Open AccessMoiré fringe alignment using composite circular-line gratings for proximity lithography
Author(s) -
Feng Xu,
Shaolin Zhou,
Song Hu,
Wenbo Jiang,
Liang Luo,
HongYu Chu
Publication year - 2015
Publication title -
optics express
Language(s) - Uncategorized
Resource type - Journals
SCImago Journal Rank - 1.394
H-Index - 271
ISSN - 1094-4087
DOI - 10.1364/oe.23.020905
Subject(s) - optics , grating , lithography , moiré pattern , wafer , materials science , diffraction grating , line (geometry) , photomask , interferometry , optoelectronics , physics , resist , nanotechnology , geometry , mathematics , layer (electronics)
We explore the feasibility of a controllable and easy-to-implement moiré-based composite circular-line gratings imaging scheme for optical alignment in proximity lithography. One circular grating and four line gratings located on both the mask alignment mark and wafer alignment mark are used to realize the coarse alignment and fine alignment respectively. The fundamental derivation of coarse alignment employing circular gratings and fine alignment employing line gratings are given. Any displacement of misalignment that occurs at the surface of two overlapped gratings can be sensed and determined through subsequent fringe phase analysis without the influence of the gap between the mask and the wafer or wafer process. The design and manufacture process of the alignment marks are presented. The experimental results validate and demonstrate the feasibility of the proposed approach.