Simulation de profils de gravure et de dépôt à l’échelle du motif pour l’étude des procédés de microfabrication utilisant une source plasma de haute densité à basse pression

En lien avec l’avancée rapide de la réduction de la taille des motifs en microfabrication, des processus physiques négligeables à plus grande échelle deviennent dominants lorsque cette taille s’approche de l’échelle nanométrique. L’identification et une meilleure compréhension de ces différents processus sont essentielles pour améliorer le contrôle des procédés et poursuivre la «nanométrisation» des composantes électroniques. Un simulateur cellulaire à l’échelle du motif en deux dimensions s’appuyant sur les méthodes Monte-Carlo a été développé pour étudier l’évolution du profil lors de procédés de microfabrication. Le domaine de gravure est discrétisé en cellules carrées représentant la géométrie initiale du système masque-substrat. On insère les particules neutres et ioniques à l’interface du domaine de simulation en prenant compte des fonctions de distribution en énergie et en angle respectives de chacune des espèces. Le transport des particules est effectué jusqu’à la surface en tenant compte des probabilités de réflexion des ions énergétiques sur les parois ou de la réémission des particules neutres. Le modèle d’interaction particule-surface tient compte des différents mécanismes de gravure sèche telle que la pulvérisation, la gravure chimique réactive et la gravure réactive ionique. Le transport des produits de gravure est pris en compte ainsi que le dépôt menant à la croissance d’une couche mince. La validité du simulateur est vérifiée par comparaison entre les profils simulés et les observations expérimentales issues de la gravure par pulvérisation du platine par une source de plasma d’argon.

Plasma polymerization of C[subscript 4]F[subscript 8] thin film on high aspect ratio silicon molds

High aspect ratio polymeric micro-patterns are ubiquitous in many fields ranging from sensors, actuators, optics, fluidics and medical. Second generation PDMS molds are replicated against first generation silicon molds created by deep reactive ion etching. In order to ensure successful demolding, the silicon molds are coated with a thin layer of C[subscript 4]F[subscript 8] plasma polymer to reduce the adhesion force. Peel force and demolding status are used to determine if delamination is successful. Response surface method is employed to provide insights on how changes in coil power, passivating time and gas flow conditions affect plasma polymerization of C[subscript 4]F[subscript 8].

The effect of N+ ion energy on the properties of ion bombarded plasma polymer films

This work describes the influence of the ion bombardment on the electrical, optical and mechanical properties of polymer films deposited from radio-frequency plasmas of benzene. Irradiations were conducted using N+ at 5 x 10(19) ions/m(2), varying the ion energy, E-0, from 0 to 150 keV. Film elemental composition was determined by Rutherford backscattering spectroscopy. Electrical resistivity and hardness were obtained by the two-point probe and nanoindentation technique, respectively. Ultraviolet-visible spectroscopy was employed to investigate the optical constants of the samples. Etching rate was determined by exposure of the films to reactive oxygen plasmas. Ion bombardment induced gradual loss of H and increase in C and O concentrations with Eo. As a consequence the electrical, optical and mechanical properties were drastically affected. Interpretation of these results is proposed in terms of chain cross-linking and unsaturation. (C) 2001 Elsevier B.V. B.V. All rights reserved.

Atmospheric plasma treatment of carbon fibers for enhancement of their adhesion properties

Plasma processing of carbon fibers (CFs) is aimed to provide better contact and adhesion between individual plies without decrease in the CF mechanical resistance. This paper deals with surface modification of CFs by an atmospheric pressure dielectric barrier discharge (DBD) for enhancing the adhesion between the CF and the polymeric matrix. The scanning electron microscopy of the treated samples revealed many small particles distributed over entire surface of the fiber. These particles are product of the fiber surface etching during the DBD treatment that removes the epoxy layer covering as-received samples. The alteration of the CF surface morphology was also confirmed by the Atomic force microscopy (AFM), which indicated that the CF roughness increased as a result of the plasma treatment. The analysis of the surface chemical composition provided by X-ray photoelectron spectroscopy showed that oxygen and nitrogen atoms are incorporated onto the surface. The polar oxygen groups formed on the surface lead to the increasing of the CF surface energy. The results of interlaminar shear strength test (short beam) of CFs/polypropylene composites demonstrated a greater shear resistance of the composites made with CFs treated by DBD than the one with untreated fibers. Both the increase in surface roughness and the surface oxidation contribute for the enhancement of CF adhesion properties. © 2012 IEEE.

Implantação iônica por imersão em plasma - IIIP - de argônio, nitrogênio e hélio em hexametildissilazano polimerizado a plasma

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Treatment of Reticulated Vitreous Carbon by Dielectric Barrier Discharge Plasma for Electrodes Production

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Amorphous silicon carbonitride films modified by plasma immersion ion implantation

Amorphous silicon carbonitride (a-SiCN:H) films were deposited from hexamethyldisilazane (HMDSN) organic compounds via radio-frequency (RF) glow discharges. Afterwards the films were bombarded, from 15 to 60 min, with nitrogen ions using Plasma Immersion Ion Implantation (PIII) technique. X-ray photoelectron spectroscopy (XPS) showed that O-containing groups increased, while C-C and/or C-H groups decreased with treatment time. This result indicates chemical alterations of the polymeric films with the introduction of polar groups on the surface, which changes the surface wettability. In fact, the hydrophobic nature of a-SiCN:H films (contact angle of 100 degrees) was changed by nitrogen ion implantation and, and after aging in atmosphere air, all samples preserved the hydrophilic character (contact angle <80 degrees) independently of treatment time. The exposure of the films to oxygen plasma was performed to evaluate the etching rate, which dropped from 24% to 6% while the implantation time increased from 15 to 60 min. This data suggests that Pill increased the film structure strength, probably due to crosslinking enhancement of polymeric chains. Therefore, the treatment with nitrogen ions via Pill process was effective to modify the wettability and oxidation resistance of a-SiCN:H films. (C) 2014 Elsevier Ltd. All rights reserved.

Avaliação do efeito do plasma não térmico na resistência adesiva à dentina supericial e profunda

Pós-graduação em Odontologia Restauradora - ICT

IN-SITU TEM PLASMA CHIP NANOFABRICATION AND CHARACTERIZATION

A silicon-based microcell was fabricated with the potential for use in in-situ transmission electron microscopy (TEM) of materials under plasma processing. The microcell consisted of 50 nm-thick film of silicon nitride observation window with 60μm distance between two electrodes. E-beam scattering Mont Carlo simulation showed that the silicon nitride thin film would have very low scattering effect on TEM primary electron beam accelerated at 200 keV. Only 4.7% of primary electrons were scattered by silicon nitride thin film and the Ar gas (60 μm thick at 1 atm pressure) filling the space between silicon nitride films. Theoretical calculation also showed low absorption of high-energy e-beam electrons. Because the plasma cell needs to survive the high vacuum TEM chamber while holding 1 atm internal pressure, a finite element analysis was performed to find the maximum stress the low-stress silicon nitride thin film experienced under pressure. Considering the maximum burst stress of low-stress silicon nitride thin film, the simulation results showed that the 50 nm silicon nitride thin film can be used in TEM under 1 atm pressure as the observation window. Ex-situ plasma generation experiment demonstrated that air plasma can be ignited at DC voltage of 570. A Scanning electron microscopy (SEM) analysis showed that etching and deposition occurred during the plasma process and larger dendrites formed on the positive electrode.

Avaliação da contaminação microbiológica de drogas vegetais e potencial descontaminação por plasma

A qualidade, eficácia e segurança no emprego de drogas vegetais dependem, entre outras questões, de sua qualidade sanitária. Sua origem e manuseio, em condições no geral inadequadas, propiciam biocarga elevada e abrangente, o que implica riscos para saúde. O presente trabalho objetivou conhecimento da microbiota das plantas estudadas e o desenvolvimento de estudos de sua descontaminação por plasma, tendo-se analisado os parâmetros físicos que influenciaram este processo. O projeto possibilitou a descontaminação de drogas vegetais com alta carga microbiana. Estudou-se a alcachofra (Cynara scolymus L.), camomila (Chamomilla recutita (L.) Rauschert.), ginco (Ginkgo biloba L.) e guaraná (Paullinia cupana Kunth), adotando parâmetros de processo que alegadamente permitem a integridade dos princípios ativos termossensíveis. Para isso, foi empregado reator disponível no Laboratório de Sistemas Integráveis, pertecente à Escola Politécnica da Universidade de São Paulo, em sistema com acoplamento capacitivo modo RIE (Reactive Ion Etching). Neste sistema, trabalhou-se com oxigênio adicionado de peróxido de hidrogênio. Todos os processos de descontaminação foram desenvolvidos a temperatura ambiente, sob diferentes parâmetros físicos complementares. A eficácia do processo foi investigada, empregando-se contagem de microrganismos heterotróficos, assim como pesquisa de indicadores de patogênicos (Staphylococcus aureus, Pseudomonas aeruginosa, Salmonella spp, Escherichia coli). As avaliações microbiológicas, quantitativas e qualitativas, assim como os estudos decorrentes dos dados obtidos, foram desenvolvidos no Laboratório de Controle Biológico da Faculdade de Ciências Farmacêuticas - USP. Os resultados obtidos após a descontaminação por plasma de oxigênio (100%), a potência de 150 W, evidenciaram redução de até 4 ciclos de aeróbicos totais. No processo por plasma peróxido de hidrogênio (20%) e oxigênio (80%), a uma potência de 150 W, observou-se a redução de até 4 ciclos log de aeróbios totais para as drogas vegetais deste estudo. A presença de substâncias químicas complexas da camomila, que contêm óleo volátil, flavonóides, aminoácidos, ácidos graxos, sais minerais, cumarinas, mucilagens e ácidos orgânicos, interferem no processo por plasma provavelmente em decorrência de a mucilagem formar um filme protetor, impedindo a difusão gasosa em ambos os processos por plasma. Assim, não só a camomila mas também o guaraná, com biocargas iniciais respectivamente de 6,6x106 UFC/g e 2,7x106 UFC/g, mantiveram-se com níveis de contaminação da mesma ordem de grandeza, após os desafios com plasma. A contagem bacteriana da alcachofra (fornecedor B), que foi submetida ao processo de descontaminação através do plasma O2 (100%), (potência de 150 W, pressão de 100 mTorr e vazão de 200 sccm), sofreu redução de dez vezes, independentemente do tempo do processo. Possivelmente este resultado, que aparenta inconsistência, decorre da ação apenas superficial do plasma. A descontaminação por processo de plasma de oxigênio e de peróxido de hidrogênio para a alcachofra (fornecedor B) não foi eficaz, devido à predominância de elementos lignificados. As amostras de alcachofra (fornecedor C), com baixa percentagem de vasos de xilema lignificados e fibras lignificadas evidenciaram a maior eficácia do processo por plasma, pois possibilitou grande difusão gasosa sobre as amostras. O estudo permitiu ainda concluir que à aplicabilidade do plasma na descontaminação de drogas vegetais depende da resistência dos microrganismos, mas igualmente das características da planta, sejam aquelas de natureza morfoanatômica, enzimática ou química. Estudos específicos devem ser desenvolvidos para cada situação.

Surface, Thermal and Antimicrobial Release Properties of Plasma-Treated Zein Films

The effects of dielectric barrier discharge plasma treatment on zein film containing thymol as an active ingredient were evaluated. The plasma discharge was optically characterized to identify the reactive species. A significant increase in the film roughness (p < 0.05) was observed due to the etching effect of DBD plasma, which was correlated with the increase in the diffusion rate of thymol in the food simulant. The diffusion of thymol from the zein film was measured in aqueous solution. The kinetics of thymol release followed the Fick’s law of diffusion as shown by the high correlation coefficients between experimental and theoretical data. No significant change (p > 0.05) was observed for the thermal properties of the antimicrobial films after DBD plasma treatment.

Microwave Plasma Assisted ALD Development for the Deposition of Gate Oxides & ALD of High-k Dielectrics

The semiconductor industry's urge towards faster, smaller and cheaper integrated circuits has lead the industry to smaller node devices. The integrated circuits that are now under volume production belong to 22 nm and 14 nm technology nodes. In 2007 the 45 nm technology came with the revolutionary high- /metal gate structure. 22 nm technology utilizes fully depleted tri-gate transistor structure. The 14 nm technology is a continuation of the 22 nm technology. Intel is using second generation tri-gate technology in 14 nm devices. After 14 nm, the semiconductor industry is expected to continue the scaling with 10 nm devices followed by 7 nm. Recently, IBM has announced successful production of 7 nm node test chips. This is the fashion how nanoelectronics industry is proceeding with its scaling trend. For the present node of technologies selective deposition and selective removal of the materials are required. Atomic layer deposition and the atomic layer etching are the respective techniques used for selective deposition and selective removal. Atomic layer deposition still remains as a futuristic manufacturing approach that deposits materials and lms in exact places. In addition to the nano/microelectronics industry, ALD is also widening its application areas and acceptance. The usage of ALD equipments in industry exhibits a diversi cation trend. With this trend, large area, batch processing, particle ALD and plasma enhanced like ALD equipments are becoming prominent in industrial applications. In this work, the development of an atomic layer deposition tool with microwave plasma capability is described, which is a ordable even for lightly funded research labs.

Controlled surface nanotopography and oxygen plasma treatment of PEEK to improve cellular response

Poly(aryl-ether-ether-ketone) (PEEK) is a semi crystalline polymer which exhibits properties that make it an attractive choice for use as an implant material. It displays natural radiolucency, and MRI compatibility, as well as good chemical and sterilization resistance, both of which make it of particular interest in orthopaedic implants. However, PEEK has demonstrated poor cellular adhesion both in vitro and in vivo. This is problematic as implant surfaces that do not develop a layer of adhesive cells are at risk of undergoing fibrous encapsulation, which in turn leads to lack of a strong interface between the implant device and the patient tissue, which can in turn lead to failure of the implant and revision surgery . As incorporating nanotopography into a polymer surface has been demonstrated to be able to direct the differentiation behaviour of stem cells, a possible solution to PEEKs underlying issues with poor cellular response would be to incorporate specific nanoscale topography into the material surface through injection moulding, and then analysing if this is a viable method for addressing PEEKs issues with cellular response. In addition to nanoscale topography, the experimental PEEK surfaces were treated with oxygen plasma to address the underlying cytophobicity of the material. As this type of treatment has been documented to be capable of etching the PEEK surface, experiments were carried out to quantify the effect of this treatment, both on the ability of cells to adhere to the PEEK surface, as well as the effect it has upon the nanotopography present at the PEEK surface. The results demonstrated that there were a range of plasma treatments which would significantly improve the ability of cells to adhere to the PEEK surface without causing unacceptable damage to the nanotopography. Three different types of cells with osteogenic capacity were tested with the PEEK surfaces to gauge the ability of the topography to alter their behaviour: SAOS-2, osteoprogenitors and 271+ MSCs. Due to PEEKs material properties (it is non transparent, exhibits birefringence and is strongly autofluorescent) a number of histological techniques were used to investigate a number of different stages that take place in osteogenesis. The different cell types did display slightly different responses to the topographies. The SAOS-2 cells cultured on surfaces that had been plasma treated for 2 minutes at 200W had statistically significantly higher levels of von Kossa staining on the NSQ surface compared to the planar surface, and the same experiment employing alizarin red staining, showed a statistically significantly lower level of staining on the SQ surface compared to the planar surface. Using primary osteoprogenitor cells designed to look into if whether or not the presence of nanotopography effected the osteogenic response of these cells, we saw a lack of statistically significant difference produced by the surfaces investigated. By utilising HRP based immunostaining, we were able to investigate, in a quantitative fashion, the production of the two osteogenic markers osteopontin and osteocalcin by cells. When stained for osteocalcin, the SQ nanotopography had total percentage of the surface with stained material, average area and average perimeter all statistically significantly lower than the planar surface. For the cells that were stained for osteopontin, the SQ nanotopgraphy had a total percentage of the surface with stained material, average area and average perimeter all highly statistically significantly lower than those of the planar surface. Additionally, for this marker the NSQ nanotopography had average areas and average perimeters that were highly significantly higher than those of the planar surface. There were no significant differences for any of the values investigated for the 271+ MSC’s When plasma treatment was varied, the SAOS-2 cells demonstrated an overall trend i.e. increasing the energy of plasma treatment in turn leads to an increase in the overall percentage of staining. A similar experiment employing stem cells isolated from human bone marrow instead of SAOS-2 cells showed that for polycarbonate surfaces , used as a control, mineralization is statistically significantly higher on the NSQ nanopattern compared to the planar surface, whereas on the PEEK surfaces we observe the opposite trend i.e. the NSQ nanotopography having a statistically significantly lower amount of mineralization compared to the planar surface at the 200W 2min and 30W 1min plasma treatments. The standout trend from the PEEK results in this experiment was that the statistically significant differences on the PEEK substrates were clustered around the lower energy plasma treatments, which could suggest that the plasma treatment disrupted a function of the nanotopograhy which is why, as the energy increases, there are less statistically significant differences between the NSQ nanotopography and the Planar surface This thesis documents the response of a number of different types of cells to specific nanoscale topographies incorporated into the PEEK surface which had been treated with oxygen plasma. It outlines the development of a number of histological methods which measure different aspects of osteogenesis, and were selected to both work with PEEK, and produce quantitative results through the use of Cell Profiler. The methods that have been employed in this body of work would be of interest to other researchers working with this material, as well as those working with similarly autofluorescent materials.

Testosterone Therapy Differently Regulates The Anti- And Pro-inflammatory Cytokines In The Plasma And Prostate Of Rats Submitted To Chronic Ethanol Consumption (uchb).

Ethanol consumption damages the prostate, and testosterone is known by anti-inflammatory role. The cytokines were investigated in the plasma and ventral prostate of UChB rats submitted or not to testosterone therapy by ELISA and Western blot, respectively. Additionally, inflammatory foci and mast cells were identified in the ventral prostate slides stained by hematoxylin and eosin and toluidine blue, respectively. Inflammatory foci were found in the ethanol-treated animals and absent after testosterone therapy. Plasma levels of IL-6 and IL-10 were not changed while TNFα and TFG-β1 were increased in the animals submitted testosterone therapy. Regarding to ventral prostate, IL-6 did not alter, while IL-10, TNFα, and TFG-β1 were increased after testosterone therapy. Ethanol increases NFR2 in addition to high number of intact and degranulated mast cell which were reduced after testosterone therapy. So, ethanol and testosterone differentially modulates the cytokines in the plasma and prostate.

Propylthiouracil Quantification In Human Plasma By High-performance Liquid Chromatography Coupled With Electrospray Tandem Mass Spectrometry: Application In A Bioequivalence Study.

A rapid, sensitive and specific method for quantifying propylthiouracil in human plasma using methylthiouracil as the internal standard (IS) is described. The analyte and the IS were extracted from plasma by liquid-liquid extraction using an organic solvent (ethyl acetate). The extracts were analyzed by high performance liquid chromatography coupled with electrospray tandem mass spectrometry (HPLC-MS/MS) in negative mode (ES-). Chromatography was performed using a Phenomenex Gemini C18 5μm analytical column (4.6mm×150mm i.d.) and a mobile phase consisting of methanol/water/acetonitrile (40/40/20, v/v/v)+0.1% of formic acid. For propylthiouracil and I.S., the optimized parameters of the declustering potential, collision energy and collision exit potential were -60 (V), -26 (eV) and -5 (V), respectively. The method had a chromatographic run time of 2.5min and a linear calibration curve over the range 20-5000ng/mL. The limit of quantification was 20ng/mL. The stability tests indicated no significant degradation. This HPLC-MS/MS procedure was used to assess the bioequivalence of two propylthiouracil 100mg tablet formulations in healthy volunteers of both sexes in fasted and fed state. The geometric mean and 90% confidence interval CI of Test/Reference percent ratios were, without and with food, respectively: 109.28% (103.63-115.25%) and 115.60% (109.03-122.58%) for Cmax, 103.31% (100.74-105.96%) and 103.40% (101.03-105.84) for AUClast. This method offers advantages over those previously reported, in terms of both a simple liquid-liquid extraction without clean-up procedures, as well as a faster run time (2.5min). The LOQ of 20ng/mL is well suited for pharmacokinetic studies. The assay performance results indicate that the method is precise and accurate enough for the routine determination of the propylthiouracil in human plasma. The test formulation with and without food was bioequivalent to reference formulation. Food administration increased the Tmax and decreased the bioavailability (Cmax and AUC).