Patent ID: 8776334

Claim:
A method for manufacturing piezoelectric thin film resonators, the method comprising: forming sacrifice layer patterns on an upper surface of a mother substrate; forming a dielectric film on the sacrifice layer patterns; processing a surface of the dielectric film by a plasma treatment so as to flatten the surface of the dielectric film, forming vibration portions on the dielectric film, the vibration portions each being composed of two excitation electrodes and a piezoelectric thin film provided therebetween; etching the sacrifice layer patterns; and cutting the mother substrate into separate piezoelectric thin film resonators, wherein the step of processing the surface of the dielectric film comprises: fitting the mother substrate provided with the dielectric film formed thereon to a substrate plate; placing the mother substrate in a sputtering chamber; supplying a gas in the sputtering chamber; and performing sputtering etching of the surface of the dielectric film with plasma of the gas generated by supplying an RF voltage to the substrate plate while the substrate plate is electrically floated from the sputtering chamber.