The invention concerns a novel bulk acoustic wave (BAW) resonator design and method of manufacturing thereof The bulk acoustic wave resonator comprises a resonator portion, which is provided with at least one void having the form of a trench which forms a continuous closed path on the resonator portion. By manufacturing the void in the same processing step as the outer dimensions of the resonator portion, the effect of processing variations on the resonant frequency of the resonator can be reduced. By means of the invention, the accuracy of BAW resonators can be increased.