Dopant Applicator System and Method of Applying Vaporized Doping Compositions to PV Solar Wafers

摘要

Silicon wafer processing system, apparatus and method of doping silicon wafers with hot concentrated acid dopant compositions for forming p-n junction and back contact layers during processing into PV solar cells. Highly concentrated acid dopant is atomized with pressurized gas and heated in the range of 80-200° C., then introduced into a concentrated acid vapor processing chamber to apply vapor over 1.5-6 min to wafers moving horizontally on a multi-lane conveyor system through the processing chamber. The wafers are dried and forwarded to a diffusion furnace. An optional UV pre-treatment assembly pre-conditions the wafers with UV radiation prior to dopant application, and doped wafers may be post-treated in a UV treatment module before being fired. The wafers may be cooled in the processing chamber. Post-firing, the wafers exhibit excellent sheet resistance in the 60-95Ω/sq range, and are highly uniform across the wafers and wafer-to-wafer.