Density Driven Placement Of Sub-Dsa Resolution Assistant Features (Sdrafs)

In the pursuit of alternatives to traditional optical lithography, block copolymer directed self-assembly (DSA) has emerged as a low-cost, high-throughput option. However, issues of defectivity have hampered DSA's viability for large-scale patterning. Recent studies have shown copolymer fill level to be a crucial factor in defectivity, as template overfill can result in malformed DSA structures and poor LCDU after etching. For this reason, it is previously demonstrated the use of sub-DSA resolution assist features (SDRAFs) as a method of evening out template density. In this work, we propose an algorithm to place SDRAFs in random logic contact/via layouts. By adopting this SDRAF placement scheme, we can significantly improve the density unevenness and the resources used are also optimized. This is the first work to investigate the placement of SDRAFs in order to mitigate the DSA density variation problem, and it can be adopted for the mass deployment of DSA.