JP2010219155A - Semiconductor element, semiconductor device, method of manufacturing semiconductor element, and method of manufacturing semiconductor device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of converting a charge type of an organic semiconductor in a specified region. <P>SOLUTION: The method of manufacturing an organic semiconductor element whose semiconductor layer is an organic compound layer formed of an oligothiophene compound having a quinoid structure, wherein the method includes a step of changing n-type characteristics, p-type characteristics or bipolar-type characteristics of the organic compound layer into different characteristics among n-type characteristics, p-type characteristics, and bipolar-type characteristics by subjecting the organic compound layer to one of thermal processing, light irradiation processing, and solvent processing. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a semiconductor element and a semiconductor device using an organic semiconductor, and a manufacturing method thereof.

  Organic semiconductor elements such as transistors and diodes using organic compounds can be manufactured with lower energy consumption than those using inorganic substances such as silicon, and light and thin elements can be manufactured. Therefore, in recent years, organic semiconductor elements such as transistors and diodes using organic compounds, and logic gates using these have attracted attention.

  Examples of organic compounds having semiconductor characteristics include a plurality of oligothiophene compounds having a quinoid structure in a report by Janzen et al. (See Non-Patent Document 1). A compound called DCMQ in Non-Patent Document 1 has been previously reported by Higuchi et al. (See Non-Patent Document 2).

D. E. Janzen et. Al., J. Am. Chem. Soc., 2004, 126, 15295-15308 H. Higuchi et. Al., Bull. Chem. Soc. Jpn., 1995, 68, 2363-2377

  By the way, by combining organic transistors, logic gates such as NAND, NOR, and NOT, which are skeletons of computers and the like, can be manufactured. A NOT can be produced from two bipolar organic transistors even if it operates to some extent. However, in order to produce a logic gate having a sufficient function, it is necessary to combine organic transistors having different charge types with semiconductor characteristics such as p-type, n-type, and bipolar types. The charge type is mainly determined by the organic compound and the source / drain electrodes used. Therefore, when creating a logic gate using an organic transistor, two types of organic compound layers or two different types of electrode materials are used. Need to use. In other words, it is usually impossible to produce a logic gate with a single organic compound and a single source / drain electrode. This leads to an increase in manufacturing processes and materials.

  The present invention has been made in view of the above problems, and an object thereof is to provide a method for converting the charge type of an organic semiconductor in a specific region.

  In order to solve the above problems, a method for manufacturing a semiconductor device according to the present invention is a method for manufacturing a semiconductor device in which the semiconductor layer is an organic compound layer formed of a compound represented by the following general formula (1). Then, the organic compound layer is subjected to at least one of heat treatment, light irradiation treatment and solvent treatment, so that the n-type characteristic, p-type characteristic or bipolar characteristic of the organic compound layer is obtained. Is changed to another characteristic of the n-type characteristic, the p-type characteristic, and the bipolar characteristic.

(In Formula (1), each R ¹ independently represents an alkyl group having 20 or less carbon atoms, the alkyl group may have a methoxy group, m represents 1 or 2, and X represents oxygen. , A cyanoimino group, a dicyanomethylene group or an organic group represented by the following chemical formula (2), (3) or (4), Z is sulfur, selenium or tellurium, and R ² is an alkyl group having 20 or less carbon atoms. * Represents a double bond portion of X in the general formula (1).)

  According to the said structure, the specific area | region or the whole characteristic can be changed by at least any one process of a heat processing, a light irradiation process, and a solvent process. Therefore, regions having different characteristics can be formed in a single compound, and semiconductor elements having different specifications can be manufactured using a single compound.

  In the method for producing a semiconductor device according to the present invention, the compound represented by the general formula (1) is preferably a compound represented by the following general formula (5).

(In Formula (5), R ³ is H or nC ₆ H ₁₃ , R ⁴ is H or nC ₆ H ₁₂ OCH ₃ , and X is the same as X in Formula (1)) .)
In the method for manufacturing a semiconductor element according to the present invention, the heat treatment is preferably performed at 100 ° C. or higher and 240 ° C. or lower.

In the method for manufacturing a semiconductor device according to the present invention, in the light irradiation treatment, light having a wavelength of 550 nm to 1750 nm and an energy of 1 J / cm ^{2 to} 500 KJ / cm ² may be irradiated. preferable.

  In the method for manufacturing a semiconductor device according to the present invention, the solvent treatment is preferably a treatment in which the organic compound layer is exposed to a vapor of chloroform, dichloromethane, tetrachloroethane, or tetrachloromethane.

  According to each configuration described above, the characteristics of the semiconductor in the processed region can be changed more reliably.

  Further, in the method of manufacturing a semiconductor device according to the present invention, the semiconductor device is an organic transistor having a gate electrode, a gate insulating film, a source electrode, a drain electrode, and the organic compound layer on a substrate, Is preferably applied to a region of the organic compound layer between the source electrode and the drain electrode.

  In the method for manufacturing a semiconductor device according to the present invention, each of the treatments is a region of the organic compound layer where the source electrode and the drain electrode are formed, and is between the source electrode and the drain electrode. It is preferable that it is also applied to a region that is continuous with a certain region.

  In the method for manufacturing a semiconductor element according to the present invention, the organic compound layer is preferably formed by a solution process.

  In order to solve the above problems, a method of manufacturing a semiconductor device according to the present invention includes a plurality of semiconductor elements in which a semiconductor layer is an organic compound layer formed of a compound represented by the general formula (1). The plurality of semiconductor elements include at least two of a semiconductor element having an n-type characteristic, a semiconductor element having a p-type characteristic, and a semiconductor element having an ambipolar characteristic. A method for manufacturing a semiconductor device, wherein a specific region of the organic compound layer is subjected to at least one of a heat treatment, a light irradiation treatment, and a solvent treatment, thereby forming the specific region in the specific region. A configuration including a step of changing the n-type characteristic, the p-type characteristic, or the bipolar characteristic of the organic compound layer to another characteristic among the n-type characteristic, the p-type characteristic, and the bipolar characteristic. Is

  In the method for manufacturing a semiconductor device according to the present invention, the compound represented by the general formula (1) is preferably a compound represented by the general formula (5).

  In order to solve the above problems, a semiconductor element according to the present invention is a semiconductor element in which a semiconductor layer is an organic compound layer formed of a compound represented by the general formula (1), and the organic compound layer Has a single composition, and in the organic compound layer, at least two regions of an n-type property region, a p-type property region, and an ambipolar property region are formed. It is the composition which is.

  In the semiconductor element according to the present invention, the compound represented by the general formula (1) is preferably a compound represented by the general formula (5).

  Moreover, in the semiconductor element according to the present invention, any one of the at least two regions is obtained by performing any one of heat treatment, light irradiation treatment, and solvent treatment on the organic compound layer. The formed region is preferable.

  In the semiconductor device according to the present invention, it is preferable that the at least two regions are formed of the same compound.

  An organic diode according to the present invention includes an organic compound layer formed of a compound represented by the general formula (1) sandwiched between a cathode and an anode facing each other and the cathode and the anode. The organic compound layer has a single composition, and each region where the cathode and the anode of the organic compound layer are disposed has an n-type characteristic, a p-type characteristic, and an ambipolarity. The structure may have any of the characteristics of the mold and may have different characteristics.

  In the organic diode according to the present invention, the compound represented by the general formula (1) is preferably a compound represented by the general formula (5).

  The organic transistor according to the present invention is an organic transistor including a gate electrode, a gate insulating film, a semiconductor layer, a source electrode, and a drain electrode on a substrate, and the semiconductor layer is represented by the general formula (1). An organic compound layer formed of the compound, the organic compound layer has a single composition, and each region where the source electrode and the drain electrode of the organic compound layer are formed has n-type characteristics. The structure may have any one of p-type characteristics and bipolar characteristics, and may have different characteristics.

  In the organic transistor according to the present invention, the compound represented by the general formula (1) is preferably a compound represented by the general formula (5).

  In the organic transistor according to the present invention, a pn junction is preferably formed in the organic compound layer.

  The semiconductor element according to the present invention is an organic diode having a semiconductor layer, an anode and a cathode on a substrate, wherein the anode and the cathode do not overlap each other, and the semiconductor layer has the general formula ( 1) An organic compound layer formed of the compound represented by the general formula (5), wherein the organic compound layer has a single composition, and a cathode and an anode of the organic compound layer are formed. Each region may have any one of n-type characteristics, p-type characteristics, and bipolar characteristics, and may have different characteristics.

  In the organic diode according to the present invention, a pn junction is preferably formed in the organic compound layer.

  In order to solve the above problems, a semiconductor device according to the present invention includes a plurality of semiconductor elements in which a semiconductor layer is an organic compound layer formed of a compound represented by the general formula (1). The plurality of semiconductor elements include at least two of a semiconductor element in which the organic compound layer has n-type characteristics, a semiconductor element having p-type characteristics, and a semiconductor element having bipolar characteristics. The organic compound layers of the at least two types of semiconductor elements have the same composition.

  In the semiconductor device according to the present invention, the compound represented by the general formula (1) is preferably a compound represented by the general formula (5).

  The semiconductor device according to the present invention preferably forms a logic circuit by combining the at least two types of semiconductor elements.

  In the semiconductor device according to the present invention, it is preferable that the organic compound layers of the plurality of semiconductor elements are formed of the same compound.

  A semiconductor element according to the present invention is a semiconductor element having a gate electrode, a gate insulating film, a semiconductor layer, a source electrode, and a drain electrode on a substrate, wherein the semiconductor layer has the following general formula (1): The structure formed with the compound represented by these may be sufficient.

  In the semiconductor element according to the present invention, the compound represented by the general formula (1) is preferably a compound represented by the general formula (5).

  In the case where the semiconductor element is a transistor, the work functions of the source electrode and the gate electrode are preferably 4.2 to 5.1 eV.

  When the semiconductor element is a transistor, the source electrode and the gate electrode are preferably the same conductive material, and are preferably gold, chrome, or silver.

  In the semiconductor device according to the present invention, the semiconductor element is an organic transistor having a gate electrode, a gate insulating film, a source electrode, a drain electrode, and the organic compound layer on a substrate, wherein the gate insulating film is 2 It is preferable that there are more than one type.

  The organic transistor substrate is preferably a plastic substrate.

  The gate insulating film of the organic transistor is preferably an organic insulating film.

  In the organic transistor, the compound is a band in which at least one of a HOMO level and a LUMO level of the compound is a difference between the HOMO level and the LUMO level due to at least one of heat treatment, light irradiation treatment, and solvent treatment. It is preferable to change more than half of the gap.

  In the organic transistor, it is preferable that the HOMO level before processing and the LUMO level after processing are substantially equal.

In the organic transistor, it is preferable that the LUMO level before processing and the HOMO level after processing are substantially equal.
In the semiconductor element, it is preferable that the molecular packing of the compound is changed by at least one of heat treatment, light irradiation treatment, and solvent treatment.

  The semiconductor element according to the present invention is an organic diode in which an anode, the organic compound layer, and a cathode are sequentially stacked on a substrate, and is superimposed on the anode and the cathode of the organic compound layer. It may be an organic diode that has been subjected to light irradiation treatment in at least a part of the region.

  The organic diode preferably has a pn junction formed in a single organic compound layer.

  In addition, the organic diode has different HOMO level on the anode side and HOMO level on the cathode side, and LUMO level on the anode side and HOMO level on the cathode side, depending on the light irradiation treatment. Preferably it is.

  Further, in the organic diode, it is preferable that the charge type of the semiconductor characteristic on the anode side and the charge type of the semiconductor characteristic on the cathode side of the organic compound layer differ depending on the light irradiation treatment.

  In the organic diode, the anode and the cathode are preferably made of the same conductive material.

  As described above, in the method for producing an organic semiconductor element according to the present invention, at least a heat treatment, a light irradiation treatment, and a solvent treatment are performed on an organic compound layer in which a semiconductor layer is formed of an oligothiophene compound having a quinoid structure. By performing any of the processes, the n-type characteristic, the p-type characteristic, or the bipolar characteristic is changed to another characteristic among the n-type characteristic, the p-type characteristic, and the bipolar characteristic. Process. Therefore, regions having different characteristics can coexist in the same compound.

It is the schematic which shows the structure of the organic transistor which concerns on one Embodiment. It is the schematic explaining the hole and electron injection | pouring barrier. (A) is a figure showing the absorption spectrum change by heat processing and light irradiation processing, (b) is a figure showing the measurement result which shows the energy level change by heat processing and light irradiation processing. It is a figure which shows the measurement result which shows the surface potential change by a light irradiation process. It is a figure showing the measurement result which shows the change of the X-ray diffraction pattern by heat processing and light irradiation processing. It is the schematic which shows the measuring method of the organic transistor which concerns on one Embodiment. It is a figure showing the transfer characteristic of the organic transistor of Example 1 and Example 6. FIG. It is a figure showing the measurement result of the transfer characteristic of the organic transistor of Example 2. It is a figure showing the measurement result of the mobility of the organic transistor of Example 6. It is a figure showing the measurement result of the mobility of the organic transistor of Example 6. It is a figure showing the measurement result of the transfer characteristic and mobility of the organic transistor of Example 7, (a) is a measurement result of a transfer characteristic, (b) is a measurement result of a mobility. It is a figure showing the measurement result of the transfer characteristic and mobility of the organic transistor of Example 8, (a) is a measurement result of a transfer characteristic, (b) is a measurement result of a mobility. It is a figure showing the measurement result which shows the change of the transmission characteristic by the solvent process of the organic transistor of Example 9, an absorption spectrum, and an X-ray-diffraction pattern, (a) is a change of a transfer characteristic, (b) is a change of an absorption spectrum, (C) represents a change in the X-ray diffraction pattern. It is a figure showing the measurement result which shows the change of the transfer characteristic by the solvent process of the organic transistor of Example 10, and a change of an absorption spectrum, (a) shows the change of the transfer characteristic, (b) shows the change of the absorption spectrum. It is a figure showing the measurement result which shows the change of the transfer characteristic by the difference in the organic solvent used for formation of the organic compound layer of Example 3, an absorption spectrum, and an X-ray-diffraction pattern, (a) is a change of a transfer characteristic, (b ) Represents a change in absorption spectrum, and (c) represents a change in X-ray diffraction pattern. It is a figure showing the measurement result of the transfer characteristic of the organic transistor of Example 4, and a mobility, (a) is a transfer characteristic, (b) is a mobility, (c) represents the ratio of mobility. It is a figure showing the measurement result which shows the change of the absorption spectrum and X-ray diffraction pattern by the difference in the film thickness of Example 4, (a) shows the change of an absorption spectrum, (b) shows the change of an X-ray diffraction pattern. Yes. It is a figure showing the measurement result of the transfer characteristic of the organic transistor of Example 5, and a mobility, (a) is a transfer characteristic, (b) is a mobility, (c) represents the ratio of mobility. It is a figure showing the measurement result of the transfer characteristic of the organic transistor of Example 11. It is the schematic explaining the structure and measuring method of the logic gate NOT which concern on one Embodiment, (a) is the schematic explaining a structure, (b) is the schematic explaining the measuring method. It is a figure showing the transfer characteristic of the logic gate NOT of Example 12, and the measurement result of a gain, (a) and (b) shows a transfer characteristic, (c) represents the gain. It is a figure showing the transfer characteristic of the logic gate NOT of Example 13, and the measurement result of a gain, (a) represents a transfer characteristic, (b) represents the gain. It is the schematic explaining the structure of the logic gate NOT which concerns on one Embodiment. It is a figure showing the measurement result of the transfer characteristic and gain of logic gate NOT of Example 14, and the transfer characteristic of the organic transistor which comprises logic gate NOT, (a) is the transfer characteristic of an organic transistor, (b) is a logic gate. (C) represents the gain. It is a figure showing the measurement result of the transfer characteristic and gain of logic gate NOT of Example 15, and the transfer characteristic of the organic transistor which comprises logic gate NOT, (a) is the transfer characteristic of an organic transistor, (b) is a logic gate. (C) represents the gain. It is the schematic explaining the structure of the logic gate NOT which concerns on one Embodiment. It is a figure showing the transmission characteristic and gain of the logic gate NOT of Example 16, and the measurement result of the transfer characteristic of the organic transistor which comprises the logic gate NOT of Example 16 and Example 17, (a) is a transmission of an organic transistor (B) represents the transfer characteristic of the logic gate, and (c) represents the gain. It is a figure showing the transfer characteristic and gain measurement result of logic gate NOT of Example 17, (a) represents a transfer characteristic, (b) represents the gain. It is a figure showing the transfer characteristic and gain measurement result of logic gate NOT of Example 18, (a) represents a transfer characteristic, (b) represents the gain. It is a figure showing the transfer characteristic of the logic gate NOT of Example 19, and the measurement result of a gain, (a) represents a transfer characteristic, (b) represents the gain. It is a figure showing the measurement result of the transfer characteristic of the logic gate NOT of Example 20, and the transfer characteristic of the organic transistor which comprises the logic gate NOT of Example 20 and Example 21, (a) is the transfer characteristic of an organic transistor, (B) shows the transfer characteristic of the logic gate. It is a figure showing the measurement result of the transfer characteristic of logic gate NOT of Example 21. It is a figure showing the measurement result which shows the change of an operation characteristic when the logic gate NOT of Example 21 is bent, (a) is a change of the transfer characteristic of an organic transistor, (b) is a change of the transfer characteristic of a logic gate. , (C) represents the bending radius dependency. (A) And (b) is the schematic explaining the structure of logic gate NAND and NOR concerning one Embodiment of this invention. FIG. 35 is a schematic diagram illustrating a method for measuring the logic gate NAND illustrated in FIG. 34. It is a measurement result of the transfer characteristic of the logic gate NAND of Example 22, (a) is a figure showing the measurement result of a transfer characteristic, (b) summarizes the result of (a) in the table | surface. FIG. 35 is a schematic diagram illustrating a method for measuring the logic gate NOR shown in FIG. 34. It is a measurement result of the transfer characteristic of logic gate NOR of Example 23, (a) is a figure showing the measurement result of a transfer characteristic, (b) summarizes the result of (a) in the table | surface. It is the schematic explaining the structure and measuring method of the organic-semiconductor element of Example 24, (a) shows a structure, (b) is the schematic explaining a measuring method. It is a figure showing the measurement result of the current-voltage characteristic of Example 24. It is the schematic which shows the structure of the organic transistor of Example 25, (a) is sectional drawing, (b) is a top view. It is a measurement result of the transfer characteristic and output characteristic of the organic transistor of Example 25, (a) and (b) express a transfer characteristic, (c) expresses an output characteristic. It is a schematic sectional drawing which shows the organic transistor by which the charge type was converted in the organic compound layer between a gate electrode and a drain electrode. It is a schematic sectional drawing which shows the organic transistor from which the charge type was converted in the organic compound layer between a gate electrode and a drain electrode, and its vicinity. It is a schematic sectional drawing which shows the organic transistor by which the whole organic compound layer is processed. It is a figure showing the difference in the absorption spectrum by the difference in the temperature of heat processing.

  The embodiment of the present invention will be described below with reference to FIGS.

  As described above, in order to fabricate a logic gate, it is necessary to incorporate organic transistors having different charge types, and two or more kinds of organic compound layers or two or more kinds of different electrode materials are necessary. Thus, if the charge type can be converted with a single compound, groundbreaking innovations such as simplification of processes and reduction of resource consumption can be brought about. The present inventors have found a compound capable of changing the charge type by heat treatment, light irradiation treatment and solvent treatment, and have completed the present invention. As a result, organic transistors with different charge types were realized with a single compound and a single source / drain electrode, and a logic gate was also realized by combining them. The logic gate was also fabricated on a plastic substrate, and it was confirmed that it would work even if the substrate was bent.

  In this specification, the charge type is a term used to distinguish whether a semiconductor layer or a semiconductor element has n-type characteristics, p-type characteristics, or bipolar characteristics.

In the present specification, “p-type”, “p-type near-polarity”, “bipolar-type”, “n-type near-bipolar” and “n-type” are distinguished as follows. Is done.
The ratio of the hole mobility μ _h to the electron mobility μ _e (μ _h / μ _e ) is
50 or more: p-type 10 or more and less than 50: bipolar type near p-type 0.1 or more and less than 10: bipolar type 0.02 or more and less than 0.1: bipolar type near n-type less than 0.02: n-type .

However, even when the ratio (μ _h / μ _e ) is determined to be an n-type bipolar type, those having a hole mobility of less than 0.001 cm ² / Vs have a small and insufficient mobility. Therefore, the n-type is used.

  First, the operation of a normal organic transistor will be described.

  In a conventional organic transistor, when a voltage is applied to the gate electrode, a channel is formed in a region between the source electrode and the drain electrode of the organic compound layer (hereinafter also referred to as an active region), and the source / The drain current between the drain electrodes is easy to flow, and the on state is established. In the case of the p-type, holes flow when the gate voltage is negative. In the case of the n-type, electrons flow when the gate voltage is positive. In the case of the bipolar type, holes or electrons flow regardless of the polarity of the gate voltage.

  In the case of an organic transistor, injection of charges from the source electrode and the drain electrode is also important. In an organic transistor, application of a gate voltage reduces a charge injection barrier from the electrode to the organic compound layer, thereby promoting charge injection and allowing a drain current to flow. Here, as shown in FIG. 2, for holes, the difference between the work function of the electrode and the HOMO (Highest Occupied Molecular Orbital) level of the organic compound layer becomes an injection barrier, and for electrons, the work function of the electrode and the organic compound layer The difference from the LUMO (Lowest Unoccupied Molecular Orbital) level becomes an injection barrier. Therefore, this charge barrier needs to be changed for charge type conversion.

  The present inventors use a compound represented by the following chemical formula (1) (hereinafter referred to as an oligothiophene compound used in the present invention) for the organic compound layer and perform a specific treatment to thereby obtain a HOMO level of the organic compound layer. The present inventors have found that the LUMO level can be easily changed and have completed the present invention.

(In Formula (1), each R ¹ independently represents an alkyl group having 20 or less carbon atoms, the alkyl group may have a methoxy group, m represents 1 or 2, and X represents oxygen. , A cyanoimino group, a dicyanomethylene group or an organic group represented by the following chemical formula (2), (3) or (4), Z is sulfur, selenium or tellurium, and R ² is an alkyl group having 20 or less carbon atoms. * Represents a double bond portion of X in the general formula (1).)

  FIG. 1 is a schematic view showing a configuration of an organic transistor according to the present invention. As shown in FIG. 1, the organic transistor 1 includes a gate electrode 11, a gate insulating film 12, a source electrode 14, a drain electrode 15, and an organic compound layer 13 on the substrate. The organic transistor 1 has a bottom gate / top contact type structure, but is not particularly limited to this structure, and a normal organic transistor structure such as a bottom gate / bottom contact type can be used. .

  Although the compound which forms the organic compound layer 13 will not be specifically limited if it is the oligothiophene compound used for this invention, It is preferable that it is a compound represented by following General formula (5), and following Chemical formula (6) and ( The compound represented by 7) is more preferable, and the compound represented by the following general formula (6) is more preferable. Hereinafter, the compound represented by the following chemical formula (6) is referred to as 4ThQ, and the compound represented by the following chemical formula (7) is referred to as 4ThQ (OMe).

(In the formula (5), R ³ is H or nC ₆ H ₁₃ , R ⁴ is H or nC ₆ H ₁₂ OCH ₃ , and X is the same as X in the above formula (1). The same.)

  The formation of the organic compound layer can be carried out more easily with a lower energy in a solution process (also referred to as a wet process or a wet process) such as spin coating and printing than in a vacuum deposition method. However, many of the compounds that can be used in the solution process are polymers, and due to the dispersibility of the degree of polymerization, etc., there is a need for repeatability and reliability. On the other hand, the oligothiophene compound used in the present invention can be formed into a thin film by a solution process and has excellent dispersibility. Up to now, there has been no example showing that a high-quality thin film that can be used as a semiconductor element can be formed using 4ThQ by a solution process.

  The 4ThQ thin film can be formed by spin coating by dissolving in a solvent such as chloroform and tetrahydrofuran (THF).

  Next, changes in the UPS spectrum and absorption spectrum obtained by ultraviolet photoelectron spectroscopy (UPS) due to light irradiation treatment or heat treatment on the 4ThQ thin film will be described.

  A thin film for UPS measurement was formed by spin-coating a chloroform solution having a 4ThQ concentration of 2 mg / ml on an ITO substrate at a rotational speed of 3000 rpm for 10 seconds. The thin film for measuring the absorption spectrum was formed by spin-coating a chloroform solution having a 4ThQ concentration of 10 mg / ml on a synthetic quartz substrate at a rotation speed of 3000 rpm for 10 seconds.

  The heat treatment was performed at 180 ° C. for 10 seconds. There was no change in the results until 40 seconds. In the light irradiation treatment, a laser scanner having a wavelength of 808 nm was used as a light source, and the entire film was processed by sequentially scanning line by line. The irradiation conditions are an optical power of 0.1 W, a spot size of 300 μm, a scanning speed of 10 mm / second, and a scanning interval of 150 μm. Similar results can be obtained with light having a wavelength of 1060 nm.

  FIG. 3 is a diagram showing measurement results of changes in absorption spectrum and energy level due to light irradiation treatment or heat treatment for 4ThQ. The absorption spectrum is shown in FIG. 3 (a), and the calculated HOMO / LUMO level is shown in FIG. 3 (b). As shown in FIG. 3A, the absorption spectrum of 4ThQ is changed by the light irradiation treatment and the heat treatment. The heat treatment was performed under the conditions of 180 ° C. and 10 seconds, but the results did not change until 40 seconds. The HOMO level and LUMO level before each treatment were 4.5 eV and 3.6 eV, respectively, but the HOMO level and LUMO level after treatment were 5.6 eV and 4. 5 e. It changed to 5 eV. That is, the HOMO level before processing and the LUMO level after processing are the same level. Therefore, the injection barrier for holes to 4ThQ and the injection barrier for electrons are interchanged, and the charge types are changed. The heat treatment was performed under the conditions of 180 ° C. and 10 seconds, but the results did not change until 40 seconds.

  FIG. 46 is a diagram illustrating a difference in absorption spectrum change due to a difference in temperature of the heat treatment. A chloroform solution having a 4ThQ concentration of 10 mg / ml was prepared, and spin coating was performed at a rotational speed of 3000 rpm for 10 seconds to produce a 4ThQ thin film on a glass substrate. The absorption spectrum of the prepared sample is measured every time the heat treatment is repeated. The heat treatment time was constant for 3 seconds, and the heating temperature was increased from 180 degrees by 10 degrees. As shown in FIG. 46, after the absorption spectrum was changed by the heat treatment at 180 degrees, the absorption spectrum was hardly changed until the heating at 230 degrees and was stable. The absorption spectrum decreased greatly by heating at 240 degrees, suggesting that the decomposition of 4ThQ began. However, if the heat treatment time is shortened, 4ThQ is not decomposed to a higher temperature, so that a heat treatment at a higher temperature is possible.

  As described above, it was experimentally confirmed that the UPS spectrum and the absorption spectrum were changed by the light irradiation treatment or the heat treatment. That is, it was experimentally confirmed that the HOMO level and the LUMO level change.

  What is important for the charge type conversion is to change the size of the hole injection barrier and the electron injection barrier, which is precisely determined by the work function of the electrode. Therefore, as an organic compound layer alone, it is preferable that at least one of the HOMO level and the LUMO level change more than half of the band gap that is the difference between the HOMO level and the LUMO level. This facilitates charge type conversion. It is more preferable that the HOMO level before processing and the LUMO level after processing are the same level, or that the LUMO level before processing and the HOMO level after processing are the same level.

  Such a change in the energy band structure is experimentally captured as a change in work function. First, a 4ThQ thin film was formed by spin-coating a chloroform solution having a 4ThQ concentration of 10 mg / ml on an ITO substrate at a rotational speed of 3000 rpm for 10 seconds. Next, using a laser scanner with a wavelength of 1060 nm, the letter “N” is drawn under the conditions of optical power 0.1 W, spot size 45 μm, scanning speed 200 mm / sec, and the letter “P” floats white. Scanned. After scanning, the surface potential was observed with a scanning Kelvin probe force microscope. The observation results showing the surface potential change are shown in FIG. As shown in FIG. 4, a pattern of surface potential was observed. Since the surface potential corresponds to the work function, the result shown in FIG. 4 can be regarded as successful in patterning the work function. In other words, the letter “N” of the n-type semiconductor region having a small absolute value of the work function is placed on the background of the p-type semiconductor region having a large absolute value of the work function, and the character of the p-type semiconductor region is placed on the background of the n-type semiconductor region. “P” can be patterned. That is, it is possible to form a pn junction and to make a p-type semiconductor region and an n-type semiconductor region separately with light.

  By the way, molecular packing is also considered important for charge type conversion. In the said nonpatent literature 1, theoretical consideration is performed about the relationship between a molecular packing and a charge transport characteristic about the oligothiophene which has a quinoid structure containing 4ThQ. Non-Patent Document 1 suggests that the molecular packing changes by slightly changing the structure of the compound, which affects the charge transport properties. In the present invention, the change in molecular packing can be realized in a single compound. Non-Patent Document 1 does not describe any possibility of realization by a single compound.

  FIG. 5 is a diagram showing an X-ray diffraction pattern of 4ThQ. As shown in FIG. 5, the peak position is changed by the light irradiation treatment and the heat treatment. This shows that the molecular packing of 4ThQ is changed by the light irradiation treatment and the heat treatment. Here, the production of the measurement sample is the same as the above-described absorption spectrum measurement sample except for the wavelength of the light irradiation treatment. A laser scanner with a wavelength of 1060 nm was used as a light source for the light irradiation treatment.

Note that the conditions of the light irradiation treatment and the heat treatment are not limited to the above-described conditions. For example, the charge type conversion is confirmed by heat treatment at 100 ° C. for 30 minutes. Even in the light irradiation process, the light power, the scanning speed, the spot size, and the like can be appropriately changed. When applied to an organic transistor, the balance with the source / drain electrodes is important as described above, and may be adjusted according to the purpose. However, in the case of light irradiation, it is necessary to carry out at least the wavelength of light absorbed by the organic compound layer. From this viewpoint, the wavelength of light in the light irradiation is preferably 550 nm to 1750 nm. Moreover, when energy is converted from the irradiation conditions of the absorption spectrum described above, energy of about 1.7 J / cm ² is absorbed, and the light energy in the light irradiation is preferably at least about 1 J / cm ^2. .

  When manufacturing an organic transistor, it is preferable that the region to be irradiated with light is a region between the source electrode and the drain electrode of the organic compound layer. As a result, as shown in FIG. 43, an organic transistor whose charge type is converted in the active region (13 'in FIG. 43) can be manufactured. In addition, as shown in the Example mentioned later, it is more preferable that the light irradiation process is performed also to the area | region which overlaps with the source electrode or the drain electrode, and is adjacent to an active region.

  In the charge type conversion by solvent treatment in Examples described later, chloroform is used as the solvent, but the solvent treatment may be performed using dichloromethane, tetrachloroethane, and tetrachloromethane.

  Further, a water-soluble film such as polyvinyl alcohol (PVA) is formed on the 4ThQ thin film by patterning, thereby partially protecting the 4ThQ, performing a solvent treatment thereon, and removing the PVA after the treatment. Thus, charge type conversion can be performed. It may be partially protected with an O-ring or a glass plate.

  Examples will be shown below, and the embodiments of the present invention will be described in more detail. Of course, the present invention is not limited to the following examples, and it goes without saying that various aspects are possible in detail. Further, the present invention is not limited to the above-described embodiments, and various modifications can be made within the scope shown in the claims, and the present invention is also applied to the embodiments obtained by appropriately combining the disclosed technical means. It is included in the technical scope of the invention. Moreover, all the literatures described in this specification are used as reference.

[Organic transistor]
Example 1
An embodiment of the organic transistor of the present invention will be described with reference to FIG. As shown in FIG. 1, the organic transistor of this example includes a gate electrode 11, a gate insulating film 12 formed on the gate electrode 11, a 4ThQ organic compound layer 13 formed on the gate insulating film 12, and an organic A source electrode 14 and a drain electrode 15 formed on the compound layer 13 are provided.

The manufacturing method of the organic transistor 1 is as follows. First, an n-doped Si wafer (thickness: 525 μm) on which a 300 nm thick thermal oxide film (SiO ₂ ) was formed was prepared. A Si wafer was used as a gate electrode that also functions as a substrate, and a thermal oxide film was used as a gate insulating film. A so-called OTS treatment was performed by immersing the Si wafer with a thermal oxide film in a hexane solution in which octadecyltrimethoxysilane (OTS) was dissolved at a concentration of 5 mM for 20 hours. Next, a 4ThQ thin film having a thickness of about 90 nm was formed as an organic compound layer on the thermal oxide film by spin coating. At this time, a chloroform solution having a 4ThQ concentration of 10 mg / ml was prepared, and spin coating was performed at a rotational speed of 3000 rpm for 10 seconds. Thereafter, vacuum drying was performed at 50 ° C. overnight. Subsequently, a gold electrode having a thickness of 20 nm to 80 nm was formed on the 4ThQ thin film by a vacuum deposition method as a source electrode and a drain electrode. The channel width was designed to be 4 mm and the channel length was 45 μm.

  Next, transfer characteristics of the organic transistor 1 will be described with reference to FIGS. 6 and 7.

FIG. 6 is a schematic diagram illustrating a method for measuring the drain current in the organic transistor 1. A lead wire is connected to the produced organic transistor 1, and as shown in FIG. 6, a voltage source for applying a gate voltage (V _g ), a voltage source for applying a drain voltage (V _d ), and a drain current An ammeter for measuring (I _d ) was further connected.

FIG. 7 is a diagram showing the measurement result of the drain current in the organic transistor 1. A drain voltage (V _d ) of 100 V was applied, and the relationship between the drain current and the gate voltage in the saturation region was examined. The result is shown by a solid line in FIG. As shown in FIG. 7, the organic transistor 1 has a p-type ambipolar characteristic. Mobility, the hole mobility 0.05~0.1cm ² / Vs, the electron mobility was reached 0.002~0.006cm ² / Vs. As an oligomer of a solution process, it was an organic transistor having top-level mobility. The results shown in FIG. 7 are the results of measurement while placing the sample in the chamber and roughing with a rotary pump, but no significant change was observed in the atmosphere, and stable operation was obtained in the atmosphere. It was.

(Example 2)
The transfer characteristics of an organic transistor having an organic compound layer of 4ThQ (OMe) will be described below with reference to FIG.

  The organic transistor of this example is the same as that of Example 1 except that the organic compound layer is 4ThQ (OMe). That is, the only difference is that a chloroform solution in which 4ThQ (OMe) is dissolved is used when forming a thin film by spin coating. At this time, the solution was heated to 50 ° C. so that 4ThQ (OMe) was sufficiently dissolved.

A voltage source and an ammeter were connected to the produced organic transistor 1 in the same manner as in Example 1. A drain voltage (V _d ) of 100 V was applied, and the transfer characteristics in the saturation region were examined. The results are shown in FIG. As shown in FIG. 8, in the organic transistor, n-type characteristics were obtained. The electron mobility was 0.0005 cm ² / Vs.

  The organic transistor has a smaller hysteresis than the organic transistor 1 of Example 1, and is less likely to cause a malfunction as the organic transistor.

Example 3
Another example of an organic transistor having an organic compound layer of 4ThQ will be described below with reference to FIG.

  The organic transistor of this example is the same as that of Example 1 except that the solvent at the time of forming the 4ThQ thin film is changed. In this example, when a 4ThQ thin film was formed, a tetrahydrofuran (THF) solution having a 4ThQ concentration of 10 mg / ml was prepared and spin-coated at a rotation speed of 1500 rpm for 10 seconds.

A lead wire was connected to the manufactured organic transistor, a voltage source and an ammeter were connected in the same manner as in Example 1, a 50 V drain voltage (V _d ) was applied, and the transfer characteristics in the saturation region were examined. The results are shown in FIG. Note that the transfer characteristics of the organic transistor in which the 4ThQ thin film was formed using the chloroform solution were examined under the same measurement conditions, and the results are also shown in FIG.

  As shown in FIG. 15 (a), in the case of an organic transistor manufactured using a chloroform solution, the characteristics of the bipolar transistor rather than the p-type in the case of an organic transistor manufactured using a chloroform solution n-type characteristics were obtained. From the above, it was found that the charge type and mobility can be adjusted by selecting a solvent for forming the 4ThQ thin film.

  Next, a 4ThQ thin film was formed on a synthetic quartz substrate, and an absorption spectrum and an X-ray diffraction pattern were measured. The respective results are shown in FIGS. 15 (b) and (c). 15B and 15C also show the results of an organic transistor manufactured using a chloroform solution. Further, the absorption spectrum of FIG. 15B is normalized and displayed with the maximum absorption value. As shown in FIGS. 15B and 15C, the absorption spectrum and the X-ray diffraction pattern differed depending on the solvent used. From this, it was confirmed that the molecular packing of 4ThQ differs depending on the solvent used.

  Further, a 4ThQ thin film was formed on the ITO substrate, the UPS spectrum was measured, and the HOMO level and the LUMO level were calculated to be 5.5 eV and 4.5 eV, respectively. This is different from the above-described HOMO / LUMO level when a 4ThQ thin film is formed using a chloroform solution. That is, it is considered that different HOMO / LUMO levels and molecular packing were obtained by changing the solvent, and as a result, different charge types were obtained.

Example 4
An organic transistor in which the film thickness is changed by changing the conditions of the 4ThQ concentration and the spin coat rotation speed when forming the 4ThQ thin film will be described below with reference to FIGS.

  The organic transistor in this example differs only in the concentration and the number of rotations among the formation conditions of the 4ThQ thin film in Example 1, and thus the film thickness of the 4ThQ thin film is different from that in Example 1.

A lead wire was connected to the produced organic transistor, a voltage source and an ammeter were connected in the same manner as in Example 1, a drain voltage (V _d ) of −50 V was applied, and the transfer characteristics in the saturation region were measured. The transfer characteristics are shown in FIG. 16A, the calculated mobility is shown in FIG. 16B, and the ratio of the hole mobility μ _h and the electron mobility μ _e calculated based on the result is shown in FIG. ). As shown in FIGS. 16A and 16B, the hole mobility is almost constant without strongly depending on the film thickness, but the electron mobility is improved as the film thickness is reduced, and is a symmetric bipolar type. It has come to show the characteristics of. Further, as shown in FIG. 16C, the ratio between the hole mobility μ _h and the electron mobility μ _e has a correlation with the film thickness. A transistor could be implemented. In the case of a film thickness of 29 nm, the ratio was 1.7 at most.

  Next, 4ThQ thin films with different film thicknesses were formed on a synthetic quartz substrate, and the absorption spectrum and X-ray diffraction pattern were measured. The respective results are shown in FIGS. 17 (a) and 17 (b). The absorption spectrum of FIG. 17A is normalized and displayed with the maximum value of absorption. As shown in FIGS. 17A and 17B, the peak positions of the absorption spectrum and the X-ray diffraction pattern changed according to the film thickness. From this, it was confirmed that the molecular packing of the 4ThQ thin film changes according to the film thickness. It is considered that the mobility changes as the packing changes.

  As described above, by adjusting the film thickness of the 4ThQ thin film, the ratio between the hole mobility and the electron mobility can be changed, and the hole mobility and the electron mobility can be made substantially equal.

(Example 5)
With reference to FIGS. 18A and 18B, an organic transistor in which the material of the source electrode and the drain electrode and the channel length are different from the organic transistor described above will be described below.

  In the organic transistor in this example, in addition to gold as an electrode material, silver, chromium and aluminum were used, and all of them were formed by a vacuum deposition method.

A lead wire was connected to the produced organic transistor, a voltage source and an ammeter were connected in the same manner as in Example 1, a drain voltage (V _d ) of −50 V was applied, and the transfer characteristics in the saturation region were measured. Part of the results are shown in FIG. FIG. 18B shows the channel length dependence of the mobility calculated from the measurement results, and FIG. 18C shows the channel length dependence of the ratio between the hole mobility μ _h and the electron mobility μ _e . It was confirmed that any metal electrode operates as a transistor. Higher mobility was obtained using silver, chrome or gold than aluminum. This is presumed to be due to the fact that the aluminum electrode is easily oxidized. The work functions of silver, chromium and gold are reported as 4.2 eV, 4.5 eV and 5.1 eV, respectively. Any conductive material having such a work function can inject charges.

As shown in FIG. 18B, in an organic transistor having a channel length of 9 μm and 18 μm using a chromium electrode, the electron mobility is 0.013 cm ² / Vs. This is a very high mobility as a solution process oligomer.

Although the hole mobility did not change greatly with the change in channel length, the electron mobility was relatively strongly affected. As a result, as shown in FIG. 18C, the ratio of the hole mobility μ _h to the electron mobility μ _e depends on the channel length. In other words, it was found that the symmetry of the bipolar characteristics can be controlled by the electrode material and the channel length. In particular, an organic transistor having a channel length of 9 μm using a chromium electrode is a very symmetric bipolar type, and the ratio of the hole mobility μ _h to the electron mobility μ _e is at most 1.5.

(Example 6)
An organic transistor in which heat treatment is performed on the organic compound layer will be described below with reference to FIGS. 7, 9, 10, and 45. The organic transistor in this example is the same as that in Example 1 except that the organic compound layer is heat-treated.

  After a 4ThQ thin film was formed in the same manner as in Example 1, heat treatment was performed on a hot plate at 180 ° C. for 10 seconds. Thereafter, a gold electrode having a thickness of 20 nm to 80 nm was formed on the 4ThQ thin film by a vacuum deposition method as a source electrode and a drain electrode. The channel width was designed to be 4 mm and the channel length was 45 μm. FIG. 45 shows a schematic configuration of the obtained organic transistor. As shown in FIG. 45, in the organic transistor of the present embodiment, the charge type is converted in the whole organic compound layer.

The transfer characteristics of the produced organic transistor will be described with reference to FIG. A voltage source and an ammeter were connected to the produced organic transistor in the same manner as in Example 1, a drain voltage (V _d ) of 100 V was applied, and the transfer characteristics in the saturation region were examined. The results are shown by broken lines in FIG. As shown in FIG. 7, when the heat treatment was performed on the 4ThQ thin film, the organic transistor in this example obtained n-type characteristics. The electron mobility was almost the same as that of the organic transistor 1 of Example 1.

  As can be seen from the comparison with the organic transistor 1 of Example 1, organic transistors having different charge types could be created using the same organic compound and the same source / drain electrode depending on the presence or absence of heat treatment.

  Next, characteristics when the heating time is changed will be described with reference to FIG. FIG. 9 is a diagram showing the measurement results of the hole and electron mobility of the organic transistor. Organic transistors were produced at various heating times at a constant heating temperature of 180 ° C., and the mobility of holes and electrons was measured in the same manner as described above. As a result, as shown in FIG. 9, the mobility of holes and electrons was changed by heating for 3 seconds, and the change in mobility was small until the treatment time of 30 seconds thereafter. The electron mobility was almost constant until 30 seconds. From this, in order to convert the charge type, it was found that a processing time of about 3 to 30 seconds is appropriate for heating at 180 degrees. The treatment time depends on the type of the substrate and the film thickness of the organic compound layer, but at 180 ° C., it is preferable to carry out the treatment time of at least 1 second.

  Next, characteristics when the heating temperature is changed will be described with reference to FIG. FIG. 10 is a diagram illustrating the measurement results of the hole and electron mobility of an organic transistor manufactured by performing the heat treatment at a temperature of 100 ° C. As shown in FIG. 10, in this case, the size of holes and electrons was changed by heating for about 25 minutes, and the charge type was converted. The treatment time is considered to depend on the type of substrate and the film thickness of the organic compound layer, but in the case of 100 ° C., it is preferable to carry out a treatment time of at least 10 minutes.

  As described above, the charge type in the organic transistor can be converted by performing the heat treatment on the 4ThQ thin film and adjusting the heating temperature and the treatment time. According to this embodiment, the bipolar type near the p-type can be converted to the n-type.

(Example 7)
An organic transistor manufactured by performing light irradiation treatment will be described below with reference to FIGS.

  The organic transistor of this example is the same as that of Example 6 except that the heat treatment is changed to the light irradiation treatment. After a 4ThQ thin film was formed in the same manner as in Example 6, light irradiation treatment was performed under the conditions described later using a laser scanner with a wavelength of 1060 nm. Thereafter, a source electrode and a drain electrode were formed. FIG. 44 is a diagram showing the manufactured organic transistor in this example. As shown in FIG. 44, in the organic transistor in this example, the charge type is converted not only in the active region of the organic compound layer but also in the region overlapping with the source electrode 14 or the drain electrode 15 by the light irradiation process ( 13 'in FIG. 44). Note that the charge is also injected from a region where the source electrode 14 or the drain electrode 15 and the organic compound layer overlap with each other. Therefore, it is apparent that the region is preferably subjected to light irradiation treatment.

A lead wire is connected to the manufactured organic transistor, a voltage source and an ammeter are connected in the same manner as in Example 1, a drain voltage (V _d ) of −50 V is applied, and the transfer characteristics in the saturation region are examined. And the electron mobility was calculated. FIG. 11A is a diagram showing the transfer characteristics of an organic transistor manufactured by performing light irradiation processing with a light power of 6.7 W, a spot size of 300 μm, a scan interval of 150 μm constant, and a scan speed changed. FIG. 11B is a diagram showing the dependence of the hole and electron mobility on the scanning speed at various spot sizes for an organic transistor manufactured with a constant optical power of 6.7 W. The scan interval was always half the spot size.

  As shown in FIG. 11A, when the spot size is 300 μm, the characteristics of the bipolar type near the p-type are the same as the hole mobility and the electron mobility at a scanning speed of 0.4 mm / second. Converted to a symmetric bipolar type of degree. Furthermore, it was converted to n-type at a scan speed of 0.04 mm / sec. As described above, by the light irradiation treatment, organic transistors having different charge types can be formed by using the same organic compound and the same source / drain electrode.

  Further, as shown in FIG. 11B, the electron mobility was almost constant regardless of the scanning speed and the spot size. As the spot increases, the light energy absorbed per unit area decreases. Therefore, the scanning speed at which the magnitudes of the mobility of holes and electrons are switched requires a slower speed as the spot becomes larger. In any case, the charge type conversion in the organic transistor can be performed by adjusting the conditions of the light irradiation treatment.

Here, the absorbed light energy is examined. When the spot size is 160 μm, the mobility of electrons and the mobility of holes are approximately the same at a scanning speed of about 0.6 mm / second. In the case of this scanning speed, considering that the absorbance of the organic compound layer is about 0.4, energy of about 11 kJ / cm ² is absorbed. That is, this level of energy is required for charge type conversion. However, strictly speaking, this value depends on the spot size because the laser spot has a distribution. When the spot size is 300 μm, the mobility of electrons and the mobility of holes are approximately the same at a scanning speed of 0.3 mm / second. The absorbed energy at this time is 11 kJ / cm ^2, which is about the same as the spot size of 160 μm. On the other hand, when the spot size is 560 μm, the mobility of electrons and the mobility of holes are approximately the same at a scanning speed of 0.07 mm / second, and the absorbed energy at this time is 26 kJ / cm ² . Further, when the spot size is 1000 μm, the mobility of electrons and the mobility of holes are approximately the same at a scanning speed of 0.01 mm / second, and the absorbed energy at this time is 100 kJ / cm ² . However, in any case, depending on the film thickness of the substrate or the organic compound layer, from the viewpoint of the manufacturing process, the charge type conversion in the organic transistor is absorption of light energy of 100 J / cm ² or more. Is preferred.

(Example 8)
An organic transistor in which the film thickness of the organic compound layer subjected to the light irradiation treatment is changed will be described below with reference to FIG.

  The organic transistor of this example was fabricated in the same manner as the organic transistor in Example 7 except that the film thickness of the organic compound layer was changed. A chloroform solution having a concentration of 5 mg / ml in which 4ThQ was dissolved was prepared, and spin coating was performed at a rotational speed of 5000 rpm for 10 seconds to form a 4ThQ thin film having a thickness of about 50 nm. Subsequently, the light irradiation process was performed on the conditions mentioned later using the laser scanner of wavelength 1060nm. Thereafter, a source electrode and a drain electrode were formed.

A lead wire is connected to the manufactured organic transistor, a voltage source and an ammeter are connected in the same manner as in Example 1, a drain voltage (V _d ) of −50 V is applied, and the transfer characteristics in the saturation region are examined. And the electron mobility was calculated. FIG. 12A is a diagram showing the transfer characteristics of an organic transistor manufactured by irradiating light with a light power of 6.7 W, a spot size of 300 μm, a scan interval of 150 μm, and changing the scan speed. FIG. 12B is a diagram showing the scan speed dependence of the hole mobility under the same conditions. In FIG. 12B, the results for the film thickness of 90 nm shown in FIG. 11B are also shown.

As shown in FIG. 12A, the charge type conversion from the bipolar type to the n-type was possible by the light irradiation treatment even at a film thickness of 50 nm. The electron mobility did not depend on the scanning speed and was almost constant at 0.015 cm ² / Vs. At a scanning speed of 4 mm / sec, the mobility of holes and the mobility of electrons are interchanged, and the absorbed energy at this time is about 560 J / cm ² .

  In addition, as shown in FIG. 12B, the charge type can be converted at a higher scanning speed, that is, with less light energy when the film thickness is 50 nm than when the film thickness is 90 nm. It was.

Example 9
An organic transistor manufactured by solvent treatment will be described below with reference to FIG.

  The organic transistor of this example is the same as that of Example 6 except that the heat treatment is changed to the solvent treatment. Similarly to the organic transistor of Example 6, a 4ThQ thin film was formed on a gate insulating film that was a thermal oxide film, and then a solvent treatment was performed in which the sample was placed in a container filled with chloroform vapor for 1 hour. Next, a source electrode and a drain electrode were formed in the same manner as in Example 6. The schematic structure of the organic transistor obtained is the same as that of the organic transistor shown in FIG.

A lead wire was connected to the manufactured organic transistor, a voltage source and an ammeter were connected in the same manner as in Example 1, a drain voltage (V _d ) of −50 V was applied, and the transfer characteristics in the saturation region were examined. The results are shown in FIG. Here, the organic transistor of Example 1 not subjected to the solvent treatment was also measured under the same conditions, and the results are also shown. As shown in FIG. 13A, the electron mobility was improved by the solvent treatment, and the organic transistor was converted from the bipolar type closer to the p-type to a more symmetric bipolar type.

  Here, a 4ThQ thin film was formed on a synthetic quartz substrate, and an absorption spectrum and an X-ray diffraction pattern of a sample subjected to solvent treatment under the same conditions were measured. The respective results are shown in FIGS. 13 (b) and (c). In FIGS. 13B and 13C, the results of the sample not subjected to the solvent treatment are also shown. As shown in FIGS. 13B and 13C, both the absorption spectrum and the X-ray diffraction pattern were changed by the solvent treatment. This shows that the molecular packing was changed by the solvent treatment. Note that the shift direction of the peak in the X-ray diffraction pattern is opposite to the shift direction by the light irradiation treatment and the heat treatment shown in FIG. Thus, it can be seen that the solvent treatment results in a change in molecular packing that differs from the light irradiation treatment and the heat treatment.

  Furthermore, a 4ThQ thin film was formed on the ITO substrate, and the UPS spectrum of the sample treated with the solvent under the same conditions was measured. The HOMO level and the LUMO level were calculated to be 4.9 eV and 4.1 eV, respectively. This was found to be different from the HOMO / LUMO level of the 4ThQ thin film not subjected to the above-described heat treatment and the 4ThQ thin film subjected to the light irradiation treatment or the heat treatment. From the above, it is considered that the HOMO / LUMO level and molecular packing different from those in the heat treatment and the light irradiation treatment were obtained by the solvent treatment, and as a result, charge type conversion occurred.

(Example 10)
An organic transistor manufactured by performing both heat treatment and solvent treatment will be described below with reference to FIG.

  The organic transistor of this example is the same as Example 9 except that the heat treatment was performed before the solvent treatment. After forming a 4ThQ thin film on the gate insulating film, which is a thermal oxide film, heat treatment was performed at 180 ° C. for 10 seconds on a hot plate. Subsequently, as in Example 9, a solvent treatment was performed in which a sample was placed in a container filled with chloroform vapor for 1 hour, and then a source electrode and a drain electrode were formed.

A lead wire was connected to the manufactured organic transistor, a voltage source and an ammeter were connected in the same manner as in Example 1, a drain voltage (V _d ) of −50 V was applied, and the transfer characteristics in the saturation region were examined. The results are shown in FIG. Here, the transfer characteristics of the organic transistor not subjected to the heat treatment in Example 1 and the organic transistor subjected to only the heat treatment were examined under the same conditions, and the results are also shown. In addition, about the organic transistor which performed only the heat processing, it measured by making drain voltage 50V. Moreover, the vertical axis | shaft of Fig.14 (a) has shown the absolute value of the electric current. As shown in FIG. 14 (a), it was found that the characteristic that was a bipolar type closer to the p-type was converted to an n-type by heat treatment and further converted to a bipolar type by a subsequent solvent treatment. As described above, even after the heat treatment, the mobility of holes and electrons can be adjusted by the solvent treatment. That is, even after the charge type is converted by heat treatment, the charge type can be further converted by the solvent treatment.

  Next, a 4ThQ thin film was formed on a synthetic quartz substrate, and an absorption spectrum of a sample subjected to heat treatment and solvent treatment under the same conditions was measured. The results are shown in FIG. As shown in FIG. 14B, absorption spectra different from those before and after the heat treatment were obtained by the solvent treatment. From this, it can be seen that the 4ThQ thin film was changed to a structure having a molecular packing different from that before and after the heat treatment by the solvent treatment. It can also be seen that the heat treatment does not cause a problem such as decomposition of 4ThQ. Moreover, the absorption spectrum of the present example in which the solvent treatment was performed after the heat treatment was substantially the same as the absorption spectrum in Example 9 in which only the solvent treatment was performed. From the above, it is considered that the HOMO / LUMO level and molecular packing different from those in the heat treatment and the light irradiation treatment are obtained by the solvent treatment, and as a result, the charge type can be converted.

(Example 11)
Another embodiment of an organic transistor in which materials of the source electrode and the drain electrode are different will be described below with reference to FIG.

  The organic transistor in this example is the same as the organic transistor in Example 6 except that silver, chromium, and aluminum are used as the electrode material in addition to gold. In any electrode material, an electrode was formed by a vacuum deposition method. Also, this example differs from the organic transistor in Example 5 in that the 4ThQ thin film was heat-treated at 180 ° C. for 10 seconds.

A lead wire was connected to the produced organic transistor, a voltage source and an ammeter were connected in the same manner as in Example 1, a 50 V drain voltage (V _d ) was applied, and the transfer characteristics in the saturation region were measured. The measurement results are shown in FIG. As can be seen from comparison with FIG. 18A, which is the result of Example 5, the charge type was converted by the heat treatment in any of the electrodes.

[Logic Gate]
Next, a logic gate using a semiconductor device including a plurality of organic transistors will be described.

Example 12
A logic gate NOT formed by using an organic transistor in which an organic compound layer is formed of 4ThQ will be described below with reference to FIGS. The logic gate NOT2 of the present embodiment is an element that combines the organic transistors described in the first embodiment.

  FIG. 20A is a schematic diagram showing the configuration of the logic gate NOT2 of this embodiment. After a 4ThQ thin film was formed in the same manner as in Example 1, gold was vacuum deposited as shown in FIG. 20A to form source / drain electrodes 27A and 27B and wiring. As a result, two organic transistors 1A and 1B were formed on the same substrate. As in Example 1, the channel width of the source electrode and the drain electrode was 4 mm, the channel length was 45 μm, and the thickness was 20 nm to 80 nm.

FIG. 20B is a diagram showing a measurement method in this logic gate NOT2. A lead wire is connected to the produced logic gate, and as shown in FIG. 20B, a voltage source for applying a power supply voltage (V _DD ), a voltage source for applying an input voltage (V _in ), A voltmeter for measuring the output voltage (V _out ) was connected.

FIG. 21A is a diagram illustrating a change in the output voltage (V _out ) when the input voltage (V _in ) is swept when 50 V and −50 V are applied as the power supply voltage (V _DD ). As shown in FIG. 21A, the absolute value of the output voltage (V _out ) decreases when the absolute value of the input voltage (V _in ) is high, regardless of whether the power supply voltage is positive or negative. When the absolute value of the input voltage (V _in ) is low, the absolute value of the output voltage (V _out ) is high. That is, it functioned as a logic gate NOT.

FIG. 21B is a diagram showing characteristics when the power supply voltage (V _DD ) is changed. FIG. 21C is a diagram showing a gain representing switching characteristics calculated by ΔV _out / ΔV _in . As shown in FIGS. 21B and 21C, the operation of this logic gate was confirmed even at 20 V, and the gain was about 5.

(Example 13)
A logic gate in which a region where any organic transistor is formed is subjected to light irradiation processing to convert the charge type in a partial region of the organic compound layer will be described below with reference to FIG. The logic gate NOT2 of this example is the same as that of Example 12 except that the organic transistor 1B is subjected to light irradiation treatment to perform charge type conversion.

  After forming a 4ThQ thin film in the same manner as in Example 12, light irradiation was performed using a laser scanner with a wavelength of 1060 nm under the conditions of optical power 6.7 W, spot size 300 μm, scan interval 150 μm, and scan speed 0.04 mm / second. The treatment was performed on a part of the 4ThQ thin film. Next, gold source and drain electrodes and wirings were formed by vacuum deposition so that the organic transistor 1B was formed in the irradiated region. The organic transistor treated under this light irradiation condition exhibits n-type characteristics as shown in Example 7. Therefore, the logic gate NOT2 of this embodiment is formed by combining the p-type ambipolar organic transistor 1A and the n-type organic transistor 1B.

A lead wire is connected to the manufactured logic gate, a voltage source and a voltmeter are connected in the same manner as in Example 12, and the change in the output voltage (V _out ) when the input voltage (V _in ) is swept can be changed to various power supplies. It was measured by voltage (V _DD ). The measurement results are shown in FIG. The calculated gain is shown in FIG.

As shown in FIG. 22A, compared with Example 12, the output voltage (V _out ) is constant without fluctuation when the input voltage (V _in ) is low, and the HIGH state is improved. A logic circuit NOT can be produced. Moreover, the operation | movement with the power supply voltage 2.5V was also confirmed. Moreover, as shown in FIG.22 (b), the gain also improved to 16.

(Example 14)
An example of a logic gate using an organic transistor manufactured using a gate insulating film different from the organic transistor described above will be described below with reference to FIGS.

FIG. 23 is a schematic diagram showing the configuration of the organic transistor that constitutes the logic gate NOT2 of this embodiment. The logic gate NOT2 of this example is the same as that of Example 13 except that the gate insulating film of the organic transistor 1A is changed. As shown in FIG. 23, a polyimide gate insulating film 16 is formed in a region where an organic transistor 1A is formed on an n-doped Si wafer on which a 300 nm-thick thermal oxide film (SiO ₂ ) is formed. Formed as shown. First, a solution (CT4112, Kyocera Chemical Co., Ltd.) in which a polyimide precursor was dissolved was applied on the thermal oxide film by a spin coating method. The spin coating at this time was performed in two stages of 800 rpm for 8 seconds and then 3000 rpm for 30 seconds. At this time, the organic transistor 1B was masked so that the polyimide insulating film 16 was not formed. Immediately after spin coating, heating was performed at 140 ° C. for 1 minute, followed by imidization by heating at 200 ° C. for 60 minutes. The film thickness after imidization was 1 μm. After forming the polyimide gate insulating film 16 in this way, a 4ThQ thin film is formed in the same manner as in Example 13, and a light irradiation process is performed on the place where the organic transistor 1B is formed, and a gold source is formed by vacuum evaporation. -Drain electrode and wiring were formed.

A lead wire was connected to the produced logic gate, and the organic transistor 1A was first wired as shown in FIG. 6 to measure the characteristics of the organic transistor 1A as a transistor. FIG. 24A shows the result of measuring the transfer characteristics in the saturation region under the condition of the drain voltage (V _d ) of −50V. The organic transistor 1A configured to include the polyimide insulating film 16 exhibited p-type characteristics. This example differs from Example 1 only in that the polyimide insulating film 16 is included, but it was found that the characteristic changed from the p-type biased bipolar type to the p-type characteristic. Also, hysteresis was greatly suppressed. Here, when the transfer characteristics of the organic transistor manufactured under the same conditions as those of the organic transistor 1B described in FIG. 11 (a) are shown in FIG. 24 (a), the organic transistor 1A and the gate voltage are about 20V. It can be seen that the magnitude of the drain current indicated by 1B is switched. The logic gate NOT2 of this embodiment is made of such a combination of organic transistors.

A voltage source and a voltmeter are connected to the logic gate NOT2 in the same manner as in the twelfth embodiment, and the change in the output voltage (V _out ) when the input voltage (V _in ) is swept is changed to various power supply voltages (V _DD ). Measured with The measurement result is shown in FIG. The calculated gain is shown in FIG. As shown in FIG. 24B, the output voltage (V _out ) is constant and does not fluctuate even at a low input voltage (V _in ) as compared with the thirteenth embodiment, and the LOW state is improved. It was. As a result, a logic circuit NOT stable in both HIGH and LOW could be manufactured. Operation with a power supply voltage of 10V was also confirmed. Moreover, as shown in FIG.24 (c), the gain was about 1.5.

(Example 15)
A logic gate using an organic transistor in which the thickness of the polyimide insulating film 16 is changed will be described below with reference to FIG.

  The logic gate NOT2 in the present embodiment is the same as the logic gate NOT2 in the embodiment 14, except that the thickness of the polyimide insulating film 16 of the organic transistor 1A constituting the logic gate NOT2 is changed. To 1 g of the solution in which the polyimide precursor was dissolved, 1.5 ml of N-methyl-2-pyrrolidone was added and diluted, and the polyimide insulating film 16 was applied with the diluted solution. Imidization was carried out in the same manner as in Example 14. The film thickness after imidization was 150 nm.

A lead wire was connected to the produced logic gate, and the organic transistor 1A was first wired as shown in FIG. 6 to measure the characteristics of the organic transistor 1A as a transistor. FIG. 25A shows the result of measuring the transfer characteristics in the saturation region under the condition of the drain voltage (V _d ) of −50V. Compared with the organic transistor 1A of Example 14, the off-current is suppressed, and the characteristics as a p-type organic transistor are further improved. The organic transistor 1B is the same as in Example 14. The logic gate NOT2 of this embodiment is made of such a combination of organic transistors.

A voltage source and a voltmeter are connected to the logic gate NOT2 in the same manner as in the twelfth embodiment, and the change in the output voltage (V _out ) when the input voltage (V _in ) is swept is changed to various power supply voltages (V _DD ). Measured with The measurement result is shown in FIG. The calculated gain is shown in FIG. As shown in FIG. 25B, the logic gate NOT2 in this embodiment has a sharper switching characteristic than that in the fourteenth embodiment. Further, as shown in FIG. 25C, the gain was improved to about 9.

(Example 16)
Another example in which the material of the substrate, the gate electrode, the gate insulating film, the source electrode and the drain electrode, and the wiring is different from that of the above-described logic gate is described below with reference to FIGS.

FIG. 26 is a schematic diagram showing the configuration of the organic transistor that constitutes the logic gate NOT2 of this embodiment. As shown in FIG. 26, an n-doped Si wafer with a thermal oxide film (SiO ₂ ) having a thickness of 300 nm was prepared and used as a substrate. An aluminum gate electrode having a thickness of 20 nm to 80 nm was formed on the thermal oxide film by a vacuum deposition method. A poly-4-vinylphenol (PVP) thin film having a thickness of 1 μm was formed as a polymer gate insulating film 12 on the substrate on which the gate electrode was arranged by spin coating as follows. 500 mg PVP (Sigma Aldrich), 0.19 ml crosslinker (Poly (melamine-co-formaldehyde) methylated solution (84 wt% in 1-butanol) (Sigma Aldrich)) and 4 ml propylene glycol methyl ether acetate (Sigma Aldrich) was mixed and dissolved, and spin coating was performed at a rotational speed of 2000 rpm for 30 seconds. Subsequently, crosslinking was performed by heating at 200 ° C. for 30 minutes. The thickness of the PVP gate insulating film 12 was 650 nm. Subsequently, a 4ThQ thin film having a thickness of about 90 nm was formed as the organic compound layer 13 on the PVP gate insulating film 12 by spin coating. At this time, a chloroform solution having a 4ThQ concentration of 10 mg / ml was prepared, and spin coating was performed at a rotational speed of 3000 rpm for 10 seconds. Vacuum drying was performed at 50 ° C. overnight. Subsequently, as shown in FIG. 20A, silver was vacuum-deposited to form source / drain electrodes 27A and 27B and wirings, whereby two organic transistors 1A and 1B were formed on the same substrate 19. The channel width was designed to be 4 mm and the channel length was 45 μm. The thickness was 20 nm to 80 nm.

A lead wire was connected to the manufactured logic gate, and wiring was first performed as shown in FIG. 6 to measure characteristics as an organic transistor. FIG. 27A shows the result of measuring the transfer characteristics in the saturation region under the condition of the drain voltage (V _d ) of 30V. As shown in FIG. 27 (a), the organic transistor in this example exhibited bipolar characteristics.

A voltage source and a voltmeter are connected to the logic gate NOT in the same manner as in the twelfth embodiment, and the change in the output voltage (V _out ) when the input voltage (V _in ) is swept is determined as the power supply voltage (V _DD ) of 30V. Measured with The measurement result is shown in FIG. The calculated gain is shown in FIG. As shown in FIGS. 20B and 20C, the logic gate NOT2 of this embodiment performs a switching operation at a lower input voltage (V _in ) than the logic gate of the above-described embodiment.

(Example 17)
A logic gate in which a region where any organic transistor is formed is subjected to light irradiation processing to convert the charge type of the organic compound layer will be described below with reference to FIG. The logic gate NOT of this embodiment is the same as that of the embodiment 16 except that the light irradiation process is performed on the organic transistor B to convert the charge type.

  After forming a 4ThQ thin film in the same manner as in Example 16, using a laser scanner with a wavelength of 1060 nm, light irradiation treatment was performed under the conditions of optical power 6.7 W, spot size 300 μm, scan interval 150 μm, and scan speed 10 mm / sec. It carried out to a part of 4ThQ thin film. Next, a silver source electrode and a drain electrode and a wiring were formed by vacuum deposition so that the organic transistor B was formed in the irradiated region. The organic transistor treated under this light irradiation condition exhibited n-type characteristics as shown in FIG. Therefore, the logic gate NOT2 of this embodiment is formed by combining the bipolar organic transistor 1A and the n-type organic transistor 1B.

A lead wire is connected to the produced logic gate, a voltage source and a voltmeter are connected in the same manner as in Example 12, and the change in the output voltage (V _out ) when the input voltage (V _in ) is swept is determined by the power supply of 30V. It was measured by voltage (V _DD ). The measurement results are shown in FIG. The calculated gain is shown in FIG. As shown in FIG. 28A, the HIGH state of the logic gate NOT2 of this embodiment is improved as compared to the sixteenth embodiment.

(Example 18)
An example of another logic gate in which the gate insulating film, the source electrode and the drain electrode, and the wiring are different from the logic gate NOT2 according to the example 16 will be described with reference to FIG.

  As shown in FIG. 19, after producing a gate electrode similarly to Example 16, the polyimide thin film with a film thickness of 1 micrometer was formed as a gate insulating film. The conditions for forming the polyimide thin film are the same as in Example 14. However, unlike the case of Example 14, the gate insulating film of the organic transistor 1B was also made of polyimide, so that it was not masked. Subsequently, a 4ThQ thin film was formed in the same manner as in Example 16. Subsequently, as shown in FIG. 20A, chromium having a film thickness of about 10 nm is vacuum-deposited to form source / drain electrodes 27A and 27B and wirings, whereby two organic transistors 1A and 1B are formed on the same substrate. Been formed. The channel width was designed to be 4 mm and the channel length was 20 μm. Further, gold having a film thickness of 20 nm to 80 nm was vacuum deposited on the wiring portion to reduce the wiring resistance.

A lead wire is connected to the logic gate NOT2, a voltage source and a voltmeter are connected in the same manner as in the twelfth embodiment, and the change in the output voltage (V _out ) when the input voltage (V _in ) is swept can be changed to various power supplies. It was measured by voltage (V _DD ). The measurement results are shown in FIG. The calculated gain is shown in FIG.

  As shown in FIG. 29B, the gain of the logic gate NOT2 of this embodiment is improved as compared to the sixteenth embodiment. In the logic gate NOT2 of the twelfth embodiment, the thermal oxide film of the Si wafer is used as the gate insulating film. However, in this embodiment, the polyimide insulating film is used as the gate insulating film. It has been clarified that if an electrode or the like suitable for each embodiment is selected, a logic gate can be produced even if an organic compound insulating film is used. Since an organic gate insulating film can be used, various substrates including a plastic substrate can be selected.

(Example 19)
A logic gate in which a region where any organic transistor is formed is subjected to light irradiation processing to convert the charge type of the organic compound layer will be described below with reference to FIG. The logic gate NOT2 of this example is the same as that of Example 18 except that the light irradiation process is performed on the organic transistor 1B to perform charge type conversion.

  After forming a 4ThQ thin film in the same manner as in Example 18, light irradiation treatment was performed using a laser scanner with a wavelength of 1060 nm under conditions of optical power 6.7 W, spot size 300 μm, scan interval 150 μm, and scan speed 0.1 mm / second. Was performed on a part of the 4ThQ thin film. Next, a chromium source electrode and drain electrode and a wiring were formed by vacuum deposition so that the organic transistor 1B was formed in the irradiated region. As in Example 18, gold having a thickness of 20 nm to 80 nm was vacuum deposited on the wiring portion.

A lead wire is connected to the manufactured logic gate, a voltage source and a voltmeter are connected in the same manner as in Example 12, and the change in the output voltage (V _out ) when the input voltage (V _in ) is swept can be changed to various power supplies. It was measured by voltage (V _DD ). The measurement result is shown in FIG. The calculated gain is shown in FIG. As shown in FIG. 30A, the HIGH state of the logic gate NOT2 of this embodiment is improved as compared with the eighteenth embodiment.

(Example 20)
An example in which the substrate of the organic transistor constituting the logic gate and the channel lengths of the source electrode and the drain electrode are different from those of the organic transistor constituting the above-described logic gate will be described below with reference to FIG. explain.

  The logic gate NOT2 of this example is the same as that of Example 18 except that the channel lengths of the substrate and the source and drain electrodes are changed. The substrate was a plastic substrate (Teonex Q65FA, Teijin DuPont Films) made of polyethylene naphthalate (PEN) and having a thickness of 125 μm. As shown in FIG. 26, an aluminum gate electrode, a polyimide gate insulating film, a 4ThQ thin film, a chromium source electrode and drain electrode, and a wiring were formed on the plastic substrate in the same manner as in Example 18. Gold having a thickness of 20 nm to 80 nm was vacuum deposited on the wiring portion. The channel width of the source and drain electrodes was designed to be 4 mm and the channel length was 45 μm. As a result, two organic transistors 1A and 1B were formed on the same substrate.

A lead wire was connected to the manufactured logic gate, and wiring was first performed as shown in FIG. 6 to measure characteristics as an organic transistor. FIG. 31A shows the result of measuring the transfer characteristics in the saturation region under the condition of the drain voltage (V _d ) of 50V. As shown in FIG. 31A, the organic transistor exhibited bipolar characteristics. It was also found that a plastic substrate functions as an organic transistor.

Subsequently, a voltage source and a voltmeter are connected to the fabricated logic gate NOT2 in the same manner as in Example 12, and the change in the output voltage (V _out ) when the input voltage (V _in ) is swept is determined as the power supply voltage of 50V. Measured with (V _DD ). The measurement result is shown in FIG. As shown in FIG. 31B, the operation of the logic gate according to this example as the logic gate NOT was confirmed. The maximum value of gain was 4. In this way, a logic gate could be manufactured even with a plastic substrate. Thereby, a lightweight semiconductor circuit can be produced.

(Example 21)
A logic gate in which a region where any organic transistor is formed is subjected to heat treatment to convert the charge type of the organic compound layer will be described below with reference to FIGS. The logic gate NOT2 of this example is the same as that of Example 20 except that the organic transistor 1B is subjected to heat treatment to perform charge type conversion.

  As in Example 20, after forming a gate electrode, a polyimide gate insulating film, and a 4ThQ thin film on a plastic substrate, they were placed on a metal block on a hot plate and partially heat-treated at 180 ° C. for 10 seconds. It was. Specifically, a small brass block corresponding to the size of the corresponding transistor is placed on a hot plate, and a substrate on which a 4ThQ thin film is formed is placed thereon, and partially heated at 180 ° C. for 10 seconds. went. Chromium source and drain electrodes and wiring were formed so that the organic transistor B was formed in the heat-treated region. Gold having a thickness of 20 nm to 80 nm was vacuum deposited on the wiring portion. The organic transistor treated under this heating condition exhibited n-type characteristics as shown in FIG. Therefore, the logic gate NOT2 of this embodiment is formed by combining the bipolar organic transistor 1A and the n-type organic transistor 1B.

A lead wire is connected to the manufactured logic gate, a voltage source and a voltmeter are connected in the same manner as in Example 12, and the change in the output voltage (V _out ) when the input voltage (V _in ) is swept is determined as a 50 V power supply. It was measured by voltage (V _DD ). The measurement results are shown in FIG. As shown in FIG. 32, the HIGH state of the logic gate NOT2 of this embodiment is improved as compared with the twentieth embodiment. The gain was improved to 8.

Subsequently, the characteristics when the substrate was bent were evaluated. The transfer function of the organic transistor 1A is shown in FIG. 33A, the switching characteristics of the logic gate NOT2 are shown in FIG. 33B, and the bending radius dependence of the gain G is shown in FIG. Incidentally, the gain _{when G 0} is not bent in FIG. 33 (c). That is, the vertical axis of the plot is normalized by the gain when not bent. From each result of FIGS. 33A to 33C, it was found that even when bent to a radius of curvature of 5 mm, it operates as an organic transistor, operates as a logic gate NOT, and gain variation is small. As described above, the logic gate NOT of this embodiment uses a plastic substrate and enables a flexible semiconductor circuit that operates even when bent.

(Example 22)
A logic gate NAND3 formed using an organic transistor having an organic compound layer formed of 4ThQ will be described below with reference to FIGS. The logic gate NAND3 of the present embodiment is an element in which the organic transistor 1A and the organic transistor B manufactured in the same manner as in the nineteenth embodiment are combined. However, unlike the case of Example 19, four organic transistors 1h, 1i, 1j and 1k are used.

  In the same manner as in Example 19, a silicon wafer with a thermal oxide film was used as a substrate, and an aluminum gate electrode and wiring were formed thereon as shown in FIG. Subsequently, a polyimide gate insulating film and a 4ThQ thin film were formed. After forming the 4ThQ thin film, using a laser scanner with a wavelength of 1060 nm, the light irradiation process under the conditions of optical power 6.7 W, spot size 300 μm, scan interval 150 μm, and scan speed 0.1 mm / second is performed on the organic transistor j and This was done for the region corresponding to k. After the light irradiation, as shown in FIG. 34 (b), chromium source / drain electrodes 27h, 27i, 27j and 27k, and wirings were formed by vacuum deposition. Gold having a thickness of 20 nm to 80 nm was vacuum deposited on the wiring portion. The channel width of the source and drain electrodes was designed to be 4 mm and the channel length was 20 μm.

A lead wire is connected to the manufactured logic gate, and as shown in FIG. 35, a voltage source for applying a power supply voltage (V _DD ), a voltage source for applying a voltage of input X (V _inX ), and an input A voltage source for applying the Y voltage (V _inY ) and a voltmeter for measuring the output voltage (V _out ) were connected. Changes in the output voltage (V _out ) when the input X voltage (V _inX ) is swept when 70 V is applied as the power supply voltage (V _DD ) and the input Y voltage (V _inY ) is 0 V and 70 V. This is shown in FIG. In addition, FIG. 36B shows the results collectively expressed as LOW and HIGH states according to the input and output voltage (V _out ). As shown in FIGS. 36A and 36B, the output is LOW only when both the input X and the input Y are HIGH. That is, the logic gate of this example functioned as a NAND.

(Example 23)
A logic gate NOR4 formed by using an organic transistor in which an organic compound layer is formed of 4ThQ will be described below with reference to FIGS. The logic gate NOR4 of this embodiment is an element in which an organic transistor 1A and an organic transistor 1B manufactured in the same manner as in Embodiment 19 are combined. However, unlike the case of Example 19, four organic transistors 1h, 1i, 1j and 1k are used.

  In the same manner as in Example 19, a silicon wafer with a thermal oxide film was used as a substrate, and an aluminum gate electrode and wiring were formed thereon as shown in FIG. Subsequently, a polyimide gate insulating film and a 4ThQ thin film were formed. After the 4ThQ thin film was formed, the light irradiation treatment under the same conditions as in Example 22 was performed on the regions corresponding to the organic transistors h and i. After the light irradiation, as shown in FIG. 34 (b), chromium source / drain electrodes 27h, 27i, 27j and 27k, and wirings were formed by vacuum deposition. Gold having a thickness of 20 nm to 80 nm was vacuum deposited on the wiring portion. The channel width of the source and drain electrodes was designed to be 4 mm and the channel length was 20 μm.

A lead wire is connected to the produced logic gate, and as shown in FIG. 37, a voltage source for applying a power supply voltage (V _DD ), a voltage source for applying a voltage of input X (V _inX ), and an input A voltage source for applying the Y voltage (V _inY ) and a voltmeter for measuring the output voltage (V _out ) were connected. Changes in the output voltage (V _out ) when the input X voltage (V _inX ) is swept when 50 V is applied as the power supply voltage (V _DD ) and the input Y voltage (V _inY ) is 0 V and 70 V. This is shown in FIG. Further, FIG. 38B shows the results collectively expressed as LOW and HIGH states according to the input and output voltage (V _out ). As shown in FIGS. 38A and 38B, the output becomes HIGH only when both the input X and the input Y are LOW. That is, the logic gate of this example functioned as NOR.

(Example 24)
A rectifying organic diode that has an organic compound layer formed of 4ThQ and is obtained by performing light irradiation treatment on the organic compound layer will be described below with reference to FIG.

  FIG. 39 is a schematic diagram showing the configuration of the organic diode in this example. As shown in FIG. 39, the organic diode 5 in this embodiment is an organic semiconductor element in which an anode 32, an organic compound layer 33 having semiconductor characteristics, and a cathode 31 are sequentially laminated on a substrate. By performing light irradiation treatment on at least part of the portion of the organic compound layer 33 that overlaps the anode 32 and the cathode 31, a region 33 ′ having a changed charge type is formed, and rectification is obtained.

  The organic diode 5 uses a Si wafer 35 with a thermal oxide film as a substrate, and a chromium anode with a film thickness of 20 nm to 80 nm is formed thereon by a vacuum deposition method. Subsequently, as in Example 1, a 4ThQ thin film having a thickness of about 90 nm was formed as an organic compound layer by spin coating. At this time, a chloroform solution having a concentration of 4 ThQ of 10 mg / ml was prepared, and spin coating was performed at a rotation speed of 3000 rpm for 10 seconds. Vacuum drying was performed at 50 ° C. overnight. This 4ThQ thin film was prepared by heat treatment, by light irradiation treatment using a laser scanner with a wavelength of 1060 nm, and without any treatment. Here, the heat treatment condition is 180 ° C. for 10 seconds. Further, the light irradiation treatment conditions were an optical power of 3.3 W, a spot size of 300 μm, a scan interval of 150 μm, and a scan speed of 0.1 mm / second. The light irradiation treatment conditions are weaker energy than the treatment conditions for the charge type conversion of the organic transistor such as Example 22. The light irradiation treatment was performed on the entire region overlapping with the cathode and the peripheral region. The heat treatment conditions are the same as the treatment conditions for the charge type conversion of the organic transistor such as Example 6. Subsequently, a chromium cathode having a thickness of 20 nm or more was formed on the 4ThQ thin film by vacuum deposition. The cathode was arranged so that the entire surface overlapped with the processed region. As described above, a heat-treated organic semiconductor element, a light-irradiated organic semiconductor element, and an untreated organic semiconductor element were produced.

  A lead wire was connected to each of the produced organic semiconductor elements, and a voltage source and an ammeter were connected as shown in FIG. The measured current-voltage characteristics are shown in FIG. As shown in FIG. 40, linear characteristics were obtained in the element that was not processed and the element that was heat-treated. From this, it was found that ohmic contact was obtained at the electrode interface. This is because the work function of chromium is 4.5 eV. However, as shown in FIG. 3, in the 4ThQ thin film, the HOMO level before treatment is 4.5 eV, and the LUMO level after heat treatment is 4.5 eV. This is considered to be consistent with the work function. On the other hand, the device irradiated with light was confirmed to have rectification and functioned as a diode. As shown in FIG. 39A, the HOMO / LUMO level on the cathode side has changed due to weak light irradiation treatment conditions, but it is assumed that the HOMO / LUMO level on the anode side has not changed. In other words, the HOMO / LUMO level on the anode side is different from the HOMO / LUMO level on the cathode side. In other words, it is assumed that a pn junction is formed in the 4ThQ thin film. It can be said that the charge type on the anode side and the charge type on the cathode side are different.

(Example 25)
With reference to FIGS. 41 and 42, an organic transistor in which the region for light irradiation treatment and the channel width are changed will be described below. The organic transistor of this example differs from the organic transistor 1B of Example 19 only in the region of light irradiation treatment and the channel width. FIG. 41A is a schematic cross-sectional view showing the configuration of the organic transistor 6 of this example, and FIG. 41B is a top view of the organic transistor 6. FIG. 41A is a cross section taken along line XX ′ in FIG.

  As shown in FIG. 41A, an Si wafer 48 with a thermal oxide film was used as a substrate 49, and an aluminum gate electrode 41 and wirings were formed thereon. Subsequently, a 1 μm thick polyimide gate insulating film 42 and a 90 nm thick 4ThQ thin film were formed. Using a laser scanner with a wavelength of 1060 nm, light irradiation treatment is performed on a part of the 4ThQ thin film through a mask under the conditions of optical power 6.7 W, spot size 300 μm, scan interval 150 μm, and scan speed 0.1 mm / second. went. Subsequently, as shown in FIG. 41 (b), the source of chromium so that the light irradiation region is included in the active region and the boundary between the light irradiation region and the non-irradiation region is substantially perpendicular to the channel direction. The electrode 44, the drain electrode 46, and wiring (not shown) were formed by a vacuum evaporation method. Gold having a thickness of 20 nm to 80 nm was vacuum deposited on the wiring portion. The channel width was 0.3 mm and the channel length was 45 μm. Therefore, in this organic transistor 6, organic compound layers having different charge types are formed between the source and drain electrodes. In other words, a semiconductor junction is formed in a single organic compound layer.

A voltage source and an ammeter were connected to the produced organic transistor 6 in the same manner as in Example 1, various drain voltages (V _d ) were applied, and transfer characteristics were measured. FIG. 42A shows a case where a positive drain voltage (V _d ) is applied, and FIG. 42B shows a case where a negative drain voltage (V _d ) is applied.

As shown in FIGS. 42 (a) and 42 (b), different transfer characteristics and different charge types were obtained depending on the drain voltage (V _d ). In the case of a positive drain voltage, an n-type ambipolar characteristic was obtained, whereas in the case of a negative drain voltage (V _d ), particularly a drain voltage (V _d ) of −10 V, a p-type characteristic was obtained. As a result, almost n-type characteristics were obtained. That is, the charge type could be controlled in accordance with the positive / negative drain voltage (V _d ).

Next, FIG. 42C shows changes in drain current (I _d ), that is, output characteristics, when various gate voltages (V _g ) are applied and the drain voltage (V _d ) is swept.

In the case of a positive drain voltage (V _d ), the drain current (I _d ) hardly depends on the gate voltage (V _g ), whereas in the case of a negative drain voltage (V _d ), the drain current (I _d). ) _Varied depending on the gate voltage (V _g ). That is, the rectification property changes according to the gate voltage (V _g ). This means that a diode whose rectification property can be controlled by the gate voltage (V _g ) has been produced. In addition, a diode exhibiting rectifying properties can be obtained with one type of source / drain electrodes in the same layer, which is advantageous when combined with other logic gates. Actually, the organic transistor in this embodiment is manufactured by the same process as the logic gate NAND of the embodiment 22 and the logic gate NOR of the embodiment 23, and the diode and the logic gate can be manufactured simultaneously.

Note that when the gate voltage (V _g ) is 0 V, diode characteristics exhibiting rectification are obtained. Therefore, the gate electrode and the gate insulating film are unnecessary when it is desired to simply manufacture a diode exhibiting rectification. If an organic compound layer on a substrate is subjected to light irradiation treatment as described above to form an electrode, an organic diode can be obtained.

  In this embodiment, the boundary between the light irradiation region and the non-irradiation region is set to be substantially perpendicular to the channel direction. However, the active region is divided into the light irradiation region and the non-irradiation region. As long as a semiconductor junction is formed between the source and drain electrodes, the junction is not necessarily vertical but may be inclined.

  As described above, it was shown that 4ThQ can form a high-quality thin film that can be used for a semiconductor element by a solution process, and an organic transistor that operates stably in the atmosphere was realized. Since it can be produced by a solution process, it can be easily formed into a thin film with low energy and is suitable for increasing the area. An organic transistor whose charge type is changed by heat treatment, light irradiation treatment and solvent treatment was realized. In addition, logic gates were also fabricated by combining treated organic transistors and untreated organic transistors. By using the organic insulating film, the hysteresis in the characteristic curve of the organic transistor could be reduced. A plastic substrate that can be bent can be used as the substrate, and it has been confirmed that it can operate as a logic gate NOT even if it is bent to a curvature radius of 5 mm. Note that the logic gate NOT is synonymous with an inverter.

  Furthermore, by performing a solvent treatment on the organic transistor converted to n-type by heat treatment, it was possible to return to the bipolar type again. In addition, the charge type could be made differently by changing the solvent used when spin-coating the organic compound layer. In addition, a logic gate NOT was fabricated using two bipolar organic transistors that were not processed. In addition, the ratio of the hole mobility and the electron mobility of the ambipolar organic transistor can be controlled by the film thickness, and a symmetrical ambipolar organic transistor in which the hole mobility and the electron mobility are almost equal can be produced. It was also shown that the ratio of hole mobility to electron mobility can be controlled by source / drain electrodes, materials, and channel length. In addition, in an organic semiconductor element in which an anode, an organic compound layer, and a cathode are sequentially stacked, by examining the conditions of light irradiation treatment, only the surface of the organic compound is converted, and a diode exhibiting rectification is manufactured. I was able to.

  Furthermore, if the present invention is applied to an ink-jet method that has been studied as a method for producing an organic semiconductor circuit, charge types can be created according to the solvent used, and therefore p-type, n-type, and bipolar organic types such as logic gates are used. An organic semiconductor circuit in which transistors are combined can be manufactured.

  In addition, if the present invention is applied, the charge type can be converted by heat treatment, so that fine pn patterning using thermal lithography can be performed.

  In addition, if the present invention is applied, the charge type can be converted by heat treatment. Therefore, by heating a mold having a fine pattern used for nanoimprint or the like and using it for the heat treatment of the organic compound layer, fine pn Patterning can be performed.

  In addition, if the present invention is applied, the charge type can be converted by the light irradiation treatment, so that fine pn patterning using a near-field optical microscope can be performed.

  Further, the semiconductor element and the semiconductor device according to the present invention can be miniaturized regardless of the solution process because the organic compound layer can be formed of a single compound.

  The present invention can be used in all fields where semiconductor materials such as TFTs and diodes are used.

1, 1A, 1B Organic transistor 1h-1k Organic transistor 2 Logic gate NOT
3 logic gate NAND
4 logic gate NOR
DESCRIPTION OF SYMBOLS 5 Organic diode 6 Organic transistor 11 Gate electrode 11h-11k Gate electrode 12 Gate insulating film 13 Organic compound layer 13 'Organic compound layer 14 of charge type conversion 14, 14A, 14B Source electrode 15, 15A, 15B Drain electrode 16 Polyimide Insulating film 17 SiO ₂ Insulating film 18 Si wafer 19 Substrate 21 Power terminal 22, 22X, 22Y Input terminal 23 Output terminal 24 Reference terminal 25h, 25i, 25k Terminal 26 Metal electrode / wiring 27A, 27B Source / drain electrode 27h-27k Source drain electrode 31 cathode 32 anode 33 organic compound layer 33 'organic compound layer 34 SiO ₂ insulating film 35 Si wafer 36 substrate 37 ammeter 38 voltage source 41 the gate electrode 42 a gate insulating film 43a organizing the charge type of conversion has been made Things layer 43b organic compound charge type of transformation is made layer 44 source electrode 45 in the channel direction 46 the drain electrode 47 SiO ₂ insulating film 48 Si wafer 49 substrate

Claims (24)

A method for producing a semiconductor element, wherein the semiconductor layer is an organic compound layer formed of a compound represented by the following general formula (1):
By subjecting the organic compound layer to at least one of heat treatment, light irradiation treatment, and solvent treatment, the organic compound layer has n-type characteristics, p-type characteristics, or bipolar characteristics. A method of manufacturing a semiconductor device, comprising a step of changing to another of n-type characteristics, p-type characteristics, and bipolar characteristics.
(In Formula (1), each R ¹ independently represents an alkyl group having 20 or less carbon atoms, the alkyl group may have a methoxy group, m represents 1 or 2, and X represents oxygen. , A cyanoimino group, a dicyanomethylene group or an organic group represented by the following chemical formula (2), (3) or (4), Z is sulfur, selenium or tellurium, and R ² is an alkyl group having 20 or less carbon atoms. * Represents a double bond portion of X in the general formula (1).)
The production method according to claim 1, wherein the compound represented by the general formula (1) is a compound represented by the following general formula (5).
(In Formula (5), R ³ is H or nC ₆ H ₁₃ , R ⁴ is H or nC ₆ H ₁₂ OCH ₃ , and X is the same as X in Formula (1)) .)   The manufacturing method according to claim 1, wherein the heat treatment is performed at 100 ° C. or higher and 240 ° C. or lower. 3. The manufacturing method according to claim 1, wherein in the light irradiation treatment, light having a wavelength of 550 nm to 1750 nm and an energy of 1 J / cm ^{2 to} 500 KJ / cm ² is irradiated. .   The method according to claim 1 or 2, wherein the solvent treatment is a treatment in which the organic compound layer is exposed to a vapor of chloroform, dichloromethane, tetrachloroethane, or tetrachloromethane. The semiconductor element is an organic transistor having a gate electrode, a gate insulating film, a source electrode, a drain electrode and the organic compound layer on a substrate,
6. The manufacturing method according to claim 1, wherein each of the treatments is performed on a region of the organic compound layer between the source electrode and the drain electrode. .   Each of the above treatments is also performed on a region of the organic compound layer where the source electrode and the drain electrode are formed and continuous with a region between the source electrode and the drain electrode. The manufacturing method according to claim 6, wherein the manufacturing method is performed.   The manufacturing method according to claim 1, wherein the organic compound layer is formed by a solution process. The semiconductor layer includes a plurality of semiconductor elements that are organic compound layers formed of a compound represented by the following general formula (1), and the organic compound layer has n-type characteristics. A method for manufacturing a semiconductor device, comprising at least two of a semiconductor element having a p-type characteristic and a semiconductor element having a bipolar characteristic,
By performing at least one of heat treatment, light irradiation treatment and solvent treatment on a specific region of the organic compound layer, the n-type characteristics of the organic compound layer in the specific region, p-type A method of manufacturing a semiconductor device comprising a step of changing a characteristic or a bipolar characteristic to another characteristic among an n-type characteristic, a p-type characteristic, and a bipolar characteristic.
(In Formula (1), each R ¹ independently represents an alkyl group having 20 or less carbon atoms, the alkyl group may have a methoxy group, m represents 1 or 2, and X represents oxygen. , A cyanoimino group, a dicyanomethylene group or an organic group represented by the following chemical formula (2), (3) or (4), Z is sulfur, selenium or tellurium, and R ² is an alkyl group having 20 or less carbon atoms. * Represents a double bond portion of X in the general formula (1).)
The production method according to claim 9, wherein the compound represented by the general formula (1) is a compound represented by the following general formula (5).
(In Formula (5), R ³ is H or nC ₆ H ₁₃ , R ⁴ is H or nC ₆ H ₁₂ OCH ₃ , and X is the same as X in Formula (1)) .) The semiconductor element is an organic compound layer formed of a compound represented by the following general formula (1),
The organic compound layer has a single composition,
A semiconductor having at least two of a region having n-type characteristics, a region having p-type characteristics, and a region having bipolar characteristics formed in the organic compound layer element.
(In Formula (1), each R ¹ independently represents an alkyl group having 20 or less carbon atoms, the alkyl group may have a methoxy group, m represents 1 or 2, and X represents oxygen. , A cyanoimino group, a dicyanomethylene group or an organic group represented by the following chemical formula (2), (3) or (4), Z is sulfur, selenium or tellurium, and R ² is an alkyl group having 20 or less carbon atoms. * Represents a double bond portion of X in the general formula (1).)
12. The semiconductor device according to claim 11, wherein the compound represented by the general formula (1) is a compound represented by the following general formula (5).
(In Formula (5), R ³ is H or nC ₆ H ₁₃ , R ⁴ is H or nC ₆ H ₁₂ OCH ₃ , and X is the same as X in Formula (1)) .)
  Any one of the at least two regions is a region formed by performing any one of heat treatment, light irradiation treatment, and solvent treatment on the organic compound layer. The semiconductor device according to claim 11 or 12.   14. The semiconductor device according to claim 11, wherein the at least two regions are formed of the same compound. An organic diode comprising a cathode and an anode facing each other, and an organic compound layer formed of a compound represented by the following general formula (1) sandwiched between the cathode and the anode,
The organic compound layer has a single composition,
Each region where the cathode and the anode of the organic compound layer are disposed has any one of n-type characteristics, p-type characteristics, and bipolar characteristics, and is different from each other. An organic diode characterized by its characteristics.
(In Formula (1), each R ¹ independently represents an alkyl group having 20 or less carbon atoms, the alkyl group may have a methoxy group, m represents 1 or 2, and X represents oxygen. , A cyanoimino group, a dicyanomethylene group or an organic group represented by the following chemical formula (2), (3) or (4), Z is sulfur, selenium or tellurium, and R ² is an alkyl group having 20 or less carbon atoms. * Represents a double bond portion of X in the general formula (1).)
The organic diode according to claim 15, wherein the compound represented by the general formula (1) is a compound represented by the following general formula (5).
(In Formula (5), R ³ is H or nC ₆ H ₁₃ , R ⁴ is H or nC ₆ H ₁₂ OCH ₃ , and X is the same as X in Formula (1)) .) An organic transistor comprising a gate electrode, a gate insulating film, a semiconductor layer, a source electrode and a drain electrode on a substrate,
The semiconductor layer is an organic compound layer formed of a compound represented by the following general formula (1),
The organic compound layer has a single composition,
Each region where the source electrode and the drain electrode of the organic compound layer are formed has any one of n-type characteristics, p-type characteristics, and bipolar characteristics, and characteristics different from each other. An organic transistor characterized by being.
(In Formula (1), each R ¹ independently represents an alkyl group having 20 or less carbon atoms, the alkyl group may have a methoxy group, m represents 1 or 2, and X represents oxygen. , A cyanoimino group, a dicyanomethylene group or an organic group represented by the following chemical formula (2), (3) or (4), Z is sulfur, selenium or tellurium, and R ² is an alkyl group having 20 or less carbon atoms. * Represents a double bond portion of X in the general formula (1).)
The organic transistor according to claim 17, wherein the compound represented by the general formula (1) is a compound represented by the following general formula (5).
(In Formula (5), R ³ is H or nC ₆ H ₁₃ , R ⁴ is H or nC ₆ H ₁₂ OCH ₃ , and X is the same as X in Formula (1)) .) A semiconductor device comprising a plurality of semiconductor elements, wherein the semiconductor layer is an organic compound layer formed of a compound represented by the following general formula (1):
The plurality of semiconductor elements include at least two of a semiconductor element in which the organic compound layer has n-type characteristics, a semiconductor element having p-type characteristics, and a semiconductor element having bipolar characteristics. And
The organic compound layer of the at least two types of semiconductor elements has the same composition as each other.
(In Formula (1), each R ¹ independently represents an alkyl group having 20 or less carbon atoms, the alkyl group may have a methoxy group, m represents 1 or 2, and X represents oxygen. , A cyanoimino group, a dicyanomethylene group or an organic group represented by the following chemical formula (2), (3) or (4), Z is sulfur, selenium or tellurium, and R ² is an alkyl group having 20 or less carbon atoms. * Represents a double bond portion of X in the general formula (1).)
The semiconductor device according to claim 19, wherein the compound represented by the general formula (1) is a compound represented by the following general formula (5).
(In Formula (5), R ³ is H or nC ₆ H ₁₃ , R ⁴ is H or nC ₆ H ₁₂ OCH ₃ , and X is the same as X in Formula (1)) .)   21. The semiconductor device according to claim 19, wherein a logic circuit is configured by combining the at least two types of semiconductor elements.   22. The semiconductor device according to claim 19, wherein each of the organic compound layers of the plurality of semiconductor elements is formed of the same compound. A semiconductor element comprising a gate electrode, a gate insulating film, a semiconductor layer, a source electrode and a drain electrode on a substrate,
The said semiconductor layer is formed with the compound represented by following General formula (1), The semiconductor element characterized by the above-mentioned.
(In Formula (1), each R ¹ independently represents an alkyl group having 20 or less carbon atoms, the alkyl group may have a methoxy group, m represents 1 or 2, and X represents oxygen. , A cyanoimino group, a dicyanomethylene group or an organic group represented by the following chemical formula (2), (3) or (4), Z is sulfur, selenium or tellurium, and R ² is an alkyl group having 20 or less carbon atoms. * Represents a double bond portion of X in the general formula (1).)
24. The semiconductor device according to claim 23, wherein the compound represented by the general formula (1) is a compound represented by the following general formula (5).
(In Formula (5), R ³ is H or nC ₆ H ₁₃ , R ⁴ is H or nC ₆ H ₁₂ OCH ₃ , and X is the same as X in Formula (1)) .)