Influence of a phase-locked RF substrate bias on the E- to H-mode transition in an inductively coupled plasma

Recently a novel concept for collisionless electron heating and plasma generation at low pressures was proposed theoretically (U Czarnetzki and Kh Tarnev, Phys. Plasmas 21 (2014) 123508). It is based on periodically structured vortex fields which produce certain electron resonances in velocity space. A more detailed investigation of the underlying theory is presented in a companion paper (U Czarnetzki, submitted to Plasma Sources Sci. Technol. (2018), arXiv:1806.00505).Here, the new concept is experimentally realized for the first time by the INCA (INductively Coupled Array) discharge. The periodic vortex fields are produced by an array of small planar coils. It is shown that the array can be scaled up to arbitrary dimensions while keeping its electrical characteristics. Stable operation at pressures around and below 1 Pa is demonstrated. The power coupling efficiency is characterized and an increase in the efficiency is observed with decreasing pressure. The spatial homogeneity of the discharge is investigated and the behaviour of the plasma parameters with power and pressure are presented. Linear scaling of the plasma density with power and pressure, typical for conventional inductive discharges, is observed. Most notably, the plasma potential and the corresponding mean ion energy show clear evidence for the presence of super energetic electrons, attributed to stochastic heating. In the stochastic heating mode, the electron distribution function becomes approximately Maxwellian but with increasing pressure it turns to the characteristic local distribution function known from classical inductive discharges. Large area processing or thrusters are possible applications for this new plasma source.

Section: Operation In H-modesupporting

confidence: 90%

“…Very good agreement between the two values is obtained with a deviation of about 20 %. Further, one can also use the measured values of the electron and gas temperatures to verify the validity of (25). The right-hand side is readily obtained with the experimental values in table 2.…”

Section: Influence Of Power and Pressurementioning

confidence: 88%

Inductively coupled array (INCA) discharge

Ahr

Tsankov

Kuhfeld

et al. 2018

“…Note that for H 2 plasmas, increasing P ICP led to a much larger increase in the area under IFEDFs compared to O 2 or N 2 plasmas, which indicated significantly higher plasma densities at the higher P ICP for H 2 plasmas. This could arise from the H 2 plasmas undergoing a transition from capacitive to inductive mode, also reported in the literature as the E to H mode transition which is a hallmark of ICP discharges [60,61]. A characteristic feature of this transition is the significant jump in n o as P ICP is increased from a low to a high value [60,61].…”

Section: Reactive Plasmas For Peald Without and With Rf Substrate Biasingmentioning

confidence: 78%

Energetic ions during plasma-enhanced atomic layer deposition and their role in tailoring material properties

Faraz

Arts

Karwal

et al. 2019

Plasma-enhanced atomic layer deposition (PEALD) has obtained a prominent position in the synthesis of nanoscale films with precise growth control. Apart from the well-established contribution of highly reactive neutral radicals towards film growth in PEALD, the ions generated by the plasma can also play a significant role. In this work, we report on the measurements of ion energy and flux characteristics on grounded and biased substrates during plasma exposure to investigate their role in tailoring material properties. Insights from such measurements are essential toward understanding how a given PEALD process at different operating conditions can be influenced by energetic ions. Ion flux-energy distribution functions (IFEDFs) of reactive plasmas typically used for PEALD (O 2 , H 2 , N 2 ) were measured in a commercial 200 mm remote inductively coupled plasma ALD system equipped with RF substrate biasing. IFEDFs were obtained using a gridded retarding field energy analyzer and the effect of varying ICP power, pressure and bias conditions on the ion energy and flux characteristics of the three reactive plasmas were investigated. The properties of three material examples-TiO x , HfN x and SiN x -deposited using these plasmas were investigated on the basis of the energy and flux parameters derived from IFEDFs. Material properties were analyzed in terms of the total ion energy dose delivered to a growing film in every ALD cycle, which is a product of the mean ion energy, total ion flux and plasma exposure time. The properties responded differently to the ion energy dose depending on whether it was controlled with RF substrate biasing where ion energy was enhanced, or without any biasing where plasma exposure time was increased. This indicated that material properties were influenced by whether or not ion energies exceeded energy barriers related to physical atom displacement or activation of ion-induced chemical reactions during PEALD. Furthermore, once ion energies were enhanced beyond these threshold barriers with RF substrate biasing, material properties became a function of both the enhanced ion energy and the duration for which the ion energy was enhanced during plasma exposure. These results have led to a better insight into the relation between energetic ions and the ensuing material properties, e.g. by providing energy maps of material properties in terms of the ion energy dose during PEALD. It serves to demonstrate how the measurement and control of ion energy and flux characteristics during PEALD can provide a platform for synthesizing nanoscale films with the desired material properties.

“…The RF power inductively coupled to the plasma via the mutual inductance is called the H-mode power transfer from the antenna ICP source, and the RF power coupled to the plasma by capacitive coupling is called the E-mode power transfer [8,9,14]. For the EMCP of these antennas, the transition from E-mode to H-mode can be indistinct [19], because both E-and H-modes co-exist to some degree [8,9,14,70]. } W. The purely inductive coupling (lumped-element) model [31] over-estimates the mode frequencies by ∼0.48 MHz (∼3.6%) and the mode impedance by less than 20%.…”

Section: Plasma Measurements With a Grounded Antennamentioning

confidence: 99%

Electromagnetic, complex image model of a large area RF resonant antenna as inductive plasma source

Guittienne¹,

Jacquier

Howling

et al. 2017

A large area antenna generates a plasma by both inductive and capacitive coupling; it is an electromagnetically coupled plasma source. In this work, experiments on a large area planar RF antenna source are interpreted in terms of a multi-conductor transmission line coupled to the plasma. This electromagnetic treatment includes mutual inductive coupling using the complex image method, and capacitive matrix coupling between all elements of the resonant network and the plasma. The model reproduces antenna input impedance measurements, with and without plasma, on a 1.2 1.2 m 2 antenna used for large area plasma processing. Analytic expressions are given, and results are obtained by computation of the matrix solution. This method could be used to design planar inductive sources in general, by applying the termination impedances appropriate to each antenna type.