METHOD OF FABRICATING SOLAR CELLS WITH SILICON NITRIDE COATING

摘要

A process of manufacturing silicon solar cells with efficiencies of between about 12.5% and about 16.0% is described, the method being characterized by forming a P/N junction adjacent the front surface of a silicon substrate, subjecting the front surface of the substrate to a selected plasma surface etch treatment, and then forming a polysilazane coating on the etched front surface by (a) first subjecting the substrate to an ammonia plasma treatment for a predetermined period of time so as to produce hydrogen implantation and (b) subjecting the subtrate to a silane and ammonia plasma treatment to obtain additional hydrogen implantation and formation of a polysilazane (hydrogenated silicon nitride) coating. The polysilazane coating is etched to form a grid electrode pattern. An aluminum coating is applied to the rear side of the substrate so as to form a back electrode. The aluminum coating is heated so as to alloy with the silicon substrate and thereby form an ohmic contact. The alloying step also densifies the polysilazane so that it is more nearly silicon nitride. The exposed silicon on the front side of the substrate is coated with an adherent coating of a highly conductive metal so as to form a grid electrode.