JPH05134103A - Microlens array and their stamper and their manufacture - Google Patents

Abstract

PURPOSE:To provide a microlens array having high effective open ratio and possible to be manufactured practically and its manufacturing method. CONSTITUTION:A microlens array 10 is composed of a substrate 11, a plurality of square frames 12 formed on the substrate 11, and lens elements 13 which are formed in the frames 12, resp. and seen square when observed from the upper side. Since the parts which do not work as lens are only the frames 12, the effective open ratio is heightened by thinning the frames 12. The frames 12 are formed on the substrate 11 and lens basic material is formed in each frame 12. By melting the lens basic material, the upper face of the lens basic material bends upward due to the surface tension of the lens basic material and the curvature of the bent face is kept isotropic due to the isotropy of the surface tension. A microlens array scarcely having astigmatism can be manufactured relatively easily.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a microlens array, a stamper for manufacturing the same, and a manufacturing method thereof.

[0002]

BACKGROUND ART Microlens arrays are expected to grow in demand as important optical elements in the fields of fine optics and other fields. For example, it can be used in a liquid crystal TV (television) projector, and each microlens of the microlens array is arranged corresponding to each pixel of the liquid crystal panel. in this case,
Microlens arrays are required to include tens of thousands to hundreds of thousands of microlenses.

An electron beam drawing method is one of the methods for manufacturing a microlens array. However, the diameter is 100 μ
If tens of thousands to hundreds of thousands of microlenses of about m are drawn, it takes a very long time (for example, tens to hundreds of days) and is not practical.

Further, when the circular microlenses are two-dimensionally arranged, even if the circular microlenses are arranged in contact with each other, it is inevitable that a region where no lens action occurs will occur between the circular microlenses. Is. The effective aperture ratio of the microlens array, which is an array of circular microlenses, is limited to 80%.

[0005]

SUMMARY OF THE INVENTION The present invention is a practical microlens
Provided is a method for manufacturing a stamper for producing an array and a microlens array.

The present invention also provides a microlens array having a high effective aperture ratio and a stamper for manufacturing the same.

In the method for manufacturing a microlens array according to the first invention, a plurality of frames arranged two-dimensionally are formed on a substrate, and each frame has a solubility that does not touch the frames. A lens base material is formed, and each lens base material is melted in each frame to form a convex surface of the microlens, and the melted lens base material is cured.

When the lens base material formed in each frame is melted, the spread range of the melted lens base material is limited by the frame, and the lens shape is determined by the frame. Further, the surface of the fused lens base material becomes a curved surface protruding upward due to surface tension. Since the surface tension generated in the molten lens base material contained within the range limited by the frame is isotropic,
The curvature of the curved surface is isotropic regardless of the shape of the frame such as a rectangle. As a result, a microlens with little or no astigmatism is realized.

The substrate and the frame can be made integrally by using the same material, or can be made by using different materials.

Since the frame and the lens base material can be manufactured by utilizing a technique used in a normal IC manufacturing process such as a molding method, exposure using a mask such as a photoresist, development, etc. A lens array can be made.

A method of manufacturing a stamper for manufacturing a microlens array according to the first aspect of the present invention uses a microlens array manufactured by the above manufacturing method as a master and depositing a stamper material on the master, A stamper is produced by removing it.

A microlens array can be manufactured using this stamper. This method of manufacturing a microlens array is to manufacture a microlens array by injecting a molten resin into the stamper manufactured by the above manufacturing method, curing the resin, and then removing the stamper.

This microlens array manufacturing method is particularly suitable for mass production of microlens arrays.

The present invention further provides a microlens array manufactured by the above manufacturing method, and a stamper for manufacturing the same.

The microlens array according to the first invention is formed of a substrate, a plurality of frames formed on the substrate and arranged two-dimensionally, and in each frame in contact with the inner surface of the frame. It is composed of a plurality of lens elements.

A stamper suitable for mass-producing the microlens array according to the first aspect of the present invention comprises a concave portion corresponding to a plurality of two-dimensionally arranged frames and a state in which each frame is in contact with the inner wall of the frame. And a concave portion corresponding to a plurality of lens elements to be formed.

The shape of the plurality of frames is arbitrary, but a square (square or rectangle) is preferable.

In the microlens array according to the first aspect of the present invention, the portion that does not act as a lens is only the region in which the frame is formed, and the width of the frame can be made considerably narrow, so that the effective aperture ratio is increased. It is possible. The effective aperture ratio is represented by the area occupied by lenses other than the frame with respect to the total area of the microlens array, so it depends on the width of the frame, but as an example, it can be increased to about 95 to 98%.

The present invention also provides a method for manufacturing a single microlens.

In the method of manufacturing a microlens according to the present invention, an enclosing wall is formed on a substrate, and a soluble lens base material having a size that does not contact the inner wall surface of the enclosing wall is formed in the enclosing wall. By melting this lens base material in the surrounding wall, a convex surface of the microlens is formed and the melted lens base material is cured.

The method of manufacturing a microlens according to the present invention can also be realized relatively easily, and a microlens having little or no astigmatism is realized due to the isotropic surface tension acting on the surface of the molten lens base material. To be done.

In the method of manufacturing a stamper for manufacturing a microlens according to the present invention, the microlens manufactured by the above manufacturing method is used as a master, a stamper material is deposited on the master, and the master is removed to form the stamper. It is to be made.

It is possible to mass-produce microlenses using this stamper. That is, the manufacturing method suitable for mass production of the microlens according to the present invention is a method of injecting a molten resin into the stamper manufactured by the above manufacturing method, curing the resin, and then removing the stamper to form the microlens. It is to be made.

The present invention provides a microlens and a stamper manufactured by the above manufacturing method.

The microlens according to the present invention comprises a substrate, a surrounding wall formed on the substrate, and a lens element formed in the surrounding wall so as to be in contact with the inner surface thereof.

The stamper according to the present invention, which is suitable for mass-producing the above-mentioned microlens, has a recess corresponding to the surrounding wall,
It is provided with a concave portion corresponding to a lens element formed in a state where the inner surface is in contact with the surrounding wall.

A method of manufacturing a microlens array according to the second invention is a method of manufacturing a microlens array in which a large number of rectangular microlenses are arranged.
A plurality of soluble, rectangular lens base materials are formed on a substrate at intervals from each other, and the lens base material is melted so that the upper surface of the lens base material is rounded and the molten lens base material is cured.

When the lens base material is melted, its surface is rounded due to surface tension. Since the plurality of lens base materials are arranged with a space between each other, even if they are melted, they remain at that position due to the surface tension and do not fuse with the adjacent ones. A microlens is formed by hardening when the surface of the molten lens base material is rounded.

Thus, according to the second invention, the microlens array can be manufactured by a relatively simple method. Although the surface tension acting on the molten lens base material in the process of manufacturing each microlens in the microlens array manufactured by the second invention cannot be expected to be isotropic, the lens performance is slightly inferior.
Compared with the method of manufacturing the microlens array according to the first aspect of the present invention, it is not necessary to form a frame, so that the manufacturing process is simplified accordingly.

The present invention provides a method of manufacturing a stamper suitable for mass-producing a square microlens array. In the stamper manufacturing method according to the present invention, the rectangular microlens array manufactured by the above manufacturing method is used as a master disk, a stamper material is deposited on the master disk, and the master disk is removed to manufacture the stamper.

The present invention further provides a method of manufacturing a microlens array using the stamper. A method of manufacturing a microlens array according to the present invention is a method of manufacturing a rectangular microlens array by injecting a molten resin into a stamper manufactured by the above manufacturing method, curing the resin, and then removing the stamper. Is. This manufacturing method is suitable for mass production of a rectangular microlens array.

The present invention further provides a rectangular microlens array manufactured by the above manufacturing method and a stamper for manufacturing the same.

A square microlens array according to a second aspect of the present invention comprises a substrate and a plurality of micro-lenses which are formed on the substrate and have a square surface in contact with the substrate and which are two-dimensionally arranged at intervals. It consists of a lens.

The microlens array according to the second invention comprises rectangular microlenses arranged at intervals. Since the microlenses are rectangular, the area occupied by the gaps between them can be made smaller than that of circular ones, etc., thereby increasing the effective aperture ratio.

[0035]

[Explanation of Examples]

(1) First Embodiment FIG. 1 shows a part of a microlens array according to the first embodiment.

The microlens array 10 includes a substrate 11 and
It is composed of a plurality of frames 12 formed on the substrate 11 and arranged two-dimensionally, and a plurality of microlens elements 13 formed in each frame 12 in contact with the inner surface of the frame 12. .. These substrate 11, frame 12 and microlens element 13
Are formed of transparent materials.

The plurality of frames 12 are formed by walls extending vertically and horizontally and intersecting each other at right angles. Although the frame 12 is rectangular in a plan view in this embodiment, it may be square, triangular, hexagonal, or any other shape. Preferably, the frame 12 is formed so as to prevent a blank portion where neither the frame 12 nor the microlens element 13 is provided, except for the edge portion of the substrate 11. The frame 12 is as narrow as possible to reduce the occupied area on the substrate 11.

The vertical and horizontal cross sections of the frame 12 and the microlens element 13 provided in the frame 12 are shown in FIGS. 2 (A) and 2 (B). Although the length and width of the frame 12 are different,
The curvature of the convex curved surface of the microlens element 13 is isotropic. That is, the cross-sectional shape of the microlens element 13 is the same in FIGS. 2 (A) and 2 (B). Therefore, the height dA at which the side surface of the microlens element 13 contacts the inner wall surface of the frame 12,
dB is lower in the cross section having a longer frame length and higher in the cross section having a shorter length.

An example of the microlens array 10 is as follows.

The substrate 11 is a glass substrate, the frame 12 and the microlens element 13 are photoresist or resin (for example, ultraviolet curing resin), and the size of the frame 12 is 120 μm × 94 μm.
The width of 12 is 2 μm, and the number of microlens elements 13 is 235,20
It is 0 (480 x 490).

The effective aperture ratio (ratio of the area occupied by the microlens element to the area occupied by the frame and the microlens element) of the microlens array 10 is 96% or more.

FIG. 3 shows the microlens array 10 described above.
The manufacturing process of is shown. In this figure, the same components as those shown in FIG. For example, the board 11 is referred to as a board 11A.

A negative type photoresist 12a is coated on the glass substrate 11A (FIG. 3 (A)).

The photoresist 12a is exposed using a mask 15 having a light transmitting portion in the shape of a frame to be formed (see FIG. 3).
(B)).

After exposure, development is performed to leave a frame 12A made of photoresist on the substrate 11A (FIG. 3C).
If necessary, deep UV (deep UV: ultraviolet light having a short wavelength) is irradiated to cure the photoresist frame 12A (deep UV cure or deep UV hardening).

A positive type photoresist 13a is coated so as to cover the frame 12A formed on the substrate 11A (FIG. 3D).

A mask 16 having a light-shielding portion in the shape of a lens base material to be formed is used to position each light-shielding portion in the center of the frame 12A, and the photoresist 13a is exposed (FIG. 3 (E)). ..

After exposure, by developing, the lens base material 13b made of photoresist remains in the central portion of the frame 12A on the substrate 11A. Further, near UV (ultra-violet light having a long wavelength) is irradiated to expose the photoresist / lens base material 13
Lower the melting point of b (Fig. 3 (F)).

Finally, the whole is baked (heated) and the base metal
Melt 13b (Fig. 3 (G)). The base material 13b spreads in the frame 12A, and its upper surface becomes a curved surface protruding upward due to surface tension. As a result, the microlens element 13
A can be done. If left at room temperature as it is, the microlens element 13A is cured.

In this way, the microlens array
10A is completed.

FIG. 5 shows a state in which the step shown in FIG. 3 (F) is completed. Lens base material 13 formed in the frame 12A
b may be cylindrical, prismatic, or any other shape. Preferably, the lens base material 13b does not contact the frame 12A.

FIG. 6 shows a microlens 13A and a frame 12A formed by completing the process shown in FIG. The lens base material 13b is melted by heating and spreads inside the frame 12A, and its peripheral portion contacts the frame 12A. Since the spread of the fused lens base material 13b is limited by the frame 12A, its surface tension is isotropic, and the curvature of the lens curved surface formed is also isotropic. That is, as shown in FIG.
As explained with reference to (B), the vertical and horizontal cross-sectional shapes are the same. In this way, a microlens excellent in light converging property with little or no astigmatism is realized.

In the above, the frame 12A and the substrate 11A may be integrally formed in advance. For example, after the process of FIG. 3 (C) is completed, a substrate 11A having a frame 12A is used, and nickel having a concave portion having the same shape as that of the frame 12A is formed by an electroforming method described later.
Form a stamper. A resin is injected between the nickel stamper and the substrate, the resin is hardened, and then the stamper is peeled off to obtain a frame integrally molded with the resin on the substrate. Both the substrate and the frame may be integrally molded with resin.

Further, both the frame 12A and the lens base material 13b can be made by using a positive type photoresist. In the step of FIG. 3A, a positive type photoresist is applied on the substrate 11A. In the step of FIG. 3B, the photoresist is exposed by using a mask having a light-shielding portion corresponding to the shape of the frame to be molded. After that, when it is developed, as shown in FIG. 3C, a frame made of photoresist remains on the substrate 11A. The frame made of this photoresist is irradiated with deep UV to cure the photoresist frame. Due to this curing, the photoresist frame is not exposed by the exposure in the exposure process shown in FIG. The following steps are the same as those in FIGS. 3 (D) to (G).

Instead of photoresist, electron beam (E
B) It is also possible to use a resist. In this case, electron beam exposure is performed.

The microlens array 10A manufactured as described above can be used as it is.
Preferably, a stamper is manufactured using the above-mentioned microlens array 10A as a master, and the stamper is used to mass-produce the microlens array.

The steps of making a stamper and making a microlens array using the stamper are shown in FIG.

Using the microlens array 10A as a master, a stamper material such as nickel is deposited on the master 10A by an electroforming method or the like to produce a nickel stamper 14 (FIG. 14 (H)). The stamper 14 and the master 10A are separated. The stamper 14 has a shape having a first recess corresponding to the frame 12A and a second recess corresponding to the microlens element 13A.

A molten resin is filled between the stamper 14 thus obtained and a separately prepared substrate 11B made of glass or the like, and a resin is applied while an appropriate pressure is applied between the stamper 14 and the substrate 11B. To cure. For example, an ultraviolet curable resin is used as the resin, and the resin can be cured by irradiating the substrate 11B with ultraviolet rays. Stamper 14
The frame 12B and the microlens element 13B are molded with resin in the first concave portion and the second concave portion, respectively (FIG. 4 (I)).

Finally, if the stamper 14 is removed, the substrate 11B
A large number of frames 12B on top and microlens elements 13 in each frame 12B
A microlens array 10B having B and B is obtained (FIG. 4 (J)). The microlens array 10B and the above-mentioned microlens array 10A have the same shape, and both can be used.

It is possible to mass-produce the microlens array 10B using the stamper 14.

The microlens thus obtained
Arrays 10A and 10B are designated as 10 in FIG.

In the above embodiment, a plurality of frames are formed on one substrate, and the microlens element is formed in each frame. It is also possible to form one frame (enclosing wall) on one substrate and form one microlens element in this frame. Such a single microlens or a master thereof, a stamper for mass production, and a microlens using the stamper include the methods described with reference to FIGS. 3 and 4. It is applicable as it is.

(2) Second Embodiment FIG. 7 shows a rectangular microlens array according to the second embodiment. In this figure, the same components as those shown in FIG. 1 are designated by the same reference numerals.

Square microlens array 20 shown in FIG.
Is different from the microlens array 10 shown in FIG. 1 in that a plurality of frames are not present. The plurality of rectangular microlens elements 13 forming the rectangular microlens array 20 are regularly arranged in the vertical and horizontal directions and are slightly spaced from each other.

Such a square microlens or its master can be manufactured by the steps shown in FIGS. 3 (D) to 3 (E). The difference from the manufacturing process of the microlens array 10A described above is that the process of manufacturing the frame is basically unnecessary.

That is, the photoresist 13 is formed on the substrate 11A.
The photoresist 13a is exposed by using a mask which is coated with a and shields the area where the rectangular microlens element is to be formed (in the case of a positive type photoresist), and then developed.

The semi-finished product obtained after development is shown in FIG. The lens base materials 13b, which are rectangular in plan view, are regularly arranged vertically and horizontally with a slight gap between them. If necessary, the melting point of the lens base material 13b is lowered by near UV irradiation, and then the lens base material 13b is baked (heated).
b melts. The molten lens base material 13b has a rounded upper surface due to surface tension. The fused lens base material 13b does not flow out due to surface tension. Since there is a gap between the lens base materials 13b, the adjacent fused lens base materials 13b do not stick to each other. After that, the lens base material 13b is cured to obtain a rectangular microlens array or its master.

Fabrication of a stamper using this master and mass production of a rectangular microlens array using this stamper can be realized in the same manner as the process shown in FIG.

In the manufacturing process of the lens base material 13b, the first
As a step, it is also possible to form a portion of the lens base material 13b to serve as a base, cure the base by deep UV irradiation, and form the lens base material 13b thereon.

[Brief description of drawings]

FIG. 1 is a perspective view showing a part of a microlens array according to a first embodiment.

2A is a sectional view taken along line AA of FIG. 1, and FIG. 2B is a sectional view taken along line BB of FIG.

3A to 3G are cross-sectional views showing a manufacturing process of a microlens array or a master thereof.

4 (H) to (J) are perspective views showing a stamper for manufacturing a microlens array and a manufacturing process of a microlens array manufactured using this stamper.

FIG. 5 is a perspective view showing a lens base material formed in a frame.

FIG. 6 is a perspective view showing a microlens element formed in a frame.

FIG. 7 is a perspective view showing a part of a rectangular microlens array according to a second embodiment.

FIG. 8 is a perspective view showing a state in which a rectangular lens preform is manufactured on a substrate for manufacturing a rectangular microlens array.

[Explanation of symbols]

 10, 10A, 10B Microlens array 11, 11A, 11B Substrate 12, 12A, 12B Frame 13, 13A, 13B Microlens element 13b Lens base material 20 Square microlens array

Claims (22)

[Claims] 1. A plurality of two-dimensionally arranged frames are formed on a substrate, and a soluble lens base material having a size not in contact with the frames is formed in each frame, and each lens base material is formed. A method for manufacturing a microlens array, in which the convex surface of the microlens is formed by melting in each frame, and the molten lens base material is cured. 2. A stamper manufacturing method, wherein a microlens array manufactured by the manufacturing method according to claim 1 is used as a master disk, a stamper material is deposited thereon, and the stamper is manufactured by removing the master disk. 3. A microlens array in which a microlens array is produced by injecting a molten resin into the stamper produced by the production method according to claim 2, curing the resin, and then removing the stamper. Manufacturing method. 4. A microlens array manufactured by the manufacturing method according to claim 1. 5. A stamper for manufacturing a microlens manufactured by the manufacturing method according to claim 2. 6. A micro comprising a substrate, a plurality of frames formed on the substrate and arranged two-dimensionally, and a plurality of lens elements formed in each frame in contact with the inner surface of the frame. Lens array. 7. A micro having a concave portion corresponding to a plurality of frames arranged two-dimensionally, and a concave portion corresponding to a plurality of lens elements formed in each frame in contact with the inner wall of the frame. Stamper for manufacturing lens arrays. 8. A microlens array according to claim 6 is used as a master, and a stamper material is deposited on the master,
A stamper manufacturing method in which a stamper is manufactured by removing a master. 9. A microlens array is manufactured by using the stamper according to claim 7, injecting a molten resin into the stamper, curing the resin, and then removing the stamper. Production method. 10. A surrounding wall is formed on a substrate, and a soluble lens base material having a size not touching an inner wall surface of the surrounding wall is formed in the surrounding wall, and the lens base material is surrounded by the surrounding wall. The convex surface of the microlens is formed by melting inside
A method for manufacturing a microlens, which comprises curing a molten lens base material. 11. A stamper manufacturing method, wherein a microlens manufactured by the manufacturing method according to claim 10 is used as a master, a stamper material is deposited thereon, and the master is removed to manufacture the stamper. 12. A method of manufacturing a microlens, which comprises manufacturing a microlens by injecting a molten resin into the stamper manufactured by the method of claim 11, curing the resin, and then removing the stamper. 13. A microlens manufactured by the manufacturing method according to claim 10. 14. A stamper for manufacturing a microlens manufactured by the manufacturing method according to claim 11. 15. A microlens comprising a substrate, a surrounding wall formed on the substrate, and a lens element formed in the surrounding wall in contact with the inner surface thereof. 16. A stamper for manufacturing a microlens, comprising a concave portion corresponding to a surrounding wall and a concave portion corresponding to a lens element formed in the surrounding wall in contact with the inner surface thereof. 17. A plurality of fusible rectangular lens base materials are formed on a substrate at intervals from each other, and the lens base materials are melted so that the top surface of the lens base materials is rounded to cure the molten lens base materials. , Method for manufacturing square microlens array. 18. A method of manufacturing a stamper, wherein a rectangular microlens array manufactured by the manufacturing method according to claim 17 is used as a master and a stamper material is deposited on the master, and the stamper is manufactured by removing the master. .. 19. A rectangular microlens array is manufactured by injecting a molten resin into a stamper manufactured by the manufacturing method according to claim 18, curing the resin, and then removing the stamper. An array manufacturing method. 20. A rectangular microlens manufactured by the manufacturing method according to claim 17 or 19. 21. A stamper for manufacturing a rectangular microlens manufactured by the manufacturing method according to claim 18. 22. A microlens array comprising a substrate and a plurality of microlenses formed on the substrate, the surfaces contacting the substrate being rectangular, and two-dimensionally arranged at intervals with respect to each other.