EUV光刻机光源靶滴喷射精密控制的基础研究

极紫外（EUV）光刻是面向7nm以下线宽大规模集成电路制造的最新一代光刻技术，其光源采用激光等离子放电原理，以高能激光束轰击锡液靶滴使其等离子化释放极紫外光。目前，EUV光源仍面临能量转换效率低、输出功率受限、碎屑污染导致可靠性差等棘手问题，提升靶滴喷射性能与质量是解决上述问题的基础，其关键在于创新靶滴喷射控制方法，降低对喷射源与激振源稳定性的依赖。为此，本项目拟开展EUV光刻机光源靶滴喷射精密控制的基础研究，揭示靶滴行为规律以及引发尺寸、位置、形态等误差的流体力学机理，进而在射流瑞利失稳断裂成液滴的基础上进一步创新靶滴控制方法，实现靶滴生成质量的主动控制与位姿形态的外场控制，提升靶滴喷射性能与质量。通过上述研究为EUV光源及光刻机整机性能与可靠性的提升提供新思路，同时为下一阶段国产EUV光刻机的自主研制提供基础。

Extreme ultraviolet (EUV) lithography is a new technology used for manufacture of large-scale integrated circuit with line-width below 7nm. Its light source adopts laser-produced-plasma (LPP) method to produce EUV light for exposure process, i.e. vaporizing and heating the tin (Sn) droplets into plasma clouds by pulsed-laser ablation and during this process the EUV light will be emitted. By now, the EUV light source still can not fulfill the lithography requirement well, due to its limited low energy conversion efficiency and output power as well as its frequent maintenance requirement caused by Sn debris contamination. Improving the performance of Sn droplet generator is required to solve above problems, for which more effective flow control methods should be proposed to reduce the extremely high requirement of the stability of the liquid Sn jetting and the vibration exciting sources. This project will focus on the fundamental research about the precise control method of Sn droplets jet for EUV light source. The droplet behavior during whole process of generation and flying will be investigated firstly, based on which we hope to explain the reasons causing the size, position and morphology errors of the droplets well from the aspect of fluid mechanics. Then, new droplet control approaches will be proposed to improve the traditional droplets generation method which is based on jet breakup caused by Rayleigh instability. Active control method based on multiple excitement sources will be developed to improve the droplets generation quality. Additional physical field will be utilized to control the space pose and morphology of the droplets after jetted. We hope to provide support in theoretical basis and technical innovation for the improvement of EUV light sources and lithography machine performances, especially to provide base for the self-development of EUV lithography machine in China.