Thin Fluorocarbon Research Articles

SURFACE PROPERTIES OF FLUOROCARBON COATINGS PRODUCED BY LOW-FREQUENCY PLASMATRON AT ATMOSPHERIC PRESSURE

This paper presents the results of studies conducted on coatings based on thin fluorocarbon films obtained by plasma-enhanced chemical vapor deposition using low-frequency plasmatron and low-temperature plasma at atmospheric pressure. The possibility of forming thin fluorocarbon layers by supplying a cyclohexane/carbon tetrafluoride gas mixture to substrates made of polymeric materials (polyethylene terephthalate and polystyrene) has been demonstrated and the main technological modes of deposition process have been established. The absorption spectra of the obtained coatings were studied, the influence of the gas discharge energy contribution on the concentration of fluorocarbon compounds was established, and the band gap was calculated using the Tauc method. The surface relief of the obtained structures was considered using atomic force microscopy and the root-mean-square deviation of the surface roughness was calculated, which reached a maximum of 36 ± 3 nm. Using the Oliver-Pharr method, the nanohardness and Young's modulus of elasticity of the obtained coatings were calculated, which amounted to 0.447 ± 0.025 and 6.10 ± 0.39 GPa, respectively.

Plasma Etching of SiO2 Contact Holes Using Hexafluoroisopropanol and C4F8

This study presents the feasibility of the use of hexafluoroisopropanol (HFIP) as a substitute to perfluorocarbon (PFC) for the plasma etching of SiO2 to confront the continuous increase in demand for PFC emission reduction. SiO2 etching is conducted in HFIP/Ar and C4F8/Ar plasmas, respectively, and its characteristics are compared. The SiO2 etch rates in the HFIP/Ar plasma are higher compared with those in the C4F8/Ar plasma. The thickness of the steady-state fluorocarbon films formed on the surface of SiO2 are lower in the HFIP/Ar plasma compared with in the C4F8/Ar plasma. Higher SiO2 etch rates and thinner fluorocarbon films in the HFIP/Ar plasma are attributed to the oxygen atoms in HFIP, which generate oxygen radicals that react with the fluorocarbon films to turn into volatile products. Due to the higher dissociation of C-F bonds in CF4 compared with in HFIP, the etch rates of SiO2 in the C4F8/Ar plasma increase more rapidly with the magnitude of the bias voltage compared with those in the HFIP/Ar plasma. The etch profiles of the 200 nm diameter SiO2 contact holes with an aspect ratio of 12 show that fairly anisotropic SiO2 contact hole etching was achieved successfully using the HFIP/Ar plasma.

Ultra-low friction, superhydrophobic, plasma micro-nanotextured fluorinated ethylene propylene (FEP) surfaces

Fluorine-containing polymers have attracted a lot of interest due to their hydrophobic nature, which enables a number of functionalities such as low friction, self-cleaning, anti-sticking, etc. Fluorinated ethylene propylene (FEP) is a copolymer of hexafluoropropylene and tetrafluoroethylene. In contrast to polytetrafluoroethylene (PTFE), FEP is melt-processable using injection molding and it is highly transparent and resistant to sunlight. Here, we transform fluorinated ethylene propylene ( FEP) surfaces to superhydrophobic using plasma processing (i.e. plasma etching with simultaneous micro-nanotexturing followed by plasma deposition). Two different plasma reactors (an inductively coupled reactor and a reactive ion etcher) and different etching conditions are used in order to micro-nanotexture FEP surfaces. Superhydrophobicity is achieved after plasma deposition of a thin (30 nm) fluorocarbon coating. Subsequently, we probe their frictional properties against water drops using a tilting stage. In particular, we demonstrate wetting control of FEP surfaces with water static water contact angle ranging from 95 o to 168 o and hysteresis down to 1–2 o . Video analysis of drops moving on different FEP surfaces shows that water drops exhibit reduced friction as etching time increases so that a hierarchical morphology is created. This is achieved using both plasma reactors, whereas the optimum performance is observed for the 10 min etched surface in a inductively coupled plasma reactor in which friction force becomes 0.7–1 μN, which corresponds to an ultra-low dynamic coefficient of friction (at least one order of magnitude lower to that of untreated FEP). • Plasma Processing for wetting control of FEP surfaces. • Superhydrophobic FEP surfaces are demonstrated. • Water drops move with reduced friction on SH FEP surfaces. • Coefficient of friction is reduced to 0.007 for SH FEP surfaces.

Significantly Reduced Secondary-Electron-Yield of Aluminum Sheet with Fluorocarbon Coating

In this work, the surface of Al sheet was coated with a fluorocarbon (FC) thin film by radio frequency (RF) sputtering of polytetrafluoroethylene (PTFE) to investigate the influence of dielectric coatings on the secondary electron yield (SEY) behavior of Al sheets. Atomic-force microscopy (AFM) and energy-dispersive spectroscopy (EDS) were employed to identify the surface topographies and elemental contents of the samples with FC coatings. Water contact angle (WCA) measurements were performed to characterize the surface tension as well as the polar and dispersion components of the samples’ surface. The secondary electron- mission (SEE) behavior of the samples was determined by measuring the SEY coefficients in an ultra-high vacuum chamber with three electron guns. The experimental results indicated that the longer sputtering time effectively led to the increase in coating thickness and a higher ratio of F/C, as well as the continued decrease of surface tension. A quite thin FC coating of about 11.3 nm on Al sheet resulted in the value of maximum SEY (δmax) dropping from 3.02 to 1.85. The further increase in coating thickness beneficially decreased δmax down to 1.60, however, at the cost of a ten-fold thicker coating (ca. 113 nm). It is found that increasing the coating thickness contributes to reducing SEY coefficients as well as suppressing SEE. The results are expected to guide the design of dielectric-coating for SEY reduction as well as multipactor suppression on Al.

Characterizing fluorocarbon assisted atomic layer etching of Si using cyclic Ar/C4F8 and Ar/CHF3 plasma.

With the increasing interest in establishing directional etching methods capable of atomic scale resolution for fabricating highly scaled electronic devices, the need for development and characterization of atomic layer etching processes, or generally etch processes with atomic layer precision, is growing. In this work, a flux-controlled cyclic plasma process is used for etching of SiO2 and Si at the Angstrom-level. This is based on steady-state Ar plasma, with periodic, precise injection of a fluorocarbon (FC) precursor (C4F8 and CHF3) and synchronized, plasma-based Ar+ ion bombardment [D. Metzler et al., J. Vac. Sci. Technol., A 32, 020603 (2014) and D. Metzler et al., J. Vac. Sci. Technol., A 34, 01B101 (2016)]. For low energy Ar+ ion bombardment conditions, physical sputter rates are minimized, whereas material can be etched when FC reactants are present at the surface. This cyclic approach offers a large parameter space for process optimization. Etch depth per cycle, removal rates, and self-limitation of removal, along with material dependence of these aspects, were examined as a function of FC surface coverage, ion energy, and etch step length using in situ real time ellipsometry. The deposited FC thickness per cycle is found to have a strong impact on etch depth per cycle of SiO2 and Si but is limited with regard to control over material etching selectivity. Ion energy over the 20-30 eV range strongly impacts material selectivity. The choice of precursor can have a significant impact on the surface chemistry and chemically enhanced etching. CHF3 has a lower FC deposition yield for both SiO2 and Si and also exhibits a strong substrate dependence of FC deposition yield, in contrast to C4F8. The thickness of deposited FC layers using CHF3 is found to be greater for Si than for SiO2. X-ray photoelectron spectroscopy was used to study surface chemistry. When thicker FC films of 11 Å are employed, strong changes of FC film chemistry during a cycle are seen whereas the chemical state of the substrate varies much less. On the other hand, for FC film deposition of 5 Å for each cycle, strong substrate surface chemical changes are seen during an etching cycle. The nature of this cyclic etching with periodic deposition of thin FC films differs significantly from conventional etching with steady-state FC layers since surface conditions change strongly throughout each cycle.

Superhydrophobic Paper by Facile and Fast Atmospheric Pressure Plasma Etching

Superhydrophobic and to some extent oleophobic paper surfaces are prepared using atmospheric pressure plasma etching. A novel dielectric barrier discharge operating in helium–oxygen mixture is used to rapidly etch organic material from paper surface and create hierarchical topography and subsequently a thin fluorocarbon film is deposited to modify the surface energy. The enhancement of surface topography is achieved via the selective removal of organic matter over inorganic calcium carbonate (calcite) fillers that co-exist in paper. The process led to the fabrication of roll-off superhydrophobic paper with water contact angles >150° and hysteresis <10° for all samples treated over 2 min with no deterioration of paper quality. Further treatment over 8 min resulted also in diiodomethane repellent surfaces.

Fluorocarbon based atomic layer etching of Si3N4 and etching selectivity of SiO2 over Si3N4

Angstrom-level plasma etching precision is required for semiconductor manufacturing of sub-10 nm critical dimension features. Atomic layer etching (ALE), achieved by a series of self-limited cycles, can precisely control etching depths by limiting the amount of chemical reactant available at the surface. Recently, SiO2 ALE has been achieved by deposition of a thin (several Angstroms) reactive fluorocarbon (FC) layer on the material surface using controlled FC precursor flow and subsequent low energy Ar+ ion bombardment in a cyclic fashion. Low energy ion bombardment is used to remove the FC layer along with a limited amount of SiO2 from the surface. In the present article, the authors describe controlled etching of Si3N4 and SiO2 layers of one to several Angstroms using this cyclic ALE approach. Si3N4 etching and etching selectivity of SiO2 over Si3N4 were studied and evaluated with regard to the dependence on maximum ion energy, etching step length (ESL), FC surface coverage, and precursor selection. Surface chemistries of Si3N4 were investigated by x-ray photoelectron spectroscopy (XPS) after vacuum transfer at each stage of the ALE process. Since Si3N4 has a lower physical sputtering energy threshold than SiO2, Si3N4 physical sputtering can take place after removal of chemical etchant at the end of each cycle for relatively high ion energies. Si3N4 to SiO2 ALE etching selectivity was observed for these FC depleted conditions. By optimization of the ALE process parameters, e.g., low ion energies, short ESLs, and/or high FC film deposition per cycle, highly selective SiO2 to Si3N4 etching can be achieved for FC accumulation conditions, where FC can be selectively accumulated on Si3N4 surfaces. This highly selective etching is explained by a lower carbon consumption of Si3N4 as compared to SiO2. The comparison of C4F8 and CHF3 only showed a difference in etching selectivity for FC depleted conditions. For FC accumulation conditions, precursor chemistry has a weak impact on etching selectivity. Surface chemistry analysis shows that surface fluorination and FC reduction take place during a single ALE cycle for FC depleted conditions. A fluorine rich carbon layer was observed on the Si3N4 surface after ALE processes for which FC accumulation takes place. The angle resolved-XPS thickness calculations confirmed the results of the ellipsometry measurements in all cases.

Deposition of fluorocarbon film with 1,1,1,2-tetrafluoroethane pulsed plasma polymerization

The fluorocarbon films were synthesized by radio frequency pulsed 1, 1, 1, 2-tetrafluoroethane plasma polymerization using various duty cycles. The deposition rates and water contact angles were examined for radio frequency pulsed plasma polymerized fluorocarbon films. The film surface properties were also determined by Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy and scanning electron microscopy. For varying duty cycle from 100% to 10% in pulsed plasma process, the plasma polymerized film drastically changed the surface property. Specifically, it has been observed that modulated plasmas with the proper duty cycle of 10% lead to the formation of the super-hydrophobic film by static water contact angle value of 150°. The surface properties of fluorocarbon films were determined as the Cassie state. In the transmittance, UV–VIS transmission spectra showed that these radio frequency pulsed plasma polymerized coatings were transparent in visible light region. By adjusting duty cycles in relation to radio frequency pulsed plasma polymerization, the hydrophobicity of the resulting thin fluorocarbon films could be tuned.

Hierarchical, Plasma Nanotextured, Superamphiphobic Polymeric Surfaces

A facile, mass production amenable, rapid method for making superamphiphobic / amphiphobic surfaces by random plasma nanotexturing of polymers in plasmas is presented. Plasma etched and simultaneously randomly roughened (nanotextured) polymethylmethacrylate (PMMA) Polyether-ether-ketone (PEEK), Cyclic-olefin-copolymer (COC) and Polydimethylsiloxane (PDMS) substrates show hierarchical roughness and complex high-aspect-ratio morphology. Here, they are investigated as superamphiphilic surfaces after plasma etching or superamphiphobic surfaces, after plasma deposition of a thin fluorocarbon film following plasma etching. We show that polymer surfaces etched in oxygen (PMMA, PEEK, COC) or SF6 (PDMS) plasma for few minutes (with texture height< 600nm) exhibit excellent superamphiphobic behaviour, while surfaces treated for longer time show porous-like filamental morphology (filaments several microns height), which is coalesced and stabilized upon wetting, allowing their potential long-term use. Superamphiphobic / amphiphobic behaviour is observed in all cases.

Hierarchical, Plasma Nanotextured, Robust Superamphiphobic Polymeric Surfaces Structurally Stabilized Through a Wetting–drying Cycle

AbstractPlasma etched and simultaneously randomly roughened (nanotextured) polymethylmethacrylate (PMMA) substrates show hierarchical roughness and complex high‐aspect‐ratio morphology. Here, they are investigated as superamphiphobic surfaces, after plasma deposition of a thin fluorocarbon film. Inspired by the need to allow their “real world” use, we explore two major stability issues of such superamphiphobic surfaces: (i) the structural stability of the nanotexture against capillary and adhesion forces during successive wetting–drying cycles, and (ii) the thermodynamic stability (robustness) of these surfaces related to the maximum sustainable pressure of the Cassie–Baxter inhomogeneous wetting state. We show that surfaces etched in oxygen plasma up to 4 min (with texture height ≈600 nm) are stable against successive wetting–drying cycles, while surfaces treated for longer time show highly porous nanofibrous morphology which is coalesced and stabilized upon wetting, allowing their potential long‐term use. Robust superhydrophobic and superoleophobic behavior is observed in drop compression tests with water (on 2, 4, 10 min plasma etched surfaces) and diiodomethane (on 4 and 10 min plasma etched surfaces), respectively, and no wetting transition is observed for these two liquids even at maximum drop compression possible (1.5 kPa). Robust oleophobic behavior with sticky surfaces is observed for 1 and 2 min etching and with diiodomethane without transition to wetted states even upon maximum compression. On the contrary, wetting transition is observed for soya oil upon repeated compression.magnified image

Superior performance of multilayered fluoropolymer films in low voltage electrowetting

The requirement for low operational voltage in electrowetting devices, met using thin dielectrics, is usually connected with serious material failure issues. Dielectric breakdown (visible as electrolysis) is frequently evident slightly beyond the onset of the contact angle saturation. Here, plasma-enhanced chemical vapor deposition (PECVD) is used to deposit thin fluorocarbon films prior to the spin-coating of Teflon® amorphous fluoropolymer. The resulting multilayered hydrophobic top coating improves the electrowetting performance of the stack, by showing high resistance to dielectric breakdown at high applied voltages and for continuous long term application of DC and AC voltage. Leakage current measurements during electrowetting experiments with the proposed composite coating showed that current remains fairly constant at consecutive electrowetting tests in contrast to plain Teflon® coating in which material degradation is evident by a progressive increase in the leakage current after multiple electrowetting tests. Since the proposed composite coating demonstrates increased resistance to material failure and to dielectric breakdown even at thin configurations, its integration in electrowetting devices may impact their reliability, robustness, and lifetime.

SU-8 micropatterning for microfluidic droplet and microparticle focusing

We demonstrate micropatterned surfaces consisting of concentric circles and spirals which can focus an evaporating sessile droplet to a specific location on a surface. We also study the micropattern geometry to focus microparticles contained within the droplet. The micropatterned surfaces are fabricated using the photoresist SU-8. Our process enables the modification of the surface wetting via the formation of smooth trench-like defects in the SU-8 which define the micropatterns; the geometry of these micropatterns determines the droplet/microparticle focusing. It is clearly shown that the introduction of small gaps into the micropatterns promotes microparticle centring due to the modification of the depinning angle of the droplet. We also show that the use of spiral micropatterns promotes microparticle centring. Finally, microparticle focusing can be enhanced by modification of surface wetting via the addition of a thin fluorocarbon hydrophobic layer onto the SU-8.

Preparation and Comparison of Hydrophobic Cotton Fabric Obtained by Direct Fluorination and Admicellar Polymerization of Fluoromonomers

Two different methods of surface modification of cotton fabrics are compared: direct fluorination using elemental fluorine and admicellar polymerization, which uses a surfactant and fluoromonomer system. Sample characterization includes infrared spectroscopy, analysis of mechanical properties, analysis of wetting times, contact angle measurements, scanning electron microscopy, elemental analysis, and atomic force microscopy analysis. Fourier transform infrared spectroscopy and elemental analysis showed the presence of fluorine moieties. For direct fluorinated cotton fabric, the static contact angle was found to be 117°, and for cotton fabric modified by admicellar polymerization, the contact angle was 125°. In all cases, the presence of a very thin fluorocarbon layer on the surface was confirmed, but differences in terms of the amount of fluorochemical formed and in surface structure were also found.

Piezoelectret microphones.

Piezoelectret microphones, a recently described new class of electret microphones, are based on the strong piezoelectric effect of internally charged, cellular polymer films. Such piezoelectret films have a large number of internal voids within the polymer. The upper and lower walls of these voids are oppositely charged. Films of this kind, when metallized on both sides, show high-piezoelectric activity and can be directly used as microphones. Recent work on these transducers has concentrated on stacking of piezoelectret films to improve sensitivity, on directional microphones, and on investigations of new film materials with improved charge stability at elevated temperatures. Stacked transducers have sensitivities proportional to the number of piezoelectret layers. With six layers, values of approximately 15 mV/Pa can be achieved. Directivities include omnidirectional, bidirectional, and cardioid patterns as well as dimensional characteristics. The new materials are based on fluoropolymers. These are, as opposed to the originally used polypropylene, not available in suitable cellular form. However, useful films can be made by fusing thin fluorocarbon films such that an array of small air voids is created between the layers. Transducers consisting of charged films of this kind withstand temperatures of 90 °C without significant loss of sensitivity.

The mechanism of formation and some properties of thin fluorocarbon films deposited onto silicon plates by electron-beam polymerization of hexafluoropropylene from the vapor phase

The results of studying thin fluorocarbon films deposited onto single-crystal silicon plates through electron beam polymerization of hexafluoropropylene from the vapor phase are presented. The films are deposited under the action of an electron beam with an energy of 40 keV at a monomer vapor pressure of 5- 20 hPa. It is shown that plastic solid films consisting of a low-molecular-mass polymer with low thermal stability are formed at a beam current density on the order of 20 μA/cm2, while at current densities on the order of 150 μA/cm2, rigid brittle films of three-dimensional crossl inked polymer are formed with a thermal stability of about 350°C. It is assumed that the films are formed via chain polymerization, which at high current densities, is accompanied by polyrecombination processes leading to efficient chain crosslinking. It is found that polymer clusters are ordered in the course of film formation.

Plasma fluorination of diamond-like carbon surfaces: mechanism and application tonanoimprint lithography

Diamond-like carbon (DLC) films, used as molds for nanoimprint lithography, weretreated with a fluorocarbon-based plasma in order to enhance their anti-adhesionproperties. While ellipsometry and atomic force microscope measurementsshowed negligible changes in thickness and surface roughness after plasmaprocessing, contact angle measurement found fluorine plasma-treated DLCsurfaces to be highly hydrophobic, with surface energy values reduced from∼45 mJ m−2 for untreatedfilms to ∼20–30 mJ m−2 after fluorination. X-ray photoelectron spectroscopy revealed a thin (from∼0.5 to∼3 nm) fluorocarbon layer on the DLC surface. Proposed mechanisms for the formation ofthis layer include two competing processes: etching of DLC and deposition offluorocarbon material, with one or the other mechanism dominant, depending on theplasma conditions. Fluorocarbon plasma-treated DLC molds for nanoimprintlithography were used to pattern sub-20 nm size features with a high degree ofrepeatability, demonstrating an extended lifetime of the anti-adhesion coating.

Fabrication of “Roll-off” and “Sticky” Superhydrophobic Cellulose Surfaces via Plasma Processing

Most of the artificial superhydrophobic surfaces that have been fabricated to date are not biodegradable, renewable, or mechanically flexible and are often expensive, which limits their potential applications. In contrast, cellulose, a biodegradable, renewable, flexible, inexpensive, biopolymer which is abundantly present in nature, satisfies all the above requirements, but it is not superhydrophobic. Superhydrophobicity on cellulose paper was obtained by domain-selective etching of amorphous portions of the cellulose in an oxygen plasma and subsequently coating the etched surface with a thin fluorocarbon film deposited via plasma-enhanced chemical vapor deposition using pentafluoroethane as a precursor. Variation of plasma treatment yielded two types of superhydrophobicity : "roll-off" (contact angle (CA), 166.7 degrees +/- 0.9 degrees ; CA hysteresis, 3.4 degrees +/- 0.1 degrees ) and "sticky" (CA, 144.8 degrees +/- 5.7 degrees ; CA hysteresis, 79.1 degrees +/- 15.8 degrees ) near superhydrophobicity. The nanometer scale roughness obtained by delineating the internal roughness of each fiber and the micrometer scale roughness which is inherent to a cellulose paper surface are robust when compared to roughened structures created by traditional polymer grafting, nanoparticle deposition, or other artificial means.

Superhydrophobic engineering surfaces with tunable air-trapping ability

A versatile hybrid processing method that combines electrostatic deposition of microparticles and subsequent anisotropic plasma etching is described that can generate superhydrophobic engineering surfaces with tunable bimodal roughness and a thin hydrophobic fluorocarbon film. These surfaces exhibit contact angles with water of more than 160° for particle coverage beyond a threshold value. A geometric model based on air-trapping ability is developed to explain this observed threshold value of particle coverage and extended to arbitrary rough surfaces utilizing statistical roughness parameters.

Study of the adhesion of thin plasma fluorocarbon coatings resisting plastic deformation for stent applications

Metallic intravascular stents are medical devices (316L stainless steel) used to support the narrowed lumen of atherosclerotic stenosed arteries. Despite the success of bare metal stents, restenosis remains the main complication after 3–6 months of implantation. To reduce the restenosis rate of bare metal stents, stent coating is an interesting alternative. Firstly, it allows the modification of the surface properties, which is in contact with the biological environment. Secondly, the coating could eventually act as a carrier for drug immobilization and release. Moreover, the in vivo stent implantation requires in situ stent expansion. This mandatory step generates local plastic deformation of up to 25% and may cause coating failures such as cracking and delamination. Fluorocarbon films were selected in this study as a potential stent coating, mainly due to their chemical inertness, high hydrophobicity, protein retention capabilities and thromboresistance properties. The aim of this study was to investigate the adhesion properties of fluorocarbon films of three different thicknesses deposited by plasma polymerization in C2F6/H2 on 316L stainless steel substrates. A previously developed small punch test was used to deform the coated samples. According to atomic force microscopy, field emission scanning electron microscopy and x-ray photoelectron spectroscopy characterizations, among the coatings with different thicknesses studied, only those with a thickness of 36 nm exhibited the required cohesion and interfacial adhesion to resist the stent expansion without cracking or delaminating. Otherwise, cracks were detected in the coatings having thicknesses equal or superior to 100 nm, indicating a lack of cohesion.

Studies of fluorocarbon film deposition and its correlation with etched trench sidewall angle by employing a gap structure using C4F8∕Ar and CF4∕H2 based capacitively coupled plasmas

A high-aspect ratio, small gap structure that provides a sample surface region without direct ion bombardment has been used to study surface chemistry aspects of fluorocarbon (FC) film deposition and to simulate FC film deposition on trench sidewalls during plasma-based pattern transfer. As on the sidewalls of microscopic trenches being etched, thin FC layers form by arrival of reactive neutrals on the shadowed surface portions of the small gap structure. The deposition rates, composition, and chemical bonding of FC films formed in the small gap structure were determined by ellipsometry and x-ray photoemission spectroscopy as a function of process conditions for C4F8∕Ar and CF4∕H2 discharges produced in a dual frequency (40.68∕4MHz) capacitively coupled plasma reactor. Actual trench features were also produced using photoresist patterned organosilicate films for the same plasma processes. Scanning electron microscopy of the trenches shows a characteristic sidewall slope angle for different process conditions. We find that plasma process conditions producing lower FC film deposition rates on the shielded surface of the gap structure yield more vertical trench sidewalls. This relationship confirms the relevance of the small gap structure approach to the examination of trench sidewall chemistry. Since the present approach produces macroscopic samples of gap-deposited FC films, it enables direct surface chemical characterization of a material that is analogous to sidewall deposited films and allows to avoid the difficulties connected with direct measurements of microscopic samples. The lack of ion bombardment for the shielded deposition increases the retention of the chemical structure of the FC film precursors for the deposited films, which promises to be useful for obtaining mechanistic insights on film precursors.