Method for manufacturing vibrator element

A method for manufacturing a vibrator element which includes a first vibration arm and a second vibration arm that extend along a first direction and that are arranged side by side along a second direction intersecting the first direction, and

• in which the first vibration arm and the second vibration arm each have a first surface and a second surface that are arranged opposite to each other in a third direction intersecting the first direction and the second direction, a bottomed first groove that opens to the first surface, a bottomed second groove that opens to the second surface,
• the method comprising:
• providing a quartz crystal substrate having a first substrate surface and a second substrate surface that are in a front and back relationship;
• forming a first protective film on the first substrate surface;
• conducting first dry etching of the first substrate surface of the quartz crystal substrate through the first protective film, to simultaneously form the first surface of the first and second vibration arms, the first bottomed grooves, and outer shapes of the first vibration arm and the second vibration arm;
• after conducting the first dry etching, forming a second protective film on the second substrate surface;
• and
• after conducting the first dry etching and after forming the second protective film, conducting second dry etching of the second substrate surface of the quartz crystal substrate through the second protective film, to simultaneously form the second surface of the first and second vibration arms, the second bottomed grooves, and the outer shapes of the first vibration arm and the second vibration arm, wherein
• in the first dry etching, the outer shapes of the first vibration arm and the second vibration arm are formed to be closer to the second substrate surface in the third direction than positions where bottom surfaces of the second bottomed grooves are formed in the second dry etching, and
• in the second dry etching, an etching depth in second groove forming regions is substantially equal to an etching depth in an inter-arm region located between a first vibration arm forming region in which the first vibration arm is formed and a second vibration arm forming region in which the second vibration arm is formed, such that overlap between the outer shapes formed in the first dry etching and the outer shapes formed in the second dry etching results in penetration of the inter-arm region.