Method for manufacturing piezoelectric resonator element

1. A method for manufacturing a piezoelectric resonator element from a substrate made of a piezoelectric material, the method comprising:

forming a first dry etching mask on a first masking region of a first surface of the substrate in a first mask forming process;

forming a plurality of openings in the first dry etching mask;

performing a first dry etching process;

removing a portion of the substrate within each of the plurality of openings during the first dry etching process and after the first mask forming process to form a plurality of flutes;

removing a portion of the substrate in areas between the first dry etching mask during the first dry etching process and after the first dry etching mask forming process to form etching-processed portions that extend into the substrate to a greater extent than each of the plurality of flutes after the first mask forming process;

maintaining a first un-etched portion of the substrate remaining from each of the removed portions of the substrate in the areas between the first dry etching mask after the first dry etching process;

forming an affected layer corresponding to the openings of the first dry etching mask and substrate during the first dry etching process;

removing the first dry etching mask in a mask removing process and after the first dry etching process;

performing a wet etching process;

removing the affected layer during the wet etching process and following the removal of the first dry etching mask;

etching a bottom surface of each flute during the wet etching process such that the bottom surface of each flute includes a sloped surface; and

removing the first un-etched portion of the substrate during the wet etching process and after the mask removing process to form the piezoelectric resonator element.

2. The method for manufacturing a piezoelectric resonator element according to claim 1 , further comprising forming a second dry etching mask on a second masking region of a second surface of the substrate in a second mask forming process, wherein the second surface of the substrate is on an opposite side from the first surface.

3. The method for manufacturing a piezoelectric resonator element according to claim 2 , further comprising performing a second dry etching process to remove a portion of the substrate in areas between the second dry etching mask after the second mask forming process.

4. The method for manufacturing a piezoelectric resonator element according to claim 3 , further comprising maintaining a second un-etched portion of the substrate remaining from each of the removed portions of the substrate in the areas of the second surface between the second dry etching mask after the second dry etching process.

5. The method for manufacturing a piezoelectric resonator element according to claim 4 , further comprising removing the second dry etching mask in a mask removing process after the second dry etching process.

6. The method for manufacturing a piezoelectric resonator element according to claim 5 , wherein performing the wet etching process removes the first un-etched portion of the substrate and the second un-etched portion of the substrate after the first mask removing process and the second mask removing process.

7. The method for manufacturing a piezoelectric resonator element according to claim 1 , wherein the piezoelectric resonator element is a tuning-fork quartz resonator element.