Showing papers on "Layer by layer published in 1997"

Molecular-Level Processing of Conjugated Polymers. 4. Layer-by-Layer Manipulation of Polyaniline via Hydrogen-Bonding Interactions

Abstract: The molecular-level layer-by-layer processing of polyaniline with a variety of different nonionic water soluble polymers has been demonstrated. This new type of layer-by-layer adsorption process is driven by hydrogen-bonding interactions and has been accomplished with poly(vinylpyrrolidone), poly(vinyl alcohol), poly(acrylamide), and poly(ethylene oxide). FTIR spectroscopy measurements confirm a high level of hydrogen bonding between polyaniline and the nonionic polymer in the multilayer films. The effects of solution pH and polymer molecular weight on the deposition process were investigated. Comparisons with polyaniline films assembled via an electrostatic mechanism with sulfonated polystyrene indicate that the nonionic polymers adsorb onto polyaniline with a greater density of loops and tails and form highly interpenetrated bilayers with a high polyaniline content. The conductivities of these self-assembled multilayer films were found to be on the order of 1−4 S/cm for films doped with methane sulfonic...

Assembling Alternate Dye−Polyion Molecular Films by Electrostatic Layer-by-Layer Adsorption

Abstract: Electrostatic alternate adsorption was successfully employed for low-molecular-weight dyes, leading to a large variety of dye−polyion layer-by-layer assemblies. The assembling process of individual dye−polyion layers of Congo Red (CR)−poly(diallyldimethylammonium chloride) (PDDA) was investigated by using a quartz crystal microbalance (QCM). The in-situ QCM measurement revealed that the dye adsorption occurred at a rate similar to that of conventional polyion adsorption. Successful assembly of the CR layer was confirmed also by increasing intensities in the UV adsorption. The molecular aggregation within the dye layer was inferred from the observed absorption shift in the case of CR−PDDA. Apparently, stable film formation is promoted by dye aggregation in the adsorbed layer, although the extent of film growth was independent of conceivable aggregation in the solution. Successive frequency decreases due to film growth were observed for other representative dyes under optimized conditions. Comparison of the...

Layer-by-layer deposition : A tool for polymer surface modification

Abstract: Layer-by-layer deposition of polyelectrolytes onto poly(ethylene terephthalate) (PET) film is reported as a method for polymer surface modification. Poly(allylamine hydrochloride) (PAH) and poly(sodium styrenesulfonate) (PSS) were sequentially adsorbed to unmodified (neutral) PET as well as PET samples that had been surface modified to contain carboxylate (PET-CO2-) and ammonium (PET-NH3+) functionality. XPS and contact angle data indicate that the layers are extremely thin (2−6 A) and stratified to a significant extent. The wettability of the multilayer films is controlled by the outermost polyelectrolyte layer and the thickness of the individual layers (sublayers have an influence in multilayers with thinner layers). The substrate surface chemistry controls the thickness of all of the layers in the multilayer assembly as well as the stoichiometry (ammonium ion:sulfonate ion ratio) of the deposition process. The effect of the ionic strength of the polyelectrolyte solutions was studied for the case of the...

Molecular-Level Processing of Conjugated Polymers. 3. Layer-by-Layer Manipulation of Polyaniline via Electrostatic Interactions

Abstract: Multilayer thin films comprised of sequentially adsorbed layers of partially doped polyaniline and a polyanion, sulfonated polystyrene, were fabricated via the use of a simple layer-by-layer molecular-level processing scheme. Using this simple multilayer polymer adsorption process, uniform thin films of polyaniline in the 40−600 A thickness range were readily fabricated onto a variety of different substrates. Doping of these films with strong acids such as HCl and methane sulfonic acid results in electrically conductive thin films with conductivities comparable to those obtained with spin cast films (0.5−1.0 S/cm). The adsorption process used to fabricate the films was found to be driven primarily by the electrostatic attractions developed between the partially doped chains of polyaniline (polycation) and the negatively charged chains of the polyanion.

Preparation of the Layer-by-Layer Deposited Ultrathin Film Based on the Charge-Transfer Interaction

Abstract: This paper is concerned with a novel layer-by-layer adsorption method for preparing multilayer assemblies of polymeric materials. We employed two kinds polymers, poly[2-(9-carbazolyl)ethyl methacry...

Thin Film Technology Handbook

Abstract: Contributors. Preface. Film Deposition Techniques and Processes. Pattern Generation Techniques. Properties of Thin film Materials. Principles and Properties of Semiconductor Thin Films. Design Guidelines for Thin film Components and Construction of Thin Film Modules. Characterization of Semiconductor Thin Films: A Compendium of Techniques. Diamond Films. Thin Film Optical Materials. Thin Film Packaging and Interconnect. Thin Film for Microwave Hybrids. Yield, Testing, and Reliability.

Ionic Effects of Sodium Chloride on the Templated Deposition of Polyelectrolytes Using Layer-by-Layer Ionic Assembly

Abstract: A new method for the patterning of ionic layer-by-layer assembled films with micron-sized features is presented. Self-assembled monolayers (SAMs) were used as templates to direct the deposition of sulfonated polystyrene (SPS) and poly(diallyldimethylammonium chloride) (PDAC) multilayers onto a surface. Both polyelectrolytes were assembled electrostatically from dilute solutions (10 and 20 mM on a repeat unit basis) with varying amounts of sodium chloride. The ionic content was varied from 0 to 4 M NaCl. The optimal conditions for templating were found at moderate salt contents. At high salt contents (≥1 M NaCl) the templating behavior of the chemically patterned SAM surface completely reversed due to electrostatic screening and dehydration of an oligo(ethylene glycol)surface, indicating that ionic strength can be used to dramatically alter polyion deposition behavior on the functionalized surface.

Nonlinear Hairy Layer Theory of Electrophoretic Fingerprinting Applied to Consecutive Layer by Layer Polyelectrolyte Adsorption onto Charged Polystyrene Latex Particles

Abstract: The consecutive layer-by-layer adsorption of poly(allylamine hydrochloride) (PAH) and poly(styrenesulfonate) (PSS) on colloidal charged latex particles is investigated by measuring the electrophoretic mobility as a function of pH and ionic strength over a broad range (electrophoretic fingerprinting) Meaningful interpretation of the data required the development of a nonlinear approach to hairy particle electrophoresis including dissociation, adsorption, and association Steric and electrostatic exclusion of mobile ions from the hairy layer has been considered Also, the surface conductivity correction is extended to the case of charged hairy layer particles We deposited up to three polyelectrolyte layers The following were found: (i) Each layer deposition is accompanied by charge overcompensation and (ii) Not only the top layer but also the underneath layers and the naked latex particle surface contribute to the particle mobility This can be interpreted as an incomplete coverage or a polyelectrolyte

Layer-by-layer electrostatic self-assembly of nanoscale Fe3O4 particles and polyimide precursor on silicon and silica surfaces

Abstract: Monolayer and multilayer ultrathin films comprised of nanosized iron oxide (Fe3O4) particles and polyimide molecules have been fabricated on single crystal silicon and quartz substrates by a novel layer-by-layer electrostatic self-assembly process. This process involves the alternate dipping of a substrate into an aqueous solution of anionic polyimide precursor (polyamic acid salt, PAATEA), followed by dipping into an aqueous solution of polycation polydiallyldimethylammonium chloride (PDDA) which coats on nanoscale Fe3O4 particles as a stabilizer. The growth process and the structure have been characterized using UV-vis spectroscopy, contact angle, and ellipsometry measurements. The results suggest that well-ordered uniform monolayer and multilayer magnetic films have been formed on silicon and silica surfaces. A recently developed highly sensitive fiber optic magnetic field sensor was used to probe the small magnetic field intensity produced by the multilayer films.

Thin film transistors fabricated on plastic substrates

Abstract: A thin film transistor is described incorporating a gate electrode, a gate insulating layer, a semiconducting channel layer deposited on top of the gate insulating layer, an insulating encapsulation layer positioned on the channel layer, a source electrode, a drain electrode and a contact layer beneath each of the source and drain electrodes and in contact with at least the channel layer, all of which are situated on a plastic substrate. By enabling the use of plastics having low glass transition temperatures as substrates, the thin film transistors may be used in large area electronics such as information displays and light sensitive arrays for imaging which are flexible, lighter in weight and more impact resistant than displays fabricated on traditional glass substrates. The thin film transistors are useful in active matrix liquid crystal displays where the plastic substrates are transparent in the visible spectrum. Enablement of the use of such plastics is by way of the use of polymeric encapsulation films to coat the surfaces of the plastic substrates prior to subsequent processing and the use of novel low temperature processes for the deposition of thin film transistor structures.

Structural forces in thin films made from polyelectrolyte solutions

Abstract: We have studied thin liquid films made from semidilute polyelectrolyte solutions. The disjoining pressure (due to interaction between film surfaces) has been measured as a function of the film thickness. We observe pressure oscillations, corresponding to film stratification. The oscillations become sharper as the polymer concentration c increases, and disappear when salt is added. The period of the oscillations scales as ${c}^{\ensuremath{-}1/2}$. We propose that the observed stratification is related to the polymer network and the size of the steps to the mesh size $\ensuremath{\xi}$.

Surface ``Priming'' for Layer-by-Layer Deposition: Polyelectrolyte Multilayer Formation on Allylamine Plasma-Modified Poly(tetrafluoroethylene)

Abstract: Allylamine plasma polymerization is reported as a method to surface-modify PTFE and to prepare substrates that promote layer-by-layer assembly of polyelectrolytes. Two conditions for the plasma polymerization that differ in radiofrequency power were studied. Both conditions (10 and 50 W) produce substrates that support layer-by-layer assembly, and well-defined multilayer structures are apparent in samples with greater than ∼10 layers. The substrates prepared at lower power yield more reproducible initial layer data; infrared spectra indicate a higher surface density of amine groups in the samples prepared at 10 W that likely leads to a higher surface charge density upon exposure to acidic aqueous solution. Poly(allylamine hydrochloride) and poly(sodium styrenesulfonate) were used to construct multilayer assemblies. XPS and contact angle data indicate stratified layers. XPS analysis also indicates that the stoichiometry of the assembly process is two ammonium ions per sulfonate group and that the average i...

Role of the hydrogen plasma treatment in layer-by-layer deposition of microcrystalline silicon

Abstract: We have investigated the role of hydrogen in hydrogenated microcrystalline silicon (μc-Si:H) formation using hydrogen plasma treatments, in particular examining the possibility of subsurface reaction due to permeating hydrogen atoms, which leads to the crystallization of hydrogenated amorphous silicon (a-Si:H). It is demonstrated that the hydrogen plasma treatment of a-Si:H film on the anode using a cathode covered by a-Si:H film, which is inevitably coated during the deposition period, gives rise to the deposition of μc-Si:H over the a-Si:H layer, i.e., chemical transport takes place. It is also found that the pure hydrogen plasma treatment using a clean cathode induces only etching of the a-Si:H layer. These results imply that the present hydrogen plasma condition does not cause crystallization of a-Si:H but only etching, and that careful experimentation is required to determine the real subsurface reaction due to atomic hydrogen.

Transfer method of thin film device, thin film device, thin film integrated circuit device, active matrix substrate, liquid crystal display and electronic equipment

Abstract: PROBLEM TO BE SOLVED: To enable independently and freely selecting a substrate to be used at the time of manufacturing a thin film device and a substrate to be used at the time of, e.g. real use of a product, and enable transferring the thin film device on the substrate to be used at the time of real use while the lamination order at the time of manufacturing the thin film device is maintained. SOLUTION: A first isolation layer like amorphous silicon is arranged on a substrate of high reliability into which a laser light can be transmitted, and a thin film device 140 like a TFT is formed on the substrate. A second isolation layer 160 like a hot-melt adhesive layer is formed on the thin film device 140, and a primary transferring member 180 is formed on the second isolation layer 160. Bonding force of the primary isolation layer is weakened, e.g. by irradiating the first isolation layer with a light, and the substrate is eliminated, so that a thin film device 140 is primarily transferred on the primary transferring member. A secondary transferring member 200 is bonded to the lower surface of the exposed thin film device via an adhesive layer 190. Bonding force is weakened, e.g. by hot-melting the second isolation layer 160, and the primary transferring member is eliminated. Thereby the thin film device 140 is secondarily transferred on the secondary transferring member.

Separating method, method for transferring thin film device, thin film device, thin film integrated circuit device, and liquid crystal display device manufactured by using the transferring method

Abstract: A method for transferring a thin film device on a substrate to a transferring body comprising the step of forming a separating layer on the substrate, the step of forming a transferred layer containing the thin film device on the separating layer, the step of joining the transferred layer containing the thin film device to the transferring body with an adhesive layer in between, the step of causing separation in the separating layer and/or on the boundary of the separating layer by irradiating the separating layer with light, and the step of separating the substrate from the separating layer.

Film which can be lettered using a laser beam

Abstract: This invention relates to film which is lettered with a laser beam comprising at least one protective film which is transparent to the laser beam, at least one opaque layer which is ablated by the laser beam, and at least one contrast-forming layer on its bottom. The abatable layer is preferably a metallic layer and can have a color like the contrast-forming layer. The color of the metallic layer is different from the color of the contrast-forming layer. The contrast-forming layer is either applied, imprinted or varnished onto the metallic layer. The contrast-forming layer can be at least one plastic film. On a side of the contrast-forming layer facing away from the metallic layer there is an adhesive layer which is covered with a carrier material, for example, an adhesive-repellant carrier film.

Alternate layer-by-layer assembly of organic dyes and proteins is facilitated by pre-mixing with linear polyions

Abstract: In the preparation of ultrathin films by alternate assembly, prior mixing with linear polyions facilitates stable adsorption of small-molecule dyes and direct assembly of globular proteins and micro-plates.

Method for fabrication of thin film resistor

Abstract: A method for forming a thin film resistor. There is first provided an insulator substrate. There is then formed upon the insulator substrate a blanket thin film resistive layer. There is then removed through a non-photolithographic etching method a portion of the blanket thin film resistive layer to form upon the substrate a patterned thin film resistive layer. Finally, there is then formed through a non-photolithographic printing method upon the patterned thin film resistive layer a patterned conductor lead layer. Alternatively, the portion of the blanket thin film resistive layer may be removed to form the patterned thin film resistive layer after the patterned conductor lead layer is formed upon the blanket thin film resistive layer. Additionally, the insulator substrate may be scribed before or after forming the blanket thin film resistive layer upon the insulator substrate to form a contiguous substrate chip upon which is formed the patterned thin film resistive layer and the patterned conductor lead layer, thus forming a contiguous thin film resistor chip within the insulator substrate. The contiguous thin film resistor chip may then be parted from the insulator substrate to form a discrete thin film resistor chip through physical fracture without cutting the insulator substrate.

Method for preparing layered structure including oxide superconductor thin film

Abstract: The invention provides a method for preparing a layered structure comprising a lower thin film composed of an oxide superconductor and an upper thin film composed of a material different from the oxide superconductor on a substrate. The lower thin film is deposited by a molecular beam deposition process and the upper thin film is deposited by a process having a deposition rate faster than that of the molecular beam deposition process.

On the accuracy of the quartz-crystal microbalance (QCM) in thin-film depositions

Abstract: The quartz-crystal microbalance (QCM) is traditionally used as a thin-film deposition monitor. The most commonly used monitor crystal is AT-cut quartz vibrating in its thickness shear mode. The mass of the deposited film on the quartz crystal's surface is indicated by the change of its resonance frequency. With the introduction of the z-matchEM technique in the 1970s, the accuracy of the QCM dramatically improved. This technique takes into account the mismatch of acoustic impedance between the quartz crystal and the deposited thin film. In recent years, new methodologies have been proposed to improve thhe accuracy of the QCM even further. For many years, we have carefully gathered a vast amount of data on the deposition of various metals, dielectrics and alloys on quartz crystals. In this paper, we report results of the comparison of the recently proposed methods with the Z-match technique, using the gravimetric measurement of deposited mass on the quartz crystals as the benchmark. We also report an extension formula, which broadens the validity of the z-match technique beyond a normalized frequency shift of 50%.

Deposition of n-type diamondlike carbon by using the layer-by-layer technique and its electron emission properties

Abstract: We have studied the electron emission behavior of the diamondlike carbon (DLC) films by plasma enhanced chemical vapor deposition using a layer-by-layer deposition, in which the deposition of a thin layer of DLC and a CF4 plasma exposure on its surface were carried out alternatively. The electron emission current increases with CF4 plasma exposure time. The increase in emission current appears to be due to the n-type behavior of the DLC.

Method for forming a thin film transistor

Abstract: Method for forming a polycrystalline silicon (ploy-Si) film of a semiconductor device includes forming the gate electrode on a substrate and depositing a dielectric layer on the substrate and the conductive layer. Then a first layer (microcrystalline silicon:μc-Si) is formed on the dielectric layer and a second layer (hydrogenated amorphous silicon:a-Si:H) is deposited on the first layer. Noted that the polycrystalline silicon (poly-Si) can be fabricated by applying the laser annealing to the first layer and the second layer to transform them to poly-Si. Annealing the first layer and the second layer by laser, followed by fabricating the source and drain electrodes, thus the TFT with good electrical characteristics is fabricated.

Method for producing a thin film magnetic head

Abstract: A longitudinal bias layer and an electrode layer are formed on a non-magnetic material layer. The longitudinal bias layer and the electrode layer are partially removed by an etching technique so that a narrow gap defining the track width Tw is formed in the longitudinal bias layer and the electrode layer. Furthermore, a three-layer film consisting of, from bottom to top, a magnetoresistance effect layer, a non-magnetic layer, and a transverse bias layer, or otherwise a spin valve film consisting of a free magnetic layer, a non-magnetic layer, a fixed magnetic layer and a bias layer is formed on the above structure. The three-layer film or the spin valve film is then partially removed by an etching technique so that the three-layer film or the spin valve film remains only in the above-described narrow gap formed in the longitudinal bias layer and the electrode layer. The shape of the side walls of the three-layer film or the spin valve film is precisely determined by the side walls of the longitudinal bias layer and the electrode layer. The resultant three-layer film or the spin valve film exhibits excellent magnetic detection characteristics. Furthermore, the longitudinal bias layer has good magnetic coupling with the magnetoresistance effect layer.

Surface plasmon resonance-sensing device

Abstract: PROBLEM TO BE SOLVED: To measure a resonance angle economically and stably by forming a multilayer film of a metallic thin film and a dielectric thin film on a prism and forming a polymer film of polysaccharide or the like as a fixation carrier for biologic molecules on the multilayer film. SOLUTION: The surface plasmon resonance-sensing device has a first metallic thin film layer 16 formed on a prism or substrate, a dielectric layer 17 on the first metallic thin film layer and a second metallic thin film layer 18 on the dielectric layer. The prism is formed of, e.g. quarts or glass which is transparent to ultraviolet rays, visible rays and near infrared rays and has a larger index of refraction than a liquid sample. The metallic thin film layers 16, 18 are formed of, e.g. gold or silver in a uniform thickness, and preferably have flat surfaces and good adhesion to a layer therebelow. The dielectric thin film layer 17 is formed of a material transparent to ultraviolet rays, visible rays and near infrared rays, for example, SiO 2 , SiO or the like. The polysaccharide is glucose or the like using, for instance, dextran sulfate as an antibody-fixing carrier. COPYRIGHT: (C)1998,JPO

Observation of oxide/Si(001)-interface during layer-by-layer oxidation by scanning reflection electron microscopy

Abstract: We have found that terrace contrast of oxidized Si(001) substrate observed with a scanning reflection electron microscopy (SREM) is reversed by progress in thermal oxidation by one atomic layer of Si. The cause for such terrace contrast reversion is that reflection electron intensity depends on Si-bond direction at oxide/Si interface. This fact was confirmed by calculations based on a multiple scattering theory. The motion of oxide/Si-bulk interface can be, thus, observed by SREM. The reversion and continuous change of the terrace contrast indicate that oxidation occurs monolayer by monolayer on Si(001) substrate.