Tailoring the Morphology Transformation and Simultaneous Generation of Bimodal Patterns through Directed Self-Assembly of Binary Cylindrical Block Copolymer/Homopolymer Blends

Abstract

Lithography with directed self-assembly (DSA) has demonstrated significant potential in fabricating integrated circuits, particularly in logic and memory chips with periodic patterns. However, it is challenging to achieve asymmetrical line patterns with block copolymers (BCPs) that meet the manufacturing requirements of integrated circuits. We propose a binary cylindrical BCP/homopolymer blending strategy to generate asymmetric multiple line patterns. By carefully tailoring the blending rates of homopolymer poly(methyl methacrylate) (hPMMA) with different molecular weights in cylindrical polystyrene-b-poly(methyl methacrylate), we manipulate the morphology transformation, period, and PMMA duty cycle (space width relative to the pitch) of BCP/hPMMA self-assembly. Specifically, we employ a BCP/hPMMA blend to fine-tune the process window of asymmetric multiple line patterns with the aid of PS-affined topographical templates. This approach highlights the superiority of line pattern quality in the blends compared to the symmetric lamellar BCP. Moreover, the simultaneous generation of bimodal line and hole patterns was achieved through a one-step DSA process with one BCP/hPMMA blend. Furthermore, self-consistent field theory simulation was employed to explore the self-assembly of BCP/homopolymer blend in confined guiding templates, and the results were in good consistency with the experimental results. This strategy provides an essential technological platform for the fabrication of asymmetrical line and hole patterns with various resolutions and complex metal layers.