JPH04165302A - Microlens and manufacture thereof - Google Patents

Abstract

PURPOSE:To prevent re-fusion of a microlens manufactured through fusion by covering the surface of the microlens with cured resin. CONSTITUTION:A base sheet on which lens materials 13 are formed in a pattern is heated and the pattern of the lens material is heated and fused to form a microlens 14. A film of crosslinkable resin 15 which causes the occurrence of crosslink reaction owing to at least one kind of heat, active energy beams, and forming treatment is formed on the surface of the microlens 14 formed at a current time by coating and the like. Thereafter, the crosslinkable resin 15 is cured through three-dimensional crosslink of the resin by means of at least one kind of heat, active energy beams, and forming treatment. This method prevents a microlens, manufactured through heat fusion, from re-fusion during heat treatment in a process to mount the microlens to a device.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a microlens provided in a solid-state image pickup device or a display device.

[Prior art] Various proposals have been made regarding the light-receiving silver electrode section, transfer method, etc. for charge-coupled solid-state imaging devices used as solid-state imaging cameras or image sensors, but recently, further miniaturization has been proposed. Along with the demand for a higher number of pixels, there is also a demand for higher sensitivity and lower noise, and various proposals have been made regarding circuits and structures of imaging devices in this regard. In particular, in terms of device structure, the most commonly proposed approach is to increase the aperture ratio of the light-receiving surface, because there is a limit to reducing inherent noise by improving the solid-state image sensor itself, so increasing the incident light This is because there is currently no effective method other than increasing the input signal strength.

Although the method of forming microlenses directly on a solid-state image sensor has a simple structure, it is recommended as one of the effective methods for increasing the aperture ratio.

The principle structure thereof will be explained with reference to FIG. 3. In the same figure, there are
A solid-state image sensor 30 is shown that includes a transparent film 32 to form an appropriate interval with respect to the light receiving sections 34, 34, etc., and a micro Lenses 33, 33, etc. are provided to condense the external incident light 35 to the light receiving parts 34, 34, etc. by the optical refraction effect of the microlens 33, and also to the non-light receiving part where the transfer part and the wiring part (not shown) are located. The incident light is also made to enter the light receiving sections 34, 34, . . . , thereby substantially increasing the aperture ratio.

The manufacturing method of this microlens is a heating melting method (for example,
There are two main methods: JP-A-59-147586 (see Japanese Patent Publication No. 59-147586) and plate-making coating method (see, for example, Japanese Patent Publication No. 62-51504).

The heat melting method will be explained with reference to FIGS. 4(A) to 4(D). FIG. 4(A) shows a solid-state image sensor having a transparent film 41 provided on a semiconductor substrate 42 having light receiving sections 46, 46, etc. 40 is shown, and a thermoplastic transparent positive-type photosensitive resin film 43 is applied on this transparent film 41 (Fig. 4(B)), and this film 43 is positioned at corresponding positions on the light receiving parts 46, 46... After exposure and development (FIG. 4(C)), the film 44 remaining after the development is heated, melted, and fluidized to form convex lenses 45, 45, etc. (FIG. 4(D)).

Next, the plate-making coating method will be explained with reference to FIGS. 5(A) to D).
A solid-state image sensing device 50 is shown in which a transparent film 51 is provided on the transparent film 51 (FIG. 5(A)), and a transparent photosensitive resin film 53 is formed on the transparent film 51 (FIG. 5(B)), which allows light to be received. Part 56.56
...Residual film 54 of convex photosensitive resin coating at the corresponding position above
．． Expose and develop so that 54... is located in Figure 5 (C
)), a transparent resin coating 55 is applied to this residual film 54, 54...
is applied, heated, melted, and fluidized to form a convex lens 5.
6.56... (Fig. 5 (D) In addition to solid-state image sensors, display devices such as liquid crystal display devices, cathode ray tubes, and projection screens also have microlenses installed on their display screens to improve the field of view. Proposals have been made for the purpose of enlarging the corners and improving contrast, and products that take advantage of these are being produced.

Unlike solid-state image sensors, these manufacturing methods require relatively large screens and therefore large pixels. Therefore, molds for microlenses are made and mass-reproduced, patterns are formed using printing methods, heat-melting methods, etc. It is possible to apply a plate coating method.

As described above, in producing microlenses for use in various fields, microlenses produced by the heating melting method and the plate coating method each have the following problems.

In the plate-making coating method, after forming a pattern by plate-making, a liquid resin is applied and cured.
As shown in A), the bottom of the lens has a concave shape 22 and does not function as a convex lens, so the effective area as a convex lens 21 tends to be small. In the heat melting method, as shown in FIG. 2(B), the effective part 24 is large and the ineffective part 23 is relatively narrow, so that the light collection efficiency is good.

[Problems to be solved by the invention] On the other hand, microlenses produced by heating and melting have a good shape as a lens, can use a large effective lens area, and are effective in terms of light gathering ability, but they do not form a pattern. In order to manufacture the microlens by heating and melting the resin, the resin of the microlens material is not hardened by a three-dimensional crosslinking reaction or the like. For this reason, the lens may be remelted by heating during post-processing (for example, during mounting, such as pancaging), resulting in defective lens shapes, or may not have sufficient resistance to various organic solvents, making it difficult to clean with solvents. There were drawbacks in terms of physical properties such as lack of durability.

[Means for Solving the Problems] The present invention has been completed as a result of studies to solve the problems, and is obtained by forming a pattern on a raw resin coated on a base material and heating and melting it. The present invention relates to a microlens, characterized in that the surface of the microlens is coated with a hardened resin, and a method for manufacturing the same.

To explain the present invention with reference to the drawings, FIG. 1 is a diagram showing the manufacturing process of the microlens of the present invention. Form layer 12. The intermediate layer has the function of maintaining the focal length of the microlens in order to efficiently position the focal point of the microlens on the sensor, and the function of making the distance between the lens and the sensor constant by forming a smooth surface. The material is cured by three-dimensional crosslinking using heat, active energy rays, etc.

The active energy rays of the present invention include electromagnetic waves such as infrared rays, visible rays, ultraviolet rays, and X-rays, radiation, and electron beams that have the energy to act on chemical substances and excite chemical reactions such as crosslinking and polymerization reactions. It is. In addition to irradiation with active energy rays, reactions such as crosslinking can also be caused by chemical conversion treatment using heat or various agents and catalysts.

Next, the lens material 13 is patterned (FIG. 1(C)). Pattern formation is performed to form a relief image on the resin that is the raw material for the microlens, and this involves irradiating the resin that is the raw material for the microlens with light through a predetermined photomask using a photosensitive resin. A photolithography method that directly obtains a relief image on the microlens material by developing it after exposure, or a photoresist coated separately from the resin that is the raw material for the microlens and irradiation with light through a predetermined photomask. After exposure and development, a relief image is formed on the photoresist, and then a relief image is formed by etching the raw material resin of the microlens, or a pattern of the raw material resin of the microlens is printed directly using a printing method. A relief image is formed.

Normally, when forming a fine pattern, a photolithography method is used, and in this case, a positive deep ultraviolet light-sensitive resin is used. As long as the pattern is rough, various pattern forming methods such as printing are possible.

In addition, with negative-tone photosensitive resins, the pattern is exposed by irradiating active energy rays such as light onto the areas where the resin should remain, so the properties of the jujube fir resin, which cross-links the resin, change due to exposure, and the resin is not sufficiently exposed. This is not preferable because it changes into a substance that cannot be melted.

Normally, when forming a fine pattern, a photolithography method is used, and in this case, a positive deep ultraviolet light-sensitive resin is used. As long as the pattern is rough, various pattern forming methods such as printing are possible.

Next, the substrate on which the lens material 13 is patterned is heated to heat and melt the pattern of the lens material to form the microlens 14 (FIG. 1(E)), but up to this step, the conventional thermal melting method is used. However, in the microlens of the present invention, a film of crosslinkable resin 15 that causes a crosslinking reaction by at least one of air, active energy rays, and chemical conversion treatment is further applied on the formed microlens. After forming on the surface by coating etc.
By at least one of active energy rays and chemical conversion treatment,
Curing the crosslinkable resin 15 by three-dimensional crosslinking or the like,
A microlens of the present invention is obtained.

As the resin used for the coating formed on the surface of the microlens, many transparent resins can be used as long as they have high physical and chemical strength due to curing through crosslinking reaction, polymerization reaction, etc. For example, a photothermosetting resin such as methyl methacrylate resin or a silicon-containing resist can be used.

Although a case has been described in which microlenses are formed using a transparent intermediate layer provided on the surface of a substrate such as a semiconductor as a base material, it goes without saying that similar microlenses can be directly formed using the substrate surface as a base material depending on the embodiment.

[Function] According to the present invention, since the surface of the microlens formed by thermal melting of the resin is coated with the hardened resin,
Microlenses manufactured by thermal melting can be prevented from remelting during heat treatment during the mounting process on equipment, and the surface is covered with hardened resin, which improves physical properties such as chemical resistance. There is.

[Example Example 1 Interline CCD (aperture ratio 20
%), a photosensitive acrylic resin was applied to a film thickness of 7 μm, prebaked by leaving it on a hot plate at 90°C for 10 minutes, exposed to ultraviolet light through the desired pattern, and then developed. Exclude the acrylic resin on the bonding pad and scribe line. Furthermore, it was left on a hot plate at 150° C. for 10 minutes to form an intermediate layer.

Next, methyl methacrylate (PMMA) was applied to a film thickness of 2 μm, and after being left on a hot plate at 120°C for 10 minutes, a cannon-filled mercury lamp was inserted through the desired pattern with accurate alignment. By exposing to far ultraviolet rays and developing, a PMMA pattern was formed that was accurately placed in the light receiving area, and the PMMA pattern was melted by leaving it on a hot plate at 150° C. for 60 minutes.

Furthermore, a negative deep ultraviolet-sensitive resin having a silicone resin as a main chain and a chloromethylated styrene as a side chain was added at 0%. 1
Coat the film to a thickness of μm, prebake by leaving on a hot plate at 70°C for 10 minutes, expose to UV light through the desired pattern, develop, and apply onto a bonding pad or scribe line. Excludes negative-type far-UV photosensitive resins.

The thus obtained solid-state image sensor with microlens was cut into chips and then washed with trichloroethane and isopropyl alcohol, but no change was observed, and the maximum heating temperature when molded and mounted was 17
Although the temperature was 0° C., no change in the shape of the microlens was observed. Furthermore, when photographing was carried out using this, the sensitivity was doubled and good images were obtained.

Example 2 A desired pattern is formed on a polarizing plate in which iodine is dispersed in polyvinyl alcohol using a transparent ink whose main component is a copolymer of acrylic acid and glycidyl methacrylate in which methacryloyl groups have been introduced into an oil-modified alkyd resin. A striped relief image with a film thickness of approximately 10 μm was printed using a silk screen plate, and then heated and melted in an oven at 120°C for 3 hours.
After cooling, urethane resin was applied to a thickness of 0.5 μm and heated in an oven at 100° C. for 30 minutes to harden the urethane resin.

In a liquid crystal cell in which liquid crystal is sandwiched between transparent electrode substrates consisting of an X-Y display, the above polarizing plate with microlens is pasted on the opposite side of the light source so that the axial direction of the microlens and the X direction of the liquid crystal cell are parallel. On the other hand, on the light source side, a microlens-equipped liquid crystal display element was formed by bonding a polarizing plate without microlens parallel to the polarization plane of the polarizing plate. The obtained microlens-equipped liquid crystal display element was immersed in methanol to clean the surface, but there was no change in the microlens.

On the other hand, lenses without a urethane resin coating peeled off.

When the microlens-equipped liquid crystal display element thus formed was turned on, the viewing angle increased from 140 degrees to 160 degrees when no microlenses were provided.

[Effects of the Invention] According to the present invention, since the surface is covered with resin hardened by three-dimensional crosslinking reaction, etc., remelting of microlenses manufactured by melting can be prevented and chemical resistance is improved. This is effective in increasing the amount of margin for each condition in the process after microlens manufacturing and improving long-term reliability.

[Brief explanation of the drawing]

FIG. 1 shows the manufacturing process of the microlens of the present invention,
Fig. 2 shows a cross section of a microlens formed by the conventional plate-making coating method and heat-melting method, Fig. 3 shows the light focusing principle of the microlens, and Fig. 4 shows a cross-section of a microlens formed by the conventional plate-making coating method and heat-melting method. A microlens is shown in the order of manufacturing steps, and FIG. 5 shows a conventional microlens manufactured by a plate-making coating method in the order of the manufacturing steps. DESCRIPTION OF SYMBOLS 11... Substrate, 12... Intermediate layer, 13... Lens material, 14... Microlens, 15... Crosslinkable resin, 16... Microlens, 21...
Convex lens, 22... Concave lens, 23... Invalid part,
24... Effective s, 30... Solid-state image sensor, 31
... Semiconductor substrate, 32 ... Transparent wL33 ... Microlens, 34 ... Light receiving s, 40 ... Solid-state image sensor, 41 ... Transparent film 42 ... Semiconductor substrate, 43
... K 44 ... Remaining film 45 ... Convex lens, 46 ... Light receiving @, 50 ... Solid-state image sensor, 51 ... Transparent film 52 ... Semiconductor substrate, 53 ...
...Photosensitive resin removal 54...Remaining 1i 55...
Clear resin removal 56... Light receiving part M1 Figure 3 Figure 5

Claims (3)

[Claims] (1) A microlens obtained by forming a pattern on a raw resin coated on a base material and heating and melting the resulting microlens, characterized in that the surface of the microlens is coated with a hardened resin. (2) The microlens according to claim 1, wherein the base material is a solid-state image sensor or a translucent material. (3) A resin that is cured by at least one of heat, active energy rays, and chemical conversion treatment is applied to the surface of the microlens obtained by forming a pattern on the resin coated on the base material and heating and melting it. A method for manufacturing a microlens, characterized by performing the following steps.