| 摘要 |
PROBLEM TO BE SOLVED: To solve a problem that a highly precise vibrating plate is not obtained. SOLUTION: A vibrating plate 10 is made of a silicon layer 23 which is doped in high concentration boron. Boron concentration of the boron-doped silicon layer 23 on the surface facing a jet chamber 6 is equal or higher than 5*1019 (at oms/cm3), and the layer possesses a concentration grade that the concentration at the position of 0.1μm crossing from the surface facing the jet chamber 6 to the vibrating plate is equal or more than 1.2 times of the concentration on the surface facing the jet chamber 6.
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