Abstract: An integrated circuit device with a semiconductor body and a method for the production of a semiconductor device a provided. The semiconductor body comprises a cell field with a drift zone of a first conduction type. In addition, the semiconductor device comprises an edge region surrounding the cell field. Field plates with a trench gate structure are arranged in the cell field, and an edge trench surrounding the cell field is provided in the edge region. The front side of the semiconductor body is in the edge region provided with an edge zone of a conduction type complementing the first conduction type with doping materials of body zones of the cell field. The edge zone of the complementary conduction type extends both within and outside the edge trench.

Abstract: A method of fabricating an integrated circuit (IC) including a plurality of MOS transistors and ICs therefrom include providing a substrate having a silicon including surface, and forming a plurality of dielectric filled trench isolation regions in the substrate, wherein the silicon including surface forms trench isolation active area edges along its periphery with the trench isolation regions. A first silicon including layer is deposited, wherein the first silicon including extends from a surface of the trench isolation regions over the trench isolation active area edges to the silicon including surface. The first silicon including layer is completely oxidized to convert the first silicon layer to a silicon oxide layer, wherein the silicon oxide layer provides at least a portion of a gate dielectric for at least one of the plurality of MOS transistors.

Abstract: A transistor suitable for high-voltage applications is provided. The transistor is formed on a substrate having a deep well of a first conductivity type. A first well of the first conductivity type and a second well of a second conductivity type are formed such that they are not immediately adjacent each other. The well of the first conductivity type and the second conductivity type may be formed simultaneously as respective wells for low-voltage devices. In this manner, the high-voltage devices may be formed on the same wafer as low-voltage devices with fewer process steps, thereby reducing costs and process time. A doped isolation well may be formed adjacent the first well on an opposing side from the second well to provide further device isolation.

Abstract: Three-dimensional transistor structures such as FinFETS and tri-gate transistors may be formed on the basis of an enhanced masking regime, thereby enabling the formation of drain and source areas, the fins and isolation structures in a self-aligned manner within a bulk semiconductor material. After defining the basic fin structures, highly efficient manufacturing techniques of planar transistor configurations may be used, thereby even further enhancing overall performance of the three-dimensional transistor configurations.

Abstract: A 3-D (Three Dimensional) inverter having a single gate electrode. The single gate electrode has a first gate dielectric between the gate electrode and a body of a first FET (Field Effect transistor) of a first doping type, the first FET having first source/drain regions in a semiconductor substrate, or in a well in the semiconductor substrate. The single gate electrode has a second gate dielectric between the gate electrode and a body of a second FET of opposite doping to the first FET. Second source/drain regions of the second FET are formed from epitaxial layers grown over the first source/drain regions.

Abstract: A method of forming a semiconductor device is provided that includes forming a gate structure atop a substrate and implanting dopants into the substrate to a depth of 10 nm or less from an upper surface of the substrate. In a following step, an anneal is performed with a peak temperature ranging from 1200° C. to 1400° C., and a hold time period ranging from 1 millisecond to 5 milliseconds.

Abstract: A device for protecting a semiconductor device from electrostatic discharge may include a high voltage first conductivity type well formed in a semiconductor substrate. A first stack region may have a first conductivity type drift region, and a first conductivity type impurity region stacked in succession in the high voltage first conductivity type well. A second stack region may have a second conductivity type drift region, and a second conductivity type impurity region stacked in succession in the high voltage first conductivity type well. A device isolating film formed between the first stack region and the second stack region for isolating the first stack region from the second stack region.

Abstract: A disposable structure displaced from an edge of a gate electrode and a drain region aligned to the disposable structure is formed. Thus, the drain region is self-aligned to the edge of the gate electrode. The disposable structure may be a disposable spacer, or alternately, the disposable structure may be formed simultaneously with, and comprise the same material as, a gate electrode. After formation of the drain regions, the disposable structure is removed. The self-alignment of the drain region to the edge of the gate electrode provides a substantially constant drift distance that is independent of any overlay variation of lithographic processes.

Abstract: A method of manufacturing a semiconductor device includes providing a semiconductor wafer and forming at least one first trench in the wafer having first and second sidewalls and a first orientation on the wafer. The first sidewall of the at least one first trench is implanted with a dopant of a first conductivity at a first implantation direction. The first sidewall of the at least one first trench is implanted with the dopant of the first conductivity at a second implantation direction. The second implantation direction is orthogonal to the first implantation direction. The first and second implantation directions are non-orthogonal to the first sidewall.

Abstract: A structure of a capacitor set is described, including at least two capacitors that are disposed at the same position on a substrate and include a first capacitor and a second capacitor. The first capacitor includes multiple first capacitor units electrically connected with each other in parallel. The second capacitor includes multiple second capacitor units electrically connected with each other in parallel. The first and the second capacitor units are arranged spatially intermixing with each other to form an array.

Abstract: A buried decoupling capacitor apparatus and method are provided. According to various embodiments, a buried decoupling capacitor apparatus includes a semiconductor-on-insulator substrate having a buried insulator region and top semiconductor region on the buried insulator region. The apparatus embodiment also includes a first capacitor plate having a doped region in the top semiconductor region in the semiconductor-on-insulator substrate. The apparatus embodiment further includes a dielectric material on the first capacitor plate, and a second capacitor plate on the dielectric material. According to various embodiments, the first capacitor plate, the dielectric material and the second capacitor plate form a decoupling capacitor for use in an integrated circuit.

Abstract: Methods of fabricating semiconductor structures and devices include bonding a seed structure to a substrate using a glass. The seed structure may comprise a crystal of semiconductor material. Thermal treatment of the seed structure bonded to the substrate using the glass may be utilized to control a strain state within the seed structure. The seed structure may be placed in a state of compressive strain at room temperature. The seed structure bonded to the substrate using the glass may be used for growth of semiconductor material, or, in additional methods, a seed structure may be bonded to a first substrate using a glass, thermally treated to control a strain state within the seed structure and a second substrate may be bonded to an opposite side of the seed structure using a non-glassy material.

Abstract: A method of manufacturing a semiconductor device includes removing a part of a semiconductor substrate to form a protruding portion and a recess portion in a surface area of the semiconductor substrate, forming a first epitaxial semiconductor layer in the recess portion, forming a second epitaxial semiconductor layer on the protruding portion and the first epitaxial semiconductor layer, removing a first part of the second epitaxial semiconductor layer with a second part of the second epitaxial semiconductor layer left to expose a part of the first epitaxial semiconductor layer, and etching the first epitaxial semiconductor layer from the exposed part of the first epitaxial semiconductor layer to form a cavity under the second part of the second epitaxial semiconductor layer.

Abstract: A method and manufacture for fabrication of flash memory is provided. In fabricating the periphery region of the flash memory, the low voltage gate oxides and high voltage gate oxides are grown to the same height as each other prior to STI etching. After STI etching and gap fill, the nitride above the high voltage gate oxide regions are etched, and the oxide in high voltage gate oxide regions is grown to the appropriate thickness for a high voltage gate oxide.

Abstract: A method of manufacturing a semiconductor wafer, the method comprising providing a base wafer comprising a semiconductor substrate; preparing a first monocrystalline layer comprising semiconductor regions; performing a first layer transfer of the first monocrystalline layer on top of the semiconductor substrate; preparing a second monocrystalline layer comprising semiconductor regions; performing a second layer transfer of the second monocrystalline layer on top of the first monocrystalline layer; and etching portions of the first monocrystalline layer and portions of the second monocrystalline layer.

Abstract: Methods directed to avoiding die cracking resulting from die separation are described herein. A method may include providing a substrate including a first die, a second die, and a monitor structure in an area between the first die and the second die, the monitor structure including a first dielectric material, removing the first dielectric material from the monitor structure, and after removing the first dielectric material, cutting the substrate along the area between the first die and the second die to separate the first die from the second die.

Abstract: With the invented dicing method, by increasing the cohesive strength while decreasing the adhesive strength of an ultraviolet-curing adhesive in advance, mixing of the ultraviolet-curing adhesive layer of an adhesive sheet with a die attach film on a dicing line can be decreased and pickup failures can be reduced, when picking up chips having a die attach film after dicing. The dicing method for a semiconductor wafer with a die-attach film comprises a first gluing step in which a die attach film is affixed to an adhesive sheet having an ultraviolet-curing adhesive laminated on a base material film, a second gluing step in which a semiconductor wafer is affixed to the opposite side of the die attach film affixed to the adhesive sheet, an ultraviolet irradiation step in which the ultraviolet-curing adhesive is irradiated with ultraviolet light, and a dicing step in which the semiconductor wafer and the die attach film affixed to the adhesive sheet are diced.

Abstract: A technique for manufacturing a microcrystalline semiconductor layer with high mass productivity is provided. In a reaction chamber of a plasma CVD apparatus, an upper electrode and a lower electrode are provided in almost parallel to each other. A hollow portion is formed in the upper electrode, and the upper electrode includes a shower plate having a plurality of holes formed on a surface of the upper electrode which faces the lower electrode. A substrate is provided over the lower electrode. A gas containing a deposition gas and hydrogen is supplied to the reaction chamber from the shower plate through the hollow portion of the upper electrode, and a rare gas is supplied to the reaction chamber from a portion different from the upper electrode. Accordingly, high-frequency power is supplied to the upper electrode to generate plasma, so that a microcrystalline semiconductor layer is formed over the substrate.

Abstract: Methods for doping a non-planar structure by forming a conformal doped silicon glass layer on the non-planar structure are disclosed. A substrate having the non-planar structure formed thereon is positioned in chemical vapor deposition process chamber to deposit a conformal SACVD layer of doped glass (e.g. BSG or PSG). The substrate is then exposed to RTP or laser anneal step to diffuse the dopant into the non-planar structure and the doped glass layer is then removed by etching.

Abstract: A method for manufacturing trench MOSFET device with low gate charge includes the steps of providing a substrate of first conductivity type; forming an epitaxial layer of first conductivity type on the substrate; forming a body region of second conductivity type in the epitaxial layer, the body region extends downwards from the surface of the epitaxial layer; forming a plurality of trenches in the epitaxial layer, the body region having the trenches formed therethrough; forming a first insulating layer on the body region and on an inner surface of each trench; forming a ploy-silicon spacer on the first insulating layer on an inner side-wall of each trench; filling a dielectric structure in the lower portion of each trench; and filling a ploy-silicon structure on top of the dielectric structure in each trench. Through the trench MOSFET device, the gate capacitance and resistance thereof are reduced so the performance is increased.

Abstract: Electronic apparatus and methods of forming the electronic apparatus may include a tantalum aluminum oxynitride film for use in a variety of electronic systems and devices. The tantalum aluminum oxynitride film may be structured as one or more monolayers. The tantalum aluminum oxynitride film may be formed using atomic layer deposition. Metal electrodes may be disposed on a dielectric containing a tantalum aluminum oxynitride film.

Abstract: A semiconductor device fabrication method includes the steps of (a) forming a dielectric film on a semiconductor substrate; (b) etching the dielectric film by a dry process; and (c) supplying thermally decomposed atomic hydrogen onto the semiconductor substrate under a prescribed temperature condition, to remove a damaged layer produced in the semiconductor substrate due to the dry process.

Abstract: The embodiments generally relate to methods of making semiconductor devices, and more particularly, to methods for making semiconductor pillar structures and increasing array feature pattern density using selective or directional gap fill. The technique has application to a variety of materials and can be applied to making monolithic two or three-dimensional memory arrays.

Abstract: Method of manufacturing a semiconductor device, which achieves a reduction in manufacturing cost and prevents, a damage on the interconnect layer by an influence of the etchant solution, since the support substrate can be easily stripped from the interconnect layer. The method of manufacturing a semiconductor device includes: forming an interconnect film, by forming a seed metal layer on a support substrate and a protective film contacting with an end of an interface between the support substrate and the seed metal layer, and by growing a plated material from a surface of the seed metal layer; mounting a semiconductor chip on the interconnect film; removing at least a portion of the protective film to form a region where the support substrate and the seed metal layer are exposed; and stripping the support substrate from the region as a starting point to remove thereof from the seed metal layer.

Abstract: A design structure is embodied in a machine readable medium for designing, manufacturing, or testing a design. The design structure includes a dielectric material formed between a design sensitive structure and a passivation layer. The design sensitive structure comprising a lower wiring layer electrically and mechanically connected to a higher wiring level by a via farm. A method and structure is also provided.

Abstract: A liner-to-liner direct contact is formed between an upper metallic liner of a conductive via and a lower metallic liner of a metal line below. The liner-to-liner contact impedes abrupt electromigration failures and enhances electromigration resistance of the metal interconnect structure. The at least one dielectric material portion may include a plurality of dielectric material portions arranged to insure direct contact of between the upper metallic liner and the lower metallic liner. Alternatively, the at least one dielectric material portion may comprise a single dielectric portion of which the area has a sufficient lateral overlap with the area of the conductive via to insure that a liner-to-liner direct contact is formed within the range of allowed lithographic overlay variations.

Abstract: A method for semiconductor fabrication using a trench first metal hard mask (TFMHM) process for damascene structures includes forming a secondary metal hard mask layer above a first metal hard mask layer after trench opening for the via (and trench) etching. The secondary metal hard mask layer is formed of metal material substantially resistant to the etching process which enables via etching to self-align (using an edge of the secondary metal mask layer). In one embodiment, the secondary metal mask layer is formed using an electroless deposition process, and may include nickel (Ni), cobalt (Co), gold, (Au), palladium (Pd), cadmium (Cd) silver (Ag), ruthenium (Ru), and alloys and/or combinations thereof. Because the first metal hard mask is usually formed of TiN, the trench and via etching process removes a significant amount of the TiN layer. Utilization of the secondary metal hard mask to protect the first metal hard mask layer further enables a reduction in the thickness of the first metal hard mask layer.

Abstract: A method for producing on-chip interconnect structures on a substrate is provided, comprising at least the steps of providing a substrate and depositing a ruthenium-comprising layer on top of said substrate, and then performing a pre-treatment of the Ru-comprising layer electrochemically with an HBF4-based electrolyte, and then performing electrochemical deposition of copper onto the pre-treated Ru-comprising layer.

Abstract: A semiconductor wafer scale package system is provided including providing a semiconductor substrate having a through-hole via with a conductive coating, forming a filled via by filling the through-hole via with a conductive material, coupling a package substrate to the filled via, and singulating a chip scale package from the semiconductor substrate and the package substrate.

Abstract: A method of manufacturing semiconductor device includes preparing a substrate having a first surface and a second surface opposite to the first surface. A first insulation layer is formed on the second surface. A sacrificial layer is formed on the first insulation layer. An opening is formed to penetrate through the substrate and extend from the first surface to a portion of the sacrificial layer. A second insulation layer is formed on an inner wall of the opening. A plug is formed to fill the opening. The sacrificial layer is removed to expose a lower portion of the plug through the second surface.

Abstract: A cleaning solution is provided. The cleaning solution includes (a) 0.01-0.1 wt % of hydrofluoric acid (HF); (b) 1-5 wt % of a strong acid, wherein the strong acid is an inorganic acid; (c) 0.05-0.5 wt % of ammonium fluoride (NH4F); (d) a chelating agent containing a carboxylic group; (e) triethanolamine (TEA); (f) ethylenediaminetetraacetic acid (EDTA); and (g) water for balance.

Abstract: The invention relates to a method of manufacturing a semiconductor device with a substrate and a semiconductor body, whereby in the semiconductor body a semiconductor element is formed by means of a mesa-shaped protrusion of the semiconductor body, which is formed on the surface of the semiconductor device as a nano wire, whereupon a layer of a material is deposited over the semiconductor body and the resulting structure is subsequently planarized in a chemical-mechanical polishing process such that an upper side of the nano wire becomes exposed. According to the invention, a further layer of a further material is deposited over the semiconductor body with the nano wire before the layer of the material is deposited, which further layer is given a thickness smaller than the height of the nano wire, and a material is chosen for the further material such that, viewed in projection, the transition between the layer and the further layer is discernible before the nano wire is reached.

Abstract: A chemical mechanical polishing composition contains 1) water, 2) optionally an abrasive material, 3) an oxidizer, preferably a per-type oxidizer, 4) a small amount of soluble metal-ion oxidizer/polishing accelerator, a metal-ion polishing accelerator bound to particles such as to abrasive particles, or both; and 5) at least one of the group selected from a) a small amount of a chelator, b) a small amount of a dihydroxy enolic compound, and c) a small amount of an organic accelerator. Ascorbic acid in an amount less than 800 ppm, preferably between about 100 ppm and 500 ppm, is the preferred dihydroxy enolic compound. The polishing compositions and processes are useful for substantially all metals and metallic compounds found in integrated circuits, but is particularly useful for tungsten.

Abstract: In a method of manufacturing a semiconductor device for planarizing a silicon oxide film with chemical mechanical polishing using a silicon film formed on a semiconductor substrate as a stopper film, a surface modification film for hydrophilizing the surface of the silicon film is formed on an upper layer of the polysilicon film, and slurry for the chemical mechanical polishing contains cerium oxide particles, a surface active agent, and resin particles having a cationic or anionic functional group.

Abstract: A method for forming a nanotube/nanofiber growth catalyst on the sides of portions of a layer of a first material, comprising the steps of depositing a thin layer of a second material; opening this layer at given locations; depositing a very thin catalyst layer; depositing a layer of the first material over a thickness greater than that of the layer of the second material; eliminating by chem./mech. polishing the upper portion of the structure up to the high level of the layer of the second material; and eliminating the second material facing selected sides of the layer portions of the first material.

Abstract: A method of forming minute patterns in a semiconductor device, and more particularly, a method of forming minute patterns in a semiconductor device having an even number of insert patterns between basic patterns by double patterning including insert patterns between a first basic pattern and a second basic pattern which are transversely separated from each other on a semiconductor substrate, wherein a first insert pattern and a second insert pattern are alternately repeated to form the insert patterns, the method includes the operation of performing a partial etching toward the second insert pattern adjacent to the second basic pattern, or the operation of forming a shielding layer pattern, thereby forming the even number of insert patterns.

Abstract: An apparatus includes a semiconductor layer (2) having therein a cavity (4). A dielectric layer (3) is formed on the semiconductor layer. A plurality of etchant openings (24) extend through the dielectric layer for passage of etchant for etching the cavity. An SiO2 pillar (25) extends from a bottom of the cavity to engage and support a portion of the dielectric layer extending over the cavity. In one embodiment, a cap layer (34) on the dielectric layer covers the etchant openings.

Abstract: A method of removing carbon doped silicon oxide between metal contacts is provided. A layer of the carbon doped silicon oxide is converted to a layer of silicon oxide by removing the carbon dopant. The converted layer of silicon oxide is selectively wet etched with respect to the carbon doped silicon oxide and the metal contacts, which forms recess between the metal contacts.

Abstract: A substrate processing method capable of selectively removing a nitride film. Oxygen plasma containing plasmarized oxygen gas is made to be in contact with a silicon nitride film, which is made of SiN, of a wafer to thereby cause the silicon nitride film to be changed to a silicon monoxide film. The silicon monoxide film is selectively etched by hydrofluoric acid generated from HF gas supplied toward the silicon monoxide film.

Abstract: A method of etching or removing an amorphous carbon organic hardmask overlying a low dielectric constant film in a lithographic process. The method includes providing a dielectric film having thereover an amorphous carbon organic hardmask to be removed, the dielectric film having a dielectric constant no greater than about 4.0, introducing over the amorphous carbon organic hardmask an ionizable gas comprising a mixture of hydrogen and an oxidizing gas, and applying energy to the mixture to create a plasma of the mixture. The method further includes contacting the amorphous carbon organic hardmask with the plasma, with the amorphous carbon organic hardmask being at a temperature in excess of 200° C., to remove the amorphous carbon organic hardmask without substantially harming the underlying substrate.

Abstract: A silicon carbide semiconductor element and a manufacturing method thereof are disclosed in which a low contact resistance is attained between an electrode film and a wiring conductor element, and the wiring conductor element is hardly detached from the electrode film. In the method, a nickel film and a nickel oxide film are laminated in this order on a surface of an n-type silicon carbide substrate or an n-type silicon carbide region of a silicon carbide substrate, followed by a heat treatment under a non-oxidizing condition. The heat treatment transforms a portion of the nickel film into a nickel silicide film. Then, the nickel oxide film is removed with hydrochloric acid solution, and subsequently, a nickel aluminum film and an aluminum film are laminated in this order on a surface of the nickel silicide film.

Abstract: Integrated circuits (ICs) commonly contain pre-metal dielectric (PMD) liners with compressive stress to increase electron and hole mobilities in MOS transistors. The increase is limited by the thickness of the PMD liner. The instant invention is a multi-layered PMD liner in an integrated circuit which has a higher stress than single layer PMD liners. Each layer in the inventive PMD liner is exposed to a nitrogen-containing plasma, and which has a compressive stress higher than 1300 MPa. The PMD liner of the instant invention is composed of 3 to 10 layers. The hydrogen content of the first layer may be increased to improve transistor properties such as flicker noise and Negative Bias Temperature Instability (NBTI). An IC containing the inventive PMD liner and a method for forming same are also claimed.

Abstract: Electrical structures and devices may be formed and include an organic passivating layer that is chemically bonded to a silicon-containing semiconductor material to improve the electrical properties of electrical devices. In different embodiments, the organic passivating layer may remain within finished devices to reduce dangling bonds, improve carrier lifetimes, decrease surface recombination velocities, increase electronic efficiencies, or the like. In other embodiments, the organic passivating layer may be used as a protective sacrificial layer and reduce contact resistance or reduce resistance of doped regions. The organic passivation layer may be formed without the need for high-temperature processing.

Abstract: Disclosed is a heat treatment unit 4 serving as a heat treatment apparatus, which includes a chamber 42 for containing a wafer W on which a low dielectric constant interlayer insulating film is formed, a formic acid supply device 44 for supplying gaseous formic acid into the chamber 42, and a heater 43 for heating the wafer W in the chamber 42 which is supplied with formic acid by the formic acid supply device 44.

Abstract: Implementations of encapsulated nanowires are disclosed.

Abstract: A method for manufacturing a semiconductor device. The method includes forming an energy cured resin layer on a semiconductor substrate having an electrode pad and a passivation film; fusing the resin layer so that fusion of a surface section is progressed more than of a central section by a first energy supply processing; forming a resin boss by curing and shrinking the resin layer by a second energy supply processing; and forming an electrical conducting layer which is electrically connected to the electrode pad and passes over the resin boss.

Abstract: A method of forming a material on a substrate is disclosed. In one embodiment, the method includes forming a tantalum nitride layer on a substrate disposed in a plasma process chamber by sequentially exposing the substrate to a tantalum precursor and a nitrogen precursor, followed by reducing a nitrogen concentration of the tantalum nitride layer by exposing the substrate to a plasma annealing process. A metal-containing layer is subsequently deposited on the tantalum nitride layer.

Abstract: A plasma processing apparatus includes a process chamber configured to be vacuum-exhausted; a worktable configured to place a target substrate thereon inside the process chamber; a microwave generation source configured to generate microwaves; a planar antenna including a plurality of slots and configured to supply microwaves generated by the microwave generation source through the slots into the process chamber; a gas supply mechanism configured to supply a film formation source gas into the process chamber; and an RF power supply configured to apply an RF power to the worktable. The apparatus is preset to turn a nitrogen-containing gas and a silicon-containing gas supplied in the process chamber into plasma by the microwaves, and to deposit a silicon nitride film on a surface of the target substrate by use of the plasma, while applying the RF power to the worktable.

Abstract: The present invention relates generally to a static dissipative textile having an electrically conductive surface achieved by coating the textile with an electrically conductive coating in a variety of patterns. The electrically conductive coating is comprised of a conducting agent and a binding agent, and optionally a dispersing agent and/or a thickening agent. The static dissipative textile generally comprises a fabric which may be screen printed or otherwise coated with a conductive coating on the backside of the fabric so that the conductive coating does not interfere with the appearance of the face of the fabric. The economically produced fabric exhibits relatively permanent static dissipation properties and conducts electric charge at virtually any humidity, while the conductive coating does not detrimentally affect the overall appearance or tactile properties of the fabric.

Abstract: The present invention relates to a three-dimensional woven hollow layer-connecting fabric, comprising an upper layer-surface (10) formed by crossing upper ground warp yarns (1), (2) and a weft yarn (3) and a lower layer-surface (11) formed by crossing lower ground warp yarns (4), (5) and a weft yarn (6); the weft yarns (3) and (6) on the upper and lower layer-surfaces are also crossed with poil warps (7), (8) besides ground warp yarns (1), (2) and (4), (5) on their own layer-surface; the spatial walking direction of poil warps (7), (8) woven from one layer-surface to another is opposite to the weft-inserting direction of the fabric. The framework feature of the composite layer-connecting fabric of the present invention is distinct, and the vertical support function of poil warps between two layer-surfaces is good. The spatial structure of the layer-connecting fabric is varied in conformation, easy to design and adapted to produce on a large scale.