Abstract: A drying process for wafers includes positioning the wafers to be dried in a cleaning device full of isopropyl alcohol (IPA) vapor and replacing moisture out of the wafers with the IPA vapor. Gas steam including the IPA vapor is exhausted from the cleaning device into a scrubber, and the scrubber has at least a solvent therein for dissolving the IPA vapor and an exhaust outlet for discharging gas mixture of the IPA vapor and the solvent. A flow rate of the solvent in the scrubber is adjusted to increase a concentration of the IPA vapor in the cleaning device and thus obtain better uniformity for drying the wafers.