Solid-state imaging element

Abstract

This solid-state imaging element is provided with: a semiconductor substrate (11) having a plurality of photoelectric conversion elements (12); a microlens layer (16) having a plurality of microlenses (17) that cause light (gamma) to enter the photoelectric conversion elements (12) of the semiconductor substrate (11); and color filters (14A-14C) provided between the semiconductor substrate (11) and the microlens layer (16), the color filters (14C) exhibiting a maximum value of transmittance at a wavelength of 400 nm to 500 nm, 50% of transmittance at a wavelength of 460 nm to 490 nm, and a refractive index smaller than the value of the microlens (17) at the wavelength of the transmittance at the maximum value.

Description

TECHNICAL FIELD

[0001] The present application relates to a solid-state imaging element such as a charge-coupled device or a complementary metal-oxide semiconductor. BACKGROUND

[0002] A solid-state imaging element such as a charge-coupled device (CCD) or a complementary metal-oxide semiconductor (CMOS) using a photoelectric conversion element such as a photodiode is applied to a digital still camera or a digital video camera. In such a solid-state imaging element, light incident light is condensed by a microlens and transmitted to a photoelectric conversion element via a color filter.

[0003] In such a solid-state imaging element, a color filter realized by dispersing a coloring composition of a pigment is generally used, but in recent years, in order to achieve an increase in sensitivity or color separation, a color filter realized by dispersing a coloring composition of a dye having a color characteristic superior to that of a pigment has been used (for example, see Patent Literature 1).

[0004] Patent Literature 1: Japanese Patent Application Laid-Open No. 2013-015817 SUMMARY

[0005] In the aforementioned solid-state imaging element, since a microlens is provided on a color filter, there is a concern that the refractive index of the color filter is greater than the refractive index of the microlens, and the condensing efficiency to a photoelectric conversion element decreases.

[0006] In view of such a situation, an object of the present application is to provide a solid-state imaging element capable of preventing a decrease in condensing efficiency to a photoelectric conversion element.

[0007] The solid-state imaging element according to the present application for solving the aforementioned problem has a semiconductor substrate having a plurality of photoelectric conversion elements, a microlens layer having a plurality of microlenses that cause light to be incident to the photoelectric conversion elements of the semiconductor substrate, respectively, and a color filter provided between the semiconductor substrate and the microlens layer, and is characterized in that, for the color filter, the transmittance exhibits a maximum value between wavelengths of 400 nm and 500 nm, and exhibits 50% between wavelengths of 460 nm and 490 nm, and the refractive index at the wavelength at which the transmittance exhibits the maximum value is a value smaller than that of the microlens.

[0008] Further, in the solid-state imaging element according to the present application, it is preferable that the color filter contain a blue pigment and a blue-violet dye.

[0009] Further, in the solid-state imaging element according to the present application, it is preferable that the color filter further contain a blue-violet pigment.

[0010] In addition, in the solid-state imaging device according to the present application, it is preferable that the proportion of the blue-violet dye and the blue-violet pigment of the color filter be greater than or equal to 0.1 and less than or equal to 1 with respect to the blue pigment.

[0011] In addition, in the solid-state imaging device according to the present application, it is preferable that the proportion of the blue-violet dye and the blue-violet pigment of the color filter be greater than or equal to 0.1 and less than or equal to 1 with respect to the blue pigment.

[0012] In addition, in the solid-state imaging device according to the present application, it is preferable that the proportion of the blue-violet dye and the blue-violet pigment of the color filter be greater than or equal to 0.1 and less than or equal to 1 with respect to the blue pigment.

[0013] In addition, in the solid-state imaging device according to the present application, it is preferable that the proportion of the blue-violet dye and the blue-violet pigment of the color filter be greater than or equal to 0.1 and less than or equal to 1 with respect to the blue pigment.

[0014] In addition, in the solid-state imaging device according to the present application, it is preferable that the proportion of the blue-violet dye and the blue-violet pigment of the color filter be greater than or equal to 0.1 and less than or equal to 1 with respect to the blue pigment.

[0015] In addition, in the solid-state imaging device according to the present application, it is preferable that the proportion of the blue-violet dye and the blue-violet pigment of the color filter be greater than or equal to 0.1 and less than or equal to 1 with respect to the blue pigment.

[0016] In addition, in the solid-state imaging device according to the present application, it is preferable that the proportion of the blue-violet dye and the blue-violet pigment of the color filter be greater than or equal to 0.1 and less than or equal to 1 with respect to the blue pigment.

[0017] Effects of the Invention

[0018] According to the solid-state imaging device according to the present application, the transmittance of the color filter exhibits a maximum value between wavelengths of 400 nm and 500 nm, and is 50% between wavelengths of 460 nm and 490 nm, and the refractive index of the color filter is a value smaller than that of the micro lens at the wavelength at which the transmittance exhibits the maximum value, so that it is possible to prevent a decrease in the light condensing efficiency of blue light from the micro lens toward the photoelectric conversion element, to achieve an improvement in the light condensing performance, and thus to improve the peak sensitivity between wavelengths of 400 nm and 500 nm. BRIEF DESCRIPTION OF DRAWINGS

[0019] Figure 1This is a cross-sectional view schematically showing the structure of a main part of a main embodiment of a solid-state imaging element according to the present invention.

[0020] Figure 2 This is a graph showing the relationship between wavelength and transmittance of the color filters of the test samples and the control samples.

[0021] Figure 3 This is a graph showing the relationship between wavelength and refractive index of the color filters and microlenses of the test samples and the control samples. DETAILED DESCRIPTION

[0022] The following describes embodiments of the solid-state imaging device according to the present invention based on the accompanying drawings. The present invention is not limited to the following embodiments described based on the accompanying drawings, and the unique technical features described in each embodiment can be appropriately combined as needed.

[0023] [Main implementation methods]

[0024] The following is based on Figures 1 to 3 , main embodiments of the solid-state imaging element according to the present invention are described.

[0025] like Figure 1 As shown, a plurality of photoelectric conversion elements 12, such as photodiodes, that convert light into electrical signals are two-dimensionally arranged within a semiconductor substrate 11, corresponding to pixels. Such a semiconductor substrate 11 is typically provided with a protective layer (not shown) on the outermost surface for the purpose of protecting and flattening the surface (light incident surface).

[0026] The semiconductor substrate 11 is formed of a material that transmits visible light and can withstand temperatures of approximately 300° C. Examples of such a material include Si, oxides such as SiO 2 , nitrides such as SiN, and Si-containing materials such as mixtures thereof.

[0027] On semiconductor substrate 11, a light-shielding layer 13 is disposed corresponding to the photosensitive regions of photoelectric conversion elements 12 to partially block incident light. On light-shielding layer 13, a plurality of color filters 14A-14C are disposed corresponding to the respective photoelectric conversion elements 12. Color filters 14A-14C are arranged in a predetermined pattern corresponding to the respective colors for color separation of incident light.

[0028] The color filters 14A-14C are arranged in a predetermined regular pattern, namely, a Bayer array, according to pixel positions so as to correspond to the plurality of photoelectric conversion elements 12. The color filters 14A-14C are not necessarily limited to the Bayer array, but may be other arrays.

[0029] A partition wall 15 is provided between adjacent color filters 14A to 14C. The provision of the partition wall 15 can also be omitted. A microlens layer 16 is provided on the color filters 14A to 14C, and a plurality of convex microlenses 17 are provided in the microlens layer 16 corresponding to each photoelectric conversion element 12. The microlenses 17 are hemispherical and each allow light to enter. That is, the color filters 14A to 14C are provided between the semiconductor substrate 11 and the microlens layer 16.

[0030] The refractive index of the microlenses 17 is greater than or equal to 1.60 and less than or equal to 1.65 in a range of wavelengths greater than or equal to 400 nm and less than or equal to 500 nm. As a material of the microlenses 17 having such a refractive index, for example, "TMR P15 (model number)" manufactured by Tokyo Otsuka Kogyo Co., Ltd. or the like can be given. Further, the microlenses 17 can also contain a filler material such as hollow silica filler.

[0031] The microlenses 17 preferably have a height (T1) that is the shortest length connecting the bottom and the top thereof, which is greater than or equal to 0.3 μm and less than or equal to 1.0 μm, and more preferably greater than or equal to 0.4 μm and less than or equal to 0.7 μm. This is because, if less than 0.3 μm, the light condensing property is degraded, which is not preferable, and if more than 1.0 μm, it is difficult to perform patterning by photolithography, which is not preferable.

[0032] Further, the color filters 14A to 14C are configured by adding a coloring agent of a prescribed color and various additives to a colorless transparent resin material. As the resin material of the color filters 14A to 14C, for example, an acrylic resin, an epoxy resin, or the like can be given.

[0033] In the color filter 14A, as the coloring material, for example, a green pigment (GP) such as C.I. Pigment Green 7, 10, 36, 37, 58, a zinc phthalocyanine pigment described in Japanese Patent Application Publication No. 2008-19383, Japanese Patent Application Publication No. 2007-320986, Japanese Patent Application Publication No. 2004-70342, or the like, an aluminum phthalocyanine pigment described in Japanese Patent No. 4893859, or the like is mixed.

[0034] In the color filter 14B, as the coloring material, for example, a red pigment (RP) such as a diketopyrrolopyrrole pigment described in C.I. Pigment Red 7, 14, 41, 48: 1, 48:2, 48:3, 48:4, 57:1, 81, 81:1, 81:2, 81:3, 81:4, 122, 146, 149, 166, 168, 169, 176, 177, 178, 179, 184, 185, 187, 200, 202, 208, 210, 221, 224, 242, 246, 254, 255, 264, 268, 269, 270, 272, 273, 274, 276, 277, 278, 279, 280, 281, 282, 283, 284, 285, 286, 287, Japanese Laid-Open Patent Publication No. 2011-523433, a naphthol pigment described in Japanese Laid-Open Patent Publication No. 2013-161025, or the like is mixed.

[0035] In the color filter 14C, as the coloring material, for example, a blue pigment (BP) such as a copper phthalocyanine pigment described in C.I. Pigment Blue 1, 1:2, 9, 14, 15, 15:1, 15:2, 15:3, 15:4, 15:6, 16, 22, 60, 64, Japanese Laid-Open Patent Publication No. 2004-333817, Japanese Patent No. 4893859, or the like, and a blue-violet dye (VD) such as C.I. Acid Red 50, 51, 52, 87, 91, 92, 94, 289, 388, C.I. Acid Violet 9, 30, 102, C.I. Basic Red 1 (Rhodamine 6G), 2, 3, 4, 8, 10, 11, C.I. Basic Violet 10 (Rhodamine B), 11, C.I. Solvent Red 218, C.I. Mordant Red 27, C.I. Reactive Red 36 (Rose Bengal B), Sulfurhodamine G, an xanthene dye described in Japanese Laid-Open Patent Publication No. 2010-32999, Japanese Patent No. 4492760, or the like, a cyanine dye, or the like are mixed. The color filter 14C preferably further has a blue-violet pigment (VP) such as a dioxazine pigment described in C.I. Pigment Violet 1, 19, 23, 29, 32, 36, 38, or the like mixed therein.

[0036] As the above-described additive, a sensitizer, an antioxidant, a dissolving oxidation-reduction agent, a leveling agent, a storage stabilizer, a adhesion promoter, a dispersion aid, or the like can be cited.

[0037] In the color filter 14A, it is preferable that the proportion of the mass of the green pigment (GP) contained with respect to the mass of the total solid content (TS) falls within a range of 30% or more and 65% or less, and more preferably falls within a range of 50% or more and 65% or less. This is because, if the mass percentage is less than 50%, it is difficult to sufficiently exert the function as a color filter, and is not preferable, and if the mass percentage exceeds 65%, the light-sensitive component is likely to be insufficient, it is difficult to form a pattern, and is not preferable.

[0038] In the color filter 14B, it is preferable that the proportion of the mass of the red pigment (RP) contained with respect to the mass of the total solid content (TS) falls within a range of 30% or more and 65% or less, and more preferably falls within a range of 50% or more and 65% or less. This is because, if the mass percentage is less than 50%, it is difficult to sufficiently exert the function as a color filter, and is not preferable, and if the mass percentage exceeds 65%, the light-sensitive component is likely to be insufficient, it is difficult to form a pattern, and is not preferable.

[0039] Also, in the color filter 14C, it is preferable that the proportion (VP / VD) of the blue-violet pigment (VP) with respect to the blue-violet dye (VD) is 0.1 or more and 10 or less, and more preferably is 0.1 or more and 1 or less. This is because, if it is less than 0.1, the light resistance is likely to decrease, and is not preferable, and if it exceeds 10, the color characteristics are likely to decrease, and is not preferable.

[0040] Further, in the color filter 14C, it is preferable that the proportion (VDP / BP) of the total amount (VDP) of the blue-violet dye (VD) and the blue-violet pigment (VP) with respect to the blue pigment (BP) is 0.1 or more and 1 or less, and more preferably is 0.1 or more and 0.5 or less. This is because, if it is less than 0.1, crosstalk between the green (Green) is likely to become large, the color reproducibility is likely to decrease, and is not preferable, and if it exceeds 1, a convex peak is likely to occur on the long-wavelength side of the light spectrum, the color purity is likely to decrease, and is not preferable.

[0041] Further, in the color filter 14C, it is preferable that the proportion of the mass of the blue pigment (BP), the blue-violet dye (VD), and the blue-violet pigment (VP) contained with respect to the mass of the total solid matter (TS) falls within a range of 30% or more and 70% or less, and more preferably, the proportion of the mass of the blue pigment (BP), the blue-violet dye (VD), and the blue-violet pigment (VP) contained with respect to the mass of the total solid matter (TS) falls within a range of 45% or more and 55% or less. This is because, if the mass percentage is less than 30%, it is difficult to sufficiently exert the function as a color filter, and is not preferable, and if the mass percentage exceeds 70%, the transmittance of light is decreased, and is not preferable.

[0042] Such a color filter 14C according to the present embodiment has a transmittance that has a maximum value in a range of wavelengths of 400 nm or more and 500 nm or less, that is, exhibits a maximum value between wavelengths of 400 nm and 500 nm (refer to Figure 2 ). Further, the transmittance of the color filter 14C becomes 50% in a range of wavelengths of 460 nm or more and 490 nm or less, that is, exhibits 50% between wavelengths of 460 nm and 490 nm (refer to Figure 2 ). In addition, the refractive index of the color filter 14C exhibits a value (1.5 or more and less than 1.6) smaller than that of the microlens 17 at the wavelength of the transmittance of the aforementioned maximum value (refer to Figure 3 ).

[0043] The color filters 14A to 14C preferably have a thickness T2 in the light transmission direction of 0.3 μm or more and 1.0 μm or less, and more preferably, 0.4 μm or more and 0.7 μm or less. This is because, if less than 0.3 μm, it is difficult to sufficiently exert the function as a color filter, and is not preferable, and if more than 1.0 μm, light is difficult to reach the bottom of the film due to absorption of the pigment at the time of exposure, and a decrease in patterning properties is easily caused, and is not preferable.

[0044] The solid-state imaging device 10 according to the present embodiment described above can be manufactured by applying a publicly known method. That is, the light-shielding layer 13 is provided on the semiconductor substrate 11 on which the photoelectric conversion elements 12 are provided, the color filters 14A to 14C and the partition walls 15 are provided on the light-shielding layer 13, and then the microlens layer 16 is further provided, and the microlenses 17 are formed in the microlens layer 16 by etching or the like.

[0045] In the solid-state imaging device 10 according to the present embodiment, if light γ is incident to the microlenses 17, the light γ is color-separated by the color filters 14A to 14C by condensing by the microlenses 17, and is transmitted to the respective photoelectric conversion elements 12 via the light-shielding layer 13.

[0046] At this time, the transmittance of the color filter 14C has a maximum value in a range of wavelengths of 400 nm or more and 500 nm or less, and is 50% in a range of wavelengths of 460 nm or more and 490 nm or less, and the refractive index at the wavelength at which the transmittance has the aforementioned maximum value is a value (1.5 or more and less than 1.6) smaller than the value (1.60 or more and 1.65 or less) of the microlens 17. Therefore, it is possible to prevent a decrease in the condensing efficiency of blue light from the microlens 17 to the photoelectric conversion element 12, and to achieve an improvement in the condensing performance.

[0047] Therefore, according to the solid-state imaging device 10 related to the present embodiment, it is possible to prevent a decrease in the condensing efficiency, to achieve an improvement in the condensing performance, and thus to improve the peak sensitivity in a range of wavelengths of 400 nm or more and 500 nm or less.

[0048] Further, as the resin material constituting the microlens or the color filter, as the substituent contributing to the refractive index, generally, first, there are -SC6H5 > -COC6H5 > -OC6H5 > -C6H5 including a benzene ring, and second, there are -NH2 > -NO2 > -OH > -CN > -OCH3 or polyhalogen (-I) > -Br > -Cl, and the like. On the other hand, a pyridine structure or an alkyl group hardly changes the refractive index, and -F has an effect of significantly decreasing the refractive index due to its small polarizability.

[0049] Here, in order to confirm the effects of the solid-state imaging device related to the present application, the test sample of the solid-state imaging device 10 described in the foregoing embodiment was produced under the following conditions, and a conventional comparative sample to be a comparative object was produced under the following conditions. Figure 1 The test sample of the solid-state imaging device 10 shown in the foregoing embodiment was produced under the following conditions, and a conventional comparative sample to be a comparative object was produced under the following conditions.

[0050] <Test Sample>

[0051]

[0052] Resin material: Acrylic resin

[0053] Blue pigment (BP): Copper phthalocyanine-based pigment

[0054] Blue-violet dye (VD): Xanthene-based dye

[0055] Blue-violet pigment (VP): Dioxazine-based pigment

[0056] Ratio of blue-violet pigment (VP) to blue-violet dye (VD) (VP / VD): 0.5

[0057] ​• Ratio (VDP / BP) of total amount (VDP) of blue-violet dye (VD) and blue-violet pigment (VP) to blue pigment (BP): 0.42

[0058] • Ratio (BVPD / TS) of total mass (BVPD) of blue pigment (BP), blue-violet dye (VD), and blue-violet pigment (VP) to total solid (TS): 53%

[0059] • Thickness: 0.7 μm

[0060] • Transmittance: Reference Figure 2

[0061] • Refractive index: Reference Figure 3

[0062] Lenticule 17

[0063] • Resin material: Phenol resin

[0064] • Height: 0.5 μm

[0065] • Refractive index: Reference Figure 3

[0066] Control sample

[0067] The same conditions as the above test sample were set except that the mixing of blue-violet dye (VD) was omitted.

[0068] • Transmittance: Reference Figure 2

[0069] • Refractive index: Reference Figure 3

[0070] From Figure 2 it was found that, in the case of the above color filter, the transmittance of both the test sample and the control sample exhibited a maximum value at a wavelength of 450 nm. From Figure 3 it was found that, in the case of the above color filter, the refractive index of the control sample at a wavelength of 450 nm (1.625) was equal to the refractive index of the lenticule. In contrast, the refractive index of the test sample (1.59) was less than the refractive index of the lenticule (1.625).

[0071] When the sensor characteristics of such above test sample and above control sample were measured by a test device, it was confirmed that, in terms of peak sensitivity at a wavelength of 450 nm, the test sample was improved by 3.2% compared to the control sample. This was considered to be due to the fact that the 3.2% was greater than the difference (2.1%) between the transmittance at a wavelength of 450 nm of the above color filter of the test sample (83.7%) and the transmittance at a wavelength of 450 nm of the above color filter of the control sample (81.6%), so that the light condensing efficiency was improved and the light condensing performance was improved.

[0072] And, the peak transmittance was calculated for the color filter in which the values of the above-mentioned VP / VD, the above-mentioned VDP / BP, and the above-mentioned BVPD / TS were changed as in Examples 1-10. And, the peak transmittance difference (values calculated by subtracting the value of the above-mentioned color filter as a control sample at a wavelength of 450 nm (81.6%) from each value of Examples 1-10, respectively) was calculated for each of the difference between the transmittance at a wavelength of 450 nm of the above-mentioned color filter as a control sample. The results thereof are shown in Table 1 below.

[0073] [Table 1]

[0074] Example VP / VD VDP / BP BVPD / TS Peak transmittance difference 1 10.0 0.42 53％ 0.8％ 2 1.0 0.42 53％ 4.6％ 3 0.1 0.42 53％ 8.6％ 4 0.5 1.00 53％ 3.0％ 5 0.5 0.50 53％ 5.6％ 6 0.5 0.10 53％ 10.0％ 7 0.5 0.42 70％ 2.2％ 8 0.5 0.42 55％ 5.7％ 9 0.5 0.42 45％ 8.2％ 10 0.5 0.42 30％ 12.0％

[0075] From Table 1, it is known that the peak transmittance difference of Examples 1-10 is all positive (greater than or equal to 0.8%), and the effect of the solid-state imaging device according to the present application can be confirmed.

[0076] Industrial applicability

[0077] The solid-state imaging device according to the present application can improve the peak sensitivity between a wavelength of 400 nm and 500 nm, and thus can be extremely effectively applied in various industries.

[0078] Explanation of reference numerals

[0079] 10 solid-state imaging device

[0080] 11 semiconductor substrate

[0081] 12 photoelectric conversion element

[0082] 13 light-blocking layer

[0083] 14A-14C color filter

[0084] 15 partition wall

[0085] 16 microlens layer

[0086] 17 microlens

Claims

1. A solid-state imaging element comprising: a semiconductor substrate having a plurality of photoelectric conversion elements; a microlens layer having a plurality of microlenses for respectively allowing light to enter the photoelectric conversion elements of the semiconductor substrate; as well as a color filter disposed between the semiconductor substrate and the microlens layer, This solid-state imaging element is characterized in that As the color filter, The transmittance reaches a maximum value between 400nm and 500nm, and reaches 50% between 460nm and 490nm. The refractive index is a value smaller than a value of the microlens at a wavelength where the transmittance reaches the maximum value.

2. The solid-state imaging element according to claim 1, wherein The color filter contains a blue pigment and a blue-violet dye.

3. The solid-state imaging element according to claim 2, wherein The color filter also contains a blue-violet pigment.

4. The solid-state imaging element according to claim 3, wherein The ratio of the blue-violet pigment to the blue-violet dye of the color filter is greater than or equal to 0.1 and less than or equal to 10.

5. The solid-state imaging element according to claim 4, wherein The ratio of the total amount of the blue-violet dye and the blue-violet pigment of the color filter to the blue pigment is greater than or equal to 0.1 and less than or equal to 1.

6. The solid-state imaging element according to claim 5, wherein The ratio of the mass of the blue pigment, the blue-violet dye, and the blue-violet pigment contained in the color filter to the mass of the total solids falls within a range of greater than or equal to 30% and less than or equal to 70%.

7. The solid-state imaging element according to any one of claims 1 to 6, characterized in that The refractive index of the color filter is greater than or equal to 1.5 and less than 1.6 at the wavelength where the transmittance reaches the maximum value.

8. The solid-state imaging element according to any one of claims 1 to 6, wherein The color filter has a thickness greater than or equal to 0.3 μm and less than or equal to 1.0 μm.

9. The solid-state imaging element according to any one of claims 1 to 6, wherein The refractive index of the microlens is greater than or equal to 1.60 and less than or equal to 1.65 within a wavelength range of greater than or equal to 400 nm and less than or equal to 500 nm.

10. The solid-state imaging element according to any one of claims 1 to 6, characterized in that The height of the microlens is greater than or equal to 0.3 μm and less than or equal to 1.0 μm.

Images