| 摘要 |
PURPOSE:To simply measure the thickness of a target in a sputtering device by bringing an ultrasonic oscillator into contact with the rear side of the target and detecting the frequency of radiated ultrasonic waves resonating with the target. CONSTITUTION:An ultrasonic quartz oscillator 3 is brought into contact with the rear side of the erosion part 2 of a target 1 consumed by use in a sputtering device, and an ultrasonic oscillator 4 generating ultrasonic waves whose frequency varies continuously according to a variation of the capacity of a variable capacitor 5 is connected to the oscillator 5 through a capacitor. Ultrasonic voltage whose frequency varies according to a variation of the capacity of the capacitor 5 is impressed on the target 1 with the oscillator 3, and the resonance of the target 1 with the impressed ultrasonic waves at the time when integral times as long as the half wavelength lambda/2 (lambda is wavelength) of the ultrasonic waves become equal to the thickness (t) of the erosion part 2 of the target 1 is detected by a rapid increase of the current value of an ammeter A. The thickness (t) is measured by an equality t=n.V/2Xfn (where fn is resonance frequency and V is the velocity of sound in the target 1).
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