A method for producing surface features and an etch masking method. A combination is provided of a block copolymer and additional material. The block 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. A film is formed of the combination directly onto a surface of a first layer. Nanostructures of the additional material self-assemble within the first polymer block. The film of the combination and the first layer are 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. The film is removed and features remain on the surface of the first layer. Also included is an etch masking method where the nanostructures mask portions of the first layer from said etchant.