Method for treating thin layers (CIGS, Mo), with a view to forming a connection of a photovoltaic cell (C1, C2) comprising said thin layers, said thin layers comprising 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, the method comprising the steps: - etching, in said first layer (CIGS), at least one first trench having a first width 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 less than the first width, the etchings of the first and second trenches being 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 coarse etching operation between the first and second fronts; said fine and coarse etching operations being chosen according to one of the following configurations: - the fine etching operation is carried out by an etching along a single row of laser shot impacts partially overlapping in the sense of the length of the trench and the coarse etching operation is carried out by an etching along a plurality of rows, each of the rows comprising a succession of impacts arranged and partially overlapping both along the length and along the width, this overlapping along the length being less than the overlap used for the fine etching operation, the overlap also applying between two facing impacts belonging respectively to a row from the fine etching and to a row from the coarse etching that follows or precedes; - the fine etching operation is carried out by an etching along a single row of laser shot impacts partially overlapping in the sense of the length of the trench and the coarse etching operation is carried out by an etching along a plurality of rows with two impacts of a same row not overlapping, two opposite impacts belonging respectively to a row from the fine etching and a row from the coarse etching also not overlapping; - the fine etching operation is carried out by an etching leading to an overlap in width and in length of the impacts from laser shots along a plurality of laser shot impact rows and the coarse etching operation is carried out by an etching leading to a simple overlap of the laser shot impacts in the sense of the length. - 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, - etching, in said first layer (CIGS), at least one first trench having a first width 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 less than the first width, - a fine etching operation close to fronts (FR1, FR2) intended to delimit the first trench, and; - a coarse etching operation between the first and second fronts; - the fine etching operation is carried out by an etching along a single row of laser shot impacts partially overlapping in the sense of the length of the trench and the coarse etching operation is carried out by an etching along a plurality of rows, each of the rows comprising a succession of impacts arranged and partially overlapping both along the length and along the width, this overlapping along the length being less than the overlap used for the fine etching operation, the overlap also applying between two facing impacts belonging respectively to a row from the fine etching and to a row from the coarse etching that follows or precedes; - the fine etching operation is carried out by an etching along a single row of laser shot impacts partially overlapping in the sense of the length of the trench and the coarse etching operation is carried out by an etching along a plurality of rows with two impacts of a same row not overlapping, two opposite impacts belonging respectively to a row from the fine etching and a row from the coarse etching also not overlapping; - the fine etching operation is carried out by an etching leading to an overlap in width and in length of the impacts from laser shots along a plurality of laser shot impact rows and the coarse etching operation is carried out by an etching leading to a simple overlap of the laser shot impacts in the sense of the length.