Fabricating electrically nonconductive blocks using a polymer brush and a sequential infiltration synthesis process

A plurality of mandrels and silicon dioxide spacer structures are formed, with the spacer structures interdigitated between the mandrels. An organic planarization layer is applied, as are a thin oxide layer and a layer of photoresist patterned in hole tone over the oxide layer, thereby defining a domain. At least one hole is etched in the thin oxide layer and the organic planarization layer to expose a portion of a hard mask layer surface between the spacer structures. A selective polymer brush is applied, which grafts only to the exposed hard mask surface, followed by solvent rinsing the domain to remove ungrafted polymer brush. At least one precursor is infused to an etch resistant material into the polymer brush by a sequential infiltration synthesis process. The organic planarization layer is ashed to convert the infused precursor into oxide form to further enhance etch selectivity to the hard mask layer.