Imaging element, manufacturing method, and electronic device

Abstract

The present disclosure relates to an imaging element, a manufacturing method, and an electronic device that can further improve reliability. This imaging element includes: a semiconductor substrate on which a photodiode is provided for each pixel; a wiring layer stacked on the semiconductor substrate and having one or more metal wiring layers; and an absorption layer that is provided on the wiring layer so as to shield the metal wiring layer(s) from light and that absorbs laser light. The imaging element is a back-illuminated imaging element, and the absorption layer is disposed closer to the semiconductor substrate side than the first metal wiring layer, from the semiconductor substrate side, provided in the wiring layer. This feature can be applied to, for example, CMOS image sensors.

Description

Image sensor, manufacturing method, and electronic device

[0001] The present disclosure relates to an image sensor, a manufacturing method, and an electronic device, and particularly to an image sensor, a manufacturing method, and an electronic device that can improve reliability more effectively.

[0002] In recent years, LiDAR (Light Detection And Ranging), which irradiates laser light to detect a target object and measure distance, has become widespread. Along with this, the chance of laser light irradiated from LiDAR entering a CMOS (Complementary Metal Oxide Semiconductor) image sensor has increased, raising concerns that the CMOS image sensor may be damaged by the laser light.

[0003] Patent Document 1 discloses a solid-state image sensor having a structure in which a waveguide for introducing light into a photoelectric conversion unit uses a material with a high refractive index, such as germanium.

[0004] Japanese Patent Application Laid-Open No. 2021-86844

[0005] For example, when high-power laser light in the SWIR (Short-Wavelength InfraRed) wavelength band irradiates the Cu wiring layer of a CMOS image sensor, migration occurs in the Cu wiring layer and polysilicon electrodes alloy due to the overcurrent generated by the laser light. As a result, for example, point defects or line defects occur in the CMOS image sensor, making it impossible to perform normal imaging and reducing reliability.

[0006] The present disclosure has been made in view of such circumstances and aims to improve reliability more effectively.

[0007] An image sensor according to one aspect of the present disclosure includes a semiconductor substrate provided with a photodiode for each pixel, a wiring layer laminated on the semiconductor substrate and provided with one or more metal wiring layers, and an absorption layer provided in the wiring layer so as to shield the metal wiring layer and absorb laser light.

[0008] One aspect of the manufacturing method of this disclosure includes stacking a wiring layer on a semiconductor substrate on which a photodiode is provided for each pixel, with one or more metal wiring layers provided on the wiring layer, and providing an absorption layer that absorbs laser light so as to shield the metal wiring layer from light.

[0009] An electronic device according to one aspect of the present disclosure includes an image sensor having a semiconductor substrate on which a photodiode is provided for each pixel, a wiring layer laminated on the semiconductor substrate and having one or more metal wiring layers, and an absorption layer provided on the wiring layer so as to shield the metal wiring layer from light and absorbing laser light.

[0010] In one aspect of this disclosure, a wiring layer is stacked on a semiconductor substrate on which a photodiode is provided for each pixel, and one or more metal wiring layers are provided on the wiring layer, and an absorption layer that absorbs laser light is provided on the wiring layer so as to shield the metal wiring layer from light.

[0011] This is a cross-sectional view showing an example configuration of a first embodiment of an image sensor to which this technology is applied. This is a diagram illustrating the manufacturing method of the image sensor of Figure 1. This is a diagram illustrating the manufacturing method of the image sensor of Figure 1. This is a cross-sectional view showing an example configuration of a second embodiment of an image sensor to which this technology is applied. This is a cross-sectional view showing an example configuration of a third embodiment of an image sensor to which this technology is applied. This is a cross-sectional view showing an example configuration of a fourth embodiment of an image sensor to which this technology is applied. This is a diagram illustrating the manufacturing method of the image sensor of Figure 6. This is a diagram illustrating the manufacturing method of the image sensor of Figure 6. This is a cross-sectional view showing an example configuration of a fifth embodiment of an image sensor to which this technology is applied. This is a cross-sectional view showing an example configuration of a sixth embodiment of an image sensor to which this technology is applied. This is a diagram showing an example of a planar layout of a germanium layer. This is a block diagram showing an example configuration of an imaging device. This is a diagram showing an example of use using an image sensor. This is a block diagram showing an example of a schematic configuration of a vehicle control system. This is an explanatory diagram showing an example of the installation position of the external information detection unit and the imaging unit.

[0012] The following describes in detail a specific embodiment of this technology, with reference to the drawings.

[0013] <First Configuration Example of Image Sensor> Figure 1 is a cross-sectional view showing a configuration example of a first embodiment of an image sensor to which this technology is applied.

[0014] The image sensor 11 shown in Figure 1 is composed of multiple pixels 12 arranged in an array. Figure 1 shows the cross-sectional configuration of a pixel 12R that receives red light, a pixel 12G that receives green light, and a pixel 12B that receives blue light. When there is no need to distinguish between them, they are simply referred to as pixels 12.

[0015] As shown in the figure, the image sensor 11 is constructed by sequentially stacking a planarization layer 22, a color filter layer 23, and an on-chip lens layer 24 on the back surface of the semiconductor substrate 21, and stacking a wiring layer 25 on the front surface of the semiconductor substrate 21.

[0016] A photodiode is provided for each pixel 12 on the semiconductor substrate 21, and light is shone from the back side of the semiconductor substrate 21 (the upper side in Figure 1).

[0017] The planarization layer 22 is composed of a light-shielding film 31 provided to shield the space between adjacent pixels 12, and an insulating film 32 provided to cover the semiconductor substrate 21 and the light-shielding film 31 and to planarize the surface.

[0018] The color filter layer 23 is configured such that each pixel 12 is provided with a plurality of filters 33 that transmit light of the color received by that pixel 12 (in the illustrated example, a filter 33R that transmits red light, a filter 33G that transmits green light, and a filter 33B that transmits blue light).

[0019] The on-chip lens layer 24 is configured such that each pixel 12 is provided with a plurality of lenses 34 that focus the light received by each pixel 12 (in the illustrated example, lens 34R that focuses the light received by pixel 12R, lens 34G that focuses the light received by pixel 12G, and lens 34B that focuses the light received by pixel 12B).

[0020] The wiring layer 25 is constructed by providing a plurality of polysilicon electrodes 42, a plurality of metal wiring layers 43, a plurality of through electrodes 44, and a germanium layer 45, which are insulated from each other by an insulating film 41.

[0021] The polysilicon electrodes 42 are used as gate electrodes for transistors that drive the pixels 12 (for example, transfer transistors, amplification transistors, reset transistors, etc.) and are arranged via a thin insulating film 41 deposited on the surface of the semiconductor substrate 21. In the example shown in Figure 1, three polysilicon electrodes 42-1 to 42-3 are illustrated.

[0022] The metal wiring layers 43 are constructed by forming a metal wiring pattern on each layer. In the example shown in Figure 1, the first metal wiring layer 43-1 and the second metal wiring layer 43-2 from the semiconductor substrate 21 are shown. Of course, the configuration may include three or more metal wiring layers 43.

[0023] The through electrodes 44a are provided to connect the semiconductor substrate 21 and the metal wiring layer 43-1, and in the example shown in Figure 1, three through electrodes 44a-1 to 44a-3 are shown. The through electrodes 44b are provided to connect the polysilicon electrode 42 and the metal wiring layer 43-1, and in the example shown in Figure 1, three through electrodes 44b-1, 44b-2, and 44b-3 are shown, connected to the polysilicon electrode 42-1, 44b-2, and 44b-3, connected to the polysilicon electrode 42-3. The through electrodes 44c are provided to connect the metal wiring layer 43-1 and the metal wiring layer 43-2, and in the example shown in Figure 1, three through electrodes 44c-1 to 44c-3 are shown.

[0024] The germanium layer 45 is provided on the semiconductor substrate 21 side of the metal wiring layer 43-1 so as to shield the metal wiring layer 43-1 from light, and is used as an absorption layer to absorb laser light irradiated from a high-power laser diode used in LiDAR, for example. That is, because germanium has a smaller band gap (Eg) than silicon, it has a high absorption coefficient in the infrared band used in LiDAR, and can attenuate laser light.

[0025] Furthermore, the germanium layer 45 has multiple openings formed therein for passing through electrodes 44a-1 to 44a-3 and 44b-1 to 44b-3, and these openings are formed to a size that allows them to be insulated from the through electrodes 44a-1 to 44a-3 and 44b-1 to 44b-3 by the insulating film 41.

[0026] As described above, the image sensor 11 is configured such that, for example, even if laser light emitted from a LiDAR or the like is incident on the image sensor 11, the germanium layer 45 absorbs the laser light, thereby suppressing (shielding) the irradiation of the metal wiring layer 43 with laser light. Therefore, the image sensor 11 can avoid the generation of overcurrent in the metal wiring layer 43 due to laser light, and can perform imaging normally without the occurrence of point defects or line defects, for example. As a result, the reliability of the image sensor 11 can be improved.

[0027] Furthermore, the image sensor 11 can also suppress optical crosstalk caused by light reflected in the metal wiring layer 43.

[0028] A method for manufacturing the image sensor 11 will be described with reference to Figures 2 and 3.

[0029] In the first step, polysilicon electrodes 42-1 to 42-3 are formed on the surface of the semiconductor substrate 21 via a thin insulating film 41, and the insulating film 41 is deposited so as to flatten the surface, as shown in the first step of Figure 2, until the thickness of the germanium layer 45 is formed.

[0030] In the second step, for example, a germanium layer 45 is laminated by a CVD (Chemical Vapor Deposition) process so as to cover the entire surface of the insulating film 41, as shown in the second step of Figure 2.

[0031] In the third step, as shown in the third row of Figure 2, multiple openings are formed in the germanium layer 45. The openings in the germanium layer 45 are formed to be larger in size than the through electrodes 44a-1 to 44a-3 and 44b-1 to 44b-3, corresponding to the locations where the through electrodes 44a-1 to 44a-3 and 44b-1 to 44b-3 are provided.

[0032] In the fourth step, as shown in the fourth row of Figure 2, the openings in the germanium layer 45 formed in the third step are filled, and an insulating film 41 is deposited until it reaches a thickness sufficient for the metal wiring layer 43-1 to be formed.

[0033] In the fifth step, as shown in the first step of Figure 3, contact holes are formed in multiple locations in the insulating film 41 so as to pass through multiple openings formed in multiple locations in the germanium layer 45. The contact holes in the insulating film 41 are formed to penetrate to the semiconductor substrate 21 in the locations where through electrodes 44a-1 to 44a-3 are provided, and are formed to penetrate to the polysilicon electrodes 42-1 to 42-3 in the locations where through electrodes 44b-1 to 44b-3 are provided.

[0034] In the fifth step, as shown in the second row of Figure 3, through electrodes 44a-1 to 44a-3 and through electrodes 44b-1 to 44b-3 are formed by embedding a metal material into the through holes formed in the fourth step.

[0035] In the sixth step, a metal wiring layer 43-1, through electrodes 44c-1 to 44c-3, and metal wiring layer 43-2 are formed, and an insulating film 41 is deposited to a predetermined thickness, thereby forming a wiring layer 25 as shown in the third step of Figure 3.

[0036] Subsequently, an image sensor 11 as shown in Figure 1 is manufactured by sequentially stacking a planarization layer 22, a color filter layer 23, and an on-chip lens layer 24 on the back surface of the semiconductor substrate 21.

[0037] Through the above process, an image sensor 11 can be manufactured in which a germanium layer 45 is provided so as to shield the metal wiring layer 43-1 from light.

[0038] <Second Example of Image Sensor Configuration> Figure 4 is a cross-sectional view showing an example of the configuration of a second embodiment of an image sensor to which this technology is applied. In the image sensor 11A shown in Figure 4, components common to the image sensor 11 shown in Figure 1 are denoted by the same reference numerals, and their detailed explanations are omitted.

[0039] As shown in Figure 4, the image sensor 11A has the same configuration as the image sensor 11 in Figure 1, in that a planarization layer 22, a color filter layer 23, and an on-chip lens layer 24 are sequentially stacked on the back surface of the semiconductor substrate 21. However, the image sensor 11A differs from the image sensor 11 in that a wiring layer 25A is stacked on the front surface of the semiconductor substrate 21.

[0040] The wiring layer 25A has the same configuration as the wiring layer 25 in Figure 1, in that it is provided with a plurality of polysilicon electrodes 42, a plurality of metal wiring layers 43, and a plurality of through electrodes 44, which are insulated from each other by an insulating film 41. However, the wiring layer 25A has a different configuration from the wiring layer 25 in Figure 1, in that it is provided with a plurality of germanium layers 45.

[0041] As shown in the figure, in the image sensor 11A, a germanium layer 45-1 is provided on the semiconductor substrate 21 side of the metal wiring layer 43-1, and a germanium layer 45-2 is provided between the metal wiring layer 43-1 and the metal wiring layer 43-2 to form the wiring layer 25A. Similar to the germanium layer 45 in Figure 1, the germanium layer 45-1 has multiple openings for passing through electrodes 44a-1 to 44a-3 and through electrodes 44b-1 to 44b-3. The germanium layer 45-2 has multiple openings for passing through electrodes 44c-1 to 44c-3.

[0042] As described above, the image sensor 11A is configured to suppress the irradiation of the metal wiring layer 43-1 and metal wiring layer 43-2 by laser light emitted from a LiDAR or the like, similar to the image sensor 11 in Figure 1. Furthermore, by providing multiple germanium layers 45, the image sensor 11A can improve its effect of absorbing laser light. As a result, the reliability of the image sensor 11A can be further improved.

[0043] <Third Configuration Example of Image Sensor>FIG. 5 is a cross-sectional view showing a configuration example of a third embodiment of an image sensor to which the present technology is applied. In the image sensor 11B shown in FIG. 5, the same reference numerals are given to the configurations common to the image sensor 11 shown in FIG. 1, and detailed descriptions thereof are omitted.

[0044] As shown in FIG. 5, the image sensor 11B has the same configuration as the image sensor 11 in FIG. 1 in that a planarization layer 22, a color filter layer 23, and an on-chip lens layer 24 are sequentially laminated on the back surface of the semiconductor substrate 21. The image sensor 11B has a different configuration from the image sensor 11 in FIG. 1 in that a wiring layer 25B is laminated on the front surface of the semiconductor substrate 21.

[0045] The wiring layer 25B has the same configuration as the wiring layer 25 in FIG. 1 in that a plurality of polysilicon electrodes 42, a plurality of metal wiring layers 43, a plurality of through electrodes 44, and a germanium layer 45 are provided so as to be insulated from each other by an insulating film 41. The wiring layer 25A has a different configuration from the wiring layer 25 in FIG. 1 in that a through electrode 44B for fixing the potential of the germanium layer 45 is provided.

[0046] As shown in the figure, the through electrode 44B is provided so as to connect the metal wiring layer 43-1 (a wiring for supplying a predetermined potential in the metal wiring layer 43-1) and the germanium layer 45. Therefore, the germanium layer 45 is fixed at a predetermined potential through the through electrode 44B.

[0047] The image sensor 11B is configured as described above. Similarly to the image sensor 11 in FIG. 1, it is possible to suppress the laser light irradiated from LiDAR or the like from irradiating the metal wiring layer 43. Further, the image sensor 11B can take measures to prevent an excessive current density from occurring by fixing the potential of the germanium layer 45, and further improve the reliability.

[0048] <Fourth Configuration Example of Image Sensor>FIG. 6 is a cross-sectional view showing a configuration example of a fourth embodiment of an image sensor to which the present technology is applied. In the image sensor 11C shown in FIG. 6, the same reference numerals are given to the configurations common to the image sensor 11 shown in FIG. 1, and the detailed description thereof is omitted.

[0049] As shown in FIG. 6, the image sensor 11C is configured by laminating a wiring layer 25C, a color filter layer 23, and an on-chip lens layer 24 in this order on the surface of a semiconductor substrate 21C. The color filter layer 23 and the on-chip lens layer 24 are configured in the same manner as in FIG. 1.

[0050] That is, the image sensor 11 in FIG. 1 is a back-illuminated type in which light is irradiated onto the back surface of the semiconductor substrate 21, whereas the image sensor 11C is a front-illuminated type in which light is irradiated onto the surface of the semiconductor substrate 21C.

[0051] The semiconductor substrate 21C is provided with a photodiode for each pixel 12, and light is irradiated from the surface side (the upper side in FIG. 6) of the semiconductor substrate 21C.

[0052] The wiring layer 25C has the same configuration as the wiring layer 25 in FIG. 1 in that a plurality of polysilicon electrodes 42, a plurality of metal wiring layers 43, and a plurality of through electrodes 44 are provided so as to be insulated from each other by an insulating film 41. The wiring layer 25C has a different configuration from the wiring layer 25 in FIG. 1 in that the planar layout of the germanium layer 45C is different from the planar layout of the germanium layer 45 in FIG. 1.

[0053] As shown in the drawing, in the image sensor 11C, a germanium layer 45C-1 is provided between the color filter layer 23 and the metal wiring layer 43-2, and a germanium layer 45C-2 is provided between the metal wiring layer 43-2 and the metal wiring layer 43-1 to form the wiring layer 25C. That is, the germanium layer 45C-1 is disposed between the uppermost metal wiring layer 43 (in the illustrated example, the metal wiring layer 43-2) provided in the wiring layer 25C and the on-chip lens layer 24.

[0054] The germanium layer 45C-1 is arranged in a planar layout such that it blocks light from the metal wiring layer 43-2 when viewed from the light incident surface side where light is incident on the image sensor 11.

[0055] The germanium layer 45C-2 is provided in a planar layout such that, when viewed from the light incident surface side where light is incident on the image sensor 11, it blocks at least the metal wiring layer 43-1 that is not blocked by the germanium layer 45C-1. Alternatively, the germanium layer 45C-2 may be provided in a planar layout such that it overlaps with the germanium layer 45C-1 and blocks the metal wiring layer 43-1.

[0056] As described above, the image sensor 11C is configured in the same way as the image sensor 11 in Figure 1, and reliability can be further improved by suppressing the irradiation of the metal wiring layer 43 by laser light emitted from LiDAR or the like.

[0057] The manufacturing method of the image sensor 11C will be described with reference to Figures 7 to 9.

[0058] In the 11th step, polysilicon electrodes 42-1 to 42-3 are formed on the surface of the semiconductor substrate 21C via a thin insulating film 41, and the insulating film 41 is deposited so as to flatten the surface, as shown in the first step of Figure 7, until the thickness is sufficient for the metal wiring layer 43-1 to be formed.

[0059] In the 12th step, as shown in the second step of Figure 7, through electrodes 44a-1 and 44a-2, through electrodes 44b-1 to 44b-3, and a metal wiring layer 43-1 are formed, and an insulating film 41 is deposited until it reaches a thickness sufficient for the germanium layer 45C-2 to be formed.

[0060] In the 13th step, for example, a germanium layer 45C-2 is laminated by a CVD process so as to cover the entire surface of the insulating film 41, as shown in the third step of Figure 7.

[0061] In the 14th step, as shown in the first step of Figure 8, the germanium layer 45C-2 is patterned to match the wiring pattern of the metal wiring layer 43-1. At this time, the germanium layer 45C-2 is patterned such that, when viewed from the light incident surface side where light is incident on the image sensor 11, it covers at least the metal wiring layer 43-1 that is not covered by the germanium layer 45C-1. In other words, the metal wiring layer 43-1 that will be covered by the germanium layer 45C-1 provided in a later step does not need to be covered by the germanium layer 45C-2.

[0062] In the 15th step, as shown in the second step of Figure 8, through electrodes 44c-1 and 44c-2 and a metal wiring layer 43-2 are formed, and an insulating film 41 is deposited until it reaches a thickness sufficient for the germanium layer 45C-1 to be formed.

[0063] In the 16th step, for example, a germanium layer 45C-1 is laminated by a CVD process so as to cover the entire surface of the insulating film 41, as shown in the third step of Figure 8.

[0064] In the 17th step, as shown in the first step of Figure 9, the germanium layer 45C-1 is patterned to match the wiring pattern of the metal wiring layer 43-2.

[0065] In the 18th step, as shown in the second step of Figure 9, the wiring layer 25C is formed by depositing an insulating film 41 to a predetermined thickness.

[0066] Subsequently, the image sensor 11C shown in Figure 6 is manufactured by sequentially stacking the color filter layer 23 and the on-chip lens layer 24 on the wiring layer 25C.

[0067] Through the process described above, an image sensor 11C can be manufactured in which a germanium layer 45C-2 is provided so as to shield the metal wiring layer 43-1 from light, and a germanium layer 45C-1 is provided so as to shield the metal wiring layer 43-2 from light.

[0068] <Fifth Configuration Example of Image Sensor> Figure 10 is a cross-sectional view showing a configuration example of a fifth embodiment of an image sensor to which this technology is applied. In the image sensor 11D shown in Figure 10, components common to the image sensor 11 shown in Figure 1 are denoted by the same reference numerals, and their detailed explanations are omitted.

[0069] As shown in Figure 10, the image sensor 11D has the same configuration as the image sensor 11 in Figure 1, in that a planarization layer 22, a color filter layer 23, and an on-chip lens layer 24 are sequentially stacked on the back surface of the semiconductor substrate 21. However, the image sensor 11D differs from the image sensor 11 in that a wiring layer 25D is stacked on the front surface of the semiconductor substrate 21.

[0070] The wiring layer 25D has the same configuration as the wiring layer 25 in Figure 1, in that it is provided with a plurality of polysilicon electrodes 42, a plurality of metal wiring layers 43, and a plurality of through electrodes 44, which are insulated from each other by an insulating film 41. However, the wiring layer 25D has a different configuration from the wiring layer 25 in Figure 1, in that it is provided with an absorption layer 46.

[0071] For example, the absorption layer 46 may be constructed using materials such as silicon germanium (SiGe), quantum dots (Q-dots), or indium gallium arsenide (InGaAs), and, like the germanium layer 45 in Figure 1, can absorb laser light, for example. Of course, the absorption layer 46 may also be constructed using materials other than those mentioned above that can absorb laser light irradiated from a LiDAR or the like.

[0072] As described above, the image sensor 11A is configured such that, similar to the image sensor 11 in Figure 1, reliability can be further improved by suppressing the irradiation of the metal wiring layer 43 by laser light emitted from LiDAR or the like.

[0073] <Sixth Configuration Example of Image Sensor> Figure 11 is a cross-sectional view showing a configuration example of a sixth embodiment of an image sensor to which this technology is applied. In the image sensor 11E shown in Figure 11, components common to the image sensor 11 shown in Figure 1 are denoted by the same reference numerals, and their detailed explanations are omitted.

[0074] As shown in Figure 11, the image sensor 11E has the same configuration as the image sensor 11 in Figure 1, in that a planarization layer 22, a color filter layer 23, and an on-chip lens layer 24 are sequentially stacked on the back surface of the semiconductor substrate 21. However, the image sensor 11E differs from the image sensor 11 in that a wiring layer 25E is stacked on the front surface of the semiconductor substrate 21.

[0075] The wiring layer 25E has the same configuration as the wiring layer 25 in Figure 1, in that it is provided with a plurality of polysilicon electrodes 42, a plurality of metal wiring layers 43, a plurality of through electrodes 44, and a germanium layer 45, which are insulated from each other by an insulating film 41. However, the wiring layer 25E has a different configuration from the wiring layer 25 in Figure 1, in that it is provided with a transistor layer 51.

[0076] As shown in the figure, the transistor layer 51 is provided between the germanium layer 45 and the metal wiring layer 43-1, and is composed of a semiconductor layer 52 and a polysilicon electrode 53 for forming a transistor that drives the pixel 12. The transistor layer 51 is also provided so as to be shielded from light by the germanium layer 45, and the polysilicon electrode 53 of the transistor layer 51 is connected to the metal wiring layer 43-1 via a through electrode 54.

[0077] As described above, the image sensor 11E is configured such that, similar to the image sensor 11 in Figure 1, reliability can be further improved by suppressing the irradiation of the metal wiring layer 43 by laser light emitted from a LiDAR or the like.

[0078] <Example of Planar Layout of Germanium Layer> Figure 12 shows an example of a planar layout of the germanium layer 45 as viewed from the light incident surface side.

[0079] Figure 12A shows an example of a planar layout of a germanium layer 45 provided on a back-illuminated image sensor 11 as shown in Figure 1. As shown in Figure 12A, in a back-illuminated image sensor 11, the germanium layer 45 is provided so as to block light from all areas except where multiple through electrodes 44 are provided.

[0080] Figure 12B shows an example of a planar layout of a germanium layer 45C provided on a surface-illuminated image sensor 11C as shown in Figure 6. As shown in Figure 12B, in a surface-illuminated image sensor 11C, the germanium layer 45C is provided so as to shield the areas where the metal wiring layer 43 (see Figure 6) is provided, that is, directly above the wiring pattern of the metal wiring layer 43.

[0081] <Example of Electronic Device Configuration> The image sensor 11 described above can be applied to various electronic devices such as imaging systems like digital still cameras and digital video cameras, mobile phones equipped with imaging functions, or other devices equipped with imaging functions.

[0082] Figure 13 is a block diagram showing an example configuration of an imaging device mounted on an electronic device.

[0083] As shown in Figure 13, the imaging device 101 is configured to include an optical system 102, an image sensor 103, a signal processing circuit 104, a monitor 105, and a memory 106, and is capable of capturing still images and moving images.

[0084] The optical system 102 is composed of one or more lenses and guides the image light (incident light) from the subject to the image sensor 103, forming an image on the light-receiving surface (sensor part) of the image sensor 103.

[0085] The image sensor 103 is the same as the image sensor 11 described above. Electrons are accumulated in the image sensor 103 for a certain period of time, depending on the image formed on the light-receiving surface via the optical system 102. Then, a signal corresponding to the electrons accumulated in the image sensor 103 is supplied to the signal processing circuit 104.

[0086] The signal processing circuit 104 performs various signal processing operations on the pixel signals output from the image sensor 103. The image (image data) obtained by the signal processing circuit 104 is supplied to the monitor 105 for display or supplied to the memory 106 for storage (recording).

[0087] In the imaging device 101 configured in this way, by applying the image sensor 11 described above, for example, images can be captured more reliably.

[0088] <Examples of Image Sensor Usage> Figure 14 shows an example of using the image sensor (imaging element) described above.

[0089] The image sensor described above can be used in various cases to sense light such as visible light, infrared light, ultraviolet light, and X-rays, for example, as follows.

[0090] - Devices that capture images for viewing purposes, such as digital cameras and portable devices with camera functions. - Devices used for traffic purposes, such as in-vehicle sensors that capture images of the front, rear, surroundings, and interior of a vehicle for safe driving such as automatic stopping and recognition of the driver's condition, surveillance cameras that monitor moving vehicles and roads, and distance measuring sensors that measure distances between vehicles. - Devices used in home appliances such as TVs, refrigerators, and air conditioners that capture user gestures and allow device operation according to those gestures. - Devices used for medical and healthcare purposes, such as endoscopes and devices that perform angiography using infrared light reception. - Devices used for security purposes, such as surveillance cameras for crime prevention and cameras for person recognition. - Devices used for beauty purposes, such as skin measuring devices that capture images of skin and microscopes that capture images of the scalp. - Devices used for sports purposes, such as action cameras and wearable cameras for sports use. - Devices used for agriculture, such as cameras that monitor the condition of fields and crops.

[0091] <Examples of application to mobile devices> The technology disclosed herein (this technology) can be applied to various products. For example, the technology disclosed herein may be implemented as a device mounted on any type of mobile device such as automobiles, electric vehicles, hybrid electric vehicles, motorcycles, bicycles, personal mobility devices, airplanes, drones, ships, and robots.

[0092] Figure 15 is a block diagram showing a schematic configuration example of a vehicle control system, which is an example of a mobile control system to which the technology described herein may be applied.

[0093] The vehicle control system 12000 comprises a plurality of electronic control units connected via a communication network 12001. In the example shown in Figure 15, the vehicle control system 12000 includes a drive system control unit 12010, a body system control unit 12020, an external information detection unit 12030, an internal information detection unit 12040, and an integrated control unit 12050. The functional configuration of the integrated control unit 12050 is shown in the figure, which includes a microcomputer 12051, an audio / image output unit 12052, and an in-vehicle network interface 12053.

[0094] The drivetrain control unit 12010 controls the operation of devices related to the vehicle's drivetrain according to various programs. For example, the drivetrain control unit 12010 functions as a control device for a drivetrain generating device that generates driving force for the vehicle, such as an internal combustion engine or a drive motor; a drivetrain transmission mechanism that transmits driving force to the wheels; a steering mechanism that adjusts the steering angle of the vehicle; and a braking device that generates braking force for the vehicle.

[0095] The body system control unit 12020 controls the operation of various devices mounted on the vehicle body according to various programs. For example, the body system control unit 12020 functions as a control device for a keyless entry system, a smart key system, a power window system, or various lamps such as headlights, reverse lights, brake lights, turn signals, or fog lights. In this case, the body system control unit 12020 may receive radio waves transmitted from a portable device that replaces a key or signals from various switches. The body system control unit 12020 receives these radio waves or signals and controls the vehicle's door lock system, power window system, lamps, etc.

[0096] The external information detection unit 12030 detects information from outside the vehicle equipped with the vehicle control system 12000. For example, an imaging unit 12031 is connected to the external information detection unit 12030. The external information detection unit 12030 causes the imaging unit 12031 to capture images of the outside of the vehicle and receives the captured images. Based on the received images, the external information detection unit 12030 may perform object detection processing such as detecting people, cars, obstacles, signs, or characters on the road surface, or distance detection processing.

[0097] The imaging unit 12031 is a light sensor that receives light and outputs an electrical signal corresponding to the amount of light received. The imaging unit 12031 can output the electrical signal as an image or as distance measurement information. The light received by the imaging unit 12031 may be visible light or invisible light such as infrared light.

[0098] The in-vehicle information detection unit 12040 detects information inside the vehicle. The in-vehicle information detection unit 12040 is connected to, for example, a driver status detection unit 12041 that detects the driver's state. The driver status detection unit 12041 includes, for example, a camera that captures images of the driver, and the in-vehicle information detection unit 12040 may calculate the driver's level of fatigue or concentration, or determine whether the driver is drowsy, based on the detection information input from the driver status detection unit 12041.

[0099] The microcomputer 12051 can calculate control target values ​​for the drive force generator, steering mechanism, or braking device based on information inside and outside the vehicle acquired by the external information detection unit 12030 or the internal information detection unit 12040, and output control commands to the drive system control unit 12010. For example, the microcomputer 12051 can perform cooperative control aimed at realizing ADAS (Advanced Driver Assistance System) functions, including collision avoidance or impact mitigation, following driving based on distance between vehicles, maintaining vehicle speed, vehicle collision warning, or vehicle lane departure warning.

[0100] Furthermore, the microcomputer 12051 can perform cooperative control for purposes such as autonomous driving, where the vehicle drives autonomously without driver intervention, by controlling the drive force generating device, steering mechanism, or braking device, etc., based on information about the vehicle's surroundings acquired by the external information detection unit 12030 or the internal information detection unit 12040.

[0101] Furthermore, the microcomputer 12051 can output control commands to the body system control unit 12020 based on external information acquired by the external information detection unit 12030. For example, the microcomputer 12051 can control the headlights according to the position of a preceding or oncoming vehicle detected by the external information detection unit 12030, and perform coordinated control aimed at reducing glare, such as switching from high beams to low beams.

[0102] The audio-image output unit 12052 transmits at least one of audio and image output signals to an output device capable of visually or audibly notifying information to the vehicle's occupants or to those outside the vehicle. In the example shown in Figure 15, the output devices include an audio speaker 12061, a display unit 12062, and an instrument panel 12063. The display unit 12062 may include, for example, at least one of an onboard display and a head-up display.

[0103] Figure 16 shows an example of the installation position of the imaging unit 12031.

[0104] In Figure 16, the imaging unit 12031 includes imaging units 12101, 12102, 12103, 12104, and 12105.

[0105] The imaging units 12101, 12102, 12103, 12104, and 12105 are installed, for example, on the front nose, side mirrors, rear bumper, back door, and the upper part of the windshield inside the vehicle 12100. The imaging unit 12101 installed on the front nose and the imaging unit 12105 installed on the upper part of the windshield inside the vehicle mainly acquire images of the front of the vehicle 12100. The imaging units 12102 and 12103 installed on the side mirrors mainly acquire images of the sides of the vehicle 12100. The imaging unit 12104 installed on the rear bumper or back door mainly acquires images of the rear of the vehicle 12100. The imaging unit 12105 installed on the upper part of the windshield inside the vehicle is mainly used for detecting preceding vehicles, pedestrians, obstacles, traffic lights, traffic signs, or lanes.

[0106] Figure 16 shows an example of the imaging range of imaging units 12101 to 12104. Imaging range 12111 indicates the imaging range of imaging unit 12101 located on the front nose, imaging ranges 12112 and 12113 indicate the imaging ranges of imaging units 12102 and 12103 located on the side mirrors, respectively, and imaging range 12114 indicates the imaging range of imaging unit 12104 located on the rear bumper or back door. For example, by superimposing the image data captured by imaging units 12101 to 12104, an overhead view image of the vehicle 12100 can be obtained.

[0107] At least one of the imaging units 12101 to 12104 may have a function for acquiring distance information. For example, at least one of the imaging units 12101 to 12104 may be a stereo camera consisting of multiple image sensors, or an image sensor having pixels for phase difference detection.

[0108] For example, the microcomputer 12051, based on distance information obtained from the imaging units 12101 to 12104, can determine the distance to each object within the imaging range 12111 to 12114 and the temporal change of this distance (relative speed to the vehicle 12100). In particular, it can extract the closest object on the vehicle 12100's path that is traveling in approximately the same direction as the vehicle 12100 at a predetermined speed (e.g., 0 km / h or more) as the preceding vehicle. Furthermore, the microcomputer 12051 can set a predetermined distance to be maintained before the preceding vehicle and perform automatic braking control (including follow-and-stop control) and automatic acceleration control (including follow-and-start control), etc. In this way, cooperative control aimed at autonomous driving, where the vehicle drives autonomously without driver intervention, can be performed.

[0109] For example, the microcomputer 12051 can use distance information obtained from imaging units 12101 to 12104 to classify and extract three-dimensional object data related to three-dimensional objects, such as motorcycles, passenger cars, large vehicles, pedestrians, utility poles, and other three-dimensional objects, and use this data for automatic obstacle avoidance. For example, the microcomputer 12051 identifies obstacles around the vehicle 12100 into obstacles that are visible to the driver of the vehicle 12100 and obstacles that are difficult to see. The microcomputer 12051 then determines the collision risk, which indicates the degree of risk of collision with each obstacle. If the collision risk is above a set value and there is a possibility of collision, the microcomputer 12051 can provide driving assistance to avoid collisions by outputting a warning to the driver via the audio speaker 12061 or the display unit 12062, or by performing forced deceleration or evasive steering via the drive system control unit 12010.

[0110] At least one of the imaging units 12101 to 12104 may be an infrared camera that detects infrared light. For example, the microcomputer 12051 can recognize pedestrians by determining whether or not pedestrians are present in the images captured by the imaging units 12101 to 12104. Such pedestrian recognition is performed, for example, by a procedure to extract feature points from the images captured by the imaging units 12101 to 12104 as infrared cameras, and a procedure to perform pattern matching on a series of feature points that indicate the contour of an object to determine whether or not it is a pedestrian. When the microcomputer 12051 determines that a pedestrian is present in the images captured by the imaging units 12101 to 12104 and recognizes a pedestrian, the audio-image output unit 12052 controls the display unit 12062 to superimpose a rectangular contour line for emphasis on the recognized pedestrian. The audio-image output unit 12052 may also control the display unit 12062 to display an icon indicating a pedestrian at a desired position.

[0111] The above describes an example of a vehicle control system to which the technology relating to this disclosure may be applied. The technology relating to this disclosure can be applied, for example, to the imaging units 12101 to 12104 of the configuration described above.

[0112] <Examples of Configuration Combinations> The technology can also take the following configurations: (1) An image sensor comprising: a semiconductor substrate on which a photodiode is provided for each pixel; a wiring layer laminated on the semiconductor substrate and having one or more metal wiring layers; and an absorption layer provided on the wiring layer so as to shield the metal wiring layer from light and absorbing laser light. (2) The image sensor according to (1) above, wherein light is irradiated onto the pixels from the back side of the semiconductor substrate, and the wiring layer is laminated on the front side of the semiconductor substrate, and the absorption layer is positioned on the semiconductor substrate side of the first metal wiring layer from the semiconductor substrate side provided on the wiring layer. (3) The image sensor according to (1) above, wherein light is irradiated onto the pixels from the front side of the semiconductor substrate, and the wiring layer is laminated on the back side of the semiconductor substrate, and the absorption layer is positioned between the uppermost metal wiring layer provided on the wiring layer and an on-chip lens layer provided above the wiring layer. (4) An image sensor according to any one of (1) to (3) above, wherein one or more layers of the absorption layer are provided on the wiring layer. (5) An image sensor according to any one of (1) to (4) above, wherein the absorption layer is fixed at a predetermined potential. (6) An image sensor according to any one of (1) to (5) above, wherein the absorption layer is composed of germanium, silicon germanium, quantum dots, or indium gallium arsenide. (7) An image sensor according to any one of (1) to (6) above, wherein a transistor layer constituting a transistor for driving the pixels is provided on the wiring layer so as to be shielded from light by the absorption layer. (8) A method for manufacturing an image sensor, comprising stacking a wiring layer on a semiconductor substrate on which a photodiode is provided for each pixel, on which one or more metal wiring layers are provided, and providing an absorption layer that absorbs laser light on the wiring layer so as to shield the metal wiring layer from light. (9) An electronic device comprising an image sensor having a semiconductor substrate on which a photodiode is provided for each pixel, a wiring layer laminated on the semiconductor substrate and having one or more metal wiring layers, and an absorption layer provided on the wiring layer so as to shield the metal wiring layer from light and to absorb laser light.

[0113] It should be noted that this embodiment is not limited to the embodiment described above, and various modifications are possible without departing from the spirit of this disclosure. Furthermore, the effects described herein are merely illustrative and not limiting, and other effects may also exist.

[0114] 11 Image sensor, 12 Pixel, 21 Semiconductor substrate, 22 Planarization layer, 23 Color filter layer, 24 On-chip lens layer, 25 Wiring layer, 31 Light-shielding film, 32 Insulating film, 33 Filter, 34 Lens, 41 Insulating film, 42 Polysilicon electrode, 43 Metal wiring layer, 44 Through electrode, 45 Germanium layer, 46 Absorption layer, 51 Transistor layer, 52 Semiconductor layer, 53 Polysilicon electrode, 54 Through electrode

Claims

1. An image sensor comprising: a semiconductor substrate on which a photodiode is provided for each pixel; a wiring layer laminated on the semiconductor substrate and having one or more metal wiring layers; and an absorption layer provided on the wiring layer so as to shield the metal wiring layer from light and to absorb laser light.

2. The image sensor according to claim 1, wherein light is irradiated onto the pixels from the back side of the semiconductor substrate, and the wiring layer is laminated on the front side of the semiconductor substrate, and the absorption layer is positioned on the semiconductor substrate side of the first metal wiring layer from the semiconductor substrate side provided on the wiring layer.

3. The image sensor according to claim 1, wherein light is irradiated onto the pixels from the surface side of the semiconductor substrate, and the wiring layer is laminated on the back side of the semiconductor substrate, and the absorption layer is disposed between the uppermost metal wiring layer provided on the wiring layer and an on-chip lens layer provided above the wiring layer.

4. The image sensor according to claim 1, wherein one or more layers of the absorption layer are provided on the wiring layer.

5. The image sensor according to claim 1, wherein the absorption layer is fixed at a predetermined potential.

6. The image sensor according to claim 1, wherein the absorption layer is composed of germanium, silicon germanium, quantum dots, or indium gallium arsenide.

7. The image sensor according to claim 1, wherein the transistor layer constituting the transistor for driving the pixel is provided on the wiring layer so as to be shielded from light by the absorption layer.

8. A method for manufacturing an image sensor, comprising stacking a wiring layer on a semiconductor substrate on which a photodiode is provided for each pixel, the wiring layer having one or more metal wiring layers, and providing an absorption layer that absorbs laser light on the wiring layer so as to shield the metal wiring layer from light.

9. An electronic device comprising an image sensor having a semiconductor substrate on which a photodiode is provided for each pixel, a wiring layer laminated on the semiconductor substrate and having one or more metal wiring layers, and an absorption layer provided on the wiring layer so as to shield the metal wiring layer from light and absorbing laser light.

Images