Abstract: A ferroelectric memory device according to an aspect of the present disclosure includes a substrate having a channel layer, a first ferroelectric layer disposed on the channel layer, a ferroelectric induction layer disposed on the first ferroelectric layer, the ferroelectric induction layer including an insulator, a second ferroelectric layer disposed on the ferroelectric induction layer, and a gate electrode layer disposed on the second ferroelectric layer.

Abstract: The invention relates to a field-effect transistor including an active zone including a source, a channel, a drain and a control gate, which is positioned level with said channel, allowing a current to flow through said channel between the source and drain along an x-axis, said channel including: a first edge of separation with said source; and a second edge of separation with said drain; said channel being compressively or tensilely strained, characterized in that said channel includes a localized perforation or a set of localized perforations along at least said first and/or second edge of said channel so as to also create at least one shear strain in said channel. The invention also relates to a process for fabricating said transistor.

Abstract: According to various embodiments, a memory cell may include: a field-effect transistor structure comprising a channel region and a gate structure disposed at the channel region, the gate structure comprising a gate electrode structure and a gate isolation structure disposed between the gate electrode structure and the channel region; and a memory structure comprising a first electrode structure, a second electrode structure, and at least one remanent-polarizable layer disposed between the first electrode structure and the second electrode structure; wherein the first electrode structure of the memory structure is electrically conductively connected to the gate electrode structure of the field-effect transistor structure.

Abstract: According to various embodiments, a memory cell may include: a channel region, a gate isolation structure disposed at the channel region; and a memory structure disposed over the gate isolation structure, the memory structure comprising a first electrode structure, a second electrode structure, and at least one remanent-polarizable layer disposed between the first electrode structure and the second electrode structure; wherein the first electrode structure, the gate isolation structure, and the channel region form a first capacitor structure defining a capacitor area of a first size; and wherein the first electrode structure, the at least one remanent-polarizable layer, and the second electrode structure form a second capacitor structure defining a capacitor area of a second size, wherein the second size is less than the first size.

Abstract: According to various embodiments, a memory cell may include: a field-effect transistor structure comprising a channel region and a gate structure disposed at the channel region, the gate structure comprising a gate electrode structure and a gate isolation structure disposed between the gate electrode structure and the channel region; and a memory structure comprising a first electrode structure, a second electrode structure, and at least one remanent-polarizable layer disposed between the first electrode structure and the second electrode structure; wherein the first electrode structure of the memory structure is electrically conductively connected to the gate electrode structure of the field-effect transistor structure.

Abstract: A semiconductor device includes a semiconductor substrate including a channel region and a source/drain region, and an electrically conductive gate on an upper surface of the channel region. An electrically conductive source/drain contact is on an upper surface of the source/drain region. The semiconductor device further includes enhanced low-k spacer on an upper surface of the substrate and interposed between the electrically conductive gate and the electrically conductive source/drain contact. The enhanced low-k spacer includes a stacked arrangement of a dielectric material and a ferroelectric material.

Abstract: A robust gate spacer that can resist a long overetch that is required to form gate spacers in fin field effect transistors (FinFETs) and a method of forming the same are provided. The gate spacer includes a first gate spacer adjacent sidewalls of at least one hard mask and a top portion of sacrificial gate material of a sacrificial gate structure and a second gate spacer located beneath the first gate spacer and adjacent remaining portions of sidewalls of the sacrificial gate material. The first gate spacers is composed of a material having a high etch resistance that is not prone to material loss during subsequent exposure to dry or wet etch chemicals employed to form the second gate spacer and to remove the hard mask.

Abstract: An integrated device includes a semiconductor body including an STI insulating structure that laterally delimits first active areas and at least one second active area in a low-voltage region and in a power region of the semiconductor body, respectively. Low-voltage CMOS components are housed in the first active areas. A power component, formed in the second active area, includes a source region, a body region, a drain-contact region, and at least one LOCOS insulation region. The insulating region is arranged between the body region and the drain-contact region and has a prominent portion that emerges from a surface of the semiconductor body, and an embedded portion inside it. The prominent portion of the LOCOS insulation region has a volume greater than that of the embedded portion.

Abstract: A semiconductor device includes a substrate having a first active region, a first gate structure over the first active region, wherein the first gate structure includes a first interfacial layer having a convex top surface, a first high-k dielectric over the first interfacial layer, and a first gate electrode over the first high-k dielectric.

Abstract: Embodiments of transistors comprise a gate stack overlying a semiconductor material. The gate stack comprises a deposited oxide layer overlying the semiconductor material, an oxygen-diffusion barrier layer overlying the deposited oxide layer, a high-k dielectric layer overlying the oxygen-diffusion barrier layer, and a conductive material (e.g., an oxygen-gettering conductive material) overlying the high-k dielectric layer. When the conductive material is an oxygen-gettering conductive material, the oxygen-diffusion barrier layer prevents diffusion of oxygen from the deposited oxide layer to the oxygen-gettering conductive material.

Abstract: This description relates to a method including forming an interlayer dielectric (ILD) layer and a dummy gate structure over a substrate and forming a cavity in a top portion of the ILD layer. The method further includes forming a protective layer to fill the cavity. The method further includes planarizing the protective layer. A top surface of the planarized protective layer is level with a top surface of the dummy gate structure. This description also relates to a semiconductor device including first and second gate structures and an ILD layer formed on a substrate. The semiconductor device further includes a protective layer formed on the ILD layer, the protective layer having a different etch selectivity than the ILD layer, where a top surface of the protective layer is level with the top surfaces of the first and second gate structures.

Abstract: A FinFET comprises an isolation region formed in a substrate, a cloak-shaped active region formed over the substrate, wherein the cloak-shaped active region has an upper portion protruding above a top surface of the isolation region. In addition, the FinFET comprises a gate electrode wrapping the channel of the cloak-shaped active region.

Abstract: A semiconductor device includes a first field effect transistor (FET) and a second FET located on a substrate, the first FET comprising a first interfacial oxide layer, and the second FET comprising a second interfacial oxide layer, wherein the second interfacial oxide layer of the second FET is thicker than the first interfacial oxide layer of the first FET; and a recess located in the substrate adjacent to the second FET.

Abstract: A method for fabricating a semiconductor device includes forming a recess pattern by selectively etching a substrate; forming a gate dielectric layer filling the recess pattern on the substrate; forming a groove by selectively etching the gate dielectric layer; forming a polysilicon electrode filling the groove; forming an electrode metal layer on the polysilicon electrode and the gate dielectric layer; and forming a gate pattern by etching the electrode metal layer and the gate dielectric layer. The recess pattern is formed along an edge portion of the gate pattern as a quadrilateral periphery.

Abstract: A semiconductor product has different active thicknesses of silicon on a single semiconductor substrate. The thickness of the silicon layer is changed either by selectively adding silicon or subtracting silicon from an original layer of silicon. The different active thicknesses are suitable for use in different types of devices, such as diodes and transistors.

Abstract: The invention describes in detail the structure of a CMOS image sensor pixel that senses color of impinging light without having absorbing filters placed on its surface. The color sensing is accomplished by having a vertical stack of three-charge detection nodes placed in the silicon bulk, which collect electrons depending on the depth of their generation. The small charge detection node capacitance and thus high sensitivity with low noise is achieved by using fully depleted, potential well forming, buried layers instead of undepleted junction electrodes. Two embodiments of contacting the buried layers without substantially increasing the node capacitances are presented.

Abstract: Disclosed is a transistor that incorporates epitaxially deposited source/drain semiconductor films and a method for forming the transistor. A crystallographic etch is used to form recesses between a channel region and trench isolation regions in a silicon substrate. Each recess has a first side, having a first profile, adjacent to the channel region and a second side, having a second profile, adjacent to a trench isolation region. The crystallographic etch ensures that the second profile is angled so that all of the exposed recess surfaces comprise silicon. Thus, the recesses can be filled by epitaxial deposition without divot formation. Additional process steps can be used to ensure that the first side of the recess is formed with a different profile that enhances the desired stress in the channel region.

Abstract: A thin film transistor of the present invention has an active layer including at least source, drain and channel regions formed on an insulating surface. A high resistivity region is formed between the channel region and each of the source and drain regions. A film capable of trapping positive charges therein is provided on at least the high resistivity region so that N-type conductivity is induced in the high resistivity region. Accordingly, the reliability of N-channel type TFT against hot electrons can be improved.

Abstract: A peripheral circuit area is formed around a memory cell array area. The peripheral circuit area has element regions, an element isolation region isolating the element regions, and field-effect transistor formed in each of the element regions and including a gate electrode extending in a channel width direction, on a semiconductor substrate. An end portion and a corner portion of the gate electrode are on the element isolation region. A radius of curvature of the corner portion of the gate electrode is smaller than a length from the end portion of the element region in the channel width direction to the end portion of the gate electrode in the channel width direction, and is less than 85 nm.

Abstract: A semiconductor device includes: a high dielectric constant gate insulating film formed on an active region in a substrate; a gate electrode formed on the high dielectric constant gate insulating film; and an insulating sidewall formed on each side surface of the gate electrode. The high dielectric constant gate insulating film is continuously formed so as to extend from under the gate electrode to under the insulating sidewall. At least part of the high dielectric constant gate insulating film located under the insulating sidewall has a smaller thickness than a thickness of part of the high dielectric constant gate insulating film located under the gate electrode.

Abstract: A semiconductor device includes a thin film transistor. The thin film transistor includes a semiconductor film over a substrate, in which the semiconductor film includes a pair of first regions, a pair of second regions interposed between the pair of first regions, and a channel formation region interposed between the pair of second regions. A concentration of an impurity in the pair of second regions is smaller than a concentration of the impurity in the pair of first regions. The thin film transistor includes an insulating film, in which a portion of the insulating film is provided over the semiconductor film. The thin film transistor includes a conductive film over the portion, and the conductive film includes a taper shape.

Abstract: An embodiment of a MOS device resistant to ionizing-radiation, has: a surface semiconductor layer with a first type of conductivity; a gate structure formed above the surface semiconductor layer, and constituted by a dielectric gate region and a gate-electrode region overlying the dielectric gate region; and body regions having a second type of conductivity, formed within the surface semiconductor layer, laterally and partially underneath the gate structure. In particular, the dielectric gate region is formed by a central region having a first thickness, and by side regions having a second thickness, smaller than the first thickness; the central region overlying an intercell region of the surface semiconductor layer, set between the body regions.

Abstract: A recessed channel transistor includes an isolation layer provided in a semiconductor substrate to define an active region. A trench is provided in the semiconductor substrate to extend across the active region. A gate insulation layer covers a sidewall and a bottom face of the trench and an upper face of the semiconductor substrate adjacent to an upper edge of the trench, wherein a portion of the gate insulation layer on the upper surface of the semiconductor substrate adjacent to the upper edge of the trench and on the sidewall of the trench extending to a first distance downwardly from the upper edge of the trench has a thickness greater than that of a portion of the gate insulation layer on the remaining sidewall and the bottom face of the trench. A gate electrode fills up the trench having the gate insulation layer formed therein.

Abstract: A field-effect transistor (142) includes a lowly p-doped region 110 formed on a surface of a substrate (102), an n-doped drain region 112 and n-doped source region 114 arranged on a surface of the lowly p-doped region 110, and a device isolation insulating film 132 and device isolation insulating film 134. Here, the device isolation insulating film 132 is formed greater in film thickness than the device isolation insulating film 134; and in the n-doped source region 114, the peak concentration section having a highest dopant concentration is formed in a deeper position than in the n-doped drain region 112.

Abstract: Methods are provided for fabricating a transistor. An exemplary method involves depositing an oxide layer overlying a layer of semiconductor material, forming an oxygen-diffusion barrier layer overlying the oxide layer, forming a layer of high-k dielectric material overlying the oxygen-diffusion barrier layer, forming a layer of conductive material overlying the layer of high-k dielectric material, selectively removing portions of the layer of conductive material, the layer of high-k dielectric material, the oxygen-diffusion barrier layer, and the oxide layer to form a gate stack, and forming source and drain regions about the gate stack. When the conductive material is an oxygen-gettering conductive material, the oxygen-diffusion barrier layer prevents diffusion of oxygen from the deposited oxide layer to the oxygen-gettering conductive material.

Abstract: A stack pad layers including a first pad oxide layer, a pad nitride layer, and a second pad oxide layer are formed on a semiconductor-on-insulator (SOI) substrate. A deep trench extending below a top surface or a bottom surface of a buried insulator layer of the SOI substrate and enclosing at least one top semiconductor region is formed by lithographic methods and etching. A stress-generating insulator material is deposited in the deep trench and recessed below a top surface of the SOI substrate to form a stress-generating buried insulator plug in the deep trench. A silicon oxide material is deposited in the deep trench, planarized, and recessed. The stack of pad layer is removed to expose substantially coplanar top surfaces of the top semiconductor layer and of silicon oxide plugs. The stress-generating buried insulator plug encloses, and generates a stress to, the at least one top semiconductor region.

Abstract: A semiconductor device. The device comprises an active region isolated by an isolation structure on a substrate. The device further comprises a gate electrode extending across the active area and overlying the substrate, a pair of source region and drain region, disposed on either side of the gate electrode on the substrate in the active area, and a gate dielectric layer disposed between the substrate and the gate electrode. The gate dielectric layer comprises a relatively-thicker high voltage (HV) dielectric portion and a relatively-thinner low voltage (LV) dielectric portion, wherein the HV dielectric portion occupies a first intersection among the drain region, the isolation structure, and the gate electrode, and a second intersection among the source region, the isolation structure, and the gate electrode.

Abstract: A semiconductor device according to one embodiment includes: an n-type transistor comprising a first gate electrode formed on a semiconductor substrate via a first gate insulating film, a first channel region formed in the semiconductor substrate under the first gate insulating film, and first source/drain regions formed in the semiconductor substrate on both sides of the first channel region, the first gate electrode comprising a first metal layer and a first conductive layer thereon; and a p-type transistor comprising a second gate electrode formed on the semiconductor substrate via a second gate insulating film, a second channel region formed in the semiconductor substrate under the second gate insulating film, and second source/drain regions formed in the semiconductor substrate on both sides of the second channel region, the second gate electrode comprising a second metal layer and a second conductive layer thereon, the second metal layer being thicker than the first metal layer and having the same const

Abstract: A semiconductor device includes a semiconductor substrate, a gate insulating film formed on the semiconductor substrate, a gate electrode formed on the gate insulating film, a source/drain diffusion layer formed in the semiconductor substrate at both sides of the gate electrode, and a channel region formed in the semiconductor substrate between a source and a drain of the source/drain diffusion layer and arranged below the gate insulating film, wherein an upper surface of the source/drain diffusion layer is positioned below a bottom surface of the gate electrode, and an upper surface of the channel region is positioned below the upper surface of the source/drain diffusion layer.

Abstract: Disclosed is a transistor that incorporates epitaxially deposited source/drain semiconductor films and a method for forming the transistor. A crystallographic etch is used to form recesses between a channel region and trench isolation regions in a silicon substrate. Each recess has a first side, having a first profile, adjacent to the channel region and a second side, having a second profile, adjacent to a trench isolation region. The crystallographic etch ensures that the second profile is angled so that all of the exposed recess surfaces comprise silicon. Thus, the recesses can be filled by epitaxial deposition without divot formation. Additional process steps can be used to ensure that the first side of the recess is formed with a different profile that enhances the desired stress in the channel region.

Abstract: A semiconductor device includes a tube-type channel formed over a semiconductor substrate. The tube-type channel is connected to first and second conductive lines. A bias electrode is formed in the tube-type channel. The bias electrode is connected to the semiconductor substrate. An insulating film is disposed between the tube-type channel and the bias electrode. A surrounding gate electrode is formed over the tube-type channel.

Abstract: Provided is a semiconductor apparatus including a substrate region, an active region on the substrate region, a gate pattern on the active region, and first and second impurities-doped regions along both edges of the active region that do not overlap the gate pattern. The length of the first and second impurities-doped regions in the horizontal direction may be shorter than in the vertical direction. The first and second impurities-doped regions may be formed to be narrow along both edges of the active region so as not to overlap the gate pattern.

Abstract: An electrical antifuse comprising a field effect transistor includes a gate dielectric having two gate dielectric portions. Upon application of electric field across the gate dielectric, the magnitude of the electrical field is locally enhanced at the boundary between the thick and thin gate dielectric portions due to the geometry, thereby allowing programming of the electrical antifuse at a lower supply voltage between the two electrodes, i.e., the body and the gate electrode of the transistor, across the gate dielectric.

Abstract: An integrated circuit is disclosed that includes a first layer made of active semiconductor material and extending along a first side of a buried layer, and trench structures, which cut through the layer made of active semiconductor material and have dielectric wall regions, whereby the dielectric wall regions isolate electrically subregions of the layer, made of active semiconductor material in the lateral direction, and whereby the trench structures, furthermore, have first inner regions, which are filled with electrically conductive material and contact the buried layer in an electrically conductive manner. The integrated circuit is notable in that the first wall regions of the trench structures completely cut through the buried layer and the second wall regions of the trench structures extend into the buried layer, without cutting it completely. Furthermore, a method for manufacturing such an integrated circuit is disclosed.

Abstract: An embodiment of a MOS device resistant to ionizing-radiation, has: a surface semiconductor layer with a first type of conductivity; a gate structure formed above the surface semiconductor layer, and constituted by a dielectric gate region and a gate-electrode region overlying the dielectric gate region; and body regions having a second type of conductivity, formed within the surface semiconductor layer, laterally and partially underneath the gate structure. In particular, the dielectric gate region is formed by a central region having a first thickness, and by side regions having a second thickness, smaller than the first thickness; the central region overlying an intercell region of the surface semiconductor layer, set between the body regions.

Abstract: An integrated circuit including a floating body transistor and method. One embodiment provides a transistor including a body region formed in a first portion and a first and a second source/drain region formed in a second and a third portion. The body region is formed in a semiconductor substrate. The integrated circuit further includes a buried structure disposed at least below the body region and a first and a second insulating structure including an insulating material and being disposed at least between the body region and regions of the second and the third portion below the first and the second source drain region, wherein the first and the second insulating structure contact the buried structure.

Abstract: On a semiconductor substrate, a well is formed. In the well, one MOS transistor including a gate electrode, a source region, a source field limiting layer and a source/drain region, and another MOS transistor including a gate electrode, a drain electrode, a drain field limiting layer and a source/drain region are formed. The one and another MOS transistors are connected in series through the source/drain region common to the two transistors. Accordingly, a semiconductor device can be provided in which increase in pattern layout area is suppressed when elements including a high-breakdown voltage MOS transistor are to be connected in series.

Abstract: A photo mask and a semiconductor device fabricated using the same is disclosed. The photo mask to form a mask pattern defining a STAR gate region includes a transparent substrate, and a light-shielding pattern defining a zigzag W-STAR gate region, wherein a waved portion of the light-shielding pattern partially overlaps a gate region and a storage node contact region of an active region disposed on a semiconductor substrate. The semiconductor device includes an active region and a device isolation region defining the active region disposed in a semiconductor substrate, a gate electrode, wherein a line width of the gate electrode in the active region is greater than that in the device isolation region, and a zigzag W-STAR gate region, wherein the waved portion of the zigzag W-STAR gate region partially overlaps the gate region and the storage node contact region in the active region.

Abstract: Flash memory devices include a pair of elongated, closely spaced-apart main active regions in a substrate. A sub active region is also provided in the substrate, extending between the pair of elongated, closely spaced-apart main active regions. A bit line contact plug is provided on, and electrically contacting, the sub active region and being at least as wide as the sub active region. An elongated bit line is provided on, and electrically contacting, the bit line contact plug remote from the sub active region.

Abstract: Provided is a CMOS image sensor and method for manufacturing the same. The CMOS image sensor includes a semiconductor substrate, a gate electrode formed on the semiconductor substrate, a conductive diffusion region formed in a photodiode area of the semiconductor substrate, a floating diffusion region formed in a transistor region of the semiconductor substrate, and an oxide region formed in the semiconductor substrate below the floating diffusion region.

Abstract: The invention describes in detail the structure of a CMOS image sensor pixel that senses color of impinging light without having absorbing filters placed on its surface. The color sensing is accomplished by having a vertical stack of three-charge detection nodes placed in the silicon bulk, which collect electrons depending on the depth of their generation. The small charge detection node capacitance and thus high sensitivity with low noise is achieved by using fully depleted, potential well forming, buried layers instead of undepleted junction electrodes. Two embodiments of contacting the buried layers without substantially increasing the node capacitances are presented.

Abstract: A semiconductor power transistor includes a drift region of a first conductivity type and a well region of a second conductivity type in the drift region such that the well region and the drift region form a pn junction therebetween. A first highly doped silicon region of the first conductivity type is in the well region, and a second highly doped silicon region is in the drift region. The second highly doped silicon region is laterally spaced from the well region such that upon biasing the transistor in a conducting state, a current flows laterally between first and second highly doped silicon regions through the drift region. Each of a plurality of trenches extending into the drift region perpendicular to the current flow includes a dielectric layer lining at least a portion of the trench sidewalls and at least one conductive electrode.

Abstract: A FET structure is provided in which at least one stressor element provided at or near one corner of an active semiconductor region applies a stress in a first direction to one side of a channel region of the FET to apply a torsional stress to the channel region of the FET. In a particular embodiment, a second stressor element is provided at or near an opposite corner of the active semiconductor region to apply a stress in a second direction to an opposite side of a channel region of the FET, the second direction being opposite to the first direction. In this way, the first and second stressor elements cooperate together in applying a torsional stress to the channel region of the FET.

Abstract: A gate structure in a transistor and method for fabricating the structure. A gate structure is formed on a substrate. The gate structure includes three layers: an oxide layer, a nitride layer and a polysilicon layer. The oxide layer is located on the substrate, the nitride layer is located on the oxide layer, and the polysilicon layer is located on the nitride layer. The gate structure is reoxidized to form a layer of oxide over the gate structure.

Abstract: A semiconductor device includes a support substrate and a semiconductor layer formed on the underlying substrate. The support substrate has its metal part formed by plating and extending across its entire thickness, whilst it has the other region made of semiconductor part. In particular, the region of the support substrate lying immediately below an active region is the metal part formed by plating. The region of the support substrate lying immediately below the region other than the active region is an inactive region made of semiconductor. The semiconductor device thus suppresses warping of a substrate otherwise caused by stress in the metal part formed by plating, and heat evolved due to the current in operation of the semiconductor device may be dissipated over the shortest path through the metal part having a higher thermal conductivity.

Abstract: A semiconductor device includes a semiconductor substrate having an active region including a channel portion. An isolation layer is formed in the semiconductor substrate to define the active region, and a gate is formed over the channel portion in the active region. The active region of the semiconductor substrate is etched to such that the entire active region is below an upper surface of the isolation layer. A U-shaped groove is formed in the channel portion of the active region, except the edges in a direction of the channel width thereof, in order to increase the channel width. In the semiconductor device, there is an increase in channel length and channel width leading to a reduction in leakage current and on increase in operation current.

Abstract: A method of manufacturing a semiconductor device comprises the following steps: a step of depositing a silicon oxide film on the top surface of an epitaxial layer of the region where a high withstand voltage MOS transistor is formed; a step of subsequently depositing a silicon oxide film on the top surface of the epitaxial layer according to the thickness of a gate oxide film of a low withstand voltage MOS transistor; and a step of subsequently adjusting the thickness of the silicon oxide film on the top surface of the high withstand voltage MOS transistor by etching and forming a P-type diffusion layer by ion-implantation method. This method can manufacture elements having gate oxide films different in thickness at low cost.

Abstract: A semiconductor device includes: an isolation region formed in a semiconductor substrate; an active region surrounded by the isolation region; and a first gate electrode formed on the isolation region and the active region and including a first region on the isolation region. The first region has a pattern width in a gate length direction larger than a pattern width of the first gate electrode on the active region. The first region includes a part having a film thickness different from a film thickness of the first gate electrode on the active region.

Abstract: An exemplary method of manufacturing a semiconductor device according to an embodiment of the present invention includes forming a P-well and an N-well for high voltage (HV) devices and a first well in a low voltage/medium voltage (LV/MV) region for a logic device, in a semiconductor substrate; simultaneously forming a second well in the LV/MV region for a logic device and a drift region for one of the HV devices using the same mask; and respectively forming gate oxide layers on the semiconductor substrate in the HV/MV/LV regions. According to the present invention, the number of photolithography processes can be reduced by replacing or combining an additional mask for forming an extended drain region of a high voltage depletion-enhancement CMOS (DECMOS) with a mask for forming a typical well of a logic device, so productivity of the total process of the device can be enhanced.

Abstract: A method of producing an element separation structure includes the steps of: forming a first thermal oxide film on the substrate; forming a silicon nitride film on the first thermal oxide film; removing the first thermal oxide film and the silicon nitride film in an element separation structure forming region; forming a groove portion in the element separation structure forming region; forming a groove portion oxide film in the groove portion; forming a pre-filling oxide film for filling the groove portion; removing the pre-filling oxide film; forming a resist layer on the silicon nitride film and the pre-filling oxide film; forming a resist mask on the element separation structure forming region; removing the silicon nitride film and the first thermal oxide film; forming a second thermal oxide film on the substrate; and removing the second thermal oxide film and leveling the pre-filling oxide film to form a filling portion.