Tuned Substrate Bias Rf Inductive Coupling Plasma Oscillations

The RF(Radio Frequency) research group specialise in the physical characteristic of ICP(inductive coupled plasma)tuned substrate self-bias. Not long ago, a new phenomenon that there was bistate, jumped delay in tuned substrate self-bias was found for the first time in an experiment,and researched in detail.In course of experiment of bistate, jumped delay phenomenon, another new phenomenon, the fluctuation of tuned substrate self-bias, was found again. The fluctuation of tuned substrate self-bias is a low frequency fluctuation that comes into being when the rf plasma discharges at a special parameter and the reactance of tuned circuit is in a definite value. The frequency of the fluctuation is about 1000-6000Hz, the swing is 10V or so.Based on the various aspect of the fluctuation, a large amount of experiment was carried on. The naissance, behavior and speciality of the fluctuation was explored, and the course of which was also analyzed. A qualitative explain was put forward.Experimental results show that the fluctuation of tuned substrate self-bias was determined by discharge gas pressure,discharge power and tuning circuit parameters etc. The fluctuation exists is because of there is capacitive coupling in ICP system and sheath capacitance is nonlinear. The nonlinear change of sheath capacitance operates with tuned circuit, results in the fluctuation.