Image sensors, camera modules and imaging equipment

Abstract

This disclosure relates to an image sensor, camera module, and imaging device; the image sensor includes: a pixel array layer including a plurality of sub-pixels arranged in an array, the pixel array layer including a plurality of pixel groups, each pixel group including a first number of sub-pixels, the first number of sub-pixels being used to sense the same color, the first number being greater than 1; a first lens layer disposed on the light-incident side of the pixel array layer, including a plurality of first lenses disposed one-to-one with the plurality of sub-pixels; a second lens layer disposed on the side of the first lens layer away from the pixel array layer, including a plurality of second lenses disposed one-to-one with the plurality of pixel groups; each second lens being used to disperse incident light onto the first number of first lenses corresponding to each second lens; each first lens being used to focus light onto the sub-pixel corresponding to the first lens.

Description

Technical Field

[0001] This disclosure relates to the field of camera technology, and more particularly to image sensors, camera modules and imaging devices. Background Technology

[0002] Image sensors are semiconductor devices that convert light signals into electrical signals and are widely used in electronic devices such as mobile phones. As users' demands for image resolution continue to increase, the size of subpixels in image sensors is constantly shrinking. However, limited by chip size, the miniaturization of subpixel pitch leads to a degradation in optical performance.

[0003] To improve the sensitivity of image sensors, related technologies have developed filter arrays with 2*2 OCLs (on-chip lenses). For a pixel with a 2*2 filter array, the pixel has four photodiodes under stacked microlenses and color filters. The focal point of the 2×2 OCL is located between the pixels, rather than focusing the incident light at the center of each photodiode as in traditional microlenses. This results in reduced photoelectric conversion efficiency in some sub-pixels, thus affecting the imaging performance of the image sensor. Utility Model Content

[0004] To overcome the problems existing in related technologies, this disclosure provides an image sensor, a camera module, and an imaging device.

[0005] According to a first aspect of the present disclosure, an image sensor is provided, comprising: a pixel array layer including a plurality of sub-pixels arranged in an array, the pixel array layer including a plurality of pixel groups, each pixel group including a first number of sub-pixels, the first number of sub-pixels being used to sense the same color, the first number being greater than 1; a first lens layer disposed on the light-incident side of the pixel array layer, including a plurality of first lenses disposed in one-to-one correspondence with the plurality of sub-pixels; a second lens layer disposed on the side of the first lens layer away from the pixel array layer, including a plurality of second lenses disposed in one-to-one correspondence with the plurality of pixel groups; each second lens being used to disperse incident light onto the first number of first lenses corresponding to each second lens; and each first lens being used to focus light onto a sub-pixel corresponding to the first lens.

[0006] In some embodiments, the side of the first lens away from the pixel array layer is a first convex surface, and the side of the first lens close to the pixel array layer is a plane; the side of the second lens away from the pixel array layer is a second convex surface, and the side of the second lens close to the pixel array layer includes a first number of concave surfaces, the shape of which matches the shape of the first convex surface.

[0007] In some embodiments, the shape of the first convex surface and / or the second convex surface is one of the following: sphere, parabola, ellipsoid, or freeform surface.

[0008] In some embodiments, the refractive index of the first lens is greater than the refractive index of the second lens.

[0009] In some embodiments, the refractive index of the first lens is in the range of 1.7 to 2.1, and the refractive index of the second lens is in the range of 1.4 to 1.65.

[0010] In some embodiments, the geometric center of the first lens has a first offset from the geometric center of the corresponding sub-pixel, and the geometric center of the second lens has a second offset from the geometric center of the corresponding pixel group.

[0011] In some embodiments, a deep trench isolation trench (DTI) is provided between adjacent subpixels.

[0012] In some embodiments, the image sensor further includes: a color filter layer disposed between the pixel array layer and the first lens layer, comprising a filter unit array having a plurality of filter units, wherein the plurality of filter units are configured in one-to-one correspondence with the plurality of pixel groups; the plurality of filter units include a plurality of red filter units, a plurality of green filter units and a plurality of blue filter units arranged in a Bayer array.

[0013] According to a second aspect of the present disclosure, a camera module is provided, including a lens assembly and an image sensor as described in the first aspect; the lens assembly includes at least one lens, the at least one lens including a light emitting end, the light emitting end being disposed opposite to the light incident surface of the image sensor.

[0014] According to a third aspect of the present disclosure, an imaging device is provided, including an image sensor as described in the first aspect; or a camera module as described in the second aspect.

[0015] The technical solutions provided by the embodiments of this disclosure may include the following beneficial effects:

[0016] In the technical solution disclosed herein, the second lens layer and the first lens layer together constitute a dual-lens system. The two work together to control the incident light. The second lens layer converges and adjusts the angle of the light, dispersing the light to multiple first lenses. The first lens layer then performs more precise focusing, accurately focusing the light onto the corresponding sub-pixels, ensuring that each sub-pixel can efficiently sense light, greatly improving the light-sensing efficiency of the sub-pixels. This enables the image sensor to obtain clearer images with more accurate color reproduction and richer details.

[0017] It should be understood that the above general description and the following detailed description are exemplary and explanatory only, and are not intended to limit this disclosure. Attached Figure Description

[0018] The accompanying drawings, which are incorporated in and form a part of this specification, illustrate embodiments consistent with this disclosure and, together with the description, serve to explain the principles of this disclosure.

[0019] Figure 1 This is a schematic structural diagram of an image sensor in related technologies;

[0020] Figure 2 yes Figure 1 A partial cross-sectional view of the image sensor in the image sensor;

[0021] Figure 3 This is a schematic structural diagram of another image sensor in related technologies;

[0022] Figure 4 yes Figure 3 A partial cross-sectional view of the image sensor in the image sensor;

[0023] Figure 5 This is a schematic structural diagram of the image sensor provided in the embodiments of this disclosure;

[0024] Figure 6 yes Figure 5 A partial structural cross-sectional view of the image sensor in the image sensor;

[0025] Figure 7 This is a schematic diagram of a pixel array provided in this disclosure;

[0026] Figure 8 This is a schematic diagram of another pixel array provided in this disclosure;

[0027] Figure 9 The results are finite-difference time-domain (FDTD) simulations of the difference in refractive index between the first and second lenses and the light transmittance.

[0028] Figure 10 yes Figure 6 FDTD simulation results of the local structure described above;

[0029] Figure 11 These are simulation results of the photoelectronic efficiency of different color subpixels after the lens layer is shifted in the related technology.

[0030] Figure 12 The simulation results show the photoelectronic efficiency of different color subpixels after the displacement adjustment of the first lens layer and the second lens layer in the technical solution disclosed herein.

[0031] Figure 13This is a schematic diagram of the automatic focus detection line of the related technology solution;

[0032] Figure 14 This is a schematic diagram of the autofocus detection line of the technical solution disclosed herein;

[0033] Figure 15 These are simulation results of the sensitivity of subpixels of different sizes;

[0034] Figure 16 This is a schematic structural diagram of the camera module provided in the embodiments of this disclosure;

[0035] Figure 17 This is a schematic structural diagram of the imaging device provided in the embodiments of this disclosure. Detailed Implementation

[0036] To make the objectives, technical solutions, and advantages of this disclosure clearer, the disclosure will be further described in detail below with reference to the accompanying drawings. The described embodiments should not be regarded as limitations on this disclosure. All other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this disclosure.

[0037] In the following description, references are made to “some embodiments,” which describe a subset of all possible embodiments. However, it is understood that “some embodiments” may be the same subset or different subsets of all possible embodiments and may be combined with each other without conflict.

[0038] In the following description, the terms “first, second, third” are used merely to distinguish similar objects and do not represent a specific ordering of objects. It is understood that “first, second, third” may be interchanged in a specific order or sequence where permitted, so that the embodiments of this disclosure described herein can be implemented in an order other than that illustrated or described herein.

[0039] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure belongs. The terminology used herein is for the purpose of describing embodiments of this disclosure only and is not intended to be limiting of this disclosure.

[0040] This disclosure provides an image sensor, a camera module, and an electronic device. Before introducing the embodiments of this disclosure, a detailed example of the image sensor in the related art and its existing problems will be given.

[0041] An image sensor is a semiconductor device that converts light signals into electrical signals. With the development of electronic technology, image sensors are widely used in various types of electronic devices such as mobile phones, tablets, digital cameras, video recorders, personal communication systems, game consoles, webcams, and medical miniature cameras. High-performance image sensors can provide a better shooting experience.

[0042] Figure 1 This is a schematic structural diagram of an image sensor in related technologies. Figure 2 yes Figure 1 A partial sectional view. See also... Figure 1 and Figure 2 The image sensor 100 includes, from bottom to top, a pixel array 110, a filter 120, and a microlens layer 130.

[0043] The pixel array 110 includes multiple photodiodes 111 arranged in an array. When light shines on the photodiodes 111, the photon energy is absorbed, triggering the photoelectric effect and generating electron-hole pairs, which in turn convert the light signal into an electrical signal.

[0044] The filter 120 is disposed on the light-incident surface of the pixel array 110. The filter includes a color filter array (CFA) corresponding to the pixel array 110. The filter 120 includes a plurality of filter units 121, which correspond one-to-one with the plurality of photodiodes 111 in the pixel array 110.

[0045] The function of each filter unit 121 is to allow light of a specific color to pass through, so that it reaches the corresponding photodiode 111, thereby realizing the perception of light of different colors.

[0046] The multiple filter units 121 in filter 120 can be arranged in various ways. Among them, the Bayer array structure is a common arrangement, where the filter consists of filter units of three colors: red (R), green (G), and blue (B). Considering the human eye's greater sensitivity to green, in the Bayer array structure, the number of green filters is twice the number of red and blue filters. For example, Figure 1 As shown in rectangular region 140, within a 2*2 rectangular area, four filter units are arranged in the RGGB manner.

[0047] Furthermore, depending on the different needs in color reproduction and light capture, the arrangement of multiple filter units 121 can also include Foveon X3 array, RGBW filter array, RYYB filter array, and CMY filter array.

[0048] The microlens layer 130 includes a plurality of tiny lenses 131, each lens 131 corresponding to a photodiode 111 in the pixel array 110. The main function of the lens 131 is to focus incident light onto the corresponding photodiode 111 to improve the photosensitivity and imaging quality of the image sensor.

[0049] Taking image sensors used in mobile terminal devices such as smartphones as an example, the compact internal space of a smartphone, which needs to accommodate various components, severely limits the available space for image sensors. Furthermore, to meet users' demands for high-resolution photos, pixel density needs to be further increased, requiring the integration of more photodiodes within a limited chip area.

[0050] Feasible ways to increase pixel density include reducing the area of ​​individual pixels and / or further reducing the spacing between adjacent pixels. However, reducing the area of ​​individual pixels and the spacing between adjacent pixels can lead to the following problems:

[0051] First, a smaller pixel size means a smaller area for each pixel to receive light, resulting in a decrease in the number of photons that can be captured, thus reducing light sensitivity. Furthermore, smaller pixel sizes make it difficult to accurately capture and record light information simultaneously in both strong and low-light environments. In high-contrast scenes, overexposure in bright areas and underexposure in dark areas can easily occur, leading to a narrower dynamic range and loss of image detail.

[0052] Secondly, the narrower distance between adjacent pixels makes it easier for light to diffuse from one pixel to its neighboring pixels, causing crosstalk. This leads to a decrease in image sharpness, blurring of color edges, and consequently affects the imaging effect.

[0053] Furthermore, at submicron pixel sizes, the diffraction effect of light causes the microlens to have a weak focusing ability for incident light, resulting in light loss.

[0054] To address the aforementioned issues, a solution based on a quad Bayer array has been provided in the relevant technologies. Figure 3 This is a schematic diagram of the image sensor structure. Figure 4 yes Figure 3 A partial sectional view. See also... Figure 3 and Figure 4 The image sensor 300 includes a pixel array 310, a filter 320, and a microlens layer 330.

[0055] The pixel array 310 includes multiple pixel groups 311 arranged in an array. Each pixel group includes four sub-pixels 3111. These four sub-pixels 3111 are used to sense light of the same color. These four sub-pixels 3111 can be combined into a large pixel, thereby solving the problem of excessively small pixel area in related technologies to a certain extent.

[0056] The filter 320 includes multiple filter units 321 arranged in an array, each of which corresponds one-to-one with a plurality of pixel groups 331 in the pixel array. The multiple filter units 321 include a red filter unit 3211, a green filter unit 3212, and a blue filter unit 3212 arranged in a Bayer array structure, with each color filter unit covering four sub-pixels.

[0057] The microlens layer 330 includes multiple microlenses 331 that are configured one-to-one with multiple pixel groups 311. That is, four adjacent sub-pixels of the same color share a microlens. This method is also called 2*2 on-chip lens (OCL).

[0058] Compared to Figure 1 The technology, which assigns a microlens to each subpixel, utilizes a larger microlens shared by four subpixels in the 2*2 OCL technology, resulting in higher quantum efficiency. This subpixel-to-microlens approach also allows the sensor to capture more photons in low-light conditions, effectively reducing noise and improving image clarity.

[0059] exist Figure 1 In the related technologies shown, in order to achieve phase focusing, it is necessary to set up an additional phase difference detection pixel. The phase difference detection pixel usually includes two sub-pixels arranged in the horizontal direction. The two sub-pixels share a microlens. Phase focusing can be performed by using the image perspective shift between the two sub-pixels. The aforementioned phase difference detection pixel does not have a photo-taking function, so multiple phase difference detection pixels can only be dispersed and set in different positions.

[0060] And in Figure 3 In the technical solution shown, since four adjacent subpixels of the same color share a lens, phase focusing can be performed by utilizing the image perspective shift between subpixels in the same pixel group; and since the entire pixel array adopts the same arrangement, phase focusing can be achieved at almost any position.

[0061] Furthermore, traditional phase difference detection pixels are typically placed horizontally, resulting in lower phase difference detection capability for horizontally aligned objects. The 2×2OCL technology, however, combines horizontal and vertical phase difference detection, enabling uniform phase difference detection across the entire sensor surface. This allows for more effective detection of phase differences for horizontal, vertical, and oblique objects, improving focusing speed and accuracy. It is particularly effective when shooting moving objects, allowing for faster and more precise focus locking.

[0062] While the aforementioned technologies can improve imaging quality and focusing performance to some extent, for pixels with a 2x2 filter array, the focal point of the microlens corresponding to each pixel group is located between the four sub-pixels of that pixel group, and cannot be evenly distributed to each sub-pixel. This leads to a decrease in the photoelectric conversion efficiency of some sub-pixels, which in turn affects the imaging effect of the image sensor.

[0063] In view of the above problems, this disclosure provides an image sensor, a camera module, and an imaging device, aiming to improve the performance of the image sensor and improve the imaging quality.

[0064] The technical solution of this disclosure will now be described in detail with reference to the accompanying drawings.

[0065] The image sensor in this disclosure embodiment is used to convert optical images into electrical signals. The image sensor may be, for example, a complementary metal-oxide-semiconductor (CMOS) or a charge-coupled device (CCD).

[0066] Figure 5 This is a schematic structural diagram of an image sensor provided in an embodiment of this disclosure. Figure 6 for Figure 5 A schematic diagram of a local structure. (For example...) Figure 5 and Figure 6 As shown, the image sensor 500 includes a pixel array layer 510, a first lens layer 520, and a second lens layer 530.

[0067] The pixel array layer 510 includes a plurality of sub-pixels 511 arranged in an array, which are used to receive incident light and generate signal charges proportional to the intensity of the incident light. For example, each sub-pixel 511 may include a photodiode for sensing light and logic circuitry for processing the detected light intensity to generate an electrical signal.

[0068] The aforementioned 511 subpixel array arrangement can be as follows: Figure 5The rectangular array shown is arranged as follows. Multiple sub-pixels 511 are arranged in parallel rows along the horizontal direction (first direction) and in parallel columns along the vertical direction (second direction). The pixel rows and pixel columns are perpendicular to each other, forming a sub-pixel matrix array, and the spacing between adjacent sub-pixels in the same row or column is equal.

[0069] It should be noted that, besides the rectangular array mentioned above, multiple sub-pixels can also be arranged in a non-rectangular array. For example, multiple sub-pixels can be arranged as follows: Figure 7 The honeycomb array shown or as Figure 8 The arrangement is as shown in the triangular array.

[0070] The aforementioned pixel array layer 510 includes multiple pixel groups 512. Each pixel group 512 includes a first number of sub-pixels 511, the first number being greater than 1, and the multiple sub-pixels 512 in each pixel group 511 are used to sense light of the same color.

[0071] For example, in Figure 5 In the pixel array layer 510 shown, the first number of sub-pixels can be Figure 5 The first number of sub-pixels can be composed of four sub-pixels within a 2*2 rectangular area, which together form a pixel group 512; or, the first number of sub-pixels can be two adjacent sub-pixels, which together form a pixel group; or, the first number of sub-pixels can be nine sub-pixels within a 3*3 rectangular unit, which together form the pixel group shown in the figure.

[0072] by Figure 7 Taking the honeycomb array of pixels as an example, the first number of sub-pixels can be two adjacent sub-pixels that form the pixel group 710 shown in the figure; or, the first number can be 7, that is, one sub-pixel and 6 sub-pixels adjacent to the sub-pixel together form a pixel group 720.

[0073] by Figure 8 Taking the triangular pixel array shown as an example, the first number of sub-pixels can be two adjacent sub-pixels, which constitute... Figure 8 The illustrated pixel group 810 is a diamond shape; or, the first number of subpixels may be four adjacent pixel groups forming the illustrated pixel group 820; or, the first number of subpixels may be six adjacent subpixels forming the illustrated pixel group 830.

[0074] It is understood that the present disclosure does not specifically limit the value of the first quantity, and it can be selected according to the arrangement of the pixel array.

[0075] Continue reading Figure 5 and Figure 6 The first lens layer 520 is disposed on the light-incident side of the pixel array layer 510, and includes a plurality of first lenses 521 disposed one-to-one with a plurality of sub-pixels 511. The first lens 521 is used to process the light before it enters the pixel array layer 510, so that the light can be focused onto the corresponding sub-pixel 511.

[0076] In some embodiments, a color separation filter layer 540 is further disposed between the first lens layer 520 and the pixel array layer 510, which is used to determine the color of the light sensed by each sub-pixel 511.

[0077] The color separation filter layer 540 includes an array of filter units 541. Each filter unit 541 is configured corresponding to a pixel group 512. For example, Figure 5 The pixel group 512 in the image corresponds to a green filter unit 5411, which allows green light to pass through. In this case, the pixel group 512 can also be called a green pixel group.

[0078] The multiple filter units 541 in the above-mentioned filter unit array include multiple green filter units 5411, multiple red filter units 5412 and multiple blue filter units 5413 arranged in a Bayer array. Each filter unit 541 corresponds to four sub-pixels 511 in a pixel group 512 in a rectangular array.

[0079] In some embodiments, the side of the first lens layer 520 near the pixel array layer 510 is configured to be attached to the side of the color filter layer 540 away from the pixel array layer 510.

[0080] In some embodiments, such as Figure 6 As shown, an anti-reflection layer 550 is also provided between the color filter layer 540 and the pixel array layer 510. This layer reduces light reflection at the cross-sections of the color filter layer 540 and the pixel array layer 510, thus reducing stray light interference. Without the anti-reflection layer, light would be reflected at the interface and then scattered inside the image sensor, forming stray light. This stray light would interfere with the pixel array's acquisition of normal light signals, reducing image contrast.

[0081] Furthermore, light reflection can cause interference on the surface of the image sensor, leading to artifacts such as moiré patterns. Anti-reflective layers can reduce the likelihood of interference and minimize the impact of moiré patterns on image quality.

[0082] In the embodiments of this disclosure, the convex surfaces of the plurality of first lenses 521 in the first lens layer 520 may be the same or different, and this disclosure does not limit this. For example, for sub-pixels that sense different colors of light, since the wavelengths of the incident light are different, in order to ensure the focusing efficiency of the first lens, the height and / or curvature of the convex surface of the first lens may be set to be different according to the different wavelengths of the different colors of light.

[0083] In this embodiment, the first lens 521 is made of a light-transmitting material, such as silicon oxide, silicon nitride, or photoresist. Silicon oxide has good optical transparency and low absorption and scattering in the visible light band, which ensures efficient light transmission, reduces light energy loss, and helps improve the sensitivity and imaging quality of the image sensor.

[0084] Based on the aforementioned materials, the first lens can be fabricated using methods such as thermal reflow, etching, or deposition combined with photolithography. Taking thermal reflow as an example, a layer of photoresist can be coated on the surface of the image sensor wafer after the front-end processes are completed. Using photolithography, the photoresist is exposed using a mask. Then, a development process removes the exposed or unexposed portions of the photoresist, forming a columnar photoresist pattern. The wafer with the columnar photoresist pattern is then heated above the glass transition temperature of the photoresist, causing it to melt. Under the influence of surface tension, the photoresist automatically shrinks back into a hemispherical microlens structure. By precisely controlling process parameters such as heating temperature and time, precise control of the shape and size of the first lens can be achieved.

[0085] The second lens layer 530 is disposed on the side of the first lens layer 520 away from the pixel array layer 510, that is, the outermost layer of the image sensor. The second lens layer 530 includes a plurality of second lenses 531, which are disposed one-to-one with a plurality of pixel groups 512 in the pixel array layer 510.

[0086] As described above, each pixel group 512 in the pixel array layer 510 includes a first number of sub-pixels 511, and each sub-pixel 511 corresponds to a first lens 521 in the first lens layer 520. Therefore, each second lens 531 in the second lens layer 530 is configured to correspond to the first number of first lenses 521 in the first lens layer 520.

[0087] For example, four sub-pixels within a 2x2 square area constitute a pixel group. Each of these four sub-pixels corresponds to a first lens 521. Above the four first lenses 521, a second lens 531 is disposed, and the second lens 531 at least covers a portion of the area of ​​the four first lenses 521. In this case, the second lens 531 can also be referred to as a 2x2 on-chip lens.

[0088] In this embodiment, the second lens layer 530 functions as follows: each second lens 531 in the second lens layer 530 can disperse incident light onto a plurality of first lenses 521 corresponding to that second lens 531. When light enters the image sensor 500 from the outside, it first passes through the second lens layer 530. The second lenses 531 can converge and adjust the angle of light from different directions. The outgoing light from the second lenses 531 is directed toward the plurality of first lenses 521 corresponding to them. The outgoing light from the second lenses 531 is the incident light from the first lenses 521, and the first lenses 521 then focus the incident light, thereby converging the light into each sub-pixel 512.

[0089] exist Figure 3 In the related technology where a microlens covers multiple subpixels, a large portion of the light refracted by the microlens 331 is focused on the middle of adjacent subpixels or the center of a 2*2 array composed of four subpixels, resulting in low light-sensing efficiency for each subpixel, thus affecting image quality.

[0090] In the technical solution disclosed herein, the second lens layer and the first lens layer together constitute a dual-lens system. The two work together to control the incident light. The second lens layer converges and adjusts the angle of the light, dispersing the light to multiple first lenses. The first lens layer then performs more precise focusing, accurately focusing the light onto the corresponding sub-pixels, ensuring that each sub-pixel can efficiently sense light, greatly improving the light-sensing efficiency of the sub-pixels. This enables the image sensor to obtain clearer images with more accurate color reproduction and richer details.

[0091] Continue reading Figure 5 and Figure 6 In some embodiments of this disclosure, the first lens 521 is provided with a first convex curved surface on the side away from the pixel array layer 510, and the side close to the pixel array layer 510 is a flat surface.

[0092] The first convex surface of the first lens 521 has the function of converging light, which can effectively focus the light dispersed from the second lens layer 530 onto the corresponding sub-pixel, thereby improving the light perception efficiency of the sub-pixel.

[0093] The side of the first lens 521 closest to the pixel array layer 510 is made flat, allowing the first lens layer 520 to be tightly attached to the light-incident surface of the pixel array layer 510. This avoids the impact of the air gap between the first lens layer 520 and the pixel array layer 510 on the incident light efficiency, reducing light reflection and refraction losses. Simultaneously, the flat lower surface increases the structural stability of the first lens 521. Furthermore, this structure simplifies the manufacturing process of the first lens layer 520 and reduces manufacturing costs.

[0094] The side of the second lens 531 away from the pixel array layer 510 is a second convex surface, and the side of the second lens 531 close to the pixel array layer 510 includes a first number of concave surfaces, the shape of which matches the first convex surface.

[0095] The first quantity mentioned above could be, for example, Figure 5 and Figure 6 The four shown in the figure, at this time the lower surface of the second lens 531 includes four concave surfaces, the shape of each concave surface matching the surface of the first lens of the four sub-pixel upper layer.

[0096] The aforementioned second convex surface can converge and guide incident light rays, so that light rays that strike the second convex surface from different angles can be converged, and the outgoing light from the second lens is emitted through the aforementioned first number of concave surfaces to the corresponding first lens.

[0097] The shape of the concave surface on the second lens is set to match the shape of the first convex surface of the first lens, so that each concave surface on the second lens 531 can be closely fitted to the corresponding first convex surface. Light experiences reflection and refraction losses at the interface between different media. By fitting the two surfaces together, making the air gap between them extremely small or even negligible, light emitted from the concave surface of the second lens 531 can smoothly enter the first lens 521, ultimately achieving sub-pixel density. This further improves the light sensitivity of the image sensor. Furthermore, this continuous stacking arrangement simplifies the fabrication process of the first lens layer 520 and the second lens layer 530. For example, the first lens layer 520 and the second lens layer 530 can be fabricated continuously using the same process.

[0098] In some embodiments, the shape of the first convex surface and / or the second convex surface is any one of a sphere, a parabola, an ellipsoid, or a freeform surface.

[0099] Spherical lenses are isotropic, meaning their optical properties are consistent in all directions, and their manufacturing process is mature, enabling large-scale production.

[0100] Parabolic lenses can accurately focus light rays parallel to the optical axis onto a single point, effectively eliminating spherical aberration. For applications requiring precise focusing, such as security or professional photography, parabolic microlenses can focus more light onto subpixels, improving image brightness and contrast.

[0101] An ellipsoidal microlens has two focal points. Light rays emitted from one focal point are reflected or refracted by the ellipsoid and converge at the other focal point. Utilizing this property, when applied to image sensors, it enables more flexible light control. For example, when applied to panoramic cameras, ellipsoidal microlenses can better collect light from different directions, thereby reducing vignetting at image edges and making the overall image brightness more uniform.

[0102] Freeform microlenses can be customized to meet different needs and achieve complex optical functions. For example, by optimizing the shape of the freeform surface, aberrations can be corrected, image quality and resolution can be improved.

[0103] Of course, the shapes of the first and second convex surfaces are not limited to the range mentioned above. In practical applications, the shapes of the first and second convex surfaces can be reasonably designed according to the application scenario and related design parameters of the image sensor.

[0104] It is also understood that the shapes of the first convex surface and the second convex surface can be the same or different, and the embodiments disclosed herein do not specifically limit this. For example, to improve the performance, the second convex surface can be set as an ellipsoid and the first convex surface can be set as a parabola; or, in order to reduce the design and manufacturing cost of the image sensor while meeting the performance requirements, both the first convex surface and the second convex surface can be set as spheres.

[0105] In some embodiments, the refractive index of the first lens 521 is greater than the refractive index of the second lens 531.

[0106] By setting the refractive indices of the first lens 521 and the second lens 531 to be different, when light enters the medium with a higher refractive index (first lens 521) from the medium with a lower refractive index (second lens 531), the light will be deflected towards the normal direction according to the law of refraction. The low-refractive-index covering microlens improves the light collection capability, while the high-refractive-index material improves the ability to focus the light onto the corresponding pixel photoelectric layer.

[0107] Figure 9 The results shown are the finite-difference time-domain (FDTD) simulation results of the difference in refractive index between the first lens 521 and the second lens 531 and the light transmittance. Here, light transmittance refers to the ratio of the light intensity received by the sub-pixel to the incident light intensity of the second lens 531.

[0108] Figure 9 The first curve 910 and the second curve 920 in the figure represent the light transmittance curves corresponding to different refractive index differences when the refractive index of the first lens 521 is greater than or less than the refractive index of the second lens 531. Figure 9It can be seen that the image sensor has higher light transmittance when the refractive index of the second lens 531 covering the outer layer is greater than that of the first lens 521 inside.

[0109] In some embodiments, the refractive index of the first lens 521 is in the range of 1.7 to 2.1, and the refractive index of the second lens 531 is in the range of 1.4 to 1.65.

[0110] Figure 10 These are the FDTD simulation results when the refractive indices of the first lens 521 and the second lens 531 are within the aforementioned range. It is understandable that... Figure 10 The case shown is that a second lens 531 covers four first lenses 521 within a 2*2 range.

[0111] exist Figure 10 In the simulation results, the darker the color, the stronger the light intensity. Figure 10 It can be seen that the second lens 531 can focus the incident light to the center of the two second lenses 531 below it, while the two first lenses 521 can refract the received light, so that most of the light can be focused to the center of the sub-pixel.

[0112] In technical solutions with 2x2 on-chip lenses, such as Figure 11 As shown, the lens layer needs to be shifted according to the green pixels, that is... Figure 11 The center of the lens shown is horizontally displaced from the centers of the four sub-pixels in the pixel group. This displacement adjustment ensures that the isolation grooves within the green pixel group evenly distribute the incident light among the four sub-pixels.

[0113] Figure 11 The bar chart below represents the photoelectric quantum efficiency (QE) of four subpixels in different color pixel groups. It can be seen that the four subpixels in the green pixel group have the same QE; that is, the four subpixels can absorb green light uniformly, and there is no difference in sensitivity among them. However, for the blue and red pixel groups, due to the differences in the refractive index of the filter and the incident light, the quantum efficiency of the four subpixels differs.

[0114] According to the simulation results above, in the technical solutions of related technologies, only the differences between subpixels within the green pixel group are relatively small. Therefore, when focusing using phase detection autofocus, it can only be done by using two green subpixels sharing the same lens, which will narrow the application scenarios of the image sensor.

[0115] More specifically, for example, in low-light conditions, relying solely on green pixels for phase detection autofocus can lead to insufficient signal strength, making it difficult for the autofocus system to accurately detect phase differences, resulting in slower autofocus speeds or even autofocus failure. Another example is when shooting scenes with multiple colors or low color contrast; relying solely on green pixels may not be able to fully and accurately capture the depth information of objects, leading to decreased focus accuracy.

[0116] In the embodiments disclosed herein, such as Figure 12 As shown, the geometric center of the first lens has a first offset from the geometric center of the corresponding sub-pixel, and the geometric center of the second lens has a second offset from the geometric center of the corresponding pixel group.

[0117] The above configuration enables the emitted light from the second lens to be evenly distributed onto the corresponding first number of first lenses; and the emitted light from the first lens can be focused onto the center of the corresponding sub-pixel.

[0118] It is understood that the first offset and the second offset mentioned above can be the same or different, and this disclosure does not specifically limit this. For example, in Figure 12 In the embodiment shown, the first offset is less than the second offset, which can optimize the optical path; or, the first offset can be equal to the second offset, in which case the geometric center of the second lens coincides with the geometric center of the corresponding first number of first lenses.

[0119] Figure 12 The distribution curves of quantum efficiency for subpixels of different colors are also shown. It can be seen that the quantum efficiencies of multiple subpixels in the red, blue, and green pixel groups are basically the same. In other words, by setting the first and second offsets mentioned above, the differences between multiple subpixels in each pixel group are eliminated, and a good balance is achieved among the multiple subpixels.

[0120] Figure 13 and 14 They are Figure 3 The diagram shows the related technologies and the schematic diagram of the autofocus detection line of the above-mentioned technical solutions provided in this disclosure. Figure 13 and Figure 14 The intersection of different colored pixel groups or focus detection lines in different directions is the autofocus (AF) intersection of the image sensor.

[0121] from Figure 13 The curves of the related technologies shown indicate that the intersection of the blue and green pixel groups is aligned to 0 degrees phase, while the intersection of the red pixel group has a -5° offset, which may cause color difference in the image and affect the focusing effect.

[0122] And in Figure 14 In the AF detection line of the technical solution of this disclosure, the horizontal coordinate of the intersection point of the red, blue and green pixel groups is 0, that is, the AF intersection points of all color pixels are aligned at this time, which makes the image sensor have better autofocus performance.

[0123] In some embodiments, a deep trench isolation trench (DTI) is further provided between adjacent subpixels in the pixel array layer 510 to prevent signal crosstalk between adjacent subpixels.

[0124] The aforementioned DTI structure can be formed through processes such as etching, and then the trenches are filled with insulating materials such as silicon dioxide. This structure can physically isolate adjacent subpixels, allowing resistive charges to diffuse and transfer between them. This DTI structure reduces signal crosstalk, enabling each subpixel to capture color information more accurately and reproduce the details of the photographed object.

[0125] Based on the above technical solutions, further improvements are made to the overlay microlens provided in the embodiments of this disclosure. Figure 3 2*2OCL and Figure 1 The sensitivity of traditional microlenses in the model was simulated at different sub-pixel sizes. For example... Figure 15 The simulation results show the sensitivity of subpixels with four different sizes: 1.2µm, 0.8µm, 0.64µm, and 0.56µm. It can be seen that the overlay microlens pixel is more sensitive than both 2*2 OCL and conventional microlens pixels, despite the progressively smaller pixel pitch. Furthermore, the sensitivity difference between overlay and conventional microlenses increases as the pixel pitch decreases. Compared to conventional microlenses and 2*2 OCL, overlay microlens pixels exhibit higher sensitivity regardless of pixel pitch. The sensitivity improvement rate is significant for smaller pixels. As pixel size decreases, sensitivity is limited by the diffraction limit.

[0126] like Figure 16 As shown, this disclosure also provides a camera module 1600, which includes a lens assembly 1610 and an image sensor 1620. The image sensor 1620 can be any of the image sensors described in the preceding embodiments.

[0127] The lens assembly 1610 in the camera module may include at least one lens, which includes a light emitting end that is disposed opposite to the light incident surface of the image sensor 1620.

[0128] When the lens assembly 1610 has multiple lenses, the multiple lenses can share the same image sensor 1620 to reduce the size and cost of the camera module.

[0129] This disclosure also provides an imaging device. Figure 17 This is a block diagram of an imaging device 1700 according to an exemplary embodiment. The imaging device 1700 of this disclosure may be a mobile phone, game console, wearable device, virtual reality device, personal digital assistant, laptop, tablet computer or TV terminal, etc. The imaging device has a camera 1701, which adopts the camera module 1500 of the aforementioned embodiment; or, the imaging device includes the image sensor 500 of the aforementioned embodiment.

[0130] The imaging device 1700 of this disclosure embodiment may include one or more of the following components: processing component 1702, memory 1704, power supply component 1706, multimedia component 1708, audio component 1710, input / output (I / O) interface 1712, sensor component 1714, and communication component 1716.

[0131] Processing component 1702 typically controls the overall operation of imaging device 1700, such as operations associated with display, telephone calls, data communication, camera operation, and recording operations. Processing component 1702 may include one or more processors 1720. Furthermore, processing component 1702 may include one or more modules to facilitate interaction between processing component 1702 and other components. For example, processing component 1702 may include a multimedia module to facilitate interaction between multimedia component 1708 and processing component 1702.

[0132] Memory 1704 is configured to store various types of data to support the operation of device 1700. Examples of this data include instructions for any application or method operating on imaging device 1700, contact data, phone book data, messages, pictures, videos, etc. Memory 1704 can be implemented by any type of volatile or non-volatile storage device or a combination thereof, such as static random access memory (SRAM), electrically erasable programmable read-only memory (EEPROM), erasable programmable read-only memory (EPROM), programmable read-only memory (PROM), read-only memory (ROM), magnetic storage, flash memory, magnetic disk, or optical disk.

[0133] The power supply assembly 1706 provides power to the various components of the imaging device 1700. The power supply assembly 1706 may include a power management system, one or more power supplies, and other components associated with generating, managing, and distributing power to the imaging device 1700.

[0134] Multimedia component 1708 includes a screen that provides an output interface between the imaging device 1700 and the user. In some embodiments, the screen may include a liquid crystal display (LCD) and a touch panel (TP). If the screen includes a touch panel, the screen may be implemented as a touchscreen to receive input signals from the user. The touch panel includes one or more touch sensors to sense touches, swipes, and gestures on the touch panel. The touch sensors may sense not only the boundaries of the touch or swipe action but also the duration and pressure associated with the touch or swipe operation. In some embodiments, multimedia component 1708 includes a front-facing camera and / or a rear-facing camera. When the device 1700 is in an operating mode, such as a shooting mode or a video mode, the front-facing camera and / or the rear-facing camera may receive external multimedia data. Each front-facing camera and rear-facing camera may be a fixed optical lens system or have focal length and optical zoom capabilities. The front-facing camera and / or the rear-facing camera employs the camera module described in the foregoing embodiments, or the front-facing camera and / or the rear-facing camera includes the image sensor described in the foregoing embodiments.

[0135] Audio component 1710 is configured to output and / or input audio signals. For example, audio component 1710 includes a microphone (MIC) configured to receive external audio signals when imaging device 1700 is in an operating mode, such as call mode, recording mode, and voice recognition mode. The received audio signals may be further stored in memory 1704 or transmitted via communication component 1716. In some embodiments, audio component 1710 also includes a speaker for outputting audio signals.

[0136] I / O interface 1712 provides an interface between processing component 1702 and peripheral interface modules, such as keyboards, click wheels, buttons, etc. These buttons may include, but are not limited to, home buttons, volume buttons, power buttons, and lock buttons.

[0137] Sensor assembly 1714 includes one or more sensors for providing status assessments of various aspects of imaging device 1700. For example, sensor assembly 1714 may detect the on / off state of device 1700, the relative positioning of components such as the display and keypad of imaging device 1700, changes in position of imaging device 1700 or a component of imaging device 1700, the presence or absence of user contact with imaging device 1700, the orientation or acceleration / deceleration of imaging device 1700, and temperature changes of imaging device 1700. Sensor assembly 1714 may include a proximity sensor configured to detect the presence of nearby objects without any physical contact. Sensor assembly 1714 may also include a light sensor, such as a CMOS or CCD image sensor, for use in imaging applications. In some embodiments, sensor assembly 1714 may also include an accelerometer, gyroscope, magnetometer, pressure sensor, or temperature sensor.

[0138] Communication component 1716 is configured to facilitate wired or wireless communication between imaging device 1700 and other devices. Imaging device 1700 can access wireless networks based on communication standards, such as Wi-Fi, 2G, or 3G, or combinations thereof. In one exemplary embodiment, communication component 1716 receives broadcast signals or broadcast-related information from an external broadcast management system via a broadcast channel. In one exemplary embodiment, communication component 1716 also includes a near-field communication (NFC) module to facilitate short-range communication. For example, the NFC module may be implemented based on radio frequency identification (RFID) technology, Infrared Data Association (IrDA) technology, ultra-wideband (UWB) technology, Bluetooth (BT) technology, and other technologies.

[0139] In an exemplary embodiment, the imaging device 1700 may be implemented by one or more application-specific integrated circuits (ASICs), digital signal processors (DSPs), digital signal processing devices (DSPDs), programmable logic devices (PLDs), field-programmable gate arrays (FPGAs), controllers, microcontrollers, microprocessors, or other electronic components.

[0140] In embodiments of this disclosure, the imaging device may be a mobile phone, game console, wearable device, virtual reality device, personal digital assistant, laptop, tablet computer, or television terminal, etc.

[0141] It is understood that in this disclosure, "multiple" refers to two or more, and other quantifiers are similar. "And / or" describes the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A alone, A and B simultaneously, and B alone. The character " / " generally indicates that the preceding and following related objects are in an "or" relationship. The singular forms "a," "the," and "the" are also intended to include the plural forms unless the context clearly indicates otherwise.

[0142] It is further understood that the terms "first," "second," etc., are used to describe various types of information, but this information should not be limited to these terms. These terms are only used to distinguish information of the same type from one another, and do not indicate a specific order or degree of importance. In fact, the expressions "first," "second," etc., are completely interchangeable. For example, without departing from the scope of this disclosure, first information can also be referred to as second information, and similarly, second information can also be referred to as first information.

[0143] It is further understood that the terms “center,” “longitudinal,” “lateral,” “front,” “rear,” “up,” “down,” “left,” “right,” “vertical,” “horizontal,” “top,” “bottom,” “inner,” and “outer,” etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this embodiment and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation.

[0144] It can be further understood that, unless otherwise specified, "connection" includes both direct connections where no other components exist between the two parties and indirect connections where other components exist between them.

[0145] Other embodiments of this disclosure will readily occur to those skilled in the art upon consideration of the specification and practice of the invention disclosed herein. This disclosure is intended to cover any variations, uses, or adaptations of this disclosure that follow the general principles of this disclosure and include common knowledge or customary techniques in the art not disclosed herein. The specification and examples are to be considered exemplary only, and the true scope and spirit of this disclosure are indicated by the claims.

[0146] It should be understood that this disclosure is not limited to the precise structures described above and shown in the accompanying drawings, and various modifications and changes can be made without departing from its scope. The scope of this disclosure is limited only by the appended claims.

Claims

1. An image sensor, characterized in that, include: A pixel array layer includes multiple sub-pixels arranged in an array. The pixel array layer includes multiple pixel groups, and each pixel group includes a first number of sub-pixels. The first number of sub-pixels is used to sense the same color, and the first number is greater than 1. The first lens layer is disposed on the light-incident side of the pixel array layer and includes a plurality of first lenses disposed in one-to-one correspondence with the plurality of sub-pixels; The second lens layer is disposed on the side of the first lens layer away from the pixel array layer, and includes a plurality of second lenses that are disposed one-to-one with the plurality of pixel groups; Each of the second lenses is used to disperse the incident light rays onto a first number of first lenses corresponding to each of the second lenses; Each of the first lenses is used to focus light onto a subpixel corresponding to the first lens.

2. The image sensor according to claim 1, characterized in that, The side of the first lens away from the pixel array layer is a first convex curved surface, and the side of the first lens close to the pixel array layer is a flat surface; The side of the second lens away from the pixel array layer is a second convex surface, and the side of the second lens close to the pixel array layer includes the first number of concave surfaces, the shape of which matches the shape of the first convex surface.

3. The image sensor according to claim 2, characterized in that, The shape of the first convex surface and / or the second convex surface is one of the following: sphere, parabola, ellipsoid, or freeform surface.

4. The image sensor according to any one of claims 1-3, characterized in that, The refractive index of the first lens is greater than that of the second lens.

5. The image sensor according to claim 4, characterized in that, The refractive index of the first lens is in the range of 1.7 to 2.1, and the refractive index of the second lens is in the range of 1.4 to 1.

65.

6. The image sensor according to any one of claims 1-3, characterized in that, The geometric center of the first lens is offset from the geometric center of the corresponding sub-pixel, and the geometric center of the second lens is offset from the geometric center of the corresponding pixel group.

7. The image sensor according to any one of claims 1-3, characterized in that, A deep trench isolation groove (DTI) is provided between adjacent subpixels.

8. The image sensor according to any one of claims 1-3, characterized in that, Also includes: A color separation filter layer is disposed between the pixel array layer and the first lens layer, including a filter unit array having multiple filter units, wherein the multiple filter units are disposed one-to-one with the multiple pixel groups; The plurality of filter units include a plurality of red filter units, a plurality of green filter units, and a plurality of blue filter units arranged in a Bayer array.

9. A camera module, characterized in that, Includes a lens assembly and an image sensor as claimed in any one of claims 1-8; The lens assembly includes at least one lens, the at least one lens including a light emitting end, the light emitting end being disposed opposite to the light incident surface of the image sensor.

10. An imaging device, characterized in that, include: The image sensor as described in any one of claims 1-8; Alternatively, the camera module as described in claim 9.

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