Acoustic wave device and method for manufacturing acoustic wave device

An acoustic wave device comprising:

• a substrate;
• a first acoustic impedance layer and a second acoustic impedance layer provided on the substrate;
• a piezoelectric layer provided on the first acoustic impedance layer and the second acoustic impedance layer;
• an interdigital transducer (IDT) electrode provided on the piezoelectric layer, and at least partially overlapping the first acoustic impedance layer in a plan view from a thickness direction of the piezoelectric layer;
• and
• at least one electrode provided on the piezoelectric layer, and at least partially overlapping the second acoustic impedance layer in a plan view from the thickness direction;
• wherein
• the second acoustic impedance layer is arranged side by side with the first acoustic impedance layer in a direction orthogonal or substantially orthogonal to the thickness direction;
• each of the first acoustic impedance layer and the second acoustic impedance layer includes:
• a high acoustic impedance layer including at least one layer;
• and
• a low acoustic impedance layer including at least one layer having a lower acoustic impedance than an acoustic impedance of the high acoustic impedance layer;
• in each of the first acoustic impedance layer and the second acoustic impedance layer, at least one of the high acoustic impedance layer and the low acoustic impedance layer is a conductive layer;
• a capacitor is defined by the conductive layer in the second acoustic impedance layer and the at least one electrode;
• and
• the conductive layer in the first acoustic impedance layer is electrically insulated from the conductive layer in the second acoustic impedance layer.