Fabrication of needle-like nanostructures using block copolymer for non-volatile memory

In this work, the fabrication of nanostructures applicable to nano floating gate memory is investigated by using a block co-polymer system composed of Polystyrene (PS) and Polymethylmethacrylate (PMMA). A thin film of self-assembled block copolymer has been used during all experiments for nanostructures with critical dimensions below photolithographic resolution limits. Under suitable conditions, the PS and PMMA self assembled into a honey comb lattice of PMMA in the matrix of PS. Nanoporous thin film from PS-b-PMMA diblock co-polymer thin film with selective removal of PMMA domains was used to fabricate needle-like nanostructures. The reactive ion etching (RIE) was then carried out at room temperature in a single wafer RIE system with the substrate having nano-cylindrical structures. The plasma was excited by radio frequency. Diverse surface nanostructures of sub-100 nm patterning were fabricated by plasma etching using block co-polymer. Finally, we have demonstrated that by combining these self assembled block co-polymers with regular semiconductor processing, a non-volatile memory device with increased charge storage capacity over planar structures can be realized.