Piezoelectric resonator unit

A piezoelectric resonator unit comprising:

• a piezoelectric resonator including a piezoelectric layer having a first principal surface and a second principal surface facing each other in a thickness direction of the piezoelectric layer, a first excitation electrode on the first principal surface, a second excitation electrode on the second principal surface, a first extended electrode electrically connected to the first excitation electrode and extended to a peripheral edge portion of the first principal surface of the piezoelectric layer, and a second extended electrode electrically connected to the second excitation electrode and extended to a peripheral edge portion of the second principal surface of the piezoelectric layer;
• a first substrate adjacent to the first principal surface of the piezoelectric layer;
• a first adhesion layer interposed between the first substrate and the piezoelectric layer;
• a second substrate adjacent to the second principal surface of the piezoelectric layer;
• a third substrate adjacent to the second principal surface of the piezoelectric layer, the third substrate positioned closer to the second principal surface of the piezoelectric layer than the second substrate;
• a third adhesion layer interposed between the third substrate and the piezoelectric layer;
• and
• a second adhesion layer interposed between the second substrate and the third substrate, wherein
• the second substrate includes a first outer electrode in a peripheral edge portion on a surface opposite from the piezoelectric layer,
• in plan view of a surface of the third substrate opposite from the piezoelectric layer, the third substrate includes a first cut-away portion exposing a first inclined portion of the third adhesion layer expanding toward an outer side portion of the third substrate and a first extended end portion of one of the first extended electrode or the second extended electrode,
• in plan view of the surface of the second substrate opposite from the piezoelectric layer, the second substrate includes a second cut-away portion exposing a second inclined portion of the second adhesion layer expanding toward an outer side portion of the second substrate, the first extended end portion of the one of the first extended electrode or the second extended electrode, the first inclined portion of the third adhesion layer, and the first cut-away portion of the third substrate;
• and
• a first connection electrode on the second cut-away portion of the second substrate, the second inclined portion of the second adhesion layer, the first cut-away portion of the third substrate, and the first inclined portion of the third adhesion layer that electrically connects the first outer electrode and the first extended end portion of the one of the first extended electrode or the second extended electrode.