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.

Is Poly(methyl methacrylate) (PMMA) a Suitable Substrate for ALD?: A Review

“…The route starts with the deposition of the BCP in substrates (silicon wafer [ 78 , 80 , 105 , 106 ] or magnesium oxide [ 104 ]) by spin-coating. Subsequently, BCP is annealed at a temperature above the glass transition temperature of both polymers [ 80 ] to neutralize and remove the excess solvent, followed by cleaning to eliminate the non-anchored chains [ 78 , 80 , 106 ].…”

“…For templates with a brush layer, there is no defined order for the subsequent steps. In fact, the desired effect depends on the order: (1) ALD deposition over the template; (2) exposition to UV light [ 78 ], piranha solution [ 80 ], plasma [ 105 ], acetic acid [ 78 , 106 ] or etching [ 104 ] to remove the PMMA and PS from the DBC and the brush layer; (3) cleaning to remove excess material from (2). According to the desired method, there is a possibility to remove the unexposed parts of the substrate by etching [ 80 , 106 ].…”

Area-selective atomic layer deposition of molybdenum oxide

“…The last approach to AS-ALD is to include etching steps in the process to etch back all the undesired material deposited on the non-growth surface. This will also etch the material on the growth surface, but since the film is thicker here, some material will still be left in the desired area [142,143].…”

Analysing trimethylaluminum infiltration into polymer brushes using a scalable area selective vapor phase process

“…PS systems are well established for achieving area deactivation to prevent material growth in ASD/BCP processes in ALD and other infiltration methods. 16,20,21 Thorough discussion of the practicalities of pyridine based polymers as infiltration media are described elsewhere, [21][22][23][24][25][26] however, to summarize, both P2VP and P4VP have favourable characteristics for use as area activation media in ASD and BCP lithography. Due to the nitrogen lone pair located in the pyridine ring ( Figure 1a), both poly-vinyl pyridines (PVPs) can facilitate metal coordination bonding.…”