Semiconductor device and method for manufacturing the same

Abstract

This semiconductor apparatus has a substrate film and a semiconductor film formed on the substrate film, wherein the substrate film comprises a polyimide obtained by condensation polymerization of an aromatic diamine and an aromatic tetracarboxylic acid anhydride and has a tensile elasticity in the longitudinal direction of 7 GPa or more, and the semiconductor film is polycrystalline and comprises crystal particles having an average particle size of 1 μm or more.

Description

[Technical Field]

[0001] The present invention relates to a semiconductor device and a method for manufacturing the semiconductor device. [Background technology]

[0002] Semiconductor films synthesized on insulators (SiO2, glass, plastic) are being actively researched as a key component for realizing three-dimensional integrated circuits (LSIs) and higher performance and lower costs for information terminals and solar cells.

[0003] Silicon is a typical semiconductor and is used in a wide variety of electronic devices. Ge and SiGe, which are also Group IV semiconductors like Si, have high affinity with the existing material, Si, and also have higher carrier mobility and a lower crystallization temperature than Si, making them promising next-generation semiconductor materials.

[0004] Patent Document 1 discloses a semiconductor device having a substrate and a semiconductor film formed on one surface of the substrate, the semiconductor film being a polycrystalline film made of crystalline grains with an average grain size of 1 μm or more (see, particularly, claim 1). Patent Document 1 also discloses a method for manufacturing the semiconductor device, comprising a first step of forming an amorphous semiconductor film on one surface of the substrate while heating the substrate, and a second step of heating the semiconductor film to promote solid-phase growth of the semiconductor film, in which the heating temperature in the first step is adjusted to be 50% or more but less than 100% of the temperature at which crystal nuclei are generated in the semiconductor film (see, particularly, claim 6). Patent Document 1 also discloses that the method for manufacturing the semiconductor device reduces the heating temperature required for solid-phase growth; for example, in the case of Ge, solid-phase growth can be achieved without high-temperature treatment of 500°C or higher, which would damage the substrate, and therefore allows the substrate to be widely made of materials such as LSI chips and low-heat-resistant glass and plastic (see, particularly, paragraph

[0030] ). [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 2018-142672 Summary of the Invention [Problem to be solved by the invention]

[0006] The present inventors have conducted extensive research into semiconductor devices having a semiconductor film made of a polycrystalline film consisting of crystal grains with an average grain size of 1 μm or more. As a result, the present inventors have discovered a new problem: when a plastic substrate is used, the semiconductor film may peel off from the substrate during manufacturing.

[0007] The present invention has been made in view of the above-mentioned problems, and its object is to provide a semiconductor device having a semiconductor film made of a polycrystalline film made of crystal grains with an average grain size of 1 μm or more, which can prevent the semiconductor film from peeling off from a substrate during manufacturing, even when the substrate is made of plastic, and also to provide a method for manufacturing a semiconductor device that can obtain such a semiconductor device. [Means for solving the problem]

[0008] The present inventors have conducted extensive research into semiconductor devices, and as a result have found that by employing the following configuration in a semiconductor device having a semiconductor film made of a polycrystalline film made of crystal grains with an average grain size of 1 μm or more, it is possible to provide a semiconductor device that can prevent the semiconductor film from peeling off from a substrate during manufacturing, even when the substrate is made of plastic, and have completed the present invention.

[0009] That is, the present invention provides the following. Base material Film and The aforementioned Base material A semiconductor film formed on the film and The aforementioned Base materialThe film is a polyimide film obtained by polycondensation of aromatic diamines and aromatic tetracarboxylic acid anhydrides, and has a tensile modulus of elasticity in the longitudinal direction of 7 GPa or more, The semiconductor device is characterized in that the semiconductor film is a polycrystalline film made of crystal grains with an average grain size of 1 μm or more.

[0010] According to the above configuration, Base material The film used has a longitudinal tensile modulus of 7 GPa or more. Because the longitudinal tensile modulus is 7 GPa or more, it can be said that there is little change in dimensions even when exposed to high temperatures. Base material The film used is obtained by polycondensation of aromatic diamines and aromatic tetracarboxylic acid anhydrides, and therefore has excellent heat resistance. Thus, according to the above configuration, a substrate film is used which has excellent heat resistance and undergoes little dimensional change even when exposed to high temperatures, and therefore, even if the semiconductor film is exposed to high temperatures during manufacturing, peeling off of the substrate film can be prevented.

[0011] In the above-described configuration, the base film preferably has a linear expansion coefficient of 5 ppm / °C or less.

[0012] When the linear expansion coefficient of the base film is 5 ppm / °C or less, the difference in the linear expansion coefficient between the base film and the semiconductor film can be kept small, and peeling between the semiconductor film and the base film can be easily prevented even when the base film is subjected to a heat application process.

[0013] The present invention also provides the following. Base material a film; Base material a semiconductor film formed on the film, Base material a method for manufacturing a semiconductor device, wherein the film is a polyimide film obtained by polycondensation of aromatic diamines and aromatic tetracarboxylic anhydrides, and has a tensile modulus of elasticity of 7 GPa or more in a longitudinal direction, and the semiconductor film is a polycrystalline film made of crystal grains having an average grain size of 1 μm or more; a first step of forming an amorphous semiconductor film on one surface of the substrate film while heating the substrate film; a second step of heating the semiconductor film to promote solid phase growth of the semiconductor film; and A method for manufacturing a semiconductor device, comprising adjusting the heating temperature in the first step to be 50% or more but less than 100% of the temperature at which crystal nuclei are generated in the semiconductor film.

[0014] According to the above configuration, Base material The film used has a longitudinal tensile modulus of 7 GPa or more. Because the longitudinal tensile modulus is 7 GPa or more, it can be said that there is little change in dimensions even when exposed to high temperatures. Base material The film used is obtained by polycondensation of aromatic diamines and aromatic tetracarboxylic acid anhydrides, and therefore has excellent heat resistance. Thus, according to the above configuration, a substrate film is used which has excellent heat resistance and undergoes little dimensional change even when exposed to high temperatures, and therefore, even if the semiconductor film is exposed to high temperatures during manufacturing, peeling off of the substrate film can be prevented.

[0015] In the above-mentioned configuration, it is preferable to adjust the heating temperature in the first step so that the density of the particles constituting the semiconductor film is 98% or more and less than 102% of the density of particles in a crystal of the same material.

[0016] By adjusting the heating temperature in the first step so that the density of the particles constituting the semiconductor film is 98% or more and less than 102% of the density of particles in a crystal of the same material, the temperature can be adjusted to be as high as possible within a range in which crystal nuclei do not form in the semiconductor film.

[0017] In the above-mentioned configuration, the heating temperature in the first step is preferably 100°C or higher and 150°C or lower.

[0018] If the heating temperature in the first step is set to 100° C. or more and 150° C. or less, it can be adjusted to be as high a temperature as possible within a range in which crystal nuclei do not form in the semiconductor film.

[0019] In the above-described configuration, the heating temperature in the second step is preferably 350°C or higher and 800°C or lower.

[0020] If the heating temperature in the second step is set to 350°C or higher and 800°C or lower, solid-phase growth of the amorphous semiconductor film formed in the first step can be promoted, and a polycrystalline semiconductor film (polycrystalline film) can be suitably synthesized.

[0021] In the above-mentioned configuration, the linear expansion coefficient of the base film is preferably 5 ppm / °C or less.

[0022] When the linear expansion coefficient of the base film is 5 ppm / °C or less, the difference in the linear expansion coefficient between the base film and the semiconductor film can be kept small, and peeling between the semiconductor film and the base film can be easily prevented even when the base film is subjected to a heat application process. [Effects of the Invention]

[0023] According to the present invention, it is possible to provide a semiconductor device having a semiconductor film made of a polycrystalline film made of crystal grains with an average grain size of 1 μm or more, which can prevent the semiconductor film from peeling off from a base film during manufacturing, even when the base film is made of plastic.Furthermore, it is possible to provide a semiconductor device manufacturing method capable of obtaining such a semiconductor device. [Brief explanation of the drawings]

[0024] [Figure 1] 1 is a schematic cross-sectional view of a semiconductor device according to an embodiment of the present invention; [Figure 2] 1A to 1C are diagrams illustrating a manufacturing process of the semiconductor device according to the present embodiment. [Figure 3] 1 shows the results of surface observation of the Ge thin film of Example 1 using a scanning electron microscope (SEM). [Figure 4]1 is a grain boundary map obtained by electron backscatter diffraction (EBSD) analysis of the Ge thin film of Example 1. [Figure 5] 5 is a graph showing the distribution of crystal grain sizes shown in FIG. 4. [Figure 6] 1 is a graph showing the relationship between hole mobility and film thickness of a Ge film in Example 1. DETAILED DESCRIPTION OF THE INVENTION

[0025] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings as appropriate. The drawings used in the following description may show characteristic portions enlarged for convenience in order to make the features of the present embodiment easier to understand, and the dimensional ratios of each component may differ from the actual ones. Furthermore, the materials, dimensions, etc. exemplified in the following description are merely examples, and the present invention is not limited thereto. Appropriate changes can be made within the scope of the effects of the present invention.

[0026] [Configuration of semiconductor device] 1 is a schematic cross-sectional view of a semiconductor device 100 according to one embodiment of the present invention. The semiconductor device 100 includes a base film 101 and a semiconductor film (semiconductor thin film) 102 formed (synthesized) on one surface 101a of the base film 101. The semiconductor device 100 is preferably a flexible semiconductor device (also referred to as a flexible semiconductor device). In this specification, a "flexible semiconductor device" refers to a semiconductor device that is visually inspected to show no damage such as cracks or chips after being wrapped and unwrapped 10 times around a rod made of ABS resin (acrylonitrile-butadiene-styrene copolymer resin) with a diameter of 5 mm.

[0027] The base film 101 has a longitudinal tensile modulus of elasticity of 7 GPa or more at 25°C, preferably 7.5 GPa or more, and more preferably 8 GPa or more. Since the longitudinal tensile modulus of the base film 101 is 7 GPa or more, it can be said that dimensional change is small even when exposed to high temperatures. Furthermore, the larger the longitudinal tensile modulus of the base film 101, the better, but from the viewpoint of flexibility, it is preferably 20 GPa or less, more preferably 15 GPa or less. The tensile modulus is measured according to the method described in the examples.

[0028] The tensile breaking strength of the base film 101 in the longitudinal direction at 25°C is preferably 100 MPa or more, more preferably 150 MPa or more, and even more preferably 200 MPa or more. There is no particular upper limit to the tensile breaking strength, but it is practically less than about 1000 MPa. When the tensile breaking strength is 100 MPa or more, no break occurs during handling, and handling is excellent. The tensile breaking strength of the base film 101 is measured by the method described in the examples.

[0029] The tensile breaking elongation of the base film 101 in the longitudinal direction at 25°C is preferably 5% or more, more preferably 10% or more, and even more preferably 15% or more. When the tensile breaking elongation is 5% or more, the handleability is excellent. There is no particular upper limit to the tensile breaking elongation, but it is practically less than about 80%. The tensile breaking elongation of the base film 101 is measured by the method described in the examples.

[0030] The coefficient of linear expansion (CTE) of the base film 101 in the longitudinal direction is preferably 5 ppm / °C or less. In this specification, the coefficient of linear expansion (CTE) of the base film 101 being 5 ppm / °C or less means that the average CTE (60°C) from 45°C to 75°C, the average CTE (300°C) from 285°C to 315°C, the average CTE (390°C) from 375°C to 405°C, and the average CTE (450°C) from 435°C to 465°C are all 5 ppm / °C or less. When the CTE is within the above range, the difference in the coefficient of linear expansion with the semiconductor film 102 can be kept small, and peeling between the semiconductor film 102 and the base film 101 can be easily prevented even when subjected to a heat application process. Here, CTE is a factor that represents reversible expansion and contraction with temperature. The CTE of the base film 101 is measured by the method described in the Examples.

[0031] The thickness of the base film 101 is not particularly limited, but is preferably 1 μm or more, more preferably 3 μm or more, from the viewpoint of ease of handling. Also, the thickness of the base film 101 is preferably 100 μm or less, more preferably 50 μm or less, from the viewpoint of flexibility.

[0032] The base film 101 is a polyimide film obtained by reacting aromatic diamines with aromatic tetracarboxylic acids, and is not particularly limited as long as it has a longitudinal tensile modulus of elasticity of 7 GPa or more. However, preferred examples include the combinations of the following aromatic diamines and aromatic tetracarboxylic acids (anhydrides). A. A combination of an aromatic tetracarboxylic acid having a pyromellitic acid residue and an aromatic diamine having a benzoxazole structure. B. A combination of an aromatic diamine having a diaminodiphenyl ether skeleton and an aromatic tetracarboxylic acid having a pyromellitic acid skeleton. C. A combination of an aromatic diamine having a phenylenediamine skeleton and an aromatic tetracarboxylic acid having a pyromellitic acid skeleton. D. A combination of one or more of the above ABCs. Among these, the combination A for producing a polyimide film having an aromatic diamine residue with a benzoxazole structure, in which the aromatic diamines include at least paraphenylenediamine and / or diaminodiphenyl ethers, is particularly preferred.

[0033] As aromatic diamines having a benzoxazole structure, from the viewpoint of ease of synthesis, each isomer of amino(aminophenyl)benzoxazole is preferred. Here, "each isomer" refers to each isomer determined depending on the coordination positions of the two amino groups possessed by amino(aminophenyl)benzoxazole. These diamines may be used alone or in combination of two or more. In this embodiment, it is preferable to use 70 mol % or more of the aromatic diamine having a benzoxazole structure.

[0034] In this embodiment, the polyimide film is not limited to the above and may use the following aromatic diamines, but is preferably a polyimide film using one or more of the following diamines not having a benzoxazole structure, as exemplified below, in combination, so long as the diamines account for less than 30 mol% of the total aromatic diamines: 4,4'-bis(3-aminophenoxy)biphenyl, bis[4-(3-aminophenoxy)phenyl]ketone, bis[4-(3-aminophenoxy)phenyl]sulfide, bis[4-(3-aminophenoxy)phenyl]sulfone, 2,2-bis[4-(3-aminophenoxy)phenyl]propane, 2,2-bis[4-(3-aminophenoxy)phenyl]-1,1,1,3,3,3-hexafluoropropane, m-phenylenediamine, o-phenylenediamine, p-phenylenediamine, m-aminobenzylamine, p-aminobenzylamine,

[0035] 3,3'-Diaminodiphenyl ether, 3,4'-diaminodiphenyl ether, 4,4'-diaminodiphenyl ether, 3,3'-diaminodiphenyl sulfide, 3,3'-diaminodiphenyl sulfoxide, 3,4'-diaminodiphenyl sulfoxide, 4,4'-diaminodiphenyl sulfoxide, 3,3'-diaminodiphenyl sulfone, 3,4'-diaminodiphenyl sulfone, 4,4'-diaminodiphenyl sulfone, 3,3'-diaminobenzophenone, 3,4'-diaminobenzophenone, 4,4'-diaminobenzophenone, 3,3'-diamino diaminodiphenylmethane, 3,4'-diaminodiphenylmethane, 4,4'-diaminodiphenylmethane, bis[4-(4-aminophenoxy)phenyl]methane, 1,1-bis[4-(4-aminophenoxy)phenyl]ethane, 1,2-bis[4-(4-aminophenoxy)phenyl]ethane, 1,1-bis[4-(4-aminophenoxy)phenyl]propane, 1,2-bis[4-(4-aminophenoxy)phenyl]propane, 1,3-bis[4-(4-aminophenoxy)phenyl]propane, 2,2-bis[4-(4-aminophenoxy)phenyl]propane,

[0036] 1,1-bis[4-(4-aminophenoxy)phenyl]butane, 1,3-bis[4-(4-aminophenoxy)phenyl]butane, 1,4-bis[4-(4-aminophenoxy)phenyl]butane, 2,2-bis[4-(4-aminophenoxy)phenyl]butane, 2,3-bis[4-(4-aminophenoxy)phenyl]butane, 2-[4-(4-aminophenoxy)phenyl]-2-[4-(4-aminophenoxy)-3-methylphenoxy] phenyl]propane, 2,2-bis[4-(4-aminophenoxy)-3-methylphenyl]propane, 2-[4-(4-aminophenoxy)phenyl]-2-[4-(4-aminophenoxy)-3,5-dimethylphenyl]propane, 2,2-bis[4-(4-aminophenoxy)-3,5-dimethylphenyl]propane, 2,2-bis[4-(4-aminophenoxy)phenyl]-1,1,1,3,3,3-hexafluoropropane,

[0037] 1,4-bis(3-aminophenoxy)benzene, 1,3-bis(3-aminophenoxy)benzene, 1,4-bis(4-aminophenoxy)benzene, 4,4'-bis(4-aminophenoxy)biphenyl, bis[4-(4-aminophenoxy)phenyl]ketone, bis[4-(4-aminophenoxy)phenyl]sulfide, bis[4-(4-aminophenoxy)phenyl]sulfoxide, bis[4-(4-aminophenoxy)phenyl]sulfone, bis[4-(3-aminophenoxy)phenyl]ether, bis [4-(4-aminophenoxy)phenyl]ether, 1,3-bis[4-(4-aminophenoxy)benzoyl]benzene, 1,3-bis[4-(3-aminophenoxy)benzoyl]benzene, 1,4-bis[4-(3-aminophenoxy)benzoyl]benzene, 4,4'-bis[(3-aminophenoxy)benzoyl]benzene, 1,1-bis[4-(3-aminophenoxy)phenyl]propane, 1,3-bis[4-(3-aminophenoxy)phenyl]propane, 3,4'-diaminodiphenyl sulfide,

[0038] 2,2-bis[3-(3-aminophenoxy)phenyl]-1,1,1,3,3,3-hexafluoropropane, bis[4-(3-aminophenoxy)phenyl]methane, 1,1-bis[4-(3-aminophenoxy)phenyl]ethane, 1,2-bis[4-(3-aminophenoxy)phenyl]ethane, bis[4-(3-aminophenoxy)phenyl]sulfoxide, 4,4'-bis[3-(4-aminophenoxy)benzoyl]diphenyl ether, 4,4'-bis[3-(3-aminophenoxy)benzoyl]diphenyl ether, 4,4'-bis[4-(4-amino-α,α-dimethylbenzyl)phenoxy]benzophenone, 4,4'-bis[4-(4-amino-α,α-dimethylbenzyl)phenoxy]diphenyl phenyl sulfone, bis[4-{4-(4-aminophenoxy)phenoxy}phenyl]sulfone, 1,4-bis[4-(4-aminophenoxy)phenoxy-α,α-dimethylbenzyl]benzene, 1,3-bis[4-(4-aminophenoxy)phenoxy-α,α-dimethylbenzyl]benzene, 1,3-bis[4-(4-amino-6-trifluoromethylphenoxy)-α,α-dimethylbenzyl]benzene, 1,3-bis[4-(4-amino-6-fluorophenoxy)-α,α-dimethylbenzyl]benzene, 1,3-bis[4-(4-amino-6-methylphenoxy)-α,α-dimethylbenzyl]benzene, 1,3-bis[4-(4-amino-6-cyanophenoxy)-α,α-dimethylbenzyl]benzene,

[0039] 3,3'-diamino-4,4'-diphenoxybenzophenone, 4,4'-diamino-5,5'-diphenoxybenzophenone, 3,4'-diamino-4,5'-diphenoxybenzophenone, 3,3'-diamino-4-phenoxybenzophenone, 4,4'-diamino-5-phenoxybenzophenone, 3,4'-diamino-4-phenoxybenzophenone, 3,4'-diamino-5'-phenoxybenzophenone, 3,3'-diamino-4,4'-dibiphenone 4,4'-diamino-5,5'-dibiphenoxybenzophenone, 3,4'-diamino-4,5'-dibiphenoxybenzophenone, 3,3'-diamino-4-biphenoxybenzophenone, 4,4'-diamino-5-biphenoxybenzophenone, 3,4'-diamino-4-biphenoxybenzophenone, 3,4'-diamino-5'-biphenoxybenzophenone, 1,3-bis(3-amino-4-phenoxybenzoyl)benzene, 1,4 1,3-bis(4-amino-5-phenoxybenzoyl)benzene, 1,4-bis(4-amino-5-phenoxybenzoyl)benzene, 1,3-bis(3-amino-4-biphenoxybenzoyl)benzene, 1,4-bis(3-amino-4-biphenoxybenzoyl)benzene, 1,3-bis(4-amino-5-biphenoxybenzoyl)benzene, 1,4-bis(4-amino-5-biphenoxybenzoyl)benzene, 2,6-bis[4-(4-amino-α,α-dimethylbenzyl)phenoxy]benzonitrile, and aromatic diamines in which some or all of the hydrogen atoms on the aromatic ring of the above aromatic diamines have been substituted with halogen atoms, alkyl or alkoxy groups having 1 to 3 carbon atoms, cyano groups, or halogenated alkyl or alkoxy groups having 1 to 3 carbon atoms in which some or all of the hydrogen atoms of the alkyl or alkoxy groups have been substituted with halogen atoms.

[0040] The aromatic tetracarboxylic acids used in this embodiment are, for example, aromatic tetracarboxylic acid anhydrides. Specific examples of aromatic tetracarboxylic acid anhydrides include the following. Among these, pyromellitic acid is preferably used, and it is preferable to use 70 mol % or more of the total aromatic tetracarboxylic acids.

[0041] These tetracarboxylic acid dianhydrides may be used alone or in combination of two or more. In this embodiment, non-aromatic tetracarboxylic acid dianhydrides such as those exemplified below may be used alone or in combination of two or more, as long as they account for less than 30 mol% of the total tetracarboxylic acid dianhydrides. Examples of such tetracarboxylic acid dianhydrides include butane-1,2,3,4-tetracarboxylic acid dianhydride, pentane-1,2,4,5-tetracarboxylic acid dianhydride, cyclobutane tetracarboxylic acid dianhydride, cyclopentane-1,2,3,4-tetracarboxylic acid dianhydride, cyclohexane-1,2,4,5-tetracarboxylic acid dianhydride, cyclohex-1-ene-2,3,5,6-tetracarboxylic acid dianhydride, 3-ethylcyclohex-1-ene-3-(1,2),5,6-tetracarboxylic acid dianhydride, 1-methyl-3-ene-4-(2-methyl-1-phenyl-2-phenyl ... 1-ethylcyclohexane-3-(1,2),5,6-tetracarboxylic dianhydride, 1-methyl-3-ethylcyclohex-1-ene-3-(1,2),5,6-tetracarboxylic dianhydride, 1-ethylcyclohexane-1-(1,2),3,4-tetracarboxylic dianhydride, 1-propylcyclohexane-1-(2,3),3,4-tetracarboxylic dianhydride, 1,3-dipropylcyclohexane-1-(2,3),3-(2,3)-tetracarboxylic dianhydride, dicyclohexyl-3,4,3',4'-tetracarboxylic dianhydride.

[0042] Examples of the tetracarboxylic acid dianhydride include bicyclo[2.2.1]heptane-2,3,5,6-tetracarboxylic acid dianhydride, 1-propylcyclohexane-1-(2,3),3,4-tetracarboxylic acid dianhydride, 1,3-dipropylcyclohexane-1-(2,3),3-(2,3)-tetracarboxylic acid dianhydride, dicyclohexyl-3,4,3',4'-tetracarboxylic acid dianhydride, bicyclo[2.2.1]heptane-2,3,5,6-tetracarboxylic acid dianhydride, bicyclo[2.2.2]octane-2,3,5,6-tetracarboxylic acid dianhydride, and bicyclo[2.2.2]oct-7-ene-2,3,5,6-tetracarboxylic acid dianhydride. These tetracarboxylic acid dianhydrides may be used alone or in combination of two or more.

[0043] The solvent used when the aromatic diamines and aromatic tetracarboxylic acids (anhydrides) are reacted (polycondensed) to obtain polyamic acids is not particularly limited as long as it dissolves both the raw material monomers and the resulting polyamic acids. However, polar organic solvents are preferred, such as N-methyl-2-pyrrolidone, N-acetyl-2-pyrrolidone, N,N-dimethylformamide, N,N-diethylformamide, N,N-dimethylacetamide, dimethyl sulfoxide, hexamethylphosphoric amide, ethyl cellosolve acetate, diethylene glycol dimethyl ether, sulfolane, and halogenated phenols. These solvents can be used alone or in combination. The amount of solvent used should be sufficient to dissolve the raw material monomers. Specific examples of the amount of solvent used include an amount in which the weight of the monomer in the solution containing the dissolved monomers is typically 5 to 40% by weight, preferably 10 to 30% by weight.

[0044] The polymerization conditions for obtaining polyamic acid may be conventionally known conditions. Specific examples include continuous stirring and / or mixing in an organic solvent at a temperature ranging from 0 to 80°C for 10 minutes to 30 hours. The polymerization reaction may be divided into sections or the temperature may be adjusted as necessary. While there is no particular restriction on the order of addition of the two monomers, it is preferable to add the aromatic tetracarboxylic acid anhydride to the aromatic diamine solution. The mass of the polyamic acid in the polyamic acid solution obtained by the polymerization reaction is preferably 5 to 40% by mass, more preferably 10 to 30% by mass. The viscosity of the solution, measured at 25°C using a Brookfield viscometer, is preferably 10 to 2000 Pa·s, more preferably 100 to 1000 Pa·s, from the viewpoint of stability in liquid delivery. The reduced viscosity (ηsp / C) of the polyamic acid in this embodiment is not particularly limited, but is preferably 3.0 dl / g or higher, more preferably 4.0 dl / g or higher. Vacuum degassing during the polymerization reaction is effective for producing a high-quality organic solvent solution of polyamic acid. Furthermore, a small amount of end-capping agent may be added to the aromatic diamines before the polymerization reaction to control the polymerization. Examples of end-capping agents include compounds having a carbon-carbon double bond, such as maleic anhydride. When maleic anhydride is used, the amount used is preferably 0.001 to 1.0 mol per 1 mol of the aromatic diamines.

[0045] The resulting polyamic acid solution is cast onto an endless support, and a self-supporting polyimide precursor film (hereinafter also referred to as a green film) in which complete imidization has not progressed is obtained by drying or desolvation, and this film is then wound up or subsequently subjected to a treatment such as high temperature to promote imidization, thereby forming a polyimide film. As an imidization method using high-temperature treatment, any of the conventionally known imidization reactions can be used as appropriate. Examples include a method in which a polyamic acid solution containing no ring-closing catalyst or dehydrating agent is subjected to a heat treatment to promote the imidization reaction (the so-called thermal ring-closing method), and a chemical ring-closing method in which a ring-closing catalyst and a dehydrating agent are added to a polyamic acid solution and the imidization reaction is carried out by the action of the ring-closing catalyst and the dehydrating agent.

[0046] In the chemical ring-closure method, the polyamic acid solution is partially imidized to form a self-supporting precursor composite, and then the imidization is completed by heating. In this case, the conditions for partially imidizing the polyamic acid solution are preferably 100-200°C for 3-20 minutes, while the conditions for completely imidizing the polyamic acid solution are preferably 200-400°C for 3-20 minutes. The timing of adding the ring-closure catalyst to the polyamic acid solution is not particularly limited; it may be added before the polymerization reaction to obtain the polyamic acid. Specific examples of ring-closure catalysts include aliphatic tertiary amines such as trimethylamine and triethylamine, and heterocyclic tertiary amines such as isoquinoline, pyridine, and beta-picoline. Among these, at least one amine selected from heterocyclic tertiary amines is preferred. The amount of ring-closure catalyst used per mole of polyamic acid is not particularly limited, but is preferably 0.5-8 moles. The timing of adding the dehydrating agent to the polyamic acid solution is not particularly limited, and it may be added in advance before the polymerization reaction to obtain the polyamic acid. Specific examples of dehydrating agents include aliphatic carboxylic acid anhydrides such as acetic anhydride, propionic anhydride, and butyric anhydride, and aromatic carboxylic acid anhydrides such as benzoic anhydride. Among these, acetic anhydride, benzoic anhydride, or a mixture thereof is preferred. The amount of dehydrating agent used per mole of polyamic acid is not particularly limited, but is preferably 0.1 to 4 moles. When using a dehydrating agent, a gelation retarder such as acetylacetone may be used in combination.

[0047] Specific imidization methods include the imidization reaction and imidization treatment described above. High-temperature imidization treatment is preferably performed at a maximum temperature of 460°C or higher but lower than 500°C for a period of 3 minutes to 30 minutes. The thickness of the polyimide film or polyimidebenzoxazole film is not particularly limited, but considering its use as a substrate film for a film-type solar cell, it is typically 3 to 200 μm, preferably 10 to 150 μm. This thickness can be easily controlled by the amount of polyamic acid solution applied to the support and the concentration of the polyamic acid solution. The polyimide film of this embodiment is typically an unstretched film, but may be stretched uniaxially or biaxially. Here, an unstretched film refers to a film obtained without intentionally applying mechanical external force in the planar expansion direction of the film by tenter stretching, roll stretching, inflation stretching, or the like.

[0048] The semiconductor film 102 is a polycrystalline film made of large crystal grains of any material that can be formed into a thin film, such as Ge, SiGe, Si, GeSn, SiC, GaAs, InP, GaN, ZnSe, CdS, ZnO, etc. The average grain size of the crystal grains should be 1 μm or more, preferably 5 μm to 30 μm, and more preferably about 30 μm.

[0049] The thickness of the semiconductor film 102 is preferably 50 nm or more, and more preferably 50 nm or more and 5000 nm or less.

[0050] [Method of manufacturing semiconductor device] Two main steps for manufacturing the semiconductor device 100 will be described with reference to FIG.

[0051] (first step) While the substrate film 101 is heated, particles 102A of Ge, SiGe, Si, GeSn, SiC, GaAs, InP, GaN, ZnSe, CdS, ZnO, etc. are deposited on one surface 101 of the substrate film to form an amorphous semiconductor film 102B (left side of Figure 2).

[0052] The heating method and deposition method are not particularly limited, and general methods (molecular beam deposition, CVD, sputtering, etc.) can be used. When using molecular beam deposition, molecular beams of particles 102A are generated in a high vacuum and irradiated onto one surface 101a of the substrate film during heating, depositing particles 102A to form amorphous film 102B. This method has the advantage that the film formation temperature can be set low.

[0053] The heating temperature in the first step is adjusted so that the amorphous film 102B to be formed has a particle number density as close as possible to that of a crystal, and no crystal nuclei are generated. In other words, the temperature is adjusted to be as high as possible within a range in which crystal nuclei are not generated in the semiconductor film 102B. The heating temperature in the first step is preferably adjusted so that the density of the particles constituting the semiconductor film is 98% or more but less than 102% of the particle density in a crystal of the same material.

[0054] Specifically, the temperature should be adjusted to 30% to less than 100% of the temperature at which crystal nuclei are generated in the semiconductor film 102B, and more preferably 50% to less than 100%. More specifically, the temperature is generally 100°C to 700°C. This temperature is adjusted depending on the material and thickness of the semiconductor film 102 to be formed. For example, when forming a 100-nm-thick semiconductor film 102 made of Ge, the temperature should be 100 to 150°C. When forming a 100-nm-thick semiconductor film 102 made of SiGe or Si, the temperature should be 100 to 650°C and 500 to 650°C, respectively.

[0055] (Second process) Heat treatment (atmosphere does not matter) is performed to promote solid-phase growth of the amorphous semiconductor film 102B formed in the first step, and synthesize a polycrystalline semiconductor film (polycrystalline film) 102C (right side of FIG. 2). In the second step, the heating temperature is preferably 350°C or higher and 800°C or lower, and the heating time is preferably 0.1 hour or higher and 300 hours or lower.

[0056] By adjusting the heating temperature in the first step as described above, the semiconductor film 102C formed becomes a polycrystalline film made up of large grains of 1 μm or more.

[0057] The semiconductor device 100 obtained through the first and second steps has a polycrystalline semiconductor film 102C obtained by forming an amorphous film 102B with a density close to that of a crystal to the extent that no crystal nuclei are generated during the manufacturing process, and then solid-phase growing this amorphous film. This semiconductor film 102C is a polycrystalline film made of large crystal grains of 1 μm or more, so when the semiconductor device 100 is operated as a device, it can achieve a higher carrier mobility than conventional devices. For example, in a semiconductor film made of Ge and having a thickness of 100 nm, the hole mobility can be increased to 290 cm 2 / V·s. In a 300 nm thick semiconductor film made of Ge, the hole mobility can be improved to 320 cm 2 / V·s.

[0058] If the grain size of the crystals constituting the semiconductor film 102 is smaller than 1 μm, the scattering of carriers due to the grain boundaries becomes significant, and it is not possible to obtain a mobility equivalent to that of this embodiment.

[0059] where: Base material The film 101 is a film obtained by polycondensation of aromatic diamines and aromatic tetracarboxylic acid anhydrides, and has a tensile modulus of elasticity in the longitudinal direction of 7 GPa or more. Base material Since the tensile modulus of elasticity in the longitudinal direction of the film 101 is 7 GPa or more, it can be said that the dimensional change is small even when exposed to high temperatures. Base material The film 101 is excellent in heat resistance because it is a film obtained by polycondensation of aromatic diamines and aromatic tetracarboxylic acid anhydrides. As described above, in this embodiment, a base film 101 is used that has excellent heat resistance and undergoes little dimensional change even when exposed to high temperatures, and therefore, even if exposed to high temperatures during manufacturing (first process, second process, etc.), peeling of the semiconductor film 102C from the base film 101 can be prevented.

[0060] As described above, the semiconductor device 100 according to this embodiment has a semiconductor film 102C obtained by forming an amorphous film 102B with a density close to that of a crystal to the extent that no crystal nuclei are generated during the manufacturing process, and then solid-phase growing this amorphous film 102B. This semiconductor film 102C is a polycrystalline film made of large crystal grains with a diameter of 1 μm or more, and therefore can achieve higher carrier mobility than conventional semiconductor films. Furthermore, the base film 101 is a film obtained by polycondensation of aromatic diamines and aromatic tetracarboxylic acid anhydrides, and has a longitudinal tensile modulus of elasticity of 7 GPa or more. Therefore, even if the base film 101 is exposed to high temperatures during manufacturing (first step, second step, etc.), peeling of the semiconductor film 102C from the base film 101 can be prevented.

[0061] In the semiconductor film 102C of this embodiment, the heating temperature required for solid phase growth is reduced. For example, in the case of Ge, it can be formed without performing high-temperature treatment of 500° C. or higher, which would damage the base film 101.

[0062] The semiconductor device and the method for manufacturing the semiconductor device according to this embodiment can be widely used in the development of high-speed, lightweight, and flexible portable information terminals, the development of three-dimensional, multi-functional LSIs, the development of multi-junction solar cells that are both highly efficient and low cost, etc. [Example]

[0063] The present invention will be described below with reference to examples, but the present invention is not limited to these. The physical properties in the following examples were evaluated using the following methods.

[0064] 1. Polyimide film thickness The thickness of the film was measured using a micrometer (Militron 1254D, manufactured by Fineruf Co., Ltd.).

[0065] 2. Polyimide film tensile strength, tensile elongation, and tensile modulus (25°C) The dried film was cut into strips of 100 mm in length and 10 mm in width in the longitudinal direction (MD) to prepare test pieces. After seasoning in an environment of 25°C and 60% RH for 24 hours, the tensile strength, tensile elongation at break, and tensile modulus were measured in the same environment using a tensile tester (Shimadzu Autograph (product name), model name AG-5000A) at a tension speed of 50 mm / min and a chuck distance of 40 mm.

[0066] 3. Coefficient of linear expansion (CTE) of polyimide film The dimensional change rate in the MD direction of the polyimide film being measured was measured under the following conditions. The dimensional change rate / temperature was measured at 15°C intervals of 30°C to 45°C, 45°C to 60°C, etc. This measurement was continued up to 465°C, and the average of the measurements from 45°C to 75°C was calculated as CTE(60°C), the average of the measurements from 285°C to 315°C was CTE(300°C), the average of the measurements from 375°C to 405°C was CTE(390°C), and the average of the measurements from 435°C to 465°C was calculated as CTE(450°C). Device name: MAC Science TMA4000S Sample length: 20 mm Sample width: 2 mm Heating start temperature: 25℃ Heating end temperature: 480℃ Heating rate: 5℃ / min Atmosphere: Argon

[0067] <Preparation of Polyimide Film A> An autoclave was charged with 3,600 parts by mass of parachlorophenol, and then 93 parts by mass of diaminodiphenyl ether (ODA) and 294 parts by mass of 3,3',4,4'-biphenyltetracarboxylic dianhydride (BPDA) were added and mixed with stirring. The atmosphere in the autoclave was then purged with nitrogen gas, and 45 parts by mass of paraphenylenediamine (PDA) was quickly added. The reaction was carried out in a sealed state at 180°C for 12 hours to obtain a dope in which the imidization reaction had been completed. The resulting dope was cooled to 80°C, filtered, and then passed through a deaerator. It was then coated onto a stainless steel endless belt using a die coater and dried at 150-160°C to form a self-supporting film. After peeling it from the endless belt, both ends of the self-supporting film were pinned and passed through a pin tenter continuously in the width direction at a fixed length. The film was heated at 200°C for 5 minutes, 300°C for 5 minutes, 400°C for 5 minutes, and 450°C for 5 minutes, with a heating profile that increased the temperature sequentially. Finally, both ends of the film were peeled from the pins, and the pinned portions were slit to remove the film, yielding a brown polyimide film A with a width of 500 mm, length of 450 m, and thickness of 38 μm. The properties of polyimide film A are shown in Table 1.

[0068] <Preparation of Polyimide Film B> An autoclave was charged with 3,000 parts by weight of N-methylpyrrolidone, 186 parts by weight of diaminodiphenyl ether (ODA), and 218 parts by weight of pyromellitic dianhydride (PMDA). The autoclave was then purged with nitrogen gas, and the mixture was allowed to react in a sealed state at 60°C for 12 hours. The mixture was then cooled to 25°C to obtain a polyamic acid solution. The resulting polyamic acid solution was filtered, passed through a defoamer, and applied to the smooth surface of a 750 mm wide, 188 μm thick polyester film (Cosmoshine A-4100 manufactured by Toyobo Co., Ltd.) using a die coater. The solution was then dried at 110°C to 125°C to form a dry coating on the polyester film, which was then wound up together with the polyester film to obtain a roll. The roll was then placed on the unwinding section of a pin tenter with an unwinding section and a winding section. The dried coating was unwound together with the polyester film, and the dried coating was continuously peeled off from the polyester film to form a self-supporting film. Both ends of the self-supporting film were pinned, and the film was passed through the pin tenter continuously in the width direction at a fixed length, heating it according to a temperature profile that sequentially increased the temperature to 200°C for 5 minutes, 300°C for 5 minutes, and 400°C for 10 minutes. After cooling, both ends of the film were finally peeled off from the pins, and the pinned portions were slit to remove the film. A brown polyimide film B with a width of 500 mm, a length of 320 m, and a thickness of 25 μm was obtained. The properties of polyimide film B are shown in Table 1.

[0069] <Preparation of Polyimide Film C> An autoclave was charged with 4,000 parts by weight of N,N-dimethylacetamide and 225 parts by weight of 5-amino-2-(p-aminophenyl)benzoxazole (DAMBO), which were stirred to dissolve. Then, 218 parts by weight of pyromellitic dianhydride (PMDA) was added and stirred for 48 hours at a reaction temperature of 25°C, yielding a pale yellow, viscous polyamic acid solution. The resulting polyamic acid solution was filtered, passed through a defoamer, and applied to the smooth surface of a 750 mm wide, 188 μm thick polyester film (Cosmoshine A-4100, manufactured by Toyobo Co., Ltd.) using a die coater. The solution was dried at 110°C to 120°C to form a dry coating on the polyester film, which was then wound up together with the polyester film to obtain a roll. The roll was then placed on the unwinding section of a pin tenter with an unwinding section and a winding section. The dried coating was unwound together with the polyester film, and the dried coating was continuously peeled off from the polyester film to form a self-supporting film. Both ends of the self-supporting film were pinned, and the film was passed through the pin tenter continuously at a fixed length across the width using a temperature profile of 200°C for 3 minutes, 225°C for 3 minutes, and 475°C for 6 minutes. After cooling, both ends of the film were finally peeled off from the pins, and the pinned portions were slit to remove the film. This yielded a brown polyimide film C measuring 500 mm wide, 320 m long, and 18 μm thick. The properties of Polyimide Film C are shown in Table 1.

[0070] [Table 1]

[0071] Example 1 (Preparation of germanium thin film 1) Using molecular beam deposition, germanium (Ge) particles were deposited on the polyimide film C obtained above at a substrate temperature of 125°C to form a 100 nm thick Ge thin film (first step). The film formation rate was 1 nm / min.

[0072] The sample that had undergone the first step was then placed in an electric furnace with a nitrogen atmosphere, and the Ge thin film formed in the first step was heat-treated at 450°C for 5 hours to promote solid-phase growth (second step).

[0073] The surface of the 100 nm thick Ge thin film obtained through the second process was observed using a scanning electron microscope (SEM), and the results are shown in Figure 3. Only the contrast of the crystals was observed in the SEM image, and no peeling or cracks in the Ge thin film were observed.

[0074] The grain size of the constituent grains of the 100 nm thick polycrystalline Ge film obtained through the second process was evaluated using the electron backscatter diffraction (EBSD) method.

[0075] Figure 4 shows the grain boundary map obtained from EBSD analysis, and Figure 5 shows the distribution of grain size. It can be seen that the polycrystalline Ge film is composed of grains of 1 μm or larger. The average grain size was calculated to be 5.6 μm.

[0076] The electrical properties of the polycrystalline Ge film obtained through the second step were evaluated using the van der Pauw method.

[0077] Figure 6 is a graph showing the relationship between the hole mobility of a polycrystalline Ge film and its film thickness. It shows that the hole mobility is comparable to that of a polycrystalline Ge film formed on a quartz glass substrate by the same process. When the Ge film thickness is 100 nm or more, a high hole mobility (300 cm 2 / V·s) is obtained.

[0078] <Example 2> (Preparation of germanium thin film 2) The same procedure as in Example 1 was carried out, except that in the first step, the thickness of the thin film of germanium (Ge) particles was changed to 50 nm. The surface of the 50 nm thick Ge thin film obtained through the second step was observed using a scanning electron microscope (SEM). Only crystalline contrast was observed in the SEM image, and no peeling or cracks in the Ge thin film were observed.

[0079] Example 3 (Preparation of germanium thin film 3) The same procedure as in Example 1 was carried out, except that in the first step, the thickness of the thin film of germanium (Ge) particles was changed to 300 nm. The surface of the 300 nm thick Ge thin film obtained through the second step was observed using a scanning electron microscope (SEM). Only crystalline contrast was observed in the SEM image, and no peeling or cracks in the Ge thin film were observed.

[0080] (Comparative Example 1) Using polyimide film A, a germanium thin film was prepared in the same manner as in Example 1. As in Example 1, germanium (Ge) particles were deposited to form (vapor-deposit) a Ge thin film with a thickness of 100 nm (first step) with the substrate temperature Td set in the range of 50°C to 200°C. The film formation rate was 1 nm / min, the same as in Example 1, and the film formation time was also 100 minutes. In the second step, the samples were placed in a nitrogen-filled electric furnace and heat-treated at 375°C for 140 hours, 400°C for 60 hours, and 450°C for 5 hours to promote solid-phase growth. However, significant warping, presumably due to substrate shrinkage, occurred in all samples, and the germanium thin film peeled off from the substrate film in the samples heat-treated at 400°C and 450°C. Therefore, grain size and mobility measurements of the germanium thin film could not be performed.

[0081] (Comparative Example 2) Using Polyimide Film B, a germanium thin film was prepared in the same manner as in Example 1. As in Example 1, germanium (Ge) particles were deposited to form (vapor-deposit) a Ge thin film with a thickness of 100 nm (first step) with the substrate temperature Td set in the range of 50°C to 200°C. The film formation rate was 1 nm / min, the same as in Example 1, and the film formation time was also 100 minutes. Next, in the second step, the substrate was placed in an electric furnace with a nitrogen atmosphere, and the Ge thin film formed in the first step was subjected to heat treatment at 375°C for 140 hours, 400°C for 60 hours, and 450°C for 5 hours in order to promote solid-phase growth. As a result, in the case of heat treatment at 375°C for 140 hours, crystal growth was confirmed and the hole mobility was 150 cm 2 / V·s. Further observations were made on samples heat-treated at 400°C and 450°C in the hope of improving the properties, but wrinkles that were thought to be due to thermal shrinkage of the film had appeared in the sample heat-treated at 400°C, making it impossible to measure mobility. Furthermore, the film substrate of the sample heat-treated at 450°C had deteriorated so severely that it had become very brittle, making it difficult to pick up with tweezers when removing it from the electric furnace, and evaluation of this sample had to be abandoned as well. [Explanation of symbols]

[0082] 100 Semiconductor device 101 Base film 101a One side of the substrate 102, 102A particles 102B, 102C Semiconductor film

Claims

1. A base film; a semiconductor film formed on the substrate film; and the substrate film is a polyimide film obtained by polycondensation of aromatic diamines and aromatic tetracarboxylic acid anhydrides, The aromatic diamines include aromatic diamines having a benzoxazole structure, The tensile modulus in the longitudinal direction is 7 GPa or more, the linear expansion coefficient of the base film is 5 ppm / °C or less in all of CTE(60°C), which is an average value from 45°C to 75°C, CTE(300°C), which is an average value from 285°C to 315°C, CTE(390°C), which is an average value from 375°C to 405°C, and CTE(450°C), which is an average value from 435°C to 465°C; The semiconductor device is characterized in that the semiconductor film is a polycrystalline film made of crystal grains having an average grain size of 1 μm or more.

2. 2. The semiconductor device according to claim 1, wherein the linear expansion coefficient of the base film is 2.5 ppm / °C or less in all of CTE(60°C), which is an average value from 45°C to 75°C, CTE(300°C), which is an average value from 285°C to 315°C, CTE(390°C), which is an average value from 375°C to 405°C, and CTE(450°C), which is an average value from 435°C to 465°C.

3. A method for manufacturing a semiconductor device, comprising: a base film; and a semiconductor film formed on the base film, wherein the base film is a polyimide film obtained by polycondensation of aromatic diamines and aromatic tetracarboxylic anhydrides, and has a longitudinal tensile modulus of elasticity of 7 GPa or more, and the base film has a linear expansion coefficient of 5 ppm / °C or less in all of CTE(60°C) which is an average value from 45°C to 75°C, CTE(300°C) which is an average value from 285°C to 315°C, CTE(390°C) which is an average value from 375°C to 405°C, and CTE(450°C) which is an average value from 435°C to 465°C, and the semiconductor film is a polycrystalline film made of crystal grains having an average grain size of 1 μm or more, a first step of forming an amorphous semiconductor film on one surface of the substrate film while heating the substrate film; a second step of heating the semiconductor film to promote solid phase growth of the semiconductor film; and A method for manufacturing a semiconductor device, comprising adjusting the heating temperature in the first step to be 50% or more but less than 100% of the temperature at which crystal nuclei are generated in the semiconductor film.

4. 4. The method for manufacturing a semiconductor device according to claim 3, wherein the heating temperature in the first step is adjusted so that the density of particles constituting the semiconductor film is 98% or more but less than 102% of the density of particles in a crystal of the same material.

5. 5. The method for manufacturing a semiconductor device according to claim 3, wherein the heating temperature in the first step is set to 100[deg.] C. or higher and 150[deg.] C. or lower.

6. 5. The method for manufacturing a semiconductor device according to claim 3, wherein the heating temperature in the second step is set to 350° C. or higher and 800° C. or lower.

7. 5. The method for manufacturing a semiconductor device according to claim 3, wherein the linear expansion coefficient of the base film is 2.5 ppm / °C or less in all of CTE(60°C), which is an average value from 45°C to 75°C, CTE(300°C), which is an average value from 285°C to 315°C, CTE(390°C), which is an average value from 375°C to 405°C, and CTE(450°C), which is an average value from 435°C to 465°C.

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