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2009
Conference Paper
Titel
Next generation of front grid metallization: LCP selective emitter combined with Ni-Cu-Sn direct plating on silicon
Abstract
The sequence of laser chemical processing (LCP) and electrochemical metal deposition direct on silicon is presented as the next generation of front grid metallization. The subsequent metallization process after selective emitter forming works self aligned and shows structures with line width as thin as ~40 ?m. Simulations give confidence that efficiency improvements in the range of 1% are achievable as compared to industrial screen printed solar cells. To reach best contact resistance first nickel was plated on locally high doped areas which were produced by LCP method. This layer is followed by thick by silver plating. If thickening is done by copper the prior nickel also needs to built up to serves as a diffusion barrier. Only copper as a strong cost reducing process (-70% compared to pure silver) needs a third metal layer like tin or thin silver to achieve a solderable surface finishing. Both sequences were applied to produce high efficient solar cells with a new front grid metallization cluster without using printing methods. All presented plating processes were carried out on a industrial production platform which ensures a single side wet chemical treatment.
Author(s)