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11 pages, 4177 KiB

Open AccessArticle

Investigation into SiO₂ Etching Characteristics Using Fluorocarbon Capacitively Coupled Plasmas: Etching with Radical/Ion Flux-Controlled

by Won-nyoung Jeong, Young-seok Lee, Chul-hee Cho, In-ho Seong and Shin-jae You

Nanomaterials 2022, 12(24), 4457; https://doi.org/10.3390/nano12244457 - 15 Dec 2022

Cited by 4 | Viewed by 2220

Abstract

SiO₂ etching characteristics were investigated in detail. Patterned SiO₂ was etched using radio-frequency capacitively coupled plasma with pulse modulation in a mixture of argon and fluorocarbon gases. Through plasma diagnostic techniques, plasma parameters (radical and electron density, self-bias voltage) were also [...] Read more.

SiO₂ etching characteristics were investigated in detail. Patterned SiO₂ was etched using radio-frequency capacitively coupled plasma with pulse modulation in a mixture of argon and fluorocarbon gases. Through plasma diagnostic techniques, plasma parameters (radical and electron density, self-bias voltage) were also measured. In this work, we identified an etching process window, where the etching depth is a function of the radical flux. Then, pulse-off time was varied in the two extreme cases: the lowest and the highest radical fluxes. It was observed that increasing pulse-off time resulted in an enhanced etching depth and the reduced etching depth respectively. This opposing trend was attributed to increasing neutral to ion flux ratio by extending pulse-off time within different etching regimes. Full article

(This article belongs to the Special Issue Plasma-Assisted Nanofabrication)

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10 pages, 3256 KiB

Open AccessArticle

Characterization of an Etch Profile at a Wafer Edge in Capacitively Coupled Plasma

by Inho Seong, Jinho Lee, Sijun Kim, Youngseok Lee, Chulhee Cho, Jangjae Lee, Wonnyoung Jeong, Yebin You and Shinjae You

Nanomaterials 2022, 12(22), 3963; https://doi.org/10.3390/nano12223963 - 10 Nov 2022

Cited by 5 | Viewed by 4151

Abstract

Recently, the uniformity in the wafer edge area that is normally abandoned in the fabrication process has become important for improving the process yield. The wafer edge structure normally has a difference of height between wafer and electrode, which can result in a [...] Read more.

Recently, the uniformity in the wafer edge area that is normally abandoned in the fabrication process has become important for improving the process yield. The wafer edge structure normally has a difference of height between wafer and electrode, which can result in a sheath bend, distorting important parameters of the etch, such as ionic properties, resulting in nonuniform etching. This problem nowadays is resolved by introducing the supplemented structure called a focus ring on the periphery of the wafer. However, the focus ring is known to be easily eroded by the bombardment of high-energy ions, resulting in etch nonuniformity again, so that the focus ring is a consumable part and must be replaced periodically. Because of this issue, there are many simulation studies being conducted on the correlation between the sheath structural characteristics and materials of focus rings to find the replacement period, but the experimental data and an analysis based on this are not sufficient yet. In this study, in order to experimentally investigate the etching characteristics of the wafer edge area according to the sheath structure of the wafer edge, the etching was performed by increasing the wafer height (thickness) in the wafer edge area. The result shows that the degree of tilt in the etch profile at the wafer edge and the area where the tilt is observed severely are increased with the height difference between the wafer and electrode. This study is expected to provide a database for the characteristics of the etching at the wafer edge and useful information regarding the tolerance of the height difference for untilted etch profile and the replacement period of the etch ring. Full article

(This article belongs to the Special Issue Plasma-Assisted Nanofabrication)

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11 pages, 3727 KiB

Open AccessArticle

Database Development of SiO₂ Etching with Fluorocarbon Plasmas Diluted with Various Noble Gases of Ar, Kr, and Xe

by Youngseok Lee, Heejung Yeom, Daehan Choi, Sijun Kim, Jangjae Lee, Junghyung Kim, Hyochang Lee and ShinJae You

Nanomaterials 2022, 12(21), 3828; https://doi.org/10.3390/nano12213828 - 29 Oct 2022

Cited by 6 | Viewed by 2131

Abstract

In the semiconductor industry, fluorocarbon (FC) plasma is widely used in SiO₂ etching, with Ar typically employed in the dilution of the FC plasma due to its cost effectiveness and accessibility. While it has been reported that plasmas with other noble gases, [...] Read more.

In the semiconductor industry, fluorocarbon (FC) plasma is widely used in SiO₂ etching, with Ar typically employed in the dilution of the FC plasma due to its cost effectiveness and accessibility. While it has been reported that plasmas with other noble gases, namely Kr and Xe, have distinct physical properties such as electron density and temperature, their implementation into plasma etching has not been sufficiently studied. In this work, we conducted SiO₂ etching with FC plasmas diluted with different noble gases, i.e., FC precursors of C₄F₈ and CH₂F₂ with Ar, Kr, or Xe, under various gas flow rates of each as well as plasma diagnostics for the process interpretation. We show that Ar, Kr, and Xe gas mixtures depend on the FC precursor flow rate and the pattern width in a significantly different manner and we elucidate these findings based on plasma diagnostic results. The results of this work are expected to offer a practical etching database for diverse applications including plasma process engineering and the development of plasma simulation in the semiconductor industry. Full article

(This article belongs to the Special Issue Plasma-Assisted Nanofabrication)

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9 pages, 2713 KiB

Open AccessArticle

Influence of Additive N₂ on O₂ Plasma Ashing Process in Inductively Coupled Plasma

by Ye-Bin You, Young-Seok Lee, Si-Jun Kim, Chul-Hee Cho, In-Ho Seong, Won-Nyoung Jeong, Min-Su Choi and Shin-Jae You

Nanomaterials 2022, 12(21), 3798; https://doi.org/10.3390/nano12213798 - 27 Oct 2022

Cited by 8 | Viewed by 3361

Abstract

One of the cleaning processes in semiconductor fabrication is the ashing process using oxygen plasma, which has been normally used N₂ gas as additive gas to increase the ashing rate, and it is known that the ashing rate is strongly related to [...] Read more.

One of the cleaning processes in semiconductor fabrication is the ashing process using oxygen plasma, which has been normally used N₂ gas as additive gas to increase the ashing rate, and it is known that the ashing rate is strongly related to the concentration of oxygen radicals measured OES. However, by performing a comprehensive experiment of the O₂ plasma ashing process in various N₂/O₂ mixing ratios and RF powers, our investigation revealed that the tendency of the density measured using only OES did not exactly match the ashing rate. This problematic issue can be solved by considering the plasma parameter, such as electron density. This study can suggest a method inferring the exact maximum condition of the ashing rate based on the plasma diagnostics such as OES, Langmuir probe, and cutoff probe, which might be useful for the next-generation plasma process. Full article

(This article belongs to the Special Issue Plasma-Assisted Nanofabrication)

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18 pages, 2706 KiB

Open AccessArticle

Influences of Plasma Plume Length on Structural, Optical and Dye Degradation Properties of Citrate-Stabilized Silver Nanoparticles Synthesized by Plasma-Assisted Reduction

by Tirtha Raj Acharya, Geon Joon Lee and Eun Ha Choi

Nanomaterials 2022, 12(14), 2367; https://doi.org/10.3390/nano12142367 - 11 Jul 2022

Cited by 17 | Viewed by 2003

Abstract

Citrate-capped silver nanoparticles (Ag@Cit NPs) were synthesized by a simple plasma-assisted reduction method. Homogenous colloidal Ag@Cit NPs solutions were produced by treating a

A g N O_{3}

-trisodium citrate-deionized water with an atmospheric-pressure argon plasma jet. The plasma-synthesized Ag@Cit NPs [...] Read more.

Citrate-capped silver nanoparticles (Ag@Cit NPs) were synthesized by a simple plasma-assisted reduction method. Homogenous colloidal Ag@Cit NPs solutions were produced by treating a

A g N O_{3}

-trisodium citrate-deionized water with an atmospheric-pressure argon plasma jet. The plasma-synthesized Ag@Cit NPs exhibited quasi-spherical shape with an average particle diameter of about 5.9−7.5 nm, and their absorption spectra showed surface plasmon resonance peaks at approximately 406 nm. The amount of Ag@Cit NPs increased in a plasma exposure duration-dependent manner. Plasma synthesis of Ag@Cit NPs was more effective in the 8.5 cm plume jet than in the shorter and longer plume jets. A larger amount of Ag@Cit NPs were produced from the 8.5 cm plume jet with a higher pH and a larger number of aqua electrons, indicating that the synergetic effect between plasma electrons and citrate plays an important role in the plasma synthesis of Ag@Cit NPs. Plasma-assisted citrate reduction facilitates the synthesis of Ag@Cit NPs, and citrate-capped nanoparticles are stabilized in an aqueous solution due to their repulsive force. Next, we demonstrated that plasma-synthesized Ag@Cit NPs exhibited a significant degradation of methylene blue dye. Full article

(This article belongs to the Special Issue Plasma-Assisted Nanofabrication)

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19 pages, 5420 KiB

Open AccessArticle

Modeling of Advanced Silicon Nanomaterial Synthesis Approach: From Reactive Thermal Plasma Jet to Nanosized Particles

by Samira Elaissi, Amira Ben Gouider Trabelsi, Fatemah H. Alkallas, Tahani A. Alrebdi and Kamel Charrada

Nanomaterials 2022, 12(10), 1763; https://doi.org/10.3390/nano12101763 - 22 May 2022

Cited by 4 | Viewed by 2323

Abstract

A three-dimensional numerical modelling of a time-dependent, turbulent thermal plasma jet was developed to synthetize silicon nanopowder. Computational fluid dynamics and particle models were employed via COMSOL Multiphysics^®v. 5.4 (COMSOL AB, Stockholm, Sweden) to simulate fluid and particle motion in the [...] Read more.

A three-dimensional numerical modelling of a time-dependent, turbulent thermal plasma jet was developed to synthetize silicon nanopowder. Computational fluid dynamics and particle models were employed via COMSOL Multiphysics^®v. 5.4 (COMSOL AB, Stockholm, Sweden) to simulate fluid and particle motion in the plasma jet, as well as the heat dependency. Plasma flow and particle interactions were exemplified in terms of momentum, energy, and turbulence flow. The transport of nanoparticles through convection, diffusion, and thermophoresis were also considered. The trajectories and heat transfer of both plasma jet fields, and particles are represented. The swirling flow controls the plasma jet and highly affects the dispersion of the nanoparticles. We demonstrate a decrease in both particles’ velocity and temperature distribution at a higher carrier gas injection velocity. The increase in the particle size and number affects the momentum transfer, turbulence modulation, and energy of particles, and also reduces plasma jet parameters. On the other hand, the upstream flame significantly impacts the particle’s behavior under velocity and heat transfer variation. Our findings open the door for examining thermal plasma impact in nanoparticle synthesis, where it plays a major role in optimizing the growth parameters, ensuring high quality with a low-cost technique. Full article

(This article belongs to the Special Issue Plasma-Assisted Nanofabrication)

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14 pages, 4586 KiB

Open AccessArticle

Non-Thermal Plasma Treatment Coupled with a Photocatalyst for Antimicrobial Performance of Ihram Cotton Fabric

by Ahmed Rida Galaly and Nagia Dawood

Nanomaterials 2022, 12(6), 1004; https://doi.org/10.3390/nano12061004 - 18 Mar 2022

Cited by 4 | Viewed by 1802

Abstract

All Muslim pilgrims must wear Ihram clothes during the Hajj and Umrah seasons, which presents a great challenge regarding how to eliminate the spread of microbes attached to the cotton fabric of Ihram from the surrounding environment. Targeted fashion research of the recent [...] Read more.

All Muslim pilgrims must wear Ihram clothes during the Hajj and Umrah seasons, which presents a great challenge regarding how to eliminate the spread of microbes attached to the cotton fabric of Ihram from the surrounding environment. Targeted fashion research of the recent past presents a new industrial treatment, which has led us to study the impact of heat directed from an atmospheric pressure plasma jet (APPJ), coupled with photocatalytic nanomaterials, for the antibacterial treatment of Escherichia coli (E. coli) attached to cotton fabric samples, to improve pollutant remediation. The average rates of heat transfer to the bacterial colonies attached to cotton fabric samples, as a function of the laminar mode, were 230 and 77 mW for dry and wet argon discharges, respectively. The jet temperatures (T_J) and heat transfer (Q_H) decreased more for wet argon discharge than for dry argon discharge. This is because, due to the wettability by TiO₂ photocatalyst concentration dosage increases from 0 to 0.5 g L⁻¹, a proportion of the energy from the APPJ photons is expended in overcoming the bandgap of TiO₂ and is used in the creation of electron–hole pairs. In the Weibull deactivation function used for the investigation of the antibacterial treatment of E. coli microbes attached to cotton fabric samples, the deactivation kinetic rate of E. coli increased from 0.0065 to 0.0152 min⁻¹ as the TiO₂ precursor concentration increased. This means that the sterilization rate increased despite (T_J) and (Q_H) decreasing as the wettability by TiO₂ photocatalyst increases. This may be due to photocatalytic disinfection and the generation of active substances, in addition to the effect of the incident plume of the non-thermal jet. Full article

(This article belongs to the Special Issue Plasma-Assisted Nanofabrication)

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Review

Jump to: Research

32 pages, 3806 KiB

Open AccessReview

Plasma-Assisted Nanofabrication: The Potential and Challenges in Atomic Layer Deposition and Etching

by William Chiappim, Benedito Botan Neto, Michaela Shiotani, Júlia Karnopp, Luan Gonçalves, João Pedro Chaves, Argemiro da Silva Sobrinho, Joaquim Pratas Leitão, Mariana Fraga and Rodrigo Pessoa

Nanomaterials 2022, 12(19), 3497; https://doi.org/10.3390/nano12193497 - 6 Oct 2022

Cited by 5 | Viewed by 4030

Abstract

The growing need for increasingly miniaturized devices has placed high importance and demands on nanofabrication technologies with high-quality, low temperatures, and low-cost techniques. In the past few years, the development and recent advances in atomic layer deposition (ALD) processes boosted interest in their [...] Read more.

The growing need for increasingly miniaturized devices has placed high importance and demands on nanofabrication technologies with high-quality, low temperatures, and low-cost techniques. In the past few years, the development and recent advances in atomic layer deposition (ALD) processes boosted interest in their use in advanced electronic and nano/microelectromechanical systems (NEMS/MEMS) device manufacturing. In this context, non-thermal plasma (NTP) technology has been highlighted because it allowed the ALD technique to expand its process window and the fabrication of several nanomaterials at reduced temperatures, allowing thermosensitive substrates to be covered with good formability and uniformity. In this review article, we comprehensively describe how the NTP changed the ALD universe and expanded it in device fabrication for different applications. We also present an overview of the efforts and developed strategies to gather the NTP and ALD technologies with the consecutive formation of plasma-assisted ALD (PA-ALD) technique, which has been successfully applied in nanofabrication and surface modification. The advantages and limitations currently faced by this technique are presented and discussed. We conclude this review by showing the atomic layer etching (ALE) technique, another development of NTP and ALD junction that has gained more and more attention by allowing significant advancements in plasma-assisted nanofabrication. Full article

(This article belongs to the Special Issue Plasma-Assisted Nanofabrication)

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