Abstract: In a high withstand voltage transistor of a LOCOS offset drain type having a buried layer, a plurality of stripe-shaped diffusion layers are formed below a diffusion layer ranging from an offset layer to a drain layer and a portion between the drain region and the buried layer is depleted completely; thus, a withstand voltage between the drain region and the buried layer is improved. By the formation of the stripe-shaped diffusion layers, the drain region becomes widened; thus, on-resistance is reduced. Further, the buried layer is made high in concentration so as to sufficiently suppress an operation of a parasitic bipolar transistor.

Abstract: According to one embodiment, a semiconductor device having an overlapping multi-well implant comprises an isolation structure formed in a semiconductor body, a first well implant formed in the semiconductor body surrounding the isolation structure, and a second well implant overlapping at least a portion of the first well implant. The disclosed semiconductor device, which may be an NMOS or PMOS device, can further comprise a gate formed over the semiconductor body adjacent to the isolation structure, wherein the first well implant extends a first lateral distance under the gate and the second well implant extends a second lateral distance under the gate, and wherein the first and second lateral distances may be different. In one embodiment, the disclosed semiconductor device is fabricated as part of an integrated circuit including a power management circuit or a power amplifier.

Abstract: An LDMOS device includes a substrate of a first conductivity type, an epitaxial layer on the substrate, a buried well of a second conductivity type opposite to the first conductivity type in a lower portion of the epitaxial layer, the epitaxial layer being of the first conductivity type below the buried layer. The device further includes a field oxide located between a drain and both a gate on a gate oxide and a source with a saddle shaped vertical doping gradient of the second conductivity type in the epitaxial layer above the buried well such that the dopant concentration in the epitaxial layer above the buried well and below a central portion of the field oxide is lower than the dopant concentration at the edges of the field oxide nearest the drain and nearest the gate.

Abstract: A MOSFET comprises a first semiconductor region having a first surface, a first insulation-filled trench region extending from the first surface into the first semiconductor region, and strips of semi-insulating material along the sidewalls of the first insulation-filled trench region. The strips of semi-insulating material are insulated from the first semiconductor region.

Abstract: A semiconductor device includes: an n-type first well diffusion layer; an n-type second well diffusion layer; a p-type source diffusion layer; a p-type third well diffusion layer; a p-type drain diffusion layer; a gate insulating film; a gate electrode; a device isolation insulating film; and a buffer layer. The buffer layer is formed between the first well diffusion layer and the third well diffusion layer to be in contact with an end of the third well diffusion layer opposing the source diffusion layer, and extends from immediately below the gate insulating film to a position deeper than a peak of curvature of impurity concentration distribution of the third well diffusion layer. The buffer layer has an impurity concentration lower than an impurity concentration in the third well diffusion layer.

Abstract: A semiconductor device with a charge carrier compensation structure. In one embodiment, the semiconductor device has a central cell field with a gate and source structure. At least one bond contact area is electrically coupled to the gate structure or the source structure. A capacitance-increasing field plate is electrically coupled to at least one of the near-surface bond contact areas.

Abstract: A super-junction trench MOSFET with Resurf Stepped Oxide is disclosed. The inventive structure can apply additional freedom for better optimization and manufacturing capability by tuning thick oxide thickness to minimize influence of charge imbalance, trapped charges, etc. . . . . Furthermore, the fabrication method can be implemented more reliably with lower cost.

Abstract: A semiconductor device is provided which includes a semiconductor substrate, a gate structure formed on the substrate, sidewall spacers formed on each side of the gate structure, a source and a drain formed in the substrate on either side of the gate structure, the source and drain having a first type of conductivity, a lightly doped region formed in the substrate and aligned with a side of the gate structure, the lightly doped region having the first type of conductivity, and a barrier region formed in the substrate and adjacent the drain. The barrier region is formed by doping a dopant of a second type of conductivity different from the first type of conductivity.

Abstract: The present invention provides a vertical tapered dielectric high-voltage device (10) in which the device drift region is depicted by action of MOS field plates (30) formed in vertical trenches. The high-voltage device comprises: a substrate (32); a silicon mesa (20) formed on the substrate and having a stripe geometry, wherein the silicon mesa provides a drift region having a constant doping profile; a recessed gate (22) and source (SN) formed on the silicon mesa; a trench (26) adjacent each side of the silicon mesa; and a metal-dielectric field plate structure (12) formed in each trench; wherein each metal-dielectric field plate structure comprises a dielectric (28) and a metal field plate (30) formed over the dielectric, and wherein a thickness of the dielectric increases linearly through a depth of the trench to provide a constant longitudinal electric field.

Abstract: According to an embodiment of a method for manufacturing a MISFET device, in a semiconductor wafer, a semiconductor layer is formed, having a first type of conductivity and a first level of doping. A first body region and a second body region, having a second type of conductivity, opposite to the first type of conductivity, and an enriched region, extending between the first and second body regions are formed in the semiconductor layer. The enriched region has the first type of conductivity and a second level of doping, higher than the first level of doping. Moreover, a gate electrode is formed over the enriched region and over part of the first and second body regions, and a dielectric gate structure is formed between the gate electrode and the semiconductor layer, the dielectric gate structure having a larger thickness on the enriched region and a smaller thickness on the first and second body regions.

Abstract: Semiconductor component having an oxide layer. One embodiment includes a first semiconductor region and a second semiconductor region. An oxide layer is arranged between the first and second semiconductor region. The first semiconductor region and the oxide layer form a first semiconductor-oxide interface. The second semiconductor region and the oxide layer form a second semiconductor-oxide interface. The oxide layer has a chlorine concentration, the chlorine concentration having a first maximum in the region of the first semiconductor-oxide interface, and having a second maximum in the region of the second semiconductor-oxide interface.

Abstract: A semiconductor chip having a transistor is described. The transistor having a gate electrode disposed over a gate dielectric. The gate electrode comprised of first gate material disposed on the gate dielectric and second gate material disposed on the gate dielectric. The first gate material being different than the second gate material. The second gate material also located at a source region or drain region of said gate electrode.

Abstract: A power device with improved reliability and a method for producing the same is disclosed. One embodiment provides an active area having an electrical power dissipation characteristic, a metallization layer portion configured with respect to the active area so that the dissipation characteristic of the active area results in heating the metallization layer portion, the metallization layer portion being formed as a connected region. The metallization layer portion has at least one hole, fully extending through the metal layer and having a dielectric. The at least one hole is arranged so that each location of the metal layer portion is connected electrically to each other location via the metallization material of the metal layer portion.

Abstract: A semiconductor structure includes a semiconductor substrate of a first conductivity type; a pre-high-voltage well (pre-HVW) in the semiconductor substrate, wherein the pre-HVW is of a second conductivity type opposite the first conductivity type; a high-voltage well (HVW) over the pre-HVW, wherein the HVW is of the second conductivity type; a field ring of the first conductivity type occupying a top portion of the HVW, wherein at least one of the pre-HVW, the HVW, and the field ring comprises at least two tunnels; an insulation region over the field ring and a portion of the HVW; a drain region in the HVW and adjacent the insulation region; a gate electrode over a portion the insulation region; and a source region on an opposite side of the gate electrode than the drain region.

Abstract: A semiconductor integrated circuit device may include: a substrate that includes a high-voltage device region and a low-voltage device region defined on the substrate; a first buried impurity layer formed in at least a portion of the high-voltage device region and coupled to a first voltage; a second buried impurity layer formed in at least a portion of the low-voltage device region and coupled to a second voltage less than the first voltage; and a well formed on the second buried impurity layer in the low-voltage device region and coupled to a third voltage less than the second voltage.

Abstract: A semiconductor component includes a body with a drift zone, a source zone, a body zone, and a drain zone. A gate forms a MOS structure with the drift zone, with the source zone and with the body zone. An edge termination between the lateral edge and the MOS structure includes a plurality of field rings which enclose the MOS structure. The lateral edge is at the same potential as the drift zone, and the edge termination reduces voltage between the lateral edge and the source zone. A horizontally extending edge plate is disposed at the front side between the lateral edge and the edge termination. The edge plate is at the same potential as the drift zone and forms a plate capacitor structure including a field plate lying above the edge plate.

Abstract: The semiconductor device includes: a first conductive-type first well and a second conductive-type second well configured over a substrate to contact each other; a second conductive-type anti-diffusion region configured in an interface where the first conductive-type first well contacts the second conductive-type second well over the substrate; and a gate electrode configured to simultaneously cross the first conductive-type first well, the second conductive-type anti-diffusion region, and the second conductive-type second well over the substrate.

Abstract: A semiconductor device includes a source, a drain, and a gate configured to selectively enable a current to pass between the source and the drain. The semiconductor device includes a drift zone between the source and the drain and a first field plate adjacent the drift zone. The semiconductor device includes a dielectric layer electrically isolating the first field plate from the drift zone and charges within the dielectric layer close to an interface of the dielectric layer adjacent the drift zone.

Abstract: A semiconductor device includes a semiconductor layer of a first conductivity type; a deep well of a second conductivity type formed in a portion of an upper layer portion of the semiconductor layer; a well of the first conductivity type formed in a portion of an upper layer portion of the deep well; a source layer of the second conductivity type formed in the well; a drain layer of the second conductivity type formed in the well apart from the source layer; and a contact layer of the second conductivity type formed outside the well in an upper layer portion of the deep well and connected to the drain layer. The drain layer is electrically connected to the deep well via the well by applying a driving voltage between the source layer and the drain layer.

Abstract: A dielectric material layer is formed on a bottom surface and sidewalls of a trench in a semiconductor substrate. The silicon oxide layer forms a drift region dielectric on which a field plate is formed. Shallow trench isolation may be formed prior to formation of the drift region dielectric, or may be formed utilizing the same processing steps as the formation of the drift region dielectric. A gate dielectric layer is formed on exposed semiconductor surfaces and a gate conductor layer is formed on the gate dielectric layer and the drift region dielectric. The field plate may be electrically tied to the gate electrode, may be an independent electrode having an external bias, or may be a floating electrode. The field plate biases the drift region to enhance performance and extend allowable operating voltage of a lateral diffusion field effect transistor during operation.

Abstract: A dual channel trench LDMOS transistor includes a substrate of a first conductivity type; a semiconductor layer of a second conductivity type formed on the substrate; a first trench formed in the semiconductor layer where a trench gate is formed in an upper portion of the first trench; a body region of the first conductivity type formed in the semiconductor layer adjacent the first trench; a source region of the second conductivity type formed in the body region and adjacent the first trench; a planar gate overlying the body region; a drain region of the second conductivity type spaced apart from the body region by a drain drift region. The planar gate forms a lateral channel in the body region, and the trench gate in the first trench forms a vertical channel in the body region of the LDMOS transistor.

Abstract: This invention discloses configurations and methods to manufacture lateral power device including a super junction structure with an avalanche clamp diode formed between the drain and the gate. The lateral super-junction structure reduces on-resistance, while the structural enhancements, including an avalanche clamping diode and an N buffer region, increase the breakdown voltage between substrate and drain and improve unclamped inductive switching (UIS) performance.

Abstract: Laterally diffused metal oxide semiconductor transistor for a radio frequency-power: amplifier comprising a drain finger (25,27) which drain finger is connected to a stack of one or more metal interconnect layers, (123,61,59,125) wherein a metal interconnect layer (123) of said stack is connected to a drain region (25) on the substrate, wherein said stack comprises a field plate (123, 125, 121) adapted to reduce the maximum magnitude of the electric field between the drain and the substrate and overlying the tip of said drain finger.

Abstract: A plurality of transistor cells, each of which can include a transistor P-body region and a Schottky diode, wherein the transistor P-body region can be formed below the Schottky diode to provide a semiconductor device having desirable electrical characteristics.

Abstract: A power metal-oxide semiconductor (MOS) transistor device is provided. The power MOS transistor device includes a drain region disposed in a substrate, a gate structure layer disposed over the substrate, and enclosing a periphery of the drain region, and a source region formed in the substrate and distributed at an outer periphery of the gate structure layer. In addition, the MOS transistor device can, for example, form a transistor array.

Abstract: A lateral power semiconductor component has a front side, a rear side and a lateral edge. The component further includes a drift zone of a first conductivity type, a source zone of the first conductivity type, a body zone of a second conductivity type opposite the first conductivity type, and a drain zone of the first conductivity type. A gate forms a MOS structure with the drift zone, the source zone and the body zone. A horizontally extending field plate above each semiconductor region of the power semiconductor component forms a plate capacitor structure with an edge plate lying under the field plate. The edge plate includes a highly doped semiconductor material and is electrically connected to one of a source potential and a drain potential of the power semiconductor component.

Abstract: The present invention provides a laterally diffused metal oxide semiconductor (LDMOS) transistor and a method for fabricating it. The LDMOS transistor includes an n-type epitaxial layer formed on a p-type substrate, and an asymmetric conductive spacer which acts as its gate. The LDMOS transistor also includes a source and a drain region on either side of the asymmetric conductive spacer, and a channel region formed by ion-implantation on the asymmetric conductive spacer. The height of the asymmetric conductive spacer increases from the source region to the drain region. The channel region is essentially completely under the asymmetric conductive spacer and has smaller length than that of the channel region of the prior art LDMOS transistors. The LDMOS transistor of the present invention also includes a field oxide layer surrounding the active region of the transistor, and a thin dielectric layer isolating the asymmetric conductive spacer from the n-type epitaxial layer.

Abstract: A split gate power transistor includes a laterally configured power MOSFET including a doped silicon substrate, a gate oxide layer formed on a surface of the substrate, and a split polysilicon layer formed over the gate oxide layer. The polysilicon layer is cut into two electrically isolated portions, a first portion forming a polysilicon gate positioned over a channel region of the substrate, and a second portion forming a polysilicon field plate formed over a portion of a transition region of the substrate. The field plate also extends over a drift region of the substrate, where the drift region is under a field oxide filled trench formed in the substrate. The field plate is electrically coupled to a source of the split gate power transistor.

Abstract: A semiconductor device includes a semiconductor layer of a first conductivity type and a first doping concentration. A first semiconductor region, used as drain, of the first conductivity type has a lower doping concentration than the semiconductor layer and is over the semiconductor layer. A gate dielectric is over the first semiconductor region. A gate electrode over the gate dielectric has a metal-containing center portion and first and second silicon portions on opposite sides of the center portion. A second semiconductor region, used as a channel, of the second conductivity type has a first portion under the first silicon portion and the gate dielectric. A third semiconductor region, used as a source, of the first conductivity type is laterally adjacent to the first portion of the second semiconductor region. The metal-containing center portion, replacing silicon, increases the source to drain breakdown voltage.

Abstract: A semiconductor device includes: a p-type active region; a gate electrode traversing the active region; an n-type LDD region having a first impurity concentration and formed from a drain side region to a region under the gate electrode; a p-type channel region having a second impurity concentration and formed from a source side region to a region under the gate electrode to form an overlap region with the LDD region under the gate electrode, the channel region being shallower than the LDD region; an n-type source region formed outside the gate electrode; and an n+-type drain region having a third impurity concentration higher than the first impurity concentration formed outside and spaced from the gate electrode, wherein an n-type effective impurity concentration of an intermediate region between the gate electrode and the n+-type drain region is higher than an n-type effective impurity concentration of the overlap region.

Abstract: A semiconductor device and method is disclosed. One embodiment provides an active region in a semiconductor substrate, including a first terminal region and a second terminal region.

Abstract: A method includes forming a transistor device on a first side of a semiconductor-on-insulator structure. The semiconductor-on-insulator structure includes a substrate, a dielectric layer, and a buried layer between the substrate and the dielectric layer. The method also includes forming a conductive plug through the semiconductor-on-insulator structure. The conductive plug is in electrical connection with the transistor device. The method further includes forming a field plate on a second side of the semiconductor-on-insulator structure, where the field plate is in electrical connection with the conductive plug. The transistor device could have a breakdown voltage of at least 600V, and the field plate could extend along at least 40% of a length of the transistor device.

Abstract: According to an exemplary embodiment, a method for fabricating a MOS transistor, such as an LDMOS transistor, includes forming a self-aligned lightly doped region in a first well underlying a first sidewall of a gate. The method further includes forming a self-aligned extension region under a second sidewall of the gate, where the self-aligned extension region extends into the first well from a second well. The method further includes forming a drain region spaced apart from the second sidewall of the gate. The method further includes forming a source region in the self-aligned lightly doped region and the first well. The self-aligned lightly doped region and the self-aligned extension region define a channel length of the MOS transistor, such as an LDMOS transistor.

Abstract: A high-voltage field-effect device contains an extended drain or “drift” region including an embedded stack of JFET regions separated by intervening layers of the drift region. Each of the JFET regions is filled with material of an opposite conductivity type to that of the drift region, and the floor and ceiling of each JFET region is lined with an oxide layer. When the device is blocking a voltage in the off condition, the semiconductor material inside the JFET regions and in the drift region that separates the JFET regions is depleted. This improves the voltage-blocking ability of the device while conserving chip area. The oxide layer prevents dopant from the JFET regions from diffusing into the drift region.

Abstract: A lateral-diffusion metal-oxide-semiconductor device includes a source in a racetrack shaped active area, a first field oxide region isolating and surrounding the racetrack shaped active area, a racetrack shaped gate surrounding the source, and a drain disposed at one side of the gate opposite to the source. The source includes a P+ doping region in a P well and an N+ doping region butting on the P+ doping region.

Abstract: In one embodiment, a high voltage field-effect transistor (HVFET) includes a field oxide layer that covers a first well region, the field oxide layer having a first thickness and extending in a second lateral direction from a drain region to near a second well region. A gate oxide covers a channel region and has a second dimension in a first lateral direction. A gate extends in the second lateral direction from the source region to over a portion of the field oxide layer, the gate being insulated from the channel region by the gate oxide, the gate extending in the first lateral dimension over an inactive area of the HVFET beyond the second dimension of the gate oxide, the gate being insulated from the first and second well regions over the inactive area by the field oxide layer.

Abstract: A semiconductor device includes: a SOI substrate; a semiconductor element having first and second impurity layers disposed in an active layer of the SOI substrate, the second impurity layer surrounding the first impurity layer; and multiple first and second conductive type regions disposed in a part of the active layer adjacent to an embedded insulation film of the SOI substrate. The first and second conductive type regions are alternately arranged. The first and second conductive type regions have a layout, which corresponds to the semiconductor element.

Abstract: An exemplary lateral diffused metal oxide semiconductor device includes a first-type substrate, a gate oxide film disposed on the first-type substrate, a poly gate disposed on the gate oxide film, a first second-type slightly doped region formed in the first-type substrate and acting as a well, a first first-type highly doped region formed in the well and acting as a body, a first second-type highly doped region formed in the body and acting as a source, a second second-type highly doped region formed in the well and acting as a drain, a second first-type highly doped region formed in the body, and a first first-type doped region formed in the body and is beneath the source.

Abstract: A high-performance semiconductor structure and a method of fabricating such a structure are provided. The semiconductor structure includes at least one gate stack, e.g., FET, located on an upper surface of a semiconductor substrate. The structure further includes a first epitaxy semiconductor material that induces a strain upon a channel of the at least one gate stack. The first epitaxy semiconductor material is located at a footprint of the at least one gate stack substantially within a pair of recessed regions in the substrate which are present on opposite sides of the at least one gate stack. A diffused extension region is located within an upper surface of said first epitaxy semiconductor material in each of the recessed regions. The structure further includes a second epitaxy semiconductor material located on an upper surface of the diffused extension region. The second epitaxy semiconductor material has a higher dopant concentration than the first epitaxy semiconductor material.

Abstract: A semiconductor device and a method for making a semiconductor device are disclosed. A trench mask may be applied to a semiconductor substrate, which is etched to form trenches with three different widths. A first conductive material is formed at the bottom of the trenches. A second conductive material is formed over the first conductive material. An insulator layer separates the first and second conductive materials. A first insulator layer is deposited on top of the trenches. A body layer is formed in a top portion of the substrate. A source is formed in the body layer. A second insulator layer is applied on top of the trenches and the source. A contact mask is applied on top of the second insulator layer. Source and gate contacts are formed through the second insulator layer. Source and gate metal are formed on top of the second insulator layer.

Abstract: A disclosed power transistor, suitable for use in a switch mode converter that is operable with a switching frequency exceeding, for example, 5 MHz or more, includes a gate dielectric layer overlying an upper surface of a semiconductor substrate and first and second gate electrodes overlying the gate dielectric layer. The first gate electrode is laterally positioned overlying a first region of the substrate. The first substrate region has a first type of doping, which may be either n-type or p-type. A second gate electrode of the power transistor overlies the gate dielectric and is laterally positioned over a second region of the substrate. The second substrate region has a second doping type that is different than the first type. The transistor further includes a drift region located within the substrate in close proximity to an upper surface of the substrate and laterally positioned between the first and second substrate regions.

Abstract: Provided is a LOCOS offset MOS field-effect transistor in which a first lightly-doped N-type drain offset region with a LOCOS oxide film and a second lightly-doped N-type drain offset region without a LOCOS oxide film are formed in a drain-side offset region, and both the regions are covered with a gate electrode. Provision of the first lightly-doped N-type drain offset region mitigates an electric field applied to the first lightly-doped N-type drain offset region to increase a breakdown voltage. Provision of the second lightly-doped N-type drain offset region increases carriers within the second lightly-doped N-type drain offset region to obtain a high current drivability.

Abstract: A LDMOS device for an ESD protection circuit is provided. The LDMOS device includes a substrate of a first conductivity type, a deep well region of a second conductivity type, a body region of the first conductivity type, first and second doped regions of the second conductivity type, and a gate electrode. The deep well region is disposed in the substrate. The body region and the first doped region are respectively disposed in the deep well region. The second doped region is disposed in the body region. The gate electrode is disposed on the deep well region between the first and second doped regions. It is noted that the body region does not include a doped region of the first conductivity type having a different doped concentration from the body region.

Abstract: A metal oxide semiconductor device comprising a substrate, at least an isolation structure, a deep N-type well, a P-type well, a gate, a plurality of N-type extension regions, an N-type drain region, an N-type source region and a P-type doped region is provided. The N-type extension regions are disposed in the substrate between the isolation structures and either side of the gate, while the N-type drain region and the N-type source region are respectively disposed in the N-type extension regions at both sides of the gate. The P-type well surrounds the N-type extension regions, and the P-type doped region is disposed in the P-type well of the substrate and is isolated from the N-type source region by the isolation structure.

Abstract: Improved radio frequency gain in a silicon-based bipolar transistor may be provided by adoption of a common-base configuration, preferably together with excess doping of the base to provide extremely low base resistances boosting performance over similar common-emitter designs.

Abstract: According to one embodiment, a power semiconductor device includes a second semiconductor layer of a first conductivity type and a third semiconductor layer of a second conductivity type periodically disposed repeatedly along a surface of the first semiconductor layer on a first semiconductor layer of the first conductivity type. A first main electrode is provided to electrically connect to the first semiconductor layer. A fourth semiconductor layer of the second conductivity type is provided to connect to the third semiconductor layer. Fifth semiconductor layers of the first conductivity type are selectively provided in the fourth semiconductor layer surface. A second main electrode is provided on a surface of the fourth and fifth semiconductor layers. A control electrode is provided on a surface of the fourth, fifth, and second semiconductor layers via a gate insulating film. First insulating films are provided by filling a trench made in the second semiconductor layer.

Abstract: A short channel Lateral MOSFET (LMOS) and method are disclosed with interpenetrating drain-body protrusions (IDBP) for reducing channel-on resistance while maintaining high punch-through voltage. The LMOS includes lower device bulk layer; upper source and upper drain region both located atop lower device bulk layer; both upper source and upper drain region are in contact with an intervening upper body region atop lower device bulk layer; both upper drain and upper body region are shaped to form a drain-body interface; the drain-body interface has an IDBP structure with a surface drain protrusion lying atop a buried body protrusion while revealing a top body surface area of the upper body region; gate oxide-gate electrode bi-layer disposed atop the upper body region forming an LMOS with a short channel length defined by the horizontal length of the top body surface area delineated between the upper source region and the upper drain region.

Abstract: According to an exemplary embodiment, a method for fabricating a MOS transistor, such as an LDMOS transistor, includes forming a gate stack over a well. The method further includes forming a recess in the well adjacent to a first sidewall of the gate stack. The method further includes forming a source region in the recess such that a heterojunction is formed between the source region and the well. The method further includes forming a drain region spaced apart from a second sidewall of the gate stack. In one embodiment, the source region can comprise silicon germanium and the well can comprise silicon. In another embodiment, the source region can comprise silicon carbide and the well can comprise silicon.

Abstract: A semiconductor device has an insulating film and an n-type buried layer. The insulating film is formed in a flat-shaped cavity formed inside a p-type semiconductor substrate and in a trench extending from a surface of the semiconductor substrate to the cavity. The buried layer is formed in surrounding regions of the cavity and the trench in the semiconductor substrate.

Abstract: Semiconductor device fabrication method and devices are disclosed. A device may be fabricated by forming in a semiconductor layer; filling the trench with an insulating material; removing selected portions of the insulating material leaving a portion of the insulating material in a bottom portion of the trench; forming one or more spacers on one or more sidewalls of a remaining portion of the trench; anisotropically etching the insulating material in the bottom portion of the trench using the spacers as a mask to form a trench in the insulator; removing the spacers; and filling the trench in the insulator with a conductive material. Alternatively, an oxide-nitride-oxide (ONO) structure may be formed on a sidewall and at a bottom of the trench and one or more conductive structures may be formed in a portion of the trench not occupied by the ONO structure.