Laser etching a stack of thin layers for a connection of a photovoltaic cell

The invention concerns a treatment of thin layers (CIGS, Mo) with a view to forming a connection of a photovoltaic cell (C1, C2) comprising said thin layers, which comprise at least: * - a first layer (CIGS), having photovoltaic properties, deposited on a second layer (Mo), and * - said second layer, a metal contact layer, deposited on a substrate (SUB). The following steps in particular are carried out: * - etching, into said first layer (CIGS), at least one first trench having a first width (L1) so as to expose the second layer (Mo); and * - etching, in said first trench, a second trench so as to expose the substrate, the second trench having a second width (L2) less than the first width (L1). The etching of the first and second trenches is, moreover, carried out by laser shots, during a single overall etching step, the method being characterised in that said overall etching step comprises: - a fine etching operation close to fronts (FR1, FR2) intended to delimit the first trench; - and a rough etching operation between the first and second fronts.