a single - chamber type cleaning - drying apparatus for flat objects , such as semiconductor wafers , wherein cleaning is carried out by impinging both sides of the wafer , which rotates at a relatively low speed , with jets of a washing liquid and wherein subsequent drying is carried out in the same chamber by increasing the rotation speed of the wafer and supplying isopropyl - alcohol mist onto the wafer from the top of the chamber . after the ipa forms a solution with the residue of water on the wafer , the drying process is accelerated by supplying gaseous nitrogen through nozzles arranged on both sides of the wafer he coaxially with the wafer center . as a result , the ipa - water solution quickly evaporates without leaving traces of water drops on the dried surface .