Light detection device

Abstract

[Problem] To provide technology which is advantageous for effectively inputting light in a desired wavelength region into a photoelectric conversion unit while suppressing the thickness of an optical filter unit. [Solution] A light detection device comprising a photoelectric conversion unit that has a plurality of photoelectric conversion elements, and an optical filter unit that is provided so as to cover the plurality of photoelectric conversion elements and that has a plurality of filter regions which are respectively associated with the plurality of photoelectric conversion elements, wherein at least some of the plurality of filter regions have multilayer structure bodies in which a wavelength selection filter layer that selectively transmits light in a specific wavelength region and another filter layer having a different refractive index from that of the wavelength selection filter layer are arranged alternatingly in a layering direction.

Description

Photodetector

[0001] The present disclosure relates to a light detection device.

[0002] In a solid-state imaging device, light is generally split using a color filter, and light in a desired visible wavelength range is selectively received.

[0003] For example, the solid-state imaging device disclosed in Patent Document 1 includes, as color filters, three types of colorant composition layers that selectively transmit red (R), green (G), and blue (B) light, respectively.

[0004] JP 2010-078680 A

[0005] When spectral separation is performed using only a color filter such as a colorant composition layer, the color filter is required to have an appropriate film thickness so that it transmits light in a desired visible wavelength range while suppressing the transmission of light in other wavelength ranges. If the color filter does not have a sufficient film thickness, it may not be possible to sufficiently suppress the transmission of light in unintended wavelength ranges, and as a result, color mixing may become noticeable in the data output from the photoelectric conversion element.

[0006] Thus, in order to properly separate light using color filters, the thickness of the color filters tends to be large.

[0007] In addition, in the solid-state imaging device of Patent Document 1, a dielectric multilayer film layer having excellent light resistance is additionally laminated on a colorant-containing composition layer having excellent spectral characteristics. In this case, the thickness of the dielectric multilayer film layer is added to the thickness of the colorant-containing composition layer, which tends to further increase the thickness of the entire filter.

[0008] On the other hand, although the overall size of devices is being reduced, an increase in the film thickness of color filters can be a factor that hinders the miniaturization of devices.

[0009] In recent years, the size of each pixel in solid-state imaging devices has been reduced, but the smaller the planar size of each pixel, the more likely it is that obliquely incident light will be incident on the separation walls between pixels. When obliquely incident light hits the separation walls, the light is absorbed or scattered by the separation walls, which can result in a decrease in pixel sensitivity and an increase in color mixing.

[0010] The incidence of obliquely incident light on the separation wall tends to occur more easily as the film thickness of the color filter increases. Reducing the film thickness of the color filter is an effective way to prevent such obliquely incident light from entering the separation wall. However, as described above, reducing the film thickness of the color filter reduces the spectral performance of the color filter, which can result in increased color mixing.

[0011] The present disclosure provides a technique that is advantageous for effectively making light in a desired wavelength range incident on a photoelectric conversion section while suppressing the thickness of an optical filter section.

[0012] One aspect of the present disclosure relates to a photodetector device having a multilayer structure including a photoelectric conversion unit having a plurality of photoelectric conversion elements, and an optical filter unit arranged to cover the plurality of photoelectric conversion elements and having a plurality of filter regions corresponding to each of the plurality of photoelectric conversion elements, at least some of the plurality of filter regions being formed by alternating wavelength-selective filter layers that selectively transmit light in a specific wavelength range and other filter layers having a refractive index different from that of the wavelength-selective filter layers in the stacking direction.

[0013] The wavelength-selective filter layer may be a color filter that transmits light in a specific wavelength range in the visible light wavelength range.

[0014] The multilayer structure may have layers containing an organic material and layers containing an inorganic material alternately arranged in the stacking direction, and the wavelength selection filter layer may be formed from a layer containing an organic material.

[0015] In the multilayer structure, the transmission wavelength ranges due to Fabry-Perot interference of the wavelength-selective filter layer and the other filter layers may correspond to at least a part of the specific wavelength range of light selectively transmitted by the wavelength-selective filter layer.

[0016] The multilayer structure may include a plurality of wavelength-selective filter layers.

[0017] Other filter layers may include metal oxides or silicon oxides.

[0018] The metal oxide may be any of titanium oxide, tantalum oxide, hafnium oxide, and aluminum oxide.

[0019] At least one other filter layer may have regularly arranged first refractive index members and second refractive index members having a refractive index different from that of the first refractive index members.

[0020] The first refractive index member may be different from the member included in the wavelength selection filter layer.

[0021] The second refractive index member may be the same as the member included in the wavelength selection filter layer.

[0022] The optical filter portion may include a plurality of unit filter regions, each of which may include a first filter region that selectively transmits first polarized light vibrating in a first vibration direction, a second filter region that selectively transmits second polarized light vibrating in a second vibration direction that forms an angle of 90° with the first vibration direction, a third filter region that selectively transmits third polarized light vibrating in a third vibration direction that forms an angle of 45° with the first vibration direction and the second vibration direction, and a fourth filter region that selectively transmits fourth polarized light vibrating in a fourth vibration direction that forms an angle of 45° with the first vibration direction and the second vibration direction and forms an angle of 90° with the third vibration direction.

[0023] In the first filter region, a plurality of first refractive index members extending in a direction perpendicular to the first vibration direction may be provided, in the second filter region, a plurality of first refractive index members extending in a direction perpendicular to the second vibration direction may be provided, in the third filter region, a plurality of first refractive index members extending in a direction perpendicular to the third vibration direction may be provided, and in the fourth filter region, a plurality of first refractive index members extending in a direction perpendicular to the fourth vibration direction may be provided.

[0024] In each filter region, a plurality of columnar structures including the first refractive index member may be regularly arranged.

[0025] In each filter region, the cross-sectional size of the plurality of structures in a direction perpendicular to the stacking direction may gradually change based on the direction perpendicular to the stacking direction.

[0026] FIG. 1 is a schematic diagram showing an example of the configuration of an image sensor. FIG. 2 is an enlarged cross-sectional view showing an example of an optical transmission control section and a photoelectric conversion section. FIG. 3 is a cross-sectional view showing a simplified stacked structure of an on-chip lens, a color filter (particularly a G color filter), a semiconductor oxide film, and a photoelectric conversion section in the example image sensor shown in FIG. 2. FIG. 4 is a diagram showing an example of the optical transmittance and reflectance of the optical transmission control section in the image sensor (particularly a G pixel region) shown in FIG. 3. FIG. 5 is a cross-sectional view showing an example of the behavior of obliquely incident light when the planar size (aperture size) of each pixel of the image sensor is relatively large. FIG. 6 is a cross-sectional view showing an example of the behavior of obliquely incident light when the planar size (aperture size) of each pixel of the image sensor is relatively small. FIG. 7 is an enlarged perspective view showing a simplified example of the stacked structure of an image sensor (particularly one pixel region) including a multilayer structure according to the first embodiment. FIG. 8 is an enlarged perspective view showing a simplified example of the stacked structure of an image sensor (particularly one pixel region (G pixel region)) including a multilayer structure according to the first embodiment. FIG. 9 is an enlarged cross-sectional view showing an example of a combination of a light transmission control section to which the multilayer structure shown in FIG. 8 is applied and a photoelectric conversion section. FIG. 10 is a diagram showing an example of the light transmittance and reflectance in the light transmission control section (particularly the G filter region including the multilayer structure) of the image sensor of the example shown in FIGS. 8 and 9 . FIG. 11 is an enlarged perspective view simply showing another example of the stacked structure of an image sensor (particularly one pixel region (G pixel region)) including the multilayer structure according to the first embodiment. FIG. 12 is an enlarged perspective view simply showing an example of the stacked structure of an image sensor (particularly one pixel region (G pixel region)) including the multilayer structure according to the second embodiment. FIG. 13 shows an example of an XY cross section of another filter layer (particularly a unit filter region) shown in FIG. 12 . FIG. 14 shows an example of an XY cross section of another filter layer included in the multilayer structure of the optical filter section according to the third embodiment. FIG. 15 is an enlarged perspective view simply showing an example of a multilayer structure (optical filter section) including the other filter layer shown in FIG. 14 and an on-chip lens, showing an example of the relationship between incident light and emitted light.

[0027] Exemplary embodiments of the disclosed technology will be described with reference to the drawings.

[0028] Unless otherwise specified, the following describes a case where the disclosed technology is applied to an image sensor (solid-state image sensor) that can be applied to an imaging camera system, etc. However, the application of the disclosed technology is not limited, and the disclosed technology may also be applied to other light detection devices (e.g., sensors) that can be used for purposes other than imaging.

[0029] Each element in the drawings is shown schematically or conceptually. Therefore, the size, shape, and other characteristics of each element in the drawings may differ from the characteristics of the corresponding element in reality. The size ratios between elements in the drawings may also differ from the size ratios between corresponding elements in the actual device. Furthermore, the size, shape, and size ratios of each element do not necessarily match between the drawings, and one or more specific elements may be exaggerated in each drawing.

[0030] In the following description, the X, Y, and Z directions are perpendicular to one another. As an example, the X direction may correspond to the horizontal direction, the Y direction may correspond to the vertical direction (height direction), and the Z direction may correspond to the depth direction. Furthermore, an XY plane / cross section is a surface extending in the X and Y directions, an XZ plane / cross section is a surface extending in the X and Z directions, and a YZ plane / cross section is a surface extending in the Y and Z directions.

[0031] Fig. 1 is a schematic diagram showing an example of the configuration of an image sensor 1. In Fig. 1, the optical transmission control unit 10 and the photoelectric conversion unit 11 are shown as viewed obliquely, and the optical system OP is shown as viewed from the side.

[0032] The image sensor 1 can typically be configured by a CCD (Charge Coupled Device) image sensor or a CMOS (Complementary Metal Oxide Semiconductor) image sensor, but the image sensor 1 can also be configured by any imaging device.

[0033] The image sensor 1 receives light from an external subject (object) and outputs information about the light as an electrical signal.

[0034] The image sensor 1 shown in Fig. 1 includes an optical system OP, an optical transmission control unit 10, and a photoelectric conversion unit 11. The optical system OP includes a lens that collects incident light L from a subject. The incident light L that passes through the optical system OP may include front incident light La that travels in a direction along the optical axis (optical axis direction) and oblique incident light Lb that travels in a direction oblique to the optical axis. In the example shown in Fig. 1, the Z direction coincides with the optical axis direction.

[0035] The photoelectric conversion unit 11 includes a plurality of light-receiving pixels (photoelectric conversion elements) PX that receive incident light L. In the example shown in FIG. 1 , the plurality of light-receiving pixels PX are arranged two-dimensionally in the X and Y directions, and the photoelectric conversion unit 11 as a whole has a rectangular light-receiving surface with sides extending in the X and Y directions. When the traveling direction of the chief ray of incident light L entering the image sensor 1 coincides with the optical axis direction, the light-receiving pixel PX located in the center of the photoelectric conversion unit 11 (0% image height) receives frontal incident light La. On the other hand, the light-receiving pixel PX located away from the center of the photoelectric conversion unit 11 (e.g., the light-receiving pixel PX located at the end of the photoelectric conversion unit 11 (e.g., 100% image height)) receives oblique incident light Lb.

[0036] The photoelectric conversion unit 11 is an element that converts received incident light into an electrical signal. Each light-receiving pixel PX of the photoelectric conversion unit 11 can typically be configured as a photodiode (e.g., made of a silicon (Si) semiconductor material) that converts light into an electric current using a pn junction of a semiconductor.

[0037] The optical transfer control unit 10 is disposed in the optical path between the optical system OP and the photoelectric conversion unit 11, and is provided so as to cover the multiple light-receiving pixels PX (light-receiving surfaces) of the photoelectric conversion unit 11. The optical transfer control unit 10 has the function of guiding multiple light components in the incident light L to the corresponding light-receiving pixels PX, and can have various configurations as described below.

[0038] For example, the portion of the optical transfer control unit 10 that covers the light-receiving pixel PX located in the center of the photoelectric conversion unit 11 focuses the frontal incident light La onto the light-receiving pixel PX located in the center of the photoelectric conversion unit 11. On the other hand, the portion of the optical transfer control unit 10 that covers the light-receiving pixel PX located at the edge of the photoelectric conversion unit 11 focuses the obliquely incident light Lb onto the light-receiving pixel PX located at the edge of the photoelectric conversion unit 11. In this way, each portion of the optical transfer control unit 10 guides the desired light component contained in the incident light L incident at various angles to the corresponding light-receiving pixel PX.

[0039] 1 includes an optical filter unit 20 that selectively transmits one or more types of light in a desired wavelength range. The optical filter unit 20 is provided to cover the photoelectric conversion unit 11 (plurality of light-receiving pixels PX) and has multiple filter regions that correspond to (i.e., are assigned to) each of the multiple light-receiving pixels PX. Each filter region selectively transmits light in a wavelength range assigned to the corresponding light-receiving pixel PX, and each light-receiving pixel PX receives light in the desired wavelength range that has transmitted through the corresponding filter region.

[0040] 2 is an enlarged cross-sectional view showing an example of the optical transmission control unit 10 and the photoelectric conversion unit 11. In FIG. 2, two pixel regions (particularly the optical transmission control unit 10 and the photoelectric conversion unit 11) of the image sensor 1 are shown.

[0041] 2, the image sensor 1 includes an optical filter unit 20 formed of a color filter 21. That is, the light transmission control unit 10 includes an on-chip lens 15, a color filter 21, a light-shielding film 16, and a semiconductor oxide film 17.

[0042] The semiconductor oxide film 17 is disposed so as to cover the photoelectric conversion unit 11 (plurality of light-receiving pixels PX), and is made of, for example, SiO ２ A color filter 21 and a light-shielding film 16 are disposed on the semiconductor oxide film 17. On the opposite side of the color filter 21 from the semiconductor oxide film 17, an on-chip lens 15 is disposed so as to cover the color filter 21.

[0043] The color filter 21 is made of color resist and is produced, for example, by mixing a color material (for example, a pigment or dye) with a light-transmitting material (for example, a transparent material such as a resin material). Figure 2 illustrates, as the color filter 21, a G color filter (G-CF) that selectively transmits green (G) light and an R color filter (R-CF) that selectively transmits red (R) light. However, the image sensor 1 in the example shown in Figure 2 also includes, as the color filter 21, a B color filter (not shown) that selectively transmits blue (B) light.

[0044] In the example shown in FIG. 2 , the incident light L is incident on the color filter 21 after its optical path is adjusted by the on-chip lens 15, and the R light, G light, and B light that pass through the color filter 21 are each focused on the light-receiving surface of the corresponding light-receiving pixel PX.

[0045] 3 is a cross-sectional view showing a simplified stacked structure of the on-chip lens 15, color filter (particularly G color filter (G-CF)) 21, semiconductor oxide film 17, and photoelectric conversion section 11 in the example image sensor 1 shown in FIG.

[0046] 4 is a diagram showing an example of the light transmittance TF and reflectance RF of the light transfer control unit 10 of the image sensor 1 (particularly the G pixel region) shown in FIG. The "transmittance TF" of the light transfer control unit 10 here is represented by the ratio of the intensity of light that has passed through the light transfer control unit 10 to the light that has entered the light transfer control unit 10. On the other hand, the "reflectance RF" of the light transfer control unit 10 is represented by the ratio of the intensity of light that travels from the light transfer control unit 10 toward the incident side (i.e., returns) to the light that has entered the light transfer control unit 10.

[0047] When the optical filter section 20 is composed of only the color filter 21 as in this example, the light transmittance TF and reflectance RF of the light transfer control section 10 are determined mainly by the light transmittance TF and reflectance RF of the color filter 21 .

[0048] The filter region having a G color filter (see FIG. 3) in the optical transmission control unit 10 of this example has a relatively high transmittance TF for light in a wavelength range that includes G light (e.g., light in a wavelength range of 500 to 565 nm), as shown in FIG. 4. On the other hand, the reflectance RF of the filter region having a G color filter in the optical transmission control unit 10 of this example is an extremely small value close to "0%" regardless of wavelength, as shown in FIG.

[0049] In this way, when the transmittance TF and reflectance RF of the light transmission control unit 10 are determined solely by the color filter 21, the specific values ​​of the transmittance TF and reflectance RF of the light transmission control unit 10 can vary depending on the film thickness t (thickness in the Z direction) of the color filter 21.

[0050] For example, when the thickness t of the color filter 21 is small, the optical transmission control unit 10 can exhibit a large transmittance TF for light in wavelength ranges other than the desired wavelength range (G light in the examples shown in FIGS. 3 and 4 ). On the other hand, when the thickness t of the color filter 21 is large, the optical transmission control unit 10 can exhibit a reduced transmittance TF for all light, including light in the desired wavelength range.

[0051] Fig. 5 is a cross-sectional view showing an example of the behavior of obliquely incident light L when the planar size (aperture size) of each pixel of the image sensor 1 is relatively large. Fig. 6 is a cross-sectional view showing an example of the behavior of obliquely incident light L when the planar size (aperture size) of each pixel of the image sensor 1 is relatively small.

[0052] 5 and 6 show one pixel region (particularly the optical transmission control unit 10 and the photoelectric conversion unit 11) of the image sensor 1. The image sensors 1 shown in each of Figures 5 and 6 have the same configuration and size except for the planar size of each pixel, and are equipped with color filters 21 of the same film thickness t.

[0053] When incident light L is obliquely incident on the image sensor 1, the incident light L travels (propagates) obliquely within the color filters 21. Such obliquely incident light L is more likely to be incident on the separation walls between the color filters 21 when traveling within color filters 21 having a relatively small planar size (see FIG. 6) than when traveling within color filters 21 having a relatively large planar size (see FIG. 5).

[0054] Incident light L that is incident on a separation wall between color filters 21 (i.e., an inter-pixel separation wall) is absorbed or scattered by the separation wall, and therefore is less likely to reach the corresponding light-receiving pixel PX. Therefore, the more likely obliquely incident light L is to be incident on an inter-pixel separation wall (see FIG. 6), the more likely it is that pixel sensitivity will decrease and color mixing will increase.

[0055] In this way, when there are restrictions on the aperture size (planar size) of each pixel due to miniaturization of pixels, reducing the film thickness t of the color filter 21 is effective in reducing the incidence of incident light L on the inter-pixel separation wall.

[0056] However, as the film thickness t of the color filter 21 decreases, the spectral performance of the color filter 21 decreases, and the transmittance of light in wavelength ranges other than the desired wavelength range increases, increasing the risk of color mixing.

[0057] An embodiment that is advantageous for reducing the film thickness of the optical filter section 20 while suppressing a decrease in the spectral performance of the optical filter section 20 will be described below as an example.

[0058] First Embodiment FIG. 7 is an enlarged perspective view showing a simplified example of a laminated structure of an image sensor 1 (particularly one pixel region) including a multilayer structure 23 according to a first embodiment.

[0059] The term "one pixel region" as used herein includes one light-receiving pixel PX and the optical transmission control section 10 (the on-chip lens 15, the multilayer structure 23, and the semiconductor oxide film 17), which is a waveguide section for directing incident light L (particularly a desired light component) into the one light-receiving pixel PX. The optical filter section 20 has a plurality of filter regions corresponding to the plurality of light-receiving pixels PX, respectively, and one pixel region includes one filter region.

[0060] 7 , at least some of the multiple filter regions of the optical filter unit 20 have a multilayer structure 23. In the multilayer structure 23, wavelength-selective filter layers (color filters 21 in this example) that selectively transmit light in a specific wavelength range and other filter layers 22 that have a refractive index different from that of the wavelength-selective filter layers are alternately arranged in the stacking direction (Z direction).

[0061] The color filters 21 and other filter layers 22 of the multilayer structure 23 having such a stacked configuration cause Fabry-Perot interference. In particular, the film thicknesses of the color filters 21 and other filter layers 22 are set so that the transmission wavelength ranges due to Fabry-Perot interference of the color filters 21 and other filter layers 22 correspond to at least a part of the specific wavelength range of light selectively transmitted by the color filters 21.

[0062] The wavelength-selective filter layer shown in Fig. 7 is a color filter 21 that transmits light in a specific wavelength range in the visible light wavelength range. The multilayer structure 23 shown in Fig. 7 includes multiple color filters 21 (two layers in the example shown in Fig. 7) each made of a layer containing an organic material. However, the wavelength-selective filter layer (color filter 21) can be made of any material, and there is no limit to the number of wavelength-selective filter layers included in the multilayer structure 23, nor is there any limit to the specific wavelength range of light that the wavelength-selective filter layer can selectively transmit.

[0063] The other filter layer 22 may have any composition, but works in conjunction with the color filter 21 to produce Fabry-Perot interference that can selectively transmit light in a desired wavelength range.

[0064] Therefore, the other filter layer 22 preferably has low absorptance and reflectance of light in the specific wavelength range that is selectively transmitted through the multilayer structure 23. The other filter layer 22 preferably has a material and composition that can provide a refractive index difference between the other filter layer 22 and the color filter 21 that is advantageous for causing Fabry-Perot interference.

[0065] Such other filter layers 22 may typically be made of inorganic materials, and may include inorganic materials such as metal oxides and silicon oxides.

[0066] In this way, the multilayer structure 23 may be configured by alternately arranging layers of color filters 21 containing organic materials and other filter layers 22 containing inorganic materials.

[0067] 7, such a multilayer structure 23 is disposed above the photoelectric conversion unit 11 (light-receiving pixel PX) via a semiconductor oxide film 17. Then, an on-chip lens 15 is disposed on the multilayer structure 23.

[0068] The multilayer structure 23 may be provided in all of the filter regions corresponding to the light-receiving pixels PX, or may be provided in only some of the filter regions.

[0069] For example, the multilayer structure 23 may be provided only in one specific type of filter region that can selectively transmit light of a specific color among light of multiple colors (e.g., RGB) that is intended to be selectively transmitted through the optical filter unit 20 and received by the photoelectric conversion unit 11. Alternatively, the multilayer structure 23 may be provided only in two specific types of filter regions that can selectively transmit light of two specific colors, respectively. Alternatively, the multilayer structure 23 may be provided in three or more specific types of filter regions that can selectively transmit light of three or more specific colors (e.g., light of all colors received by the photoelectric conversion unit 11).

[0070] The types of filter regions here are classified based on the wavelength ranges of light that can be selectively transmitted, and correspond to the wavelength ranges of light that are intended to be incident on the corresponding light-receiving pixels PX. For example, if R light, G light, and B light are received by the photoelectric conversion unit 11, each of the multiple filter regions of the optical filter unit 20 is configured as either an R filter region, a G filter region, or a B filter region that can selectively transmit R light, G light, and B light, respectively.

[0071] Generally, color mixing is likely to occur between the light-receiving pixels PX that receive G light and the light-receiving pixels PX that receive R light, and in terms of human visual characteristics, sensitivity to G light tends to be relatively higher than that to R light and B light. For this reason, the multilayer structure 23 can be effectively applied to the G filter region.

[0072] Furthermore, the wavelength of transmitted light due to Fabry-Perot interference in the multilayer structure 23 is affected by the film thickness of the color filters 21 and other filter layers 22 that constitute the multilayer structure 23. Therefore, the film thickness of each of the color filters 21 and other filter layers 22 that constitute the multilayer structure 23 is determined according to the intended wavelength of transmitted light, and depends on the desired wavelength of transmitted light assigned to each filter region.

[0073] Specifically, the shorter the wavelength of transmitted light assigned to a filter region, the thinner the film thickness of each of the layers 21, 22 constituting the multilayer structure 23 in that filter region. The thinner the film thickness of each of the layers 21, 22 constituting the multilayer structure 23, the more layers 21, 22 can be stacked for a given thickness in the stacking direction of the multilayer structure 23. The greater the number of layers 21, 22 constituting the multilayer structure 23, the greater the Fabry-Perot interference effect that can be obtained, and as a result, light in a desired wavelength range can be selectively transmitted through the multilayer structure 23 (filter region) with higher precision.

[0074] Therefore, the multilayer structure 23 can be effectively applied to a filter region that can selectively transmit light in a relatively short wavelength range among the multiple colors of light received by the photoelectric conversion unit 11. For example, if the multiple filter regions of the optical filter unit 20 include an R filter region, a G filter region, and a B filter region, the multilayer structure 23 can be effectively applied to the B filter region that selectively transmits B light in a wavelength range shorter than that of the R light and the G light.

[0075] FIG. 8 is an enlarged perspective view showing a simplified example of a layered structure of the image sensor 1 (particularly one pixel region (G pixel region)) including the multilayer structure 23 according to the first embodiment. FIG. 9 is an enlarged cross-sectional view showing an example of a combination of the light transmission control section 10 to which the multilayer structure 23 shown in FIG. 8 is applied and the photoelectric conversion section 11. FIG. 10 is a diagram showing an example of the light transmittance TF and reflectance RF in the light transmission control section 10 (particularly the G filter region including the multilayer structure 23) of the image sensor 1 of the example shown in FIGS. 8 and 9 .

[0076] As described above, in the multilayer structure 23, the other filter layer 22 included together with the color filter (wavelength selection filter layer) 21 may contain, for example, a metal oxide. Such a metal oxide included in the other filter layer 22 may be, for example, any one of titanium oxide, tantalum oxide, hafnium oxide, and aluminum oxide.

[0077] 8 to 10, the multilayer structure 23 is provided only in the G filter region (G pixel) among the plurality of filter regions. The other filter layer 22 of the multilayer structure 23 is made of inorganic material TiO ２ (Titanium (IV) oxide) containing TiO ２ A planar membrane is provided.

[0078] On the other hand, among the multiple filter regions of the optical filter section 20, the R filter region (R pixel) and the B filter region (B pixel) are not provided with the multilayer structure 23, and the optical filter section 20 is constituted by the color filters 21 (R color filter and B color filter).

[0079] 10 , for light in the wavelength range of G light (for example, light in the wavelength range of 500 to 565 nm), the transmittance TF of the G filter region (i.e., the filter region including the multilayer structure 23) of the optical transmission control unit 10 is relatively high and the reflectance RF is relatively low. On the other hand, for light in wavelength ranges other than G light (for example, light in wavelength ranges shorter than 500 nm or longer than 565 nm), the transmittance TF of the G filter region is relatively low and the reflectance RF is relatively high.

[0080] In this way, the filter region including the multilayer structure 23 can effectively transmit light in a desired wavelength range while effectively suppressing reflection of the light in the desired wavelength range. In addition, the filter region including the multilayer structure 23 can effectively reflect light outside the desired wavelength range while effectively suppressing transmission of light outside the desired wavelength range.

[0081] Therefore, the filter region including the multilayer structure 23 can selectively transmit light in the desired wavelength range with high precision, and can effectively reduce the mixing of light outside the desired wavelength range with the light in the desired wavelength range that has passed through the filter region.

[0082] The specific transmittance TF and reflectance RF of the light transmission control section 10 and the optical filter section 20 in the filter region including the multilayer structure 23 are not limited.

[0083] As described above, the "light in a specific wavelength range" referred to here corresponds to light in a wavelength range that can be selectively transmitted by the color filter 21 included in the multilayer structure 23, and if the color filter 21 is a G color filter, the "light in a specific wavelength range" corresponds to G light.

[0084] FIG. 11 is an enlarged perspective view simply showing another example of the laminated structure of the image sensor 1 (particularly one pixel region (G pixel region)) including the multilayer structure 23 according to the first embodiment.

[0085] As described above, in the multilayer structure 23, the other filter layer 22 included together with the color filter (wavelength selection filter layer) 21 may contain, for example, silicon oxide.

[0086] In the image sensor 1 shown in FIG. 11, the multilayer structure 23 is provided only in the G filter region (G pixel) among the plurality of filter regions, and the other filter layers 22 of the multilayer structure 23 are made of inorganic material, such as SiO ２ SiO containing ２ A planar membrane is provided.

[0087] Of the multiple filter regions, the R filter region (R pixel) and the B filter region (B pixel) are not provided with the multilayer structure 23, and instead have color filters 21 (R color filter and B color filter) provided as the optical filter section 20.

[0088] The image sensor 1 of this example shown in Fig. 11 can also exhibit light transmission characteristics and reflection characteristics similar to those of the image sensors 1 of the examples shown in Fig. 8 to Fig. 10. That is, in the filter region including the multilayer structure 23, the optical filter section 20 can have high transmittance TF and low reflectance RF for light in a desired wavelength range, and low transmittance TF and high reflectance RF for light outside the desired wavelength range.

[0089] As described above, the optical filter section 20 of this embodiment has the multilayer structure 23 including the color filter 21 and the other filter layer 22. Therefore, light in a desired wavelength range is selected not only by the dispersion by the color filter 21 but also by the Fabry-Perot interference by the multilayer structure 23.

[0090] In particular, light outside the desired wavelength range is absorbed by the color filter 21 and reflected based on the Fabry-Perot interference of the multilayer structure 23. In this way, the absorption by the color filter 21 and the Fabry-Perot interference by the multilayer structure 23 act synergistically on light outside the desired wavelength range, making it possible to more reliably prevent light outside the desired wavelength range from entering the light-receiving pixel PX.

[0091] In particular, by reflecting light in a wavelength range close to the desired wavelength range (crosstalk wavelength range) based on the Fabry-Perot interference of the multilayer structure 23, crosstalk can be reduced and the occurrence of color mixing can be effectively suppressed.

[0092] Furthermore, by using the color filter 21 as part of the multilayer structure 23, it is possible to reduce the overall thickness of the optical filter unit 20 (i.e., make it thinner) compared to a conventional optical filter unit configured only with color filters. That is, even if the overall thickness of the optical filter unit 20 is such that color mixing becomes noticeable in a conventional optical filter unit that uses only spectral separation by color filters, the occurrence of color mixing can be sufficiently suppressed in the optical filter unit 20 that includes the above-described multilayer structure 23.

[0093] In this way, by reducing the height of the optical filter section 20 using the multilayer structure 23, it is possible to reduce the incidence of incident light L on the inter-pixel separation wall (see Figures 5 and 6 above), thereby suppressing a decrease in pixel sensitivity and an increase in color mixing.

[0094] Furthermore, the wavelength range of light that is affected by the Fabry-Perot interference of the multilayer structure 23 varies depending on the film thickness (thickness in the stacking direction) of the multiple layers 21 and 22 that make up the multilayer structure 23. Therefore, by adjusting the film thicknesses of the multiple layers 21 and 22 that make up the multilayer structure 23, the light transmission characteristics and reflection characteristics of the multilayer structure 23 can be flexibly and easily controlled.

[0095] Second Embodiment In this embodiment, elements that are the same as or correspond to those in the first embodiment described above are denoted by the same reference numerals, and detailed description thereof will be omitted.

[0096] Fig. 12 is an enlarged perspective view showing, in a simplified manner, an example of the stacked structure of the image sensor 1 (particularly, one pixel region (G pixel region)) including the multilayer structure 23 according to the second embodiment. Fig. 13 shows an example of an XY cross section perpendicular to the stacking direction of another filter layer 22 (particularly, unit filter region FR0) shown in Fig. 12.

[0097] In the multilayer structure 23, at least one other filter layer 22 may have a regularly arranged first refractive index member 31 and a second refractive index member 32 having a refractive index different from that of the first refractive index member 31.

[0098] The first refractive index member 31 is a member (e.g., an inorganic material member) different from the member contained in the color filter 21 (wavelength selection filter layer), and has a higher refractive index than the second refractive index member 32. The second refractive index member 32 is the same member (e.g., an organic material member) as the member contained in the color filter 21 (wavelength selection filter layer), and has a lower refractive index than the first refractive index member 31.

[0099] The image sensor 1 of this embodiment is configured as a polarization image sensor, and each filter region (optical filter portion 20) including the multilayer structure 23 selectively transmits polarized light vibrating in a desired direction.

[0100] 12 and 13 , first refractive index members 31 made of an inorganic material are arranged in a periodic planar pattern (XY planar pattern), and second refractive index members 32 made of a color filter material are filled around the first refractive index members 31. The periodic planar pattern of the first refractive index members 31 is a pattern optimized for each filter region according to the characteristics (vibration direction) of transmitted light in each filter region.

[0101] The optical filter section 20 of this example includes a plurality of unit filter regions FR0, which are arranged two-dimensionally in the X and Y directions.

[0102] Each unit filter region FR0 includes four filter regions FR1, FR2, FR3, and FR4, and the four filter regions FR1, FR2, FR3, and FR4 are arranged in a 2×2 matrix in the X and Y directions. A "one pixel region" includes one corresponding filter region of the optical filter unit 20 (i.e., any of the four filter regions FR1, FR2, FR3, and FR4).

[0103] The first filter region FR1 selectively transmits a first polarized light vibrating in a first vibration direction (the horizontal direction in FIG. 13).

[0104] The second filter region FR2 selectively transmits second polarized light vibrating in a second vibration direction (the up-and-down direction in FIG. 13) that forms an angle of 90° with the first vibration direction.

[0105] The third filter region FR3 selectively transmits third polarized light vibrating in a third vibration direction (upper right-lower left direction in FIG. 13) that forms an angle of 45° with the first and second vibration directions.

[0106] The fourth filter region FR4 selectively transmits the fourth polarized light vibrating in a fourth vibration direction (upper left-lower right direction in Figure 13) that is 45° with the first vibration direction and the second vibration direction and 90° with the third vibration direction.

[0107] In each of these four types of filter regions FR1, FR2, FR3, and FR4, the vibration direction of the polarized light to be transmitted is a direction that forms an angle of 90° with the extension direction of each first refractive index member 31 and is a direction that coincides with the arrangement direction (spacing direction) of the multiple first refractive index members 31.

[0108] Therefore, the first filter region FR1 is provided with a plurality of first refractive index members 31 extending in a direction perpendicular to the first vibration direction (the up-down direction in FIG. 13 ). The second filter region FR2 is provided with a plurality of first refractive index members 31 extending in a direction perpendicular to the second vibration direction (the horizontal direction in FIG. 13 ). The third filter region FR3 is provided with a plurality of first refractive index members 31 extending in a direction perpendicular to the third vibration direction (the upper left-to-lower right direction in FIG. 13 ). The fourth filter region FR4 is provided with a plurality of first refractive index members 31 extending in a direction perpendicular to the fourth vibration direction (the upper right-to-lower left direction in FIG. 13 ).

[0109] In this way, each unit filter region FR0 includes four types of filter regions FR1, FR2, FR3, and FR4 having periodic patterns in four directions, and can transmit each of the four types of polarized light vibrating in the four directions through the filter regions FR1, FR2, FR3, and FR4.

[0110] The image sensor 1 of this embodiment includes four types of pixel regions according to the type of transmitted polarization (i.e., the types of filter regions FR1, FR2, FR3, FR4), and selectively receives four types of polarization (first to fourth polarization) in the incident light L.

[0111] As described above, the multilayer structure 23 of this embodiment has a pattern structure of the constituent layers 21 and 22 in the stacking direction (Z direction) as well as a pattern structure of the first refractive index member 31 and the second refractive index member 32 in the planar direction (XY direction).

[0112] This makes it possible to reduce the height of the optical filter section 20 and prevent color mixing based on the dispersion by the color filter 21 and the Fabry-Perot interference by the multilayer structure 23, while also making it possible to properly obtain polarization information of the incident light L.

[0113] [Third Embodiment] In this embodiment, elements that are the same as or correspond to those in the first and second embodiments described above are denoted by the same reference numerals, and detailed description thereof will be omitted.

[0114] Fig. 14 shows an example of an XY cross section of another filter layer 22 included in the multilayer structure 23 of the optical filter section 20 according to the third embodiment. Fig. 15 is an enlarged perspective view simply showing an example of the multilayer structure 23 (optical filter section 20) including the other filter layer 22 shown in Fig. 14 and the on-chip lens 15, and shows an example of the relationship between incident light L0 and outgoing light L1.

[0115] In the multilayer structure 23 of this embodiment, as in the second embodiment described above, at least one other filter layer 22 has a regularly arranged first refractive index member 31 and a second refractive index member 32 having a refractive index different from that of the first refractive index member 31.

[0116] However, in this embodiment, a plurality of columnar structures (meta-atoms 40) including the first refractive index members 31 are regularly arranged in each filter region FR.

[0117] In particular, in each filter region FR, the size (e.g., diameter) of the cross section (XY cross section) of the multiple structures of the first refractive index member 31 in a direction perpendicular to the stacking direction (Z direction) gradually changes based on the direction perpendicular to the stacking direction.

[0118] Another example filter layer 22 shown in Figure 14 has a so-called metasurface structure including a large number of columnar structures (metaatoms 40), in which a regular pattern of a first refractive index member 31 with a relatively high refractive index is embedded in a second refractive index member 32 with a relatively low refractive index.

[0119] The XY cross section of each columnar structure (each meta-atom 40) of the first refractive index member 31 has a rectangular (square) shape in FIG. 14, but may have any other shape (e.g., a circular shape), and the distribution pattern of the multiple columnar structures (meta-atoms 40) is not limited to the example shown in FIG. 14.

[0120] By adjusting the distribution pattern of the first refractive index member 31 and the density of the first refractive index member 31 relative to the second refractive index member 32 for each filter region FR, it is possible to optimize the optical function based on the metasurface structure of the other filter layer 22 for each filter region FR.

[0121] Specifically, the other filter layer 22 in this example exhibits an optical path adjustment function based on a metasurface structure.

[0122] That is, as shown in Figure 15, each of the other filter layers 22 in the multilayer structure 23 adjusts the optical path so that the traveling direction of the incident light L0 is closer to the optical axis direction (Z direction), and emits the output light L1 at an output angle closer to "0°".

[0123] For example, the distribution of the first refractive index member 31 in each filter region FR may be adjusted based on the image height in the image sensor 1. In this case, the effective refractive index of the optical filter unit 20 (particularly the other filter layers 22 in the multilayer structure 23) has a distribution in the X and Y directions, and can be set to an optimal effective refractive index value depending on the position in the X and Y directions.

[0124] For example, even if the angle of incidence of incident light L0 on the image sensor 1 changes depending on the image height, it is possible to make the outgoing light L1 incident on each light-receiving pixel PX perpendicular or at an angle close to perpendicular, regardless of the image height, thereby effectively reducing the decrease in pixel sensitivity and the occurrence of color mixing.

[0125] The other filter layer 22 may perform an optical function other than the optical path adjustment function based on the metasurface structure. For example, the other filter layer 22 may perform an optical function based on the metasurface structure, such as a spectroscopic function of separating multiple types of light having different wavelength ranges and emitting the light in different directions, or an optical function of separating multiple types of polarized light having different vibration directions and emitting the light in different directions.

[0126] It should be noted that the embodiments and modifications disclosed in this specification are merely illustrative in all respects and should not be construed as limiting. The above-described embodiments and modifications may be omitted, substituted, and modified in various ways without departing from the scope and spirit of the appended claims. For example, the above-described embodiments and modifications may be combined in whole or in part, and embodiments other than those described above may be combined with the above-described embodiments or modifications. Furthermore, the effects of the present disclosure described in this specification are merely illustrative, and other effects may be obtained.

[0127] The technical category embodying the above technical idea is not limited. For example, the above technical idea may be embodied by a computer program that causes a computer to execute one or more procedures (steps) included in a method of manufacturing or using the above device. The above technical idea may also be embodied by a computer-readable non-transitory recording medium on which such a computer program is recorded.

[0128] [Additional Notes] The disclosed technology may also have the following configurations.

[0129] [Item 1] A photodetector comprising: a photoelectric conversion unit having a plurality of photoelectric conversion elements; and an optical filter unit provided to cover the plurality of photoelectric conversion elements and having a plurality of filter regions corresponding to each of the plurality of photoelectric conversion elements, wherein at least some of the plurality of filter regions have a multilayer structure in which wavelength-selective filter layers that selectively transmit light in a specific wavelength range and other filter layers that have a refractive index different from that of the wavelength-selective filter layers are alternately arranged in a stacking direction.

[0130] [Item 2] The photodetector according to Item 1, wherein the wavelength-selective filter layer is a color filter that transmits light in the specific wavelength range in a visible light wavelength range.

[0131] [Item 3] The photodetector according to item 1 or 2, wherein the multilayer structure has layers containing an organic material and layers containing an inorganic material alternately arranged in the stacking direction, and the wavelength-selective filter layer is composed of the layer containing the organic material.

[0132] [Item 4] The photodetector according to any one of Items 1 to 3, wherein in the multilayer structure, the transmission wavelength ranges due to Fabry-Perot interference of the wavelength selection filter layer and the other filter layer correspond to at least a part of the specific wavelength range of light selectively transmitted by the wavelength selection filter layer.

[0133] [Item 5] The photodetector according to any one of Items 1 to 4, wherein the multilayer structure includes a plurality of the wavelength-selective filter layers.

[0134] [Item 6] The photodetector device according to any one of Items 1 to 5, wherein the other filter layer includes a metal oxide or a silicon oxide.

[0135] [Item 7] The light detection device according to Item 6, wherein the metal oxide is any one of titanium oxide, tantalum oxide, hafnium oxide, and aluminum oxide.

[0136] [Item 8] The photodetector according to any one of Items 1 to 7, wherein at least one of the other filter layers has a first refractive index member that is regularly arranged and a second refractive index member that has a refractive index different from that of the first refractive index member.

[0137] [Item 9] The photodetector according to Item 8, wherein the first refractive index member is different from a member included in the wavelength selection filter layer.

[0138] [Item 10] The photodetector according to Item 8 or 9, wherein the second refractive index member is the same as a member included in the wavelength selection filter layer.

[0139] [Item 11] The optical detection device according to any one of Items 8 to 10, wherein the optical filter section includes a plurality of unit filter regions, each of which includes: a first filter region that selectively transmits first polarized light vibrating in a first vibration direction; a second filter region that selectively transmits second polarized light vibrating in a second vibration direction that forms an angle of 90° with the first vibration direction; a third filter region that selectively transmits third polarized light vibrating in a third vibration direction that forms an angle of 45° with the first vibration direction and the second vibration direction; and a fourth filter region that selectively transmits fourth polarized light vibrating in a fourth vibration direction that forms an angle of 45° with the first vibration direction and the second vibration direction and forms an angle of 90° with the third vibration direction.

[0140] [Item 12] The photodetector according to Item 11, wherein the first filter region includes a plurality of first refractive index members extending in a direction perpendicular to the first vibration direction, the second filter region includes a plurality of first refractive index members extending in a direction perpendicular to the second vibration direction, the third filter region includes a plurality of first refractive index members extending in a direction perpendicular to the third vibration direction, and the fourth filter region includes a plurality of first refractive index members extending in a direction perpendicular to the fourth vibration direction.

[0141] [Item 13] The photodetector according to any one of Items 8 to 12, wherein a plurality of columnar structures including the first refractive index member are regularly arranged in each filter region.

[0142] [Item 14] The photodetector according to Item 13, wherein in each filter region, the cross-sectional size of the plurality of structures in a direction perpendicular to the stacking direction gradually changes based on the direction perpendicular to the stacking direction.

[0143] REFERENCE SIGNS LIST 1 Image sensor 10 Light transmission control section 11 Photoelectric conversion section 15 On-chip lens 16 Light-shielding film 17 Semiconductor oxide film 20 Optical filter section 21 Color filter 22 Other filter layer 23 Multilayer structure 31 First refractive index member 32 Second refractive index member 40 Meta-atom FR Filter region FR0 Unit filter region FR1 First filter region FR2 Second filter region FR3 Third filter region FR4 Fourth filter region L Incident light L0 Incident light L1 Emitted light La Frontal incident light Lb Oblique incident light OP Optical system PX Light-receiving pixel RF Reflectance TF Transmittance t Film thickness

Claims

1. A photodetector comprising: a photoelectric conversion section having a plurality of photoelectric conversion elements; and an optical filter section provided to cover the plurality of photoelectric conversion elements and having a plurality of filter regions corresponding to each of the plurality of photoelectric conversion elements, wherein at least a portion of the plurality of filter regions have a multilayer structure in which a wavelength selection filter layer that selectively transmits light in a specific wavelength range and another filter layer having a refractive index different from that of the wavelength selection filter layer are alternately arranged in the stacking direction.

2. The photodetector according to claim 1, wherein the wavelength-selective filter layer is a color filter that transmits light in the specific wavelength range in the visible light wavelength range.

3. The optical detection device according to claim 1, wherein the multilayer structure has layers containing an organic material and layers containing an inorganic material arranged alternately in the stacking direction, and the wavelength selection filter layer is composed of the layer containing the organic material.

4. The optical detection device according to claim 1, wherein in said multilayer structure, the transmission wavelength range due to Fabry-Perot interference of said wavelength selection filter layer and said other filter layers corresponds to at least a part of said specific wavelength range of light selectively transmitted by said wavelength selection filter layer.

5. The optical detection device according to claim 1, wherein the multi-layer structure includes a plurality of the wavelength selection filter layers.

6. The optical detection device according to claim 1, wherein the other filter layer comprises a metal oxide or a silicon oxide.

7. The optical detection device according to claim 6, wherein the metal oxide is any one of titanium oxide, tantalum oxide, hafnium oxide and aluminum oxide.

8. The optical detection device according to claim 1, wherein at least one of the other filter layers has a first refractive index member arranged regularly and a second refractive index member having a refractive index different from that of the first refractive index member.

9. The optical detection device according to claim 8, wherein the first refractive index member is different from a member contained in the wavelength selection filter layer.

10. The optical detection device according to claim 8, wherein the second refractive index member is the same as a member contained in the wavelength selection filter layer.

11. The optical detection device of claim 8, wherein the optical filter section includes a plurality of unit filter regions, each of which includes: a first filter region selectively transmitting a first polarized light vibrating in a first vibration direction; a second filter region selectively transmitting a second polarized light vibrating in a second vibration direction that forms an angle of 90° with the first vibration direction; a third filter region selectively transmitting a third polarized light vibrating in a third vibration direction that forms an angle of 45° with the first vibration direction and the second vibration direction; and a fourth filter region selectively transmitting a fourth polarized light vibrating in a fourth vibration direction that forms an angle of 45° with the first vibration direction and the second vibration direction and forms an angle of 90° with the third vibration direction.

12. The optical detection device of claim 11, wherein the first filter region is provided with a plurality of the first refractive index members extending in a direction perpendicular to the first vibration direction, the second filter region is provided with a plurality of the first refractive index members extending in a direction perpendicular to the second vibration direction, the third filter region is provided with a plurality of the first refractive index members extending in a direction perpendicular to the third vibration direction, and the fourth filter region is provided with a plurality of the first refractive index members extending in a direction perpendicular to the fourth vibration direction.

13. The light detection device according to claim 8, wherein a plurality of columnar structures including the first refractive index member are regularly arranged in each filter region.

14. The light detection device according to claim 13, wherein in each filter region, the size of the cross section of the plurality of structures in a direction perpendicular to the stacking direction gradually changes with reference to the direction perpendicular to the stacking direction.

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