A treatment of thin layers for forming a connection of a photovoltaic cell including the thin layers, which includes a first layer, having photovoltaic properties, deposited on a second layer, and the second layer, which is a metal contact layer, deposited on a substrate, the treatment including etching, in the first layer, at least one first trench having a first width so as to expose the second layer; and etching, in the first trench, a second trench so as to expose the substrate, the second trench having a second width less than the first width.