The invention relates to a method for patterning the surface of a substrate by self-assembly of block copolymers which includes the following steps: forming a first mask (20) defining at least two areas to be plated (21a, 21c) on the surface of the substrate; forming an assembly guide (23a) above the first mask (20), such that the assembly guide defines a surface covering two contact areas (22a, 22c) belonging respectively to the two areas to be plated (21a, 21c); depositing a block-copolymer layer on said surface; reorganising the block-copolymer layer; removing one of the phases (24) of the reorganised block-copolymer layer, resulting in a plurality of holes extending in the block-copolymer layer above the two contact areas (22a, 22c) and a portion of the first mask (20) arranged between the two contact areas (22a, 22c); widening the holes of the block-copolymer layer by etching, until a continuous trench (25a) is formed above the two contact areas (22a, 22c) and said portion of the first mask (20); transferring the continuous trench (25a) through the first mask (20) onto the surface of the substrate such as to form patterns that correspond to the contact areas (22a, 22c).