4978526.

Authors

Christopher S A Musgrave¹, Takehiro Murakami¹, Teruyuki Ugomori², Kensuke Yoshida², Shinsuke Fujioka², Hiroaki Nishimura², Hironori Atarashi¹, Tomokazu Iyoda¹, Keiji Nagai¹

Affiliations

¹ Iyoda Supra-Integrated Material Project, Exploratory Research for Advanced Technology (ERATO), Japan Science and Technology Agency, and Frontier Research Center, Tokyo Institute of Technology, 4259-S2-3 Nagatsuta, Midori-ku, Yokohama 226-8503, Japan.
² Institute of Laser Engineering, Osaka University, 2-6 Yamada-Oka, Suita, Osaka 565-0871, Japan.

PMID: 28372444
DOI: 10.1063/1.4978526

Abstract

With the advent of high volume manufacturing capabilities by extreme ultraviolet lithography, constant improvements in light source design and cost-efficiency are required. Currently, light intensity and conversion efficiency (CE) measurments are obtained by charged couple devices, faraday cups etc, but also phoshpor imaging plates (IPs) (BaFBr:Eu). IPs are sensitive to light and high-energy species, which is ideal for studying extreme ultraviolet (EUV) light from laser produced plasmas (LPPs). In this work, we used IPs to observe a large angular distribution (10°-90°). We ablated a tin target by high-energy lasers (1064 nm Nd:YAG, 10¹⁰ and 10¹¹ W/cm²) to generate the EUV light. The europium ions in the IP were trapped in a higher energy state from exposure to EUV light and high-energy species. The light intensity was angular dependent; therefore excitation of the IP depends on the angle, and so highly informative about the LPP. We obtained high-space resolution (345 μm, 0.2°) angular distribution and grazing spectrometer (5-20 nm grate) data simultaneously at different target to IP distances (103 mm and 200 mm). Two laser systems and IP types (BAS-TR and BAS-SR) were also compared. The cosine fitting values from the IP data were used to calculate the CE to be 1.6% (SD ± 0.2) at 13.5 nm 2% bandwidth. Finally, a practical assessment of IPs and a damage issue are disclosed.