Expanding the operating space for pulsed ICP plasmas through matchless power delivery

Abstract

This work details how the implementation of a matchless RF power delivery system broadens the operating conditions for pulsed, inductively coupled plasmas (ICPs). Using a high-frequency matchless RF generator, notably faster electron density rise times and higher peak power densities, compared with traditionally matched ICP systems, were achieved. The generator couples power to the plasma source through a resonant circuit design with minimal dissipative elements in the generator’s final amplification phase, enabling high efficiency power coupling to the dissipative plasma loaded antenna. Time-resolved electron density measurements taken using a microwave resonator (hairpin) probe showed the plasma getting to the same target, steady-state density more than twice as fast. This generator is capable of very short duty cycles <0.1% which enables peak power densities up to 3 W cm-3, higher than some industrial ICP sources. These operating capabilities open new avenues for plasma processing applications, particularly low duty cycle pulsed power processes with higher electron densities.