Method for Manufacturing Vibration Element

A method for manufacturing a vibration element including

• a first vibrating arm and a second vibrating arm extending along a first direction and arranged side by side along a second direction that intersects with the first direction,
• the first and second vibrating arms each having a first surface and a second surface being front and rear sides with respect to each other and arranged side by side in a third direction that intersects with the first and second directions, a bottomed first groove that opens to the first surface, a bottomed second groove that opens to the second surface, and a side surface that couples the first surface and the second surface to each other, the method comprising:
• a preparation step of preparing a quartz crystal substrate having the first surface and the second surface;
• a first dry etching step of dry-etching the quartz crystal substrate from a first surface side to form the first grooves and outer shapes of the first and second vibrating arms;
• a second dry etching step of dry-etching the quartz crystal substrate from a second surface side to form the second grooves and the outer shapes of the first and second vibrating arms;
• and
• a subsequent wet etching step of wet-etching the side surfaces of the first and second vibrating arms, the first grooves, and the second grooves to form inclining surfaces that couple bottom surfaces to in-groove side surfaces of the first and second grooves,
• wherein the first and second grooves satisfy a relationship of D1/D ≥ 0.80, where D represents a depth of each of the first and second grooves, and D1 represents a result of subtraction of a length of the inclining surfaces in the third direction from the depth in each of the first and second grooves.