Example acoustic bandgap devices provided that can be fabricated in a
semiconductor fabrication tool based on design check rules. An example device includes a substrate
lying in an x-y plane and defining an x-direction and a y-direction, an acoustic
resonant cavity over the substrate, and a phononic
crystal disposed over the acoustic
resonant cavity by generating the phononic
crystal as a plurality of unit cells disposed in a periodic arrangement. Each unit
cell include: (a) at least one higher
acoustic impedance structure having a longitudinal axis oriented in the y-direction and a thickness in the x-direction greater than or about equal to a minimal feature thickness of the
semiconductor fabrication tool, and (b) at least one lower
acoustic impedance material bordering at least a portion of the at least one higher
acoustic impedance structure and forming at least a portion of a remainder of the respective unit
cell.