Remote Plasma Source Chamber Modeling and Generator Design

This article presents the modeling of the plasma load in the vacuum chamber of a remote plasma source (RPS) and its generator is designed and implemented correspondingly. Traditionally, equivalent plasma load modeling usually acquired parameters measured by a Langmuir probe which is hard to conduct and is basically intrusive. A simple method to model the plasma load into frequency and flow rate-related equivalent
RLC
load without a special device is proposed in this article. Two different resonant inverters, which are operated around 400 kHz as an igniter and a sustainer of the plasma source generator, are designed based on the equivalent load. The igniter generates a high voltage of 5 kV with argon gas as a trigger to start the plasma progress and the sustainer provides a maximum power of 2.5 kVA to keep the plasma generating with nitrogen gas. To avoid interruptions of plasma generation under gas flow rate varying from 100 to 600 sccm, a simple proportional-integral (PI) control with frequency modulation on the sustainer to regulate its output current is adopted. Both system design and equivalent load modeling are verified with the simulated and experimental results in this article.