JP5025110B2 - Method for manufacturing semiconductor device - Google Patents

Description

The present invention relates to a semiconductor device having an organic thin film transistor and a manufacturing method thereof.

In recent years, a technique for forming a thin film transistor (TFT) using a semiconductor thin film (having a thickness of about several to several hundred nm) formed on a substrate having an insulating surface has attracted attention. Thin film transistors are widely applied to electronic devices such as ICs and electro-optical devices, and are particularly urgently developed as switching elements for display devices.

Among TFTs, research on thin film transistors using organic semiconductors (hereinafter referred to as organic TFTs) is underway. Organic TFTs are rich in flexibility because they use organic materials. In addition, since it can be formed at a lower temperature than a TFT using an inorganic semiconductor, a resin material such as plastic can be used for the substrate. As a result, a light and flexible device can be obtained. Furthermore, the organic TFT can be expected not only to simplify the process by the printing method, ink jet method, vapor deposition method, etc., but also can be manufactured at low cost because it can use an inexpensive substrate material, which is advantageous in terms of cost. I can estimate.

Since organic semiconductors are oxidized or decomposed by contact with water or oxygen, there is a demerit that if the organic TFT is left in the atmosphere, the electrical characteristics are deteriorated. Therefore, as in Patent Document 1, an insulating film is formed on a semiconductor layer of an organic TFT, the semiconductor layer is protected by the insulating film, and deterioration due to water, light, or oxygen is suppressed.
JP 2003-324202 A

However, when an insulating film covering the semiconductor layer of the organic TFT is formed, the number of TFT manufacturing steps is increased by one.

Also, when a plurality of organic TFTs of different conductivity types are formed on the same substrate, the semiconductor film of one conductivity type organic TFT previously formed is etched with the other conductivity type semiconductor film formed later. The previously formed semiconductor film must be covered with an insulating film or the like so that it is not etched together. Therefore, a process for forming a new insulating film on the previously formed semiconductor film is required.

On the other hand, when the organic semiconductor layer is formed by etching, there is a step of removing a mask used at the time of etching. Generally, since the mask is made of an organic insulating film such as polyvinyl, it is removed by wet etching. After removing the mask, the surface of the organic semiconductor layer is washed with water in order to wash away the etching agent remaining on the surface of the organic semiconductor layer. Therefore, there is a high possibility that moisture enters the organic semiconductor layer in this step, which is not preferable for the organic semiconductor layer. Further, since both the mask material and the organic semiconductor layer are organic materials, it is difficult to take a large selection ratio with the organic semiconductor material when removing the mask. In order to obtain the selection ratio, it is necessary to use a mask material and an organic semiconductor material capable of obtaining the selection ratio, and there is a limit to the use of the material.

In view of the above problems, an object of the present invention is to simplify a manufacturing process. It is another object of the present invention to provide a method for manufacturing a semiconductor device having a highly reliable organic TFT.

One feature of the present invention is that a semiconductor layer containing an organic material is formed by etching using a mask, and the TFT is completed in a state where the mask is not removed and left on the semiconductor layer. Then, the remaining mask is used to protect the semiconductor layer from deterioration due to water, light, oxygen, or the like.

One of the features of the present invention is that when forming a P-type or N-type organic TFT on the same substrate, first, one of the conductive type semiconductor layers is formed by etching using a mask. Then, the semiconductor layer of the other conductivity type is formed by etching using the mask with the mask remaining on the semiconductor layer. That is, one of the characteristics is that each organic TFT is completed with the mask remaining on each semiconductor layer.

One of the characteristics of the present invention is that a mask formed over a semiconductor layer is formed by a method such as a droplet discharge method with little physical damage to a lower semiconductor layer. In addition, a barrier layer made of an inorganic film is provided between the remaining mask and the semiconductor layer containing an organic material. Note that in this specification, a droplet discharge method is a method of forming a film using an inkjet device or a dispenser device.

According to the present invention, the manufacturing process can be simplified, the organic TFT can be prevented from deterioration due to water, light, or oxygen, and a highly reliable organic TFT can be obtained. In addition, since the mask is not removed, it is not necessary to consider the problem of etchant selectivity in the mask removal step, and materials can be freely selected for both the organic semiconductor material and the mask material.

Further, since there is no mask removal step, it is possible to omit wet etching often used for mask removal and water washing on the surface of the organic semiconductor layer after etching. Therefore, it is possible to omit the process in which water is most likely to enter the organic semiconductor layer, which is very effective in preventing the deterioration of the organic semiconductor layer.

Further, when the present invention is applied to the formation of organic TFTs of different conductivity types, a semiconductor film containing an organic material of the other conductivity type is etched with a mask on the semiconductor layer containing the organic material of one conductivity type. Can do. Therefore, etching on the surface of the semiconductor layer of one conductivity type due to the etching can be prevented, and unnecessary film slippage of the semiconductor layer and physical damage to the semiconductor layer can be prevented.

By providing a barrier layer between the semiconductor layer and the mask, the semiconductor layer can be more reliably protected from water, light, oxygen, and the like from the external environment. Further, even when the mask retains water, the barrier layer can prevent water from entering the semiconductor layer.

The best mode for carrying out the invention will be described below with reference to the drawings. However, the present invention can be implemented in many different modes, and those skilled in the art can easily understand that the modes and details can be variously changed without departing from the spirit and scope of the present invention. Is done. Therefore, the present invention should not be construed as being limited to the description of the embodiment modes. In the drawings, common portions are denoted by the same reference numerals, and detailed description thereof is omitted.

(Embodiment 1)
In this embodiment mode, a method for manufacturing an organic TFT of the present invention will be described with reference to FIGS.

As shown in FIG. 1A, a substrate 101 having an insulating surface is prepared. As the substrate 101, a glass substrate, a quartz substrate, or a substrate formed of an insulating material such as alumina can be used. Further, the substrate may be flexible, or may be a substrate selected from polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polyether sulfone (PES), polycarbonate (PC), polyimide, and the like.

Then, a TFT gate electrode 102 is formed on the substrate 101 using a conductive material, a droplet discharge method, a printing method, an electroplating method, a PVD method (Physical Vapor Deposition), a CVD method (Chemical Vapor Deposition), and vapor deposition. It is formed by a method such as a method. The thickness of the gate electrode 102 is preferably 100 to 500 nm. Note that in the case of using a PVD method, a CVD method, an evaporation method, or the like, the gate electrode 102 is formed by etching into a desired shape after film formation.

Examples of conductive materials include metals such as Ag, Au, Cu, Ni, Pt, Pd, Ir, Rh, W, Al, Ta, Mo, Cd, Zn, Fe, Ti, Si, Ge, Zr, and Ba. Or indium tin oxide (ITO), zinc oxide (ZnO), indium zinc oxide (IZO), zinc oxide added with gallium (GZO), indium tin oxide containing silicon oxide, or organic indium used as a transparent conductive film , Organic tin, titanium nitride (TiN) and the like are used as appropriate. In addition, a conductive layer made of any of these materials may be stacked.

In the case of forming a gate electrode by a droplet discharge method, a composition in which a conductor is dissolved or dispersed in a solvent is used as the composition discharged from the discharge port. As the conductor, a metal of the above conductive material, silver halide fine particles, or the like, or dispersible nanoparticles can be used.

In addition, it is preferable to use what dissolved or disperse | distributed the material of either gold | metal | money, silver, and copper in the solvent considering the specific resistance value as the composition discharged from a discharge outlet. More preferably, low resistance and inexpensive silver or copper may be used. As the solvent, esters such as butyl acetate and ethyl acetate, alcohols such as isopropyl alcohol and ethyl alcohol, organic solvents such as methyl ethyl ketone and acetone may be used.

The viscosity of the composition used for the droplet discharge method is preferably 5 to 20 mPa · s, which is to prevent the composition from being dried and to smoothly discharge the composition from the discharge port. The surface tension is preferably 40 mN / m or less. Note that the viscosity of the composition may be appropriately adjusted according to the solvent to be used and the application. As an example, the viscosity of a composition in which ITO, ZnO, IZO, GZO, indium tin oxide containing silicon oxide, organic indium, organic tin, or the like is dissolved or dispersed in a solvent is 5 to 20 mPa · s, or silver is dissolved in the solvent. The viscosity of the dispersed composition is 5 to 20 mPa · s, and the viscosity of the composition in which gold is dissolved or dispersed in a solvent is 10 to 20 mPa · s.

The diameter of each nozzle depends on the desired pattern shape and the like, but in order to prevent clogging of the nozzle and to produce a high-definition pattern, the diameter of the conductor particles is preferably as small as possible. .1 μm or less is preferable. The composition is formed by a known method such as an electrolytic method, an atomizing method, or a wet reduction method, and its particle size is generally about 0.5 to 10 μm. However, when formed by the gas evaporation method, the nanoparticles protected with the dispersant are as fine as about 7 nm. When the nanoparticles are covered with a coating agent, the nanoparticles are aggregated in the solvent. And stably disperse at room temperature and shows almost the same behavior as liquid. Therefore, it is preferable to use a coating agent.

The step of discharging the composition may be performed under reduced pressure. This is because the solvent of the composition volatilizes until the composition reaches the object to be processed, and the subsequent drying and firing steps can be omitted or shortened. After discharging the solution, one or both of drying and baking steps are performed by laser light irradiation, rapid thermal annealing, a heating furnace, or the like under normal pressure or reduced pressure depending on the material of the solution. The drying and firing steps are both heat treatment steps. For example, the drying is performed at 100 degrees for 3 minutes, and the firing is performed at 200 to 350 degrees for 15 minutes to 120 minutes. Time is different. In order to satisfactorily perform the drying and firing steps, the substrate may be heated, and the temperature at that time depends on the material of the substrate or the like, but is 100 to 800 degrees (preferably 200 to 350 degrees). And By this step, the solvent in the solution is volatilized or the dispersant is chemically removed, and the resin around the conductor particles is cured and shrunk to accelerate fusion and fusion between the conductor particles. The atmosphere for drying or baking is an oxygen atmosphere, a nitrogen atmosphere, or air. In particular, it is preferable to perform the reaction in an oxygen atmosphere in which the solvent in the solution is easily volatilized. However, the binder formed of an organic substance remains in the conductive layer depending on the heating temperature, atmosphere, and time.

In the present embodiment, the gate electrode selectively discharges a solution in which silver particles of several nm are dispersed (hereinafter referred to as “Ag paste”), and is dried and fired to form a conductive layer mainly composed of silver. To do.

Next, a gate insulating film 103 with a thickness of 100 to 400 nm is formed over the gate electrode 102. The gate insulating film 103 can be formed using a single layer or a stacked structure of an insulating film containing silicon nitride, silicon oxide, or other silicon by a thin film formation method such as a plasma CVD method or a sputtering method. In addition, the gate insulating film 103 preferably has a stacked structure of a silicon nitride film (silicon nitride oxide film), a silicon oxide film, and a silicon nitride film (silicon nitride oxide film) from the side in contact with the gate electrode. In this structure, since the gate electrode is in contact with the silicon nitride film or the silicon nitride oxide film, deterioration of the gate electrode due to oxidation can be prevented.

The gate insulating film 103 can be formed using an insulating solution by a droplet discharge method, a coating method, a sol-gel method, or the like. Typical examples of the insulating solution include a solution in which fine particles of inorganic oxide are dispersed, polyimide, polyamide, polyester, acrylic, PSG (phosphorus glass), BPSG (phosphorus boron glass) film, silicate-based SOG (Spin on Glass), alkoxysilicate SOG, polysilazane SOG, and SiO ₂ having a Si—CH ₃ bond represented by polymethylsiloxane can be used as appropriate.

Next, as illustrated in FIG. 1B, the source electrode 104 and the drain electrode 104 ′ are formed over the gate insulating film 103 using a conductive material. The source electrode and the drain electrode can be formed using a material and a formation method similar to those of the gate electrode 102, and the film thickness is preferably in the range of 300 to 800 nm. Here, a solution Ag paste in which silver particles of several nm are dispersed is selectively discharged and dried to form the source electrode 104 and the drain electrode 104 ′.

Next, as shown in FIG. 1C, an organic semiconductor material is used over the source electrode 104 and the drain electrode 104 ′, and a printing method, a spray method, a spin coating method, a droplet discharge method, a vapor deposition method, a CVD method, and the like. Then, the semiconductor film 105 is formed. Since the semiconductor film 105 may be larger than a desired semiconductor layer, the semiconductor film 105 may be formed over the entire surface as shown in FIG. 1C, or a part of the semiconductor film 105 may be formed instead of the entire surface as shown in FIG. It may be formed in a region.

In the case of using a polymer material among organic semiconductor materials, a dipping method, a casting method, a bar coating method, a spin coating method, a spray method, an ink jet method, or a printing method may be used as appropriate. As the organic semiconductor material, an organic molecular crystal or an organic polymer compound material may be used. Specific organic molecular crystals include polycyclic aromatic compounds, conjugated double bond compounds, carotenes, macrocyclic compounds or complexes thereof, phthalocyanines, charge transfer complexes (CT complexes), tetrathiofulvalene: TCNQ complexes, Examples include free radicals, diphenylpiclyhydrazyl, dyes or proteins. Specific examples of the organic polymer compound material include polymers such as a π-conjugated polymer, polyvinyl pyridine, iodine, or a phthalocyanine metal complex. In particular, polyacetylene, polyaniline, polypyrrole, polythienylene, polythiophene derivatives, poly (3-hexylthiophene) [P3HT; a flexible alkyl group at the 3-position of polythiophene, which is a π-conjugated polymer whose skeleton is composed of conjugated double bonds The polymer in which the alkyl group of the polythiophene derivative is a hexyl group], poly (3 alkylthiophene), poly (3docosylthiophene), polyparaphenylene derivative, or polyparaphenylene vinylene derivative is preferably used.

In addition, an organic semiconductor film using a low molecular material may be formed by an evaporation method. For example, a thiophene oligomer film (polymerization degree 6) or a pentacene film may be formed by vapor deposition.

In particular, when the substrate 101 is a large substrate or has high flexibility, it is preferable to form the organic semiconductor film by a method of dropping a solution. Then, the semiconductor film 105 is formed by volatilizing the solvent by natural drying or baking. The thickness of the semiconductor film 105 is preferably 20 to 100 nm, and is 50 nm here.

Then, a mask 106 is formed with a thickness of 400 nm to 2 μm with an insulating material in contact with the semiconductor film 105. The present invention is characterized in that the mask is formed by a method in which there is no physical damage to the semiconductor film 105, that is, by a method of exposing with a photomask after forming by a droplet discharge method, a printing method, or a droplet discharge method. And These mask formation methods are very preferable because physical damage to the semiconductor film 105 is less than that of a plasma method or a sputtering method.

The insulating material is preferably formed using a heat-resistant polymer material, and a polymer having an aromatic ring or a heterocyclic ring in the main chain and containing at least a highly polar heteroatom group in the aliphatic portion can be used. . Typical examples of such a polymer substance include polyvinyl alcohol (PVA), acrylic, siloxane, polyimide, and the like. When a photomask is used as the mask 106, a resin material having photosensitivity, such as an epoxy resin, a phenol resin, a novolac resin, an acrylic resin, a melamine resin, or a urethane resin, is used as an insulating film of the photosensitive resin. In addition, organic materials exhibiting photosensitivity such as benzocyclobutene, parylene, flare, and polyimide can be used. In addition, as a typical positive photosensitive resin, a photosensitive resin having a novolak resin and a naphthoquinonediazide compound as a photosensitive agent can be mentioned, and as a negative photosensitive resin, a base resin, diphenylsilanediol, an acid generator, etc. And a photosensitive resin having When an organic material is used for the mask, its flatness is excellent, so it is difficult to reflect the unevenness of the underlying semiconductor film, the film thickness formed on the mask can be made uniform, and disconnection is prevented. I can do it.

In the case of forming a mask by a droplet discharge method, a composition in which the above insulating material is dissolved or dispersed in a solvent is used as the composition discharged from the discharge port.

Next, the semiconductor film 105 is etched using the mask 106 to form a semiconductor layer 107 as illustrated in FIG. Etching methods include O ₂ ashing and O ₃ ashing. At the time of the etching, when the mask is an organic material, the mask is slightly etched together with the semiconductor layer. However, the thickness of the mask is much thicker than that of the semiconductor layer, and etching of the mask does not cause a problem. Thereafter, the organic TFT is completed while leaving the mask 106 on the semiconductor layer 107 without being removed. After completion of the organic TFT, an insulating film, a passivation film, and the like are formed on the TFT to form a semiconductor device.

Thus, by completing the organic TFT without removing the mask used for etching the semiconductor layer, the number of mask removal steps can be reduced and moisture can be prevented from entering the semiconductor layer due to mask removal. it can. In addition, by leaving the mask on the semiconductor layer, it is possible to prevent physical effects such as deterioration and etching due to light, oxygen, moisture, etc., and the remaining mask functions as a protective film for the organic semiconductor layer. Can be made.

In the above step, the organic TFT was completed by forming the semiconductor layer after forming the source electrode and the drain electrode. However, the semiconductor layer 107 using an organic semiconductor material may be formed after the gate insulating film 103 is formed, and then the source electrode 104 and the drain electrode 104 ′ may be formed. A cross-sectional view of the organic TFT of the present invention formed by this process is shown in FIG.

In the case of FIG. 2, since the mask 106 remains, the contact region between the semiconductor layer 107, the source electrode 104, and the drain electrode 104 'becomes small. Therefore, the semiconductor film is preferably etched in a tapered shape when the semiconductor film is etched. Thereby, the contact region between the semiconductor layer and the source electrode and the drain electrode becomes large, and disconnection of the source electrode and the drain electrode can be prevented.

When the source electrode and the drain electrode are formed after the semiconductor layer is formed, the semiconductor layer may be affected by plasma, vapor deposition, sputtering, or the like when the source electrode and the drain electrode are formed. However, by applying the present invention, since the semiconductor layer is protected by the mask from the influence of plasma, vapor deposition, sputtering, or the like, the semiconductor layer can be prevented from being physically damaged.

(Embodiment 2)
In this embodiment, a method for forming a top gate type organic TFT will be described with reference to FIGS. In FIG. 3, the same reference numerals as those in the first embodiment refer to the description of the first embodiment for the material, the forming method, and the like.

A source electrode 104 and a drain electrode 104 ′ are formed on the substrate 101. Next, a semiconductor film 105 containing an organic material is formed over the substrate 101, the source electrode, and the drain electrode, and a mask 106 is formed in contact with the semiconductor film 105 (FIGS. 3A and 3B).

Next, as illustrated in FIG. 3C, the semiconductor film 105 is etched using the mask 106 to form the semiconductor layer 107. Then, the gate electrode 102 is formed over the mask 106 while leaving the mask 106 without being removed (FIG. 3D). In this embodiment mode, the mask 106 serves as a protective film for the semiconductor layer 107 and also serves as a gate insulating film.

By completing the top gate type organic TFT with the mask 106 left on the semiconductor layer 107 as in this embodiment, the number of steps for forming the gate insulating film is reduced, and a semiconductor such as plasma or sputtering during the formation of the gate insulating film is reduced. The physical influence on the layer 107 can be eliminated. In addition, deterioration of the semiconductor layer 107 due to water, light, oxygen, or the like from the outside can be prevented.

(Embodiment 3)
In this embodiment, a method for forming a first element which is an N-type organic TFT and a second element which is a P-type organic TFT on the same substrate will be described with reference to FIGS. In FIG. 4, for the substrate, gate electrode, gate insulating film, source electrode, drain electrode, mask, semiconductor film, semiconductor layer, and the like having the same reference numerals as those in Embodiment 1, the materials, formation methods, and the like are the same as those in Embodiment 1. Refer to the explanation.

A gate electrode 102a of the first element and a gate electrode 102b of the second element are formed over the substrate 101 in FIG. Next, a gate insulating film 103 is formed over the gate electrode 102a of the first element and the gate electrode 102b of the second element. On the gate insulating film 103, the source electrode 104a and the drain electrode 104a 'of the first element, and the source electrode 104b and the drain electrode 104b' of the second element are formed.

Next, as illustrated in FIG. 4B, a first semiconductor film 105a is formed over the source and drain electrodes of the first and second elements. The first semiconductor film 105a may be either an N-type organic semiconductor material or a P-type organic semiconductor material, but here it is an N-type organic semiconductor material. As a specific N-type organic semiconductor material, any material can be used as long as the completed N-type organic TFT operates. The first semiconductor film 105a may be formed over the entire surface as shown in FIG. 4B, or may be partially formed in a region where an N-type semiconductor layer is formed as shown in FIG. May be.

Next, a first mask 106a is formed over the first semiconductor film 105a, and the first semiconductor film 105a is etched using the first mask to form a semiconductor layer 107a of the first element ( FIG. 4 (C)).

Next, as shown in FIG. 4D, a second semiconductor film 105b made of a P-type organic semiconductor material is formed with the first mask remaining on the semiconductor layer 107a. As the P-type organic semiconductor material, any material can be used as long as the completed P-type organic TFT operates. Here, pentacene is used. A second mask 106b is formed over the second semiconductor film 105b, and the second semiconductor film is etched using the second mask. At this time, since the first mask 106a remains over the semiconductor layer 107a, physical damage to the semiconductor layer 107a that occurs during etching of the second semiconductor film can be prevented.

As described above, the semiconductor layer 107b of the P-type organic TFT which is the second element is formed, and the first element and the second element are completed, and the N-type organic TFT and the P-type organic TFT are formed on the same substrate. Can be formed (FIG. 4E). A CMOS (complementary metal-oxide semiconductor) circuit may be configured by the N-type organic TFT and the P-type organic TFT formed in this embodiment.

When N-type and P-type organic TFTs are formed on the same substrate, a process for forming an N-type organic semiconductor layer and a process for forming a P-type organic semiconductor layer must be provided separately. For this reason, the organic semiconductor layer of one conductivity type previously formed may be physically damaged. In addition, since either organic semiconductor layer contains an organic material, there is no great difference in etching rate, and at the same time as the etching at the time of forming the other organic semiconductor layer, one conductive type organic semiconductor layer formed earlier is greatly etched. There was also.

However, in the present invention, the organic semiconductor layer formed earlier is protected by the mask remaining thereon, so that the physical influence of etching of the organic semiconductor layer formed later can be reduced. Further, since the mask used at the time of etching can be used as it is as a protective film, the mask removing step can be omitted without increasing the number of new steps, and the number of manufacturing steps can be greatly reduced. In addition, the mask functioning as a protective film can prevent light, heat, oxygen, and the like from entering the organic semiconductor layer, and a highly reliable organic TFT can be provided.

In this embodiment mode, as shown in FIG. 1 of Embodiment Mode 1, the step of forming the organic semiconductor layer after forming the source electrode and the drain electrode has been described. However, as shown in FIG. 2, the source electrode and the drain electrode may be formed after forming the semiconductor layer, or the N-type and P-type organic TFTs may be formed in the top gate type structure of the second embodiment. Needless to say.

(Embodiment 4)
In this embodiment mode, an N-type organic TFT and a P-type organic TFT constituting one pixel of an electroluminescence (EL) display device will be described with reference to FIGS. In FIGS. 5-7, about the code | symbol similar to Embodiment 1-3, the material, the formation method, etc. refer to the description location of Embodiment 1-3.

First, the gate electrode 102 a of the first element is formed over the substrate 101. The first element may be either an N-type organic TFT or a P-type organic TFT, but here it is an N-type organic TFT. Next, a gate insulating film 103a, a source electrode 104a, and a drain electrode 104a 'are formed over the gate electrode 102a of the first element (FIG. 5A). Then, a first semiconductor film 105a containing an N-type organic semiconductor material and a first mask 106a are formed (FIG. 5B). Although the first semiconductor film 105a is partially formed here, it may be formed over the entire surface.

The first semiconductor film is etched using the first mask to form the semiconductor layer 107a containing the N-type organic material of the first element. At this stage, a first element including the gate electrode 102a, the gate insulating film 103a, the source electrode 104a and the drain electrode 104a ', and the semiconductor layer 107a containing an organic material is formed (FIG. 5C).

Next, as shown in FIG. 5D, a second element which is a P-type organic TFT is formed. First, a gate insulating film 103b, a source electrode 104b and a drain electrode 104b ', a second semiconductor film 105b containing a P-type organic semiconductor material, and a second mask 106b are sequentially formed. Although the second semiconductor film 105b is partially formed here, it may be formed over the entire surface. Then, the second semiconductor film is etched using the second mask to form the semiconductor layer 107b containing the P-type organic material of the second element. Through the above steps, an N-type organic TFT 601 and a P-type organic TFT 602 are formed (FIG. 6A).

Next, as illustrated in FIG. 6B, an insulating film 603 is formed. The insulating film may be an inorganic film or an organic film. Subsequently, a wiring 604 connected to the drain electrode 104b 'of the P-type organic TFT 602 is formed, and a conductive layer 605 is formed so as to be connected to the wiring. Next, an insulating layer 606 to be a bank is formed, and an electroluminescent layer 607 and a conductive layer 608 are stacked so as to be in contact with the conductive layer 605. In the above structure, since the TFT for driving the light emitting element is a P-type organic TFT, the conductive layer 605 corresponds to an anode and the conductive layer 608 corresponds to a cathode. Then, light from the light emitting element is emitted to the substrate 101 side and has a bottom emission structure. However, the structure of the EL element in this embodiment mode is not limited to the structure of the EL element exemplified in this embodiment mode as long as it emits light using the N-type organic TFT 601 and the P-type organic TFT 602.

Through the above steps, a display device for driving an EL element with P-type and N-type organic TFTs is completed. By manufacturing a display device by the method of this embodiment mode, the drain electrode 104a 'of the first element can also serve as the gate electrode of the second element. That is, the drain electrode 104a 'is formed in the same layer as the gate electrode of the second element and is further integrated. Therefore, the contact process of the drain electrode of the first element and the gate electrode of the second element can be omitted, and the process can be shortened.

In this embodiment mode, both the first element and the second element have a bottom gate structure. However, the present invention is not limited to this, and the first element is a top gate type and the second element is a bottom gate type. good. Even in this case, one of the source electrode and the drain electrode of the first element can also serve as the gate electrode of the second element.

A top view of a pixel portion of a display device manufactured in this embodiment mode is shown in FIG. 7A, and a circuit diagram thereof is shown in FIG. 6B is a cross-sectional view of the pixel portion of the display device in FIG. 7A cut along A-A ′. Reference numeral 701 shown in FIG. 7B denotes an EL element, which includes the conductive layers 605 and 608 and the electroluminescent layer 607 in FIG.

This embodiment can be combined with Embodiments 1 to 3 within a feasible range.

(Embodiment 5)
In this embodiment, a structure in which a barrier layer is provided between the organic semiconductor layer of Embodiments 1 to 4 and a mask serving as a protective film thereof will be described with reference to FIG.

As shown in FIG. 8A, until the source electrode and the drain electrode of the bottom gate TFT are formed on the substrate, they are formed in the same manner as in FIGS. 1A to 1B of the first embodiment. Then, after forming the semiconductor film 105 containing an organic material, the inorganic film 801 is formed in contact with the semiconductor film 105. The inorganic film is formed of a silicon oxide film, a silicon nitride film, a silicon oxynitride film, or a stacked film including at least two of these. As a method for forming the inorganic film, a CVD method, a sputtering method, a vapor deposition method, a droplet discharge method, a printing method, or the like can be used. In view of physical damage to the semiconductor film, a method for forming the inorganic film 801 is preferably a droplet discharge method, a printing method, or the like.

Next, a mask 106 is formed in contact with the inorganic film 801, and the inorganic film 801 and the semiconductor film 105 are etched using the mask 106 as shown in FIG. 8B. First, the inorganic film 801 is etched using the mask 106, and then the semiconductor film 105 is etched using the mask 106. By the etching, an organic TFT having a barrier layer 802 between the semiconductor layer 107 and the mask 106 is completed. By providing this barrier layer, in addition to the mask, the barrier layer also functions as a protective film for the semiconductor layer, so that the semiconductor layer can be more reliably protected from water, light, and oxygen.

Since the mask 106 is generally formed using an organic material, the mask itself may absorb and retain water. However, by providing the barrier layer between the mask and the semiconductor layer, even if the mask retains water, the barrier layer can prevent moisture from being immersed in the semiconductor layer. Therefore, a more reliable organic TFT can be provided. Further, since the barrier layer can be etched using the mask 106, the number of manufacturing steps does not increase so much.

Although the present embodiment has been described using the bottom gate type organic TFT shown in FIG. 1, it goes without saying that the present embodiment can also be applied to the bottom gate type organic TFT of FIG. 2 and the top gate type organic TFT of FIG. This embodiment can be combined with Embodiments 1 to 4 as far as practicable.

(Embodiment 6)
In this embodiment mode, a structure for suppressing deterioration of the organic semiconductor layer due to water, organic gas, or the like entering from the substrate side will be described with reference to FIG.

In this embodiment, a barrier layer 901 is provided between the substrate and the organic TFT. This barrier layer may be formed of silicon nitride not containing hydrogen formed by a high-frequency sputtering method or a multilayer film of the silicon nitride and silicon oxide film. The barrier layer 901 may be formed on the entire surface of the substrate as shown in FIG. 9A, or selectively formed only on the portion where the organic TFT is formed on the upper portion as shown in FIG. 9B. You may do it. After forming the barrier layer 901, the organic TFT 902 described in Embodiments 1 to 5 is formed on the barrier layer.

This barrier layer becomes a barrier layer for water vapor or organic gas entering from the substrate side, and can prevent the organic semiconductor material or the like from being deteriorated by water vapor or organic gas. In addition, when the structure in which the barrier layer is provided between the semiconductor layer and the mask described in Embodiment 5 is applied to this embodiment, water vapor and organic gas from above and below the organic semiconductor layer can be prevented.

This embodiment can be combined with Embodiments 1 to 5 within a feasible range.

(Embodiment 7)
In this embodiment, an example in which an organic TFT of the present invention is formed using an organic material will be described with reference to FIGS. First, as illustrated in FIG. 10A, a substrate 1001 having an insulating surface is prepared. The substrate 1001 may be any material having flexibility and translucency, such as polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polyethersulfone (PES), polycarbonate (PC), polyimide, and the like. Selected. The practical thickness of the substrate 1001 is 10 to 200 μm.

Then, a first conductive film functioning as a gate electrode 1002 of the TFT is formed over the substrate 1001 using a conductive paste. As the conductive paste, conductive carbon paste, conductive silver paste, conductive copper paste, conductive nickel, or the like is used, and a predetermined pattern is formed by a screen printing method, a roll coater method, or a droplet discharge method. After the conductive paste is formed into a predetermined pattern, it is cured at 100 to 200 ° C. after leveling and drying.

Next, an insulating film functioning as the gate insulating film 1003 is formed over the gate electrode 1002. Note that the first insulating film is formed using a roll coater method, a spray method, or the like to which an acrylic resin, a polyimide resin, a polyamide resin, a phenoxy resin, a non-aromatic polyfunctional isocyanate, or a melamine resin is added. . The gate insulating film is preferably formed to a thickness of about 100 to 200 nm in consideration of the gate voltage.

After that, a second conductive film functioning as the source electrode 1004 and the drain electrode 1004 ′ is formed over the gate insulating film 1003. As a material of the second conductive film, since a material that transports charges in many organic semiconductor materials is a p-type semiconductor that transports holes as carriers, a work function is required to make ohmic contact with the semiconductor layer. It is desirable to use a large metal. Specifically, a conductive paste containing a metal or an alloy material such as gold, platinum, chromium, palladium, aluminum, indium, molybdenum, or nickel is formed by a droplet discharge method, a printing method, or a roll coater method.

Thereafter, an organic semiconductor film is formed. In the case of using a high molecular weight material among the organic semiconductor films, a dipping method, a casting method, a bar coating method, a spin coating method, a spray method, a droplet discharge method, or a printing method may be used as appropriate. As the organic semiconductor material, an organic molecular crystal or an organic polymer compound material may be used. Specific organic molecular crystals include polycyclic aromatic compounds, conjugated double bond compounds, carotenes, macrocyclic compounds or complexes thereof, phthalocyanines, charge transfer complexes (CT complexes), tetrathiofulvalene: TCNQ complexes, Examples include free radicals, diphenylpiclyhydrazyl, dyes or proteins. Specific examples of the organic polymer compound material include polymers such as a π-conjugated polymer, polyvinyl pyridine, iodine, or a phthalocyanine metal complex. In particular, polyacetylene, polyaniline, polypyrrole, polythienylene, polythiophene derivatives, poly (3-hexylthiophene) [P3HT; a flexible alkyl group at the 3-position of polythiophene, which is a π-conjugated polymer whose skeleton is composed of conjugated double bonds The polymer in which the alkyl group of the polythiophene derivative is a hexyl group], poly (3 alkylthiophene), poly (3docosylthiophene), polyparaphenylene derivative, or polyparaphenylene vinylene derivative is preferably used.

An organic semiconductor film using a low molecular material may be formed by an evaporation method. For example, a thiophene oligomer film (polymerization degree 6) or a pentacene film may be formed by vapor deposition.

In particular, in the case of a large substrate or when the substrate is flexible, it is preferable to form the organic semiconductor film by a method of dropping a solution. Then, as shown in FIG. 10B, the solvent is volatilized by natural drying or baking to form a semiconductor film 1005 containing an organic material.

Then, an insulating layer to be the mask 1006 is formed in contact with the semiconductor film 1005. The mask may be formed by a droplet discharge method or a printing method, or may be further exposed by a photomask after being formed by the droplet discharge method, and the mask shape may be adjusted. These mask formation methods are preferable because physical damage to the semiconductor film is less than that of a plasma method or a sputtering method. As a material for the insulating layer, it is preferable to use a heat-resistant polymer material, and a polymer having an aromatic ring or a heterocyclic ring as a main chain and containing at least a highly polar heteroatom group in an aliphatic portion is used. Can do. Typical examples of such a polymer substance include polyvinyl alcohol (PVA), acrylic, siloxane, polyimide, and the like. When used as a photomask, a resin material exhibiting photosensitivity such as an epoxy resin, a phenol resin, a novolac resin, an acrylic resin, a melamine resin, or a urethane resin is used as an insulating film of the photosensitive resin. In addition, organic materials exhibiting photosensitivity such as benzocyclobutene, parylene, flare, and polyimide can be used. Moreover, as a typical positive type photosensitive resin, there can be mentioned a novolak resin and a photosensitive resin having a naphthoquinonediazide compound as a photosensitive agent, and as a negative type photosensitive resin, a base resin, diphenylsilanediol, an acid generator and the like The photosensitive resin which has.

After that, as illustrated in FIG. 10C, the semiconductor film 1005 containing an organic material is etched using a mask 1006 to form a semiconductor layer 1007 containing an organic material. The organic TFT is completed while leaving the mask 1006 on the semiconductor layer 1007 without removing it. After completion of the organic TFT, an insulating film, a passivation film, and the like are formed on the TFT to manufacture a semiconductor device.

As described above, the organic TFT formed entirely of an organic compound material is light and a flexible semiconductor device can be obtained. Further, it can be formed using an inexpensive organic material, and further, the utilization efficiency of the material can be increased, and the cost of the semiconductor device can be reduced. In the manufacturing process, it is not necessary to use a vacuum apparatus, and the apparatus cost can be reduced.

In addition, this embodiment can be combined with Embodiments 1 to 6 within a feasible range.

(Embodiment 8)
A method for manufacturing a display panel in the display device of the present invention will be described with reference to FIGS. In FIG. 11, the same reference numerals as those in the first to seventh embodiments are referred to the description of the first to seventh embodiments for the material, the formation method, and the like.

First, a method for manufacturing a liquid crystal display panel is described with reference to FIG. The organic TFT 1101 as formed in Embodiments 1 to 4 is formed on the substrate 101, the pixel electrode 1102 is formed so as to be connected to the drain electrode 104 ′ included in the organic TFT 1101, and an alignment film is formed on the pixel electrode 1102. 1103 is formed. Then, a substrate 1108 provided with a color filter 1107, a counter electrode 1106, and an alignment film 1105 is prepared, and the substrate 101 and the substrate 1108 are bonded to each other with a sealant (not shown). After that, when the liquid crystal 1104 is injected, a display device having a display function is completed. Polarizing plates 1100 and 1109 are attached to the substrates 101 and 1108. Note that the alignment films 1103 and 1105 and the liquid crystal 1104 are preferably formed by a droplet discharge method in order to further reduce manufacturing time and manufacturing cost.

Next, a method for manufacturing a display panel in a display device including a light-emitting element will be described with reference to FIG. An organic TFT 1101 as formed in the first to fourth embodiments is formed on the substrate 101, and an insulating layer 1110 is formed on the organic TFT 1101. Next, a wiring 1111 connected to the drain electrode 104 ′ included in the organic TFT 1101 is formed, and a conductive layer 1112 is formed so as to be connected to the wiring. Subsequently, an insulating layer 1113 serving as a bank is formed, and an electroluminescent layer 1114 and a conductive layer 1115 are stacked so as to be in contact with the conductive layer 1112. In the above configuration, when the organic TFT 1101 for driving the light emitting element is an N-type organic TFT, the conductive layer 1112 corresponds to a cathode and the conductive layer 1115 corresponds to an anode. Then, a display device that performs so-called top emission, in which light emitted from the light emitting element is emitted to the side opposite to the substrate 101 is completed. If the organic TFT 1101 for driving the light emitting element is a P-type organic TFT, the conductive layer 1112 corresponds to an anode and the conductive layer 1115 corresponds to a cathode. Then, light emitted from the light emitting element is emitted to the substrate 101 side to be a display device that performs bottom emission.

It is needless to say that the display panel shown in this embodiment mode is merely one embodiment, and display panels having various other structures can be manufactured. This embodiment can be combined with Embodiments 1 to 7 as far as practicable.

(Embodiment 9)
This embodiment will be described in detail with reference to FIG. The display device according to this embodiment includes, for each pixel, an electronic ink composed of a contrast medium whose reflectance is changed by application of an electric field or a microcapsule containing charged particles whose reflectance is changed by application of an electric field. The pixel unit includes an organic TFT that controls an electric field applied to the pixel.

12A is a vertical cross-sectional view illustrating the structure of the pixel portion, and FIG. 12B is a top view. Between the plastic substrates 1201 and 1202, there is an organic TFT 1203 using an organic semiconductor layer as described in the first to seventh embodiments. In addition, an electronic ink layer 1209 including microcapsules 1206 containing charged particles is disposed between a pixel electrode 1204 electrically connected to each organic TFT and a common electrode 1205 on the opposite side. The insulating films 1210 to 1212 are formed of an insulating material, and the wiring 1213 electrically connects the pixel electrode 1204 and the organic TFT 1203. Note that the longitudinal sectional view shown in FIG. 12A corresponds to the A-A ′ line shown in FIG.

At least one of the plastic substrates 1201 and 1202 has translucency, and is selected from polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polyethersulfone (PES), polycarbonate (PC), polyimide, and the like. Preferably it has flexibility and its practical thickness is 10 to 200 μm. Of course, it may be thicker than this and does not essentially affect the structure of the present invention.

On the surfaces of the plastic substrates 1201 and 1202, barrier layers 1207 and 1208 are formed with an inorganic insulator material with a thickness of 10 to 200 nm. This is an AlO _X N _1-X (where x = 0.01 to 20 atomic%) film or a layer made of silicon nitride not containing hydrogen formed using silicon as a target and high-frequency sputtering using nitrogen as a sputtering gas. Or a laminated structure including any of these. This inorganic insulating material is densely formed and used as a barrier layer of water vapor or organic gas entering from the external environment. The purpose of forming the barrier layer is that the organic semiconductor material, the contrast medium whose reflectivity is changed by application of an electric field, or the microcapsule containing charged particles whose reflectivity is changed by application of an electric field is deteriorated by water vapor or organic gas. This is to prevent it.

This embodiment can be combined with Embodiments 1 to 8 as far as practicable.

(Embodiment 10)
As an example of an electronic device manufactured by applying the present invention, a digital camera, a sound reproduction device such as a car audio, a personal computer, a game device, a portable information terminal (a mobile phone, a portable game machine, etc.), a home game machine An image reproducing apparatus provided with a recording medium such as Specific examples of these electronic devices are shown in FIGS.

FIG. 13A illustrates a television receiver, which includes a housing 9501, a display portion 9502, and the like. FIG. 13B illustrates a monitor for a personal computer, which includes a housing 9601, a display portion 9602, and the like. FIG. 13C illustrates a personal computer, which includes a housing 9801, a display portion 9802, and the like. The present invention is applied to manufacture of a display portion of the electronic device. Since the organic TFT of the present invention has little deterioration and high reliability, a display device with little display deterioration can be provided. Further, it can be formed using an inexpensive organic material, and the manufacturing process does not need to use an expensive vacuum device by using a printing method or a droplet discharge method, so that these electronic devices can be manufactured at low cost.

FIG. 14A illustrates a mobile phone of mobile terminals, which includes a housing 9101, a display portion 9102, and the like. FIG. 14B illustrates a PDA of portable terminals, which includes a housing 9201, a display portion 9202, and the like. FIG. 14C illustrates a video camera, which includes display portions 9701 and 9702 and the like. The present invention is applied to manufacture of a display portion of the electronic device. Since the organic TFT of the present invention has little deterioration and high reliability, a display device with little display deterioration can be provided. Since the electronic device is a portable terminal, its screen is relatively small. Therefore, it is preferable to reduce the size by mounting a driving circuit using a thin film transistor using a polycrystalline semiconductor channel, a functional circuit such as a CPU, and multilayer wiring on the same substrate as the display portion. The organic TFT of the present invention can be formed using an inexpensive organic material, and the manufacturing process does not need to use an expensive vacuum device by using a printing method or a droplet discharge method. be able to. Further, since the electronic device is a mobile terminal, a display portion using a light-emitting element is preferably used in order to achieve added value in terms of thinness, lightness, and small size. This embodiment can be freely combined with the above-described embodiment as long as practicable.

8A to 8D illustrate a manufacturing process of a semiconductor device of the present invention. It is a figure explaining the semiconductor device of the present invention. 8A to 8D illustrate a manufacturing process of a semiconductor device of the present invention. 8A to 8D illustrate a manufacturing process of a semiconductor device of the present invention. 8A to 8D illustrate a manufacturing process of a semiconductor device of the present invention. 8A to 8D illustrate a manufacturing process of a semiconductor device of the present invention. It is a top view and a circuit diagram of a display device of the present invention. 8A to 8D illustrate a manufacturing process of a semiconductor device of the present invention. It is a figure explaining the semiconductor device of the present invention. 8A to 8D illustrate a manufacturing process of a semiconductor device of the present invention. It is a figure of a display device using the present invention. It is a figure of the display apparatus which has electronic ink using this invention. It is a figure of the electronic device which provided the semiconductor device of this invention. It is a figure of the electronic device which provided the semiconductor device of this invention.

Explanation of symbols

101 Substrate 102 Gate electrode 103 Gate insulating film 104 Source electrode 104 'Drain electrode 105 Semiconductor film 106 Mask 107 Semiconductor layer

Claims (9)

Forming a gate electrode over a substrate having an insulating surface;
Forming a gate insulating film on the gate electrode;
Forming a semiconductor film containing an organic material on the gate insulating film;
Forming an inorganic film on the semiconductor film;
Forming a mask on the inorganic film;
Etching the inorganic film with the mask forms a barrier layer made of the inorganic film, and then etching the semiconductor film with the mask to form a semiconductor layer with a tapered end. ,
A method for manufacturing a semiconductor device, wherein a source electrode and a drain electrode are formed over the mask, the barrier layer, the semiconductor layer, and the gate insulating film while leaving the mask. Forming a first barrier layer over a substrate having an insulating surface;
Forming a gate electrode on the first barrier layer;
Forming a gate insulating film on the gate electrode;
Forming a semiconductor film containing an organic material on the gate insulating film;
Forming an inorganic film on the semiconductor film;
Forming a mask on the inorganic film;
Etching the inorganic film using the mask to form a second barrier layer made of the inorganic film, and then etching the semiconductor film using the mask to form a semiconductor layer having a tapered end portion Form the
A method for manufacturing a semiconductor device, wherein a source electrode and a drain electrode are formed over the mask, the second barrier layer, the semiconductor layer, and the gate insulating film while leaving the mask. In claim 1 or claim 2,
The method for manufacturing a semiconductor device, wherein the source electrode and the drain electrode are in contact with a tapered end portion of the semiconductor layer. Forming a source electrode and a drain electrode on a substrate having an insulating surface;
Forming a semiconductor film containing an organic material on the source electrode and the drain electrode;
Forming an inorganic film on the semiconductor film;
Forming a mask on the inorganic film;
Etching the inorganic film using the mask to form a barrier layer made of the inorganic film, and then etching the semiconductor film using the mask to form a semiconductor layer,
A method for manufacturing a semiconductor device, comprising forming a gate electrode over the mask while leaving the mask. Forming a first barrier layer over a substrate having an insulating surface;
Forming a source electrode and a drain electrode on the first barrier layer;
Forming a semiconductor film containing an organic material on the source electrode and the drain electrode;
Forming an inorganic film on the semiconductor film;
Forming a mask on the inorganic film;
Etching the inorganic film using the mask to form a second barrier layer made of the inorganic film, and then etching the semiconductor film using the mask to form a semiconductor layer,
A method for manufacturing a semiconductor device, comprising forming a gate electrode over the mask while leaving the mask. In claim 1 or the claim 4, wherein the barrier layer is a silicon oxide film, a silicon nitride film, a silicon oxynitride film or a semiconductor device which is a laminated film composed of at least two layers of these, Manufacturing method. In claim 2 or the claims 5, wherein the first barrier layer, a method for manufacturing a semiconductor device, wherein the hydrogen and silicon or the silicon nitride nitride not containing a laminated film of a silicon oxide film. Features claim 2, in claim 5 or claim 7, wherein the second barrier layer, a silicon oxide film, a silicon nitride film, a silicon oxynitride film or that the laminated film composed of at least two layers of these, A method for manufacturing a semiconductor device. In any one of claims 1 to 8, wherein the mask is a method for manufacturing a semiconductor device characterized by being formed by a droplet discharge method.

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