Fundamental study towards a better understanding of low pressure radio-frequency plasmas for industrial applications

Abstract

Two classic radio-frequency (RF) plasmas, i.e., the capacitively and the inductively coupled plasma (CCP and ICP), are widely employed in material processing, e.g., etching and thin film deposition, etc. Since RF plasmas are usually operated in particular circumstances, e.g., low pressures (mTorr ~ Torr), high-frequency electric field (13.56 MHz ~200 MHz), reactive feedstock gases, diverse reactor configurations, etc., a variety of physical phenomena, e.g., electron resonance heating, discharge mode transitions, striated structures, standing wave effects, etc., arise. These physical effects could significantly influence plasma-based material processing. Therefore, understanding the fundamental processes of RF plasma is not only of fundamental interest, but also of practical significance for the improvement of the performance of the plasma sources. In this article, we review the major progresses that have been achieved in the fundamental study on the RF plasmas, and the topics include 1) electron heating mechanism, 2) plasma operation mode, 3) pulse modulated plasma, and 4) electromagnetic effects. These topics cover the typical issues in RF plasma field, ranging from fundamental to application.

Cold plasma application to fresh green leafy vegetables: Impact on microbiology and product quality

“…Electromagnetic waves drive these plasmas at frequencies of 1–100 kHz for kHz or 13.56 MHz or 27 MHz for RF or 2.45 GHz for MW. RF discharges can be generated when the gas is exposed to an oscillating electromagnetic field using an induction coil surrounding the vacuum chamber (inductive discharge) or by separate electrodes mounted on the external surface of the vacuum chamber (capacitive discharge) (Liu et al., 2022). MW discharges are generated by a magnetron that delivers the MWs to the process vacuum chamber (Lebedev, 2015).…”

Frequency-dependent electron power absorption mode transitions in capacitively coupled argon-oxygen plasmas

“…Capacitively coupled plasmas (CCPs) driven by radio frequency (RF) waveforms have a wide range of applications in the semiconductor industry and are basic tools in biomedical applications [1][2][3][4][5]. Study of processing plasmas is driven by the motive of understanding the complex physical and chemical interactions as well as improving performance and control in such systems [6][7][8]. In plasma processing applications electronegative gases are frequently diluted with electropositive gases.…”

“…The computational investigation of the spatio-temporal dynamics of the electron power absorption is based on the Boltzmann term analysis, a computational diagnostic tool, which is capable of providing a complete description of the electron power absorption in CCPs [55,56]. This method, first proposed in [57] and later revisited in [58], has recently been applied to CCPs under various conditions: in inert gases [8,55,56,[59][60][61][62][63], in electronegative gases [36,54,64,65], in CCPs at atmospheric pressure [66], and in magnetized CCPs as well [46,[67][68][69].…”

Speeding-up direct implicit particle-in-cell simulations in bounded plasma by obtaining future electric field through explicitly propulsion of particles

“…Low-temperature bounded plasmas, such as capacitively coupled plasmas (CCPs) or magnetron plasmas, have generated significant research interest due to their applications in film preparation, hi-tech industries, materials surface treatment, and other areas. [1][2][3] Charged particles in plasmas play significant roles in plasma-based material processing. Therefore, researching the particle dynamics and microscopic physical processes in plasma is crucial for optimizing the plasma technological processes.…”