Abstract: A non-volatile memory is formed on a substrate. The non-volatile memory includes an isolation structure, a floating gate, and a gate dielectric layer. The isolation structure is disposed in the substrate to define an active area. The floating gate is disposed on the substrate and crosses over the active area. The gate dielectric layer is disposed between the floating gate and the substrate. The floating gate includes a first region and a second region. An energy band of the second region is lower than an energy band of the first region, so that charges stored in the floating gate are away from an overlap region of the floating gate and the gate dielectric layer.

Abstract: In a nonvolatile semiconductor memory device provided with memory cell transistors arranged in a direction and a select transistor to select the memory cell transistors, each of the memory cell transistors of a charge trap type are at least composed of a first insulating layer and a first gate electrode respectively, and the select transistor is at least composed of a second insulating layer and a second gate electrode. The first gate electrode is provided with a first silicide layer of a first width formed on the first insulating layer. The second gate electrode is provided with an impurity-doped silicon layer formed on the second insulating layer and with a second silicide layer of a second width formed on the impurity-doped silicon layer. The second silicide has the same composition as the first silicide. The second width is larger than the first width.

Abstract: A semiconductor storage device according to the present invention includes: a semiconductor substrate; an embedded insulator embedded in a trench formed in the semiconductor substrate and having an upper portion protruding above a top surface of the semiconductor substrate; a first insulating film formed on the top surface of the semiconductor substrate; a floating gate formed on the first insulating film at a side of the embedded insulator, having a side portion arching out above the embedded insulator, and having a side surface made of a flat surface and a curved surface continuing below the flat surface; a second insulating film contacting an upper surface, the flat surface and the curved surface of the floating gate; and a control gate opposing the upper surface, the flat surface and the curved surface of the floating gate across the second insulating film.

Abstract: A nonvolatile semiconductor memory device according to an embodiment includes a plurality of cell array layers, each cell array layer including: a plurality of semiconductor layers that extends in a first direction; gate insulating layers; a plurality of floating gates arranged in the first direction; inter-gate insulating layers; and a plurality of control gates that extends in a second direction intersecting semiconductor layers, and faces the floating gates via the inter-gate insulating layers, in which, in the cell array layers adjacent each other in a stacking direction, the control gates of a lower cell array layer and the control gates of the an upper cell array layer are intersecting each other, and the floating gates within the lower cell array layer and the semiconductor layers within the upper cell array layer are aligned in position with each other.

Abstract: The present invention discloses a floating gate structure of a flash memory device and a method for fabricating the same, which relates to a nonvolatile memory in a manufacturing technology of an ultra-large-scaled integrated circuit. In the invention, by modifying a manufacturing of a floating gate in the a standard process for the flash memory, that is, by adding three steps of deposition, two steps of etching and one step of CMP, an -shaped floating gate is formed. In addition to these steps, all the other steps are the same as those of the standard process for the flash memory process. By the invention, a coupling ratio may be improved effectively and a crosstalk between adjacent devices may be lowered, without adding additional photomasks and barely increasing a process complexity, which are very important to improve programming speed and reliability.

Abstract: A method and system for providing at least one contact in a flash memory device is disclosed. The flash memory device includes a plurality of gate stacks and at lease one component including a polysilicon layer as a top surface. The method and system further include forming a silicide on the top surface of the polysilicon layer and providing an insulating layer covering the plurality of gate stacks, the at least one component and the silicide. The method and system also include etching the insulating layer to provide at least one contact hole. The insulating layer etching step uses the silicide as an etch stop layer to ensure that the insulating etching step does not etch through the polysilicon layer. The method and system also include filling the at least one contact hole with a conductor.

Abstract: A lamination pattern having a control gate electrode, a first insulation film thereover, and a second insulation film thereover is formed over a semiconductor substrate. A memory gate electrode is formed adjacent to the lamination pattern. A gate insulation film is formed between the control gate and the semiconductor substrate. A fourth insulation film, including a lamination film of a silicon oxide film, a silicon nitride film, and another silicon oxide film, is formed between the memory gate electrode and the semiconductor substrate and between the lamination pattern and the memory gate electrode. At the sidewall on the side of the lamination pattern adjacent to the memory gate electrode, the first insulation film is retreated from the control gate electrode and the second insulation film, and the upper end corner portion of the control gate electrode is rounded.

Abstract: An example of a method of fabricating a gate oxide of a floating gate transistor includes forming a plurality of shallow trench isolation (STI) regions in a silicon wafer. The method also includes selectively filling the STI regions with oxide. Further, the method includes forming sacrificial oxide regions on the silicon wafer. Furthermore, the method includes forming implant regions in the silicon wafer. In addition, the method includes selectively removing the sacrificial oxide regions. The method further includes forming the gate oxide.

Abstract: A non-volatile memory cell includes first and second regions and a channel region therebetween, a word line gate over a first portion of the channel region, a floating gate over another portion of the channel region and adjacent to the word line gate, a coupling gate over the floating gate, and an erase gate adjacent to the floating gate on an opposite side to the word line gate and over the second region. Programming the memory cell includes applying a first positive voltage to the word line gate, applying a voltage differential between the first and second regions, applying a second positive voltage to the coupling gate (where the voltages and the voltage differential are applied substantially at the same time), and applying a third positive voltage to the erase gate after a period of delay from the application of the first and second positive voltages and the voltage differential.

Abstract: A flash memory device wherein the floating gate of the flash memory is defined by a recessed access device. The use of a recessed access device results in a longer channel length with less loss of device density. The floating gate can also be elevated above the substrate a selected amount so as to achieve a desirable coupling between the substrate, the floating gate and the control gate comprising the flash cell.

Abstract: A semiconductor device includes a first conductive layer, a first intermediate structure over the first conductive layer, a second intermediate structure over the first intermediate structure, and a second conductive layer over the second intermediate structure. The first intermediate structure includes a metal silicide layer and a nitrogen containing metal layer. The second intermediate structure includes at least a nitrogen containing metal silicide layer.

Abstract: A method for forming a field effect transistor (FET) device includes forming a dielectric layer on a substrate, forming a first metal layer on the dielectric layer, removing a portion of the first metal layer to expose a portion of the dielectric layer, forming a second metal layer on the dielectric layer and the first metal layer, and removing a portion of the first metal layer and the second metal layer to define a boundary region between a first FET device and a second FET device.

Abstract: A device having thin-film transistor (TFT) floating gate memory cell structures is provided. The device includes a substrate, a dielectric layer on the substrate, and one or more source or drain regions being embedded in the dielectric layer. the dielectric layer being associated with a first surface. Each of the one or more source or drain regions includes an N+ polysilicon layer on a diffusion barrier layer which is on a first conductive layer. The N+ polysilicon layer has a second surface substantially co-planar with the first surface. Additionally, the device includes a P? polysilicon layer overlying the co-planar surface and a floating gate on the P? polysilicon layer. The floating gate is a low-pressure CVD-deposited silicon layer sandwiched by a bottom oxide tunnel layer and an upper oxide block layer. Moreover, the device includes at least one control gate made of a P+ polysilicon layer overlying the upper oxide block layer.

Abstract: The invention enhances program performance by increasing a coupling ratio between an N+ type source layer and a floating gate and reduces a memory cell area. Trenches are formed on the both sides of an N+ type source layer. The sidewalls of the trench includes first and second trench sidewalls that are parallel to end surfaces of two element isolation layers, a third trench sidewall that is perpendicular to the STIs, and a fourth trench sidewall that is not parallel to the third trench sidewall. The N+ type source layer is formed so as to extend from the bottom surface of the trench to the fourth trench sidewall, largely overlapping a floating gate, by performing ion-implantation of arsenic ion or the like in a parallel direction to the third trench sidewall and in a perpendicular direction or at an angle to a P type well layer from above the trench having this structure.

Abstract: In a non-volatile memory in which writing/erasing is performed by changing a total charge amount by injecting electrons and holes into a silicon nitride film serving as a charge accumulation layer, in order to realize a high efficiency of a hole injection from a gate electrode, the gate electrode of a memory cell comprises a laminated structure made of a plurality of polysilicon films with different impurity concentrations, for example, a two-layered structure comprising a p-type polysilicon film with a low impurity concentration and a p+-type polysilicon film with a high impurity concentration deposited thereon.

Abstract: Over the top of a semiconductor substrate, a lamination pattern having a control gate electrode, a first insulation film thereover, and a second insulation film thereover is formed. Over the top of the semiconductor substrate, a memory gate electrode adjacent to the lamination pattern is formed. Between the control gate electrode and the semiconductor substrate, a third insulation film for gate insulation film is formed. Between the memory gate electrode and the semiconductor substrate, and between the lamination pattern and the memory gate electrode, a fourth insulation film including a lamination film of a silicon oxide film, a silicon nitride film, and another silicon oxide film is formed. At the sidewall on the side of the lamination pattern adjacent to the memory gate electrode, the first insulation film is retreated from the control gate electrode and the second insulation film, and the upper end corner portion of the control gate electrode is rounded.

Abstract: A memory cell is provided including a tunnel dielectric layer overlying a semiconductor substrate. The memory cell also includes a floating gate having a first portion overlying the tunnel dielectric layer and a second portion in the form of a nanorod extending from the first portion. In addition, a control gate layer is separated from the floating gate by an intergate dielectric layer.

Abstract: An electronic device includes a first memory cell and a second memory cell, of a nonvolatile memory array. The first memory cell includes a body region, a gate structure, a source region, and a drain region. The second memory cell includes a body region, a gate structure, a source region, and a drain region. In one embodiment, the body of the second memory cell is physically isolated from the body region of the first memory cell. A bitline segment is electrically connected to the drain region of the first memory cell and to the drain region of the second memory cell.

Abstract: A semiconductor device has a first-conductivity-type-channel MOSFET formed on a semiconductor substrate, wherein the first-conductivity-type-channel MOSFET is typically a P-channel MOSFET, and is composed of a gate insulating film and a gate electrode provided over the semiconductor substrate, the gate electrode contains a metal gate electrode provided over the gate insulating film, a metal oxide film provided over the metal gate electrode, and another metal gate electrode provided over metal oxide film.

Abstract: A nonvolatile semiconductor memory device having a source-side-injected split-gate type of nonvolatile memory cell which can be formed by a one-layer polysilicon CMOS process is provided. A memory cell includes a first memory cell unit including first and second diffusion regions formed on a semiconductor substrate surface, and first and second gate electrodes separately formed through a gate insulation film on a first channel region between the first and second diffusion regions, a second memory cell unit including third and fourth diffusion regions formed on the semiconductor substrate surface, and a third gate electrode formed through a gate insulation film on a second channel region between the third and fourth diffusion regions, and a control terminal. The first to third gate electrodes are formed of the same electrode material layer. The second and third gate electrodes are electrically connected to form a floating gate capacitively coupled to the control terminal.

Abstract: A split gate-type non-volatile semiconductor memory device includes a floating gate having an acute-angled portion between a side surface and an upper surface above a semiconductor substrate; a control gate provided apart from the floating gate to oppose to the acute-angled portion; and an insulating portion provided on the floating gate. A side surface of the insulating portion on a side of the control gate is inclined to a direction apart from the control gate with respect to a vertical line to the semiconductor substrate.

Abstract: Semiconductor devices and methods of forming the same. The semiconductor devices include a tunnel insulation layer on a substrate, a floating gate on the tunnel insulation layer, a gate insulation layer on the floating gate, a low-dielectric constant (low-k) region between the top of the floating gate and the gate insulation layer, the low-k region having a lower dielectric constant than a silicon oxide, and a control gate on the gate insulation layer.

Abstract: Some embodiments include memory cells that contain floating bodies and diodes. The diodes may be gated diodes having sections doped to a same conductivity type as the floating bodies, and such sections of the gated diodes may be electrically connected to the floating bodies. The floating bodies may be adjacent channel regions, and spaced from the channel regions by a dielectric structure. The dielectric structure of a memory cell may have a first portion between the floating body and the diode, and may have a second portion between the floating body and the channel region. The first portion may be more leaky to charge carriers than the second portion. The diodes may be formed in semiconductor material that is different from a semiconductor material that the channel regions are in. The floating bodies may have bulbous lower regions. Some embodiments include methods of making memory cells.

Abstract: Provided are three-dimensional nonvolatile memory devices and methods of fabricating the same. The memory devices include semiconductor pillars penetrating interlayer insulating layers and conductive layers alternately stacked on a substrate and electrically connected to the substrate and floating gates selectively interposed between the semiconductor pillars and the conductive layers. The floating gates are formed in recesses in the conductive layers.

Abstract: A flash memory device including a lower tunnel insulation layer on a substrate, an upper tunnel insulation layer on the lower tunnel insulation layer, and a P-type gate on the upper tunnel insulation layer, wherein the upper tunnel insulation layer includes an amorphous oxide layer.

Abstract: Methods, devices, and systems for a memory cell are provided. One embodiment includes a memory cell with a storage node separated from a body region by a first dielectric, wherein the body region includes a channel separating a source and a drain region, and wherein a length of the storage node is less than a length of the channel. The embodiment further includes a memory cell with a gate separated from the storage node by a second dielectric, wherein a length of the gate is greater than a length of the storage node.

Abstract: Non-volatile memory devices are provided including a control gate electrode on a substrate; a charge storage insulation layer between the control gate electrode and the substrate; a tunnel insulation layer between the charge storage insulation layer and the substrate; a blocking insulation layer between the charge storage insulation layer and the control gate electrode; and a material layer between the tunnel insulation layer and the blocking insulation layer, the material layer having an energy level constituting a bottom of a potential well.

Abstract: Exemplary power semiconductor devices with features providing increased breakdown voltage and other benefits are disclosed.

Abstract: Semiconductor memory having both volatile and non-volatile modes and methods of operation.

Abstract: Memories, systems, and methods for forming memory cells are disclosed. One such memory cell includes a charge storage node that includes nanodots over a tunnel dielectric and a protective film over the nanodots. In another memory cell, the charge storage node includes nanodots that include a ruthenium alloy. Memory cells can include an inter-gate dielectric over the protective film or ruthenium alloy nanodots and a control gate over the inter-gate dielectric. The protective film and ruthenium alloy can be configured to protect at least some of the nanodots from vaporizing during formation of the inter-gate dielectric.

Abstract: A flash memory device includes a wafer; a gate oxide layer disposed upon the wafer; a floating gate disposed upon the gate oxide layer, the wafer, or a combination thereof; the floating gate including a flat floating gate portion and a generally rectangular floating gate portion disposed upon selected areas of the flat floating gate portion; a high K dielectric material disposed upon the floating gate; and a control gate disposed upon the high K dielectric material; wherein the high K dielectric material forms a zigzag pattern coupling the floating gate with the control gate.

Abstract: Embodiments of the invention provide a semiconductor integrated circuit device and a method for fabricating the device. The semiconductor device includes a semiconductor substrate having a cell region and a peripheral region, a cell active region formed in the cell region, and a peripheral active region formed in the peripheral region, wherein the cell active region and the peripheral active region are defined by isolation regions. The semiconductor device further includes a first gate stack formed on the cell active region, a second gate stack formed on the peripheral active region, a cell epitaxial layer formed on an exposed portion of the cell active region, and a peripheral epitaxial layer formed on an exposed portion of the peripheral active region, wherein the height of the peripheral epitaxial layer is greater than the height of the cell epitaxial layer.

Abstract: A non-volatile memory device includes a memory cell region which is formed on a semiconductor substrate to store predetermined information, and a peripheral circuit region which is formed on the semiconductor substrate. The memory cell region includes a gate electrode; and a charge storage layer, the charge storage layer being formed to be a notch or wedge shape having an edge extending into both sides of a bottom end of the gate electrode. The peripheral circuit region includes no charge storage layer therein.

Abstract: A plurality of NAND cells are arranged in a cell array. In each of the NAND cells, a pair of selection gate transistors is connected in series to a plurality of memory cell transistors. An inter-gate connection trench is formed in an insulating film between layers of stacked gates of the selection gate transistors. The stacked gates are electrically connected to each other. At an end part of the cell array in the row direction, an STI area is formed, and dummy NAND cells are formed at an end part in the row direction. A dummy selection gate transistor is connected in series to a plurality of dummy memory cell transistors. No inter-gate connection trench is present in an insulating film between layers of stacked gates of the dummy selection gate transistor, and the stacked gates of the dummy selection gate transistor are not electrically connected to each other.

Abstract: There is provided a nonvolatile semiconductor memory device, including, a tunnel insulator, a floating gate electrode including a first floating gate electrode and a second floating gate electrode being constituted with a nondegenerate state semiconductor, an intergate insulating film formed to cover at least continuously an upper and a portion of a side surface of the floating gate electrode, and a control gate electrode in order, and an isolation insulating film, a lower portion of the isolation insulating film being embedded in the semiconductor substrate in both sides of the floating gate electrode along a channel width direction, an upper portion of the isolation insulating film contacting with a side surface of the first floating gate electrode and protruding to a level between an upper surface of the semiconductor substrate and an upper surface of the first floating gate electrode.

Abstract: In a semiconductor device, a first gate structure is provided in a cell transistor region and includes a floating gate electrode, a first dielectric layer pattern, and a control gate electrode including a first metal silicide pattern. A second gate structure is provided in a selecting transistor region and includes a first conductive layer pattern, a second dielectric layer pattern, and a first gate electrode including a second metal silicide pattern. A third gate structure is provided in a peripheral circuit region and includes a second conductive layer pattern, a third dielectric layer pattern including opening portions on the second conductive layer pattern, and a second gate electrode including a concavo-convex portion at an upper surface portion thereof and a third metal silicide pattern. The third metal silicide pattern has a uniform thickness.

Abstract: A nonvolatile semiconductor memory device includes: a semiconductor member; a memory film provided on a surface of the semiconductor member and being capable of storing charge; and a plurality of control gate electrodes provided on the memory film, spaced from each other, and arranged along a direction parallel to the surface. Average dielectric constant of a material interposed between one of the control gate electrodes and a portion of the semiconductor member located immediately below the control gate electrode adjacent to the one control gate electrode is lower than average dielectric constant of a material interposed between the one control gate electrode and a portion of the semiconductor member located immediately below the one control gate electrode.

Abstract: A semiconductor memory device is provided including: a spacer shaped floating gate formed on a semiconductor substrate; a dielectric layer spacer formed at one side wall of the floating gate; a third oxide layer formed over the floating gate and the dielectric layer; and a control gate formed over the third oxide layer. According to an embodiment, the structure of the floating gate in a plate shape whose center is concave is improved to the spacer structure, making it possible to minimize the size of the semiconductor memory device and to improve density. Moreover, a LOCOS process can be excluded while forming the floating gate, making it possible to more efficiently fabricate the device.

Abstract: A semiconductor apparatus is presented that includes an array of memory cells. The memory cells are arranged in rows and columns. Non-intersecting shallow trench isolation regions isolate the columns of memory cells. Also included is at least one source region that is isolated between an adjoining pair of the non-intersecting shallow trench isolation regions and isolated from a drain region. The source region is coupled to source lines in the array of memory cells. A contact couples a select plurality of the columns of memory cells, the select plurality functioning as a single content addressable memory cell.

Abstract: A method for fabricating a gated semiconductor device, and the device resulting from performing the method. In a preferred embodiment, the method includes forming a hard mask for use in gate formation on one or more layers of alternately insulating and conducting material that have been formed on a substrate. The hard mask preferably includes three layers; a lower nitride layer, a middle oxide, and an upper nitride layer. In this embodiment, the middle oxide layer is formed with the rest of the hard mask, and then reduced in a lateral dimension, preferably using a DHF dip. A dielectric layer formed over the gate structure, including the hard mask, then etched back, self-aligns to be reduced-dimension oxide layer. In addition, where two conducting, that is gate layers are present, the lower layer is laterally reduced in dimension on at least one side to create an undercut.

Abstract: According to one embodiment, a nonvolatile semiconductor memory device includes a semiconductor substrate including a first region in which a memory cell transistor is arranged, a second region in which an electrode that extracts a word line electrically connected to the memory cell transistor is arranged, and a third region in which a peripheral transistor is arranged, the semiconductor substrate including an element isolation layer which separates adjacent active regions, first active regions provided in the first region and each having a first width, second active regions provided in the second region and each having a second width greater than the first width, third active regions provided in the third region and each having a third with greater than the first width. An upper surface of an element isolation layer in the second region is higher than that of an element isolation layer in the first region.

Abstract: A semiconductor device having a non-volatile memory and a method of manufacturing the same are provided. The semiconductor device includes a base material and a stack structure. The stack structure disposed on the base material at least includes a tunneling layer, a trapping layer and a dielectric layer. The trapping layer is disposed on the tunneling layer. The dielectric layer has a dielectric constant and is disposed on the trapping layer. The dielectric layer is transformed from a first solid state to a second solid state when the dielectric layer undergoes a process.

Abstract: A nonvolatile semiconductor memory device includes a gate electrode formed on a gate insulating film, a source/drain region formed at each side of the gate electrode and including a first region, a second region and a third region located between the first and second regions, a first silicon oxide film formed on a sidewall of the gate electrode, a second silicon oxide film formed on the third region, and a silicon nitride film formed on an upper surface of the second silicon oxide film. The first silicon oxide film, the second silicon oxide film having the silicon nitride film, and a contact plug are contiguously arranged on the first, third and second regions of the source/drain region. The contact plug extends through the second silicon oxide film and the second nitride file to contact the source/drain region.

Abstract: A method of repairing a nonvolatile semiconductor memory device to eliminate defects includes monitoring a memory endurance indicator for a nonvolatile semiconductor memory device contained in a semiconductor package. It is determined whether that the memory endurance indicator exceeds a predefined limit. Finally, in response to determining that the memory endurance indicator exceeds the predefined limit, the device is annealed.

Abstract: An object is to suppress reading error even in the case where writing and erasing are repeatedly performed. Further, another object is to reduce writing voltage and erasing voltage while increase in the area of a memory transistor is suppressed. A floating gate and a control gate are provided with an insulating film interposed therebetween over a first semiconductor layer for writing operation and erasing operation and a second semiconductor layer for reading operation which are provided over a substrate; injection and release of electrons to and from the floating gate are performed using the first semiconductor layer; and reading is performed using the second semiconductor layer.

Abstract: A method and system for providing at least one contact in a flash memory device is disclosed. The flash memory device includes a plurality of gate stacks and at lease one component including a polysilicon layer as a top surface. The method and system further include forming a silicide on the top surface of the polysilicon layer and providing an insulating layer covering the plurality of gate stacks, the at least one component and the silicide. The method and system also include etching the insulating layer to provide at least one contact hole. The insulating layer etching step uses the silicide as an etch stop layer to ensure that the insulating etching step does not etch through the polysilicon layer. The method and system also include filling the at least one contact hole with a conductor.

Abstract: A method of manufacturing a semiconductor device that comprises the steps of: removing a second insulating film on a contact region of a first conductor; forming a second conductive film on the second insulating film; removing the second conductive film on the contact region of the first conductor to make the second conductive film into a second conductor; forming an interlayer insulating film (a third insulating film) covering the second conductor; forming a first hole in the interlayer insulating film on the contact region; and forming a conductive plug, which is electrically connected with the contact region, in the first hole.

Abstract: The invention relates to a nonvolatile two-transistor semiconductor memory cell and an associated fabrication method, source and drain regions (2 ) for a selection transistor (AT) and a memory transistor (ST) being formed in a substrate (1). The memory transistor (ST) has a first insulation layer (3 ), a charge storage layer (4), a second insulation layer (5) and a memory transistor control layer (6), while the selection transistor (AT) has a first insulation layer (3 ?) and a selection transistor control layer (4*). By using different materials for the charge storage layer (4) and the selection transistor control layer (4*), it is possible to significantly improve the charge retention properties of the memory cell by adapting the substrate doping with electrical properties remaining the same.

Abstract: Some embodiments include memory cells that contain floating bodies and diodes. The diodes may be gated diodes having sections doped to a same conductivity type as the floating bodies, and such sections of the gated diodes may be electrically connected to the floating bodies. The floating bodies may be adjacent channel regions, and spaced from the channel regions by a dielectric structure. The dielectric structure of a memory cell may have a first portion between the floating body and the diode, and may have a second portion between the floating body and the channel region. The first portion may be more leaky to charge carriers than the second portion. The diodes may be formed in semiconductor material that is different from a semiconductor material that the channel regions are in. The floating bodies may have bulbous lower regions. Some embodiments include methods of making memory cells.

Abstract: In a nonvolatile semiconductor memory device provided with memory cell transistors arranged in a direction and a select transistor to select the memory cell transistors, each of the memory cell transistors of a charge trap type are at least composed of a first insulating layer and a first gate electrode respectively, and the select transistor is at least composed of a second insulating layer and a second gate electrode. The first gate electrode is provided with a first silicide layer of a first width formed on the first insulating layer. The second gate electrode is provided with an impurity-doped silicon layer formed on the second insulating layer and with a second silicide layer of a second width formed on the impurity-doped silicon layer. The second silicide has the same composition as the first silicide. The second width is larger than the first width.