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

A method of treating thin layers for forming a connection of a photovoltaic cell comprising said thin layers, said thin layers comprising:

• a first layer, with photovoltaic properties, deposited on a second layer, and
• said second layer, which is a metal contact layer, deposited on a substrate, the method comprising:
• etching, in said first layer, at least one first trench having a first width so as to expose the second layer;
• 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 etching of the first and second trenches being carried out by laser impacts, during a single overall etching step,
• wherein said overall etching step comprises:
• a fine etching operation close to first and second fronts intended to delimit the first trench, and
• a rough etching operation between the first and second fronts.