Image sensor pixel unit, image sensor and electronic equipment

Abstract

The invention discloses an image sensor pixel unit, an image sensor and electronic equipment, and belongs to the field of image sensors. The image sensor pixel unit comprises at least one image sub-pixel, wherein each image sub-pixel comprises a photodiode layer and a micro-lens unit; the photodiode layer of each image sub-pixel comprises 2K first photodiodes and 4K second photodiodes, K is a positive integer power of 2, the size of the long side of each first photodiode is twice that of each second photodiode, and the size of the short side of each first photodiode is equal to that of each second photodiode; the micro-lens unit of each image sub-pixel comprises K first micro-lenses and 4K second micro-lenses, each first micro-lens covers two adjacent first photodiodes, each second micro-lens correspondingly covers a second photodiode, and a second micro-lens arranged in a # imgabs0 # array is arranged between every two adjacent first micro-lenses.

Description

Technical Field

[0001] This application belongs to the field of image sensors, and particularly relates to an image sensor pixel unit, an image sensor, and an electronic device. Background Art

[0002] With the continuous development of software and hardware photography technologies of electronic devices such as mobile phones and computers, users' demands for the photography functions of various electronic devices are also increasing day by day, especially in meeting the shooting requirements of various sub-scenarios. Despite the continuous upgrade of the hardware and software of electronic devices, there are still some shooting scenarios where it is difficult to solve shooting problems. For example, in shooting large dynamic range scenarios or high-brightness scenarios (hereinafter collectively referred to as: high dynamic range scenarios), overexposure problems may still occur in some areas, or some areas may be too dark, resulting in the loss of details in some areas, and thus an ideal shooting effect cannot be achieved. Summary of the Invention

[0003] The purpose of the embodiments of this application is to provide an image sensor pixel unit, an image sensor, and an electronic device, which can at least solve the problem of overexposure or underexposure in some areas in high dynamic range scenarios.

[0004] In a first aspect, the embodiments of this application provide an image sensor pixel unit, including: at least one image sub-pixel, and each of the image sub-pixels includes a photodiode layer and a microlens unit; the photodiode layer of each of the image sub-pixels includes 2K first photodiodes and 4K second photodiodes, where K is a positive integer power of 2, the long side dimension of the first photodiode is twice the size of the second photodiode, and the short side dimension of the first photodiode is equal to the size of the second photodiode; the microlens unit of each of the image sub-pixels includes K first microlenses and 4K second microlenses, each of the first microlenses covers two adjacent first photodiodes, each of the second microlenses correspondingly covers the second photodiodes, and second microlenses arranged in an array are provided between every two adjacent first microlenses.

[0005] In a second aspect, the embodiments of this application provide an image sensor, including M rows and N columns of the image sensor pixel units as described in the first aspect above, where M and N are integer multiples of 4, and both M and N are greater than or equal to 8.

[0006] In a third aspect, the embodiments of this application provide an electronic device, including the image sensor as described in the second aspect above.

[0007] In an embodiment of the present application, an image sensor pixel unit includes at least one image sub-pixel, and each image sub-pixel includes a photodiode layer and a microlens unit; the photodiode layer of each image sub-pixel includes 2K first photodiodes and 4K second photodiodes, where K is a positive integer power of 2, the long side dimension of the first photodiode is twice the dimension of the second photodiode, and the short side dimension of the first photodiode is equal to the dimension of the second photodiode; the microlens unit of each image sub-pixel includes K first microlenses and 4K second microlenses, each first microlens covers two adjacent first photodiodes, each second microlens correspondingly covers a second photodiode, and second microlenses arranged in an array are provided between every two adjacent first microlenses. In this way, in a high dynamic range scenario, overexposure spillage in the high-light area can be avoided through the first photodiodes and the first microlenses, and at the same time, higher resolution can be achieved through the second photodiodes and the second microlenses under the same area, thereby reducing the loss of details in some areas and improving the shooting effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] Figure 1 is a top view of an image sensor pixel unit provided by an embodiment of the present application; Figure 2 is Figure 1 the M sectional view of the image sensor pixel unit in Figure 3 is Figure 1 the N sectional view of the image sensor pixel unit in Figure 4 is another top view of an image sensor pixel unit provided by an embodiment of the present application; Figures 5a - 5c is yet another top view of an image sensor pixel unit provided by an embodiment of the present application; Figure 6 is a schematic structural diagram of a pixel unit circuit provided by an embodiment of the present application; Figure 7 is a schematic structural diagram of an image sensor provided by an embodiment of the present application. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0009] Next, the technical solutions in the embodiments of the present application will be clearly described with reference to the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments are some, but not all, of the embodiments of the present application. All other embodiments obtained by those of ordinary skill in the art based on the embodiments in the present application belong to the scope of protection of the present application.

[0010] The terms "first", "second", etc. in the description and claims of this application are used to distinguish similar objects, rather than to describe a specific order or sequence. It should be understood that the data used in this way can be interchanged under appropriate circumstances, so that the embodiments of this application can be implemented in an order other than those illustrated or described herein, and the objects distinguished by "first", "second", etc. are usually of the same type, and the number of objects is not limited. For example, the first object can be one or more. In addition, "and / or" in the description and claims means at least one of the connected objects, and the character " / ", generally represents an "or" relationship between the associated objects before and after.

[0011] The following will combine the accompanying drawings to detail the image sensor pixel unit provided by the embodiments of this application through specific embodiments and their application scenarios.

[0012] As Figures 1 - 3 shown, the image sensor pixel unit provided by the embodiments of this application includes: at least one image sub-pixel 100, and each image sub-pixel 100 includes a photodiode layer 110 and a microlens unit 120; The photodiode layer 110 of each image sub-pixel 100 includes 2K first photodiodes 111 and 4K second photodiodes 112, where K is a positive integer power of 2. The long side dimension of the first photodiode 111 is twice the size of the second photodiode 112, and the short side dimension of the first photodiode 111 is equal to the size of the second photodiode 112; The microlens unit 120 of each image sub-pixel 100 includes K first microlenses ML1 and 4K second microlenses ML2. Each first microlens ML1 covers two adjacent first photodiodes 111, each second microlens ML2 correspondingly covers the second photodiode 112, and between every two adjacent first microlenses ML1, there are second microlenses ML2 arranged in an array.

[0013] Among them, the image sensor pixel unit includes at least one image sub-pixel 100, and the image sub-pixel 100 includes, but is not limited to, red sub-pixels, green sub-pixels, and blue sub-pixels. For the design size of the image sensor pixel unit, no specific limitation is made here.

[0014] In an exemplary embodiment, as Figure 1As shown, the image sensor pixel unit includes a red sub-pixel R, a green sub-pixel G, and a blue sub-pixel B. Taking K = 2 as an example, each image sub-pixel includes a large pixel structure in which two first photodiodes 111 share a first microlens ML1, and a small pixel structure composed of four second photodiodes 112 and a second microlens ML2. Among them, the size of the first microlens ML1 is 4 times that of the second microlens ML2. Four second microlenses ML2 are arranged between every two adjacent first microlenses ML1, and the four second microlenses ML2 are arranged in an array. As shown in the figure, the second microlenses ML2 are all around the first microlens ML1. In this way, better image quality and phase information with uniform image plane can be obtained; the top view of the first photodiode 111 is rectangular, the top view of the second photodiode 112 is square, the short side size of the first photodiode 111 is equal to the side length of the second photodiode 112, and the long side size of the first photodiode 111 is 2 times the side length of the second photodiode 112. As Figure 2 and Figure 3 shown, the first microlens ML1 covers the two adjacent first photodiodes 111, and the second microlens ML2 covers the four second photodiodes 112 respectively.

[0015] In some embodiments, for the cases where K is other positive integer powers of 2, the arrangement is the same as the above arrangement of K = 2. As Figure 4 shown, when K = 2 3 , the photodiode layer of the image sub-pixel 100 includes 16 first photodiodes and 32 second photodiodes; the microlens unit 120 of the image sub-pixel 100 includes 8 first microlenses ML1 and 32 second microlenses ML2. Each first microlens ML1 covers two adjacent first photodiodes 111, each second microlens ML2 correspondingly covers the second photodiode 112, and the second microlenses ML2 arranged in an array are arranged between every two adjacent first microlenses ML1.

[0016] In this way, in a high dynamic range scenario, overexposure overflow in the highlight area can be avoided through the large pixel structure, higher resolution can be achieved with the same area through the small pixel structure, and when the large pixel structure and the small pixel structure are combined and output, a better signal-to-noise ratio can be obtained in the low light scenario, realizing the improvement of the low light image quality.

[0017] In some embodiments, the first photodiode 111 includes photodiodes PD1 and PD2, and the second photodiode 212 includes photodiode PD3. Among them, the photodiodes PD1, PD2, and PD3 have the same size, and their shapes can be circular, rectangular, annular, etc. The shape of the photodiode is not specifically limited herein.

[0018] In some embodiments, the designed number of layers of the microlens unit 120 can be one layer or multiple layers. The designed number of layers of the microlens unit 120 is not specifically limited herein.

[0019] In some embodiments, two adjacent first photodiodes 111 covered by each first microlens ML1 are symmetrically distributed in a preset angular direction.

[0020] In an exemplary embodiment, as Figure 1 shown, two first photodiodes 211 are symmetrically distributed in the vertical direction, and horizontal phase information HP can be obtained. Two first photodiodes 211 are symmetrically distributed in the horizontal direction, and vertical phase information VP can be obtained.

[0021] In this way, each color channel supports the output of phase information in two directions and regularly covers the entire frame of the image sensor. The image sensor pixel unit provided by the embodiments of the present application can cover more application scenarios. For example, scenarios where there is less or no green wavelength light.

[0022] Among them, as Figures 5a - 5c shown, the image sensor pixel unit can also only obtain horizontal phase information, or only obtain vertical phase information, or can also be other direction phase information. For the pixel unit that obtains phase information, the setting of its phase direction is not specifically limited herein.

[0023] In some embodiments, each image sub-pixel 100 further includes a filter layer (Color Filter, CF) 130. The filter layer 130 is disposed between the photodiode layer 110 and the microlens unit 120. The filter layers corresponding to at least one image sub-pixel are arranged based on the Bayer pattern. Among them, the Bayer pattern is a grid arrangement composed of three color filters of red R, green G, and blue B. Its arrangement is: there is a red, green, or blue filter below each pixel point, and usually there is a green filter between every two adjacent pixel points.

[0024] In an exemplary embodiment, the filter layer adopts a square design, and the red, green, and blue channels are arranged using the Bayer pattern. Among them, the filter layer blocking red light, green light, and blue light is only an example, and the blocking wavelength band of the filter layer is not specifically limited herein.

[0025] In some embodiments, a first planarization layer 141 is disposed on the filtering layer 130, and the microlens unit 120 is disposed on the filtering layer 130 through the first planarization layer 141.

[0026] In the embodiments of the present application, by disposing the first planarization layer 141 on the filtering layer 130, the first planarization layer 141 covers the entire filtering layer 130, so that it is convenient to manufacture the microlens unit in the production process.

[0027] In some embodiments, a second planarization layer 142 is disposed on the first planarization layer 141, and the second microlens ML2 is disposed on the first planarization layer 141 through the second planarization layer 242.

[0028] Wherein, the first planarization layer 141 and the second planarization layer 142 are relatively uniform surface layers for providing stable optical performance, thereby ensuring image consistency.

[0029] In this way, when light enters the microlens unit obliquely, since the first microlens ML1 is higher than the second microlens ML2 in the vertical direction, the light entering the second microlens ML2 is blocked. Therefore, by disposing the second planarization layer 142 below the second microlens ML2, light occlusion can be avoided, the shooting effect can be improved, and it is convenient to manufacture the second microlens ML2 in the production process.

[0030] In some embodiments, each image sub-pixel 100 further includes a metal layer 150 and a silicon substrate layer 160. The metal layer 150 is located below the photodiode layer 110 and is used to transmit the electrical signals output by the respective photodiodes in the photodiode layer 110 to the silicon substrate layer 160. The silicon substrate layer 160 is used to transmit and process the electrical signals to obtain image data.

[0031] In some embodiments, a pixel unit circuit is further connected to the electrical signal output terminals of the respective photodiodes in the photodiode layer 110. The pixel unit circuit includes a switching transistor TG and a parasitic capacitor FD, and the electrical signals converted by the respective photodiodes in the photodiode layer are stored in the parasitic capacitor FD by controlling the on / off of the switching transistor TG.

[0032] In an exemplary embodiment, each of the photodiodes in the photodiode layer 110 may use a single parasitic capacitor FD or share a single parasitic capacitor FD. As shown in FIG. 5, the respective photodiodes in the photodiode layer 110 share a single parasitic capacitor FD to simplify the circuit design. Among them, the full well capacity of PD1 is equal to the full well capacity of PD2, the full well capacity of PD3 has no relation with the full well capacity of PD1 or PD2, and the larger the technical index of the full well capacity of a single pixel, the better.

[0033] In some embodiments, the pixel unit circuit further includes an electrical signal output unit, which is configured to transfer the electrical signal stored in the parasitic capacitance to a bus and output the electrical signal through the bus.

[0034] In an exemplary embodiment, as Figure 6 shown, the electrical signal output unit includes a reset switch (Reset trgate, RG), a source follower (Source follower transistor, SF), and a selection switch (select transistor, SEL); after each photodiode obtains a light signal, according to the photoelectric conversion principle, the light signal is converted into an electrical signal, then the TG is controlled to be turned on to transfer the electrical signal to the FD, after the source follower of the SF, the SEL switch is controlled to be turned on to transfer the electrical signal to the bus, and finally the electrical signal is output.

[0035] As Figure 7 shown, the image sensor provided by the embodiment of the present application includes M rows and N columns of the above-mentioned image sensor pixel units, where M and N are integer multiples of 4, and both M and N are greater than or equal to 8.

[0036] In the embodiment of the present application, the light passes through the microlens unit 120 and converges, passes through the planarization layer and then enters the filtering layer 130 to filter out the light wavelengths that the image sub-pixels 100 do not need to record, and then enters the photodiode layer 110. The photoelectric conversion is completed via the photodiode layer 110, and the electrical signal is output through the metal layer 150, so as to obtain the image data recorded by the image sensor and complete the shooting. Among them, the planarization layer includes the above-mentioned first planarization layer 141 and second planarization layer 142.

[0037] The embodiment of the present application also provides an electronic device, including the above-mentioned image sensor.

[0038] Among them, the above-mentioned electronic device can be a smart phone, a tablet computer, a digital camera, a camera, a medical imaging device, a virtual reality device, a spectral analyzer, a scanner and other devices.

[0039] It should be noted that in this text, the term "including", "comprising" or any other variant thereof is intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements not only includes those elements, but also includes other elements not expressly listed, or also includes elements inherent to such process, method, article or device. Without further limitation, an element defined by the statement "including one..." does not exclude the existence of additional identical elements in the process, method, article or device including such element. In addition, it should be pointed out that the scope of the methods and devices in the embodiments of the present application is not limited to performing functions in the order shown or discussed, but may also include performing functions in a substantially simultaneous manner or in a reverse order according to the functions involved. For example, the described methods may be performed in an order different from that described, and various steps may be added, omitted, or combined. Additionally, features described with reference to certain examples may be combined in other examples.

[0040] Through the description of the above embodiments, those skilled in the art can clearly understand that the above-described example methods can be implemented by means of software plus a necessary general hardware platform. Of course, they can also be implemented by hardware, but in many cases the former is a better implementation. Based on this understanding, the technical solution of the present application, in essence, or the part that contributes to the prior art can be embodied in the form of a computer software product. This computer software product is stored in a storage medium (such as ROM / RAM, magnetic disk, optical disk) and includes several instructions for causing a terminal (which may be a mobile phone, computer, server, or network device, etc.) to execute the methods described in the various embodiments of the present application.

[0041] The embodiments of the present application have been described above in conjunction with the accompanying drawings. However, the present application is not limited to the above specific embodiments. The above specific embodiments are merely illustrative and not restrictive. Under the inspiration of the present application, those of ordinary skill in the art can also make many forms without departing from the purpose of the present application and the scope protected by the claims, and all of them fall within the protection scope of the present application.

Claims

1. An image sensor pixel unit, characterized in that, it includes: At least one image sub-pixel (100), each of the image sub-pixels (100) includes a photodiode layer (110) and a microlens unit (120); The photodiode layer (110) of each of the image sub-pixels (100) includes 2K first photodiodes (111) and 4K second photodiodes (112), where K is a positive integer power of 2, the long side dimension of the first photodiode (111) is twice the dimension of the second photodiode (112), and the short side dimension of the first photodiode (111) is equal to the dimension of the second photodiode (112); The microlens unit (120) of each of the image sub-pixels (100) includes K first microlenses (ML1) and 4K second microlenses (ML2). Each of the first microlenses (ML1) covers two adjacent first photodiodes (111), and each of the second microlenses (ML2) correspondingly covers the second photodiode (112). Between every two adjacent first microlenses (ML1), there are second microlenses (ML2) arranged in an array.

2. The image sensor pixel unit according to claim 1, characterized in that, Two adjacent first photodiodes (111) covered by each of the first microlenses (ML1) are symmetrically distributed in a preset angular direction.

3. The image sensor pixel unit according to claim 1, characterized in that, Each of the image sub-pixels further includes a filter layer (130), the filter layer (130) is disposed between the photodiode layer (110) and the microlens unit (120), and the filter layers corresponding to the at least one image sub-pixel are arranged based on a Bayer pattern.

4. The image sensor pixel unit according to claim 3, characterized in that, A first planarization layer (141) is disposed on the filter layer (130), and the microlens unit (120) is disposed on the filter layer (130) through the first planarization layer (141).

5. The image sensor pixel unit according to claim 4, characterized in that, A second planarization layer (142) is disposed on the first planarization layer (141), and the second microlens (ML2) is disposed on the first planarization layer (141) through the second planarization layer (142).

6. The image sensor pixel unit according to claim 1, characterized in that, Each of the image sub-pixels (100) further includes a metal layer (150) and a silicon substrate layer (160), the metal layer (150) is located below the photodiode layer (110) and is used to transmit the electrical signals output by the respective photodiodes in the photodiode layer (110) to the silicon substrate layer (160), and the silicon substrate layer (160) is used to transmit and process the electrical signals to obtain image data.

7. The image sensor pixel unit according to claim 1, characterized in that, The electrical signal output terminals of the respective photodiodes in the photodiode layer (110) are further connected to a pixel unit circuit; the pixel unit circuit includes a transfer switch (TG) and a parasitic capacitor (FD), and the electrical signals converted by the respective photodiodes in the photodiode layer are stored in the parasitic capacitor (FD) by controlling the on / off of the transfer switch (TG).

8. The image sensor pixel unit according to claim 7, characterized in that, The pixel unit circuit further includes an electrical signal output unit, which is configured to transfer the electrical signal stored in the parasitic capacitance to a bus, and output the electrical signal through the bus.

9. An image sensor, characterized in that it includes M rows and N columns of image sensor pixel units as described in any one of claims 1 to 8, wherein M and N are integer multiples of 4, and both M and N are greater than or equal to 8.

10. An electronic device, characterized in that it includes the image sensor as described in claim 9.

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