RF self-bias potential is measured in a Capacitively coupled RF plasma by adding a capacitor (called bolcking capacitor) just after the matching network (provided your matching network require manual tuning of capacitor) and rf live electrode. For all automatic RF tuning networks available RF self-bias is always measured and displayed. I think more help might be available if you expand what actual problem you are facing and what type of matching network and RF system you have.
yes, check wether you have this blocking capacitor, normally you have it in your matchbox. I am not sure a rf plasma would start without it? Have a high-voltage probe on the driven electrode (with an oszilloscope, well grounded to the chamber), that is all. Out of the rf noise, the DC offset will be your self-bias. Whenever you work at low self-bias voltages (higher -100V) you will have to take care of the plasma potential to determine your ion bombardment energy (something like +/- 15V). If you do not have the oscilloscope with the high-voltage probe, then you have to build yourself your own probe. An approprate (high) inductance, followed by a voltage divider (if no highvoltage is wanted) . The inductance would filter out the rf signal, let only the DC average pass through. (of course the voltage divider has to have a high impedance so that you not drive to much current, since this current will modify your self-bias (the plasma carrier balance))
thanks..i just confuse about where to tab the probe..so, i can confirm that what i done before are right..
i have tab the probe after matching box, but i am using normal probe..so the probe easily become hot..
i using 150MHz and my matching is in Pai configuration with both capasitor are grounded..i also working with capasitive couple plasma..
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