Laser ablation of etch resists for structuring and lift-off processes
Structuring of dielectric and metal layers as well as silicon itself are key processes in the production of silicon solar cells. In this paper we suggest selective structuring of etch resist and organic lacquers by laser ablation as a general structuring approach. This approach is a simple and fast way of creating small structures in an etch resists or a precursor for lift- off processes. Two possible applications for laser structured organic lacquers will be presented in this paper. One application includes the structured etch resist technology for the electrical isolation of an aluminum layer acting as a rear side metallization for back contacted cells, the other is based on a lift-off application leading to a process sequence for a front side metallization. Since etch resist absorbs light at wavelengths in the infrared regime (2 - 10 ?m) which are not absorbed in silicon the chance of damaging the wafer by choosing an appropriate laser system can be reduced. To this point high efficiency solar cells with Ps-FF of up to 83.1 % and VOC of 661 mV were fabricated.