Surface Modification by Plasma-Based Processes

A special issue of Coatings (ISSN 2079-6412). This special issue belongs to the section "Surface Characterization, Deposition and Modification".

Deadline for manuscript submissions: closed (30 July 2021) | Viewed by 31880

Special Issue Editor


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Guest Editor
Korea Institute of Fusion Energy, Plasma E. I. Convergence Research Center, 814-2, Osikdo-dong, Gunsan-si, Jeonbuk 54004, Korea
Interests: plasma diagnostics; plasma nitridation; surface modification

Special Issue Information

Dear Colleagues,

I would like to invite you to submit your work to a Special Issue on “Surface Modification by Plasma-Based Processes”. Plasma-based processing technologies are of vital importance to several of the largest manufacturing industries in the world. Most recently, plasma processing technology has been used as a useful tool to modify the surface properties of different materials via the interaction of energetic particles (ions, electrons, neutrals) and photons with surface exposed to plasmas.

A great variety of plasmas originate from the possibility to vary their parameters: chemical composition, pressure, power, and electromagnetic field structure of reactor configuration. However, all plasma processes are currently used in the industry with an incomplete understanding of the coupled chemical and physical properties of the plasma involved. Thus, they are often “non-predictive”, and hence, it is not possible to alter the manufacturing process without the risk of considerable product loss. Only a more comprehensive understanding of such processes will allow models of such plasmas to be constructed that in turn can be used to design the next generation of plasma reactors. Developing such models and gaining a detailed understanding of the physical and chemical mechanisms within plasma systems is intricately linked to our knowledge of the key interactions within the plasma and, thus, the status of the database for characterizing electron, ion, and photon interactions with those atomic and molecular species within the plasma and knowledge of both the cross-sections and reaction rates for such collisions, both in the gaseous phase and on the surfaces of the plasma reactor.

Thus, the aim of this Special Issue is to present the state of the art of plasma technologies for surface modification based on the fundamental approach through a combination of original research papers, short communications, and review articles from leading research groups.

In particular, the topics of interest include:

  • Fundamental understanding of plasma surface interaction (plasma simulation, diagnostics, A+M/PMI, analysis and control, etc.);
  • Characterization and development of plasma technologies for surface modifications;
  • Applications in various industries.

Dr. Jongsik Kim
Guest Editor

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All submissions that pass pre-check are peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Coatings is an international peer-reviewed open access monthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2600 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • plasma simulation
  • diagnostics
  • data analysis
  • atomic and molecular data
  • AI/ML technologies for plasma
  • plasma surface modifications

Published Papers (11 papers)

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Research

15 pages, 2825 KiB  
Article
Exploring Emerging Technologies with Analysis of Bibliographic Data Focused on Plasma Surface Treatment
by Youbean Kim
Coatings 2021, 11(11), 1291; https://doi.org/10.3390/coatings11111291 - 25 Oct 2021
Cited by 3 | Viewed by 1575
Abstract
Research trends and emerging technologies were explored through the Web of Science (WoS) literature of the last decade in relation to plasma technology, especially plasma surface treatment, widely used in all industries. For this, a network analysis using country and author keywords and [...] Read more.
Research trends and emerging technologies were explored through the Web of Science (WoS) literature of the last decade in relation to plasma technology, especially plasma surface treatment, widely used in all industries. For this, a network analysis using country and author keywords and emerging technology search algorithms, with regard to novelty, fast growth and impact, were used. As a result, we derived 40 keywords in terms of novelty and fast growth. Additionally, with these keywords, we traced the impact based on the citation relationships. Finally, nine keywords which were analyzed to contain many new technological issues were identified by deriving the author keywords included in the relevant documents. It is expected that the new technology fields derived from this paper can contribute to establishing a preemptive R&D strategy. Full article
(This article belongs to the Special Issue Surface Modification by Plasma-Based Processes)
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13 pages, 2727 KiB  
Article
Machine Learning Prediction of Electron Density and Temperature from Optical Emission Spectroscopy in Nitrogen Plasma
by Jun-Hyoung Park, Ji-Ho Cho, Jung-Sik Yoon and Jung-Ho Song
Coatings 2021, 11(10), 1221; https://doi.org/10.3390/coatings11101221 - 06 Oct 2021
Cited by 7 | Viewed by 2670
Abstract
We present a non-invasive approach for monitoring plasma parameters such as the electron temperature and density inside a radio-frequency (RF) plasma nitridation device using optical emission spectroscopy (OES) in conjunction with multivariate data analysis. Instead of relying on a theoretical model of the [...] Read more.
We present a non-invasive approach for monitoring plasma parameters such as the electron temperature and density inside a radio-frequency (RF) plasma nitridation device using optical emission spectroscopy (OES) in conjunction with multivariate data analysis. Instead of relying on a theoretical model of the plasma emission to extract plasma parameters from the OES, an empirical correlation was established on the basis of simultaneous OES and other diagnostics. Additionally, we developed a machine learning (ML)-based virtual metrology model for real-time Te and ne monitoring in plasma nitridation processes using an in situ OES sensor. The results showed that the prediction accuracy of electron density was 97% and that of electron temperature was 90%. This method is especially useful in plasma processing because it provides in-situ and real-time analysis without disturbing the plasma or interfering with the process. Full article
(This article belongs to the Special Issue Surface Modification by Plasma-Based Processes)
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16 pages, 11909 KiB  
Article
Theoretical Analysis of Si2H6 Adsorption on Hydrogenated Silicon Surfaces for Fast Deposition Using Intermediate Pressure SiH4 Capacitively Coupled Plasma
by Hwanyeol Park and Ho Jun Kim
Coatings 2021, 11(9), 1041; https://doi.org/10.3390/coatings11091041 - 29 Aug 2021
Cited by 7 | Viewed by 2876
Abstract
The rapid and uniform growth of hydrogenated silicon (Si:H) films is essential for the manufacturing of future semiconductor devices; therefore, Si:H films are mainly deposited using SiH4-based plasmas. An increase in the pressure of the mixture gas has been demonstrated to [...] Read more.
The rapid and uniform growth of hydrogenated silicon (Si:H) films is essential for the manufacturing of future semiconductor devices; therefore, Si:H films are mainly deposited using SiH4-based plasmas. An increase in the pressure of the mixture gas has been demonstrated to increase the deposition rate in the SiH4-based plasmas. The fact that SiH4 more efficiently generates Si2H6 at higher gas pressures requires a theoretical investigation of the reactivity of Si2H6 on various surfaces. Therefore, we conducted first-principles density functional theory (DFT) calculations to understand the surface reactivity of Si2H6 on both hydrogenated (H-covered) Si(001) and Si(111) surfaces. The reactivity of Si2H6 molecules on hydrogenated Si surfaces was more energetically favorable than on clean Si surfaces. We also found that the hydrogenated Si(111) surface is the most efficient surface because the dissociation of Si2H6 on the hydrogenated Si(111) surface are thermodynamically and kinetically more favorable than those on the hydrogenated Si(001) surface. Finally, we simulated the SiH4/He capacitively coupled plasma (CCP) discharges for Si:H films deposition. Full article
(This article belongs to the Special Issue Surface Modification by Plasma-Based Processes)
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11 pages, 2543 KiB  
Article
Comprehensive Data Collection Device for Plasma Equipment Intelligence Studies
by Yong-Hyun Kim, Ji-Ho Cho, Jong-Sik Kim, Jong-Bae Park, Dae-Chul Kim and Young-Woo Kim
Coatings 2021, 11(9), 1025; https://doi.org/10.3390/coatings11091025 - 26 Aug 2021
Cited by 3 | Viewed by 2245
Abstract
In this study, various diagnostic tools were constructed and plasma factors measured to evaluate the intelligence of plasma process equipment. We used an ICP (Inductively Coupled Plasma) reactor with a radio frequency (RF) power of 13.56 MHz, a power of 400 to 800 [...] Read more.
In this study, various diagnostic tools were constructed and plasma factors measured to evaluate the intelligence of plasma process equipment. We used an ICP (Inductively Coupled Plasma) reactor with a radio frequency (RF) power of 13.56 MHz, a power of 400 to 800 W, and a pressure of 10 to 30 mTorr. Plasma parameters such as electron density (ne), electron temperature (Te), plasma potential (Vp), and floating potential (Vf) were measured using several instruments (VI probe and mass/energy analyzer, etc.) and subsequently analyzed. Regression analysis was performed to correlate the measured data with the plasma parameters. As a result, the plasma density (ne) and temperature (Te) were observed to be in good agreement with the non-invasive measurement results. In particular, the VI probes were highly correlated with almost all the measured plasma parameters. Therefore, the results of this study provide a basis for the estimation of plasma parameters using non-invasive measurement techniques. Full article
(This article belongs to the Special Issue Surface Modification by Plasma-Based Processes)
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16 pages, 16065 KiB  
Article
Computational Fluid Dynamics Analysis of Particle Deposition Induced by a Showerhead Electrode in a Capacitively Coupled Plasma Reactor
by Ho Jun Kim and Jung Hwan Yoon
Coatings 2021, 11(8), 1004; https://doi.org/10.3390/coatings11081004 - 23 Aug 2021
Cited by 1 | Viewed by 5054
Abstract
Defect formation in the deposition of thin films for semiconductors is not yet sufficiently understood. In a showerhead-type capacitively coupled plasma (CCP) deposition reactor, the showerhead acts as both the gas distributor and the electrode. We used computational fluid dynamics to investigate ways [...] Read more.
Defect formation in the deposition of thin films for semiconductors is not yet sufficiently understood. In a showerhead-type capacitively coupled plasma (CCP) deposition reactor, the showerhead acts as both the gas distributor and the electrode. We used computational fluid dynamics to investigate ways to enhance cleanliness by analyzing the particle deposition induced by the showerhead electrode in a CCP reactor. We analyzed particle transport phenomena using a three-dimensional complex geometry, whereas SiH4/He discharges were simulated in a two-dimensional simplified geometry. The process volume was located between the RF-powered showerhead and the grounded heater. We demonstrated that the efficient transportation of particles with a radius exceeding 1 μm onto the heater is facilitated by acceleration inside the showerhead holes. Because the available space in which to flow inside the showerhead is constricted, high gas velocities within the showerhead holes can accelerate particles and lead to inertia-enhanced particle deposition. The effect of the electrode spacing on the deposition of particles generated in plasma discharges was also investigated. Smaller electrode spacing promoted the deposition of particles fed from the showerhead on the heater, whereas larger electrode spacing facilitated the deposition of particles generated in plasma discharges on the heater. Full article
(This article belongs to the Special Issue Surface Modification by Plasma-Based Processes)
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17 pages, 5986 KiB  
Article
Enhancement of Cleanliness and Deposition Rate by Understanding the Multiple Roles of the Showerhead Electrode in a Capacitively Coupled Plasma Reactor
by Ho Jun Kim
Coatings 2021, 11(8), 999; https://doi.org/10.3390/coatings11080999 - 21 Aug 2021
Cited by 3 | Viewed by 3281
Abstract
Increasing the productivity of a showerhead-type capacitively coupled plasma (CCP) reactor requires an in-depth understanding of various physical phenomena related to the showerhead, which is not only responsible for gas distribution, but also acts as the electrode. Thus, we investigated how to enhance [...] Read more.
Increasing the productivity of a showerhead-type capacitively coupled plasma (CCP) reactor requires an in-depth understanding of various physical phenomena related to the showerhead, which is not only responsible for gas distribution, but also acts as the electrode. Thus, we investigated how to enhance the cleanliness and deposition rate by studying the multiple roles of the showerhead electrode in a CCP reactor. We analyzed the gas transport in a three-dimensional complex geometry, and the SiH4/He discharges were simulated in a two-dimensional simplified geometry. The process volume was installed between the showerhead electrode (radio frequency powered) and the heater electrode (grounded). Our aim of research was to determine the extent to which the heated showerhead contributed to increasing the deposition rate and to reducing the size of the large particles generated during processing. The temperature of the showerhead was increased to experimentally measure the number of particles transported onto the heater to demonstrate the effects thereof on the decrease in contamination. The number of particles larger than 45 nm decreased by approximately 93% when the showerhead temperature increased from 373 to 553 K. Full article
(This article belongs to the Special Issue Surface Modification by Plasma-Based Processes)
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8 pages, 2133 KiB  
Article
Ion and Radical Characteristics (Mass/Energy Distribution) of a Capacitively Coupled Plasma Source Using Plasma Process Gases (CxFy)
by Yong-Hyun Kim, Jong-Sik Kim, Dae-Chul Kim, Young-Woo Kim, Jong-Bae Park, Duk-Sun Han and Mi-Young Song
Coatings 2021, 11(8), 993; https://doi.org/10.3390/coatings11080993 - 20 Aug 2021
Cited by 2 | Viewed by 3036
Abstract
We constructed a capacitively coupled plasma (CCP) source and installed various diagnostic tools to perform process diagnosis using a plasma process gas (CxFy). We obtained the energy and mass distributions of the ions and radicals from Ar, C4F8/Ar, and [...] Read more.
We constructed a capacitively coupled plasma (CCP) source and installed various diagnostic tools to perform process diagnosis using a plasma process gas (CxFy). We obtained the energy and mass distributions of the ions and radicals from Ar, C4F8/Ar, and C4F6/Ar plasmas. The energy distribution of the ions incident on the substrate was controlled using the self-bias voltage, and the ion energy was found to be inversely proportional to the mass. The measured species and density of the ions and radicals can help understand plasma process results as they provide information about the ions and radicals incident on the substrate. Full article
(This article belongs to the Special Issue Surface Modification by Plasma-Based Processes)
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12 pages, 2941 KiB  
Article
Silicon Carbide Wafer Machining by Using a Single Filament Plasma at Atmospheric Pressure
by Seungryul Yoo, Dong Chan Seok, Kang Il Lee, Yong Ho Jung and Yong Sup Choi
Coatings 2021, 11(8), 958; https://doi.org/10.3390/coatings11080958 - 11 Aug 2021
Viewed by 2060
Abstract
SiC wafers were etched using a filament plasma of He:NF3:O2 (helium:nitrogen trifluoride:oxygen) mixed gas at atmospheric pressure. When 0.5–2 sccm of NF3 was mixed to 2 slm of He filament plasma, the etch depth and etch rate increased, but [...] Read more.
SiC wafers were etched using a filament plasma of He:NF3:O2 (helium:nitrogen trifluoride:oxygen) mixed gas at atmospheric pressure. When 0.5–2 sccm of NF3 was mixed to 2 slm of He filament plasma, the etch depth and etch rate increased, but there was little change in the etch width as the NF3 mixing amount increased. The increment of the NF3 mixing also suppressed the surface roughening of plasma etching. The addition of O2 to the He-NF3 filament plasma slightly increased the SiC wafer etch rate. When the NF3 mixing amount was 2 sccm, the roughness of the etched surface increased sharply by O2 addition. On the contrary, the NF3 mixing amount was 1 sccm; the addition of O2 reduced the roughness more than that of the pristine. The roughness of the pristine SiC wafer specimens is in the range of Ra 0.7–0.8 nm. After 30 min of etching on a 6 mm by 6 mm square area, the roughness of the etched surface reduced to Ra 0.587 nm, while the etch rate was 2.74 μm/h with a He:NF3:O2 of 2:1:3 (slm:sccm:sccm) filament plasma and 3 mm/s speed of raster scan etch of the optimized roughening suppression etching recipe. Full article
(This article belongs to the Special Issue Surface Modification by Plasma-Based Processes)
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8 pages, 2546 KiB  
Article
Hydrophilic Surface Treatment of Carbon Powder Using CO2 Plasma Activated Gas
by Seungryul Yoo, Dongchan Seok, Yongho Jung and Kiyong Lee
Coatings 2021, 11(8), 925; https://doi.org/10.3390/coatings11080925 - 02 Aug 2021
Cited by 5 | Viewed by 2845
Abstract
Carbon powders exhibit electrical conductivity that causes the powders to agglomerate due to the applied electrostatic forces and discharges capacitance when used for surface treatments with plasma sources. To avoid this obstacle, a non-direct method is used with active gas that is generated [...] Read more.
Carbon powders exhibit electrical conductivity that causes the powders to agglomerate due to the applied electrostatic forces and discharges capacitance when used for surface treatments with plasma sources. To avoid this obstacle, a non-direct method is used with active gas that is generated through plasma. This active gas is in contact with the carbon powder so that the hydrophilic characteristics are formed. It is the carboxyl COO functional group that causes hydrophilic improvement and it is shown to increase in the carbon surface after soft oxidation. The wettability of carbon powder gradually improves with more plasma treatment time. This is shown through a simple water dispersion test. Eventually, the dispersed aqueous solution gradually separates the powder, which either floats or sinks. The sample treated for 60 min is shown to continuously sustain dispersibility in water over a long period of time. Full article
(This article belongs to the Special Issue Surface Modification by Plasma-Based Processes)
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9 pages, 1558 KiB  
Article
Measurement of Ion Energy Distribution and Deposition of Ti Thin Films Using ABPPS Technology on Glass Substrate
by Dae-Chul Kim, Young-Woo Kim, Yong-Hyun Kim, Jong-Bae Park, Jong-Sik Kim and Duk-Sun Han
Coatings 2021, 11(8), 904; https://doi.org/10.3390/coatings11080904 - 28 Jul 2021
Viewed by 1659
Abstract
Ion energy distributions (IEDs) play an important role in material processes and thin film deposition. We developed a newly designed multistep pulsed power supply (modulator) for the asymmetric bipolar pulsed power sputtering (ABPPS) technology and studied the effect of reverse bias voltage in [...] Read more.
Ion energy distributions (IEDs) play an important role in material processes and thin film deposition. We developed a newly designed multistep pulsed power supply (modulator) for the asymmetric bipolar pulsed power sputtering (ABPPS) technology and studied the effect of reverse bias voltage in improving the properties of thin films through Ti deposition. Using an ion energy analyzer, we confirmed IEDs and relative ion intensity under a reverse bias voltage of the modulator at the substrate position. A dense plasma was generated near the sputter target at reverse bias voltages above 300 V. Experiments were conducted by varying the bias voltage applied to the sputter target and the duty cycle of the modulator. Our results demonstrate that the in-house-built ABPPS system can be used to clean the sample surfaces without requiring additional energy sources or substrate bias and that thin films prepared using this system have a smoother surface than those prepared by conventional sputtering. Full article
(This article belongs to the Special Issue Surface Modification by Plasma-Based Processes)
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8 pages, 1241 KiB  
Communication
Atmospheric-Pressure Air Plasma Jet and Its Striation Discharge Mode for Treatment of Thermally Sensitive Materials
by Yong-Cheol Hong
Coatings 2021, 11(7), 866; https://doi.org/10.3390/coatings11070866 - 20 Jul 2021
Cited by 2 | Viewed by 3263
Abstract
A hollow inner electrode covered with a dielectric tube was inserted into an outer electrode and airflow was fed through the inner electrode. The electrodes were then connected to a transformer operated at an alternating voltage with sinusoidal waveform at a frequency of [...] Read more.
A hollow inner electrode covered with a dielectric tube was inserted into an outer electrode and airflow was fed through the inner electrode. The electrodes were then connected to a transformer operated at an alternating voltage with sinusoidal waveform at a frequency of 20 kHz. The resulting discharge is ejected out of the outer electrode from a 0.7 mm hole in the form of a plasma jet into ambient air. The attributes of the discharged plasma jet were evaluated by monitoring the voltage and current behavior and by investigating the optical emissions. The discharge patterns in the atmospheric-pressure air plasma jet in the form of striations could be observed by the naked eye. Furthermore, we reported the striation mechanism by ion acoustic wave propagation by utilizing a simple calculation. Full article
(This article belongs to the Special Issue Surface Modification by Plasma-Based Processes)
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