Showing papers on "Tantalum capacitor published in 1992"

Compact surface mount solid state capacitor and method of making same

Abstract: An improved surface mountable tantalum capacitor and method of making same are disclosed. In accordance with the method of tubular tantalum container is fully or partially filled with tantalum powder, sintered to bond the powder to itself and to the container and thereafter conventionally processed to form dielectric and counter-electrode coatings. An anode termination is secured to an exterior surface of the container and a cathode termination is secured to a portion of the counter-electrode exposed through an opening in the container. The resultant capacitor is characterized by high capacitance per volume, a small footprint, shock resistance and low ESR.

Capacitor used in an integrated circuit and comprising opposing electrodes having barrier metal films in contact with a dielectric film

Abstract: On a first conductor layer of a capacitor element of an IC and in contact with a dielectric film made of a particular dielectric material, a first barrier metal film is made of platinum, palladium, tantalum, or titanium nitride. A second barrier metal film is made of a similar material in contact with the dielectric film and on a second conductor layer. The particular dielectric material is either tantalum oxide or a perovskite oxide, such as strontium titanate or a composite of lead zirconate and lead titanate. In cooperation with such a dielectric film, the first and the second barrier metal films make it possible to provide a compact capacitor having a great and reliable capacitance. The capacitor element is manufactured like a conventional one except for use of the particular dielectric material and for manufacturing steps of forming the first and the second barrier metal films and may be an MOS, MIS, or MIM capacitor or a multilayer wired capacitor.

High dielectric constant capacitor and method for manufacturing the same

Abstract: A high dielectric constant film comprised of at least a first dual-film layer, which includes a first tantalum oxide film, and a first metal oxide film which is made of a metal oxide whose valence is smaller than that of tantalum, and whose dielectric constant is equal to or greater than that of tantalum oxide. The first metal oxide film preferably has a thickness of less than approximately 50 angstroms, in order to thereby avoid the formation of a columnar structure, which has been identified as a principal cause of the high leakage current problem which has plagued presently available high dielectric constant capacitors. The first tantalum oxide film preferably has a thickness in the range of between approximately 5 angstroms to approximately 200 angstroms, with the ratio of the thickness of the first tantalum oxide film to the thickness of the first metal oxide film being in the range of 1:10 to 100:1. The high dielectric constant film preferably further includes a plurality of additional dual-film layers formed on the first dual-film layer, to thereby provide a multilayer high dielectric constant film. Each of the additional dual-film layers is preferably of the same construction as that of the first dual-film layer. The present invention also encompasses a high dielectric constant capacitor which incorporates the above-described high dielectric constant film, and a method for manufacturing the same.

High-permittivity dielectric capacitor for use in a semiconductor device and process for making the same

Abstract: A high-permittivity dielectric capacitor (28) having a refractory-metal oxide layer (16) framing the first electrode (14) of the capacitor (28) and separating a high-permittivity dielectric layer (24) from an insulating layer (12) underlying the capacitor (28). The high-permittivity dielectric layer (16) makes contact with the first electrode (14) through an opening (18) in the refractory-metal oxide layer (16). The refractory-metal oxide layer (16) separates the high-permittivity dielectric layer (24) from the insulating layer (12) in all regions away from the opening (18) in the refractory-metal oxide layer (16). During fabrication of the capacitor (28), when the high-permittivity dielectric layer (24) is patterned, the refractory-metal oxide layer (16) provides an etch-stop.

Fibrous tantalum and capacitors made therefrom

Abstract: A method of making a tantalum capacitor of improved specific capacitance (and volumetric efficiency) is described Short tantalum fibers are precipitated out of a carrier liquid to form a felt, or tumbled to form fiber containing particles, and in either case subsequently bonded so as to form a felt or particles containing the fibers in random orientation in substantially non-aligned array These particles or felt are heated to bond the fibers together, purify and (optionally) cylindricalize them The felt or particles can be processed in conventional fashion thereafter to form the capacitor Cylindricalized fibers and pellets of increased surface area are also described

Method for forming a transistor and a capacitor for use in a vertically stacked dynamic random access memory cell

Abstract: A method for forming a transistor and a capacitor to provide, in one form, a DRAM cell (10). The capacitor of cell (10) is formed within a substrate (12). The capacitor has a first capacitor electrode (16) and a second capacitor electrode (20). A dielectric layer (18) is formed as an inter-electrode capacitor dielectric. A first transistor current electrode (36) is formed overlying and electrically connected to the first capacitor electrode (16). A channel region (38) is formed overlying the first transistor current electrode (36). A second transistor current electrode (40) is formed overlying the channel region (38). A conductive layer (30) is formed laterally adjacent the channel region (38) and isolated from the substrate (12) by dielectric layers (22 and 28). A conductive layer (30) functions as a gate electrode for the transistor and a sidewall dielectric (34) functions as a gate dielectric.

Copper lead frame material for tantalum capacitor and manufacture thereof

Abstract: PURPOSE:To provide a copper lead frame material for a tantalum capacitor having excellent heat peeling resistance and exhibiting satisfactory solder wettability even after heat treatment. CONSTITUTION:A copper lead frame material for a tantalum capacitor has a base material 4 made of German silver, a nickelplated layer 2 formed on the material 4, an intermetallic compound layer 3 of tin and copper formed in thickness of 0.1 to 2.0mum on the layer 2, and a tin-plated layer 1 (or solder- plated layer) formed on the layer 3. The layer 3 is formed by forming, for example, a copper-plated layer of 0.1 to 1.0mum thick on the nickel-plated layer, forming a tin- or solder-plated layer on the copper-plated layer, and then reflowing or melted tin-plating or melted solder-plating on the copper-plated layer.

Method of manufacturing a highly integrated semiconductor memory device with trench capacitors and stacked capacitors

Abstract: A highly integrated semiconductor memory device comprises a plurality of memory cells formed by alternately disposing a stack-type capacitor cell and a combined stack-trench type capacitor cell both in row and column directions. Each storage electrode of the capacitor of the memory cell is extended to overlap with the storage electrode of the capacitor of the adjacent memory cell. The combined stack-trench type capacitor is formed into the substrate to increase the storage capacitance thereof which allow the storage capacitance of the stack-type capacitor to increase by extending the storage electrode of the capacitor. Due to the alternate arrangement of stack-trench type capacitor and stack-type capacitor, step coverage, leakage current and soft errors of stack-trench type capacitor are prevented.

Process for manufacturing tantalum capacitors

Abstract: A process for manufacturing tantalum capacitors in which microwave energy is used to sinter a tantalum powder compact in order to achieve higher surface area and improved dielectric strength. The process comprises cold pressing tantalum powder (12) with organic binders and lubricants to form a porous compact (14). After removal of the organics, the tantalum compact is heated to 1300 to 2000 °C by applying microwave radiation. The compact is then anodized to form a dielectric oxide layer (16) and infiltrated with a conductive material (20) such as Mn02. Wire leads (13 and 22) are then attached to form a capacitor (10) and the capacitor is hermetically packaged to form the finished product.

Multilayer solid electrolytic capacitor and fabrication thereof

Abstract: PURPOSE: To provide a multilayer solid electrolytic capacitor excellent in electric characteristics, e.g. frequency characteristics of impedance and leak current characteristics, which exhibits stabilized characteristics over a wide temperature range and contributes to downsizing and high capacity. CONSTITUTION: After forming through tunnel pits 1, countless cubic pits are formed to obtain an anode base body 3 having surfaces of sponge-like pits 2. A plurality of anode base bodies 3 are then laminated to produce an anode laminate which is then subjected to formation thus forming a dielectric oxide 6 on the surface. A conductive polymeric layer 7 composed of a chemical polymerization film and an electrolytic polymerization film is formed entirely on the surface of dielectric oxide 6 and a cathode lead-out part, i.e., a conductor layer 8, is formed thereon thus obtaining a capacitor element 9. COPYRIGHT: (C)1994,JPO&Japio

Printed circuit board with internal capacitor

Abstract: A printed circuit board (PCB) has an internal capacitor (26) with at least two conductive foils (28, 30) and one intermediate dielectric sheet (36A), the dielectric sheet including spacer material (37A) extending therethrough for uniformly maintaining its thickness and dielectric material (37B) developing a uniform dielectric constant therein, the spacer material and dielectric material maintaining the uniform thickness and uniform dielectric constant of the internal capacitor during final lamination of formation of the PCB. The internal capacitor may depend upon borrowed capacitance with the total effective capacitance of the internal capacitor being less than the combined capacitive requirements of devices coupled with the internal capacitor. In one embodiment, at least a portion of the internal capacitor is formed simultaneously with final formation of the PCB by an in situ method. In another embodiment, the internal capacitor is formed with multiple capacitor elements, at least one conductive foils in the internal capacitor forming a portion of two different capacitor elements, the number of dielectric sheets in the internal capacitor equaling the number of capacitor elements, the number of conductive foils in the internal capacitor equalling the number of capacitor elements plus one.

Electrical destruction of amorphous tantalum and niobium oxide films

Abstract: The author presents the results of a study on the processes of the destruction of amorphous tantalum and niobium oxides in thin anodic layers on metal surfaces in strong electric fields. The kinetics of the processes under study determines the reliability of oxide dielectric capacitors. The destruction processes take place in one of two forms, i.e. a breakdown of the oxide dielectric in capacitor structures whose counterelectrode is constituted of a solid phase material (metal, semiconductor, or solid electrolyte), or an electrically stimulated growth of metal oxide crystals in metal-oxide-electrolyte capacitor structures. By studying the breakdown of a highly homogeneous oxide dielectric, it is shown that such a breakdown is preceded by storage processes (dielectric aging). A number of experimental techniques are presented for detecting, in an amorphous oxide dielectric, structural defects which accelerate film destruction processes in a strong electric field and thus are potentially dangerous under the prolonged thermoelectric stresses applied to capacitor structures. These techniques are based on structure-sensitive kinetic phenomena in amorphous metal oxide dielectrics. >

High frequency design and performance of tabular capacitors

Abstract: The electrical design, analysis and performance of tabular capacitors are presented. Simple formulas for capacitances are derived for spiral and concentric type tabular capacitors. By numerical methods the regions of greatest electric stress in the dielectric are found. The influence of bumps on the capacitor plates is examined by the method of conformal transformation. It is shown that a small circular ridge running the length of the capacitor can reduce the voltage rating by 50%. The inductance of the capacitor sets an upper bound on the highest frequency at which the capacitor behaves ideally. It was previously shown that high frequency behavior is influenced by the particular connection used in a capacitor. For a spiral wound tabular capacitor one type of connection is considered, and its equivalent circuit is exhibited. For concentric cylindrical tubular capacitors the only type of connection possible is the one considered for the spiral-wound capacitors. For that configuration a closed form electrostatic induction coefficient and inductance coefficient matrices are presented and used for high frequency analyses. >

Method for manufacturing semiconductor memory device having a stacked type capacitor

Abstract: A capacitor of a semiconductor memory device includes a planar type capacitor portion formed on a surface of an impurity region and a stacked type capacitor portion extending above the gate electrode. The stacked capacitor portion has a three-layer structure of polycrystalline silicon in which upper, lower and side surfaces of a lower electrode are surrounded by a dielectric layer and the upper electrode. A portion of a dielectric layer in the stacked capacitor portion is coupled to another dielectric layer formed on the surface of one impurity region. The capacitor has a planar type capacitor provided in the planar area of occupation of the stacked capacitor portion, whereby the capacitance of the capacitor can be increased without increasing the planar area of occupation.

Solid-state electrolytic capacitor and manufacture thereof

Abstract: PURPOSE: To make it possible to form an electrolytic polymerization film to the center of a capacitor element smoothly, by using a capacitor element in which a film of a conductive polymer such as polypyrrole or polyaniline is interposed between metal foils and is wound. CONSTITUTION: A film 6 of a conductive polymer such as polypyrrole, polyaniline, polythiophene or polyfuran is interposed between an anode foil 2 and a cathode foil 4 having a valve function such as aluminum, tantalum or niobium on which an oxide film is formed and is wound, and a capacitor element 1 is formed, and further the film 6 of the conductive polymer is previously installed in the proximity of the center of the capacitor element 1. Then, the film 6 of the conductive polymer is used for a supply of an electrolytic polymerization current, and an electrolytic polymerization film such as polypyrrole or polyaniline is smoothly formed to the center of the capacitor element 1, and a solid electrolytic capacitor with a good occurrence rate of electrostatic capacity can be implemented. COPYRIGHT: (C)1994,JPO&Japio

Manufacturing method of tantalum capacitor chip, tantalum capacitor chip manufactured by the method and tantalum capacitor containing the tantalum capacitor chip

Abstract: PURPOSE:To eliminate that the difference in the density of a tantalum sintered body is caused between the surface part and the inside by a method wherein the pressurization and molding operation of a tantalum-powder molded body is performed a plurality of times. CONSTITUTION:By using a pressurization and molding apparatus 14a and in a state that a lower punch 12a has been advanced into a hole in a die by a prescribed amount, a tantalum powder 15 in a prescribed quantity is put into the hole, an upper punch 13a which holds a tantalum wire 3 is moved downward and advanced into the hole 10a, the powder is pressurized and a first intermediate molded body 16a is formed. Then, by using a second pressurization and molding apparatus 14b in which a hole 10b in a die 11b is larger, the first intermediate molded body 16a is set on a lower punch 12b, a tantalum powder in a prescribed quantity is put into the hole 10b, the powder is pressurized and molded, a second intermediate molded body 16b' is formed. In addition, by using a third pressurization and molding apparatus 14c, a third molded layer 16c' is formed by the same technique as when a second pressurized and molded layer 16b is formed. Thereby, it is possible to improve the fragility of the title capacitor against a mechanical stress or a thermal stress.

Microwave Processing of Tantalum Capacitor Anodes

Abstract: Porous tantalum anodes were sintered at temperatures from 1600 to 1900{degrees}C using a conventional high-vacuum furnace as well as both 2.45 GHz fixed-frequency and 4--8 GHz variable-frequency microwave furnaces. Various insulation and casketing techniques were used to couple the microwave power to the tantalum compacts. Several types of tantalum powder were used to assess the effect of microwave processing on sintered surface area and impurity levels. Some microwave sintered anodes have an unusual surface rippling not seen on conventionally fired parts. The rippling suggests that a microscopic arcing or plasma might have been generated. Two important effects could be exploited if this phenomenon can be controlled. First, the effective tantalum surface area could be increased, yielding higher capacitance per volume. Second, surface impurities might be cleaned away, allowing the formation of a better dielectric film during the anodization process and, ultimately, higher working voltage.

Semiconductor memory with increased capacitive storage capabilities and reduced size

Abstract: A semiconductor memory includes a transistor and a capacitor which are formed on a semiconductor substrate, wherein the capacitor comprises in superposed layers a first capacitor composed of an impurity diffused layer formed in a surface layer of the semiconductor substrate, a first dielectric formed on the impurity diffused layer and a lower plate electrode formed on the first dielectric and serving as a field plate; a second capacitor composed of the lower plate electrode, a second dielectric formed on the lower plate electrode and a node electrode formed on the second dielectric; and a third capacitor composed of the node electrode, a third dielectric formed on the node electrode and an upper plate electrode formed on the third dielectric.

Chip type solid electrolytic tantalum capacitor

Abstract: PURPOSE:To manufacture the title compact chip type solid electrolytic tantalum capacitor in parallel-connection structure by using the tantalum elements in the structure wherein tantalum sintered bodies are connected to tantalum foils. CONSTITUTION:The esboss parts 22 are provided on tantalum foils 2 and then tantalum powder is pressure-molded and sintered in vacuum atmosphere into tantalum sintered parts 3 connecting to the welded tantalum foils 2. Next, the surfaces of the tantalum foils 2 into which the tantalum sintered bodies 3 are not yet welded are anode-oxidized and then manganese dioxide layers, graphite layers and silver paste layers are successively formed on the tantalum foils 2 to form tantalum elements. Through these procedures, exceeding two tantalum elements are parallel-connected and then covered with an insulating resin 7 as an exterior so as to manufacture the title tantalum capacitor.

Solid electrolytic capacitor

Abstract: PURPOSE:To enable formation of a solid electrolytic capacitor having the same shape as a conventional one and to considerably increase the electrostatic capacity thereof by forming AgTaO3 (silver paste layer) on the dielectric layer of solid electrolytic capacitor CONSTITUTION:Ta element 1 is formed by applying vacuum sintering to pressure molded tantalum powder at high temperature is anodically oxidated in phosphoric acid aqueous solution by formation voltage of 100V to prepare tantalum oxide film over the entire outer surface Next, the element 1 is dipped in silver acetate aqueous solution to stick silver acetate to the surface of element 1 and the element 1 is dried up in the atmosphere The element 1 is heated in a temperature range of 300-500 degC at a temperature up rate of 10 degC/H-50 degC/ to decompose silver acetate and to diffuse it into Ta2O5 film to take in oxygen from the atmosphere, thereby causing the reaction of Ag+Ta2O5+1/2 O2 AgTaO3 to form AgTaO3 Further, depending on the extent of diffusion of Ag into Ta2O5, the control of dielectric constant is made possible With this a solid electrolytic capacitor can be obtained m the same configuration as a 100muF tantalum capacitor that has a large capacitance and that has a capacitance of greater than 1mF

Solid tantalum electrolytic capacitor

Abstract: PURPOSE:To increase contact area with tantalum powder and to enhance anti- pulling strength by roughening the surface of positive lead wire, at least a part buried in a sintered body, through etching with substantially the same degree of roughness as the average grain size of tantalum powder. CONSTITUTION:A positive lead wire, i.e., a tantalum wire of 0.25mm diameter, is immersed in an etching liquid having volume ratio of HF:HNO3:H2O=2:3:5 for 10min thus roughening the surface with degree of roughness of 1.5 mum which is close to the grain size of tantalum powder. The tantalum wire is then molded and sintered at 1450 deg.C. The tantalum wire exhibited anti-pulling strength of 1.5-2.0kg. Tantalum powder having grain size in the range of 1.2-1.5mum is employed. Preferably, roughness on the surface of the tantalum wire is close to the average grain size of tantalum powder.

Chip type tantalum capacitor

Abstract: PURPOSE:To eliminate solder leach, miniaturize a device, and facilitate polarity discrimination, by forming a conductive paste layer composed of copper powder and thermosetting polymer on a sintered body on which manganese dioxide is formed, and forming a solder layer on said paste layer. CONSTITUTION:A tantalum sintered body 12 in which an anode tantalum line 11 is buried is used; an tantalum oxide coating film layer 13 and manganese dioxide layer 14 are formed on the sintered body 12; a conductive paste layer 15 composed of metal powder and thermosetting resin and a solder layer 6 are formed on the whole surface of the sintered body 12 except the top surface part 20 and the side surface peripheral part 19 continuous with the top surface part 20. At least the part except the solder layer 16 is coated with an insulating resin layer 22, and a tantalum solid-state electrolytic capacitor wherein an anode plane type lead 23 is connected with the anode tantalum line 11 is realized. Thereby the coating film of sheath resin of a chip type tantalum capacitor can be thinned, the device is miniaturized, and the reliability of soldering is increased. Since the anode is equipped with the leading-out plate 23, the polarity is never mistaken.

Aging method for tantalum capacitor

Abstract: PURPOSE:To obtain an aging treatment method without igniting a defective tantalum capacitor. CONSTITUTION:Solder bridge parts 5-1 and 6 are provided on an electrode lead 2-1, and the ignition on a tantalum capacitor is prevented by fusing a solder bridge parts 5-1 and 6 when an excessive current is allowed to flow to a defective capacitor. The title aging between a tie bar 3-1 and the electrode lead 2-1 a solder dipping process in which solder bridge parts 5-1 and 6 are formed on the above-mentioned cutting point and the like, a side-bar cutting process in which a side bar 4 is cut, an aging process in which high voltage E is added to each capacitor under heating, and a continuity testing process in which a continuity test is conducted between the tie bar 3-1 and the electrode lead 2-1 of each capacitor.

Chip type solid tantalum electrolytic capacitor

Abstract: PURPOSE:To achieve a relatively large surface area, thin tantalum sintered layer that is difficult to break or chip by compression molding a tantalum powder on one side of a tantalum sheet, sintering this, and then forming an oxide film, semiconductor layer, and conduction layer to create a tantalum capacitor element. CONSTITUTION:The embossed sections 4a are formed on the tantalum sheet 3a and a tantalum powder is compression molded on the protruding side of the embossed sections 4a. Next, vacuum sintering is performed and a tantalum sintered body 5a is obtained. After this, the recessed side of the embossed sections 4a on the tantalum sheet 3a is made the anode. In a hydrogen phosphate solution, the surfaces of the tantalum sintered body 5a and the protruding side of the embossed sections 4a of the tantalum sheet 3a are anodized and a cathode layer consisting of manganese dioxide, graphite, and silver paste is formed. Then the silver paste layer 7a is used to connect the cathode layer 6a and the cathode terminal 1a thereby obtaining a tantalum capacitor. Finally, two tantalum capacitor element are stacked and connected by a conductive resin layer 7b.

Experimental evidence of damaged zones in thin Ta2O5 anodic layers on polycrystalline tantalum foils

Abstract: The challenge recently demanded of electrolytic tantalum capacitors is to be able to operate above the frequency of 1 MHz which can be carried out insofar as their equivalent series resistance (ESR) is sufficiently small. Now, the mechanical quality of the oxide layers plays a determining part in the value of the ESR and the purpose of the present work is to detect in the oxide layer the areas most likely to be damaged but not yet cracked. It is shown that weaker zones exist in the oxide layer. These zones are revealed by chemical etching. The relative damaged area of one sample relative to another is correlated with the grain size ratio, by means of XPS, SEM and liquid capacitance measurements. It is established that the amorphous oxide is preferentially etched just above the grain boundaries of the tantalum substrate. These results lead to the conclusion that annealing at the greatest possible temperature has the best effect on the mechanical quality of the oxide layer.

Electrolytic Capacitors with a Conducting Polymer

Abstract: In this paper we describe the characteristics of a new type of aluminum electrolytic capacitor in which an electroconducting polymer is used as an electrolyte. A thick layer of polypyrrole is deposited on the alumina surface (dielectric) by chemical oxidative poly condensation in aqueous solution. By a precise controle of the deposit conditions of the polymer we demonstrate the possibility of a good coverage of the etched and anodized aluminum substrate. This is the condition required to obtain a high specific capacitance value. The final capacitor device has excellent impedance-frequency characteristics comparable to the ceramic capacitors. Film stability has been studied for polymers synthesized with different doping ions. It was found that increasing the molecular size of the counter-ion improves the stability of these aluminum electrolytic capacitors.

A fractal approach to electrolytic capacitors for implantable devices

Abstract: Electrolytic capacitors for implantable devices need an improvement in respect to size and contact reliability. In the following a new design of dry tantalum capacitors will b presented using thin films with a fractal surface structure. The achieved capacities related to the projected substrate area are presently in the same range as for commercially available SMT-components, but the height of the devices is reduced to 1/5. Furthermore the reliability in respect to the contact is highly improved by using standard thick film technolog.