Stencil-masked phosphorus-implanted silicon for solar cell applications

Stencil-masked phosphorus implantation on silicon wafers is demonstrated for solar cell applications. Line-shaped window patterns with areas of 156 mm × 156 mm and 125 mm × 125 mm are laid out in the silicon stencil mask with diameters of 200 and 300 mm, respectively. According to laser optical microscopy and scanning electron microscopy observation, the phosphorus-implanted line is 100 μm wide with an edge roughness of a few micrometers. Based on the silicon-stencil-masked phosphorus implantation, the fabrication process of alternative phosphorus-implanted and boron-diffused patterns on silicon wafers is proposed. During the post-implantation wet oxidation process, a thick oxide layer is grown on the phosphorus-implanted silicon, acting as a protective layer for the subsequent diffusion of boron. Scanning capacitance microscopy observation reveals the p-type polarity in boron-diffused silicon and the n-type in phosphorus-implanted silicon with homogeneous contrast along the textured surface. Silicon-stencil-masked ion implantation has potential as a selective doping method on silicon wafers for solar cells.