Method for etching high-k films in solutions comprising dilute fluoride species

A process for etching high dielectric constant (high-k) films (e.g., ZrzSiyOx, HfzSiyOx, ZrzHfyOx, HfzAlyOx, and ZrzAlyOx) more rapidly than coexisting SiO2, polysilicon, silicon and/or other films is disclosed. The process comprises contacting the films with an aqueous solution comprising a fluoride containing species at a concentration sufficiently dilute to achieve a desired selective etch of the high-k film. The etching solution is preferably used above ambient temperature to further increase the etch selectivity of the high-k films relative to coexisting SiO2 and/or other films. The etch rate of the solution can also be adjusted by controlling the pH of the etching solution, e.g., by the addition of other acids or bases to the solution (for example, HCl or NH4OH).