Contacting - Laser Contact Opening (LCO)
The so-called Laser Contact Opening (LCO) process is an important step in the production of IBC and PERC cells. It creates contact openings at the rear passivation layer by laser ablation. The focus is on the selective removal of passivation layers via a dashed, dot or line pattern.
Typical methods for opening the back of the cell
Typical processes for opening the back of the cell are the mechanical scribing or the wet chemical etching process. Both processes are impractical in terms of speed and waste, cue:
High contamination in wet etching, are not practical.
Therefore, the laser process is ideal for selective, non-contact removal of the layer.
Advantages of Laser Contact Opening
- Interdigitated Back Contact Solar Cells (IBC) feature interdigitated metal contacts on the back surface. The doped emitter and back surface field regions are also interdigitated under the contacts.
- The challenges in fabricating this cell structure lie in precisely defining the n+ and p+ doped regions on the back surface and avoiding short circuits when contacting the two regions separately.
- High-precision laser systems from InnoLas Solutions achieve the necessary precision of the local contact opening (significantly smaller than 10µm) at maximum throughput of up to 7,500 wafers per hour.
Recommended machine type: LUMION, ULTAGO