| CPC H03H 9/02259 (2013.01) [H03H 9/02015 (2013.01); H03H 9/0207 (2013.01); H03H 9/02102 (2013.01); H03H 9/0211 (2013.01); H03H 9/02157 (2013.01); H03H 9/131 (2013.01); H03H 9/205 (2013.01); H03H 2009/02165 (2013.01)] | 32 Claims |

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1. A bulk acoustic wave resonator comprising:
a substrate;
a first piezoelectric layer having a first piezoelectric axis orientation;
a second piezoelectric layer having a second piezoelectric axis orientation that substantially opposes the first piezoelectric axis orientation; and
a multi-layer metal top acoustic reflector electrode including a first pair of top metal electrode layers electrically and acoustically coupled with the first and second piezoelectric layers to excite a piezoelectrically excitable resonance mode at a main resonant frequency of the bulk acoustic wave resonator; and
an etched edge region extending through the first piezoelectric layer, the second piezoelectric layer, and the first pair of top metal electrode layers.
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