| AVS 65th International Symposium & Exhibition | |
| Plasma Science and Technology Division | Friday Sessions |
| Session PS-FrM |
| Session: | Plasma Modeling |
| Presenter: | Kallol Bera, Applied Materials |
| Authors: | K. Bera, Applied Materials X. Li, Applied Materials S. Rauf, Applied Materials K.S. Collins, Applied Materials |
| Correspondent: | Click to Email |
Wide area very high frequency (VHF) capacitively coupled plasmas (CCP) are used for materials processing in the semiconductor and display industries. Electromagnetic effects can play significant role in plasma distributions for VHF plasma source. In this study, a VHF linear plasma source is considered, which consists of parallel conductive bars enclosed within ceramic insulator tubes. The linear source is immersed inside the discharge volume, which is enclosed by perfect conductors on the front, back, top, and bottom boundaries except for the input and output ports. Periodic boundary conditions are used on the left and right side boundaries parallel to the conductive bars in order to represent an array of conductive bars over a wide area. A full three dimensional electromagnetic plasma model is used to understand the interactions between the external radio-frequency source and the plasma. The fluid plasma model computes species densities and fluxes, as well as the plasma current density. Drift-diffusion approximation is used for species fluxes in the continuity equations for all charged species. Neutral species densities are determined by solving the continuity equations with diffusion coefficients computed using the Lennard-Jones potentials. The electromagnetic phenomena are fully described by the Maxwell equations with the plasma current density updated from the fluid model. The RF source in the model excites a transverse electromagnetic (TEM) wave through the input ports. The CPML absorbing boundary condition is applied for the termination port that avoids electromagnetic wave reflections back into the plasma. The finite difference time domain (FDTD) technique is used to discretize the Maxwell equations, which are solved explicitly in time. Ar discharge is studied based on the reaction mechanism similar to the previous study [1]. The plasma density distribution is found to be dependent on excitation frequency, pressure and power. The spatial distribution of plasma also depends on excitation phases from the ports as well as the port terminations (using either short or perfect absorption).
1. S. Rauf and M. J. Kushner, J. Appl. Phys. 82, 2805 (1997)