浸没式光刻机对焦控制技术研究
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摘要
随着大规模集成电路芯片制造步入十几纳米技术节点时代,光刻机的对焦控制变得越来越困难,其精度需要达到几十纳米。基于实际的光刻机对焦控制系统架构和光刻对焦原理,开展了浸没光刻对焦控制统计分析方法研究。根据系统结构分析出一系列误差源,研究了这些误差对总离焦误差的贡献方式及其与总离焦误差的关系。研究结果表明:由于光刻对焦误差中存在非正态分布的误差贡献项,常规正态统计分布使用的3_σ原则就无法满足99.7%的对焦成功率要求;在28,14,7nm技术节点集成电路芯片制造过程中,采用3_σ和4_σ原则得到的浸没光刻工艺总对焦成功率之差分别为28.4%、55.1%、62.9%。为了达到99.7%的对焦成功率,浸没式光刻机对焦控制应采用4_σ原则。
As large-scale integrated circuit chips manufacturing steps into the era of tens of nanometers technology node,the focus control of the lithography machine becomes more and more difficult with the precision of several tens of nanometers.In this paper,a statistical analysis method of immersion lithography focusing control is studied based on the architecture and lithography focusing principle of actual lithography machine focusing control system.A series of error sources are obtained based on the system structure,and their contribution way and relationship to the total defocus error are investigated.The results show that due to the non-normal distribution error contribution term in lithography focusing error,the 3_σ principle used in the normal statistical distribution can not meet the 99.7%focusing success rate requirement.In the manufacturing process of 28,14,7 nm technology node integrated circuit chips,the difference of the total focusing success rates of immersion lithography can be as high as 28.4%,55.1% and 62.9%,when 3_σ and 4_σ principles are used respectively.In order to reach 99.7%focusing success rate,the 4_σ principle should be used in the focus control of immersion lithography.
As large-scale integrated circuit chips manufacturing steps into the era of tens of nanometers technology node,the focus control of the lithography machine becomes more and more difficult with the precision of several tens of nanometers.In this paper,a statistical analysis method of immersion lithography focusing control is studied based on the architecture and lithography focusing principle of actual lithography machine focusing control system.A series of error sources are obtained based on the system structure,and their contribution way and relationship to the total defocus error are investigated.The results show that due to the non-normal distribution error contribution term in lithography focusing error,the 3_σ principle used in the normal statistical distribution can not meet the 99.7%focusing success rate requirement.In the manufacturing process of 28,14,7 nm technology node integrated circuit chips,the difference of the total focusing success rates of immersion lithography can be as high as 28.4%,55.1% and 62.9%,when 3_σ and 4_σ principles are used respectively.In order to reach 99.7%focusing success rate,the 4_σ principle should be used in the focus control of immersion lithography.
引文
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[7] Li X P,Chen F B.Measurement model of focusing and leveling measurement system for projection lithography tool[J].Acta Optica Sinica,2007,27(11):1987-1991.李小平,陈飞彪.投影光刻机硅片调焦调平测量模型[J].光学学报,2007,27(11):1987-1991.
[2] Wei Y Y. Advanced lithography theory and application of VLSI[M].Beijing:Science Press,2016:6-10.韦亚一.超大规模集成电路先进光刻理论与应用[M].北京:科学出版社,2016:6-10.
[3] Bouchoms I, Leenders M,Graaf R D,et al.Extending 1.35 NA immersion lithography down to1xnm production nodes[J].Proceedings of SPIE,2012,8326:83260L.
[4] Mih R D.How focus budgets are spent:limitations of advanced i-line lithography[J].Proceedings of SPIE,1996,2726:386-397.
[5] Jang J H,Park T,Park K D,et al.Focus control budget analysis for critical layers of flash devices[J].Proceedings of SPIE,2014,9050:90502F.
[6] Li J L,Hu S,Zhao L X.Control technique of wafer surface in dual-stage lithographic system[J].Acta Optica Sinica,2012,32(12):1223002.李金龙,胡松,赵立新.双工件台光刻机中的焦面控制技术[J].光学学报,2012,32(12):1223002.
[7] Li X P,Chen F B.Measurement model of focusing and leveling measurement system for projection lithography tool[J].Acta Optica Sinica,2007,27(11):1987-1991.李小平,陈飞彪.投影光刻机硅片调焦调平测量模型[J].光学学报,2007,27(11):1987-1991.