Abstract: Method for filling a gap, comprising providing in a deposition chamber a semiconductor substrate having a gap, wherein a bottom of the gap includes a crystalline semiconducting material and wherein a side wall of the gap includes an amorphous material; depositing a silicon precursor in the gap.

Abstract: A method for doping fins includes, for a first dopant layer formed in a first region and a second region to a height continuously below a top portion of a plurality of fins such that an entirety of the first dopant layer is formed below the top portion of the plurality of fins, and a dielectric layer formed over the top portion of the plurality of fins, removing the dielectric layer and the first dopant layer in the first region to expose a first fin in the first region, forming a second dopant layer over the first fin, and annealing to drive dopants into the fins from the first dopant layer in the second region and from the second dopant layer in the first region.

Abstract: A method for doping fins includes forming a first dopant layer in a first region and a second region to a height relative to a plurality of fins, forming a dielectric layer over the fins, removing the dielectric layer and the first dopant layer in the first region to expose a first fin in the first region, forming a second dopant layer over the first fin, and annealing to drive dopants into the fins from the first dopant layer in the second region and from the second dopant layer in the first region.

Abstract: A method for manufacturing a semiconductor device includes forming a fin structure having a top surface and side surfaces. A mask layer is disposed over the top surface. A doping support layer is formed to cover part of the fin structure. A first impurity is introduced into a first region of the fin structure covered by the doping support layer, by implanting the first impurity into the doping support layer so that the implanted first impurity is introduced into the first region of the fin structure through the side surfaces.

Abstract: The present disclosure provides a semiconductor structure. The semiconductor structure includes a fin active region formed on a semiconductor substrate and spanning between a first sidewall of a first shallow trench isolation (STI) feature and a second sidewall of a second STI feature; an anti-punch through (APT) feature of a first type conductivity; and a channel material layer of the first type conductivity, disposed on the APT feature and having a second doping concentration less than the first doping concentration. The APT feature is formed on the fin active region, spans between the first sidewall and the second sidewall, and has a first doping concentration.

Abstract: The embodiments of mechanisms for doping wells of finFET devices described in this disclosure utilize depositing doped films to dope well regions. The mechanisms enable maintaining low dopant concentration in the channel regions next to the doped well regions. As a result, transistor performance can be greatly improved. The mechanisms involve depositing doped films prior to forming isolation structures for transistors. The dopants in the doped films are used to dope the well regions near fins. The isolation structures are filled with a flowable dielectric material, which is converted to silicon oxide with the usage of microwave anneal. The microwave anneal enables conversion of the flowable dielectric material to silicon oxide without causing dopant diffusion. Additional well implants may be performed to form deep wells. Microwave anneal(s) may be used to anneal defects in the substrate and fins.

Abstract: A structure comprising at least one DTI-type insulating trench in a substrate, the trench being at the periphery of at least one active area of the substrate forming a pixel, the insulating trench including a cavity filled with a dielectric material, the internal walls of the cavity being covered with a layer made of a boron-doped material.

Abstract: Disclosed are methods of forming bulk FinFET semiconductor devices to reduce punch through leakage currents. One example includes forming a plurality of trenches in a semiconducting substrate to define a plurality of spaced-apart fins, forming a doped layer of insulating material in the trenches, wherein an exposed portion of each of the fins extends above an upper surface of the doped layer of insulating material while a covered portion of each of the fins is positioned below the upper surface of the doped layer of insulating material, and performing a process operation to heat at least the doped layer of insulating material to cause a dopant material in the doped layer to migrate from the doped layer of insulating material into the covered portions of the fins and thereby define a doped region in the covered portions of the fins that is positioned under the exposed portions of the fins.

Abstract: A semiconductor device is formed with extended STI regions. Embodiments include implanting oxygen under STI trenches prior to filling the trenches with oxide and subsequently annealing. An embodiment includes forming a recess in a silicon substrate, implanting oxygen into the silicon substrate below the recess, filling the recess with an oxide, and annealing the oxygen implanted silicon. The annealed oxygen implanted silicon extends the STI region, thereby reducing leakage current between N+ diffusions and N-well and between P+ diffusions and P-well, without causing STI fill holes and other defects.

Abstract: Methods of forming an insulative element are described, including forming a first metal oxide material having a first dielectric constant, forming a second metal oxide material having a second dielectric constant different from the first, and heating at least portions of the structure to crystallize at least a portion of at least one of the first dielectric material and the second dielectric material. Methods of forming a capacitor are described, including forming a first electrode, forming a dielectric material with a first oxide and a second oxide over the first electrode, and forming a second electrode over the dielectric material. Structures including dielectric materials are also described.

Abstract: A method for fabricating semiconductor dice includes the steps of providing a wafer assembly having a substrate and semiconductor structures on the substrate; and defining the semiconductor dice on the substrate. The method also includes the step of separating the substrate from the semiconductor structures by applying a first laser pulse to each semiconductor die on the substrate having first parameters selected to break an interface between the substrate and the semiconductor structures and then applying a second laser pulse to each semiconductor die on the substrate having second parameters selected to complete separation of the substrate from the semiconductor structures. The method can also include the steps of forming one or more intermediate structures between the semiconductor dice on the substrate configured to protect the semiconductor dice during the separating step.

Abstract: A trench contact silicide is formed on an inner wall of a contact trench that reaches to a buried conductive layer in a semiconductor substrate to reduce parasitic resistance of a reachthrough structure. The trench contact silicide is formed at the bottom, on the sidewalls of the trench, and on a portion of the top surface of the semiconductor substrate. The trench is subsequently filled with a middle-of-line (MOL) dielectric. A contact via may be formed on the trench contact silicide. The trench contact silicide may be formed through a single silicidation reaction with a metal layer or through multiple silicidation reactions with multiple metal layers.

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 method of forming a back gate transistor device includes forming an open isolation trench in a substrate; forming sidewall spacers in the open isolation trench; and using the open isolation trench to perform a doping operation so as to define a doped well region below a bottom surface of the isolation trench that serves as a back gate conductor, wherein the sidewall spacers prevent contamination of a channel region of the back gate transistor device by dopants.

Abstract: Disclosed are methods of forming bulk FinFET semiconductor devices to reduce punch through leakage currents. One example includes forming a plurality of trenches in a semiconducting substrate to define a plurality of spaced-apart fins, forming a doped layer of insulating material in the trenches, wherein an exposed portion of each of the fins extends above an upper surface of the doped layer of insulating material while a covered portion of each of the fins is positioned below the upper surface of the doped layer of insulating material, and performing a process operation to heat at least the doped layer of insulating material to cause a dopant material in the doped layer to migrate from the doped layer of insulating material into the covered portions of the fins and thereby define a doped region in the covered portions of the fins that is positioned under the exposed portions of the fins.

Abstract: A method of manufacturing an electronic device includes the steps of: forming a sacrifice layer made of at least one of an alkali metal oxide and an alkali earth metal oxide in a part of a first substrate; forming a supporting layer covering the sacrifice layer; forming an electronic device on the sacrifice layer with the supporting layer in between; exposing at least a part of a side face of the sacrifice layer by removing a part of the supporting layer; forming a support body between the electronic device and the supporting layer, and a surface of the first substrate; removing the sacrifice layer; breaking the support body and transferring the electronic device onto a second substrate by bringing the electronic device into close contact with an adhesion layer provided on a surface of the second substrate; removing a fragment of the support body belonging to the electronic device; removing at least an exposed region in the adhesion layer not covered with the electronic device; and forming a fixing layer on a

Abstract: An embodiment of an integrated circuit includes first and second semiconductor layers and a contact region disposed in the second layer. The first semiconductor layer is of a first conductivity, and the second semiconductor layer is disposed over the first layer and has a surface. The contact region is contiguous with the surface, contacts the first layer, includes a first inner conductive portion, and includes an outer conductive portion of the first conductivity. The contact region may extend deeper than conventional contact regions, because where the inner conductive portion is formed from a trench, doping the outer conductive portion via the trench may allow one to implant the dopants more deeply than conventional techniques allow.

Abstract: A method of forming an integrated circuit structure includes providing a semiconductor substrate; and forming a first and a second MOS device. The first MOS device includes a first active region in the semiconductor substrate; and a first gate over the first active region. The second MOS device includes a second active region in the semiconductor substrate; and a second gate over the second active region. The method further include forming a dielectric region between the first and the second active regions, wherein the dielectric region has an inherent stress; and implanting the dielectric region to form a stress-released region in the dielectric region, wherein source and drain regions of the first and the second MOS devices are not implanted during the step of implanting.

Abstract: A trench contact silicide is formed on an inner wall of a contact trench that reaches to a buried conductive layer in a semiconductor substrate to reduce parasitic resistance of a reachthrough structure. The trench contact silicide is formed at the bottom, on the sidewalls of the trench, and on a portion of the top surface of the semiconductor substrate. The trench is subsequently filled with a middle-of-line (MOL) dielectric. A contact via may be formed on the trench contact silicide. The trench contact silicide may be formed through a single silicidation reaction with a metal layer or through multiple silicidation reactions with multiple metal layers.

Abstract: A semiconductor photovoltaic device comprises a semiconductor substrate having a first surface and a second surface, the first surface and the second surface being opposed to each other, a plurality of trenches extending into the semiconductor substrate from the first surface, the first surface being a substantially planar surface, a dopant region in the semiconductor substrate near the first surface and the plurality of trenches, a first conductive layer over the semiconductor substrate, and a second conductive layer on the second surface of the semiconductor substrate.

Abstract: A description is given of a method for producing isolation trenches (32, 34) with different sidewall dopings on a silicon-based substrate wafer for use in the trench-isolated smart power technology. In this case, a first trench (32) having a first width and a second trench (34) having a second width which is greater than the first width are formed using a hard mask (30). The sidewalls of the first and second trenches are doped in accordance with a first doping type in order to produce sidewalls having a first doping. A material layer (50, 51, 60, 61) is deposited with a thickness determined so as to fill the first trench (32) completely up to and beyond the hard mask and to maintain the gap (34a) in the second trench (34). By means of isotropic etching the material layer is removed from the second trench, but residual material of the material layer is maintained in the first trench.

Abstract: A method for forming a trench structure is provided for a semiconductor and/or memory device, such as an DRAM device. In one embodiment, the method for forming a trench structure includes forming a trench in a semiconductor substrate, and exposing the sidewalls of the trench to an arsenic-containing gas to adsorb an arsenic containing layer on the sidewalls of the trench. A material layer is then deposited on the sidewalls of the trench to encapsulate the arsenic-containing layer between the material layer and sidewalls of the trench.

Abstract: Adding nitrogen to the Si—SiO2 interface at STI sidewalls increases carrier mobility in MOS transistors, but control of the amount of nitrogen has been problematic due to loss of the nitrogen during liner oxide growth. This invention discloses a method of forming STI regions which have a controllable layer of nitrogen atoms at the STI sidewall interface. Nitridation is performed on the STI sidewalls by exposure to a nitrogen-containing plasma, by exposure to NH3 gas at high temperatures, or by deposition of a nitrogen-containing thin film. Nitrogen is maintained at a level of 1.0·1015 to 3.0·1015 atoms/cm2, preferably 2.0·1015 to 2.4·1015 atoms/cm2, at the interface after growth of a liner oxide by adding nitrogen-containing gases to an oxidation ambient. The density of nitrogen is adjusted to maximize stress in a transistor adjacent to the STI regions. An IC fabricated according to the inventive method is also disclosed.

Abstract: A method of forming an integrated circuit structure includes providing a semiconductor substrate; and forming a first and a second MOS device. The first MOS device includes a first active region in the semiconductor substrate; and a first gate over the first active region. The second MOS device includes a second active region in the semiconductor substrate; and a second gate over the second active region. The method further include forming a dielectric region between the first and the second active regions, wherein the dielectric region has an inherent stress; and implanting the dielectric region to form a stress-released region in the dielectric region, wherein source and drain regions of the first and the second MOS devices are not implanted during the step of implanting.

Abstract: In various embodiments, semiconductor structures and methods to manufacture these structures are disclosed. In one embodiment, a structure includes a dielectric material and a void below a surface of a substrate. The structure further includes a doped dielectric material over the dielectric material, over the first void, wherein at least a portion of the dielectric material is between at least a portion of the substrate and at least a portion of the doped dielectric material. Other embodiments are described and claimed.

Abstract: In a semiconductor substrate, a shallow trench isolation structure having a dielectric material disposed in voids of a trench-fill material and a method for forming the shallow trench isolation structure. The voids may be formed during a wet clean process after the dielectric material is formed in the trench. A conformal silicon nitride layer is formed over the substrate and in the voids. After removal of the silicon nitride layer, the voids are at least partially filled by the silicon nitride material.

Abstract: In a method of manufacturing a semiconductor device, a mask pattern is formed on an active region of a substrate. An exposed portion of the substrate is removed to form a trench in the substrate. A preliminary first insulation layer is formed on a bottom and sidewalls of the trench and the mask pattern. A plasma treatment is performed on the preliminary first insulation layer using fluorine-containing plasma to form a first insulation layer including fluorine. A second insulation layer is formed on the first insulation layer to fill the trench. A thickness of a gate insulation layer adjacent to an upper edge of the trench may be selectively increased, and generation of leakage current may be reduced.

Abstract: This invention discloses semiconductor device that includes a top region and a bottom region with an intermediate region disposed between said top region and said bottom region with a controllable current path traversing through the intermediate region. The semiconductor device further includes a trench with padded with insulation layer on sidewalls extended from the top region through the intermediate region toward the bottom region wherein the trench includes randomly and substantially uniformly distributed nano-nodules as charge-islands in contact with a drain region below the trench for electrically coupling with the intermediate region for continuously and uniformly distributing a voltage drop through the current path.

Abstract: A method of forming an integrated circuit structure includes providing a semiconductor substrate; and forming a first and a second MOS device. The first MOS device includes a first active region in the semiconductor substrate; and a first gate over the first active region. The second MOS device includes a second active region in the semiconductor substrate; and a second gate over the second active region. The method further include forming a dielectric region between the first and the second active regions, wherein the dielectric region has an inherent stress; and implanting the dielectric region to form a stress-released region in the dielectric region, wherein source and drain regions of the first and the second MOS devices are not implanted during the step of implanting.

Abstract: Provided is a method of implanting dopant ions to an integrated circuit. The method includes forming a first pixel and a second pixel in a substrate, forming an etch stop layer over the substrate, forming a hard mask layer over the etch stop layer, patterning the hard mask layer to include an opening between the first pixel and the second pixel, and implanting a plurality of dopants through the opening to form an isolation feature.

Abstract: A system and method are disclosed for providing a self aligned bipolar transistor using a silicon nitride ring. An active region of the transistor is formed and a sacrificial emitter is formed above the active region of the transistor. A silicon nitride ring is formed around the sacrificial emitter. The sacrificial emitter and the silicon nitride ring are formed by depositing a layer of silicon nitride material over the active area of the transistor and performing an etch process to simultaneously create both the sacrificial emitter and the silicon nitride ring. The silicon nitride ring provides support for forming a raised external base for the transistor.

Abstract: A doping method for a semiconductor device includes forming a trench in a semiconductor substrate, forming a doped layer doped with a dopant over the undoped layer, and forming a doped region into which the dopant is diffused, wherein the doped region is a portion of the semiconductor substrate in contact with the doped layer.

Abstract: It is intended to provide a plasma processing method and apparatus capable of increasing the uniformity of amorphyzation processing. A prescribed gas is introduced into a vacuum container 1 from a gas supply apparatus 2 through a gas inlet 11 while being exhausted by a turbomolecular pump 3 as an exhaust apparatus through an exhaust hole 12. The pressure in the vacuum container 1 is kept at a prescribed value by a pressure regulating valve 4. High-frequency electric power of 13.56 MHz is supplied from a high-frequency power source 5 to a coil 8 disposed close to a dielectric window 7 which is opposed to a sample electrode 6, whereby induction-coupled plasma is generated in the vacuum container 1. A high-frequency power source 10 for supplying high-frequency electric power to the sample electrode 6 is provided and functions as a voltage source for controlling the potential of the sample electrode 6.

Abstract: A semiconductor device includes a first conductivity type semiconductor substrate. A first conductivity type drift layer is formed on a surface of the first conductivity type semiconductor substrate, and a second conductivity type base region is produced in the first conductivity type drift layer. The second conductivity type base region has a trench formed in a surface thereof. A trench-stuffed layer is formed by stuffing the trench with a suitable material, and a second conductivity type column region formed in the first conductivity type drift layer and sited beneath the trench-stuffed layer.

Abstract: A method for fabricating a semiconductor device includes: providing a semiconductor substrate; forming a STI region on the semiconductor substrate; forming a channel region on the semiconductor substrate; implanting impurities into the STI region; and performing a thermal treatment to diffuse impurities to a side of the channel region.

Abstract: An improved superjunction semiconductor device includes a charged balanced pylon in a body region, where a top of the pylon is large to create slight charge imbalance. A MOSgated structure is formed over the top of the pylon and designed to conduct current through the pylon. By increasing a dimension of the top of the pylon, the resulting device is less susceptible to variations in manufacturing tolerances to obtain a good breakdown voltage and improved device ruggedness.

Abstract: A first example embodiment comprises the following steps and the structure formed therefrom. A trench having opposing sidewalls is formed within a substrate. A stress layer having an inherent stress is formed over the opposing trench sidewalls. The stress layer having stress layer sidewalls over the trench sidewalls. Ions are implanted into one or more portions of the stress layer to form ion-implanted relaxed portions with the portions of the stress layer that are not implanted are un-implanted portions, whereby the inherent stress of the one or more ion-implanted relaxed portions of stress layer portions is relaxed.

Abstract: An embodiment of an integrated circuit includes first and second semiconductor layers and a contact region disposed in the second layer. The first semiconductor layer is of a first conductivity, and the second semiconductor layer is disposed over the first layer and has a surface. The contact region is contiguous with the surface, contacts the first layer, includes a first inner conductive portion, and includes an outer conductive portion of the first conductivity. The contact region may extend deeper than conventional contact regions, because where the inner conductive portion is formed from a trench, doping the outer conductive portion via the trench may allow one to implant the dopants more deeply than conventional techniques allow.

Abstract: A semiconductor device may include a semiconductor substrate, trench region, buffer pattern, gap fill layer, and transistor. The trench region may be provided in the semiconductor substrate to define an active region. The buffer pattern and gap fill layer may be provided in the trench region. The buffer pattern and gap fill layer may fill the trench region. The gap fill layer may be densified by the buffer pattern. The transistor may be provided in the active region. A method of manufacturing a semiconductor device may include: forming a trench region in a semiconductor substrate; forming a buffer layer on an inner wall of the first trench region; forming a gap fill layer, filling the trench region; performing a thermal process to react the impurity with the oxygen, forming a buffer pattern; and forming a transistor in the active region.

Abstract: A semiconductor structure includes a semiconductor layer stack includes a semiconductor substrate of a first conductivity type, a heavily-doped buried layer of a second conductivity type, and a monocrystalline semiconductor layer of a third conductivity type formed on top of the semiconductor layer and the buried layer, a contact to the buried layer, the contact formed in a contact hole, and a lateral insulation of different portions of the semiconductor structure, the insulation formed in an isolation trench. A contact to the semiconductor substrate may be formed within the isolation trench.

Abstract: A method of fabricating and separating semiconductor structures comprises the steps of: (a) partially forming a semiconductor structure attached to a support structure, the partially formed semiconductor structure comprising a plurality of partially formed devices, where the partially formed devices are attached to one another by at least one connective layer; (b) forming a partial mask layer over at least a part of the partially formed devices; (c) etching the connective layer to separate the devices; and (d) removing the partial mask layer. Advantages of the invention include higher yield than conventional techniques. In addition, less expensive equipment can be used to separate the devices. The result is a greater production of devices per unit of time and per dollar.

Abstract: To isolate two active regions formed on a silicon-on-insulator (SOI) substrate, a shallow trench isolation region is filled with liquid phase deposited silicon dioxide (LPD-SiO2) while avoiding covering the active areas with the oxide. By selectively depositing the oxide in this manner, the polishing needed to planarize the wafer is significantly reduced as compared to a chemical-vapor deposited oxide layer that covers the entire wafer surface. Additionally, the LPD-SiO2 does not include the growth seams that CVD silicon dioxide does. Accordingly, the etch rate of the LPD-SiO2 is uniform across its entire expanse thereby preventing cavities and other etching irregularities present in prior art shallow trench isolation regions in which the etch rate of growth seams exceeds that of the other oxide areas.

Abstract: A method of isolating semiconductor devices including forming a pad layer on a semiconductor substrate, forming a trench by etching the semiconductor substrate to a predetermined depth using the pad layer as an etch barrier, implanting ion impurities into a bottom of the trench so as to increase an oxidation rate thereat, performing heat treatment for activating ion implanted impurities, growing a liner oxide film on a bottom and a sidewall of the trench, forming an isolation film on the liner oxide film so as to fill the trench, and smoothing the isolation film.

Abstract: Method for preventing sneakage in shallow trench isolation and STI structure thereof. A semiconductor substrate having a pad layer and a trench formed thereon is provided, followed by the formation of a doped first lining layer on the sidewall of the trench. A second lining layer is then formed on the doped first lining layer. Etching is then performed to remove parts of the first lining layer and the second lining layer so that the height of the first lining layer is lower than the second lining layer. A sacrificial layer is then formed on the pad layer and filling the trench. Diffusion is then carried out so that the doped ions in the first lining layer out-diffuse to the substrate and form diffuse regions outside the two bottom corners of the trench.

Abstract: The present invention provides a method for eliminating inverse narrow width effects in the fabrication of DRAM devices. A semiconductor substrate is provided having thereon a shallow trench. The shallow trench surrounds an active area. A non-doped silicate glass (NSG) layer is deposited to fill the shallow trench, and is then etched back to a depth of the shallow trench, thereby exposing a portion of the semiconductor substrate at an upper portion of the shallow trench. A doped dielectric layer is deposited over the remaining NSG layer to cover the exposed semiconductor substrate. A thermal process is then carried out to diffuse dopants of the doped dielectric layer into the semiconductor substrate, thereby forming a doped region at the periphery of the active area in a channel width direction.

Abstract: Provided is a technique for fabrication of STIs in a semiconductor device using implantation of damaging high-energy ions to insulating material overburden to generally and/or selectively increase insulation overburden removal rates. This technique avoids the use of chemical mechanical planarization (CMP) with a combination of implantation and, in some instances, low cost batch etching. The electrical characteristics of devices created with the new technique match closely to those fabricated with the standard CMP-based technique.

Abstract: It is an object of the invention to provide a method for manufacturing an IC chip wherein a wafer is prevented from being damaged and the ease of handling thereof is improved so that the wafer can be appropriately processed into IC chips, even if a thickness of the wafer is extremely reduced to approximately 50 ?m.

Abstract: A fabrication method for a shallow trench isolation region is described. A part of the trench is filled with a first insulation layer, followed by performing a surface treatment process to form a surface treated layer on the surface of a part of the first insulation layer. The surface treated layer is then removed, followed by forming a second insulation layer on the first insulation layer and filling the trench to form a shallow trench isolation region. Since a part of the trench is first filled with the first insulation layer, followed by removing a portion of the first insulation layer, the aspect ratio of the trench is lower before the filling of the second insulation in the trench. The adverse result, such as, void formation in the shallow trench isolation region due to a high aspect ratio, is thus prevented.

Abstract: A semiconductor processing method for filling structural gaps includes depositing a substantially boron free silicon oxide comprising material at a first average deposition rate over an exposed semiconductive material in a gap between wordline constructions and at a second average deposition rate less than the first average deposition rate over the wordline constructions. A reduced gap having a second aspect ratio less than or equal to a first aspect ratio of the original gap may be provided. An integrated circuit includes a pair of wordline constructions separated by a gap therebetween in areas where the wordline constructions do not cover an underlying semiconductive substrate. A layer of substantially boron free silicon oxide material has a first thickness over the substrate within the gap and has a second thickness less than the first thickness over the wordline constructions.

Abstract: A method for forming a trench in a semiconductor device is disclosed. An example method forms a pad oxide film and a silicon nitride film on a semiconductor substrate, selectively etches the silicon nitride film and the pad oxide film on a region to be formed with a trench, and implants oxygen ions into the semiconductor substrate in the region to be formed with the trench. The example method also forms an oxide in the semiconductor substrate by reacting the oxygen ions with the semiconductor substrate through a thermal diffusion of the oxygen ions, forms the trench by etching the semiconductor substrate and the oxide on the region to be formed with the trench using the silicon nitride film as a mask, forms a liner oxide film on an inner wall of the trench using a thermal diffusion process, and forms an insulation film on the liner oxide film such that the trench is filled.