A method for removing a plurality of dielectric films from a supporting substrate by providing a substrate with a dielectric layer overlying another dielectric layer, contacting the substrate at a first temperature with an acid solution exhibiting a positive etch selectivity at the first temperature, and then contacting the substrate at a second temperature with an acid solution exhibiting a positive etch selectivity at the second temperature. The dielectric layers exhibit different etch rates when etched at the first and second temperatures. The first and second acid solutions may contain phosphoric acid. The first dielectric layer may be silicon nitride and the second dielectric layer may be silicon oxide. Under these conditions, the first temperature may be about 175° C. and the second temperature may be about 155° C.