Stitch-avoiding Detailed Routing for Multiple E-Beam Lithography

Document Type

Conference Article

Publication Title

IEEE/IFIP International Conference on VLSI and System-on-Chip, VLSI-SoC


Next-Generation Lithography techniques such as Electron Beam Lithography (EBL), Multiple E-Beam Lithography (MEBL), and Extreme Ultraviolet Lithography (EUVL), overcome the limitations of 193 nm immersion lithography. In MEBL, the layout is split into vertical stripes, with the stripe boundaries termed stitch-lines, and thousands or even millions of electron beams (e-beams) are used in parallel for good throughput. Patterns in different stripes are written either by distinct e-beams or in different passes. Hence, patterns cut by stitch-lines suffer from overlay error and thereby severe pattern distortions, particularly Via, Vertical Routing, and Short Polygon violations near the stitch-lines. In this paper, we propose a Stitch-avoiding Detailed Router that reduces these violations. It is integrated with (i) a traditional global router, and (ii) a Stitch-avoiding Global Router. Experimental results for these two routing flows are compared with those of a baseline flow comprising a traditional global router followed by a traditional detailed router. Significant reductions in stitch-line violations are obtained, especially for the second routing flow, compared to the baseline flow.



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