28 March 2014 A shape-modification strategy of electron-beam direct writing considering circuit performance in LSI interconnects
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Abstract
As the feature size of LSI shrinks, the cost of mask manufacturing and turn-around-time continue to increase. Maskless lithography using electron beam direct writing (EBDW) technology attracts attention. On the other hands, with continuous scaling and the introduction of low-k dielectrics in Cu interconnect technology, reliability degradation caused by time-dependent dielectric breakdown (TDDB) and electromigration has become important issues. Therefore, EBDW in backend process is needed to ensure superior patterning quality and reliability using high-accuracy proximity effect correction (PEC). We have already proposed a dose-modification strategy of EBDW considering reliability for TDDB degradation. In this paper, furthermore, we propose a shape-modification strategy of EBDW considering circuit performance in LSI interconnects for improving EB drawing throughput. We use effectively patterns with rounded corner in order to reduce EB shots increased by PEC and avoid the local high current density at the corner of metal lines. We applied the proposed method to a microprocessor layout synthesized with the Nangate 45nm Open Cell Library. As a result, the drawn pattern by corner rounding and coarse dose adjustment achieved 2.5% higher throughput than that by no corner rounding and fine dose adjustment.
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Yoshihiro Midoh, Atsushi Osaki, Koji Nakamae, "A shape-modification strategy of electron-beam direct writing considering circuit performance in LSI interconnects", Proc. SPIE 9049, Alternative Lithographic Technologies VI, 90491Z (28 March 2014); doi: 10.1117/12.2046336; https://doi.org/10.1117/12.2046336
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