A method for forming a modified resonator is provided. In one aspect, the method includes obtaining a resonator on top of a substrate, thereby forming an interface area between a bottom surface of the resonator and a top surface of the substrate. The resonator can include niobium or tantalum. The method also includes contacting the resonator and the substrate with a liquid acidic etching solution selected so as to have a higher etch rate towards the substrate than towards the resonator and a nonzero etch rate towards the resonator.