AVS 57th International Symposium & Exhibition
    Plasma Science and Technology Tuesday Sessions
       Session PS2-TuA

Paper PS2-TuA11
Inhomogeneous Magnetic Field Interaction with VHF and HF Capacitively Coupled Plasmas

Tuesday, October 19, 2010, 5:20 pm, Room Galisteo

Session: Plasma Sources
Presenter: K. Bera, Applied Materials, Inc.
Authors: K. Bera, Applied Materials, Inc.
S. Rauf, Applied Materials, Inc.
K. Collins, Applied Materials, Inc.
Correspondent: Click to Email
Both electromagnetic and electrostatic power deposition play important role in very high frequency (VHF) capacitively coupled plasma source to determine the plasma spatial profile. The electromagnetic effect enhances the plasma density near the chamber center, while electrostatic and inductive effects increase the density near the electrode edges. The electrostatic effect prevails for high frequency (HF) plasma sources. Secondary electron emission also plays an important role in determining the HF plasma profile. It has been shown earlier that the plasma profile generated due to VHF and HF sources can be modified using static magnetic fields. In this study, we further investigate the interaction of inhomogeneous static magnetic fields with plasmas. Various magnetic coil configurations, such as solenoid, cusp, mirror and dual solenoids, are considered. Our plasma model includes the full set of Maxwell equations in their potential formulation. The equations governing the vector potential, A, are solved in the frequency domain after every cycle for multiple harmonics of the driving frequency. The electron transport coefficients become tensor quantities in the magnetized plasma. The coupled set of equations governing the scalar potential, Φ, and drift-diffusion equations for all charged species are solved implicitly in time. Static magnetic field from dc current sources has been simulated for different coil configurations, and imported to our plasma model. The plasma modeling result shows that radial magnetic field component limits electron loss to the electrodes and locally enhances the electron density. The axial magnetic field component primarily limits plasma diffusion in the radial direction thereby preserving the effect of improved electron confinement by the radial magnetic field component. For VHF plasmas, using solenoid coil, the magnetic field decreases the electron density in the chamber center and the peak in electron density gradually moves to the edge of the lower electrode. For HF plasmas, the peak density near the electrode edge increases with magnetic field. The effect of magnetic field on the plasma profile is enhanced using the cusp configuration. With dual solenoid, the radial and axial components of magnetic field are modified locally using different coil current ratios and directions. Depending on the nature and location of power deposition in the plasma chamber, the plasma profile is modified in different manner using various coil configurations, current directions, and current ratios.