氟化物准分子激光器电极中非主量元素参与的腐蚀机制研究

Fluoride excimer laser is one of the most effective ultraviolet band devices, but fluoride media are strongly corrosive to the material. The electrodes are an important part of the laser, their corrosion under the action of fluoride media and plasma may cause deformation of the section and generate harmful substances. This would affect the laser output energy and stability, limit the performance and application of the laser. But the exact corrosion mechanism and the influence factors of the electrodes are unknown. Preliminary experiments show that after corrosion, a reefing layer concentrated with Al, Fe, F and other elements would cover unevenly on the surface of the anode, particles rich in Zn, Fe and other elements would cover the surface of the cathode. This indicates that the non-main element participates in the corrosion. Therefore, we will use the advanced technical methods such as inductively coupled plasma mass spectrometry (ICP-MS), time of flight secondary ion mass spectrometry (TOF.SIMS), gas chromatography mass spectrometry (GC-MS) to determine the distribution and the existence form of the non-main elements in the electrodes, the composition of the harmful gaseous products in the passivation and plasma discharge process. We will explore the reaction law of the electrode composition and their effects on the corrosion process, elaborate the corrosion mechanism of electrodes, and make clear the relationship between the harmful components, reaction products and the laser output energy. The research of this project can provide theoretical basis for design, material selection and corrosion resistance treatment of the electrodes.

氟化物准分子激光器是目前最有效的紫外波段器件之一，但是氟介质具有强腐蚀性。电极是激光器的重要部件，它会在氟介质和等离子体的作用下发生腐蚀，可能引起截面变形、生成有害物质，降低激光输出能量和稳定性，限制激光器的性能和应用范围，但确切的腐蚀机制及影响因素目前尚不明确。预实验显示，腐蚀后电极阳极表面不均匀地覆盖着聚集Al、Fe、F等元素的暗礁层，阴极表面遍布聚集Zn、Fe等元素的微粒，表明非主量元素参与腐蚀反应。为此，本项目采用电感耦合等离子体质谱（ICP-MS）、飞行时间二次离子质谱（TOF.SIMS）、气相色谱质谱（GC-MS）等技术，测定激光器钝化和等离子体放电环节电极内非主量元素的分布及存在形式、有害气态产物的组成，探究电极各元素的变化规律和对腐蚀进程的影响，阐述电极的腐蚀机制，阐明有害组分-反应产物-激光输出能量的相关性，为电极的设计、选材与防腐蚀提供理论依据。

氟化物准分子激光器是光刻机主流光源。电极是激光器放电的关键部件，会在强腐蚀性氟工作介质和放电等离子体的作用下发生腐蚀，可能引起截面变形、生成有害物质，降低输出能量、光束质量和稳定性。微观腐蚀机制及影响因素的不明确显著影响着电极的优化，阻碍了光刻光源的研发。.因此，本项目开展了氟化物准分子激光器电极中非主量元素参与的腐蚀机制研究。(1)搭建了高安全性腐蚀平台，包含卤素放电腐蚀模块、在线通道钝化质谱分析模块、激光辐照研究模块，解决了安全性与可控性难题。(2)利用先进的表征技术系统研究了电极的腐蚀特征，揭示了阳极氟负离子侵蚀、阴极氩离子溅射腐蚀与锌元素蒸发为主的腐蚀机制；明确了气体产物CF4、SiF4、PF5等的生成规律，验证其对能量的影响遵循GM Jursich基于气体成分的经验模型；明确了微米级腐蚀产物对光学部件严重的诱导损伤作用；(3)建立了钝化、放电、换气等过程腐蚀的物化模型，确定了各环节的主要反应物与控制措施；确定了放电过程扩散形成的十微米量级的碳氢氧硅和IA族、IIA族、VIB族元素严重聚集区域，是造成不同电极放电性能差异的主要原因；揭示了电极钝化效果在很大程度上取决于表面有害组分含量，但长期化学稳定性与表面质量、内部有害组分及扩散速率有关。目前，通过针对性优化，国产准分子激光器电极寿命已超过20亿脉冲，有害元素含量降低3.5%，并基于研究过程中建立的低污染、高分辨率表征与监测方案制定了放电腔工艺规程。.本项目研究结果已应用于从材料工艺的角度支撑国内自主知识产权的深紫外光刻光源研发。同时，本研究也对航空宇航、航海、核能等领域极端环境中材料的腐蚀与防护具有重要的借鉴与参考价值。