| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide an EUV (extreme ultraviolet) radiation source employing a laser prepulse of a low energy just before a laser main pulse of a high energy. <P>SOLUTION: The prepulse generates a weak plasma in a target area, and improves laser absorption of the laser main pulse to improve a radiation emission in EUV radiation. An ion flux of high energy is reduced by collision in a localized target vapor cloud generated by the prepulse. The prepulse of low energy reaches the target area before 20-200ns compared with the main pulse for obtaining the maximum output intensity. The timing between the prepulse and the main pulse can be reduced below 160ns to provide a lower intensity of the EUV radiation. In one embodiment, the prepulse is split from the main pulse by a beam splitter having a proper beam intensity ratio, and the main pulse is delayed to arrive at the target area after the prepulse. <P>COPYRIGHT: (C)2005,JPO&NCIPI |
