Study of Fundamental Plasma Properties in an Inductively Coupled Plasma Device
- Author(s): Han, Jia
- Advisor(s): Gekelman, Walter
- et al.
Radio frequency inductively coupled plasma sources are widely used in low temperature industrial processing. Recent computer simulations and experiments indicate significant improvement in processing results with the use of pulsed plasmas. This thesis reports simultaneous measurements of nearly all plasma and electromagnetic properties of an ICP in three-dimensions under pulsed operation.The plasma density profile is measured by rf compensated Langmuir probes, hairpin probes, and a 60 GHz microwave interferometer. Line integrated electron density measured from these three very distinct diagnostic techniques (interferometer, Langmuir probe, Hairpin resonator probe) shows agreement. Three-axis Bdot probes are used to measure the magnetic field. Inductive plasma current is calculated from measured magnetic field using Ampere’s law. With the observed cylindrical symmetry, the electromagnetic electric field is derived from Bdot data using Faraday's law. The above field and current are used to calculate the inductive power and Poynting vector. A side by side comparison in pulsed plasma operation is presented for two industry-relevant neutral pressures (5 mTorr, 25 mTorr). Distinct plasma evolution is observed with the two cases. The observations from the experiment are explained with the help of a simple lumped element circuit model.