Development of Block Co-Polymers as Self-Assembling Templates for Patterned Media

Abstract

Block copolymers that self-organize are of interest as templates for patterned media, as they potentially provide a low cost fabrication route. Poly(styrene)-Poly(methylmethacrylate) block co-polymers (PS-b-PMMA) of appropriate block length and PS to PMMA ratio self-assemble into a 2-D hexagonal phase in which the PS majority phase is continuous and surrounds cylinders of the minority, PMMA phase. For application of this phase to patterned media it is necessary that the cylinders of the minority phase be oriented perpendicular to the substrate surface. This can be achieved by a number of methods, including appropriate choice of substrate and use of a random co-polymer underlayer. We report here that indium tin oxide surfaces are also capable of inducing a perpendicular orientation in block co-polymers, likely due to the effect of surface roughness of the substrate. Use of an acetic acid wash causes the minority PMMA component can be induced to be rearranged, giving rise to pores perpendicular to the substrate. Using a conducting substrate such as Tantalum thin film on Silicon wafer, electrodeposition can be carried out into the open pores to produce arrays of magnetic nanopillars of 18 nm diameter.

Electrodeposition of cobalt nanowires on H-terminated conductive Si(111) surfaces using coblock polymer templating

“…Figure 1 shows representative GISAX images of block copolymers spin-coated atop the surface of H-terminated conductive Si͑111͒ and annealed for 24 h above the T g temperature. 13,14,20 As can be observed in Fig. Similar results have been shown on SiO x surfaces where electric-field alignment is used to orient the pores perpendicular to the surface.…”