Fundamental studies of plasma applications in microelectronic manufacturing and flames: Fluid mechanics, phase-change, and heat transfer

Low energy plasmas and associated phase change and melt flow of the anode have been modeled using experiments and computational methods. Results were developed in the context of a sample application in microelectronic manufacturing, the Electronic Flame Off (EFO) process.;The experiments were performed in a scaled-up arc chamber that qualitatively reproduce the Electronic Flame Off (EFO) discharge at an enlarged length scale. Experiments involved the design and development of a PC-based control and data acquisition system. Results indicate that voidage increases and the heat affected zone decreases with increasing current.;The computational model consisted of two components: a low energy weakly ionized plasma model and a model for the phase change, flow and heat transfer in the anode.;The plasma model simulated the breakdown of a wire-to-plane gap and the subsequent discharge. The conservation equations for the electron and ion number densities, the electron temperature, and Gauss' law for the self consistent electric field were solved simultaneously. The methodology to model geometrically complex domains with arbitrarily prescribed anode shapes was also developed. Results showed that intense charge sheaths are formed near the anode showing the strong influence of geometry on the discharge. A heat flux minimum was shown to exist at the neck of a spherically tipped anode.;The phase change and flow in the anode were modeled. Phase-change included melting during the discharge and solidification on termination of the discharge. The methodology to model the evolving shape of the melting anode has also been described. Next, the plasma model was coupled to the fluid mechanics/heat transfer model to provide a realistic simulation of the complete process. Results shown for the first time in this dissertation have indicated that the inter-electrode gap decreases and then increases as the melt at the anode tip rolls up due to surface tension.;The theory for modeling electric field effects on flames has been described along with a new self-consistent model. It has been shown that a widely prevalent theory for electric effects on flames is not self-consistent. Results from the new model indicated a smaller magnitude of the electric field effect.