Structure and fabrication process for self-aligned locally deep-diffused

Abstract

A solar cell having self-aligned metal electrodes and underlying relatively deep emitter regions joined by relatively shallow emitter regions under the surface not covered by the electrodes is formed in a semiconductive substrate by forming relatively shallow p+ and n+ diffusion regions on the front and back surfaces, respectively, of a silicon semiconductive substrate, screen printing aluminum onto the front surface of the substrate in a desired electrode pattern, heat treating the developing cell to form the relatively deep p+ type emitter regions underneath the electrode pattern, while growing an oxide passivation layer over the uncovered portions of the substrate surface, applying an antireflective coating to the front surface in the regions not covered by the electrodes, and screen printing silver over the electrodes on the front surface and over the back surface of the solar cell.