Image sensor and preparation method thereof, camera module and electronic equipment

Abstract

The embodiment of the invention provides an image sensor, a preparation method thereof, a camera module and electronic equipment, relates to the technical field of imaging, and is used for improving the image acquisition effect of the image sensor. The image sensor comprises a light absorption layer, the material of the light absorption layer comprises Si < x > Ge < 1-x-y > Sn < y > alloy, and x and y are both larger than 0 and smaller than 1. The light absorption layer comprises a plurality of absorption parts, and the component proportions of Si element, Ge element and Sn element in the plurality of absorption parts are different. The image sensor is applied to the electronic equipment so as to improve the performance of the electronic equipment.

Description

Technical Field

[0001] This application relates to the field of imaging technology, and in particular to an image sensor and its fabrication method, a camera module, and an electronic device. Background Technology

[0002] An image sensor is a device that converts optical images into electronic signals and is widely used in electronic devices such as digital cameras and mobile phones. In recent years, image sensors have evolved from charge-coupled device (CCD) image sensors to complementary metal-oxide-semiconductor (CMOS) image sensors, which are less expensive and have effectively improved noise levels.

[0003] Image sensors include a light absorption layer, which comprises multiple photoelectric conversion elements. These photoelectric conversion elements operate in different environments, but their photoelectric conversion capabilities are the same. This can lead to some photoelectric conversion elements failing to meet operational requirements, and in severe cases, can affect the image acquisition effect of the image sensor and the imaging quality of the electronic device. Summary of the Invention

[0004] This application provides an image sensor and its fabrication method, a camera module, and an electronic device, which can adjust the performance of different photoelectric conversion elements in the light absorption layer to improve the image acquisition effect of the image sensor and the imaging quality of the electronic device.

[0005] To achieve the above objectives, the embodiments of this application adopt the following technical solutions:

[0006] In a first aspect, an image sensor is provided, the image sensor including a light-absorbing layer, the material of the light-absorbing layer including Si. x Ge 1-x-y Sn y The alloy has x and y values ​​greater than 0 and less than 1. The light absorption layer includes multiple absorption sections, and the composition ratios of Si, Ge, and Sn elements in the multiple absorption sections are different.

[0007] In the image sensor provided in this application embodiment, the different composition ratios of Si, Ge, and Sn elements in multiple absorption sections can result in different quantum efficiencies for the multiple light absorption sections. This allows different light absorption sections to have different photoelectric conversion efficiencies for light of the same wavelength, or different light absorption sections to absorb light of different wavelength ranges. Consequently, the performance of the multiple light absorption sections varies, and the photoelectric conversion elements located in different light absorption sections can meet different operating requirements, thereby improving the image acquisition capability and image acquisition effect of the image sensor, as well as the imaging effect of the electronic device using the image sensor.

[0008] In one possible implementation of the first aspect, the multiple absorption portions are a red absorption portion, a blue absorption portion, a first green absorption portion, and a second green absorption portion. The composition ratios of Si, Ge, and Sn elements in the red absorption portion, the blue absorption portion, and the first green absorption portion are different; the composition ratios of Si, Ge, and Sn elements in the first green absorption portion and the second green absorption portion are the same.

[0009] In the image sensor provided in this application embodiment, the composition ratios of Si, Ge, and Sn elements in the red absorber, the first green absorber (or the second green absorber), and the blue absorber are different. This allows for optimization of the photoelectric conversion capability of different absorbers for different wavelengths based on the quantum efficiency of the absorbers for the corresponding wavelengths, thereby improving the performance of the photoelectric conversion elements in the different absorbers, enhancing the image acquisition capability of the image sensor, and ultimately improving the imaging quality of electronic devices using this image sensor.

[0010] Meanwhile, the different proportions of Si, Ge, and Sn elements in the red absorber, the first green absorber (or the second green absorber), and the blue absorber can adjust the wavelength of light that can be absorbed by different absorbers, improve the accuracy of other colors of light affecting the generation of electrical signals by the absorbers, further optimize the image acquisition capability of the image sensor, and improve the imaging quality of electronic devices using the image sensor.

[0011] In addition, the same composition ratio of Si, Ge and Sn elements in the first green absorbing part and the second green absorbing part allows the first green absorbing part and the second green absorbing part to be prepared simultaneously, which helps to simplify the preparation process of the light absorption layer, improve the preparation efficiency of the light absorption layer, and thus improve the preparation efficiency of the image sensor.

[0012] In another possible implementation of the first aspect, the light absorption layer includes a plurality of red absorption portions, a plurality of blue absorption portions, a plurality of first green absorption portions, and a plurality of second green absorption portions; the proportions of Si, Ge, and Sn elements in the plurality of red absorption portions are the same; and / or, the proportions of Si, Ge, and Sn elements in the plurality of blue absorption portions are the same; and / or, the proportions of Si, Ge, and Sn elements in the plurality of first green absorption portions are the same; and / or, the proportions of Si, Ge, and Sn elements in the plurality of second green absorption portions are the same.

[0013] When the proportions of Si, Ge, and Sn elements in multiple red absorbers are the same, multiple red absorbers in the light absorption layer can be prepared simultaneously, which simplifies the preparation process of the light absorption layer 201 and improves the preparation efficiency. Similarly, when the proportions of Si, Ge, and Sn elements in multiple first green absorbers are the same, multiple first green absorbers can be prepared simultaneously, which simplifies the preparation process of the light absorption layer and improves the preparation efficiency. Likewise, when the proportions of Si, Ge, and Sn elements in multiple second green absorbers are the same, multiple second green absorbers can be prepared simultaneously, which simplifies the preparation process of the light absorption layer and improves the preparation efficiency. Finally, when the proportions of Si, Ge, and Sn elements in multiple blue absorbers are the same, multiple blue absorbers in the light absorption layer can be prepared simultaneously, which simplifies the preparation process of the light absorption layer and improves the preparation efficiency.

[0014] In one possible implementation of the first aspect, the sum of the proportions of Ge and Sn elements in the red absorber is greater than the sum of the proportions of Ge and Sn elements in the blue absorber. And / or, the sum of the proportions of Ge and Sn elements in the red absorber is greater than the sum of the proportions of Ge and Sn elements in the first green absorber.

[0015] In this way, the indirect band gap of the first green absorber (second green absorber) is relatively large, which allows the first green absorber (second green absorber) to absorb green light better without absorbing red light, thereby improving the problem of light crosstalk and improving the image quality generated by electronic devices using this image sensor.

[0016] In another possible implementation of the first aspect, the light-absorbing layer includes a first region and a second region. An absorber located within the first region is designated as a first absorber, and an absorber located within the second region is designated as a second absorber. The composition ratios of Si, Ge, and Sn elements in the first and second absorber regions are different.

[0017] In the image sensor provided in this application embodiment, the composition ratios of Si, Ge, and Sn elements in the first and second absorption sections are different. This allows the quantum efficiency of the first and second absorption sections to be adjusted according to the different needs of the first and second regions, reducing the effect deviation of image information acquired in different regions, thereby improving the image acquisition capability and image acquisition effect of the image sensor, as well as the imaging effect of the electronic device using the image sensor.

[0018] In one possible implementation of the first aspect, the light-absorbing layer includes a light-receiving surface, which comprises a first portion and a second portion. The first portion corresponds to a first region, and the second portion corresponds to a second region. The distance from the center of the light-receiving surface to the edge of the first portion is less than or equal to 0.7 times the maximum distance from the center of the light-receiving surface to the edge of the second portion. In this case, the difference in light received by the first and second regions is significant. Adjusting the composition ratio of Si, Ge, and Sn elements in the first and second absorption portions can effectively reduce the image information deviation between the first and second regions.

[0019] In another possible implementation of the first aspect, the sum of the component proportions of Ge and Sn in the first absorption section is greater than the sum of the component proportions of Ge and Sn in the second absorption section. Alternatively, the sum of the component proportions of Ge and Sn in the first absorption section is less than the sum of the component proportions of Ge and Sn in the second absorption section.

[0020] This results in differences in the absorption coefficients and quantum efficiencies of the first and second absorption sections, leading to differences in the photoelectric conversion efficiency of the optical fiber within the same wavelength range. Even with significant differences in the light received by the first and second regions, the deviation in the image information acquired from different regions can be minimized. This improves the image acquisition capability and quality of the image sensor, as well as the imaging performance of electronic devices using this image sensor.

[0021] In one possible implementation of the first aspect, the light-absorbing layer includes a first sublayer and a second sublayer stacked together. The material of the first sublayer includes a SixGe1-x-ySny alloy, and the material of the second sublayer includes at least one of Si, SiGe, and Ge. The lattice constant of the second sublayer is smaller than that of the first sublayer. This effectively reduces the dark current generated by the lattice mismatch between Si, Ge, and Sn in the light-absorbing layer, thereby improving the performance of the light-absorbing layer.

[0022] In another possible implementation of the first aspect, the image sensor further includes a logic circuit layer and a filter layer. The logic circuit layer is located on one side of the light absorption layer; the filter layer is located on the side of the light absorption layer away from the logic circuit layer. The filter layer includes multiple filter units, with each filter unit corresponding to an absorption section. In the embodiments of this application, a filter unit can be disposed opposite to an absorption section, allowing all photoelectric conversion elements in an absorption section to receive light of the same color.

[0023] In one possible implementation of the first aspect, the image sensor further includes: an isolation structure located on the logic circuit layer and between two adjacent absorbers; the isolation structure is made of an insulating material. By providing the isolation structure, the problem of charges generated in the absorbers moving to adjacent absorbers and affecting the charge quantity of the adjacent absorbers can be mitigated or even avoided.

[0024] Secondly, this application provides a method for fabricating an image sensor, the method comprising: forming a light-absorbing layer; the material of the light-absorbing layer comprising a SixGe1-x-ySny alloy, wherein x and y are both greater than 0 and less than 1; the light-absorbing layer comprising multiple absorption sections, wherein the composition ratios of Si, Ge, and Sn elements in the multiple absorption sections are different; forming a logic circuit layer on one side of the light-absorbing layer; and forming a filter layer on the side of the light-absorbing layer away from the logic circuit layer; the filter layer comprising multiple filter units, one filter unit corresponding to one absorption section.

[0025] In one possible implementation of the second aspect, the multiple absorption portions are a red absorption portion, a blue absorption portion, a first green absorption portion, and a second green absorption portion; a light absorption layer is formed, including forming the red absorption portion, the blue absorption portion, the first green absorption portion, and the second green absorption portion on different portions of the same surface of the substrate, respectively; the composition ratios of Si, Ge, and Sn elements in the red absorption portion, the blue absorption portion, and the first green absorption portion are different; the composition ratios of Si, Ge, and Sn elements in the first green absorption portion and the second green absorption portion are the same.

[0026] In one possible implementation of the second aspect, the plurality of absorbing portions are a first absorbing portion and a second absorbing portion; forming a light-absorbing layer includes: forming a first absorbing portion on a substrate; the substrate includes a first sub-part and a second sub-part, the second sub-part being located on the periphery of the first sub-part, and the first absorbing portion being located on the first sub-part. A second absorbing portion is formed on the substrate, the second absorbing portion being located on the same side of the substrate as the first absorbing portion, and the second absorbing portion being located on the second sub-part. The composition ratios of Si, Ge, and Sn elements in the first absorbing portion and the second absorbing portion are different.

[0027] Thirdly, this application provides a camera module, which includes a lens assembly and an image sensor as provided in any of the above implementations, wherein the lens assembly is located on the light-incident side of the image sensor.

[0028] Fourthly, this application provides an electronic device, which includes a processor and a camera module as described in any of the above implementations, wherein the processor is electrically connected to an image sensor in the camera module.

[0029] The technical effects of any of the design methods in the second to fourth aspects can be found in the technical effects of different implementation methods in the first aspect, and will not be repeated here. Attached Figure Description

[0030] Figure 1 This is a schematic diagram of the structure of an electronic device provided in an embodiment of this application;

[0031] Figure 2 An exploded view of an electronic device provided in an embodiment of this application;

[0032] Figure 3 This is a schematic diagram of the structure of a camera module provided in an embodiment of this application;

[0033] Figure 4 Quantum efficiency curves for different pixels provided in embodiments of this application;

[0034] Figure 5 This is a schematic diagram of the structure of an image sensor provided in an embodiment of this application;

[0035] Figure 6 Band structure diagrams of Si, Ge, and Sn provided for embodiments of this application;

[0036] Figure 7 The absorption coefficients of Si and GE are shown as photon energy curves in the embodiments of this application.

[0037] Figure 8 This is a top view schematic diagram of a light absorption layer provided in an embodiment of this application;

[0038] Figure 9 A top view schematic diagram of another light absorption layer provided in the embodiments of this application;

[0039] Figure 10 This is a schematic diagram of the field of view of the image sensor provided in the embodiments of this application;

[0040] Figure 11 This is a schematic diagram of another image sensor structure provided in an embodiment of this application;

[0041] Figure 12This is a schematic diagram of the structure of another image sensor provided in an embodiment of this application;

[0042] Figure 13 A flowchart illustrating the fabrication process of an image sensor provided in this application embodiment;

[0043] Figure 14 This is a structural state diagram of the image sensor corresponding to step S100;

[0044] Figure 15 This is a structural state diagram of the image sensor corresponding to step S111;

[0045] Figure 16 This is a structural state diagram of the image sensor corresponding to step S112;

[0046] Figure 17 This is a structural state diagram of the image sensor corresponding to step S113;

[0047] Figure 18 This is a structural state diagram of the image sensor corresponding to step S114;

[0048] Figure 19 This is a structural state diagram of the image sensor corresponding to step S115;

[0049] Figure 20 This is a structural state diagram of another image sensor corresponding to step S100;

[0050] Figure 21 A flowchart illustrating the fabrication process of another image sensor provided in this application embodiment;

[0051] Figure 22 This is a structural state diagram of the image sensor corresponding to step S200;

[0052] Figure 23 This is a structural state diagram of the image sensor corresponding to step S400;

[0053] Figure 24 This is a structural state diagram of the image sensor corresponding to step S300. Detailed Implementation

[0054] The technical solutions of the embodiments of this application will now be described with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments provided in this application are within the scope of protection of this application.

[0055] Unless the context otherwise requires, throughout the specification and claims, the term "comprising" is interpreted as open-ended and encompassing, meaning "including, but not limited to." In the description of the specification, terms such as "one embodiment," "some embodiments," "exemplary embodiment," "exemplary," or "some examples," etc., are intended to indicate that a particular feature, structure, material, or characteristic associated with that embodiment or example is included in at least one embodiment or example of this application. The illustrative representations of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics mentioned may be included in any suitable manner in any one or more embodiments or examples.

[0056] In the description of this application, unless otherwise stated, "a plurality of" means two or more.

[0057] Furthermore, to facilitate a clear description of the technical solutions in the embodiments of this application, the terms "first," "second," and "third" are used in the embodiments of this application to distinguish identical or similar items with essentially the same function and effect. Those skilled in the art will understand that the terms "first," "second," and "third" do not limit the quantity or execution order, and the terms "first," "second," and "third" are not necessarily different.

[0058] In this application, the terms "exemplary" or "for example" are used to indicate that something is an example, illustration, or description. Any embodiment or design described as "exemplary" or "for example" in this application should not be construed as being better or more advantageous than other embodiments or designs. Specifically, the use of terms such as "exemplary" or "for example" is intended to present the relevant concepts in a specific manner to facilitate understanding.

[0059] This application describes exemplary embodiments with reference to cross-sectional views and / or plan views as idealized exemplary drawings. In the drawings, the thickness of layers and regions is enlarged for clarity. Therefore, variations in shape relative to the drawings are contemplated due to, for example, manufacturing techniques and / or tolerances. Thus, exemplary embodiments should not be construed as limited to the shapes of the regions shown in this application, but rather include shape deviations due to, for example, manufacturing processes. For example, etched regions shown as rectangular would typically have curved features. Therefore, the regions shown in the drawings are schematic in nature, and their shapes are not intended to show the actual shapes of the regions of the device, nor are they intended to limit the scope of the exemplary embodiments.

[0060] Furthermore, the architecture and scenarios described in the embodiments of this application are for the purpose of more clearly illustrating the technical solutions of the embodiments of this application, and do not constitute a limitation on the technical solutions provided in the embodiments of this application. As those skilled in the art will know, with the evolution of architecture and the emergence of new scenarios, the technical solutions provided in the embodiments of this application are also applicable to similar technical problems.

[0061] This application provides an electronic device with camera functionality. This electronic device can be, for example, a webcam, an internet protocol camera (IPC), a mobile phone with front and / or rear cameras, a tablet with front and / or rear cameras, a digital camera, a digital camcorder, a vehicle-mounted camera, or an industrial camera capable of image acquisition. Furthermore, this electronic device can be used in security, photography and videography, automotive electronics, or industrial machine vision applications.

[0062] Figure 1 This is a structural diagram of an electronic device 100 provided in an embodiment of this application. Figure 2 An exploded view of an electronic device 100 provided in an embodiment of this application. Wherein, Figure 1 and Figure 2 All examples use mobile phones as an example, with "electronic device 100" as the illustration. Figure 1 As shown, the electronic device 100 includes a screen 10, a back cover 20, and a camera module 30.

[0063] The screen 10 is used to display images and / or videos. The back cover 20 is used to protect the internal electronic components of the electronic device 100 (e.g., motherboard, processor, battery, etc.). The camera module 30 is used to take photos and / or videos.

[0064] The back cover 20 may include a back cover 21 and a frame 22. The frame 22 is disposed around the edge of the back cover 21, and the screen is located on the side of the frame 22 opposite to the back cover 21. The screen 10 is attached to the periphery of the frame 22. The screen 10, the back cover 21, and the frame 22 form the internal housing space of the electronic device 100.

[0065] The camera module 30 is fixed in the internal storage space of the electronic device 100. For example, the camera module 30 can be a periscope camera module or a vertical camera module.

[0066] In some examples, camera module 30 can be a rear-facing camera module. In this case, such as... Figure 1 and Figure 2As shown, the electronic device 100 may also include a camera cover 40 located on the back cover 21. The camera cover 40 has a light-transmitting window (not shown) that allows light to pass through so that the light can illuminate the camera module 30.

[0067] Figure 3 This is a schematic diagram of the structure of a camera module 30 provided in an embodiment of this application. Figure 3 As shown, the camera module 30 includes an image sensor 31 and a lens assembly 32, with the lens assembly 32 located on the light-incident side of the image sensor 31. The light-incident side refers to the side of the image sensor 31 that receives light. The lens assembly 32 is used to converge the light emitted or reflected by the object being photographed onto the image sensor 31.

[0068] The image sensor 31 can also be referred to as a photosensitive chip, photosensitive element, etc. For example, the image sensor 31 may include multiple photoelectric conversion elements that can generate charge after receiving light, that is, convert light signals into electrical signals.

[0069] It is understood that the structure of the camera module 30 in this application embodiment is not limited to this.

[0070] In some embodiments, the electronic device 100 may further include a processor electrically connected to the camera module 30. For example, the processor may be connected to the image sensor 31 in the camera module 30, and the processor may be able to receive and process electrical signals from the image sensor 31.

[0071] For example, the processor may include an analog-to-digital converter (ADC) and a digital signal processor (DSP) connected together. The ADC converts analog electrical signals into digital electrical signals and transmits these digital signals to the DSP. The DSP processes the digital electrical signals, for example, by optimizing them through a series of complex mathematical algorithms, ultimately outputting an image.

[0072] With the development of image sensors, their resolution is increasing, the number of pixels is growing, and the pixel size is decreasing, resulting in less light being received by each pixel. Because image sensors incorporate color filters (CF), over 50% of the light incident on each pixel is absorbed by the color filter, further reducing the amount of light received by the photoelectric conversion element below the color filter. This decrease in light reception by the photoelectric conversion element leads to a weaker electrical signal generated by the image sensor, resulting in a poorer signal-to-noise ratio and ultimately lower image or video quality.

[0073] In low-light environments, the photoelectric conversion elements in an image sensor can receive less light compared to those in bright light, resulting in a poorer signal-to-noise ratio and lower quality images or videos. To improve image brightness, it is often necessary to extend the exposure time of the image sensor (e.g., to tens of milliseconds or even several seconds), but this negatively impacts the user's photography experience in low-light conditions.

[0074] Beyond consumer electronics, the issue of insufficient light reception in image sensors, particularly photoelectric conversion elements, is also evident in the automotive sector. Intelligent driving systems relying on machine vision face significant challenges in nighttime (low-light) imaging. Insufficient lighting results in dark real-time images from automotive cameras, severely impacting the driver's and driver assistance systems' perception of their surroundings.

[0075] To address the aforementioned issues, related technologies have altered the material composition of color filters to change their absorption rate for different wavelengths of light, thereby increasing the amount of light received by the photoelectric conversion element below the color filter. However, this method does not improve the photoelectric conversion efficiency of the photoelectric conversion element.

[0076] Figure 4 This is a graph showing the quantum efficiency (QE) of an image sensor. The horizontal axis represents wavelength in nanometers (nm), and the vertical axis represents absolute quantum efficiency. Figure 4 Using an image sensor comprising blue pixels, red pixels, a first green pixel, and a second green pixel as an example, the quantum efficiency curves corresponding to different types of pixels are shown.

[0077] like Figure 4 As shown, due to the presence of color filters, different types of pixels have different absolute quantum efficiencies for light of different wavelengths. For example, blue pixels have higher absolute quantum efficiencies for light with wavelengths of 400nm to 500nm, the first green pixel and the second green pixel have higher absolute quantum efficiencies for light with wavelengths of 500nm to 600nm, and red pixels have higher absolute quantum efficiencies for light with wavelengths of 625nm to 740nm.

[0078] Taking a blue pixel as an example, when the absorption rate of a color filter changes for different wavelengths of light, the color filter can allow not only light with wavelengths of 400nm to 500nm to pass through, but also light with a wavelength of 650nm. This increases the amount of 650nm light received by the photoelectric conversion element in the blue pixel, thereby improving the absolute quantum efficiency of the blue pixel for 650nm light. However, the quantum efficiency of the blue pixel for light with wavelengths of 400nm to 500nm is difficult to improve.

[0079] Current image sensors suffer from low absorption efficiency for infrared wavelengths, hindering their ability to meet the demands of certain applications. For example, a camera in an underground parking garage doesn't need to accurately determine object color; it only needs to be able to observe objects in low-light conditions. In such scenarios, a higher absorption efficiency for infrared wavelengths significantly improves the imaging performance of electronic devices using that sensor in darker environments.

[0080] In view of the above problems, this application provides an image sensor that can be applied to the above-mentioned camera module or directly applied to electronic devices. Figure 5 This is a schematic diagram of the structure of the image sensor 200 provided in an embodiment of this application. Figure 5 As shown, the image sensor 200 includes a light absorption layer 201, a light filter layer 202, and a logic circuit layer 203. The light filter layer 202 is located on one side of the light absorption layer 201, and the logic circuit layer 203 is located on the side of the light absorption layer 201 away from the light filter layer 202. That is, the light absorption layer 201 is located between the light filter layer 202 and the logic circuit layer 203.

[0081] The light absorption layer 201 may contain multiple photoelectric conversion elements 211. These photoelectric conversion elements 211 are used to receive optical signals and convert them into electrical signals. For example, the photoelectric conversion element 211 is a photodiode.

[0082] For example, such as Figure 5 As shown, the photoelectric conversion element 211 may include an N-type doped region 211a and a P-type doped region 211b, and a PN junction is formed at the interface between the N-type doped region 211a and the P-type doped region 211b. It is understood that... Figure 5 The example shown is that the P-type doped region 211b encloses the N-type doped region 211a. However, the positional relationship between the N-type doped region 211a and the P-type doped region 211b in this embodiment is not limited to this.

[0083] The material of the light-absorbing layer 201 includes Si. x Ge 1-x-y Sn y An alloy in which x and y are both greater than 0 and less than 1.

[0084] Figure 6 The band structure is composed of silicon (Si), germanium (Ge), and tin (Sn). Figure 6 The diagram shows the valence band, heavy hole band, and light hole band of Si, Ge, and Sn, respectively. The horizontal axis K represents crystal momentum, and the vertical axis E represents electron energy. Points Γ, X, and L are three high-symmetry points on the valence band; the extreme values ​​(maximums or minimums) of the valence band fall at these high-symmetry points.

[0085] pass Figure 6 It can be seen that the indirect band gap of silicon is 1.12 eV (electron volts), and the direct band gap of silicon is 3.5 eV. The indirect band gap of germanium is 0.66 eV, and the direct band gap of germanium is 0.805 eV. Tin is a half-metal; its indirect band gap is -0.413 eV, and its direct band gap is 0.098 eV. Therefore, it is evident that the indirect band gap of silicon is greater than that of germanium, and the indirect band gap of germanium is greater than that of tin; conversely, the direct band gap of silicon is greater than that of germanium, and the direct band gap of germanium is greater than that of tin.

[0086] Thus, by adding germanium and tin to silicon materials to form Si x Ge 1-x-y Sn y During the alloying process, by adjusting the composition ratio of germanium, tin, and silicon, the Si can be alloyed. x Ge 1-x-y Sn y The gap (or band structure) of the alloy can be controlled.

[0087] For example, Si x Ge 1-x-y Sn y The indirect band gap of the alloy satisfies the formula:

[0088] Among them, E i (x, y) represents Si x Ge 1-x-y Sn y Indirect band gap of alloys Indicates the indirect band gap of silicon. Indicates the indirect band gap of germanium. Indicates the indirect band gap of tin. This indicates the band bending coefficient of germanium-tin alloys. This indicates the band bending coefficient of silicon-germanium alloys. This represents the band bending coefficient of the silicon-tin alloy. x and y represent the band bending coefficient of Si. x Ge 1-x-y Sn y The proportions of silicon and tin components in the alloy.

[0089] By adjusting the composition ratio of germanium, tin, and silicon, Si can be made... x Ge 1-x-y Sn y The indirect bandgap of the alloy is adjustable within the range of -0.41 eV to 1.12 eV. In this embodiment, the material of the light-absorbing layer 201 includes Si. x Ge 1-x-y Sn yWhen alloying, the indirect band gap of the light absorption layer 201 is also adjustable in the range of -0.41eV to 1.12eV.

[0090] Figure 7 This graph shows the relationship between the absorption coefficient of silicon (Si) and germanium (Ge) at different temperatures (300K and 77K) and photon energy. The horizontal axis represents photon energy in eV, and the vertical axis represents the absorption coefficient in cm. Figure 7 It is known that, at the same photon energy, germanium has a greater absorption coefficient than silicon. Tin, being a semi-metal, has a much greater absorption coefficient than both germanium and silicon at the same photon energy.

[0091] The relationship between quantum efficiency and absorption coefficient satisfies the following formula: Where η represents quantum efficiency, a s ω represents the light absorption coefficient. a This indicates the material thickness. Therefore, the larger the absorption coefficient, the greater the quantum efficiency.

[0092] In this embodiment, germanium and tin are added to silicon material to form Si. x Ge 1-x-y Sn y Alloys, making Si x Ge 1-x- y Sn y The absorption coefficient of the alloy can be greater than that of silicon, Si x Ge 1-x-y Sn y The quantum efficiency of the alloy can be greater than that of silicon. In the embodiments of this application, the material of the light-absorbing layer includes Si. x Ge 1-x-y Sn y Alloys can make the quantum efficiency of the light absorption layer higher than that of a light absorption layer made of silicon.

[0093] In this embodiment, the material of the light-absorbing layer 201 includes Si. x Ge 1-x-y Sn y The alloy allows for the tunability of the indirect bandgap of the light absorption layer 201 within the range of -0.41 eV to 1.12 eV, thereby enabling the adjustment of the absorption wavelength and improving the applicability of the image sensor. For example, when the indirect bandgap of the light absorption layer is small, even light with wavelengths in the infrared band can be absorbed by the light absorption layer. Furthermore, the alloy allows for a higher absorption coefficient and quantum efficiency in the light absorption layer 201, improving the photoelectric conversion capability of the image sensor and ultimately enhancing the quality of the images generated using the image sensor.

[0094] Meanwhile, because Si has an electron mobility of 1350 cm⁻¹ 2 / Vs, the electron mobility of Ge is 3600 cm⁻¹ 2 The electron mobility of Sn is 120000 cm⁻¹ / Vs. 2 / Vs, therefore the material of the light-absorbing layer 201 includes Si x Ge 1-x-y Sn y When alloyed, the electron mobility of the light-absorbing layer can be higher than that of the light-absorbing layer using only Si material, resulting in a higher electron mobility of the light-absorbing layer 201.

[0095] Similarly, since the hole mobility of Si is 480 cm⁻¹ 2 / Vs, the hole mobility of Ge is 1800cm 2 The hole mobility of / Vs,Sn is 110000cm 2 / Vs, therefore the material of the light-absorbing layer 201 includes Si x Ge 1-x-y Sn y When alloyed, the hole mobility of the light absorption layer can be higher than that of the light absorption layer using only Si material, resulting in a higher hole mobility of the light absorption layer 201.

[0096] In the embodiments of this application, the light absorption layer 201 has both high electron mobility and high hole mobility, which can result in a high carrier transport speed, which is beneficial to the rapid transmission of electrical signals generated by the light absorption layer 201.

[0097] In addition, Si, Ge, and Sn are all group IV elements; therefore, the material of the light-absorbing layer 201 in this embodiment includes Si. x Ge 1-x-y Sn y The alloy also allows for a smaller degree of lattice mismatch in the light absorption layer 201 and a smaller dark current.

[0098] In this embodiment, the thickness of the light absorption layer 201 is not limited and can be designed according to actual needs. As shown in the above embodiments, the quantum efficiency of the light absorption layer 201 is positively correlated with the absorption coefficient of the material in the light absorption layer 201 and also with the thickness of the light absorption layer 201. When the absorption coefficient of the material in the light absorption layer 201 is large, the thickness of the light absorption layer 201 in this embodiment can be smaller to achieve the same quantum efficiency. Meanwhile, when the thickness of the light absorption layer 201 is consistent, since the light absorption layer 201 uses Si... x Ge 1-x-y Sn yThe alloy has a large absorption coefficient, and the quantum efficiency of the light absorption layer 201 in this embodiment can be significantly greater than that of the light absorption layer in related technologies.

[0099] The light absorption layer 201 includes multiple photoelectric conversion elements. These elements operate in different environments, meaning they are located in different positions and absorb different amounts of light. However, all the photoelectric conversion elements have the same conversion capability. This leads to some elements failing to meet operational requirements, and in severe cases, it can affect the image acquisition effect of the image sensor and the imaging quality of the electronic device.

[0100] Based on this, in some embodiments, such as Figure 5 As shown, the light absorption layer 201 includes multiple absorption sections 221, and the composition ratios of Si, Ge, and Sn elements in the multiple absorption sections 221 are different.

[0101] The absorption section 221 includes at least one photoelectric conversion element 211, that is, an absorption section 221 may include one photoelectric conversion element 211 or multiple photoelectric conversion elements 211. Figure 5 The illustration takes an absorption section 221 that includes a photoelectric conversion element 211 as an example.

[0102] In this embodiment, the number of light-absorbing parts in the light-absorbing layer is not limited, and can be designed according to actual needs.

[0103] It is understandable that "the different composition ratios of Si, Ge, and Sn elements in the multiple absorption sections 221" means that at least two of the multiple absorption sections 221 have different composition ratios of Si, Ge, and Sn elements. That is, in the multiple absorption sections 221 of the light absorption layer 201, some absorption sections 221 may have the same composition ratio of Si, Ge, and Sn elements, while other absorption sections 221 may have different composition ratios. Alternatively, in the multiple absorption sections of the light absorption layer, the composition ratios of Si, Ge, and Sn elements in any two absorption sections may be different.

[0104] In the image sensor provided in this application embodiment, the composition ratio of Si, Ge, and Sn elements in the multiple absorption sections 221 is different, which can make the quantum efficiency of the multiple light absorption sections 221 different. This allows different light absorption sections 221 to have different photoelectric conversion efficiencies for light of the same wavelength, or different light absorption sections 221 to absorb light of different wavelength ranges. As a result, the performance of the multiple light absorption sections 221 is different. The photoelectric conversion elements located in different light absorption sections 221 can meet different working requirements, thereby improving the image acquisition capability and image acquisition effect of the image sensor 200, as well as the imaging effect of the electronic device using the image sensor 200.

[0105] Figure 8 This is a top view schematic diagram of a light absorption layer provided in an embodiment of this application. In some examples, such as... Figure 8 As shown, the absorption portions 221 in the light absorption layer 201 can be arranged in an array. That is, multiple absorption portions 221 can be arranged in multiple rows and columns. At this time, multiple absorption portions 221 located in the same row can be arranged along the first direction X, and multiple absorption portions 221 located in the same column can be arranged along the second direction Y.

[0106] In some embodiments, continue reading Figure 8 The multiple absorption sections 221 can be divided into a red absorption section 221a, a first green absorption section 221b, a second green absorption section 221c, and a blue absorption section 221d.

[0107] Among them, the red absorption part 221a can be used to absorb red light, the first green absorption part 221b and the second green absorption part 221c are used to absorb green light, and the blue absorption part 221d is used to absorb blue light.

[0108] It is understood that at least one photoelectric conversion element 211 in the red absorption section 221a can be used to absorb red light. At least one photoelectric conversion element 211 in the first green absorption section 221b and the second green absorption section 221c can be used to absorb green light. At least one photoelectric conversion element 211 in the blue absorption section 221d can be used to absorb blue light.

[0109] For example, the red absorption portion 221a, the first green absorption portion 221b, the second green absorption portion 221c, and the blue absorption portion 221d can be arranged in a Bayer pattern.

[0110] For example, the number of red absorption portions 221a, the number of first green absorption portions 221b, the number of second green absorption portions 221c, and the number of blue absorption portions 221d can be the same.

[0111] In some examples, the composition ratios of Si, Ge, and Sn elements in the red absorber 221a, the first green absorber 221b, and the blue absorber 221d are different. The composition ratios of Si, Ge, and Sn elements in the first green absorber 221b and the second green absorber 221c are the same.

[0112] In the image sensor 200 provided in this application embodiment, the composition ratios of Si, Ge, and Sn elements in the red absorption section 221a, the first green absorption section 221b (or the second green absorption section 221c), and the blue absorption section 221d are different. This allows for optimization of the photoelectric conversion capability of different absorption sections 221 for different wavelengths based on the quantum efficiency of the different absorption sections 221 for the corresponding wavelengths, thereby improving the performance of the photoelectric conversion element 211 in the different absorption sections, enhancing the image acquisition capability of the image sensor, and ultimately improving the imaging quality of the electronic device using the image sensor.

[0113] Meanwhile, the different proportions of Si, Ge, and Sn elements in the red absorber 221a, the first green absorber 221b (or the second green absorber 221c), and the blue absorber 221d can adjust the wavelength of light that can be absorbed by different absorbers 221, improve the accuracy of other colors of light affecting the generation of electrical signals by the absorbers 221, further optimize the image acquisition capability of the image sensor, and improve the imaging quality of electronic devices using the image sensor.

[0114] In addition, the Si, Ge and Sn elements in the first green absorption part 221b and the second green absorption part 221c are in the same composition ratio, which allows the first green absorption part 221b and the second green absorption part 221c to be prepared simultaneously. This simplifies the preparation process of the light absorption layer 201 and improves the preparation efficiency of the light absorption layer 201, thereby improving the preparation efficiency of the image sensor 200.

[0115] It is understood that the light absorption layer 201 may include multiple red absorbers 221a. In this case, the composition ratio of Si, Ge, and Sn elements in the multiple red absorbers 221a can be the same. This allows the multiple red absorbers 221a in the light absorption layer 201 to be fabricated simultaneously, which simplifies the fabrication process of the light absorption layer 201 and improves its fabrication efficiency.

[0116] Similarly, the light-absorbing layer 201 may include multiple first green absorbers 221b. In this case, the composition ratio of Si, Ge, and Sn elements in the multiple first green absorbers 221b can be the same. This allows multiple first green absorbers 221b in the light-absorbing layer 201 to be fabricated simultaneously, which simplifies the fabrication process of the light-absorbing layer 201 and improves its fabrication efficiency.

[0117] Similarly, the light-absorbing layer 201 may include multiple second green absorbers 221c. In this case, the composition ratios of Si, Ge, and Sn elements in the multiple second green absorbers 221c can be the same. This allows multiple second green absorbers 221c in the light-absorbing layer 201 to be fabricated simultaneously, which simplifies the fabrication process of the light-absorbing layer 201 and improves its fabrication efficiency.

[0118] Of course, the light-absorbing layer 201 may include multiple blue absorbers 221d. In this case, the composition ratio of Si, Ge, and Sn elements in the multiple blue absorbers 221d can be the same. In this way, the multiple blue absorbers 221d in the light-absorbing layer 201 can be fabricated simultaneously, which helps to simplify the fabrication process of the light-absorbing layer 201 and improve the fabrication efficiency of the light-absorbing layer 201.

[0119] In some examples, the sum of the proportions of Ge and Sn elements in the red absorber 221a can be greater than the sum of the proportions of Ge and Sn elements in the blue absorber 221d. The sum of the proportions of Ge and Sn elements in the red absorber 221a can be greater than the sum of the proportions of Ge and Sn elements in the first green absorber 221b (or the second green absorber 221c).

[0120] In this way, the absorption coefficient of the red absorber 221a can be relatively large, which is beneficial to improving the photoelectric conversion efficiency of the red absorber 221a for red light. At the same time, the indirect band gap of the red absorber 221a can be relatively small, allowing the red absorber 221a to absorb more red light and even infrared light.

[0121] It is understandable that "the sum of the proportions of Ge and Sn elements in the red absorber 221a is greater than the sum of the proportions of Ge and Sn elements in the blue absorber 221d," therefore, the proportion of Si element in the blue absorber 221d is greater than the proportion of Si element in the red absorber 221a. This results in a larger indirect bandgap in the blue absorber 221d, allowing it to better absorb blue light without absorbing red or green light. This helps to mitigate crosstalk and improve the image quality generated by electronic devices using this image sensor.

[0122] "The sum of the proportions of Ge and Sn elements in the red absorber 221a is greater than the sum of the proportions of Ge and Sn elements in the first green absorber 221b (or the second green absorber 221c)," therefore, the proportion of Si elements in the first green absorber 221b is greater than the proportion of Si elements in the red absorber 221a.

[0123] In this way, the indirect band gaps of the first green absorption section 221b (the second green absorption section 221c) are both large, which allows the first green absorption section 221b (the second green absorption section 221c) to absorb green light better without absorbing red light, thereby improving the problem of light crosstalk and improving the image quality generated by electronic devices using this image sensor.

[0124] In some embodiments, such as Figure 9 As shown, the light absorption layer 201 may include a first region AA and a second region BB. Among the plurality of absorption portions 221, the absorption portion located within the first region AA is designated as the first absorption portion 221e, and the absorption portion located within the second region AA is designated as the second absorption portion 221f. The composition ratios of Si, Ge, and Sn elements in the first absorption portion 221e and the second absorption portion 221f are different.

[0125] In some examples, the second region BB can be located around the first region AA. For example, the second region BB can be set around the first region AA.

[0126] The first absorption section 221e can be used to absorb red, green, or blue light. The second absorption section 221f can also be used to absorb red, green, or blue light.

[0127] "The composition ratios of Si, Ge, and Sn elements in the first absorption section 221e and the second absorption section 221f are different" can mean that the composition ratios of Si, Ge, and Sn elements are different in all the first absorption sections 221e and the second absorption section 221f, or that the composition ratios of Si, Ge, and Sn elements are different in a portion of the first absorption sections 221e and the second absorption section 221f, while the composition ratios of Si, Ge, and Sn elements are different in another portion of the first absorption sections 221e and the second absorption section 221f.

[0128] For example, there is a difference in the composition ratio of Si, Ge, and Sn elements between the first absorption portion 221e absorbing red light in the first region AA and the second absorption portion 221f absorbing red light in the second region BB. However, there is no difference in the composition ratio of Si, Ge, and Sn elements between the first absorption portion 221e absorbing blue light in the first region AA and the second absorption portion 221f absorbing blue light in the second region BB. Similarly, there is no difference in the composition ratio of Si, Ge, and Sn elements between the first absorption portion 221e absorbing green light in the first region AA and the second absorption portion 221f absorbing green light in the second region BB.

[0129] For example, there is a difference in the composition ratio of Si, Ge, and Sn elements between the first absorption portion 221e absorbing blue light in the first region AA and the second absorption portion 221f absorbing blue light in the second region BB. However, there is no difference in the composition ratio of Si, Ge, and Sn elements between the first absorption portion 221e absorbing red light in the first region AA and the second absorption portion 221f absorbing red light in the second region BB. Similarly, there is no difference in the composition ratio of Si, Ge, and Sn elements between the first absorption portion 221e absorbing green light in the first region AA and the second absorption portion 221f absorbing green light in the second region BB.

[0130] It is understandable that the light received by the light absorption layer 201 varies at different locations, for example, the proportions of red, green, and blue light in the light differ. In the image sensor provided in this application embodiment, the composition ratios of Si, Ge, and Sn elements in the first absorption section 221e and the second absorption section 221f are different. This allows the quantum efficiency of the first absorption section 221e and the second absorption section 221f to be adjusted according to the different requirements of the first region AA and the second region BB, thereby reducing the effect deviation of image information acquired in different regions, and thus improving the image acquisition capability and image acquisition effect of the image sensor 200, as well as the imaging effect of the electronic device using the image sensor 200.

[0131] In some embodiments, such as Figure 9 As shown, the light absorption layer 201 includes a light receiving surface S1, which comprises a first portion S11 and a second portion S12. The first portion S11 corresponds to the first region AA, and the second portion S12 corresponds to the second region BB. The distance d1 from the center Q of the light receiving surface S1 to the edge of the first portion AA is less than or equal to 0.7 times the maximum distance d2 from the center Q of the light receiving surface S1 to the edge of the second portion BB.

[0132] Understandable Figure 9The first part S11 is illustrated as a rectangle, but the shape of the first part S11 in this embodiment is not necessarily the same. For example, the first part S11 can be circular.

[0133] At this time, the light received by the first region AA and the second region BB is significantly different. Adjusting the composition ratio of Si, Ge and Sn elements in the first absorption part 221e and the second absorption part 221f can effectively reduce the effect deviation of the image information acquired by the first region AA and the second region BB.

[0134] Figure 10 This is a schematic diagram of the field of view of the image sensor 200. During the use of the image sensor, due to differences in the field of view, color shading often exists between different fields of view (e.g., high field of view and central field of view). For example, the high field of view receives more red light than the central field of view. Thus, when the performance of the photoelectric conversion elements in the light absorption layer corresponding to different fields of view is the same, the portion of the image generated using information collected by the photoelectric conversion elements in the region corresponding to the high field of view will have a significantly different effect compared to the portion of the image generated using information collected by the photoelectric conversion elements in the region corresponding to the central field of view. For example, the overall image may appear reddish, resulting in an overall color shading problem.

[0135] In this case, the first region AA in the above embodiment can correspond to the central field of view, and the second region BB can correspond to the high field of view. Adjusting the composition ratio of Si, Ge, and Sn elements in the first absorption part 221e in the first region AA and the second absorption part 221f in the second region BB can also improve the color shift problem caused by the difference in field of view.

[0136] In some examples, the sum of the proportions of Ge and Sn elements in the first absorber 221e located in the first region AA is less than the sum of the proportions of Ge and Sn elements in the second absorber 221f located in the second region BB. Alternatively, the sum of the proportions of Ge and Sn elements in the first absorber 221e located in the first region AA is less than the sum of the proportions of Ge and Sn elements in the second absorber 221f located in the second region BB.

[0137] In this way, the absorption coefficients of the first absorption section 221e and the second absorption section 221f are different, and their quantum efficiencies are also different, resulting in differences in the photoelectric conversion efficiency of the optical fiber within the same wavelength range. Even if the light received by the first region AA and the second region BB differs significantly, the effect deviation of the image information acquired from different regions is relatively small. This improves the image acquisition capability and effect of the image sensor, as well as the imaging effect of the electronic device using this image sensor.

[0138] In some embodiments, such as Figure 5 As shown, the light absorption layer 201 can be a single-layer structure.

[0139] In other embodiments, such as Figure 11 As shown, the light absorption layer 201 can be a multilayer structure.

[0140] In some examples, such as Figure 11 As shown, the light-absorbing layer 201 includes a first sub-layer 231 and a second sub-layer 241 stacked together. The material of the first sub-layer 231 includes Si. x Ge 1-x-y Sn y The alloy, the material of the second sublayer 241 includes at least one of Si, SiGe, and Ge. Furthermore, the lattice constant of the second sublayer 241 is less than the lattice constant of the first sublayer 231.

[0141] This effectively reduces the dark current generated by the lattice mismatch between Si, Ge and Sn in the light absorption layer 201, thereby improving the performance of the light absorption layer 201.

[0142] Continue reading Figure 5 The filter layer 202 may include multiple filter units 212, and one filter unit 212 may be disposed opposite to an absorber 221. The filter unit 212 can be used to filter incident light, allowing light of a specific color to pass through. For example, the filter unit 212 may be a color filter.

[0143] For example, the multiple filter units 212 can be divided into a first filter unit 212a, a second filter unit 212b, and a third filter unit 212c. The first filter unit 212a allows light of a first color to pass through, the second filter unit 212b allows light of a second color to pass through, and the third filter unit 212c allows light of a third color to pass through. The first, second, and third colors of light can correspond to the three primary colors; for example, the first color of light is red, the second color of light is blue, and the third color of light is green.

[0144] The photoelectric conversion element 211 in the absorption section 221 corresponds one-to-one with the filter unit 212, so that it can receive light of a specific color from the filter unit. Multiple photoelectric conversion elements 211 cooperate to obtain a color image.

[0145] In this embodiment, a filter unit 212 can be disposed opposite to an absorption unit 221, so that all photoelectric conversion elements in an absorption unit receive light of the same color.

[0146] The logic circuit layer 203 may include multiple layers of metal wiring, which can be used to form logic circuits. Logic circuits include, but are not limited to, amplifier circuits, analog-to-digital converter circuits, and other related processing circuits. Multiple photoelectric conversion elements in the light absorption layer convert optical signals into electrical signals, which can then be transmitted to the logic circuit layer 203. The logic circuits in the logic circuit layer can process the electrical signals and transmit the processed electrical signals to other devices (e.g., processors).

[0147] Figure 12 This is a schematic diagram of another image sensor provided in an embodiment of this application. Figure 12 As shown, the image sensor 200 may further include an isolation structure 204. The isolation structure 204 is located on the logic circuit layer 203 and between two adjacent absorption sections 221. The material of the isolation structure 204 is an insulating material.

[0148] The height of the isolation structure 204 can be less than or equal to the height of the absorption section 221 (i.e., the thickness of the light absorption layer).

[0149] In some examples, the material of the isolation structure 204 may include silicon oxide, silicon nitride, silicon oxynitride, etc.

[0150] In some examples, the isolation structure 204 may be in the form of a grid, with multiple absorption portions 221 located in the multiple grids enclosed by the isolation structure 204.

[0151] In this embodiment, the material of the isolation structure 204 is an insulating material, which enables the isolation structure to improve or even avoid the problem that the charge generated in the absorption part 221 moves to the adjacent absorption part 221 and affects the amount of charge in the adjacent absorption part 221.

[0152] In some embodiments, such as Figure 12 As shown, the image sensor 200 may further include a plurality of optical lenses 205, which are located on the side of the filter layer 202 away from the light absorption layer 201. One optical lens 205 may correspond to one absorption section 221. The optical lens 205 can concentrate light into the absorption section 221 corresponding to that optical lens 205.

[0153] In some embodiments, such as Figure 12 As shown, the image sensor 200 may further include a planarization layer 206, which is located between the light absorption layer 201 and the filter layer 202. The planarization layer 206 is used to provide a flat surface to the filter layer 202, thereby facilitating the formation of the filter layer 202.

[0154] Figure 13 This application provides a method for fabricating an image sensor 200. For example... Figure 13As shown, the preparation method includes steps S100 to S300.

[0155] S100, such as Figure 14 As shown, a light-absorbing layer 201 is formed. The material of the light-absorbing layer 201 includes Si. x Ge 1-x-y Sn y The alloy has x and y values ​​greater than 0 and less than 1. The light absorption layer 201 includes multiple absorption sections 221, and the Si, Ge, and Sn elements in the multiple absorption sections 221 are composed in different proportions.

[0156] In some examples, such as Figure 14 The multiple absorption sections 221 shown are divided into a red absorption section 221a, a blue absorption section 221d, a first green absorption section 221b, and a second green absorption section 221c. At this time, refer to... Figure 14 Step S100 includes step S110.

[0157] S110. A red absorbing portion, a blue absorbing portion, a first green absorbing portion, and a second green absorbing portion are formed on different parts of the same surface of the substrate. The composition ratios of Si, Ge, and Sn elements in the red absorbing portion, the blue absorbing portion, and the first green absorbing portion are different. The composition ratios of Si, Ge, and Sn elements in the first green absorbing portion and the second green absorbing portion are the same.

[0158] For example, the substrate material may include silicon.

[0159] For example, step S110 may include steps S111 to S115.

[0160] S111, such as Figure 15 As shown, a sacrificial layer 102 is formed on a substrate 101. Exemplarily, the material of the sacrificial layer 102 may include silicon oxide.

[0161] In some examples, a deposition process can be used to form a sacrificial layer 102 on substrate 101.

[0162] S112, such as Figure 16 As shown, a portion of the sacrificial layer 102 is removed, exposing a portion of the surface of the substrate 101. Exemplarily, a dry etching process can be used to etch the sacrificial layer 102.

[0163] For example, before etching the sacrificial layer 102, a photoresist 103 can be formed on the surface of the sacrificial layer 102 away from the substrate 101, and the photoresist 103 can be patterned.

[0164] S113, such as Figure 17As shown, one of the red absorption portion 221a, blue absorption portion 221d, first green absorption portion 221b, and second green absorption portion 221c is formed on the exposed surface of the substrate 101. Figure 17 The red absorption section 221a is used as an example for illustration.

[0165] For example, a red absorber 221a can be formed on the exposed surface of the substrate 101 using a chemical vapor deposition process or a molecular beam epitaxy process.

[0166] S114, such as Figure 18 As shown, part of the sacrificial layer 102 is removed again, exposing part of the surface of the substrate 101.

[0167] For example, the sacrificial layer 102 can be etched again using a dry etching process.

[0168] Understandably, to protect the already formed absorption portion (e.g., red absorption portion 221a), photoresist 103 can be formed again on the surface of the already formed absorption portion. Before etching the sacrificial layer 102, the photoresist 103 is patterned to expose a portion of the sacrificial layer 102.

[0169] S115, such as Figure 19 As shown, one of the following is formed on the exposed surface of the substrate 101: a red absorber 221a, a blue absorber 221d, a first green absorber 221b, and a second green absorber 221c. Taking the formation of the red absorber 221a in step S113 as an example, one of the blue absorber 221d, the first green absorber 221b, and the second green absorber 221c can be formed in step S115. Figure 19 The first green absorption section 221b is used as an example for illustration.

[0170] Repeat steps S114 and S115 until... Figure 20 As shown, red absorber 221a, blue absorber 221d, first green absorber 221b, and second green absorber 221c are all formed on substrate 101. It is understood that the absorber formed during the repetition of step S115 is different from the absorber formed in the previous two steps.

[0171] In other examples, multiple absorption portions are a first absorption portion and a second absorption portion. For example... Figure 21 As shown, step S100 may include steps S120 and S130.

[0172] S120. A first absorption portion is formed on a substrate. The substrate includes a first sub-part and a second sub-part, the second sub-part being located on the periphery of the first sub-part, and the first absorption portion being located on the first sub-part.

[0173] S130. A second absorption portion is formed on the substrate, the second absorption portion and the first absorption portion are located on the same side of the substrate, and the second absorption portion is located on the second sub-part.

[0174] The composition ratios of Si, Ge, and Sn elements differ between the first and second absorption sections.

[0175] S200, such as Figure 22 As shown, a logic circuit layer 203 is formed on one side of the light absorption layer 201.

[0176] For example, a logic circuit layer 203 can be formed on one side of the light absorption layer using deposition and etching processes.

[0177] After step S200 and before step S300, the preparation method may further include step S400.

[0178] S400, such as Figure 23 As shown, substrate 101 is thinned or removed. For example, a chemical mechanical polishing process can be used to remove substrate 101.

[0179] S300, see reference Figure 24 A filter layer 202 is formed on the side of the light absorption layer 201 away from the logic circuit layer 203. The filter layer 202 includes a plurality of filter units 212, and one filter unit 212 corresponds to one absorption portion 221.

[0180] After step S300, for example, refer to Figure 24 Furthermore, multiple optical lenses 205 can be formed on the side of the filter layer 202 away from the light absorption layer.

[0181] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions conceived by those skilled in the art within the scope of the technology disclosed herein should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. An image sensor, characterized in that, Includes a light-absorbing layer, the material of which includes Si. x Ge 1-x-y Sn y The alloy, wherein x and y are both greater than 0 and less than 1; the light absorption layer includes multiple absorption sections, wherein the composition ratios of Si, Ge and Sn elements in the multiple absorption sections are different.

2. The image sensor according to claim 1, characterized in that, The plurality of absorption portions are a red absorption portion, a blue absorption portion, a first green absorption portion, and a second green absorption portion; The composition ratios of Si, Ge, and Sn elements in the red absorber, the blue absorber, and the first green absorber are different. The Si, Ge, and Sn elements in the first and second green absorption sections have the same composition ratio.

3. The image sensor according to claim 2, characterized in that, The light absorption layer includes multiple red absorption portions, multiple blue absorption portions, multiple first green absorption portions, and multiple second green absorption portions; The proportions of Si, Ge, and Sn elements in the plurality of red absorbers are the same; and / or, The proportions of Si, Ge, and Sn elements in the plurality of blue absorbers are the same; and / or, The proportions of Si, Ge, and Sn elements in the plurality of first green absorbers are the same; and / or, The proportions of Si, Ge, and Sn elements in the plurality of second green absorbers are the same.

4. The image sensor according to claim 2 or 3, characterized in that, The sum of the component proportions of Ge and Sn in the red absorption section is greater than the sum of the component proportions of Ge and Sn in the blue absorption section; And / or, The sum of the proportions of Ge and Sn elements in the red absorption section is greater than the sum of the proportions of Ge and Sn elements in the first green absorption section.

5. The image sensor according to claim 1 or 2, characterized in that, The light-absorbing layer includes a first region and a second region; The absorption portion located in the first region among the plurality of absorption portions is designated as the first absorption portion, and the absorption portion located in the second region among the plurality of absorption portions is designated as the second absorption portion; the composition ratios of the Si element, the Ge element, and the Sn element in the first absorption portion and the second absorption portion are different.

6. The image sensor according to claim 5, characterized in that, The light absorption layer includes a light receiving surface, which includes a first part and a second part, wherein the first part corresponds to the first region and the second part corresponds to the second region; The distance from the center of the light-receiving surface to the edge of the first part is less than or equal to 0.7 times the maximum distance from the center of the light-receiving surface to the edge of the second part.

7. The image sensor according to claim 5 or 6, characterized in that, The sum of the component proportions of Ge and Sn in the first absorption section is greater than the sum of the component proportions of Ge and Sn in the second absorption section; or, The sum of the component proportions of Ge and Sn in the first absorption section is less than the sum of the component proportions of Ge and Sn in the second absorption section.

8. The image sensor according to any one of claims 1 to 7, characterized in that, The light-absorbing layer includes a first sublayer and a second sublayer stacked together, wherein the material of the first sublayer includes Si. x Ge 1-x-y Sn y The alloy, wherein the material of the second sublayer includes at least one of Si, SiGe, and Ge; the lattice constant of the second sublayer is less than the lattice constant of the first sublayer.

9. The image sensor according to any one of claims 1 to 8, characterized in that, Also includes: A logic circuit layer is located on one side of the light absorption layer; A filter layer is located on the side of the light absorption layer away from the logic circuit layer; the filter layer includes multiple filter units, one filter unit corresponding to one absorption portion.

10. The image sensor according to claim 9, characterized in that, Also includes: An isolation structure is located on the logic circuit layer and between two adjacent absorption sections; The material of the isolation structure is an insulating material.

11. A method for fabricating an image sensor, characterized in that, include: Forming a light-absorbing layer; The material of the light-absorbing layer includes Si. x Ge 1-x-y Sn y An alloy in which x and y are both greater than 0 and less than 1; the light absorption layer includes multiple absorption sections, and the Si, Ge, and Sn elements in the multiple absorption sections are in different proportions. A logic circuit layer is formed on one side of the light absorption layer; A filter layer is formed on the side of the light absorption layer away from the logic circuit layer; the filter layer includes a plurality of filter units, one filter unit corresponding to one absorption portion.

12. The preparation method according to claim 11, characterized in that, The plurality of absorption portions are a red absorption portion, a blue absorption portion, a first green absorption portion, and a second green absorption portion; the formation of the light absorption layer includes: The red absorbing portion, the blue absorbing portion, the first green absorbing portion, and the second green absorbing portion are formed on different parts of the same surface of the substrate, respectively; the composition ratio of Si, Ge, and Sn elements in the red absorbing portion, the blue absorbing portion, and the first green absorbing portion is different; the composition ratio of Si, Ge, and Sn elements in the first green absorbing portion and the second green absorbing portion is the same.

13. The preparation method according to claim 11, characterized in that, The plurality of absorption portions are a first absorption portion and a second absorption portion; the formation of the light absorption layer includes: A first absorption portion is formed on a substrate; the substrate includes a first sub-part and a second sub-part, the second sub-part being located on the periphery of the first sub-part, and the first absorption portion being located on the first sub-part; A second absorption portion is formed on the substrate, the second absorption portion and the first absorption portion are located on the same side of the substrate, and the second absorption portion is located on the second sub-portion; The composition ratios of Si, Ge, and Sn elements in the first and second absorption sections are different.

14. A camera module, characterized in that, include: The image sensor as described in any one of claims 1 to 10; The lens assembly is located on the light-incident side of the image sensor.

15. An electronic device, characterized in that, include: The camera module as described in claim 14; The processor is electrically connected to the image sensor in the camera module.

Images