Image sensor, preparation method, imaging method and electronic device

Abstract

The present invention provides an image sensor structure, an electronic device, a preparation method and an imaging method, wherein the structure includes: a first type of pixel and a second type of pixel; a modulation function layer, which at least includes a light shielding portion located on the first type of pixel; based on the modulation function layer, the incident light enters the second type of pixel and generates a derived light, the derived light enters the first type of pixel, and a first signal is generated based on the derived light, the second type of pixel generates a second signal based on the incident light, and each second type of pixel corresponding to the same first type of pixel responds to the same type of light signal. The present invention can obtain different light signals based on the first type of pixel and the second type of pixel to improve the dynamic range of the image, and effectively realize the acquisition of photos or videos with flickering light sources. In addition, the light shielding portion and the light guiding portion can be prepared simultaneously, the light signals of the first type of pixel and the second type of pixel can be modulated, and crosstalk between different types of light signals can be effectively prevented, the preparation process can be simplified, and the efficiency can be improved.

Description

Technical Field

[0001] The present invention belongs to the field of image sensor manufacturing and imaging technology, and in particular relates to an image sensor, a preparation method, an imaging method and electronic equipment. Background Art

[0002] Image sensors use the photoelectric conversion function of photoelectric devices to convert the light image on the photosensitive surface into an electrical signal that is proportional to the light image. Depending on the components, they can be divided into two categories: CCD (charge coupled device) and CMOS (metal oxide semiconductor device). With the continuous development of CMOS image sensor (CIS) design and manufacturing technology, CMOS image sensors have gradually replaced CCD image sensors and become the mainstream. Among them, CMOS image sensors can be divided into two categories: FSI (FrontSide Illumination) and BSI (Back Side Illumination).

[0003] However, in some applications, CMOS image sensors need to capture scenes with a large dynamic range to obtain clear images in low-light conditions to bright light conditions. At other times, it is necessary to capture photos or videos of flickering light sources, for example, to capture scenes with traffic lights. At least a portion of the pixels in the CMOS image sensor need to be exposed for a long time to be immune to the flicker of certain light sources (LFM, light flicker mitigation); at the same time, in this scenario, the pixels exposed for a long time cannot be overexposed, so the image sensor needs to have a large dynamic range.

[0004] Therefore, it is necessary to provide an image sensor, a preparation method, an imaging method and an electronic device to solve the above problems in the prior art. Summary of the invention

[0005] In view of the shortcomings of the prior art described above, an object of the present invention is to provide an image sensor pixel structure, a preparation method, an imaging method and an electronic device, which are used to solve the problems in the prior art that the dynamic range of image sensors is difficult to effectively improve and that photos or videos with flickering light sources are difficult to effectively obtain.

[0006] To achieve the above object and other related objects, the present invention provides an image sensor, comprising:

[0007] A first type of pixel, the first type of pixel comprising a first photosensitive area;

[0008] A second type of pixel, wherein the second type of pixel comprises a second photosensitive area, and a spacing area is provided between the first type of pixel and the second type of pixel; and

[0009] The modulation function layer at least comprises a light shielding portion, wherein the light shielding portion is located on the first type of pixel to shield incident light;

[0010] Based on the modulation functional layer, incident light enters the area corresponding to the second-type pixel and generates derived light, and the derived light enters the first-type pixel at least through the spacing area, wherein the first photosensitive area receives the derived light to generate a first signal, and the second photosensitive area receives the incident light to generate a second signal, and each of the second-type pixels corresponding to the same first-type pixel responds to the same type of light signal.

[0011] Optionally, the side surface of the first type of pixel is composed of a plurality of light incident surfaces, and the derived light enters the first photosensitive area of ​​the first type of pixel at least through the light incident surface, wherein each of the light incident surfaces corresponds one-to-one to the second type of pixel or other first type of pixels.

[0012] Optionally, the second-category pixels are nearest neighbor pixels of the first-category pixels, and at least the second-category pixels corresponding to the same first-category pixel are covered with the same color filter, so that the second-category pixels respond to the same type of light signal.

[0013] Optionally, the image sensor further includes a third type of pixels, and the corresponding area between the third type of pixels and the first type of pixels is smaller than 1 / 10 of the corresponding area between the second type of pixels and the first type of pixels, or the third type of pixels and the first type of pixels are spaced apart.

[0014] Optionally, the image sensor includes a plurality of pixel units, each of the pixel units includes a plurality of pixel sub-units, and each of the pixel sub-units includes at least one pixel of the first type and at least one pixel of the second type.

[0015] Optionally, the image sensor also includes a plurality of color filter unit layers, and the color filter unit layers correspond one-to-one to the pixel sub-units, wherein the color filter unit layers are located on the second type of pixels or cover both the first type of pixels and the second type of pixels, and the pixel unit obtains a corresponding type of light signal based on the color filter unit layers corresponding to each of the pixel sub-units, so as to obtain a corresponding image signal based on the pixel unit.

[0016] Optionally, the pixel unit includes at least a first pixel sub-unit responding to red light, a second pixel sub-unit responding to green light, and a third pixel sub-unit responding to blue light, and each pixel sub-unit corresponds to a first light-shielding portion, a second light-shielding portion, and a third light-shielding portion, respectively, and the sizes of the first type of pixels of different pixel sub-units in the pixel unit are the same, wherein the size of the first light-shielding portion is larger than the size of the second light-shielding portion, which is larger than the size of the third light-shielding portion, or the sizes of the light-shielding portions of different pixel sub-units are the same, and the size of the light-shielding portion is larger than, smaller than or equal to the size of the corresponding first type of pixels.

[0017] Optionally, the size of the second light shielding portion is the same as the size of the corresponding first type of pixel, the size of the first light shielding portion is not greater than 120% of the size of the second light shielding portion, and the size of the third light shielding portion is not less than 70% of the size of the second light shielding portion.

[0018] Optionally, the arrangement of pixels in the pixel sub-unit includes: the pixel sub-unit includes a central area and a peripheral area surrounding the central area, the first type of pixels are located in the central area, and the second type of pixels are at least located in the peripheral area; or, the pixel sub-unit includes an edge area, the first type of pixels are located in the edge area, and the first type of pixels located in the edge area have an exposed light incident contact portion, and the light incident contact portion is in contact with the first type of pixels of an adjacent pixel sub-unit located in the edge area.

[0019] Optionally, the pixel unit includes four pixel sub-units, and the arrangement of the pixel sub-units includes: the pixels of the pixel sub-units form a 3×3 structure, the first type of pixels are located in the center, and the second type of pixels are located around; or, the pixels of the pixel sub-units form a 2×2 structure, the first type of pixels are located in a corner, and the second type of pixels are located in the remaining positions; or, the pixels of the pixel sub-units form an improved 2×2 structure, the first type of pixels are located in the center and have four light-receiving sides, and four second-type pixels are located around the first type of pixels and correspond one-to-one to the four light-receiving sides.

[0020] Optionally, the pixel structure also includes an auxiliary modulation structure, which is at least arranged on a side of the second type of pixel away from the incident light. The incident light passing through the second type of pixel is modulated by the auxiliary modulation structure and enters the first type of pixel to obtain modulated light. The first type of pixel obtains the first signal based on the modulated light and the derived light.

[0021] Optionally, the image sensor further includes an intermediate modulation transition layer located between the substrate and the modulation functional layer.

[0022] Optionally, the thickness of the intermediate modulation transition layer is greater than 20 nm.

[0023] Optionally, the material of the intermediate modulation transition layer is a single-layer oxide transition layer or a stacked layer composed of multiple oxides.

[0024] Optionally, the shading rate of the shading portion is greater than 98%.

[0025] Optionally, the first type of pixels and the second type of pixels have the same shape and size and are distributed in a periodic array.

[0026] Optionally, the modulation functional layer further includes a light guiding portion, and the light guiding portion is located correspondingly on the spacing area, so that the modulation functional layer has a plurality of light entrances corresponding to the second type of pixels, and the incident light enters the second type of pixel area through the light entrances.

[0027] Optionally, the modulation function layer composed of the light guiding portion and the light shielding portion is a structure formed based on the same process.

[0028] Optionally, the material of the light shielding portion includes at least one of tungsten, aluminum, titanium, titanium nitride, tantalum and tantalum nitride.

[0029] Optionally, the material of the light guiding portion includes at least one of tungsten, aluminum, titanium, titanium nitride, tantalum, tantalum nitride and a material having a refractive index smaller than a refractive index of a filling material layer between adjacent light guiding portions.

[0030] In addition, the present invention further provides a method for preparing an image sensor as described in any one of the above solutions, the method comprising the following steps:

[0031] providing a substrate;

[0032] preparing the first type of pixels, the second type of pixels and the spacer in the substrate;

[0033] The modulation functional layer is prepared on the substrate.

[0034] Optionally, when the modulation functional layer further includes the light guiding portion, the steps of preparing the modulation functional layer include:

[0035] depositing an initial layer of barrier material on the substrate;

[0036] preparing a mask layer on the initial barrier material layer; and

[0037] The initial blocking material layer is patterned based on the mask layer to simultaneously obtain the light shielding portion and the light guiding portion.

[0038] Optionally, when the modulation functional layer further includes the light guiding portion, the steps of preparing the modulation functional layer include:

[0039] depositing an initial layer of barrier material on the substrate;

[0040] preparing a light-guiding lithography mask layer on the initial barrier material layer;

[0041] Patterning the initial blocking material layer based on the light-guiding etch mask layer to obtain the light-guiding portion and a plurality of openings corresponding to pixels in the substrate, wherein the openings include the light entrance; and

[0042] A light shielding material is deposited to fill the opening corresponding to the first type of pixel to obtain the light shielding portion.

[0043] Optionally, the preparation method further comprises preparing a filter array and a microlens in sequence after preparing the modulation functional layer.

[0044] In addition, the present invention also provides an imaging method based on the image sensor described in any one of the above-mentioned schemes, and the imaging method includes the following steps: controlling the first type of pixels to have a first exposure time, the second type of pixels to have a second exposure time, and the first exposure time is greater than the second exposure time.

[0045] Optionally, the second exposure time is greater than 1 / 100 of the first exposure time.

[0046] In addition, the present invention also provides an electronic device, comprising the image sensor described in any one of the above solutions.

[0047] As described above, the image sensor and the method for preparing the same, the electronic device based on the image sensor and the imaging method of the present invention have at least the following beneficial effects:

[0048] The present invention designs a first type of pixel with a shading portion on the top and a second type of pixel without a shading portion on the top that can receive light, and the derived light based on the second type of pixel is used as the response light of the first type of pixel, and each second type of pixel corresponding to the same first type of pixel responds to the same type of light signal, so that the first type of pixel receives the same type of derived light to generate a first signal, and at the same time, the second type of pixel generates a second signal based on the incident light, so that an effective image signal can be obtained based on the first signal of the first type of pixel and the second signal of the second type of pixel, so as to improve the dynamic range of the image, and can effectively realize the acquisition of photos or videos with light source flickering based on the above signals. In addition, based on the design of the present invention, the shading portion and the light guiding portion can be prepared simultaneously, the light signals of the first type of pixel and the second type of pixel can be modulated, and crosstalk between different types of light signals can be effectively prevented, which can simplify the preparation process and improve efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0049] Figure 1 Shown is a system framework diagram of an image sensor structure provided in an embodiment of the present invention.

[0050] Figure 2 Shown is a process flow chart for preparing the image sensor pixel structure provided in the first embodiment of the present invention.

[0051] Figure 3-17 Shown is a schematic diagram of the structure obtained in each step of preparing the pixel structure of an image sensor according to an embodiment of the present invention.

[0052] Figure 18-20 Shown is a schematic diagram of the structure obtained in each step of preparing the pixel structure of the image sensor in the second embodiment of the present invention.

[0053] Figure 21-28 Shown is a schematic diagram of the arrangement of each pixel sub-unit and its corresponding pixel in a pixel unit based on the first type of pixel and the second type of pixel design provided in the third embodiment of the present invention.

[0054] Component number description

[0055] 101 Base

[0056] 101a Page 1

[0057] 101b Side 2

[0058] 101c thinned surface

[0059] 102 First Isolation Structure

[0060] 103 First-class pixels

[0061] 103a First photosensitive area

[0062] 103b Type I pixel transfer gate

[0063] 104 Second type of pixels

[0064] 104a Second photosensitive area

[0065] 104b Type II pixel transfer gate

[0066] 105 Interconnect Layer

[0067] 106 Support substrate

[0068] 107 Thinned substrate

[0069] 108 Second isolation structure

[0070] 109 Interval

[0071] 110 Transition layer

[0072] 111 Initial barrier

[0073] 111a Light inlet

[0074] 112, 201 Shading part

[0075] 113 Light guide

[0076] 114 Dielectric layer

[0077] 115 filter unit layer

[0078] 116 Microlens

[0079] 117 Auxiliary modulation structure

[0080] 202 Modulation Function Layer

[0081] 300, 400, 500, 600 pixel units

[0082] 301, 302, 303, 304, 401, 402, pixel subunit 403、404、501、502、503、504、 601, 602, 603, 604

[0085] Steps S1 to S3 DETAILED DESCRIPTION

[0086] The following describes the embodiments of the present invention through specific examples, and those skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present invention. For example, when describing the embodiments of the present invention in detail, for the sake of convenience, the cross-sectional view showing the device structure will not be partially enlarged according to the general proportion, and the schematic diagram is only an example, which should not limit the scope of protection of the present invention. In addition, in actual production, the three-dimensional dimensions of length, width and depth should be included.

[0087] For the convenience of description, spatial relationship words such as "under", "below", "lower than", "below", "above", "on", etc. may be used here to describe the relationship between one element or feature shown in the drawings and other elements or features. It will be understood that these spatial relationship words are intended to include other directions of the device in use or operation, in addition to the directions depicted in the drawings. In addition, when a layer is referred to as being "between" two layers, it can be the only layer between the two layers, or there can be one or more layers in between. In addition, "between..." used in the present invention includes two endpoint values. In the context of the present application, the structure described as a first feature "above" a second feature may include an embodiment in which the first and second features are formed in direct contact, and may also include an embodiment in which another feature is formed between the first and second features, so that the first and second features may not be in direct contact.

[0088] It should be noted that the illustrations provided in this embodiment are only used to illustrate the basic concept of the present invention in a schematic manner, and therefore the illustrations only show components related to the present invention rather than being drawn according to the number, shape and size of components in actual implementation. In actual implementation, the type, quantity and proportion of each component may be changed arbitrarily, and the component layout may also be more complicated.

[0089] The contents of the present invention are described in detail below in conjunction with the accompanying drawings provided in the present invention.

[0090] Figure 1 The following is a basic structural diagram of an image sensor system. Figure 1As shown in , the image sensor includes a readout circuit and a control circuit connected to a pixel array, a functional logic unit is connected to the readout circuit, and performs logical control on the reading of the pixel circuit; the readout circuit and the control circuit are connected to the state register to realize the reading control of the pixel array. The pixel array includes a plurality of pixels arranged in rows (R1, R2, R3...Ry) and columns (C1, C2, C3...Cx), and the pixel signal output by the pixel array is output to the readout circuit via the column line. In one embodiment, after each pixel acquires image data, the image data is read out by a readout circuit of a readout mode specified by the state register, and then transmitted to the functional logic unit. In a specific application, the readout circuit may include an analog-to-digital conversion (ADC) circuit, an amplification circuit, and others. In some application embodiments, the state register may include a programmed selection system to determine whether the readout system is read out through a rolling exposure mode (rolling shutter) or a global exposure mode (global shutter). The functional logic unit may only store image data or image data applied or processed by image effects. In one embodiment, the readout circuit can read out image data one row at a time along the readout column line, or can read out the image data in various other ways. The operation of the control circuit can be determined by the current setting of the status register. For example, the control circuit generates a shutter signal for controlling image acquisition. In some embodiments, the shutter signal can be a global exposure signal so that all pixels of the pixel array simultaneously acquire their image data through a single acquisition window. In some other embodiments, the shutter signal can be a rolling exposure signal, and each pixel row is continuously read through the acquisition window.

[0091] However, in the prior art, in some applications, CMOS image sensors need to capture scenes with a large dynamic range to obtain clear images in both low-light and bright-light conditions. At other times, it is necessary to capture photos or videos of flashing light sources, such as capturing scenes with traffic lights. This is currently difficult to solve effectively. The present invention, based on the design of pixel structure, etc., can obtain different light signals, obtain an image sensor with a high dynamic range, and effectively solve the above problem.

[0092] in, Figure 2-20 Shown is a process flow chart of the image sensor preparation process of the present invention and a cross-sectional schematic diagram of the structure obtained in each step during the preparation process. Figure 21-28 Shown are top-view schematic diagrams of different examples of pixel structure arrangements of the image sensor of the present invention.

[0093] This will be described in detail in different embodiments below.

[0094] Embodiment 1:

[0095] See also Figure 2-17As shown, this embodiment 1 provides a structure of an image sensor and a method for manufacturing the same, wherein Figure 15-17 As shown, the image sensor structure provided by the present invention is shown, which includes:

[0096] A first type of pixel 103 includes a first photosensitive area 103a; a second type of pixel 104 includes a second photosensitive area 104a; and a spacing area 109 is provided between the first type of pixel 103 and the second type of pixel 104; in addition, the image sensor structure further includes a modulation functional layer, and the modulation functional layer at least includes a shading portion 112 located on the first type of pixel 103.

[0097] Wherein, based on the modulation function layer, the light shielding portion 112 is located on the first type of pixel 103 to shield the incident light, so that the incident light cannot enter the first type of pixel, and the incident light will enter the second type of pixel 104 without shielding by the light shielding portion. In addition, the incident light in the corresponding area of ​​the second type of pixel 104 (which may be the second type of pixel and the area above it) generates derived light, and the derived light enters the first type of pixel 103 at least through the spacer area.

[0098] It should be noted that the first type of pixel in the present invention refers to a type of pixel with the shading portion formed on the top, and the second type of pixel refers to a pixel without the shading portion formed on the top and can provide a light source (derivative light generated after the incident light is incident) for the corresponding first type of pixel. In addition, for the derived light, it can be that after the incident light enters the second type of pixel, diffraction of the incident light occurs in the pixel, and the diffracted light enters the first type of pixel, and this part of the diffracted light constitutes the derived light. In addition, the derived light can also be the incident light entering the second type of pixel, and before entering the second type of pixel, it enters the first type of pixel from the spacing area between the first type of pixel and the second type of pixel or the area extending upward from the spacing area, and this part of the light also constitutes the derived light, which enters the first type of pixel to obtain the first signal.

[0099] Based on the above design of the present invention, the derived light is used as the light signal of the first type of pixel 103, and the first photosensitive area 103a receives the derived light to generate a first signal; the incident light is used as the light signal of the second type of pixel 104, and the second photosensitive area 104a receives the incident light to generate a second signal, and each of the second type of pixels 104 corresponding to the same first type of pixel 103 responds to the same type of light signal, and the first type of pixel and the corresponding second type of pixel have consistent spectral lines.

[0100] In addition, it should be noted that the "same type of light signal" here can refer to light of the same color obtained after passing through the same color filter, such as a first-type pixel surrounded by second-type pixels with a red filter on top, so that these second-type pixels respond to red light, and the corresponding first-type pixels also respond to the derived red light signal. In addition, it can also be provided with a green filter, a blue filter, an infrared filter, or no filter of any color to collect visible light signals. Of course, the "same type of light signal" can also be other settings for the second-type pixels based on actual needs.

[0101] Therefore, based on the above design, the image sensor structure of the present invention can obtain different light signals based on the first type of pixels and the second type of pixels. The first type of pixels only use the derived light of the second type of pixels to obtain image information, thereby improving the dynamic range of the image sensor based on different signals, and can also be suitable for obtaining images with flickering light sources.

[0102] The image sensor structure and preparation method of the present invention will be described in detail below with reference to the accompanying drawings. Figure 2 The sequence shown in the figure does not represent the preparation sequence of all image sensor pixel structures protected by the present invention, and those skilled in the art may change it according to the actual process steps. Figure 2 Only one example of the present invention is shown.

[0103] First, if Figure 2 S1 and Figure 3 As shown, step S1 is performed to provide a substrate 101 .

[0104] Specifically, the substrate 101 can be any structure in the field of image sensors for preparing various functional areas of image sensors, such as preparing photosensitive elements and various control transistors of CMOS image sensors based on the substrate 101. The substrate 101 can be a structure composed of a single material layer, including but not limited to a silicon substrate, and the elements in each area are prepared in the silicon substrate, which can be single crystal silicon, single crystal germanium, polycrystalline silicon, amorphous silicon, or silicon germanium compounds.

[0105] In addition, the substrate 101 can also be a stacked structure composed of two or more material layers, and each region is prepared in any required layer. For example, the substrate 101 includes a silicon substrate and an epitaxial layer (EPI) formed on the silicon substrate, and the photosensitive element and various control transistors are prepared in the epitaxial layer. For example, a back-illuminated (BSI) image sensor can be prepared based on the above structure. In addition, the substrate 101 can also be a silicon on insulator (Silicon On Insulator, SOI). In addition, the substrate 101 can also be a structure with N-type doping or P-type doping so that the device meets the functional requirements.

[0106] See also Figure 3 As shown, in one example, the substrate 101 has a first surface 101a and a second surface 101b opposite to each other. In an optional example, the first surface 101a and the second surface 101b may be formed by the opposite front and back sides of the substrate, such as the front and back sides of a silicon substrate. In other examples, the first surface 101a may be formed by a surface of an epitaxial layer formed on the substrate, and the second surface 101b may be formed by another surface of the substrate away from the epitaxial layer.

[0107] Then, if Figure 2 S2 and Figure 4-7 As shown, step S2 is performed to prepare the first type of pixel 103, the second type of pixel 104 and the spacer 109 between the first type of pixel 103 and the second type of pixel 104 in the substrate 101. The first type of pixel 103 includes a first photosensitive area 103a, and the second type of pixel 104 includes a second photosensitive area 104a.

[0108] Specifically, the first type of pixel 103 and the second type of pixel 104 may be pixels (Pixel) in a conventional image sensor chip. The first photosensitive area 103a and the second photosensitive area 104a may receive light signals and generate photoelectrons. In one example, the first photosensitive area 103a and the second photosensitive area 104a include photodiodes, and pixel structures such as PP (Passive Pixel), AP (Active Pixel), and PPD (Pinned Photodiode Pixel) may be formed based on the photodiodes. Of course, the first photosensitive area 103a and the second photosensitive area 104a may also be other structures that can convert light signals into electrical signals.

[0109] In addition, the first type of pixel 103 and the second type of pixel 104 may also include other transistor structures, such as a field effect transistor electrically connected to the photodiode. For example, taking the first type of pixel 103 as an example, the first type of pixel 103 may also include a transfer transistor TX having a transfer gate 103b. In another example, a floating diffusion node FD is also formed in the first type of pixel 103. Of course, other field effect transistors may also be included, such as a reset transistor RST, a source follower transistor SF, and a row selection transistor RS, to form a 3T, 4T, 5T, etc. pixel structure. Among them, the types of the above-mentioned transistors are all selected as N-type in this embodiment, and it can be understood that they can also be P-type in their implementation. Similarly, the second type of pixel 104 may also have a similar setting, such as having a transfer gate 104b. In addition, the number of the first type of pixel 103 and the second type of pixel 104, as well as the number and arrangement of internal transistors, can be designed according to actual needs, and are not overly restricted here.

[0110] See also Figure 4-7 As shown, in a specific example, a specific method for preparing the first type of pixel 103, the second type of pixel 104 and the isolation region 109 is provided, and the back-illuminated CMOS image sensor process is used as an example for illustration. Of course, the structural design of the present invention can also be applied to the existing front-illuminated image sensor, which will not be described in detail here.

[0111] The following is a description of each execution step and the structure obtained in the execution step:

[0112] First, if Figure 4 As shown, a first isolation structure 102 is prepared in the substrate 101, and the first isolation structure 102 isolates each pixel. For example, the first isolation structure 102 may be located between adjacent first-type pixels 103 and second-type pixels 104, or between adjacent first-type pixels 103 and first-type pixels 103, or between adjacent second-type pixels 104 and second-type pixels 104, so as to achieve isolation between pixels.

[0113] As an example, the first isolation structure 102 may be an STI (Shallow Trench Isolation) structure. In other examples, an ion implantation region may be used to form a potential difference based on the ion implantation region to achieve isolation, such as a P-type doped region. The first isolation structure 102 may be prepared using an existing STI or ion implantation process.

[0114] In one example, the first isolation structure 102 and each transistor are fabricated from the first surface 101 a of the substrate 101 .

[0115] In addition, see Figure 4 As shown, after forming the first isolation structure 102, the step of preparing each transistor in the substrate between each first isolation structure, such as an N-type MOS transistor, is also included to prepare a complete pixel circuit element. Only the transmission gate 103b corresponding to the first type pixel 103 and the transmission gate 104b corresponding to the second type pixel 104 are shown in the figure.

[0116] Then, if Figure 5 As shown, the method further includes the step of continuously forming an interconnection layer 105 and a supporting substrate 106 on the substrate 101. In one example, the interconnection layer and the supporting substrate are continuously prepared on the first surface 101a of the substrate 101.

[0117] Specifically, the interconnection layer 105 and the support substrate 106 can be prepared using existing structures and processes, and the interconnection of various transistors can be realized based on the interconnection layer 105, such as the interconnection layer 105 can include a metal layer and a dielectric layer. In addition, the support substrate 106 can provide support after the substrate 101 is flipped over to continue to complete the preparation of the image sensor, and the required logic circuit can be set in the support substrate 106 by means commonly used in the art. Of course, before forming the interconnection layer 105 and the support substrate 106, the first surface 101a of the substrate 101 can also be processed or a required material layer can be formed on the first surface 101a, which are all within the protection scope of the present invention.

[0118] Then, if Figure 6 As shown, the substrate 101 is flipped over to perform other steps on the other side. In one example, after flipping the substrate 101, the second side 101b faces upward, the first side 101a faces downward, and other structures of the image sensor are continuously prepared on one side of the second side 101b, such as obtaining a back-illuminated image sensor through the above steps.

[0119] Specifically, after turning over the substrate 101, a step of thinning the substrate 101 may be further included to obtain a thinned substrate 107 and form a thinned rear surface 101c. In one example, after the thinning step, the depths of the first photosensitive area 103a and the second photosensitive area 104a are defined, and a portion of the thinned rear surface 101c constitutes a surface of the first photosensitive area 103a and the second photosensitive area 104a, such as a light-receiving surface of a back-illuminated image sensor.

[0120] As an example, the first photosensitive area 103a and the second photosensitive area 104a have the same depth, the first isolation structure 102 has a depth less than the depths of the first and second isolation structures, and after thinning, there is still a gap between the end of the first isolation structure 102 away from the first surface 101a and the thinned surface 101c. In addition, the dimensions of the first photosensitive area 103a and the second photosensitive area 104a in other directions may also be the same, so as to obtain the first photosensitive area and the second photosensitive area having the same structure.

[0121] In a further optional example, each pixel of the image sensor has the same shape and the same size at all locations, such as each pixel in a top view is a square shape with equal sides, thereby forming a plurality of pixel arrays arranged in a periodic array.

[0122] Then, if Figure 7As shown, the method further includes preparing a second isolation structure 108 in the flipped substrate 101, wherein the second isolation structure 108 corresponds to the first isolation structure 102 one by one to form the isolation region 109 located between adjacent pixels (such as the first type of pixel 103 and the second type of pixel 104). In one example, the central axes of the first isolation structure 102 and the second isolation structure 108 forming the same isolation region 109 coincide.

[0123] In one example, the second isolation structure 108 may be a back side deep trench isolation (BDTI) structure, which may be manufactured using an existing process. In addition, the second isolation structure 108 may further penetrate the thinned substrate 107 .

[0124] Finally, if Figure 2 S3 and Figure 8-13 As shown, step S3 is performed to prepare the modulation functional layer on the substrate, and the modulation functional layer at least includes a shading portion 112, and the shading portion 112 is located on the first type of pixel 103 to block incident light and prevent the incident light from entering the first type of pixel 103.

[0125] As an example, Fig.10 As shown, the modulation functional layer also includes a light guiding portion 113, and the light guiding portion 113 is located correspondingly on the spacer area 109. The light guiding portion 110 and the light shielding portion 112 form a plurality of light entrances 111a corresponding to the second type of pixels 104, and the incident light enters the second type of pixels 104 through the light entrances 111a.

[0126] As an example, see Figure 9-10 As shown, a method for forming the modulation functional layer is provided:

[0127] like Fig. 9 As shown, first, an initial barrier material layer 111 is deposited on the substrate. It can be understood by those skilled in the art that the substrate is a thinned substrate 107 at this time; then, a mask layer (not shown in the figure) is prepared on the initial barrier material layer 111, and the mask layer can be prepared by an existing photolithography process; Fig.10 As shown, finally, the initial blocking material layer 111 is patterned based on the mask layer to obtain the light shielding portion 112 and the light guiding portion 113 at the same time.

[0128] Specifically, the light shielding portion 112 is used to shield the incident light directed to the first type of pixel 103, and the light guiding portion 113 is formed on the spacing area and forms a light entrance, based on which the incident light enters the second type of pixel 104, and the light guiding portion 113 can also prevent crosstalk of incident light between adjacent pixels.

[0129] As an example, the shading rate of the shading portion 112 is greater than 98%, for example, it can be 99% or 100%.

[0130] In one example, the modulation functional layer (including the light shading portion 112 and the light guiding portion 113) can adopt an existing metal grid, that is, the preparation of the light shading portion 112 and the light guiding portion 113 can be completed simultaneously based on the existing metal grid preparation process, which greatly simplifies the process while modulating the light.

[0131] As an example, the material of the shading portion includes at least one of tungsten, aluminum, titanium, titanium nitride, tantalum and tantalum nitride, and may be a material layer formed by any one of the above materials, or a stack of material layers formed by the above different materials.

[0132] In addition, the material of the light guide portion includes at least one of tungsten, aluminum, titanium, titanium nitride, tantalum, tantalum nitride and a material having a refractive index less than the refractive index of the material layer filled between adjacent light guide portions. It can be a material layer formed by any of the above materials, or a stack of material layers formed by the above different materials. In one example, the material of the light guide portion 113 is a material having a refractive index less than the refractive index of the material layer filled between adjacent light guide portions 113. It can be a material layer composed of a compound formed by Si-Al-O.

[0133] See also Figure 8 As shown, as an example, the image sensor further includes an intermediate modulation transition layer 110 located between the substrate and the modulation functional layer.

[0134] As an example, the thickness of the intermediate modulation transition layer 110 is greater than 20 nm, such as 30 nm, 50 nm, or 100 nm, so as to allow a portion of incident light to enter the first type of pixel from the portion of the transition layer above the spacer based on actual needs.

[0135] As an example, the material of the intermediate modulation transition layer is a single-layer oxide transition layer or a stack of multiple oxides, for example, a single-layer silicon oxide structure layer, and of course, a stack of two or more oxide layers.

[0136] The transition layer 110 can be prepared by using existing atomic layer deposition, physical vapor deposition, chemical vapor deposition, and thermal oxidation processes.

[0137] See also Fig.11 and Fig.12As shown, as an example, for a certain first-type pixel 103 and a light shielding portion 112 located above and corresponding to it, the size of the light shielding portion 112 is greater than, less than or equal to the size of the corresponding first-type pixel 103. By flexibly adjusting the size of the light shielding portion and the corresponding first-type pixel, it is possible to obtain the required amount of diffracted light according to needs.

[0138] In one example, a direction is defined in the plane where the surface of the substrate 101 is located, and the distance between the central axes of the isolation region 109 at the periphery of the first type of pixel 103 is defined as the size L2 of the first type of pixel in the direction. In addition, in the plane, the distance of the edge of the shading portion 112 corresponding to the direction is defined as the size L1 of the shading portion, wherein the size of the shading portion 112 is greater than (e.g. Fig.11 as shown), less than (as shown Fig.12 The size of the first type of pixel 103 is equal to (not shown in the figure) or equal to (not shown in the figure). It should be noted that, taking "greater than" as an example, it means that the size of the shading portion in all directions in the plane where the substrate surface is located is greater than the size of the first type of pixel. For example, the top view shape of the first type of pixel is a square, and the top view shape of the shading portion is also a square, and the centers of the two coincide, and the side length of the shading portion is greater than the side length of the first type of pixel. This description also applies to the case of less than. In addition, the "equal to" mentioned here means that the outer edge of the shading portion coincides with the central axis position of the spacing area outside the corresponding first type of pixel below.

[0139] See also Figure 13-16 As shown, the image sensor pixel structure further includes a color filter unit layer 115 and micro lenses 116. The color filter unit layer 115 can be an existing color filter array (Color Filter Array), which is prepared by using an existing color filter preparation process, and the micro lenses 116 can be prepared by using an existing micro lens process.

[0140] It should be noted that the filter unit layer 115 allows light of one color to pass through, so as to obtain the light signal of the color based on the corresponding pixel, that is, the color filter mentioned above. As an example, the filter unit layer 115 can only pass red light, green light, blue light, or infrared light. In addition, in other examples, the filter unit layer 115 may not be provided, so that each second type of pixel passes visible light.

[0141] See also Fig.14As shown, in one example, after the modulation function layer is formed, a dielectric layer 114 is filled at the position of the light entrance 111a above the second type of pixel 104, and then the color filter unit layer is prepared on the dielectric layer 114 and the modulation function layer. The material of the dielectric layer 114 includes but is not limited to silicon oxide. In addition, in another optional example, as Fig.16 As shown, after the modulation function layer is prepared, the filter unit layer 115 can be directly prepared in the light entrance 111a above the second type of pixel 104, so that the filter unit layer 115 is formed in the space defined by the light guiding part and the light shielding part, which is further beneficial to prevent crosstalk of adjacent pixel light signals.

[0142] In addition, in one example, Fig.15 and Fig.16 As shown, the microlenses 116 are arranged in a one-to-one correspondence with the pixels. For example, each of the first-type pixels 103 corresponds to a microlens 116, and each of the second-type pixels 104 corresponds to a microlens 116. Of course, other microlens arrangements may also be used, such as four pixels sharing the same microlens.

[0143] See also Fig.17 As shown, as an example, the pixel structure further includes an auxiliary modulation structure 117, and the auxiliary modulation structure 117 is at least arranged on the side of the second type pixel 104 away from the incident light. For example, the auxiliary modulation structure 117 is arranged in the interconnection layer 105. The auxiliary modulation structure 117 can be prepared simultaneously when the first metal interconnection layer is prepared. Of course, it can also be prepared in other ways. The incident light passing through the second type pixel 104 is modulated by the auxiliary modulation structure 117 and enters the first type pixel to obtain modulated light. For example, it can be reflected light formed after passing through the auxiliary modulation structure 117. The first type pixel obtains the first signal based on the modulated light and the derived light.

[0144] As an example, the auxiliary modulation structure 117 can be continuously corresponding to and covering the position corresponding to the second type of pixel, or the auxiliary modulation structure 117 can include a plurality of auxiliary modulation units, and each of the auxiliary modulation units is arranged at intervals to achieve further reflection of the incident light. The number and arrangement of the auxiliary modulation units can be designed according to actual needs.

[0145] As an example, a design of a first-type pixel 103 is provided, wherein the side of the first-type pixel 103 is composed of a plurality of light incident surfaces, and the derived light enters the first photosensitive area of ​​the first-type pixel through the light incident surfaces, wherein each of the light incident surfaces corresponds one-to-one to the second-type pixel or other first-type pixels.

[0146] That is to say, the side of the first-category pixel 103 corresponds to the second-category pixel that obtains the same type of light signal, or corresponds to another first-category pixel. When corresponding to another first-category pixel, since the other first-category pixel is not directly exposed to light, it is difficult for diffracted light to enter the first-category pixel adjacent to it, so that only the derived light of the second-category pixel enters the first-category pixel, and no other type of light signal enters, which is conducive to effectively obtaining the first signal based on the first-category pixel.

[0147] In a further example, the second-class pixel is the nearest neighbor pixel of the first-class pixel, and at least each of the second-class pixels corresponding to the same first-class pixel covers the same color filter, so that each of the second-class pixels responds to the same type of light signal. Among them, the nearest pixel can refer to the pixel whose center of gravity is the smallest distance from the center of gravity of the first-class pixel. In an optional example, the shape and size of the first-class pixel and the second-class pixel are the same, and the nearest neighbor pixel of the first-class pixel refers to the pixel whose center is the smallest distance from the center of the pixel to the center of the first-class pixel. For example, for periodically arranged square pixels, there are 9 pixels in its 3×3 structure, and the 4 pixels corresponding to the four sides of the central square are the nearest neighbor pixels, and the 4 pixels corresponding to the four vertices in the positive direction are not the nearest neighbor pixels.

[0148] As an example, the image sensor further includes a third type of pixel, and the corresponding area between the third type of pixel and the first type of pixel is less than 1 / 10 of the corresponding area between the second type of pixel and the first type of pixel, for example, the corresponding area between the third type of pixel and the first type of pixel may be 1 / 20, 1 / 50, 1 / 100, 1 / 200, etc. of the corresponding area between the second type of pixel and the first type of pixel; or, the third type of pixel and the first type of pixel are arranged at intervals. Thus, the first type of pixel is not affected by the third type of pixel in the process of acquiring the derived light of the second type of pixel to generate the first signal.

[0149] That is to say, in this example, in the image sensor pixel array, a light shielding portion is provided above the first type of pixels, and no light shielding portion is provided above the second type of pixels and the third type of pixels. In addition, the second type of pixels generates derivative light that enters the first type of pixels, and the third type of pixels cannot generate derivative light that enters the first type of pixels, or generates a very small amount of derivative light that does not affect the acquisition of the first signal.

[0150] In a specific example, the side of the first type of pixel is composed of a plurality of the light incident surfaces, wherein the pixel corresponding to the boundary (a line) between adjacent light incident surfaces is the third type of pixel, and the corresponding area between the third type of pixel and the first type of pixel can be considered to be 0. For example, for periodically arranged square pixels, in its 3×3 structure, there are 9 pixels in total, the four sides of the central square correspond to four light incident surfaces, the four light incident surfaces correspond to the second type of pixels, and the 4 pixels corresponding to the four vertices in the positive direction are the third type of pixels.

[0151] Embodiment 2:

[0152] like Figure 18-20 As shown, this embodiment provides another image sensor pixel structure and preparation method, wherein the difference between this embodiment 2 and embodiment 1 is that the preparation method of the modulation functional layer is different from that of embodiment 1. The other preparation steps and the various material layers of the pixel structure can refer to the description in embodiment 1 and will not be repeated here.

[0153] Among them, see Figure 18-19 As shown, the method for forming the modulation functional layer in the second embodiment includes the following steps:

[0154] First, if Fig.18 As shown, after depositing the initial barrier material layer 111 on the substrate in the first embodiment, in the second embodiment, a light-guiding lithography mask layer (not shown in the figure) is prepared on the initial barrier material layer 11; and the initial barrier material layer is patterned based on the light-guiding lithography mask layer to obtain the light-guiding portion 113 and the corresponding light inlet 111a; in this step, the light-guiding portion 113 is correspondingly formed on each of the spacers 109, and the initial barrier material layer 111 on the first type of pixel 103 is also etched away; then, as shown in FIG. Fig.19 As shown, a light shielding material is deposited on the first type of pixel 103 to obtain the light shielding portion 201, thereby obtaining the modulation functional layer 202, that is, the light shielding portion and the light guiding portion can also be prepared step by step.

[0155] In addition, if Fig. 20 As shown, it also includes a process for preparing the filter unit layer and the microlens using the process described in the first embodiment.

[0156] Embodiment three:

[0157] See also Figure 21-28 As shown, this embodiment 3 provides an arrangement of the pixel structure of the first type of pixels and the second type of pixels based on the embodiments 1 and 2. The characteristics and description of each material layer of the pixel structure in this embodiment 3 refer to the embodiments 1 and 2, and will not be repeated here.

[0158] As an example, the pixel structure includes a plurality of pixel units, each of the pixel units includes a plurality of pixel sub-units, and each of the pixel sub-units includes at least one pixel of the first type and at least one pixel of the second type.

[0159] In one example, if Figure 21-24 As shown, the pixel structure includes a plurality of pixel units 300, and the pixel unit 300 includes a plurality of pixel sub-units, and the figure shows that it includes four pixel sub-units 301, 302, 303, and 304. Among them, taking the pixel sub-unit 301 as an example, it includes 1 first-type pixel 301a and 8 second-type pixels 301b. The pixels of the pixel sub-unit form a 3×3 structure, and the first-type pixel 301a is located in the center, and the second-type pixels 301b are located around. In addition, it can be understood by those skilled in the art that the first-type pixel 301a is blocked by the first light shielding portion 301c, and the same applies to other examples.

[0160] In another example, if Fig.25 As shown, the pixel structure includes a plurality of pixel units 400, and the pixel unit 400 includes a plurality of pixel sub-units, and the figure shows that the pixel sub-units include four pixel sub-units 401, 402, 403, and 404. Among them, taking the pixel sub-unit 401 as an example, it includes 1 first-type pixel 401a and 4 second-type pixels 401b. It can be considered that the pixels of the pixel sub-units constitute an improved 2×2 structure, the first-type pixel is located in the center and has four light-receiving sides, and the four second-type pixels are located around the first-type pixel and correspond one-to-one to the four light-receiving sides. In an optional example, it can be considered that if the first-type pixel 401a is removed, the hypotenuses of the other four second-type pixels 401b continue to extend to form a second-type pixel array with a 2×2 structure, see Fig.25 As shown by the dotted line extending in FIG. 1 , each second type pixel 401b has a common intersection M after extension, and the intersection M is also the center of the first type pixel. In a further optional example, the side length of the square formed by the extension of the second type pixels is greater than the side length of the square of the first type pixels.

[0161] In another example, Figure 26-27 As shown, the pixel structure includes a plurality of pixel units 500, and the pixel unit 500 includes a plurality of pixel sub-units, including four pixel sub-units 501, 502, 503, and 504. In particular, taking the pixel sub-unit 501 as an example, it includes one first-type pixel 501a and three second-type pixels 501b. The pixels of the pixel sub-unit form a 2×2 structure, the first-type pixels are located at a corner, and the second-type pixels are located at the remaining positions.

[0162] In yet another example, Fig.28As shown, the pixel structure includes a plurality of pixel units 600, and the pixel unit 600 includes a plurality of pixel sub-units, including four pixel sub-units 601, 602, 603, and 604. Taking the pixel sub-unit 601 as an example, it includes 2 first-type pixels 601a and 14 second-type pixels 601b, forming a 4×4 structure.

[0163] Please continue reading Figure 21-28 As shown, and in conjunction with Fig.17 As an example, the pixel structure further includes a plurality of color filter unit layers 115, and the color filter unit layers 115 correspond to the pixel subunits (such as pixel subunits 301 and 302) one by one, wherein the pixel unit obtains a corresponding type of light signal based on each pixel subunit to obtain a corresponding image signal based on the pixel unit. Fig.21 The example shown is used as an example for explanation. For pixel unit 300, a color filter unit layer that can transmit red light is covered on pixel subunit 301, that is, red light can pass through the filter (color filter), so that a red light signal can be obtained based on pixel subunit 301. Similarly, a green light signal can be obtained based on pixel subunits 302 and 303, and a blue light signal can be obtained based on pixel subunit 304.

[0164] As an example, the color filter unit layer 115 is located on the second type of pixels or covers both the first type of pixels and the second type of pixels. Fig.21 In the example, in another example, for the pixel sub-unit 301, the color filter unit layer 115 may include a plurality of color filter sub-units, each color filter unit corresponding to each pixel one by one, and further, in this example, the color filter unit may be prepared only above the second type of pixel 301b.

[0165] In another example, for the pixel sub-unit 301, the color filter unit layer 115 can also cover each pixel as a whole, that is, the color filter unit layer 115 corresponds to each pixel sub-unit one by one. In this example, the color filter unit layer covers the first type of pixels and the second type of pixels of a pixel sub-unit at the same time.

[0166] See also Figure 21-24As shown, a design method of a pixel layout with an RGGB filter is provided, wherein, as an example, such as taking 21 as an example, the pixel unit includes a first pixel subunit 301 responding to red light, a second pixel subunit 302, 303 responding to green light, and a third pixel subunit 304 responding to blue light, and each pixel subunit corresponds to a first light shielding portion 301c, a second light shielding portion 302c, 303c, and a third light shielding portion 304c, wherein the first type of pixels of different pixel subunits in the pixel unit have the same size, that is, the first type of pixels 301a, 302a, 303a, 304a have the same size, and are pixels of the same shape and size. In a further example, in this example, each pixel in the pixel array is a pixel of the same shape and size.

[0167] Among them, Fig.24 As shown, in an optional example, the size d1 of the first light shielding portion 301c is designed to be larger than the size d2 of the second light shielding portion 302c, 303c, and larger than the size d3 of the third light shielding portion 304c. Among them, due to the different diffraction capabilities of light of different colors, for the three colors of red, green and blue, the diffraction capability of red light is the strongest, and the diffraction capability of blue light is the weakest. In this example, the light-blocking material covering the first type of pixels is designed to have different widths for different first type pixels, with red pixels being the widest and blue pixels being the narrowest, which is further conducive to obtaining uniform signals.

[0168] As an example, the size d2 of the second light-shielding portion is the same as the size of the corresponding first-type pixel, the size d1 of the first light-shielding portion is not greater than 120% of the size d2 of the second light-shielding portion, and can be selected as 110%, 115%, etc. In addition, the size d3 of the third light-shielding portion is not less than 70% of the size d2 of the second light-shielding portion, and can be selected as 80%, 90%, etc.

[0169] For another example, see Figure 21-23 As shown, the sizes of the light shielding parts of different pixel sub-units may be the same, and the size of the light shielding part is greater than ( Fig. 22 ), less than( Fig.23 ) or equal to ( Fig.21 ) The size of the first photosensitive area corresponding to the pixel. In one example, each pixel is a square structure with equal sides, and the corresponding light shielding portion is also a square structure, wherein the side length d0 of the square light shielding portion can be greater than, equal to, or less than the side length of the pixel to meet different needs.

[0170] Please continue reading Figure 21-28As shown, as an example, the arrangement of pixels in the pixel subunit may be: the pixel subunit includes a central area and a peripheral area surrounding the central area, the first type of pixels are located in the central area, and the second type of pixels are at least located in the peripheral area. Figure 21-25 and Fig.28 As shown, in this arrangement, at least the outermost circle of pixel sub-units are second-type pixels, and of course can also be third-type pixels described in the previous embodiment, while the first-type pixels are located in the central area, so that the first-type pixels all receive derived light from the pixel sub-unit.

[0171] like Figure 26-27 As shown, the pixel subunit includes an edge region, the first-type pixel is located in the edge region, and the first-type pixel located in the edge region has an exposed light-entry contact portion, and the light-entry contact portion contacts the first-type pixel of the adjacent pixel subunit located in the edge region. In this example, at least one of the first-type pixels in the pixel subunit is located at the edge of the entire pixel subunit, and has an exposed light-entry contact portion relative to the pixel subunit itself. For example, for the pixel subunit 501, there is a first-type pixel 501a located in the edge region, and the first-type pixel 501a has an exposed light-entry contact portion 501aa. In this arrangement, the first-type pixel 501 is set to correspond to the light-entry contact portion of the adjacent subpixel, such as the light-entry contact portion 501aa of the first-type pixel 501a corresponds to the light-entry contact portion 502aa of the first-type pixel 502a in the adjacent pixel subunit 502, which is also located in the edge region, so that the first-type pixel is surrounded by only the second-type pixel or other first-type pixels, and a relatively single signal is obtained, which is conducive to reflecting image information.

[0172] Embodiment 4:

[0173] The present invention also provides an imaging method of a pixel structure obtained based on any one of embodiments 1 to 3, in which the first type of pixels are controlled to have a first exposure time, the second type of pixels are controlled to have a second exposure time, and the first exposure time is greater than the second exposure time. In one example, the second exposure time is greater than 1 / 100 of the first exposure time, for example, the second exposure time is 1 / 50, 1 / 20, 1 / 10, or 1 / 2 of the first exposure time.

[0174] For example, the exposure time of the first type of pixels can be controlled to be greater than the exposure time of the second type of pixels. The surface of the first type of pixels is covered with a light blocking material (the light blocking part does not transmit light), so that the light incident on the pixel cannot enter the pixel, but the light entering the surrounding pixels (the second type of pixels) can enter these pixels due to the diffraction of light. Since the diffraction effect between different pixels is weak, a weaker light response can be achieved, and long-term exposure can be achieved without easily causing overexposure, thereby improving the dynamic range of the image sensor. In addition, for light sources whose brightness changes over time, for example, light sources operating in pulse modulation mode (for example, LEDs), the design of the present invention can be based on long-term exposure of the first type of pixels, which can be suitable for shooting photos or videos with flickering light sources, and can attenuate the impact of light source flicker. Furthermore, each second type of pixel corresponding to the same first type of pixel responds to the same type of light signal, so the spectral curves of these pixels are consistent with those of the adjacent second type of pixels, and these pixels can be made to have a suitable spectral response through appropriate settings. In addition, compared with the existing technology, the pixels in the traditional image sensor are no different. Timing control is used to expose some pixels in the pixel array for a short time and other pixels for a long time, so LFM can be achieved. However, the disadvantage is that the pixels exposed for a long time are prone to overexposure, and a clear image acquisition function cannot be achieved.

[0175] Embodiment five:

[0176] The present invention also provides an electronic device, wherein the electronic device includes the image sensor structure pixel structure as described in any one of the schemes in the above embodiments. The electronic device can be a security camera device, an automotive electronic camera device, a mobile phone camera device, a drone, a machine vision device, and an existing camera. Furthermore, the electronic device can use the imaging method described in embodiment 4 for imaging.

[0177] In summary, the present invention designs a first type of pixel with a shading portion on the top and a second type of pixel without a shading portion on the top that can receive light, and uses the derived light of the second type of pixel as the response light of the first type of pixel, and each second type of pixel corresponding to the same first type of pixel responds to the same type of light signal, so that the first type of pixel receives the same type of derived light to generate a first signal, and at the same time, the second type of pixel generates a second signal based on the incident light, so that an effective image signal can be obtained based on the first signal of the first type of pixel and the second signal of the second type of pixel, so as to improve the dynamic range of the image, and can effectively realize the acquisition of photos or videos with light source flickering based on the above signals. In addition, based on the design of the present invention, the shading portion and the light guiding portion can be prepared simultaneously, the light signals of the first type of pixel and the second type of pixel can be modulated, and crosstalk between different types of light signals can be effectively prevented, the preparation process can be simplified, and the efficiency can be improved. Therefore, the present invention effectively overcomes various shortcomings in the prior art and has a high industrial utilization value.

[0178] The above embodiments are merely illustrative of the principles and effects of the present invention, and are not intended to limit the present invention. Anyone familiar with the art may modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by a person of ordinary skill in the art without departing from the spirit and technical concept disclosed by the present invention shall still be covered by the claims of the present invention.

Claims

1. An image sensor, It is characterized in that The image sensor comprises: A first type of pixel, the first type of pixel comprising a first photosensitive area; A second type of pixel, wherein the second type of pixel comprises a second photosensitive area, and a spacing area is provided between the first type of pixel and the second type of pixel; and The modulation function layer at least comprises a light shielding portion, wherein the light shielding portion is located on the first type of pixel to shield incident light; Based on the modulation functional layer, incident light enters the area corresponding to the second-type pixel and generates derived light, and the derived light enters the first-type pixel at least through the spacing area, wherein the first photosensitive area receives the derived light to generate a first signal, and the second photosensitive area receives the incident light to generate a second signal, and each of the second-type pixels corresponding to the same first-type pixel responds to the same type of light signal.

2. The image sensor according to claim 1, It is characterized in that The side surfaces of the first-type pixels are composed of a plurality of light incident surfaces, and the derived light enters the first photosensitive area of ​​the first-type pixels through the light incident surfaces, wherein each of the light incident surfaces corresponds one-to-one to the second-type pixels or other first-type pixels.

3. The image sensor according to claim 2, It is characterized in that The second-type pixels are the nearest neighbor pixels of the first-type pixels, and at least the second-type pixels corresponding to the same first-type pixel are covered with the same color filter, so that the second-type pixels respond to the same type of light signal.

4. The image sensor according to claim 1, It is characterized in that The image sensor further includes a third type of pixels, wherein the corresponding area between the third type of pixels and the first type of pixels is smaller than 1 / 10 of the corresponding area between the second type of pixels and the first type of pixels, or the third type of pixels and the first type of pixels are spaced apart.

5. The image sensor according to claim 1, It is characterized in that The image sensor includes a plurality of pixel units, each of the pixel units includes a plurality of pixel sub-units, wherein each of the pixel sub-units includes at least one pixel of the first type and at least one pixel of the second type.

6. The image sensor according to claim 5, It is characterized in that The image sensor also includes a plurality of color filter unit layers, and the color filter unit layers correspond one-to-one to the pixel sub-units, wherein the color filter unit layers are located on the second type of pixels or cover both the first type of pixels and the second type of pixels, and the pixel units obtain corresponding types of light signals based on the color filter unit layers corresponding to each of the pixel sub-units to obtain corresponding image signals.

7. The image sensor according to claim 6, It is characterized in that The pixel unit at least includes a first pixel sub-unit responding to red light, a second pixel sub-unit responding to green light, and a third pixel sub-unit responding to blue light, and each pixel sub-unit corresponds to a first light-shielding portion, a second light-shielding portion, and a third light-shielding portion, respectively, and the sizes of the first type of pixels of different pixel sub-units in the pixel unit are the same, wherein the size of the first light-shielding portion is larger than the size of the second light-shielding portion which is larger than the size of the third light-shielding portion, or the sizes of the light-shielding portions corresponding to different pixel sub-units are the same, and the size of the light-shielding portion is larger than, smaller than or equal to the size of the corresponding first type of pixels.

8. The image sensor according to claim 7, It is characterized in that The size of the second light shielding portion is the same as the size of the corresponding first type of pixel, the size of the first light shielding portion is not greater than 120% of the size of the second light shielding portion, and the size of the third light shielding portion is not less than 70% of the size of the second light shielding portion.

9. The image sensor according to claim 5, It is characterized in that The arrangement of pixels in the pixel sub-unit includes: the pixel sub-unit includes a central area and a peripheral area surrounding the central area, the first type of pixels are located in the central area, and the second type of pixels are at least located in the peripheral area; or, the pixel sub-unit includes an edge area, the first type of pixels are located in the edge area, and the first type of pixels located in the edge area have an exposed light incident contact portion, and the light incident contact portion is in contact with the first type of pixels of an adjacent pixel sub-unit located in the edge area.

10. The image sensor according to claim 9, It is characterized in that The pixel unit includes four pixel sub-units, and the arrangement of the pixel sub-units includes: the pixels of the pixel sub-units form a 3×3 structure, the first type of pixels are located in the center, and the second type of pixels are located around; or, the pixels of the pixel sub-units form a 2×2 structure, the first type of pixels are located in a corner, and the second type of pixels are located in the remaining positions; or, the pixels of the pixel sub-units form an improved 2×2 structure, the first type of pixels are located in the center and have four light-receiving side surfaces, and four second type of pixels are located around the first type of pixels and correspond one-to-one to the four light-receiving side surfaces.

11. The image sensor according to claim 1, It is characterized in that The image sensor also includes an auxiliary modulation structure, which is arranged on a side of the second-type pixel away from the incident light. The incident light passing through the second-type pixel is modulated by the auxiliary modulation structure and enters the first-type pixel to obtain modulated light. The first-type pixel obtains the first signal based on the modulated light and the derived light.

12. The image sensor according to claim 1, It is characterized in that The image sensor includes a substrate, in which the first type of pixels, the second type of pixels and the spacer area are prepared. The image sensor also includes an intermediate modulation transition layer located between the substrate and the modulation functional layer, wherein the thickness of the intermediate modulation transition layer is greater than 20nm; and / or the material of the intermediate modulation transition layer is a single-layer oxide transition layer or a stacked layer composed of multiple oxides.

13. The image sensor according to claim 1, It is characterized in that The shading rate of the shading portion is greater than 98%; and / or, the first type of pixels and the second type of pixels are the same in shape and size and are distributed in a periodic array.

14. The image sensor according to any one of claims 1 to 13, It is characterized in that The modulation function layer also includes a light guiding portion, which is located correspondingly on the spacing area, so that the modulation function layer has a plurality of light entrances corresponding to the second type of pixels, and the incident light enters the second type of pixel area through the light entrances.

15. The image sensor according to claim 14, It is characterized in that The modulation functional layer composed of the light guiding part and the light shading part is a structure formed based on the same process; and / or the material of the light shading part includes at least one of tungsten, aluminum, titanium, titanium nitride, tantalum and tantalum nitride, and the material of the light guiding part includes at least one of tungsten, aluminum, titanium, titanium nitride, tantalum, tantalum nitride and a material having a refractive index less than the refractive index of the filling material layer between adjacent light guiding parts.

16. A method for preparing an image sensor according to any one of claims 1 to 15, It is characterized in that The preparation method comprises the following steps: providing a substrate; preparing the first type of pixels, the second type of pixels and the spacer in the substrate; The modulation functional layer is prepared on the substrate.

17. The method for preparing an image sensor according to claim 16, It is characterized in that When the modulation functional layer further includes a light guide portion and forms a light entrance, the light guide portion is correspondingly located on the spacer area, so that the modulation functional layer has a plurality of light entrances corresponding to the second type of pixels, and the incident light enters the second type of pixel area through the light entrance, and the preparation steps of the modulation functional layer include: depositing an initial layer of barrier material on the substrate; preparing a mask layer on the initial barrier material layer; and Patterning the initial blocking material layer based on the mask layer to simultaneously obtain the light shielding portion and the light guiding portion; or, depositing an initial layer of barrier material on the substrate; preparing a light-guiding lithography mask layer on the initial barrier material layer; Patterning the initial blocking material layer based on the light-guiding etch mask layer to obtain the light-guiding portion and a plurality of openings corresponding to pixels in the substrate, wherein the openings include the light entrance; and A light shielding material is deposited to fill the opening corresponding to the first type of pixel to obtain the light shielding portion.

18. The method for preparing an image sensor according to any one of claims 16 to 17, It is characterized in that The preparation method further comprises the steps of sequentially preparing a filter array and a microlens after the modulation function layer is prepared.

19. An imaging method based on the image sensor according to any one of claims 1 to 15, It is characterized in that The imaging method comprises the following steps: The first type of pixels are controlled to have a first exposure time, the second type of pixels are controlled to have a second exposure time, and the first exposure time is greater than the second exposure time.

20. The imaging method according to claim 19, It is characterized in that The second exposure time is greater than 1 / 100 of the first exposure time.

21. An electronic device, It is characterized in that Comprising the image sensor as claimed in any one of claims 1-15.

Images