Patent ID: 8770724

Claim:
A piezoelectric element comprising: a first electrode; a piezoelectric layer formed above the first electrode to have a longitudinal direction and a transverse direction in a planar view, the piezoelectric layer having a side surface following the longitudinal direction; and a second electrode formed above the piezoelectric layer, wherein at least a part of the side surface of the piezoelectric layer includes a concavo-convex surface having a plurality of concavities and convexities in a cross-sectional view normal to the longitudinal direction, and a width of the piezoelectric layer in the transverse direction increases from the second electrode to the first electrode over the extent of the side surface, wherein the side surface of the piezoelectric layer has a flat surface connected to an upper surface of the piezoelectric layer, the concavo-convex surface is connected to the flat surface, the side surface of the flat surface and the second electrode is covered by a first coating layer, the concavo-convex surface is covered by a second coating layer, and Young's modulus of the second coating layer is smaller than Young's modulus of the first coating layer and Young's modulus of the piezoelectric layer.