Patent Application
20240147741
The present invention relates to an inorganic/organic hybrid complementary semiconductor device and a method for manufacturing the same.
Semiconductor devices are expected to be basic elements of electronic devices in the Internet of Things (IoT) society. In particular, a complementary metal oxide semiconductor (CMOS) including p-type and n-type transistors has been a foundation technology of a current integrated circuit.
Non-Patent Literature 1: Takeda, Y et al. Appl. Sci. 2018, 8, 1331
Non-Patent Literature 2: K. Hong. et al. Adv. Mater. 2014, 26, 7032
Non-Patent Literature 3: M. Uno, et al. Adv. Electron. Mater. 2015, 1, 1500178
Non-Patent Literature 4: K. J. Baeg, et al. Org. Electron. 2013, 14, 1407
Non-Patent Literature 5: S. H. Kim, et al, IEEE Electron Device Lett. 2013, 34, 307
Non-Patent Literature 6: W. Smaal, et al. Org. Electron. 2012, 13, 1686
Non-Patent Literature 7: L. Herlogsson, et al. Adv. Mater. 2011, 23. 4684
However, there is still a need for an inexpensive CMOS that can be manufactured on a large scale. In addition, a CMOS that has excellent long-term stability, has a well-balanced operation between a p-type transistor and an n-type transistor, and operates at a high speed.
The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a complementary semiconductor device that can be manufactured at a lower cost, has excellent long-term stability, has the well-balanced operation between the p-type transistor and the n-type transistor, and operates at a high speed.
The gist of an embodiment of the present invention is as follows.
According to the present invention, a complementary semiconductor device that can be manufactured at a lower cost, has excellent long-term stability, has well-balanced operation between a p-type transistor and a n-type transistor, and operates at a high speed can be provided.
The present disclosure is directed to an inorganic/organic hybrid complementary semiconductor device including a substrate, a p-type organic semiconductor single crystal layer, an n-type amorphous metal oxide inorganic semiconductor layer between the substrate and the p-type organic semiconductor single crystal layer, and a protective layer between the p-type organic semiconductor single crystal layer and the n-type amorphous metal oxide inorganic semiconductor layer, in which, when viewed from a direction perpendicular to a main surface of the p-type organic semiconductor single crystal layer, the p-type organic semiconductor single crystal layer is disposed and thus at least a part of the p-type organic semiconductor single crystal layer overlaps the n-type amorphous metal oxide inorganic semiconductor layer or the p-type organic semiconductor single crystal layer does not overlap the n-type amorphous metal oxide inorganic semiconductor layer, a distance between the p-type organic semiconductor single crystal layer and the n-type amorphous metal oxide inorganic semiconductor layer is 1 mm or less, and the n-type amorphous metal oxide inorganic semiconductor layer has a distribution of an oxygen defect amount in a thickness direction in which the oxygen defect amount is larger on the p-type organic semiconductor single crystal layer side than on the substrate side.
The inorganic/organic hybrid complementary semiconductor device of the present disclosure (hereinafter, also referred to as a complementary semiconductor device) includes an amorphous metal oxide inorganic semiconductor layer (hereinafter, also referred to as an AOS layer) and an organic semiconductor single crystal layer formed under air atmosphere by using a solution process. Therefore, in the manufacture of the complementary semiconductor device of the present disclosure, a special apparatus such as a high vacuum chamber used in dry process is not required, and the manufacturing cost can be reduced as compared with the related art. In particular, in a case where a large area is to be achieved, increase in the size of the special apparatus such as the high vacuum chamber is not required, and the cost reduction effect is further increased as compared with the dry process.
The complementary semiconductor device of the present disclosure has also excellent long-term stability, and can exhibit substantially the same characteristics before and after being left to stand under air atmosphere for five months.
Since the p-type transistor is made of the organic semiconductor single crystal and the n-type transistor is made of the AOS, the operations of the p-type transistor and the n-type transistor are well-balanced, and the complementary semiconductor device of the present disclosure can operate at a high speed.
Since the AOS layer is formed by the solution process, oxygen deficiency occurs on the surface of the AOS layer, and as schematically illustrated in
Therefore, the AOS layer formed by a solvolysis method operates particularly well when the thickness is preferably from 4 nm to 7 nm, more preferably from 5 nm to 6 nm. Surface oxygen deficiency is exploited to maximize device performance. An
AOS film formed by the dry process such as sputtering does not have such a distribution of oxygen deficiency states. A film thickness of the AOS layer can be adjusted by, for example, changing a metal ion concentration in a precursor solution.
The distribution of the oxygen defect amount of the AOS layer in the thickness direction can be evaluated by measuring an angle dependence of a ratio (ηM—O—M) of M—O—M (in a metal oxide state) to the entire O1s by angle-resolved X-ray photoelectron spectroscopy (XPS). In the AOS layer having the distribution of the oxygen defect amount in the thickness direction, the closer to the outermost surface of the AOS layer, the less M—O—M (M: In or Zn) bonds.
As illustrated in
, where I0 is an incident electron intensity, I(d) is effective intensity at a depth d from a surface, λ is an inelastic mean free path of electrons in a solid (estimated to be about 2.8 nm under the present measurement condition), and 3λ is an escape depth (I(d) to I0×5%), and
, where d is a depth from the surface, dinf is a detection depth (information depth), and θsub is a tilt angle of the substrate, by changing an angle (inclination angle θ) with respect to an XPS detector (analyzer) with reference (0°) to a direction perpendicular to a surface of a measurement sample. The inclination angle θ can be set in a range from 0° to less than 90°, and preferably from 0° to 70°.
In the AOS layer, a ratio of ηM—O—M of the outermost surface to ηM—O—M of the inside is preferably smaller by 10% or more, more preferably smaller by 15% or more, and still more preferably smaller by 20% or more.
The AOS layer preferably has an area of 0.0025 mm2 or greater, more preferably 0.005 mm2 or greater, still more preferably 0.5 mm2 or greater, and yet still more preferably 2.0 mm2 or greater.
The AOS layer exhibits a mobility of preferably 0.5 cm2/V·s or greater, more preferably 3.0 cm2/V·s or greater, still more preferably 5.0 cm2/V·s or greater, yet still more preferably 7.5 cm2/V·s or greater, yet still more preferably 10 cm2/V·s or greater. The mobility of the AOS layer can be calculated from the measurement result of an organic field effect transistor.
The type of the inorganic semiconductor constituting the AOS layer is not particularly limited, and for example, ZnO, In2O3, Zn—O (IZO), In—Ga—Zn—O (IGZO), or the like may be used.
Whether the AOS layer is amorphous can be confirmed by thin film X-ray diffraction.
The average film thickness of the organic semiconductor single crystal layer is preferably from 2 nm to 100 nm and more preferably from 4 nm to 20 nm. The upper limit of the average film thickness of the organic semiconductor single crystal layer may be 18 nm or less, 16 nm or less, 14 nm or less, 12 nm or less, 10 nm or less, or 8 nm or less. When the average film thickness of the organic semiconductor single crystal layer is in the above range, good device characteristics can be obtained. The average film thickness of the organic semiconductor single crystal layer can be measured using a stylus type surface profile measuring instrument or an atomic force microscope.
The organic semiconductor single crystal layer has preferably from 1 molecular layer to 50 molecular layers, more preferably from 1 molecular layer to 10 molecular layers, still more preferably from 1 molecular layer to 5 molecular layers, even still more preferably from 1 molecular layer to 4 molecular layers, even still more preferably from 1 molecular layer to 3 molecular layers, and even still more preferably from 1 molecular layer to 2 molecular layers in the thickness direction. The organic semiconductor single crystal layer has most preferably 1 molecular layer, but may have 2 or more molecular layers in the thickness direction. The number of molecular layers of the organic semiconductor single crystal layer can be measured by the atomic force microscope.
The film thickness of 1 molecular layer of the organic semiconductor single crystal layer is preferably from 2 nm to 6 nm and more preferably from 2 nm to 4 nm. The thickness of 1 molecular layer of the organic semiconductor single crystal layer can be measured by combining single crystal X-ray structure analysis and atomic force microscope observation.
The organic semiconductor single crystal layer is composed of a single domain or a multi domain, and is preferably composed of the single domain. The domain of the organic semiconductor single crystal layer can be measured by single crystal X-ray diffraction. The organic semiconductor single crystal layer has the single domain having a continuous area of preferably 0.0025 mm2 or greater, more preferably 0.005 mm2 or greater, still more preferably 0.5 mm2 or greater, and yet still more preferably 2.0 mm2 or greater. The area of the single domain of the organic semiconductor single crystal layer may be the same as the above-described preferable area of the AOS. The area of the organic semiconductor single crystal layer may be the same as the area of the single domain.
It should be understood that a separated organic semiconductor single crystal layer including the above-described single domain having the preferable continuous area may be incorporated in the organic semiconductor single crystal layer in the complementary semiconductor device of the present disclosure. For example, the organic semiconductor single crystal layer including the above-described single domain having the preferable continuous area may be separated into a plurality of pieces of the organic semiconductor single crystal layers and incorporated into the organic semiconductor device, and/or an unnecessary portion of the organic semiconductor single crystal layer including the above-described single domain having the preferable continuous area may be etched by photolithography or the like to be separated into the plurality of pieces of the organic semiconductor single crystal layers and incorporated into the complementary semiconductor device. Each organic semiconductor single crystal layer is separated in the complementary semiconductor device, and thus it can be electrically isolated from other elements. The fact that each separated organic semiconductor single crystal layer is obtained from a single crystal film having an aligned crystal axis direction can be confirmed by measurement by the single crystal X-ray diffraction, electron diffraction, or an observation with a polarizing microscope.
The organic semiconductor single crystal layer exhibits a mobility of preferably 0.5 cm2/V·s or greater, more preferably 3.0 cm2/V·s or greater, still more preferably 5.0 cm2/V·s or greater, yet still more preferably 7.5 cm2/V·s or greater, yet still more preferably 10 cm2/V·s or greater. The mobility of the organic semiconductor single crystal layer can be calculated from the measurement result of the organic field effect transistor.
The type of the organic semiconductor constituting the organic semiconductor single crystal layer is not particularly limited, and for example, a polycyclic aromatic compound having four or more rings or a polycyclic compound having four or more rings including 1 one or more unsaturated five-membered heterocyclic compounds and a plurality of benzene rings may be used.
The organic semiconductor constituting the organic semiconductor single crystal layer is preferably a material having a high self-condensation function, and examples thereof include a p-type organic semiconductor Cn-DNBDT-NW of the following Formula (1) exhibiting high mobility.
In the Formula (1), n may be from 1 to 14. The self-condensation function means a tendency of molecules to spontaneously aggregate and crystallize easily when the molecules are precipitated from a solvent.
Other examples of the organic semiconductor constituting the organic semiconductor single crystal layer are illustrated in the following Formulas (2) to (5).
In the Formula (2), each of R3, R4, R5, and R6 is independently a hydrogen atom or an alkyl group containing from 1 to 14 carbons. The alkyl group may contain a hetero atom (typically selected from an oxygen atom and a sulfur atom), and a hydrogen atom in the alkyl group may he substituted with a substituent such as a halogen atom. For reasons of self-aggregation capacity, it is preferable that R4=R5, and it is preferable that R3=R6. From the viewpoint of solubility, R4 and R5 are preferably hydrogen atoms and each of R3 and R6 is independently an alkyl group containing from 1 to 14 carbons, or R3 and R6 are hydrogen atoms and each of R4 and R5 is independently an alkyl group containing from 1 to 14 carbons. More preferably, R3 and R6 are hydrogen atoms, and each of R4 and R5 is independently an alkyl group containing from 1 to 14 carbons. For reasons of self-aggregation capacity, the number of carbons of the alkyl group is preferably from 4 to 12, and more preferably from 6 to 10.
In the Formula (3), each of R7, R8, R9, and R10 is independently a hydrogen atom or an alkyl group containing from 1 to 14 carbons. The alkyl group may contain a hetero atom (typically selected from an oxygen atom and a sulfur atom), and a hydrogen atom in the alkyl group may be substituted with a substituent such as a halogen atom. For reasons of self-aggregation capacity, it is preferable that R7=R9, and it is preferable that R8=R10. From the viewpoint of solubility, R7 and R9 are preferably hydrogen atoms and each of R8 and R10 is independently an alkyl group containing from 1 to 14 carbons, or R8 and R10 are hydrogen atoms and each of R7 and R9 is independently an alkyl group containing from 1 to 14 carbons. More preferably, R8 and RIO are hydrogen atoms, and each of R7 and R9 is independently an alkyl group containing from 1 to 14 carbons. For reasons of self-aggregation capacity, the number of carbons of the alkyl group is preferably from 6 to 13, and more preferably from 8 to 10.
In the Formula (4), each of R11, R12, R13, and R14 is independently a hydrogen atom or an alkyl group containing from 1 to 14 carbons. The alkyl group may contain a hetero atom (typically selected from an oxygen atom and a sulfur atom), and a hydrogen atom in the alkyl group may be substituted with a substituent such as a halogen atom. For reasons of self-aggregation capacity, it is preferable that R11=R13, and it is preferable that R12=R14. From the viewpoint of solubility, R11 and R13 are preferably hydrogen atoms and each of R12 and R14 is independently an alkyl group containing from 1 to 14 carbons, or R12 and R14 are hydrogen atoms and each of R11 and R13 is independently an alkyl group containing from 1 to 14 carbons. More preferably, R12 and R14 are hydrogen atoms, and each of R11 and R13 is independently an alkyl group containing from 1 to 14 carbons. For reasons of self-aggregation capacity, the number of carbons of the alkyl group is preferably from 5 to 12, and more preferably from 8 to 10.
In the Formula (5), each of R15, R16, R17, and R18 is independently a hydrogen atom or an alkyl group containing from 1 to 14 carbons. The alkyl group may contain a hetero atom (typically selected from an oxygen atom and a sulfur atom), and a hydrogen atom in the alkyl group may be substituted with a substituent such as a halogen atom. For reasons of self-aggregation capacity, it is preferable that R15=R17, and it is preferable that R16=R18. From the viewpoint of solubility, R16 and R18 are preferably hydrogen atoms and each of R15 and R17 is independently an alkyl group containing from 1 to 14 carbons, or R15 and R17 are hydrogen atoms and each of R16 and R18 is independently an alkyl group containing from 1 to 14 carbons. More preferably, R16 and R18 are hydrogen atoms, and each of R15 and R17 is independently an alkyl group containing from 1 to 14 carbons. For reasons of self-aggregation capacity, the number of carbons of the alkyl group is preferably from 5 to 12, and more preferably from 8 to 10.
Still other examples of the organic semiconductor constituting the organic semiconductor single crystal layer are illustrated in the following Formulas (6) to (15). In the Formulas (6) to (15), linear alkyl, branched alkyl, cyclic alkyl, fluorinated linear and branched alkyl, triisopropylsilylethynyl, phenyl, and the like can be used as R.
Whether the organic semiconductor single crystal layer is a single crystal can be confirmed by observation with a transmission electron microscope (TEM).
The substrate used in the complementary semiconductor device of the present disclosure may be a substrate typically used in semiconductor process, a flexible substrate, or the like, and is preferably the flexible substrate. The flexible substrate is a film-like substrate, and is preferably a polyimide substrate, a polyphenylene sulfide substrate, or a silicone substrate. The thickness of the substrate is preferably from 0.001 mm to 1 mm, and more preferably from 0.002 mm to 0.1 mm. By using the flexible substrate, even in a state where the complementary semiconductor device of the present disclosure is strained to a strain ε of preferably 0.03% or greater, more preferably 0.04% or greater, and still more preferably 0.08% or greater, the complementary semiconductor device of the present disclosure can exhibit substantially the same characteristics as those in a state where there is no strain. The strain ε(%) is approximated by ε=hs/2R×100, where hs is the thickness of the substrate on which the complementary semiconductor device is disposed and R is a bend radius. For example, when a complementary semiconductor device having a thickness of 200 nm disposed on a polyimide substrate having a thickness of 10 μm is wound around a glass cylinder having a radius of 6 mm, the strain ε(%) is calculated as strain ε(%)=10 μm/(2×6 mm)×100.
A distance between the organic semiconductor single crystal layer and the AOS layer is 1 mm or less, preferably 0.8 mm or less, more preferably 0.5 mm or less, still more preferably 0.3 mm or less, even still more preferably 0.1 mm or less. The distance between the organic semiconductor single crystal layer and the AOS layer refers to the shortest distance between the organic semiconductor single crystal layer and the AOS layer. When the distance between the organic semiconductor single crystal layer and the AOS layer is within the above range, the complementary semiconductor device can operate at a high speed and the complementary semiconductor device can be highly integrated. When viewed from a direction perpendicular to a main surface of the p-type organic semiconductor single crystal layer, when at least a part of the p-type organic semiconductor single crystal layer overlaps the n-type amorphous oxide inorganic semiconductor layer, the distance between the organic semiconductor single crystal layer and the AOS layer corresponds to a thickness of an intermediate layer of the complementary semiconductor device as illustrated in
A protective layer is disposed between the AOS layer and the organic semiconductor single crystal layer. The protective layer may be or need not be adjacent to the AOS layer, but is preferably adjacent to the AOS layer. The protective layer may be or need not be adjacent to the organic semiconductor single crystal layer. The protective layer can protect the AOS layer from being affected by the manufacturing process of the complementary semiconductor device. The protective layer can also prevent components such as water, oxygen, or the like in the air atmosphere from reacting with the AOS layer. As a result, the deterioration of the AOS layer can be prevented and the long-term stability of the complementary semiconductor device can be improved. The protective layer may be disposed parallel to the main surface of the AOS layer, but in addition may also he disposed to protect an end surface of the AOS layer.
The thickness of the protective layer is preferably 1000 nm or less, more preferably 500 nm or less, still more preferably 250 nm or less, even still more preferably 100 nm or less, and even still more preferably 75 nm or less. The lower limit of the thickness of the protective layer is preferably 25 nm or greater. The thinner the thickness of the protective layer, the easier the protective layer having excellent surface flatness is formed, and deterioration in characteristics of the complementary semiconductor device can be suppressed. When the lower limit of the thickness of the protective layer is within the above range, a better barrier function can be obtained.
The protective layer preferably includes a first organic film and a second organic film, the first organic film is located on the n-type amorphous metal oxide inorganic semiconductor layer side, and the second organic film is located on the p-type organic semiconductor single crystal layer side, and the first organic film contains an organic solvent soluble polymer, and the second organic film is a vacuum deposited film.
The organic solvent soluble polymer means a polymer which is soluble in an organic solvent and examples thereof includes those that are polymers or oligomers when dissolved in the organic solvent. The organic solvent is a solvent which can dissolve the organic solvent soluble polymer but does not dissolve the AOS layer, and examples thereof include butyl acetate, toluene, xylene, and acetonitrile.
The first organic film composed of the organic solvent soluble polymer can be formed on the AOS layer by a mild method such as solution process without damaging the AOS layer. Since the solution process does not use vacuum or radical reaction, further formation of oxygen defects due to desorption of oxygen can be avoided, and there is an advantage of very low or no reactivity with the AOS layer. In the solution process, there is also no reaction in which acid is generated. Therefore, the first organic film can be formed directly on the AOS layer without substantially damaging the AOS layer. Since the second organic film which is a vacuum deposited film is formed on the first organic film, damage to the AOS layer due to vacuum process can be suppressed.
A chemical vapor deposition film (vacuum deposited film) such as parylene can be formed by a chemical vapor deposition (CVD) method which does not need heating of the substrate. However, since the AOS layer has extremely high environmental sensitivity, the AOS layer is easily damaged by a vacuum environment and generated radicals during formation of the vacuum deposited film.
On the other hand, when the first organic film containing the organic solvent soluble polymer is formed on the AOS layer by the solution process, the first organic film can be disposed without substantially damaging the AOS layer.
The first organic film can protect the AOS layer from the radicals generated during the formation of the vacuum deposited film and the vacuum environment. Therefore, the second organic film can be formed on the first organic film without substantially damaging the AOS layer. Since the first organic film has a low density, the first organic film has low gas barrier performance and allows oxygen to pass through the first organic film to some extent. The density of the first organic film is preferably from 0.4 g/cm3 to 1.3 g/cm3, more preferably from 0.5 g/cm3 to 1.2 g/cm3, still more preferably 0.6 g/cm3 to 1.1 g/cm3, and even still more preferably from 0.7 g/cm3 to 1.0 g/cm3. On the other hand, since the second organic film having a relatively high density is located on the first organic film, moisture and oxygen cannot substantially pass through the protective layer. The density of the first organic film is calculated from X-ray reflectivity measurement. By fitting the X-ray reflectivity data, the film thickness and the film density can be simultaneously estimated as fitting parameters.
Unlike the first organic film formed by the solution process, the second organic film which is the vacuum deposited film is formed by the dry process. Therefore, the second organic film is dense and has a high barrier effect. The density of the second organic film composed of the vacuum deposited film is higher than the density of the first organic film containing the organic solvent soluble polymer. The density of the second organic film is preferably from 1.0 g/cm3 to 1.5 g/cm3, and more preferably from 1.0 g/cm3 to 1.45 g/cm3. The density of the second organic film is measured by ASTM D1505 or ASTM E1461.
The protective layer may have any shape, and may be a protective film, a protective sheet, or the like.
The first organic film preferably has a thickness of 10 nm or greater, more preferably 13 nm or greater, and still more preferably 16 nm or greater. When the first organic film has the above-described preferable thickness, damage to the AOS layer due to the vacuum process and generated radicals during vacuum deposition of the second organic film can be further suppressed. The upper limit of the thickness of the first organic film is not particularly limited, and may be, for example, 1 mm or less. However, to avoid increasing the total thickness of the complementary semiconductor device, the thickness of the first organic film is preferably small, and may be preferably 1000 nm or less, more preferably 500 nm or less, and may be 100 nm or less, 50 nm or less, or 30 nm or less.
The second organic film preferably has a thickness from 100 nm to 300 nm, more preferably from 120 nm to 200 nm. When the second organic film which is the vacuum deposited film has the above-described preferable thickness, damage to the AOS layer due to the manufacturing process of the complementary semiconductor device and damage to the AOS layer due to exposure of the complementary semiconductor device to the atmosphere for a long period of time can be further suppressed. Although the vacuum deposited film is a relatively hard polymer film, when the upper limit of the thickness of the second organic film is in the above-described preferable range, the influence on flexibility when the complementary semiconductor device is formed on the flexible substrate can be reduced.
The organic solvent soluble polymer is preferably an acrylic polymer, a styrenic polymer, a fluorine-based polymer, a thermally crosslinkable polymer, or a combination thereof.
The acrylic polymer is preferably polymethyl methacrylate (PMMA), polyadamantyl methacrylate (PADMA), or polycyclohexyl methacrylate (PCMA).
The styrenic polymer is preferably polystyrene, poly-α-methylstyrene (PαMS), poly-4-methylstyrene (PMS), or polyvinylphenol (PVP).
The fluorine-based polymer is preferably CYTOP (registered trademark) or Teflon (registered trademark) AF.
The thermally crosslinkable polymer is preferably an epoxy resin or a thermally curable cycloolefin polymer.
The vacuum deposited film is preferably parylene. Parylene is sequentially formed at around room temperature, and thus is preferable in terms of high denseness and uniformity. Parylene also includes derivatives thereof.
The protective layer is not limited to the above-described configuration, and may be a protective layer (hereinafter referred to as a second protective layer) preferably including the first organic film and an inorganic oxide insulator film. In the second protective layer, the first organic film is located on the n-type amorphous metal oxide inorganic semiconductor layer side, and the inorganic oxide insulator film is located on the p-type organic semiconductor single crystal layer side. When the first organic film is present between the AOS layer and the inorganic oxide insulator film, damage to the AOS layer during the formation of the inorganic oxide insulator film can be suppressed.
The first organic film has the same configuration as that of the first organic film described above, and is preferably 50 nm or greater, more preferably 75 nm or greater, and still more preferably 100 nm or greater. When the first organic film has the above-described preferable thickness, damage to the AOS layer during formation of the inorganic oxide insulator film can be further suppressed.
When the inorganic oxide insulator film such as an AlOx layer is directly formed on the AOS layer by using an atomic layer deposition (ALD) method, the AOS is deteriorated because the ALD method is a process in which the substrate is heated under vacuum and which is mediated by water. When the inorganic oxide insulator film is directly formed on the AOS layer by using sputtering, the AOS is deteriorated because the sputtering is vacuum process.
The first organic film can protect the AOS layer from moisture associated with the ALD method or the vacuum environment of the sputtering process. Therefore, the inorganic oxide insulator film can be formed on the first organic film without substantially damaging the AOS laver. Since the first organic film has a low density, the first organic film has low gas barrier performance and allows oxygen to pass through the first organic film to some extent. On the other hand, since the inorganic oxide insulator film having a dense structure is located on the first organic film, moisture and oxygen cannot substantially pass through the second protective layer.
Preferably, the protective layer further includes the second organic film which is the vacuum deposited film located between the first organic film and the inorganic oxide insulator film. When the second organic film which is the vacuum deposited film is located between the first organic film and the inorganic oxide insulator film, damage to the AOS layer during formation of the inorganic oxide insulator film can be further suppressed. The AOS layer can be protected from attack of radical due to the CND process for forming the second organic film. When the second protective layer includes the second organic film, a preferable thickness of the first organic film may be thin, or may be 10 nm or greater.
The configuration of the second organic film has the same configuration of the second organic film described above, and a thickness of the second organic film in the second protective layer is preferably from 10 nm to 40 nm, and more preferably from 15 nm to 35 nm. Since the second organic film has a high density, the barrier effect can be obtained together with the inorganic oxide insulator even in the above-described preferable thickness range, and thus the total thickness of the second protective layer can be reduced.
In the second protective layer of a hybrid structure including the first organic film, the second organic film, and the inorganic oxide insulator film, the first organic film including the organic solvent soluble polymer and the second organic film which is the vacuum deposited film function as a buffer layer against damage due to the ALD process or the sputtering process during the formation of the inorganic oxide insulator film, and the inorganic oxide insulator film has a strong barrier effect.
The thickness of the inorganic oxide insulator film is preferably from 5 nm to 100 nm, more preferably from 15 nm to 75 nm, and still more preferably from 25 nm to 55 nm. Since the inorganic oxide insulator film has a further higher barrier effect than the second organic film composed of a polymer, the total thickness of the second protective layer can be reduced while exhibiting a good barrier effect in the above-described preferable thickness range. Since the inorganic oxide insulator film has the dense structure and is relatively hard, the thickness of the inorganic oxide insulator film is preferably 100 nm or less from the viewpoint of ensuring flexibility of the electronic element or electronic device including the second protective layer.
When the second protective layer includes the first organic film containing the organic solvent soluble polymer, the second organic film composed of the vacuum deposited film, and the inorganic oxide insulator film, the total thickness of the second protective layer is preferably 100 nm or less, more preferably 90 nm or less, and still more preferably 80 nm or less. When the second organic film composed of the vacuum deposited film is provided, the total thickness of the second protective layer can be reduced. The thickness of the second protective layer is preferably 25 nm or greater, and more preferably 40 nm or greater. When the thickness of the second protective layer is in the above-described preferable range, the thickness of the electronic element or electronic device provided with the second protective layer can be reduced while obtaining the good barrier function.
An inorganic oxide insulator of the inorganic oxide insulator film is preferably AlOx, HfOx, ZrOx, SiOx, TiOx, or a combination thereof. x may be a value satisfying the stoichiometric composition or may be a value not satisfying the stoichiometric composition. The inorganic oxide insulator film has a high density, and large molecules such as water molecules and oxygen in the air cannot pass through the inorganic oxide insulator film, and thus the inorganic oxide insulator film has a high barrier effect against moisture and gases.
The second protective layer preferably has a three layer hybrid structure of a PMMA layer as the first organic film, a parylene layer as the second organic film, and an AlOx layer as the inorganic oxide insulator film. The hybrid three layer protective layer of PMMA/parylene/AlOx can obtain strong protection without deteriorating the performance of the AOS layer.
A gate insulating film, a gate electrode, and source/drain electrodes (S/D electrodes) may be made of a typically used material.
The complementary semiconductor device of the present disclosure includes a p-type structure and an n-type structure. Examples of the complementary semiconductor device will be described below in which the organic semiconductor single crystal layer is disposed and the organic semiconductor single crystal layer and the AOS layer completely overlap each other when viewed from the direction perpendicular to the main surface of the organic semiconductor single crystal layer.
When the n-type transistor has a bottom-gate top-contact structure, the p-type structure/n-type structure of the complementary semiconductor device may have a bottom-gate top-contact/bottom-gate top-contact structure in
When the n-type transistor has a bottom-gate bottom-contact structure, the p-type structure/n-type structure of the complementary semiconductor device may have a bottom-gate top-contact/bottom-gate bottom-contact structure in
When the n-type transistor has a top-gate top-contact structure, the p-type structure/n-type structure of the complementary semiconductor device may have a bottom-gate top-contact/top-gate top-contact structure in
When the n-type transistor has a top-gate bottom-contact structure, the p-type structure/n-type structure of the complementary semiconductor device may have a bottom-gate top-contact/top-gate bottom-contact structure in
Examples of the complementary semiconductor device will be described below in which the organic semiconductor single crystal layer is disposed and the organic semiconductor single crystal layer do not overlap the AOS layer when viewed from the direction perpendicular to the main surface of the organic semiconductor single crystal layer.
When the n-type transistor has the bottom-gate top-contact structure, the n-type structure/p-type structure of the complementary semiconductor device may have a bottom-gate top-contact/bottom-gate top-contact structure in
When the n-type transistor has the bottom-gate bottom-contact structure, the n-type structure/p-type structure of the complementary semiconductor device may have a bottom-gate bottom-contact/bottom-gate top-contact structure in
When the n-type transistor has the top-gate top-contact structure, the n-type structure/p-type structure of the complementary semiconductor device may have a top-gate top-contact/bottom-gate top-contact structure in
When the n-type transistor has the top-gate bottom-contact structure, the n-type structure/p-type structure of the complementary semiconductor device may have a top-gate bottom-contact/bottom-gate top-contact structure in
As illustrated in
A method of the present disclosure is directed to a method for manufacturing an inorganic/organic hybrid complementary semiconductor device, the method including providing a substrate, forming an n-type structure on the substrate, forming a protective layer on the n-type structure, and forming a p-type structure on the protective layer, in which the forming the n-type structure includes preparing a precursor solution of an n-type amorphous metal oxide inorganic semiconductor containing a metal salt by using a sol-gel method, forming a precursor film by applying the precursor solution on the substrate, and forming an n-type amorphous metal oxide inorganic semiconductor layer by heat-treating the precursor film at 350° C. to 400° C., the forming the p-type structure includes forming a p-type organic semiconductor single crystal layer by using a coating method, when viewed from a direction perpendicular to a main surface of the p-type organic semiconductor single crystal layer, the p-type organic semiconductor single crystal layer is disposed and thus at least a part of the p-type organic semiconductor single crystal layer overlaps the n-type amorphous metal oxide inorganic semiconductor layer or the p-type organic semiconductor single crystal layer does not overlap the n-type amorphous metal oxide inorganic semiconductor layer, a distance between the p-type organic semiconductor single crystal layer and the n-type amorphous metal oxide inorganic semiconductor layer is 1 mm or less, and the n-type amorphous metal oxide inorganic semiconductor layer has a distribution of an oxygen defect amount in a thickness direction in which the oxygen defect amount is larger on the p-type organic semiconductor single crystal layer side than on the substrate side. The n-type structure and the p-type structure may have the above-exemplified configurations of the n-type structure and the p-type structure, respectively, described with reference to
In the method of the present disclosure, the solution process is used as film forming process of the amorphous metal oxide inorganic semiconductor layer (AOS layer) and the organic semiconductor single crystal layer. Since the AOS layer and the organic semiconductor single crystal layer can be formed under air atmosphere by using the solution process, a special apparatus such as a high vacuum chamber used in the dry process is not required, and the organic semiconductor device can be manufactured at a lower cost. In particular, in a case where a large area is to he achieved, increase in the size of the special apparatus such as the high vacuum chamber is not required, and the cost reduction effect is further increased as compared with the dry process.
As the film forming process of the AOS layer, first, as illustrated in
The precursor solution is then applied on the substrate to form a thin film of the precursor. An application method of the precursor solution is preferably a spin coating method, a bar coating method, a spray coating method, a dip coating method, an ink-jet method, a flexographic printing method, or a gravure printing method, more preferably the spin coating method, the bar coating method, the spray coating method, the dip coating method, or the ink-jet method, and still more preferably the spin coating method.
The spin coating method has advantages in terms of good reproducibility and high uniformity of an as-processed film in deposition of an active layer. The thin film formed by the spin coating method before the heat treatment contains a large amount of impurities such as nitrogen used in the preparation of the precursor solution and is completely different from the thin film obtained by the thy process. However, the impurities such as nitrogen are released as a gas by the heat treatment, and portions from which the impurities are released may be crosslinked by oxygen.
The soft bake for removing the solvent is preferably performed at 100° C. to 150° C. When the heat treatment is performed at the above-described preferable temperature, the solvent can be more favorably removed.
The hard bake for firing is performed at 350° C. to 400° C. When the heat treatment is performed at a low temperature of 400° C. or less, even when the flexible substrate is included, the amorphous metal oxide inorganic semiconductor layer can be formed without damaging the flexible substrate. When the heat treatment temperature is high, the formation of the M—O—M structure is facilitated, and thus the crystallinity is increased, a shallow donor concentration is increased, and the mobility is improved. However, when the temperature is too high, a negative voltage shift of an on-state voltage (VON) or a high off-current is generated, and power consumption tends to increase. Therefore, from this viewpoint, the heat treatment temperature is set to 400° C. or less. When the heat treatment temperature is less than 350° C., an organic residue is generated in the amorphous metal oxide inorganic semiconductor layer, and the organic residue functions as an electron trap, and thus the heat treatment temperature is set to 350° C. or higher.
The lower limit of the heat treatment temperature is preferably 355° C. or higher, more preferably 360° C. or higher, and still more preferably 365° C. or higher. The upper limit of the heat treatment temperature is preferably lower than 400° C., more preferably 395° C. or lower, still more preferably 390° C. or lower, even still more preferably 385° C. or lower, even still more preferably 380° C. or lower, and even still more preferably 375° C. or lower. When the heat treatment is performed in the above preferable temperature range, the power consumption and the organic residue can be further reduced.
The area of the AOS layer formed by the present method is preferably 2 mm2 or greater, more preferably 10 mm2 or greater, still more preferably 100 mm2 or greater, even still more preferably 1000 mm2 or greater, and even still more preferably 10000 mm2 or greater. The upper limit of the area of the AOS layer is not particularly limited, and is limited by a size of manufacturing equipment, and may be, for example, 10 m2. Since the AOS layer in the complementary semiconductor device of the present disclosure is formed by the solution process, the AOS layer can have a larger area as described above at a lower cost.
The AOS layer formed by the solution process is preferably patterned using a photoradical initiator and a sodium carbonate developer.
The AOS layer formed by the solution process is very sensitive to an external environment such as oxygen, water, and organic solvents. Photoacid generators and strong alkali developers such as tetramethylammoniwn hydroxide (TMAH) used in known photolithography process can damage the AOS layer. On the other hand, when patterning is performed by a photolithography method using a photoradical initiator and a sodium carbonate developer (1 mass % Na2CO3 solution) which is a solvent milder than the strong alkali developer, tine patterning can be performed without changing the characteristics of the AOS layer formed by the solution process.
As illustrated in
Preferably, the forming the protective layer includes preparing an organic solvent in which a polymer is dissolved, forming the first organic film on the n-type structure by applying the organic solvent in which the polymer is dissolved, and forming the second organic film that is the vacuum deposited film on the first organic film by using chemical vapor deposition method.
By mixing the organic solvent and the polymer, the organic solvent in which the polymer is dissolved can be prepared. The concentration of the polymer may be changed depending on the desired thickness of the first organic film, and is, for example, 1 mg/mL, to 80 mg/mL, 2 mg/mL to 70 mg/mL or 3 mg/mL to 60 mg/mL.
The organic solvent in which the polymer is dissolved is applied on the n-type structure to form the first organic film. An application method is preferably a spin coating method, a bar coating method, a spray coating method, a dip coating method, an ink-jet method, a flexographic printing method, or a gravure printing method, more preferably the spin coating method, the bar coating method, the spray coating method, the dip coating method, or the ink-jet method, and still more preferably the spin coating method.
The second organic film which is the vacuum deposited film is formed on the first organic film by using the chemical vapor deposition (CVD) method. The second organic film which is the vacuum deposited film is formed by CVD. CVD is gentle vacuum process and is preferable in terms of deposition rate, processing area, denseness, and uniformity.
The organic semiconductor single crystal layer may be formed directly on the gate insulating layer, the S/D electrodes, the protective layer, or a combination thereof by the coating method.
The coating method is a method in which an organic semiconductor is dissolved in an organic solvent to prepare an organic semiconductor solution, the organic semiconductor solution is applied on the substrate, and the organic solvent is evaporated to form a film. As the organic solvent, an organic solvent typically used in the coating method can be used, and for example, toluene and dichlorobenzene can be used.
The area of the organic semiconductor single crystal layer formed by the coating method is preferably 2 mm2 or greater, more preferably 10 mm2 or greater, still more preferably 100 mm2 or greater, even still more preferably 1000 mm2 or greater, and even still more preferably 10000 mm2 or greater. The upper limit of the area of the organic semiconductor single crystal layer is not particularly limited, and is limited by the size of the manufacturing equipment, and may be, for example, 10 m2. In the related art, when a vapor phase growth method is used, only an organic semiconductor single crystal film having an area of at most about the 1 mm2 is obtained, whereas the organic semiconductor single crystal layer in the present method can have the larger area as described above because it is formed by the solution process.
Preferably, the forming the p-type organic semiconductor single crystal layer includes forming a p-type organic semiconductor single crystal film on a first substrate having hydrophilic and water-insoluble properties by using the coating method, and applying water or an aqueous solution to an interface between the first substrate and the p-type organic semiconductor single crystal film to separate the p-type organic semiconductor single crystal film from the first substrate, and disposing a p-type organic semiconductor single crystal layer on a second substrate, and the second substrate is at least one of a gate insulating layer or S/D electrodes of the n-type structure, a protective layer, or a combination thereof.
The p-type organic semiconductor single crystal film to be separated from the first substrate is disposed on the gate insulating layer, the S/D electrodes, the protective layer, or a combination thereof to form the organic semiconductor single crystal layer. At least one of the gate insulating layer or the S/D electrodes of the n-type structure, the protective layer, or a combination thereof is referred to as the second substrate. The second substrate refers to those located on a surface in contact with the p-type organic semiconductor single crystal layer when the p-type organic semiconductor single crystal layer is disposed. According to this method for forming the organic semiconductor single crystal layer, the organic semiconductor single crystal layer having a thin film thickness can be easily disposed on the second substrate even if the second substrate has characteristics such as hydrophobicity, solvent solubility, non-heat resistance, or a combination thereof, and further includes a concave portion, a convex portion, or an uneven portion.
As the coating method, a typically used method can be used, and for example, an edge casting method, a continuous edge casting method, a drop casting method, a spin coating method, a printing method (an ink jet method or a gravure printing method), a dispenser method, a spray method, a dip coating method, a die coater method, a roll coater method, a bar coater method, a blade coating method, or the like can be used.
The first substrate is a hydrophilic substrate having a water contact angle of preferably 20 degrees or less, and more preferably 10 degrees or less. The first substrate is water-insoluble and may be, for example, mica or glass. Since the first substrate is water-insoluble, when water or an aqueous solution is applied to the interface between the first substrate and the organic semiconductor single crystal film, the components of the first substrate are not eluted and do not adhere to or react with the organic semiconductor single crystal film, and thus a high-purity organic semiconductor single crystal film can be obtained. In addition, when water or an aqueous solution is applied to the interface between the first substrate and the organic semiconductor single crystal film, the shape of the first substrate is maintained without being deformed, and thus the organic semiconductor single crystal film can be separated from the first substrate without distorting the shape of the organic semiconductor single crystal film. The term water-insoluble refers to not substantially dissolving, decomposing, or swelling in water or an aqueous solution. The glass has a surface which is preferably subjected to UV/ozone treatment or hydrophilization treatment with a hydrophilic coating material or the like.
Water or an aqueous solution is applied to the interface between the first substrate and the organic semiconductor single crystal film to separate the organic semiconductor single crystal film from the first substrate. Since the molecules of the organic semiconductor single crystal film applied on the first substrate are hydrophobic, water or an aqueous solution enters between the hydrophilic first substrate and the hydrophobic molecules of the organic semiconductor single crystal film, and thus the organic semiconductor single crystal film can be separated from the first substrate.
The contact angle of the hydrophilic first substrate with water or an aqueous solution is smaller than the contact angle of the hydrophobic organic semiconductor single crystal film with water or an aqueous solution, and the difference between the contact angles of the first substrate and the organic semiconductor single crystal film with water or an aqueous solution is preferably 80 degrees or more, and more preferably 90 degrees or more. The contact angle of the organic semiconductor single crystal film is preferably from 100 degrees to 120 degrees. When the difference between the contact angles of the hydrophilic first substrate and the hydrophobic organic semiconductor single crystal film is in the above preferable range, the organic semiconductor single crystal film can he more stably peeled off from the first substrate.
The method for applying water or an aqueous solution to the interface between the first substrate and the organic semiconductor single crystal film is not particularly limited, and may be a method for immersing the first substrate on which the organic semiconductor single crystal film is formed in water or an aqueous solution, a method for dropping water or an aqueous solution to the interface between the first substrate and the organic semiconductor single crystal film with a dropper, or the like.
The method for applying water or an aqueous solution to the interface between the first substrate and the organic semiconductor single crystal film preferably includes immersing the first substrate on which the organic semiconductor single crystal film is formed in water or an aqueous solution. By immersing the first substrate on which the organic semiconductor single crystal film is formed in water or an aqueous solution, the organic semiconductor single crystal film is separated from the first substrate in water or an aqueous solution, and the organic semiconductor single crystal film in a state of self-standing in water or an aqueous solution can be obtained. The self-standing organic semiconductor single crystal film can be disposed on the second substrate.
The disposing the organic semiconductor single crystal film on the second substrate preferably includes, applying water or an aqueous solution to the interface between the first substrate and the organic semiconductor single crystal film while disposing the second substrate to he in contact with the organic semiconductor single crystal film formed on the first substrate to separate the organic semiconductor single crystal film from the first substrate and to dispose the organic semiconductor single crystal film on the second substrate. As described above, by separating the organic semiconductor single crystal film from the first substrate while disposing the second substrate to be in contact with the organic semiconductor single crystal film, the organic semiconductor single crystal film can be transferred from the first substrate onto the second substrate.
Alternatively, the disposing the organic semiconductor single crystal film on the second substrate preferably includes immersing the first substrate on which the organic semiconductor single crystal film is formed in water or an aqueous solution, separating the organic semiconductor single crystal film from the first substrate in water or an aqueous solution to obtain the self-standing organic semiconductor single crystal film, and disposing the organic semiconductor single crystal film on the second substrate in water or an aqueous solution. As described above, by disposing the self-standing organic semiconductor single crystal film on the second substrate in water or an aqueous solution, the organic semiconductor single crystal film can be easily transferred from the first substrate to the second substrate.
More preferably, the disposing the organic semiconductor single crystal film on the second substrate includes, immersing the first substrate, the organic semiconductor single crystal film, and the second substrate in water or aqueous solution while disposing the second substrate so as to be in contact with the organic semiconductor single crystal film formed on the first substrate, and transferring the organic semiconductor single crystal film from the first substrate to the second substrate. As described above, by separating the organic semiconductor single crystal film from the first substrate while disposing the second substrate to be in contact with the organic semiconductor single crystal film in water or an aqueous solution, the organic semiconductor single crystal film can be further easily transferred from the first substrate onto the second substrate.
The patterning of the organic semiconductor single crystal film is not particularly limited and can be performed by a known method, but is preferably performed using a photoresist of a dry film. When the photoresist of the dry film is used, damage to the organic semiconductor single crystal film can he more suppressed than when a photoresist of an application type containing an organic solvent is used.
Preferably, the forming the p-type organic semiconductor single crystal layer includes forming a p-type organic semiconductor single crystal film on a third substrate having hydrophilic and water-insoluble properties by using the coating method, pressing the p-type organic semiconductor single crystal film against a convex portion of a stamp having the convex portion and a concave portion, applying water or an aqueous solution to an interface between the third substrate and the p-type organic semiconductor single crystal film to transfer the p-type organic semiconductor single crystal film to the convex portion, and pressing the p-type organic semiconductor single crystal film transferred to the convex portion against a fourth substrate to transfer the p-type organic semiconductor single crystal film to the fourth substrate to obtain a patterned p-type organic semiconductor single crystal layer, and the fourth substrate is at least one of a gate insulating layer or SID electrodes of the n-type structure, a protective layer, or a combination thereof.
At least one of the gate insulating layer or the S/D electrodes of the n-type structure, the protective layer, or a combination thereof is referred to as a fourth substrate. The fourth substrate refers to those located on a surface in contact with the p-type organic semiconductor single crystal layer when the p-type organic semiconductor single crystal layer is transferred from the convex portion of the stamp to be patterned.
According to this method, if a mold is fabricated in advance, photolithography is not required and the cost is low. Since the p-type organic semiconductor single crystal layer can be patterned simultaneously with the transfer to the stamp, the patterning can be performed in a short time Since the patterning of the p-type organic semiconductor single crystal layer is physically performed by utilizing the unevenness of the stamp, there is no need to use a solvent or a laser, and the patterning of various p-type organic semiconductor single crystal layers can be performed, and thus versatility is high. Since only the stamp is pressed against the fourth substrate, a solvent or the like does not damage the fourth substrate. For example, even when the fourth substrate is soluble in a solvent that dissolves an organic material, a patterned p-type organic semiconductor single crystal layer can be formed. Since the stamp is in contact with only water or an aqueous solution and does not need to be in contact with a solvent or to be heated, there is no swelling or shrinkage of the stamp due to the solvent or heat. For example, a film which has been applied in advance and has become a single crystal can be patterned.
In this method, a water-resistant p-type organic semiconductor single crystal thin is formed on the third substrate having hydrophilic and water-insoluble properties by using the coating method. The coating method is a method in which the organic material is dissolved in the organic solvent to prepare an organic solution, the organic solution is applied on the substrate, and the organic solvent is evaporated to form the film. As the organic solvent, an organic solvent typically used in the coating method can be used, and for example, toluene and dichlorobenzene can be used.
As the coating method, a typically used method can be used, and for example, an edge casting method, a continuous edge casting method, a drop casting method, a spin coating method, a printing method (an ink jet method or a gravure printing method), a dispenser method, a spray method, a dip coating method, a die coater method, a roll coater method, a bar coater method, a blade coating method, or the like can be used.
The third substrate is a hydrophilic substrate having a contact angle with water or an aqueous solution of preferably 20 degrees or less, and more preferably 10 degrees or less. The third substrate may be a substrate having a hydrophilic surface or a substrate having a surface subjected to a hydrophilization treatment, and is preferably a glass substrate or mica, more preferably the glass substrate. The glass substrate is preferably Eagle glass. The hydrophilization treatment can be performed by subjecting the glass substrate to a UV/O3 treatment.
The third substrate is water-insoluble and may be, for example, mica or glass. Since the third substrate is water-insoluble, when water or an aqueous solution is applied to the interface between the third substrate and the p-type organic semiconductor single crystal film, the components of the third substrate are not eluted and do not adhere to or react with the p-type organic semiconductor single crystal film, and thus a high-purity p-type organic semiconductor single crystal film can be obtained. In addition, when water or an aqueous solution is applied to the interface between the third substrate and the p-type organic semiconductor single crystal film, the shape of the third substrate is maintained without being deformed, and thus the organic film can he separated from the third substrate without distorting the shape of the p-type organic semiconductor single crystal film. The term water-insoluble refers to not substantially dissolving, decomposing, or swelling in water or an aqueous solution. The glass has a surface which is preferably subjected to UV/ozone treatment or hydrophilization treatment with a hydrophilic coating material or the like. The third substrate may be flexible.
Water or an aqueous solution is applied to the interface between the third substrate and the p-type organic semiconductor single crystal film to separate the p-type organic semiconductor single crystal film from the third substrate. The p-type organic semiconductor single crystal film may be a hydrophobic p-type organic semiconductor single crystal film. Water or an aqueous solution enters between the hydrophilic third substrate and molecules of the hydrophobic p-type organic semiconductor single crystal film, and thus the p-type organic semiconductor single crystal film can be separated from the third substrate.
The water contact angle of the hydrophilic third substrate is smaller than the water contact angle of the hydrophobic p-type organic semiconductor single crystal film, and the difference between the water contact angles of the third substrate and the p-type organic semiconductor single crystal film is preferably 80 degrees or more, and more preferably 90 degrees or more. The contact angle of the p-type organic semiconductor single crystal film is preferably from 100 degrees to 120 degrees. When the difference between the contact angles of the hydrophilic third substrate and the hydrophobic p-type organic semiconductor single crystal film is in the above preferable range, the p-type organic semiconductor single crystal film can be more stably peeled off from the third substrate.
The method for applying water or an aqueous solution to the interface between the third substrate and the p-type organic semiconductor single crystal film is not particularly limited, and may be a method for dropping water or an aqueous solution to the interface between the third substrate and the p-type organic semiconductor single crystal film with a water supplier such as a dropper or the like, a method for immersing the third substrate on which the p-type organic semiconductor single crystal film is formed in water or an aqueous solution, or the like.
The term hydrophobic means to possibly have a contact angle of preferably 80 degrees or greater, more preferably 90 degrees or greater, still more preferably 100 degrees or greater, even still more preferably 110 degrees or greater, and even still more preferably 150 degrees or greater.
A distance between the uppermost portion of the convex portion and the lowermost portion of the concave portion of the stamp is preferably from 2 μm to 100 μm, more preferably from 5 μm to 50 μm, still more preferably from 7 μm to 40 μm, and even still more preferably from 10 μm to 30 μm. When the distance between the uppermost portion of the convex portion and the lowermost portion of the concave portion of the stamp is in the above-described preferable range, physical patterning can be performed while preventing the concave portion from coming into contact with the p-type organic semiconductor single crystal film and preventing the convex portion from being broken when the stamp and the p-type organic semiconductor single crystal film are pressed against each other.
The pressing force for pressing the p-type organic semiconductor single crystal film against the convex portion of the stamp may be appropriately adjusted within a range in which the concave portion does not come into contact with the p-type organic semiconductor single crystal film and the convex portion is not broken, and may be, for example, from 5 kPa to 200 kPa, from 10 kPa to 100 kPa, or from 15 kPa to 50 kPa.
The constituent material of the stamp is preferably a resin, preferably polydimethylsiloxane (PDMS) or polymethyl methacrylate (PMMA), and more preferably PDMS. The constituent material of the stamp may be mainly composed of PDMS or PMMA. By using a stamp made of such a material, transferring the p-type organic semiconductor single crystal film to the convex portion of the stamp and transferring the p-type organic semiconductor single crystal film from the convex portion of the stamp to the fourth substrate can be favorably performed. The stamp may be hydrophobic. The stamp may include a support substrate of glass or a film.
The support substrate is preferably a glass substrate, a polyethylene naphthalate (PEN) substrate, or a polyethylene terephthalate (PET) substrate.
The glass substrate, the PEN substrate, or the PET substrate (depending on the heat treatment temperature during stamp fabrication) can be selected based on the ease of holding the stamp material before curing and being peeled off from the stamp fabrication mold after thermal curing. When a flexible substrate is used as a base material of the stamp, the peeling is facilitated.
A peeling layer may be formed on a surface of the stamp. The peeling layer is preferably CYTOP or a self-assembled monolayer (SAM), and more preferably CTYOP. The self-assembled monolayer is, for example, decyltrimethoxysilane (DTS), triethoxy-1H,1H,2H,2H-heptadecafluorodecylsilane (F-SAM), or trimethoxy(2-phenylethyl) silane (β-PTS). Since DTS has a contact angle of about 101 degrees, F-SAM has a contact angle of about 110 degrees, and β-PTS has a contact angle of about 80 degrees, when the p-type organic semiconductor single crystal film is transferred to the fourth substrate, the p-type organic semiconductor single crystal film can be more easily peeled off from the stamp to be transferred. The SAM treatment can be performed by a gas phase method or a liquid phase method.
The patterned p-type organic semiconductor single crystal layer preferably includes 10 or more single crystal films, each single crystal film has a thickness of 2 nm or greater, a width of 500 nm or greater, and a length of 500 nm or greater, and a spacing between adjacent single crystal films is 10 μm or greater.
The number of single crystal films included in the patterned p-type organic semiconductor single crystal layer is more preferably 50 or more, and still more preferably 100 or more. Each of the width and the length of the single crystal film may be more preferably 15 μm or greater, and still more preferably 45 μm or greater. The thickness of the single crystal film is more preferably from 2 nm to 100 nm and still more preferably from 7 nm to 20 nm. The spacing between adjacent single crystal films is more preferably 20 μm or greater, and still more preferably 25 μm or greater.
The upper limit of the width of the single crystal film is not particularly limited, and is, for example, 500 μm or less. The upper limit of the spacing between the single crystal films is not particularly limited.
The description described above with respect to the complementary semiconductor device is applied to the configurations of the organic semiconductor single crystal layer, the AOS layer, the protective layer, and the complementary semiconductor device formed in this method. The same applies to the configurations of the gate electrode, the gate insulating film, and the S/D electrodes.
The complementary semiconductor device illustrated in
A precursor solution of indium zinc oxide (IZO) was prepared by the sol-gel method schematically illustrated in
A polyimide vanish (YuPia (registered trademark)-ST, available from UBE Corporation) was spin coated on a 5 cm square glass supporter at 2000 rpm for 3 minutes, and then thermally cured on a hotplate under conditions of 110° C. for 60 minutes, 150° C. for 30 minutes, 200° C. for 10 minutes, 250° C. for 10 minutes, and 430° C. for 10 minutes under air atmosphere to form a polyimide substrate having a thickness of 10 μm.
By a lift-off method in which Cr/Au/Cr was vapor-deposited on a pattern formed of photoresist (TLOR, Tokyo Ohka Kogyo Co., Ltd.) and then the photoresist was removed, a gate electrode of Cr/Au/Cr having thicknesses of 5 nm/25 nm/5 nm, respectively, was formed on the polyimide substrate. An AlOx (alumina) gate insulating film having a thickness of 75 nm was formed on the entire surface of the polyimide substrate and the formed gate electrode by the atomic layer deposition (ALD) method.
The substrate on which the AlOx gate insulating film was formed was subjected to a treatment with a UV ozone cleaner (UV253H available from Filgen, Inc.) for 10 minutes to remove the organic residue and improve wettability.
As schematically illustrated in
On the same layer on the substrate including the patterned IZO active layer, the photosensitive dielectric (PDM, TAIYO INK MFG. CO., LTD.) was disposed and patterning is performed by photolithography, and A1 was thermally evaporated and lifted off using the patterned PDM as a shadow mask to form the S/D electrodes of the n-type transistor and a gate electrode of the p-type organic semiconductor, having a thickness of 60 nm. Next, a laminate body on which the S/D electrodes were formed was subjected to the heat treatment at 90° C. for 3 hours under air atmosphere, and gradually cooled to a room temperature.
The PMMA layer having a thickness of 13 nm and the parylene layer having a thickness of 200 nm were formed on the entire surfaces of the AlOx gate insulating film, the IZO layer, and the A1 electrode to serve as both the protective layer for the IZO layer and the gate insulating film for the p-type organic transistor to obtain an intermediate body of the complementary semiconductor device.
The PMMA layer was formed by spin coating a butyl acetate solution in which 0.56 mass % PMMA solution (Mw=120000) was dissolved at 500 rpm for 5 seconds and at 4000 rpm for 30 seconds, and then performing the heat treatment at 150° C. for 1 hour. Parylene was deposited by CVD vacuum deposition.
Formation of P-Type Organic Semiconductor Single Crystal Layer
An organic semiconductor single crystal layer of C9-DMBDT-NW which is a p-type semiconductor was formed on the protective layer of the p-type transistor portion by the continuous edge casting method. The continuous edge casting method was performed as follows.
A natural mica substrate was prepared as the hydrophilic substrate. A powder of the p-type organic semiconductor C9-DNBDT-NW of the following Formula (16) exhibiting high mobility:
was prepared as the organic semiconductor. By using 3-chlorothiophene as a solvent, 0.02 mass % organic semiconductor powder was dissolved in the solvent to prepare an organic semiconductor solution. The prepared organic semiconductor solution was applied on the mica substrate heated to 100° C. by the continuous edge casting method to form the organic semiconductor single crystal film having an average thickness of 12 nm and an area of 200 mm2. The water contact angle of the organic semiconductor single crystal film surface was 108 degrees.
The intermediate body of the complementary semiconductor device on which the protective layer was formed was disposed and the protective layer was in contact with the organic semiconductor single crystal film formed on the mica substrate, and water was dropped to the interface between the mica substrate and the organic semiconductor single crystal film to separate the organic semiconductor single crystal film from the mica substrate and transfer the organic semiconductor single crystal film onto the protective layer. The transferred organic semiconductor single crystal film was patterned by photolithography to form the organic semiconductor single crystal layer.
The patterning of the organic semiconductor single crystal film was performed as follows using a dry film resist (PDM available from TAIYO INK MFG. CO., LTD.) having a thickness of 5 μm as a photoresist.
Au having a thickness of 30 nm was deposited on the organic semiconductor single crystal film by the thermal evaporation, a PMMA solution (Mw=120000, 0.56 mass %, butyl acetate solution) was spin coated at 500 rpm for 5 seconds and at 1000 rpm for 30 seconds, and then heat treatment was performed at 80° C. for 10 minutes to form a PMMA film having a thickness of 300 nm, and laminate a dry film resist on the PMMA film.
The dry film resist was patterned by photolithography, and the PMMA film was removed by O2 plasma treatment using the patterned dry film resist as a mask. Then, an Au film was patterned by etching using Aurum S-50790 (available from Kanto Chemical Co., Inc.). Further, the organic semiconductor single crystal film was patterned by O2 plasma treatment. The PMMA film and dry film resist were then peeled off with acetonitrile which is a mild photoresist remover.
Au having a thickness of 60 nm was deposited by thermal evaporation on the entire surface of the intermediate body of the complementary semiconductor device fabricated by the above-described method. Next, in the same manner as described above, formation of the PMMA film, lamination of the dry film resist, patterning of the dry film resist by photolithography, removal of the PMMA film by O2 plasma, patterning of the Au film using the Aurum S-50790, and resist peeling off using acetonitrile were performed to form the S/D electrodes of Au having a length of 0.2 mm, a width of 1 mm, and a height of 90 nm (except for a wire portion). Next, a laminate body on which the S/D electrodes were formed was subjected to the heat treatment at 90° C. for 3 hours under air atmosphere, and gradually cooled to a room temperature. Thus, the complementary semiconductor device in which the p-type structure/n-type structure is the bottom-gate top-contact/bottom-gate top-contact structure illustrated in
In the same manner as in Example 1, complementary semiconductor devices having a channel width W of 200 μm and channel lengths L of 100 μm, 80 μm, 60 μm, 40 μm, 20 μm, 10 μm, 7 μm, and 5 μm, respectively, were fabricated. The channel lengths L of the p-type organic TFT and the n-type inorganic TFT were set to be the same.
In the same manner as in Example 1, an organic/inorganic hybrid complementary semiconductor device including the organic TFT having a W/L of 200 μm/9 μm and the inorganic TFT having the W/L of 200 μm/13 μm was fabricated, and characteristics thereof were evaluated.
The mobility of the p-type organic TFT was 5.1 cm2V−1s−1 and the mobility of the n-type inorganic. TFT was 4.0 cm2V−1s−1. An off-current and an on-off ratio of the p-type organic TFT were 10−11 A and 108, respectively, and an off-current and an on-off ratio of the n-type inorganic TFT were 10−12 A and 108, respectively. The threshold voltages of the p-type organic ITT and the n-type inorganic TFT were also substantially the same. As described above, it was confirmed that the p-type organic TFT and the n-type inorganic ITT included in the complementary semiconductor device of the present disclosure had a well-balanced operation and operated at a high speed.
Inverter characteristics of the organic-inorganic hybrid complementary semiconductor device single element obtained in Example 3 were evaluated.
A five stage ring oscillator (oscillation circuit) was fabricated in which five complementary semiconductor devices fabricated by the same method as in Example 1 were connected to each other in a loop.
where t is the delay time per stage of the ring oscillator and n is the number of stages of the ring oscillator. The ring oscillator operated to output a stationary waveform, and thus it was found that the characteristics of each p-type TFT, each n-type TFT, and each complementary semiconductor device have high uniformity. This is considered to be because each complementary semiconductor device includes the organic semiconductor single crystal film as the p-type semiconductor and the uniform AOS as the n-type semiconductor.
The ring oscillator characteristics of the complementary semiconductor device based on the organic semiconductor and the oxide semiconductor deposited by the previously reported solution process and heat treatment at 400° C. or less was compared from the perspective of scalable manufacturing and a flexible circuit. The results are shown in Table 1. The p-type semiconductors are all organic semiconductors. The n-type semiconductors are amorphous oxides in Example 1 and Comparative Example 2, and organic semiconductors in the others. Example 1 in Table 1 is the five stage ring oscillator in which five complementary semiconductor devices fabricated by the same method as in Example 1 were connected to each other in a loop. The delay time is proportional to VDD, and a converted delay time when VDD is aligned to 10 V to compare the ring oscillator characteristics of each example is denoted as t10 V. The p-type semiconductor and the n-type semiconductor are formed in the same layer by the ink-jet method in Comparative Examples 1, 2, and 4 to 6. by the continuous edge casting method in Comparative Example 3, and by the spin coating method in Comparative Example 7, and the protective layer is not used.
Comparative Example 1 was fabricated by the method reported in Takeda, Y et al. Appl. Sci. 2018, 8, 1331. Comparative Example 2 was fabricated by the method reported in K. Hong, et al. Adv. Mater. 2014, 26, 7032. Comparative Example 3 was fabricated by the method reported in M. Uno, et al. Adv. Electron. Mater. 2015, 1, 1500178. Comparative Example 4 was fabricated by the method reported in K. J. Baeg. et al. Org. Electron. 2013, 14, 1407. Comparative Example 5 was fabricated the method reported in S. H. Kim, et al, IEEE Electron Device Lett. 2013, 34, 307. Comparative Example 6 was fabricated by the method reported in W. Smaal, et al, Org. Electron. 2012, 13, 1686. Comparative Example 7 was fabricated by the method reported in L. Herlogsson, et al. Adv. Mater. 2011, 23, 4684.
It was found that the converted delay time t10 V of the ring oscillator fabricated in Example 1 in which five complementary semiconductor devices are connected to each other was much shorter than that of the ring oscillator of the complementary semiconductor device based on the organic semiconductor and the oxide semiconductor deposited by the previously reported solution process and heat treatment at 400° C. or less.
M refers to In or Zn. M—O—M refers to an oxide of a stoichiometric composition in which oxygen bridges between metal ions and there is no oxygen defect. M—O(H) refers to a composition having oxygen defects containing an oxygen or a hydroxyl group having an unpaired electron not bridging between metal ions. M—O—R refers to a composition having oxygen defects containing oxygen in an organic material such as H2O. CO2, or alcohol bonded to a metal ion.
The larger the inclination angle θ, the more the surface selective, and thus the composition closer to the surface of the AOS layer is represented. The ratio of the M—O—M bond was constant at about 50% in the inside of the AOS film, but the closer to the surface of the AOS film, the smaller the ratio of the M—O—M bond, and the ratio was decreased to about 40%, that is, the ratio of the M—O—M bond was decreased by about 20%. As described above, it was indicated that the AOS layer had more oxygen defects near the surface than in the inside and had a non-uniform chemical composition in the film thickness direction. In
A P-doped Si wafer substrate including thermally oxidized SiO2 (having a thickness of 100 nm) as a gate insulating film was ultrasonically cleaned in acetone and then in 2-propanol for 10 minutes each, and then dried at 100° C. for 10 minutes under air atmosphere by using a hotplate.
The cleaned and dried substrate was subjected to a treatment with a UV ozone cleaner (UV253H available from Filgen, Inc.) for 10 minutes to remove the organic residue and improve wettability.
IZO films (AOS layers) having different thicknesses were formed in the same manner as in Example 1 except that the precursor solution concentration was changed.
The source/drain (S/D) electrodes (Al, 40 nm) were formed and patterned on the IZO film by thermal evaporation using a metal mask. Further, the IZO film was patterned by an yttrium aluminum garnet (YAG) laser, subjected to a heat treatment at 90° C. for 3 hours under air atmosphere, and gradually cooled to a room temperature to obtain the IZO active layer.
Butyl acetate solution (50 mg/mL) in which PMMA (Mw: 120000) was dissolved was spin coated at 500 rpm for 5 seconds and at 4000 rpm for 30 seconds on the gate insulating layer on which the IZO active layer and the S/D electrodes were formed, and then subjected to heat treatment at 150° C. for 2 hours to form the PMMA layer having a thickness of 100 nm. AlOx having a thickness of 40 nm was deposited on the PMMA layer by the ALD method while the substrate temperature was maintained at 110° C. to form a protective layer including two layers of PMMA layer/AlOx layer. Thus, the bottom-gate top-contact n-type inorganic TFT including the protective layer and the IZO film was fabricated. The fabricated n-type inorganic TFT had the channel length (L) of 100 μm and the channel width (W) of 2000 μm.
TFT characteristics of IZO formed with the total metal ion concentrations of 0.05 M, 0.1 M, and 0.2 M, respectively, were evaluated.
When the AOS layer had a thickness of 2.5 nm, the off-current was good, but the mobility was relatively low and hysteresis was also observed. When the AOS layer had a thickness of 5.5 nm, the off-current and the mobility were good, and no hysteresis was observed. When the AOS layer had a thickness of 11 nm, the off-state was not obtained. When the total metal ion concentration was 0.1 M and the AOS layer had a thickness of 5.5 nm, the best TFT characteristics were obtained.
Characteristics of an oxide thin film (IZO) formed by the same method as in Reference Example 1 except that the heat treatment temperature was changed, and characteristics of an n-type TFT fabricated by the same method as in Reference Example 1 using the oxide thin film were evaluated.
The IZO thin films indicating an amorphous structure at respective sintering temperatures, having high uniformity, and having good characteristics were obtained. However, in the heat treatment at 350° C., an organic residue acting as an electron trap was observed. Therefore, the optimum temperature of the IZO system is considered to be 370° C.
10 Substrate
20 Gate electrode of n-type structure
22 Gate insulating film of n-type structure
24 n-type amorphous metal oxide inorganic semiconductor layer
26 S/D electrodes of n-type structure
30 Protective layer
40 Gate electrode of p-type structure
42 Gate insulating film of p-type structure
44 p-type organic semiconductor single crystal layer
46 S/D electrodes of p-type structure
| Number | Date | Country | Kind |
|---|---|---|---|
| 2021-029329 | Feb 2021 | JP | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/JP2022/007658 | 2/24/2022 | WO |
