Utilizing Block Copolymer Films as an Etch Mask for Pattern Transfer

Micro- and nanopatterned surfaces are highly useful as functional surfaces and in the fabrication of electronic and optical devices. Transferring high-resolution patterns into a photoresistive layer or the substrate surface is a crucial step in fabricating a nanostructure with gratings, pillar arrays, and hole arrays. In this work, a very simple yet efficient and high-throughput route for pattern transfer was investigated based on the self-assembly of block copolymers (BCPs). The high etch contrast and high density of the periodic pillar array require a vertically oriented structure of the cylinder-forming BCP. Solvent-vapor annealing under fine-tuned conditions allowed us to control the orientation of the BCP microdomains relative to the surface. Liquid-phase infiltration (LPI) of metal ions of Au, Pt, and Pd into the BCP domains effectively enhanced the etch contrast for pattern transfer. By investigating the conditions of the LPI and etching processes, it was found that the nanopatterns from BCP templates were successfully transferred into the SiO₂ layer on wafers with a high aspect ratio of pillars. It was also shown that this process can be applied to the Si₃N₄ substrate and that more diverse and complex patterns can be transferred via BCP blends. Through this work, it was demonstrated that BCP assembly combined with the LPI process can be a highly efficient and versatile route to pattern transfer with high resolution and throughput.