| In MEMS applications such as chemical analysis and micro ion propulsion systems, miniaturized ICP sources are widely used due to their simplicity, power saving, long life and low process contamination. More importantly, they are much easier to be integrated with other MEMS devices.Inductively Coupled Plasma (ICP) is generated from neutral gas ionized by electrons which are accelerated in strong electromagnetic field generated by a microwave antenna. The magnetic field set a restriction to electrons so they can not go beyond the field area, meanwhile the electric field provide energy to accelerate the electrons to make the neutral gases ionized. Comparing with other high density plasma sources, ICP sources have much simpler structure because they don't need extra magnetic field. Generally, plasma source devices are huge and cost considerable expense, but with the developing of MEMS fabrication process, miniaturization and low power feature of plasma sources have become an issue.In this paper, a microstrip spiral resonator is presented according to equivalent circuit. By carrying out equivalent circuit with extracted plasma-loaded model, modeling, analyzing and optimizing of the planar antenna using MatLab and HFSS, a top-down design flow is proposed to simplify the design process.A microstrip ICP antenna operated at 2.45GHz is designed to verify the theoretical analytic results. Parameters which have impact on the performance of microstrip resonator are also investigated. Coil size is found to have the most significant effect on resonant frequency. The outer diameter of the coil is proved to have a more serious impact. The resonant frequency decreases when outer diameter increases, it also decreases when the dielectric coefficient increases vice versa. The experiment results agree with the theoretical results. The loss of ICP antenna is also investigated, and a self-resonating structure is proposed which can increase the field density by 7 times.
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