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Graphene is typically grown using thermal chemical vapor deposition (CVD) on metallic substrates such as copper and nickel at elevated temperatures above 1000 °C. The synthesis of large-area graphene at low temperature is highly desirable for large volume industrial production. In this paper, the authors report a remote plasma-assisted CVD graphene synthesis at a reduced temperature of 600 °C in a relatively shorter duration of 15 min. Scanning electron microscopy reveals the formation of large graphene crystal with an approximate size of 100 × 100 μm2 over the entire 2 × 10 cm2 surface of copper foil substrates. Raman spectra recorded for graphene grown at 600 °C show the presence of a graphene characteristic “2D” peak, attesting to the formation of graphene. The results show that it is possible to grow horizontal graphene at low temperatures and transfer it to flexible polyethylene terephthalate substrates. The utility of the synthesized graphene is ascertained through the successful fabrication of a flexible graphene-based electrochemical sensor for the detection of glucose concentration. The present research will have a direct impact on flexible wearable biosensors.Graphene is typically grown using thermal chemical vapor deposition (CVD) on metallic substrates such as copper and nickel at elevated temperatures above 1000 °C. The synthesis of large-area graphene at low temperature is highly desirable for large volume industrial production. In this paper, the authors report a remote plasma-assisted CVD graphene synthesis at a reduced temperature of 600 °C in a relatively shorter duration of 15 min. Scanning electron microscopy reveals the formation of large graphene crystal with an approximate size of 100 × 100 μm2 over the entire 2 × 10 cm2 surface of copper foil substrates. Raman spectra recorded for graphene grown at 600 °C show the presence of a graphene characteristic “2D” peak, attesting to the formation of graphene. The results show that it is possible to grow horizontal graphene at low temperatures and transfer it to flexible polyethylene terephthalate substrates. The utility of the synthesized graphene is ascertained through the successful fabrication of a fl...

Remote plasma sources are widely used in applications such as chamber cleaning and flowable chemical vapor deposition. In these processes, it is desirable that the dissociation rate of feed gases be as high as possible and stable. Here, the authors present results on radical densities and gas dissociation fractions for a 400 kHz toroidal transformer-coupled plasma source (MKS Instruments), operating at a power density of 5–50 W/cm3 with feed gas mixtures of O2 or NF3 in Ar and pressures of 0.4 or 2.0 Torr. Radical densities and feed gas dissociation percentages in the plasma were measured by optical emission spectroscopy combined with Ar actinometry. In the plasma, O2 was about 60% dissociated in dilute O2 mixtures (10%–20%). Dissociation decreased with the increasing addition of O2, dropping to 10% dissociation for 90% O2 in the feed gas. NF3 was >95% dissociated for all NF3/Ar mixtures. Little or no dependence on the flow rate was found. Plasma products flow into an anodized Al downstream chamber that is probed by vacuum ultraviolet (VUV) absorption spectroscopy and line-of-sight molecular beam mass spectrometry. In the downstream chamber, O recombined on the walls to form O2 (detected by VUV O2 absorption). The measured downstream O/O2 ratio was a strongly increasing function of an increasing flow rate reproduced by a downstream global model with O wall recombination probability of γO between 0.001 and 0.002. NF3 does not reform in the downstream chamber, as verified by VUV absorption and mass spectrometry. No NF or NF2 was detected, and F mostly recombined to form F2 at the back of the downstream chamber, along with N2. The F2, F, and N2 product absolute number densities were consistent with the 3:1 F:N mass balance of the NF3 feed gas.

Developing processes for highly selective etching of silicon nitride (Si3N4) with respect to silicon dioxide (SiO2) is a major priority for semiconductor fabrication processing. In this paper and in Paper I [Volynets et al., J. Vac. Sci. Technol. A 38, 023007 (2020)], mechanisms are discussed for highly selective Si3N4 etching in a remote plasma based on experimental and theoretical investigations. The Si3N4/SiO2 etch selectivity of up to 380 was experimentally produced using a remote plasma sustained in NF3/N2/O2/H2 mixtures. A selectivity strongly depends on the flow rate of H2, an effect attributed to the formation of HF molecules in vibrationally excited states that accelerate etching reactions. Based on experimental measurements and zero-dimensional plasma simulations, an analytical etching model was developed for etch rates as a function of process parameters. Reaction rates and sticking coefficients were provided by quantum chemistry models and also fitted to the experimental results. Etch rates from the analytical model show good agreement with the experimental results and demonstrate why certain etchants accelerate or inhibit the etch process. In particular, the modeling shows the important role of HF molecules in the first vibrationally excited state [HF(v = 1)] in achieving high Si3N4/SiO2 selectivity.

In this paper, we report the plasma-enhanced atomic layer deposition (PEALD) of TiO2 and TiO2/Al2O3 nanolaminate films on p-Si(100) to fabricate metal-oxide-semiconductor (MOS) capacitors. In the PEALD process, we used titanium tetraisopropoxide (TTIP) as a titanium precursor, trimethyl aluminum (TMA) as an aluminum precursor and O2 plasma as an oxidant, keeping the process temperature at 250 &deg, C. The effects of PEALD process parameters, such as RF power, substrate exposure mode (direct or remote plasma exposure) and Al2O3 partial-monolayer insertion (generating a nanolaminate structure) on the physical and chemical properties of the TiO2 films were investigated by Rutherford backscattering spectroscopy (RBS), Raman spectroscopy, grazing incidence X-ray diffraction (GIXRD), and field emission scanning electron microscopy (FESEM) techniques. The MOS capacitor structures were fabricated by evaporation of Al gates through mechanical mask on PEALD TiO2 thin film, followed by evaporation of an Al layer on the back side of the Si substrate. The capacitors were characterized by current density-voltage (J-V), capacitance-voltage (C-V) and conductance-voltage (G-V) measurements. Our results indicate that RF power and exposure mode promoted significant modifications on the characteristics of the PEALD TiO2 films, while the insertion of Al2O3 partial monolayers allows the synthesis of TiO2/Al2O3 nanolaminate with well-spaced crystalline TiO2 grains in an amorphous structure. The electrical characterization of the MOS structures evidenced a significant leakage current in the accumulation region in the PEALD TiO2 films, which could be reduced by the addition of partial-monolayers of Al2O3 in the bulk of TiO2 films or by reducing RF power.

Hafnium disulfide (HfS2) is a promising two-dimensional material for scaling electronic devices due to its higher carrier mobility, in which the combination of two-dimensional materials with traditional semiconductors in the framework of CMOS-compatible technology is necessary. We reported on the deposition of HfS2 nanocrystals by remote plasma enhanced atomic layer deposition at low temperature using Hf(N(CH3)(C2H5))4 and H2S as the reaction precursors. Self-limiting reaction behavior was observed at the deposition temperatures ranging from 150 °C to 350 °C, and the film thickness increased linearly with the growth cycles. The uniform HfS2 nanocrystal thin films were obtained with the size of nanocrystal grain up to 27 nm. It was demonstrated that higher deposition temperature could enlarge the grain size and improve the HfS2 crystallinity, while causing crystallization of the mixed HfO2 above 450 °C. These results suggested that atomic layer deposition is a low-temperature route to synthesize high quality HfS2 nanocrystals for electronic device or electrochemical applications.

University of California Observatories has undertaken an effort to develop improved coatings for optical astronomy, both reflective and anti-reflective. We report of the latest developments in this program. This effort includes new interface materials between silver and protective over-layers, one of which (nickel oxide) shows great promise for enhanced durability and works well to λ~340nm, as shown by aggressive environmental stressing. In addition, we have been exploring atomic layer deposition (ALD) for building protective metal-oxide layers for silver-based coatings, using a new facility capable of coating optics up to 0.9-m in size. This new facility has just been delivered, but we have already obtained excellent uniformity with Al2O3 coatings across the full diameter. We are exploring different deposition parameters with the goal of achieving excellent thin films at lower temperature than typically used in ALD by employing both remote plasma enhancement and/or alternate oxidizing agents. We plan to explore nitride and fluorides also. Finally, we report on continued development and deposition of broad-band anti-reflection coatings based on silica sol-gel. These developments are particularly important with regards to the next generation telescopes and instruments, but of course could be applied to existing telescopes and instruments.

A pair of metal-dielectric metameric filters that could create a hidden image was presented for the first time. The structure of the filters is simple and only six layers for filter A and five layers for filter B. The prototype filters were designed by using the film color target optimization method and the designed results show that, at normal observation angle, the reflected colors of the pair of filters are both green and the color difference index between them is only 0.9017. At observation angle of 60°, the filter A is violet and the filter B is blue. The filters were fabricated by remote plasma sputtering process and the experimental results were in accordance with the designs.

An extended study on an advanced method for the cleaning of carbon contaminations from large optical surfaces using a remote inductively coupled low-pressure RF plasma source (GV10x DownStream Asher) is reported. Technical and scientific features of this scaled up cleaning process are analysed, such as the cleaning efficiency for different carbon allotropes (amorphous and diamond-like carbon) as a function of feedstock gas, RF power (from 30 to 300W), and source-object distances (415 to 840 mm). The underlying physical phenomena for these functional dependences are discussed., The authors would like to acknowledge the help by Guillaume Sauthier (ICN2) for his collaboration during the XPS characterization. We also thank ibss Group Inc. for supplying the GV10x DS Asher systems as well as the DLC samples.

In this paper, we will report on the formation of HfSixOy layer on an HF-last Si(100) substrate by atomic layer deposition from tetrakis(dimethylamido)hafnium (TDMAH) and atomic oxygen generated by a microwave remote plasma. Transmission electron microscopy observations of HfSixOy /Si structures deposited at 100 and 300°C revealed that 3~5-nm-thick amorphous HfSixOy layers were unintentionally formed preceded the growth of crystalline Hf-rich HfSixOy layers. To understand the mechanism of this unintentional growth of HfSixOy, the depth profiles of Hf, O and Si elements were measured by X-ray photoelectron spectroscopy. It was found that Hf atoms deeply diffused into the Si substrate. From these results, suppression of Hf in diffusion to the Si substrate must be important to reduce the capacitance equivalent thickness of the metal-oxide-semiconductor capacitors. The roles of TDMAH and plasma-generated oxygen radical on the enhanced diffusion of Hf will be discussed in detail.

Remote plasma processing is one of the most effective methods for the manipulation of intrinsic defects, doping, stoichiometry, and morphology of a large variety of oxides. Here, we discuss the interaction of polar ZnO and of LiGaO2 and LiAlO2 with atomic hydrogen and nitrogen produced by remote H2 and N2 plasmas. We show that the various crystallographic faces of those wurtzite-like oxides are characterized by a different reactivity to hydrogen and nitrogen. Specifically, we demonstrate that the O-polar ZnO is the most stable surface to hydrogen and, therefore, it should be the one of interest to preserve electrode stability in all those applications involving hydrogen. Conversely, we found that H2 remote plasma processing does not significantly alter Li-based oxides LiGaO2 and LiAlO2, while their nitridation can be exploited to alter the Li composition and mobility.

Fundamental surface reactions in the atomic layer deposition of GaN with trimethylgallium (TMG) and plasma-excited NH 3 are investigated by multiple-internal-reflection infrared absorption spectroscopy (MIR-IRAS) at surface temperatures varying from room temperature (RT) to 400 °C. It is found that TMG is saturated at RT on GaN surfaces when the TMG exposure exceeds 8 × 10 4 Langmuir (L), where 1 L corresponds to 1.33 × 10 −4 Pa s (or 1.0 × 10 −6 Torr s), and its saturation density reaches the maximum value at RT. Nitridation with the plasma-excited NH 3 on the TMG-saturated GaN surface is investigated by X-ray photoelectron spectroscopy (XPS). The nitridation becomes effective at surface temperatures in excess of 100 °C. The reaction models of TMG adsorption and nitridation on the GaN surface are proposed in this paper. Based on the surface analysis, a temperature-controlled ALD process consisting of RT-TMG adsorption and nitridation at 115 °C is examined, where the growth per cycle of 0.045 nm/cycle is confirmed. XPS analysis indicates that all N atoms are bonded as GaN. Atomic force microscopy indicates an average roughness of 0.23 nm. We discuss the reaction mechanism of GaN ALD in the low-temperature region at around 115 °C with TMG and plasma-excited NH 3 .

The decontamination efficiency of a non-thermal remote plasma application for dry and heat sensitive products was investigated. Therefore three different types of herbs and spices (pepper seeds, crushed oregano and paprika powder) with various surface-to-volume ratios were treated with plasma processed air up to 90 min and the inactivation of their native microbial flora was examined. Furthermore the impact of the plasma treatment on the product color was determined. The remote plasma treatment reduced the native microbial flora of the pepper seeds and the paprika powder by more than 3 log10 after 60 min treatment time. However remote plasma treatment of red paprika powder resulted in a considerable loss of redness after a treatment time of ⩾5 min. The lower inactivation of the native microbial flora of oregano of 1.6 log10, was related to the much lower initial microbial load. The treatment had only a minor impact on the pepper seed’s and oregano’s color (ΔE∗ up to 10.2 and 20.0, respectively).

In this paper the fabrication of highly porous 1D nanostructures by a vacuum and plasma etching combined protocol is presented. Zn-phthalocyanine (ZnPc) is utilized as a solid precursor to form the ZnO. First the ZnPc is sublimated in low argon pressure. Depending on the substrate temperature and microstructure, polycrystalline films or single crystal ZnPc nanowires are grown. These starting materials are then subjected to a remote plasma oxidizing treatment. Experimental parameters such as substrate position, plasma power, treatment duration, and substrate temperature determine the microstructure and properties of the final ZnO nanostructures. The article gathers an in depth study of the obtained porous nanostructured films following scanning and transmission electron microscopy (SEM and TEM), X-ray photoelectron spectroscopy (XPS), X-ray Diffraction (XRD), UV-Vis transmittance, and fluorescence spectroscopies.

Hydrogen (H 2 ) plasma treatment at the interface between 4H-SiC substrate and Al 2 O 3 dielectric prepared by the atomic layer deposition (ALD) was performed and its effects on capacitance–voltage characteristics as well as the interface state density ( D it ) was evaluated with metal oxide semiconductor devices. The atomic force microscopy result indicates that the remote H 2 plasma treatment reduces surface roughness. Compared with the non-passivated devices, lower leakage current, lower hysteresis and higher breakdown voltage are attained with remotely hydrogen plasma-treated devices. Without post metallization annealing (PMA), D it value more than 10 14 eV −1 cm −2 is attained with hydrogen plasma passivated devices, indicating plasma-induced damage on the surface. However, using PMA, D it of the H 2 plasma treated device is significantly reduced to as low as 1.00 × 10 12 eV −1 cm −2 at E c − E t = 0.4 eV and is about five times lower than that of sample without H 2 plasma passivation ( D it = 4.84 × 10 12 eV −1 cm −2 ).

Introduction H2-based plasma process has been controversial for a long time as it’s reported the high H2-based plasma could result in device instability [1]. In this work, we investigated various H2 related etch processes in advanced logic technology from the point of view of selectivity, defect, reliability and yield performance. Due to the chemi-sorption and recombination of H atom at Si [2], high temperature(>250℃) H2 remote plasma can be used to minimize the material loss for process where oxygen is forbidden, while and low temperature( High temperature H2 based plasma process Both shallow junction and HKMG have been integrated into the advanced logic process. This leads to the introduction of forming gas (4% H2 in N2/H2 mixture) to replace the traditional O2-based ashing process for metal gate EOT concern. Compared with conventional forming gas ash process, high H2(>10% H2 in N2/H2 mixture) ash process delivers superior photo resist removal capability, much less Si loss and higher throughput at high-dose implant strip, thus yield enhancement as shown in Fig.1. Besides, Si-C bond after p-MOS Si recess etch could inhibit SiGe epitaxy and result in defect. We proved that high H2 ash process could effectively remove the Si-C bond at EPI surface and greatly reduce the SiGe EPI defect count [3]. In Static Random Access Memory vehicle, high H2 process delivers >10% Vmin yield enhancement as shown in Fig 2. Furthermore, after Dummy Poly Gate Remove, H2 based ash process provided more hydrogen mobiles to passivate dangling bond at Si/SiO2 interface and delivered 7 times better Negative Bias Temperature Instability performance than forming gas ash process as shown in Fig 3. Low temperature H2 based plasma process Low temperature H2 can be used to etch Si or used as post etch treatment to remove the poly-si residue on ICP etcher. In this work, we demonstrated the H2 based DPGR process could deliver >50% gate leakage(Ig) improvement than conventional halogen gas etch process because of less HK capping layer loss as shown in Fig4. At same time, low temperature H2 based plasma was evaluated as post etch Treatment at Ultra Low K(ULK) etch to remove etch by-product. The hot H radicals can make the hydrophobic CHn group to be more reactive CHn-1 group. Si which loses the CHn group will absorb the H2O during the exposure to ambient and result in ULK degradation (Fig5).When we implemented same H2 PET process at Pad etch process, severe Plasma Induce Damage issue was detected (Fig6). This phenomenon also proved that low temperature H2 plasma dissociated more high energy ions because of small mass. Pad acted as large area antenna which collected more charges. The reversed electron shading effect results in PID. In ULK Metal Hard mask approach, we introduced H2 in via etch to achieve self-aligned Via. CxFy and H2 gas plasma delivered high selectivity between ULK and metal hard mask because H atom can decrease the F concentration in plasma. The via-via distance can be doubled with H2 implementation (Fig7). and this will benefit the time-dependent dielectric breakdown reliability performance. Conclusions In brief, H2 based plasma process plays important role in advanced logic technology, especially in HKMG technology. Low temperature H2 based plasma process needs to be evaluated prudently because H radical is more reactive. Figure 1

Whole black pepper is a dry product, which is often naturally contaminated with bacterial endospores and sometimes also with human pathogens like Salmonella. Dry pepper itself is a shelf-stable product, but if it is incorporated into high moisture minimally processed food, the microorganisms can reduce the shelf-life of the final product and/or can cause foodborne diseases. In this study the antimicrobial effect of two different atmospheric pressure plasma applications for the decontamination of whole black pepper was investigated. Naturally contaminated peppercorns and with Bacillus subtilis spores, Bacillus atrophaeus spores and Salmonella enterica inoculated ones were treated using a plasma jet or a microwave-driven remote plasma. Surface color and the content of essential oils and piperine was measured. S. enterica, B. subtilis spores and B. atrophaeus spores were reduced by 4.1, 2.4 and 2.8 log, respectively, after 30 min remote plasma treatment. Direct plasma jet treatment did not result in equivalent inactivation levels. However, both plasma applications did not considerable affect the quality parameters.

We investigated the effects of NH3 plasma power on characteristics of low-temperature silicon nitride thin films for application of a gate spacer. SiNx thin film was deposited on a Si(100) substrate by remote plasma atomic layer deposition (RPALD) using trisilylamine (TSA) as a Si precursor and NH3 gas as a reactant. NH3 remote plasma was analyzed with optical emission spectroscopy (OES) and it largely consisted of NH and H. As the plasma power increased, more NH and H radicals were generated and a proportion of NH radicals in the plasma increased, which resulted in the slight increase of the high-N content and low-H content in SiNx thin film. The low-H content with nearly stoichiometric SiNx thin films improve etch rate properties. The densities of RPALD SiNx thin film were 2.7 g cm−3 and almost the same regardless of plasma power. RPALD SiNx thin films showed a low leakage current density of 10−7 A cm−2 at 2 MV cm−1 and a breakdown voltage of approximately 8 MV cm−1.

Traditional application of multipactor coatings applied with sputtering techniques to high-power RF windows typically performs well when applied to sintered powder ceramics. Unfortunately, sputtered coatings do not adhere well to crystal materials, such as sapphire. This publication describes a plasma-assisted process that molecularly bonds the multipactor coating to the base window material. The performance was verified by measuring secondary electron emission yield and operating the window at high power. The coating process and performance are presented.

Specific features of remote plasma enhanced chemical vapor deposition processes with inductive and capacitive coupling of power have been analyzed. Experimental results from a study of the physical and chemical regularities of those processes have been considered. Influence of diluting nitrogen with noble gases on growth rate and composition of the deposited films has been discussed. Essential role of argon diluting providing a high concentration of atomic nitrogen in the reacting gas phase required for plasma chemical synthesis of nitride films was demonstrated. Possible approaches to further improvement of plasma enhanced chemical deposition processes have been proposed.

The electron swarm parameters of Ar/He mixtures in a low pressure 13.56 MHz hollow cathode discharge in remote plasma are analyzed utilizing Boltzmann equation method. These parameters are important to understand the mechanism of plasma dynamics and could not be measured directly. In this work, we calculate the electron energy distribution functions (EEDF), compare them with experimental results, and determine the mobility, the drift velocity, the average electron energy and the diffusion coefficients in pure argon and in Ar/He mixtures.

In this study, the characteristics of nickel thin film deposited by remote plasma atomic layer deposition (RPALD) on p-type Si substrate and formation of nickel silicide using rapid thermal annealing were determined. Bis(1,4-di-isopropyl-1,3-diazabutadienyl)nickel, Ni(iPr-DAD)2, was used as a Ni precursor and ammonia plasma was used as a reactant. This was the first attempt to deposit Ni thin film using Ni(iPr-DAD)2 as a precursor for the ALD process. The RPALD Ni film was deposited with a growth rate of around 2.2{\AA}/cycle at 250 {\deg}C and showed significant low resistivity of 33 {\mu}{\Omega}cm with a total impurity concentration of around 10 at. %.The impurities of the thin film, carbon and nitrogen, were existent by the forms of C-C and C-N in a bonding state. The impurities removal tendency was investigated by comparing of experimental conditions, namely process temperature and pressure. Nitrogen impurity was removed by thermal desorption during each ALD cycle and carbon impurity was reduced by the optimizing of the process pressure which is directly related with a mean free path of NH3 plasma. After Ni deposition, nickel silicide was formed by RTA in a vacuum ambient for 1 minute. A nickel silicide layer from ALD Ni and PVD Ni was compared at the annealing temperature from 500 to 900 {\deg}C. NiSi from ALD Ni showed better thermal stability due to the contribution of small amounts of carbon and nitrogen in the asdeposited Ni thin film. Degradation of the silicide layer was effectively suppressed with a use of ALD Ni., Comment: 21 pages, 7 figures

Modification of polyethylene and polypropylene surfaces by atmospheric-pressure plasmas using mixtures of nitrogen and hydrogen was studied using Fourier-transform infrared spectroscopy in the attenuated total reflection mode (FTIR-ATR) and by near-edge x-ray absorption fine structure spectroscopy (NEXAFS) in order to shed some light on the chemical nature of nitrogen-containing functional groups on the polymer surface. Using FTIR-ATR spectroscopy combined with hydrogen-deuterium isotope exchange of active hydrogen atoms, it was shown that the direct treatment of PE foils by dielectric barrier discharges (DBDs) in N2/H2 mixtures and a subsequent exposure of the samples to the ambient air results in the formation of -NH2 moieties of primary amides on the polymer surface. Corresponding in situ experiments with streaming N2/H2 DBD post-discharges virtually free of H2O and O2, on the other hand, showing the absence of -NH2, proving that no primary amines or amides are formed by this treatment although substantial amounts of nitrogen are incorporated. Moreover, directly N2/H2-plasma-treated polymer surfaces, similar to afterglow-treated low-density polyethylene (LDPE), show amphiphilic character as to be seen by chemical derivatization with nucleophilic reagents 4-(trifluoromethyl)phenylhydrazine and 4-(trifluoromethyl)benzyl­amine, in addition to electrophilic aromatic aldehydes normally used to derivatize such surfaces. The presence of imines or other functional groups with C=N moieties which may be invoked to explain the dual (amphiphilic) reactivity is proven by NEXAFS studies on ultrathin plasma-treated PE films, confirming significant amounts of nitrogen in C=N bonds and carbon in C=C bonds.

In this study, the influence of dielectric barrier discharges at atmospheric pressure on maple sapwood was analyzed. Three common discharge types, a coplanar surface barrier discharge (CSBD), a direct dielectric barrier discharge and a jet discharge/ remote plasma, were realized by the same electrodes and power supply. In general, plasma treatments are known to modify various surface properties leading to improved adhesion. For resins such as urea formaldehyde, the curing behavior is dependent on the pH. Therefore, the change of the surface pH value of maple is measured. As the main product of plasma-generated nitrogen oxides, the nitrate concentrations and consequently the nitric acid concentrations of the surfaces were determined. A significant pH reduction from about pH 5.6 to pH 4.6 was reached after a 30 s plasma treatment. An increase in the nitrate concentration over the plasma treatment duration was measured for all three discharges with a maximum of 6.6 mg/L for the CSBD, which corresponds to a concentration of 8.25 mg per m2 wooden surface. peerReviewed

International audience; A Cold Remote (N-2 + O-2) Plasma (CRNOP) process was used in order to create new surface properties on various wooden samples. Two applications were studied and optimized using experimental design. The first one involved samples (fir, pine, beech and oak) treated by the CRNOP in order to increase their impregnability evaluated by dynamic wetting and water absorption measurements. In the best conditions, water absorption was increased by 1.8; 1.9; 2.0 and 5.1 for fir, pine, oak and beech, respectively. The second application involved a plasma polymerization of 1,1,3,3, tetramethyldisiloxane induced by the CRNOP in order to create a superhydrophobic coating on beech sample previously treated by the CRNOP. In optimal conditions, a contact angle equal to 160 degrees could be reached. FTIR spectroscopy give evidence for Si-O-Si, Si-O-C and Si(CH3)(n) bands in a polysiloxane structure. (C) 2018 Elsevier B.V. All rights reserved.

A compromise between high power conversion efficiency and long-term stability of hybrid organic–inorganic metal halide perovskite solar cells is necessary for their outdoor photovoltaic application and commercialization. Herein, a method to improve the stability of perovskite solar cells under water and moisture exposure consisting of the encapsulation of the cell with an ultrathin plasma polymer is reported. The deposition of the polymer is carried out at room temperature by the remote plasma vacuum deposition of adamantane powder. This encapsulation method does not affect the photovoltaic performance of the tested devices and is virtually compatible with any device configuration independent of the chemical composition. After 30 days under ambient conditions with a relative humidity (RH) in the range of 35–60%, the absorbance of encapsulated perovskite films remains practically unaltered. The deterioration in the photovoltaic performance of the corresponding encapsulated devices also becomes significantly delayed with respect to devices without encapsulation when vented continuously with very humid air (RH > 85%). More impressively, when encapsulated solar devices were immersed in liquid water, the photovoltaic performance was not affected at least within the first 60 s. In fact, it has been possible to measure the power conversion efficiency of encapsulated devices under operation in water. The proposed method opens up a new promising strategy to develop stable photovoltaic and photocatalytic perovskite devices

Remote plasma sputtering (RPS) offers a high degree of control over the sputtering parameters used to deposit thin metallic films and has demonstrated a capability to control the media grain size distribution. Narrow grain size distributions remain a key requirement for future magnetic media. Here we report a comprehensive magnetometry, X-ray diffraction and transmission electron microscopy study of how RPS affects the grain size distribution of continuous, non-segregated L1 0 FePt thin films. These provide a model medium for heat-assisted magnetic recording and more generally for spintronic devices such as magnetoresistive random access memory and spin torque oscillators, where very high perpendicular magnetocrystalline anisotropy is required. Varying the target DC bias voltage, which in RPS can be tuned independently of the plasma generation, produces no meaningful, statistical change in average grain size, 6.5 ± 0.1 nm, for as-deposited, disordered FePt. Annealing at 800 °C creates the well-ordered L1 0 phase but results in an increased average grain size of 8.3–13.6 nm, and a significantly wider grain size distribution of 6.4–8.5 nm. These results show that whilst RPS is capable of producing well-ordered L1 0 FePt thin films, it does not offer an advantage in controlling the grain size of FePt, as reported in other thin film systems.

Today the IC manufacturing faces lots of problematics linked to the continuous down scaling of printed structures. Some of those issues are related to wet processing, which are often used in the IC manufacturing flow for wafer cleaning, material etching and surface preparation. In the current work we summarize the limitations for the next nodes of wet processing such as metallic contaminations, wafer charging, corrosion and pattern collapse. As a replacement, we promoted the isotropic chemical dry etching (CDE) which is supposed to fix all the above drawbacks. Etching steps of SI3N4 layers were evaluated in order to prove the interest of such technique.

We investigate the etching of a pure hydrogen plasma on graphite samples and graphene flakes on SiO$_2$ and hexagonal Boron-Nitride (hBN) substrates. The pressure and distance dependence of the graphite exposure experiments reveals the existence of two distinct plasma regimes: the direct and the remote plasma regime. Graphite surfaces exposed directly to the hydrogen plasma exhibit numerous etch pits of various size and depth, indicating continuous defect creation throughout the etching process. In contrast, anisotropic etching forming regular and symmetric hexagons starting only from preexisting defects and edges is seen in the remote plasma regime, where the sample is located downstream, outside of the glowing plasma. This regime is possible in a narrow window of parameters where essentially all ions have already recombined, yet a flux of H-radicals performing anisotropic etching is still present. At the required process pressures, the radicals can recombine only on surfaces, not in the gas itself. Thus, the tube material needs to exhibit a sufficiently low H radical recombination coefficient, such a found for quartz or pyrex. In the remote regime, we investigate the etching of single layer and bilayer graphene on SiO$_2$ and hBN substrates. We find isotropic etching for single layer graphene on SiO$_2$, whereas we observe highly anisotropic etching for graphene on a hBN substrate. For bilayer graphene, anisotropic etching is observed on both substrates. Finally, we demonstrate the use of artificial defects to create well defined graphene nanostructures with clean crystallographic edges., 7 pages, 4 color figures

We present a low-temperature versatile protocol for the fabrication of plasma nanocomposite thin films to act as tunable emitters and optical gain media. The films are obtained by the remote plasma-assisted deposition of a 4-(dicyano-methylene)-2-methyl-6-(4-dimethylamino-styryl)-4H-pyran (DCM) laser dye alongside adamantane. The experimental parameters that determine the concentration of the dye in the films and their optical properties, including light absorption, the refractive index, and luminescence, are evaluated. Amplified spontaneous emission experiments in the DCM/adamantane nanocomposite waveguides show the improvement of the copolymerized nanocomposites’ properties compared to films that were deposited with DCM as the sole precursor. Moreover, one-dimensional distributed feed-back laser emission is demonstrated and characterized in some of the nanocomposite films that are studied. These results open new paths for the optimization of the optical and lasing properties of plasma nanocomposite polymers, which can be straightforwardly integrated as active components in optoelectronic devices., The authors thank the European Regional Development Funds program (EU-FEDER), the Junta de Andalucia (TEP8067), and the Spanish Ministry of Economy and Competitiveness (Project Nos. MAT2016-79866-R, MAT2013-40852-R, MAT2013-42900-P, MAT2014-51937-C3-1-P, RECUPERA 2020, and IJCI-2014-21226) for their financial support.

This study examined the effect of a novel precursor on the growth behavior and structure of titanium dioxide (TiO2) thin films. TiO2 thin films were deposited by remote plasma atomic layer deposition (RPALD). Dimethylamin-cyclopentadienyl titanium, (CpN)Ti(NMe2)2, was used as a Ti precursor and oxygen plasma was used as a reactant. (CpN)Ti(NMe2)2 is a newly synthesized precursor for TiO2 deposition. Characteristics of TiO2 thin films deposited by (CpN)Ti(NMe2)2 were compared with those of films deposited using a titanium tetrakis isopropoxide (TTIP) precursor. A wide processing window from 170 to 400 °C was observed, and the growth rate was around 0.44 A/cycle at 200 °C. X-ray photoelectron spectroscopy (XPS) measurements revealed that nearly stoichiometric TiO2 films were deposited. The residual impurity concentrations inside the films were almost the same for (CpN)Ti(NMe2)2 and TTIP. TiO2 films deposited on ruthenium showed a pure rutile phase at a low deposition temperature and low power pre-treatment. Therefore, this TiO2 film is very promising for metal–insulator–metal (MIM) capacitor dielectrics for dynamic random access memory (DRAM) applications.

The degradation induced by oxygen (O 2 ) plasma irradiation to the various low dielectric constant materials (low- k ; k = 3.0–2.5) has been investigated in this study. The dielectric constant was observed to increase upon O 2 plasma treatment due to carbon atom depletion and Si OH bond formation, which is strongly influenced by the bonding structure or strength of the low- k materials, and less related to the porosity. Moreover, the O 2 damage can be suppressed by densifying the low- k film's surface induced by He/H 2 remote plasma treatment. Additionally, the role of ions, photons, and radicals in the plasma in inducing the low- k material degradation was clarified by using a special designed structure. The experimental results showed that all components in the plasma have contributions in degrading the electrical and reliability performance of low- k film. Moreover, the synergy between the radicals, the photons, and the ions enhanced the damage.

Ultrafiltration (UF) is considered as a potential alternative to gravity settling in liquid surfactant membrane process for fast separation of water-in-oil (W/O) emulsions from the external aqueous phase. Flux behavior was studied in this work during batch UF of W/O/W solutions by poly(vinylidene fluoride) (PVDF) membrane with a molecular weight cut-off of 30 kDa after the membrane was modified by remote cyclonic atmospheric-pressure plasma with argon gas and methane/argon gas mixture. Physicochemical properties of the membrane surfaces including hydrophilicity, functional group concentrations, and pore size distribution before and after plasma modifications were determined by static contact angle measurements, X-ray photoelectron spectroscopy, and capillary flow porometry, respectively. Higher surface concentrations of oxygen functional groups for plasma-functionalized membranes were observed compared to the unmodified membranes. It was shown that UF flux was significantly enhanced with the plasma-modified membranes under the conditions studied (feed, 5 vol% W/O emulsions; stirring, 300 rpm; pressure, 35–138 kPa). Resistance-in-series analysis of the flux data indicated that the proposed remote plasma treatment, particularly with methane/argon gas mixture, could considerably reduce both resistances due to solute adsorption and cake layer formation on the membrane surface, although the above two resistances always contributed more than 71% of the total filtration resistance.

We described thin nitrogen plasma-treated gate oxide film formed by rapid thermal process technology. This thin nitrogen plasma-treated gate oxide film has been formed using remote plasma nitridation process onto in situ steam generated oxide layer. We investigated the nitrogen profile within the gate dielectric film formed by this technique using SIMS analysis. The result shows that nitrogen concentration profile is composed of high at top surface and low at SiO2/Si interface. The peak concentration of nitrogen is placed at near top place and goes rapidly down to SiO2/Si interface. This nitrogen profile results in excellent boron diffusion barrier characteristics and superior interface properties for p+PMOSFET. We also performed the electrical analysis such as capacitance–voltage (C–V), gate leakage current, dielectric breakdown voltage and time-to-breakdown (TBD) measurement. It has been found that this thin nitrogen plasma-treated gate oxide film results in superior electrical reliability having significant lower leakage current, superior dielectric strength and outstanding TBD. Copyright © 2014 John Wiley & Sons, Ltd.

The few-view emission tomography (ET) of plasma, which introduces physical properties of objects into a reconstruction algorithm, requires a reliable experimental verification using independent methods for validating an adopted model of plasma inhomogeneities. The chosen test object—low-temperature argon plasma in a reactor with a remote plasma source—allows one to study the two-dimensional spatial distribution of a concentration of Ar+ ions, which is calculated using the two-view ET, and to verify results using direct measurements by a Langmuir multiprobe located in the plane of tomographic scanning. Studies are carried out for the chamber pressure 2–12 mTorr; the sensitivity of the ion-field homogeneity to the external magnetic field is estimated. A close agreement between concentration fields of Ar+, which are measured and reconstructed by tomography, is obtained. The divergence between the probe method and the ET data reconstruction with respect to two views is not above 10%.

Room-temperature atomic layer deposition (ALD) of TiO 2 was developed using tetrakis(dimethylamino)titanium (TDMAT) and a remote-plasma-excited water vapor. A growth rate of 0.157 nm/cycle at room temperature was achieved, and the TDMAT adsorption and its oxidation on TiO 2 were investigated by multiple-internal-reflection infrared absorption spectroscopy. Saturated adsorption of the TDMAT occurs at exposures of ∼1 × 10 6 Langmuir (1 Langmuir = 1 × 10 −6 Torr s) at room temperature, and the remote-plasma-excited water vapor is effective in oxidizing the TDMAT-saturated TiO 2 surface. The IR study suggests that the Ti-OH plays a role of adsorption site for TDMAT. The reaction mechanism of room-temperature TiO 2 ALD is discussed.

High-k, low leakage thin films are crucial components for dynamic random access memory (DRAM) capacitors with high storage density and a long storage lifetime. In this work, we demonstrate a method to increase the dielectric constant and decrease the leakage current density of atomic layer deposited BaTiO3 thin films at low process temperature (250 °C) using postdeposition remote oxygen plasma treatment. The dielectric constant increased from 51 (as-deposited) to 122 (plasma-treated), and the leakage current density decreased by 1 order of magnitude. We ascribe such improvements to the crystallization and densification of the film induced by high-energy ion bombardments on the film surface during the plasma treatment. Plasma-induced crystallization presented in this work may have an immediate impact on fabricating and manufacturing DRAM capacitors due to its simplicity and compatibility with industrial standard thin film processes.

The optimal development of silicon photonics could improve the current state of microelectronics technology. However due to the multiple parameters involved in the elaboration processes, it is not a simple task to fabricate and reproduce silicon emitting structures. In this paper we discuss the role played by ammonia in depositing silicon nanoparticles (Si-NPs) embedded in silicon nitride matrix by remote plasma enhanced chemical vapor deposition (RPECVD). We found that by varying the ammonia flow, the deposition rate changes. It was observed by high resolution transmission electron microscopy (HRTEM) that higher density and a lower average size of Si-NPs is achieved by increasing the ammonia flow. We recognized a linear behavior between the ammonia flow used to deposit a sample and its maximum photoluminescence (PL) emission peak. Finally we propose a model that allows to predict the maximum PL peak for a given ammonia flow within the range of 403–540 nm.

An argon plasma generated between the cone-shaped electrode powered by commercial electronic ballast and grounded plane electrode has been investigated. Since the electronic ballast has positive and negative cycle in a period, two different discharge modes of remote plasma—the normal glow discharge mode and the hollow cathode discharge mode—have been observed. It is noted that the hollow cathode discharge mode has wider operation window in gas pressure than the glow discharge one. The glow discharge started to be extinguished at pressure higher than 4.1 torr and turned to the hollow cathode discharge mode in the holes on ground plate, while the hollow cathode discharge mode kept growing until 10 torr. These results show that the stable operation window of the system could be defined by the glow discharge mode rather than the hollow cathode discharge mode and could be improved by optimizing the applied voltage waveform and electrode configuration.

We investigated the characteristics of silicon nitride (SiNx) thin films deposited by remote plasma atomic layer deposition (RPALD) using trisilyamine (TSA) and ammonia (NH3) plasma at low temperatures. Although the process window of SiNx thin films is 150–350 °C, considering the refractive index (RI), SiNx thin films deposited at 250–350 °C were focused on for analyses. All of the SiNx films were nearly stoichiometric, regardless of the deposition temperature. As the deposition temperature increased, the RI increased, while the hydrogen content decreased. The defect density also changed at higher deposition temperatures; as the deposition temperature increased, all of the trap densities increased because of the low-hydrogen content in the SiNx thin films. The characteristics of the SiNx thin film deposited by RPALD could be controlled to adjust the defect density for charge trap flash memory applications by changing the deposition temperature.

In the quest for materials with a lower dielectric constant and/or a higher Young’s modulus, new results on advanced low-k films are reported. These films are fabricated using a sequence of three process steps: a PECVD co-deposition of matrix skeleton and porogen, a remote plasma to remove the porogen and a UV cure to strengthen the film. In this study, most emphasis was put on the optimization of the remote plasma and of the UV cure step. In this way it was possible to obtain a film with dielectric constant as low as 1.82 and another with a dielectric constant of 2.02 combined with a Young’s modulus higher than 5 GPa. Besides, this series of films showed also a very good resistance against 0.5% HF etching. FTIR analyses indicated that during this HF etching a C–F bond is formed. A model for the HF etching of this porous low-k material is proposed.

We report the permeation barrier properties of Al 2 O 3 /ZrO 2 multi-layers deposited by remote plasma atomic layer deposition. Electrical Ca degradation tests were performed to derive the water vapor transmission rate (WVTR) of Al 2 O 3 , ZrO 2 and Al 2 O 3 /ZrO 2 multi-layers at 50 °C and 50% relative humidity (RH). Al 2 O 3 /ZrO 2 multi-layers exhibit better barrier properties than Al 2 O 3 and ZrO 2 layers, and when more individual layers were deposited in the same total thickness, the WVTR value was reduced further, indicating a better barrier property. The WVTR of the Al 2 O 3 and ZrO 2 layers were 9.5 × 10 −3 and 1.6 × 10 −2 g/m 2 day, respectively, but when deposited alternatively with 1 cycle of each layer, the WVTR decreased to 9.9 × 10 −4 g/m 2 day. X-ray diffraction results indicated that ZrO 2 has a monoclinic structure but Al 2 O 3 and Al 2 O 3 /ZrO 2 multi-layers show an amorphous structure. Cross sectional Al 2 O 3 /ZrO 2 multi-layer structures and the formation of a ZrAl x O y phase are observed by transmission electron microscopy (TEM). X-ray photoelectron spectrometry (XPS) results indicate that Al 2 O 3 and ZrO 2 contain 33.7% and 37.8%, respectively, Al–OH and Zr–OH bonding. However, the ZrAl x O y phase contained 30.5% Al–OH and Zr–OH bonding. The results of transmittance measurement indicate that overall, Al 2 O 3 , ZrO 2 and Al 2 O 3 /ZrO 2 multi-layers show high transmittance greater than 80% in the visible region.

Gallium nitride (GaN) films have been grown by using our newly developed Radical-Enhanced Metalorganic Chemical Vapor Deposition (REMOCVD) system. This system has three features: (1) application of very high frequency (60 MHz) power in order to increase the plasma density, (2) introduction of H 2 gas together with N 2 gas in the plasma discharge region to generate not only nitrogen radicals but also active NH x molecules, and (3) radical supply under remote plasma arrangement with suppression of charged ions and photons by employing a Faraday cage. Using this new system, we have studied the effect of the trimethylgallium (TMG) source flow rate and of the plasma generation power on the GaN crystal quality by using scanning electron microscopy (SEM) and double crystal X-ray diffraction (XRD). We found that this REMOCVD allowed the growth of epitaxial GaN films of the wurtzite structure of (0001) orientation on sapphire substrates with a high growth rate of 0.42 μm/h at a low temperature of 800 °C. The present REMOCVD is a promising method for GaN growth at relatively low temperature and without using costly ammonia gas.

A new screened remote plasma-enhanced atomic vapor deposition (SPEAVD) technique was studied for depositing Sb–Te phase-change materials inside trench structures with high aspect ratios. The theoretical model of the screening mechanism included the concepts of a plasma sheath and a sticking coefficient. Plasma’s limitation of poor step coverage was overcome by filtering its high-energy ions and electrons. Cross-sectional observation was conducted using field emission scanning electron microscopy (SEM). The trench-covering ability of SPEAVD was much better than that of direct remote PEAVD under broad chamber conditions. Surface morphology was observed by SEM and atomic force microscopy. The surface chemical state of the deposited film was measured by X-ray photoelectron spectroscopy. The crystallinity in various deposition temperatures was analyzed by X-ray diffraction measurements. The electrical characteristics of the films were measured by a four-point probe. We expect this research to provide a new deposition method that will allow fine control of step coverage and other characteristics.

Remote plasma processing (RPP) provides pathways to the formation of photovoltaic (PV) and thin-film-transistor (TFT) devices that include buried interfaces. This is made possible by separate and independent control of (i) plasma excited O- and N-atom deposition precursors in a up-stream plasma chamber, combined with (ii) down-stream injection of Si- and Ge-atoms with control gas flow rates providing control of buried interface bonding at monolayer levels. Devices with intrinsic, B p-type and P n-type “a-Si(H)” & “a-Si,Ge(H)” layers require 10% bonded H in monolayer (Si H arrangements) and deposition and/or annealing at temperatures between 240 and 275 °C. Deposition from SiH4 with either PH3 or B2H6 dopant gasses provides spectrally reflecting films which can be annealed yielding fine-grain films for gate, or source and drain regions for TFTs or FETs.