The application discloses an acid
pickling method for electronic-grade polysilicon gradient, which comprises the following steps: carrying out three-stage acid
pickling on polysilicon blocks, using the
discharge liquid of the next stage acid
pickling as the acid pickling liquid of each stage; carrying out high-purity water cleaning on the polysilicon blocks before each acid pickling, and carrying out high-purity water spraying after the first high-purity water cleaning and the last high-purity water cleaning; and finally, carrying out
nitrogen drying on the polysilicon blocks after the spraying cleaning. The method has the advantages that the
utilization rate of the acid pickling liquid is effectively improved, and the operation cost is reduced through the orderly and multi-stage acid pickling utilization mode. Meanwhile, the
acid concentration of the multi-stage utilized acid pickling liquid is reduced, the
ion concentration is high, the
surface tension of the acid pickling liquid is effectively reduced, the wettability of the acid pickling liquid is higher, the acid pickling liquid can be more deeply in the gaps of the
silicon blocks, and the cleaning quality is improved. Compared with other electronic-grade polysilicon processes, the process is simple, the acid preparation links are reduced, the acid
discharge is reduced, the treatment cost is saved, the method is more
environmentally friendly, and the
personnel safety problem is greatly reduced.