Structure and fabrication process for self-aligned locally deep-diffused emitter (salde) solar cell

Abstract From the Canadian patent

A solar cell (10) having self-aligned metal electrodes (14) and underlying relatively deep emitter regions (21) joined by relatively shallow emitter regions (22) under the surface not covered by the electrodes is formed in a semiconductive substrate (12) by forming relatively shallow p+ and n+ diffusion regions on the front and back surfaces respectively, of a silicon , semiconductive substrate (12) 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 (21) underneath the electrode pattern, while growing an oxide passivation layer (18) over the uncovered …