By Icp Tuned Substrate Bias Transition Hysteresis Phenomenon

In a CCP system, there is a discontiguous characteristic on tuned substrate self-bias. When the impedance between substrate and ground was made increasingly inductive, a large negative dc potential developed on the substrate. However, when the inductance was increased beyond a certain critical value, the dc substrate potential changed discontinuously to a small, sometimes positive, value.Our research group first developed tuned substrate experiment in an ICP system. A LC resonance circuit was connected to the substrate, and it is found that there were bistable, jumped delay phenomena in substrate self-bias.In this paper, the reasons why the tuned substrate self-bias jumped discontinuously and was bistable are revealed, and the factors affect the characteristic are given.Experimental results show that the bistable of tuned substrate self-bias was determined by discharge gas pressure, discharge power and tuning circuit parameters etc. The bistable exists is because of there is capacitive coupling in ICP system and sheath capacitance is nonlinear. The nonlinear change of sheath capacitance result in the nonlinear change of tuned substrate self-bias.