| 摘要 |
PROBLEM TO BE SOLVED: To prevent dispersion of the thickness (main resonance frequency) of a crystal piece and the deterioration of an yield caused by obtaining the crystal piece by dividing a crystal wafer ground to fixed thickness. SOLUTION: A crystal wafer is fixed by a pedestal 2 inside a container 3 for circulating etchant and an array-like heater 5, for which heater pieces are arranged in a grid shape, is provided on the bottom surface of the container 3. A controller 7 fetches the thickness data of respective parts inside a crystal wafer surface, controls each output of a programmable power source 6 corresponding to the data, and thus individually heats the respective parts of the crystal wafer. Thus, by individually controlling the dissolving speed of the respective parts and changing the dissolving amount of' the respective parts, intra-surface thickness is uniformized. The plate thickness of the crystal pieces for which the crystal wafer is divided thereafter is less dispersed.
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