Review of inductively coupled plasmas: Nano-applications and bistable hysteresis physics

Abstract

Many different gas discharges and plasmas exhibit bistable states under a given set of conditions, and the history-dependent hysteresis that is manifested by intensive quantities of the system upon variation of an external parameter has been observed in inductively coupled plasmas (ICPs). When the external parameters (such as discharge powers) increase, the plasma density increases suddenly from a low- to high-density mode, whereas decreasing the power maintains the plasma in a relatively high-density mode, resulting in significant hysteresis. To date, a comprehensive description of plasma hysteresis and a physical understanding of the main mechanism underlying their bistability remain elusive, despite many experimental observations of plasma bistability conducted under radio-frequency ICP excitation. This fundamental understanding of mode transitions and hysteresis is essential and highly important in various applied fields owing to the widespread use of ICPs, such as semiconductor/display/solar-cell processing (etching, deposition, and ashing), wireless light lamp, nanostructure fabrication, nuclear-fusion operation, spacecraft propulsion, gas reformation, and the removal of hazardous gases and materials. If, in such applications, plasma undergoes a mode transition and hysteresis occurs in response to external perturbations, the process result will be strongly affected. Due to these reasons, this paper comprehensively reviews both the current knowledge in the context of the various applied fields and the global understanding of the bistability and hysteresis physics in the ICPs. At first, the basic understanding of the ICP is given. After that, applications of ICPs to various applied fields of nano/environmental/energy-science are introduced. Finally, the mode transition and hysteresis in ICPs are studied in detail. This study will show the fundamental understanding of hysteresis physics in plasmas and give open possibilities for applications to various applied fields to find novel control knob and optimizing processing conditions.

Optical Emission Spectroscopic (OES) analysis for diagnostics of electron density and temperature in non-equilibrium argon plasma based on collisional-radiative model

“…microelectronics, semiconductors, material engineering, etc., where low-pressure discharge plasmas have been utilized for a long time with practical levels of industry. For example, in the microelectronics engineering, dry etching processes have been widely applied for more than 30 years for the commercial fabrication of memories [7], where typically, fluorine radicals are generated from fluorocarbon gases in the argon-based low-temperature plasmas like CCP [8,9], ICP [10,11], ECR plasmas [12,13], or others, and applied to material etching out of the substrate. On the other hand, for thin-film deposition processes like photovoltaic-device manufacturing, silicon-based materials are quite often deposited on substrates from the SiH 4 or other siliconcompound gaseous molecules [14,15].…”

Properties of Nitrogen/Silicon Doped Vertically Oriented Graphene Produced by ICP CVD Roll-to-Roll Technology

“…In FE-SEM images of this type of coating the increased VOG density packing and the vertical orientation of pillars may indicate that the electric field, which directs the growth of nanostructures, can be localized above the substrate during the The estimated averaged height of nitrogen-doped VOG coating is~489 nm (Sample N1, Figure A8C) and~528 nm (Sample N2, Figure 4A). In FE-SEM images of this type of coating the increased VOG density packing and the vertical orientation of pillars may indicate that the electric field, which directs the growth of nanostructures, can be localized above the substrate during the plasma process [27,77]. At these conditions in atmosphere at lower N 2 partial pressure, VOG pillars were assembled into nanostructures, consisting of agglomerated columns ( Figure A8D).…”

“…Among the many methods used for VOG preparation, chemical vapor deposition (CVD) has demonstrated great potential for economical mass production, however, it requires elevated temperatures (800-1000 • C) and the costs for industrial manufacturing are high [24][25][26]. VOG growth can be achieved at lower temperatures (<800 • C) if the inductively coupled plasma chemical vapor deposition method (ICP CVD) is used, and it has become a key technique for the synthesis of high-quality coating without material damage and undesired defect formation [27][28][29]. Another advantage of CVD is due to the broad choice of available substrates for VOG preparation (e.g., SiO 2 and Al 2 O 3 [30], Si [31], Ni [32], stainless steel [33][34][35][36], Cu [37][38][39][40], Co [41], Al and TiO 2 [42], Al 2 O 3 [43], and Pt [44][45][46]).…”

“…Accurate control over the gas proportion can determine the type of carbon hybridization (sp 1 , sp 2 or sp 3 ) and crystallinity (amorphous α-C, mono-or polycrystalline carbon), thereby strongly influencing the VOG morphology and structure. However, it is difficult to define a certain precursor gas ratio for all the ICP CVD systems, even of the same type, due to the difference in plasma characteristics and operating conditions [27].…”

UQ eSpace

“…Outside of the aerospace research sector, inductively coupled plasma torches have been used in numerous industrial applications, including plasma sintering, ICP mass spectroscopy and hazardous material destruction. If the reader is interested in further applications, the author would recommend review articles by Lee [28], Okumura [29] and Hopwood [30]. These articles include analysis on nano-applications and plasma etching.…”