Direct Self-Assembly for Non-Periodic Designs

Abstract

Previously we investigated a directed self-assembly (DSA) process for fabricating a nonperiodic pattern (i.e., wide line) lying in between the periodic line/space patterns. A symmetric poly(styrene-block-methyl methacrylate) (PS-b-PMMA) was employed here, which formed a lamella morphology with the natural period (L 0 ) of 30 nm. Unlike the conventional DSA process, we used ArF resist patterns as the chemical guides, and generated a horizontal lamella on the non-periodic guide pattern as an etch template for fabricating the wide line. Our preliminary results showed that controlling the morphological defects around the boundary between the periodic and non-periodic regions would be crucial for this DSA flow. In this paper, we report on how the width of the non-periodic pattern, W, would affect on the overall self-assembled morphology of PS-b-PMMA on the pre-patterned surface. The experimental results showed that a transition from the perpendicular to horizontal lamella on the non-periodic pattern occurred at W=2.50 L0. It was also revealed from our simulations that at W=1.50 L 0 , the perpendicular PS-rich domain was not attached to the guide surface; it might be taken off after the removal of PMMA. For W>3.5 L 0 , the wide line was transferred to the underlying silicon (Si) substrate, but some large defects were observed in the non-periodic region, possibly due to some residues of the neutral materials on top of the ArF guide pattern.

The Photopolymer Science and Technology Award

“…These interesting research results were presented at the Annual Conference of Photopolymer Science and Technology in 2013 and 2016, and published in the JPST [18,19].…”

“…In 2016, Dr. Yoshimoto and his coworkers have reported an application of the OK model to the new DSA process for generating the periodic and non-periodic patterns at one step [19]. In this study, they determined the values of interactive parameters between surface and block copolymers from the calibration to some experimental data.…”