针对极紫外(EUV)光刻机工作过程中,多层膜反射镜表面沉积碳污染造成的反射率下降问题展开研究,讨论了多层膜反射镜表面碳污染清洗方法.首先描述了在EUV曝光过程中多层膜表面的碳污染形成过程,简单阐述了碳污染对多层膜反射镜的危害.然后从清洗机理、速率以及效果等方面详细描述了多种EUV多层膜表面碳污染清洗方法,分析对比了各清洗技术在清洗速率和效果等方面的优缺点.分析表明:离子体氧和活化氧清洗速率相差不多,可达到2 nm/min,但清洗过程中容易造成表面氧化;等离子体氢和原子氢的清洗速率相对较慢,一般在0.37 nm/min左右,但清洗过程中不易产生氧化.最后针对不同方法应用于在线清洗EUV多层膜反射镜过程中将遇到的问题和难点进行了讨论.%T his paper focuses on the reflectivity decrease of reflective elements caused by the carbon contamination deposited on multilayers during EUV ( Extreme Ultraviolet ) lithography working and emphasizes the clear method of carbon contamination deposited on multilayers .T he process of carbon contamination deposited on multilayers was elucidated and the damage of carbon contamination on the multilayers was introduced briefly . Several kinds of cleaning methods for carbon contamination deposited on multilayers were described in detail from cleaning mechanism ,removing rate and cleaning effect ,and their advantages and disadvantages were analyzed .The result indicates that the cleaning rates of plasma oxygen and activated oxygen reach 2 nm/min ,but the multilayer surface is easy to be oxidized in cleaning process ;and the plasma hydrogen and atomic hydrogen have relatively slow cleaning rates ,they are only about 0 .37 nm/min ,but the multilayer surface is hardly to be oxidized . Moreover ,the difficulties of different cleaning methods for X-ray multilayer mirrors in-situ are discussed .
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