Abstract: An apparatus and method for wafer level fabrication of high value inductors directly on top of semiconductor integrated circuits. The apparatus and method includes fabricating a semiconductor wafer including a plurality of dice, each of the dice including power circuitry and a switching node. Once the wafer is fabricated, then a plurality of inductors are fabricated directly onto the plurality of dice on the wafer respectively. Each inductor is fabricated by forming a plurality of magnetic core inductor members on an interconnect dielectric layer formed on the wafer. An insulating layer, and then inductor coils, are then formed over the plurality of magnetic core inductor members over each die. A plated magnetic layer is formed over the plurality of inductors respectively to raise the permeability and inductance of the structure.

Abstract: A method of forming an inductor. The method including: (a) forming a dielectric layer on a top surface of a substrate; after (a), (b) forming a lower trench in the dielectric layer; after (b), (c) forming a resist layer on a top surface of the dielectric layer; after (c), (d) forming an upper trench in the resist layer, the upper trench aligned to the lower trench, a bottom of the upper trench open to the lower trench; and after (d), (e) completely filling the lower trench and at least partially filling the upper trench with a conductor in order to form the inductor.

Abstract: A semiconductor device has a substrate with an inductor formed on its surface. First and second contact pads are formed on the substrate. A passivation layer is formed over the substrate and first and second contact pads. A protective layer is formed over the passivation layer. The protective layer is removed over the first contact pad, but not from the second contact pad. A conductive layer is formed over the first contact pad. The conductive layer is coiled on the surface of the substrate to produce inductive properties. The formation of the conductive layer involves use of a wet etchant. The second contact pad is protected from the wet etchant by the protective layer. The protective layer is removed from the second contact pad after forming the conductive layer over the first contact pad. An external connection is formed on the second contact pad.

Abstract: Disclosed is a semiconductor device comprising: a semiconductor substrate in which an integrated circuit is formed; a first resin film provided over the semiconductor substrate; a second resin film provided over an upper surface of the first resin film except at least a peripheral portion of the first resin film; and a thin film inductor provided over the second resin film.

Abstract: The present invention generally relates to a circuit structure and a method of manufacturing a circuit, and more specifically to an electrostatic discharge (ESD) circuit with a through wafer via structure and a method of manufacture. An ESD structure includes an ESD active device and at least one through wafer via structure providing a low series resistance path for the ESD active device to a substrate. An apparatus includes an input, at least one power rail and an ESD circuit electrically connected between the input and the at least one power rail, wherein the ESD circuit comprises at least one through wafer via structure providing a low series resistance path to a substrate. A method, includes forming an ESD active device on a substrate, forming a ground plane on a backside of the substrate and forming at least one through wafer via electrically connected to a negative power supply of the ESD active device and the ground plane to provide a low series resistance path to the substrate.

Abstract: Various semiconductor chip carrier substrate circuit tuning apparatus and methods are disclosed. In one aspect, a method of manufacturing is provided that includes assembling a semiconductor chip carrier substrate with a first input/output site adapted to electrically connect to an external component and a second input/output site adapted to electrically connect to an input/output site of a semiconductor chip. An inductor is placed in the semiconductor chip carrier substrate. The inductor is electrically connected between the first and second input/output sites. The inductor has a preselected inductance to reduce an impedance discontinuity between the first input/output site or the second input/output site due to coupling to a second conductor in the semiconductor chip carrier substrate.

Abstract: A semiconductor device sends and receives electrical signals. The semiconductor device includes a first substrate provided with a first circuit region containing a first circuit; a multi-level interconnect structure provided on the first substrate; a first inductor provided in the multi-level interconnect structure so as to include the first circuit region; and a second inductor provided in the multi-level interconnect structure so as to include the first circuit region, wherein one of the first inductor and the second inductor is connected to the first circuit and the other of the first inductor and the second inductor is connected to a second circuit.

Abstract: An integrated circuit includes a first integrated circuit die having a first circuit and a first inductive interface and a second integrated circuit die having a second circuit and a second inductive interface. A substrate is coupled to support the first integrated circuit die and the second integrated circuit die, the substrate including a magnetic communication path aligned with the first inductive interface and the second inductive interface, to magnetically communicate signals between the first circuit and the second circuit.

Abstract: Typically, chips nowadays comprise a number of circuits as well as a number of inductors, often RF-inductors. These IC inductors are essential to realize the voltage controlled oscillators needed in the many fully integrated transceiver chips, serving a multitude of wireless communication protocols, that are provided to the market today. The present invention relates to an RF-IC packaging method, which virtually eliminates the long-range electromagnetic crosstalk between inductors and transmission lines of different parts of the circuitry.

Abstract: A structure and a method for forming the same. The structure includes (a) a substrate which includes a top substrate surface which defines a reference direction perpendicular to the top substrate surface, (b) N semiconductor regions on the substrate, and (c) P semiconductor regions on the substrate, N and P being positive integers. The N semiconductor regions comprise dopants. The P semiconductor regions do not comprise dopants. The structure further includes M interconnect layers on top of the substrate, the N semiconductor regions, and the P semiconductor regions, M being a positive integer. The M interconnect layers include an inductor. (i) The N semiconductor regions do not overlap and (ii) the P semiconductor regions overlap the inductor in the reference direction. A plane perpendicular to the reference direction and intersecting a semiconductor region of the N semiconductor regions intersects a semiconductor region of the P semiconductor regions.

Abstract: A planar inductor comprises a metal element (11-14) on a substrate (300, 310), said metal element being provided with at least one groove (20) extending along and into said element from at least one surface (2) of said element. Said groove or grooves (20) extend into the element in a direction substantially perpendicular to the surface of the substrate (300, 310), giving rise to a higher Q value and a lower serial resistance are also achieved. The inductor may comprise grooved (11, 13, 14) and non-grooved (12) layers. The invention also relates to a method of manufacturing the inductor.

Abstract: Integrated circuit devices include a semiconductor substrate and a flux line generating passive electronic element on the semiconductor substrate. A dummy gate structure is arranged on the semiconductor substrate in a region below the passive electronic element. The dummy gate includes a plurality of segments, each segment including a first longitudinally extending part and a second longitudinally extending part. The second longitudinally extending part extends at an angle from an end of the first longitudinally extending part. Ones of the segments extend at a substantially same angle and are arranged displaced from each other in an adjacent nested relationship.

Abstract: A semiconductor device has a substrate with an inductor formed on its surface. First and second contact pads are formed on the substrate. A passivation layer is formed over the substrate and first and second contact pads. An insulating layer is formed over the passivation layer. The insulating layer is removed over the first contact pad, but not from the second contact pad. A metal layer is formed over the first contact pad. The metal layer is coiled on the surface of the substrate to produce inductive properties. The formation of the metal layer involves use of a wet etchant. The second contact pad is protected from the wet etchant by the insulating layer. The insulating layer is removed from the second contact pad after forming the metal layer over the first contact pad. An external connection is formed on the second contact pad.

Abstract: A spiral inductor, which is formed of a spiral wiring pattern, is formed in an inductor formation region which is assigned within an IC chip. A plurality of dummy wiring lines are formed according to a given design rule on an inside region surrounded by the spiral inductor within the inductor formation region and on an outside region of the spiral inductor within the inductor formation region. Each of the plurality of dummy wiring lines is formed to have such a shape that at least one side of a closed loop is opened, and the plurality of dummy wiring lines are disposed to have regularity and/or uniformity at a given distance from the spiral inductor.

Abstract: The bow in a wafer that results from fabricating a large number of MEMS devices on the top surface of the passivation layer of the wafer so that a MEMS device is formed over each die region is reduced by forming a stress relief layer between the passivation layer and the MEMS devices.

Abstract: A method for fabricating an inductor structure or a dual damascene structure includes following steps. First, a dielectric layer is provided. Subsequently, a first etching process is performed on the dielectric layer so as to form a first opening in the dielectric layer. A polymer is also formed in the first opening during the first etching process. Next, a polymer-removing step is performed to remove the polymer. Thereafter, a second etching process is performed on the dielectric layer to form a second opening in the dielectric layer. Furthermore, the first opening and the second opening are filled with a conductive material so as to form an inductor structure or a dual damascene structure.

Abstract: A method for manufacturing an inductor according to the embodiment comprises the steps of: forming a first photoresist pattern; forming an impurity region forming the inductor by implanting an impurity ion to the substrate by means of the first photoresist pattern and a pad region applying current across the impurity region; forming a second photoresist pattern so that a position spaced by a predetermined interval from the impurity region is opened; and forming a guard impurity region in the position spaced from the impurity region by implanting the same impurity ion as the impurity ion by means of the second photoresist pattern.

Abstract: Systems and methods associated with semiconductor articles are disclosed, including forming a first layer of material on a substrate, etching trenches within regions defining a passive element in the first layer, forming metal regions on sidewalls of the trenches, and forming a region of dielectric or polymer material over or in the substrate. Moreover, an exemplary method may also include forming areas of metal regions on the sidewalls of the trenches such that planar strip portions of the areas form electrically conductive regions of the passive element(s) that are aligned substantially perpendicularly with respect to a primary plane of the substrate. Other exemplary embodiments may comprise various articles or methods including capacitive and/or inductive aspects, Titanium- and/or Tantalum-based resistive aspects, products, products by processes, packages and composites consistent with one or more aspects of the innovations set forth herein.

Abstract: A first wiring layer in a circuit substrate structure is provided with a first inductor and a second inductor. A dielectric layer is provided with a first via and a second via electrically connected to the first inductor and the second inductor, respectively. A second wiring layer is provided with: a bridge electrically connecting the first via and the second via; and a conductive pattern provided around the bridge, the outer edge of the conductive pattern being located outside the outer edge of the first wiring pattern and the second wiring pattern in the first wiring layer. The bridge functions as a coplanar line and suppresses generation of electromagnetic field.

Abstract: Disclosed are embodiments of a circuit (e.g., an electrostatic discharge (ESD) circuit), a design methodology and a design system. In the circuit, an ESD device is wired to a first metal level (e.g., M1). An inductor is formed in a second metal level (e.g., M5) above the first metal level and is aligned over and electrically connected in parallel to the ESD device by a single vertical via stack. The inductor is configured to nullify, for a given application frequency, the capacitance value of the ESD device. The quality factor of the inductor is optimized by providing, on a third metal level (e.g., M3) between the second metal level and the first metal level, a shield to minimize inductive coupling. An opening in the shield allows the via stack to pass through, trading off Q factor reduction for size-scaling and ESD robustness improvements.

Abstract: An inductor for a semiconductor device and a method for fabricating the same includes a wafer, a first metal pad formed on the wafer and having a surface exposed from the surface of the wafer, a second metal pad formed on the wafer and having a surface exposed from the surface of the wafer, a first inductor line formed in the wafer and extending from the first metal pad and having a plurality of branches with a surface exposed from the surface of the wafer, and a second inductor line formed in the wafer and extending from the second metal pad and having a plurality of branches with a surface exposed from the surface of the wafer. The plurality of branches of the first inductor line and the plurality of branches of the second inductor line are arranged in parallel in an alternating pattern.

Abstract: A semiconductor structure. The semiconductor structure includes: a substrate having a metal wiring level within the substrate; a capping layer on and above a top surface of the substrate; an insulative layer on and above a top surface of the capping layer; an inductor comprising a first portion in and above the insulative layer and a second portion only above the insulative layer; and a wire bond pad within the insulative layer, wherein the first portion the inductor has a height in a first direction greater than a height of the wire bond pad in the first direction, wherein the first direction is perpendicularly directed from the top surface of substrate toward the insulative layer.

Abstract: A semiconductor device includes: a semiconductor substrate; an interlayer insulating film formed on the semiconductor substrate; a first inductor interconnect layer having a spiral pattern, formed to be embedded in a top portion of the interlayer insulating film; a barrier insulating film formed to cover the interlayer insulating film and the first inductor interconnect layer, the barrier insulating film having at least one connecting groove running along the first inductor interconnect layer; and a second inductor interconnect layer formed on the barrier insulating film to run along the first inductor interconnect layer and fill the connecting groove to be electrically connected with the first inductor interconnect layer. The second inductor interconnect layer has at least one concave groove formed on the top to run along the length thereof.

Abstract: Disclosed is a semiconductor device which includes a substrate having an air layer or void therein, an interlayer dielectric film above the substrate, and a metal wiring having a spiral structure on the interlayer dielectric film corresponding to or over the air layer. The semiconductor device exhibits reduced parasitic capacitance between the metal wiring (used as an inductor) and the substrate, thereby improving a self-resonance frequency as well as an applicable frequency band of the inductor.

Abstract: A method of a semiconductor device. A substrate is provided. At least one metal wiring level is within the substrate. An insulative layer is deposited on a surface of the substrate. An inductor is formed within the insulative layer using a patterned plate process. A wire bond pad is formed within the insulative layer, wherein at least a portion of the wire bond pad is substantially co-planar with the inductor.

Abstract: A method of forming a semiconductor substrate. A substrate is provided. At least one metal wiring level is within the substrate. A first insulative layer is deposited on a surface of the substrate. A portion of a wire bond pad is formed within the first insulative layer. A second insulative layer is deposited on the first insulative layer. An inductor is within the second insulative layer using a patterned plate process. A remaining portion of the wire bond pad is formed within the second insulative layer, wherein at least a portion of the wire bond pad is substantially co-planar with the inductor.

Abstract: Provided is a semiconductor device capable of increasing the capacitance of a capacitor, while reducing an area occupied by the capacitor and inductor on a substrate. The semiconductor device includes a first line; an interlayer insulating film that is formed on the first line and has a recess formed at a location corresponding to the first line; and a second line formed in the recess of the interlayer insulating film. The first line, the second line, and an insulating film formed between the first line and the second line constitute a capacitor. At least one of the first line and the second line constitutes an inductor.

Abstract: A microelectronic assembly and a method for forming the same are provided. The method includes forming first and second lateral etch stop walls (44, 46) in a semiconductor substrate (20) having first and second opposing surfaces (22, 24). An inductor (56) is formed on the first surface (22) of the semiconductor substrate (20) and a hole (60) is formed through the second surface (24) of the substrate (20) to expose the substrate (20) between the first and second lateral etch stop walls (44, 46). The substrate (20) is isotropically etched between the first and second lateral etch stop walls (44, 46) through the etch hole (60) to create a cavity 62) within the semiconductor substrate (20). A sealing layer (70) is formed over the etch hole (60) to seal the cavity (62).

Abstract: An integrated receiver with channel selection and image rejection substantially implemented on a single CMOS integrated circuit is described. A receiver front end provides programmable attenuation and a programmable gain low noise amplifier. Frequency conversion circuitry advantageously uses LC filters integrated onto the substrate in conjunction with image reject mixers to provide sufficient image frequency rejection. Filter tuning and inductor Q compensation over temperature are performed on chip. The filters utilize multi track spiral inductors with shields to increase circuit Q. The filters are tuned using local oscillators to tune a substitute filter, and frequency scaling during filter component values to those of the filter being tuned. In conjunction with filtering, frequency planning provides additional image rejection. The advantageous choice of local oscillator signal generation methods on chip is by PLL out of band local oscillation and by direct synthesis for in band local oscillator.

Abstract: An embodiment is an inductor that may include a laminated material structure to decrease eddy currents therein that may limit the operation of the inductor at high frequency. An embodiment may employ electroless plating techniques to form a layer or layers of magnetic material within the laminated material structure, and in particular those magnetic layers adjacent to insulator layers.

Abstract: An integrated circuit chip comprising a bond wire and a mass of magnetic material provided on the bond wire, wherein the mass of magnetic material increases the inductance of the bond wire.

Abstract: A method of forming an integrated circuit is disclosed. The method includes providing a substrate and forming on the substrate a shield structure comprising a shield member and a ground strap. The shield member comprises a non-metallic portion, and the ground strap comprises a metallic portion.

Abstract: The plating method comprises the step of forming a resin layer 10 over a substrate 16; the step of cutting the surface part of the resin layer 10 with a cutting tool 12; the step of forming a seed layer 36 on the resin layer 10 by electroless plating; and the step of forming a plating film 44 on the seed layer 36 by electroplating. Suitable roughness can be give to the surface of the resin layer 10, whereby the adhesion between the seed layer 36 and the resin layer 10 can be sufficiently ensured. Excessively deep pores are not formed in the surface of the resin layer 10, as are by desmearing treatment, whereby a micronized pattern of a photoresist film 40 can be formed on the resin layer 10. Thus, interconnections 44, etc. can be formed over the resin layer 10 at a narrow pitch with high reliability ensured.

Abstract: An integrated circuit inductor has a number of vertical metal segments, a number of lower metal straps that electrically connect alternate metal segments, and a number of upper metal straps that electrically connect alternate metal segments to form a continuous electrical path. Layers of a ferromagnetic material are formed normal to the metal segments to extend past at least two sides of each metal segment to increase the inductance of the inductor.

Abstract: An inductor with plural coil layers includes a base wafer; a plurality of insulating layers sequentially laminated on one surface of the base wafer; and a plurality of coil layers built in the plurality of insulating layers, respectively, and having different magnetic flux passage areas.

Abstract: Methods for forming multiple inductors on a semiconductor wafer are described. A plating layer and a photoresist layer are applied over a semiconductor wafer. Recess regions are etched in the photoresist layer using photolithographic techniques, which exposes portions of the underlying plating layer. Metal is electroplated into the recess regions in the photoresist layer to form multiple magnetic core inductor members. A dielectric insulating layer is applied over the magnetic core inductor members. Additional plating and photoresist layers are applied over the dielectric insulating layer. Recess regions are formed in the newly applied photoresist layer. Electroplating is used to form inductor windings in the recess regions. Optionally, a magnetic paste can be applied over the inductor coils.

Abstract: An integrated current sensor package includes an integrated circuit having a coil in a metal layer of the circuit. A wire is placed close enough to the coil such that the coil and the wire are inductively coupled with each other.

Abstract: A method of forming an inductor. The method including: (a) forming a dielectric layer on a top surface of a substrate; after (a), (b) forming a lower trench in the dielectric layer; after (b), (c) forming a resist layer on a top surface of the dielectric layer; after (c), (d) forming an upper trench in the resist layer, the upper trench aligned to the lower trench, a bottom of the upper trench open to the lower trench; and after (d), (e) completely filling the lower trench and at least partially filling the upper trench with a conductor in order to form the inductor.

Abstract: A fabricating method of packaging structure is provided. First, a capacitive element is formed. Then, a first dielectric layer is formed on a first electronic component by performing a build-up process, an interconnection is formed in the first dielectric layer, and a plurality of contacts are formed on the upper and lower surfaces of the first dielectric layer, wherein the capacitive element is embedded in the first dielectric layer during the fabrication of the interconnection and the capacitive element is electrically connected to the corresponding contacts through the interconnection. A second electronic component is disposed on the first dielectric layer, wherein the second electronic component is electrically connected to the corresponding contacts.

Abstract: A method of manufacturing a coil inductor and a coil inductor are provided. A plurality of conductive bottom structures are formed to be lying on a first dielectric layer. A plurality pairs of conductive side structures are then formed, wherein each pair of the conductive side structure stand on top surface of a first end and a second end of each conductive bottom structure respectively; a second dielectric layer is formed on the first dielectric layer, coating the bottom and side structures; and a plurality of conductive top structures are formed to be lying on the second dielectric layer, wherein each conductive top structure electrically connects each pair of the conductive side structures, wherein the conductive bottom structures, the conductive side structures and the conductive top structures together form a conductive coil structure.

Abstract: Various methods of forming a passive element such as an inductor raised off the surface of the substrate to improve the performance of the passive element are presented. A first wafer may be provided, and passive elements diced from a second wafer. The passive elements are flipped, and then aligned to be bonded on the first wafer such that the passive elements are raised a distance off the first wafer because of the presence of chip connections such as C4 solder bumps. A gap between the passive elements and the first wafer can be filled with underfill or air. If air is used, a hermetic seal around the gap can be created using chip connections such as C4 solder bumps or other known bonding means to seal the gap.

Abstract: A semiconductor package includes a base substrate on which a semiconductor chip is placed so that a first surface thereof faces the base substrate. A circuit section is formed adjacent to the first surface. An insulation layer is formed on a second surface of the semiconductor chip which faces away from the first surface. Passive elements are formed on the insulation layer. Via patterns are formed to pass through the insulation layer and are connected to the passive elements. Via wirings are formed to pass through the semiconductor chip and connected to the circuit section, the via patterns and the base substrate. Outside connection terminals are attached to a first surface of the base substrate, which face away from a second surface of the base substrate on which the semiconductor chip is placed.

Abstract: An apparatus and method for wafer level fabrication of high value inductors directly on top of semiconductor integrated circuits. The apparatus and method includes fabricating a semiconductor wafer including a plurality of dice, each of the dice including power circuitry. Once the wafer is fabricated, then a plurality of inductors are fabricated directly onto the plurality of dice on the wafer and are in electrical contact with a switching node of the power circuitry on each die respectively. The inductors are fabricated by forming a plurality of magnetic core inductor members on an interconnect dielectric layer for each die on the wafer. An insulating layer and then inductor coils are then formed over the plurality of magnetic core inductor members over each die. A layer of magnetic paste is also optionally provided over each inductor coil to further increase inductance.

Abstract: A semiconductor device has an inductor and capacitor formed on the substrate. The inductor and capacitor are electrically connected in series. The inductor is a coiled conductive layer. The capacitor has first and second conductive layers separated by an insulating layer. A first test pad and second test pad are formed on the substrate. A terminal of the inductor is coupled to the first and second test pads. A third test pad and fourth test pad are formed on the substrate. A terminal of the capacitor is coupled to the third and fourth test pads such that the inductor and capacitor are connected in shunt between the first and second test pads and the third and fourth test pads. An electrical characteristic of the inductor and capacitor such that resonant frequency and quality factor are tested using a two-port shunt measurement which negates series resistance of test probes.

Abstract: Semiconductor devices are provided with high performance high-frequency circuits in which interference caused by inductors is reduced. In a semiconductor device including a modulator circuit to modulate a carrier wave by a base band signal to output an RF signal and a demodulator circuit to demodulate the RF signal by use of the carrier wave to gain the base band signal and a local oscillator to generate the carrier wave, inductors respectively having a closed loop wire are adopted. Interference caused by mutual inductance is reduced by the closed loop wire. For example, where inductors are adopted in the modulator circuit, a closed loop wire is disposed around the outer periphery of the inductors.

Abstract: Methods for fabricating a back-end-of-line (BEOL) wiring structure that includes an on-chip inductor and an on-chip capacitor, as well as methods for tuning and fabricating a resonator that includes the on-chip inductor and on-chip capacitor. The fabrication methods generally include forming the on-chip capacitor and on-chip inductor in different metallization levels of the BEOL wiring structure and laterally positioned to be substantially vertical alignment. The on-chip capacitor may serve as a Faraday shield for the on-chip inductor. Optionally, a Faraday shield may be fabricated either between the on-chip capacitor and the on-chip inductor, or between the on-chip capacitor and the substrate. The BEOL wiring structure may include at least one floating electrode capable of being selectively coupled with the directly-connected electrodes of the on-chip capacitor for tuning, during circuit operation, a resonance frequency of an LC resonator that further includes the on-chip inductor.

Abstract: A method of forming an inductor. The method includes: forming a dielectric layer on a substrate; forming a lower trench in the dielectric layer; forming a liner in the lower trench and on the dielectric layer; forming a Cu seed layer over the liner; forming a resist layer on the Cu seed layer; forming an upper trench in the resist layer; electroplating Cu to completely fill the lower trench and at least partially fill the upper trench; removing the resist layer; selectively forming a passivation layer on all exposed Cu surfaces; selectively removing the Cu seed layer from regions of the liner; and removing the thus exposed regions of the liner from the dielectric layer, wherein a top surface of the inductor extends above a top surface of the dielectric layer, the passivation layer remaining on regions of sidewalls of the inductor above the top surface of the dielectric layer.

Abstract: A method for forming a through-silicon via bandpass filter includes forming a substrate comprising a silicon layer and providing a metal layer on a bottom side of the silicon layer. Additionally, the method includes providing a dielectric layer on a top side of the silicon layer and forming a top-side interconnect of the through-silicon via bandpass filter on a surface of the dielectric layer. Further, the method includes forming a plurality of contacts in the dielectric layer in contact with the top-side interconnect and forming a plurality through-silicon vias through the substrate and in contact with the plurality of contacts, respectively, and the metal layer.

Abstract: An inductor having a helicoidal shape is provided on an insulation film formed on a semiconductor substrate. A conductive thin layer (a plating layer) is provided on a surface of the inductor. A conductivity of the conductive thin layer is higher than that of the inductor. According to the constitution, a Q value can be improved, and a large volume of current can be flowed.

Abstract: A design structure is embodied in a machine readable medium for designing, manufacturing, or testing a design. The design structure includes a high resistivity substrate and a buried inductor formed directly in the high resistivity substrate and devoid of an insulating layer therebetween.