Auto-cleaning of deposited tin debris in a laser-produced plasma extreme ultraviolet source by using a liquid jet target containing tin chloride

Abstract

We have demonstrated auto-cleaning of deposited tin debris produced in a laser-plasma extreme ultraviolet (EUV) source by using a liquid jet target containing tin chloride solution. The use of double laser pulse irradiation improved the EUV conversion efficiency of 1.1%, which was 3.3 times as large as that obtained with single laser pulse irradiation. At an appropriate concentration of tin chloride, the amount of deposited debris was balanced out with that of sputtered and/or etched debris, resulting in a thickness of deposited debris less than 1 nm after 40 000 laser pulse irradiations.