Modulation of plasma uniformity in capacitively coupled plasmas using non-uniform magnetic fields

Based on a two-dimensional axisymmetric plasma fluid model, this study investigates the modulation effect of non-uniform static magnetic fields on plasma uniformity in capacitively coupled plasma (CCP) chambers. Static magnetic fields are generated by arranging DC coils at the top, sidewall, and bottom of the chamber, and the effects of coil number, position, and applied current on the magnetic field distribution and plasma characteristics are systematically examined. The results show that in the absence of a magnetic field, the plasma exhibits a non-uniform distribution characterized by higher density at the edge and lower density at the center. After applying the coil-generated magnetic field, the electron density is significantly enhanced, and increasing the number of coil groups further improves magnetic field coverage and confinement. The cooperative configuration of top–sidewall–bottom multi-coils effectively suppresses radial electron loss and compensates for the radial density non-uniformity inherent in conventional CCP systems. Under 40 mTorr argon discharge conditions, the optimal plasma uniformity is achieved using three groups of sidewall coils at 40 A. By increasing the current to 100 A and adopting a full-chamber multi-coil configuration, the plasma density can be greatly enhanced while maintaining good uniformity. This method provides a low-cost and highly flexible approach for uniformity control in large-area wafer etching and deposition processes.