Selection of DBO measurement wavelength for bottom mark asymmetry based on FDTD method  

作　　者：Buqing Xu Qiang Wu Lisong Dong Yayi Wei 

机构地区：[1]University of Chinese Academy of Sciences,Beijing 100049,China [2]Shanghai Integrated Circuit Research&Development Center,Shanghai 201210,China [3]Institute of Microelectronics,Chinese Academy of Sciences,Beijing 100029,China

出　　处：《Journal of Semiconductors》2019年第12期101-106,共6页半导体学报（英文版）

基　　金：supported by the National Science and Technology Major Project of China (Grant No. 2016ZX02301001)

摘　　要：A physical model for simulating overlay metrology employing diffraction based overlay(DBO)principles is built.It can help to optimize the metrology wavelength selection in DBO.Simulation result of DBO metrology with a model based on the finite-difference time-domain(FDTD)method is presented.A common case(bottom mark asymmetry)in which error signals are always induced in DBO measurement due to the process imperfection were discussed.The overlay sensitivity of the DBO measurement across the visible illumination spectrum has been performed and compared.After adjusting the model parameters compatible with the actual measurement conditions,the metrology wavelengths which provide the accuracy and robustness of DBO measurement can be optimized.A physical model for simulating overlay metrology employing diffraction based overlay(DBO) principles is built. It can help to optimize the metrology wavelength selection in DBO. Simulation result of DBO metrology with a model based on the finite-difference time-domain(FDTD) method is presented. A common case(bottom mark asymmetry) in which error signals are always induced in DBO measurement due to the process imperfection were discussed. The overlay sensitivity of the DBO measurement across the visible illumination spectrum has been performed and compared. After adjusting the model parameters compatible with the actual measurement conditions, the metrology wavelengths which provide the accuracy and robustness of DBO measurement can be optimized.

关 键 词：diffraction based overlay SCATTEROMETRY photolithography simulation metrology wavelength finite difference time domain 

分 类 号：TN2[电子电信—物理电子学]