Showing papers on "Tantalum capacitor published in 1999"

Electric-field penetration into metals: consequences for high-dielectric-constant capacitors

Abstract: A consequence of the finite electronic screening length in metals is that electric fields penetrate short distances into the metal surface. Using a simple, semiclassical model of an idealized capacitor, we estimate the capacitance correction due to the distribution of displacement charge in the metal electrodes. We compare our result with experimental data from thin-film high-dielectric-constant capacitors, which are currently leading contenders for use in future high-density memory applications. This intrinsic mechanism contributes to the universally-seen decrease in measured dielectric constant with capacitor film thickness.

Ta2O5 thin films with exceptionally high dielectric constant

Abstract: We have achieved tantalum pentoxide (Ta2O5) thin films with extremely highly predominant 〈001〉 orientation The Ta2O5 thin films have an exceptionally high dielectric constant of 90–110, and capacitors using these Ta2O5 films as a dielectric layer show the high capacitance and low leakage current meeting the requirements for the new generation of memory devices

Fixed frequency regulation circuit employing a voltage variable dielectric capacitor

Abstract: Frequency regulating apparatus comprising a high power, voltage variable dielectric varactor or capacitor (or ferroelectric voltage variable dielectric capacitor) for use as a control element in the regulation circuit that actively tunes a resonant network to modulate power delivered to a load. The voltage variable dielectric capacitor comprises a substrate having a bottom electrode 33 formed thereon. A dielectric material is disposed on the substrate is a crystallized ceramic material that preferably comprises a barium, strontium, and titanium mixture. A top electrode is disposed on top of the crystallized ceramic material. Methods of fabricating the voltage variable dielectric varactor (capacitor) are also disclosed.

Integrated circuit device having dual damascene capacitor

Abstract: An integrated circuit device includes a dielectric layer having an opening therein, and a capacitor comprising in stacked relation a lower electrode lining the opening, a capacitor dielectric layer adjacent the lower electrode, and an upper electrode adjacent the capacitor dielectric layer. The capacitor has a substantially planar upper surface substantially flush with adjacent upper surface portions of the dielectric layer. Additionally, the edges of the lower electrode and the capacitor dielectric layer preferably terminate at the upper surface of the capacitor. Also, the capacitor dielectric may include a high-k, high quality and low leakage dielectric, and which prevents the reduction of the capacitor dielectric by the metal of the upper and lower metal electrodes.

Electrolytic capacitor and multi-anodic attachment

Abstract: A multi-anodic aluminum electrolytic capacitor includes an electrical connection to the multiple porous (e.g., tunnel-etched) anodes in an anode stack using a single anode tab that is attached only to a first anode. Other anodes are electrically coupled to the anode tab through the first anode. Anodes in the anode stack are in intimate physical and electrical contact with other such anodes as a result of layering effected by planar stacking or cylindrical winding. The need for separate tabs to different anode layers is eliminated or at least minimized, thereby reducing capacitor volume, increasing capacitor reliability, and reducing the cost and complexity of the capacitor manufacturing process for multi-anodic capacitors. The capacitor is capable of use in implantable defibrillators, camera photoflashes, and other electric circuit applications.

Electrolyte for use in a capacitor

Abstract: An electrolyte for activating an electrolytic or electrochemical capacitor is described. The electrolyte preferably includes a mixed solvent of water and ethylene glycol having an ammonium salt dissolved therein. An acid such as phosphoric or acetic acid is used to provide a pH of about 3 to 6. The electrolyte is particularly useful for activating a ruthenium oxide/tantalum capacitor having an anode breakdown voltage in the range of 175 to 300 volts.

Preparation of conductive polymers from stabilized precursor solutions

Abstract: Conductive polymers are prepared from a stabilized solution containing a monomer, an Fe(III) oxidizing agent, and a mixed solvent. The solvents are selected to stabilize the Fe(III) oxidizing agent and monomer in solution while allowing highly conducting polymers to be produced upon evaporating the lower-boiling solvent. The higher-boiling solvent does not appreciably complex with Fe(III), while the lower-boiling solvent forms a weak complex with Fe(III). The mixed-solvent system of the present invention may be used for preparing a conductive polymer counter electrode in a solid tantalum capacitor by polymerizing the monomer inside a porous tantalum pellet.

Chip type solid electrolytic capacitor and its manufacturing method

Abstract: A chip type solid electrolytic capacitor of the present invention has a section formed in a step-wise manner on a cathode lead frame that is connected with a capacitor element. An anode lead wire of the capacitor element is resistance welded to the top of a reversed V-letter shaped structure formed by folding part of an anode lead frame into halves. Further, with the chip type solid electrolytic capacitor of the present invention, part of respective cathode and anode lead frames is exposed outside in such a way as being made flush with the periphery of a resin package, thereby each serving as a terminal. Accordingly, a space problem due to the terminals has been eliminated and the anode lead wire can be made short, thus allowing the volume of a capacitor element employed to be increased. As a result, a chip type solid electrolytic capacitor having a large capacity with its outer dimensions is kept the same as a prior art capacitor can be obtained.

Electrolytic capacitor and its manufacturing method

Abstract: A electrolytic capacitor includes (a) a capacitor element having a positive electrode, a negative electrode, and a solid organic conductive material disposed between the positive electrode and the negative electrode, (b) an electrolyte, (c) a case for accommodating the capacitor element and the electrolyte, and (d) a sealing member disposed to cover the opening of the case. The solid organic conductive material has at least one of organic semiconductor and conductive polymer. In this constitution, an electrolytic capacitor having excellent impedance characteristic, small current leak, excellent reliability, and high dielectric strength is obtained.

Multilayer electrode for ferroelectric and high dielectric constant capacitors

Abstract: A ferroelectric or high dielectric constant capacitor having a multilayer lower electrode comprising at least two layers—a platinum layer and a platinum-rhodium layer—for use in a random access memory (RAM) cell The platinum layer of the lower electrode adjoins the capacitor dielectric, which is a ferroelectric or high dielectric constant dielectric such as BST, PZT, SBT or tantalum pentoxide The platinum-rhodium layer serves as an oxidation barrier and may also act as an adhesion layer for preventing separation of the lower electrode from the substrate, thereby improving capacitor performance The multilayer electrode may have titanium and/or titanium nitride layers under the platinum-rhodium layer for certain applications The capacitor has an upper electrode which may be a conventional electrode or which may have a multilayer structure similar to that of the lower electrode Processes for manufacturing the multilayer lower electrode and the capacitor are also disclosed

Methods of forming integrated circuit capacitors having composite titanium oxide and tantalum pentoxide dielectric layers therein

Abstract: Methods of forming integrated circuit capacitors (e.g., DRAM capacitors) include the steps of forming a first capacitor electrode (e.g., polysilicon electrode) on a substrate and then forming a titanium nitride layer on the first capacitor electrode. A tantalum pentoxide dielectric layer is then formed on an upper surface of the titanium nitride layer. A step is then performed to convert the underlying titanium nitride layer into a titanium oxide layer. A second capacitor electrode is then formed on the tantalum pentoxide layer. The step of converting the titanium nitride layer into a titanium oxide layer is preferably performed by annealing the tantalum pentoxide layer in an oxygen ambient in a range between about 700° C. and 900° C. This oxygen ambient provides free oxygen to fill vacancies within the tantalum oxide layer and also provides free oxygen which diffuses into the underlying titanium nitride layer.

Three-dimensional ferroelectric capacitor structure for nonvolatile random access memory cell

Abstract: A capacitor structure or an array of capacitors and a method of fabricating the structure utilize the contours of a cavity created in a layer stack to form two three-dimensional electrode plates. The three-dimensional electrode plates reduce the lateral size of the capacitor structure. The fabrication of the capacitor structure is compatible to conventional CMOS processing technology, in which the resulting capacitor structure may become embedded in a CMOS device. As an example, the capacitor structure may be fabricated along with a MOS transistor to produce a one-transistor-one-capacitor nonvolatile memory cell. Preferably, the three-dimensional electrode plates are made of platinum (Pt) or iridium (Ir) and the capacitor dielectric is a ferrous-electric material, such as lead-zirconate-titanate (PZT) or barium-strontium-titanate (BST). The electrode plates and the capacitor dielectric are formed by depositing layers of appropriate materials within the cavity, which has been formed to include tapering walls in a dielectric layer of the layer stack. Next, portions of the deposited layers, or a “capacitor stack,” are removed down to the surface of the dielectric layer such that only the materials that were deposited within the cavity of the dielectric layer are left. The remaining materials form the electrode plates, as well as the capacitor dielectric. In the preferred embodiment, the selective removal of the capacitor stack portions is accomplished by planarizing the capacitor stack using a Chemical Mechanical Planarization (CMP) process. Alternatively, a sputter etch-back process may be utilized to remove the capacitor stack portions.

Method for forming dielectric layer of capacitor

Abstract: A method for forming the dielectric layer of a capacitor. A titanium layer and a tantalum pentoxide layer are sequentially formed over a polysilicon lower electrode. A high-temperature treatment is performed so that titanium in the titanium layer and silicon in the polysilicon lower electrode react to form a titanium silicide layer at their interface. Titanium in the titanium layer also reacts with oxygen in the atmosphere to form a titanium oxide layer at its interface with the tantalum pentoxide layer. The titanium silicide layer, the titanium oxide layer and the tantalum pentoxide layer together constitute a composite dielectric layer with a high dielectric constant capable of increasing the capacitance of the capacitor.

Electrolytic solution for use in electrolytic capacitor and electrolytic capacitor

Abstract: An electrolytic solution for use in an electrolytic capacitor, comprising a solution containing a solvent consisting of 20 to 80% by weight of an organic solvent and 80 to 20% by weight of water, and at least one electrolyte selected from the group consisting of a carboxylic acid or a salt thereof and an inorganic acid or a salt thereof, having added thereto at least one nitro compound selected from the group consisting of nitrophenol, nitrobenzoic acid, dinitrobenzoic acid, nitroacetophenone and nitroanisole. The electrolytic solution has a low impedance and excellent low-temperature stability, along with good working life characteristics, and it can also exhibit an excellent hydrogen gas absorption function when an electrolytic solution contains a highly increased amount of water in its mixed solvent or when an electrolytic capacitor is used under high temperature conditions.

Capacitor and its manufacturing method

Abstract: A capacitor of the present invention employs one of i) polyimide directly formed by electrodeposition, ii) organic high polymer having a specific structure formed by electrodeposition, and iii) a composite film of the organic high polymer and oxide film of a conductor as dielectrics formed on the surface-roughened conductor. The organic high polymer used in the present invention contains carboxylic radical in its molecular structure. The capacitor of the present invention further comprises an opposite electrode at least containing conductive high polymer on the dielectrics. This conductive high polymer is formed by chemical oxydation-polymerization or both chemical oxydation-polymerization and electro-polymerization. The capacitor element as configured above is strong to mechanical stress, and possible to apply pressure during lamination. By laminating many of capacitor elements as configured above, a capacitor with large capacitance but small equivalent serial resistance, small leak current, and good frequency characteristics is obtained. A method for manufacturing capacitors of the present invention comprises the steps of forming a dielectric layer made of organic high polymer or a composite film of the organic high polymer and oxide film of conductor on a surface-roughened conductor; forming an insulating layer at least on the conductor; forming an opposite electrode on said dielectric layer to manufacture capacitor elements; and laminating more than one capacitor elements and connecting each other to form a laminated capacitor.

Leakage current reduction of a tantalum oxide layer via a nitrous oxide high density annealing procedure

Abstract: A process of fabricating a capacitor structure, using a tantalum oxide capacitor dielectric layer, has been developed. The process features deposition of a thin, high dielectric constant tantalum oxide layer, followed by a high density plasma anneal procedure, used to reduce the leakage current in the as-deposited tantalum oxide layer, that can evolve during normal operating conditions of the capacitor structure. The high density plasma anneal procedure is performed in a nitrous oxide ambient, at a temperature of about 400° C.

Thin film capacitor formed in via

Abstract: There is provided a thin film capacitor including (a) a lower electrode, (b) an insulating layer formed burying the lower electrode therein and formed with a via-hole reaching the lower electrode, (c) a dielectric layer formed on an inner sidewall of the via-hole and covering an exposed surface of the lower electrode therewith, and (d) an upper electrode surrounded by the dielectric layer. In accordance with the thin film capacitor, the upper electrode is formed to be buried in the via-hole formed above the lower electrode. Hence, it is possible to prevent short-circuit between the upper and lower electrodes, and degradation of the dielectric layer during fabrication of a thin film capacitor, both of which enhances reliability of a capacitor. In addition, a multi-layered wiring structure could be readily fabricated on the thin film capacitor.

Electrolytic capacitor and method of producing the same

Abstract: The present invention provides an electrolytic capacitor having a large capacitance sufficiently close to its design capacitance, and a method of easily producing such an electrolytic capacitor. In this method, a cathode-side conductive polymer layer or a electrolyzing electrode is formed on at least one side surface of an anode valve metal foil having through holes 20 and a coarsened surface, electrolysis is carried out in a conductive monomer solution, with the polymer layer used as the anode, and an electrolytically-formed conductive polymer layer is formed on the surface of the dielectric oxide film of the valve metal foil, thereby obtaining an electrolytic capacitor. As a result, it is possible to easily obtain an electrolytic capacitor having a large capacitance sufficiently close to its design capacitance.

Directionally-grown capacitor anodes

Abstract: A dendritic sponge which is directionally-grown on a substrate material has a high surface to volume ratio and is suitable for forming anodes for highly efficient capacitors. A dielectric film is formed on the sponge surface by oxidizing the surface. In a preferred embodiment, the dielectric is grown on titanium sponge and is doped with oxides of Ca, Mg, Sr, Be, or Ba to improve the film's dielectric constant or with higher valent cations, such as Cr 6+ , V 5+ , Ta 5+ , Mo 6+ , Nb 5+ , W 6+ , and P 5+ , to reduce the oxygen vacancy concentration and leakage current of the dielectric film. A capacitor formed from the sponge includes a cathode electrolyte which serves as an electrical conductor and to repair the dielectric film by re-oxidizing the anode surface at areas of local breakdown. Sponges of titanium, tantalum, and aluminum form efficient dielectric films. In another embodiment, sponges of elements which do not form efficient dielectric films are coated with a dielectric material. Capacitors formed with titanium sponges have energy densities of 10 −2 to 50 Watt hours and power densities of 100,000 to 10,000,000 Watts per kilogram of titanium.

Use of anodic tantalum pentoxide for high-density capacitor fabrication

Abstract: In this work we report on very thin (10 to 100 nm) tantalum oxide fabricated by anodic oxidation of tantalum nitride and tantalum silicide to be used as the dielectric of high density MIM and MIS capacitors. These films exhibit greatly improved leakage currents, breakdown voltage and very low defect density, thus allowing the fabrication of large area capacitors. Several counter and bottom electrodes have been used and compared. The effects of the different processing conditions (top-electrode metals, annealing conditions, bottom electrode stoichiometry) on the capacitor performances are extensively discussed throughout this work. The nitrogen content of tantalum nitride films seems to have an important influence on the insulator quality. Leakage currents in the insulator have been carefully studied in order to determine the nature and physical origin of the dominant conduction mechanisms in the insulator. The electrical behaviour of the resulting high-density MIM capacitors has been extensively characterized. Finally, we describe a new method to fabricate MIS diodes with anodic tantalum oxide as insulator.

Method and apparatus for the in-circuit testing of a capacitor

Abstract: A test apparatus and method of testing a capacitor while it is still in-circuit incorporation a sequence of tests including a DC capacitance value measurement, a measurement of the DC current paths in parallel with the capacitor, a measurement of the equivalent series resistance of the capacitor, and an AC impedance measurement of the capacitor and its associated circuitry.

Method of making a semiconductor variable capacitor

Abstract: A variable capacitor in a semiconductor device is described in which the capacitance is varied by the movement of a dielectric material in the space between the plates of the capacitor in response to an external stimulus. A method of making such a variable capacitor is also described in which the capacitor is built in a layered structure with the top layer including a portion of dielectric material extending into the space between the capacitor plates. After formation of the top layer, an intermediate layer is etched away to render the top layer flexible to facilitate movement of the dielectric material in the space between the capacitor plates.

Monolayer capacitor element and solid electrolytic multilayer capacitor

Abstract: The present invention provides a solid electrolytic multilayer capacitor excellent in yield and capability, and provides a monolayer capacitor element for use in the manufacture of the solid electrolytic multilayer capacitor. In the multilayer solid electrolyte capacitor of the present invention, a solid electrolytic multilayer capacitor 25 in which a plurality of monolayer capacitor elements 7 are stacked such that the anode areas 11 aligned in the same direction are stacked and bonded onto a lead frame 9 on the anode side and the cathode areas are stacked and bonded onto a lead frame 8 on the cathode side so as to have an unfolded fan shape widening toward the distal end of the cathode area from the anode area 11 side, to provide a multilayer capacitor element 19 and the periphery of the multilayer capacitor element 19 that are covered and sealed with an armoring resin 23 . The monolayer capacitor element 7 preferably has a constitution such that the end part of the anode substrate 1 having thereon a dielectric oxide layer 2 worked out to an anode area 11 , the cathode area 6 is formed by providing a solid electrolyte layer 4 on the dielectric oxide layer 2 in the area exclusive of the anode area 11 and an electrically conducting layers 5 and 6 on the solid electrolyte layer 4 , and the thickness S 2 at the distal end of the cathode area is larger than the thickness S 1 at the base part of the cathode area.

Enhanced dielectric properties of modified Ta2O5 thin films

Abstract: Tantalum oxide (Ta2O5) is a promising high dielectric constant material for the DRAM applications because of its ease of integration compared to other complex oxide dielectrics. The dielectric constant and thermal stability characteristics of bulk Ta2O5 samples were reported to enhance significantly through small substitutions of Al2O3. However, this improvement in the dielectric constant of (1-x)Ta2O5-xAl2O3 is not clearly understood. The present research attempts to explain the higher dielectric constant of (1-x)Ta2O5-xAl2O3 by fabricating thin films with enhanced dielectric properties. A higher dielectric constant of 42.8 was obtained for 0.9Ta2O5–0.1Al2O3 thin films compared to that reported for pure Ta2O5 (25–30). This increase was shown to be closely related to a-axis orientation. Pure Ta2O5 thin films with similar a-axis orientation also exhibited a high dielectric constant of 51.7, thus confirming the orientation effect. The leakage current properties and the reliability characteristics were also found to be improved with Al2O3 addition.

Multi-layer metal capacitor

Abstract: A structure of a capacitor includes an electromigration layer, which is located on a dielectric layer and serves as a lower electrode of the capacitor. A pattered capacitor dielectric layer is located on the electromigration layer, and a patterned metallic layer is located on the capacitor dielectric layer and serves as an upper electrode of the capacitor.

Capacitor film for a self-healing film capacitor

Abstract: The invention relates to a metallization for a film capacitor, wherein a dielectric capacitor film provided with a metallic coating is wound into a capacitor element in the running direction of the capacitor film, whereby the coating is provided with a segmentation.

Method for manufacturing capacitor of semiconductor memory device having tantalum oxide film

Abstract: A method for manufacturing a capacitor having a dielectric film formed of a tantalum oxide film. The method includes forming a lower electrode that is electrically connected to an active region of a semiconductor substrate. A pre-treatment film including a component selected from a group consisting of silicon oxide, silicon nitride, and combinations thereof, is formed on the surface of the lower electrode. A dielectric film is formed on the pre-treatment film using a Ta precursor. The dielectric film includes a first dielectric layer deposited at a first temperature selected from a designated temperature range, and a second dielectric layer deposited at a second temperature different from the first temperature and selected from the same designated temperature range. A thermal treatment is thereafter performed on the dielectric film in an oxygen atmosphere.

Semiconductor variable capacitor and method of making same

Abstract: A variable capacitor in a semiconductor device is described in which the capacitance is varied by the movement of a dielectric material in the space between the plates of the capacitor in response to an external stimulus. A method of making such a variable capacitor is also described in which the capacitor is built in a layered structure with the top layer including a portion of dielectric material extending into the space between the capacitor plates. After formation of the top layer, an intermediate layer is etched away to render the top layer flexible to facilitate movement of the dielectric material in the space between the capacitor plates.