Wet etching of HfO2 assisted by excimer photon irradiation

This report describes an attempt to remove an HfO₂ film by wet etching in the trial manufacture of a high-k film loaded transistor module. In dry etching, there are techniques for improving the etching rate, such as an assist of ionic species by plasmas. Wet etching, which involves immersion in a chemical solution, has limitations. This study achieved improvement in the etching rate by irradiating the film to be etched with excimer UV light so that the film is changed into a state that is readily eroded by the chemical solution.