JPH07174902A - Microlens array and its production - Google Patents

Abstract

PURPOSE:To provide a method for producing microlenses by which a light shielding layer is easily formed and a microlens array excellent in environmental resistance can easily be produced. CONSTITUTION:A light shielding layer 3 is formed in accordance with an array of the lens apertures of microlenses on at least one side of a substrate 1 which is a transparent flat plate having parallel faces and cured resin parts 7 having an array of desired refractive faces are formed by molding with a mold 5 having an array of curved surfaces corresponding to the desired refractive faces.

Description

Detailed Description of the Invention

[0001]

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

[0002]

2. Description of the Related Art Starting from the field of optical communication, the use of microlenses, that is, extremely small lenses having a lens diameter of 1 mm or less is intended and is being put to practical use. Since the microlens has an extremely small lens diameter, it is difficult to manufacture the microlens by a polishing method like an ordinary lens, and a manufacturing method by a chemical / physical method has been proposed.

In the microlens array, since the minute lenses as described above are arrayed, the light to be incident on another microlens is incident as stray light unless the arranged microlenses are optically independent. Then, the optical performance of the microlens array may be deteriorated.

Therefore, it is preferable to form a "light-shielding layer" having an opening corresponding to each microlens array in the microlens array. As a method of forming such a light shielding layer, the following method can be considered. That is, a pattern of a photoresist is formed by photolithography in a portion forming an opening with the optical axis of each microlens of the microlens array as the center, and a light shielding layer is formed of metal or the like on the photoresist pattern. After that, the microlens array is immersed in an organic solvent to dissolve the photoresist pattern with the solvent, and the light-shielding layer on the pattern is peeled off from the microlens array by "lift-off", and the portion other than the openings of the microlens array is removed. Leave the light shielding layer.

This light-shielding layer forming method is not efficient because of the large number of steps. Further, since the light-shielding layer is formed on the surface of the microlens array, there is a problem that the light-shielding layer is likely to be peeled off depending on environmental conditions.

[0006]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned circumstances, and an object thereof is to provide a microlens array in which a light-shielding layer can be easily formed and which has excellent environmental resistance. 1). Another object of the present invention is claim 1.
A microlens manufacturing method capable of easily manufacturing the described microlens array is provided (2, 3).

[0007]

According to a first aspect of the present invention, there is provided a "microlens array" having a light-shielding layer corresponding to an array arrangement of lens apertures of microlenses on at least one surface of a transparent parallel plate substrate. A curable resin portion having a refracting surface arrangement that matches the array arrangement of the lens apertures is formed on at least the surface on the side where the light shielding layer is formed ”.

The light shielding layer is the "at least one surface" of the substrate.
It is needless to say that the light-shielding layer may be formed on both surfaces of the substrate, if necessary. Of course, when the light-shielding layers are formed on both surfaces of the substrate, the light-shielding layers are aligned so that the lens apertures in the light-shielding layers on both sides of the substrate are aligned with each other (the centers of the corresponding apertures are aligned). Of course it is done.

A method for manufacturing a microlens array according to a second aspect is a method for manufacturing the microlens according to the first aspect, which includes a light shielding layer forming step and a mold forming step. The “light-shielding layer forming step” is a step of forming a “light-shielding layer corresponding to an array arrangement of lens openings of microlenses” on at least one surface of a transparent parallel plate substrate.

The "mold forming step" is a mold forming using a "mold" having an array array of curved surfaces corresponding to a desired refracting surface shape, and a "curable resin portion" having an array array of desired refracting surfaces.
Is a step of forming.

In the light-shielding layer forming step, various methods can be used to form a light-shielding layer corresponding to the array arrangement of the lens apertures of the microlenses on at least one surface of the transparent parallel plate substrate.

For example, a metal thin film and a thin layer of photoresist are laminated on the surface of the substrate in the above order from the substrate surface side, and the thin film of photoresist is patterned by photolithography according to the array arrangement of the lens openings to form openings. Make the metal thin film part corresponding to the part "exposed",
After that, the metal thin film is etched using the patterned photoresist as a mask to remove the metal thin film at the lens opening. Then, if the photoresist mask is removed, a light-shielding layer is obtained by the pattern of the metal thin film. Alternatively, the light shielding layer can be formed as an ink layer by printing.

As the "curable resin", a thermosetting resin or a photocurable resin can be used. When the "thermosetting resin" is used, the resin may be cured by heating the thermosetting resin in a desired shape with a mold.

When a "photo-curable resin" such as an ultraviolet-curable resin is used as the curable resin, it is
The resin may be cured by irradiation with light. The irradiation of light is
When the “mold” is transparent, it can be carried out through the mold, but when the mold is a light-shielding material such as metal, it may be carried out through the substrate.

At this time, since the light-shielding layer formed on the substrate makes it difficult to irradiate light from the substrate side to the photo-curable resin portion which becomes the "shadow of the light-shielding layer", in this case, the surface of the mold. Of at least "curved portion is light-reflecting" so that the light emitted from the substrate side is reflected on the surface of the mold and is applied to the shaded portion of the light-shielding layer (claim 3). .

[0016]

As described above, in the present invention, since the light shielding layer is formed "directly" on the substrate, the light shielding layer has a shape sandwiched between the substrate and the curable resin portion, and the opening end portion of the light shielding layer is Never touch the outside air.

[0017]

EXAMPLE FIG. 1 is an explanatory view showing an example of a method for manufacturing a microlens according to claim 3. In FIG. 1A, a light shielding layer 3 corresponding to “array arrangement of lens apertures of microlenses” is formed on the upper surface of the substrate indicated by reference numeral 1.

The substrate 1 is, for example, quartz glass and is a transparent parallel plate. The light shielding layer 3 is made of a metal thin film and is formed as follows. Al was vapor-deposited on the surface of the substrate 1 to form a metal thin film, and a thin layer of photoresist was formed thereon. The thin film of the above photoresist was patterned by photolithography according to the array arrangement of the lens openings so that the metal thin film portion corresponding to the openings was “exposed”.

The shape of the opening is circular. afterwards,
The metal thin film was etched using the patterned photoresist as a mask to remove the metal thin film in the lens opening, and then the photoresist mask was removed. This state is the state shown in FIG.

As shown in FIG. 1 (b), the mold 5 was fitted to the light shielding layer 3 side. The mold 5 has a concave array corresponding to the array arrangement of the openings of the light shielding layer, and is aligned such that the bottom of each concave is aligned with the center of each opening of the light shielding layer 3. The concave portion of the mold 5 has "light reflectivity".

An ultraviolet curable resin 7 as a photocurable resin was injected into a space sandwiched between the substrate 1 and the mold 5, and ultraviolet rays 9 were uniformly irradiated through the substrate 1. The applied ultraviolet rays cure the ultraviolet curing resin 7. In addition, since the concave portion of the mold 5 is light-reflecting, the ultraviolet rays reflected by this portion are also effectively irradiated to the portion that becomes the “shadow of the light-shielding layer 3” with respect to the irradiation ultraviolet rays, and the ultraviolet curing resin 7a is effectively cured.

The mold 5 is removed, and as shown in FIG. 1C, "the light-shielding layer 3 is formed on the substrate 1 according to the array arrangement of the lens openings, and the surface on the side where the light-shielding layer 3 is formed is formed. , And a curable resin portion 7 having a refracting surface arrangement that matches the array arrangement of the lens apertures is formed ”. The shape of the refracting surface formed by the curable resin portion 7 is a “convex spherical surface”.

As shown in FIG. 2 (a), with respect to the microlens array of FIG. 1 (c), another surface is formed on the opposite surface of the substrate 1 in correspondence with the refraction surface array of the curable resin portion 7. By forming the refraction surface array as the curable resin portion 11 in the same manner as the curable resin portion 7, a microlens array having biconvex microlenses can be obtained.

In the embodiment shown in FIG. 2B, the surface of the microlens array shown in FIG.
In correspondence with the refraction surface arrangement of the curable resin portion 7, the concave surface shape 1
3 is an example in which a refracting surface arrangement according to 3 is formed. In this microlens array, the individual microlenses are "meniscus lenses".

In FIG. 1B, if a “mold having a convex array” is used instead of the mold 5, the refracting surface formed as the surface shape of the curable resin portion can be made concave. it is obvious.

Here, the mold 5 described with reference to FIG.
The manufacturing will be briefly described. In FIG. 3A, reference numeral 10 indicates a substrate such as a glass plate. A thermoplastic material layer 12 having a desired thickness is formed on a flat surface of the substrate 10, and a metal thin film layer 14 as an intermediate layer and a thin layer 16 of a photosensitive material such as photoresist are laminated on the thermoplastic material layer 12. ing.

In the state shown in FIG. 3A, the "end face shape of the microlens array" is patterned on the thin layer 16 of the photosensitive material by exposure. For patterning exposure, a mask may be used to uniformly irradiate light,
The pattern may be drawn by "laser drawing".

When the portion which is not irradiated with light (when the photosensitive material is a negative type) or the portion which is irradiated with light (when the photosensitive material is a positive type) is removed by the exposure, as shown in FIG.
Patterning is performed as shown in FIG.

The above-mentioned "end face shape" refers to the shape of the patterned thin layer 16 of the photosensitive material in FIG. 3 (b) as viewed from above in FIG. 3 (b). Or elliptical, square or rectangular, or 5
The shape may be a polygonal shape such as a polygonal shape or a hexagonal shape, but the arrangement is in agreement with the “lens arrangement in the microlens array to be formed”.

After patterning, the metal thin film layer 14 is wet-etched. At this time, the patterned thin layer 16 of the photosensitive material serves as a mask, and the wet etching acts only on the "bare metal thin film layer portion".

Therefore, after the etching, the "end face shape" formed on the thin layer 16 of the photosensitive material is "transferred" to the metal thin film layer 14 as it is. This state is shown in Figure 3.
It shows in (c). In the portion where the metal thin film layer 14 has been removed by etching, the upper surface of the thermoplastic material layer 12 below it is exposed.

Subsequently, anisotropic dry etching is performed using the metal thin film layer on which the above-mentioned end face shape is copied as a mask.
Since the dry etching proceeds so as to engrave the “portion not covered by the mask (metal thin film layer 14)” of the thermoplastic material layer 12 in the thickness direction, the thermoplastic material layer 12
When dry etching is performed until the film is completely etched in the thickness direction, a three-dimensional pattern of the thermoplastic material layer 12 that exactly follows the end face shape is obtained in a "relief shape", as shown in FIG. 3 (d). From this state, when the metal thin film layer 14 used as the mask is removed by a usual method, as shown in FIG.
A dimensional pattern is obtained. Although the thin layer 16 of the patterned photosensitive material is removed before performing the dry etching (FIG. 3D), the dry etching is performed without removing the thin layer 16. After etching, the thin metal film layer 14 and the thin layer 16 of the photosensitive material may be removed.

Subsequently, the three-dimensional pattern of the thermoplastic material layer 12 is heated and thermally deformed (generated by the action of heat flow and surface tension) to create one or more desired convex surface shapes (FIG. 3 (f). )).

After thermal deformation, anisotropic dry etching is further performed. That is, dry etching is performed from the state of FIG. 3F, and the “convex shape” formed by the thermoplastic material layer 12 is engraved on the substrate 10. At this time, if the rates of dry etching are equal in the thermoplastic material layer 12 and the base body 10, the convex shape created in the thermoplastic material layer 12 is “engraved” as the surface shape of the base body 10 as it is. It will be. If the thermoplastic material layer 12 and the base 10 have different etching rates, the convex shape engraved on the base 10 is the same as the convex shape created in the thermoplastic material layer 12 in the height direction. The shape is an “enlarged or reduced shape”, but in any case, the shape corresponds to the convex shape created in the thermoplastic material layer 12.

In this way, the surface shape of the substrate 10 can be obtained in a state where the convex shapes are arrayed.
As described above, this convex shape can be formed into a desired shape by adjusting the thickness of the thermoplastic material layer 12 and the etching rate ratio (selection ratio) between the thermoplastic material layer 12 and the substrate 10. Therefore, this convex surface shape is made to be the refractive surface shape of each microlens in the microlens array to be created. It should be noted that the convex shape formed can be made to be an “aspherical shape” by adjusting the selection ratio continuously or stepwise.

In this way, the substrate 10 on which the convex array array is formed is used as a "mold", and a second mold having a concave shape corresponding to the convex array array is formed by molding. By forming a thin film of Al or the like on the concave surface by vapor deposition or sputtering, the mold 5 described with reference to FIG. 1B can be obtained.

The intermediate layer shown by the reference numeral 14 in FIG. 3 (a) may be formed as a non-metal thin film such as Si in addition to the above metal thin film. When the intermediate layer is a non-metal thin film, The etching for shifting from the state of FIG. 3B to the state of FIG. 3C can be performed by dry etching.

The thickness of the intermediate layer is preferably 2000 to 10000Å when the intermediate layer is formed of a metal thin film, and 2000 to 5000Å when formed of Si or the like.

Next, a method for directly forming a concave refracting surface on the back surface side of the substrate 10 in the state of FIG. 2B will be described. As this method, the method disclosed in JP-A-5-173003, column 11, lines 18 to 20, and FIG. 3 can be used.

In FIG. 2B, a photoresist film having a desired thickness is formed on the back surface of the substrate 1 (the surface on the side where the concave refraction surface array is formed), and the concave array is formed on the photoresist film. A pattern corresponding to the array is exposed using a mask.

In the exposure mask used at this time, the light transmittance gradually decreases from the central portion of the pattern shape to the outside in the portion corresponding to each concave shape (when the photoresist is a positive type). Use things.

When the development is performed after the exposure as described above, the surface shape of the photoresist becomes a concave shape.
From this state, dry etching as described with reference to FIG. 3G is performed to engrave the concave shape as the surface shape of the substrate 1. At this time, the thickness of the photoresist, the exposure conditions, the selection ratio, etc. are adjusted so that the engraved concave surface shape becomes a desired refractive surface shape (the shape of the refractive surface 13 in FIG. 2B). .

In the "concave shape" of FIG. 2B, a mold having a convex shape is used, and an ultraviolet curable resin is injected into the space between the substrate 1 and the mold so that ultraviolet rays are evenly distributed through the substrate 1. It may be formed by irradiating and curing the ultraviolet curable resin.

It is obvious that the substrate 1 having a concave shape thus formed can also be used as a mold for forming a convex refracting surface on the surface of a curable resin. In this case, it goes without saying that if the substrate is transparent, light irradiation can be performed through the substrate as a mold. Also, FIG.
The base body 10 having a convex shape as shown in (g) can be used as a mold when forming a concave refracting surface in the curable resin.

If a substrate having a shape other than the plane-parallel plate is used as the substrate, for example, a prism-shaped substrate, an in-prism microlens array can be formed, or the number of lenses to be formed can be 1 or It should be additionally noted that a microlens, an in-prism microlens, or the like can be realized by dividing the array arrangement of the formed microlens array for each microlens.

[0046]

As described above, according to the present invention, a novel microlens array and a manufacturing method thereof can be provided.

Since the microlens array of the present invention has the "light-shielding layer corresponding to the array arrangement of the lens apertures of the microlens", the light to be incident on another microlens is incident as stray light and is incident on the microlens. The optical performance of the lens array is not likely to deteriorate, and the end face of the opening in the light-shielding layer does not come into contact with the outside air, so there is little possibility of peeling due to the action of the environment, and environmental resistance is excellent.

According to the second and third aspects of the present invention, since it has the above-mentioned structure, the microlens array can be efficiently formed.

[Brief description of drawings]

FIG. 1 is a diagram for explaining one embodiment of the invention according to claim 3;

FIG. 2 is a diagram for explaining two examples of the form of the microlens array of the present invention.

FIG. 3 is a method 1 for manufacturing a mold used in the above embodiment.
It is a figure for explaining an example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Substrate 3 Light-shielding layer 5 Type 7a Curable resin 7 Curable resin part on which an array arrangement of refracting surfaces is formed

Claims (3)

[Claims] 1. A light shielding layer corresponding to an array arrangement of lens apertures of microlenses is formed on at least one surface of a transparent parallel plate substrate, and at least a surface on the side where the light shielding layer is formed, A microlens array, wherein a curable resin portion having a refracting surface arrangement that matches the array arrangement of the lens apertures is formed. 2. A method of manufacturing a microlens array according to claim 2, wherein a light-shielding layer is formed on at least one surface of a transparent parallel plate substrate in accordance with an array arrangement of lens apertures of the microlenses. And a mold forming step of forming a curable resin portion having an array arrangement of desired refraction surfaces by mold forming with a mold having an array arrangement of curved surface shapes corresponding to a desired refraction surface shape. A method of manufacturing a microlens array, comprising: 3. The method for manufacturing a microlens array according to claim 2, wherein the curable resin is a photocurable resin, and light is irradiated from the transparent substrate side during molding, so that at least a curved surface of the mold is obtained. A method for manufacturing a microlens array, characterized in that a portion having a shape of light reflection is used.