Contaminants such as photoresist are quickly removed from a wafer having metal features, using water, ozone and a base such as ammonium hydroxide. Processing is performed at room temperature to avoid metal corrosion. Ozone is delivered into a stream of process liquid or into the process environment or chamber. Steam may alternatively be used. A layer of liquid or vapor forms on the wafer surface. The ozone moves through the liquid layer via diffusion, entrainment, jetting/spraying or bulk transfer, and chemically reacts with the photoresist, to remove it.