JP2004327977A - Thin film transistor and method for manufacturing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for manufacturing a thin film transistor for realizing a heating process for improving the characteristics of a gate insulating film, such as reduction in the boundary surface level and reduction in the fixed charges, while preventing a problem of the alignment deviation in patterning due to expansion and contraction of glass. <P>SOLUTION: In the method for manufacturing a thin film transistor, a heating process is carried out in a state in which at least a gate insulating film is formed on an element unisolated semiconductor film; the gate insulating film and the semiconductor film are isolated into an element structure at the same time; an insulating film that covers the side of the exposed semiconductor film is formed; and thus a short-circuit between the semiconductor film and the gate electrode is prevented. Since the gate insulating film and the semiconductor film are simultaneously machined into an element shape after the heating process, the expansion and contraction of a glass substrate does not exert influence on the alignment deviation in patterning. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a semiconductor element typified by a field-effect transistor formed on a substrate having a low strain point, a method for manufacturing the same, a semiconductor integrated circuit including the semiconductor element, and a method for manufacturing the same, particularly, a strain point of a substrate such as glass. The present invention relates to a thin film transistor for performing a heat treatment on a gate insulating film at a temperature exceeding 300 ° C. and a method for manufacturing the same.

  In recent years, attention has been paid to the development of a system-on-panel in which logic circuits such as a CPU and a memory are incorporated in addition to pixels and a driving circuit on an insulating substrate that transmits light such as glass or quartz. A high-speed operation is required for a driver circuit and a logic circuit, and a thin film transistor (hereinafter, also referred to as a TFT) having a high switching speed is required to realize the operation. In order to increase the switching speed of a TFT, it is effective to use a semiconductor film with few crystal defects as an active layer, to reduce the thickness of a gate insulating film, and to reduce a transistor size represented by a reduction in gate length.

The characteristics required for the gate insulating film include few defects in the thin film, no fixed charge, low interface state with the semiconductor film, low leakage current, and the like. However, the gate leak current tends to increase as the thickness of the gate insulating film decreases. In order to reduce the thickness of the gate insulating film, a dense gate insulating film capable of suppressing a gate leak current is required. When the gate insulating film is thinned, low-voltage driving can be performed, and a field-effect semiconductor device with high response even at a high driving frequency can be obtained (for example, see Patent Document 1).
JP-A-6-188421

  When a silicon film is formed on a transparent insulating substrate such as glass and an integrated circuit is manufactured using the silicon film, the manufacturing technology cultivated in a large-scale integrated circuit using a single crystal silicon substrate cannot be diverted as it is. It was impossible. This is not only due to the problem of crystallinity of a silicon film (such as a polycrystalline silicon film) for fabricating an integrated circuit, but also because of the heat resistance of glass or the like as a substrate on which the integrated circuit is formed, the process temperature is limited. It was to get it.

  Although a gate insulating film that is dense and excellent in electrical suitability can be formed by a CVD method, the film forming temperature must be 750 ° C. or higher. Although the plasma CVD method can form a film at a low temperature, there is a problem that the film is damaged by charged particles in the plasma and defects and pinholes are easily formed. When the film formation temperature is 500 ° C. or lower, hydrogen is contained in the film, and the stability of the film is reduced. On the other hand, the high frequency sputtering method can form a thin film free of hydrogen. However, compared to the CVD method, a high-frequency sputtering method could not generally provide a dense film to be used as a gate insulating film.

  In order to manufacture a TFT having a high switching speed, which is indispensable as an element for a logic operation circuit, and to achieve high integration, miniaturization of element dimensions is increasingly required. For that purpose, it is essential to form a high-quality gate insulating film. In order to form a high-quality gate insulating film, it is desired to heat the formed gate insulating film. However, before and after applying a temperature exceeding the strain point, a substrate such as glass that expands and contracts has a problem that misalignment occurs when patterning a film formed on the substrate. It is difficult to perform heat treatment on the gate insulating film at a temperature higher than the strain point of the substrate.

  In general, a process of manufacturing a TFT over a glass substrate will be described with reference to FIGS. 7E to 7H are top views, and FIGS. 7A to 7D are cross-sectional views taken along broken lines AB and BC in the top views, respectively. FIG. 7 particularly describes steps from semiconductor film formation and element isolation to gate electrode fabrication.

  First, a base film 11 and a semiconductor film 12 are formed on an insulating substrate 10 (FIGS. 7A and 7E). Next, the semiconductor film 12 is processed into an island shape to separate elements into a transistor formation region 13 and a transistor formation region 14 (FIGS. 7B and 7F). Subsequently, a gate insulating film 15 and a conductive film 16 are formed (FIGS. 7C and 7G). Finally, the conductive film 16 is patterned to form a gate electrode 18 (FIGS. 7D and 7H). Note that a region of the gate insulating film 15 that does not overlap with the gate electrode 18 is etched by etching when the gate electrode 18 is formed, so that the gate insulating film 17 is formed.

  As described above, after the semiconductor film 12 is separated into islands, the gate insulating film 15 and the conductive film 16 are formed. Thereafter, the position of the gate electrode 18 is changed to an island-like semiconductor film, that is, the transistor formation region 13. , 14, the conductive film 16 is patterned to form a transistor. In this method, the upper limit of the process temperature after the semiconductor film 12 is processed into the island shape is determined in consideration of the amount of shrink of the substrate so as not to cause a defect due to misalignment during patterning.

  The present invention provides a thin film transistor capable of performing a heat treatment for the purpose of improving characteristics of a gate insulating film such as reduction of interface states and reduction of fixed charges without causing a problem of misalignment of patterning due to expansion and contraction of a substrate such as glass. And a method for manufacturing the same.

  The present invention provides an island-shaped semiconductor film and an island-shaped gate insulating film patterned using the same photomask on an insulating substrate, and a side surface formed of an insulating material formed on a side surface of the island-shaped semiconductor film. A gate electrode formed on the island-shaped gate insulating film, wherein the gate electrode overlaps a side surface of the island-shaped semiconductor film via the sidewall. It is a thin film transistor.

  The present invention provides an island-shaped semiconductor film and an island-shaped gate insulating film which are patterned by using the same photomask on an insulating substrate; and the side surfaces of the island-shaped semiconductor film and the island-shaped gate insulating film. A sidewall formed of an insulating material and a gate electrode formed on the island-shaped gate insulating film, wherein the gate electrode has a side surface of the island-shaped semiconductor film via the sidewall. This is a thin film transistor characterized by being overlapped.

  The present invention has an island-shaped semiconductor film and an island-shaped gate insulating film patterned using the same photomask on an insulating surface, and a gate electrode formed on the island-shaped gate insulating film. A side surface of the island-shaped semiconductor film is insulated, and the gate electrode overlaps a side surface of the insulated island-shaped semiconductor film.

  The present invention is directed to an island-shaped semiconductor film and an island-shaped gate insulating film patterned using the same photomask on an insulating substrate, and side surfaces of the island-shaped semiconductor film and the island-shaped gate insulating film. An insulating film patterned so as to cover only a peripheral portion of the upper surface of the island-shaped gate insulating film, and a gate electrode formed on the island-shaped gate insulating film, wherein the gate electrode is An insulating film patterned to cover only the side surface of the island-shaped semiconductor film and the island-shaped gate insulating film and a peripheral portion of the upper surface of the island-shaped gate insulating film; A thin film transistor overlapped with a side surface.

  The present invention forms a semiconductor film over an insulating substrate, forms a first insulating film over the semiconductor film, heat-treats the semiconductor film and the first insulating film, and after the heat treatment, Patterning the semiconductor film and the first insulating film into islands using the same photomask to form an island-shaped semiconductor film and an island-shaped gate insulating film; A second insulating film is formed thereon, and the second insulating film is anisotropically etched to self-align sidewalls covering the side surfaces of the island-shaped semiconductor film and the island-shaped gate insulating film. Forming a conductive film on the island-shaped gate insulating film, patterning the conductive film to form a gate electrode, and forming the gate electrode. Is the way.

  The present invention forms a semiconductor film over an insulating substrate, forms an insulating film over the semiconductor film, heat-treats the semiconductor film and the insulating film, and uses the same resist mask after the heat treatment. Patterning the semiconductor film and the insulating film in an island shape to form an island-shaped semiconductor film and an island-shaped gate insulating film, and removing the resist mask without removing the resist mask. Adding oxygen or nitrogen to the side surface to insulate the side surface of the semiconductor film, forming a conductive film on the island-shaped gate insulating film, and patterning the conductive film to form a gate electrode This is a method for manufacturing a thin film transistor.

  The present invention forms a semiconductor film over an insulating substrate, forms a first insulating film over the semiconductor film, heat-treats the semiconductor film and the first insulating film, and after the heat treatment, Patterning the semiconductor film and the first insulating film into islands using the same photomask to form an island-shaped semiconductor film and an island-shaped gate insulating film; A second insulating film is formed thereon, and the second insulating film is formed so as to cover only the end portions of the island-shaped semiconductor film and the island-shaped gate insulating film and the peripheral portion of the upper surface of the island-shaped gate insulating film. 2. A method of manufacturing a thin film transistor, comprising: patterning the insulating film of No. 2; thereafter, forming a conductive film on the island-shaped gate insulating film, and patterning the conductive film to form a gate electrode. .

  According to the present invention, a semiconductor film is formed over an insulating substrate; a first insulating film is formed over the semiconductor film; a first conductive film is formed over the first insulating film; The first insulating film and the first conductive film are subjected to heat treatment, and after the heat treatment, the semiconductor film, the first insulating film, and the first conductive film are formed using the same photomask. The film is patterned into an island shape to form an island-shaped semiconductor film, an island-shaped gate insulating film, and an island-shaped first conductive film, and a second film is formed on the island-shaped first conductive film. A second insulating film, and anisotropically etching the second insulating film to form a side surface of the island-shaped semiconductor film, a side surface of the island-shaped gate insulating film, and the island-shaped first conductive film. A sidewall covering the side surface of the film is formed in a self-aligning manner, and after forming the sidewall, a second conductive film is formed on the island-shaped first conductive film. Sex film is formed, a manufacturing method of a thin film transistor and forming the island-shaped first conductive film and the second conductive film is patterned gate electrode.

  According to the present invention, a semiconductor film is formed over an insulating substrate, an insulating film is formed over the semiconductor film, a first conductive film is formed over the insulating film, and the semiconductor film, the insulating film, and the Heat-treating the first conductive film and, after the heat treatment, patterning the semiconductor film, the insulating film, and the first conductive film into islands using the same resist mask; Forming an island-shaped semiconductor film, an island-shaped gate insulating film, and an island-shaped first conductive film, and adding oxygen or nitrogen to a side surface of the island-shaped semiconductor film without removing the resist mask. A side surface of the semiconductor film is insulated, and thereafter, a second conductive film is formed on the island-shaped first conductive film, and the island-shaped first conductive film and the second conductive film are formed. Forming a gate electrode by patterning a conductive film.

  According to the present invention, a semiconductor film is formed on an insulating substrate, a first insulating film is formed on the semiconductor film, and a first conductive film is formed on the insulating film. Heat treatment is performed on the insulating film and the first conductive film, and after the heat treatment, the semiconductor film, the first insulating film, and the first conductive film are separated using the same photomask. An island-shaped semiconductor film, an island-shaped gate insulating film, and an island-shaped first conductive film are formed by patterning in an island shape, and a second insulating film is formed on the island-shaped first conductive film. A film is formed, and only the end portions of the island-shaped semiconductor film, the island-shaped gate insulating film, the island-shaped first conductive film, and the peripheral portion of the upper surface of the island-shaped first conductive film Patterning the second insulating film so as to cover the first conductive film, and then forming a second conductive film on the island-shaped gate insulating film, And a method for manufacturing a thin film transistor and forming the second conductive film is patterned gate electrode.

  In the method for manufacturing a thin film transistor of the present invention, a heat treatment is performed in a state where at least a gate insulating film is formed over a semiconductor film which has not been subjected to element isolation. An element structure is separated using a mask, an insulating film covering side surfaces of the exposed semiconductor film is formed, and then a gate electrode is formed over the gate insulating film. Since the gate insulating film and the semiconductor film are simultaneously patterned after the heat treatment and processed into an element shape, expansion and contraction of a substrate such as glass during the heat treatment can be prevented from affecting alignment deviation in patterning. In a state where the gate insulating film and the semiconductor film are simultaneously patterned and processed into an element shape, the side surfaces of the semiconductor film are exposed. Therefore, before forming an electrode such as a gate electrode or a wiring on the gate insulating film, an insulating film covering a side surface of the semiconductor film is formed. Thus, a short circuit between the semiconductor film processed into an element structure and an electrode or a wiring formed over the gate insulating film is prevented.

  In the present invention, any kind of insulating substrate on which a thin film transistor is formed is effective when a substrate having a strain point lower than a heat treatment temperature of 600 to 800 ° C. applied to a gate insulating film is used.

  In the present invention, a heat treatment is simultaneously performed on a stacked film of a semiconductor film and a gate insulating film which have not been subjected to element isolation. In the heat treatment, furnace or RTA (Rapid Thermal Anneal) may be used. In the RTA treatment, either gas heating or lamp heating can be used. Preferably, lamp heat treatment is performed on the stacked film in a state where a conductive film for forming at least a part of the gate electrode is formed. When a halogen lamp having an emission spectrum peak in the infrared region is used, the conductive film effectively absorbs the radiated light and not only can efficiently heat the gate insulating film, but also the gate insulating film and the conductive film. Can also be subjected to heat treatment, thereby improving characteristics such as a reduction in leakage current caused by the interface between the gate electrode and the gate insulating film.

  When a stacked film including a semiconductor film and a gate insulating film is simultaneously subjected to element isolation, a side surface of the semiconductor film is exposed. Therefore, when a conductive film for forming a gate electrode is subsequently formed, a side surface of the semiconductor film is short-circuited with the gate electrode. In particular, a portion where the gate electrode is routed outside the semiconductor film from which the element is separated and the side surface of the semiconductor film are short-circuited. Therefore, an insulating film that covers the side surface of the semiconductor film is required. The insulating film covering the side surface of the semiconductor film is formed by forming an insulating film covering the entire surface of the substrate over the patterned semiconductor film and the gate insulating film, anisotropically etching the insulating film, and forming a sidewall in a self-aligned manner. It can be formed by processing. Further, as another method for manufacturing the insulating film covering the side surface of the semiconductor film, a method of insulating the side surface of the semiconductor film at a low temperature, or a method of forming only the side surface of the semiconductor film and the gate insulating film and the peripheral portion of the upper surface of the gate insulating film only. There is a method of patterning and forming an insulating film so as to cover the insulating film. In view of the integration, the insulating film covering the side surface of the semiconductor film can be formed with high accuracy because there is no misalignment when formed in a self-aligned manner. It is preferable to manufacture it by a method of insulating the semiconductor side surface at a low temperature. Thus, the insulating film is formed only on the side surface of the target semiconductor film.

  According to the present invention having the above configuration, even at a temperature of 700 ° C., in which alignment misalignment during patterning is conventionally a problem due to shrinkage of a substrate such as glass, alignment defects during patterning do not pose a problem to the gate insulating film. Heat treatment can be added.

  In the present invention, heat treatment can be performed on the gate insulating film at a temperature of 700 ° C., which is higher than the strain point of a substrate such as glass, so that in a thin film transistor, interface states are reduced, fixed charges are reduced, and The leakage current is reduced, the field-effect mobility, the subthreshold coefficient, and the like are improved, the change over time in characteristics in continuous operation is reduced, the manufacturing yield can be improved, and the variation in characteristics can be reduced.

  According to the present invention, it is possible to apply heat treatment to a gate insulating film without causing a problem of poor alignment during patterning even at a temperature of 700 ° C. where alignment during patterning is conventionally a problem due to shrinkage of a substrate such as glass. Can be.

  By performing heat treatment on the gate insulating film at 700 ° C., which exceeds the strain point of glass, the interface state in the thin film transistor is reduced, the fixed charge is reduced, the gate leak current is reduced, the field-effect mobility, The sub-threshold coefficient and the like are improved, the change over time in transistor characteristics in continuous operation is reduced, the manufacturing yield can be improved, and the variation in characteristics can be reduced.

(Embodiment 1)
As a substrate that can be used in this embodiment, a glass substrate formed using barium borosilicate glass, aluminoborosilicate glass, aluminosilicate glass, or the like can be given. Typically, a 1737 glass substrate (strain point 667 ° C.) manufactured by Corning Incorporated, an AN100 (strain point 670 ° C.) manufactured by Asahi Glass Co., Ltd. can be applied. Of course, if other similar substrates are used, there is no particular limitation. Absent.

Using the above substrate, as shown in FIGS. 1A and 1E, a second insulating film such as a silicon oxide film, a silicon nitride film, or a silicon oxynitride film (SiO _x N _y ) is formed on a glass substrate 20. 1 Inorganic insulator layer 21 is formed. A typical example of the first inorganic insulator layer 21 has a two-layer structure, a first silicon oxynitride film 50 nm formed by a plasma CVD method using SiH ₄ , NH ₃ , and N ₂ O as a reaction gas. This is a structure in which a second silicon oxynitride film is formed to a thickness of 100 nm by a plasma CVD method using SiH ₄ and N ₂ O as reaction gases.

  The crystalline semiconductor film 22 serving as an active layer of the TFT is obtained by crystallizing an amorphous semiconductor film formed on the first inorganic insulator layer 21. As the crystalline semiconductor film 22, a crystalline silicon film or the like can be used. The thickness of the amorphous semiconductor film is selected so that the thickness of the crystalline semiconductor film 22 obtained by crystallizing the amorphous semiconductor film is 20 nm to 60 nm. The upper limit of the thickness of the crystalline semiconductor film 22 serving as the active layer of the TFT is the maximum value in order to operate as a fully depleted type in the channel region of the TFT. In the etching process of the crystalline semiconductor film 22, it is determined as the minimum value required when only the crystalline semiconductor film 22 is selectively processed.

A gate insulating film is formed on the crystalline semiconductor film. As the gate insulating film 23, a silicon oxide film formed by a reactive sputtering method using Ar and O ₂ using a Si target, and a film formed by CVD using SiH ₄ , NH ₃ , and N ₂ O as reaction gases. Silicon oxynitride film or the like can be used. Of course, the gate insulating film 23 is not limited to a silicon compound, and may be a metal oxide having a higher dielectric constant than silicon oxide and a high dielectric constant metal oxide that can effectively reduce the thickness of the gate insulating film. The effective film thickness is defined as an actual film thickness t and a ratio k ₁ / k ₂ between a relative permittivity k _{1 of} a reference film material, for example, silicon oxide, and a relative permittivity k ₂ of the actual film material. And the product of t · k ₁ / k ₂ . Note that the thickness of the gate insulating film 23 is set based on a scaling rule and a margin in the process. Here, in order to manufacture a TFT having a gate length of 0.35 μm to 2.5 μm, the thickness of the gate insulating film 23 is set to 20 nm to 80 nm. did.

Next, a first conductive film 24 is formed over the gate insulating film 23. The first conductive film 24 is formed of a tantalum nitride film with a thickness of 10 to 50 nm by reactive sputtering using a Ta target and using Ar and N ₂ gas. Of course, other conductive films than the tantalum compound may be used for the first conductive film 24. However, the first conductive film 24 is a material that absorbs light having a wavelength of about 1 μm, and a material that can have a sufficient selectivity in etching with a second conductive film 34 to be formed later. Is desirable.

  After that, as shown in FIGS. 1B and 1F, heat treatment is performed on the crystalline semiconductor film 22, the gate insulating film 23, and the first conductive film 24. As the heat treatment, an RTA process capable of instantaneously raising and lowering the temperature is used. In the RTA process, the temperature is raised to 600 ° C. to 800 ° C. in 10 seconds to 120 seconds, and heat treatment is performed at 600 ° C. to 800 ° C. for 30 seconds to 180 seconds. As a method of the RTA treatment, there are a gas heating method using a heating gas and a lamp heating method using radiation of a lamp. In the case of the gas heating method, the glass substrate 20 itself is heated by the gas, so that the gate insulating film 23 can be heated. However, in the lamp heating method, the temperature raising efficiency is generally extremely low. This is because a general halogen lamp has a radiation spectrum peak at about 1 μm, and the glass substrate 20 does not sufficiently absorb light in such a wavelength region, so that the glass substrate 20 itself is not easily heated. In this embodiment, since the tantalum nitride film as the first conductive film 24 absorbs light having a wavelength of about 1 μm, heat conduction to the gate insulating film 23 occurs using the tantalum nitride film as an absorption layer, and The heat treatment of the film 23 can be performed efficiently. Note that this heat treatment is performed at a temperature exceeding the strain point of the glass, and the glass substrate 20 shrinks. However, when the heat treatment is performed, the crystalline semiconductor film 22 is not yet processed into an element shape. Therefore, patterning failure due to the shrink does not occur.

Next, as shown in FIGS. 1C and 1G, the crystalline semiconductor film 22, the gate insulating film 23, and the first conductive film 24 are collectively etched into an island shape using the same photomask. . As an etching method, for example, an ICP (Inductively Coupled Plasma: inductively coupled plasma) etching method can be applied. As an etching gas, a mixed gas of CF ₄ and Cl ₂ can be used for etching the first conductive film 24 made of a tantalum nitride film. A CHF ₃ gas can be used for etching the gate insulating film 23 made of a silicon oxide film, and a mixed gas of CF ₄ and O ₂ can be used for etching the crystalline semiconductor film 22 made of a crystalline silicon film. Thus, the crystalline semiconductor film 25 and the crystalline semiconductor film 28 processed into an island shape, the gate insulating film 26 and the gate insulating film 29 processed into an island shape, and the first conductive film processed into an island shape 27, forming a first conductive film 30;

  Next, as shown in FIGS. 1D and 1H, an insulating film 31 covering the entire surface of the glass substrate 20 is formed, and the exposed side surfaces of the crystalline semiconductor film 25 and the crystalline semiconductor film 28 are covered. As the insulating film 31, a silicon oxide film formed to have a thickness of 500 nm to 1.5 μm by using a low pressure CVD method which grows isotropically was used. Note that the insulating film 31 may be any insulating film, and is not limited to a silicon oxide film. Of course, a silicon nitride film and a silicon oxynitride film can also be used.

  Then, a predetermined bias voltage is applied to the glass substrate 20 side, and the insulating film 31 made of a silicon oxide film is anisotropically etched, as shown in FIGS. Side walls 32 and 33 covering the side surfaces of the conductive semiconductor film 28 and the side surfaces of the gate insulating film 26 and the gate insulating film 29 can be formed. The effective thickness in the direction perpendicular to the side surfaces of the sidewalls 32 and 33 in the portion covering the side surfaces of the crystalline semiconductor film 25 and the crystalline semiconductor film 28 is determined by the effective thickness of the gate insulating film 26 and the gate insulating film 29. Thickness. For example, when the gate insulating film 26, the gate insulating film 29, the sidewalls 32, and the sidewalls 33 are all formed of a silicon oxide film, the crystalline semiconductor film 25 and the sidewalls 32 in portions covering the side surfaces of the crystalline semiconductor film 28 are formed. The thickness of the wall 33 in the direction perpendicular to the side surface is 20 nm to 80 nm or more, which is the thickness of the gate insulating film 26 and the gate insulating film 29. Thus, a short circuit and a current leak between the portion where the gate electrode is routed out of the semiconductor film separated from the element and the side surfaces of the crystalline semiconductor film 25 and the crystalline semiconductor film 28 can be suppressed.

  Next, a second conductive film 34 shown in FIGS. 2B and 2G is formed. In this embodiment, a tungsten film having a thickness of 300 nm to 500 nm is used as the second conductive film 34. The second conductive film 34 is not limited to a tungsten film and may be a conductive film. However, it is desirable that the second conductive film 34 be made of a material that can provide a sufficient selectivity in etching with the first conductive film 24.

Further, as shown in FIGS. 2C and 2H, the first conductive film 24 and the second conductive film 34 are etched to form a first conductive film made of tantalum nitride and processed into a gate electrode shape. The layer 37, the first conductive layer 40, and the second conductive layer 38 made of tungsten are obtained. Here, a structure in which end portions of the first conductive layer 37, the first conductive layer 40, and the second conductive layer 38 have different inclination angles is manufactured. The first conductive layer 37, the first conductive layer 40, and the second conductive layer 38, which have different inclination angles at the ends, form the first conductive film 24 and the second conductive film 34 in two stages. It is formed by etching. In the first stage of etching, both tungsten and tantalum nitride are simultaneously etched by applying a predetermined voltage to the glass substrate 20 using a mixed gas of CF ₄ , Cl _2, and O ₂ as an etching gas, and etching both ends. A layer made of tungsten and a layer made of tantalum nitride having the same inclination angle in the portions are produced. Next, in the second stage etching, the etching gas is changed to SF ₆ , Cl ₂ and O _{2 under} the conditions of the first stage etching, and a predetermined bias voltage is applied to the glass substrate 20 so that only the tungsten layer is formed. Is anisotropically etched. Thus, the first conductive layer 37, the first conductive layer 40, and the second conductive layer 38 having different inclination angles at the ends are formed. Note that in the process of etching the first conductive layer 37, the first conductive layer 40, and the second conductive layer 38, the gate insulating film 26, the gate insulating film 29, the sidewalls 32, and the sidewalls 33 are also etched. The gate insulating film 36, the gate insulating film 39, the sidewall 35a, and the sidewall 35b are formed.

  Next, a desired amount of impurity doping is performed. 2D and 2I, 41 and 44 are a source or a drain doped with a high concentration of n-type or p-type impurities, respectively, and 42 and 45 are a first conductive layer 37 which is a part of a gate electrode. Since the doping is performed through the end of the first conductive layer 40, a doping region (Gate Overlapped Lightly Doped Drain) doped with an n-type impurity at a lower concentration than the source or drain 41 and the source or drain 44 is formed. 43 and 46 are channel regions.

  After that, as shown in FIGS. 2E and 2J, a silicon oxynitride film containing hydrogen is formed to a thickness of 100 nm by a plasma CVD method as the insulating film 51, and a heat treatment at 410 ° C. The semiconductor film 25, the crystalline semiconductor film 28, the gate insulating film 36, and the gate insulating film 39 are subjected to hydrogenation treatment. Further, a silicon oxide film having a thickness of 400 to 600 nm is formed as the interlayer insulating film 52 by a CVD method. Note that as the interlayer insulating film 52, phosphorus glass (PSG), boron glass (BSG), phosphorus boron glass (PBSG), or the like can be used. In addition, as the interlayer insulating film 52, a porous film or a low dielectric constant film such as an organic resin-based acrylic or Teflon (registered trademark) can be used. Next, a silicon nitride film having a thickness of 100 nm is formed as the barrier film 53 by a sputtering method. Next, the barrier film 53, the interlayer insulating film 52, the insulating film 51, the gate insulating film 36, and the gate insulating film 39 are etched to form a contact portion reaching the source or drain 41 and the source or drain 44. 48, wiring 49, and wiring 50 are formed. As the wirings 47 to 50, a stacked structure of a 60-nm-thick titanium film, a 40-nm-thick titanium nitride film, a 300-nm-thick aluminum film, and a 100-nm-thick titanium film is used. However, needless to say, the structure of the wirings 47 to 50 is not limited to this, and copper can be used instead of aluminum. The film in contact with the aluminum film in the wirings 47 to 50 is not limited to titanium nitride, but may be tantalum nitride, tungsten nitride, or the like.

(Embodiment 2)
In Embodiment 1, the crystalline semiconductor film 25, the crystalline semiconductor film 28, the gate insulating film 26, the gate insulating film 29, and the first conductive film which are processed into an island shape as shown in FIGS. The film 27 and the first conductive film 30 are oxidized at 500 ° C. using ozone. Thus, as shown in FIGS. 3A and 3C, an oxide film is formed on the exposed side surfaces of the crystalline semiconductor film 25 and the crystalline semiconductor film 28, and the effective thickness of the oxide film is reduced to the gate insulating film. 26, by setting the thickness to be equal to or more than the effective thickness of the gate insulating film 29, a short circuit between the subsequently formed gate electrode and the side surfaces of the crystalline semiconductor film 25 and the crystalline semiconductor film 28 can be prevented. Note that as the insulating film formed on the side surfaces of the crystalline semiconductor film 25 and the crystalline semiconductor film 28, an oxide film, a nitride film, an oxynitride film, or the like can be used. As an oxidation method, plasma oxidation using plasma containing oxygen can be used in addition to a method using ozone gas. In addition, washing with ozone water may be performed as an oxidation method. At this time, when the surface of the glass substrate 20 is irradiated with ultraviolet light, oxidation can be performed efficiently. As a nitriding method, plasma nitriding using a plasma containing a nitrogen gas can be used. A resist mask used for patterning the island-shaped crystalline semiconductor film 25, the crystalline semiconductor film 28, the gate insulating film 26, the gate insulating film 29, the first conductive film 27, and the first conductive film 30. By doping with oxygen or nitrogen while leaving the surface, only the side surfaces of the crystalline semiconductor film 25 and the crystalline semiconductor film 28 can be selectively turned into an insulator film.

(Embodiment 3)
In Embodiment 1, as shown in FIGS. 1C and 1G, the crystalline semiconductor film 25, the crystalline semiconductor film 28, the gate insulating film 26, the gate insulating film 29, and the first After the formation of the conductive film 27 and the first conductive film 30, an insulating film is formed on the entire surface of the glass substrate 20 so as to cover the crystalline semiconductor film 25, the crystalline semiconductor film 28, the gate insulating film 26, and the gate insulating film 29. I do. As the insulating film, a silicon oxide film formed with a thickness of 50 to 100 nm by a CVD method is used. Needless to say, the insulating film is not limited to a silicon oxide film formed by a CVD method, and a silicon nitride film, a silicon oxynitride film, or the like can be used. The film formation method is not limited to the CVD method, and a sputtering method or the like can be used. Thereafter, as shown in FIGS. 3B and 3D, the insulating film is patterned to form insulating layers 54 to 57. The insulating layers 54 to 57 each have a shape covering a side surface in a region overlapping with a gate electrode formed at least after the island-shaped crystalline semiconductor film 25 and the crystalline semiconductor film 28, and have an effective thickness of the insulating layers 54 to 57. By setting the thickness to be equal to or more than the effective thickness of the gate insulating film 26 and the gate insulating film 29, short circuit between the crystalline semiconductor film 25 and the crystalline semiconductor film 28 and a gate electrode formed thereafter can be prevented. it can.

  A cross-sectional structure in the case where a display device is manufactured using a typical thin film transistor manufactured in Embodiments 1 to 3 will be described.

  Through the manufacturing process described in the above embodiment, the TFTs provided in the driver circuit portion and the pixel portion are formed over the substrate 500 having an insulating surface. After that (FIG. 4A), a first electrode 501 made of a transparent conductive film is formed so as to be electrically connected to the wiring 507 of the driving TFT 513. It is preferable that the transparent conductive film be formed using a material having a large work function, and examples thereof include a compound of indium oxide and tin oxide (ITO), a compound of indium oxide and zinc oxide, zinc oxide, tin oxide, and indium oxide. , Titanium nitride and the like. In this embodiment, as the first electrode 501, an ITO film having a thickness of 0.1 μm is formed by a sputtering method.

  In this embodiment, the method of forming the wiring 507 and then forming the transparent conductive film so as to be electrically connected to the wiring 507 is described; however, another method may be used. For example, after forming a transparent conductive film, patterning the transparent conductive film to form a first electrode, and then forming a TFT wiring 507 so as to be electrically connected to the first electrode. Good. After forming the wiring 507 for the TFT, an insulating film is formed over the wiring 507, and then a contact hole is formed in the insulating film so as to reach the wiring 507. Then, a transparent conductive film may be formed so as to be electrically connected to the wiring 507 through the contact hole.

  Next, an insulating film 504 is formed so as to cover an end surface of the first electrode 501. The material for forming the insulating film 504 is not particularly limited, and can be formed using an inorganic or organic material. It is preferable that the insulating film 504 be formed using a photosensitive organic substance because the shape of the opening provided in the insulating film 504 is less likely to cause disconnection of the light-emitting layer deposited over the insulating film 504. That is, since the shape of the opening provided in the insulating film 504 can be a gentle curved surface shape in which the inclination of the deposition surface of the light-emitting layer changes continuously, coverage of the light-emitting layer is improved, and breakage of the light-emitting layer is improved. Cutting can be prevented. Thereby, a short circuit between the anode and the cathode due to disconnection of the light emitting element is reduced. Further, it is possible to prevent the light emitting layer from being partially thinned, and it is possible to prevent local concentration of an electric field in the light emitting layer. As a photosensitive organic substance for forming the insulating film 504, a photosensitive polyimide resin, a photosensitive acrylic, or the like can be used. For example, when a negative photosensitive resin is used as the material of the insulating film 504, the shape of the upper end of the insulating film 504 in contact with the upper surface of the first electrode 501 is changed to the upper surface of the insulating film 504 and the upper end of the insulating film 504. Has a center of curvature below the tangent to the first electrode 501 and has a curved surface determined by the first radius of curvature, and the shape of the lower end of the insulating film 504 is set above the tangent of the first electrode 501 and the lower end of the insulating film 504. It can be formed to have a curved surface shape having a center of curvature and determined by the second radius of curvature. The first and second radii of curvature are preferably 0.2 μm to 3 μm, and the angle of the wall surface of the opening with respect to the first electrode 501 is preferably 35 ° or more.

  Next, wiping is performed using a PVA (polyvinyl alcohol) -based porous body to remove dust and the like. In this embodiment, fine powder (dust) generated when the first electrode 501 and the insulating film 504 made of ITO are etched by wiping using a porous body of PVA.

  Next, a light-emitting layer 502 is formed so as to be in contact with the first electrode 501. The light-emitting layer 502 is formed by an evaporation method or a coating method (a spin coating method, an inkjet method, or the like). In this embodiment, a method of performing evaporation while moving the evaporation source was used. In this method, the organic compound that is the material of the light emitting layer 502 placed in the evaporation source is vaporized in advance by resistance heating, and prevents the vaporized organic compound from scattering from the vapor deposition source toward the glass substrate 20. A shutter is provided. At the time of vapor deposition, the organic compound vaporized by opening the shutter scattered upward, was vapor-deposited on the glass substrate 20 through an opening provided in the metal mask, and the light-emitting layer 502 was formed.

  Note that as a process before the deposition of the light-emitting layer 502, PEDOT may be applied to the entire surface and baking may be performed. At this time, since PEDOT has poor wettability with ITO as the first electrode 501, it is preferable to apply PEDOT once, rinse with water, and apply PEDOT again. After applying PEDOT in this manner, heating is performed at normal pressure to remove moisture, and then heating is performed in a reduced-pressure atmosphere.

  One or more layers provided between the first and second electrodes included in the light-emitting element are collectively referred to as a light-emitting layer (a layer containing a light-emitting material) 502. The light-emitting layer 502 is a low-molecular organic compound. It can be formed of a material, a polymer organic compound material, or a combination of both. Further, a mixed layer in which an electron transporting material and a hole transporting material are appropriately mixed, or a mixed junction in which a mixed region is formed at each bonding interface may be formed. Further, an inorganic light emitting material may be used in addition to the organic material. Further, the layered structure of the light-emitting layer 502 is not particularly limited, and may have a structure in which layers made of a low molecular material are stacked or a structure in which a layer made of a high molecular material and a layer made of a low molecular material are stacked.

  Subsequently, a second electrode 503 is formed over the light-emitting layer 502. The second electrode 503 is formed using a thin film containing a metal (Li, Mg, Cs) having a low work function, or a transparent conductive film stacked over a thin film containing Li, Mg, or the like. The film thickness may be appropriately set so as to function as a cathode, and is formed to a thickness of about 0.01 to 1 μm by a known method (such as an electron beam evaporation method). However, when the electron beam evaporation method is used, if the acceleration voltage is too high, radiation is generated, and the TFT is damaged. However, even if the acceleration voltage is too low, the film forming speed is reduced, and the productivity is reduced. Therefore, the second electrode 503 is not formed to have a thickness larger than that which can function as a cathode. When the second electrode 503 is thin, the productivity is not significantly affected even if the deposition rate is low. However, there is also a problem that the resistance is increased due to the thin film thickness of the cathode. This problem can be solved by forming a low resistance metal such as Al on the cathode by resistance heating evaporation or sputtering to form a laminated structure. In this embodiment, as the second electrode 503, Al-Li is formed to a thickness of 0.1 μm by an electron beam evaporation method.

  Next, a protective film 505 is formed over the insulating film 504 and the second electrode 503. As the protective film 505, a film which does not easily transmit a substance such as moisture or oxygen which causes deterioration of the light-emitting element 506, as compared with another insulating film, is used. Typically, it is preferable to use a DLC film, a carbon nitride film, a silicon nitride film formed by an RF sputtering method, or the like. It is desirable that the film thickness be about 10 to 200 nm. In this embodiment, a silicon nitride film is formed with a thickness of 100 nm by a sputtering method.

  The stacked body of the first electrode 501, the light-emitting layer 502, and the second electrode 503 formed in the steps up to here corresponds to the light-emitting element 506. The first electrode 501 corresponds to an anode, and the second electrode 503 corresponds to a cathode. In the present invention, the excited state of the light-emitting element 506 includes singlet excitation and triplet excitation; however, light emission may pass through either of the excited states.

  FIG. 4B is a top view of one pixel in a display device using a light-emitting element. FIG. 4B shows a state where the pixel electrode 501 is formed. In the top view of FIG. 4B, a cross-sectional view corresponding to ABC is equivalent to FIG. FIG. 4C is a circuit diagram of one pixel corresponding to FIG. 4B. 4B and 4C, 508 is a source line, 509 is a gate line, 510 is a power line, 511 is a capacitor, 501 is a first electrode (pixel electrode), 512 is a switching TFT, and 513 is a switching TFT. It corresponds to a driving TFT.

  In this embodiment, the case where light emitted from the light-emitting element 506 is extracted from the substrate 500 side, that is, so-called bottom emission is described. However, light may be extracted from a direction opposite to the substrate 500, that is, so-called top emission may be performed. In that case, the first electrode 501 may be formed to correspond to a cathode, the second electrode 503 may be formed to correspond to an anode, and the second electrode 503 may be formed of a transparent material. Further, the driving TFT 513 is preferably formed by an N-channel TFT. Although the conductivity type of the driving TFT 513 may be changed as appropriate, the capacitor 511 is arranged so as to hold a gate-source voltage of the driving TFT 513. In this embodiment, the case of the light emitting device using the thin film transistor and the light emitting element of the present invention is described; however, the present invention can be applied to other display devices such as a liquid crystal display device.

  This embodiment can be freely combined with the above embodiments.

  An embodiment of the present invention will be described with reference to FIG. FIG. 5A is a top view of a display panel formed by sealing a substrate on which a TFT is formed with a sealing material, and FIG. 5B is a cross-sectional view taken along line BB ′ in FIG. FIGS. 5C and 5D are cross-sectional views taken along line AA ′ of FIG. 5A. Note that FIG. 5C shows a display panel which emits light in the direction of the substrate on which the TFT is formed and emits light in the bottom direction, and FIG. 5D shows an upper surface which emits light in the direction opposite to the substrate on which the TFT is formed. It is sectional drawing of the display panel which performs.

  5A to 5D, over a substrate 601, a pixel portion (display portion) 602, a signal line driver circuit 603 provided to surround the pixel portion 602, a scan line driver circuit 604a, a scan line A driving circuit 604b is provided, and a sealing material 606 is provided so as to surround these. As the structure of the pixel portion 602, the configuration and the like described in Embodiment 1 can be used. As the sealant 606, a glass material, a metal material, a ceramic material, or a plastic material is used. The sealant 606 may be provided so as to overlap with part of the signal line driver circuit 603, the scan line driver circuit 604a, and part of the scan line driver circuit 604b.

  In the display panel illustrated in FIG. 5C, a sealing material 607 is provided using a sealing material 606 as an adhesive layer, and a closed space 608 is formed by the substrate 601, the sealing material 606, and the sealing material 607. The sealing material 607 is provided with a hygroscopic agent 609 in the concave portion in advance, and plays a role of adsorbing moisture, oxygen, and the like inside the closed space 608 to maintain a clean atmosphere and suppress deterioration of the light emitting element. This concave portion is covered with a fine mesh-shaped cover material 610. The cover member 610 allows air and moisture to pass, but does not allow the moisture absorbent 609 to pass. Note that the sealed space 608 may be filled with a rare gas such as nitrogen or argon, and may be filled with a resin or liquid if it is inert.

  In the display panel in FIG. 5D, a transparent counter substrate 621 is provided using the sealant 606 as an adhesive layer, and a closed space 622 is formed by the substrate 601, the opposing substrate 621, and the sealant 606. The opposite substrate 621 is provided with a color filter 620 and a protective film 623 for protecting the color filter. Light emitted from a light-emitting element provided in the pixel portion 602 is emitted outside through the color filter 620, and a multi-color display is performed on a display panel. The closed space 622 is filled with an inert resin or a liquid. When performing multi-color display, the light emitting layer may be set to emit each color of RGB, or a pixel provided with a light emitting layer that emits white light may be arranged and a color filter or a color conversion layer may be used. May be set.

  An input terminal portion 611 for transmitting a signal to the signal line driver circuit 603, the scan line driver circuit 604 a, and the scan line driver circuit 604 b is provided over the substrate 601, and the input terminal portion 611 is connected to the video terminal via the FPC 612. A data signal such as a signal is transmitted. A cross section of the input terminal portion 611 is as illustrated in FIG. 5B, and an input wiring 613 formed of a wiring formed at the same time as a scan line or a signal line and a wiring 615 provided on the FPC 612 side are connected to a conductor 616. Are electrically connected using a resin 617 in which is dispersed. Note that as the conductor 616, a material in which a spherical polymer compound is plated with gold or silver may be used.

  In this embodiment, an example in which the present invention is applied to a light-emitting panel using a light-emitting element is described. However, the present invention may be applied to a liquid-crystal panel using a liquid crystal display element.

  This embodiment can be freely combined with the above-described embodiment modes and embodiments.

  Examples of the electronic device to which the present invention is applied include a video camera, a digital camera, a goggle type display, a navigation system, a sound reproducing device (such as a car audio), a notebook personal computer, a game device, and a portable information terminal (a mobile computer, a mobile phone, etc.). ), An image reproducing apparatus provided with a recording medium, and the like. FIG. 6 shows specific examples of these electronic devices.

  FIG. 6A illustrates a light-emitting device, which includes a housing 2001, a support base 2002, a display portion 2003, a speaker portion 2004, a video input terminal 2005, and the like. The present invention can be applied to the display portion 2003. Since the light-emitting device is a self-luminous type, it does not require a backlight and can be a display portion thinner than a liquid crystal display. Note that the light-emitting device includes all display devices for displaying information, such as for personal computers, for receiving TV broadcasts, and for displaying advertisements.

  FIG. 6B illustrates a digital still camera, which includes a main body 2101, a display portion 2102, an image receiving portion 2103, operation keys 2104, an external connection port 2105, a shutter 2106, and the like. The present invention can be applied to the display portion 2102.

  FIG. 6C illustrates a laptop personal computer, which includes a main body 2201, a housing 2202, a display portion 2203, a keyboard 2204, an external connection port 2205, a pointing mouse 2206, and the like. The present invention can be applied to the display portion 2203.

  FIG. 6D illustrates a mobile computer, which includes a main body 2301, a display portion 2302, a switch 2303, operation keys 2304, an infrared port 2305, and the like. The present invention can be applied to the display portion 2302.

  FIG. 6E illustrates a portable image reproducing device (specifically, a DVD reproducing device) including a recording medium, which includes a main body 2401, a housing 2402, a display portion A 2403, a display portion B 2404, a recording medium reading portion 2405, An operation key 2406, a speaker unit 2407, and the like are included. The display portion A2403 mainly displays image information, and the display portion B2404 mainly displays character information. The present invention can be applied to the display portion A2403 and the display portion B2404.

  FIG. 6F illustrates a goggle-type display (head-mounted display), which includes a main body 2501, a display portion 2502, and an arm portion 2503. The present invention can be applied to the display portion 2502.

  FIG. 6G illustrates a video camera, which includes a main body 2601, a display portion 2602, a housing 2603, an external connection port 2604, a remote control receiving portion 2605, an image receiving portion 2606, a battery 2607, a voice input portion 2608, operation keys 2609, and the like. An eye 2610 is included. The present invention can be applied to the display portion 2602.

  FIG. 6H illustrates a mobile phone, which includes a main body 2701, a housing 2702, a display portion 2703, a sound input portion 2704, a sound output portion 2705, operation keys 2706, an external connection port 2707, an antenna 2708, and the like. The present invention can be applied to the display portion 2703. Note that the display portion 2703 displays white characters on a black background, so that current consumption of the mobile phone can be suppressed.

  As described above, the applicable range of the present invention is extremely wide, and the present invention can be used for electronic devices in all fields. The electronic device of this embodiment can be freely combined with any of the above-described embodiments and examples.

FIG. 4 illustrates a manufacturing process of a thin film transistor of the present invention. FIG. 4 illustrates a manufacturing process of a thin film transistor of the present invention. FIG. 4 illustrates a manufacturing process of a thin film transistor of the present invention. FIG. 4 illustrates a pixel configuration of a display panel according to the present invention. FIG. 4 illustrates a configuration of a display panel according to the present invention. FIG. 2 illustrates a configuration of an electronic device according to the present invention. 6A to 6C illustrate a manufacturing process of a conventional thin film transistor in which a semiconductor film is separated before a gate insulating film is formed.

Explanation of reference numerals

REFERENCE SIGNS LIST 10 insulating substrate 11 base film 12 semiconductor film 13 transistor fabrication region 14 transistor fabrication region 15 gate insulating film 16 conductive film 17 gate insulating film 18 gate electrode 20 glass substrate 21 first inorganic insulator layer 22 crystalline semiconductor film 23 gate Insulating film 24 first conductive film 25 crystalline semiconductor film 26 gate insulating film 27 first conductive film 28 crystalline semiconductor film 29 gate insulating film 30 first conductive film 31 insulating film 32 sidewall 33 sidewall 34 second conductive film 35a sidewall 35b sidewall 36 gate insulating film 37 first conductive layer 38 second conductive layer 39 gate insulating film 40 first conductive layer 41 source or drain 42 gate electrode 43 channel region 44 Source or drain 45 Gate electrode 46 Channel region 47 Wiring 48 Wiring 9 wiring 50 wiring 51 insulating film 52 interlayer insulating film 53 barrier film 54 insulating layer 55 insulating layer 56 insulating layer 57 insulating layer 500 substrate 501 first electrode 502 light emitting layer 503 second electrode 504 insulating film 505 protective film 506 light emitting element 507 Wiring 508 Source line 509 Gate line 510 Power supply line 511 Capacitance element 512 Switching TFT
513 Driving TFT
601 Substrate 602 Pixel unit 603 Signal line driving circuit 604a Scanning line driving circuit 604b Scanning line driving circuit 606 Sealing material 607 Sealing material 608 Sealed space 609 Hygroscopic agent 610 Cover material 611 Input terminal part 612 FPC
613 Input wiring 615 Wiring 616 Conductor 617 Resin 620 Color filter 621 Counter substrate 622 Sealed space 623 Protective film 2001 Housing 2002 Support base 2003 Display unit 2004 Speaker unit 2005 Video input terminal 2101 Main unit 2102 Display unit 2103 Image receiving unit 2104 Operation key 2105 External connection port 2106 Shutter 2201 Main body 2202 Housing 2203 Display 2204 Keyboard 2205 External connection port 2206 Pointing mouse 2301 Main body 2302 Display 2303 Switch 2304 Operation key 2305 Infrared port 2401 Main body 2402 Housing 2403 Display A
2404 Display B
2405 Recording medium reading unit 2406 Operation keys 2407 Speaker unit 2501 Main unit 2502 Display unit 2503 Arm unit 2601 Main unit 2602 Display unit 2603 Housing 2604 External connection port 2605 Remote control receiving unit 2606 Image receiving unit 2607 Battery 2608 Audio input unit 2609 Operation key 2701 Main unit 2702 Housing 2703 Display unit 2704 Audio input unit 2705 Audio output unit 2706 Operation keys 2707 External connection port 2708 Antenna

Claims (17)

On an insulating substrate, an island-shaped semiconductor film and an island-shaped gate insulating film patterned using the same photomask, a sidewall made of an insulating material formed on a side surface of the island-shaped semiconductor film, A gate electrode formed on an island-shaped gate insulating film, wherein the gate electrode overlaps a side surface of the island-shaped semiconductor film via the sidewall. An island-shaped semiconductor film and an island-shaped gate insulating film patterned using the same photomask on an insulating substrate, and an insulating film formed on side surfaces of the island-shaped semiconductor film and the island-shaped gate insulating film. A sidewall made of a material, and a gate electrode formed on the island-shaped gate insulating film, wherein the gate electrode overlaps a side surface of the island-shaped semiconductor film via the sidewall. A thin film transistor characterized by the above-mentioned. An island-shaped semiconductor film and an island-shaped gate insulating film patterned using the same photomask on an insulating surface, and a gate electrode formed on the island-shaped gate insulating film; A thin film transistor, wherein a side surface of the semiconductor film is insulated, and the gate electrode overlaps a side surface of the insulated island-shaped semiconductor film. On an insulating substrate, an island-shaped semiconductor film and an island-shaped gate insulating film patterned using the same photomask, side surfaces of the island-shaped semiconductor film and the island-shaped gate insulating film, and the island-shaped An insulating film patterned so as to cover only a peripheral portion of an upper surface of the gate insulating film; and a gate electrode formed on the island-shaped gate insulating film, wherein the gate electrode is formed of the island-shaped semiconductor. A film and a side surface of the island-shaped gate insulating film and an insulating film patterned so as to cover only a peripheral portion of an upper surface of the island-shaped gate insulating film, and overlap with the side surface of the island-shaped semiconductor film. A thin film transistor. In claim 1 or claim 2,
An effective thickness of a portion covering the side surface of the island-shaped semiconductor film in a direction perpendicular to the side surface of the sidewall is equal to or more than an effective thickness of the island-shaped gate insulating film. Thin film transistor. In claim 3,
A thin film transistor, wherein the effective thickness of the insulated portion on the side surface of the island-shaped semiconductor film in the direction perpendicular to the side surface is equal to or more than the effective thickness of the island-shaped gate insulating film. . In claim 4,
The effective thickness of the insulating film patterned so as to cover only the side surfaces of the island-shaped semiconductor film and the island-shaped gate insulating film and the peripheral portion of the upper surface of the island-shaped gate insulating film, A thin film transistor having a thickness greater than the effective thickness of the gate insulating film. Forming a semiconductor film on an insulating substrate,
Forming a first insulating film on the semiconductor film;
Heat-treating the semiconductor film and the first insulating film;
After the heat treatment, the semiconductor film and the first insulating film are patterned into an island shape using the same photomask to form an island-shaped semiconductor film and an island-shaped gate insulating film,
Forming a second insulating film on the island-shaped gate insulating film;
Anisotropically etching the second insulating film to form self-aligned sidewalls covering side surfaces of the island-shaped semiconductor film and side surfaces of the island-shaped gate insulating film;
After forming the sidewall, a conductive film is formed on the island-shaped gate insulating film,
A method for manufacturing a thin film transistor, comprising forming a gate electrode by patterning the conductive film. Forming a semiconductor film on an insulating substrate,
Forming an insulating film on the semiconductor film,
Heat-treating the semiconductor film and the insulating film,
After the heat treatment, the semiconductor film and the insulating film are patterned into an island shape using the same resist mask to form an island-shaped semiconductor film and an island-shaped gate insulating film,
Without removing the resist mask, oxygen or nitrogen is added to the side surface of the island-shaped semiconductor film to insulate the side surface of the semiconductor film,
Thereafter, a conductive film is formed on the island-shaped gate insulating film,
A method for manufacturing a thin film transistor, comprising forming a gate electrode by patterning the conductive film. Forming a semiconductor film on an insulating substrate,
Forming a first insulating film on the semiconductor film;
Heat-treating the semiconductor film and the first insulating film;
After the heat treatment, the semiconductor film and the first insulating film are patterned into an island shape using the same photomask to form an island-shaped semiconductor film and an island-shaped gate insulating film,
Forming a second insulating film on the island-shaped gate insulating film;
Patterning the second insulating film so as to cover only the end portions of the island-shaped semiconductor film and the island-shaped gate insulating film and the peripheral portion of the upper surface of the island-shaped gate insulating film;
Thereafter, a conductive film is formed on the island-shaped gate insulating film,
A method for manufacturing a thin film transistor, comprising forming a gate electrode by patterning the conductive film. Forming a semiconductor film on an insulating substrate,
Forming a first insulating film on the semiconductor film;
Forming a first conductive film on the first insulating film;
Heat-treating the semiconductor film, the first insulating film, and the first conductive film,
After the heat treatment, the semiconductor film, the first insulating film, and the first conductive film are patterned into an island shape using the same photomask, so that an island-shaped semiconductor film and an island-shaped gate are formed. Forming an insulating film and an island-shaped first conductive film;
Forming a second insulating film on the island-shaped first conductive film;
Anisotropically etching the second insulating film to form a sidewall covering the side surface of the island-shaped semiconductor film, the side surface of the island-shaped gate insulating film, and the side surface of the island-shaped first conductive film. Self-aligned,
After forming the sidewall, a second conductive film is formed on the island-shaped first conductive film,
A method for manufacturing a thin film transistor, wherein the island-shaped first conductive film and the second conductive film are patterned to form a gate electrode. Forming a semiconductor film on an insulating substrate,
Forming an insulating film on the semiconductor film,
Forming a first conductive film on the insulating film;
Heat-treating the semiconductor film, the insulating film, and the first conductive film,
After the heat treatment, the semiconductor film, the insulating film, and the first conductive film are patterned into islands using the same resist mask, so that an island-shaped semiconductor film and an island-shaped gate insulating film are formed. And an island-shaped first conductive film,
Without removing the resist mask, oxygen or nitrogen is added to the side surface of the island-shaped semiconductor film to insulate the side surface of the semiconductor film,
After that, a second conductive film is formed on the island-shaped first conductive film,
A method for manufacturing a thin film transistor, wherein the island-shaped first conductive film and the second conductive film are patterned to form a gate electrode. Forming a semiconductor film on an insulating substrate,
Forming a first insulating film on the semiconductor film;
Forming a first conductive film on the insulating film;
Heat-treating the semiconductor film, the first insulating film, and the first conductive film,
After the heat treatment, the semiconductor film, the first insulating film, and the first conductive film are patterned into an island shape using the same photomask, so that an island-shaped semiconductor film and an island-shaped gate are formed. Forming an insulating film and an island-shaped first conductive film;
Forming a second insulating film on the island-shaped first conductive film;
The edge of the island-shaped semiconductor film, the island-shaped gate insulating film, the end of the island-shaped first conductive film, and only the peripheral portion of the upper surface of the island-shaped first conductive film are covered. Patterning the second insulating film,
After that, a second conductive film is formed on the island-shaped gate insulating film,
A method for manufacturing a thin film transistor, wherein a gate electrode is formed by patterning the first conductive film and the second conductive film. In any one of claim 8, claim 10, claim 11, or claim 13,
The method for manufacturing a thin film transistor, wherein the heat treatment of the semiconductor film and the first insulating film is performed at 600 to 800 ° C. In claim 9 or claim 12,
The method for manufacturing a thin film transistor, wherein the heat treatment of the semiconductor film and the insulating film is performed at 600 to 800 ° C. In claim 14 or claim 15,
A method for manufacturing a thin film transistor, wherein a strain point of the insulating substrate is 600 ° C. or lower. In any one of claims 8 to 16,
The method for manufacturing a thin film transistor, wherein the gate electrode is led out of the island-shaped semiconductor film.