Evidence of ionic film deposition from single‐filament dielectric barrier discharges in Ar–HMDSO mixtures

Bröcker, Lars; Perlick, Gesa S.; Klages, Claus‐Peter

doi:10.1002/ppap.202000129

Cited by 14 publications

(12 citation statements)

References 68 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The analysis clearly indicates as well that trimethylsilyl cations can be considered to be mainly responsible for the film formation. This result is strongly supported by first experimental results related to a single-filament DBD in Ar-HMDSO mixtures, where pentamethyldisiloxanyl cations, generated from HMDSO via Penning ionization due to collisions with excited argon atoms, are found to be the dominant species to form the film [211]. Thus, the present modeling studies raise the serious question, if the current knowledge of the processes leading to the formation of organosilicon films has to be reconsidered or revised.…”

Section: Resultssupporting

confidence: 78%

Modeling of Atmospheric-Pressure Dielectric Barrier Discharges in Argon with Small Admixtures of Tetramethylsilane

Loffhagen

Becker

Czerny

et al. 2020

Plasma Chem Plasma Process

Self Cite

View full text Add to dashboard Cite

A time-dependent, spatially one-dimensional fluid-Poisson model is applied to analyze the impact of small amounts of tetramethylsilane (TMS) as precursor on the discharge characteristics of an atmospheric-pressure dielectric barrier discharge (DBD) in argon. Based on an established reaction kinetics for argon, it includes a plasma chemistry for TMS, which is validated by measurements of the ignition voltage at the frequency $$f =86.2\, {\hbox{kHz}}$$ f = 86.2 kHz for TMS amounts of up to 200 ppm. Details of both a reduced Ar-TMS reaction kinetics scheme and an extended plasma-chemistry model involving about 60 species and 580 reactions related to TMS are given. It is found that good agreement between measured and calculated data can be obtained, when assuming that 25% of the reactions of TMS with excited argon atoms with a rate coefficient of $$3.0 \times 10^{-16}\, {\hbox{m}^3/\hbox{s}}$$ 3.0 × 10 - 16 m 3 / s lead to the production of electrons due to Penning ionization. Modeling results for an applied voltage $${U}_{{\mathrm{a}},0} = 4\, {\hbox{kV}}$$ U a , 0 = 4 kV show that TMS is depleted during the residence time of the plasma in the DBD, where the percentage consumption of TMS decreases with increasing TMS fraction because only a finite number of excited argon species is available to dissociate and/or ionize the precursor via energy transfer. Main species resulting from that TMS depletion are presented and discussed. In particular, the analysis clearly indicates that trimethylsilyl cations can be considered to be mainly responsible for the film formation.

show abstract

Section: Resultssupporting

confidence: 78%

Modeling of Atmospheric-Pressure Dielectric Barrier Discharges in Argon with Small Admixtures of Tetramethylsilane

Loffhagen

Becker

Czerny

et al. 2020

Plasma Chem Plasma Process

Self Cite

View full text Add to dashboard Cite

show abstract

“…Most of all, the diffusion of ions in strong electric fields, as observed close to RF electrodes, might further enhance the deposition rate at the electrode. [ 89 ] Anyway, the simulation clearly indicates that the transport of film‐forming species depends on the interaction between diffusion and convection. The relation between diffusion coefficient and gas flow velocity depending on p and F (scaling with p / F ) can, thus, be a crucial factor for film growth, which becomes even more important for film‐forming species with low‐sticking coefficients.…”

Section: Resultsmentioning

confidence: 95%

“…[ 93 ] Such ions are discussed to substantially contribute to HMDSO plasma polymerization at conditions deviating from plasma‐state polymerization such as very low pressure or very short residence time, which involve reactions near or at the surface for film growth. [ 52,89 ] The density of smaller ions, however, is limited (see Figure 7a), [ 94 ] resulting in the indicated high uncertainty by calculating Γ i for the kinetic energy flux. Further analysis of the role of ion bombardment in HMDSO plasma polymerization, for example, in stability/aging and plasma polymer topography, strongly depending on plasma−surface interaction, [ 8,18,77 ] is beyond the scope of this study.…”

Section: Resultsmentioning

confidence: 99%

“…[ 67 ] Recently, atmospheric pressure conditions with very short residence times in the plasma zone (~1 ms) and related low conversion indicated PDMSO ions produced by Penning ionization to be mainly responsible for film deposition. [ 89 ] Neutral fragments were hindered to reach the surface requiring much longer diffusion times. Likely, such conditions are no longer representative of plasma‐state polymerization, yet it demonstrates that the ionic route is of importance.…”

Section: Resultsmentioning

confidence: 99%

See 1 more Smart Citation

Plasma polymerization of hexamethyldisiloxane: Revisited

Hegemann

Bülbül

Hanselmann

et al. 2020

Plasma Processes & Polymers

View full text Add to dashboard Cite

Activation reactions of molecules in plasma are investigated using plasma polymerization of hexamethyldisiloxane as a model system for plasma‐state polymerization. Underlying reaction pathways and film‐forming mechanisms are revisited based on a simplified macroscopic approach, considering the average energy available per monomer particle, Epl, in relation to the threshold energy, Eth, which represents an activation barrier for plasma polymerization. Basic principles are discussed involving averaged values for collision frequency, cross‐section, and reaction rate to produce film‐forming species combining macroscopic and microscopic quantities. Considering the energy uptake from the electric field by the electrons, the energy transfer from electrons to monomer molecules, and the conversion into film‐forming species, it is demonstrated that Epl/Eth is equally relevant as the electron energy distribution function for plasma‐chemical activation reactions.

show abstract

“…[ 26 ] Bröcker et al recently deposited a sub‐millimeter width HMDSO thin film “dot” using a single filament in a DBD with a pin‐to‐plate electrode arrangement to study ionic contributions to HMDSO film growth. [ 27 ] However, because of their random nature and short lifetime (≈10–100s ns), the potential of plasma filaments as microreactors for localized deposition has, to our knowledge, not been exploited for localized and large‐scale surface deposition yet. In this work, a DBD with a textured dielectric was used to immobilize plasma filaments in a mixture of Ar and propargyl methacrylate (PMA, a reactive precursor for plasma polymerization) and led to deposition of a thin film with patterned morphologies and wettability contrasts.…”

Section: Introductionmentioning

confidence: 99%

Simple and Scalable Chemical Surface Patterning via Direct Deposition from Immobilized Plasma Filaments in a Dielectric Barrier Discharge

et al. 2022

View full text Add to dashboard Cite

In this work, immobilization of the often unwanted filaments in dielectric barrier discharges (DBD) is achieved and used for one‐step deposition of patterned coatings. By texturing one of the dielectric surfaces, a discharge containing stationary plasma filaments is ignited in a mix of argon and propargyl methacrylate (PMA) in a reactor operating at atmospheric pressure. From PMA, hydrophobic and hydrophilic chemical and topographical contrasts at sub‐millimeter scale are obtained on silicon and glass substrates. Chemical and physical characterizations of the samples are performed by micrometer‐scale X‐ray photoelectron spectroscopy and infrared imaging and by water contact angle and profilometry, respectively. From the latter and additional information from high‐speed imaging of the plasma phase and electrical measurements, it is suggested that filaments, denser in energetic species, lead to higher deposition rate with higher fragmentation of the precursor, while surface discharges igniting outwards the filaments are leading to smoother and slower deposition. This work opens a new route for a one‐step large‐area chemical and morphological patterning of surfaces at sub‐millimeter scales. Moreover, the possibility to separately deposit coatings from filaments and the surrounding plasma phase can be helpful to better understand the processes occurring during plasma polymerization in filamentary DBD.

show abstract

Evidence of ionic film deposition from single‐filament dielectric barrier discharges in Ar–HMDSO mixtures

Cited by 14 publications

References 68 publications

Modeling of Atmospheric-Pressure Dielectric Barrier Discharges in Argon with Small Admixtures of Tetramethylsilane

Modeling of Atmospheric-Pressure Dielectric Barrier Discharges in Argon with Small Admixtures of Tetramethylsilane

Plasma polymerization of hexamethyldisiloxane: Revisited

Simple and Scalable Chemical Surface Patterning via Direct Deposition from Immobilized Plasma Filaments in a Dielectric Barrier Discharge

Contact Info

Product

Resources

About