(A) study on impedance matching in a large-area transformer coupled plasma source

Abstract

Impedance matching in a large-area Transformer Coupled Plasma source was studied. At first, automatic impedance matching was planned, so some ideas for automatic impedance matching are presented. But, we discovered that in our experimental system there is only one impedance matching condition and it is irrelevant to plasma status. Because the automatic impedance matching in our experimental system is meaningless, we tried to find the only impedance matching condition. During the impedance matching experiment, a discrepancy between theoretical calculations and experimental results was found. So, we introduced a new way of understanding our system using a modified model which is based on the assumption that inductance and capacitances have a dependency on frequency, and the modified model explained the experimental results well. With this modified model, load impedances of the power supply in various configurations were calculated and used to analyze the data from plasma experiments. In our experimental system, maximum plasma density was found near 500Ω load impedance regardless of the condition of a plasma. Thus, we concluded that the only impedance matching condition is located near 500Ω load impedance. Furthermore, plasma control is possible based on the experimental data.