This invention methods of etching an aluminum oxide comprising substrate, and methods of forming capacitors. In one implementation, a method of etching an aluminum oxide comprising substrate includes flowing water and ozone to aluminum oxide on the substrate, with at least one of the water and the ozone being at a temperature of at least 65.degree. C. at the aluminum oxide effective to etch aluminum oxide from the substrate. In one implementation, aspects of the method are utilized in forming a capacitor.