Fluid Modeling of Pulsed Dual-Frequency Capacitively Coupled Plasma
|關鍵字:||脈衝;雙頻率;電容耦合電漿;Pulse;dual frequency;capacitively coupled plasma|
The dual-frequency capacitively coupled plasma (DF-CCP) is a powerful tool for semiconductor processing etching. As compared to conventional single-frequency CCP, DF-CCP have an advantage of separately controlling the ion energy distributions (IEDs) and the ion flux to the substrate electrode. However, with the miniaturization of the microelectronic fabrication, DF-CCP cannot meet the strict requirements of high-aspect-ratio hole or trench etching anymore. Thus, DF-CCP with pulsed operation has been developed and was found to improve etched profile significantly. This thesis numerically investigates pulsed dual-frequency capacitively coupled argon discharge using a parallel 2-D axisymmetric plasma fluid model which has been developed by our group. The governing equations, including continuity equations, momentum equations based on drift-diffusion approximation for all charged species, Poisson equation and electron energy equation, are discretized through semi-implicit cell-centered finite-volume method and are parallelized with domain decomposition using message passing interface (MPI). The objective of the thesis is to study the physical phenomena of plasma in pulsed dual-frequency CCP and to improve the plasma uniformity. The results show that modulating the phase shift between dual-frequency powers and increasing the space of gap can affect plasma uniformity. However, adjusting the radius of grounded electrode is not useful in improving plasma uniformity.