A method. A combination is provided of a block copolymer and additional material. The copolymer includes a first block of a first polymer covalently bonded to a second block of a second polymer. The additional material is miscible with the first polymer. The first polymer includes polystyrene and the second polymer includes poly(ethylene oxide). A first layer including polydimethylglutarimide is adhered onto a surface of a substrate including a dielectric coated silicon wafer. A film is formed of the combination directly onto a surface of the first layer. Nanostructures of the additional material self-assemble within the first polymer block. The film and the first layer are simultaneously etched. The nanostructures have an etch rate lower than an etch rate of the block copolymer and lower than an etch rate of the first layer. Portions of the film are removed. Features remain on the surface of the first layer.