 The third and last step (called SC-2) is performed with a solution of (ratios may vary)
at 75 or 80 °C, typically for 10 minutes.This treatment effectively removes the remaining traces of metallic (ionic) contaminants, some of which were introduced in the SC-1 cleaning step.It also leaves a thin passivizing layer on the wafer surface, which protects the surface from subsequent contamination (bare exposed silicon is contaminated immediately).