A method of forming a resonator by providing a first layer; forming a sacrificial layer on the first layer; forming a capping layer on the sacrificial layer; forming at least one etching aperture in the capping layer; forming at least one additional aperture having a different size than the at least one etching aperture; forming a cavity and releasing a resonator structure within the cavity by removing the sacrificial layer by etching via the at least one etching aperture; sealing the at least one etching aperture; and forming a lining in the at least one additional aperture.