Next Generation Debris-Free EUV Source using Fast Z-pinch Discharge in Cylindrical Gas Curtain

为了开发高质量、高输出功率的新一代无碎屑极紫外线(EUV)光源，本研究的目标确定为：1.提高从电能存储到EUV发射的能量转换效率；2.抑制碎屑产生；3.开发不干扰放电气流的碎屑屏蔽，以缓解上述方法无法清除的碎屑。由于通常的Z-Pinch放电头部采用绝缘壁，因此碎屑是由壁材产生的。因此，为了防止碎片的产生，已经拆除了绝缘墙，并打算沿径向收集EUV。利用光谱仪，从杂质谱线的显著减少中证实了碎片产生的抑制。此外，特别设计的圆柱形气幕被发现具有放电气体限制功能，这是一开始并不假设的。杂散…前者的多电感很大，不可能获得大的放电电流。然后，对电路设计进行了重新检查。为了最大限度地降低放电电路末级的杂散电感，采用了LC反相发生器和两级磁脉冲压缩(MPC)电路。实验测得的短路电流幅值为22kA，脉宽为260 ns。此外，为了提高电输入到极紫外光发射的转换效率，建立了一种利用射频放电产生等离子体射流的装置，按照原方案，尝试使用射频预电离等离子体射流进行Z-Pinch放电。结果发现，在使用射频预电离射流的情况下，由于腔内充满了弱电离等离子体，放电发生在等离子体射流以外的其他地方。因此，在这种情况下不能获得Z箍缩等离子体。为了保持腔室内部的高真空度，用涡轮分子泵抽真空，而不是用来作为扩散器，现在我们正在努力改善腔室的真空状态。较少

To develop a next generation debris-free extreme ultraviolet (EUV) source with high quality and high output power, the objectives of this study were decided as follows: 1. increase energy conversion efficiency from electrical energy storage to EUV emission, 2. suppress the debris generation, 3. develop a debris shield, which does not interfere the discharge gas flow, to mitigate the debris that cannot be removed by the above mentioned method.Since the usual Z-pinch discharge head employs an insulating wall, debris is generated from the wall material. Therefore, in order to prevent the debris from generating, the insulating wall has been removed and the EUV has been intended to be collected in the radial direction. Using a spectrometer, suppression of debris generation was confirmed from the remarkable reduction of impurity lines. In addition, the specially designed cylindrical gas curtain was found to have a discharge gas confinement function, which was not supposed at first.The stray … More inductance of the former device was very large and it was impossible to get large discharge current. Then, the circuit design was re-examined. To reduce the stray inductance in the final stage of discharge circuit as much as possible, an LC inversion generator and a two-stage magnetic pulse compression (MPC) circuit have been adopted. Experimentally obtained current has the amplitude of 22 kA and the pulse width of 260 ns for short-circuit. Moreover, to increase the conversion efficiency from the electrical input to EUV emission, a device which generates a plasma jet by using RF discharge was set.According to the original plan, Z-pinch discharge was tried using the RF preionized plasma jet. As a result, it was found that in case of using RF preionized jet since the chamber was filled with weakly ionized plasma and discharge occurred at other place other than the plasma jet. Therefore, no Z-pinch plasma could be obtained in this case. To keep the inside of chamber high vacuum, using the turbo molecular pump to evacuate the chamber instead of using it for the diffuser, we are now trying to improve the vacuum state in the chamber. Less