Method of manufacturing piezoelectric resonator

A method of manufacturing a piezoelectric resonator provided with grooves formed on each of a plurality of vibrating arms extending from the base, comprising the steps of:

• forming a metal film on the surface of a substrate, a piezoelectric substrate;
• forming a first resist film patterned so as to retain the shape of the piezoelectric resonator on the surface of the metal film to form a pattern on the metal film by etching;
• peeling off said whole first resist film;
• forming a second resist film having a pattern formed such that the edge thereof is positioned inside of the edge of the pattern of said metal film by 3 μm to 12 μm at least at the part corresponding to the vibrating arm, and the part conforming to the groove of the vibrating arm is opened;
• next, forming the outer shape of the piezoelectric resonator using said metal film as a mask by bringing said substrate into contact with the etching solution;
• etching to remove the metal film at the part conforming to the groove of said vibrating arm and to remove the metal film outside of the outer shape of said second resist film, using said second resist film as a mask;
• and
• etching the outer shape of the vibrating arm to a shape conforming to the outer shape of said metal film by bringing said substrate into contact with an etching solution to form grooves respectively in said plural vibrating arms and to remove the part extending to the outside of the edge of the metal film on the vibrating arm using said metal film as a mask.