JP2007081043A - Organic thin film transistor and method of manufacturing same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To manufacture an organic thin film transistor using a low molecular weight organic semiconductor at low cost by reducing a mask step in a vacuum process. <P>SOLUTION: The method of manufacturing the organic thin film transistor uses a laminate S1 having a gate electrode 102 on a substrate 101, and a gate insulating film 103 on the surface of the gate electrode 102 and the substrate 101. The method includes the steps of: arranging a mask 108 having a predetermined pattern-shaped opening while being spaced apart from the laminate S1 (a); forming an organic semiconductor film 104 in the element forming region of the laminate S1 by ejecting an organic semiconductor material, in the directions including inclined directions, to the mask 108 (b); and forming a source electrode 105 and a drain electrode 106 in the element forming region of the laminate S1 by using the mask 108 and ejecting an electrode material in the direction substantially perpendicular to the mask 108 (c). The organic thin film transistor manufactured by this method is also provided. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an organic thin film transistor element and a manufacturing method thereof. More specifically, the present invention relates to a method for manufacturing an organic thin film transistor element capable of reducing the number of manufacturing steps and an organic thin film transistor with improved performance.

  In recent years, environmental problems due to the massive use of paper have become obvious, and research and development of electronic information technology has been actively conducted in order to cope with paperlessness. For example, a light and thin electronic display medium called electronic paper or digital paper that displays information printed on a paper medium has attracted attention. This display medium has an advantage that it can be easily carried and is optimal as a mobile display medium. In order to realize such a display medium, a large area and flexible thin film transistor for displaying digitized information is indispensable.

  A thin film transistor in a liquid crystal display device, which is a representative of the current display device, sequentially forms an a-Si (amorphous silicon) or p-Si (polysilicon) semiconductor thin film and a metal thin film as an electrode on a glass substrate. It is manufactured by. Thin film formation requires a high-temperature treatment process in addition to a vacuum process such as CVD or sputtering, and it has been difficult to form a transistor element on a light and flexible resin substrate.

  Therefore, research and development of an organic thin film transistor that forms a thin film of an organic semiconductor material on a resin substrate has been actively performed (see, for example, Japanese Patent Application Laid-Open No. 2004-79623 (Patent Document 1)). That is, since the organic semiconductor material can form a thin film on a resin substrate by a low temperature process, a flexible display using an organic thin film transistor can be realized by using a thin resin film as a substrate (“Nikkei Electronics”, 2003). October 13th issue, p.30 (Non-Patent Document 1)).

JP 2004-79623 A “Nikkei Electronics”, October 13, 2003, p. 30

  However, the organic thin film transistor according to the above-described prior art has a problem of high manufacturing cost. For example, when an organic thin film transistor is used for a display device (display) or an input device (scanner), it is necessary to satisfy the operating frequency. In order to increase the operating frequency, a low molecular system using a vacuum process is required. It is necessary to form an organic semiconductor with high carrier mobility by vapor deposition of the organic semiconductor material. However, when a vacuum process is used, the manufacturing cost increases.

For example, when an organic thin film transistor (array) having a top contact type structure as shown in FIG. 3 of Patent Document 1 is manufactured using a vacuum process, the following steps are performed.
(1) First, a resist is formed on a substrate by a spin coating method, and then an opening is formed by a photomask using a lithography technique. A metal film is formed on the entire surface by sputtering or the like, the resist is removed with a resist stripping solution, and the gate electrode is formed by leaving only the metal in close contact with the resist opening.
(2) After forming the gate electrode, a gate insulating film is formed on each gate electrode surface and the substrate surface by plasma CVD.
(3) The substrate is transported to the first vacuum deposition apparatus.
(4) Subsequently, for example, an organic semiconductor film is separately deposited for each active element region of each pixel in the display device. At this time, an opening of the metal mask is disposed on the element region, and an organic semiconductor film is deposited on the gate insulating film for each element formation region by a vacuum deposition method.
(5) After removing the metal mask, the metal mask is transported to a second vacuum deposition apparatus.
(6) A second metal mask is disposed on the organic semiconductor film, and source and drain electrodes are formed on the organic semiconductor film by vacuum deposition.

Thus, when manufacturing an organic thin-film transistor by the conventional vacuum process, there are many mask processes (two metal mask processes and one photomask process), many processes of removing or arranging a mask, and a conveyance process. A large number of factors was a major factor in increasing manufacturing costs. More specifically, in the metal mask process, a mask process for forming an organic semiconductor and a mask process for forming source and drain electrodes are required twice, and a mask alignment apparatus is required for each. Moreover, since the vapor deposition process is separated, it is necessary to transport between vacuum vapor deposition apparatuses.
Therefore, in the conventional manufacturing method, the manufacturing cost is increased by these mask process and transport process.
Moreover, in the said process (4), even if the organic-semiconductor film could be vapor-deposited for every element area | region, it was difficult to isolate | separate and vapor-separate for every element, and, thereby, the leakage current generate | occur | produced.

  In addition, the organic thin film transistor manufactured by the above manufacturing method has a step similar to a rectangle where the organic semiconductor film is not formed when the organic semiconductor film is deposited using a mask as in the above step (4). When the flexible organic thin film transistor is bent, element peeling is likely to occur from the interface between the organic semiconductor film and the gate insulating film, which is a disadvantageous structure for improving the bending resistance and the element life.

  The present invention has been made in view of the above problems, and has as its main purpose to reduce the number of manufacturing steps and to obtain an organic thin film transistor with improved bending resistance and device lifetime at a low cost. To do.

Thus, according to the present invention, the gate electrode formed on the surface of the substrate, the surface of the substrate and the gate insulating film formed on the surface of the gate electrode, and the element formation region on the gate insulating film are formed. An organic thin film transistor is provided that includes an organic semiconductor film, a source electrode, and a drain electrode, and the organic semiconductor film is formed in a taper shape in which both ends in a channel length direction become thinner toward the outside.
According to another aspect of the present invention, a laminate having a gate electrode on the surface of the substrate and a gate insulating film on the surface of the gate electrode and the substrate is used, and (a) having at least a pair of openings. A step of disposing a mask above the stacked body with a gap; and (b) irradiating the organic semiconductor material at least in a channel length direction with respect to the mask to form an organic semiconductor film in an element forming region of the stacked body. And (c) forming a source electrode and a drain electrode in an element formation region of the laminate by irradiating an electrode material in a direction substantially perpendicular to the mask using the mask. A method of manufacturing a thin film transistor is provided.

According to the organic thin film transistor of the present invention, since the organic semiconductor film is formed in a taper shape in which the film thickness decreases toward the outside at both ends in the channel length direction, at least one organic thin film transistor has a periphery in the channel length direction. This region is electrically insulated from the region. Therefore, it is possible to obtain a semiconductor device (transistor array) in which a plurality of organic thin film transistors that have a tapered portion in the channel length direction and are insulated (divided) from each other are arranged on the same substrate.
In addition, the organic thin film transistor of the present invention has an end portion of the organic semiconductor film having a tapered shape, so that the end portion of the organic semiconductor film is curved as compared with a conventional organic thin film transistor having a steep step formed vertically. When the device is peeled off, the device life is improved. Therefore, the present invention is suitable for a flexible organic thin film transistor that can be used or stored in a curved state.

According to the method of manufacturing an organic thin film transistor of the present invention, the organic semiconductor film and the source and drain electrodes are formed with one mask and one vacuum device, so that the number of transfer steps between the conventional mask process and the vacuum deposition apparatus is reduced. Can do. When forming the organic semiconductor film, a mask for forming the source and drain electrodes is used, and the film forming material is obliquely irradiated in the channel length direction so that the organic semiconductor film is also formed outside the mask opening. It is formed by wrapping around. With this wraparound film formation, the organic semiconductor film is connected between the source and drain electrodes to form a channel region, and both ends of the organic semiconductor film in the channel length direction are formed in a taper shape. It becomes possible to divide and form organic semiconductor films in adjacent organic thin film transistors. That is, element isolation can be performed simultaneously with the formation of the organic semiconductor film. Therefore, isolation for each element is possible as compared with the conventional method in which isolation for each element region is mainly performed.
Therefore, according to the method for producing an organic thin film transistor of the present invention, the production process is reduced and simplified, and the organic thin film transistor can be produced at low cost.

(Structure of organic thin film transistor)
As shown in FIG. 1D, the organic thin film transistor of the present invention includes a gate electrode 102 formed on the surface of the substrate 101, a gate insulating film 103 formed on the surface of the substrate 101, and the surface of the gate electrode 102. And an organic semiconductor film 104 formed in an element formation region on the surface of the gate insulating film 103, a source electrode 105, and a drain electrode 106. The organic semiconductor film 104 has a thickness toward the outside at both ends in the channel length direction. It is characterized by being formed in a taper shape in which the thickness becomes thin.

In this organic thin film transistor, from the viewpoint of further improving the current characteristics, as shown in FIG. 1D, the organic semiconductor film 104 is formed on the surface of the gate insulating film 103, and the source and drain electrodes 105 are formed on the surface of the organic semiconductor film 104. , 106 are preferred. The bottom contact type structure in which the source and drain electrodes are formed on the surface of the gate insulating film and the organic semiconductor film is formed on the surface of the source and drain electrodes and the surface of the non-electrode region of the gate insulating film functions as a transistor. Generally, the current characteristics are degraded.
In the present invention, the channel length direction means a direction from the source electrode (or drain electrode) toward the drain electrode (or source electrode). The channel width direction described later means a direction orthogonal to the channel length direction.

In the organic thin film transistor of the present invention, the channel length between the source electrode 105 and the drain electrode 106 is G ₁ , and the distance from the end of the source or drain electrode to the end of the organic semiconductor film 104 in the channel length direction Is 1 _S / 2, then the equation (1)
G ₁ ≦ l _S (1)
The relationship holds.
By satisfying this equation (1), the source electrode 105 and the drain electrode 106 in the organic semiconductor film 104 are connected to form a channel region.

  The organic thin film transistor of the present invention is a film in a region where the film thickness of the channel region between the source electrode 105 and the drain electrode 105 and the film thickness at both ends of the organic semiconductor film 104 are in contact with the source and drain electrodes 105 and 106. Another feature is that the thickness is smaller than the thickness. Since the parasitic capacitance is reduced, the switching time is shortened and high-speed operation is possible.

  In the organic thin film transistor of the present invention, as shown in FIG. 1 (d), between the source and drain electrodes 105 and 106, the surface of the organic semiconductor film 104 has inclined surfaces on both sides, and the space between them is substantially flat. However, the surface of the organic semiconductor film 104 in the channel region between the source and drain electrodes 105 and 106 is only substantially flat from the viewpoint of facilitating current flow by shortening the current path in the channel. It is preferable to comprise.

  A plurality of organic thin film transistors having the above-described configuration of the present invention may be provided on the same substrate. That is, an organic semiconductor film is divided and arranged in a plurality of element formation regions on the gate insulating film, and a source electrode and a drain electrode are formed on the surface of the organic semiconductor film in each element formation region to constitute an organic thin film transistor array. May be.

Moreover, you may provide a protective film in the organic thin-film transistor of this invention. The protective film protects the organic thin film transistor from exposure to other processes and from the external environment.
Examples of the constituent material of the protective film include polymers made of polyimide, parylene, undoped polyaniline, photosensitive materials such as polyvinyl alcohol, organic materials such as fluorine-based polymers, and inorganic materials such as SiO ₂ and SiN _x. However, it is not limited to these materials.
The protective film can be formed by a known method depending on the material to be used. When a protective film is formed by a method based on plasma CVD, it is necessary to consider the influence of the substrate temperature on the organic semiconductor film. When a protective layer is formed by a solvent-based method, the solvent is organic. The influence on the semiconductor film must be considered.
The thickness of the protective film can be about 0.1 to 5 μm.

(Method for producing organic thin film transistor)
As shown in FIG. 1B, this organic thin film transistor manufacturing method includes a stacked body S1 having a gate electrode 102 on the surface of a substrate 101 and a gate insulating film 103 on the surface of the gate electrode 102 and the substrate 101. As shown in FIG. 1C, (a) a step of arranging a mask 108 having at least a pair of openings with a gap above the stacked body S1, and (b) at least a channel length direction with respect to the mask 108. The step of forming the organic semiconductor film 104 in the element formation region of the stacked body S1 by irradiating the organic semiconductor material in a slanted manner, and using the mask 108 as shown in FIG. The source electrode 105 and the drain electrode 106 are formed in the element formation region of the stacked body S1 by irradiating the electrode material in a direction substantially perpendicular to And having a degree.

  In the method of manufacturing the organic thin film transistor, if the step (a) is performed before the steps (b) and (c), the order of the steps (b) and (c) is not limited. From the viewpoint of forming an excellent organic thin film transistor, the order in which the step (c) is followed by the step (c) is preferable. In FIG. 1C, an arrow indicates a state where the organic semiconductor film material is irradiated, and in FIG. 1D, an arrow indicates a state where the electrode material is irradiated.

  Moreover, the manufacturing method of this invention should just provide the said process (a)-(c) at least, forms the gate electrode 102 on the surface of the board | substrate 101 as shown to Fig.1 (a), and shows FIG. As shown in b), the method may include a step of forming the stacked body by forming the gate insulating film 103 on the surface of the substrate 101 and the surface of the gate electrode 102. In FIG. 1A, reference numeral 107 denotes a mask for forming the gate electrode 102 in the element formation region, and an arrow indicates a state in which the gate electrode material is irradiated.

  Hereafter, each component and manufacturing method of the organic thin-film transistor of this invention are demonstrated in detail in order of a process substantially.

(substrate)
In the present invention, the substrate is not particularly limited as long as it is insulative, and a substrate with little dimensional change depending on the treatment process is preferable. Specific examples include a synthetic quartz substrate, a glass substrate, a plastic substrate, a silicon substrate, a highly doped silicon substrate with a thermal oxide film, and the like. When a highly doped silicon substrate with a thermal oxide film is used, a gate electrode and a gate insulating film The formation of can be omitted. In order to reduce the substrate cost and obtain a flexible device, a plastic substrate (resin film) having excellent bending properties is preferable. For example, a PEN (polyethylene naphthalate) substrate, PES (polyether) Sulfone) substrate, polyimide substrate, PET (polyethylene terephthalate) substrate and the like.
Although the thickness of a board | substrate changes with constituent materials etc., it can be set as about 0.1-3.0 mm, and 0.5-1.3 mm is preferable when it is going to obtain the device which has flexibility.

(Gate electrode)
The constituent material of the gate electrode is not particularly limited as long as it is a conductive material. Specific examples include conductive organic materials, conductive inks, metals, alloys, conductive metal oxides, inorganic semiconductors and organic semiconductors whose conductivity has been improved by doping, and the like. You may use together. For example, a single layer film of aluminum, a two-layer metal film of titanium and gold, and the like can be given. When the gate insulating film is a silicon nitride film (SiN _x ), titanium is preferable because it has an effect of improving the adhesion between gold and the SiN _x film.

The gate electrode can be formed by a known method depending on a material to be used. For example, if the material is metal, alloy, etc., vacuum deposition method, sputtering method, CVD method, etc. are mentioned. If the material is conductive organic material or conductive ink (polyaniline, polythiophene, etc.), coating method, printing method, etc. Etc.
Although the film thickness of a gate electrode is not specifically limited, It can be set as about 20-400 nm, Preferably it is 50-100 nm.

(Gate insulation film)
Examples of the constituent material of the gate insulating film include insulating plastics such as polyimide and polycarbonate, and silicon compounds such as silicon nitride (Si _x N) and silicon oxide (SiO ₂ ).
The gate insulating film can be formed by a known method depending on a material to be used. For example, if the material is an insulating plastic, a method of thermal curing after application by a coating method, a printing method or the like can be used. If the material is a silicon compound, for example, a plasma CVD method can be given.
The thickness of the gate insulating film is about 10 to 500 nm, preferably 100 to 300 nm. Further, it is preferable that the film thickness between the source and drain electrodes is made thinner than the film thickness under the electrode because low voltage operation becomes possible.

(Organic semiconductor film)
As a constituent material of the organic semiconductor film, π-electron conjugated aromatic compounds, chain compounds, organic pigments, organic silicon compounds, and the like are preferably used, but are not limited thereto. Specifically, pentacene having high field effect mobility can be given.

  As a method for forming the organic semiconductor film, a mask (metal mask) for forming source and drain electrodes is used, and is inclined at least in the channel length direction with respect to the plane of the mask disposed with a gap substantially parallel to the substrate (stacked body). Any method may be used as long as the film is formed by irradiating the organic semiconductor material in a shape. Therefore, the irradiation direction may include an irradiation direction of 90 ° as long as the irradiation direction includes a direction of an irradiation angle smaller than and / or larger than 90 ° with respect to the mask plane. Further, the irradiation direction only needs to be directed to at least the channel length direction, other channel width directions may be included, and may be the entire circumferential direction. Preferably, the organic semiconductor material is irradiated radially (90 ° or less and in the entire circumferential direction). Note that when the irradiation direction is one direction, it is preferable that the layered body is rotated by a turntable at the time of film formation so that the material is relatively irradiated radially.

Specifically, for example, a vapor deposition beam is irradiated radially from an organic semiconductor vapor deposition source by a vacuum vapor deposition method, and the vapor deposition beam is obliquely applied to the mask source / drain electrode forming openings as shown in FIG. By passing the light, the vapor deposition beam also travels outside the pair of openings, and an organic semiconductor layer is formed on almost the entire surface of the element formation region including the channel formation region on the surface of the gate insulating film. At this time, an evaporation source is disposed substantially in parallel with the mask on an extension line connecting both ends of the organic semiconductor film in the channel length direction and the outer ends of the pair of mask openings, and between the pair of openings in the mask. gap length of the G, the channel length direction of the length of the evaporation source l _0, the distance between the gate insulating film and the mask L _S on the substrate surface, and the distance between the mask and the deposition source and L _0, the formula ( 2)
G ≦ l ₀ (L _S / L ₀ ) (2)
The relationship is established.

Other deposition conditions include, for example, about 5 × 10 ⁻⁴ Pa in the vacuum deposition method (resistance heating), and 1 to 1 at a deposition rate of about 0.1 to 0.5 nm / s on a molybdenum (Mo) boat. For example, an organic semiconductor such as pentacene is deposited for about 20 minutes.

(Source electrode and drain electrode)
A constituent material of the source electrode and the drain electrode is not particularly limited as long as it is a conductive material. Specific examples include inorganic semiconductors and organic semiconductors whose conductivity is improved by metals, alloys, conductive metal oxides, doping, and the like.
The source electrode and the drain electrode are formed by irradiating the electrode material in a direction substantially perpendicular to the plane of the mask (metal mask) arranged with a gap substantially parallel to the substrate (stacked body). Any method may be used, but it is preferable to employ the same vapor deposition method as the method for forming the organic semiconductor film because the organic semiconductor film and the source and drain electrodes can be formed in the same film forming apparatus.

  By irradiating a metal material in a direction substantially perpendicular to the mask by a vapor deposition method, source and drain electrodes are formed only in a region almost immediately below the mask opening on the surface of the gate insulating film as shown in FIG. . Also at this time, the relationship of the above-mentioned formula (2) is established. That is, when the organic semiconductor film is formed first, the source and drain electrodes are formed with the mask used in the formation of the organic semiconductor film as it is. On the contrary, when the source and drain electrodes are formed first, the source and drain electrodes are formed after arranging or preparing the mask and the vapor deposition source for organic vapor deposition so that the formula (2) is satisfied. Thereafter, an organic semiconductor film is formed.

As other vapor deposition conditions, in order to irradiate the vapor deposition beam substantially vertically, for example, a substantial point vapor deposition source is used so that wraparound at the mask opening is substantially eliminated, and vacuum vapor deposition (resistance heating) Then, it is mentioned that an electrode is vapor-deposited for about 1 to 20 minutes at a vapor deposition rate of about 0.1 to 0.5 nm / s at about 5 × 10 ⁻⁴ Pa.
In the source and drain electrodes, the film thickness is about 20 to 400 nm, preferably 50 to 100 nm, the width in the channel length direction is about 10 to 500 μm, preferably 50 to 300 μm, and the length in the channel width direction is 0.1 to 50 mm. Preferably it can be set to 1-15 mm.
Further, in order to effectively take up the element area, it is generally performed to use comb-shaped source and drain electrodes (a gate electrode and an organic semiconductor film also correspond to a comb-shaped).

(Explanation about mask)
A source / drain forming mask that is also used for forming an organic semiconductor film is a metal mask in which openings of a predetermined pattern are formed in a metal sheet made of, for example, stainless steel and having a thickness of 20 to 100 μm.
As a mechanism for holding the mask in the film forming apparatus in parallel to the film formation substrate with a predetermined gap, for example, a spacer having a thickness of about 50 to 3000 μm is provided in a portion where the mask is not open or in the periphery. (Formation) and pressing the mask so that it does not move, or by applying unevenness to the part where there is no opening in the mask and the periphery with a press so that the mask does not move as a gap can be adopted.

  When forming the above-described gate electrode, the gate electrode forming mask is held with a predetermined gap in parallel to the deposition target substrate by this mechanism, or the mask is placed on the deposition target substrate without a gap, The gate electrode may be formed by irradiating the gate electrode material in a radial or vertical direction with respect to the mask by an evaporation method. In this way, the gate electrode, the organic semiconductor film, the source and drain electrodes can be formed with the same film forming apparatus. In addition, when a gap is provided between the mask and the deposition target substrate, the substrate is not in contact with the substrate and dust is not easily deposited, so that the yield does not need to be reduced. Further, when irradiated radially, the end portion of the gate electrode becomes tapered, so that the entire element can be shaped without a step, and even if it is curved, peeling does not occur and reliability is improved.

(Deposition system using vapor deposition)
A deposition apparatus using a vapor deposition method includes a mechanism capable of adjusting the position of a substrate, a mask, and / or a deposition source while holding the substrate, a mask, and / or a deposition source in order to establish the relationship of the above formula (2). It is preferable to adjust the distance L _S between the mask and the mask, the distance L ₀ between the mask and the deposition source, or the length l ₀ of the organic semiconductor deposition source. As such a position adjustment mechanism, a method of adjusting the position of the mask with a spacer, adjusting the position of the vapor deposition source with an XYZ stage, or installing a blocking mask for adjusting the length of the vapor deposition source is adopted. Can do.

  Next, the characteristics of the organic thin film transistor and the method for manufacturing the same according to the present invention will be described in more detail with reference to the drawings showing the embodiments. In addition, this invention is not limited to the following embodiment.

(Embodiment 1)
FIG. 2 is a cross-sectional view illustrating a manufacturing process of the organic thin film transistor of the first embodiment. This organic thin film transistor can be manufactured by the following manufacturing method. For the flow of the manufacturing process, refer to FIG.

  First step: The substrate 201 is set in a vacuum apparatus, and a mask is disposed above the substrate 201 in parallel and spaced apart at a predetermined interval, and the material is irradiated radially from a gate electrode deposition source (aluminum) by a vacuum deposition method. Then, an Al thin film is deposited on the substrate 201 to form the gate electrode 202. In this case, the substrate 201 is a polyethylene naphthalate substrate having a thickness of 0.7 mm. The gate electrode 202 has a film thickness of 50 nm at the center, a width of 150 μm in the channel length direction, and a length of 5 mm in the channel width direction. Both end portions in the channel length direction are formed in a tapered shape, and the cross section is substantially trapezoidal. By using polyethylene naphthalate for the substrate 201, a flexible organic thin film transistor can be manufactured.

  Second step: The substrate 201 is taken out from the vacuum apparatus, a polyimide precursor is applied to the surface of the gate electrode 202 and the surface of the substrate 201 by a spin coating method, and a coating film is formed in a closed heater at 180 ° C. for 30 minutes. By curing, a polyimide film having a thickness of 300 nm is formed. As a result, a stacked body S1 in which the gate electrode 202 and the gate insulating film 203 are sequentially stacked on the substrate 201 is formed.

Third step: A vacuum formation using a laminate S1 and a mask 208 having an opening having a pattern shape corresponding to the shape, size, interval, and the like of the source electrode 205 and the drain electrode 206 to be formed in a later step. Install in the membrane device. The mask 208 is made of stainless steel and has a thickness of 50 μm.
In performing this third step, the following conditions are required.
(Condition A)
A mask 208 is arranged in a state of being separated from the gate insulating film 203 on the substrate surface in the stacked body S 1 by a predetermined distance L _S and substantially parallel to the substrate 202.

Fourth step: An organic semiconductor vapor deposition source (pentacene) 209 is disposed on the opposite side of the stacked body S1 so as to sandwich the mask 208, and pentacene is vapor-deposited on the gate insulating film 203 by a vacuum vapor deposition method using the mask 208. A semiconductor film 204 is formed.
This organic semiconductor vapor deposition source 209 has a line shape extending in the channel length direction, a form in which a plurality of point vapor deposition sources are arranged close to each other in a line shape, a surface form, or a plurality of point vapor deposition sources arranged in a plane shape It can be set as the form. In the case of a form other than the planar shape, a plurality of vapor deposition sources may be arranged in parallel in the channel width direction.
In performing this fourth step, the following conditions are required.

(Condition B)
The organic semiconductor vapor deposition source 209 is disposed substantially in parallel with the mask 208 on extension lines j ₁ and j ₂ connecting the ends of both ends of the organic semiconductor film 204 and the outer end of the opening of the mask 208 in the channel length direction. Is done. In this case, the organic semiconductor deposition source 209, the length of the channel length direction so that the distance between the extension line j _1, j _2, is positioned at both ends on the extension line j _1, j _2. Since L ₀ is actually several thousand times larger than L _S , a part of the organic semiconductor vapor deposition source 209 in the channel length direction is omitted in FIG. A part of the space between 209 and the stacked body S1 is omitted.
(Condition C)
The gap length between a pair of openings for forming the source electrode 205 and the drain electrode 206 in the mask 208 is G, the length of the organic semiconductor vapor deposition source 209 in the channel length direction is l ₀ , and the organic semiconductor on the surface of the substrate 201 is used. When the distance between the film 204 and the mask 208 is L _S , and the distance between the mask 208 and the organic semiconductor vapor deposition source 209 is L ₀ , the equation (2)
G ≦ l ₀ (L _S / L ₀ ) (2)
The relationship is established.
(Condition D)
A vapor deposition beam is irradiated radially from the organic semiconductor vapor deposition source 209. At this time, as the vapor deposition source, for example, a vapor beam that radiates in an unspecified direction (radial) is used instead of an irradiation beam that irradiates at least a specific direction from the vapor deposition source.

Fifth step: An electrode evaporation source (gold) 210 is disposed on the opposite side of the stacked body S1 across the mask 208, and the organic semiconductor is formed by vacuum deposition using the mask 208 used in the fourth step as it is. A gold film is deposited on the surface of the film 204 to form a source electrode 205 and a drain electrode 206. The electrode evaporation source 210 can be a substantial point evaporation source or an evaporation source that emits an evaporation beam only in a specific direction.
The following conditions are required when performing this step 5.
(Condition E)
A deposition beam is irradiated from the electrode deposition source 210 in a direction substantially perpendicular to the mask 208.

[Explanation of Formula in Embodiment 1]
Here, the derivation of Expression (2) described in Condition C and the meaning thereof will be described. This formula (2) is the main condition for connecting the organic semiconductor film 204 that is wraparound deposited between the source and drain electrodes, as described above. For convenience of explanation, the range of the opening width in the channel length direction of the mask 208 will be described separately for the first, second and third cases. Note that the term “length and width” simply means the length and width in the channel length direction.

<First case>
First, the opening width w is the formula (a)
w ≧ l ₀ (L _S / L ₀ ) (a)
A case where the above condition is satisfied will be described with reference to FIG.
In FIG. 3, w is the opening width in the channel length direction of the opening of the mask 308 that forms the source / drain electrodes. When the wrap-around deposition is used, the cross-sectional shape of the organic semiconductor film 304 becomes a trapezoid. In FIG. 3, reference numeral 309 represents an organic semiconductor vapor deposition source.
The length l _S of the bottom side of the trapezoidal triangular portion (shaded portion) is expressed by the equation (b) based on the similar relationship between the triangles g and h formed by the extension lines j and j connecting both ends of the base side and the mask opening end. )
l _S = l ₀ (L _S / L ₀ ) (b)
Can be described. In this case, the channel length direction of the length of the portion protruding coupling loop evaporation from the mask 308 in the organic semiconductor film 304 is a half of l _S / 2.
From FIG. 2, the condition that the wrapping organic semiconductor film (length l _S / 2) is connected is as follows:
l _S / 2 ≧ G / 2 That is, l _S ≧ G (c)
It is. Substituting equation (b) into equation (c), equation (1)
G ≦ l ₀ (L _S / L ₀ ) (2)
Is obtained.
In short, the condition for connection is G ≦ l _S / 2 + l _S / 2 = l _S = l ₀ (L _S / L ₀ ).

<Second case>
Next, a second case where the opening width w is smaller than that in the first case will be described with reference to FIG.
In this case, the opening width w is the formula (d)
_{(l 0/2) (L} S / L 0) ≦ w <l 0 (L S / L 0) ··· (d)
Meet.
In the second case, the length of the bottom side of the triangular portion (shaded portion) protruding from the mask 408 in the organic semiconductor film 404 is l _S / 2 as described above. Therefore, from FIG. 2, the expression (2) is similarly obtained as a condition for connecting the wrapping organic semiconductor film (length l _S / 2). In FIG. 4, reference numeral 409 denotes an organic semiconductor vapor deposition source.

<Third case>
Next, a third case where the opening width w is smaller than that in the second case will be described with reference to FIG.
In this case, the opening width w is the formula (e)
_{0 <w <(l 0/} 2) (L S / L 0) ··· (e)
Meet.
Also in the third case, the length of the bottom side of the hatched portion that protrudes from the mask 508 in the organic semiconductor film 504 is l _S / 2 as described above. Therefore, from FIG. 2, the expression (2) is similarly obtained as a condition for connecting the wrapping organic semiconductor film (length l _S / 2). In FIG. 5, reference numeral 509 denotes an organic semiconductor vapor deposition source.

[Example of parameters in Embodiment 1]
Specific numerical examples of the parameters in FIG. 2 in the first embodiment are as follows.
G = 118 μm
l ₀ = 38 mm
L _S = 1.4mm
L ₀ = 250 mm
In this example, the expression (2) of the condition C is satisfied as follows.
That is, since G = 118 μm and l ₀ (L _S / L ₀ ) = 38 mm (1.4 mm / 250 mm) = 213 μm, the expression (2): G ≦ l ₀ (L _S / L ₀ ) is satisfied. is doing.
When each of the above parameters G, l ₀ , L _S and L ₀ satisfies the formula (2), the tapered portion between the source electrode 205 and the drain electrode 206 in the organic semiconductor film 204 is connected to form a channel. The At this time, the thickness of the flat region c of the channel is 50 nm, the thickness of the neighboring regions b and d of the source electrode 205 and the drain electrode 206 is 112 nm, and the region c is formed thinner.

[Structural Features of Organic Thin Film Transistor of Embodiment 1]
The organic thin film transistor of the present invention manufactured by performing the above first to fifth steps has a gate electrode 202, a gate insulating film 203, an organic semiconductor film 204, and source and drain electrodes 205, 206 on a substrate 201 as shown in FIG. Are field effect transistors that can be sequentially formed and whose current can be controlled by a gate voltage, and further have the following structural features.

(1) Since the vapor deposition beam irradiated radially according to the above conditions A to D (particularly conditions C and D) wraps around the outside of the pair of openings of the mask 208 like the extension lines j ₁ and j ₂ , the channel In the longitudinal direction, a region corresponding to the outside of the opening in the organic semiconductor film 204 is formed in a tapered shape, and the end surface of the organic semiconductor film 204 is tapered.
On the other hand, even in the region corresponding to the pair of mask openings in the organic semiconductor film 204, a part is formed in a tapered shape as the distance from the opening is increased, but the portion where the vapor deposition beams that have circulated from the openings overlap is flat. In this way, a channel region having a substantially flat surface and inclined surfaces on both sides thereof is formed. That is, the distance when the channel length between the source electrode 205 and the drain electrode 206 and G _1, the end portions of the source electrode 205 or the drain electrode 206 in the channel length direction to the end tip of the organic semiconductor film 204 l _S Therefore, the relationship G ₁ ≦ l _S is established (see FIG. 2). Note that the channel length G ₁ is substantially equal to the gap length G between the pair of openings of the mask 208, and can be expressed as G ₁ = G.
That is, an organic thin film transistor satisfying the equation (2) when the above parameters (G = G ₁ = 118 μm, l ₀ = 38 mm, L _S = 1.4 mm, L ₀ = 250 mm) is G ₁ = 118 μm <l _S = 213 μm.
(2) Further, as described above, the thickness of the organic semiconductor film 204 is thinner in the non-contact regions a, c, e than in the contact regions b, d with the source and drain electrodes 205, 206.
(3) According to the condition E in addition to the conditions A to C, source and drain electrodes 205 and 206 having substantially the same size as the opening size of the mask 208 and vertical ends are formed.

[Manufacturing effect and structural effect of organic thin film transistor of embodiment 1]
According to the manufacturing method of the first embodiment, when the organic semiconductor film 204 is formed, the organic semiconductor film is formed between the source and drain electrodes by performing wrap-around deposition using the mask 208 for forming the source and drain electrodes 205 and 206. Are connected to form a channel region, and both ends of the organic semiconductor film in the channel length direction are tapered so that they are separated from other regions, and the organic semiconductor film in the organic thin film transistor adjacent to the channel length direction It becomes possible to divide and form each other. That is, element isolation can be performed simultaneously with the formation of the organic semiconductor film. Therefore, it is possible to separate each element as compared with the conventional method which mainly separates each element region, and the leakage current between elements can be reduced. Further, since the shape is tapered, element peeling can be suppressed.
In addition, since the deposition process of the organic semiconductor film 204 and the deposition process of the source and drain electrodes 205 and 206 can be performed in one mask and one vacuum apparatus, the deposition substrate between the two deposition processes can be performed. The transfer device (process) and the mask alignment device (process) are not required, and the manufacturing apparatus is simplified along with the simplification of the manufacturing process.

Further, according to the condition of the gap length G between the openings of the mask 208, the source electrode 205 and the drain electrode 206 can be reliably connected by the channel region of the organic semiconductor film 204. Therefore, an organic thin film transistor can be manufactured at low cost by a simplified manufacturing process and apparatus.
In the organic semiconductor film 204, the thicknesses of the regions b and d near the source electrode 205 and the drain electrode 206 are thicker than the tapered regions a and e and the channel region c in the peripheral part. As a result, the organic thin film transistor of the present invention has a small parasitic capacitance, so that the switching time is shortened and high speed operation is possible.
In addition, since the end of the organic semiconductor film 204 is tapered, device peeling can be suppressed as much as possible compared to a conventional organic semiconductor film having a vertical step, and the lifetime of the organic thin film transistor can be improved. The effect is expected.

  In the manufacturing method of the first embodiment, as shown in FIG. 2, an example in which the cross-sectional shape of the channel between the source electrode 205 and the drain electrode 206 is constituted by a substantially flat portion and an inclined portion is shown. However, depending on conditions, the structure has only a substantially flat portion as shown in FIG. This will be described in the second embodiment.

(Embodiment 2)
FIG. 6 is a cross-sectional view illustrating a manufacturing process of the organic thin film transistor of the second embodiment. The organic thin film transistor of the second embodiment can be manufactured in the same manner as in the first embodiment except that the condition C in the fourth step in the manufacture of the first embodiment is changed to the following condition F. Hereinafter, a different part of Embodiment 2 from Embodiment 1 will be described.

(Condition F)
The gap length between the pair of openings for forming the source electrode 605 and the drain electrode 606 in the mask 608 is G, the length of the organic semiconductor vapor deposition source 609 in the channel length direction is l ₀ , and the organic semiconductor on the surface of the substrate 601 is used. When the distance between the film 604 and the mask 608 is L _S , the distance between the mask 608 and the organic semiconductor vapor deposition source 609 is L ₀ , and the opening width in the channel length direction of the openings of the source and drain electrodes 605 and 606 is w (3)
_{G ≦ (l 0/2)} (L S / L 0) ≦ w / 2 ··· (3)
Or the formula (4)
_{G ≦ (l 0/2)} (L S / L 0) ≦ w <l 0 (L S / L 0) ··· (4)
Or formula (5)
_{0 <w = l 0 (L} S / L 0) -G <(l 0/2) (L S / L 0) ··· (5)
That the relationship holds.
In FIG. 6, reference numeral 602 represents a gate electrode, 603 represents a gate insulating film, and 610 represents an electrode evaporation source.

In Embodiment 2, each of the parameters G, l ₀ , L _S , L ₀ and w satisfies the above formula (3), (4) or formula (5). Between the drain electrodes 705 and 706, the channel region c of the organic semiconductor film 704 is not inclined and has a substantially flat shape. This shape is a feature of the second embodiment.
According to this, the current path in the channel becomes the shortest, and the current flows more easily.

[Explanation of Formula in Embodiment 2]
Here, the derivation of the above formulas (3), (4) and (5) and their meaning will be described. The expressions (3), (4), and (5) are the main conditions for connecting the organic semiconductor film that is wraparound-deposited between the source and drain electrodes and forming a flat shape. For convenience of explanation, the range of the opening width in the channel length direction of the mask will be described separately for the first, second, and third cases similar to the first embodiment. Note that the term “length and width” simply means the length and width in the channel length direction.

<First case>
In the first case, as described in the first embodiment, the opening width w is expressed by the formula (a).
w ≧ l ₀ (L _S / L ₀ ) (a)
Meet.
In this case, as shown in FIG. 7, the length of the substantially flat channel region c in the connecting portion of the organic semiconductor film 704 is 2 × (l _S / 2) −G = l _S −G.
It becomes. When the source and drain electrodes 605 and 606 are deposited on the organic semiconductor film 704 with a substantially parallel deposition beam, if the edges of the electrodes 605 and 606 are present on the substantially flat region c, the channel region The surface of c is composed only of a substantially flat portion (see FIG. 6).
From this, as shown in FIG. 7, the gap length G between the pair of openings of the mask 708 is expressed by the following equation (f).
G ≦ l _S −G (f)
The formula (f) is expressed by the formula (g).
2G ≦ l _S (g)
It can be expressed as
Substituting the equation (b) of the first embodiment into this equation (g), the following equation (h)
_{G ≦ l S / 2 = (} l 0/2) (L S / L 0) ··· (h)
Is obtained. Therefore, from equation (a) and equation (h), equation (3)
_{G ≦ (l 0/2)} (L S / L 0) ≦ w / 2 ··· (3)
Is obtained. This expression (3) is a condition for forming a channel region c that is only substantially flat in the first case.

<Second case>
In the second case, as described above, the opening width w is the formula (d).
_{(l 0/2) (L} S / L 0) ≦ w <l 0 (L S / L 0) ··· (d)
Meet.
In this case, as shown in FIG. 8, only the substantially flat portion of the organic semiconductor film 804 becomes the channel region c according to the formulas (f) to (h) as described above. Therefore, the following formula (4) is obtained from the formula (d) and the formula (h), and this formula (4) is a condition for forming the channel region a that is only substantially flat in the second case.
_{G ≦ (l 0/2)} (L S / L 0) ≦ w <l 0 (L S / L 0) ··· (4)
In FIG. 8, reference numeral 808 represents a mask.

<Third case>
In the third case, as described above, the opening width w is the formula (e).
_{0 <w <(l 0/} 2) (L S / L 0) ··· (e)
Meet.
In this case, as shown in FIG. 9, the channel region c between the source and drain electrodes is substantially flat because the length l _S -G in the channel region c is equal to the bottom length of the tapered portion of the organic semiconductor film 904. This is the case where they are equal and the opening width w of the mask 908 is equal.
That is, the formula (k)
l _S −G = w (k)
It becomes. Here, when the formula (k) is substituted into the formula (b) described in the first embodiment, the formula (m)
w = l _S −G = l ₀ (L _S / L ₀ ) −G (m)
It becomes. Substituting this equation (m) into equation (e), equation (5)
_{0 <w = l 0 (L} S / L 0) -G <(l 0/2) (L S / L 0) ··· (5)
Is obtained under the condition that the substantially flat channel region c is formed in the third case.

[Example of parameters in Embodiment 2]
In the second embodiment, specific numerical examples of the parameters in FIG. 6 that satisfy Expression (3) are as follows.
G = 118 μm
l ₀ = 38 mm
L _S = 1.8mm
L ₀ = 250 mm
w = 300μm
In this example, the expression (3) of the condition C is satisfied as follows.
That is _{G = 118μm, (l 0/} 2) (L S / L 0) = (38mm / 2) (1.8mm / 250mm) = a 137 microns, since it is w / 2 = 150 [mu] m, the formula ( 3): meets the _{G ≦ (l 0/2)} (L S / L 0) ≦ w / 2.
When each of the above parameters G, l ₀ , L _S , L ₀ and w satisfies Expression (3), the source electrode 605 and the drain electrode 606 in the organic semiconductor film 604 are connected to form a substantially flat channel. It is formed. At this time, the thickness of the substantially flat channel region c is 50 nm, the thicknesses of the neighboring regions b and d of the source electrode 205 and the drain electrode 206 are 87.9 nm, and the region c is formed thinner. .

In the second embodiment, specific numerical examples of the parameters in FIG. 6 that satisfy Expression (4) are as follows.
G = 118 μm
l ₀ = 38 mm
L _S = 1.8mm
L ₀ = 250 mm
w = 200 μm
In this example, Expression (4) of Condition C is satisfied as follows.
That is _{G = 118μm, (l 0/} 2) (L S / L 0) = (38mm / 2) (1.8mm / 250mm) = a 137 microns, a _{w = 200μm, l 0 (L} S / L ₀₎ = from a 274Myuemu, equation (4): satisfies G ≦ a _{(l 0/2) (L} S / L 0) ≦ w <l 0 (L S / L 0).
When each of the above parameters G, l ₀ , L _S , L ₀ and w satisfies the formula (4), the source electrode 605 and the drain electrode 606 in the organic semiconductor film 604 are connected to form a substantially flat channel. It is formed. At this time, the thickness of the substantially flat channel region c is 50 nm, the thicknesses of the neighboring regions b and d of the source electrode 205 and the drain electrode 206 are 64.3 nm, and the region a is formed thinner. .

In the second embodiment, specific numerical examples of the parameters in FIG. 6 that satisfy Expression (5) are as follows.
G = 118 μm
l ₀ = 38 mm
L _S = 1.8mm
L ₀ = 350mm
w = 77.4 μm
In this example, Expression (5) of Condition C is satisfied as follows.
That is _{w = 77.4μm, l 0 (L} S / L 0) -G = 38mm × (1.8mm / 350mm) was _{-118μm = 77.4μm, (l 0/} 2) (L S / since L ₀₎ = a 97.7μm, equation (5): 0 <w = l 0 (L S / L 0) -G < meets the _{(l 0/2) (L} S / L 0).
When each of the above parameters G, l ₀ , L _S , L ₀ and w satisfies Expression (5), the source electrode 605 and the drain electrode 606 in the organic semiconductor film 604 are connected to form a substantially flat channel. It is formed. At this time, the thickness of the substantially flat channel region c is 50 nm, the thicknesses of the neighboring regions b and d of the source electrode 205 and the drain electrode 206 are 50 nm, and the region a is formed thinner.

[Structural Features of Organic Thin Film Transistor of Embodiment 2]
(1) Between the channel length G ₁ between the source electrode 605 and the drain electrode 606 and the distance (l _S / 2) from the source and drain electrodes 605 and 606 to the end of the tapered portion, G ₁ ≦ l _S A relationship is established. Note that since the channel length G ₁ is substantially equal to the gap length G between the pair of openings of the mask 608, G ₁ = G.
In the case of the organic thin film transistor satisfying the equation (3) when the above parameters (G = 118 μm, l ₀ = 38 mm, L _S = 1.8 mm, L ₀ = 250 mm, w = 300 μm), G ₁ = 118 μm <l _S = 274 μm.
In the case of the organic thin film transistor satisfying the formula (4) when the above parameters (G = 118 μm, l ₀ = 38 mm, L _s = 1.8 mm, L ₀ = 250 mm, w = 200 μm), G ₁ = 118 μm <l _S = 274 μm.
In the case of the organic thin film transistor satisfying the equation (5) when the above parameters (G = 118 μm, l ₀ = 38 mm, L _S = 1.8 mm, L ₀ = 350 mm, w = 77.4 μm), G ₁ = 118 μm <L _S = 195 μm.
(2) As shown in FIG. 6, the channel region c of the organic semiconductor film 604 is not inclined and has a substantially flat shape.

[Manufacturing effect and structural effect of organic thin film transistor of embodiment 2]
According to the manufacturing method of Embodiment 2, in addition to the effects of Embodiment 1, the following effects are further exhibited.
Since the channel is substantially flat without an inclined portion, the current path between the source electrode 605 and the drain electrode 606 becomes the shortest, and the channel junction (from the interface layer where the channel is accumulated by the gate voltage to form the source and drain) The resistance of the thick portion up to the electrode is also reduced, and there is an effect that current can easily flow.
In addition, since the edges of the source and drain electrodes 605 and 606 are not located at the inclined portion of the organic semiconductor film 604, even if the deposition positions of the electrodes 605 and 606 are slightly shifted in the channel length direction, the change in the device current is small. For example, pixel variations when a plurality of organic thin film transistors are used in a display device can be suppressed, yield can be improved, and cost can be reduced.
Further, similarly, since the edges of the electrodes 605 and 606 are not located in the inclined portion of the organic semiconductor film 604, the thickness of the channel portion hardly changes even if the deposition positions of the electrodes 605 and 606 are slightly shifted in the channel length direction. Thus, variations in the threshold voltage of a plurality of manufactured organic thin film transistors can be suppressed. For example, pixel variations in the case of a display device can be suppressed, yield can be improved, and cost can be reduced.

(Embodiment 3)
In the first and second embodiments, the case of manufacturing one organic thin film transistor has been described. In the third embodiment, the case of manufacturing a plurality of organic thin film transistors will be described.
FIG. 10 is a cross-sectional view for explaining a manufacturing process of the organic thin film transistor of the third embodiment. The organic thin film transistor of the third embodiment can be manufactured in substantially the same manner as in the first and second embodiments, but the following is different from the first and second embodiments. Hereinafter, the points of the third embodiment different from the first and second embodiments will be mainly described.

In the first step, a plurality of gate electrodes 1102 are formed on the surface of the substrate 1101 using a mask having a plurality of openings.
In the second step, a stacked body S2 is formed by forming a gate insulating film 1103 on the surface of each gate electrode 1102 and the substrate 1101.
In the third step, a mask 1108 having a plurality of pairs of openings for forming source and drain electrodes corresponding to each gate electrode 1102 is placed in the vacuum film forming apparatus used in the first step.

In the fourth step, the organic semiconductor film 1104 is separated (separated) from each other in each of the plurality of element formation regions in the stacked body S2 by vacuum deposition through the mask 1108 having a plurality of pairs of openings. Form. At this time, the following is added as a condition.
(Condition G)
In a mask 1108 having a plurality of pairs of openings, source / drain electrode formation openings corresponding to one organic semiconductor film 1104 and source / drain electrodes corresponding to other organic semiconductor films 1104 adjacent in the channel length direction If the distance from the opening for formation is H, Equation (6)
H> l ₀ (L _S / L ₀ ) (6)
The relationship holds.
In the fifth step, source and drain electrodes 1105 and 1106 are formed on the surface of each organic semiconductor film 1104 by vacuum evaporation using the mask 1108.
In FIG. 10, reference numeral 1109 denotes an organic semiconductor vapor deposition source, and 1110 denotes an electrode vapor deposition source.

[Explanation of Formula in Embodiment 3]
Here, the derivation of Expression (6) and its meaning will be described.
As described in Embodiment Mode 1, the length in the channel length direction of the portion of the organic semiconductor film 1104 that protrudes from the mask 1108 and wraps around is 1 _s / 2. Therefore, as shown in FIG. 10, when the opening interval H of the mask 1108 corresponding to the adjacent organic thin film transistor in the channel length direction is larger than (l _S / 2) + (l _S / 2), the deposited organic semiconductor The film 1104 is not connected between elements.
That means
H> (l _S / 2) + (l _S / 2) (n)
It becomes. Substituting the above equation (b) into this equation (n), H> l ₀ (L _S / L ₀ ) (6)
Is obtained. When this equation (6) is satisfied, adjacent elements are divided.

[Example of parameters in Embodiment 3]
Specific numerical values of the parameters in FIG. 10 of the third embodiment are as follows.
G = 118 μm
H = 300μm
l ₀ = 38 mm
L _S = 1.4mm
L ₀ = 250 mm
The above numerical example satisfies the following conditional expression (6).
That is, since H = 300 μm and l ₀ (L _S / L ₀ ) = 38 mm (1.4 mm / 250 mm) = 213 μm, Expression (6): H> l ₀ (L _S / L ₀ ) is satisfied. To do.

[Structural Features of Organic Thin Film Transistor of Embodiment 3]
When the manufacturing method according to Embodiment 3 is used, the structure of the organic thin film transistor is, as shown in FIG. 10, an end tapered region e of the organic semiconductor film 1104 of one organic thin film transistor and the organic semiconductor film of another adjacent organic thin film transistor. The end tapered region a 1104 is disconnected without being connected.

[Manufacturing Effect and Structural Effect of Organic Thin Film Transistor of Embodiment 3]
According to the third embodiment, in addition to the effects of the first and second embodiments, the following effects are further achieved.
Adjacent organic thin film transistors are divided without being connected, and a plurality of organic thin film transistors can be formed at a time. In particular, when a plurality of organic thin film transistors are formed on the same substrate 1201 as shown in FIG. 10 according to the above condition G, the ends (tapered portions) of the organic semiconductor film 1104 in adjacent organic thin film transistors are connected to each other. Can be split without

Further, it is possible to simultaneously perform vapor deposition formation of the plurality of organic semiconductor films 1104 and vapor deposition between elements. That is, conventionally, even if the organic semiconductor film 1104 can be deposited for each element region, it is difficult to separate and deposit each element separately, which causes a leakage current. However, in the present invention, by using one mask 1108 for forming the source electrode 1105 and the drain electrode 1106, first, the organic semiconductor film 1104 can be formed by evaporation, and secondly, the source electrode 1105 and the drain electrode 1106 are evaporated. Third, the elements can be separated. Thus, an integrated organic thin film transistor can be formed while sharing the mask for forming the organic semiconductor film and the mask for forming the source / drain electrodes with one mask, thereby reducing and simplifying the manufacturing process and reducing the organic thin film transistor. There is an effect that it can be formed at a cost.
Further, by separating the organic thin film transistors, there is an effect that the organic semiconductor film 1104 is not shared and leakage current can be suppressed.

  The organic thin film transistor of the present invention uses a vacuum deposition method in which the element performance of the organic semiconductor film is most excellent. By reviewing the manufacturing process and reducing the cost, it is possible to manufacture a flexible device using the highest level of mobility realized in an organic semiconductor as an active element of a display device or an input device. Therefore, since the pixel size can be reduced, it can be used in electronic devices such as electronic paper, flexible scanner, organic EL, and flexible tag, and is particularly suitable for electronic paper and flexible scanner.

It is a figure which shows the manufacturing process flow of the organic thin-film transistor element in embodiment of this invention. It is sectional drawing which shows the manufacturing method of the organic thin-film transistor element of Embodiment 1 of this invention. In Embodiment 1, it is a figure which shows the shape of the organic-semiconductor film vapor-deposited when the opening width of the channel length direction of a mask is 1st. In Embodiment 1, it is a figure which shows the shape of the organic-semiconductor film vapor-deposited when the opening width of the channel length direction of a mask is 2nd. In Embodiment 1, it is a figure which shows the shape of the organic-semiconductor film vapor-deposited when the opening width of the channel length direction of a mask is 3rd. It is sectional drawing which shows the organic thin-film transistor manufacturing method of Embodiment 2 of this invention. In Embodiment 2, it is a figure which shows the shape of the organic-semiconductor film vapor-deposited when the opening width of the channel length direction of a mask is 1st. In Embodiment 2, it is a figure which shows the shape of the organic-semiconductor film vapor-deposited when the opening width of the channel length direction of a mask is 2nd. In Embodiment 2, it is a figure which shows the shape of the organic-semiconductor film vapor-deposited when the opening width of the channel length direction of a mask is 3rd. It is sectional drawing which shows the manufacturing method of the organic thin-film transistor element of Embodiment 3 of this invention.

Explanation of symbols

101, 201, 601, 1101 Substrate 102, 202, 602, 1102 Gate electrode 103, 203, 603, 1103 Gate insulating film 104, 204, 604, 1104 Organic semiconductor film 105, 205, 605, 1105 Source electrode 106, 206, 606, 1106 Drain electrode 107 Mask (for gate electrode formation)
108, 208, 608, 1108 Mask (shared with organic semiconductor film and source / drain electrode formation)
209, 609, 1109 Organic semiconductor deposition source 210, 610, 1110 Electrode deposition source

Claims (15)

  A gate electrode formed on the surface of the substrate, a gate insulating film formed on the surface of the substrate and the surface of the gate electrode, an organic semiconductor film formed in an element formation region on the gate insulating film, a source electrode, and a drain An organic thin film transistor comprising: an electrode, wherein the organic semiconductor film is formed in a tapered shape with a thickness decreasing toward both ends in a channel length direction. In the organic semiconductor film, the channel length between the source electrode and the drain electrode is G ₁ , and the distance from the end of the source or drain electrode to the end of the organic semiconductor film in the channel length direction is l _S / 2. Then, the formula (1)
G ₁ ≦ l _S (1)
The organic thin film transistor according to claim 1, which is configured so that   3. The organic thin film transistor according to claim 1, wherein the organic semiconductor film is formed on the surface of the gate insulating film, and the source and drain electrodes are formed on the surface of the organic semiconductor film.   The organic semiconductor film according to any one of claims 1 to 3, wherein the channel region between the source electrode and the drain electrode and the film thickness at both ends are thinner than the region in contact with the source and drain electrodes. The organic thin-film transistor as described.   The organic thin film transistor according to claim 3 or 4, wherein a surface of the organic semiconductor film is substantially flat between the source and drain electrodes.   The organic semiconductor film is divided and arranged in a plurality of element formation regions on the gate insulating film, and a source electrode and a drain electrode are formed on the surface of the organic semiconductor film in each element formation region. The organic thin-film transistor as described in one.   The organic thin film transistor according to any one of claims 1 to 6, wherein the substrate is a resin film. Using a laminate having a gate electrode on the surface of the substrate and a gate insulating film on the surface of the gate electrode and the substrate,
(A) disposing a mask having at least a pair of openings above the laminate with a gap;
(B) forming an organic semiconductor film in an element formation region of the stacked body by irradiating the mask with an organic semiconductor material at least in a channel length direction;
And (c) forming a source electrode and a drain electrode in an element formation region of the laminate by irradiating an electrode material in a direction substantially perpendicular to the mask using the mask. Manufacturing method.   9. The method of manufacturing an organic thin film transistor according to claim 8, wherein an organic semiconductor film is formed on the surface of the gate insulating film in the step (b), and then a source electrode and a drain electrode are formed on the surface of the organic semiconductor film in the step (c). .   The method for producing an organic thin film transistor according to claim 8 or 9, wherein the organic semiconductor film is formed by irradiating a vapor deposition beam radially from an organic semiconductor vapor deposition source by a vacuum vapor deposition method. On the extension line connecting the both ends of the organic semiconductor film in the channel length direction and the outer ends of the openings of the pair of masks, an evaporation source is disposed substantially parallel to the mask,
The gap length between a pair of openings in the mask is G, the length of the vapor deposition source in the channel length direction is l ₀ , the distance between the gate insulating film on the substrate surface and the mask is L _S , and the distance between the mask and the vapor deposition source. Is L ₀ , formula (2)
G ≦ l ₀ (L _S / L ₀ ) (2)
The manufacturing method of the organic thin-film transistor of Claim 9 or 10 with which these relationships are satisfied. When the width in the channel length direction of the opening for forming the source and drain electrodes in the mask is w, Equation (3)
_{G ≦ (l 0/2)} (L S / L 0) ≦ w / 2 (3)
Or formula (4)
_{G ≦ (l 0/2)} (L S / L 0) ≦ w <l 0 (L S / L 0) (4)
Or formula (5)
_{0 <w = l 0 (L} S / L 0) -G <(l 0/2) (L S / L 0) (5)
The method for producing an organic thin film transistor according to claim 11, wherein the relationship: In the step (b), a mask having a plurality of gate electrodes on the surface of the substrate and a plurality of pairs of openings in a plurality of element formation regions on the stacked body having each gate electrode and a gate insulating film on the surface of the substrate. The organic semiconductor film is divided and formed using
13. The organic thin film transistor according to claim 9, wherein in step (c), a source electrode and a drain electrode are formed on a surface of each organic semiconductor film using the mask having the plurality of pairs of openings. Production method. In a mask having a plurality of pairs of openings, an opening for forming a source / drain electrode corresponding to one organic semiconductor film and a source / drain electrode for forming another organic semiconductor film adjacent to the channel length direction are formed. If the distance from the opening is H, Equation (6)
H> l ₀ (L _S / L ₀ ) (6)
The organic thin film transistor manufacturing method according to claim 13, wherein   Before the step (a), a gate electrode forming mask is disposed above the substrate with a gap, and a gate electrode material is irradiated to form a gate electrode in an element formation region of the substrate. The method for producing an organic thin film transistor according to claim 8, further comprising: forming a stacked body by forming a gate insulating film on the surface of the gate electrode.

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