JP2005062304A - Method for manufacturing micro lens array and manufacturing apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for manufacturing a micro lens array and a manufacturing apparatus for easily manufacturing a micro lens array having high light condensing efficiency and being controlled to have desired curvature. <P>SOLUTION: While a film forming substrate having a conductive thin film and an optical semiconductor thin film consecutively deposited on an insulating substrate is kept in contact with an aqueous electrolyte liquid containing a film forming material the solubility or dispersibility of which with an aqueous liquid decreases by changes in the pH, a selected region of the optical semiconductor thin film is irradiated with light to form a micro lens array layer. The layer is heated at 50 to 200°C and subjected to plastic deformation under reduced pressure of 0.1 to 100 kPa to obtain the micro lens array. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a method and apparatus for manufacturing a microlens array, and more particularly to a method and apparatus for manufacturing a microlens array suitable for a display device such as a liquid crystal projector and an optical element such as a condenser lens.

  The manufacturing method of the microlens array includes an etching process such as a photolithography process and dry etching, a high refractive index material doping method by thermal diffusion, and a method of forming a microlens array by pouring a plastic material into a preformed mold. and so on. However, in the photolithography process, an arbitrary microlens array can be formed with high resolution. However, the microlens produced by this process collects light by producing a diffraction phenomenon at the staircase-shaped edge, and therefore is more concentrated than a curved surface. Poor light characteristics. The dry etching method requires a long etching time, has low production efficiency, and is difficult to control the curvature of the lens. The high-refractive-index material doping method by thermal diffusion has the advantage of being a flat plate, but because it is controlled only by the refractive index, there are many restrictions on the shape and curvature of the lens, heat resistance is required, and it can only be used for glass substrates There are restrictions on equipment, such as no. Although there is a method of preparing a pre-formed mold, there is a problem that there is a limit to miniaturization of the mold. In addition, it is difficult to say that any of these techniques is a high-cost, simple and highly flexible microlens manufacturing technique (see, for example, Patent Documents 1 and 2).

  On the other hand, the present inventors have provided an image forming method excellent in resolution by using an electrodeposition material containing a coloring material in advance and performing electrodeposition or photo-deposition by applying a low voltage (photo-deposition method) (for example, Patent References 1 to 6). The methods described in these methods are characterized in that a polymer film is easily formed with high resolution, but are mainly applied in the field of display devices such as liquid crystal display devices.

  The present inventors have also proposed a photocatalyst deposition method in which a polymer film is formed with high resolution by a simple method similar to the above method (see, for example, Patent Document 7).

However, the film formation by the above-mentioned photo-deposition method or photo-catalyst film formation method changes the pH of the optical semiconductor interface by using the photoelectromotive force when the optical semiconductor is irradiated with light, and deposits the electrodeposition material to grow the film. Therefore, there is a limit in simply forming the desired curvature by controlling the pH distribution of the electrolyte solution at the optical semiconductor interface.
Japanese Patent Laid-Open No. 3-169076, JP-A-4-286360 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 microlens array is used as an optical element such as a condensing lens in addition to a display device such as a liquid crystal projector. However, a microlens array composed of curved surfaces having excellent condensing characteristics as described above is still provided. At present, the production of the photosensitive material is generally carried out by microfabrication of the photosensitive material through complicated processes including the photolithography method, and the photo-deposition method and the photocatalytic film-forming method which do not require complicated steps. Therefore, no attempt has been made to make the device particularly simple and low-cost. Therefore, there has been a demand for a technique that is low in cost, has high light collection efficiency, and can be easily controlled to a desired curvature.

  The present invention has been made in view of the above, a method of manufacturing a microlens array capable of easily producing a microlens array having high light collection efficiency and controlled to a desired curvature, and a method for manufacturing the microlens array. It aims at providing a manufacturing apparatus and makes it a subject to achieve this objective.

Specific means for solving the above problems are as follows.
<1> An aqueous substrate containing a film-forming material whose solubility or dispersibility in an aqueous liquid decreases due to a change in pH (hereinafter also simply referred to as “electrolytic solution”) and an insulating substrate (hereinafter simply referred to as “insulation”). In a state where a film forming substrate in which a conductive thin film and an optical semiconductor thin film having a photovoltaic function are sequentially provided from the substrate side is arranged so that the optical semiconductor thin film is in contact, A film forming step of forming a microlens array layer by irradiating a selected region of the optical semiconductor thin film with light to apply a voltage between the selected region and a counter electrode, and depositing the film forming material on the selected region And a molding step of heating the formed microlens array layer to 50 to 200 ° C. and plastically deforming under reduced pressure of 0.1 to 100 kPa.

  <2> An aqueous electrolyte solution (electrolyte solution) containing a film-forming material whose solubility or dispersibility in an aqueous liquid decreases due to a change in pH, an electrically conductive thin film on a conductive substrate, and a photovoltaic film in contact with the conductive thin film An optical semiconductor thin film having a power function is sequentially provided from the substrate side, and the conductive thin film is disposed so that at least the optical semiconductor thin film is in contact with the aqueous electrolyte and the conductive semiconductor thin film is in contact with the conductive thin film. A film forming step of forming a microlens array layer by depositing the film forming material in the selected region by irradiating the selected region of the optical semiconductor thin film with light while the conductive thin film is energized to the aqueous electrolyte solution; A microlens array layer having a molding step in which the formed microlens array layer is heated to 50 to 200 ° C. and plastically deformed under a reduced pressure of 0.1 to 100 kPa. It is the law.

  <3> An aqueous electrolyte containing a film-forming material whose solubility or dispersibility in an aqueous liquid decreases due to a change in pH, an electrically conductive thin film and an optical semiconductor thin film having a photovoltaic function on an insulating substrate A voltage is applied between the selected region and the counter electrode by irradiating the selected region of the optical semiconductor thin film with light applied to the film forming substrate sequentially provided from the side in a state where the optical semiconductor thin film is in contact with the substrate. Film forming means for depositing the film forming material in the selected region to form a microlens array layer, heating means for heating the microlens array layer to 50 to 200 ° C., and setting the microlens array layer to 0. A pressure reducing means for reducing the pressure to 1 to 100 kPa and plastically deforming the microlens array.

  <4> A water-based electrolyte containing a film-forming material whose solubility or dispersibility in aqueous liquid decreases due to a change in pH has a conductive thin film and a photovoltaic function in contact with the conductive thin film on an insulating substrate An optical semiconductor thin film is sequentially provided from the substrate side, and the conductive thin film is disposed so that at least the optical semiconductor thin film is in contact with the aqueous electrolyte solution and the conductive thin film is in contact with the aqueous thin film. Film forming means for forming a microlens array layer by depositing the film forming material in the selected region by irradiating the selected region of the optical semiconductor thin film with light applied to the aqueous electrolyte, and the microlens array A heating means for heating the layer to 50 to 200 ° C., and a decompression means for reducing the pressure of the microlens array layer to 0.1 to 100 kPa and plastically deforming the microlens array layer. It is a manufacturing apparatus of Nzuare.

<5> The temperature sensor for measuring a temperature at the time of heating, and a temperature control means for controlling the heating means so that the temperature measured by the temperature sensor is 50 to 200 ° C. Alternatively, the microlens array manufacturing apparatus according to <4>.
<6> The pressure sensor according to <3>, further comprising: a pressure sensor that measures a pressure during decompression; and a pressure control unit that controls the decompression means so that the pressure measured by the pressure sensor is 0.1 to 100 kPa. >-<5> The manufacturing apparatus of the microlens array in any one of.

  ADVANTAGE OF THE INVENTION According to this invention, the manufacturing method of the microlens array which can produce easily the microlens array with high condensing efficiency and controlled to the desired curvature, and the manufacturing apparatus of this microlens array can be provided. .

  The microlens array manufacturing method and microlens array manufacturing apparatus of the present invention will be described in detail below.

[Microlens array manufacturing method]
In the present invention, a microlens array is disclosed in JP-A-10-119414, JP-A-11-189899, JP-A-11-15418, JP-A-11-174790, and JP-A-11-133224. It is formed by using a photo-deposition method described in Kaihei 11-335894 or the like, or a photocatalyst deposition method described in Japanese Patent Application Laid-Open No. 2001-140096.

  The photo-deposition method uses a photovoltaic force generated in an optical semiconductor thin film, and an insulating substrate is added to an aqueous electrolyte solution containing a film-forming material whose solubility or dispersibility in an aqueous liquid decreases due to a change in pH. A conductive thin film and an optical semiconductor thin film stacked sequentially from the substrate side (film forming substrate) are arranged in a selected region of the optical semiconductor thin film in a state where the optical semiconductor thin film is in contact with the electrolytic solution. In this method, a voltage is applied between the photo-semiconductor thin film and the counter electrode in the selected region by irradiating light to deposit a film forming material on the selected region of the photo-semiconductor 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 utilizes the photocatalytic function of the photo semiconductor thin film and is described in detail in paragraphs [0025] to [0029] of JP-A-2001-140096. In the manufacturing method of the microlens array using this method, the same electrolytic solution as that used in the above-mentioned photo-deposition method is used as the electrolytic solution, and the conductive thin film and the conductive thin film are in contact with the insulating substrate as the film forming substrate. The optical semiconductor thin film is provided in order from the substrate side, and the conductive thin film is made conductive (see paragraph [0026] in the above publication) (film forming substrate). Furthermore, the film forming substrate is disposed so that the optical semiconductor thin film is in contact with the electrolytic solution, and the conductive thin film is in conduction with the electrolytic solution (see paragraph [0026] of the publication). In this method, a selected region of the optical semiconductor thin film is irradiated with light to deposit a film forming material on the selected region of the optical semiconductor thin film. In the case of this method, since no separate electrode for electrodeposition is required, a film can be formed at a low cost with a simpler apparatus. The microlens array produced in this way has a high quality equivalent to that of the photoelectric deposition method.

In the manufacturing method of the microlens array of the present invention, by using the above-described photo-deposition method or photocatalyst film formation method, the integration degree is simple and low-cost and highly integrated (50,000 / 30 μm in the micro-lens array having a diameter of 30 μm). cm ² or more) A microlens array can be manufactured, and its degree of integration and refractive index can be freely adjusted. As will be described later, a heating means and a decompression means are provided to cause plastic deformation, thereby forming a microlens array. In addition, it is possible to increase the light collection efficiency and to control the curvature of the lens as desired. In addition, a microlens array having an arbitrary pattern including a complicated one can be manufactured. Furthermore, since the method is simple, mass production is possible. In the conventional method for producing a microlens array using a photosensitive resin, it is necessary to apply the film thickness to the substrate with high accuracy, and there is a problem that an alkaline waste liquid is produced. Can easily produce a microlens having a uniform and controlled shape and curvature, does not require a complicated process including a photolithography method, and has a small environmental load.

-Substrate for film formation-
The film forming substrate in the photo-deposition method is obtained by sequentially laminating a conductive thin film and an optical semiconductor thin film on an insulating substrate from the substrate side. Insulating substrates include glass plates, quartz plates, plastic films, epoxy substrates, etc., conductive thin films include ITO, indium oxide, nickel, aluminum, etc., and optical semiconductor thin films as described below. A titanium oxide thin film or the like is suitable. In the case where light is irradiated to the optical semiconductor thin film through the insulating substrate, the insulating substrate and the conductive thin film need to be light transmissive. However, this is not the case when the optical semiconductor thin film is irradiated with light through the electrolytic solution.

  In addition, the insulating substrate, the conductive thin film, and the optical semiconductor thin film (photocatalytic thin film) of the film forming substrate in the photocatalytic film forming method can be configured in the same manner as the film forming substrate used in the photodeposition method. However, it is necessary that the conductive thin film of the film forming substrate and the optical semiconductor thin film are in contact with each other and that the conductive thin film can be electrically connected to the electrolytic solution.

  FIG. 1 shows an example of a film forming substrate according to the present invention. In FIG. 1, a film forming substrate 5 is configured by sequentially laminating a conductive thin film 2 and an optical semiconductor thin film 3 on the surface of an insulating substrate 1 from the insulating substrate 1 side. This film-forming substrate 5 is used for both the photoelectric deposition method and the photocatalytic deposition method.

Next, the optical semiconductor thin film (photocatalytic thin film) according to the present invention will be described. As the photo semiconductor thin film used for the photo-deposition method and the photo-catalyst film formation method, basically any thin film semiconductor that generates an electromotive force by photoirradiation or has a photo-catalytic function (preferably transparent) can be used. . Specifically, GaN, diamond, c-BN, some _{SiC, ZnSe, TiO 2, ZnO} , and In ₂ O _3, SnO _2. Among them, titanium oxide 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.

  As a method for providing a titanium oxide semiconductor thin film on a substrate, there are a thermal oxidation method, a sputtering method, an electron beam evaporation method (EB method), an ion plating method, a sol-gel method, and the like. As a result, a product with good characteristics can be obtained.

  However, when the substrate 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. Although the sol-gel method can form titanium oxide with high optical activity as an optical semiconductor, it needs to be sintered at 500 ° C., so a titanium oxide film is formed on a plastic film substrate having only heat resistance of about 200 ° C. It is difficult. Therefore, when a plastic film substrate is used, 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 sputtering method, which is a film forming method with relatively little damage to the substrate. Preferably used. The RF sputtering method is also preferable from the viewpoint that an anatase-type titanium oxide thin film having high optical activity can be obtained (the electron beam method and the ion plating method are not preferable because the substrate is heated at around 200 ° C.).

-Film formation process-
In the film forming step, a microlens array layer is formed by precipitating a film forming material on a selected region irradiated with light in a pattern by the photo-deposition method or the photocatalyst deposition method. A specific forming method will be described later.

(Aqueous electrolyte)
The aqueous electrolytic solution in the photodeposition method and the photocatalyst deposition method according to the present invention has at least a change in pH, that is, the solubility or dispersibility in an aqueous liquid is lowered due to the change in pH. A film forming material that is deposited on the film and deposited. 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 the electrolytic solution, Then, it is taken into the film-forming material and fixed in the microlens array.

  “Film-forming materials whose solubility or dispersibility in aqueous liquids decreases due to changes in pH” include groups (ion ions) whose ion dissociation properties change as the pH of the liquid changes, such as carboxyl groups and amino groups. It is preferable to include a substance having a functional 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 aqueous liquid decreases due to a change in pH” is preferably a polymer material having such 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 as described above (an ionic polymer).
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.

  Further, in order to have a function of lowering solubility or dispersibility in aqueous liquid due to pH change, it is preferable that the molecule has a hydrophilic group and a hydrophobic group, and the hydrophilic group includes a carboxyl group (anionic group). ), An ion-dissociating group such as an amino group (cationic group) is preferably introduced. For example, in the case of a polymer material having a carboxyl group, the carboxyl group is dissociated and dissolved in an aqueous liquid when the pH is alkaline, and the dissociated state disappears and the solubility is lowered and precipitates in the acidic region. In addition, the presence of the hydrophobic group gives the polymer material the function of instantly depositing a film, coupled with the loss of ionicity of the ion-dissociated group due to the change in pH as described above. . This hydrophobic group has the ability to adsorb refractive index control fine particles in the microlens array manufacturing method of the present invention described later, and imparts a good dispersion function to the polymer.

  Specifically, it includes a unit from a monomer having a hydrophobic group (hydrophobic unit) and a unit from a monomer having a group capable of ion dissociation (ion dissociation unit), with respect to the sum of the hydrophobic unit and ion dissociation unit. A copolymer (polymer material) having a hydrophobic unit ratio of 55 to 70% is preferred. Examples of the ion dissociating group include a carboxyl group, an amino group, a sulfo group, and a quaternary ammonium group.

  Preferred polymer materials include, for example, 1) one or more monomers selected from alkenes, styrene and derivatives thereof, and vinyl naphthalene and derivatives thereof (monomers having a hydrophobic group), and 2) an ion-dissociating acidic group. A copolymer containing each structural unit from one or more monomers is preferably used. In addition to the above-mentioned monomers, other monomers, for example, a copolymer containing each structural unit from one or more of α, β-ethylenically unsaturated carboxylic acid alkyl ester (other monomers) are preferably used.

Units composed of monomers selected from alkene, styrene and derivatives thereof, and vinyl naphthalene and derivatives thereof, which are monomers of 1), are highly hydrophobic and strongly adsorb pigment fine particles to stabilize pigment dispersion. Further, the structural unit contributes to the water resistance of the formed image due to its hydrophobicity, and also gives the image portion fastness. Furthermore, the structural unit also affects the suppression of the ion dissociation function of the monomer containing an acidic group capable of ion dissociation of the copolymer.
Alkenes preferably have about 2 to 20 carbon atoms, more preferably 2 to 10 carbon atoms, and may have other substituents as long as the hydrophobicity is not significantly impaired.
Styrene and its derivatives include styrene, α-methyl styrene, α-ethyl styrene, and the benzene ring of these styrene and its derivatives substituted with substituents that do not significantly impair the hydrophobicity or further increase the hydrophobicity. And so on. Examples of vinyl naphthalene and derivatives thereof include vinyl naphthalene, vinyl naphthalene in which the naphthalene ring is substituted with a substituent that does not significantly impair the hydrophobicity, or a substituent that further increases hydrophobicity.
Among them, alkene, styrene and derivatives thereof are useful hydrophobic monomers having high controllability during copolymer synthesis.

  The constitutional unit from the monomer containing an acidic group capable of ion dissociation, which is the monomer of 2), has a function of dissolving the copolymer in an alkaline aqueous medium, and the monomer includes α, β-ethylenic monomers. Unsaturated carboxylic acid is mentioned preferably, for example, methacrylic acid, acrylic acid, maleic anhydride or its monoester, fumaric acid or its monoester, itaconic acid or its monoester, crotonic acid and the like. In particular, methacrylic acid and acrylic acid are preferable from the viewpoint of the above functions.

  The structural unit from the α, β-ethylenically unsaturated carboxylic acid alkyl ester, which is another monomer, is a component that imparts flexibility to the copolymer. The alkyl group of the α, β-ethylenically unsaturated carboxylic acid alkyl ester preferably has 1 to 20 carbon atoms, more preferably 2 to 10 carbon atoms. For example, methacrylic acid esters such as methyl methacrylate, ethyl methacrylate and butyl methacrylate, acrylic acid esters such as methyl acrylate, ethyl acrylate and butyl acrylate, maleic acid esters such as dimethyl maleate and diethyl maleate And fumaric acid esters such as dimethyl fumarate and diethyl fumarate.

In addition, the polymer material can be a polymer material that can be crosslinked by introducing a crosslinkable group. After the microlens array is formed, the polymer material is subjected to a heat treatment to be crosslinked, so that the mechanical strength and heat resistance of the microlens array are increased. Can be 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.
From this point, for example, a polymer material obtained by copolymerizing a polymerizable monomer having a crosslinkable group, a monomer having an ion dissociating group, and a monomer having a hydrophobic group is preferable.

  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 polymerizable monomers having a crosslinkable group vary depending on the type of monomer, they are generally contained in an amount of 1 to 20 mol% in the polymer material.

  The degree of polymerization of the polymer material is preferably in the range of 6,000 to 25,000 in terms of obtaining good film forming performance. Moreover, More preferably, it is 9,000-20,000. If the degree of polymerization is lower than 6,000, it may be easily re-dissolved, and if it is higher than 25,000, solubility in an aqueous liquid may be insufficient, and the liquid may become cloudy or precipitate may be formed. .

  In addition, when the polymer material has an anionic group such as a carboxyl group, the acid value of the polymer material is preferably in the range of 60 to 300 in terms of obtaining good film forming characteristics. The range of 90-195 is more preferable. If the acid value is less than 60, the solubility in an aqueous liquid becomes insufficient, the solid content concentration of the electrolytic solution cannot be increased to an appropriate value, the liquid becomes cloudy or precipitates are formed, and the liquid viscosity is low. If it exceeds 300, the formed film may be easily dissolved again.

  The polymer material has a liquidity change within the pH range 2 in which a supernatant is generated from a dissolved state or a dispersed state to cause precipitation in accordance with a change in pH value of an electrolytic solution in which the polymer material is dissolved. Is preferred. When the pH range is within 2, the film can be instantly deposited even when abrupt pH changes, the cohesive force of the deposited film is high, and the re-dissolution rate in the electrolyte solution is reduced. The effect is excellent. Thereby, a highly integrated microlens array in which the shape of each microlens array is arranged is obtained. On the other hand, if the pH range is larger than 2, the film formation speed for obtaining a sufficient thin film structure, the lack of water resistance of the film (deteriorating the resolution) and the like are likely to occur. In order to obtain more preferable characteristics, the pH range is preferably 1 or less.

  In addition, the electrolyte solution in which the polymer material is dissolved as described above has characteristics that precipitation changes with respect to changes in pH value abruptly occurs, and further, it is difficult to re-dissolve. Is preferred. This characteristic is referred to as a so-called hysteresis characteristic. For example, in the case of an anionic polymer material, precipitation occurs abruptly as the pH decreases, but even if the pH increases (for example, at the end of electrodeposition or photocatalysis) This means that re-dissolution does not occur abruptly and the precipitation state is maintained for a certain time). On the other hand, those that do not exhibit hysteresis characteristics have increased solubility even when the pH is slightly increased, and the deposited film tends to be redissolved.

  A polymer material having hysteresis characteristics can be obtained by appropriately adjusting the type and balance of the hydrophilic group (ion-dissociating group) and the hydrophobic group, the acid value, the molecular weight, and the like. The polymer material contained in the electrolytic solution according to the present invention can be composed of any combination of the above materials as long as the thin film formability is not impaired, and can be the same as a mixture of two or more types of anionic molecules. Mention may be made of mixtures of polar molecules or mixtures of heteropolar molecules such as mixtures of anionic and cationic molecules.

(Refractive index)
Next, the refractive index control when forming the microlens array will be described.
The microlens array may be made of only a film-forming material such as the above-described polymer material, but since the refractive index in this case is about 1.4 to 1.6, a microlens array having a higher refractive index is used. In order to obtain this, in addition to the polymer material, in addition to the polymer material, inorganic oxide fine particles (refractive index control material) that are light transmissive and have a high refractive index are dispersed, and deposited together with the polymer material so that the refractive index of the film itself is increased. It can also be controlled.

As the inorganic oxide fine particles, those having a refractive index of about 1.8 to 2.8 are preferably used. For example, TiO ₂ , ZnO, ZrO ₂ , ITO and the like can be used. Rutile-type titanium oxide fine particles are preferred because they have a large refractive index control range and high stability. Moreover, when obtaining a low refractive index, a fluorine compound typified by magnesium fluoride can be preferably used. The number average particle diameter of the inorganic oxide fine particles is preferably from 0.2 to 150 nm, more preferably from 2 to 20 nm, from the viewpoint of dispersibility in the electrolyte and transparency of the microlens array. When the number average particle diameter is less than 0.2 nm, the production costs of the fine particles and the electrolyte solution may increase, and it may be difficult to stabilize the quality. Since it exceeds 1/10 of 1.5 μm which is a band, the loss of transmitted light and internal diffuse reflection may be caused and the transmitted light loss may increase. The amount of addition is appropriately determined in consideration of the refractive index required for the microlens array, the mechanical strength of the microlens array, and the like. It is also possible to change the refractive index of the polymer by attaching a substituent to the film-forming polymer material.

(conductivity)
The conductivity of the electrolyte is related to the deposition speed, in other words, the amount of deposition, and the higher the conductivity, the thicker the film deposited in a given time and saturates at about 20 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. Supporting salts generally used in the field of electrochemistry include alkali metal salts such as NaCl and KCl, and tetraalkylammonium salts such as ammonium chloride, ammonium nitrate, and tetraethylammonium perchlorate (Et ₄ NClO ₄ ). These supporting salts can also be used in the present invention.

(PH)
Naturally, the pH of the electrolyte also 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 film is deposited, it is difficult to redissolve 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 the thin film at a pH of the solution that saturates the solubility, it is possible to adjust the electrolyte using acid or alkali at the desired pH.

In particular, the photodeposition 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 as described above, or by using an electrolytic solution having hysteresis characteristics. .
In ordinary 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. Film formation is performed. However, in the formation of such a high voltage film, bubbles are generated, resulting in non-uniform electric field distribution on the electrode surface, non-uniform film quality, and irregularities on the film surface due to bubble defoaming. Or 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 re-dissolves immediately when the voltage application is stopped, and a fine pattern with good resolution cannot be formed. On the other hand, by using the electrolytic solution having the above characteristics, there is 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 voltage generated in the optical semiconductor thin film by light irradiation or the bias voltage supplementarily added thereto. The applied voltage is preferably 9 V or less, more preferably 5 V or less. In the case where a film can be formed only by photovoltaic power, it is not necessary to apply a bias voltage. Depending on the semiconductor to be used, when a bias voltage higher than the voltage depending on the semiconductor band gap is applied, there is a problem that the Schottky barrier between the semiconductor and the solution necessary for the formation of photovoltaic power is broken, There is a limit to the bias voltage that can be applied.

  The manufacturing method of the microlens array of the present invention uses the photodeposition method or the photocatalyst deposition method described above. Since the film thickness obtained by these methods corresponds to the amount of light irradiated to the optical semiconductor thin film, the film thickness corresponding to the cross-sectional shape of each microlens array can be obtained by using this film. Then, a predetermined adjusted amount of light is irradiated to a selected region of the optical semiconductor thin film. Since the photo-deposition method or the photocatalyst deposition method can form fine patterns with high resolution, the degree of integration of the microlens array can be improved.

  The selective irradiation of light to the optical semiconductor thin film can be performed by light irradiation through a photomask or laser light irradiation. For example, when light irradiation is performed through a photomask in which each portion through which light is transmitted (hereinafter also referred to as an opening) is circular, the light intensity applied to the optical semiconductor thin film is the light intensity of each opening in the photomask. There is a difference in exposure intensity in each pattern that the light intensity is weaker in the part corresponding to the circular peripheral part than the part corresponding to the central part in the part corresponding to the circular peripheral part and the part corresponding to the central part. Arise. Therefore, even in the photovoltaic power generated in the optical semiconductor thin film, a difference occurs in the photovoltaic power between the portion corresponding to the circumferential edge portion and the portion corresponding to the central portion, and the corresponding film thickness is generated. . 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 photomask, the shape or curvature of each lens cross section can be freely controlled by providing gradation so that the intensity of light transmitted through the opening decreases from the center of the opening to the periphery of the circle. For example, a minute dot that does not transmit light is formed in the opening of the photomask, and at this time, the light intensity passing through each opening is directed from the center to the periphery by decreasing the density of the dots from the periphery to the center of the opening. This can be done by a method of decreasing. At that time, the distribution of the dot density can be adjusted so that a film thickness corresponding to the curvature of the lens is formed.

  In addition, when selective light irradiation to the optical semiconductor thin film is performed with laser light, setting is performed by changing the irradiation intensity of the laser light so that a film thickness corresponding to the lens shape or curvature is formed. It is possible to control so as to obtain a microlens array having a lens shape or curvature.

  Further, the laser light has an intensity distribution that changes according to a predetermined lens shape pattern, for example, a Gaussian beam of laser light, that is, a laser light beam whose light intensity decreases from the center to the periphery of the beam as it is, A target lens-shaped pattern is obtained. However, the photo-deposition method for forming a microlens array layer utilizes the fact that a pH change occurs at the interface of a light-irradiated selected region of the optical semiconductor thin film, and provides directionality in the film thickness direction. Since the pH distribution cannot be freely formed, there is a limit to the film thickness of the microlens array to be deposited. However, as will be described later, it is possible to obtain a microlens array having a desired lens shape or curvature by further heating and reducing the pressure to plastically deform the formed microlens array layer.

Further, from the viewpoint of improving the transmittance of the microlens array, it is preferable to provide an antireflection film on the surface of the formed microlens array. As a material for the antireflection film, SiO ₂ having a low refractive index is preferably used. In general, it is preferable that the optical film thickness represented by the product of the film thickness and the refractive index of the film in contact with air is 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, and SiO ₂ having a refractive index of 1.43, the thickness of the antireflection film is 96 nm or an integer thereof. It is preferable to double.

In the film formation process, water evaporates from the liquid surface of the electrolytic solution, and solids such as polymer compounds are deposited on the liquid surface and adhere to the substrate to form residues, or the solids are taken into the formed film. In rare cases, it may cause inconveniences such as preventing the formation of a uniform film. Therefore, it is preferable to maintain the relative humidity in the vicinity of the electrolyte surface at 50% or more. Furthermore, during the deposition of the microlens array layer, the electrolyte may dry and adhere near the contact portion on the side that is in contact with the electrolyte, leaving a thin, narrow strip of dry residue. If it remains, it is possible to cut the side, but since the cost increases as the cutting process is added, the relative humidity in the vicinity of the part in contact with the electrolyte of the film forming substrate should be increased. Is preferred. In this case, it is preferable to keep the relative humidity at 70% or higher in consideration of preventing the generation of dry residue.
That is, for example, when further cleaning is performed after the microlens array layer is formed, the relative humidity in the vicinity of the substrate is consistently maintained at least from immediately before the substrate on which the electrodeposited film is formed is lifted from the electrolytic solution until the cleaning is completed. It is preferable to keep it at 50% or more. Furthermore, by maintaining the ratio at 70% or more, it is possible to effectively prevent the formation of a narrow strip-like residue on the side of the substrate.

-Washing process-
A cleaning step can be provided between the film forming step and a molding step described later.
The film forming substrate on which the microlens array layer is formed as described above has an unnecessary electrolytic solution attached due to surface tension or the like, so that the impact pressure is applied to the microlens array layer, resulting in damage, It is desirable to wash so as not to dry and stick.

  Examples of the cleaning method include immersion in pure water or other aqueous liquids, flowing water, and a method of jetting or jetting aqueous liquids or humidified air. Preferably, the aqueous liquid or humidified air is applied to a low pressure of 0.01 to 1000 KPa. By supplying pressure, the electrolytic solution adhering to the surface of the film forming substrate can be removed using a nozzle. Details thereof are described in JP-A No. 2002-317297.

-Molding process-
After the microlens array layer is formed on the film formation substrate, the microlens array layer is further heated and depressurized to form a viscous fluid and plastically deformed (possibly after a cleaning step). By this step, it can be formed into a microlens array controlled to have a desired lens shape and curvature.

  The heating in this step is set to a temperature of 50 to 200 ° C. The microlens array layer obtained in the film forming step is mainly composed of the above-described polymer material (film forming material), and becomes a viscoelastic fluid by being heated to a flow start temperature or higher. Here, the flow start temperature is described in a polymer material test method (“Polymer Engineering Course 14”, pages 364 to 369, edited by the Society of Polymer Science, Jinjinshokan, published in 1963). It means “outflow start temperature”. The polymer material suitable for the present invention has a flow initiation temperature in the range of approximately 50 to 200 ° C, preferably in the range of 80 to 150 ° C. In this case, it can heat in the range of 80-150 degreeC.

  The microlens array layer heated to the flow start temperature or more gradually changes into a viscoelastic fluid, and when further heated, the elasticity becomes weak and becomes a viscous fluid, which is plastically deformed. By performing pressure reduction as well as heating, plastic deformation can be performed faster than under atmospheric pressure at the same temperature, and while controlling the shape, curvature, and the like.

  The film-forming materials (including polymers) that make up the microlens array layer that has become a viscous fluid flow to reduce the surface area by receiving van der Waals forces between the polymer and other film-forming materials. By utilizing the fact that the microlens array layer is formed on the surface (lower surface) on the gravity direction side of the film forming substrate by utilizing the fact that the microlens array layer is also affected by gravity due to the shape change caused by It can be formed into a microlens array with protrusions, that is, a large curvature, and when formed on the surface (upper surface) opposite to the direction of gravity of the film forming substrate, it becomes a flat shape, that is, a microlens array with a loose curvature. Can be molded. Thereafter, the shape change is stopped by cooling to room temperature and returning to atmospheric pressure.

  As described above, by utilizing the fluidity of the layer by heating and decompression, a curvature portion having a desired lens curvature can be formed from the microlens array layer which is a precursor form of the microlens array. And by appropriately controlling the degree of temperature and pressure as desired, the shape and curvature of the microlens array to be finally formed can be arbitrarily controlled, and molding with a particularly high light collection efficiency is possible. Become.

  When the microlens array layer deposited as described above has scattering properties and light transmission is insufficient, the microlens array layer is heated above the glass transition point of the polymer material constituting the microlens array layer. It may be. Thereby, the space | gap in a layer can be removed and light transmittance can be improved.

  As described above, in this step, heating is performed at 50 to 200 ° C. When the heating temperature is lower than 50 ° C., the flow starting temperature of the polymer material suitable for the present invention is not reached or the elastic state is achieved. Stays and does not deform. On the other hand, when it exceeds 200 ° C., the microlens array is burnt and discolored, which is not preferable. Among the above temperature range, 80 to 150 ° C. is particularly preferable. When the heating temperature is less than 80 ° C., it takes a long time for plastic deformation, the production tact time may be long and the production cost may be high, and when it exceeds 150 ° C., the temperature distribution at the time of cooling to room temperature It may become easy to produce shape variation.

  In addition, as described above, in this step, the pressure is reduced to 0.1 to 100 kPa, whereby the deformation is accelerated. However, when the pressure under the reduced pressure is less than 0.1 Pa, the viscosity is too low. Not only is shape control difficult, but it is not realistic because it takes a long time to reduce pressure and the manufacturing cost increases, and when it exceeds 100 kPa, it flows because it is not different from atmospheric pressure or is pressurized compared to atmospheric pressure. The effect is not obtained. Among these ranges, 1 to 10 kPa is particularly preferable. When the pressure is reduced to this range, the viscosity is moderate and shape control is easy to perform.

[Microlens array manufacturing equipment]
The apparatus for producing a microlens array of the present invention includes a film forming unit for forming a microlens array layer by the following photodeposition method or photocatalyst deposition method described above, and a microlens array layer formed by the film formation unit by 50 to 50. A heating means for heating to 200 ° C. and a pressure reducing means for plastically deforming the microlens array layer formed by the film forming means by reducing the pressure to 0.1 to 100 kPa.

  In the film forming means, (1) in the case of the photo-deposition method, the electrolysis method is applied to an insulating substrate containing an aqueous electrolyte solution containing a film forming material whose solubility or dispersibility in aqueous liquid is lowered due to a change in pH. The selected region of the optical semiconductor thin film is irradiated with light in a state where the film forming substrate in which the thin film and the optical semiconductor thin film having a photovoltaic function are sequentially provided from the substrate side is arranged so that the optical semiconductor thin film is in contact As a result, a voltage is applied between the selected region and the counter electrode to deposit the film forming material on the selected region, or (2) in the case of the photocatalytic film deposition method, dissolution in an aqueous liquid is caused by a change in pH. A conductive electrolyte thin film and an optical semiconductor thin film having a photovoltaic function in contact with the conductive thin film are sequentially provided from the substrate side in an aqueous electrolyte containing a film-forming material with reduced properties or dispersibility. And The photoconductive semiconductor thin film is disposed in a state in which the electroconductive thin film is placed in a state where at least the photoconductive thin film is in contact with the electroconductive thin film and the electroconductive thin film is energized with the aqueous electrolyte. By irradiating the selected region with light, the film forming material is deposited on the selected region, thereby forming a microlens array layer. As a result, a microlens array layer that constitutes a highly integrated microlens array can be formed easily and at low cost as described above.

The film forming means can be suitably configured, for example, as shown in FIG. FIG. 2 is a schematic cross-sectional view showing a configuration example of an electrodeposition apparatus for forming a microlens array layer in a selected region of an optical semiconductor thin film by a photoelectric deposition method. That is, as shown in FIG. 2, a light source (not shown) for irradiating ultraviolet rays and a second image-forming optical lens 11 and a first light source that are sequentially provided from the light source toward the irradiation direction and image the received light. An imaging optical system including the imaging optical lens 13, a photomask 12 provided between the first imaging optical lens 13 and the second imaging optical lens 11, and the electrolytic solution 20 are accommodated. An electrodeposition electrode 14, a potentiostat 17 for applying a bias voltage, a counter electrode 15 disposed on the electrodeposition electrode so as to be in contact with the stored electrolyte 20, and a saturated calomel electrode 16 as a reference electrode. Can be configured. The film-forming substrate on which the microlens array layer is formed is disposed in the upper opening of the electrodeposition electrode 14, and the conductive thin film 2, the counter electrode 15, and the saturated calomel electrode 16 are each electrically connected to the potentiostat 17. ing. At this time, the film forming substrate (photo semiconductor thin film) functions as a working electrode for the counter electrode.
Further, the above electrodeposition apparatus can be configured using a mirror reflection optical system instead of the imaging optical system.

  When the film forming substrate 5 having the structure shown in FIG. 1 is used in such a structure, the optical semiconductor thin film 3 is in contact with the electrolytic solution 20 on the film forming substrate 5 for forming the microlens array layer. A bias voltage is applied by using a potentiostat (applying means) 17 while being placed on the electrodeposition electrode 14 (the application means for applying the bias voltage may be omitted when a necessary electrodeposition voltage can be obtained only by photovoltaic power). In this state, when the pattern light that has passed through the imaging / mirror reflection optical system is selectively imaged on the optical semiconductor thin film 3 of the film forming substrate 5, the selected region on which the pattern light is imaged A photovoltaic force is generated between the counter electrode 5 and a microlens array layer is formed in the selected region. Thereby, a fine microlens array layer can be formed in a short exposure time.

  The distance between the second imaging optical lens 11 constituting the imaging optical system and the insulating substrate (light transmissive) 1 constituting the film forming substrate 5 is 1 mm to 50 cm from the viewpoint of handling. In addition, the depth of focus of the second imaging optical lens is preferably in the range of ± 10 to ± 100 μm in terms of accuracy and handling.

  In addition, when the photomask and the optical semiconductor thin film can be brought close to each other due to the device configuration, it is not necessary to use a device equipped with an imaging optical system or a mirror reflection optical system as described above, and parallel light or close contact Light irradiation can be performed by a mold exposure apparatus.

  Examples of the light source used for light irradiation include a mercury lamp, a mercury xenon lamp, and a high-pressure mercury lamp. When a Hg—Xe uniform irradiation light source is used as the light source, for example, instead of the imaging / mirror reflection optical system shown in FIG. 2, an Hg—Xe uniform irradiation light source is arranged on the upper part of the film forming substrate 5, and A photomask is brought into close contact with the insulating substrate 1 of the film-forming substrate 5, and the insulating substrate thickness is reduced to 0.2 mm or less, thereby preventing light diffraction and providing a highly integrated microlens array layer. Formation is possible.

  When exposure over a long period of time is possible, light irradiation is possible even with an inexpensive scanning laser writing apparatus. In this case, instead of the imaging / mirror reflection optical system and the photomask shown in FIG. 2, a scanning laser writing device for laser beam irradiation such as a He—Cd laser can be used. As the laser beam, a Gaussian beam, that is, a beam whose intensity is stronger at the center of the beam and becomes weaker as it spreads from the center to the periphery, and when the laser beam is irradiated to a predetermined position by turning on / off the laser beam, Accordingly, microlenses whose curvature and the like are determined are formed in an array. In addition, a proximity type exposure apparatus can be used as long as the pattern resolution allows.

  Although the case where light irradiation is performed from the insulating substrate 1 side of the film forming substrate 5 has been described above, the exposure may be performed from the optical semiconductor thin film 3 side. In the case of exposure from the optical semiconductor thin film side, the film-forming substrate 5 is immersed in the electrolytic solution, but the electrolytic solution according to the present invention is configured so as not to absorb the irradiated ultraviolet rays. The optical semiconductor thin film 3 can be irradiated with light. However, as the film grows and becomes thicker, light absorption cannot be ignored and it becomes difficult to form a lens shape. Therefore, it is desirable to irradiate light from the insulating substrate side.

  On the other hand, in the case of the photocatalyst deposition method, for example, the same configuration except for the potentiostat 17 for applying a bias voltage, the counter electrode 15 and the reference electrode 16 provided in the electrodeposition apparatus shown in FIG. Can do. When a microlens array is manufactured using an apparatus having this configuration, the conductive thin film 2 and the optical semiconductor thin film 3 constituting the film forming substrate 5 are provided in contact with each other, and the conductive thin film 2 is electrically connected to the electrolytic solution. It is necessary to be configured as follows.

  The heating means according to the present invention heats the microlens array layer formed by the film forming means to 50 to 200 ° C. The microlens array layer can be softened by heating to a desired temperature in accordance with the components constituting the formed microlens array layer.

  In the above temperature range, a suitable temperature range differs depending on the individual component structure, but it may be heated to a temperature not lower than the flow start temperature at which the microlens array layer is softened and still not self-flowing under normal pressure. In this state, it is possible to quickly plastically deform by further reducing the pressure by a molding means described later, and the microlens array layer can be molded into a microlens array controlled to a desired curvature.

  There is no restriction | limiting in particular as a heating means, It can select suitably from well-known heaters, such as a heater and a warm air, and can use. The heating may be performed by directly heating the film-forming substrate, or preferably by indirectly adjusting the room temperature to a desired temperature range.

  The decompression unit according to the present invention is a unit that plastically deforms the microlens array layer formed by the film formation unit by reducing the pressure to 0.1 to 100 kPa under the above heating. The microlens is depressurized to a desired pressure in accordance with the degree of heating in a state where the side on which the microlens array layer is formed of the film forming substrate is arranged in a desired direction such as the gravity direction or the opposite direction. The array layer can be deformed to a desired curvature.

  In the above-described reduced pressure range, a suitable pressure range varies depending on the heating temperature, the degree of softening, etc., but may be appropriately selected so that plastic deformation is possible in relation to the heating temperature. There is no restriction | limiting in particular as a decompression means, It can select suitably from well-known decompressors, such as a rotary pump, and can use.

  In the present invention, since the plastic deformation using the decompression means needs to be performed under heating, the heating means and the decompression means are preferably provided in the same chamber. For example, a heater and a decompressor are provided in one chamber, the chamber is heated to a desired temperature in advance, and the film forming substrate on which the microlens array layer is formed by the film forming means is placed in the heated chamber. After placement, it can be sealed and depressurized (with heating if necessary) to achieve a desired pressure state.

  Further, in each chamber provided with heating means or decompression means, or in a chamber provided with heating means and decompression means, a temperature sensor that measures the temperature during heating, and the temperature measured by the temperature sensor is 50 to 200. It is preferable to further provide a temperature control means for controlling the heating means so that the temperature becomes ° C. Thereby, the space or object to be heated can be controlled to a desired temperature, and can be easily controlled to an appropriate curvature.

  Furthermore, in each chamber provided with heating means or pressure reducing means, or in a chamber provided with heating means and pressure reducing means, the pressure at the time of pressure reduction is measured separately from or together with the above temperature sensor and temperature control means. It is preferable to further provide a pressure sensor that controls the pressure reducing means so that the pressure measured by the pressure sensor is 0.1 to 100 kPa. Thereby, the space to be depressurized can be controlled to a desired pressure, and can be easily controlled to an appropriate curvature.

The above-described temperature sensor, temperature control means, pressure sensor, and pressure control means can be appropriately selected from known ones.
These temperature sensors (26) and pressure sensors (25), heating means (heater 28), pressure reducing means (pressure reducing device 27), potentiostat (17), light source not shown, humidifier (18), humidity The sensor (19), cleaning device (21), drying device (22), etc. are electrically connected to the control device (30) that controls the operation in each process such as the film forming process, film forming process, and cleaning process. (The numbers in parentheses indicate the symbols in FIG. 3), and are automatically controlled to operate. In addition, the specific manufacturing method which manufactures a microlens array by each process, such as a film formation process and a film-forming process, is demonstrated in detail in the following Example.

A specific example of the microlens array manufacturing apparatus of the present invention will be described below with reference to FIG.
The microlens array manufacturing apparatus shown in FIG. 3 includes a film formation cleaning chamber 101 that performs a film formation process and a cleaning process by a photo-deposition method, a drying chamber 102 that performs a drying process, and a molding chamber 103 that performs a molding process. Each room is partitioned and arranged so that each process can be continuously performed, and the manufacturing booth 100 is constructed. It should be noted that the film forming cleaning chamber 101, the drying chamber 102, and the molding chamber 103 in the manufacturing booth 100 are closed with a loading / unloading port for loading and unloading a film forming substrate between adjacent chambers. A door (both not shown) is provided.

  The film-forming cleaning chamber 101 includes an electrodeposition apparatus 10 that forms a microlens array layer, a cleaning apparatus 21 that removes unnecessary electrolytic solution adhering to the film-forming substrate, and a relative humidity of 50 near the film-forming substrate 5. It is comprised with the humidifier 18 and the humidity sensor 19 for keeping at% or more. The humidifier 18 and the humidity sensor 19 are connected to the control device 30, and at least a predetermined relative humidity between immediately before the film forming substrate 5 on which the microlens array layer is formed is pulled up from the electrolytic solution until the cleaning is completed. (50% or more) can be maintained.

  In addition, the electrodeposition apparatus 10 is provided with a light source (not shown) for irradiating ultraviolet rays, a second imaging optical lens 11 for sequentially imaging the received light, and a second imaging optical lens 11 provided in order from the light source toward the irradiation direction. An image forming optical system including one image forming optical lens 13, a photomask 12 provided between the first image forming optical lens 13 and the second image forming optical lens 11, and an electrolytic solution 20 are accommodated. The electrodeposition electrode 14 ', a potentiostat 17 for applying a bias voltage, and a counter electrode 15 and a saturated calomel electrode (reference electrode) 16 disposed in the stored electrolyte 20 are connected to each other. The image optical system, the photomask 12 and the potentiostat 17 are arranged outside the production booth 100, and the electrodeposition electrode 14 ′ is arranged inside the production booth 100 together with the counter electrode 15 and the saturated calomel electrode 16. Then, a light-transmitting window provided in the manufacturing booth 100 with respect to the film-forming substrate disposed in a state in which the electrodeposition electrode 14 ′ is in contact with the electrolytic solution 20 in the film-forming cleaning chamber 101. It is configured to be able to irradiate light through 105 (at least a synthetic quartz glass plate that transmits the irradiating light).

  The electrodeposition electrode 14 'contains an aqueous electrolyte solution 20 containing a film-forming material whose solubility or dispersibility in an aqueous liquid decreases due to a change in pH (hydrogen ion concentration), and a film-forming substrate in an upper opening thereof. 5 can be arranged so that the optical semiconductor thin film 3 is in contact with the electrolytic solution 20. Further, a counter electrode 15 and a saturated calomel electrode 16 are provided at the bottom of the electrodeposition electrode so as to be immersed in the electrolytic solution 20, and the counter electrode 15 and the saturated calomel electrode 16 and the conductive thin film 2 of the film forming substrate are provided. Are electrically connected to the potentiostat 17 so that a bias voltage can be appropriately applied under the control of the control device 30 as necessary.

  This imaging optical system is a projection type exposure apparatus, and light from a light source is imaged on a photomask 12 through a second imaging optical lens 11, and light patterned through the photomask 12 is further An image is formed on the surface of the optical semiconductor thin film of the film forming substrate 5 through the light transmissive window 105 through the first imaging optical lens 13.

  The film formation cleaning chamber 101 of the manufacturing booth 100 is isolated from the outside so that the relative humidity is maintained at 50% or more (preferably 70% or more) by the humidifier 18 and the humidity sensor 19 provided in the chamber. It has become. As shown in FIG. 3, the imaging optical system is disposed outside the manufacturing booth 100, and even when the booth humidity in the manufacturing booth 100 is increased, condensation or fogging occurs on the lens, resulting in a decrease in optical performance or exposure. This prevents rust and the like from being produced on precision parts used in containers, etc., resulting in problems such as equipment life, performance degradation, and equipment failure. In particular, since manufacturing equipment is expensive, the defects directly increase costs.

  The humidifier 18 and the humidity sensor 19 are connected to the control device 30, and the inside of the production booth 100 can be controlled within an appropriate relative humidity range based on the humidity measured by the humidity sensor 19. As the humidifier 18, for example, a known ultrasonic humidifier, heating humidifier, vaporizer humidifier, or the like can be appropriately selected and used. Also, instead of using a humidifier, using a cleaning fluid such as an aqueous liquid or humidified air used in the cleaning process, for example, before the film forming substrate is carried into the booth, the cleaning fluid is supplied from the cleaning nozzle into the booth. You may make it eject. This is advantageous in that the device configuration is simpler.

In addition, a cleaning device 21 is further provided inside the film cleaning chamber 101 so that it can be cleaned by being ejected substantially perpendicularly to the surface of the film forming substrate 5 on the side where the microlens array layer is formed. ing. The cleaning device 21 can eject the aqueous liquid from the ejection nozzle, and can eject humidified air or the like. Further, as shown in FIG. 3, the film forming substrate 5 is configured to be independently movable in the arrow direction B or B ′, and the cleaning device 21 is configured to be independently movable in the arrow direction A or A ′. Cleaning can be performed by fixing one of the substrate and the cleaning apparatus and moving the other, or by moving both in different directions or at different speeds in the same direction.
Further, when the aqueous liquid is ejected from the ejection nozzle, a door or partition (not shown) can be provided between the film forming process and the cleaning process, and thus the aqueous liquid for cleaning is added to the electrolytic solution 20 in this way. It is desirable to prevent contamination.

  In the manufacturing booth 100, a drying chamber 102 is installed adjacent to the film forming and cleaning chamber 101. A drying device 22 capable of blowing gas (nitrogen gas, air, etc.) from a nozzle is provided at the lower part of the drying chamber 102, and is blown to the microlens array forming surface of the cleaned film forming substrate 5. It can be dried. Similarly to the cleaning device 21, the drying device 22 can be configured to be movable.

  In addition, the production booth 100 is provided with a molding chamber 103 adjacent to the side of the drying chamber 102 where the film forming and cleaning chamber 101 is not adjacent. In the molding chamber 103, a substrate for film formation after drying is provided. The formed microlens array layer can be plastically deformed. For example, preheating is performed in advance before the film forming substrate 5 is carried in, and after the film forming substrate 5 is carried into the preheated molding chamber, the film forming substrate 5 is further heated at a predetermined temperature and reduced to a predetermined pressure. It can be made to plastically deform. It is also possible to carry it in without carrying out preheating, and then reduce the pressure and heat it.

  In the molding chamber 103 shown in FIG. 3, the film forming substrate 5 from the drying chamber 102 is arranged so that the side on which the microlens array layer 4 is formed is opposite to the direction of gravity (upper surface). In the room, a temperature sensor 26, a heater (such as a heater) 28, a pressure sensor 25, and a decompressor (such as a rotary pump) 27 are provided. The temperature sensor 26, the heater 28, the pressure sensor 25, and the decompressor 27 are each connected to the control device 30, and are adjusted to a predetermined temperature and pressure based on the temperature and pressure detected from each sensor by the control device 30. It is possible to control the heater and the decompressor. The film-forming substrate 5 can also be arranged so that the side on which the microlens array layer 4 is formed is in the direction of gravity (lower surface) as shown in FIG. You can choose.

  As described above, since the microlens array is formed by providing the heating means and the decompression means and plastically deforming, it is possible to increase the light collection efficiency of the microlens array, and the curvature can be controlled uniformly and arbitrarily. A microlens array having a shape can be easily produced. In addition, it is possible to mass-produce a microlens array having an arbitrary pattern including a complicated one or an arbitrarily controlled microlens array. According to the present invention, as in the case of manufacturing a microlens array using a photosensitive resin as in the prior art, problems such as the necessity of coating with a precise film thickness on the substrate and alkaline waste liquid are eliminated. In addition, a complicated process including a photolithography method is unnecessary, and the burden on the environment can be reduced.

EXAMPLES Hereinafter, although an Example demonstrates this invention in detail, this invention is not limited to these Examples.
(Example 1)
-Production of substrate for film formation-
First, a conductive thin film made of ITO is formed to a thickness of 75 nm by RF sputtering on a non-alkali glass substrate (7059 glass) having a thickness of 0.4 mm, and an anatase-type titanium oxide thin film having a thickness of 110 nm is further formed on the film. As shown in FIG. 1, a film-forming substrate 5 in which an ITO film 2 and a titanium oxide thin film 3 were sequentially laminated on a glass substrate 1 was obtained.

-Preparation of electrolyte solution-
Next, rutile type titanium oxide fine particles (particle size 10 nm, refractive index 2.7) and styrene-acrylic acid copolymer (molecular weight 13,000, hydrophobic group (hydrophilic group + hydrophobic group) molar ratio 65%, acid 150) was added at a volume ratio of 1: 5, and 5% by mass of ethylene glycol was further added thereto. Then, tetramethylammonium hydroxide and ammonium chloride were further used to adjust the pH to 7.8 and the conductivity to 6 mS / cm. Thus, an electrolyte solution that is an aqueous dispersion (solid content: 10% by mass) containing transparent fine particles was prepared.

-Preparation of microlens array manufacturing equipment-
As a microlens array manufacturing apparatus, an apparatus (manufacturing booth 100) having the same configuration as that shown in FIG. This apparatus is a projection type exposure apparatus (focusing distance between the imaging optical lens 13 and the imaging surface (exposed surface of the titanium oxide thin film 3) = 100 mm, the focal depth is ± 50 μm, and the light intensity is 365 nm as the imaging optical system. 100 mW / cm ² ; manufactured by Ushio Electric Co., Ltd.), and the liquid contact of the titanium oxide thin film 3 of the film forming substrate 5 arranged so that the titanium oxide thin film 3 is in contact with the electrolytic solution as shown in FIG. A microlens array layer can be formed on the surface. In the projection type exposure apparatus, a first imaging optical lens 13, a photomask 12, a second imaging optical lens 11, and a light source (not shown) are arranged in order from the film forming substrate 5.

  In this apparatus, the film forming substrate 5 is connected to a potentiostat (voltage applying means) 17 through the ITO film 2, and the potentiostat 17 is also connected to a saturated calomel electrode (reference electrode) 16 and a counter electrode 15. The film forming substrate 5 (titanium oxide thin film 3) is used as a working electrode for the counter electrode (platinum electrode) 15. The prepared electrolytic solution 20 is accommodated in the electrodeposition electrode 14 '. Further, the photomask 12 is formed such that black micro dots are formed in a circular light transmission portion so as to increase in density from the central portion toward the peripheral edge of the circle so that a predetermined microlens is formed. Light-transmitting gradation).

-Formation of microlens array-
(Film formation process)
The film forming process was performed in the film forming cleaning chamber 101 as follows.
First, the titanium oxide thin film 3 is used as a working electrode with respect to the saturated calomel electrode 16, a voltage is applied from the potentiostat 17 so that the bias voltage applied to the working electrode is 1.8 V, and the back surface of the film forming substrate 5. From the side (side on which the titanium oxide thin film 3 of the film forming substrate is not provided), ultraviolet rays were irradiated for 30 seconds so that the pattern light was imaged on the liquid contact surface of the titanium oxide thin film 3. At this time, the microlens array layer 4 was formed on the surface of the titanium oxide thin film 3. Subsequently, when the film-forming substrate 5 is separated from the electrolytic solution, unnecessary electrolytic solution adheres to the periphery of the microlens array layer 4 and the surface (electrodeposited surface) of the titanium oxide thin film 3 on which the layer is formed. Therefore, the film-forming substrate 5 was transported to the cleaning process in which the cleaning apparatus was installed in the same room while the electrodeposition surface was in a substantially horizontal state in which the electrodeposition surface was in the direction of gravity (lower surface).

(Washing process)
The film-forming substrate 5 was disposed so that the ejection port of the ejection nozzle of the cleaning device 21 disposed in the lower right portion of the film-forming cleaning chamber 101 and the electrodeposition surface of the film-forming substrate 5 face each other. The film forming substrate 5 is held by a holding mechanism connected to a moving mechanism (not shown), can move in the direction of arrow B or B ′, and the cleaning device 21 can move in the direction of arrow A or A ′. The nozzle shape of the ejection nozzle is configured as a slit. The outlet of the ejection nozzle is directed upward so as to face the electrodeposition surface, and the ejection direction of pure water is substantially parallel to the normal direction of the electrodeposition surface of the film forming substrate 5 arranged substantially horizontally. The film was ejected in the form of a curtain film, and the film-forming substrate 5 and the ejection nozzle were moved in 10 directions reciprocally in opposite directions at a constant speed of 100 m / sec. At this time, the striking pressure of pure water on the electrodeposition surface was adjusted to 2 KPa so that the profile of the microlens array layer did not collapse as much as possible.

  As a result of the cleaning as described above, the electrolytic solution adhering to the electrodeposition surface of the film-forming substrate 5 is uniformly removed, and a radius of curvature of 20 μm (refractive index 1.65, focal length 31 μm) is selected on the electrodeposition surface. It was confirmed that the microlens array layer 4 was formed. Further, there was no residue in which the electrolytic solution could be adhered to the region where the microlens array layer on the electrodeposited surface was not formed and the outer edge portion, and it was possible to perform the cleaning well.

(Drying process)
After cleaning, the film forming substrate 5 is taken out from the film forming and cleaning chamber 101, the film forming substrate 5 is carried into the drying chamber 102 with the electrodeposition surface facing in the direction of gravity, and the ejection of the drying device 22 provided at the lower portion of the drying chamber. The film forming substrate 5 was disposed so that the nozzle and the electrodeposition surface of the film forming substrate 5 face each other. Then, nitrogen was blown onto the electrodeposition surface from the ejection nozzle, and drying was performed so as to blow off water droplets. In addition, it was possible to perform the drying here using clean air.

(Molding process)
The dried film forming substrate 5 is unloaded from the drying chamber 102, and then loaded into the drying chamber 103 so that the electrodeposition surface on which the microlens array layer 4 is formed is opposite to the direction of gravity (upper surface). did. The molding chamber 103 was preliminarily heated in advance so that it was around 100 ° C. at the time of loading. In the molding chamber 103, the film-forming substrate 5 is disposed substantially horizontally with the electrodeposition surface on which the microlens array layer 4 is formed as an upper surface, and is heated at 100 ° C. for 5 minutes while maintaining a substantially horizontal state, and further 10 kPa. The pressure was reduced. Thereafter, the film forming substrate 5 was carried out of the molding chamber 103 and cooled to room temperature.

  As described above, the microlens array 4 ′ formed by plastic deformation of the microlens array layer 4 is formed on the film forming substrate 5. The radius of curvature of the formed microlens array 4 ′ is 51 μm. (Refractive index 1.65, focal length 78 μm). In this way, a microlens array having a desired curvature could be produced on the titanium oxide thin film of the film forming substrate.

(Example 2)
In Example 1, the film forming substrate 5 was carried into the molding chamber 103 of the production booth 100 so that the electrodeposition surface thereof was in the direction of gravity (bottom surface) (see FIG. 4) and was plastically deformed. A microlens array was prepared in the same manner as in Example 1.
Specifically, it is as follows. The electrodeposition surface on which the microlens array layer 4 of the film-forming substrate 5 is formed when the film-forming substrate 5 is transported to the molding chamber 103 and oriented in the direction of being unloaded from the drying chamber 102, that is, substantially horizontal. It arrange | positioned in a molding chamber so that it might become a gravitational direction (lower surface), and it heated for 5 minutes similarly to Example 1, and reduced pressure to 10 kPa, and was set as the microlens array. The curvature radius of the formed microlens array was 15 μm (refractive index 1.65, focal length 23 μm).

(Comparative Example 1)
In Example 2, a microlens array was produced in the same manner as in Example 2 except that the inside of the molding chamber 103 of the production booth 100 was preheated to 45 ° C. and further heated at 45 ° C. for 15 minutes. The curvature radius of the microlens array obtained here was 20 μm (refractive index 1.65, focal length 31 μm), and plastic deformation was not achieved under these conditions.

(Comparative Example 2)
In Example 2, a microlens array was produced in the same manner as in Example 2 except that the pressure in the molding chamber 103 of the production booth 100 was not reduced. However, plastic deformation was not achieved under normal pressure conditions.

It is a schematic sectional drawing which shows the structural example of the board | substrate for film formation which concerns on this invention. It is a schematic sectional drawing which shows the structural example of the electrodeposition apparatus which comprises the manufacturing apparatus of the microlens array of this invention, and forms a microlens array layer in a selection area | region by the photodeposition method. It is a schematic block diagram which shows an example of the manufacturing apparatus of the micro lens array of this invention. It is a schematic block diagram which shows the other example of the molding chamber which comprises the manufacturing apparatus of the micro lens array of this invention.

Explanation of symbols

1 ... Glass substrate (insulating substrate)
2 ... ITO film (conductive thin film)
3. Titanium oxide thin film (photo semiconductor thin film)
4 ... microlens array layer 4 '... microlens array 5 ... film forming substrate 10 ... electrodeposition apparatus (film forming means)
DESCRIPTION OF SYMBOLS 20 ... Water-system electrolyte solution 25 ... Pressure sensor 26 ... Temperature sensor 27 ... Depressurizer 28 ... Heater 30 ... Control apparatus (temperature control means, pressure control means)

Claims (6)

An aqueous electrolyte containing a film-forming material whose solubility or dispersibility in aqueous liquids decreases due to a change in pH, an electrically conductive thin film and an optical semiconductor thin film having a photovoltaic function on an insulating substrate sequentially from the substrate side A voltage is applied between the selected region and the counter electrode by irradiating the selected region of the optical semiconductor thin film with light in a state where the provided film forming substrate is arranged so that the optical semiconductor thin film is in contact therewith, Forming a microlens array layer by depositing the film forming material in the selected region; and
A molding step of heating the formed microlens array layer to 50 to 200 ° C. and plastically deforming under a reduced pressure of 0.1 to 100 kPa,
A method of manufacturing a microlens array having An aqueous electrolytic solution containing a film-forming material whose solubility or dispersibility in aqueous liquid decreases due to a change in pH, an electrically conductive thin film on an insulating substrate, and an optical semiconductor thin film having a photovoltaic function in contact with the electrically conductive thin film Are disposed in order from the substrate side, and the conductive thin film is disposed so that at least the photo-semiconductor thin film is in contact with the aqueous electrolytic solution and the conductive thin film is in contact with the aqueous electrolytic solution. A film forming step of forming a microlens array layer by depositing the film forming material in the selected region by irradiating the selected region of the optical semiconductor thin film with light in
A molding step of heating the formed microlens array layer to 50 to 200 ° C. and plastically deforming under a reduced pressure of 0.1 to 100 kPa,
A method of manufacturing a microlens array having An aqueous electrolyte containing a film-forming material whose solubility or dispersibility in aqueous liquids decreases due to a change in pH, an electrically conductive thin film and an optical semiconductor thin film having a photovoltaic function on an insulating substrate sequentially from the substrate side A voltage is applied between the selected region and the counter electrode by irradiating light to the selected region of the optical semiconductor thin film in a state where the provided film forming substrate is arranged so that the optical semiconductor thin film is in contact with the substrate, Film forming means for forming a microlens array layer by depositing the film forming material in a selected region;
Heating means for heating the microlens array layer to 50 to 200 ° C .;
Pressure reducing means for reducing the pressure of the microlens array layer to 0.1 to 100 kPa and plastically deforming;
A microlens array manufacturing apparatus comprising: An aqueous electrolytic solution containing a film-forming material whose solubility or dispersibility in aqueous liquid decreases due to a change in pH, an electrically conductive thin film on an insulating substrate, and an optical semiconductor thin film having a photovoltaic function in contact with the electrically conductive thin film Are disposed in order from the substrate side, and the conductive thin film is disposed so that at least the photo-semiconductor thin film is in contact with the aqueous electrolytic solution and the conductive thin film is in contact with the aqueous electrolytic solution. Film forming means for forming a microlens array layer by depositing the film forming material in the selected region by irradiating the selected region of the optical semiconductor thin film with light applied to
Heating means for heating the microlens array layer to 50 to 200 ° C .;
Pressure reducing means for reducing the pressure of the microlens array layer to 0.1 to 100 kPa and plastically deforming;
A microlens array manufacturing apparatus comprising:   The temperature sensor which measures the temperature at the time of a heating, The temperature control means which controls the said heating means so that the temperature measured with the said temperature sensor may be 50-200 degreeC was further provided. Microlens array manufacturing equipment.   The pressure sensor which measures the pressure at the time of pressure reduction, The pressure control means which controls the said pressure reduction means so that the pressure measured with the said pressure sensor may be 0.1-100 kPa, The further provided of Claims 3-5 The microlens array manufacturing apparatus according to any one of the preceding claims.

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