Influence Of Different Coil Geometries On Plasma Properties In Inductively Coupled Plasmas

An inductively coupled plasma (ICP) source, due to its geometric simplicity, ability to generate high density and large area plasma at low pressure, has been widely used in many fields. From the point view of coil optimization, influence of different coil geometries on plasma performances has been studied.A transformer model, in which the plasma is considered as the secondary coil, is applied for analyzation and calculation. The results indicate the source coil with a higher Q value will exhibit a higher power coupling efficiency.The effects of different coil geometries on plasma performances have been experimentally studied using four different coils with different turns. It is shown that the single-turn coil, due to its low inductance, can not generate plasmas. A coil with a thin Ag layer will have a lower resistance and resultantly a higher power coupling efficiency; for different coils, the comparison of power coupling efficiencies should considerate both Q values and resistance values. Power coupling efficiency increases and exhibits a saturated tendency with the increasing of input power, which is in accordance with the transformer model. In H-mode discharges, power coupling efficiency increases with the increasing of pressure; while in E-mode discharges, power coupling efficiency doesn't vary with the variation of pressure. At the same power and pressure parameters, the plasma densities for two-turn and three-turn coils are three times of that for single-turn coil.Through this work, some valuable conclusions for ICP source design have been achieved.