Plasma Uniformity and DC Self-Bias Control Using a Time-Varying Magnetic Field

Uniformity in capacitively coupled plasma (CCP) used for semiconductor processing must be tightly controlled because it directly influences process outcomes. Earlier studies employed static magnetic fields to improve plasma uniformity, but the resulting magnetic asymmetry effect (MAE) altered the DC self-bias, coupling ion energy with plasma uniformity. In this work, we aim to decouple these two parameters by applying a time-varying magnetic field. An electromagnet with tunable frequency and amplitude is integrated into a CCP chamber, and changes in plasma density and DC self-bias are investigated. Increasing the magnetic field frequency progressively suppresses the MAE, causing the DC self-bias to gradually approach its zero-field value. Concurrently, the edge plasma density rises, demonstrating independent control of ion energy and plasma uniformity. Tuning the magnetic field frequency may become a pivotal decoupling parameter in future semiconductor processing.