Piezoelectric element, piezoelectric device, and method of manufacturing piezoelectric element

A piezoelectric device comprising:

• a casing;
• and
• a piezoelectric element disposed in the casing, the piezoelectric element includes a support, and a vibrating portion configured to output a pressure detection signal in accordance with a pressure, wherein
• the vibrating portion includes a piezoelectric film disposed on the support and made of scandium aluminum nitride, and an electrode film connected to the piezoelectric film to generate electric charges by deformation and to extract the electric charges generated,
• the vibrating portion is configured to have a support region supported by the support, and a plurality of vibration regions connected to the support region and floating from the support,
• the plurality of vibration regions are separated from each other by a slit,
• the slit has a tapered portion that is tapered from a first surface of the vibration regions on an opposite side to the support, to a second surface opposite to the first surface,
• the electrode film is positioned in the vibration region such that the electrode film is not exposed at the tapered portion of the slit when being viewed from a normal direction that is orthogonal to the first surface,
• an angle defined by a side surface of the tapered portion in the vibration region and a surface parallel to the first surface is in a range of 39 to 81 degrees,
• the casing includes a mounted member on which the piezoelectric element is mounted, and a lid portion fixed to the mounted member in a state of accommodating the piezoelectric element in the casing, and
• the casing has a through hole communicating with an outside and introducing an atmospheric pressure therein.