| 摘要 |
PURPOSE: To compensate the variation of ion beam current caused by the variation of degree of vacuum in a processing chamber by collecting secondary electrons and secondary ions produced by the collision of ion beams and remaining gas, measuring current, and correctly monitoring the number of incident ion particles based on the measured current value. CONSTITUTION: Ion beams 13, when pass through a slit 18 of a disc 11 rotating at high speed, are monitored with a Faraday cup 15, and detected with an ammeter 16. The current is formed into pulse state corresponding to the revolution speed of the disc 11. The amounts of secondary electrons and secondary ions produced by the collision of the ion beams and the remaining gas are independently measured with ammeters 28, 29, added 30, then converted into the variation of the current amount of the ion beams 13. The converted amount is sampled with a sampler 31, and converted into a signal synchronized with a signal from the Faraday cup 15. The signal from the Faraday cup 15 and the signal from the sampler 31 are added 32, current-multiplied 33, and used for measuring the number of incident ions.
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