JP2023183381A - lens element - Google Patents

Abstract

The present invention provides a lens element having both a color separation function and a light condensing function, the lens element having a novel configuration. The lens element includes a substrate and a lens section, the lens section includes a plurality of microlenses arranged spaced apart from each other on the substrate, and the plurality of microlenses are configured to perform spectroscopy. A lens element comprising microlenses of two or more colors having different characteristics, the microlenses being made of a photocurable resin composition and having a convex curved surface on a surface not in contact with the substrate. [Selection diagram] Figure 1

Description

TECHNICAL FIELD The present invention relates to lens elements.

A solid-state imaging device that can be applied to a solid-state imaging device of a digital camera and a video camera has a plurality of photoelectric conversion elements that receive an optical image from an object to be imaged and convert the incident light into an electrical signal. As photoelectric conversion elements, CCD (Charge Coupled Device) type, CDMOS (Complementary Metal Oxide Semiconductor) type, etc. are known.

By providing a color filter that transmits light of a specific wavelength in the path of light that enters the photoelectric conversion element, solid-state imaging devices can acquire color information of the imaged object using the color separation function of the color filter. Make it. It is also known that in solid-state image sensors, in order to efficiently capture light into the light receiving part of the photoelectric conversion element, a microlens is provided to condense the light incident from the object to be imaged and guide it to the light receiving part of the photoelectric conversion element. It is being

Conventionally, color microlenses have been known that have both the color separation function of the above-mentioned color filters and the light-condensing function of the above-mentioned microlenses. Patent Document 1 describes a solid-state image sensor having a color microlens in which a lens shape is formed by a lithography method by applying a material containing a photopolymerizable negative photosensitive resin and a dye onto a substrate. There is.

International Publication No. 2019/220861

The color microlens described in Patent Document 1 is configured such that each lens portion is in contact with each other, and further includes a light-shielding film that suppresses color mixture between pixels and an inorganic film that covers the lens portion. The structure is as follows.

SUMMARY OF THE INVENTION An object of the present invention is to provide a lens element having both a color separation function and a light condensing function, and which has a novel configuration.

The present invention includes the following.
[1] A lens element having a substrate and a lens part,
The lens section includes a plurality of microlenses arranged spaced apart from each other on the substrate,
The plurality of microlenses include microlenses of two or more colors with different spectral characteristics,
The microlens is a lens element made of a photocurable resin composition and having a convex curved surface on a surface not in contact with the substrate.
[2] Further has a coating layer,
The lens element according to [1], wherein the coating layer covers at least a portion of the curved surfaces of the plurality of microlenses.
[3] The lens element according to [2], wherein the coating layer fills a space between the microlenses that are spaced apart from each other.
[4] The lens element according to [3], wherein the coating layer covers all surfaces of the plurality of microlenses that are not in contact with the substrate, and has a flat surface.
[5] The lens element according to any one of [2] to [4], wherein the coating layer has a refractive index lower than the refractive index of the microlens.
[6] The lens element according to any one of [2] to [5], wherein the coating layer has a refractive index of 1.1 or more.
[7] The lens element according to any one of [1] to [6], wherein the plurality of microlenses include green, blue, and red microlenses, or cyan, magenta, and yellow microlenses.
[8] A method for manufacturing the lens element according to any one of [2] to [7], comprising:
(a) arranging the plurality of microlenses on the substrate to form the lens portion;
a step (b1) of applying a coating layer-forming resin composition to the surface of the lens portion to form a coating film;
A manufacturing method comprising, in this order, a step (b2) of curing the coating film.
[9] The step (a) includes:
a step (a1) of applying the photocurable resin composition on the substrate to form a photocurable resin composition layer;
a step (a2) of selectively exposing the photocurable resin composition layer,
The manufacturing method according to [8], wherein in the step (a2), the photocurable resin composition layer is exposed with an exposure amount that is 2.0 times or more the saturation exposure amount.
[10] A resin composition for forming a coating layer used in the manufacturing method according to [8] or [9].
[11] A solid-state imaging device comprising the lens element according to any one of [1] to [7].
[12] A display device comprising the lens element according to any one of [1] to [7].

According to the lens element of the present invention, it has a lens section made up of a plurality of microlenses, and the lens section has a configuration that has both a color separation function and a light gathering function, and furthermore, it is possible to suppress color mixture between pixels. Since it has a simple configuration, it can perform multiple functions with a simple configuration.

FIG. 1 is a cross-sectional view schematically showing a lens element of a first embodiment. FIG. 3 is a diagram showing a plan view of the lens element of the first embodiment. FIG. 2 is a cross-sectional view schematically showing a microlens of the first embodiment. FIG. 7 is a cross-sectional view schematically showing a lens element of a second embodiment. It is a partial sectional view showing each manufacturing process of the lens element of a 2nd embodiment. FIG. 3 is a schematic diagram showing how light travels in a mode in which a lens element is arranged and used in a solid-state image sensor. FIG. 2 is a schematic diagram showing how light travels in an embodiment in which the lens composition is arranged and used in a display device.

The lens element of the present invention includes a substrate and a lens section, the lens section includes a plurality of microlenses arranged on the substrate and spaced apart from each other, and the plurality of microlenses have spectral characteristics. The microlens is made of a photocurable resin composition and has a convex curved surface on a surface not in contact with the substrate. EMBODIMENT OF THE INVENTION Hereinafter, the form for implementing this invention is demonstrated according to drawing.

[Lens element]
<First embodiment>
FIG. 1 is a cross-sectional view schematically showing a lens element 1 of the first embodiment. The lens element 1 includes a substrate 10 and a lens section 30. The lens section 30 includes a plurality of microlenses 31 arranged on the substrate 10 and spaced apart from each other. The plurality of microlenses 31 include microlenses of two or more colors having different spectral characteristics. The microlens 31 is made of a photocurable resin composition and has a convex curved surface 31a on the surface not in contact with the substrate 10.

Since the lens element 1 includes microlenses 31 of two or more colors, it has a color separation function that is a function of a color filter. Furthermore, since the lens element 1 includes a plurality of microlenses 31 having a convex curved surface 31a, it has a light-condensing function of condensing light incident from the curved surface 31a. Furthermore, since the lens element 1 has a configuration in which the plurality of microlenses 31 are arranged apart from each other, it has a function of suppressing color mixture. More specifically, in the lens section 30, since the plurality of microlenses 31 are arranged apart from each other, gaps (spaces between the microlenses) 30a exist between the microlenses 31. Color mixing may occur when light that has passed through one microlens 31 enters another microlens 31, but in the lens section 30 of the present invention, light that has passed through one microlens 31 enters another microlens 31. It is necessary for the light to pass through the gap 30a between the microlenses 31 before entering the light beam. That is, in order to transmit through two boundaries (the boundary between the first microlens 31 and the gap 30a, and the boundary between the gap 30a and the second microlens 31), the microlenses 31 are arranged in contact with each other. Unlike the configuration described in 1, since the light always passes through the gap 30a, it is possible to suppress the frequency with which the light that has passed through the first microlens 31 enters the other microlenses 31. Therefore, the lens element 1 has a function of suppressing color mixture. In this way, in the present invention, since the lens element 1 is configured to have multiple functions at the same time, it is possible to achieve a thin film while realizing multiple functions. Further, the configuration can be simplified while realizing multiple functions.

The plurality of microlenses 31 include microlenses of two or more colors having different spectral characteristics. As the plurality of microlenses 31, for example, a configuration including three colors of green (G), blue (B), and red (R), and a configuration including three colors of cyan (C), magenta (M), and yellow (Y) are used. Examples include a configuration including four colors, cyan (C), magenta (M), yellow (Y), and green (G).

FIG. 2 is a diagram showing a plan view of the lens section 30. The shape of the microlens 31 in plan view can be adjusted by the shape of the photomask used in the exposure step in the method for manufacturing the lens portion 30, and may be, for example, square, rectangular (for example, FIG. 2), circular, or elliptical. It may be.

FIG. 3 shows a cross-sectional view of one microlens 31 in the lens section 30. In any cross-sectional view of the microlens 31, the lens width W1 in contact with the substrate 10 is preferably 200 μm or less, more preferably 100 μm or less, further preferably 1 μm or more, and more preferably 2 μm or more. The lens width W1 may be the same or different in all cross sections. When the microlens 31 is rectangular in plan view, the lens width W1 has different values depending on the cross section. It is preferable that there is at least one cross section that satisfies the numerical range of the above-mentioned suitable lens width W1, and it is more preferable that it is satisfied for any cross section. The length of the gap 30a (FIG. 1) between the microlenses 31 in the lens portion 30 can be appropriately designed depending on the use of the lens element 1, but from the viewpoint of suppressing color mixture, it is important to The cross-sectional length (width) of the gap 30a with respect to the cross-sectional length (width) of the lens 31 is preferably 0.1 times or more and 1 time or less, more preferably 0.2 times or more and 0.8 times or less. preferable. The cross-sectional length (width) of the gap 30a is preferably 0.5 μm or more, more preferably 1.0 μm or more. The cross-sectional length (width) of the gap 30a is, for example, 200 μm or less. The cross-sectional length (width) of the gap 30a may be the same or different in all cross-sections, and may not be the same in all cross-sections. For example, the cross-sectional length (width) may be different depending on the arrangement direction of the microlenses 31. In FIG. 2, there is an example in which the cross-sectional length (width) of the gap 30a in the vertical arrangement of the microlenses 31 is longer than the cross-sectional length (width) of the gap 30a in the horizontal arrangement of the microlenses 31. It is shown.

In the microlens 31, the ratio (W2/W1) of the lens width W2 at a height H of 90% of the lens height from the substrate surface to the lens width W1 in contact with the substrate 10 is preferably 0.7 or less, It is more preferably 0.6 or less, more preferably 0.4 or more, and even more preferably 0.5 or more. By setting the ratio (W2/W1) within the above range, it is possible to improve the function as a microlens.

According to the manufacturing method described below, it is possible to easily obtain a lens portion in which the lens width W1 and ratio (W2/W1) of each microlens are within the above ranges.

The lens element 1 of this embodiment can be used for the same purpose as a conventional lens element having a plurality of microlenses. For example, it can be used by being placed in a solid-state image sensor. In a solid-state image sensor, it can be used by stacking it on a photoelectric conversion element layer consisting of a plurality of photoelectric conversion elements, and furthermore, a microlens is arranged to correspond to each photoelectric conversion element, and photoelectric conversion is performed through the microlens. By configuring so that light is incident on the conversion element, it is possible to condense light of a desired color and make it incident on each photoelectric conversion element. Although the specific form of the solid-state image sensor is not particularly limited, for example, a plurality of photos forming the light receiving area of the solid-state image sensor (such as a CCD image sensor, a CMOS image sensor, or an organic CMOS image sensor) on a substrate may be used. It is possible to configure a plurality of photoelectric conversion elements made of diodes, polysilicon, etc., and arrange microlenses so as to correspond to each photoelectric conversion element.

The lens element 1 of this embodiment can be used by being placed in a display device, for example. In a display device, it can be used by stacking on a display element layer consisting of a plurality of display elements, and furthermore, microlenses are arranged to correspond to each display element, and light from the display elements is transmitted through the microlenses. By configuring the light to be emitted, it is possible to generate a color image and simultaneously improve light utilization efficiency. The specific form of the display device is not particularly limited, but can be used, for example, as a liquid crystal display device, an organic EL display device, etc. Also, micro LEDs, micro OLEDs, etc., which can enlarge and display images by projection, etc. It can be used for.

<Second embodiment>
FIG. 4 is a cross-sectional view schematically showing the lens element 2 of the second embodiment. The lens element 2 has a structure that further includes a coating layer 40 in addition to the structure of the lens element 1 of the first embodiment. The configuration other than the coating layer 40 is the same as the configuration of the lens element 1 of the first embodiment, so a description thereof will be omitted.

The coating layer 40 has a structure that covers at least a portion of the curved surfaces 31a of the plurality of microlenses 31, and has the effect of protecting the plurality of microlenses 31 and the lens section 30 due to this structure. Further, the covering layer 40 is preferably a continuous layer that connects the plurality of microlenses 31 to each other, and this structure has the effect of suppressing the separation of each microlens 31 from the substrate 10. Further, as shown in FIG. 4, the coating layer 40 preferably fills the gaps 30a between the microlenses 31 arranged on the substrate 10 at a distance from each other, and more preferably, a plurality of coating layers 40 This structure covers all surfaces of the microlens 31 that are not in contact with the substrate 10. With such a configuration, the contact area between the microlens 31 and the coating layer 40 can be increased, making it easier to suppress peeling between the layers.

In such a configuration, by appropriately adjusting the refractive index of the material forming the coating layer 40, the incidence efficiency of light on the curved surface 31a of the microlens 31 is improved, and light leaks from the side surface of the microlens 31 to the coating layer 40. It has the effect of suppressing In addition, in such a configuration, by appropriately adjusting the refractive index of the material forming the coating layer 40, light incident on the microlens 31 from the lower surface facing the curved surface 31a of the microlens 31 can be transmitted from the side surface to the coating layer 40. leakage of light can be suppressed, and the light output efficiency from the curved surface 31a can be improved. Note that color mixing can be prevented by suppressing light leakage from the side surface of the microlens 31 to the coating layer 40.

The refractive index of the coating layer 40 is preferably lower than the microlens 31 (than any of the plurality of microlenses 31) and higher than air. By adjusting the refractive index in this way, the light incident on the microlens 31 is easily totally reflected at the interface between the microlens 31 and the coating layer 40, and the efficiency of light utilization can be improved. The refractive index of the coating layer 40 is preferably 1.10 or more, more preferably 1.20 or more. The refractive index of the coating layer 40 is preferably 1.60 or less, more preferably 1.49 or less, even more preferably 1.45 or less. In addition, in the present invention, the refractive index of the coating layer means the refractive index at a wavelength of 589 nm.

FIG. 6 is a diagram schematically showing that leakage of light to the coating layer 40 can be suppressed in an embodiment in which the lens element 1 is arranged and used in a solid-state image sensor. In an embodiment in which the lens element 1 is arranged and used in a solid-state image sensor, light enters from the curved surface 31a of the macro lens 31. Even if the light reaches the side surface 31b within the microlens 31, the light is totally reflected at the interface between the microlens 31 and the coating layer 40, thereby suppressing leakage of the light to the coating layer 40. be able to.

FIG. 7 is a diagram schematically showing that leakage of light to the coating layer 40 can be suppressed in an embodiment in which the lens element 1 is arranged and used in a display device. In a mode in which the lens element 1 is placed and used in a display device, light enters the microlens from the lower surface 31c facing the curved surface 31a. Even if the light reaches the side surface 31b within the microlens 31, the light is totally reflected at the interface between the microlens 31 and the coating layer 40, thereby suppressing leakage of the light to the coating layer 40. be able to.

It is preferable that the surface 40a of the coating layer 40 on the side opposite to the substrate 10 is flat (the difference in height is small). The higher the flatness is, the more the ratio of light reflected on the surface 40a of the coating layer 40 can be reduced, and the efficiency of light utilization can be improved. Regarding the degree of flatness, for example, if L is the distance from the surface of the substrate 10 to the surface 40a of the coating layer 40, the minimum value of L is preferably 1/2 or more of the maximum value of L, and 2/ More preferably, it is 3 or more. In this specification, it is assumed that the surface 40a of the coating layer 40 is flat when the minimum value of L is 1/2 or more of the maximum value of L. The coating layer 40 preferably has a surface roughness of 20 nm or less on the surface 40a opposite to the substrate 10, more preferably 10 nm or less.

[Lens element manufacturing method]
An example of a method for manufacturing the lens element 2 of the second embodiment will be described. FIG. 4 shows a lens element 2 in which the lens portion 30 has three color microlenses 31 (referred to as "microlens 31A", "microlens 31B", and "microlens 31C", respectively). A manufacturing method for forming microlenses 31A, microlenses 31B, and microlenses 31C in this order in the lens portion 30 will be specifically described. The microlens 31A, the microlens 31B, and the microlens 31C each have different spectral characteristics and are formed from different photocurable resin compositions A, photocurable resin composition B, and photocurable resin composition C. shall be taken as a thing. For example, the photocurable resin compositions A, B, and C may be resin compositions that differ only in the type of colorant contained and otherwise have the same composition; the colorant, resin, polymerizable compound, and light All types of polymerization initiators may be different. The refractive index of the microlenses 31A, 31B, and 31C formed from the photocurable resin compositions A, B, and C is preferably 1.50 or more, and more preferably 1.60 or more. The refractive index of the microlenses 31A, 31B, and 31C is preferably 1.80 or less. The microlenses 31A, 31B, and 31C may have the same or different refractive indexes. Note that in the present invention, the refractive index of the microlens may mean the refractive index at a wavelength at which the transmittance is maximum in the visible light region of 380 nm to 780 nm, and may be compared with the refractive index of the coating layer 40. It may also mean the refractive index at a wavelength of 589 nm.

The lens element 2 includes, in order, a step (a) of arranging a plurality of microlenses 31A, 31B, and 31C on a substrate 10 to form a lens portion 30, and a step (b) of forming a coating layer 40. .

The lens element 1 of the first embodiment has at least the step (a) of arranging a plurality of microlenses 31A, 31B, and 31C on the substrate 10 to form the lens portion 30.

<Lens portion forming step: step (a)>
Step (a) includes a step of sequentially forming microlenses 31A, 31B, and 31C on the substrate 10. This process will be explained.

First, as shown in FIG. 5(a), a photocurable resin composition A is applied onto the substrate 10 to form a photocurable resin composition layer 20A (photocurable resin composition layer forming step, Step (a1)). The photocurable resin composition layer 20A is dried as necessary. Thereafter, as shown in FIG. 5(b), the photocurable resin composition layer 20A is selectively exposed (exposure step, step (a2)). In FIG. 5(b), the selectively exposed region in the photocurable resin composition layer 20A is shown as a region 21A. Selective exposure of the photocurable resin composition layer 20A can be performed, for example, by irradiating light through the photomask 50 or by irradiating light in spots. In the exposure step, the photocurable resin composition layer 20A is exposed with an exposure amount that is 2.0 times or more the saturation exposure amount. Thereafter, the photocurable resin composition layer 21A is developed (development step). A post-bake step may be provided after the development step, and the post-bake step may be performed following the development step. Through the above steps, the microlens 31A is formed on the substrate 10, as shown in FIG. 5(c).

Next, microlenses 31B are formed on the substrate 10. The microlenses 31B are formed by forming a photocurable resin composition layer on the substrate 10 on which the microlenses 31A are formed, using the photocurable resin composition B, by the same method as for forming the microlenses 31A described above. , an exposure step, and a development step in this order.

Next, a microlens 31C is formed on the substrate 10. The microlens 31C is formed by applying a photocurable resin composition C onto the substrate 10 on which the microlenses 31A and 31B are formed, using the same method as for forming the microlens 31A described above. It is formed by sequentially performing a material layer forming step, an exposure step, and a development step. Each step of forming the microlens 31A will be described in more detail below. The same applies to the details of each forming process of the microlenses 31B and 31C.

<Photocurable resin composition layer formation process>
The photocurable resin composition is not limited as long as it has the property of being polymerized by light irradiation in the exposure step and that the unexposed portion is eluted by development in the development step. Concerning the photocurable resin composition, specific examples will be shown later.

The substrate 10 may be a glass plate such as quartz glass, borosilicate glass, alumina silicate glass, or soda lime glass whose surface is coated with silica, a resin plate such as polycarbonate, polymethyl methacrylate, or polyethylene terephthalate, silicon, or the above substrate. A material on which a thin film of aluminum, silver, silver/copper/palladium alloy, etc. is formed is used.

Examples of the method for applying the photocurable resin composition include an extrusion coating method, a direct gravure coating method, a reverse gravure coating method, a CAP coating method, and a die coating method. Further, coating may be performed using a coater such as a dip coater, a bar coater, a spin coater, a slit and spin coater, a slit coater (sometimes referred to as a die coater, a curtain flow coater, or a spinless coater), or a roller. Among these, it is preferable to apply using a spin coater.

Examples of methods for drying the photocurable resin composition layer 20A include natural drying, ventilation drying, and vacuum drying. Specific heating temperatures include about 30 to 120°C, preferably about 60 to 100°C. The heating time is suitably about 10 seconds to 60 minutes, preferably about 30 seconds to 30 minutes. For example, the vacuum drying is performed under a pressure of about 50 to 150 Pa and at a temperature of about 20 to 25°C. When the photocurable resin composition contains a solvent, the solvent can be removed by the above-mentioned drying.

The thickness of the photocurable resin composition layer 20A is not particularly limited, and can be adjusted as appropriate depending on the material used, the purpose of the lens element, etc. For example, the thickness after drying is about 0.1 to 30 μm, preferably 0. For example, the thickness is about .1 to 20 μm, more preferably about 0.3 to 10 μm, and still more preferably about 0.5 to 10 μm.

<Exposure process>
Selective exposure of the photocurable resin composition layer 20A can be performed by exposing through a photomask 50, for example. As the photomask 50, a mask is used in which a light-shielding portion is formed corresponding to a portion to be removed according to a desired pattern. The light source used for exposure may be a light source with a wavelength exceeding 300 nm or a light source with a wavelength of 300 nm or less. For example, light of less than 350 nm can be cut using a filter that cuts this wavelength range, or light around 436 nm, 408 nm, and 365 nm can be selectively extracted using a band pass filter that extracts these wavelength ranges. You can also Alternatively, 248 nm (KrF line), 193 nm (ArF line), etc. may be used. Examples of the light source include a mercury lamp, a light emitting diode, a metal halide lamp, a halogen lamp, and an excimer laser such as a KrF excimer laser and an ArF excimer laser. An exposure device such as a mask aligner or a stepper can be used to uniformly irradiate the entire exposure surface with parallel light and to accurately align the photomask 50 and the photocurable resin composition layer 20A. is preferred.

Here, the photocurable resin composition layer 20A is exposed with an exposure amount that is 2.0 times or more the saturation exposure amount. The photocurable resin composition layer 20A has a different residual film rate in the development step depending on the exposure amount in the exposure step. In the photocurable resin composition layer 20A, the residual film rate increases as the exposure dose increases, and after the residual film rate reaches 100%, the residual film rate remains at 100% even if the exposure dose increases. becomes. The remaining film rate is calculated by the following formula (1).
Remaining film rate (%) = (film thickness after development / film thickness before development) x 100 (1)

In this specification, the saturation exposure amount of the photocurable resin composition layer 20A is the minimum exposure amount (hereinafter also referred to as "absolute minimum exposure amount") at which the residual film rate is 95% or more and 100% or less. In actual measurement, the exposure amount is increased stepwise to measure the minimum measurement exposure amount (hereinafter also referred to as "measured minimum exposure amount"). Specifically, when the exposure amount is increased stepwise and the remaining film rate exceeds 95% for the first time when exposed at the exposure amount a and then exposed at the next larger exposure amount b, the remaining film rate is determined. The measured minimum exposure amount for which the value is 95% or more and 100% or less is measured as b, and therefore it can be seen that the absolute minimum exposure amount x is a value that satisfies a<x<b. By adjusting the exposure amount in the exposure step to be at least twice b, it is possible to make it at least twice the saturation exposure amount x. That is, if the measured minimum exposure amount b has been obtained, it is not necessarily necessary to determine the absolute minimum exposure amount x that corresponds to the saturated exposure amount. The measurement minimum exposure amount b can be measured, for example, by the following method.

(Measurement of measurement minimum exposure amount b)
A photocurable resin composition having the same thickness as that of the photocurable resin composition layer 20A obtained by applying a photocurable resin composition having the same composition onto the substrate using the same coating method and drying under the same conditions. The layer was exposed using an exposure machine (TME-150RSK; manufactured by Topcon Co., Ltd., light source: ultra-high pressure mercury lamp) at an exposure dose (365 nm standard) in the range of 1 mJ/cm ² to 500 mJ/cm ² in an atmospheric atmosphere. The light is irradiated at 11 levels (1, 10, 15, 20, 40, 60, 100, 150, 200, 300, 500). Note that this light irradiation is performed by passing the emitted light from an ultra-high pressure mercury lamp through an optical filter (UV-31; manufactured by Asahi Techno Glass Co., Ltd.). The thickness of the photocurable resin composition layer after light irradiation is measured and taken as the film thickness before development. A cured film is obtained by developing with the same developer and the same development conditions as in the development step, and performing post-baking. The thickness of this cured film is measured and used as the film thickness after development. The film thickness before development and the film thickness after development are measured using a contact film thickness measuring device (DEKT AK6M, manufactured by ULVAC Co., Ltd.).

In the above measurement, for example, if the residual film rate is 93% when the exposure dose is 60 mJ/ ^cm2 , and the residual film rate is 99% when the exposure dose is 100 mJ/ ^cm2 , then the residual film rate in the actual measurement is The minimum measured exposure amount b at which the film ratio is 95% or more and 100% or less is 100 mJ/cm ² .

Therefore, when the measured minimum exposure amount b is 100 mJ/cm ² , the photocurable resin composition layer 20A should be exposed in the exposure step with an exposure amount of 200 mJ/cm ² or more, which is more than twice the measured minimum exposure amount b. Therefore, exposure can be performed with an exposure amount that is twice or more than the saturation exposure amount.

By adjusting the exposure amount of the photocurable resin composition layer 20A in the exposure step within a range exceeding the saturation exposure amount, the shape of the surface of each dot can be adjusted with respect to the dot pattern obtained through the development step, When the exposure amount is 2.0 times or more the saturation exposure amount, dots having a convex surface that can function as a lens can be obtained.

The exposure amount of the photocurable resin composition layer 20A is not particularly limited as long as it is 2.0 times or more the saturated exposure amount, but it is 2.1 times or more, 2.2 times the saturated exposure amount. As mentioned above, the amount may be 2.3 times or more, and preferably 3.0 times or less the saturation exposure amount.

<Developing process>
After the exposure step, a development step is performed to develop the photocurable resin composition layer 20A. By bringing the exposed photocurable resin composition layer 20A into contact with a developer and developing the photocurable resin composition layer 20A, the unexposed portion of the photocurable resin composition layer 20A is dissolved in the developer and removed, and is deposited on the substrate 10. A photocurable resin composition layer 20A having a pattern is formed. As the developer, an aqueous solution of an alkaline compound such as potassium hydroxide, sodium bicarbonate, sodium carbonate, or tetramethylammonium hydroxide is preferred. The concentration of these alkaline compounds in the aqueous solution is preferably 0.01 to 10% by mass, more preferably 0.03 to 5% by mass. Furthermore, the developer may contain a surfactant. The developing method may be any of the paddle method, dipping method, spray method, etc. Furthermore, the substrate 10 may be tilted at an arbitrary angle during development. After development, it is preferable to wash with water.

<Post-bake process>
After the development process, a curing process may be performed by a post-exposure process using, for example, light with a wavelength of 254 to 350 nm, or a curing process may be performed by a post-baking process. Preferably, the photocurable resin composition layer 20A is washed with water and then subjected to a post-baking process. The post-bake step is preferably performed after washing with water after the development step, since the time required for production can be shortened. By performing a post-baking process, the durability (solvent resistance) of the lens can be improved.

The post-bake step is a step of heating the photocurable resin composition layer 20A on the substrate. Heating is usually performed using a heating device such as an oven or a hot plate. The heating temperature is preferably 60 to 260°C. When the heating temperature is set to such a temperature, unnecessary solvent can be prevented from remaining in the film. The heating time is preferably 1 to 120 minutes, more preferably 10 to 60 minutes.

[Photocurable resin composition]
As mentioned above, the photocurable resin composition used in the method for producing a lens of the present invention has the property of being polymerized by light irradiation in the exposure step, and that unexposed areas are eluted by development in the development step. It is not limited as long as it has desired spectral characteristics. Hereinafter, one form of the photocurable resin composition suitably used in the present invention will be described. The compounds exemplified as each component can be used alone or in combination, unless otherwise specified.

The photocurable resin composition of the present embodiment includes a resin (hereinafter referred to as resin (A)), a polymerizable compound (hereinafter referred to as polymerizable compound (C)), a photopolymerization initiator (hereinafter referred to as photopolymerization (hereinafter referred to as a polymerization initiator (D)), a colorant, and a solvent (hereinafter referred to as a solvent (E)). Furthermore, it may contain a polymerization initiation aid (hereinafter referred to as a polymerization initiation aid (H)).

<Resin (A)>
The resin (A) is preferably an alkali-soluble resin, and the structural unit (Aa) derived from at least one selected from the group consisting of unsaturated carboxylic acids and unsaturated carboxylic acid anhydrides (hereinafter referred to as "constituent units (Aa)") ) is more preferable. It is more preferable that the resin (A) further includes a structural unit (Ab) having a carbazole ring (hereinafter referred to as "structural unit (Ab)"). In addition, in this specification, "(meth)acrylic acid" represents at least one type of compound selected from the group consisting of acrylic acid and methacrylic acid. Notations such as "(meth)acryloyl" and "(meth)acrylate" have similar meanings.

Specifically, the monomer leading to the structural unit (Aa) includes, for example,
Unsaturated monocarboxylic acids such as acrylic acid, methacrylic acid, crotonic acid, o-, m-, p-vinylbenzoic acid;
Maleic acid, fumaric acid, citraconic acid, mesaconic acid, itaconic acid, 3-vinylphthalic acid, 4-vinylphthalic acid, 3,4,5,6-tetrahydrophthalic acid, 1,2,3,6-tetrahydrophthalic acid, dimethyl Unsaturated dicarboxylic acids such as tetrahydrophthalic acid and 1,4-cyclohexenedicarboxylic acid;
Unsaturated dicarboxylic acid anhydrides such as maleic anhydride, citraconic anhydride, itaconic anhydride, vinyl phthalic anhydride, and tetrahydrophthalic anhydride;
Examples include unsaturated acrylates containing a hydroxy group and a carboxy group in the same molecule, such as α-(hydroxymethyl)acrylic acid.
Among these, acrylic acid, methacrylic acid, and the like are preferred from the viewpoint of copolymerization reactivity and the solubility of the resulting resin in an aqueous alkali solution.

Specific examples of the monomer leading to the structural unit (Ab) include unsaturated compounds having a carbazole ring. When the resin (A) contains the structural unit (Ab), the refractive index of the obtained film can be improved.

The unsaturated compound having a carbazole ring is preferably a compound represented by formula (III).

[In formula (III), R ¹ represents a hydrogen atom, a methyl group, or a hydroxymethyl group.
R ² to R ⁹ each independently represent a hydrogen atom, a halogen atom, a saturated hydrocarbon group having 1 to 20 carbon atoms, or an aryl group having 6 to 20 carbon atoms, and the hydrogen atoms contained in the saturated hydrocarbon group are , an alkoxy group or an aryl group.
X is a single bond, an alkanediyl group having 1 or more carbon atoms, or -CO(-O-X ⁰ )m-(X ⁰ represents an alkanediyl group having 1 or more carbon atoms, and m represents an integer of 0 or more ).

Examples of the compound represented by formula (III) include N-vinylcarbazole, N-allylcarbazole, N-(meth)acryloylcarbazole, 2-(9-carbazolyl)ethyl(meth)acrylate, 2-(9-carbazolyl) Examples include ethoxyethyl (meth)acrylate, 2-(9-carbazolyl)-2-methylethyl (meth)acrylate, and 2-(9-carbazolyl)-1-methylethyl (meth)acrylate.

The resin (A) may have a structural unit (Ac) different from the structural unit (Aa) and the structural unit (Ab).

The structural unit (Ac) is a structural unit derived from an unsaturated compound having a cyclic ether structure having 2 to 4 carbon atoms (for example, at least one selected from the group consisting of an oxirane ring, an oxetane ring, and a tetrahydrofuran ring); Examples include structural units having an ethylenically unsaturated bond in the chain and other structural units.

Examples of the unsaturated compound having a cyclic ether structure having 2 to 4 carbon atoms (for example, at least one selected from the group consisting of an oxirane ring, an oxetane ring, and a tetrahydrofuran ring) include glycidyl (meth)acrylate, β-methylglycidyl (meth)acrylate, glycidyl vinyl ether, glycidyloxymethylstyrene; vinylcyclohexene monooxide, 1,2-epoxy-4-vinylcyclohexane (e.g. Celoxide 2000; manufactured by Daicel Corporation), 3,4-epoxycyclohexylmethyl (meth) ) acrylate (for example, Cyclomer A400; manufactured by Daicel Corporation), 3,4-epoxycyclohexylmethyl (meth)acrylate (for example, Cyclomer M100; manufactured by Daicel Corporation), 3,4-epoxytricyclo[5 .2.1.0 ^2,6 ] Decyl (meth)acrylate; 3-methyl-3-(meth)acryloyloxymethyloxetane, 3-ethyl-3-(meth)acryloyloxymethyloxetane; Tetrahydrofurfuryl (meth) ) acrylate, etc.

The structural unit having a structural unit having an ethylenically unsaturated bond in the side chain can be obtained by adding an unsaturated compound having a cyclic ether structure having 2 to 4 carbon atoms to a copolymer containing the structural unit (Aa), or adding an unsaturated compound having a cyclic ether structure having 2 to 4 carbon atoms. It can be produced by adding an unsaturated carboxylic acid to a copolymer containing a structural unit derived from an unsaturated compound having 2 to 4 cyclic ether structures. The latter resin may be further reacted with a carboxylic acid anhydride.

Examples of monomers leading to other structural units include:
Methyl (meth)acrylate, butyl (meth)acrylate cyclohexyl (meth)acrylate, 2-methylcyclohexyl (meth)acrylate, tricyclo[5.2.1.0 ^2,6 ]decane-8-yl (meth)acrylate, tricyclo [5.2.1.0 ^2,6 ]Decen-8-yl (meth)acrylate, benzyl (meth)acrylate, 2-hydroxyethyl (meth)acrylate N-phenylmaleimide, N-cyclohexylmaleimide, N-benzylmaleimide , styrene, vinyltoluene and the like.

The weight average molecular weight (Mw) of the resin (A) in terms of polystyrene is preferably 3,000 to 100,000, more preferably 5,000 to 50,000, even more preferably 5,000 to 20,000, particularly preferably is between 5,000 and 10,000. When the weight average molecular weight (Mw) of the resin (A) is within the above range, the coating properties of the photocurable resin composition tend to be good.

The dispersity [weight average molecular weight (Mw)/number average molecular weight (Mn)] of the resin (A) is preferably 1.1 to 6.0, more preferably 1.2 to 4.0. When the degree of dispersion is within the above range, the resulting film tends to have excellent chemical resistance.

The acid value of the resin (A) is preferably 30 mg-KOH/g or more and 180 mg-KOH/g or less, more preferably 40 mg-KOH/g or more and 150 mg-KOH/g or less, and even more preferably 50 mg-KOH/g or more and 135 mg or less. -KOH/g or less. Here, the acid value is a value measured as the amount (mg) of potassium hydroxide required to neutralize 1 g of resin, and can be determined by titration using an aqueous potassium hydroxide solution. When the acid value of the resin (A) is within the above range, the resulting film tends to have excellent adhesion to the substrate.

The content of the resin (A) in the photocurable resin composition of the present invention is preferably 5% by mass or more and 70% by mass or less, more preferably 5% by mass or more and 70% by mass or less, based on the total solid content of the photocurable resin composition of the present invention. is 10% by mass or more and 60% by mass or less, more preferably 15% by mass or more and 55% by mass or less. When the content of the resin (A) is within the above range, the resulting film tends to have excellent heat resistance, as well as excellent adhesion to the substrate and chemical resistance. Here, the solid content of the photocurable resin composition refers to the amount obtained by subtracting the content of the solvent (E) from the total amount of the photocurable resin composition of the present invention.

<Polymerizable compound (C)>
The polymerizable compound (C) is a monomer that reacts with heat or the action of a photopolymerization initiator (D), and examples of the monomer include compounds having an ethylenically unsaturated bond, preferably (meth)acrylic. Examples include acid ester compounds.

The polymerizable compound is preferably a (meth)acrylic compound having three or more (meth)acryloyl groups, such as trimethylolpropane tri(meth)acrylate, pentaerythritol tri(meth)acrylate, pentaerythritol tetra(meth)acrylate, More preferred are dipentaerythritol penta(meth)acrylate and dipentaerythritol hexa(meth)acrylate.
The weight average molecular weight of the polymerizable compound (C) is preferably 150 or more and 2,900 or less, more preferably 250 or more and 1,500 or less.

The content of the polymerizable compound (C) in the photocurable resin composition of the present invention may be, for example, 1% by mass or more and 99% by mass or less, based on the total solid content of the photocurable resin composition. The content is preferably 5% by mass or more and 90% by mass or less, more preferably 8% by mass or more and 80% by mass or less, and still more preferably 10% by mass or more and 70% by mass or less. When the content of the polymerizable compound (C) is within the above range, the resulting film can have good chemical resistance and mechanical strength.

<Photopolymerization initiator (D)>
The photopolymerization initiator (D) is not particularly limited as long as it is a compound that generates active radicals, acids, etc. by the action of light and can initiate polymerization of the polymerizable compound (C), and may be any known photopolymerization initiator. Agents can be used. The photopolymerization initiator (D) is preferably a photopolymerization initiator containing at least one selected from the group consisting of O-acyloxime compounds, alkylphenone compounds, triazine compounds, acylphosphine oxide compounds, and biimidazole compounds; - A photopolymerization initiator containing an acyloxime compound is more preferred. These photopolymerization initiators tend to have high sensitivity and high transmittance in the visible light region.
Examples of such photopolymerization initiators include N-benzoyloxy-1-(4-phenylsulfanylphenyl)butan-1-one-2-imine, N-benzoyloxy-1-(4-phenylsulfanylphenyl) Octan-1-one-2-imine, N-benzoyloxy-1-(4-phenylsulfanylphenyl)-3-cyclopentylpropan-1-one-2-imine, 2-methyl-2-morpholino-1-(4 -methylsulfanylphenyl)propan-1-one, 2-dimethylamino-1-(4-morpholinophenyl)-2-benzylbutan-1-one, 1-hydroxycyclohexylphenylketone, 2,4-bis(trichloromethyl) -6-Piperonyl-1,3,5-triazine, 2,4,6-trimethylbenzoyldiphenylphosphine oxide, 2,2'-bis(2-chlorophenyl)-4,4',5,5'-tetraphenylbi Examples include imidazole.

The content of the photopolymerization initiator (D) in the photocurable resin composition of the present invention is preferably 0.1 mass parts with respect to 100 parts by mass of the total amount of the resin (A) and the polymerizable compound (C). parts or more and 30 parts by mass or less, more preferably 0.3 parts by mass or more and 20 parts by mass or less. When the content of the photopolymerization initiator (D) is within the above range, the transmittance of the visible light transmitting portion of the resulting pattern tends to be high.

<Polymerization initiation aid (H)>
The polymerization initiation aid (H) is a compound used together with the photopolymerization initiator (D) to promote the polymerization of the polymerizable compound (C) whose polymerization has been initiated by the photopolymerization initiator (D), or a polymerization promoter. It is a sensitizing agent. When a polymerization initiation aid (H) is included, it is usually used in combination with a photopolymerization initiator (D).

Examples of the polymerization initiation aid (H) include 4,4'-bis(dimethylamino)benzophenone (commonly known as Michler's ketone), 4,4'-bis(diethylamino)benzophenone, 9,10-dimethoxyanthracene, and 2,4-diethylthioxanthone. , N-phenylglycine, and the like.

When the photocurable resin composition of the present invention contains the polymerization initiation aid (H), the content is preferably based on 100 parts by mass of the total content of the resin (A) and the polymerizable compound (C). is 0.1 parts by mass or more and 30 parts by mass or less, more preferably 0.2 parts by mass or more and 10 parts by mass or less. When the amount of the polymerization initiation aid (H) is within the above range, the sensitivity tends to be even higher when forming a pattern.

<Colorant>
The colorant includes at least one selected from the group consisting of dyes and pigments. The colorant preferably comprises a combination of two dyes or a combination of at least one dye and at least one pigment, more preferably a combination of two dyes or one dye and one pigment. including combinations of

As the dye, known dyes can be used, including solvent dyes, acid dyes, direct dyes, mordant dyes, etc. For example, in Color Index (published by The Society of Dyers and Colourists), solvent, acid, basic, Examples include compounds classified as dyes such as reactive, direct, disperse, mordant, or bat, and known dyes described in Dyeing Notes (Shirosensha). The dye may be appropriately selected depending on the desired spectral characteristics of the microlens array. These dyes may be used alone or in combination of two or more. The dye is preferably an organic solvent soluble dye. Examples of pigments include organic pigments and inorganic pigments, including compounds classified as pigments in the Color Index (published by The Society of Dyers and Colourists).

<Solvent (E)>
The photocurable resin composition of the present invention contains a solvent (E). The solvent (E) is not particularly limited, and includes solvents commonly used in the field. For example, ester solvents (solvents that contain -COO- but no -O- in the molecule), ether solvents (solvents that contain -O- but no -COO- in the molecule), and ether ester solvents (solvents that contain -O- but no -COO- in the molecule). solvents containing -COO- and -O-), ketone solvents (solvents containing -CO- in the molecule but not -COO-), alcohol solvents (solvents containing OH in the molecule, -O-, - (CO- and -COO--free solvents), aromatic hydrocarbon solvents, amide solvents, dimethyl sulfoxide, and the like.

Solvents include methyl lactate, ethyl lactate, butyl lactate, methyl 2-hydroxyisobutanoate, ethyl acetate, n-butyl acetate, isobutyl acetate, pentyl formate, isopentyl acetate, butyl propionate, isopropyl butyrate, ethyl butyrate, butyl butyrate, Ester solvents of methyl pyruvate, ethyl pyruvate, propyl pyruvate, methyl acetoacetate, ethyl acetoacetate, cyclohexanol acetate and γ-butyrolactone;

Ether solvents such as ethylene glycol monobutyl ether, diethylene glycol monomethyl ether 3-methoxy-3-methylbutanol diethylene glycol dimethyl ether diethylene glycol ethyl methyl ether; ethyl 3-methoxypropionate, methyl 3-ethoxypropionate, 3-methoxybutyl acetate, propylene glycol monomethyl Ether ester solvents such as ether acetate, ethylene glycol monoethyl ether acetate, diethylene glycol monoethyl ether acetate; 4-hydroxy-4-methyl-2-pentanone heptanone, 4-methyl-2-pentanone, cyclopentanone, cyclohexanone, etc. alcohol solvents such as butanol and hexanol propylene glycol; amide solvents such as N,N-dimethylformamide, N,N-dimethylacetamide and N-methylpyrrolidone.
More preferred solvents include propylene glycol monomethyl ether acetate, propylene glycol monomethyl ether, ethyl lactate, ethyl 3-ethoxypropionate and 4-hydroxy-4-methyl-2-pentanone.

As the solvent, propylene glycol monomethyl ether acetate, propylene glycol monomethyl ether, ethyl 3-ethoxypropionate, ethyl lactate, ethylene glycol ethyl methyl ether, cyclohexanone, methoxybutanol and methoxybutyl acetate are preferred, and propylene glycol monomethyl ether acetate is more preferred. .

The content of the solvent (E) in the photocurable resin composition of the present invention is usually 99.99% by mass or less, preferably 40% by mass or more and 99% by mass, based on the total amount of the photocurable resin composition. The content is more preferably 50% by mass or more and 97% by mass or less, still more preferably 60% by mass or more and 95% by mass or less, even more preferably 65% by mass or more and 90% by mass or less. In other words, the total solid content of the photocurable resin composition of the present invention is usually 0.01% by mass or more, preferably 1% by mass or more and 60% by mass or less, more preferably 3% by mass or more and 50% by mass. The content is more preferably 5% by mass or more and 40% by mass or less, even more preferably 10% by mass or more and 35% by mass or less. When the content of the solvent (E) is within the above range, flatness during coating will be good, and display characteristics will tend to be good since the color density will not be insufficient when forming a color filter. .

<Other ingredients>
The photocurable resin composition of the present invention may optionally contain fillers, other polymer compounds, leveling agents, antioxidants, curing agents, ultraviolet absorbers, chain transfer agents, adhesion promoters, etc. It may also contain additives known in the art.

<Method for producing photocurable resin composition>
The photocurable resin composition of this embodiment includes a resin (A), a polymerizable compound (C), a photoinitiator (D), a colorant, and a solvent (E), and further a polymerization initiation aid (H). It can be manufactured by mixing other components such as, etc. by a known method. After mixing, it is preferable to filter through a filter with a pore size of about 0.05 to 1.0 μm.

<Resin composition for forming coating layer>
The covering layer 40 is formed from a resin composition for forming a covering layer. The resin composition for forming the coating layer includes a resin, a polymerizable compound, a photopolymerization initiator, and the like. The refractive index of the resin composition for forming the coating layer should be lower than the refractive index of the photocurable resin composition, and may be the same as the resin, polymerizable compound, and photopolymerization initiator described in the photocurable resin composition described above. are used. The resin in the resin composition for forming a coating layer preferably has the above-mentioned structural unit (Aa) and structural unit (Ac).

As a method for laminating the coating layer forming resin composition on the substrate 10, the coating layer forming resin composition is applied to the surface of the lens portion 30 so as to cover all exposed surfaces of each microlens 31. Then, it can be cured by irradiating active energy rays.

Application can be performed by a conventional method such as a microgravure coating method, a roll coating method, a dipping coating method, a spin coating method, a die coating method, a cast transfer method, a flow coating method, and a spray coating method. From the viewpoint of easily improving the optical properties of the coating layer, it is preferable to laminate the coating layer-forming composition by a microgravure coating method or a die coating method.

Thereafter, the composition for forming a coating layer is cured by irradiation with active energy rays, and the desired coating layer is obtained. Examples of active energy rays include electron beams, ultraviolet rays, and visible rays, and are appropriately selected depending on the type of coating layer forming composition used. The intensity of the active energy rays to be irradiated, the irradiation time, etc. are appropriately selected depending on the type of the coating layer forming composition used, the thickness of the coating layer, etc. The active energy rays may be irradiated in an inert gas atmosphere. In order to irradiate active energy rays in a nitrogen atmosphere, the active energy rays may be irradiated, for example, in a container sealed with an inert gas, and nitrogen gas, argon gas, etc. can be used as the inert gas.

DESCRIPTION OF SYMBOLS 1, 2 Lens element, 10 Substrate, 20 Photocurable resin composition layer, 30 Lens part, 40 Covering layer, 50 Photomask.

Claims (12)

A lens element having a substrate and a lens part,
The lens section includes a plurality of microlenses arranged spaced apart from each other on the substrate,
The plurality of microlenses include microlenses of two or more colors with different spectral characteristics,
The microlens is a lens element made of a photocurable resin composition and having a convex curved surface on a surface not in contact with the substrate. further comprising a coating layer,
The lens element according to claim 1, wherein the coating layer covers at least a portion of the curved surfaces of the plurality of microlenses. The lens element according to claim 2, wherein the coating layer fills a space between the microlenses that are spaced apart from each other. The lens element according to claim 3, wherein the coating layer covers all surfaces of the plurality of microlenses that are not in contact with the substrate, and has a flat surface. The lens element according to claim 4, wherein the coating layer has a refractive index lower than the refractive index of the microlens. The lens element according to claim 5, wherein the coating layer has a refractive index of 1.1 or more. 3. The lens element according to claim 1, wherein the plurality of microlenses include green, blue, and red, or cyan, magenta, and yellow microlenses. A method for manufacturing a lens element according to claim 2 or 3,
(a) arranging the plurality of microlenses on the substrate to form the lens portion;
a step (b1) of applying a coating layer-forming resin composition to the surface of the lens portion to form a coating film;
A manufacturing method comprising, in this order, a step (b2) of curing the coating film. The step (a) includes:
a step (a1) of applying the photocurable resin composition on the substrate to form a photocurable resin composition layer;
a step (a2) of selectively exposing the photocurable resin composition layer,
The manufacturing method according to claim 8, wherein in the step (a2), the photocurable resin composition layer is exposed with an exposure amount that is 2.0 times or more a saturation exposure amount. A resin composition for forming a coating layer used in the manufacturing method according to claim 8. A solid-state imaging device comprising the lens element according to claim 1 or 2. A display device comprising the lens element according to claim 1 or 2.

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