JP2010109352A - Method of manufacturing semiconductor substrate and the semiconductor substrate obtained by the method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of efficiently manufacturing a semiconductor substrate that is formed of a semiconductor layer reduced in thickness with density, smoothness, and high performance by baking a printed layer, which is provided on a base material and contains semiconductor nanoparticles, at low temperature in a short time. <P>SOLUTION: The method of manufacturing the semiconductor substrate includes the steps of: forming the printed layer on the base material by printing a pattern of a coating solution containing the semiconductor nanoparticles; and forming the patterned semiconductor layer by baking the printed layer. The printed layer is baked by exposure to surface wave plasma generated by applying microwave energy. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a method for manufacturing a semiconductor substrate, a semiconductor substrate obtained by the method, and an electronic member including the semiconductor substrate. More specifically, the present invention relates to a semiconductor substrate formed by baking a printed layer containing semiconductor nanoparticles provided on a base material at a low temperature in a short time to form a dense, smooth semiconductor layer having excellent performance. The present invention relates to a method for efficiently manufacturing a semiconductor substrate, a semiconductor substrate obtained by the method, and an electronic member including the semiconductor substrate.

Thin film transistors (TFTs) are used as image drive elements in flat panel displays such as liquid crystal displays and organic EL displays.
Conventionally, as a thin film used for a TFT, a semiconductor thin film such as amorphous silicon or polysilicon has been formed by a chemical vapor deposition method (CVD) or a vacuum film forming method such as sputtering. These methods require expensive equipment and require a photolithography technique for patterning, which requires many steps and is complicated. In addition, it is not easy to cope with an increase in area with these techniques, and expensive manufacturing costs are required.

  In contrast, organic semiconductors have attracted attention as semiconductors that can be formed by coating. Since an organic semiconductor can be formed by coating, it can be formed at a low cost and at a low temperature, and can be applied to a flexible display or the like. However, since organic semiconductors generally have low mobility and are unstable in the atmosphere, they have not been put into practical use.

By the way, Non-Patent Document 1 presents a field effect transistor having a conductive channel made of a lead selenium (PbSe) semiconductor nanocrystal using a liquid phase process as a solution-based process of an inorganic semiconductor. . Nanocrystals are insulative, and an example in which this material is formed into a pattern and then reduced with hydrazine is presented.
However, since hydrazine is explosive and dangerous, and PbSe is toxic, there is a problem in putting it to practical use.

Patent Document 1 proposes a method of manufacturing a thin film semiconductor using nanoparticles, including a step of forming a nanoparticle film on a substrate and performing a heat treatment. The step of forming a nanoparticle film includes a step of dispersing nanoparticles in a solvent and preparing a nanoparticle liquid, a step of mixing a precipitant in the nanoparticle liquid, and a nanoparticle liquid containing the precipitant. And a step of vapor deposition on the substrate. Nanoparticles include HgTe, HgSe, HgS, CdTe, CdSe, CdS, ZnTe, ZnSe, ZnS, PbTe, PbSe, PbS, and ZnO.
The method for depositing the nanoparticle liquid containing the precipitating agent on the substrate is one of a spin coating method, a dip coating method, a stamp method, a spray method, a Langmuir-Blodgett method, and a printing method. It is disclosed that it can be used. Furthermore, the example which heat-processes a nanoparticle film | membrane at 100 to 185 degreeC for 10 to 200 minutes and obtains a semiconductor layer is disclosed.
However, the method described in Patent Document 1 has low semiconductor characteristics and further has a relatively long heating time of 10 to 200 minutes, so that the productivity is low and is not a practical method.

Patent Document 2 proposes a thin film forming method for forming a thin film by applying nanoparticles to a substrate and subjecting the nanoparticles applied on the substrate to atmospheric pressure plasma processing as a thin film forming method. ing. Under a pressure of atmospheric pressure or near atmospheric pressure, a gas is supplied between opposing electrodes and a high-frequency electric field is generated between the electrodes to make the gas an excitation gas. It is a thin film formation method using the atmospheric pressure plasma treatment to expose. A thin film forming method in which the nanoparticle is a metal atom-containing compound, and the metal atom of the metal atom-containing compound is at least one selected from the group consisting of In, Ga, Al, Sn, Ge, Sb, Bi, and Zn. It is disclosed.
However, the specific method for forming a thin film described in Patent Document 2 is to apply a thin film to a substrate by spray coating or spin coating, and form the thin film by an atmospheric pressure plasma method. Description of pattern printing In addition, the nanoparticles are examples relating to Sn / In composite nanoparticles, and the obtained thin film only describes a Sn / In transparent conductive film.

  Under such circumstances, the present inventors have developed a semiconductor substrate in which a semiconductor layer having a practically sufficient mobility is formed on a base material using Ge nanoparticles with high productivity. As a manufacturing method, a printing layer including patterned Ge nanoparticles formed on a substrate is heated at 600 ° C. or higher in a reducing atmosphere, or a hydrogen radical is generated. A method for firing using a process was found and a patent was filed (Japanese Patent Application No. 2008-92533).

  By the way, when a coating layer is formed by printing a coating solution containing semiconductor nanoparticles on a base material, and this is fired to form a semiconductor layer, if the firing temperature is high or the firing time is long, this firing A heat-resistant base material that can withstand the treatment is required, resulting in a problem that the degree of freedom of selection of the base material is reduced. In addition, if the firing time is long or the nanoparticle printing layer is fired nonuniformly, the nanoparticles are formed by abnormal grain growth or nonuniform grain growth in the surface. There is a problem that the density of the layer is lowered or the surface is uneven. When such a semiconductor layer is used for, for example, a TFT, carrier mobility is reduced or sufficient performance is obtained due to insufficient contact with the source electrode and drain electrode in contact with the semiconductor layer. The problem of not. Therefore, the baking treatment is preferably performed at a temperature as low as possible for a short time, and the formed semiconductor layer preferably has no particle growth, is dense, and has a smooth surface.

  Moreover, when obtaining a semiconductor layer with the coating liquid containing a semiconductor nanoparticle, it is desirable that the thickness is 10-200 nm normally which is the minimum layer thickness which can maintain a semiconductor characteristic. If the thickness of the semiconductor layer is larger than this, an unsintered portion remains in the layer, particularly in the vicinity of the interface with the base material, after that, and this portion becomes a source of impurities and carriers. Therefore, the semiconductor performance may be deteriorated. On the other hand, it is possible to reduce the concentration by reducing the concentration of semiconductor nanoparticles in the coating solution. However, since the concentration of semiconductor nanoparticles is low, the nanoparticles are difficult to sinter on the base material after the baking treatment, and are dense. Sometimes it is difficult to layer. Therefore, producing a thin semiconductor layer having a layer thickness of 10 to 200 nm by applying a thin coating while maintaining a concentration of semiconductor nanoparticles capable of producing a dense layer is a conventional coating solution containing semiconductor nanoparticles. Then it might be difficult.

JP 2007-273949 A JP 2007-182605 A Science, 310, p86

  Under such circumstances, the present invention bakes a printed layer containing semiconductor nanoparticles provided on a base material at a low temperature for a short time to obtain a dense, smooth, excellent performance, and even thinner semiconductor layer. It is an object of the present invention to provide a method for efficiently producing a formed semiconductor substrate, a semiconductor substrate obtained by the method, and an electronic member provided with the semiconductor substrate.

As a result of intensive studies to achieve the above object, the inventors of the present invention have developed a surface-wave plasma generated by applying microwave energy to a patterned printing layer containing semiconductor nanoparticles provided on a substrate. It has been found that the object can be achieved by subjecting to a baking treatment. The present invention has been completed based on such findings.
That is, the present invention
(1) A method of manufacturing a semiconductor substrate in which a coating layer containing semiconductor nanoparticles is printed on a base material in a pattern to form a printed layer, and then the printed layer is baked to form a patterned semiconductor layer. A method for manufacturing a semiconductor substrate, wherein the printed layer is subjected to a firing process by exposing the printed layer to surface wave plasma generated by application of microwave energy,
(2) A semiconductor substrate obtained by the manufacturing method as described in (1) above, and (3) an electronic member comprising the semiconductor substrate as described in (2) above,
Is to provide.

  According to the method for producing a semiconductor substrate of the present invention, a patterned printed layer containing semiconductor nanoparticles provided on a substrate is exposed to surface wave plasma generated by application of microwave energy, thereby reducing the temperature and the temperature. A semiconductor substrate that can be fired in time, dense, smooth, excellent in performance, and formed with a thinner semiconductor layer can be efficiently manufactured.

2 is a scanning electron microscope (SEM) photograph in which the surface of the semiconductor substrate manufactured in Example 1 is observed. 4 is a scanning electron microscope (SEM) photograph in which the surface of the semiconductor substrate manufactured in Reference Example 1 is observed. 4 is a scanning electron microscope (SEM) photograph in which a cross section of a semiconductor substrate manufactured in Example 2 is observed.

First, the manufacturing method of the semiconductor substrate of this invention is demonstrated.
[Method for Manufacturing Semiconductor Substrate]
In the method for producing a semiconductor substrate of the present invention, a coating layer containing semiconductor nanoparticles is printed in a pattern on a substrate to form a printed layer, and then the printed layer is baked to form a patterned semiconductor layer. A method of manufacturing a semiconductor substrate to be formed, wherein the printed layer is subjected to a baking treatment by exposing the printed layer to surface wave plasma generated by application of microwave energy.
In addition, as an aspect which forms a printing layer on a base material here, when forming a printing layer directly on a base material, and when having a primer layer, other functional layers, an electrode, etc. on a base material, Any of the cases where a printed layer is formed on them is included.

(Base material)
The base material used in the production method of the present invention is not particularly limited as long as it is used for a semiconductor substrate. For example, silicon wafer; soda lime glass, alkali-free glass, borosilicate glass, quartz glass, etc. A glass substrate; inorganic materials such as a ceramic substrate such as alumina, and various plastics such as a film, a sheet, or a plate can be used, but a film form is preferable from the viewpoint of thinning.
Examples of the plastic that can be used as the film substrate include those having a melting point of 200 ° C. or higher in consideration of heat resistance in the baking treatment, such as polyimide, polyethylene naphthalate (PEN), polyethylene terephthalate (PET), Examples thereof include polyphenylene sulfide, polyether ether ketone, polyether sulfone, polycarbonate, polyamide imide, polyether imide, epoxy resin, glass-epoxy resin, polyphenylene ether, and liquid crystalline polymer compound.
In addition, an easily adhesive component may be formed on the surface of the base material, and when a plastic base material is used, the surface may be subjected to a surface treatment such as an oxidation method or an unevenness method.

Examples of easy adhesion component film formation include, for example, a method of forming a metal thin film such as Ni, Cr, Ti, Co, Mo, Ta, or a metal oxide thereof, a thermoplastic resin, a thermosetting resin, and a photocurable resin. A method of applying an adhesive component made of a resin or the like, or a method of applying an organic-inorganic coupling agent can be employed.
Examples of the oxidation method for the plastic substrate include corona discharge treatment, plasma treatment, chromic acid treatment (wet), flame treatment, hot air treatment, ozone / ultraviolet irradiation treatment, and the like. Examples of the uneven method include a sand blast method and a solvent treatment method. These surface treatment methods are appropriately selected according to the type of the base film, but in general, the plasma treatment method is preferably used from the viewpoints of effects and less contamination by impurities.

Although there is no restriction | limiting in particular about the thickness of a base material, When a base material is an inorganic material, it is about 0.1-10 mm normally, Preferably it is 0.5-3 mm.
On the other hand, in the case of a plastic substrate, it is usually in the range of 10 to 300 μm. When the thickness is 10 μm or more, deformation of the base material is suppressed when forming the semiconductor layer, which is preferable in terms of shape stability of the formed semiconductor layer. Moreover, when it is 300 micrometers or less, when winding-up processing is performed continuously, it is suitable at the point of a softness | flexibility.

Moreover, an electrode, an insulating layer, etc. can be previously formed in the base material according to the use of the semiconductor substrate. In addition, when such a functional layer, an electrode, etc. are provided in a base material, a printing layer is formed on this functional layer, an electrode, etc.
Examples of the electrodes include metals such as Au, Ag, Cu, Ni, Al, Pt, Cr, Fe, Sn, Pd, Mo, Mn, In, Co, Pb, Si, Ir, and Zn, tin-doped indium oxide, and oxidation. Examples thereof include metal oxides such as tin, zinc oxide, and titanium oxide, carbon materials, and conductive polymers. Examples of the insulating layer include Si, Al, Ta, Ti, Sn, V, Y, W, Cr, Materials such as oxides and nitrides of metals such as Ni and Mn, composite metal oxides such as barium titanate, and insulating polymers are used. In addition, an antioxidant layer, a gas barrier layer, a diffusion prevention layer, and the like can be provided in accordance with the application.

(Semiconductor nanoparticles)
There is no restriction | limiting in particular about the semiconductor substance which comprises the semiconductor nanoparticle used in the manufacturing method of this invention, It can select suitably from a conventionally well-known semiconductor substance. As this semiconductor substance, for example, Group 14 elements of the periodic table such as silicon (Si) and germanium (Ge), III-V compounds such as GaAs and InP, some II-VI compounds such as ZnTe, and the like can be used.
In addition, as said III-V compound, periodic table group 13 Al, Ga, In (may include Tl) and 15 group P, As, Sb (may include N) The resulting atomic ratio compound is 1: 1, and the II-VI compound includes atoms of Zn, Cd, Hg of Group 12 elements of the periodic table and S, Se, Te (may include O) of Group 16 elements. A 1: 1 ratio of compounds is mentioned.
The semiconductor material described above may be pure or may be doped with an impurity element (for example, a group 12, 14, or 16 element). Doping may be performed at any time, and can be performed at any stage such as the stage of forming the semiconductor nanoparticles or after the formation of the semiconductor layer.
Among these semiconductor materials, silicon (Si) and germanium (Ge) are preferable, and germanium (Ge) is particularly preferable.

In the present invention, semiconductor nanoparticles having an average primary particle diameter of 1 to 100 nm are used for dispersibility in a coating solution, reduction treatment, easiness of firing, fine line reproducibility during pattern formation, and the like. From the viewpoint of
The average primary particle diameter of the semiconductor nanoparticles is preferably 1 nm or more because it can be easily synthesized and can be stably dispersed. On the other hand, when the average primary particle size is 100 nm or less, the dispersion stability of the coating liquid is good and the melting point can be made lower than the melting point of the original semiconductor material, so that sufficient sintering is possible. A dense and smooth semiconductor film is obtained, and fine line reproducibility during pattern formation is improved.
From the above viewpoint, the average primary particle diameter of the semiconductor nanoparticles is more preferably in the range of 1 to 50 nm, and further preferably in the range of 2 to 30 nm. Here, the average primary particle diameter of the semiconductor nanoparticles is measured from an image observed with a transmission electron microscope.
In addition, the surface of the semiconductor nanoparticles used in the present invention may be oxidized or may be oxidized to the inside.

The shape of the semiconductor nanoparticles is not particularly limited and may be any of a spherical shape, a rod shape, a fiber shape, a plate shape, an irregular shape, and the like, but a spherical shape or an irregular shape is preferable from the viewpoint of dispersibility.
Moreover, in order to improve the dispersion stability of the coating liquid, the semiconductor nanoparticles may be subjected to a surface treatment, or a dispersant composed of a polymer, an ionic compound, a surfactant, or the like may be added.
In the present invention, germanium nanoparticles (Ge nanoparticles) are particularly preferably used as the semiconductor nanoparticles.

  The semiconductor nanoparticles used in the present invention are a physical synthesis method such as spark erosion method, gas evaporation method, vacuum deposition method, sputtering method, CVD method; thermal decomposition method, chemical reduction method, electrolysis method, ultrasonic method, It is synthesized by chemical synthesis methods such as laser ablation method and microwave synthesis method, but physical synthesis method is preferable in terms of purity and particle size control, especially vacuum deposition method in terms of simplicity of synthesis. Is particularly preferred.

(Coating solution containing semiconductor nanoparticles)
Water and / or an organic solvent can be used as a dispersion medium for forming a coating solution containing semiconductor nanoparticles and dispersing the semiconductor nanoparticles. Organic solvents include methanol, ethanol, n-propanol, isopropanol, n-butanol, alcohols such as ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, and glycerin; aromatic hydrocarbons such as toluene and xylene; acetone, methyl ethyl ketone , Ketones such as methyl isobutyl ketone, cyclohexanone, isophorone; esters such as methyl acetate, ethyl acetate, propyl acetate, butyl acetate, isobutyl acetate; tetrahydrofuran, dioxane, ethylene glycol monomethyl ether (methyl cellosolve), ethylene glycol monoethyl ether (Ethyl cellosolve), ethers such as ethylene glycol monobutyl ether (butyl cellosolve), hexane, etc. Aliphatic hydrocarbons, alicyclic hydrocarbons such as cyclohexane, chloroform, dichloroethane, and some halogen-substituted hydrocarbon dichlorobenzene, and the like.

  In order to disperse the semiconductor nanoparticles in the dispersion medium, the semiconductor nanoparticles are preferably dispersed in the dispersion medium in the presence of the dispersant. As the dispersant, a polymer dispersant, a surfactant, or a compound having a polar functional group such as a thiol group, an amino group, a hydroxyl group or a carboxyl group capable of interacting with a metal or a semiconductor is preferable. These dispersants are preferably coated with the nanoparticles simultaneously with the production of the nanoparticles during the synthesis of the semiconductor nanoparticles. In particular, when semiconductor nanoparticles are synthesized by a physical synthesis method such as a vacuum deposition method, the nanoparticles are coated with a surfactant and collected with a surfactant so that the nanoparticle has good dispersion stability. This is preferable because particles can be obtained.

Specific examples of the surfactant include carboxylate-based, sulfonate-based, sulfate ester-based and phosphate ester-based anionic surfactants; cationic surfactants; amphoteric surfactants; Nonionic surfactants such as ethers, ester ethers, esters, and nitrogen-containing systems; fluorine-based surfactants; reactive surfactants and the like can be mentioned.
Of these, nitrogen-containing nonionic surfactants and ester-based nonionic surfactants are preferable in terms of ease of dispersion and dispersion stability.

Further, as the surfactant, carboxylic acid anhydrides and carboxylic acid imides are preferably used, and carboxylic acid anhydrides are particularly preferable in that a coating film can be formed thinly.
Specific examples of particularly preferred carboxylic acid anhydrides include alkyl or alkenyl succinic anhydride, alkyl or alkenyl glutaric anhydride, alkyl or alkenyl maleic anhydride, alkyl or alkenyl phthalic anhydride, and the like. Specific examples of particularly preferred carboxylic acid imides include alkyl or alkenyl succinimides, alkyl or alkenyl glutaric imides, alkyl or alkenyl maleic imides, alkyl or alkenyl phthalic imides, and the like. . By using these surfactants, dispersed particles having a small particle diameter can be formed, and a dispersion of semiconductor nanoparticles having excellent dispersibility, dispersion stability, and high concentration dispersibility can be obtained even with a small particle diameter. be able to.

  The concentration of the dispersant in the dispersion is not particularly limited and can be adjusted as appropriate, but the surfactant is preferably in the range of 0.3 to 50 parts by mass with respect to 100 parts by mass of the dispersion medium. When the amount is 0.3 part by mass or more, sufficient dispersibility is exhibited, and good dispersibility of the semiconductor nanoparticles can be obtained. On the other hand, when the amount is 50 parts by mass or less, since the dispersant does not remain in the semiconductor film obtained after firing, there is no fear of performance deterioration, which is preferable. From the above viewpoint, the concentration of the dispersant is more preferably 1 to 20 parts by mass, and particularly preferably 3 to 10 parts by mass.

  In addition, a dispersion aid may be added to the coating solution in order to improve the dispersibility and dispersion stability of the semiconductor nanoparticles in the coating solution containing semiconductor nanoparticles. As a dispersion aid, it is particularly preferable to add primary or secondary amines, carboxylic acids or alcohols.

  The primary or secondary amines as the dispersion aid are not particularly limited, and alkylamines, alkenylamines, aniline derivatives and the like are preferable. In particular, alkylamine or alkenylamine is preferable in that the dispersibility and dispersion stability of the semiconductor nanoparticles can be improved. The carbon number of the alkyl group or alkenyl group of the primary amines is not particularly limited, but is preferably 5 to 25, particularly preferably 8 to 18, from the viewpoint of improving dispersibility and dispersion stability. In the case of secondary amines, it is preferable that one organic group is the alkyl group or alkenyl group described in the primary amines. The other organic group may be a lower organic group such as a methyl group, an ethyl group, or a vinyl group. Further, the alkyl group or alkenyl group may have a linear structure or a side chain.

  Carboxylic acids as a dispersion aid are not particularly limited, but from the viewpoint of improving dispersibility and dispersion stability, fatty acids having 5 to 25 carbon atoms including the carbon number of the carboxylic acid (1) are preferable. A fatty acid having 8 to 20 carbon atoms is particularly preferred. Regarding fatty acids, those that are liquid at room temperature are more preferred.

  Alcohols as a dispersion aid are not particularly limited, but from the viewpoint of improving dispersibility and dispersion stability, alcohols having 5 to 25 carbon atoms are preferable, and alcohols having 8 to 20 carbon atoms are particularly preferable. preferable.

In addition, in the coating liquid, for example, polyester resin, acrylic resin, or urethane is used for the purpose of enhancing adhesion to a substrate, enhancing film forming property, imparting printability, and enhancing dispersibility. A resin or the like can be added as a resin binder.
Furthermore, an inorganic binder such as ethyl silicate and a silicate oligomer may be used in order to maintain adhesion or film-forming property with the base material after firing. Moreover, you may add a viscosity modifier, a surface tension modifier, a stabilizer, etc. as needed.

  The coating liquid containing semiconductor nanoparticles used in the present invention preferably has a solid content concentration of 5 to 60% by mass. When the solid content concentration is 5% by mass or more, a sufficient film thickness is obtained, and when it is 60% by mass or less, good dispersibility is obtained, and a coating liquid containing semiconductor nanoparticles on a substrate is printed in a pattern. Easy to do. From the above viewpoint, the solid content concentration in the coating liquid containing semiconductor nanoparticles is more preferably in the range of 10 to 50% by mass.

(Printing of coating liquid)
The method for printing a coating solution containing semiconductor nanoparticles on a substrate in a pattern is not particularly limited, and gravure printing, screen printing, spray coating, spin coating, comma coating, bar coating, knife coating, offset printing, flexographic printing. Methods such as printing, ink jet printing, and dispenser printing can be used. Of these, gravure printing, flexographic printing, and inkjet printing are preferable from the viewpoint that fine patterning can be performed.
Further, in the present invention, since a coating solution containing semiconductor nanoparticles can be directly printed on a substrate or the like in a desired pattern, productivity is remarkably higher than that of a lithography method using a conventional photoresist. Can be improved.

  The coating liquid containing the semiconductor nanoparticles on the substrate may be dried by a usual method after printing. Specifically, for example, it is heated and dried at a temperature of about 80 to 120 ° C. for about 0.1 to 20 minutes using a normal oven or the like. The film thickness of the printed portion after drying can be controlled by appropriately changing the coating amount, the average primary particle diameter of the semiconductor nanoparticles, and the like according to the application. Specifically, the film thickness is preferably in the range of 0.01 to 100 μm, more preferably in the range of 0.05 to 50 μm. Drying may be performed by baking by heating in a reducing atmosphere described below, or may be performed without heating in air.

(Baking process)
In the present invention, the pattern-like printed layer provided on the substrate in this way is surface wave plasma generated by application of microwave energy (hereinafter sometimes referred to as “microwave surface wave plasma”). The patterned semiconductor layer is formed by baking treatment by exposing to.
The method for generating the microwave surface wave plasma and the conditions for exposing the patterned print layer to the surface wave plasma will be described in detail later. In the present invention, the microwave surface wave plasma is reduced to a reducing gas. It is preferable to generate in the atmosphere.
When the patterned printing layer is exposed to a microwave surface wave plasma generated under an atmosphere of reducing gas (hereinafter sometimes referred to as “reducing atmosphere”) and the baking treatment is performed, the baking temperature depends on the semiconductor nanoparticles used. It is preferable to select appropriately according to the type.

In addition, before baking in a reducing atmosphere, in order to remove organic substances such as a dispersant contained in the semiconductor nanoparticle dispersion, heating is performed in the atmosphere at a temperature of about 300 to 500 ° C. for about 30 minutes to 2 hours. Is preferred. By this heat treatment, organic substances are oxidatively decomposed and removed.
In the method of the present invention, the semiconductor atmosphere is a semiconductor nanoparticle that is easily oxidized because it is a fine particle, and the surface of the semiconductor nanoparticle is an insulating oxide, and is coated in a pattern. This is for reducing and removing the oxide film and the like on the surface because the particles are not electrically connected to each other and sufficient semiconductor characteristics cannot be obtained. Semiconductor nanoparticles are easily removed by heat applied from plasma because the melting point is lower than that of the original semiconductor material when organic substances such as dispersants are removed and the oxide film on the surface is reduced and removed. The particles become sintered to each other. In the present invention, semiconductor nanoparticles oxidized to the inside of the particles may be used.
The reducing gas that forms the reducing atmosphere includes hydrogen, carbon monoxide, ammonia, or a mixed gas thereof. In particular, hydrogen gas is used to remove organic substances adhering to the surface of the fine particles. preferable.
Further, the reducing gas has an effect that plasma is easily generated when an inert gas such as helium, argon, neon, krypton, or xenon is mixed and used.

Next, a method for generating surface wave plasma in the method for manufacturing a semiconductor substrate of the present invention will be described.
(Method for generating surface wave plasma)
In the present invention, by applying microwave energy, surface wave plasma is generated, and the surface-wave plasma is exposed to the pattern-like printed layer formed using the coating liquid containing the semiconductor nanoparticles described above and subjected to a firing treatment. By doing so, a semiconductor substrate is manufactured.
There is no particular limitation on the method of generating the surface wave plasma, for example, an electrodeless electrode that supplies microwave energy from a dielectric irradiation window in a reduced pressure firing process chamber and generates surface wave plasma along the irradiation window in the firing process chamber. The use of plasma generating means is preferable in that a large area substrate can be processed.

As the plasma generating means, for example, microwave energy having a frequency of 2450 MHz is supplied from an irradiation window of a baking processing chamber, and an electron temperature is about 1 eV or less and an electron density is about 1 × 10 ¹¹ to 1 × 10 ^{13 in the} processing chamber. A cm ^-3 microwave surface wave plasma can be generated.
Microwave energy refers to high-frequency energy of 2450 MHz, but a frequency range of 2450 MHz / ± 50 MHz is allowed due to an accuracy error of a magnetron that is a microwave oscillation device.
The irradiation time is preferably about 10 seconds to 10 minutes.

  Such microwave surface wave plasma has the characteristics of high plasma density and low electron temperature, and can sinter the patterned printed layer at low temperature in a short time, and is dense, smooth and has performance It is possible to form an excellent semiconductor layer. The surface wave plasma is irradiated with plasma having a uniform density within the surface with respect to the processing surface. As a result, compared to other firing methods and other plasma methods, non-uniform film formation is less likely to occur, such as partial sintering of particles in the plane, and grain growth is prevented. As a result, a very dense and smooth film can be obtained. In addition, since it is not necessary to provide an electrode in the in-plane processing chamber, contamination of impurities derived from the electrode can be prevented, and damage to the processing material due to abnormal discharge can be prevented. Further, when a plastic substrate is used, the substrate is less damaged, and the electrode and other layers are less damaged.

  In the present invention, as described above, the microwave surface wave plasma can be generated in a reducing gas atmosphere, preferably in a hydrogen gas atmosphere. As a result, the insulating oxide present on the surface of the semiconductor nanoparticles is reduced and removed, and a semiconductor layer having good semiconductor characteristics is formed.

Thus, by exposing the printing layer to microwave surface wave plasma, preferably microwave surface wave hydrogen plasma, the growth of semiconductor particles can be suppressed, and a dense and smooth film can be obtained. As for the compactness, a dense film is obtained in which the area of voids (hereinafter referred to as “porosity”) not occupied by particles on the surface of the semiconductor layer is 15% or less, preferably 10% or less.
The porosity is calculated by analyzing the image of a scanning electron microscope image obtained at a magnification of 50,000 times and calculating the ratio of the portion where particles are present to the pore portion where particles are not present. The values calculated from 10 photographs are averaged.

[Semiconductor substrates, electronic components]
The present invention also provides a semiconductor substrate obtained by the above-described manufacturing method of the present invention, and an electronic member comprising the semiconductor substrate.
The semiconductor substrate of the present invention has a patterned semiconductor layer on a base material produced by the above-described method of the present invention, and the semiconductor layer is compact and has a suppressed growth of semiconductor particles. It has excellent semiconductor performance such as smoothness and good carrier mobility. The semiconductor substrate manufactured by the method of the present invention can be a very thin film having a semiconductor layer thickness of 200 nm or less, and for example, 120 nm or less by adjusting the viscosity and coating amount of a coating solution containing semiconductor nanoparticles. It is also possible to manufacture a thin semiconductor layer of 100 nm or less, and further about 10 to 50 nm. That is, the semiconductor substrate of the present invention not only has excellent semiconductor characteristics as described above, but also has a very thin semiconductor layer.

In addition, as a manufacturing method, a coating layer containing semiconductor nanoparticles is printed in a pattern on a substrate to form a printed layer, and this printed layer is exposed to microwave surface wave plasma and subjected to a firing treatment. Therefore, a baking process can be performed at a relatively low temperature and in a short time, and the damage to the base material is small, and a semiconductor substrate having excellent semiconductor performance can be given with high productivity.
In the semiconductor layer of the semiconductor substrate, functional layers such as an electrode, an insulating layer, an antioxidant layer, a gas barrier layer, and a diffusion preventing layer can be further formed on the semiconductor layer depending on the application.

  The electronic member of the present invention is an electronic member including the above-described semiconductor substrate of the present invention, and can be effectively used for, for example, a display TFT such as a liquid crystal display device, a solar cell, a sensor, and an opto device.

EXAMPLES Next, although an Example demonstrates this invention further in detail, this invention is not limited at all by these examples.
Note that the semiconductor substrate obtained in each example was evaluated by mobility and carrier density. The evaluation method is as follows.
(Measurement method of carrier density and measurement method of semiconductor mobility)
In accordance with the van der Pauw method described in the book “Semiconductor Evaluation Technology” (published by Takashi Katoda, Sangyo Tosho Co., Ltd.), p. A sample piece having an electrode formed thereon was prepared and used for measurement.

(Preparation of germanium nanoparticles A)
The germanium nanoparticles A used in the examples were prepared as follows.
As a dispersion medium, 380 g of (A) Lion diffusion pump oil (manufactured by Lion) was used, and 20 g of polyisobutenyl succinic acid tetraamine imide (manufactured by Sanyo Chemical Industries) was added and stirred. Lion diffusion pump oil is alkyl naphthalene having an alkyl group having 12 to 16 carbon atoms.
Subsequently, the dispersion medium (A) was placed in a rotary drum type deposition chamber, germanium particles were placed in a deposition source, and then the pressure was reduced by a vacuum pump, so that the pressure in the chamber was 10 ⁻³ Pa. The chamber was rotated while being cooled with a water flow, and heated until germanium (Ge) was dissolved and evaporated. The germanium (Ge) particles are evaporated, deposited in a dispersion medium in which the surfactant is dissolved, and taken into the surfactant, whereby a dispersion liquid in which germanium nanoparticles A are dispersed is formed.
To 50 g of the Ge nanoparticle A dispersion prepared as described above, methyl ethyl ketone (hereinafter referred to as “MEK”) is added, adjusted to a total of 500 mL, and after stirring, at 25 ° C. for 1 day. The Ge nanoparticles A were allowed to settle to settle. The supernatant was discarded and MEK was added again to remove the dispersion medium.
Next, the amount of MEK was reduced by distilling off under reduced pressure, toluene was added and redispersed, the solid content was adjusted to 22% by mass, and a Ge nanoparticle A dispersion was obtained. By observation with a transmission electron microscope, it was confirmed that Ge nanoparticles A having an average primary particle diameter of about 6 nm were dispersed without aggregation.

Example 1
A toluene dispersion of germanium nanoparticles A having an average primary particle diameter of 6 nm prepared by the above method is applied to an alkali-free glass substrate (Corning Corp., 1737) having a thickness of 0.7 mm by an inkjet printing method ( FUJIFILM Dimatix DMP-2831) was printed in a pattern and then heat-treated in an oven at 400 ° C. for 60 minutes.
Then, it processed with the microwave surface wave plasma processing apparatus (MSP-1500, the product made by a microelectronics company). The plasma treatment was performed using hydrogen gas for 3 minutes at a hydrogen introduction pressure of 10 Pa, a hydrogen flow rate of 100 mL / min, and a microwave output of 1000 W.
About the obtained semiconductor film, when the film thickness was measured with the stylus type surface shape measuring device (Dektak6M by ULVAC, Inc.), it was 0.5 micrometer. Further, the surface resistivity was measured with a low resistivity meter (Loresta GP, manufactured by Dia Instruments Co., Ltd.) in accordance with JIS K 7194. As a result, it was 1.0 × 10 ⁵ Ω / □. In addition, when the mobility was measured by the van der Pauw method, it was 15 cm ² / Vs. Further, the carrier density was about 10 ¹⁶ / cm ^3.
The obtained semiconductor film surface was observed with a scanning electron microscope (S-4800, manufactured by Hitachi High-Technologies Corporation) at a magnification of 50,000 times. A 50,000 times photograph taken with the electron microscope is shown in FIG.
Further, the surface porosity obtained by obtaining five observation images, image-analyzing the obtained observation images, and calculating and averaging by the ratio of the portion where the particles are present and the void portion where the particles are not present Was 7.5%.

Example 2
The toluene dispersion of germanium nanoparticles having an average primary particle diameter of 6 nm prepared by the above method is applied to a 75 μm-thick polyimide substrate (manufactured by Toray DuPont Films, Kapton 300H) by inkjet printing (FUJIFILM Dimatix). After printing in a pattern using DMP-2831), heat treatment was performed in an oven at 300 ° C. for 60 minutes.
Then, it processed with the microwave surface wave plasma processing apparatus (MSP-1500, the product made by a microelectronics company). The plasma treatment was performed using hydrogen gas for 2 minutes at a hydrogen introduction pressure of 10 Pa, a hydrogen flow rate of 100 mL / min, and a microwave output of 1000 W.
About the obtained semiconductor film, it was 0.7 micrometer when the film thickness was measured with the stylus type surface shape measuring device (Dektak6M by ULVAC). Further, when the surface resistivity was measured with a low resistivity meter (Loresta GP, manufactured by Dia Instruments Co., Ltd.) in accordance with JIS K 7194, it was 1.2 × 10 ⁵ Ω / □. In addition, when the mobility was measured by the van der Pauw method, it was 8 cm ² / Vs. The carrier density was about 10 ¹⁷ / cm ³ .
With respect to the surface of the obtained semiconductor film, the porosity measured by the same method as described in Example 1 was 8.6%.

(Preparation of germanium nanoparticles B)
Germanium nanoparticles B were prepared as follows.
As a dispersion medium, 280 g of (A) alkylnaphthalene (alkyl group: 16 to 20 carbon atoms) was used, and 120 g of tetrapropenyl succinic anhydride was added thereto and stirred.
Subsequently, the dispersion medium (A) was placed in a rotary drum type deposition chamber, germanium particles were placed in a deposition source, and then the pressure was reduced by a vacuum pump, so that the pressure in the chamber was 10 ⁻³ Pa. The chamber was rotated while being cooled with a water flow, and heated until germanium (Ge) was dissolved and evaporated. The germanium (Ge) particles are evaporated, deposited in a dispersion medium in which the surfactant is dissolved, and taken into the surfactant to form a dispersion in which germanium nanoparticles B are dispersed.
To 100 g of the Ge nanoparticle B dispersion prepared as described above, 500 g of methanol was added and stirred. Since the liquid containing Ge nanoparticles B was separated and settled, the liquid was completely separated using a centrifuge (10000 × g, 5 minutes), and the supernatant was removed. 500 g of ethyl acetate was added to the remaining precipitate and stirred, and the liquid containing Ge nanoparticles B was completely separated again using a centrifuge (10000 × g, 5 minutes), and the supernatant was removed. Was repeated three times.
The remaining precipitate was collected in an eggplant flask, the solvent was removed using a rotary evaporator, 10 g of toluene was added to 10 g of the obtained solid, and 2.5 g of oleylamine was further added and stirred. The obtained liquid had a blackish brown color, and a Ge nanoparticle B dispersion liquid in which aggregation was not visually confirmed was obtained. By observation with a transmission electron microscope, it was confirmed that germanium (Ge) nanoparticles B having an average primary particle diameter of about 10 nm were dispersed without being aggregated. The dispersion had a solid content of 14.7% and a viscosity of 0.9 mPa · s.

Example 3
In order to clean the substrate, surface treatment of the quartz glass substrate (Asahi Glass Co., Ltd.) was carried out with oxygen gas for 10 minutes using a high-frequency plasma processing apparatus (PED-350, manufactured by Canon Anelva Engineering Co., Ltd.). Moreover, after spin-coating Ge nanoparticle B dispersion liquid on quartz glass, it heat-processed in air | atmosphere at 500 degreeC for 30 minutes.
Next, quartz glass (hereinafter, simply referred to as a sample) coated with Ge nanoparticles B is set on a sample stage in a plasma chamber of a microwave surface wave plasma processing apparatus (MSP-1500, manufactured by Microelectronics). The sample was heated to 350 ° C. and then subjected to plasma treatment. The plasma treatment was performed using hydrogen gas at a hydrogen introduction pressure of 10 Pa, a hydrogen flow rate of 10 mL / min, and a microwave output of 1000 W for 2 minutes to obtain a semiconductor substrate having a germanium film on quartz glass. The temperature immediately after the plasma treatment of the semiconductor substrate was 450 ° C.

About the obtained semiconductor substrate, the cross section was observed with a scanning electron microscope at a magnification of 50,000 times. FIG. 3 shows a 50,000 times photograph taken with the electron microscope. From the photograph of FIG. 3, the germanium film had a thickness of 100 nm, and no unreacted portion was confirmed in the film.
Further, the porosity of the obtained semiconductor film surface measured by the same method as described in Example 1 was 10.3%.

Reference example 1
Similar to that used in Example 1, a toluene dispersion of germanium nanoparticles having an average primary particle size of 6 nm was inkjet-printed on a quartz substrate (manufactured by Asahi Glass Co., Ltd., synthetic quartz AQ) having a thickness of 0.75 mm. The coating film was formed into a pattern by FUJIFILM Dimatrix DMP-2831), and then heat-treated in an oven at 400 ° C. for 60 minutes. Thereafter, reduction was performed at 650 ° C. in a reducing atmosphere using hydrogen gas to obtain a semiconductor substrate.
In the reduction, the temperature was raised at 10 ° C./min, held at 650 ° C. for 30 minutes, and then air-cooled. As a reducing gas, a mixed gas of argon / hydrogen = 96/4 (volume ratio) was used.
About the said semiconductor substrate, when the semiconductor film thickness was measured with the stylus type surface shape measuring device (Dektak6M by ULVAC, Inc.), it was 0.5 micrometer. Further, when the surface resistance was measured with a low resistivity meter (Loresta GP manufactured by Dia Instruments Co.) in accordance with JIS K 7194, it was 1.7 × 10 ⁵ Ω / □. Further, when the mobility was measured by the van der Pauw method, it was about 9 cm ² / Vs, and the carrier density was about 10 ¹⁶ / cm ³ .
The obtained semiconductor film surface was observed with a scanning electron microscope (S-4800, manufactured by Hitachi High-Technologies Corporation) at a magnification of 50,000 times. FIG. 2 shows a 50,000 times photograph taken with the electron microscope.
Further, the surface porosity obtained by obtaining five observation images, image-analyzing the obtained observation images, and calculating and averaging by the ratio of the portion where the particles are present and the void portion where the particles are not present Was 18.8%.

Reference example 2
Similar to that used in Example 1, a toluene dispersion of germanium nanoparticles having an average primary particle size of 6 nm was inkjet-printed on a quartz substrate (manufactured by Asahi Glass Co., Ltd., synthetic quartz AQ) having a thickness of 0.75 mm. A coating film was formed in a pattern by FUJIFILM Dimatrix DMP-2831), and then heat-treated in an oven at 350 ° C. for 60 minutes. Then, it reduced by the high frequency hydrogen plasma process, and the semiconductor substrate was obtained.
The high-frequency hydrogen plasma treatment uses “PED-350 special type” manufactured by Canon Anelva Engineering as an apparatus, the hydrogen introduction pressure is 10 Pa, the hydrogen flow rate is 100 mL / min, the high-frequency power is 500 W, and the plasma treatment time is 20 minutes. .
About the said semiconductor substrate, when the semiconductor film thickness was measured with the stylus type surface shape measuring device (Dektak6M by ULVAC, Inc.), it was 0.5 micrometer. Further, when the surface resistance was measured with a low resistivity meter (Loresta GP, manufactured by Dia Instruments Co.) in accordance with JIS K 7194, the surface resistance was 6.9 × 10 ⁵ Ω / □. Further, when the mobility was measured by the van der Pauw method, it was about 5 cm ² / Vs, and the carrier density was about 10 ¹⁷ / cm ³ .
The obtained semiconductor film surface was observed with a scanning electron microscope (S-4800, manufactured by Hitachi High-Technologies Corporation) at a magnification of 50,000 times. Obtaining five observation images, image analysis of the obtained observation image, the porosity of the surface obtained by averaging by calculating the ratio of the portion where the particles are present and the void portion where the particles are not present, It was 16.0%.

  The method for producing a semiconductor substrate of the present invention comprises a printed layer containing semiconductor nanoparticles provided on a base material, exposed to microwave surface wave plasma, and subjected to a baking process at a low temperature and in a short time, thereby being dense and smooth. This is a method for producing a semiconductor substrate formed with a semiconductor layer having excellent performance, and can be effectively used for TFT semiconductors for displays such as liquid crystal, solar cells, sensors, and opto devices.

Claims (10)

  A method for producing a semiconductor substrate, comprising: forming a printed layer by printing a coating solution containing semiconductor nanoparticles on a substrate in a pattern; and firing the printed layer to form a patterned semiconductor layer. A method for producing a semiconductor substrate, comprising subjecting the printed layer to baking treatment by exposing the printed layer to surface wave plasma generated by application of microwave energy.   The method for manufacturing a semiconductor substrate according to claim 1, wherein the surface wave plasma is generated in an atmosphere of a reducing gas.   The method of manufacturing a semiconductor substrate according to claim 2, wherein the reducing gas atmosphere is a gas phase atmosphere containing hydrogen.   The method for producing a semiconductor substrate according to claim 1, wherein the average primary particle diameter of the semiconductor nanoparticles is 1 to 100 nm.   The method for producing a semiconductor substrate according to claim 1, wherein the semiconductor nanoparticles are germanium nanoparticles.   The method of manufacturing a semiconductor substrate according to claim 1, wherein the base material is selected from a silicon wafer, a glass substrate, and a ceramic substrate.   The method for producing a semiconductor substrate according to claim 1, wherein the substrate is made of a plastic film having a melting point of 200 ° C. or higher.   A semiconductor substrate obtained by the manufacturing method according to claim 1.   9. The semiconductor substrate according to claim 8, wherein the porosity on the surface of the semiconductor layer is 15% or less in an observation image observed with a scanning electron microscope.   An electronic member comprising the semiconductor substrate according to claim 8.