A stack of layers defines a filter and is formed by copper on hydrogenated silicon nitride supported by a carrier. The filter includes a layer of hydrogenated silicon nitride, a layer of silicon oxide on the layer of hydrogenated silicon nitride and a layer of copper on the layer of silicon oxide. The layer of hydrogenated silicon nitride may have, in a vicinity of its upper side, a ratio of a number of silicon atoms per cubic centimeter to a number of nitrogen atoms per cubic centimeter lower than 0.8 (or even lower than 0.6), with a number of silicon-hydrogen bonds smaller than or equal to 6×1021 bonds per cubic centimeter (or even smaller than 0.5×1021 bonds per cubic centimeter). The filter further includes an additional layer of copper between the layer of hydrogenated silicon nitride and the carrier.