Image sensor and imaging device

Abstract

The present application relates to the technical field of imaging, and provides an image sensor and an imaging device. The image sensor comprises a pixel unit array, a micro-lens unit array and a plurality of polarization units; the pixel unit array comprises a plurality of pixel units, and each pixel unit comprises at least one photoelectric conversion element; the micro-lens unit array comprises a plurality of micro-lens units, and each micro-lens unit comprises at least one micro-lens; the pixel units are in one-to-one correspondence to the micro-lens units; each micro-lens covers a light receiving surface of the corresponding photoelectric conversion element; the plurality of polarization units are located between the pixel unit array and the micro-lens unit array, and each polarization unit corresponds to one pixel unit; and each polarization unit comprises at least one polarization assembly, each polarization assembly corresponds to one photoelectric conversion element, and the polarization assembly covers the corresponding photoelectric conversion element. The image sensor and the imaging device satisfy the requirements on image sensors for high dynamic range imaging and anti-glare performance in security and automotive fields, etc.

Description

Image sensor and imaging device

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims priority to the Chinese patent application filed with the State Intellectual Property Office of China on January 31, 2024, with application number 202410146508.6 and application name “An Image Sensor and Imaging Device”, the entire contents of which are incorporated by reference into this application. Technical Field

[0003] The present application relates to the field of imaging technology, and in particular to an image sensor and an imaging device. Background Art

[0004] Image sensors, devices that convert optical images into electronic signals, are widely used in electronic devices such as cameras and video cameras (for example, security cameras and automotive cameras). In recent years, image sensors have evolved from charge-coupled device (CCD) image sensors to complementary metal-oxide semiconductor (CMOS) image sensors, which offer lower costs and significantly improved noise levels. The advancement of machine vision and artificial intelligence (AI) has further increased the performance requirements for image sensors. For example, in the security and automotive fields, image sensors are required to exhibit excellent anti-glare performance and high dynamic range performance. Summary of the Invention

[0005] The embodiments of the present application provide an image sensor and an imaging device that can address the needs of security and automotive fields for high dynamic imaging and anti-glare performance of image sensors.

[0006] In a first aspect, the present application provides an image sensor comprising a pixel unit array, a microlens unit array, and a plurality of polarization units, wherein the pixel unit array comprises a plurality of pixel units, each of which comprises at least one photoelectric conversion element; the microlens unit array comprises a plurality of microlens units, each of which comprises at least one microlens; the plurality of pixel units correspond one-to-one to the plurality of microlens units, each photoelectric conversion element corresponds to a microlens, and each microlens covers the light-receiving surface of the corresponding photoelectric conversion element; the plurality of polarization units are located between the pixel unit array and the microlens unit array, each of which corresponds to a pixel unit; the polarization unit comprises at least one polarization component, each of which corresponds to a photoelectric conversion element, and the polarization component covers the corresponding photoelectric conversion element. In this solution, on the one hand, the image generated by the photoelectric conversion element covered with the polarization component is polarized imaging, which can provide an anti-glare effect. On the other hand, the photoelectric conversion element covered with the polarization component has a small amount of light entering, and can form an image with a different amount of light entering than the photoelectric conversion element not covered with the polarization component. The synthesis of these two images can form high-dynamic imaging. In other words, the image sensor provided by this solution is both glare-proof and has high-dynamic imaging performance, thereby meeting the needs of high-dynamic imaging in the security and automotive fields, and can also meet the imaging problems in glare scenes such as backlit scenes and light metering scenes, realizing full-environment detection in high-dynamic, extremely low-light and strong-light environments.

[0007] Furthermore, in a possible embodiment, the pixel unit includes four photoelectric conversion elements, and the pixel unit is a four-pixel-in-one structure.

[0008] Furthermore, in one possible embodiment, each polarization unit includes two polarization components, and the two polarization components correspond one-to-one to two diagonal photoelectric conversion elements in the corresponding pixel unit. In this solution, the polarization components are more evenly distributed across the pixel unit, which can improve the high dynamic performance and anti-glare performance of the image sensor.

[0009] Furthermore, in a possible embodiment, the polarization angles of the polarization components are the same, so as to facilitate data processing by the image sensor.

[0010] In one possible embodiment, each pixel unit includes a filter unit located between the photoelectric conversion element and the microlens, the filter unit including at least one filter, and the pixel unit array is a four-pixel-in-one Bayer array. Each filter corresponds to a photoelectric conversion element, and the filter covers the corresponding photoelectric conversion element. In other words, the image sensor is a four-pixel-in-one Bayer array based on color pixels, enabling electronic devices using the image sensor provided by this embodiment to capture color images.

[0011] Furthermore, in a possible embodiment, each of the polarization units includes one polarization component.

[0012] In another possible embodiment, each polarization unit includes two polarization components; the two polarization components correspond one-to-one to two diagonal photoelectric conversion elements in the corresponding pixel unit. In this solution, the polarization components are more evenly distributed across the pixel unit, which can improve the image sensor's high dynamic performance and anti-glare performance.

[0013] Furthermore, the polarization angles of the two polarization components in each polarization unit are different.

[0014] In one possible embodiment, the image sensor includes a semiconductor substrate, in which the photoelectric conversion element is arranged; a grid structure is provided on the surface of the semiconductor substrate facing the microlens unit array, and the grid structure has a plurality of openings, and the plurality of openings correspond one-to-one to each of the photoelectric conversion elements and each of the microlenses, and are used to guide the light incident from the microlens to the corresponding photoelectric conversion element; the image sensor also includes a transparent planarization layer, the planarization layer covers the grid structure, and the surface of the planarization layer opposite to the semiconductor substrate is parallel to the surface of the semiconductor substrate facing the planarization layer, and the polarization component is arranged on the surface of the planarization layer opposite to the semiconductor substrate.

[0015] Furthermore, in one possible embodiment, the planarization layer includes an optical waveguide structure. The optical waveguide structure is used to increase the amount of light entering. The optical waveguide structure has a higher refractive index than the structures in other parts of the planarization layer, thereby allowing more light to enter the photoelectric conversion element, thereby making the pixel unit more sensitive to light. In addition, the amount of light entering the first type of pixel and the second type of pixel can be adjusted by changing the size of the optical waveguide structure, thereby further increasing the difference in the amount of light entering the two types of pixels, which is more conducive to achieving high dynamic range.

[0016] In one possible embodiment, the image sensor includes an image signal processor, which is used to process the received electrical signals sent by each of the photoelectric conversion elements to form an anti-glare image signal, and to synthesize the strong light area in the first image with the non-strong light area in the second image to obtain an image signal of a high dynamic range image; wherein the first image is an image generated by processing the photoelectric conversion element covered with the polarization component, and the second image is an image generated by processing the photoelectric conversion element not covered with the polarization component.

[0017] Furthermore, in a possible embodiment, each of the pixel units further includes a dual conversion gain control unit, which is used to implement gain control. The dual conversion gain control unit is used to implement gain control. The dual conversion gain control unit can implement two conversion gain conversions for the first type of pixel and the second type of pixel, respectively, thereby further improving the high dynamic range based on the high dynamic range achieved by the above-mentioned strong and weak light input amounts.

[0018] In a second aspect, an embodiment of the present application provides an imaging device, which includes a lens module and an image sensor provided by the technical solution of the first aspect, wherein the lens module and the image sensor are arranged in sequence along the direction of the optical path, and the image sensor can convert the light image entering from the lens module into an electrical signal. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] FIG1 is a schematic structural diagram of an image sensor provided in an embodiment of the present application;

[0020] FIG2 is an exploded view of the image sensor shown in FIG1 ;

[0021] FIG3 is a schematic structural diagram of an image sensor provided in an embodiment of the present application;

[0022] FIG4 is a schematic diagram of a typical high dynamic result of the image sensor corresponding to FIG3 ;

[0023] FIG5 is a schematic structural diagram of another image sensor provided in an embodiment of the present application;

[0024] FIG6 is a schematic diagram of the structure of another image sensor provided in an embodiment of the present application;

[0025] FIG7 is a cross-sectional view of an image sensor provided in an embodiment of the present application;

[0026] FIG8 is a schematic structural diagram of an image sensor provided in an embodiment of the present application;

[0027] FIG9 is a schematic diagram of a typical high dynamic range result of the image sensor corresponding to FIG8 ;

[0028] FIG10 is a schematic structural diagram of an image sensor provided in an embodiment of the present application;

[0029] FIG11 is a cross-sectional view of an image sensor provided in an embodiment of the present application;

[0030] FIG12 is a cross-sectional view of another image sensor provided in an embodiment of the present application;

[0031] FIG13 is a schematic diagram of the steps for manufacturing an image sensor provided in an embodiment of the present application;

[0032] FIG14 is a schematic diagram of the steps for manufacturing an image sensor provided in an embodiment of the present application;

[0033] FIG15 is a schematic diagram of the steps for manufacturing an image sensor provided in an embodiment of the present application;

[0034] FIG16 is a schematic diagram of the steps for manufacturing an image sensor provided in an embodiment of the present application;

[0035] FIG17 is a schematic diagram of the steps for manufacturing an image sensor provided in an embodiment of the present application;

[0036] FIG18 is a schematic diagram of the steps for manufacturing an image sensor provided in an embodiment of the present application;

[0037] FIG19 is a control flow chart of an image sensor provided by an embodiment of the present application;

[0038] FIG20 is a control flow chart of another image sensor provided in an embodiment of the present application;

[0039] FIG21 is a control flow chart of another image sensor provided in an embodiment of the present application;

[0040] FIG22 is a schematic structural diagram of an imaging device provided in an embodiment of the present application.

[0041] Label: 1-pixel unit array; 11-pixel unit; 111-photoelectric conversion element; 2-microlens unit array; 21-microlens unit; 211-microlens; 3-polarization unit; 31-polarization component; 4-filter; 5-semiconductor substrate; 51-deep trench isolation pattern; 6-grating structure; 7-planarization layer; 71-optical waveguide structure; 8-image signal processor; 81-glare processing unit; 82-dynamic synthesis unit; 83-dual conversion gain control unit; 84-output unit; 9-filling layer; 100-image sensor; 200-lens module. DETAILED DESCRIPTION

[0042] The image sensor provided in the embodiment of the present application can be applied to various camera modules, for example, it can be applied to camera devices such as still cameras, vehicle-mounted cameras, and security cameras. The image sensor in the embodiment of the present application can be a CCD image sensor or a CMOS image sensor. Specifically, when light irradiated on an object is incident on the image sensor, each pixel unit in the image sensor can convert the incident light incident on the pixel unit into a corresponding electrical signal. The image processing module in the image sensor can generate an image of the object or determine changes in the object through the electrical signals provided by each pixel unit.

[0043] As the security and automotive fields place higher demands on the anti-glare and high-dynamic performance of image sensors, the design of image sensors is being further optimized. For example, in some embodiments, a portion of the pixels of the image sensor are partially blocked by a baffle. That is, the baffle reduces the light-receiving area of ​​these pixels, thereby reducing the amount of light entering these pixels and, in turn, reducing the photosensitivity of these pixels. In this way, the unblocked pixels have a relatively larger area and can receive more light, thus achieving better imaging effects under low illumination; the blocked pixels have a relatively smaller area and receive weaker light, making them less likely to be overexposed under strong light. The combination of these two types of pixels creates high dynamics. Although the image sensor in this solution has certain high-dynamic performance, it does not have anti-glare performance.

[0044] Based on this, the embodiments of the present application provide an image sensor and an imaging device to solve the above problems. In order to make the purpose, technical solutions and advantages of the present application more clear, the present application will be further described in detail below with reference to the accompanying drawings.

[0045] The terms used in the following embodiments are only for the purpose of describing specific embodiments and are not intended to limit the present application. As used in the specification and appended claims of this application, the singular expressions "a", "an", "said", "above", "the", and "this" are intended to also include expressions such as "one or more", unless the context clearly indicates otherwise.

[0046] References to "one embodiment" or "some embodiments" in this specification mean that a particular feature, structure, or characteristic described in conjunction with that embodiment is included in one or more embodiments of the present application. Thus, phrases such as "in one embodiment," "in some embodiments," "in other embodiments," and "in yet other embodiments" appearing in various places in this specification do not necessarily refer to the same embodiment, but rather mean "one or more but not all embodiments," unless otherwise specifically emphasized. The terms "including," "comprising," "having," and variations thereof mean "including but not limited to," unless otherwise specifically emphasized.

[0047] FIG1 is a schematic structural diagram of an image sensor 100 provided in an embodiment of the present application, and FIG2 is an exploded view of the image sensor 100 shown in FIG1 . As shown in FIG1 and FIG2 , an image sensor 100 provided in an embodiment of the present application includes a pixel unit array 1, a microlens unit array 2, and multiple polarization units 3. Specifically, the pixel unit array 1 and the microlens unit array 2 are both M×N arrays, where M and N are both integers greater than 1. That is, the pixel unit array 1 includes multiple pixel units 11, which are arranged in an M×N array. The microlens unit array 2 includes multiple microlens units 21, which are also arranged in an M×N array. Furthermore, the multiple pixel units 11 correspond one-to-one to the multiple microlens units 21. That is, each pixel unit 11 corresponds to one microlens unit 21, and each microlens unit 21 corresponds to one pixel unit 11. Specifically, each pixel unit 11 includes at least one photoelectric conversion element 111, such as a photodiode. Each microlens unit 21 includes at least one microlens 211, and each photoelectric conversion element 111 corresponds to a microlens 211, and each microlens 211 covers the light-receiving surface of the corresponding photoelectric conversion element 111, so that the light entering through the microlens 211 can reach the light-receiving surface of the corresponding photoelectric conversion element 111. The multiple polarization units 3 are located between the pixel unit array 1 and the microlens unit array 2, and each polarization unit 3 corresponds to a pixel unit 11. Furthermore, the polarization unit 3 includes at least one polarization component 31, each polarization component 31 corresponds to a photoelectric conversion element 111, and the polarization component 31 covers the light-receiving surface of the corresponding photoelectric conversion element 111. In this solution, on the one hand, the image generated by the photoelectric conversion element 111 covered with the polarization component 31 is polarized imaging, which can have an anti-glare effect. On the other hand, the photoelectric conversion element 111 covered with the polarization component 31 has a small amount of light entering, and can form an image with a different amount of light entering than the photoelectric conversion element 111 not covered with the polarization component 31. The synthesis of these two images can form high-dynamic imaging. In other words, the image sensor 100 provided by this solution is both glare-proof and has high-dynamic imaging performance, thereby being able to solve the needs of security and automotive fields for high-dynamic imaging, and also meet the imaging problems in glare scenes such as backlit scenes and light metering scenes, and realize full-environment detection in high-dynamic, extremely low-illumination and strong-light environments.

[0048] It should be understood that each photoelectric conversion element 111 corresponds to a pixel; at the same time, a planarization layer 7 may be provided on the side of the polarization unit 3 opposite the pixel unit array 1, and the microlens unit 21 may be disposed on the planarization layer 7. Furthermore, for ease of understanding, the following description will refer to pixels corresponding to photoelectric conversion elements 111 covered with polarization components 31 as first-category pixels, and pixels corresponding to photoelectric conversion elements 111 not covered with polarization components 31 as second-category pixels.

[0049] In a specific implementation, the number of polarization units 3 can be smaller than the number of pixel units 11, thereby facilitating ensuring the amount of light entering the image sensor 100. Of course, in other embodiments, the number of polarization units 3 can also be equal to the number of pixel units 11 according to actual needs. Furthermore, in some embodiments, multiple polarization units 3 are evenly distributed on the surface of the pixel unit array 1, and the number of polarization components 31 in the polarization unit 3 is smaller than the number of photoelectric conversion elements 111 in the corresponding pixel unit 11. The relative position relationship between the polarization component 31 in each polarization unit 3 and the corresponding pixel unit 11 is the same (as shown in FIG3 ), to facilitate subsequent data processing.

[0050] In a specific implementation, each pixel unit 11 may include one photoelectric conversion element 111, two photoelectric conversion elements 111, three photoelectric conversion elements 111, or four photoelectric conversion elements 111. For example, when the pixel unit 11 includes two photoelectric conversion elements 111, the pixel unit 11 may have a two-pixel-in-one structure; when the pixel unit 11 includes three photoelectric conversion elements 111, the pixel unit 11 may have a three-pixel-in-one structure; and when the pixel unit 11 includes four photoelectric conversion elements 111, the pixel unit 11 may have a four-pixel-in-one structure. A four-pixel-in-one structure is a structure in which four adjacent pixels of the same color are arranged together to form a pixel structure that is four times the size of the original pixel area. For example, taking the pixel unit 11 as a four-pixel-in-one structure, in some embodiments, the ratio of the number of polarization components 31 to the number of photoelectric conversion elements 111 may be 1 / 10 to 9 / 10, so as to ensure the amount of light entering the image sensor 100 while ensuring high dynamic performance and anti-glare performance.

[0051] FIG3 is a schematic diagram of the structure of an image sensor provided in an embodiment of the present application. As shown in FIG3 , in a specific implementation, the pixel unit 11 includes four photoelectric conversion elements 111, and the pixel unit 11 is a four-pixel-in-one structure. Each polarization unit 3 includes two polarization components 31, and the two polarization components 31 correspond one-to-one to the two photoelectric conversion elements 111 in the corresponding pixel unit 11 that are in a diagonal relationship. In this solution, the distribution of the polarization components 31 on the pixel unit 11 is more uniform, which can make the high dynamic performance and anti-glare performance of the image sensor 100 better. Furthermore, the polarization angles of each polarization component 31 are the same to facilitate data processing of the image sensor 100. For example, the polarization angles of each polarization component 31 can be 0°, 45° (as shown in FIG3 ), 90° or 135°, etc. It is not difficult to understand that the polarization angle of the polarization component 31 is not limited to the above four angles, and the polarization angle of the polarization component 31 can also be other angles according to actual needs. FIG4 is a schematic diagram of typical high-dynamic range (HDR) results for image sensor 100 corresponding to FIG3 . The horizontal axis represents light intensity, denoted by L, and the vertical axis represents high-dynamic range (HDR), denoted by HDR. FIG4 shows that within a certain light intensity range, HDR increases with increasing light intensity. Furthermore, it can be seen that the various HDR measures of the present invention can achieve high-dynamic range imaging. For example, HDR can reach 100dB to 170dB.

[0052] Of course, when the pixel unit 11 is a four-pixel-in-one structure, the arrangement of the polarization unit 3 is not limited to the situation shown in FIG3 . For example, the number of polarization components 31 in the polarization unit 3 can also be one, three, or four. Among them, when the number of polarization components 31 in the polarization unit 3 is one, the position of the polarization component 31 in each polarization unit 3 relative to the corresponding pixel unit 11 can be the same, so as to facilitate data processing of the image sensor 100. For example, FIG5 is a structural schematic diagram of another image sensor 100 provided in an embodiment of the present application. As shown in FIG5 , the polarization component 31 corresponds to the photoelectric conversion element 111 in the upper left corner of the corresponding pixel unit 11, that is, the polarization component 31 corresponds to the photoelectric conversion element 111 in the upper left corner of the corresponding pixel unit 11. When the number of polarization components 31 in the polarization unit 3 is three, the position of the polarization component 31 in each polarization unit 3 relative to the corresponding pixel unit 11 can also be the same, so as to facilitate data processing of the image sensor 100. For example, Figure 6 is a structural schematic diagram of another image sensor 100 provided in an embodiment of the present application. As shown in Figure 6, in each pixel unit 11, only the photoelectric conversion element 111 in the upper left corner does not have a corresponding polarization component 31, and the remaining three photoelectric conversion elements 111 each correspond to a polarization component 31.

[0053] It is worth noting that when the pixel unit 11 is a four-pixel-in-one structure, the distribution of the polarization components 31 in the polarization unit 3 is not limited to the above method, and other distribution forms can also be adopted according to actual needs. The above is only an example and not an exhaustive list.

[0054] FIG7 is a cross-sectional view of an image sensor 100 provided in an embodiment of the present application. As shown in FIG7 , in some embodiments, each pixel unit 11 includes a filter unit located between the photoelectric conversion element 111 and the microlens 211, the filter unit includes at least one filter 4, and the pixel unit array 1 is a four-pixel-in-one Bayer array. In other words, the image sensor 100 is a four-pixel-in-one Bayer array based on color pixels, so that the electronic device using the image sensor 100 provided in this embodiment can record color images. Exemplarily, each filter 4 corresponds to a photoelectric conversion element 111, and the filter 4 covers the corresponding photoelectric conversion element 111. Continuing to refer to FIG7 , in some embodiments, the polarization component 31 is located between the corresponding filter 4 and the photoelectric conversion element 111.

[0055] Next, based on the image sensor 100 shown in FIG7 and in conjunction with FIG8 , a specific image sensor 100 will be described. As shown in FIG8 , in the image sensor 100 , each polarization unit 3 includes a polarization component 31 . The image sensor 100 includes a 3×3 pixel unit array 1 , wherein the nine pixel units are pixel unit 1, pixel unit 2, pixel unit 3, pixel unit 4, pixel unit 5, pixel unit 6, pixel unit 7, pixel unit 8, and pixel unit 9. Pixel unit 1, pixel unit 2, and pixel unit 1 are arranged sequentially along a row direction E; pixel unit 4, pixel unit 5, and pixel unit 6 are arranged sequentially along a row direction E; and pixel unit 7, pixel unit 8, and pixel unit 9 are arranged sequentially along a row direction E. Simultaneously, along a column direction F, pixel unit 1, pixel unit 4, and pixel unit 7 are arranged sequentially; pixel unit 2, pixel unit 5, and pixel unit 8 are arranged sequentially; and pixel unit 3, pixel unit 6, and pixel unit 9 are arranged sequentially. Among them, pixel unit 1, pixel unit 3, pixel unit 7, and pixel unit 9 all include four red filters 4 and are red pixel units, represented by R in Figure 8. Pixel unit 2, pixel unit 4, pixel unit 6, and pixel unit 8 all include four green filters 4 and are green pixel units, represented by G in Figure 8. Pixel unit 5 includes four blue filters 4 and is a blue pixel unit, represented by B in Figure 8. In this solution, the ratio of the number of first-class pixels to the number of second-class pixels is 1 / 3. By performing binning readout of the charge domain of each second-class pixel in pixel unit 11, dynamic performance can be further improved.

[0056] FIG9 is a schematic diagram of a typical high dynamic range result of the image sensor 100 corresponding to FIG8 , wherein the horizontal axis represents light intensity, represented by the symbol L, and the vertical axis represents HDR. As can be seen from FIG9 , within a certain light intensity range, HDR increases with increasing light intensity. It can also be seen that high dynamic range imaging can be achieved through the various HDR measures of the present invention, for example, HDR can reach 100 dB to 170 dB.

[0057] Still based on the image sensor 100 shown in Figure 7, as shown in Figure 10, in some other embodiments, each polarization unit 3 includes two polarization components 31. Specifically, the two polarization components 31 correspond one-to-one to the two photoelectric conversion elements 111 in the corresponding pixel unit 11 that are in a diagonal relationship, so that the two polarization components 31 in the polarization unit 3 are more evenly distributed on the corresponding pixel unit 11, which can make the high dynamic performance and anti-glare performance of the image sensor 100 better.

[0058] Specifically, as shown in FIG10 , taking a 2×2 pixel unit array 1 as an example, the four pixel units 11 are respectively a first pixel unit, a second pixel unit, a third pixel unit, and a fourth pixel unit, wherein the first pixel unit and the second pixel unit are arranged sequentially along the row direction E, and the third pixel unit and the fourth pixel unit are arranged sequentially along the row direction E. At the same time, along the column direction F, the first pixel unit and the third pixel unit are arranged sequentially, and the second pixel unit and the fourth pixel unit are arranged sequentially. The first pixel unit includes four red filters 4 and is a red pixel unit, and the red pixel unit is represented by R in FIG10 . The second pixel unit and the third pixel unit each include four green filters 4 and are a green pixel unit, and the green pixel unit is represented by G in FIG10 . The fourth pixel unit includes four blue filters 4 and is a blue pixel unit, and the blue pixel unit is represented by B in FIG10 . Each polarization unit 3 includes two polarization components 31. The two polarization components 31 correspond one-to-one to two diagonal photoelectric conversion elements 111 in the corresponding pixel unit 11. The two polarization components 31 in each polarization unit 3 have different polarization angles. For example, as shown in FIG10 , the polarization angle of one polarization component 31 in the polarization unit 3 is 45°, and the polarization angle of the other polarization component 31 is 135°. Of course, in some embodiments, the polarization angles of the polarization components 31 may also be the same.

[0059] It should be understood that the arrangement of the polarization component 31 relative to the pixel unit array 1 is not limited to the above situation, and other arrangements can also be adopted according to actual needs.

[0060] FIG11 is a cross-sectional view of an image sensor 100 provided in an embodiment of the present application. As shown in FIG11 , in a specific embodiment, the image sensor 100 includes a semiconductor substrate 5, and a photoelectric conversion element 111 is disposed in the semiconductor substrate 5. In a specific implementation, the material of the semiconductor substrate 5 can be bulk silicon, and a pixel isolation pattern 51 is provided in the semiconductor substrate 5, for example, a deep trench isolation (DTI) pattern, and adjacent photoelectric conversion elements 111 are isolated by the pixel isolation pattern 51. Furthermore, a grid structure 6 is provided on the surface of the semiconductor substrate 5 facing the microlens unit array 2, and the grid structure 6 has a plurality of openings, and the plurality of openings correspond one-to-one to each microlens 211 and the photoelectric conversion element 111, and are used to guide the light incident from the microlens 211 to the corresponding photoelectric conversion element 111. It is not difficult to understand that the openings of the grid structure 6 are opposite to the corresponding microlens 211 and the photoelectric conversion element 111 in the incident direction of the light. Continuing with Figure 11 , image sensor 100 further includes a transparent planarization layer 7. Planarization layer 7 covers grid structure 6, and the surface of planarization layer 7 opposite semiconductor substrate 5 is parallel to the surface of semiconductor substrate 5 facing planarization layer 7. Polarization element 31 is disposed on the surface of planarization layer 7, and color filter 4 is disposed on the surface of polarization element 31. For the second type of pixels, color filter 4 is disposed on the surface of planarization layer 7. As shown in Figure 12 , in image sensor 100 without color filter 4, a filling layer 9 is disposed on the surface of planarization layer 7 opposite semiconductor substrate 5, and each microlens 211 is disposed on the surface of the filling layer.

[0061] In some embodiments, the planarization layer 7 includes an optical waveguide structure 71, which is used to increase the amount of light entering. The optical waveguide structure 71 has a higher refractive index than the structures in other parts of the planarization layer 7, and thus can guide more light into the photoelectric conversion element 111, thereby making the pixel unit 11 more sensitive to light. In addition, the volume of the optical waveguide structure can be changed to adjust the amount of light entering the first type of pixel and the second type of pixel, thereby further increasing the difference in the amount of light entering the two types of pixels, which is more conducive to achieving high dynamic range.

[0062] The following briefly introduces a method for manufacturing the image sensor 100 .

[0063] Step 1: Provide a semiconductor substrate 5, wherein the semiconductor substrate 5 has a pixel isolation region and a pixel area. Specifically, the semiconductor substrate 5 is patterned to form a deep trench, i.e., the pixel isolation region. Each area enclosed by the pixel isolation region is the pixel area. An insulating material is embedded in the deep trench to form a deep trench isolation pattern, i.e., a pixel isolation pattern 51. A photoelectric conversion element 111 is fabricated in the pixel area, resulting in the structure shown in FIG13 .

[0064] Step 2: fabricating a grid structure 6 on the surface of the semiconductor substrate 5, wherein the grid structure 6 includes a plurality of openings, and the plurality of openings of the grid structure 6 are aligned with each of the photoelectric conversion elements 111, as shown in FIG14 ;

[0065] Step 3: Fill the openings of the grid structure 6 , as shown in FIG15 ; wherein the refractive index of the filling material may be higher than the refractive index of the grid structure 6 .

[0066] Step 4: Chemical mechanical planarization (CMP) is performed on the surfaces of the dielectric layer and the grid structure 6 to planarize them into a planarization layer 7, as shown in FIG16 ;

[0067] Step 5: Dispose a polarizing component 31 and a filter 4 on the surface of the planarization layer 7, as shown in FIG17 ;

[0068] Step 6: Prepare micro lenses 211 on the surface of each filter 4, as shown in FIG. 18 .

[0069] FIG19 is a control flow chart of an image sensor 100 provided in an embodiment of the present application. As shown in FIG19 , in some embodiments, the image sensor 100 includes an image signal processor (ISP) 8. The ISP 8 is configured to process the electrical signals received from each photoelectric conversion element 111 to form an anti-glare image signal, and to synthesize the bright light areas in the first image with the non-bright light areas in the second image to obtain an image signal for a high dynamic range image. The first image is generated by processing the first type of pixels, and the second image is generated by processing the second type of pixels. In this scheme, the first type of pixels can filter out most of the bright light interference signals, leaving a signal with a high signal-to-noise ratio. This signal is processed by the ISP 8 to form the anti-glare image signal. Furthermore, because the first type of pixels receive relatively little light, they can effectively prevent overexposure of the bright light areas of the subject when imaging the subject. Because the second type of pixels receive relatively much light, they can better image the non-bright light areas of the subject when imaging the subject. Image signal processor 8 synthesizes the bright areas in the first image with the non-bright areas in the second image to produce an image signal for a high dynamic range image. Furthermore, in this solution, image signal processor 8 can process data from a single exposure and two reads to output an image with a wider dynamic range. It is worth noting that the terms "bright" and "non-bright" are relative terms and can be determined empirically. In other words, the division between bright areas and non-bright areas can be determined empirically.

[0070] FIG20 is a control flow chart of an image sensor 100 provided in an embodiment of the present application. As shown in FIG20 , in one specific implementation, the image signal processor 8 includes a glare processing unit 81 and a dynamic synthesis unit 82. The high signal-to-noise ratio signal remaining after the first type of pixels filters out most of the strong light interference signal is processed by the glare processing unit 81 to form an anti-glare image signal. The dynamic synthesis unit 82 synthesizes the strong light areas in the first image with the non-strong light areas in the second image to obtain an image signal with a high dynamic range.

[0071] FIG21 is a control flow chart of an image sensor 100 provided in an embodiment of the present application. As shown in FIG21 , each pixel unit 11 further includes a dual conversion gain (DCG) control unit 83, which is used to implement gain control. The dual conversion gain control unit 83 can implement two conversion gain (CG) conversions for the first type of pixels and the second type of pixels, respectively, thereby further improving the high dynamics on the basis of achieving high dynamics for the above-mentioned strong and weak light input amounts; the improved high dynamic data is processed by the dynamic synthesis unit. The image sensor 100 may also include an output unit 84, and the high dynamic image signal synthesized by the dynamic synthesis unit 82 is output to the storage unit of the imaging device, etc. via the output unit 84.

[0072] FIG22 is a schematic structural diagram of an imaging device provided by an embodiment of the present application. As shown in FIG22 , the imaging device includes a lens module 200 and the above-mentioned image sensor 100, wherein the lens module 200 and the image sensor 100 are arranged in sequence along the optical path direction, so that the image sensor 100 can convert the light entering from the lens module 200 into an electrical signal. In this solution, on the one hand, the light entering the image sensor 100 through the lens module 200 is processed by the first type of pixels to generate a polarized image, which can have an anti-glare effect. On the other hand, the first type of pixels have a small amount of light input, and can form an image with a different amount of light input with the second type of pixels. After the two types of images are synthesized, high-dynamic imaging can be formed.

[0073] Obviously, those skilled in the art may make various changes and modifications to this application without departing from the spirit and scope of this application. Thus, if these modifications and variations of this application fall within the scope of the claims of this application and their equivalents, this application is intended to include these modifications and variations.

Claims

1. An image sensor, characterized in that: The device comprises a pixel unit array, a microlens unit array, and a plurality of polarization units, wherein the pixel unit array comprises a plurality of pixel units, each of which comprises at least one photoelectric conversion element; the microlens unit array comprises a plurality of microlens units, each of which comprises at least one microlens; the plurality of pixel units correspond one to one with the plurality of microlens units, each photoelectric conversion element corresponds to one microlens, and each microlens covers the light-receiving surface of the corresponding photoelectric conversion element; The multiple polarization units are located between the pixel unit array and the microlens unit array, and each polarization unit corresponds to one pixel unit; the polarization unit includes at least one polarization component, each polarization component corresponds to one photoelectric conversion element, and the polarization component covers the corresponding photoelectric conversion element.

2. The image sensor according to claim 1, wherein The pixel unit includes four photoelectric conversion elements, and the pixel unit is a four-pixel-in-one structure.

3. The image sensor according to claim 2, wherein: Each of the polarization units includes two polarization components, and the two polarization components correspond one-to-one to two diagonal photoelectric conversion elements in the corresponding pixel unit.

4. The image sensor according to claim 3, wherein The polarization angles of the polarization components are the same.

5. The image sensor according to claim 2, wherein: Each of the pixel units includes a filter unit located between the photoelectric conversion element and the microlens, the filter unit includes at least one filter, and the pixel unit array is a four-pixel-in-one Bayer array; each of the filters corresponds to one of the photoelectric conversion elements, and the filter covers the corresponding photoelectric conversion element.

6. The image sensor according to claim 5, wherein: Each of the polarization units includes one polarization component.

7. The image sensor according to claim 5, wherein: Each of the polarization units includes two polarization components; the two polarization components correspond one-to-one to the two diagonal photoelectric conversion elements in the corresponding pixel unit.

8. The image sensor according to claim 7, wherein: The polarization angles of the two polarization components in each polarization unit are different.

9. The image sensor according to any one of claims 1 to 8, wherein: The device comprises a semiconductor substrate in which the photoelectric conversion element is disposed; a grid structure is provided on a surface of the semiconductor substrate facing the microlens unit array, the grid structure having a plurality of openings, the plurality of openings corresponding one-to-one to each of the photoelectric conversion element and each of the microlenses, and used to guide light incident from the microlenses to the corresponding photoelectric conversion element; The image sensor also includes a transparent planarization layer, which covers the grid structure. The surface of the planarization layer opposite to the semiconductor substrate is parallel to the surface of the semiconductor substrate facing the planarization layer. The polarization component is arranged on the surface of the planarization layer opposite to the semiconductor substrate.

10. The image sensor according to claim 9, wherein The planarization layer includes an optical waveguide structure.

11. The image sensor according to any one of claims 1 to 10, wherein: It includes an image signal processor, which is used to process the received electrical signals sent by each of the photoelectric conversion elements to form an anti-glare image signal, and to synthesize the strong light area in the first image with the non-strong light area in the second image to obtain an image signal of a high dynamic range image; wherein, the first image is an image generated by processing the photoelectric conversion element covered with the polarization component, and the second image is an image generated by processing the photoelectric conversion element not covered with the polarization component.

12. The image sensor according to claim 11, wherein Each of the pixel units further includes a dual conversion gain control unit, which is used to implement gain control.

13. An imaging device, characterized in that: The invention comprises a lens module and the image sensor according to any one of claims 1 to 12, wherein the lens module and the image sensor are arranged in sequence along the optical path direction, and the image sensor can convert the light image entering through the lens module into an electrical signal.

Images