1 May 1994 Low-complexity subspace-based estimation of axis of symmetry for lithographic alignment
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In lithographic alignment, the previously etched features on the wafer are used for aligning the wafer with the mask for subsequent exposure steps. Accurate and timely estimation of the position of the alignment patterns on the wafer is becoming more crucial as feature sizes continue to shrink, and misalignment errors become less tolerable. In this paper, we propose a low complexity algorithm for estimating the position of the axis of symmetry of registration marks in lithographic alignment. The proposed technique is based on the exploitation of our recently developed SLIDE (subspace-based line detection) algorithm along with ideas from communication theory, and produces sub-pixel resolution estimates for the axis of symmetry of alignment marks. A further stage of the algorithm provides estimates of the linewidth.
© (1994) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Hamid K. Aghajan, Hamid K. Aghajan, Thomas Kailath, Thomas Kailath, } "Low-complexity subspace-based estimation of axis of symmetry for lithographic alignment", Proc. SPIE 2196, Integrated Circuit Metrology, Inspection, and Process Control VIII, (1 May 1994); doi: 10.1117/12.174148; https://doi.org/10.1117/12.174148

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