JP2005078049A - Manufacturing method of micro lens array - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a simple manufacturing method of a micro lens array, which can freely control an refractive index and a curvature of the lens and which gives the micro lens array a high latitude of design and degree of integration as well as a high strength including solvent resistance, heat resistance, or the like. <P>SOLUTION: The method for manufacturing the micro lens array comprises a stage in which a substrate having a conductive thin film and a photovoltaic layer thin film laminated in this order on the surface is arranged in a manner that the optical semiconductor thin film comes into contact with a water-based electrolyte containing a film forming material, in which a voltage is applied between the photovoltaic layer thin film and a counter electrode by radiating the selected area of the photovoltaic layer thin film with light, and in which the film forming material is then precipitated on the selected area of the photovoltaic layer thin film to form a micro lens array layer. The method is characterized in that the electrolyte contains a radical generating agent, an acid generating agent, and at least one kind among cross linking agents having a functional group contributing to cross linking. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a method of manufacturing a microlens array in which microlenses capable of condensing light with high efficiency are integrated in an array, and specifically, a method of performing etching such as a photolithography method or a dry etching method, The present invention also relates to a method for manufacturing a robust microlens array by a simple method in place of a high refractive index material doping method using thermal diffusion or the like.

  Microlens array manufacturing methods include etching methods such as photolithography and dry etching, high-refractive index material doping using thermal diffusion, and plastic material poured into a pre-formed mold. There is a method for producing a microlens array.

  However, with the photolithography method, an arbitrary microlens array can be produced with high resolution, but it is difficult to control the curvature of the lens. The dry etching method has problems that a long etching time is required and that it is difficult to control the curvature of the lens. In addition, the high refractive index material doping method using thermal diffusion has the advantage of being a flat plate, but in order to control only by the refractive index, there are many restrictions on the shape and curvature of the lens, and heat resistance is required. However, it can be used only for glass substrates. Furthermore, the method using a pre-formed mold has a problem in the optical characteristics of a microlens array that can limit the miniaturization of the mold. In addition, all the technologies are expensive, the difficulty of increasing the area is high, and there is currently no microlens forming technology that is simple and highly flexible.

  On the other hand, the present inventors have provided an image forming method and a color filter manufacturing method excellent in resolution by using an electrodeposition material containing a colorant and performing electrodeposition or photo-deposition by applying a low voltage. (For example, refer to Patent Documents 1 to 6) These image forming methods and color filter manufacturing methods are characterized in that a colored film is formed with good resolution by a simple method. This technology is applied in the field of devices. In addition, the present inventors also provide a photocatalyst film forming method for forming a colored film such as a color filter with a high resolution by a simple method similar to the above method (see, for example, Patent Document 7).

  And the present inventors applied the said technique, and proposed the method of manufacturing a microlens array by carrying out the microfabrication using the said photo electrodeposition, without using the complicated process containing the said photolithography method (for example, And Japanese Patent Application No. 2002-18746).

However, since the microlens array is used as an optical element such as a condenser lens in addition to a display device such as a liquid crystal projector, not only transparency but also high shape accuracy is required. On the other hand, in the said manufacturing method, since the electrodeposition film | membrane was formed into a film by water system, there existed a case where performance was not satisfied with respect to the said request | requirement.
Japanese Patent Laid-Open No. 10-119414 JP 11-189899 A Japanese Patent Laid-Open No. 11-15418 JP-A-11-174790 JP-A-11-133224 JP-A-11-335894 JP 2001-140096 A

The object of the present invention is to solve the above-mentioned problems of the prior art.
That is, the present invention can freely control the refractive index and the curvature of the lens, and is simple, has a high degree of design freedom, a high degree of integration, and manufactures a microlens array having high robustness such as solvent resistance and heat resistance. It aims to provide a method.

The above-mentioned subject is achieved by the following present invention. That is, the present invention
<1> A conductive thin film and a photovoltaic layer thin film are arranged in this order on the surface of the base material with respect to an aqueous electrolyte solution containing a film-forming material whose solubility or dispersibility in aqueous liquid is reduced by changing pH. A microlens array fabrication substrate provided in a stacked manner is arranged so that the photo-semiconductor thin film is in contact with the electrolytic solution, and light is applied to a selected region of the photovoltaic layer thin film, thereby forming a photovoltaic layer thin film and A method for producing a microlens array, comprising a step of forming a microlens array layer by applying a voltage between a counter electrode and depositing the film forming material on a selected region of the photovoltaic layer thin film,
The method for producing a microlens array is characterized in that the electrolytic solution contains at least one of a radical generator, an acid generator, and a crosslinking agent having a functional group contributing to crosslinking.

<2> The method for producing a microlens array according to <1>, wherein the selected region of the photovoltaic layer thin film is irradiated with light through a photomask.

<3> The method for producing a microlens array according to <2>, wherein the photomask has a light transmittance gradation in accordance with a predetermined lens shape pattern in the light transmitting portion.

<4> The method for producing a microlens array according to <1>, wherein the selected region of the photovoltaic layer thin film is irradiated with laser light with an irradiation intensity changed according to a predetermined lens shape pattern. .

<5> The method for producing a microlens array according to <1>, wherein the selected region of the photovoltaic layer thin film is irradiated with laser light having an intensity distribution that changes in accordance with a predetermined lens shape pattern. .

<6> The method for producing a microlens array according to <5>, wherein the laser beam is a beam having a Gaussian energy distribution.

<7> The method for producing a microlens array according to <1>, wherein the photovoltaic layer thin film contains titanium oxide.

<8> The method for producing a microlens array according to <1>, wherein the film forming material is a polymer material having a carboxyl group.

<9> The method for producing a microlens array according to <1>, wherein inorganic fine particles having a light transmittance and a high refractive index are dispersed in the electrolytic solution.

<10> The method for producing a microlens array according to <9>, wherein the inorganic compound fine particles are fine particles containing rutile-type titanium oxide.

<11> A light source for irradiating light to a selected region of the photovoltaic layer thin film, and an imaging optical system having a first imaging optical lens and a second imaging optical lens The method for producing a microlens array according to <1>, wherein at least an exposure apparatus is used, and the distance between the second imaging optical lens and the microlens array substrate surface is set in a range of 1 mm to 50 cm. It is.

<12> The method for producing a microlens array according to <11>, wherein the depth of focus of the second imaging optical lens is in a range of ± 10 to ± 100 μm.

  According to the method for manufacturing a microlens array of the present invention, a microlens array having high resolution and high light collection efficiency can be manufactured at low cost without using any photolithography process. In particular, a microlens array in which the curvature and the refractive index are freely designed with a highly robust lens can be easily manufactured at low cost.

Hereinafter, the present invention will be described in more detail.
The method for producing a microlens array of the present invention is the method for producing a microlens array using the above-described photodeposition method or photocatalyst deposition method, wherein the aqueous electrolyte containing the film-forming material is a radical generator, an acid It contains at least one of a generator and a crosslinking agent having a functional group that contributes to crosslinkability.
The outline of the manufacturing method will be described below.

  The photoelectric deposition method uses the photovoltaic power generated in the photovoltaic layer thin film, and the pH changes when the conductive thin film and the photovoltaic layer thin film are laminated in this order on the surface of the substrate. With respect to the aqueous electrolyte solution containing the film-forming material whose solubility or dispersibility in aqueous liquid is reduced, the photovoltaic layer thin film is disposed so as to contact the electrolyte solution and placed in the electrolyte solution. In a state where the counter electrode and the conductive thin film are electrically connected, a voltage is applied between the selected region and the counter electrode by irradiating light to the selected region of the photovoltaic layer thin film, and the light In this method, the film forming material is deposited on a selected region of the electromotive force layer thin film. This photo-deposition method is characterized in that a film having a uniform film thickness can be accurately formed at a lower voltage (5 V or less) than the conventional electrodeposition method. The photocatalyst deposition method uses the photocatalytic function of the photovoltaic layer thin film, and is described in detail in paragraphs 0025 to 0029 of JP-A-2001-140096.

  In the method for producing a microlens array of the present invention, the above method is used. First, an electrolytic solution similar to the electrolytic solution used in the above-described photo-deposition method is used. A photovoltaic layer thin film is provided in contact with the conductive thin film, and the conductive thin film is made conductive with the electrolytic solution. Then, the microlens array manufacturing substrate is disposed so that the photovoltaic layer thin film is in contact with the electrolytic solution, and the conductive thin film is brought into conduction with the electrolytic solution. In this state, the photovoltaic layer thin film is formed. The selected region is irradiated with light, and the material is deposited on the selected region of the photovoltaic layer thin film to form a microlens array layer.

As a result, according to the present invention, a microlens array can be manufactured at a low cost by a simple method, and the degree of integration is high (50,000 / cm ² or more for a microlens having a diameter of 30 μm). An array can be produced and the degree of integration and the refractive index can be freely adjusted. In addition, a microlens array having an arbitrary pattern including a complicated one can be manufactured. Furthermore, since the obtained microlens array has high light collection efficiency and is a simple method, it can be mass-produced. In addition, the conventional method for manufacturing a microlens array using a photosensitive resin has a problem that the film thickness needs to be accurately controlled and applied to the substrate, and there is a problem that an alkaline waste liquid is produced by etching. According to the present invention, a lens having a uniform shape can be easily manufactured, an etching process for forming a pattern is unnecessary, and an environmental load is small.

In particular, in the present invention, the shape can be maintained in the heat treatment step after the formation of the microlens array layer by including the radical generator or the like in the electrolytic solution containing the film forming material.
Specifically, when a film is formed in an aqueous system as in the present invention, the microlens array layer is used for the purpose of removing moisture in the film in order to improve the transparency of the microlens as described later. However, if it is heated above the glass transition point (Tg) of the polymer material in the film-forming material at this time, the microlens array layer flows and the lens changes shape in the flattening direction. Resulting in. As a result, a deviation occurs in the edge portion of the lens, and a desired shape accuracy cannot be achieved.

  In the present invention, the polymer material in the microlens array layer at the time of heating or before heating by containing a compound that induces crosslinking such as a radical generator and / or a compound constituting the crosslinking in the electrolytic solution. Since the microlens array layer can be cured, the shape of the lens can be maintained even when heated to a high temperature during heating as described above.

  In addition, the microlens array produced in this way has a microlens array layer that is three-dimensionally cross-linked and is in a dense state. Even if it is not attacked, it can be excellent in durability. Furthermore, sufficient strength can be ensured from the viewpoint of mechanical strength.

  The microlens array production substrate in the present invention is obtained by laminating a conductive thin film and a photovoltaic layer thin film in this order on the surface of a base material. FIG. 1 shows a cross-sectional view of an example of a microlens array manufacturing substrate 1 used in the present invention. In the figure, 10 is a substrate, 12 is a conductive thin film, and 14 is a photovoltaic layer thin film.

  The substrate 10 is preferably insulating, and a glass plate, a quartz plate, a plastic film, an epoxy substrate, or the like is used. As the conductive thin film 12, ITO, indium oxide, nickel, aluminum, or the like is used. When the photovoltaic layer thin film 14 is irradiated with light through the substrate 10, the substrate 10 and the conductive thin film 12 are required to be light transmissive (transparent). However, this is not the case when light is applied to the optical semiconductor thin film 14 from the photovoltaic layer thin film side through the electrolytic solution. In the microlens array manufacturing substrate 1, it is necessary that the conductive thin film 12 and the photovoltaic layer thin film 14 are in contact with each other and that the conductive thin film 12 can be electrically connected to the electrolytic solution.

Next, the photovoltaic layer thin film 14 in the present invention will be described. As the photovoltaic layer thin film 14 used in the present invention, basically any transparent thin film semiconductor that generates an electromotive force by light irradiation can be used. Specifically, examples of the semiconductor include GaN, diamond, C—BN, SiC, ZnSe, TiO ₂ , ZnO, In ₂ O ₃ , and SnO ₂ . In particular, titanium oxide (TiO ₂ ) has an absorption of only 400 nm or less, is transparent, and can easily form an n-type semiconductor. Therefore, it can be used as it is as a substrate for manufacturing an optical device.

Examples of methods for forming the titanium oxide or the like as a semiconductor thin film include thermal oxidation methods, sputtering methods, electron beam evaporation methods (EB methods), ion plating methods, sol-gel methods, and the like. As a result, an n-type semiconductor having good characteristics can be obtained.
However, when the base material 1 has low heat resistance, for example, a plastic film, it is necessary to select a film forming method that does not adversely affect the plastic film. The sol-gel method can form titanium oxide having high optical activity as an optical semiconductor, but since it is necessary to sinter at 500 degrees, a titanium oxide film is formed on the surface of a plastic film substrate having heat resistance of about 200 ° C. It is difficult to produce.

  Therefore, when using a plastic film substrate, it is possible to form a film at a temperature as low as possible, preferably at 200 ° C. or less, and a sputtering method, particularly an RF method, which is a film forming method with relatively little damage to the substrate 1. A sputtering method is preferably used. The RF sputtering method is also preferable from the viewpoint of obtaining an anatase-type titanium oxide thin film having high optical activity. (The electron beam method and the ion plating method are not preferable because the substrate 1 is heated at around 200 ° C.)

  The electrolytic solution used in the present invention includes a film-forming material that deposits and deposits on the photovoltaic layer thin film from the electrolytic solution, since the solubility or dispersibility with respect to the aqueous liquid is lowered at least by changing the pH. If one or more kinds of film forming materials have such a film forming property, even when various refractive index control materials (which will be described later) having no film forming ability alone are dispersed in an electrolytic solution, Then, it is taken into the film-forming film forming material and fixed in the microlens array layer.

  As an example of a film-forming material in which solubility or the like decreases due to the change in pH and deposits, an acrylic and styrene copolymer polymer will be described as an example. This polymer hardly dissolves in pure water (pH 6-8), but dissolves easily when heated or becomes alkaline. In addition, it has a large hysteresis in water solubility, and once dissolved, once it becomes acidic and precipitates, it does not readily re-dissolve with neutral or weak alkali.

When a platinum electrode is immersed in this polymer aqueous solution and energized, OH ^- ions in the aqueous solution are consumed near the anode to become O ₂ , hydrogen ions increase, and the pH decreases. This is because the following reaction occurs in which the hole (p) and the OH ⁻ ion are combined in the vicinity of the anode.
2OH ⁻ + 2p ⁺ → 1/2 (O ₂ ) + H ₂ O
In order for this reaction to occur, a certain voltage is required, and as the reaction proceeds, the hydrogen ion concentration in the aqueous solution increases and the pH decreases. Therefore, when a voltage of a certain level or higher is applied, the solubility of the polymer is lowered on the anode side of the electrode, so that it becomes insoluble and a thin film is formed. That is, generally, a threshold voltage of a certain level or more is required for the formation of the thin film (electrodeposition film), and the electrodeposition film is not necessarily formed when a current flows.

  The thin film formation uses a photovoltaic force generated by irradiating a semiconductor with light to obtain the constant threshold voltage. However, the photovoltaic power alone is insufficient to form a thin film. However, if a bias voltage is applied and raised, a pattern can be formed even if the voltage level input from the outside is small. In this way, when a photovoltaic layer is provided on the electrodeposited substrate and light irradiation is used for this input signal, an arbitrary electrodeposition film having a desired shape is formed at a desired position in accordance with the amount of irradiation light. Will be able to. Nevertheless, if the voltage exceeds a certain voltage (voltage depending on the band gap of the semiconductor used), there is a problem that the Schottky barrier between the semiconductor and the solution necessary for the formation of photovoltaic power is broken, and the bias voltage that can be applied. Has its limits.

  In general, polymers well known as electrodeposition coating cannot be used for electrodeposition techniques using photovoltaic power because the voltage required for electrodeposition is 10 V or more. However, since the copolymer polymer has a hysteresis of solubility in water, it can be formed into a thin film at a low voltage, and an electrodeposition film can be formed by photovoltaic power with various semiconductors.

  Specifically, in general, the photovoltaic power of a semiconductor can be obtained at most 0.6V even with relatively large Si. However, materials that can be electrodeposited at 0.6 V are limited. Therefore, it is necessary to compensate for the insufficient voltage by applying a bias voltage. The upper limit of the bias voltage that can be applied is up to the limit at which the Schottky barrier is maintained. When the Schottky barrier is broken, an electric current flows even in a region where no light is applied, and an electrodeposition film is formed on the entire region of the substrate, so that a microlens array layer cannot be formed. For example, in the case of a material that is electrodeposited at 2.0 V, when a bias voltage of 1.5 V is applied and irradiated with light, the semiconductor photovoltaic power of the photovoltaic layer 14 is increased by 0.6 V to 2.1 V. Thus, a photo-deposited film is formed only in the selected region irradiated with light exceeding the threshold voltage necessary for electrodeposition.

  Next, a combination of a material (semiconductor) used for the photovoltaic layer and a film forming material capable of forming an electrodeposition film is determined by the polarity of the semiconductor used. As is well known as a solar cell, a photovoltaic thin film is formed using a Schottky barrier or a pn or pin junction generated at an interface in contact with a semiconductor. As an example, an n-type semiconductor will be described as an example. When there is a Schottky barrier between the n-type semiconductor and the solution, if the semiconductor side is negative, the current flows in the forward direction, but conversely, when the semiconductor side is positive, no current flows. However, even when the semiconductor side is positive and no current flows, electron-hole pairs are generated when light is irradiated, and the holes move to the solution side and current flows. In this case, since the semiconductor electrode is made positive, the electrodeposited material must be negative ions. Therefore, it becomes a combination of an n-type semiconductor and an anionic molecule, and conversely, in a p-type semiconductor, a cationic molecule is electrodeposited.

  In the present invention, the film-forming material whose solubility or dispersibility in aqueous liquid is lowered by changing the pH, such as carboxyl group or amino group, the ion dissociation property is changed by changing the pH of the solution. It is preferable to include a substance having an ionic group in the molecule. However, the presence of an ionic group is not necessarily essential for the material. Moreover, the polarity of ion is not ask | required.

  The film-forming material whose solubility or dispersibility in an aqueous liquid is reduced by changing the pH is preferably a polymer material having the above properties from the viewpoint of the mechanical strength of the microlens array. . Examples of such a polymer material include a polymer material having an ionic group (ionic polymer) as described above. The ionic polymer must have sufficient solubility or dispersibility in an aqueous liquid (including an aqueous liquid whose pH has been adjusted) and must have light transmission properties. It is.

  In addition, in order to have a function of lowering the solubility or dispersibility in aqueous liquid due to a change in pH, the polymer material has a group that ionically dissociates from a monomer unit having a hydrophobic group in the molecule (hydrophobic unit). It is preferable to have a monomer unit (ion dissociation unit) having an ionizable group such as a carboxyl group (anionic group) or an amino group (cationic group) introduced as the ion dissociating group. Preferably it is. For example, in the case of a polymer material having a carboxyl group, the carboxyl group becomes dissociated and dissolves in an aqueous liquid when the pH is in an alkaline region, and the dissociated state disappears and the solubility is lowered and precipitates in an acidic region.

  The presence of the hydrophobic unit in the polymer material, combined with the fact that the group dissociated by the change in pH as described above loses ionicity, has the function of instantly depositing a film. Given to the material. Moreover, this hydrophobic group has the capability of adsorbing refractive index control fine particles described later, and imparts a good dispersion function to the polymer. In addition, examples of the ion-dissociating group include a hydroxy group.

  The number of hydrophobic units in the polymer having hydrophobic units and ion dissociation units is preferably within the range of 30 to 80% of the total number of hydrophobic units and ion dissociation units. When the number of hydrophobic units is less than 30% of the total number of ion dissociation units and hydrophobic units, the formed film is easily re-dissolved, and the water resistance and film strength of the film may be insufficient. When the number of hydrophobic units is larger than 80% of the total number of ion dissociation units and hydrophobic units, the solubility of the polymer in the aqueous liquid becomes insufficient, so that the electrolytic solution becomes cloudy or the material precipitates Or the viscosity of the electrolytic solution tends to increase. The number of hydrophobic units relative to the total number of ion dissociation units and hydrophobic units is more preferably in the range of 55% to 70%. In this range, the film deposition efficiency is particularly high, and the electrolyte solution is stable. In addition, a film can be formed with an electrodeposition potential with low photovoltaic power.

Examples of the polymer material include those obtained by copolymerizing a polymerizable monomer having an ion dissociating group and a polymerizable monomer having a hydrophobic group.
Further, as the polymerizable monomer containing an ion dissociating group, methacrylic acid, acrylic acid, hydroxyethyl methacrylate, acrylamide, maleic anhydride, fumaric acid, propiolic acid, itaconic acid, and derivatives thereof are used. It is not limited to these. Among these, methacrylic acid and acrylic acid are useful hydrophilic monomers because of high film deposition efficiency due to pH change.

  Moreover, as the polymerizable monomer material having the hydrophobic group, alkene, styrene, α-methylstyrene, α-ethylstyrene, methyl methacrylate, butyl methacrylate, acrylonitrile, vinyl acetate, ethyl acrylate, butyl acrylate, Although lauryl methacrylate etc. and these derivatives are used, it is not limited to these. In particular, since styrene and α-methylstyrene are highly hydrophobic, they are useful hydrophobic monomers that are easy to obtain hysteresis characteristics against re-dissolution.

  As the polymer material used in the method for producing a microlens array of the present invention, a copolymer using acrylic acid or methacrylic acid as the ion dissociation unit and styrene or α-methylstyrene as the hydrophobic unit is preferably used. That is, as the polymer material, it is preferable to use a material having a carboxyl group from the viewpoint of obtaining good film forming characteristics. The content of the carboxyl group is preferably in the range of 5 to 35 mol% as the ratio of the monomer having a carboxyl group in all monomers constituting the polymer material.

  The polymer material used as a film constituent material in the method for producing a microlens array of the present invention preferably dissociates such a polymerizable monomer containing an ion dissociating group and a hydrophobic group, respectively, in the polymer. It is a polymer material copolymerized so that the ratio of the number of groups to hydrophobic groups is the above ratio, and the type of each ion-dissociating group and hydrophobic group is not limited to one type Absent.

  Moreover, a crosslinkable group can be introduce | transduced into the polymeric material used in this invention if needed. By introducing such a crosslinkable group, it is possible to promote crosslinking by a crosslinking agent having a functional group that contributes to crosslinking, which is included in the electrolyte solution described later, and also by heat treatment after the microlens array is manufactured. -It can be cured, and the mechanical strength and heat resistance of the microlens array can be further improved.

  Examples of the crosslinkable group include an epoxy group, a blocked isocyanate group (including a group that can be changed to an isocyanate group), a cyclocarbonate group, and a melamine group. Therefore, for example, a polymer obtained by copolymerizing a polymerizable monomer having a crosslinkable group, a polymerizable monomer having a hydrophilic group, and a monomer having a hydrophobic group is preferably used as the polymer material.

  Examples of the polymerizable monomer having a crosslinkable group include glycidyl (meth) acrylate, (meth) acrylic acid azide, 2- (O- [1′-methylpropylideneamino] carboxyamino) ethyl methacrylate (Showa Denko ( Product name: Karenz MO1-BN), 4-((meth) acryloyloxymethyl) ethylene carbonate, (meth) acryloylmelamine, and the like. Although these crosslinkable monomers vary depending on the type of monomer used, it is generally preferred that they are contained in the polymer compound in an amount of 1 to 20 mol%. Here, for example, “(meth) acrylate” means “acrylate” or “methacrylate”.

  The polymer material having a degree of polymerization in the range of 6,000 to 25,000 is a polymer material that obtains good film formability. More preferably, the material has a polymerization degree of 9,000 to 20,000. If the degree of polymerization is lower than 6,000, it may be easy to redissolve. When the degree of polymerization is higher than 25,000, the solubility in an aqueous liquid becomes insufficient, and the liquid may become turbid or precipitates may be generated.

  Moreover, when the said polymeric material has anionic groups, such as a carboxyl group, the favorable film formation characteristic is acquired in the acid value of this polymeric material in the range of 60-300. The range of 90-195 is more preferable. If the acid value is less than 60, the solubility in aqueous liquid becomes insufficient, the solid content concentration of the electrolytic solution cannot be raised to an appropriate value, the liquid becomes cloudy or precipitates are formed, and the liquid viscosity is low. May rise. On the other hand, if the acid value exceeds 300, the formed film may be easily dissolved again.

In addition, the polymer material has a liquidity change that causes precipitation by generating a supernatant from a dissolved state or a dispersed state in accordance with a change in pH value of an electrolyte solution in which the polymer material is dissolved, and the pH range is within 2 Preferably it occurs in When the pH range is within 2, the film can be deposited instantly even with abrupt pH change, the cohesive force of the deposited film is high, and the re-dissolution rate in the electrolyte is reduced. The effect is excellent. As a result, a highly integrated microlens array in which the shape of each microlens is arranged can be obtained.
When the pH range is larger than 2, a decrease in the deposition rate for obtaining a sufficient thin film structure or a lack of water resistance of the membrane is likely to occur. In order to obtain more preferable characteristics, the pH range is within 1.

Furthermore, the electrolyte solution in a state in which the polymer material is dissolved as described above has a characteristic that it is difficult to re-dissolve as described above, in addition to a sharp change in state that causes precipitation with respect to a change in pH value. It is preferable to have a hysteresis characteristic.
The polymer material having the above characteristics can be obtained by appropriately adjusting the kind of the hydrophilic group and the hydrophobic group, the balance between the hydrophilic group and the hydrophobic group, the acid value, the molecular weight, and the like. The polymer material as the film forming material contained in the electrolytic solution of the present invention can be arbitrarily combined with the above materials as long as the effect of forming the thin film is not impaired. A mixture of homopolar molecules, such as a mixture, or a mixture of heteropolar molecules, such as a mixture of anionic and cationic molecules.

  In the present invention, the electrolytic solution needs to contain at least one of a radical generator, an acid generator, and a crosslinking agent having a functional group that contributes to crosslinking. As described above, by previously containing a compound that induces crosslinking and / or a compound that constitutes crosslinking in the electrolytic solution, these compounds are contained in the formed microlens array layer. As described above, even when the microlens array layer is subjected to the heat treatment, the film forming material can be cross-linked during the heat treatment or before the heat treatment, and the shape change due to the heat treatment can be reduced.

  The radical generator and the acid generator are compounds that generate radicals and protons by heat, light, etc., respectively, and the generated radicals and protons attack the polymer that is a membrane constituent material, and perform hydrogen abstraction and proton donation. Followed by cross-linking between the chains by recombination or ionic bonding. Both the radical generator and acid generator not only perform hydrogen abstraction or proton donation (inducing cross-linking), but also these compounds themselves constitute a bridging bond (cross-linking). In some cases).

  The crosslinking agent having a functional group that contributes to the crosslinking literally reacts with a functional group of a polymer that is a film constituent material to form a chemical bond, and the compound itself is a bonding part of the crosslinking. To form a cross-linked structure.

  Examples of the radical generator include benzophenone compounds such as 2-benzyl-2,2-dimethylamino- (4-morpholinophenyl) butan-1-one, 2,2-bis (2-chlorophenyl) -4, 4 ', 5,5'-tetrakis (4-ethoxycarbonylphenyl) biimidazole, 4- [o-bromo-pN, N'-di (ethoxycarbonyl) aminophenyl] -2,6-di (trichloromethyl) ) -S-triazine, 7-[[4-chloro-6- (diethylamino) -s-triazin-2-yl] amino] -3-phenylcoumarin,

Further, as trihalomethyl group-containing triazine derivatives, 2-phenyl-4,6-bis (trichloromethyl) -s-triazine, 2- (p-chlorophenyl) -4,6-bis (trichloromethyl) -s-triazine, Examples include 2- (p-methylthiophenyl) -4,6-bis (trichloromethyl) -s-triazine.
Among these, 2-benzyl-2,2-dimethylamino- (4-morpholinophenyl) butan-1-one, 2,2-bis (2-chlorophenyl) -4,4 ′, 5,5′- Tetrakis (4-ethoxycarbonylphenyl) biimidazole and 2- (p-chlorophenyl) -4,6-bis (trichloromethyl) -s-triazine are preferably used.

Examples of the acid generator include onium salt compounds such as diphenyliodonium hexafluorophosphonate, diphenyliodonium trifluoroacenate, diphenyliodonium hexafluoroarsenate, diphenyliodonium-p-toluenesulfonate, 4-methoxyphenyliodonium hexafluoro. Arsenate, 4-methoxyphenyliodonium trifluoroarsenate, bis (4-tert-butylphenyl) iodonium tetrafluoroborate, triphenylsulfonium trifluoromethanesulfonate, 4-methoxyphenyldiphenylsulfonium trifluoroacenate it can.
Of these, diphenyliodonium hexafluoroarsenate and diphenyliodonium-p-toluenesulfonate are preferably used.

  The cross-linking agent having a functional group that contributes to the cross-linking is not particularly limited in terms of structure, but examples thereof include compounds having a plurality of functional groups such as a hydroxyl group, an amino group, a carboxyl group, an isocyanate group, and an epoxy group. As the compound having a functional group, a benzophenone compound, a trihalomethane group-containing triazine derivative, or the like is preferably used.

In the present invention, the microlens array layer formed by adding at least one of the above radical generator, acid generator, and crosslinking agent having a functional group that contributes to crosslinking to the electrolyte is sufficiently obtained. It can be a hard and strong film. Two or more types of radical generators, acid generators, and crosslinking agents having functional groups that contribute to crosslinking may be used.
The content of the radical generator or the like for making the sufficiently robust film is preferably in the range of 0.005 to 20% by mass, and in the range of 0.05 to 5.0% by mass in terms of the solid content concentration in the electrolytic solution. Is more preferable.

In order to crosslink the microlens array so that the shape can be maintained even when the microlens array layer containing a radical generator or the like is heated to Tg or higher in the heat treatment, for example, in the case of heating, Crosslinking is preferably performed at 120 ° C. for about 10 minutes, and in the case of light irradiation, crosslinking is performed with an ultraviolet lamp having a light intensity of 5 mW / cm ² for about 4 minutes. This crosslinking may be performed simultaneously with the heat treatment, or may be performed before the heat treatment.

Next, the conductivity of the electrolytic solution will be described. In other words, the conductivity is related to the deposition amount, and the higher the conductivity, the thicker the film deposited in a certain time and saturates at about 10 mS / cm. Therefore, when the electrical conductivity is insufficient with the polymer material alone, the deposition speed can be controlled by adding ions that do not affect the deposition, such as NH ⁴⁺ ions or Cl ⁻ ions. Usually, the electrolytic solution increases the conductivity by adding a supporting salt. Support salts generally used in electrochemistry include alkali metal salts such as NaCl and KCl, and tetraalkylammonium salts such as ammonium chloride, ammonium nitrate, and tetraethylammonium perchlorate ((C ₂ H ₅ ) ₄ NClO ₄ ). Used. These supporting salts can also be used in the present invention.

  In addition, the pH of the electrolytic solution naturally affects the formation of the thin film. For example, if the film is deposited under the condition that the solubility of the film-forming molecule is saturated before the thin film is formed, it is difficult to dissolve again after the thin film is formed. However, when the film is formed at the pH of the unsaturated solution, even if a thin film is formed, the film starts to redissolve as soon as light irradiation is stopped. Therefore, since it is desirable to form a thin film at a pH of a solution that saturates the solubility, it is necessary to adjust the electrolyte using acid or alkali at the desired pH.

In particular, as described above, the photo-deposition method can form a film at a low voltage by considering the relationship between the pH of the electrolytic solution and the deposition start point, or by using an electrolytic solution having hysteresis characteristics. is there.
In normal electrodeposition coating, an applied voltage of 70 V or more is applied, and the pH of the electrolyte is set to be considerably higher than the deposition start point of the electrodeposition material, thereby causing an irreversible reaction based on the Kolbe reaction on the electrodeposition substrate. A film is being formed. However, in the formation of such a high voltage film, as a result of the generation of bubbles, the electric field distribution on the electrode surface becomes non-uniform and the film quality of the film itself becomes non-uniform. As a result, a fine pattern with good resolution and smoothness cannot be formed with good reproducibility. On the other hand, in this case, even if the voltage is simply lowered, the film immediately re-dissolves when the voltage application is stopped, and a fine pattern with good resolution cannot be formed.

  On the other hand, the use of the electrolytic solution having the above-described characteristics has an advantage that it easily deposits even when a low voltage is applied and does not immediately re-dissolve even when the voltage application is stopped. The voltage application referred to here means the sum of the photovoltaic power generated in the photovoltaic layer thin film by light irradiation or the bias voltage supplementarily added thereto. The applied voltage is 9 V or less, preferably 5 V or less. If a film can be formed only by photovoltaic power, a bias voltage is unnecessary.

  The production method of the microlens array of the present invention utilizes a film deposition method (photodeposition method, photocatalyst deposition method) as described above. Since the film thickness obtained by these methods corresponds to the amount of light applied to the photovoltaic layer thin film, the film thickness corresponding to the cross-sectional shape of each microlens is formed by utilizing this fact. As shown, the selected region of the photovoltaic layer thin film is irradiated with a predetermined adjusted amount of light. Since the film deposition method can form a fine pattern with high resolution, a microlens array with a high degree of integration can be obtained by the method for producing a microlens array of the present invention.

  The light irradiation to the selected region of the photovoltaic layer thin film is preferably performed by light irradiation through a photomask or laser light irradiation. For example, when light irradiation is performed through a photomask in which each light transmitting portion (hereinafter, referred to as an opening) through which light is transmitted is circular, the light intensity applied to the photovoltaic layer thin film depends on each photomask. In the portion corresponding to the peripheral portion of the opening and the portion corresponding to the central portion, the light intensity is weaker in the portion corresponding to the peripheral portion than in the portion corresponding to the central portion. A difference in strength occurs. Therefore, even in the photovoltaic power generated in the photovoltaic layer thin film, there is a difference in photovoltaic power between the portion corresponding to the peripheral portion of the circle and the portion corresponding to the central portion, and the film thickness formed corresponding to the difference. There is a difference. That is, the obtained film pattern has a circular planar shape, and a lens-like film is formed in which the film thickness in the cross-sectional shape decreases toward the periphery of the circle.

  In the present invention, in the photomask, the opening follows a predetermined lens shape pattern so that the light intensity transmitted through the opening (light transmitting portion) decreases from the center of the opening to the periphery. By providing gradation of light transmittance, the shape or curvature of each lens cross section to be formed can be freely controlled. For example, by forming minute dots that do not allow light to pass through the openings in the photomask and decreasing the density of the dots from the periphery of the openings to the center, the light intensity passing through each opening decreases from the center toward the periphery. The method to make is taken. At that time, a desired lens shape can be obtained by adjusting the dot density distribution so that a film thickness corresponding to the curvature of the lens is formed.

It is also possible to selectively irradiate the photovoltaic layer thin film with laser light. At this time, by controlling the irradiation intensity of the laser light so that a film thickness corresponding to the lens shape or curvature is formed, the microlens array having the set lens shape or curvature is controlled. be able to.
The laser light may have an intensity distribution that changes according to a predetermined lens shape pattern. For example, a beam having a Gaussian energy distribution, that is, a laser light beam whose light intensity decreases from the center to the periphery of the beam as it is. By using it, a target lens-shaped pattern can be obtained.

  FIG. 2 shows an example of a microlens array 2 manufactured by the above method as a sectional view. In the figure, 10 is an insulating substrate, 12 is a conductive thin film, 14 is an optical semiconductor thin film, and 20 is a microlens.

  In the microlens array in the present invention, as shown in FIG. 2, finally, the micro lenses 20 are densely arranged at regular intervals. When the film is formed by irradiating the selected area with light. If all the microlenses 20 are formed from the beginning, the cleaning between the microlenses after the film formation is insufficient, and the shape accuracy of each microlens 20 is lowered. For this reason, the light irradiation to the selected region is not performed on all the microlens 20 portions at once, but may be performed in multiple steps, for example, in the range of 25 to 50% of the total microlens area. preferable.

  The film forming material constituting the microlens array 2 may be only an electrodeposition film made of a polymer material as described above, but the refractive index in this case is in the range of 1.4 to 1.6, In order to obtain a microlens array having a high refractive index, in addition to the above polymer material, inorganic compound fine particles having a high refractive index are dispersed in the electrolytic solution and deposited together with the polymer material. The rate can be controlled.

As the inorganic compound fine particles, those having a refractive index in the range of about 1.8 to 2.8 are preferably used. For example, TiO ₂ , ZnO, ZrO ₂ , ITO, etc. can be used. Among these, rutile-type titanium oxide fine particles are preferred because they have a large refractive index control range and high stability. The particle diameter of the fine particles is preferably in the range of 5 to 300 nm, more preferably about 20 to 120 nm. The amount of addition is appropriately determined in consideration of the refractive index required for the microlens array 2, the mechanical strength of the microlens array 2, and the like.
It is also possible to change the refractive index of the polymer by attaching a substituent to the film-forming polymer.

  In addition, as described above, when the microlens array layer deposited by the film deposition method has a scattering property and the light transmittance is insufficient, the glass of polymer material constituting the microlens array layer By heating above the transition point (Tg) (heat treatment), the voids in the layer can be removed and the light transmittance can be improved. However, the microlens array layer in the present invention can also be used in the above heat treatment. No change in shape or the like occurs. The deviation of the edge portion (A in FIG. 2) of the boundary of the microlens 20 before and after the heat treatment varies depending on the size of the microlens 20, but is preferably in the range of 0.05 to 10 μm. A range of 1 to 5 μm is more preferable.

Furthermore, in order to improve the transmittance, it is preferable to apply the antireflection film 30 to the surface of the microlens 20 formed by the above method. As a material for the antireflection film 30, SiO ₂ having a low refractive index is preferably used. In general, the optical film thickness represented by the product of the film thickness and the refractive index of the film in contact with air is preferably ¼ of the wavelength near the center of the visible band or an integer multiple thereof. . Therefore, when obtaining transparency in the visible region (400 nm to 700 nm), when the center wavelength is 550 nm, in the case of SiO ₂ having a refractive index of 1.43, the thickness of the antireflection film 30 is 96 nm or An integer multiple is preferable.

  When designing an actual lens, the refractive index of the film-forming material (polymer material, inorganic compound fine particles, etc.) varies depending on the material used, so the transmittance and wavelength required for the application must be determined through rigorous simulation. There is.

  In the microlens array 2 manufactured according to the present invention, the size of the microlens 20 is preferably in the range of 5 to 100 μm in diameter, and preferably in the range of 30 to 1000 μm in radius of curvature. The interval between the microlenses 20 is preferably in the range of 1 to 20 μm.

Next, a microlens array manufacturing apparatus used in the present invention will be described.
FIG. 3 is a conceptual diagram showing a microlens array manufacturing apparatus that uses a photomask to form a microlens array by photoelectric deposition. The microlens array manufacturing apparatus shown in FIG. 3 includes a light source (not shown) for irradiating ultraviolet rays, an imaging optical system having a first imaging optical lens 72, and a second imaging optical lens 73, A photomask 71 inserted between one imaging optical lens and a second imaging optical lens, an electrodeposition tank 80 containing an electrolyte, means 90 for applying voltage such as a potentiostat, counter electrode 91, saturation A reference electrode 92 such as a calomel electrode is provided. In this microlens array manufacturing apparatus, a mirror reflection optical system can be used instead of the imaging optical system.

  As shown in FIG. 3, the microlens array fabrication substrate is used in the manufacturing apparatus by placing it in the electrodeposition tank 80 so that the photovoltaic layer thin film 14 is in contact with the electrolytic solution. By using the projection optical system, pattern exposure can be imaged on the photovoltaic layer thin film 14, and a fine microlens array can be formed in a short exposure time. Needless to say, the means for applying the voltage can be omitted when the required electrodeposition voltage can be obtained only by the photovoltaic power.

  As a light source, what has a wavelength which has a sensitivity to the transparent semiconductor which comprises a photovoltaic layer thin film is required, and it is preferable to expose with a light source whose wavelength is 400 nm or less. Specifically, light having a wavelength of 350 nm to 400 nm such as a mercury lamp or a mercury xenon lamp is used.

  The distance between the second imaging optical lens 73 of the imaging optical system and the light-transmitting substrate surface is preferably in the range of 1 mm to 50 cm from the viewpoint of handling, and is preferably in the range of 5 mm to 50 mm. More preferred. The depth of focus of the second imaging optical lens 73 is preferably in the range of ± 10 to ± 200 μm from the viewpoint of accuracy and handling, and more preferably in the range of ± 30 to ± 100 μm.

  In addition, when the photomask 71 and the photovoltaic layer thin film 14 are close to each other, it is not necessary to use an apparatus having an exposure apparatus having an imaging optical system or a mirror reflection optical system as described above, and it is not necessary to use parallel light or close contact. Light irradiation can be performed by a mold exposure apparatus. As the irradiation light source, for example, a uniform irradiation light source of Hg—Xe can be used. For example, the photomask 71 is brought into close contact with the insulating substrate 10 of the microlens array manufacturing substrate, or in addition to this, the insulating base material 10 is made 0.2 mm or less to prevent light diffraction, thereby reducing the degree of integration. A high microlens array can be formed.

Of course, if the exposure time may be a long time, light irradiation can be performed by an inexpensive scanning laser writing apparatus. Although not shown, a scanning laser writing apparatus for laser beam irradiation such as a He—Cd laser can be used instead of the exposure apparatus of FIG. At this time, using a Gaussian beam as a laser light beam, that is, a beam whose intensity is stronger toward the center and becomes weaker toward the periphery, and turning on / off the laser light to irradiate the laser light at a predetermined position, Microlenses whose curvature and the like are determined according to the beam diameter are formed in an array.
In addition, a proximity type exposure apparatus can be used as long as the pattern resolution allows.

Regarding the exposure in the above-described microlens array manufacturing apparatus, the case of exposing from the insulating base material 10 side of the microlens array manufacturing substrate has been described, but the exposure may be performed from the photovoltaic layer thin film 14 side. In the case of exposure from the photovoltaic layer thin film 14 side, the microlens array fabrication substrate is immersed in the electrolytic solution, but the electrolytic solution used in the present invention absorbs ultraviolet rays used as irradiation light. Therefore, the photovoltaic layer thin film 14 can be exposed through the electrolytic solution. However, if the film thickness is increased, light absorption cannot be ignored and it becomes difficult to form a lens shape. Therefore, it is desirable to perform exposure from the insulating base material 10 side. In the photo-deposition method, when an electromotive force sufficient for electrodeposition can be obtained by the photovoltaic layer, it is not necessary to apply a bias voltage by a voltage application device.
In FIG. 3, the voltage application device 90 is connected to the conductive thin film 12, but the photovoltaic layer thin film 14 functions as a working electrode.

  As a device for producing a microlens array by the photocatalyst deposition method, a device having a configuration excluding the means 90 for applying voltage, the counter electrode 91 and the reference electrode 92 from the device shown in FIG. 3 may be used. . When a microlens array is manufactured using this apparatus, it is necessary that the conductive thin film 10 of the microlens array manufacturing substrate is electrically connected to the electrolytic solution.

EXAMPLES Hereinafter, although an Example is given and this invention is demonstrated further more concretely, this invention is not limited to these Examples.
(Example 1)
On the surface of a quartz glass substrate (base material) having a thickness of 0.5 mm, ITO is formed as a transparent conductive layer (conductive thin film) by a sputtering method to a thickness of 0.1 μm, and TiO ₂ is formed as a photovoltaic layer thin film. A film having a thickness of 0.2 μm was formed. In order to improve the photocurrent characteristics of TiO ₂ , reduction treatment was performed in a mixed gas of hydrogen and nitrogen to obtain a microlens array fabrication substrate. The reduction treatment was performed by annealing at 460 ° C. for 10 minutes in pure nitrogen gas mixed with 4% hydrogen gas.

  Next, a polymer material (styrene-acrylic acid random copolymer, weight average molecular weight: 19,000, hydrophobic group / (hydrophilic group + hydrophobic group) molar ratio: 73 mol%, acid value: 97 in pure water. Glass transition point: 75 ° C., decomposition point: 247 ° C., precipitation start point: pH 5.8), and an inorganic alkali is added to adjust the pH. The pH is 7.7 and the solid content concentration is 6% by mass. An aqueous solution of was prepared. To this aqueous solution, an isopropyl alcohol solution of 1% by mass of 2-phenyl-4,6-bis (trichloromethyl) -s-triazine was added, and 5-phenyl-4,6-bis (trichloromethyl) -s-triazine was 5%. An electrolytic solution was prepared while stirring to a mass%. Moreover, it adjusted with the inorganic salt so that the electrical conductivity of the electrolyte solution might be set to 3 S / cm.

Using the three-electrode electrodeposition apparatus common in the electrochemical field shown in FIG. 3, the electrolyte is put in the electrodeposition tank 80, and the TiO ₂ photovoltaic power is applied to the saturated calomel electrode as the reference electrode 92. The layer thin film 14 was used as a working electrode. At this time, the light from the first imaging optical lens 72 forms an image once on the photomask 71 and further passes through the second imaging optical lens 73 to the TiO ₂ thin film surface on the back surface of the substrate 10. Adjusted to image. The distance between the second imaging optical lens 73 and the imaging surface was 10 cm, and the depth of focus was ± 50 μm.
Further, the photomask 71 is formed with black fine dots in a light transmitting portion corresponding to one lens so that a predetermined microlens array can be formed so that the density increases from the central portion toward the peripheral edge, and density gradation (Tone of light transmittance).

Then, a bias potential of 1.7 V was applied to the working electrode, and a photo of the mask pattern of the microlens was applied from the back side of the substrate 10 by a mercury xenon lamp (manufactured by Yamashita Denso, wavelength: 365 nm, light intensity: 50 mW / cm ² ). Using the mask 71, the selected region of the TiO ₂ photovoltaic layer thin film 14 was irradiated with the light for 63 seconds. As a result, a film (microlens array layer) containing a transparent polymer having a microlens-shaped pattern was formed in the region irradiated with the transmitted light on the surface of the photovoltaic layer thin film. The film formation at this time was performed at an interval so that the area ratio was 50% with respect to the area of the entire microlens finally formed on the surface of the photovoltaic layer thin film 14. Then, washing with pure water and drying with dry air at room temperature were performed.

  Next, in the same manner as described above, an inorganic alkali is added to a polymer material styrene-acrylic acid copolymer aqueous solution to adjust the pH, thereby preparing an aqueous solution having a pH of 7.8 and a solid content concentration of 6% by mass. In this aqueous solution, 1% by mass of 2-phenyl-4,6-bis (trichloromethyl) -s-triazine in isopropyl alcohol was dissolved in 2-phenyl-4,6-bis (trichloromethyl) -s-triazine. An electrolyte solution was prepared while stirring so as to be 5% by mass. Moreover, it adjusted with the inorganic salt so that the electrical conductivity of the electrolyte solution at that time might be 8 S / cm.

The electrolyte solution was placed in an electrodeposition tank 80 of the same electrodeposition apparatus as described above, and was similarly arranged so as to use the photovoltaic layer thin film 14 of TiO ₂ as a working electrode with respect to a saturated calomel electrode. Then, a bias potential of 1.7 V was applied to the working electrode, and the mercury xenon lamp was used to irradiate the selected region of the photovoltaic layer thin film 14 with light for 72 seconds from the back side of the substrate 10 using the photomask 71. In addition, the light irradiation area | region at this time was set as the predetermined | prescribed micro lens formation area | region of the remaining area ratio 50% other than the area | region which formed the film | membrane initially.

As a result, a microlens-shaped pattern (microlens array layer) was formed in the same manner as described above in the region irradiated with the transmitted light on the surface of the TiO ₂ photovoltaic layer thin film (the area ratio was 50%). Thus, a microlens array layer in which microlenses are arranged at the microlens formation positions was obtained. Thereafter, washing with pure water and drying with dry air at room temperature were performed, then cascade cleaning was sufficiently performed with a pH adjusting liquid having a pH of 4.5, and washing with pure water was performed again.

  Next, the produced sample was heated in an oven at 80 ° C. for 1 hour to harden the electrodeposition film (crosslinking). Thereafter, in order to increase the transparency of the microlens, the sample was heat-treated in an oven at 200 ° C. for 30 minutes to produce a final microlens array.

In the microlens array, microlenses having a lens diameter of 30 μm and a radius of curvature of 20 μm are formed on the entire surface of a 100 mm square substrate (lens integration degree: 6 × 10 ⁵ pieces / cm ² ), and at the boundary edge portion. The deviation was 5 μm and the refractive index was 1.55. In addition, when an ultrasonic durability test (60 hours) with an organic solvent (ethanol) was performed, the shape of the microlens array was not changed, and no change was observed on the film surface.

  In addition, this sample was immersed in a dilute hydrochloric acid solution at 50 ° C. for 20 days, and the film quality of the formed film was observed, but no change was confirmed, indicating that the microlens array exhibits sufficient robustness. It was. Furthermore, this film was proved to be a hard film that did not cause scratches even for the 2H pencil scratch test.

(Example 2)
On the surface of a glass substrate (base material) having a thickness of 0.5 mm, ITO is formed as a transparent conductive layer (conductive thin film) by a sputtering method to a thickness of 0.1 μm. Further, TiO ₂ is sol as a photovoltaic layer thin film. -A 0.1 micrometer-thick film was formed with the gel method, and it heated at 500 degreeC for 30 minutes. Then, in order to improve the photocurrent characteristics of this TiO ₂ , as in Example 1, annealing was performed at 360 ° C. for 20 minutes in pure nitrogen gas mixed with 5% hydrogen gas as a reduction treatment to produce a microlens array. A substrate was used.

  Next, a polymer material (styrene-acrylic acid random copolymer, weight average molecular weight: 22,000, hydrophobic group / (hydrophilic group + hydrophobic group) molar ratio: 73 mol%, acid value: 100 in pure water. Glass transition point: 85 ° C., flow start point: 134 ° C., decomposition point: 247 ° C., precipitation start point: pH 5.9), and an inorganic alkali is added thereto to adjust the pH, so that the pH is 7.8. An aqueous solution having a solid content concentration of 6% by mass was prepared. To this aqueous solution, a dioxane solution of 2% by mass of diphenyliodonium-p-toluenesulfonate was mixed with stirring so that diphenyliodonium-p-toluenesulfonate was 5% by mass to prepare an electrolytic solution. Moreover, it adjusted with the inorganic salt so that the electrical conductivity of the electrolyte solution might be set to 8 S / cm.

In the same manner as in Example 1, the electrolyte solution was placed in the electrodeposition tank 80 of the electrodeposition apparatus shown in FIG. 3, and the microlens array production substrate was similarly arranged. Then, a bias potential of 1.8 V was applied to the working electrode, and the same microlens as in Example 1 was applied from the back side of the substrate 10 by a mercury xenon lamp (manufactured by Yamashita Denso, wavelength: 365 nm, light intensity: 50 mW / cm ² ). The selected region of the TiO ₂ photovoltaic layer thin film 14 was irradiated with the light for 93 seconds using the photomask 71 of the mask pattern.

  As a result, a film (microlens array layer) containing a microlens-shaped pattern of transparent polymer having a maximum thickness of 7.5 μm was formed in the region irradiated with the transmitted light on the surface of the photovoltaic layer thin film. The film formation at this time was performed at an interval so that the area ratio was 50% with respect to the area of the entire microlens finally formed on the surface of the photovoltaic layer thin film 14. Then, after washing with pure water and drying with room-temperature dry air, cascade washing was sufficiently performed with a pH adjusting liquid having a pH of 4.5, and washing with pure water was performed again.

  Subsequently, in the same manner as described above, a styrene-acrylic acid copolymer as a polymer material (weight average molecular weight: 14,000, hydrophobic group / (hydrophilic group + hydrophobic group) molar ratio: 73 mol%, acid value: 109, glass transition point: 42 ° C., decomposition point: 238 ° C., precipitation start point: pH 6.3) An inorganic alkali was added to the aqueous solution to adjust the pH, the aqueous solution having a pH of 7.8 and a solid content concentration of 6% by mass. The dioxane solution of 2% by mass of diphenyliodonium-p-toluenesulfonate was added to this aqueous solution while stirring so that the amount of diphenyliodonium-p-toluenesulfonate was 5% by mass to prepare an electrolytic solution. Moreover, it adjusted with the inorganic salt so that the electrical conductivity of the electrolyte solution might be set to 5 mS / cm.

The electrolyte solution was placed in an electrodeposition tank 80 of the same electrodeposition apparatus as described above, and was similarly arranged so as to use the photovoltaic layer thin film 14 of TiO ₂ as a working electrode with respect to a saturated calomel electrode. Then, a bias potential of 1.8 V was applied to the working electrode, and the mercury xenon lamp was used to irradiate the selected region of the photovoltaic layer thin film 14 with light for 106 seconds from the back side of the substrate 10 using the photomask 71. In addition, the light irradiation area | region at this time was set as the predetermined | prescribed micro lens formation area | region of the remaining area ratio 50% other than the area | region which formed the film | membrane initially.

As a result, a microlens-shaped pattern (microlens array layer) having a maximum thickness of 7.8 μm was formed in the same manner as described above in the region irradiated with the transmitted light on the surface of the TiO ₂ photovoltaic layer thin film (the area described above). A microlens array layer in which microlenses are arranged at all microlens formation positions was obtained. Thereafter, washing with pure water and drying with dry air at room temperature were performed, followed by sufficient cascade washing with a pH adjusting liquid having a pH of 4.8, and washing with pure water again.

Thereafter, heat treatment was performed in a heating oven at 190 ° C., and the hardening process of the electrodeposited film and the heat treatment for improving the transparency of the microlens were simultaneously performed.
In the microlens array, microlenses having a lens diameter of 30 μm and a radius of curvature of 20 μm are formed on the entire surface of a 100 mm square substrate (lens integration degree: 5 × 10 ⁵ pieces / cm ² ), and at the boundary edge portion. The deviation was 2 μm and the refractive index was 1.57. In addition, when an ultrasonic durability test (60 hours) with an organic solvent (ethanol) was performed, the shape of the microlens array was not changed, and no change was observed on the film surface.

In addition, this sample was immersed in a dilute hydrochloric acid solution at 50 ° C. for 20 days, and the film quality of the formed film was observed, but no change was confirmed, indicating that the microlens array exhibits sufficient robustness. It was. Furthermore, this film was proved to be a hard film that did not cause scratches even for the 2H pencil scratch test.
Finally, a microlens array was completed by coating the surface of the microlens array layer with a transparent epoxy resin having a thickness of 0.5 μm as a protective layer.

(Example 3)
On the surface of a polysulfone film (base material) having a thickness of 0.2 mm, ITO was formed as a transparent conductive film (conductive thin film) by a sputtering method to a thickness of 0.16 μm, and TiO ₂ was formed as a photovoltaic layer thin film. A film having a thickness of 0.2 μm was formed. Then, in order to improve the photocurrent characteristics of this TiO ₂ , as in Example 1, annealing is performed at 170 ° C. for 20 minutes in pure nitrogen gas mixed with 4% hydrogen gas as a reduction treatment, thereby producing a microlens array. A substrate was used. Thereafter, it was washed with a pH adjusting liquid having a pH of 4.2.

  Next, a polymer material (styrene-acrylic acid random copolymer, weight average molecular weight: 13,000, hydrophobic group / (hydrophilic group + hydrophobic group) molar ratio: 70 mol%, acid value: 95 in pure water. Glass transition point: 46 ° C., decomposition point: 244 ° C., precipitation start point: pH 5.9), and an inorganic alkali is added to adjust the pH. The pH is 7.8 and the solid content concentration is 8% by mass. An aqueous solution of was prepared. To this aqueous solution, 2.5% by mass of 2-benzyl-2,2-dimethylamino- (4-morpholinophenyl) butan-1-one in dioxane was added to 2-benzyl-2,2-dimethylamino- ( 4-Morpholinophenyl) butan-1-one was mixed with stirring so as to be 5% by mass to prepare an electrolytic solution. Moreover, it adjusted with the inorganic salt so that the electrical conductivity of the electrolyte solution might be set to 12 mS / cm.

In the same manner as in Example 1, the electrolyte solution was placed in the electrodeposition tank 80 of the electrodeposition apparatus shown in FIG. 3, and the microlens array production substrate was similarly arranged. Then, a bias potential of 1.7 V was applied to the working electrode, and the same microlens as in Example 1 was applied from the back side of the substrate 10 by a mercury xenon lamp (manufactured by Yamashita Denso, wavelength: 365 nm, light intensity: 50 mW / cm ² ). The selected region of the TiO ₂ photovoltaic layer thin film 14 was irradiated with the light for 102 seconds using the photomask 71 having the above mask pattern.

  As a result, a film (microlens array layer) containing a transparent polymer having a microlens shape pattern with a maximum thickness of 4.8 μm was formed in the region irradiated with the transmitted light on the surface of the photovoltaic layer thin film. The film formation at this time was performed at an interval so that the area ratio was 50% with respect to the area of the entire microlens finally formed on the surface of the photovoltaic layer thin film 14. Then, after washing with pure water and drying with room-temperature dry air, cascade washing was sufficiently performed with a pH adjusting liquid having a pH of 4.5, and washing with pure water was performed again.

  Subsequently, in the same manner as described above, a styrene-acrylic acid copolymer (weight average molecular weight: 10,000, hydrophobic group / (hydrophilic group + hydrophobic group) molar ratio: 68 mol%, acid value: 130, glass transition point: 65 ° C., decomposition point: 240 ° C., precipitation start point: pH 5.8) An aqueous solution having an inorganic alkali added to the aqueous solution to adjust the pH to a pH of 7.8 and a solid content concentration of 8% by mass. Into this aqueous solution, a dioxane solution of 2.5% by mass of 2-benzyl-2,2-dimethylamino- (4-morpholinophenyl) butan-1-one was added 2-benzyl-2,2- An electrolytic solution was prepared by adding dimethylamino- (4-morpholinophenyl) butan-1-one with stirring so as to be 5% by mass. Moreover, it adjusted with the inorganic salt so that the electrical conductivity of the electrolyte solution might be set to 4 mS / cm.

The electrolyte solution was placed in an electrodeposition tank 80 of the same electrodeposition apparatus as described above, and was similarly arranged so as to use the photovoltaic layer thin film 14 of TiO ₂ as a working electrode with respect to a saturated calomel electrode. Then, a bias potential of 1.7 V was applied to the working electrode, and the mercury xenon lamp was used to irradiate the selected region of the photovoltaic layer thin film 14 for 115 seconds from the back side of the substrate 10 using the photomask 71. In addition, the light irradiation area | region at this time was set as the predetermined | prescribed micro lens formation area | region of the remaining area ratio 50% other than the area | region which formed the film | membrane initially.

As a result, a microlens-shaped pattern (microlens array layer) having a maximum thickness of 4.9 μm is formed in the same manner as described above in the region irradiated with the transmitted light on the surface of the TiO ₂ photovoltaic layer thin film (the area described above). A microlens array layer in which microlenses are arranged at all microlens formation positions was obtained. Thereafter, washing with pure water and drying with dry air at room temperature were performed, and then cascade cleaning was sufficiently performed with a pH adjusting liquid having a pH of 4.2, followed by washing with pure water again.

Thereafter, heat treatment was performed in a heating oven at 170 ° C., and the hardening process of the electrodeposition film and the heat treatment for increasing the transparency of the microlens were simultaneously performed.
In the microlens array, microlenses having a lens diameter of 30 μm and a curvature radius of 20 μm are formed on the entire surface of a 100 mm square substrate (lens integration degree: 8 × 10 ⁵ pieces / cm ² ). The deviation was 0.6 μm and the refractive index was 1.61. In addition, when an ultrasonic durability test (60 hours) with an organic solvent (ethanol) was performed, the shape of the microlens array was not changed, and no change was observed on the film surface.

  In addition, this sample was immersed in a dilute hydrochloric acid solution at 50 ° C. for 20 days, and the film quality of the formed film was observed, but no change was confirmed, indicating that the microlens array exhibits sufficient robustness. It was. Furthermore, this film was proved to be a hard film that did not cause scratches even for the 2H pencil scratch test.

Example 4
On the surface of a non-alkali glass substrate having a thickness of 0.4 mm (manufactured by Corning: # 7059 glass), ITO is formed into a film having a thickness of 75 nm by RF sputtering as a transparent conductive layer (conductive thin film), and a photovoltaic layer is further formed. As a thin film, anatase TiO ₂ was formed to a thickness of 110 nm.

  Next, rutile titanium oxide (average particle size: 23 nm, refractive index: 2.7) as inorganic oxide fine particles in pure water, and a polymer material (styrene-acrylic acid random copolymer, weight average molecular weight: 13,000, molar ratio of hydrophobic group / (hydrophilic group + hydrophobic group): 65 mol%, acid value: 130, glass transition point: 95 ° C., decomposition point: 240 ° C., precipitation start point: pH 5.9), Is added so that the mass ratio (titanium oxide / polymer material) becomes 1/5, and an inorganic alkali is added to adjust the pH to produce an aqueous solution having a pH of 7.8 and a solid content concentration of 12% by mass. did. To this aqueous solution, a tetrahydrofuran solution of 3.5% by mass of 2-benzyl-2,2-dimethylamino- (4-morpholinophenyl) butan-1-one was added 2-benzyl-2,2-dimethylamino- ( 4-Morpholinophenyl) butan-1-one was mixed with stirring so as to be 10% by mass to prepare an electrolytic solution. Moreover, it adjusted with the inorganic salt so that the electrical conductivity of the electrolyte solution might be set to 3 mS / cm.

In the same manner as in Example 1, the electrolyte solution was placed in the electrodeposition tank 80 of the electrodeposition apparatus shown in FIG. 3, and the microlens array production substrate was similarly arranged. A bias potential of 1.8 V is applied to the working electrode, and a He—Cd laser beam (wavelength: 330 nm, light intensity: 10 mW / cm ² ) is selected from the back side of the substrate 10 to select the TiO ₂ photovoltaic layer thin film 14. The area was irradiated. The He-Cd laser is linked with a galvano scanner and an AO modulator, and can turn on / off laser light at a predetermined position. Further, since the laser light is a beam having a Gaussian energy distribution, the light intensity is stronger toward the center and becomes weaker toward the periphery.

  When the laser beam was scanned with this apparatus, a film (microlens array layer) containing a transparent polymer having a microlens-shaped pattern with a maximum thickness of 4.2 μm was formed. Then, after washing with pure water and drying with dry air at room temperature, the pattern image was immersed in a pH-adjusted aqueous solution having a pH of 4.2, and then washed with pure water again.

Thereafter, since there was scattering in this state and the transparency was insufficient, crosslinking was performed at 150 ° C. and heat treatment was performed to provide optical transparency. Next, the prepared sample was placed in a heating oven at 190 ° C. and left for 1 hour to complete the hardening of the electrodeposition film.
In the microlens array, a microlens of an arc portion having a lens diameter of 40 μm and a curvature radius of 90 μm is formed on the entire surface of a 100 mm square substrate (lens integration degree: 5 × 10 ⁵ pieces / cm ² ), and the boundary The deviation of the edge portion was 0.5 μm and the refractive index was 1.57. In addition, when an ultrasonic durability test (60 hours) with an organic solvent (ethanol) was performed, the shape of the microlens array was not changed, and no change was observed on the film surface.

In addition, this sample was immersed in a dilute hydrochloric acid solution at 50 ° C. for 20 days, and the film quality of the formed film was observed, but no change was confirmed, indicating that the microlens array exhibits sufficient robustness. It was. Furthermore, this film was proved to be a hard film that did not cause scratches even for the 2H pencil scratch test.
Finally, SiO ₂ functioning as an antireflection film was deposited by sputtering so as to have a thickness of 96 nm, and a microlens array having a high transmittance was obtained. The focal length of each lens was optical performance in the range of 60 to 85 μm.

(Comparative Example 1)
A microlens array was prepared in the same manner as in Example 1 except that 2-phenyl-4,6-bis (trichloromethyl) -s-triazine was not added to the electrolytic solution.

  As a result, the shape of the formed microlens array layer was the same as in Example 1, but the film flowed during the heat treatment, the deviation of the edge portion after the treatment was 8 μm, and the refractive index was 1.54. Met. Moreover, when the ultrasonic durability test by the organic solvent similar to Example 1 and the immersion test in the dilute hydrochloric acid solution were performed, in any case, the shape change and film quality change (crack and desorption) of the microlens array were observed. confirmed. Further, this film was insufficient in scratch resistance even for the 2H pencil scratch test.

It is sectional drawing which shows an example of a microlens array production board | substrate. It is sectional drawing which shows an example of a microlens array. It is a conceptual diagram which shows an example of a microlens array manufacturing apparatus.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Microlens array production board | substrate 2 Microlens array 10 Base material 12 Conductive thin film 14 Photovoltaic layer thin film 71 Photomask 72, 73 Imaging optical lens 80 Electrolysis tank 90 Potentiostat 91 Counter electrode 92 Reference electrode

Claims (12)

A conductive thin film and a photovoltaic layer thin film are laminated in this order on the surface of a base material with respect to an aqueous electrolyte solution containing a film-forming material whose solubility or dispersibility in aqueous liquids decreases as pH changes. The provided microlens array fabrication substrate is arranged so that the photo-semiconductor thin film is in contact with the electrolytic solution, and the photovoltaic layer thin film, the counter electrode, and the counter electrode are irradiated by irradiating light to a selected region of the photovoltaic layer thin film. A method for producing a microlens array, including a step of applying a voltage between and depositing the film forming material on a selected region of the photovoltaic layer thin film to form a microlens array layer,
The method for producing a microlens array, wherein the electrolytic solution contains at least one of a radical generator, an acid generator, and a crosslinking agent having a functional group that contributes to crosslinking.   2. The method of manufacturing a microlens array according to claim 1, wherein light is irradiated to a selected region of the photovoltaic layer thin film through a photomask.   The method of manufacturing a microlens array according to claim 2, wherein the photomask has a light transmittance gradation according to a predetermined lens shape pattern in the light transmitting portion.   2. The method of manufacturing a microlens array according to claim 1, wherein the selected region of the photovoltaic layer thin film is irradiated with laser light while changing an irradiation intensity according to a predetermined lens shape pattern.   2. The method of manufacturing a microlens array according to claim 1, wherein the selected region of the photovoltaic layer thin film is irradiated with laser light having an intensity distribution that changes in accordance with a predetermined lens shape pattern.   6. The method of manufacturing a microlens array according to claim 5, wherein the laser light is a beam having a Gaussian energy distribution.   The method for manufacturing a microlens array according to claim 1, wherein the photovoltaic layer thin film contains titanium oxide.   The method for manufacturing a microlens array according to claim 1, wherein the film forming material is a polymer material having a carboxyl group.   2. The method for producing a microlens array according to claim 1, wherein inorganic fine particles having a light transmittance and a high refractive index are dispersed in the electrolytic solution.   The method for producing a microlens array according to claim 9, wherein the inorganic compound fine particles are fine particles containing rutile-type titanium oxide.   At least a light source for irradiating the selected region of the photovoltaic layer thin film with a light source, and an imaging optical system having a first imaging optical lens and a second imaging optical lens 2. The method of manufacturing a microlens array according to claim 1, wherein an exposure apparatus is used to perform the distance between the second imaging optical lens and the microlens array substrate surface in a range of 1 mm to 50 cm.   The method of manufacturing a microlens array according to claim 11, wherein the focal depth of the second imaging optical lens is in a range of ± 10 to ± 100 µm.

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