The Studies On Instabilities In Electronegative Gas Inductively Coupled Plasma

The investigation on discharge mode transition and the non-linear of forced oscillation are studies in the past. At the foundation of past work, Characteristics of instabilities in electronegative gas (SF6) inductively coupled plasmas (ICPs) are experimentally studied under different condition. This more in-depth understanding of radio-frequency inductive coupling plasma mode transformation and the generation mechanism of instability provide a guarantee for the preparation of large area uniform RF plasma source.In the past electronegative gas studies of attachment instabilities, only the effect of gas pressure to attachment instabilities was studied and the related theories were studied. However, no experimental work was reported on the subject that the coupling intensity involved with the distance is reasonably able to influence the attachment instability. Using advanced Z-Scan measuring system, current probe and Langmuir probe, measuring many parameters including plasma absorbed power, antenna current, antenna voltage, plasma floating voltage, and the wave shape of the attachment instabilities, effects on the properties of transition between plasma discharge E-mode and H-mode transition by changing impedance matching network, coupled density of antenna, and pressure are studied. The effective resistance of the hardware consisting of the matching network and the rf coil was calculated, and the rf power absorbed by the plasma greatly improves the reliability of experimental results. It is found that the forced oscillation, the sudden mode transitions and the attachment instabilities are influenced by the coupling intensities. With increasing absorbed power, weak and middle coupling discharges sequentially undergo sudden mode transitions and attachment instabilities. In strong coupling discharges, the sudden mode transitions disappear and only attachment instabilities exist. It can be deduced that the strong and weak coupling discharges are the most stable and unstable, respectively. Experimental results also show that the instabilities only occur in H modes operating in positive feedback regions.