Selective Laser Ablation of Anti-Reflection Coatings for Novel Metallization Techniques

The industrial standard process for producing solar cell front sides includes several drawbacks. First of all the screen-printed front side metallisation with silver paste leads to contacts with a poor aspect ratio and a low conduction quality due to the composition of a printable paste. Additionally, the poor contact resistance requires high surface doping concentrations of the emitter. When using further developed cell concepts like the laser-fired contacted rear side (LFC) featuring dielectric passivation and a local point contact structure, the high-temperature step for establishing the front contact is detrimental too. A solution for this problem could be the use of alternative front side metallisation techniques. Without firing through they all require a selective opening of the front side antireflection coating. The approach studied in this paper is the selective laser ablation of this layer.