Self-assembly of Blended PS-b-P2VP Block Copolymers

Abstract

Directed Self-Assembly (DSA) of block copolymers (BCPs) is a promising technique for sub-10 nm nanofabrication, which is highly compatible with conventional lithography. DSA relies on the microphase separation of block copolymers to form nanostructures of different morphologies. The pitch size of the obtained nanostructure depends largely on the intrinsic properties of BCPs and is usually fixed when BCPs are produced. One effective way of tuning the pitch size of BCPs is by blending BCPs of different molecular weight. In this paper, we have demonstrated the pitch tuning capability by blending the triblock poly (2-vinyl pyridine-b-polystyrene-b-poly 2-vinyl) pyridine (P2VP-b-PS-b-P2VP) with another triblock P2VP-b-PS-b-P2VP or diblock copolymer (PS-b-P2VP) at various volume ratios by solvent annealing. The nanopatterns of blended BCPs after sequential infiltration synthesis (SIS) and plasma etching process, were characterized by scanning electron microscopy. It’s observed that the blended BCPs can form highly ordered lamellar nanostructures of different pitch sizes at different blending ratios. The method of blending BCPs of varying molecular weights greatly extends the functionality of existing BCPs, with the capability of fine-tuning nanopatterning pitch at nanometer resolution.

Keywords

• micro-phase
• blending
• lamellar pattern
• solvent annealing
• sequential infiltration synthesis