Patent ID: 8347469

Claim:
A method for manufacturing a crystal oscillator piece containing a vibrating tine having a first side face and a second side face, comprising the steps of: forming a first etching mask on an upper surface of a crystal wafer and a second etching mask on a lower surface of said crystal wafer; and forming said vibrating tine by immersing said crystal wafer in an etching solution thereby dissolving crystal portions not covered with said first and second etching masks, wherein said second etching mask is designed to have a first protruding portion protruding from a position corresponding to a first edge of said first etching mask, said first protruding portion being chosen to have such a length that a first residue is formed in a predetermined shape on said first side face, irrespective of a positional displacement between said first and second etching masks, and said first and second etching masks are designed so that a second residue formed on said second side face is adjusted so as to ensure that one of two principal axes passing through a centroid and dynamically perpendicular to each other in a cross section taken perpendicularly to a longitudinal direction of said vibrating tine is oriented substantially parallel to said upper or lower surface of said crystal wafer.