Resonator Element

A resonator element, when three axes orthogonal to each other are defined as an X-axis, a Y-axis, and a Z-axis, and a direction along the X-axis is defined as an X-axis direction, a direction along the Y-axis is defined as a Y-axis direction, and a direction along the Z-axis is defined as a Z-axis direction, the resonator element comprising:

• a vibrating substrate including:
• a base portion;
• and a first vibrating arm, a second vibrating arm, and a third vibrating arm, each of the first, second, and third vibrating arms extending from the base portion in the Y-axis direction and being arranged side by side in the X-axis direction, the first vibrating arm being disposed between the second vibrating arm and the third vibrating arm in plan view from the Z-axis direction;
• a first piezoelectric element disposed across the first vibrating arm and the base portion to cause the first vibrating arm to perform flexural vibration in the Z-axis direction by expanding and contracting in the Y-axis direction;
• a second piezoelectric element disposed across the second vibrating arm and the base portion to cause the second vibrating arm to perform flexural vibration in the Z-axis direction by expanding and contracting in the Y-axis direction;
• and
• a third piezoelectric element disposed across the third vibrating arm and the base portion to cause the third vibrating arm to perform flexural vibration in the Z-axis direction by expanding and contracting in the Y-axis direction,
• wherein each of the first piezoelectric element, the second piezoelectric element, and the third piezoelectric element includes:
• a piezoelectric layer;
• a lower electrode disposed between the piezoelectric layer and the vibrating substrate;
• and
• an upper electrode overlapping the lower electrode via the piezoelectric layer in plan view from the Z-axis direction, and
• in the first vibrating arm, the second vibrating arm, and the third vibrating arm,
• when a region overlapping a boundary between the base portion and a vibrating arm is defined as a first portion, and
• when a region closer to a tip end side of the vibrating arm than the first portion is defined as a second portion,
• each of the lower electrode and the upper electrode of the first piezoelectric element includes:
• a first electrode film in the first portion;
• and
• a second electrode film in the second portion,
• the first electrode film being connected to the second electrode film,
• the first electrode film being made of a material having a higher yield point than that of a constituent material of the second electrode film.