A four-quadrant gratings alignment method was presented for proximity lithography, which experimentally achieved the alignment accuracy of nanometer level. The alignment marks consist of gratings with slightly different periods, leading to different Talbot distances with the same monochromatic planar wave. The contrast of moire fringe varies with the gap between mask (alignment mark) and wafer (alignment mark), which will affect the phase comparison, and induce more errors as well. This paper concentrates on the optimization of parameters of alignment marks to achieve the resulting moire fringes with an optimum contrast. By simulation and experiment, we investigate effects of the gap on the contrast, based on which, the design principle of alignment marks is concluded, and it is helpful to the practicability with our proposed alignment method. (C) 2014 Elsevier Ltd. All rights reserved.
1.Chinese Acad Sci, Inst Opt & Elect, Chengdu 610209, Peoples R China 2.Univ Elect Sci & Technol China, Sch Optoelect Informat, Chengdu 610054, Peoples R China 3.Univ Chinese Acad Sci, Beijing 100039, Peoples R China
Zhu, Jiangping,Hu, Song,Zhou, Pei,et al. Experimental study of Talbot imaging moire-based lithography alignment method[J]. OPTICS AND LASERS IN ENGINEERING,2014,58:54-59.