Mixtures containing concentrated sulfuric acid used for stripping photoresist from semiconductor wafer, such as SOM and SPM mixtures, are more quickly removed from a wafer surface using another liquid also containing high concentration of sulfuric acid, with the second liquid furthermore containing controlled small amounts of fluoride ion. The second liquid renders the wafer surface hydrophobic, which permits easy removal of the sulfuric acid therefrom by spinning and/or rinsing.