Area-selective atomic layer deposition of cobalt oxide to generate patterned cobalt films

Abstract

The authors report the area-selective deposition of cobalt (II) oxide on polystyrene-patterned SiO2/Si and MgO(001) substrates at 180 °C by atomic layer deposition (ALD) using bis(N-tert butyl, N′-ethylpropionamidinato) cobalt (II) and water as coreactants. The patterned CoO films are carbon-free, smooth, and were reduced with atomic deuterium at 220 °C to produce Co metal patterns without shape deformation. CoO ALD is facile on starting surfaces that features hydroxyl groups favoring CoO nucleation and growth. Polystyrene (PS) is very effective in blocking ALD of CoO. The PS is patterned using UV-crosslinked 40 nm-thick PS films to generate μm-size features or using self-assembled 40 nm-thick polystyrene-block-polymethylmethacrylate (PS-b-PMMA) films to generate nm-size features. The unexposed PS in UV-crosslinked PS films is dissolved away with toluene, or the PMMA component in self-assembled PS-b-PMMA films is selectively removed by a plasma etch to expose the underlying oxide surface. The magnetic properties of the Co metal patterns grown by area-selective atomic layer deposition are presented.