Field-Theoretic Simulations of Multi-Cylinder Configurations in VIA Lithography

We have studied the self-assembly of PS-PMMA block copolymers by means of SCFT simulations in elongated templates and established commensurability windows for the formation of single rows of two and three cylindrical VIAs. Our results indicate that VIAS with increasing CD form inside templates of increasing dimensions. The VIAs are symmetrically arranged inside the template and the resulting hole-to-hole distances range from 24 nm to 34 nm for template lengths between 80 nm and 140 nm. We emphasize that the present work assumed perfect templates; future studies will examine VIA positioning within templates with line edge roughness. While encouraging for both CD and placement aspects, our results nonetheless indicate low defect formation energies leading to defect densities well above the targets of the lithography community. The development of novel strategies, including alternative polymer architectures, to reduce defectivity is thus critical for the success of DSA in VIA lithography and contact multiplication.