Topology-Oriented Design of Inductively-Coupled-Plasma Generators without Matching-Networks, Focusing on Negative-Differential-Resistance

This paper presents a circuit topology-oriented design for an inductively coupled plasma (ICP) generator without a 50-Ω impedance matching network (IMN), targeting remote plasma applications in advanced semiconductor processing. The design addresses two key challenges: the negative differential resistance (NDR) behavior of plasma and the need for soft-switching in high-power DC-AC converters. A voltage-driven, series-resonance, frequency-tracking scheme is identified through comparative analysis of topologies. A 2.7–3.5 MHz, 6 kW prototype demonstrates stable plasma discharge and soft-switching under high-pressure conditions, 10 Torr N₂, confirming its suitability for next-generation remote plasma systems.