Method for manufacturing vibration element

A method for manufacturing a vibration element, wherein

• the vibration element includes a first vibrating arm and a second vibrating arm extending along a first direction and arranged side by side along a second direction intersecting the first direction,
• the first vibrating arm and the second vibrating arm each have a first surface and a second surface arranged side by side in a third direction intersecting the first direction and the second direction in a front and back relationship and a bottomed groove opening to the first surface,
• the method for manufacturing a vibration element comprising:
• a preparing step of preparing a quartz crystal substrate having a first substrate surface and a second substrate surface in a front and back relationship;
• a base film forming step of forming a first base film at the first substrate surface in a first vibrating arm forming region in which the first vibrating arm is to be formed and a second vibrating arm forming region in which the second vibrating arm is to be formed;
• a protective film forming step of forming a first protective film in a region of the first base film excluding a groove forming region in which the groove is to be formed;
• and
• a dry-etching step of dry-etching the quartz crystal substrate from a first substrate surface side through the first base film and the first protective film to form the first surfaces, the grooves, and outer shapes of the first vibrating arm and the second vibrating arm.