A method is disclosed to form a patterned template on a substrate, to direct orientation of a self-assemblable block copolymer. The method involves providing a resist layer of a positive tone resist on the substrate and overexposing the resist with actinic (e.g. UV) radiation by photolithography to expose a continuous region of the resist layer with a sub-resolution unexposed resist portion at the interface between the resist and the substrate. The resist portion remaining at the interface, after removal of the exposed region, provides a basis for a chemical epitaxy template. The method may allow for simple, direct photolithography to form a patterned chemical epitaxy template and optionally include an accurately co-aligned graphoepitaxy feature and/or a substrate alignment feature.