Optical substrate, solid-state imaging device package, and optical substrate manufacturing method

Abstract

To provide an optical substrate capable of suppressing diffuse reflection. [Solution] An optical substrate 10 according to one embodiment of the present invention comprises a transparent substrate 11 and a light-shielding film 12 laminated in a rectangular frame shape on one main surface of the transparent substrate 11, and the light-shielding film 12 has a plurality of groove structures 122 formed in a stripe shape on the surface opposite the contact surface of the transparent substrate 11.

Description

[Technical Field]

[0001] The present invention relates to an optical substrate, a solid-state imaging device package, and a method for manufacturing an optical substrate. [Background technology]

[0002] Solid-state imaging device packages, in which a solid-state imaging device is directly mounted on the solid-state imaging device or a substrate on which the solid-state imaging device is mounted is covered with a transparent substrate such as glass, are widely used. It is known that unintended light entering such solid-state imaging device packages can be reflected by wiring outside the sensor area, the bottom or wall of the substrate, or the like, and then enter the sensor area, resulting in noise in the captured image, such as flare and ghosting. Therefore, it is known to suppress unintended light from entering the solid-state imaging device package by using an optical substrate with a light-shielding film (colored film) in a peripheral area that does not directly face the sensor area of ​​the transparent substrate. Furthermore, forming a fine uneven structure on the surface of the light-shielding film to suppress reflection from the light-shielding film has also been proposed (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] International Publication No. WO2018 / 180477 Summary of the Invention [Problem to be solved by the invention]

[0004] Forming a fine uneven structure on the surface of the substrate reduces the specular reflection of light, and even if diffusely reflected light enters the sensor area of ​​the solid-state imaging device, the intensity of the light is reduced, thereby reducing clear flare and ghosting. However, the need for flare and ghosting suppression in solid-state imaging device packages is becoming more sophisticated year by year, and suppression of not only specular reflection of light but also diffuse reflection of light is now required. Therefore, an object of the present invention is to provide an optical substrate and a solid-state imaging device package that can significantly suppress total reflection, including diffuse reflection. [Means for solving the problem]

[0005] (1) A solid-state imaging element package according to one embodiment of the present invention comprises a transparent substrate and a light-shielding film laminated in a rectangular frame shape on one main surface of the transparent substrate, the light-shielding film having a plurality of groove structures formed in a stripe shape on the surface opposite to the contact surface of the transparent substrate.

[0006] (2) In the optical substrate of (1), the cross-sectional shape of the groove structure may be U-shaped, semicircular, semi-elliptical, or parabolic.

[0007] (3) In the optical substrate of (1) to (2), the pitch of the groove structure may be 20 μm or more and 300 μm or less.

[0008] (4) In the optical substrate of (1) to (3), the thickness of the light-shielding film may be 5 μm or more and 50 μm or less, and the depth of the groove structure may be 5% or more of the thickness of the light-shielding film.

[0009] (5) In the optical substrate of any one of (1) to (4), the depth of the groove structure may be 50% or less of the thickness of the light-shielding film.

[0010] (6) A solid-state imaging element package according to one embodiment of the present invention comprises an optical substrate (1) to (5) and a solid-state imaging element arranged opposite the optical substrate and having a sensor area facing the opening of the light-shielding film.

[0011] (7) An optical substrate manufacturing method according to one embodiment of the present invention is a method for manufacturing an optical substrate, which comprises forming a rectangular frame-shaped light-shielding film on one main surface of a transparent substrate by photolithography using a photosensitive resin composition containing a colorant, and in the photolithography, a photomask having an opening pattern with stripe-shaped openings is used to form a plurality of stripe-shaped groove structures on the surface opposite to the contact surface of the transparent substrate.

[0012] (8) In the method for producing an optical substrate according to (7), the photosensitive resin composition may be a negative photosensitive resin composition. [Effects of the Invention]

[0013] According to the present invention, it is possible to provide an optical substrate and a solid-state imaging device package that can suppress diffuse reflection. [Brief explanation of the drawings]

[0014] [Figure 1] 1 is a cross-sectional view of a solid-state imaging device package according to an embodiment of the present invention. [Figure 2] FIG. 2 is a rear view of the optical substrate of FIG. [Figure 3] FIG. 2 is a partially enlarged cross-sectional view of the optical substrate of FIG. [Figure 4] 1 is a flowchart showing the steps of a method for manufacturing an optical substrate according to an embodiment of the present invention. [Figure 5] FIG. 3 is a rear view of an alternative optical substrate to FIG. 2. DETAILED DESCRIPTION OF THE INVENTION

[0015] Hereinafter, embodiments of the present invention will be described with reference to the drawings. For convenience, hatching and component symbols may be omitted. In such cases, other drawings should be referenced. Furthermore, the dimensions of various components in the drawings have been adjusted for clarity.

[0016] [Solid-state imaging device package] 1 is a cross-sectional view of a solid-state imaging device package 1 according to a first embodiment of the present invention. The solid-state imaging device package 1 includes an optical substrate 10, a mounting substrate 20 facing the optical substrate 10, a frame 30 interposed between the optical substrate 10 and the mounting substrate 20, and a solid-state imaging device 40 mounted on the mounting substrate 20 so as to face the optical substrate 10. The optical substrate 10 itself is one embodiment of the optical substrate according to the present invention.

[0017] The optical substrate 10 includes a transparent substrate 11 and a light-shielding film 12 laminated on one main surface of the transparent substrate 11 in the shape of a rectangular frame in plan view as shown in Fig. 2. The transparent substrate 11, together with the mounting substrate 20 and the frame 30, seals the space in which the solid-state imaging element 40 is disposed. The transparent substrate 11 also provides an optical path for light to enter the solid-state imaging element 40.

[0018] The transparent substrate 11 is a transparent plate material. The transparent substrate 11 can be formed from transparent ceramics such as glass or sapphire, or transparent plastics such as acrylic resin or polycarbonate. From the viewpoint of reliability, it is preferable to form it from transparent ceramics, and from the viewpoint of versatility, it is more preferable to form it from glass. The type of glass forming the transparent substrate 11 is not particularly limited, but examples include quartz glass, borosilicate glass, and alkali-free glass. The transparent substrate 11 may have an optically functional coating film on its surface. Examples include an anti-reflection film, a band-pass filter film, and a light-absorbing film. These coating films are formed by methods such as vacuum deposition, sputtering, and immersion.

[0019] The light-shielding film 12 is formed in a rectangular frame shape, defining a rectangular light path opening 121 within the frame, which serves as an optical path for light from a subject to be incident on the solid-state imaging element 40. The light-shielding film 12 blocks light that is obliquely incident on the solid-state imaging element 40. The light-shielding film 12 can be formed so that its outer edge overlaps the frame 30. This shape can absorb reflected light that may occur around the frame. The outer edge can also be formed inside the frame, which allows the optical substrate 10 and the frame 30 to be assembled using a UV-curable adhesive. The light-shielding film 12 has multiple groove structures 122 (hatched in FIG. 2 for clarity) formed in a stripe pattern on the surface opposite the transparent substrate 11. The thickness of the light-shielding film 12 (the thickness of the portions between the groove structures 122) is preferably 5 μm to 50 μm, more preferably 10 μm to 40 μm. By setting the thickness of the light-shielding film 12 to the above-mentioned lower limit or more, it is possible to ensure light-shielding properties. Furthermore, by setting the thickness of the light-shielding film 12 to the above-mentioned upper limit or less, it is possible to suppress tilting of the transparent substrate 11 caused by an error in the thickness of the light-shielding film 12. This stabilizes the thickness of the light-shielding film 12, and also maintains a high adhesion strength of the film to the substrate.

[0020] The light-shielding film 12 may be formed from a resin composition containing a colorant. The light-shielding film 12 may be formed by any method, such as printing. However, by using a photosensitive resin composition, a light-shielding film 12 with a uniform thickness and an accurate planar shape can be formed by photolithography. The photosensitive resin composition is preferably a liquid or semi-solid dry film resist on a film. Furthermore, the light-shielding film 12 may be formed from a negative-type photosensitive resin composition (photocurable resin composition) in which the exposed portions are cured by photoreaction and the unexposed portions are dissolved and removed by a developer, thereby easily forming an appropriate groove structure 122. The negative-type photosensitive resin composition contains a resin component having a reactive group, such as an epoxy group, an acrylate group, or a methacrylate group, and a photopolymerization initiator. To improve productivity, the negative-type photosensitive resin composition is preferably prepared so that it can maintain its shape by heating (pre-baking) after application to the transparent substrate 11 and hardens upon exposure so as not to dissolve in the developer. The developer may be an alkaline aqueous solution or an organic solvent. Examples of the alkaline aqueous solution include those containing sodium hydroxide aqueous solution, potassium hydroxide aqueous solution, sodium carbonate aqueous solution, sodium silicate aqueous solution, sodium borate aqueous solution, tetramethylammonium hydroxide aqueous solution, and tetraethylammonium hydroxide aqueous solution. Examples of the organic solvent include those containing hydrocarbon solvents such as benzene, toluene, xylene, and hexane, ketone solvents such as acetone and cyclohexanone, tetrahydrofuran, N-methylpyrrolidone, dimethylformamide, dimethylacetamide, propylene glycol monomethyl ether acetate, propylene glycol monomethyl ether, ethyl acetate, butyl acetate, methoxybutyl acetate, methanol, ethanol, and isopropanol.

[0021] Examples of colorants contained in the photosensitive resin composition forming the light-shielding film 12 include organic pigments, inorganic pigments, dyes, and the like. From the viewpoints of heat resistance and colorability, it is preferable to use a pigment as the colorant. When forming a black colored pattern, it is preferable to use a black pigment as the colorant. In addition to black patterns, colored patterns such as red, yellow, and blue are also possible. Pigments that absorb a wide range of wavelengths in the visible light range are preferred. Among the pigments that absorb a wide range of wavelengths in the visible light range, examples of black organic pigments include anthraquinone-based black pigments, perylene-based black pigments, azo-based black pigments, and lactam-based black pigments. Among these, perylene-based black pigments and lactam-based black pigments are preferred due to their excellent light-shielding properties. Examples of black inorganic pigments include carbon black and black low-order titanium oxynitride. Examples of other inorganic pigments include composite metal oxide pigments, titanium oxide, barium sulfate, lead sulfate, yellow lead, red iron oxide, ultramarine, Prussian blue, chromium oxide, antimony white, zinc sulfide, zinc, manganese purple, cobalt purple, and magnesium carbonate. Examples of dyes include azo compounds, anthraquinone compounds, perylene compounds, perinone compounds, phthalocyanine compounds, carbonium compounds, and indigoid compounds. Pigments used to obtain colored patterns other than black patterns include chromatic pigments such as red, orange, yellow, green, blue, purple, cyanine, and magenta. Specific examples of chromatic pigments include Color Index (CI) Pigment Yellow 1, 10, and 83; CI Pigment Orange 2, 5, and 13; CI Pigment Red 1, 2, and 3; CI Pigment Green 7, 10, and 36; and CI Pigment Blue 1, 2, and 15. These pigments can be used alone or in various combinations.

[0022] The content of the colorant in the photosensitive resin composition forming the light-shielding film 12 is preferably 0.3% by mass or more and 8% by mass or less, more preferably 0.5% by mass or more and 6% by mass or less, and particularly preferably 1.0% by mass or more and 4% by mass or less. By setting the content of the colorant at or above the lower limit, the light transmittance of the light-shielding film 12 can be sufficiently reduced, thereby effectively suppressing flare and ghosting. Furthermore, by setting the content of the colorant at or below the upper limit, it is possible to prevent the colorant from remaining on the surface of the transparent substrate 11 after removing the photosensitive resin composition from areas not irradiated with light.

[0023] The groove structures 122 suppress total reflection on the main surface (rear surface) of the light-shielding film 12 facing the solid-state imaging device 40. The groove structures 122 are preferably formed in a line-and-space pattern with a constant width and constant spacing across substantially the entire surface. Microscopically, light incident on the inner surface of the groove structures 122 at a certain angle of incidence is thought to be absorbed by the light-shielding film 12 and converted into thermal energy as it repeatedly reflects off the grooves of the groove structures 122. While this effect could theoretically be achieved with a conventional structure that has a dense pattern of fine irregularities, it is extremely difficult to actually form such effective irregularities on a nanometer scale. Therefore, conventional fine irregularity structures primarily result in diffuse reflection of light, failing to effectively reduce total reflection. For this reason, it is believed that forming multiple groove structures 122 extending with a uniform cross-sectional shape would have a greater light-absorbing effect.

[0024] 3, the cross-sectional shape of the groove structure 122 is preferably a shape in which the slope gradually decreases toward the back in at least a range having a depth of 70% or more of the deepest part in a cross section perpendicular to the extension direction of the groove structure 122, specifically a U-shape, semicircular shape, semi-elliptical shape, parabolic shape, etc. Note that the shoulder portion formed by the surface of the light-shielding film 12 and the inner surface of the groove structure 122 is preferably chamfered so that the slope gradually increases toward the back, and more preferably chamfered so that no flat area remains between the groove structures 122.

[0025] The depth of the groove structure 122 (the depth of the deepest part in a cross section perpendicular to the extension direction of the groove structure 122) is preferably 5% to 100% of the thickness of the light-shielding film 12, more preferably 5% to 70% of the thickness of the light-shielding film 12, and still more preferably 5% to 50% of the thickness of the light-shielding film 12. By setting the depth of the groove structure 122 to the above-mentioned lower limit or more, light reflected on the inner surface of the groove structure 122 can be easily re-incident on another inner surface of the groove structure 122. Furthermore, by setting the depth of the groove structure 122 to the above-mentioned upper limit or less, light transmission through the light-shielding film 12 can be prevented. Specifically, the lower limit of the depth of the groove structure 122 is preferably 1 μm or more, more preferably 2 μm or more. Furthermore, the upper limit is preferably the same depth as the widest width of the groove structure 122. This is because if the depth is deeper than the width portion, the aspect ratio exceeds 1, making it difficult to maintain the shape of the groove structure. The 70% width of the groove structure 122 (the width of the range having a depth of 70% or more of the deepest part in a cross section perpendicular to the extension direction of the groove structure 122) is preferably 20 μm to 200 μm, more preferably 50 μm to 150 μm. By setting the 70% width of the groove structure 122 to be equal to or greater than the above-mentioned lower limit, it is possible to relatively accurately form a recessed shape that can efficiently absorb light. Furthermore, by setting the 70% width of the groove structure 122 to be equal to or less than the above-mentioned upper limit, it is possible to prevent the groove structure 122 from becoming excessively deep. The pitch P of the groove structure 122 (the average distance between the center lines of each groove) is preferably 30 μm to 300 μm, more preferably 30 μm to 200 μm. Furthermore, it is preferable that the pitch of the groove structure 122 be smaller than twice the 70% width of the groove structure 122. By setting the pitch P of the groove structures 122 to the lower limit or more, it is possible to form concave shapes that can efficiently absorb light relatively accurately. Furthermore, by setting the pitch P of the groove structures 122 to the upper limit or less, it is possible to reduce the area that does not contribute to improving light absorption. The skewness Ssk (ISO-25178) of the back surface of the light-shielding film 12, in which multiple groove structures 122 are formed with the cross-sectional shape, width, and pitch P described above, over the reference length including the multiple groove structures 122, is a positive value. In other words, in order to efficiently absorb light, it is preferable that the skewness Ssk of the back surface of the light-shielding film 12 is a positive value. The groove structures 122 are not necessarily spaced at equal intervals, and may be designed so that the width and intervals are not constant.

[0026] The mounting board 20 is a structural member that supports the solid-state imaging element 40 and the frame 30. For this reason, the mounting board 20 is formed from a material with sufficient rigidity. The mounting board 20 may be a simple support, but is preferably a circuit board on which a circuit is formed that supplies power to the solid-state imaging element 40 and extracts signals from the solid-state imaging element 40. In this embodiment, the mounting board 20 has a circuit including electrodes 201 for electrical connection with the solid-state imaging element 40.

[0027] Examples of the mounting substrate 20 include organic materials such as polyimide, polyester, ceramic, epoxy, bismaleimide triazine, and phenolic resin; structures in which paper or glass fiber nonwoven fabric is impregnated with the organic materials and then heat-cured; ceramic materials such as alumina, aluminum nitride, beryllium oxide, and silicon nitride; and metal substrates. Among these, glass epoxy substrates and ceramic substrates are preferred. Circuits with metal wiring patterns and metal bumps can be formed on or inside these insulating substrates.

[0028] The frame 30 determines the distance between the optical substrate 10 and the mounting substrate 20 and forms an enclosed space that encloses the solid-state imaging element 40. The frame 30 is preferably formed from a colored material, i.e., a resin composition containing a colorant, so as to prevent light from entering the sensor region 41 of the solid-state imaging element 40 from the side. The frame 30 may also have a light diffusion structure so as to reduce the amount of light that enters the sensor region 41 of the solid-state imaging element 40 from the side by diffusing the incident light. Examples of the light diffusion structure include an uneven surface structure and a structure containing a light diffusion material inside.

[0029] The frame 30 is preferably formed from a heat-resistant thermosetting resin. Preferred thermosetting resins include epoxy resin, silicone resin (addition type silicone resin, condensation type silicone resin, siloxane bond-containing curable resin), urethane resin, polyimide resin, acrylate resin, unsaturated polyester resin, and phenolic resin. The frame 30 may be adhered to the mounting substrate 20 with an adhesive, or may be molded onto the mounting substrate 20. Alternatively, the frame 30 may be formed integrally with the mounting substrate 20 using, for example, a ceramic material or the above-mentioned thermosetting resin. When the frame 30 and the mounting substrate 20 are formed integrally, a ceramic material is preferred from the standpoint of reliability.

[0030] The solid-state imaging element 40 is mounted on the side of the mounting substrate 20 facing the optical substrate 10, and converts an image of light incident through the transparent substrate 11 and the optical path opening 121 into an electrical signal. The solid-state imaging element 40 may have a sensor region 41 in which a sensor for capturing an image is formed, and a connection region 42 provided outside the sensor region 41. The sensor region 41 may have a two-dimensional imaging element structure such as a CMOS image sensor. Electrodes 421 and the like for electrically connecting the solid-state imaging element 40 to the mounting substrate 20 and the like are disposed in the connection region 42. In this embodiment, the electrodes 421 of the solid-state imaging element 40 and the electrodes 101 of the mounting substrate 20 are electrically connected by wires 422.

[0031] As described above, the solid-state imaging element package 1 has a plurality of groove structures 122 formed in a stripe pattern on the surface of the light-shielding film 12 of the optical substrate 10 opposite the contact surface with the transparent substrate 11, thereby effectively suppressing the reflection of light that is reflected by the wires 422, etc. and enters the back surface of the light-shielding film 12, thereby effectively preventing flare and ghosting and obtaining high-quality images.

[0032] [Optical substrate manufacturing method] The optical substrate 10 can be manufactured by an optical substrate manufacturing method according to one embodiment of the present invention shown in Fig. 4. In the optical substrate manufacturing method according to this embodiment, a rectangular frame-shaped light-shielding film is formed on one main surface of a transparent substrate 11 by photolithography using a photosensitive resin composition. Specifically, the optical substrate manufacturing method of this embodiment includes a coating step (step S1), an exposure step (step S2), and a development step (step S3).

[0033] In the coating step of step S1, a photosensitive resin composition containing a colorant, preferably a negative photosensitive resin composition, is coated on one main surface of a transparent substrate. The coating method is not particularly limited, and bar coating, die coating, or the like can be used, but spin coating, which can form a coating film of uniform thickness, is particularly suitable.

[0034] In the exposure step of step S2, the photosensitive resin composition is exposed to active energy rays such as ultraviolet rays and electron beams using a photomask having a striped opening pattern in the light-shielding film formation region. The openings of the photomask may be formed as a halftone that is not completely transparent, or as a fine pattern to reduce light. Examples of exposure methods using a photomask include proximity exposure and contact exposure. When performing proximity exposure, the distance between the resin-coated substrate and the photomask is preferably 0.01 mm to 3 mm, more preferably 0.1 mm to 2 mm. After the exposure, a post-exposure bake (PEB) step may be performed to promote the curing reaction. By performing such proximity exposure and PEB, groove structures 122 having recessed shapes that can efficiently absorb light can be formed, as described above.

[0035] In the development step S3, the portions of the photosensitive resin composition that have not been sufficiently cured by exposure are dissolved and removed with a developer, thereby forming a light-shielding film having a plurality of groove structures formed in a stripe pattern on the surface of the transparent substrate opposite the contact surface.

[0036] In this way, by forming the light-shielding film by photolithography, it is possible to relatively easily form a groove structure having a shape corresponding to the opening pattern of the photomask and having a high reflection suppressing effect at the same time as forming the light-shielding film.

[0037] Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments and various modifications and variations are possible. In the above-described embodiments, the light-shielding film has a groove structure extending in the same direction across the entire surface. However, the light-shielding film may be divided into multiple regions, and groove structures extending in different directions may be formed in each region. For example, the groove structure may be formed to extend at a certain angle relative to the side edges of the sensor regions of adjacent solid-state imaging elements. Alternatively, as illustrated in FIG. 5, the light-shielding film may be divided into multiple grid-like regions, and the groove structure may be formed to extend perpendicular to adjacent regions. The groove structure may also be formed in a curved shape. Furthermore, the solid-state imaging element package according to the present invention may have a so-called CSP (Chip Size Package) structure in which a frame is bonded to an area just outside the sensor region on the surface of the solid-state imaging element. Furthermore, in the optical substrate according to the present invention, the groove structure may be formed by, for example, embossing, laser ablation, or the like. Furthermore, the optical substrate manufacturing method according to the present invention may include a pre-baking step in which the photosensitive resin is pre-cured by heating between the coating step and the exposure step, and may include a baking step in which the photosensitive resin is completely cured by heating after the development step. [Example]

[0038] The present invention will be specifically described below based on examples, but the present invention is not limited to the following examples.

[0039] Example 1 A photosensitive resin composition for forming a light-shielding film was prepared, and the composition was coated on a glass substrate, followed by photolithography in which ultraviolet light was irradiated through a photomask to form a light-shielding film.

[0040] The photosensitive resin composition was prepared by first adding 143 μL of a xylene solution of platinum vinylsiloxane complex (Pt-VTSC-3X, manufactured by Umicore Precious Metals Japan, a solution containing 3% by mass of platinum) to a mixture of 40 g of diallyl isocyanurate, 29 g of diallyl monomethyl isocyanurate, and 264 g of 1,4-dioxane to obtain solution S1. Separately, 88 g of 1,3,5,7-tetrahydrogen-1,3,5,7-tetramethylcyclotetrasiloxane was dissolved in 176 g of toluene to obtain solution S2.

[0041] Then, in a nitrogen atmosphere containing 3% by volume of oxygen, solution S2 was heated to a temperature of 105°C, and solution S1 was added dropwise to solution S2 over 3 hours. After the dropwise addition was completed, the temperature was maintained at 105°C and the mixture was stirred for 30 minutes to obtain solution S3. Separately, 62 g of 1-vinyl-3,4-epoxycyclohexane was dissolved in 62 g of toluene to obtain solution S4. Then, in a nitrogen atmosphere containing 3% by volume of oxygen, solution S3 was heated to a temperature of 105°C, and solution S4 was added dropwise to solution S3 over 1 hour. After the dropwise addition was completed, the mixture was stirred for 30 minutes to obtain solution S5.

[0042] After cooling Solution S5, the solvents (toluene, xylene, and 1,4-dioxane) were distilled off under reduced pressure to obtain a solid content. Next, to 100 parts by mass of the obtained solid content, 49 parts by mass of propylene glycol 1-monomethyl ether 2-acetate, 15 parts by mass of an epoxy monomer (3',4'-epoxycyclohexylmethyl 3,4-epoxycyclohexanecarboxylate: "Celloxide 2021P" manufactured by Daicel Corporation), 1 part by mass of a sulfonium salt-based photocationic polymerization initiator ("CPI-210S" manufactured by San-Apro Co., Ltd.), and 1 part by mass of a black pigment (carbon black: "MA-100" manufactured by Mitsubishi Chemical Corporation) were added to obtain a photosensitive resin composition for forming a light-shielding film.

[0043] The obtained photosensitive resin composition was applied to a transparent substrate by spin coating to form a coating film with a thickness of 25 to 35 μm, and the coating film was pre-cured by heating it on a hot plate heated to 100°C for 10 minutes. Next, using a manual exposure machine (high-pressure mercury lamp), the pre-cured coating film was exposed to light through a photomask with a proximity of 0.4 mm. The photomask used had stripe-shaped openings with a width of 50 μm and a pitch of 150 μm formed over the entire surface. The exposure dose was 6000 mJ / cm. 2 (30mW / cm 2 × 200 sec). After exposure, the PEB was heated on a hot plate heated to 100°C for 10 minutes to promote the curing reaction of the exposed areas. The coating was then developed with an alkaline developer, i.e., the photosensitive resin composition that had not been sufficiently cured by the light irradiation was dissolved and removed. At this time, areas other than the openings shielded by the photomask were exposed to light due to the provision of a predetermined proximity and the diffraction of the exposure light source, even the shielded areas of the photomask outside the openings were exposed to light, so that they remained as a thinner film than the exposed areas after development. As a result, a light-shielding film having multiple groove structures with a cross-sectional shape as shown in Figure 3 was formed. Furthermore, the light-shielding film was completely cured by heating in an oven heated to 200°C for 2 hours, and the optical substrate of Example 1 was obtained.

[0044] Example 2 An optical substrate of Example 2 was obtained in the same manner as in Example 1, except that a photomask with stripe-shaped openings of 100 μm width and 150 μm pitch was used.

[0045] (Comparative Example 1) An optical substrate of Comparative Example 1 was obtained in the same manner as in Example 1, except that a photomask was not used.

[0046] (Comparative Example 2) The surface of the light-shielding film of the optical substrate of Comparative Example 1 was further roughened with a chemical roughening solution to obtain an optical substrate of Comparative Example 2.

[0047] (Comparative Example 3) An optical substrate of Comparative Example 3 was obtained in the same manner as in Example 1, except that a photomask with lattice-shaped openings (having square light-shielding regions) of 100 μm width and a vertical and horizontal pitch of 200 μm was used.

[0048] Comparative Example 4 An optical substrate of Comparative Example 4 was obtained in the same manner as in Example 1, except that a photomask with square openings (having lattice-shaped light-shielding portions) measuring 60 μm in length and width and with a vertical and horizontal pitch of 200 μm was used.

[0049] (Comparative Example 5) An optical substrate of Comparative Example 5 was obtained in the same manner as in Example 1, except that a photomask was used in which square openings with a diagonal length of 200 μm were arranged so that the four corners of the square openings were in contact with adjacent openings.

[0050] Table 1 below summarizes the shapes (width, depth, and pitch) of the groove structures or recesses formed on the back surface (the surface opposite the transparent substrate) of the light-shielding film of the optical substrate in Examples 1 and 2 and Comparative Examples 1 to 5, as well as the total reflectance of the light-shielding film. The shape of the back surface of the light-shielding film was measured using a 3D measuring laser microscope "LEXT-OLS4000" manufactured by Olympus Corporation, and the reflectance was measured using a UV-Visible-Near-Infrared Spectrophotometer "V-770" manufactured by JASCO Corporation. An integrating sphere was used during the measurements to evaluate the total luminous flux.

[0051] [Table 1]

[0052] These results confirm that the reflectance can be effectively suppressed by forming a striped groove structure. [Explanation of symbols]

[0053] 1 Solid-state imaging device package 10 Optical board 11 Transparent substrate 12 Light-shielding film 121 Optical path aperture 122 Groove structure 20 Mounting board 201 Electrode 30 frames 40 Solid-state imaging device 41 Sensor Area 42 Connection Area 421 Electrode 422 Wire

Claims

1. A transparent substrate and a light-shielding film laminated in a rectangular frame shape on one main surface of the transparent substrate, The light-shielding film has a plurality of groove structures formed in a stripe pattern on the surface opposite to the contact surface of the transparent substrate.

2. The optical substrate according to claim 1 , wherein the cross-sectional shape of the groove structure is U-shaped, semicircular, semi-elliptical, or parabolic.

3. The optical substrate according to claim 1 or 2, wherein the pitch of the groove structure is 20 μm or more and 300 μm or less.

4. 3. The optical substrate according to claim 1, wherein the thickness of the light-shielding film is 5 μm or more and 50 μm or less, and the depth of the groove structure is 5% or more of the thickness of the light-shielding film.

5. The optical substrate according to claim 4 , wherein the depth of the groove structure is 50% or less of the thickness of the light-shielding film.

6. The optical substrate according to claim 1 or 2; a solid-state imaging element disposed opposite the optical substrate and having a sensor region facing the opening of the light-shielding film; A solid-state imaging device package comprising:

7. A method for manufacturing an optical substrate, comprising forming a rectangular frame-shaped light-shielding film on one main surface of a transparent substrate by photolithography using a photosensitive resin composition containing a colorant, The optical substrate manufacturing method includes forming a plurality of stripe-shaped groove structures on the surface of the transparent substrate opposite to the contact surface using a photomask having a stripe-shaped opening pattern in the photolithography.

8. The method for producing an optical substrate according to claim 7 , wherein a negative photosensitive resin composition is used as the photosensitive resin composition.

Images