from the conferences organized by TANGER Ltd.
We have targeted in this study the contact deposition of copper on the silicon surface of a solar cell. We show the different drawbacks encountered in the process and present some solution and ways to obtain satisfactory copper-based contact. Nickel and copper are studied individually by varying the current density and the deposition time. The final structure obtained is a layer of 140 nm of nickel and more than 10 µm of copper. The quality of the contact strongly depends on the uniformity of the deposit. The thickness must be the same on each point of opened surface and the busbar that is 1.5mm wide has to be adequately fulfilled as the fingers that are narrower (less than 200µm). The adhesion is also an important parameter to make a good contact. If these conditions are completed the obtained contact resistance is around 1mΩ.cm². This condition implies a good seed layer of Ni, without oxidation. A heat treatment around 400°C during 5min in an inert atmosphere provides an accurate Ni seed layer. Otherwise the Cu top layer will comes off. So the conditions of a good contact deposition are tightly related to the surface preparation.
Keywords: Electrochemical deposition, copper contact, Si solar cells, adhesion© This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.