Plasma Polymerized Thin Films Research Articles

A study on the characteristics of plasma polymer thin film with controlled nitrogen flow rate

Nitrogen-doped thiophene plasma polymer [N-ThioPP] thin films were deposited by radio frequency (13.56 MHz) plasma-enhanced chemical vapor deposition method. Thiophene was used as organic precursor (carbon source) with hydrogen gas as the precursor bubbler gas. Additionally, nitrogen gas [N2] was used as nitrogen dopant. Furthermore, additional argon was used as a carrier gas. The as-grown polymerized thin films were analyzed using ellipsometry, Fourier-transform infrared [FT-IR] spectroscopy, Raman spectroscopy, and water contact angle measurement. The ellipsometry results showed the refractive index change of the N-ThioPP film. The FT-IR spectra showed that the N-ThioPP films were completely fragmented and polymerized from thiophene.

플라즈마 중합법에 의한 게이트 절연박막의 제작 및 특성

Polymer thin films were prepared by capacitively coupled plasma polymerization process for application of gate insulator. The polymer thin films revealed to form polymer layers with original properties of the monomer. Among the plasma polymer thin films, the styrene polymer having large number of phenyl sites revealed higher dielectric constant of k

Organic Plasma-Polymer Thin Film Coatings on Super-Hydrophilic Coated Surface for Increasing the Surface Durability against Scratch without Changing of Surface Wettability

In this study, the SiO polymer coating film was prepared the containing tetraethyl orthosilane (TEOS) solution by the sol-gel method on soda lime glass. After then, the plasma polymer coating was deposited on SiO polymer coated glass by plasma enhanced chemical vapor deposition (PECVD) method at room temperature during 15 seconds. The thiophene monomer was used as organic precursor. It was heat up to 60 oC and bubbled with hydrogen gas which flow rate was 50 sccm. Plasma was ignited by radio frequency (RF, 13.56 MHz) and its power was 10 W. SiO polymer and plasma polymer coated SiO polymer films were investigated by Fourier Transform Infrared (FT-IR), scanning electron microscopy (SEM), ultraviolet-visible (UV-Vis.), water contact angle, the adhesion test, and the pencil hardness test. The IR spectra shows evidence of very thin organic plasma polymer, which could not be measured by SEM cross image. The SEM images show that the morphology of each film was not changed by plasma polymer coating. Low water contact angles showed with both coating. Moreover surface hardness was increased by plasma polymer coating.

Preparation and Characterization of Plasma Polymerized Methyl Methacrylate Thin Films as Gate Dielectric for Organic Thin Film Transistor

Plasma polymerized methyl methacrylate (ppMMA) thin films were deposited by plasma polymerization technique with different plasma powers and subsequently thermally treated at temperatures of 60 to <TEX>$150^{\circ}C$</TEX>. To find a better ppMMA preparation technique for application to organic thin film transistor (OTFT) as dielectric layer, the chemical composition, surface morphology, and electrical properties of ppMMA were investigated. The effect of ppMMA thin-film preparation conditions on the resulting thin film properties were discussed, specifically O-H site content in the pMMA, dielectric constant, leakage current density, and hysteresis.

A substrate-independent method for surface grafting polymer layers by atom transfer radical polymerization: Reduction of protein adsorption

A general method for producing low-fouling biomaterials on any surface by surface-initiated grafting of polymer brushes is presented. Our procedure uses radiofrequency glow discharge thin film deposition followed by macro-initiator coupling and then surface-initiated atom transfer radical polymerization (SI-ATRP) to prepare neutral polymer brushes on planar substrates. Coatings were produced on substrates with variable interfacial composition and mechanical properties such as hard inorganic/metal substrates (silicon and gold) or flexible (perfluorinated poly(ethylene-co-propylene) film) and rigid (microtitre plates) polymeric materials. First, surfaces were functionalized via deposition of an allylamine plasma polymer thin film followed by covalent coupling of a macro-initiator composed partly of ATRP initiator groups. Successful grafting of a hydrophilic polymer layer was achieved by SI-ATRP of N, N′-dimethylacrylamide in aqueous media at room temperature. We exemplified how this method could be used to create surface coatings with significantly reduced protein adsorption on different material substrates. Protein binding experiments using labelled human serum albumin on grafted materials resulted in quantitative evidence for low-fouling compared to control surfaces.

Plasma polymerization of amine-containing thin films and the studies on the deposition kinetics

Plasma-polymerized thin films prepared from amine-containing saturated (propylamine) and unsaturated (allylamine and propargylamine) precursors were investigated in terms of the deposition rate, polymerization kinetics and thin film morphology as function of the applied power. Moreover, a mathematical model was established to correlate the physicochemical properties to the deposition kinetics under plasma polymerizations. It was found that the thin film deposition rate was primarily dictated by the amine bond dissociation energy (NH 2 BDE) of precursors. On the other hand, surface chemistry (N/C ratio, surface imine and amine contents) guided the growth of L-929 fibroblast cells on the prepared amine-functionalized surfaces. A close relationship among the deposition kinetics, the physicochemical and biological properties of the deposited amine-containing plasma polymers was presented.

Direct optical transition in plasma polymerized vinylene carbonate thin films

Plasma polymerized vinylene carbonate (PPVC) thin films were deposited on to glass substrates by low pressure glow discharge plasma from vinylene carbonate monomer at room temperature. Surface morphology and chemical structure of PPVC were analyzed by Scanning electron microscopy and Fourier transformation infrared spectroscopy, respectively. The surfaces of the PPVC thin films were observed to be smooth and pinhole free. The structural analysis by FTIR spectroscopy indicates structural rearrangement due to the removal of bonds. Ultraviolet-visible spectroscopic studies have been carried out on the PPVC thin films of different thicknesses. It is seen that the absorbance increases with the increase of film thickness. The direct band gap energies were calculated from the absorption data and are found to be in the range of 3.96 to 4.15 eV.

Stem Cells, Nitrogen-Rich Plasma-Polymerized Culture Surfaces, and Type X Collagen Suppression

Mesenchymal stem cells (MSCs) are multipotent cells that can differentiate into chondrocytes, osteoblasts, myocytes, adipocytes, and a variety of other cell types. Several studies have been directed toward using MSCs from patients with osteoarthritis (OA) for cartilage repair, not only because these are the ones that will require a source of autologous stem cells if biological repair of cartilage lesions is to be a therapeutic option, but also to further an understanding of stem cell differentiation. Previous studies have shown that a major drawback of current cartilage and intervertebral disc tissue repair is that human MSCs from OA patients express type X collagen (COL X). COL X, a marker of late-stage chondrocyte hypertrophy, is implicated in endochondral ossification. However, those studies also revealed that a novel plasma-polymerized thin film material, named nitrogen-rich plasma-polymerized ethylene (PPE:N), was able to inhibit COL X expression in committed MSCs. The specific aim of this present study was to determine if the suppression of COL X by PPE:N is maintained when MSCs are transferred to pellet cultures in serum-free media. Our results confirmed the potential of two different types of PPE:N surfaces (low-pressure-PPE:N [L-PPE:N] and high-pressure-PPE:N [H-PPE:N]) in suppressing COL X expression, more so on the latter. Interestingly, when MSCs were transferred to pellet cultures, the expression level of COL X was further decreased by preincubation on H-PPE:N, suggesting that these kinds of coatings show promise for tissue engineering of cartilage and disc tissues. Further studies are needed to assess the relative importance of surface-chemistry versus surface-morphology in the mechanism of COL X suppression.

Highly Mass-Sensitive Thin Film Plate Acoustic Resonators (FPAR)

The mass sensitivity of thin aluminum nitride (AlN) film S0 Lamb wave resonators is theoretically and experimentally studied. Theoretical predictions based on modal and finite elements method analysis are experimentally verified. Here, two-port 888 MHz synchronous FPARs are micromachined and subsequently coated with hexamethyl-disiloxane(HMDSO)-plasma-polymerized thin films of various thicknesses. Systematic data on frequency shift and insertion loss versus film thickness are presented. FPARs demonstrate high mass-loading sensitivity as well as good tolerance towards the HMDSO viscous losses. Initial measurements in gas phase environment are further presented.

Complex permittivity measurements of RF plasma polymerized polyterpenol organic thin films employing split post dielectric resonator

Abstract In the fields of organic electronics and biotechnology, applications for organic polymer thin films fabricated using low-temperature non-equilibrium plasma techniques are gaining significant attention because of the physical and chemical stability of thin films and the low cost of production. Polymer thin films were fabricated from non-synthetic terpinen-4-ol using radiofrequency polymerization (13.56 MHz) on low loss dielectric substrates and their permittivity properties were ascertained to determine potential applications for these organic films. Real and imaginary parts of permittivity as a function of frequency were measured using the variable angle spectroscopic ellipsometer. The real part of permittivity (k) was found to be between 2.34 and 2.65 in the wavelength region of 400–1100 nm, indicating a potential low-k material. These permittivity values were confirmed at microwave frequencies. Dielectric properties of polyterpenol films were measured by means of split post dielectric resonators (SPDRs) operating at frequencies of 10 GHz and 20 GHz. Permittivity increased for samples deposited at higher RF energy – from 2.65 (25 W) to 2.83 (75 W) measured by a 20-GHz SPDR and from 2.32 (25 W) to 2.53 (100 W) obtained using a 10-GHz SPDR. The error in permittivity measurement was predominantly attributed to the uncertainty in film thickness measurement.

A Low Dielectric Study on Hybrid Plasma-Polymer Thin Films of Different Ratio Between Toluene and TEOS

Organic-inorganic hybrid co-polymer thin films were deposited on silicon(100) substrates under the several ratio of TEOS (tetraethoxysilane) against toluene by plasma enhanced chemical vapour deposition (PECVD) method. Toluene and TEOS were utilized as organic and inorganic precursors each, and hydrogen and argon were also used as a bubbler and carrier gases, respectively. In order to compare the difference of the electrical and the mechanical properties of the plasma polymerized thin films, we grew the hybrid co-polymer thin films under the conditions of various ratio between toluene and TEOS with fixed RF (radio frequency using 13.56 MHz) powers at 30 W. The as-grown polymerized thin films were in first analyzed by FT-IR and XPS. The result of FT-IR showed that the co-polymer thin films were polymerized with fragmented each precursor. Also, XPS results showed the chemical species and binding energies of each species. Si 2p core-level spectra from the hybrid polymer thin film showed the status of Si oxidation number. Impedance analyzer was utilized for the measurements of I-V curves and capacitance values. Also, the thin films were analyzed for hardness and Young's modulus by nano-indenter.

Surface oxygen in the growth of plasma polymerised thin films

Three different types of non-oxygen containing monomers were plasma polymerised into thin films and then studied using X-ray photoelectron spectroscopy (XPS) to determine the surface oxygen content. These three monomers were benzene, ferrocene, and octafluorocyclobutane. Depth profiling was also used to investigate the oxygen content into the bulk of the films by analysing the newly formed film surfaces after different amounts of argon ion sputtering. The initial oxygen concentration on the surface of the ferrocene films was the largest of the three (>20 at.%) while octafluorocyclobutane films had only a small concentration at the surface (∼0.4 at.%). The benzene films had an intermediate concentration (∼4 at.%). Affinity for oxygen on the benzene films is due to residual activated species including free radicals and dangling bond sites on the film surface. Depth profiling showed a rapid reduction of oxygen (to ∼0.2 at.%) a short distance into the benzene films, indicating that the oxygen adsorbed on the surface after film deposition and exposure to the ambient. For the ferrocene films, a substantial amount of oxygen remained with depth, indicating that oxygen was incorporated into the film during deposition. Due to the chemical nature of fluorine, the as-deposited octafluorocyclobutane films did not exhibit significant affinity towards oxygen.

New Insights into the Substrate–Plasma Polymer Interface

We describe a new method to characterize the underside (substrate interface) of plasma polymer (PP) thin films via their simple delamination from a sodium chloride single crystal substrate. By depositing the PP film onto an ionic bonded surface such as a sodium chloride crystal, the PP films investigated were easily delaminated from the substrate. Two plasma polymer films deposited from 1-bromopropane (BrPP) and allylamine (AAPP) were used to exemplify this new technique. The top- and underside (substrate-plasma polymer interface) of the films were examined by X-ray photoelectron spectroscopy (XPS) and synchrotron-based near edge X-ray adsorption fine structure (NEXAFS) spectroscopy. The results demonstrate that both films exhibit heterogeneous film structures with their chemical composition and levels of unsaturated species. The underside of both the BrPP and the AAPP films exhibited higher concentrations of oxygen, while their topsides contained higher levels of unsaturated species. These results provide useful insights into the BrPP and AAPP film formation and the chemistry. The delamination technique provides a simple method to analyze the early stages of film chemistry for plasma polymer thin films. Furthermore, this approach opens new opportunities for additional studies on the mechanisms and fundamentals of plasma polymer thin film formation with various monomers.

Characteristics of multilayered plasma-polymer thin films using toluene and TEOS by PECVD

This study investigated the interaction of alternate multilayer ultralow-k TEOS (tetraethoxysilane)-toluene plasma-polymer thin films, as well as their electrical and chemical properties. Multilayered plasma-polymer thin films were deposited on silicon (1 0 0) substrates with the alternate injection of each precursor at room temperature via the plasma enhanced chemical vapor deposition (PECVD) method. Toluene and TEOS were prepared as the organic and inorganic precursors, and hydrogen and argon gases were used as the bubbler and carrier gases, respectively. To compare differences in the electrical and chemical properties of the multilayer plasma-polymer thin films, the hybrid polymer thin films were grown under 30 W of RF (radio frequency using 13.56 MHz) power with different proportions of toluene and TEOS polymer layer in the same total thickness. The as-grown plasma polymer thin films were in first analyzed by using FT-IR (Fourier transform infrared) and FE-SEM (field emission scanning electron microscopy). FT-IR results showed that the hybrid polymer thin films were totally fragmented and polymerized by PECVD. SEM cross sectional images showed alternate TEOS-toluene plasma polymer thin films. Plasma-polymer thin film capacitances were measured to determine the dielectric constant at 1 MHz.

Synthesis and Characterization of Plasma Polymerized Thin Films Deposited from Benzene and Hexamethyldisiloxane using (PECVD) Method

Polymer-like organic thin films were deposited on both aluminum alloy type 6061 and glass substrates at room temperature by Plasma Enhanced Chemical Vapor Deposition (PECVD) methodusing benzene and hexamethyldisiloxane (HMDSO) as precursor materials. The surface and physical properties of plasma-polymerized organic thin films were investigated at different r.f. powers. The effects of benzene/argon ratio on the properties of plasma polymerized benzene films were also investigated. It is found that using benzene alone results in a non-coherent and non-adherent powdery deposited material. The chemical structure and surface properties of the asgrown plasma polymerized thin films were analyzed on glass substrates with FTIR and contact angle measurements. FTIR spectra of benzene deposited film indicated that the benzene rings are preserved when increasing benzene ratio and/or decreasing r.f. powers. FTIR spectra of HMDSO deposited films indicated an increase of the hydrogen concentration and a decrease of the oxygen concentration with the increase of r.f. power. The contact angle (θ) of the films prepared from benzene was found to increase by about 43% as benzene ratio increases from 10% to 20%. θ was then found to decrease to the original value (51°) when the benzene ratio increases to 100%. The contact angle, θ, for both benzene and HMDSO deposited films were found to increase with r.f. power. This signifies that the plasma polymerized organic films have substantially low surface energy as the r.f power increases. The corrosion resistance of aluminum alloy substrate both bare and covered with plasma polymerized thin films was carried out by potentiodynamic polarization measurements in standard 3.5 wt. % NaCl solution at room temperature. The results indicate that the benzene and HMDSO deposited films are suitable for protection of the aluminum substrate against corrosion. The changes in the processing parameters seem to have a strong influence on the film protective ability. Surface roughness of films deposited on aluminum alloy substrate was investigated using scanning electron microscopy (SEM). The SEM images indicate that the surface roughness of benzene deposited films increase with decreasing the benzene ratio. SEM images of benzene and HMDSO deposited films indicate that the surface roughness decreases with increasing r.f. power. Studying the above parameters indicate that the films produced are suitable for specific practical applications. Keywords—Plasma polymerization, potentiodynamic test, Contact angle.

A study on the plasma polymer thin film surface modification for DNA alignment by using high energy electron beam irradiation

The plasma polymer thin films were deposited on Si(100) substrate by PECVD (plasma enhanced chemical vapor deposition) method. Liquid cyclohexene was used as single organic precursor. It was heated up to 60 °C and bubbled up by hydrogen gas, which flow rate was 50 sccm (standard cubic centimeters per min). Deposition temperature was room temperature. Plasma was ignited by a radio frequency (RF; 13.56 MHz) of 10 W. As-deposited plasma polymer thin films were treated by e-beam of 300 keV with various adsorption radiation doses. The plasma polymer films, which were treated by high energy e-beam (HEEB), were investigated by FT-IR (Fourier Transform Infrared), XPS (X-ray Photoelectron Spectroscopy), AFM (Atomic Force Microscopy), and the water contact angles. From IR spectra, the intensity of OH functional group is increased by increasing electron dose rate. XPS results also show that the intensity of O 1s peak is increased by increasing electron dose rate. C 1s peak shows that oxygen bonded at carbon site. The water contact angles are decreased by increasing electron dose rate. From the AFM analysis, we observed the formation of λ-DNA (deoxyribonucleic acid) array on plasma polymer film, which was treated by HEEB with 14 kGy of adsorption radiation dose.

DIELECTRIC PROPERTIES OF PLASMA POLYMERIZED N,N,3,5 TETRAMETHYLANILINE THIN FILMS

Plasma polymerized thin films of aluminium/thin film/aluminium configuration were deposited at room temperature by a parallel plate capacitively coupled glow discharge reactor using N,N,3,5 tetramethylaniline (TMA) as a precursor. The infrared spectroscopic analyses revealed that plasma polymerized TMA (PPTMA) films contained an aromatic ring structure with NC and CH side groups, presence of C = O was also evident. The differential thermal analysis and thermogravimetric analysis of PPTMA thin film was thermally stable up to about 505 K. The scanning electron microscopy of PPTMA thin film showed a smooth, flawless and pinhole free surface. The capacitance and ac electrical conductance of PPTMA thin films were measured as functions of frequency (100 &lt; f &lt; 105 Hz) and temperature (300 &lt; T &lt; 450 K). The electrical conductivity is more dependent on temperature in the low frequency region than that in the high frequency region. In PPTMA thin films the conduction may be dominated by hopping of carriers between the localized states at low temperatures and thermally excited at the high temperatures. The activation energies are estimated to be about 0.05 eV in the low temperature and 0.23 eV in the high temperature. Dielectric constant decreases with the increase of frequency and that decreases with the increase of temperature but dielectric loss increases with increasing frequency with a minimum in the low frequency region. The temperature-dependence of the Cole-Cole diagram shows the existence of distribution of dielectric relaxation times in the PPTMA thin films.

Combination of zinc alloy coating with thin plasma polymer films for novel corrosion protective systems on coated steel

Steel sheet used in automotive applications has to be corrosion protected effectively, which is usually realized by zinc or zinc alloy coatings with a thickness range of 5–10μm. Steel sheet for areas of a car body which are exceptionally stressed by corrosion, e.g. cavity flanges or joints, may be protected additionally by a thin weldable organic coating with a thickness of 2–4μm. A very promising approach to a significantly reduced use of resources is the combination of zinc alloy coatings with thin plasma polymer films deposited by means of plasma-enhanced chemical vapour deposition (PECVD). Such plasma polymer films of just a few 100nm thickness show excellent barrier and adhesion properties as well as a high mechanical stability.Within this work thin plasma polymer films were deposited on zinc alloy coated steel substrates using the strip hollow cathode (SHC) method, which was modified for application on grounded substrates. A pulsed DC glow discharge in a mixture of argon and an organosilane precursor was used for the deposition of films with a thickness of 100–500nm.The chemical compositions of the coatings were determined by means of X-ray photoelectron spectroscopy and Fourier transform infrared spectroscopy. The morphologies of the coating systems were studied by means of scanning electron microscopy. The performance of the coating systems has been studied in different specific tests of corrosion and processing behaviour. The investigated coating systems show a corrosion resistance comparable to reference samples of electro-galvanised steel sheet with additional organic coating even with a coating thickness less of half of the reference samples.

Study of the Characteristics of Organic Thin Film Transistors with Plasma-Polymer Gate Dielectrics

The effects of gate dielectrics material in organic thin film transistors (OTFTs) were investigated. The gate dielectrics were deposited by plasma enhanced chemical vapor deposition (PECVD) with cyclohexane and tetraethylorthosilane (TEOS) respectively used as organic and inorganic precursors. The gate dielectrics (gate insulators) were deposited as either organic plasma-polymer or organic–inorganic hybrid plasma-polymer thin film by using cyclohexane or cyclohexane with TEOS, respectively. Additionally, hydrogen and argon were used as precursor bubbler gases. A polyimide (PI) substrate was used in the fabrication of pentacene OTFTs with a plasma-polymer gate insulator, an Au source–drain (S/D), and Cu gate electrodes. Different gate dielectrics were investigated. The as-grown plasma-polymer thin films were first analyzed using Fourier-transform infrared (FT-IR) spectroscopy. Also, they were analyzed by nano-indentation and capacitance measurements. The electrical properties, such as mobility and threshold voltage of the pentacene field-effect transistors with the plasma-polymer gate-dielectrics were investigated. Transistor with cyclohexane gate dielectric had a higher field-effect mobility, µFET = 0.84 cm2 V-1 s-1, and a smaller threshold voltage, VT= -6.8 V, than the transistor with the hybrid gate-dielectric.

Microwave characterization of a novel, environmentally friendly, plasma polymerized organic thin film

Polymerized Linalyl Acetate (PLA) thin films were fabricated using RF plasma polymerization. The dielectric properties of the PLA thin films have been investigated using the split post dielectric resonance technique, which consists of a silver coated copper cavity and two precisely machined identical dielectric materials. The measurements have been carried out at resonance frequencies of 10GHz and 20GHz, with good agreement between results. The dielectric properties were also investigated at low frequencies using capacitive measurements of MIM structures. All methodologies place the dielectric constant of the PLA material at approximately 2.4, indicating the material is suitable for use in electronics as an insulating layer.