Plasma characteristics of fixed and swept frequency power supplies in pulsed inductively coupled plasma

Pulsed inductively coupled plasma (ICP) has been widely used due to its high etching rate, good etching morphology, and small substrate damage. However, how to make the plasma parameters reach the set value smoothly and quickly at the initial stage of pulse is a key challenge. This work experimentally and numerically compares the temporal evolution of plasma parameters, including input power, coil current, and plasma density in different discharge conditions of radio frequency power supply under fixed and swept frequency modes. The results reveal that, under moderate modulation frequencies (500 Hz–2 kHz), the swept frequency mode exhibits a shorter power rise time and faster achievement of the target power across varying pressures, pulsed frequencies, and duty cycles. At extremely low or high frequencies (e.g., 100 Hz or 5 kHz), the difference diminishes. This is because when the pulse frequency is low, the plasma needs to be re-ignited, whereas when the pulse frequency is high, the plasma barely goes out. The key advantage of swept frequency mode lies in its ability to dynamically match impedance by compensating for transient changes in plasma parameters, thereby enhancing power transfer efficiency and discharge stability. This approach holds significant potential for improving the repeatability and controllability of pulsed ICP processes in industrial applications.