| 摘要 |
A tuning-fork crystal wafer 1A which has legs 11, 12 with grooves 11c, 12c is shaped by etching of a crystal substrate 2. To improve processing precision of the depth of the grooves 11c, 12c, the width of the grooves 11c, 12c, is set in advance, based on the etch stop technique in which the amount of etching depends on the pattern of an etch portion. Consequently, as far as the etch time satisfies a required minimum time, it is possible to obtain the depth as designed.
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