Using Solvent Immersion to Fabricate Variably Patterned Poly(methyl methacrylate) Brushes on Silicon Surfaces

In this paper we describe a graft polymerization/solvent immersion method for generating various patterns of polymer brushes. We used a very-large-scale integration (VLSI) process to generate well-defined patterns of polymerized methyl methacrylate (MMA) on patterned Si(100) surfaces. A monolayer of Si(CH3)3 groups was first generated to form an inert surface by reacting a hydroxylated Si surface with hexamethyldisilazane in a thermal evaporator. Oxygen plasma was the used to reactivate the patterned surface under a duty ratio of 1:1 using electron beam lithography. The surface-generated oxygen species, such as Si−O and Si−O−O, reacted with the initiator for atom transfer radical polymerization (ATRP) on the patterned hydroxylated surface. The ATRP initiator on the patterned surface was then used for the graft polymerization of MMA to prepare the PMMA brushes. After immersion of wafers presenting lines and dots of these PMMA brushes in water and tetrahydrofuran, we observed mushroom- and brush-like regimes, respectively, for the PMMA brushes with various pattern resolutions.