Factors influencing ion energy distributions in pulsed inductively coupled argon plasmas

Chen, Zhiying; Longo, Roberto C.; Hummel, Michael; Carruth, Megan; Blakeney, Joel; Ventzek, Peter L. G.; Ranjan, Alok

doi:10.1088/1361-6463/ab8b08

Cited by 3 publications

(3 citation statements)

References 25 publications

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“…The results were shown that the ion energy increased and energy spread from single peaked to bi-modal with the decrease of RF power duty cycle. 140) During transitions of plasma in a pulsed period from a plasma ignition stage to a stable glow stage and to an afterglow period, the ion energy and ion flux were tailored by pulsing waveforms. 141) 2.7.2.…”

Section: 5mentioning

confidence: 99%

Science-based, data-driven developments in plasma processing for material synthesis and device-integration technologies

Kambara

Kawaguchi

Lee

et al. 2022

Jpn. J. Appl. Phys.

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Low-temperature plasma processing technologies is essential for material synthesis, device fabrication, and surface treatment. The development of plasma-related products and services requires an understanding of the multiscale complex behaviors of plasma and the hierarchical integration of plasma generation, energy and mass transports through sheath region, surface reactions, and other processes. The importance of science-based and data-driven approaches to controlling systems is argued. The state-of-the-art of deep learning, machine learning, and artificial intelligence in low-temperature plasma science and technology is reviewed. In this review, the requirements and challenges for plasma parameter prediction and processing recipe discovery are asserted by researchers in the fields of material science and plasma processing. It also outlined a science-based, data-driven approach for development of virtual metrology in plasma processes.

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Section: 5mentioning

confidence: 99%

Science-based, data-driven developments in plasma processing for material synthesis and device-integration technologies

Kambara

Kawaguchi

Lee

et al. 2022

Jpn. J. Appl. Phys.

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Section: Introductionmentioning

confidence: 99%

“…The pulsed df discharge excitation can also provide additional control of plasma parameters, including ion energy. Some results on the ion energy control in a pulsed df ICP discharge are discussed in [9][10][11].As mentioned above, in addition to choosing a suitable plasma system for processing materials, it is equally important to obtain information in "real time" about the plasma process and, preferably, directly about the flux and energy of ions on the surface. Since the direct use of invasive plasma diagnostics is not possible in industrial plasma reactors, diagnostic methods such as "virtual sensors" are being investigated.…”

mentioning

confidence: 99%

‘Virtual IED sensor’ for df rf CCP discharges

Bogdanova¹,

Lopaev²,

Рахимова³

et al. 2021

Plasma Sources Sci. Technol.

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Ion-assisted surface processes are the basis of modern plasma processing. Ion energy distribution (IED) control is critical for precise material modification, especially in atomic-level technologies such as atomic layer etching. Since this control should be done in "real time", it requires "real-time" feedback using fast process sensors. In the general case of an industrial plasma reactor, when direct IED measurement is not possible, the IED can be estimated using the concept of a "virtual IED sensor". In this paper, a similar "virtual IED sensor" is considered using an asymmetric dual-frequency (df) rf CCP discharge as an example. It is based on a fast calculation method of the IED at an rf-biased electrode. This approach uses the experimentally measured sheath voltage waveform and plasma density (or ion flux) as input data, and also includes Monte-Carlo simulation of ion motion in the sheath to take into account the effect of ion-neutral collisions. To validate this approach, experiments were carried out using various plasma diagnostics in several gases: argon and xenon as examples of plasma with atomic ions and nitrogen as an example of plasma with molecular ions. It is shown that in all cases it is possible to obtain an adequate IED estimation, close to the experimental one, in a reasonably short time ( tens of seconds when using a modern PC). The results obtained demonstrate the possibility of using a virtual IED sensor in real plasma processing.So, on the one hand, modern plasma processing requires the development of new plasma approaches and systems to ensure an appropriate level of control. On the other hand, this control requires the development of fast sensors.The dual-frequency (df) rf ICP and CCP discharges are widely used today in plasma surface treatment. The simultaneous use of high-frequency and low-frequency rf voltages is aimed at realizing separate control of ion flux and energy. This idea was presented in the works of Goto in the early 1990s [1,2]. Since then, these discharges have been extensively studied both experimentally and theoretically [3,4]. However, one of the main results of these studies is that the two frequencies are generally coupled and the desired functional separate control can only be achieved over a limited range of discharge parameters (frequencies, pressures, and input powers).The multi-frequency discharge excitation was also investigated [5] to reveal the role of the third frequency in controlling the IED shape [6]. In order to better control the ion energy, some new methods of rf discharge excitation have recently been developed. One of them is the excitation of a symmetric rf CCP discharge with two frequencies (the fundamental frequency and its second harmonic) with a phase shift between them. In this configuration, the dc self-bias voltage appears due to the electrical asymmetry effect (EAE) [7]. This voltage is adjusted by the phase shift value between the two frequencies and is used for additional control of ion energy. This idea was further developed in the so-call...

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Time-resolved ion energy distribution in pulsed inductively coupled argon plasma with/without DC bias

Chen

Blakeney

Carruth

et al. 2022

Journal of Vacuum Science &Amp; Technology B

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Pulsed plasmas have emerged as promising candidates as a means for precise control of ion energy/angle dependent surface processes and surface chemistry during the plasma process, which are key to 3 nm and beyond device fabrication. The ion energy distribution functions (IEDFs) and ion fluxes over a pulsed period are important to understand as they directly influence the feature profile, damage, and selectivity. We have developed an advanced plasma diagnostics (APD) system with advanced pulsing capability, including source, bias, and synchronous pulsing. It is a compact inductively coupled plasma system with a RF source frequency of 13.56 MHz intended to diagnose the general behavior of biased high density plasmas. We report the effect of the pulse frequency (2–10 kHz), RF duty cycle (25%–75%), DC duty cycle (5%–50%), phase lag (50–60 μs), RF power (120–180 W), DC bias voltage (0–150 V), and discharge pressure (20–80 mTorr) on the IEDFs and ion flux over a pulse period on the APD system. The time-resolved IEDFs and ion flux were measured using a retarding field energy analyzer. The ion energy transitions in a pulsed period from a plasma ignition stage to a stable stage and from plasma in a glow period to an afterglow period are studied. The results indicate that the ion energy and ion flux are tailored by RF pulsing and RF-DC pulsing. The time-resolved IEDF demonstrates the merits of pulsing to precisely control ion energy and flux, and the ion energy spread was narrowed by the pulsed plasma.

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Factors influencing ion energy distributions in pulsed inductively coupled argon plasmas

Cited by 3 publications

References 25 publications

Science-based, data-driven developments in plasma processing for material synthesis and device-integration technologies

Science-based, data-driven developments in plasma processing for material synthesis and device-integration technologies

‘Virtual IED sensor’ for df rf CCP discharges

Time-resolved ion energy distribution in pulsed inductively coupled argon plasma with/without DC bias

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