Abstract: The present invention provides a method for manufacturing a thin film transistor panel. At first, a gate line is formed on an insulating substrate. A gate insulating layer and a semiconductor layer which comprises an impurity-doped layer are deposited over the gate line sequentially. The semiconductor layer is patterned. A conductive pattern layer with a source electrode, a channel region and a drain electrode is formed over the patterned semiconductor layer. The impurity-doped layer is exposed at the channel region. Then, the impurity-doped layer at the channel region is insulated.

Abstract: An amorphous semiconductor film is etched so that a width of a narrowest portion thereof is 100 &mgr;m or less, thereby forming island semiconductor regions. By irradiating an intense light such as a laser into the island semiconductor regions, photo-annealing is performed to crystallize it. Then, of end portions (peripheral portions) of the island semiconductor regions, at least a portion used to form a channel of a thin film transistor (TFT), or a portion that a gate electrode crosses is etched, so that a region that the distortion is accumulated is removed. By using such semiconductor regions, a TFT is produced.

Abstract: In a semiconductor device, typically an active matrix display device, the structure of TFTs arranged in the respective circuits are made suitable in accordance with the function of the circuit, and along with improving the operating characteristics and the reliability of the semiconductor device, the manufacturing cost is reduced and the yield is increased by reducing the number of process steps.

Abstract: The light emitting device according to the present invention is characterized in that a gate electrode comprising plurality of conductive films is formed, and concentration of impurity regions in an active layer are adjusted with making use of selectivity of the conductive films in etching and using them as masks. The present invention reduces the number of photolithography steps in relation to manufacturing the TFT for improving yield of the light emitting device and shortening manufacturing term thereof, by which a light emitting device and an electronic appliance are inexpensively provided.

Abstract: The invention provides a method of manufacturing an electronic device including a vertical thin film transistor. A layer (8) of semiconductor material is provided over an insulated gate electrode (2). A negative resist (14) is used to define source and drain electrodes (26,28) which extend over the insulating layer (8) up to the step formed therein adjacent an edge (16A) of the gate electrode (2).

Abstract: A method for fabricating a thin film transistor array and driving circuit comprising the steps of: providing a substrate; patterning a polysilicon layer and an N+ thin film over the substrate to form a plurality of islands; patterning the islands to form P+ doped regions; patterning out source/drain terminals and the lower electrode of a storage capacitor; etching back the N+ thin film; patterning out a gate and the upper electrode of the storage capacitor and patterning a passivation layer and a conductive layer to form pixel electrodes and a wiring layout.

Abstract: In a thin film transistor, a first insulating film on a silicon layer formed in an island on a substrate is smaller in thickness than the silicon layer so that the stepped island edges is gentle in slope to facilitate covering the island with a second insulating film. This reduces occurrence of gate leak considerably. Since the peripheral region of the stepped island is smaller in thickness than the central region above the channel, it is possible to minimize occurrence of gate electrode breakage. The silicon layer contains two or more inert gas atoms, and the atoms smaller in mass number (e.g., He) are contained in and near an interface with a silicon active layer while the atoms larger in mass number (e.g., Ar) than those smaller in mass number are contained in and near a second interface with a gate electrode.

Abstract: A method of forming an oxide film and a method of manufacturing an electronic device utilizing the oxide film is disclosed. A silicon oxide film is formed on a substrate by sputtering. Therefore, the film formation is carried out at a low temperature. The sputtering atmosphere comprises an oxidizing gas and an inert gas such as argon. In order to prevent fixed electric charges from being generated in the film and to obtain an oxide film of good properties, the proportion of argon is adjusted to 20% or less. Alternatively, a gas including halogen elements such as fluorine is added to the above sputtering atmosphere at a proportion less than 20%. Hereupon, alkali ions and dangling bonds of silicon in the oxide film are neutralized by the halogen elements, whereby a fine oxide film is obtained.

Abstract: A method of manufacturing a semiconductor device may include forming a fin structure on an insulator and forming a gate structure over a channel portion of the fin structure. The method may also include forming a sacrificial oxide layer around the gate structure and removing the gate structure to define a gate recess within the sacrificial oxide layer. A metal gate may be formed in the gate recess, and the sacrificial oxide layer may be removed.

Abstract: An object of the present invention is to crystallize and activate the doped amorphous semiconductor layer at the same time. It is also an object to provide the TFT with good electrical connection between the source or drain electrodes and the semiconductor layer.

Abstract: In a bottom gate type semiconductor device made of a semiconductor layer with crystal structure, source/drain regions are constructed by a lamination layer structure including a first conductive layer (n+ layer), a second conductive layer (n− layer) having resistance higher than the first conductive layer, and an intrinsic or substantially intrinsic semiconductor layer (i layer). At this time, the n− layer acts as LDD region, and the i layer acts as an offset region is a film thickness direction.

Abstract: A silicon oxynitride film is manufactured using SiH4, N2O and H2 by plasma CVD, and it is applied to the gate insulating film (1004 in FIG. 1A) of a TFT. The characteristics of the silicon oxynitride film are controlled chiefly by changing the flow rates of N2O and H2. A hydrogen concentration and a nitrogen concentration in the film can be increased by the increase of the flow rate of H2. Besides, the hydrogen concentration and the nitrogen concentration in the film can be decreased to heighten an oxygen concentration by the increase of the flow rate of N2O. The gate insulating film ensures the stability and reliability of the characteristics of the TFT, such as the threshold voltage (Vth) and sub-threshold constant (S value) thereof.

Abstract: A semiconductor substrate, for forming a circuit pattern of a semiconductor chip, comprised of a substrate, an insulating film formed on the substrate, and a semiconductor layer formed on the insulating film, wherein the semiconductor layer is isolated by the insulating film for every region formed with a circuit pattern of a semiconductor chip, able to be generally used even if a silicon on insulator or semiconductor on insulator (SOI) layer is isolated by an insulating film, and a process of production of an SOI substrate, enabling a reduction of thickness of the SOI layer and able to suppress the manufacturing costs and variation in the thickness of the SOI layer, comprising forming a groove in a first substrate made of a semiconductor, forming a first insulating film in the groove and on the first substrate, injecting hydrogen ions to form a peeling layer, bonding a second substrate, peeling off the first substrate by heat treatment while leaving the semiconductor layer, and polishing the semiconductor la

Abstract: A method of producing a top gate thin-film transistor comprises the steps of forming doped silicon source and drain regions (6a,8a) on an insulating substrate (2) and subjecting the face of the substrate (2) on which the source and drain regions (6a,8a) are formed to plasma treatment to form a doped surface layer. An amorphous silicon layer (12) is formed on the doped surface layer over at least the spacing between the source and drain regions (6a,8a) and an insulated gate structure (14, 16) is formed over the amorphous silicon layer (12). Laser annealing of areas of the amorphous silicon layer not shielded by the gate conductor is carried out to form polysilicon portions (12a, 12b) having the impurities diffused therein. In the method of the invention, doped silicon source and drain regions underlie the silicon layer to be crystallized using the laser annealing process. It has been found that the laser annealing process can then result in crystallization of the full thickness of the amorphous silicon layer.

Abstract: After a polysilicon semiconductor film 5 and a first gate oxide film 6 are formed on a transparent insulating substrate 1, the semiconductor film 5 and the first gate oxide film 6 are patterned into an island shape to form an island part. At this time, an overhang part 8 of a visor shape is formed where side end surfaces of the first gate oxide film 6 and the semiconductor film 5 are not aligned and an end part of the first gate oxide film 6 projects slightly from a position of a side end surface of the semiconductor film 5. The overhang part 8 is removed, for example, during cleaning, which thus enhances yield.

Abstract: The benefits of strained semiconductors are combined with silicon-on-insulator approaches to substrate and device fabrication.

Abstract: In a method of fabricating a thin film transistor array substrate, an aluminum-based conductive layer is deposited onto an insulating substrate, and patterned to form a gate line assembly. The gate line assembly includes gate lines, gate electrodes, and gate pads. A gate insulating layer is formed on the substrate with the gate line assembly. A semiconductor layer, and an ohmic contact layer are sequentially formed on the gate insulating layer. A double-layered conductive film with a chrome-based under-layer and an aluminum-based over-layer is deposited onto the substrate, and patterned to form a data line assembly. The data line assembly includes data lines crossing over the gate lines, source electrodes, drain electrodes, and data pads. The chrome-based under-layer of the conductive film is patterned through dry etching while using Cl2 or HCl as the dry etching gas.

Abstract: A method for making transistors comprises depositing source electrode and drain electrode features onto a substrate through a single aperture in a stationary shadow mask, said aperture having at least two opposing edges; wherein the shapes of the features are defined by the aperture and location of source materials in relation to the substrate.

Abstract: The present invention provides a device design and method for forming Field Effect Transistors (FETs) that have improved performance without negative impacts to device density. The present invention forms high-gain p-channel transistors by forming them on silicon islands where hole mobility has been increased. The hole mobility is increased by applying physical straining to the silicon islands. By straining the silicon islands, the hole mobility is increased resulting in increased device gain. This is accomplished without requiring an increase in the size of the devices, or the size of the contacts to the devices.

Abstract: An SOI substrate includes a diffusion barrier layer, the layer thickness and composition of which is selected so as to substantially prevent copper atoms and ions from diffusing through the diffusion barrier layer. The diffusion barrier layer is located to substantially reduce the deleterious effect of copper that may be introduced into a semiconductor device from the back side of the substrate during various manufacturing stages of the semiconductor device. In one particular example, a silicon wafer with a silicon nitride layer as a diffusion barrier layer and a silicon wafer with an oxide layer is bonded. After separation, an SOI substrate is obtained that has superior characteristics with respect to resistance against copper back side diffusion.

Abstract: A method of manufacturing a semiconductor device is provided which uses a laser crystallization method capable of increasing substrate processing efficiency. An island-like semiconductor film including one or more islands is formed by patterning (sub-island). The sub-island is then irradiated with laser light to improve its crystallinity, and thereafter patterned to form an island. From pattern information of a sub-island, a laser light scanning path on a substrate is determined such that at least the sub-island is irradiated with laser light. In other words, the present invention runs laser light so as to obtain at least the minimum degree of crystallization of a portion that has to be crystallized, instead of irradiating the entire substrate with laser light.

Abstract: A method of forming a semiconductor device wherein treatment gate insulating layer is formed such that its edges extend beyond edges of a gate electrode. Specifically, the method includes the steps of forming a non-single crystalline semiconductor layer on an insulating surface, forming a gate electrode on the semiconductor layer with a gate insulating layer formed therebetween, doping portions of the semiconductor layer with an impurity to form source and drain regions, and exposing the doped portions with light to crystallize the portions and activate the dopant. Since the gate electrode extends beyond the edges of the gate electrode, the doping of the portions of the semiconductor layer and the exposure to light irradiation is carried out through a part of the gate insulating layer.

Abstract: An object of the present invention is to form a channel formation region, or a TFT formation region, using one crystal aggregate (domain) by controlling crystal location and size, thus suppressing TFT variations. According to the present invention, laser irradiation is performed selectively on an amorphous silicon film in the periphery of a channel formation region, or the periphery of a TFT formation region containing a channel formation region, source and drain region, and the like. Each TFT formation region is isolated, a metallic element for promoting crystallization (typically Ni) is added, and heat treatment is performed, thus making it possible to arbitrarily determine the locations of crystal aggregates (domains). It becomes possible to suppress variations in the TFTs by arbitrarily controlling the crystal aggregate (domain) locations.

Abstract: Wafers of the present invention comprise a semiconductor layer and a dielectric layer. The semiconductor layer is patterned to form semiconductor regions, and the dielectric layer is deposited on top of the semiconductor layer. Chemical mechanical planarization (CMP) is performed to remove a portion of the dielectric layer, exposing the upper surfaces of the semiconductor regions. The amount of CMP necessary to expose all of the semiconductor regions on the wafer is reduced, because the dielectric is targeted to deposit up to the upper edge of the semiconductor regions in the spaces in between the semiconductor regions. This technique reduces non-uniformities in the thickness of the dielectric and semiconductor layers across the wafer. The thickness of the dielectric or semiconductor layer deposited on polish monitor pads located at the edges of each die may be monitored to determine when enough CMP has been performed to expose each of the semiconductor regions.

Abstract: A method and semiconductor structure including silicon-on-insulator (SOI) devices are provided for implementing reach through buried interconnect. A semiconductor stack includes a predefined buried conductor to be connected through multiple insulator layers and at least one intermediate conductor above the predefined buried conductor. A hole is anisotropically etched through the semiconductor stack to the predefined buried conductor. The etched hole extends through the at least one intermediate conductor and the insulators to the predefined buried conductor in the semiconductor stack. A thin layer of insulator is deposited over an interior of the etched hole. The deposited thin insulator layer is anisotropically etched to remove the deposited thin insulator layer from a bottom of the hole exposing the predefined buried conductor in the semiconductor stack with the thin insulator layer covering sidewalls of the hole to define an insulated opening.

Abstract: A method for is provided forming a thin-film transistor (TFT) on a flexible substrate. The method comprises: supplying a metal foil substrate such as titanium (Ti), Inconel alloy, stainless steel, or Kovar, having a thickness in the range of 10 to 500 microns; depositing and annealing amorphous silicon to form polycrystalline silicon; and, thermally growing a gate insulation film overlying the polycrystalline. The silicon annealing process can be conducted at a temperature greater than 700 degrees C. using a solid-phase crystallization (SPC) annealing process. Thermally growing a gate insulation film includes: forming a polycrystalline silicon layer having a thickness in the range of 10 to 100 nanometers (nm); and, thermally oxidizing the film at temperature in the range of 900 to 1150 degrees for a period of time in the range of 2 to 60 minutes. Alternately, a plasma oxide layer is deposited over a thinner thermally oxidized layer.

Abstract: The present invention thus provides a device structure and method for forming fin Field Effect Transistors (FETs) that overcomes many of the disadvantages of the prior art. Specifically, the device structure and method provides the ability to form finFET devices from bulk semiconductor wafers while providing improved wafer to wafer device uniformity. Specifically, the method facilitates the formation of finFET devices from bulk semiconductor wafers with improved fin height control. Additionally, the method provides the ability to form finFETs from bulk semiconductor while providing isolation between fins and between the source and drain region of individual finFETs. Finally, the method can also provide for the optimization of fin width. The device structure and methods of the present invention thus provide the advantages of uniform finFET fabrication while using cost effect bulk wafers.

Abstract: Method of fabricating a semiconductor circuit is initiated with formation of an amorphous silicon film. Then, a second layer containing at least one catalytic element is so formed as to be in intimate contact with the amorphous silicon film, or the catalytic element is introduced into the amorphous silicon film. This amorphous silicon film is selectively irradiated with laser light or other equivalent intense light to crystallize the amorphous silicon film.

Abstract: In an inverted stagger type thin-film transistor, the preparing process thereof can be simplified, and the unevenness of the thin film transistor prepared thereby can be reduced. That is, disclosed is a preparing method which comprises selectively doping a semiconductor on a gate insulating film with an impurity to form source, drain, and channel forming regions, and conducting a laser annealing to them, or a preparing method which comprises selectively doping the semiconductor region with an impurity by a laser doping method.

Abstract: A method of forming a thin film transistor (TFT) on a plastic sheet. An etching stop layer is formed on a glass substrate. A buffer layer is formed on the etching stop layer. At least one TFT structure is formed on part of the buffer layer. A passivation layer is formed on the TFT structure and the buffer layer. A plastic layer is formed on the passivation layer. The glass substrate and the etching stop layer are removed. Thus, the invention can transfer the TFT structure from the glass plate to the plastic sheet without damage from the process temperature of the TFT.

Abstract: There is provided an active matrix type semiconductor display device which realizes low power consumption and high reliability. In the active matrix type semiconductor display device of the present invention, a counter electrode is divided into two, different potentials are applied to the two counter electrodes, respectively and inversion driving is carried out each other. Since a potential of an image signal can be made low by doing so, it is possible to lower a voltage necessary for operation of a driver circuit. As a result, it is possible to realize improvement of reliability of an element such as a TFT and reduction of consumed electric power. Moreover, since it is possible to lower a voltage of a timing pulse supplied by the driver circuit, a booster circuit can be omitted, and reduction of an area of the driver circuit can be realized.

Abstract: The present invention provides a device design and method for forming Field Effect Transistors (FETs) that have improved performance without negative impacts to device density. The present invention forms high-gain p-channel transistors by forming them on silicon islands where hole mobility has been increased. The hole mobility is increased by applying physical straining to the silicon islands. By straining the silicon islands, the hole mobility is increased resulting in increased device gain. This is accomplished without requiring an increase in the size of the devices, or the size of the contacts to the devices.

Abstract: A structure and method of forming a fully planarized polymer thin-film transistor by using a first planar carrier to process a first portion of the device including gate, source, drain and body elements. Preferably, the thin-film transistors made with all organic materials. The gate dielectric can be a high-k polymer to boost the device performance. Then, the partially-finished device structures are flipped upside-down and transferred to a second planar carrier. A layer of wax or photo-sensitive organic material is then applied, and can be used as the temporary glue. The device, including its body area, is then defined by an etching process. Contacts to the devices are formed by conductive material deposition and chemical-mechanical polish.

Abstract: A method of manufacturing a flat panel display device using fewer masks and resulting in a device with high brightness is disclosed. The resulting devices includes at least first to fourth thin film transistors, the first, third, and fourth thin film transistors having a first conductive type, and the second thin film transistors having a second conductive type.

Abstract: A method for fabricating a monolithically integrated liquid crystal array display and control circuitry on a silicon-on-sapphire structure comprises the steps of: a) forming an epitaxial silicon layer on a sapphire substrate to create a silicon-on-sapphire structure; b) ion implanting the epitaxial silicon layer; c) annealing the silicon-on sapphire structure; d) oxidizing the epitaxial silicon layer to form a silicon dioxide layer from portion of the epitaxial silicon layer so that a thinned epitaxial silicon layer remains; e) removing the silicon dioxide layer to expose the thinned epitaxial silicon layer; f) fabricating an array of pixels from the thinned epitaxial silicon layer; and g) fabricating integrated circuitry from the thinned epitaxial silicon layer which is operably coupled to modulate the pixels. The thinned epitaxial silicon supports the fabrication of device quality circuitry which is used to control the operation of the pixels.

Abstract: A process for fabricating a thin film transistor, which comprises crystallizing an amorphous silicon film, forming thereon a gate insulating film and a gate electrode, implanting impurities in a self-aligned manner, adhering a coating containing a catalyst element which accelerates the crystallization of the silicon film, and annealing the resulting structure at a temperature lower than the deformation temperature of the substrate to activate the doped impurities. Otherwise, the catalyst element can be incorporated into the structure by introducing it into the impurity region by means of ion implantation and the like.

Abstract: An object of the present invention is to crystallize and activate the doped amorphous semiconductor layer at the same time. It is also an object to provide the TFT with good electrical connection between the source or drain electrodes and the semiconductor layer.

Abstract: By applying ion or optical energy or catalytic effects at the time of depositing a crystalline silicon thin film, improvements in crystallinity of the crystalline silicon thin film in proximities of an interface of a substrate or smoothing of its surface may be achieved. With this arrangement, it is possible to achieve improvements in crystallinity of the crystalline silicon film that is formed in a low temperature condition through CVD method and to prevent concaves and convexes from being formed on its surface or to prevent oxidation of grain fields, and it is accordingly possible to provide a thin film transistor, a semiconductor device such as a solar cell and methods for manufacturing these that exhibit superior characteristics and reliability.

Abstract: A data holding control signal for each data line is supplied to a plurality of source followers that are connected together in parallel. The parallel-connected source followers are a combination of at least one first follower that is illuminated with laser light only once and at least one second follower that is illuminated twice. A width of the laser light illumination for crystallization is equal to a pitch of the source followers multiplied by an integer that is not less than 3.

Abstract: An Insulated Gate Field Effect Transistor (IGFET), fabricated using Shallow Trench Isolation (STI), has an edge of a channel region of the IGFET which has a curved shape with a controlled radius of curvature so as to reduce the electric field at the edge of the channel region. A method of controlling the shape of the edge of the channel region is to limit the supply of oxygen to the region at the edge of the channel region during the oxidation process when the side walls of the silicon island, in which the transistor will be formed, are initially covered with a layer of silicon oxide.

Abstract: In a monolithic active matrix circuit that uses offset-gate TFTs in which the gate electrode is offset from the source and drain regions or TFTs whose gate insulating film is formed by vapor deposition, not only an active matrix circuit but also a drive circuit therefor is formed by using P-channel TFTs.

Abstract: A method of forming a field effect transistor includes forming a channel region within bulk semiconductive material of a semiconductor substrate. Source/drain regions are formed on opposing sides of the channel region. An insulative dielectric region is formed within the bulk semiconductive material proximately beneath at least one of the source/drain regions. A method of forming a field effect transistor includes providing a semiconductor-on-insulator substrate, said substrate comprising a layer of semiconductive material formed over a layer of insulative material. All of a portion of the semiconductive material layer and all of the insulative material layer directly beneath the portion are removed thereby creating a void in the semiconductive material layer and the insulative material layer. Semiconductive channel material is formed within the void. Opposing source/drain regions are provided laterally proximate the channel material. A gate is formed over the channel material.

Abstract: TFT structures optimal for driving conditions of a pixel portion and driving circuits are obtained using a small number of photo masks. First through third semiconductor films are formed on a first insulating film. First shape first, second, and third electrodes are formed on the first through third semiconductor films. The first shape first, second, third electrodes are used as masks in first doping treatment to form first concentration impurity regions of one conductivity type in the first through third semiconductor films. Second shape first, second, and third electrodes are formed from the first shape first, second, and third electrodes. A second concentration impurity region of the one conductivity type which overlaps the second shape second electrode is formed in the second semiconductor film in second doping treatment. Also formed in the second doping treatment are third concentration impurity regions of the one conductivity type which are placed in the first and second semiconductor films.

Abstract: A semiconductor device and a method for forming the same. The semiconductor device comprises an insulating or semiconductor substrate, a thermally-contractive insulating film which is formed on said substrate and provided with grooves, and a semiconductor film which is formed on the thermally-contractive insulating film and divided in an islandish form through the grooves. The thermally-contractive insulating film is contracted in a heat process after the semiconductor film is formed.

Abstract: A thin film transistor of reversed stagger type having improved characteristics and yet obtained by a simple process, which is fabricated by selectively doping the semiconductor region on the gate dielectric to form the source, drain, and channel forming regions by using ion implantation, ion doping, or doping a plasma of ions; and then effecting rapid thermal annealing by irradiating a ultraviolet radiation, a visible light, or a near-infrared radiation for a short period of time. The source, drain, and channel forming regions are formed substantially within a single plane.

Abstract: A silicon on insulator (SOI) semiconductor device is provided having a semiconductor substrate with an inverted region, an insulator, and a silicon island. The device combines the inverted region with channel doping to fully deplete the silicon island of majority carriers when the device is in the off state and both of its junctions are at ground.

Abstract: A double-gate field effect transistor (DGFET) is provided using a damascene-like replacement gate processing step to create sidewall source/drain regions, oxide spacers and gate structures inside a previously formed trench. The damascene-like replacement gate processing step allows for the fabrication of a tapered transistor body region having a thicker body under the contacts which reduces access resistance.

Abstract: There is provided a semiconductor apparatus, and a fabrication method thereof, which are improved such that a reduction in concentration at the SOI active layer is prevented, and a parasitic MOSFET is not formed even in cases where Mesa-type isolation techniques and the STI isolation method are applied to form a MOSFET in an SOI layer. In an isolation step for separating and forming a plurality of device regions, a layered film of a nitride film (Si3N4) and an oxide film (SiO2) is taken as an isolation mask, and a semiconductor layer (SOI layer) is removed from the isolation region by etching. Subsequently, a SiON film (7) is formed on a sidewall surface of an SOI layer (3) by a nitridation oxidation process. Thereafter, isolation is performed by the STI method. Finally, an oxide film (9) and an electrode (10) are formed, and a MOSFET is completed.

Abstract: To provide a semiconductor device having high mass production performance and high reliability and reproducibility by simple fabrication steps, in a constitution of a semiconductor device of a bottom gate type formed by a semiconductor layer having a crystal structure, source and drain regions are constituted by a laminated layer structure comprising a first conductive layer (n+ layer), a second conductive layer (n− layer) having resistance higher than the first conductive layer and an intrinsic or a substantially intrinsic semiconductor layer (i layer) in which the n− layer functions as an LDD region and the i layer functions as an offset region in a film thickness direction.

Abstract: A TFT formed on an insulating substrate source, drain and channel regions, a gate insulating film formed on at least the channel region and a gate electrode formed on the gate insulating film. Between the channel region and the drain region, a region having a higher resistivity is provided in order to reduce an Ioff current. A method for forming this structure comprises the steps of anodizing the gate electrode to form a porous anodic oxide film on the side of the gate electrode; removing a portion of the gate insulating using the porous anodic oxide film as a mask so that the gate insulating film extends beyond the gate electrode but does not completely cover the source and drain regions. Thereafter, an ion doping of one conductivity element is performed. The high resistivity region is defined under the gate insulating film.