| 摘要 |
PURPOSE: To eliminate electron shading by a method wherein a positive voltage of a pulse waveform is applied as a bias voltage and the duty ratio of the pulse waveform and a repetition frequency are set so that the maximum value of a potential in a material to be treated under a surface treatment becomes larger than that of a potential in plasma. CONSTITUTION: A conventional high frequency power supply of a sine waveform, which is used as a bias power supply, is changed and a pulse power supply 17 is installed. The power supply 17 is constituted of an arbitrary waveform generator 25 and a high-speed wide band power amplifier 26 of a slew rate of 10<5> /μsec and a signal from the generator 25 is amplified by the amplifier 26. A positive voltage of a pulse waveform is applied from this power supply 17 as a bias voltage and the duty ratio of the pulse waveform and a repetition frequency are set so that the maximum value of a potential in a material 1 to be treated under a surface treatment becomes larger than that of a potential in plasma. That is, the duty ratio of the pulse waveform and the repetition frequency are respectively set in a ratio of 95 to 5% or lower and at a frequency of 400kHz or higher, desirably in a ratio of 99 to 1% or higher and at a frequency of 1MHz or higher.
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