| 摘要 |
PURPOSE:To detect an emission spectrum with high resolving power, and to detect the end point of film formation positively by a method wherein emission spectral intensity is converted into voltage, amplified and observed, a maximum value is predicted from a voltage rise after discharge starting and amplification gains are corrected automatically. CONSTITUTION:An emission spectral intensity signal converted 3 into voltage is amplified 4, multiplication type D/S converted 8, and A/D converted 7 and input to a CPU 5. The CPU predicts a peak value from the rise of emission spectral intensity, and computes amplification gains so that the peak value is brought close to the full scale of the A/D converter 7 and feeds back a computed value to the multiplication type D/A converter 8. According to the constitution, gains are corrected automatically so that the A/D con verter is full-sealed even to the level variation of emission spectral band intensity, thus detecting spectral intensity with high resolving power, then positively detecting an end point.
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