| 摘要 |
PROBLEM TO BE SOLVED: To provide a low cost, precise, and reliable probe which detects current and voltage of RF electric power to be applied to a plasma chamber and precisely detects phase angle between the supplied voltage and the supplied current. SOLUTION: An RF probe of a plasma chamber 20 picks up data of current and voltage of an RF electric power applied to an RF plasma chamber and supplies waveforms of the RF electric voltage and current respectively to mixers 30, 36. A local oscillator 38 supplies local oscillator signals to both mixers at about±15kHz RF frequency to provide voltage and current base band signals. These base band signals are supplied to a stereo two-channel A/D converter 42 to supply the base band signals to a DSP 46. The DSP 46 are properly programmed to carry out compounded fast Fourier transform for the base band signals of voltage and current and the amplitude and the phase angle of voltage and current are extremely precisely computed. Consequently, parameters are miniaturized, the cost is made cow low, drift is lowered, and precision is heightened, and suitability for integration is improved and moreover harmonic analysis is made possible and remote controlling and monitoring can be easily carried out.
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