A method produces a microstructure comprising an island of material confined between two electrodes forming barriers, the island (30) of material having lateral flanks running parallel to and lateral flanks running perpendicular to the barriers, wherein the lateral flanks of the island are defined by etching of at least one layer (16), called the template layer, and the barriers are formed by damascening. The method includes (a) a first etching of the template layer using a first etching mask having at least one filiform part, and (b) a second etching of the template layer, subsequent to the first etching, using a second etching mask also having at least one filiform part, oriented in a direction forming a non-zero angle with a direction of orientation of the filiform part of the first mask, in the vicinity of the site of formation of the island.