| For large area micro-processing, a large area plasma source with low pressure, high density and high uniformity is required. Radio frequency (rf), inductively coupled plasma systems driven at 13.56 MHz are known for their capabilities in generating a high plasma density under low pressure, and for their independent control of ion flux and ion-bombarding energy, which are essential for the next generation of sub-micron material processing. However, when the plasma source is scaled to large size, comparable to the wavelength along the antenna of the rf power supply frequency, the plasma generated is inherently non-uniform due to the standing wave effect. To overcome this difficulty, an inductively coupled, large area plasma source (LAPS), driven by a traveling wave, is designed, constructed, and characterized. This dissertation is a detailed description of the procedure in developing and studying this large area plasma source.; The exciting antenna in LAPS is placed inside the processing chamber, embedded in the plasma, and separated from the plasma by thin quartz tubes for efficient power delivery. In order to obtain a uniform plasma density, a lumped circuit element tuning network is designed and used in the system. In this study, the antenna-plasma system is modeled as a transmission line with its parameters dependent on the system configuration and plasma condition. The transformer model is applied to relate the transmission line parameters with plasma properties, and a traveling wave model is developed to evaluate the requirements for the tuning network to launch a traveling wave under different system configurations and plasma operating conditions. A global model is used to predict the plasma densities and temperatures with different input power and argon gas pressures.; Since real-time voltage monitoring is a key factor to obtain a traveling wave for various plasma conditions and to facilitate the tuning network and matching network adjustments, a multiplexer circuit was developed to display the four spatially separated DC signals in one time-multiplexed oscilloscope channel. The measurements of the plasma properties under various operating conditions are made with Langmuir probes and capacitive probes. The Langmuir probe is used to determine plasma density, electron temperature, and plasma potential, while the capacitive probe is employed to measure the rf plasma potential. (Abstract shortened by UMI.)... |
