부산대학교 도서관

Study on coupling source from three plasmas in capillary discharge opens up an alternative way for large-scale industrial production of extreme ultraviolet lithography. Based on the coupling mechanism of three plasmas in capillary tube, partial coupling parameters are calculated. It is found from experimental results that the average optical power of the coupling source is increased by ~1.2 times, and up to 1.7 times compared to that of the uncoupling source when the working pressure of N_2 is initially set at 30 Pa, this results in an average magnification factor of ~3.6 with the maximum of 5.1 and an average energy coupling efficiency of ~18% with the maximum of 41%. Further more, when the working pressure is adjusted at 90 Pa, the average optical power, magnification factor and energy coupling efficiency of the coupling source are improved by ~1.4 times, ~4.2 and ~28% respectively, corresponding to their maximums of 2.1 times, 6.3 and 52%. A higher working pressure (no more than the optimal breakdown pressure of N_2) produces a higher energy coupling efficiency, and this comes from the fact that more particles can absorb the energy of laser pulse in the coupling zone to intensify the ability of 'expansion outward' at the higher pressure so that the annulus emitting plasma is expanded. In a word, the extreme ultraviolet coupling source from three plasmas in capillary discharge has been realized for the first time, and raising the working pressure is beneficial for the energy coupling efficiency.