Solid-state imaging element package

Abstract

A solid-state imaging element package (1) according to one embodiment of the present invention is provided with: a transparent substrate (31); a frame-shaped wall body (32) which is formed from a resin composition containing a colorant, is laminated on one main surface of the transparent substrate (31), and defines an inner space; and a solid-state imaging element (20) that captures an image of light incident through the transparent substrate (31) into the inner space, the arithmetic average roughness (Ra) of the inner peripheral surface (321) of the wall body (32) being 50-3000 nm, and the shortest distance between the wall body (32) and the functional part (21) of the solid-state imaging element (20) being 800 [mu] m or less.

Description

Technical Field

[0001] The present invention relates to a solid-state imaging element package. Background Art

[0002] Solid-state imaging element packages are widely used, in which a wall (frame) surrounding the solid-state imaging element is bonded to a substrate on which the solid-state imaging element is mounted, and the opening of the wall is covered with a transparent substrate such as a glass plate (see, for example, Patent Document 1). In such solid-state imaging element packages, the wall determines the relative position of the transparent substrate with respect to the solid-state imaging element and reduces noise in the captured image, such as stray light (flare) and ghosting, by suppressing unintended light from entering the solid-state imaging element.

[0003] Prior art literature

[0004] Patent Literature

[0005] Patent Document 1: Japanese Patent Application Laid-Open No. 2004-296453 Summary of the Invention

[0006] Problems to be solved by the invention

[0007] Demand for miniaturization of solid-state imaging element packages is increasing, and the use of solid-state imaging element packages constructed with, for example, glass-on-chip (GOC) systems, where walls are bonded to the outer periphery of the solid-state imaging element, is increasing. Miniaturization of solid-state imaging element packages also requires high precision of the walls. To improve wall precision, an optical substrate with walls formed directly on a transparent substrate can be considered, and the walls of the optical substrate can be bonded to the solid-state imaging element or the mounting substrate on which the solid-state imaging element is mounted.

[0008] As a method for molding resin with high precision on a transparent substrate, photolithography technology is known. However, in order to form a wall that can limit the incidence of light as described above, it is necessary to use a material with light-shielding properties. Therefore, it is impossible to use light for development (selective curing or solubilization of the resin). In addition, if the content of the pigment is increased, the problem of residual pigment in the opening part that should be removed during development will also occur, generating image noise. Therefore, it has been studied to form a wall using a resin containing a minimum amount of pigment, but if the content of the pigment is reduced, the noise of the captured image such as stray light and ghosting is likely to increase. In view of this actual situation, the subject of the present invention is to provide a solid-state imaging element package with less noise in the captured image.

[0009] Solutions for solving problems

[0010] A solid-state imaging element package described in one embodiment of the present invention comprises: a transparent substrate; a frame-shaped wall body formed from a resin composition containing a colorant and laminated on a main surface of the aforementioned transparent substrate to divide an inner space; and a solid-state imaging element that captures an image of light incident on the aforementioned inner space through the aforementioned transparent substrate, wherein the arithmetic mean roughness Ra of the inner peripheral surface of the aforementioned wall body is greater than or equal to 50 nm and less than or equal to 3000 nm, and the shortest distance between the aforementioned wall body and a functional portion of the aforementioned solid-state imaging element is less than or equal to 800 μm.

[0011] In the solid-state imaging element package, the content of the colorant may be 5% by mass or less.

[0012] In the solid-state imaging element package, the skewness Ssk of the inner peripheral surface of the wall may be a negative value.

[0013] In the solid-state imaging element package, the wall body may be bonded to the solid-state imaging element.

[0014] In the solid-state imaging element package, the wall may be formed of the photocurable resin composition.

[0015] Effects of the Invention

[0016] According to the present invention, a solid-state imaging element package with less noise in captured images can be provided. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 This is a cross-sectional view of a solid-state imaging element package according to one embodiment of the present invention. DETAILED DESCRIPTION

[0018] The following describes embodiments of the present invention with reference to the accompanying drawings. It should be noted that in the embodiments described later, components identical to those in previously described embodiments may be denoted by the same reference numerals, and duplicate descriptions may be omitted. Furthermore, to facilitate understanding of features, the drawings may include altered ratios, omissions of details, and the like.

[0019] [First embodiment]

[0020] Figure 1 This is a cross-sectional view of a solid-state imaging element package 1 according to a first embodiment of the present invention. The solid-state imaging element package 1 includes a mounting substrate 10; a solid-state imaging element 20 mounted on the mounting substrate 10; an optical substrate 30 bonded to the solid-state imaging element 20; and a sealing material 40 that seals the solid-state imaging element 20 on the mounting substrate 10 and the outer sides of the optical substrate 30.

[0021] The mounting substrate 10 is a structural member that supports the solid-state imaging element 20. Therefore, the mounting substrate 10 is formed of a material having sufficient rigidity. The mounting substrate 10 can be a simple support, but is preferably a circuit substrate having circuits for supplying power to the solid-state imaging element 20 and extracting signals from the solid-state imaging element 20. In this embodiment, the mounting substrate 10 includes circuits including electrodes 101 for electrically connecting to the solid-state imaging element 20.

[0022] Examples of mounting substrate 10 include organic materials such as polyimide, polyester, ceramics, epoxy resin, bismaleimide triazine, and phenolic resin; structures formed by impregnating paper or glass fiber nonwoven fabric with these organic materials and then heat-curing them; ceramics such as alumina, aluminum nitride, beryllium oxide, and silicon nitride; and metal substrates. Preferred examples include glass epoxy substrates and ceramic substrates. Circuits with metal wiring patterns and metal bumps can be formed on or within the surfaces of these insulating substrates.

[0023] The solid-state imaging element 20 is mounted on the side of the mounting substrate 10 facing the optical substrate 30. The solid-state imaging element 20 is formed on the surface facing the optical substrate 30 and includes a functional portion 21 for imaging, a connecting portion 22 for electrical connection, and an edge portion 23 between the functional portion 21 and the connecting portion 22. The solid-state imaging element 20 is mounted such that the imaging surface of the functional portion 21 is parallel to the main surface of the mounting substrate 10; in other words, the optical axis is parallel to the normal direction of the mounting substrate 10. For example, a two-dimensional imaging element such as a CMOS image sensor can be used as the solid-state imaging element 20. For example, the functional portion 21 can be formed into a two-dimensional imaging element structure such as a CMOS image sensor. The connecting portion 22 is a region where electrodes 221 and the like are provided for electrically connecting the solid-state imaging element 20 to the mounting substrate 10 and the like. As in this embodiment, the connecting portion 22 can be provided outside the functional portion 21. Alternatively, the connecting portion 22 can be provided on the surface opposite the functional portion 21, in other words, on the surface facing the mounting substrate 10. In this embodiment, the electrodes 221 of the solid-state imaging element 20 and the electrodes 101 of the mounting substrate 10 are electrically connected via the wires 222. The edge portion 23 is a region to which the optical base 30 is bonded.

[0024] The optical base 30 forms a sealed space that seals the functional portion 21 against the solid-state imaging element 20. The optical base 30 includes a transparent substrate 31 and a frame-shaped wall 32. The frame-shaped wall 32 is laminated on one main surface of the transparent substrate 31 and adhered to the edge portion 23 to define an inner space within which the functional portion 21 is located. In other words, in the solid-state imaging element package 1, the solid-state imaging element 20 captures an image of light that passes through the transparent substrate 31 and enters the inner space.

[0025] The transparent substrate 31 is a transparent plate. It can be made of glass, transparent ceramics such as sapphire, or transparent plastics such as acrylic resin and polycarbonate. From the perspective of reliability, transparent ceramics are preferred, while from the perspective of versatility, glass is more preferred. The type of glass forming the transparent substrate 31 is not particularly limited; examples include quartz glass, borosilicate glass, and alkali-free glass.

[0026] The wall 32 is formed by a resin composition containing a colorant, preferably a photocurable resin composition. By forming the wall 32 from a photocurable resin composition, it is possible to form a wall 32 with uniform thickness and an accurate planar shape using, for example, photolithography technology. The photocurable resin composition, for example, contains a resin component having reactive groups such as an epoxy group and an acryl group, and a photopolymerization initiator. In addition, as the colorant contained in the photocurable resin composition, organic pigments, inorganic pigments, dyes, etc. can be listed. From the viewpoint of heat resistance and colorability, pigments are preferably used as colorants. In the case of forming a black coloring pattern, black pigments are preferably used as colorants. In addition, as coloring patterns other than black patterns, red patterns, yellow patterns, blue patterns, etc. can be listed.

[0027] As pigments, pigments that widely absorb wavelengths in the visible light region are preferred. Among the pigments that widely absorb wavelengths in the visible light region, as black organic pigments, anthraquinone-based black pigments, perylene-based black pigments, azo-based black pigments, lactam-based black pigments, etc. can be listed. Among these, perylene-based black pigments and lactam-based black pigments are preferred from the perspective of excellent light-shielding properties. As black inorganic pigments, carbon black, black low-valent titanium oxide (black low-valent titanium oxide) and the like can be listed. As examples of other inorganic pigments, carbon black, composite metal oxide pigments, titanium oxide, barium sulfate, lead sulfate, chrome yellow, iron oxide red, ultramarine, Prussian blue, chromium oxide, antimony white, zinc sulfide, zinc, manganese violet, cobalt violet, magnesium carbonate, etc. can be listed. As dyes, azo compounds, anthraquinone compounds, perylene compounds, violet ketone compounds, phthalocyanine compounds, carbonium compounds, indigo compounds, etc. can be listed. Examples of pigments for obtaining colored patterns other than black patterns include color pigments such as red, orange, yellow, green, cyan, purple, cyanine, and magenta.

[0028] Specific examples of color pigments include Color Index (CI) Pigment Yellow 1, 10, 83, etc.; CI Pigment Orange 2, 5, 13, etc.; CI Pigment Red 1, 2, 3, etc.; CI Pigment Green 7, 10, 36, etc.; CI Pigment Blue 1, 2, 15, etc. These pigments may be used alone or in combination of two or more.

[0029] The lower limit of the colorant content in the photocurable resin composition forming the wall 32 is preferably 0.2% by mass, more preferably 0.5% by mass, and particularly preferably 0.8% by mass. On the other hand, the upper limit of the colorant content in the photocurable resin composition forming the wall 32 is preferably 5% by mass, more preferably 4% by mass, and particularly preferably 3% by mass. By setting the colorant content above the lower limit, the light transmittance of the wall 32 can be reduced, thereby effectively suppressing stray light and ghosting. Furthermore, by setting the colorant content below the upper limit, it is possible to form the wall 32 with a precise shape by exposing the interior of the photocurable resin composition. Furthermore, after removing the photocurable resin composition from the unexposed area, it is possible to suppress the colorant from remaining on the surface of the transparent substrate 31.

[0030] The lower limit of the shortest distance between the wall 32 and the functional portion 21 of the solid-state imaging element 20 is preferably 100 μm, and more preferably 200 μm. On the other hand, the upper limit of the shortest distance between the wall 32 and the functional portion 21 is preferably 800 μm, and more preferably 600 μm. By setting the shortest distance between the wall 32 and the functional portion 21 to be greater than the lower limit, it is possible to suppress light reflected by the inner peripheral surface 321 from being incident on the functional portion 21 and projected onto the captured image by the wall 32. Furthermore, by setting the shortest distance between the wall 32 and the functional portion 21 to be less than the upper limit, it is possible to block unintended light that might obliquely enter the functional portion 21.

[0031] The wall 32 has a concave-convex structure that scatters light, at least on its inner surface 321, which is exposed to the inner space. The inner surface 321 with the concave-convex structure reduces the intensity of unexpected light incident on the functional portion 21 of the solid-state imaging element 20 by diffusing light, thereby increasing the S / N ratio and suppressing recognizable stray light and ghosting. In particular, even if the colorant content of the wall 32 is reduced as described above, the transmitted light is scattered on the inner surface 321, thereby effectively suppressing image noise. Furthermore, when unexpected light incident on the inner space of the solid-state imaging element package 1, such as light incident obliquely on the inner space of the wall 32, is reflected and incident on the wall 32, the inner surface 321 diffuses the light that may have been re-reflected on the wall 32 and then incident on the functional portion 21 of the solid-state imaging element 20, thereby suppressing image noise. In order to further reduce reflection of obliquely incident light, the inner peripheral surface 321 of the wall 32 may be formed into a tapered or dome-shaped shape with a smaller inner diameter on the transparent substrate 31 side.

[0032] The concavo-convex structure of the inner circumferential surface 321 can be formed by, for example, embossing by pressing a mold having concavo-convex patterns against the surface of the wall body 32 while the wall body 32 is in a semi-cured state (B-stage). Furthermore, if the wall body 32 is cured while the mounting substrate 10 is in close contact with the semi-cured wall body 32 having the inner circumferential surface 321, the wall body 32 can be bonded to the edge portion 23 of the solid-state imaging element 20 without using an adhesive.

[0033] The lower limit of the arithmetic mean roughness Ra (JIS-B0601) of the inner circumferential surface 321 is preferably 50 nm, more preferably 100 nm, and even more preferably 200 nm. On the other hand, the upper limit of the arithmetic mean roughness Ra of the inner circumferential surface 321 is preferably 3000 nm, more preferably 2600 nm, even more preferably 2000 nm, and particularly preferably 1000 nm. By setting the arithmetic mean roughness Ra of the inner circumferential surface 321 to above the aforementioned lower limit, regular reflection can be more effectively suppressed, thereby more effectively suppressing stray light and ghosting. In addition, by setting the arithmetic mean roughness Ra of the inner circumferential surface 321 to below the aforementioned upper limit, manufacturing is relatively easy, thereby suppressing manufacturing costs.

[0034] As the lower limit of the average length RSm (JIS-B0601) of the roughness curve element of the inner circumferential surface 321, it is preferably 100nm, more preferably 200nm, and further preferably 300nm. On the other hand, as the upper limit of the average length RSm of the roughness curve element of the inner circumferential surface 321, it is preferably 20000nm, more preferably 10000nm, and further preferably 8000nm. By setting the average length RSm of the roughness curve element of the inner circumferential surface 321 to above the aforementioned lower limit, it is easier to manufacture, and therefore it is possible to suppress manufacturing costs. In addition, by setting the average length RSm of the roughness curve element of the inner circumferential surface 321 to below the aforementioned upper limit, it is possible to more effectively suppress regular reflection, and therefore it is possible to more effectively suppress stray light and ghosting.

[0035] The skewness Ssk (ISO-25178) of the inner circumferential surface 321 is preferably set to a negative value. More specifically, the lower limit of the skewness Ssk of the inner circumferential surface 321 is preferably -0.80, and more preferably -0.70. On the other hand, the upper limit of the skewness Ssk of the inner circumferential surface 321 is preferably -0.10, and more preferably -0.20. By setting the skewness Ssk to be above the aforementioned lower limit, it is easy to miniaturize the concavities and convexities, and thus it is possible to effectively suppress stray light and ghosting. In addition, by setting the skewness Ssk to be below the aforementioned upper limit, the light incident on the inner circumferential surface 321 is repeatedly reflected in the valleys of the concavities and convexities and is attenuated, and can be reflected in a dispersed manner in multiple directions to reduce regular reflection, thereby promoting the effect of suppressing stray light and ghosting.

[0036] The sealing material 40 seals the outer sides of the solid-state imaging element 20 and the optical substrate 30 on the mounting substrate 10, thereby preventing the optical substrate 30 from being peeled off from the solid-state imaging element 20 by foreign objects. In addition, the sealing material 40 protects the leads 222, thereby ensuring electrical connection between the mounting substrate 10 and the solid-state imaging element 20.

[0037] As the sealing material 40, for example, thermosetting resins such as epoxy resin, acrylic resin, silicone resin are preferably used. From the viewpoint of toughness and heat resistance, epoxy resin is particularly preferred. In addition, in order to prevent unexpected light from entering the functional portion 21, the sealing material 40 is preferably formed by a resin composition containing a colorant or a light diffusion material. In addition, the sealing material 40 may contain a filler such as silicon dioxide that has thixotropy before curing in order to easily form.

[0038] The solid-state imaging element package 1 having the above-mentioned structure has an optical substrate 30 that can use the inner peripheral surface 321 to suppress stray light and ghosting even if the colorant content is reduced to a level that allows the wall 32 to be formed by photolithography or the like without leaving residue on the transparent substrate 31, thereby being able to capture high-quality images with little noise.

[0039] While the embodiments of the present invention have been described above, the present invention is not limited to these embodiments and various modifications and variations are possible. For example, the solid-state imaging element package of the present invention may be a so-called chip-size package, in which the overall planar dimensions of the package and the optical substrate are approximately equal to those of the solid-state imaging element. Alternatively, a wall may be bonded to a mounting substrate on which a solid-state imaging element having functional components formed substantially entirely may be mounted.

[0040] Example

[0041] Hereinafter, the present invention will be specifically described based on examples, but the present invention is not limited to the following examples.

[0042] Prototypes of solid-state imaging element packages having the structure of FIG2 were produced and their performance was evaluated. Specifically, a photocurable resin composition for forming a wall body was prepared and applied to a glass substrate, and a semi-cured wall body having a different distance (wall body distance) from the functional portion of the solid-state imaging element was formed by photolithography. Various optical substrates were produced by embossing a mold having concave and convex shapes pressed against the inner periphery of the semi-cured wall body. Prototypes 1 to 18 of the solid-state imaging element package were produced by bonding these optical substrates to a mounting substrate on which a solid-state imaging element was mounted. It should be noted that prototype 18 was not embossed. The wall body distances of these prototypes are summarized in Table 1.

[0043] To prepare the photocurable resin composition, first, 143 μL of a xylene solution of a platinum-vinylsiloxane complex ("Pt-VTSC-3X" manufactured by Umicore Precious Metals Japan, containing 3% platinum by mass) was added 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-tetrahydro-1,3,5,7-tetramethylcyclotetrasiloxane was dissolved in 176 g of toluene to obtain solution S2.

[0044] Then, under a nitrogen atmosphere containing 3% by volume of oxygen, while solution S2 was heated to 105°C, solution S1 was added dropwise to solution S2 over 3 hours. After the addition was completed, the temperature was maintained at 105°C and 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. Furthermore, under a nitrogen atmosphere containing 3% by volume of oxygen, while solution S3 was heated to 105°C, solution S4 was added dropwise to solution S3 over 1 hour. After the addition was completed, the temperature was maintained at 105°C and stirred for 30 minutes to obtain solution S5.

[0045] After cooling the solution S5, the solvent (toluene, xylene and 1,4-dioxane) was distilled off under reduced pressure from the solution S5 to obtain a solid component. Next, 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: "CELLOXIDE2021P" manufactured by Daicel Corporation), 1 part by mass of a sulfonium salt-based photocationic polymerization initiator ("CPI-210S" manufactured by San-Apro Corporation) and a black organic pigment ("NPFT-70565") (see Table 1 for the amount of compounding) were added to 100 parts by mass of the obtained solid component to obtain a photocurable resin composition for forming a wall. It should be noted that the light transmittance of the photocurable resin composition when 2 parts by mass of the black organic pigment is compounded is 4% at a wavelength of 600 nm.

[0046] The arithmetic mean roughness Ra (evaluation length: 20 μm) and skewness Ssk of the inner circumferential surface of the wall formed on the glass substrate were measured using the Olympus 3D measurement laser microscope "LEXT-OLS5100." Note that for skewness Ssk, 10 measurement locations (20 μm × 20 μm square areas) were randomly selected, and the average value of the skewness Ssk measured at the selected measurement locations was used (see Table 1).

[0047] In addition, the performance of the solid-state imaging element package is evaluated by the number of residues on the transparent substrate inside the wall, the ghosting index of the captured image, and the mapping in the captured image. Regarding the number of residues, a 1 mm square area of ​​the transparent substrate was observed using the 3D measurement laser microscope "LEXT-OLS4000" manufactured by Olympus Corporation. A D was assigned when there were more than 10 residues / foreign matter larger than 10 μm, a C when there were 6 to 9 residues / foreign matter, a B when there were 3 to 5 residues, and an A when there were 2 or fewer residues. Regarding the ghosting index, the GCS-2T ghosting and stray light evaluation system "Tsubosaka Electric" was used to determine the number of abnormal pixels exceeding a specified threshold (one hundred millionth relative to the brightness of the light source). The value (abnormal pixel number / total pixel number) was then divided by the total number of pixels and calculated as a percentage of the unembossed prototype 17 (see Table 1). Regarding mapping, images were captured using prototypes of 10 solid-state imaging element packages of the same specifications. A was set as the number of mapped solid-state imaging element packages being 0, B as the number being 1 or more and 4 or less, and C as the number being 5 or more.

[0048] [Table 1]

[0049]

[0050] As described above, it can be confirmed that by setting the arithmetic mean roughness Ra to greater than 50nm and less than 3000nm and the wall distance to greater than 100μm and less than 800μm, only a relatively small amount of pigment can be added to reduce the residue, ghosting index and mapping in the optical path. In other words, the image quality can be improved.

[0051] Description of Reference Numerals

[0052] 1 Solid-state imaging element package

[0053] 10 Install the base plate

[0054] 20 solid-state imaging element

[0055] 21 Function Department

[0056] 22 Connection

[0057] 23 Edge

[0058] 30 Optical substrate

[0059] 31 Transparent substrate

[0060] 32 Wall

[0061] 321 inner surface

[0062] 40 Sealing material

Claims

1. A solid-state imaging element package comprising: Transparent substrate; a frame-shaped wall formed of a resin composition containing a colorant, laminated on one main surface of the transparent substrate, and defining an inner space; and a solid-state imaging element that captures an image of light that passes through the transparent substrate and enters the inner space; The arithmetic mean roughness Ra of the inner peripheral surface of the wall body is greater than or equal to 50 nm and less than or equal to 3000 nm, The shortest distance between the wall and the functional portion of the solid-state imaging element is 800 μm or less.

2. The solid-state imaging element package according to claim 1, wherein The content of the colorant is 5% by mass or less.

3. The solid-state imaging element package according to claim 1 or 2, wherein: The skewness Ssk of the inner peripheral surface of the wall body is a negative value.

4. The solid-state imaging element package according to claim 1 or 2, wherein: The wall body is bonded to the solid-state imaging element.

5. The solid-state imaging element package according to claim 1 or 2, wherein: The wall body is formed of the photocurable resin composition.

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