Method of manufacturing piezoelectric oscillating pieces, piezoelectric oscillating piece, and piezoelectric resonator

A method of manufacturing piezoelectric oscillating pieces, comprising:

• forming a metal film on a surface of a piezoelectric substrate which is cut in a manner that an etching rate in a thickness direction becomes higher than an etching rate in a plane direction;
• forming a photoresist film on a surface of the metal film, the photoresist film having a pattern with which areas around the piezoelectric oscillating pieces are etched and connection support portions supporting the piezoelectric oscillating pieces are formed between the piezoelectric oscillating pieces and the piezoelectric substrate;
• etching the metal film by using the photoresist film as a mask, to form a pattern by;
• next, etching the piezoelectric substrate by using the photoresist film and the metal film as masks, to form contours of the piezoelectric oscillating pieces corresponding to the pattern on the piezoelectric substrate;
• subsequently, from a direction of through spaces formed by the etching for forming the contours of the piezoelectric oscillating pieces, etching the metal film with an etching solution without peeling off the photoresist film, to remove outer peripheral sides of the metal film and expose surfaces of outer peripheral ends of the piezoelectric oscillating pieces;
• and
• thereafter, etching the exposed surfaces of the piezoelectric substrate with an etching solution in the thickness direction of the piezoelectric substrate so as to make the outer peripheral ends of the piezoelectric oscillating pieces thinner than inner peripheral sides of the piezoelectric oscillating pieces.