【作者】 徐强；

【导师】 李琦； 赵永蓬；

【作者基本信息】 哈尔滨工业大学 ， 物理电子学， 2014， 博士

【摘要】 为了实现更小特征尺寸的集成电路，采用更短曝光波长的下一代光刻技术被提出来。极紫外(EUV)光刻相比其他下一代光刻技术，在光学光刻技术上的延续性较好，是目前发展的一种主要技术方案。根据实际应用需求，目前极紫外光刻光源主要沿着两条路线发展：满足大规模工业生产需求的高功率、高重复频率光源；用于光刻机中光学系统、掩膜版、光刻胶等系统检测用的中小功率光源。后者要求光源具有较高的功率稳定性和适中的光源功率，同时要求光源结构简单、工作成本较低。毛细管放电Z箍缩Xe等离子体EUV光源具有结构较为简单、稳定性好、收集效率较高等优点，是目前实现检测用的中小功率光源主要技术方案之一。关于毛细管放电Z箍缩Xe等离子体EUV光源，系统的机理研究、良好的放电结构和工作参数，是实现功率较高、稳定性良好的13.5nm(2%带宽)辐射光输出的关键。围绕这一目标，本文开展了EUV光源理论分析、实验装置的改造、EUV光源实验研究和1kHz光源设计及建造等四方面的研究工作，以实现较高功率和稳定性的13.5nm(2%带宽)辐射光输出。在理论方面，本文采用Cowan程序计算了Xe离子能级参数。采用碰撞-辐射模型模拟了不同条件下等离子体中不同价态离子丰度分布。根据离子能级参数和丰度分布计算结果，考虑谱线展宽的影响，结合离子丰度分布计算结果，模拟了不同条件下辐射光谱的变化。采用雪耙模型模拟了毛细管放电Xe等离子体EUV光源中的Z箍缩过程，分析了箍缩过程中存在的多次箍缩效应。同时，深入分析了不同电流、气压和毛细管内径等参数，对等离子体Z箍缩过程的影响。结合光学收集系统相关参数，计算了不同毛细管内径和等离子体长度对收集效率和中间焦点处功率的影响。毛细管放电Z箍缩Xe等离子体EUV光源实验装置，主要包括电源系统、放电系统、充配气系统、真空系统、探测系统等五部分。本文针对光源工作中出现的问题做出了相应的改进，以满足放电过程中实现较高功率和稳定性的极紫外辐射的要求。改造后的结构可以实现等离子体的有效箍缩，实现了EUV辐射光输出。实验上，系统地研究了预脉冲放电对辐射光谱和光源的时间及功率稳定性的影响，为后续采用预-主脉冲联合放电提供了实验依据。在此基础上，结合理论分析，系统地研究了主脉冲电流幅值、Xe气流量、毛细管内径、辅助气体和等离子体长度等参数对Xe等离子体EUV光谱的影响，优化了上述实验参数。详细的测量了各种实验参数对13.5nm(2%带宽)辐射信号时间特性的影响，深入分析了毛细管放电Z箍缩Xe等离子体EUV光源物理机制。实验发现大电流、低气压时13.5nm(2%带宽)辐射信号时间特性存在多个峰值，但目前国际上并没有系统的研究和解释，本文结合理论模拟，证实了多峰现象来源于等离子体的多次箍缩。Xe气中掺入He气可以提高13.5nm(2%带宽)辐射强度，本文通过在Xe气中掺入不同比例He气，优化了He与Xe的流量比，并对比掺入He、Ne和Ar等气体时的光谱及13.5nm(2%带宽)时间特性，解释了掺入He气提高13.5nm(2%带宽)辐射强度的物理机制。在前期实验和理论研究的基础上，设计建造了一套1kHz毛细管放电Z箍缩Xe等离子体EUV光源，主要包括电源系统、放电系统、充配气系统、真空系统、探测系统、冷却系统、光学收集系统和去碎屑系统等。独立测试了各关键部件的性能，测试结果表明，均基本满足设计指标和实验要求。完成了系统的集成，并在单脉冲和重复频率条件下Xe气放电，实现了13.5nm辐射光输出，优化了Xe气流量和掺入He气比例。更多还原

【Abstract】 In order to get much smaller feature for the ICs, the technology of next generation lithography(NGL) has been put forward. Comparing with other technologies, the extreme ultraviolet(EUV) lithograph technology, which has better continuity in the optical lithography, is one of the most important technologies. According to the requirements, the EUV source has been developed along two ways. One way is to develop a high power and high repetition frequency source, which is used to satisfy the high volume manufacturing requirements. And the other way is to build a moderate power test source to detect the collectors, mask and photosensitive resist. The latter source requires more steady, moderate power, simple and cheap. And the EUV source of Z-pinch xenon plasma pumbed by capillary discharge, which has the advantages of simple structure, steady power, high collection efficiency and so on, is one of the key technology as the test source.For a capillary discharge Z-pinch Xe plasma EUV source, systemic researches about mechanism, better discharge structures and parameters are the key factors to achieve high power and better stability13.5nm(2%bandwidth) emission. In order to achieve high power and high stability13.5nm(2%bandwidth) emission, the theoretical researches, experimental equipment improvements, experimental researches, as well as the design and building of the1kHz EUV source have been studied in this paper.Theoretically, the energy level parameters of Xe ions have been calculated with the Cowan code. The abundances of different valences for Xe ions under different conditions have been calculated by the collision-radiation model as well. According to the upper results, the emission spectra under different conditions have been simulated in consideration of the broadening of spectral line. Moreover, the pinch processes of Xe plasma in the capillary under different discharge current and Xe pressure, have been simulated with the snow-plow model. And the multi-pinch process has been studied as well. In combination with the experimental results, the effect of the discharge current, Xe pressure and the inner diameter of capillary on the pinch processes have been analyzed. In addition, the influence of the nner diameter of capillary and plasma length on the collection efficiency and power at the intermediate focus have been calculated in consideration of the parameters of the collectors.The EUV source of Z-pinch xenon plasma pumbed by capillary discharge mainly consists of five parts: the power system, discharge system, gas system, vacuum system and detection system. The problems which existed in the source have been improved to satisfy the requirements for high power and high stability.The effective pinch of plasma and EUV radiation have been realized with the rebuilt structure. Experimentally, the effect of the pre-pulse on the EUV sepctra, the time and power stabilities have been studied systemically. Based on the experimental results, the pre discharge and main discharge were used in the latter experiments. In order to optimize the value of the main current, flow rate of Xe, inner diameter of the capillary, the assist gas and the length of the plasma, the effects of these parameters on the spectra and the plasma state of the EUV source have been studied scientifically. Moreover, The physical mechanism of the EUV source of Z-pinch xenon plasma pumbed by capillary discharge have been studied by detection the effects of these parameters on the temporal evolution of the13.5nm(2%bandwidth) emission. The results show that there are multi-peaks for the temporal evolution of the13.5nm(2%bandwidth) emission under high current and low Xe pressure. However, there are little researches and analysis about the phenomena. Moreover, it can be founded that the13.5nm(2%bandwidth) emission intensity can be increased by mixing Xe with He. The optimum mixing ratio has been got. By comparing the spectra and temporal evolution of the13.5nm(2%bandwidth) emission under different He: Xe mixing ratio and the Xe/Ne, Xe/Ar mixture, the physical mechanism that mixing Xe with He can increase13.5nm(2%bandwidth) emission intensity has been interpreted.According to the upper researches, an1kHz capillary discharge Z-pinch EUV source has been built, which includes the power system, the discharge system, the pumped gas system, the vacuum system, the detection system, the cooled system, the collectors and the debris mitigation tool. The performance for each component has been tested. The results show that all of them can basically meet the design index and experimental requirements. The13.5nm emission under monopulse and frequency condition, the optimum Xe flow rate and He: Xe ratio have been got with the integrated1kHz EUV source.更多还原