JP2000241607A - Forming method for microlens array and microlens array - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a forming method for a microlens array excellent in optical characteristic and having desired optical characteristics. SOLUTION: This method for forming a microlens array comprises the processes of: forming a transfer layer 20 having on the substrate 10; plural fine transfer recessess to be transferred to a substrate 10; continuing the process of removing the whole surface from the surface side of the transfer layer 20 substantially uniformity while keeping the surface shape until the transfer layer 20 is eliminated and transferring the transfer recessess 30 of the transfer layer 20 to the substrate 10 to form micro-recessed parts 31 on the substrate 10; and filling the micro-recessed parts with a filling material having a refractive index higher than that of the substrate 10 to form a lens part 32.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for forming a microlens array and a microlens array.

[0002]

2. Description of the Related Art A microlens array is an array of minute lenses having a size of several hundreds of micrometers or less in a one-dimensional or two-dimensional array, and is widely known in the field of optoelectronics. For example, if a microlens array corresponding to each pixel of the liquid crystal element is used, light blocked by the black matrix can be focused on each pixel,
Light use efficiency can be improved. (NIKKEI
MICRODEVICES, (12) 129, (19
91), Tadashi Aoki, National Technical Report, 36, (3)
Jun. 116 (1990)). In addition, when a microlens array is used at the joint between the optical fiber and the light receiving element arranged in an array, the light receiving efficiency can be improved.

[0003] Such a microlens array forms a micro-convex lens on a substrate. The microlens array is formed by contacting a substrate containing ions with another ion source and distributing a refractive index generated by ion exchange. A refractive index distribution type microlens array that produces an effect, a structure in which a minute concave shape is formed on a substrate, and a filling material having a higher refractive index than the substrate is filled in the concave shape to form a convex lens have been proposed. I have.

In a structure in which a convex lens is formed by forming a minute concave shape on a substrate and filling the concave with a filler having a higher refractive index than the substrate, the surface itself of the obtained microlens array can be formed flat, so that the reflection can be obtained. It has an advantage that it can be easily combined with an optical element such as a prevention film, an interference filter, and a pinhole and bonded with a liquid crystal element, which is extremely advantageous in manufacturing.

As a method of forming a microlens array in which a minute concave shape is formed on a substrate and the concave portion is filled with a high refractive index substance to form a convex lens, a method by wet etching is known. In this method, an etching mask having minute openings is formed on a substrate such as glass, immersed in an etching solution such as hydrofluoric acid, and isotropic wet etching is performed with the etching solution from the minute openings to form a substrate such as glass. In this method, a hemispherical concave shape is formed, and then the etching mask is removed, and the concave portion is filled with a filling material having a higher refractive index than the substrate. In addition, as the filler, organic substances such as polycarbonate and acrylic styrene copolymer resin are generally known.

[0006]

However, in the method of forming a microlens array by wet etching, the shape of the microlens that can be formed for isotropic etching is determined by the size of the minute opening, and the shape of the microlens is arbitrary. The formation of a microlens array is extremely difficult. Further, the substrate to be used needs to be able to be etched by the etching solution, and only a limited material such as quartz glass can be used for the substrate.

The present invention has been made in view of the above-described problems of the microlens array forming method and the microlens array. A microlens array having an arbitrary shape can be formed, and the material of the substrate to be used is arbitrary. An object of the present invention is to provide a method of forming a microlens array from which materials can be selected and a microlens array excellent in optical characteristics.

[0008]

According to a first aspect of the present invention, there is provided a concave portion forming step of forming a plurality of minute concave portions on a transparent substrate, and a concave portion forming step. Forming a lens portion by filling the concave portion with a filling substance having a higher refractive index than the refractive index of the substrate, wherein the concave portion forming step includes a plurality of minute transfer concave portions. A transfer layer forming a transfer layer having a shape on the substrate; and a transfer step of transferring a shape of the transfer layer to the substrate to form a plurality of minute concave portions on the substrate. This is a method for forming a microlens array.

According to a second aspect, in the method of forming a microlens array according to the first aspect, the transfer layer forming step includes forming a transfer material layer constituting the transfer layer on the substrate, Forming a resist mask in which fine openings corresponding to the arrangement of the microlens array are formed on the layer, and performing etching through the resist mask to form a plurality of minute transfer concave shapes in the transfer material layer. And obtaining a transfer layer by performing a method of forming a microlens array.

According to a third aspect of the present invention, in the method of forming a microlens array according to the first aspect, the transfer layer forming step includes forming a wall on the substrate corresponding to the arrangement of the microlens array, A method for forming a microlens array, comprising a step of supplying a liquid material between the wall-like materials to form a transfer layer having a concave shape for transfer.

According to a fourth aspect of the present invention, in the method of forming a microlens array according to the first aspect, the step of forming a transfer layer includes forming a photosensitive resin layer on the substrate and forming a micro resin layer on the photosensitive resin layer. Using a photomask on which a pattern corresponding to the lens array shape is formed, by exposing and developing the photomask and the photosensitive resin layer at a distance of 20 μm or more, a plurality of minute transfer concave shapes are formed. A method for forming a microlens array, comprising a step of forming a transfer layer.

According to a fifth aspect of the present invention, in the method of forming a microlens array according to the first aspect, in the step of forming a transfer layer, a photosensitive resin layer is formed on the substrate, and a micro resin layer is formed on the photosensitive resin layer. A microlens array including a step of forming a transfer layer having a plurality of minute transfer concave shapes by exposing and developing using a gradation mask in which a pattern corresponding to the lens array shape is formed. Is a method of forming

A sixth invention is a method of forming a microlens array according to the fifth invention, wherein the gradation mask is formed of minute dots.

According to a seventh aspect, in the method of forming a microlens array according to any one of the first to sixth aspects, the transfer step of transferring the shape of the transfer layer to the substrate is performed by dry etching. This is a method for forming a characteristic microlens array.

According to an eighth aspect, in the method of forming a microlens array according to the seventh aspect, the dry etching rate in the transfer step is different between the dry etching rate of the substrate and the dry etching rate of the transfer layer. This is a method for forming a microlens array.

According to a ninth aspect of the present invention, in the method of forming a microlens array according to any one of the first to eighth aspects, the substrate comprises a concave portion forming substrate for forming a plurality of minute concave portions; A method for forming a microlens array according to any one of claims 1 to 8, further comprising a supporting substrate for supporting the portion forming substrate.

A tenth invention is a microlens array formed by the method of forming a microlens array according to any one of the first to tenth inventions.

[0018]

FIG. 1 is an explanatory diagram of a method for forming a microlens array according to an embodiment of the present invention. The method for forming a microlens array according to this embodiment includes (1) a transfer layer forming step of forming a transfer layer having a shape of a plurality of minute concave portions transferred onto the substrate (FIG. 1A )), (2) a transfer step of transferring the shape of the transfer layer to a substrate to form a plurality of minute concave portions on the substrate (see FIG. 1B), and (3) a transfer step of forming the transfer layer. Forming a lens portion by filling the formed concave portion with a filler having a refractive index higher than the refractive index of the substrate (see FIGS. 1C and 1D). Less than,
A method for forming a microlens array according to the embodiment will be described with reference to FIG.

(1) Transfer Layer Forming Step In this step, a transfer layer 20 having a plurality of minute concave concave spherical shapes 30 for transfer to the substrate 10 is formed on the substrate 10. This is a transfer layer forming step.

Here, the substrate 10 needs to be transparent to the wavelength used for the microlens array.
₂ 0 ₃ substrate made of a substrate and a metal oxide of MgO substrate,
Ceramic substrates such as SiC, SiN, MgF, etc., silicon substrates and GaAs substrates, various glass substrates such as quartz glass and alumina silicate glass, plastic substrates such as polyethylene terephthalate (PET), polycarbonate, polyurethane and epoxy resin, or composite substrates thereof Are appropriately selected.

The transfer layer 20 has a transfer material layer 2 on the substrate 10.
1 (see FIG. 2), and a transfer concave shape 30 is formed in the transfer material layer 21. Transfer material layer 21
Are organic polymers such as polyethylene terephthalate (PET), polycarbonate, polyurethane, epoxy resin, polyimide, polyimide precursor, and water-soluble polymers such as polypinyl alcohol and hydroxyethyl cellulose, which can form the transfer concave shape 30; Is appropriately selected. Further, Al ₂ 0 ₃ or metal oxides such as MgO, ceramics such as SiC or SiN, silicon,
Various glasses such as quartz glass and alumina silicate glass can also be used.

The transfer material layer 21 may be formed on the entire surface of the substrate 10 or may be formed partially on a portion where a microlens array is to be formed. As a method for forming the transfer material layer 21, a known method such as screen printing, spin coating, vacuum evaporation, sputtering, or CVD is used. The thickness of the transfer material layer 21 to be formed is appropriately determined depending on the desired shape of the microlens array, but is preferably about 0.05 μm to 100 μm.

The method of forming the transfer concave shape 30 may be a method of forming by machining, a method of forming the transfer layer using a press having a convex shape by pressing or heating and pressing, and a method of forming a photocurable resin. A method in which a photo-curable resin is cured by pressing and light irradiation using a press die having a convex shape placed on a substrate, a method of forming by injection molding using an injection mold having a convex shape, or A method of forming the resist by etching using a resist mask having a minute opening or the like is used. In particular, a method of forming by etching using a resist mask having a minute opening is an excellent method capable of efficiently forming a high-definition spherical transfer concave shape compared to other methods.

FIG. 2 is an explanatory view of a method of forming the transfer concave shape 30 by etching using a resist mask having a minute opening. In this method, first, the substrate 10
A transfer material layer 21 is formed thereon. Next, a resist mask 2 provided with minute openings 3 corresponding to the arrangement of the microlens array is formed on the transfer material layer 21 (FIG. 2A).
reference). Next, wet etching or dry etching is performed using the resist mask 2 as a mask to form a transfer concave shape 30 (see FIG. 2B). Then
The resist mask 2 is removed to obtain a substrate having the transfer layer 20 formed on the substrate 10 (see FIG. 2C).

Here, the resist mask 2 is appropriately selected from a material which is not affected by the process of forming a minute transfer concave spherical shape on the transfer layer through the minute opening 3.
Metals such as W and Ta, ITO, MgO and Al ₂ O ₃
And the like, and organic compounds such as epoxy resins and novolak resins. The shape of the minute opening 3 is formed corresponding to the desired arrangement of the microlens array, and the size of the opening must be the same as or smaller than the diameter of the desired microlens. .

The method of forming the fine opening 3 is a method of forming the resist mask 2 at a portion other than the fine opening 3 by printing such as screen printing or intaglio printing using an ink capable of forming the resist mask 2. A method of forming a material for forming the resist mask 2 on the entire upper surface and forming the minute openings 3 using a photolithography process, and forming a resist mask 3 on the entire surface after masking a portion where the minute openings 3 are to be formed in advance. A method of forming a material and removing the masked portion to form the minute opening 3 is used.

In the wet etching performed through the minute openings 3, the transfer material layer 21 is etched, but the resist mask 2 is not etched. This is performed by etching.

In this case, the etching solution may be an aqueous solution of hydrofluoric acid, an aqueous solution of sulfuric acid, an aqueous solution of nitric acid, an aqueous solution of hydrochloric acid or a mixed solution of these aqueous acid solutions, an aqueous solution of sodium carbonate, an aqueous solution of potassium hydroxide, an aqueous solution of sodium hydroxide, hydrazine. Or an alkaline solution of an amine compound or an organic solvent such as acetone or butyl acetate.

In the dry etching performed through the minute openings 3, the transfer material layer 21 is etched and the resist layer 2 is processed in a gas layer containing an etching gas that does not etch the resist mask 2. A step of partially etching isotropically is performed. The etching gas in the gas layer at this time is CF ₄ , CHF ₃ , SF ₆ , N
A plasma reactive gas containing components such as F ₃ and Cl ₂ is preferred.

The method of removing the resist mask 2 is appropriately selected depending on the material constituting the resist mask 2, and the resist mask 2 is removed using an acid aqueous solution, an alkaline solution or an organic solvent.
Mask 2 by dissolution and dry etching
Is used. Further, the resist mask 2 does not always need to be removed, and if the resist mask 2 does not affect the optical path of the microlens array, the removal step is unnecessary.

FIG. 3 shows a transfer layer 20 having a concave shape for transfer.
FIG. 4 is an explanatory view of another method of forming a hologram. In the method shown in FIG. 3, the wall-shaped objects 5 are formed on the substrate 10 corresponding to the arrangement of the microlens array (see FIG. 3A), and the liquid material 51 is interposed at least between the wall-shaped objects 5. Is supplied, and the liquid material is dried to form the transfer layer 20 having the concave shape 30 for transfer.

In FIG. 3A, the wall-like objects 5 are formed corresponding to the arrangement of the microlens array, and the shape thereof is 4.
It is formed and arranged on the substrate 10 in a polygonal shape such as a rectangular shape, a hexagonal shape, an octagonal shape, or a circular shape.

The wall 5 is made of polyethylene terephthalate (PET), polycarbonate, polyurethane, epoxy resin, polyimide, polyimide precursor, organic polymer such as water-soluble polymer such as polypinyl alcohol and hydroxyethyl cellulose, or the like. A composite material is appropriately selected. Further, Al ₂ 0 ₃ or metal oxides such as MgO,
It is also possible to use ceramics such as SiC and SiN, various kinds of glass such as silicon, quartz glass and alumina silicate glass, and the like.

The method of forming the wall-like material 5 includes a method of forming the wall-like material 5 by printing such as screen printing or intaglio printing using an ink capable of forming the wall-like material 5, and a material for forming the wall-like material 5 on the entire surface of the substrate 10. A method of forming the wall-shaped material 5 using a photolithography process, forming a material for forming the wall-shaped material 5 on the entire surface after masking a portion where the wall-shaped material 5 is formed, and removing the masked portion. For example, a method of forming the wall-shaped object 5 is used.

The liquid material 5 is obtained by dissolving a nonvolatile material in a volatile solution, and a sol-gel solution or a solution in which an organic polymer is dissolved in a solvent is effective.

As a method of supplying the liquid material 51 into the wall-like material 5, a method of applying the liquid material on the upper surface of the substrate 10 can be used. As a method of applying the liquid material on the upper surface of the substrate 10, a method such as screen printing, curtain coating, dipping, or spin coating is preferable. By applying and drying the liquid material, a spherical or aspherical concave shape is formed on the wall surface of the wall 5 by the surface tension of the liquid material. In this case, some liquid material 51 may remain on the wall-shaped material 5.

After the wall 5 corresponding to the arrangement of the microlens array is formed on the substrate 10, the liquid 5
By applying a method of forming a minute transfer concave shape by applying and drying the transfer concave shape 1, the transfer concave shape 30 can be formed without using a press die having a convex shape. The shape can be formed efficiently.

FIG. 4 shows a transfer layer 20 having a concave shape for transfer.
FIG. 11 is an explanatory view of still another method of forming a hologram. The method shown in FIG. 4 uses a photomask 8 in which a fine pattern corresponding to the arrangement and shape of a microlens array is formed on a substrate 10 on which a photosensitive resin layer 7 as a transfer material layer is formed.
3 is placed at an interval of 20 μm or more from the surface of the substrate 10, exposed, and developed to obtain the transfer layer 20 having the transfer concave shape 30.

As the photosensitive resin 7, a known photosensitive resin used in a printed circuit board, a semiconductor manufacturing process or the like can be used.
Known methods such as screen printing, curtain coating, dipping, and spin coating are also used for the method of forming the substrate 10. The photomask 83 is formed by forming a light-transmitting portion and a light-shielding portion on a transparent support such as glass or plastic. When a photodegradable photosensitive resin is used as the photosensitive resin layer 7, the photomask 83 is used for transfer. When a photomask that transmits light is used for a portion where the concave shape 30 is formed and a photopolymerizable photosensitive resin is used, it is necessary to use a photomask that does not transmit light for a portion where the concave shape 30 for transfer is formed. .

Here, the photosensitive resin layer 7 and the photomask 8
By setting the interval of 3 to 20 μm or more, transmitted light is diffracted, and a difference in light amount occurs between the central portion and the peripheral portion forming the microlens. Forming the photosensitive resin layer as described above
By developing the photosensitive resin layer 7 exposed at an interval of 0 μm or more with a developing solution, the transfer concave shape 30 is obtained.

Here, the photosensitive resin layer 7 and the photomask 8
The interval of 3 needs to be 20 μm or more. However, if the interval is too wide, the amount of diffracted light increases and the transfer concave shape 30 cannot be formed. This interval depends on the exposure apparatus used, but is preferably 200 μm or less. According to this method, since the transfer concave shape 30 can be formed without using a convex press die or the like, a high-definition transfer concave shape can be efficiently formed.

FIG. 5 shows a transfer layer 20 having a concave shape for transfer.
FIG. 11 is an explanatory view of still another method of forming a hologram. The method shown in FIG. 5 uses a gradation mask 84 in which a fine pattern corresponding to the arrangement and shape of a microlens array is formed on a substrate 10 on which a photosensitive resin layer 7 as a transfer material layer is formed.
Is placed on the surface of the substrate 10 (see FIG. 5A), exposed, and developed to obtain a transfer layer 20 having a transfer concave shape 30 (see FIG. 5B). is there.

As the photosensitive resin 7, a known photosensitive resin used in a printed circuit board or a semiconductor manufacturing process can be used, and the method of forming the substrate 10 can be a known method such as screen printing, curtain coating, dipping, or spin coating. Is used.

The gradation mask 84 is formed by forming a light transmitting part and a light shielding part on a transparent support such as glass or plastic, and as shown in FIG. 5C, each micro lens of the micro lens array is formed. Is a configuration in which the light transmission amount changes stepwise. Here, the gradation mask for changing the light transmittance stepwise is Cr which forms the light shielding portion.
And the like, in which the thickness of the material is changed and the transmission amount is changed stepwise, and the material in which the light transmission amount is different is sequentially formed.

Further, as a more preferable gradation mask, minute dots having a resolution equal to or less than the resolution of the photosensitive resin 7 are used.
A configuration is effective in which the density at which the minute dots are formed is sequentially changed, and the light transmission amount is changed stepwise.

The gradation mask 84 is formed of the photosensitive resin layer 7.
When a photo-decomposable photosensitive resin is used, a photomask that allows light to be transmitted in a stepwise manner at a portion where the transfer spherical concave shape 34 is formed is used. When a photopolymerizable photosensitive resin is used, a transfer mask is used. It is necessary to use a gradation mask that does not transmit light stepwise in the portion where the concave shape 30 is formed.

As described above, the transfer concave shape 30 is obtained by forming the photosensitive resin layer 7 and developing the photosensitive resin layer 7 exposed using the gradation mask 84 with the developing solution.

In this case, by using the gradation mask 84, the light transmission amount changes stepwise, the development amount of the photosensitive resin layer 7 changes stepwise, and the transfer concave shape 30 is obtained. Further, by controlling the change in the light transmission amount of the gradation mask 84, the shape of the transfer concave shape 30 can be spherical or aspherical.

The above-described method using a gradation mask has an advantage that the transfer concave shape 30 can be formed with high precision and efficiency without using a press die having a convex shape, and also, the transfer concave shape is formed as a transfer concave shape. In addition to the spherical shape, there is an excellent advantage that an aspherical shape can be easily and efficiently formed.

(2) Transfer Step In this step, the shape of the transfer layer 20 formed in the above-described transfer layer forming step is transferred to the substrate 10 and a plurality of minute concave portions 31 are formed on the substrate (see FIG. 1B). ) Is formed. Here, as a method of transferring the transfer concave shape 30 to the substrate 10, an etching method, a sandblast method, or
A method by ion milling or the like is possible.

As a method used in this transfer step, in particular, if a dry etching method is used, a plurality of minute concave portions 31 can be formed on the substrate 10 accurately and efficiently. Among dry etching, CF ₄ , CHF ₃ , S
Reactive ion etching using a reactive gas such as F ₆ , NF ₃ or Cl ₂ is preferable. In this case, when etching is performed under the condition that the dry etching rate of the transfer concave shape 30 and the dry etching rate of the substrate 10 are different, a minute concave portion 31 amplifying the shape of the transfer concave shape 30 can be formed. It is possible to control the optical properties of the array.

More specifically, when the dry etching rate of the substrate 10 is twice as fast as the dry etching rate of the transfer concave shape 30, the depth of the minute concave portion 31 formed on the substrate 10 becomes , Which is twice the depth of the transfer concave shape 30. In addition, when the dry etching rate of the substrate 10 is 0.5 times the dry etching rate of the transfer concave shape 30, the depth of the minute concave portion 31 formed on the substrate 10 is equal to the transfer concave shape 30. 0.5 times the depth of

When the ratio between the dry etching rate of the transfer concave shape 30 and the dry etching rate of the substrate 10 is changed in the dry etching step, a minute concave portion 31 having an aspherical curvature is obtained, and the aspherical shape is obtained. A microlens array can be formed, and optical characteristics of the microlens array can be controlled.

Here, the dry etching rate of the transfer concave shape 30 and the dry etching rate of the substrate 10 can be changed by a combination of the material of the substrate 10 to be used and the material of the transfer layer 20. Further, it can be changed depending on the dry etching conditions such as the dry etching method and the type of gas used.

(3) Lens Part Forming Step In this step, a plurality of minute concave parts 31 formed in the concave part forming step are filled with a filling material having a refractive index higher than the refractive index of the substrate 10. Lens section 32
To form a microlens array.

The filling material having a higher refractive index than the substrate 10 needs to be small in scattering and transparent with respect to the wavelength used for the microlens array, and must be transparent such as polyethylene terephthalate (PET), polycarbonate, polyurethane or epoxy resin. Plastic or a composite material thereof is appropriately selected. In particular, an organic substance containing S in the molecular chain has a high refractive index and is effective.

The method of filling the concave portion 31 with a filling material having a higher refractive index than the substrate 10 is appropriately selected according to the characteristics of the filling material to be used. And a method of polymerizing with heat or light is used. After the lens portion 32 is formed, it is preferable that the formed surface is polished to be flat.

As shown in FIG. 1C, the filling material is filled only in the recess 31 of the substrate 10 as shown in FIG. 1C.
As shown in (D), at the same time as the filling material is filled in the concave portion 31, the filling material is also applied on the surface of the substrate 10,
The flat portion 33 made of the filling material may be formed.

As shown in FIG. 6, it is preferable to attach a support substrate 11 to the back surface of the substrate 10 in order to reinforce the mechanical strength of the substrate 10. According to this, since the material of the substrate 10 can be selected only by considering the ease of forming the concave portion 31 without being restricted by the mechanical strength, a more appropriate material can be selected. Becomes In this case, the substrate 10 and the support substrate 11 need to be transparent to the light to be used, and the substrate 10
Preferably, an organic polymer material such as a resin which can easily form is used, and the support substrate 11 is preferably made of ceramic or glass having high mechanical strength.

The microlens array formed by the above-described method of forming a microlens array has high precision, excellent optical characteristics, and can form a flat microlens array, and can be integrated with other optical elements. Easy. The method for forming a microlens array and the microlens array according to the present invention are not limited to a microlens array formed on a liquid crystal element and a microlens array used for a joint between an optical fiber and a light receiving element. It can also be used in the field of optoelectronics such as a condenser lens for an optical pickup such as a disk, a coupling element of a one-dimensional image sensor or an LED printer, and the like.

Next, the present invention will be described in more detail with reference to examples. (Embodiment 1) FIG. 7 is an explanatory view of a method of forming a microlens array according to Embodiment 1 of the present invention. Hereinafter, the first embodiment will be described with reference to FIG.

A non-alkali glass having a thickness of 1.1 mm (NA
40: A polyimide precursor (trade name: Semicofine 811 manufactured by Toray Industries, Inc.) is applied as a transfer layer 20 on a substrate 10 made of HOYA Corporation, and a photoresist (trade name) constituting a resist mask 2 is applied thereon. : AZ13
50; Clariant Japan Co., Ltd.), exposed using a photomask for forming fine openings, and developed with an alkaline developer to form fine openings 3,
A part of the transfer layer 20 of the polyimide precursor was dissolved in the alkali developing solution through the minute openings 3 to form the transfer concave shape 30 in the transfer layer 20 (FIG. 7).
(A)).

In this case, the arrangement of the minute openings 3 is 80 μm.
They were arranged in a grid pattern within a 40 mm square with m pitches, and the depth of the formed transfer concave shape 30 was 1 μm.
Next, the resist mask 3 was dissolved and removed using butyl acetate to obtain the substrate 10 having the transfer layer 20 on which the minute transfer concave shape 30 having a depth of 1 μm was formed (see FIG. 7B).

Next, the entire surface of the transfer layer 20 on which the transfer concave shape 30 is formed is ground with a sandblasting device using a SiC abrasive having an average particle diameter of 20 μm, and the transfer concave shape 30 is stored. The grinding is continued until the transfer layer 20 is exhausted.
The transfer concave shape 30 is transferred to the substrate 10 and
Then, a number of minute concave portions 31 having a depth of 1.5 μm were formed (see FIG. 7C).

Next, a polysulfone (for example, UDEL P-1700 (trade name of Amoco Performance Products) or the like) which is a filling substance made of a substance having a higher refractive index than the substrate 10 is applied to the surface of the substrate 10 where the concave portion 31 is formed. ) Was applied and heated and fused at 200 ° C., and after cooling, the formed surface was polished to obtain a microlens array shown in FIG. 7D.

The microlens array described above was a very good microlens array with a variation in focal length of ± 18%.

(Embodiment 2) FIG. 8 is an explanatory view of a method of forming a microlens array according to Embodiment 2 of the present invention.
Hereinafter, the second embodiment will be described with reference to FIG.

A photoresist (trade name: AZ1350; manufactured by Clariant Japan)) is applied on a substrate 10 made of quartz glass having a thickness of 0.7 mm by spin coating to a thickness of 0.8 μm to form a photosensitive resin layer 7. Then, the photosensitive resin layer 7 was exposed using a photomask 83 through which the arrangement portion of the microlens array transmits light (see FIG. 8A).

Next, the photosensitive resin layer 7 was developed with an alkali developing solution and heated at 200 ° C. for 1 hour to obtain a circular wall 5 having a width of 1 μm, a radius of 24 μm and a height of 0.7 μm. (See FIG. 8B). Next, an aqueous solution containing 5% by weight of polypinyl alcohol was dip-coated on the substrate 10 on which the wall-shaped material 7 was formed, and dried at 60 ° C. for 2 hours.
The transfer concave shape 30 shown in (C) was formed on the substrate 10.

Next, the substrate 10 was etched in a CHF ₃ plasma gas for 40 minutes using a parallel plate type plasma etching apparatus, and the shape of the transfer concave shape 30 was changed to the substrate 10.
To form a large number of minute concave portions 31 (FIG. 8).
(D)). In this case, the etching rate of the substrate 10 was 2.5 times the etching rate of the transfer concave shape 30, and the depth of the minute concave portion 31 was 1.4 μm.

Next, a thermosetting crezohernovolak type epoxy resin, which is a filling material having a higher refractive index than the substrate, was applied to the surface on which the minute concave portions 31 were formed to obtain a microlens array (FIG. 8 (E)). This microlens array had an extremely good focal length variation of ± 8%.

(Embodiment 3) FIG. 9 is an explanatory view of a method of forming a microlens array according to Embodiment 3 of the present invention.
The third embodiment will be described below with reference to FIG.

A photosensitive resin (trade name: AZ1350; manufactured by Clariant Japan)) is applied on a substrate 10 made of quartz glass having a thickness of 0.7 mm by spin coating to a thickness of 1.2 μm. Using a light-transmitting photomask, the distance between the photomask and the photosensitive resin layer is set to 22 μm, and after exposure, developed with an alkali developing solution to form a transfer concave shape 30 having a width of 2 μm and a radius of 12 μm.
Was obtained (see FIG. 9A).

Next, the substrate 10 is etched in a CF ₄ plasma gas for 40 minutes using a parallel plate type plasma etching apparatus, and the shape of the transfer concave shape 30 is transferred to the substrate 10 to form a minute concave portion 31. (See FIG. 9B). The etching rate of the substrate 10 was 0.8 times the etching rate of the transfer concave shape 30, and the depth of the minute spherical concave portion 31 was 0.96 μm.

On the surface on which the minute concave portions 31 were formed, Si as a filling material having a higher refractive index than the substrate 10 was formed by sputtering, and the formed surface was polished and smoothed to obtain a microlens array. 9 (C)). With this microlens array, the dispersion of the focal length was ± 7%, and a very good microlens array could be formed.

(Embodiment 4) FIG. 10 is an explanatory view of a method of forming a microlens array according to Embodiment 4 of the present invention. Hereinafter, the fourth embodiment will be described with reference to FIG.

A substrate 10 made of 100 μm fluororesin is formed on a Si support substrate 11, and a photosensitive resin (trade name: CD-500; manufactured by Asahi Chemical Laboratory) is coated on the substrate 10 with 2.4 μm.
The photosensitive resin layer 7 is formed by screen printing with a thickness of m to form a photosensitive resin layer 7, and the photosensitive resin layer 7 is exposed using a gradation mask 84 in which the light transmittance of the array portion of the microlens array changes stepwise (FIG. 10A). reference).

Next, this substrate was heated to 35 ° C. and 1%
After development with a developing solution comprising an aqueous sodium carbonate solution, a transfer concave shape 30 having a radius of 63 μm and a depth of 1.8 μm was formed (see FIG. 10B). Note that the gradation mask 84
As shown in FIG. 10 (E), the light transmittance of the circular portion at the center of the microlens of 10 μm is 0% and the light transmittance of the outer portion is 5 μm for each microlens array portion of the microlens array.
The light transmittance of the circular portion of 5% is 5%, the light transmittance of the circular portion of 5 μm outside is 10%, the light transmittance of the circular portion of 5 μm outside is 20%, and the light transmittance of the circular portion of 5 μm outside is 5%. 30
%, And a circular portion of 5 μm outside the circle has a light transmittance of 50%, and a circular portion of 2 μm outside the circle has a gradation of 100% light transmittance. This gradation 84 mask is 2 μm
The amount of transmitted light is controlled by the dot arrangement density.

Next, the substrate 10 is etched in a plasma of a mixed gas of CH ₄ and CF _{4 for} 40 minutes using a parallel plate type plasma etching apparatus, and the shape of the transfer concave shape 30 is transferred to the substrate 10. A concave portion 31 was formed (see FIG. 10C). The etching rate of the substrate 10 was 3.8 times the etching rate of the transfer concave shape 30, and the depth of the minute concave portion 31 was 6.8 μm.

Then, 2,5-dimethylmercapto-1,4-dithiane 1M and bidroxyethyl methacrylate 2M, which are high refractive index filling materials having a higher refractive index than the substrate 10, are formed on the surface on which the minute concave portions 31 are formed. , Photoinitiator (trade name Irgacure 184 manufactured by Ciba Geigy Co., Ltd.) 3w
t% of a photo-curing resin is applied by spin coating, adhered to a counter substrate 12 made of a glass plate, and irradiated with ultraviolet rays of 1 J / cm 2 using a high-pressure water lamp to obtain a microlens array (FIG. 10 ( D)). This microlens array was extremely good with a variation in focal length of ± 7%.

[0081]

As described in detail above, the present invention relates to a concave portion forming step of forming a plurality of minute concave portions on a transparent substrate, and a concave portion formed by the concave portion forming step. A lens portion forming step of forming a lens portion by filling a filling material having a higher refractive index than the refractive index, wherein the concave portion forming step includes forming a plurality of minute transfer concave shapes to be transferred to the substrate. A transfer layer forming step of forming a transfer layer having the transfer layer on the substrate, and a transfer step of transferring a shape of the transfer layer to the substrate to form a plurality of minute concave portions on the substrate. This makes it possible to efficiently form a microlens array having excellent optical characteristics and arbitrary optical characteristics.

In this case, as the transfer layer forming step, a resist mask having fine openings formed in accordance with the arrangement of the microlens array is formed on the transfer material layer, and the resist mask is formed on the transfer layer material layer through the fine openings. By employing the method of forming the transfer concave shape, it is possible to efficiently form the transfer concave shape.

As a transfer layer forming step, after forming a wall-shaped object corresponding to the arrangement of the microlens array on the substrate,
By adopting a method in which a liquid material is applied to the entire surface of the wall-shaped material and then dried to form a minute transfer concave shape, the transfer concave shape can be efficiently formed.

Further, as a transfer layer forming step, a photosensitive resin layer is formed on the substrate, and the distance between the photomask corresponding to the arrangement of the microlens array and the photosensitive resin layer is set to 20 mm.
Employing a method of forming a minute transfer concave shape by exposing and developing by a distance of at least μm enables efficient formation of the transfer concave shape.

Further, the transfer step of transferring the above-described transfer concave shape to the substrate is performed by dry etching, and the dry etching rate of the transfer layer and the dry etching rate of the substrate are made different from each other to obtain the transfer concave shape. Forming a small concave portion on the substrate that amplifies the shape of
Alternatively, an aspherical concave portion can be formed, and it is possible to obtain a very excellent microlens array forming method capable of precisely controlling the optical characteristics of the microlens array.

Further, by forming the substrate with a substrate forming a minute concave portion and a supporting substrate for mechanically supporting the substrate, the selectivity of the material of the substrate on which the minute concave portion can be formed is remarkably increased. To be spread out,
It is possible to obtain a higher performance microlens array.

The microlens array formed by the above-described method of forming a microlens array has excellent optical characteristics.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram of an embodiment of a method for forming a microlens array according to the present invention.

FIG. 2 is an explanatory diagram of a transfer layer forming step.

FIG. 3 is an explanatory diagram of a transfer layer forming step.

FIG. 4 is an explanatory diagram of a transfer layer forming step.

FIG. 5 is an explanatory diagram of a transfer layer forming step.

FIG. 6 is a diagram showing an example in which a substrate is reinforced with a support substrate.

FIG. 7 is an explanatory diagram of the first embodiment.

FIG. 8 is an explanatory diagram of a second embodiment.

FIG. 9 is an explanatory diagram of a third embodiment.

FIG. 10 is an explanatory diagram of a fourth embodiment.

[Explanation of symbols]

10: substrate, 20: transfer layer, 30: concave shape for transfer, 3
Reference numeral 1 denotes a minute concave portion, 32 denotes a lens portion, 83 denotes a photomask, and 84 denotes a gradation mask.

Continuation of the front page (72) Inventor Shigeo Sato 2-7-5 Nakaochiai, Shinjuku-ku, Tokyo Hoya Co., Ltd. F-term (reference) 4F213 AA44 AH74 WA02 WA53 WA56 WA58 WA86 WC02

Claims (10)

[Claims] 1. A concave part forming step of forming a plurality of minute concave parts on a transparent substrate, and a filling material having a refractive index higher than the refractive index of the substrate in the concave part formed by the concave part forming step. And a lens portion forming step of forming a lens portion by filling the transfer portion, wherein the concave portion forming step is a transfer layer forming step of forming a transfer layer having a plurality of minute transfer concave shapes on the substrate, Transferring a shape of the transfer layer to a substrate to form a plurality of minute concave portions on the substrate. 2. The method of forming a microlens array according to claim 1, wherein in the transfer layer forming step, a transfer material layer constituting the transfer layer is formed on the substrate, and a micro layer is formed on the transfer material layer. By forming a resist mask in which minute openings are formed in accordance with the arrangement of the lens array and performing etching through the resist mask, a plurality of minute transfer concave shapes are formed in the transfer material layer to form a transfer layer. Forming a microlens array. 3. The method of forming a microlens array according to claim 1, wherein the step of forming a transfer layer includes forming a wall on the substrate corresponding to the arrangement of the microlens array, A method of forming a transfer layer having a concave shape for transfer by supplying a liquid material during the process. 4. The method of forming a microlens array according to claim 1, wherein in the transfer layer forming step, a photosensitive resin layer is formed on the substrate, and the photosensitive resin layer is formed into a microlens array shape. By using a photomask on which a corresponding pattern is formed, exposing and developing the photomask and the photosensitive resin layer at a distance of 20 μm or more, a transfer layer having a plurality of minute transfer concave shapes is formed. Forming a microlens array. 5. The method of forming a microlens array according to claim 1, wherein in the transfer layer forming step, a photosensitive resin layer is formed on the substrate, and the photosensitive resin layer is formed into a microlens array shape. A method of forming a microlens array, comprising a step of forming a transfer layer having a plurality of minute transfer concave shapes by exposing and developing using a gradation mask on which a corresponding pattern is formed. 6. The method of forming a microlens array according to claim 5, wherein the gradation mask is formed by minute dots. 7. The microlens array according to claim 1, wherein the transfer step of transferring the shape of the transfer layer to a substrate is performed by dry etching. Array formation method. 8. The method of forming a microlens array according to claim 7, wherein a dry etching rate in the transfer step is different between a dry etching rate of the substrate and a dry etching rate of the transfer layer. A method for forming a microlens array. 9. The method for forming a microlens array according to claim 1, wherein the substrate supports a concave portion forming substrate for forming a plurality of minute concave portions, and the substrate supports the concave portion forming substrate. 9. The method of forming a microlens array according to claim 1, further comprising a supporting substrate that performs the method. 10. A microlens array formed by the method of forming a microlens array according to claim 1.