纳米光刻中调焦调平测量系统的工艺相关性  

Process Dependency of Focusing and Leveling Measurement System in Nanoscale Lithography

作　　者：孙裕文[1,2] 李世光[1] 叶甜春[1] 宗明成[1] 

机构地区：[1]中国科学院微电子研究所,北京100029 [2]中国科学院大学,北京100049

出　　处：《光学学报》2016年第8期102-112,共11页Acta Optica Sinica

基　　金：国家科技重大专项(2012ZX02701004)

摘　　要：随着半导体制造步入1xnm技术节点时代,光刻机中的对焦控制精度需要达到几十纳米。在纳米精度范围内,硅片上的集成电路（IC）工艺显著影响调焦调平系统的测量精度。基于实际的调焦调平光学系统模型和三角法、叠栅条纹法测量原理,建立工艺相关性误差模型。研究表明,工艺相关性误差主要来源于测量光在光刻胶涂层内部的多次反射。选取3种光刻胶仿真分析发现,不同光刻胶的工艺相关性误差随光刻胶厚度的变化趋势相同,随测量光入射角（45°~85°）的增大而减小。在实验验证平台上分别测量7种工艺硅片,实验测量值与理论模型计算值差异统计平均值小于6nm。结果表明,光刻机中调焦调平系统的测量光有必要采用大入射角度,同时提高光刻胶的涂胶均匀性,以减少工艺相关性误差。With the development of semiconductor manufacturing to 1x nm technological node,focus control accuracy of lithography needs to meet dozens of nanometers.In the range of nanoscale,integrated circuit（IC）process on silicon wafer has an important impact on the measurement accuracy of the focusing and leveling system.A process dependent error model is established based on actual focusing and leveling optical system model,trigonometry and Moire measurement principle.Research shows that process dependent error mainly results from the multiple reflections inside the photoresist.Simulation is conducted with three different photoresists.The simulation results indicate that process dependent error of different photoresists has the same trend as the photoresist thickness and process dependent error decreases with the increase of incident angle（45°~85°）.Seven processed silicon wafers are measured on the experimental setup.The statistical mean of the difference between the experimental measurement and the theoretical model calculation is less than 6nm.The results show that,in order to reduce the process dependent error,it is necessary to increase the angle of incidence of focusing and leveling system in lithography and improve the uniformity of the photoresist coating.

关 键 词：测量 调焦调平 工艺相关性 纳米光刻 

分 类 号：O436[机械工程—光学工程]