Bulk Acoustic Wave Resonator Boundary Mass Structure for Q Stability

The patent applies local quality by creating a through-hole at the center of the resonance film rather than uniformly thickening the entire structure. This localized modification provides mechanical support exactly where needed (at the center where bending stress is highest) while keeping the rest of the film thin, thus resolving the contradiction between device compactness and mechanical strength.

Instead of removing material in annular recesses around the periphery, the patent places a through-hole at the center of the resonance film. This localized structural modification achieves the desired acoustic boundary condition improvement for enhancing Q factor while actually strengthening the film by providing central support, thus resolving the contradiction between Q factor enhancement and mechanical strength.

The patent maintains the thin film structure for good acoustic wave propagation but introduces a through-hole at the center where the film is most vulnerable to bending. This localized modification provides mechanical support that maintains flatness under stress while preserving the thin-film acoustic performance, thus resolving the contradiction between acoustic propagation and flatness.

Instead of forming a protruding structure on the bottom electrode that would affect the entire flatness of the resonance film, the patent creates a through-hole at the center of the film. This localized approach provides the necessary boundary condition modification for Q factor enhancement while minimizing impact on overall flatness, as the modification is confined to a small central region rather than affecting the entire film structure.