Collaborative Research on Particle-in-Cell Modeling of Materials-Processing Plasmas

Kinetic effects are important in many low-pressure plasma processing applications. Although fluid or hybrid models are computationally efficient, they are often not able to adequately describe electron transport and non-local phenomena. Full kinetic treatment of these plasmas is therefore necessary. We discuss results from our collaborative research on particle-in-cell (PIC) modeling of materials processing plasmas. These projects have been used to understand the physics of several plasma sources, facilitated the development of faster kinetic modeling methodologies, and provided innovative solutions to processing problems. This presentation describes the outcome of some of this research. Plasmas generated by energetic electron beams are known for their low electron temperature. PIC modeling in conjunction with analytical models was used to understand electron transport in magnetized electron beam plasmas. Magnetized capacitively coupled plasmas (CCP) can exhibit instabilities producing non-uniform and rotating structures. PIC simulations of low-pressure magnetized CCPs were used to delineate the limits of stable plasma operation and devise methodologies for extending the stable regime. Pulsing is widely used to control plasma chemistry and ion energy in processing plasmas. Synchronous pulsing in low-pressure dual-frequency CCP was examined to develop strategies to further regulate the plasma during the on and off states. We also discuss methods to accelerate kinetic simulations including semi-implicit PIC, the use of graphical processing units, and hybrid PIC–fluid models.