Abstract
Since accurate alignment is essential for projection lithography, an extended dual-grating based alignment scheme is proposed. This method is an extension of the basic dual-grating alignment model, the mechanism of which is explained to make it clear how the extended scheme performs in projection lithog raphy. The framework of the extended alignment scheme for projection lithography is constructed, and the process of key parameter determination is then detailed. In both cases, a tiny shift of the wafer during the alignment process can be resolved by a conspicuous displacement or phase variation of corresponding fringes. Analytical results indicate that alignment is independent of the gap between wafer and mask, disturbance from the fluctuation in illumination can be neglected, and alignment resolution in sub nanometers can be realized with this scheme.
© 2010 Optical Society of America
Full Article | PDF ArticleMore Like This
Wei Yan, Yong Yang, Wangfu Chen, Song Hu, and Shaolin Zhou
Appl. Opt. 49(31) 5959-5963 (2010)
Feng Xu, Shaolin Zhou, Song Hu, Wenbo Jiang, Liang Luo, and Hongyu Chu
Opt. Express 23(16) 20905-20915 (2015)
Jiangping Zhu, Song Hu, Junsheng. Yu, Shaolin Zhou, Yan Tang, Min Zhong, Lixin Zhao, Minyong Chen, Lanlan Li, Yu He, and Wei Jiang
Opt. Express 21(3) 3463-3473 (2013)