Image sensor, preparation method, chip and equipment

Abstract

The invention provides an image sensor, a preparation method, a chip and equipment, and relates to the technical field of semiconductors. An image sensor includes: a substrate; the substrate comprises a photoelectric conversion region; a storage structure; the storage structure is arranged on the backlight side of the photoelectric conversion area and used for storing photo-induced electrons generated by the photoelectric conversion area. The storage structure is arranged on the backlight side of the photoelectric conversion area, and does not occupy the area of the photoelectric conversion area, so that the area of the photoelectric conversion area is not extruded, and the reduction of filling factors is avoided. Moreover, the storage structure provided by the invention only needs to be connected with a photo-induced electron transmission structure of the image sensor, and the photo-induced electrons can be received and stored, so that the overall design complexity of the image sensor can be reduced.

Description

Technical Field

[0001] The present application relates to the field of semiconductor technology, and in particular to an image sensor, a preparation method, a chip and a device. Background Art

[0002] As various electronic products have higher and higher performance requirements for image sensors, image sensors need to have more image details, a larger dynamic range, faster light response and transmission speed. Image sensors with high dynamic range can obtain more image details, making the application range of image sensors wider and the photos taken clearer.

[0003] Therefore, improving the dynamic range of image sensors is a current design direction of image sensors. Summary of the invention

[0004] The present application provides an image sensor, a preparation method, a chip and a device, which are used to provide a technical solution for an image sensor with a high dynamic range.

[0005] In a first aspect, the present application provides an image sensor, comprising:

[0006] A substrate; the substrate includes a photoelectric conversion region;

[0007] Storage structure: The storage structure is arranged on the backlight side of the photoelectric conversion region and is used to store the photogenerated electrons generated by the photoelectric conversion region.

[0008] In an optional embodiment, the image sensor further includes a photogenerated electron storage area, and the storage structure is connected to the photogenerated electron storage area and is used to store photogenerated electrons overflowing from the photogenerated electron storage area.

[0009] In an optional implementation, the image sensor further includes a gate structure; the gate structure is connected to the photoelectric conversion region.

[0010] In an optional embodiment, the photogenerated electron storage region is arranged on a side of the gate structure away from the photoelectric conversion region;

[0011] The gate structure is used to transfer the photogenerated electrons generated in the photoelectric conversion area to the photogenerated electron storage area.

[0012] In an alternative embodiment, the photogenerated electron storage region includes a floating gate diffusion structure;

[0013] The gate structure is used to transfer the photogenerated electrons generated in the photoelectric conversion region to the floating gate diffusion structure.

[0014] In an optional embodiment, the photogenerated electron storage area further includes a photogenerated electron storage structure;

[0015] The photogenerated electron storage structure is connected to the floating gate diffusion structure and the storage structure, and is used for storing the photogenerated electrons overflowing from the floating gate diffusion structure and transmitting the overflowed photogenerated electrons to the storage structure.

[0016] In an optional embodiment, the image sensor further includes a first switch structure, which is disposed between the photogenerated electron storage structure and the floating gate diffusion structure and is used to control the transmission of photogenerated electrons between the floating gate diffusion structure and the photogenerated electron storage structure.

[0017] In an optional embodiment, the first switch structure, the photogenerated electron storage structure and the floating gate diffusion structure form a dual conversion gain transistor.

[0018] In an optional embodiment, the first switch structure forms a control electrode of a dual conversion gain transistor;

[0019] and / or, the floating gate diffusion structure forms an input terminal of a dual conversion gain transistor;

[0020] And / or, the photogenerated electron storage structure forms the output electrode of the dual conversion gain transistor.

[0021] In an optional embodiment, the storage structure includes a capacitor structure.

[0022] In an optional implementation, the capacitor structure includes a first capacitor.

[0023] In an optional implementation, the first capacitor includes a first substrate and a second substrate.

[0024] In an optional embodiment, the second substrate is made of the same material as the gate structure of the image sensor.

[0025] In an optional embodiment, the gate structure includes a trench gate structure.

[0026] In an optional embodiment, along the thickness direction of the substrate, the second substrate and the top gate layer of the trench gate structure are prepared at the same layer.

[0027] In an optional embodiment, the first substrate or the second substrate is electrically connected to the photogenerated electron storage region.

[0028] In an optional embodiment, the first substrate or the second substrate is electrically connected to the photogenerated electron storage region.

[0029] In an optional implementation, the first capacitor includes a first junction capacitor.

[0030] In an optional implementation, the first junction capacitor is electrically connected to the photogenerated electron storage region.

[0031] In an optional implementation, the capacitor structure includes a plurality of capacitors.

[0032] In an optional implementation, the plurality of capacitors include a first capacitor and a second capacitor connected in parallel.

[0033] In an optional implementation, the first capacitor includes a first substrate and a second substrate.

[0034] In an optional implementation, the second capacitor includes a second substrate and a third substrate.

[0035] In an optional embodiment, the first substrate is electrically connected to the third substrate.

[0036] In an optional embodiment, the second substrate is electrically connected to the photogenerated electron storage region.

[0037] In an optional embodiment, the second substrate is located between the first substrate and the third substrate.

[0038] In an optional embodiment, the second substrate is made of the same material as the gate structure of the image sensor.

[0039] In an optional embodiment, the gate structure includes a trench gate structure.

[0040] In an optional embodiment, along the thickness direction of the substrate, the second substrate is prepared in the same layer as the top gate layer of the trench gate structure. In an optional embodiment, a first dielectric layer is provided between the first substrate and the second substrate, and the first dielectric layer is used to store the photogenerated electrons.

[0041] In an optional embodiment, the first dielectric layer is made of the same material as the gate oxide layer of the trench gate structure.

[0042] In an optional embodiment, the first dielectric layer is prepared at the same layer as the top gate oxide layer of the trench gate structure.

[0043] In an optional implementation, a second dielectric layer is disposed between the second substrate and the third substrate, and the second dielectric layer is used to store the photogenerated electrons.

[0044] In an optional implementation, the second dielectric layer is a dielectric layer with a high dielectric constant.

[0045] In an optional embodiment, the first substrate is disposed in the base.

[0046] In an optional embodiment, the first substrate is located on the backlight side of the photoelectric conversion region.

[0047] In an optional embodiment, the image sensor includes an isolation layer disposed in the base, and the isolation layer is used to isolate the first substrate and the photoelectric conversion region.

[0048] In an optional embodiment, the isolation layer is at least partially disposed between the first substrate and the photoelectric conversion region.

[0049] In an optional embodiment, the isolation layer is a layer formed by doping the substrate with first conductivity type ions from the backlight side of the substrate.

[0050] In an optional embodiment, the first substrate is a layer formed by doping the isolation layer with ions of the second conductivity type from the backlight side of the substrate.

[0051] In an optional embodiment, the thickness of the first substrate is smaller than the thickness of the isolation layer.

[0052] In an optional embodiment, the ratio of the thickness of the first substrate to the thickness of the isolation layer is in a range of 1 / 5 to 1 / 3.

[0053] In an optional implementation, the plurality of capacitors include a first capacitor, a second capacitor, and a third capacitor.

[0054] In an optional implementation, the capacitor structure includes a first junction capacitor and a second junction capacitor.

[0055] In an optional embodiment, the first junction capacitor or the second junction capacitor is electrically connected to the photogenerated electron storage region.

[0056] In an optional embodiment, the photogenerated electron storage region includes a floating gate diffusion structure, and the first junction capacitor or the second junction capacitor is electrically connected to the floating gate diffusion structure;

[0057] The first junction capacitor or the second junction capacitor is used to store photogenerated electrons overflowing from the floating gate diffusion structure.

[0058] In an optional embodiment, the image sensor further includes a second switch structure, and the second switch structure is located at the backlight side of the photoelectric conversion region.

[0059] In an optional embodiment, the second switch structure is disposed on a side of the substrate away from the photoelectric conversion region.

[0060] In an optional embodiment, the second switch structure is disposed between the first junction capacitor and the second junction capacitor to control the transmission of photogenerated electrons between the first junction capacitor and the second junction capacitor.

[0061] In an optional embodiment, the second switch structure, the first junction capacitor and the second junction capacitor form a dual conversion gain transistor.

[0062] In an optional embodiment, the second switch structure forms a control electrode of a dual conversion gain transistor;

[0063] and / or, one of the first junction capacitance and the second junction capacitance forms an input electrode of the dual conversion gain transistor;

[0064] And / or, the other of the first junction capacitance and the second junction capacitance forms an output electrode of the dual conversion gain transistor.

[0065] In an optional embodiment, the image sensor includes an isolation layer disposed in the substrate; the isolation layer is used to isolate the first junction capacitance and the second junction capacitance from the photoelectric conversion region.

[0066] In an optional embodiment, the isolation layer is at least partially disposed between the first junction capacitor, the second junction capacitor and the photoelectric conversion region.

[0067] In an optional embodiment, the isolation layer is a layer formed by doping the substrate with ions of the first conductivity type.

[0068] In an optional implementation, the first junction capacitor and the second junction capacitor are capacitor structures formed by doping the isolation layer with ions of the second conductivity type.

[0069] In an optional embodiment, the first junction capacitor and the second junction capacitor are disposed in the substrate.

[0070] In an optional embodiment, the first junction capacitor and the second junction capacitor are located on the backlight side of the photoelectric conversion region.

[0071] In a second aspect, the present application further provides a method for preparing an image sensor, the method comprising:

[0072] Providing a substrate, the substrate comprising a photoelectric conversion region;

[0073] A storage structure is formed, which is arranged on the backlight side of the photoelectric conversion region and is used to store the photogenerated electrons generated by the photoelectric conversion region.

[0074] In an alternative embodiment, providing a substrate comprises:

[0075] providing a base material layer;

[0076] The base material layer is doped to form a photoelectric conversion region in the base material layer.

[0077] In an optional implementation, the storage structure is a capacitor structure, and forming the storage structure includes:

[0078] On the backlight side of the photoelectric conversion region, a capacitor structure is formed.

[0079] In an optional embodiment, before forming the capacitor structure, the method further includes:

[0080] From the backlight side of the substrate, the substrate is doped with ions of the first conductive type to form an isolation layer; the isolation layer is used to isolate the photoelectric conversion area from the capacitor structure;

[0081] Among them, the backlight side of the substrate is the backlight side of the substrate.

[0082] In an optional embodiment, the capacitor structure includes a first capacitor; and forming the capacitor structure on the backlight side of the photoelectric conversion region includes:

[0083] From the backlight side of the substrate, doping the isolation layer with ions of the second conductive type to form a first substrate;

[0084] A second substrate is formed on a side of the first substrate away from the photoelectric conversion region; the first substrate and the second substrate form a first capacitor.

[0085] In an optional embodiment, the capacitor structure includes a first capacitor and a second capacitor connected in parallel; on the backlight side of the photoelectric conversion region, forming the capacitor structure includes:

[0086] From the backlight side of the substrate, doping the isolation layer with ions of the second conductive type to form a first substrate;

[0087] forming a second substrate on a side of the first substrate away from the photoelectric conversion region;

[0088] A third substrate is formed on a side of the second substrate facing away from the first substrate; the first substrate and the second substrate form a first capacitor, and the second substrate and the third substrate form a second capacitor.

[0089] In an optional embodiment, the doping concentration of the second conductive type ions in the first substrate is greater than the doping concentration of the first conductive type ions in the isolation layer.

[0090] In an optional embodiment, before forming the second substrate on a side of the first substrate away from the photoelectric conversion region, the method further comprises:

[0091] A gate groove is formed in the substrate from a first side of the substrate; the gate groove is arranged on one side of the capacitor structure, and the bottom of the gate groove is located in the photoelectric conversion area.

[0092] In an optional embodiment, forming the second substrate on a side of the first substrate away from the photoelectric conversion region comprises:

[0093] From the opening direction of the gate groove, a gate oxide layer and a gate material layer are sequentially formed on the substrate and in the gate groove;

[0094] The gate material layer is patterned to form a second substrate.

[0095] In an optional embodiment, while patterning the gate material layer to form the second substrate, the method further includes:

[0096] A gate structure is formed.

[0097] In an optional embodiment, after forming the gate structure, the method further includes:

[0098] forming sidewalls on both sides of the gate structure and the second substrate;

[0099] A floating gate diffusion structure is formed in the substrate, and the floating gate diffusion structure is arranged on a side of the gate structure away from the capacitor structure.

[0100] In an optional implementation, the capacitor structure includes a first junction capacitor and a second junction capacitor, and forming the capacitor structure includes:

[0101] The designated area of ​​the isolation layer is doped with ions of the second conductive type to form a first junction capacitor and a second junction capacitor.

[0102] In an optional embodiment, the storage structure further includes a second switch structure; while patterning the gate material layer to form a second substrate, the method further includes:

[0103] A second switch structure is formed, wherein the second switch structure is located between the first junction capacitor and the second junction capacitor.

[0104] In a third aspect, an embodiment of the present application further provides a chip, comprising the image sensor of the first aspect, or comprising an image sensor prepared using the method of the second aspect.

[0105] In a fourth aspect, an embodiment of the present application further provides a device, comprising the image sensor of the first aspect, or comprising an image sensor prepared using the method of the second aspect.

[0106] In the technical solution provided in the present application, a storage structure is arranged on the backlight side of the photoelectric conversion region, and the storage structure is connected to the photogenerated electron transmission structure of the image sensor for receiving and storing the photogenerated electrons. Therefore, the image sensor of the present application can utilize the storage structure to store more photogenerated electrons to achieve a higher dynamic range. BRIEF DESCRIPTION OF THE DRAWINGS

[0107] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the present application and, together with the description, serve to explain the principles of the present application.

[0108] Figure 1 A schematic diagram of the structure of an image sensor provided in an embodiment of the present application Figure 1 ;

[0109] Figure 2 A schematic diagram of the structure of an image sensor provided in an embodiment of the present application Figure 2 ;

[0110] Figure 3 A schematic diagram of the structure of an image sensor provided in an embodiment of the present application Figure 3 ;

[0111] Figure 4 A schematic diagram of the structure of an image sensor provided in an embodiment of the present application Figure 4 ;

[0112] Figure 5 A schematic diagram of a substrate provided in an embodiment of the present application;

[0113] Figure 6 A schematic diagram of a structure for forming a first conductive type doping region in a substrate provided in an embodiment of the present application;

[0114] Figure 7 A schematic diagram of a structure in which a first substrate is formed in a first conductive type doping region provided in an embodiment of the present application;

[0115] Figure 8 A schematic diagram of a structure after a gate trench is formed provided in an embodiment of the present application;

[0116] Fig. 9 A schematic diagram of a structure after forming a second substrate and a gate structure provided in an embodiment of the present application;

[0117] Fig.10 A schematic diagram of a structure in which side walls are formed on both sides of a second substrate and a gate structure provided in an embodiment of the present application;

[0118] Fig.11 A schematic diagram of a structure after a photogenerated electron storage area is formed in a substrate provided in an embodiment of the present application;

[0119] Fig.12 A schematic diagram of a structure after a third substrate is formed provided in an embodiment of the present application.

[0120] Reference numerals:

[0121] 10: substrate; 11: photoelectric conversion region; 111: light incident side of the photoelectric conversion region; 112: backlight side of the photoelectric conversion region; 12: first conductive type doping region (12);

[0122] 20: storage structure; 21: first substrate; 22: second substrate; 23: third substrate; 24: junction capacitance; 25: second switch structure;

[0123] 30: gate structure; 301: gate groove; 302: sidewall; 310: gate oxide layer;

[0124] 40: photogenerated electron storage area; 41: floating gate diffusion structure; 42: photogenerated electron storage structure; 43: first switch structure.

[0125] The above drawings have shown clear embodiments of the present application, which will be described in more detail later. These drawings and text descriptions are not intended to limit the scope of the present application in any way, but to illustrate the concept of the present application to those skilled in the art by referring to specific embodiments. DETAILED DESCRIPTION

[0126] Exemplary embodiments will be described in detail herein, examples of which are shown in the accompanying drawings. When the following description refers to the drawings, the same numbers in different drawings represent the same or similar elements unless otherwise indicated. The implementations described in the following exemplary embodiments do not represent all implementations consistent with the present application. Instead, they are merely examples of devices and methods consistent with some aspects of the present application as detailed in the appended claims.

[0127] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those generally understood by those skilled in the art to which the present application belongs. The terms used herein in the specification of the present application are only for the purpose of describing specific embodiments and are not intended to limit the present application. It is understood that the terms "first", "second", etc. used in the present application can be used to describe various information or data in this article, but these elements are not limited by these terms. These terms are only used to distinguish the first information from another information. For example, without departing from the scope of the present application, the first action information can be referred to as the second action information, and similarly, the second action information can be referred to as the first action information. Both the first action information and the second action information are action information, but they are not the same action information.

[0128] First, the terms involved in this application are explained:

[0129] Image sensors, which convert light signals into electrical signals, are core components of modern digital cameras, camcorders, smartphone cameras and other devices.

[0130] The electro-optical conversion region is a key part of the image sensor, responsible for converting the incident light signal into photogenerated electrons. This region is usually composed of a photodiode or other photosensitive element.

[0131] The photogenerated electron storage area is responsible for storing the photogenerated electrons generated by the photoelectric conversion area (ie, the electrons generated after the incidence of photons).

[0132] Photogenerated electrons refer to free electrons generated when photons are incident on semiconductor materials (such as silicon) during the photoelectric effect.

[0133] The technical solution provided in this application can be applied to image sensors with high dynamic range. The dynamic range of the image sensor is determined by the full well capacity and the background noise. Therefore, there are two ways to increase the dynamic range of the image sensor: increase the full well capacity and reduce the noise to reduce the value of the detectable signal, that is, reduce the sensitivity threshold. The currently commonly used solution is to use DCG+HDR (Dual conversion gain High dynamic ratio, dual conversion gain high dynamic range) technology. By adding a capacitor to the periphery of the photoelectric conversion area and using a DCG (Dual Gain Switch, dual conversion gain) MOS switch to control the capacitor.

[0134] The most commonly used capacitors added to the periphery of the photoelectric conversion area are MOSCAP (Metal-Oxide-Semiconductor Capacitor) and MIM (Metal-Oxide-Semiconductor Capacitor). However, MOSCAP capacitors occupy a large area on the chip surface, which seriously squeezes the area of ​​the photoelectric conversion area and causes a decrease in the fill factor. MIM capacitors will increase the routing complexity of the chip, making the design more difficult.

[0135] Based on this, the technical concept of the embodiment of the present application is to design a technical solution that can reduce the design complexity of the image sensor and improve the integration of the image sensor without affecting the performance of the image sensor. Based on this, the embodiment of the present application sets a storage structure on the backlight surface of the photoelectric conversion area, and the storage structure is used to store the photogenerated electrons generated by the photoelectric conversion area under high light conditions to achieve a larger full well capacity, thereby improving the dynamic range of the image sensor.

[0136] The technical solution of the present application and how the technical solution of the present application solves the above-mentioned technical problems are described in detail below with specific embodiments. The following specific embodiments can be combined with each other, and the same or similar concepts or processes may not be repeated in some embodiments. The embodiments of the present application will be described below in conjunction with the accompanying drawings.

[0137] In a first aspect, an embodiment of the present application provides an image sensor. Figure 1 , the image sensor comprises:

[0138] The substrate 10 comprises a photoelectric conversion region 11 , wherein the photoelectric conversion region 11 has a light incident side 111 and a backlight side 112 opposite to each other, and the light incident side 111 is used to receive an optical signal.

[0139] The photoelectric conversion region 11 is used to realize photoelectric conversion. Photons are incident on the photoelectric conversion region 11 from the light incident side 111 , so that the photoelectric conversion region 11 generates photogenerated electrons.

[0140] And a storage structure 20 ; the storage structure 20 is disposed on the backlight side 112 of the photoelectric conversion region 11 , and is used to store the photogenerated electrons generated by the photoelectric conversion region 11 .

[0141] The storage structure 20 is arranged on the backlight side 112. In the related art, there is no structure on the surface of the backlight side 112. However, in this embodiment, a storage structure is arranged on the surface of the backlight side 112 to store photogenerated electrons. Therefore, this embodiment can improve the integration of the image sensor without affecting the performance of the image sensor.

[0142] This embodiment can also utilize the storage structure 20 to store photogenerated electrons generated in the photoelectric conversion region under high light conditions to achieve a larger full well capacity, thereby improving the dynamic range of the image sensor.

[0143] Moreover, in this embodiment, a storage structure is arranged on the backlight side of the photoelectric conversion region, and the storage structure does not occupy the area of ​​the photoelectric conversion region itself, so it does not squeeze the area of ​​the photoelectric conversion region, thereby avoiding the decrease of the fill factor. Furthermore, the storage structure of this embodiment only needs to be connected to the photogenerated electron transmission structure of the image sensor to achieve the reception and storage of the photogenerated electrons. Therefore, the image sensor in the embodiment of the present application can not only store more photogenerated electrons to achieve a higher dynamic range, but also reduce the overall design complexity of the image sensor.

[0144] In some examples, reference Figure 1 , Figure 2 or Figure 4 The image sensor further includes a photogenerated electron storage region 40 and a gate structure 30 .

[0145] Among them, the photogenerated electron storage area 40 is connected to the above-mentioned storage structure 20. The photogenerated electron storage area 40 is used to preferentially store the photogenerated electrons generated by the photoelectric conversion area 11. When the photogenerated electron storage area 40 is full of photogenerated electrons, the overflowed photogenerated electrons are transmitted to the storage structure 20 to store more photogenerated electrons through the storage structure 20, thereby increasing the storage capacity of photogenerated electrons.

[0146] Optional, see Figure 1 or Figure 2The photogenerated electron storage area 40 includes a floating gate diffusion structure (FD, FloatingDiffusion) 41, which is used to preferentially store the photogenerated electrons generated by the photoelectric conversion area 11. Afterwards, after the floating gate diffusion structure 41 is full of photogenerated electrons, the overflowing photogenerated electrons are transmitted to the storage structure 20 to increase the number of photogenerated electrons stored in the image sensor, thereby increasing the full well capacity and achieving the purpose of improving the dynamic range of the image sensor.

[0147] The photoelectric conversion region 11 converts the incident light signal into photogenerated electrons. These photogenerated electrons are then transferred to the floating gate diffusion structure 41. In the floating gate diffusion structure 41, the charge formed by the photogenerated electrons is converted into a voltage signal through the capacitive effect. As more and more photogenerated electrons are stored in the floating gate diffusion structure 41, the photogenerated electrons in the floating gate diffusion structure 41 will reach an overflow state. Therefore, another structure can be set to store the overflowed photogenerated electrons to increase the capacity of the photogenerated electron storage region 40 that can store photogenerated electrons.

[0148] Based on this, refer to Figure 1 or Figure 2 The photogenerated electron storage area 40 also includes a photogenerated electron storage structure 42 .

[0149] The photogenerated electron storage structure 42 is connected to the floating gate diffusion structure 41 and the capacitor structure, and is used to store the photogenerated electrons overflowing from the floating gate diffusion structure 41, and transmit its own overflowing photogenerated electrons to the storage structure 20, so as to increase the capacity of the photogenerated electron storage area 40 to store photogenerated electrons. Transmitting its own overflowing photogenerated electrons to the storage structure 20 can increase the overall storage capacity of the image sensor for photogenerated electrons, so as to achieve a larger full-well capacity, thereby improving the dynamic range of the image sensor.

[0150] The gate structure 30 is connected to the photoelectric conversion region 11. When the gate structure 30 is a vertical gate structure, the bottom end of the vertical gate structure extends into the photoelectric conversion region 11. It should be understood that the gate structure can also be a planar gate structure, which is not particularly limited in this embodiment.

[0151] During operation, a light signal is incident on the light incident side 111 of the photoelectric conversion region 11, and photogenerated electrons are generated in the photoelectric conversion region 11. The photogenerated electrons are transmitted outwardly to the photogenerated electron storage region 40 through the gate structure 30 to ensure that the photoelectric conversion region 11 can generate more photogenerated electrons.

[0152] For example, when the photogenerated electron storage region 40 includes the floating gate diffusion structure 41 , the floating gate diffusion structure 41 is disposed on a side of the gate structure 30 away from the photoelectric conversion region 11 , and the gate structure 30 is used to transfer the photogenerated electrons generated in the photoelectric conversion region 11 to the floating gate diffusion structure 41 .

[0153] For another example, when the photogenerated electron storage region 40 includes a floating gate diffusion structure 41 and a photogenerated electron storage structure 42, the floating gate diffusion structure 41 is disposed on the side of the gate structure 30 away from the photoelectric conversion region 11, and the photogenerated electron storage structure 42 is electrically connected to the floating gate diffusion structure 41. Specifically, any suitable electrical connection method may be used. The gate structure 30 is used to transfer the photogenerated electrons generated by the photoelectric conversion region 11 to the floating gate diffusion structure 41, and the floating gate diffusion structure 41 transfers the overflowing photogenerated electrons to the photogenerated electron storage structure 42. Afterwards, when the photogenerated electron storage structure 42 is full of photogenerated electrons, the overflowing photogenerated electrons are transferred to the storage structure 20.

[0154] Based on the above structure, in some examples, the above-mentioned photogenerated electron storage area 40 may also include a first switch structure 43, which is arranged between the photogenerated electron storage structure and the floating gate diffusion structure to control the transmission of photogenerated electrons between the floating gate diffusion structure and the photogenerated electron storage structure.

[0155] Optionally, under high light conditions, the first switch structure 43 is turned on to transfer the photogenerated electrons overflowing from the floating gate diffusion structure 41 to the photogenerated electron storage structure 42, and then to the capacitor structure, so that the image sensor can store more photogenerated electrons. Under low light conditions, the first switch structure 43 is turned off to save energy consumption of the image sensor, wherein the control of the first switch structure 43 can be achieved by applying an external signal.

[0156] Based on this, under high light conditions, the photogenerated electrons stored in the image sensor can achieve a larger full-well capacity, thereby improving the dynamic range of the image sensor.

[0157] In an optional implementation, the first switch structure, the photogenerated electron storage structure, and the floating gate diffusion structure form a dual conversion gain transistor.

[0158] Optionally, the first switch structure forms a control electrode of the dual conversion gain transistor; and / or, the floating gate diffusion structure forms an input electrode of the dual conversion gain transistor; and / or, the photogenerated electron storage structure forms an output electrode of the dual conversion gain transistor.

[0159] Based on this, the first switch structure can be prepared in the same layer as the gate structure to save process steps.

[0160] For example, when the gate structure is a trench gate structure, the first switch structure can be prepared at the same layer as the top gate layer of the trench gate structure.

[0161] The above content describes the overall structure of the image sensor improved by the embodiment of the present application, and the following is used to describe the specific structure of the above storage structure.

[0162] Optionally, the storage structure may include a capacitor structure.

[0163] The capacitor structure can store photogenerated electrons in the photoelectric conversion region, and the present embodiment can improve the storage capacity of the capacitor structure by designing a specific implementation method of the capacitor structure to store more photogenerated electrons, thereby improving the dynamic range of the image sensor.

[0164] In a first example, the capacitor structure may include a first capacitor.

[0165] Reference Figure 2 , shows a structural diagram of an image sensor including a first capacitor having a capacitor structure. The first capacitor includes a first substrate 21 and a second substrate 22.

[0166] The first capacitor is used to store the photogenerated electrons generated by the photoelectric conversion region 11, so as to increase the photogenerated electron storage capacity of the image sensor by providing an additional storage structure, thereby improving the dynamic range of the image sensor.

[0167] In this example, one substrate (the first substrate 21 or the second substrate 22) in the first capacitor is connected to the photogenerated electron storage area 40. Optionally, the first substrate 21 in the first capacitor is electrically connected to the photogenerated electron storage area 40. Or, the second substrate 22 in the first capacitor is electrically connected to the photogenerated electron storage area 40.

[0168] In one embodiment, when the photo-generated electron storage region 40 includes a floating gate diffusion structure 41 , a substrate in the first capacitor is electrically connected to the floating gate diffusion structure 41 .

[0169] For another example, when the photo-generated electron storage region 40 includes a floating gate diffusion structure 41 and a photo-generated electron storage structure 42 , a substrate in the first capacitor is electrically connected to the photo-generated electron storage structure 42 .

[0170] Optional, see Figure 2 The second substrate 22 is made of the same material as the gate layer of the gate structure 30 of the image sensor.

[0171] The gate structure 30 includes a trench gate structure. Along the thickness direction of the substrate 10, the second substrate 22 is prepared at the same layer as the top gate layer of the trench gate structure.

[0172] It should be understood that the trench gate structure includes a vertical portion formed in the trench and a top portion formed on the trench, and both the vertical portion and the top portion include a gate dielectric layer and a gate layer formed in sequence.

[0173] Based on this, the second substrate of the first capacitor can be prepared while preparing the trench gate structure, so as to save process steps and further save manufacturing costs.

[0174] Reference Figure 2Optionally, the image sensor further includes an isolation layer 12 ; the isolation layer 12 is disposed in the substrate 10 and is located on the backlight side of the photoelectric conversion region 11 .

[0175] In this embodiment, the isolation layer is used to isolate the photoelectric conversion region and the capacitor structure, reduce the surface dark current of the photoelectric conversion region and the storage structure, and avoid the storage structure affecting the performance of the photoelectric conversion region.

[0176] On this basis, the first substrate 21 can be arranged inside the base to save the area occupied by the entire capacitor structure on the backlight side surface of the photoelectric conversion region, thereby increasing the integration of the image sensor.

[0177] Optionally, the isolation layer 12 is a layer formed by doping the substrate 10 with first conductive type ions from the backlight side of the substrate 10. On this basis, the first substrate 21 can be set in the isolation layer. At this time, the first substrate 21 is a doping layer formed by doping the isolation layer 12 with second conductive type ions.

[0178] The implementation of the first substrate may include:

[0179] The isolation layer is doped with second conductivity type doping ions to form a second conductivity type doping layer, and the second conductivity type doping layer is formed in the isolation layer as the first substrate.

[0180] The thickness of the first substrate is smaller than the thickness of the isolation layer, so as to ensure that the first substrate is completely wrapped by the isolation layer, thereby ensuring the functionality of the photoelectric conversion region.

[0181] Exemplarily, the ratio of the thickness of the first substrate to the thickness of the isolation layer is in a range of 1 / 5 to 1 / 3.

[0182] Within this numerical range, the functionality of the first substrate can be ensured, and it can also be ensured that the first substrate will not affect the function of the photoelectric conversion region itself.

[0183] For example, the ratio of the thickness of the first substrate to the thickness of the isolation layer is 1 / 5.

[0184] For another example, the ratio of the thickness of the first substrate to the thickness of the isolation layer is 1 / 4.

[0185] For another example, the ratio of the thickness of the first substrate to the thickness of the isolation layer is 1 / 3.

[0186] Furthermore, the doping concentration of the second conductive type doped ions needs to be greater than the doping concentration of the isolation layer to ensure that the region of the isolation layer doped with the second conductive type ions is completely inverted.

[0187] Optional, see Figure 2A first dielectric layer is disposed between the first substrate 21 and the second substrate 22 , and the first dielectric layer is used to store the photogenerated electrons.

[0188] In some examples, considering the preparation process and manufacturing cost, the first dielectric layer is made of the same material as the gate oxide layer of the trench gate structure. The first dielectric layer is prepared at the same layer as the top gate oxide layer of the trench gate structure.

[0189] In a second example, the capacitor structure may include a plurality of capacitors connected in parallel.

[0190] For example, a first capacitor, a second capacitor, and a third capacitor connected in parallel.

[0191] For another example, a first capacitor and a second capacitor are connected in parallel.

[0192] Reference Figure 1 The first capacitor includes a first substrate 21 and a second substrate 22. The second capacitor includes a second substrate 22 and a third substrate 23. The first substrate is electrically connected to the third substrate through a wire; and / or the second substrate is electrically connected to the photogenerated electron storage area through a wire, and the second substrate is located between the first substrate and the third substrate, serving as a common substrate for the first capacitor and the second capacitor. The above structure is used to realize the parallel connection of the first capacitor and the second capacitor.

[0193] It should be understood that the calculation formula for capacitance is: Where A is the effective area of ​​the upper and lower substrates, ε0 is the vacuum dielectric constant, ε x is the dielectric constant of the dielectric layer between the substrates, and d is the distance between the upper and lower substrates. Therefore, increasing the capacitance can be achieved by increasing the effective area A between the substrates and the dielectric constant εx of the dielectric layer between the substrates, and reducing the spacing between the two substrates. Since the capacitor structure in the embodiment of the present application is placed on the surface of the photoelectric conversion area, A is limited by the area of ​​the photoelectric conversion area, and the substrate spacing needs to maintain a certain thickness to ensure leakage current safety.

[0194] Therefore, in the embodiment of the present application, a first capacitor and a second capacitor connected in parallel are arranged on the surface of the photoelectric conversion region to achieve twice the capacitance value on the surface of the photoelectric conversion region, thereby increasing the storage capacity of photogenerated electrons to a certain extent.

[0195] It should be understood that the above-mentioned first capacitor and second capacitor structure can not only reduce the difficulty of image sensor design, but also increase the flexibility of image sensor design. Specifically, the total capacitance can be adjusted by the effective area of ​​the upper and lower substrates and the material type of the dielectric layer between the first substrate and the second substrate, and the material type of the dielectric layer between the second substrate and the third substrate to increase the full well capacity, thereby achieving the purpose of improving the dynamic range of the image sensor.

[0196] In this example, refer to Figure 1 The second substrate 22 can be connected to the photogenerated electron storage area 40 through a wire. Based on this, the first capacitor and the second capacitor can be used to store the photogenerated electrons overflowing from the photogenerated electron storage area.

[0197] Optionally, based on the above structure, the photogenerated electron storage area 40 is used to preferentially store the photogenerated electrons generated by the photoelectric conversion area 11. When the photogenerated electron storage area 40 is full of photogenerated electrons, the overflowed photogenerated electrons are transferred to the second substrate 22 to store more photogenerated electrons through the first capacitor and the second capacitor, thereby increasing the storage capacity of photogenerated electrons.

[0198] For example, when the photogenerated electron storage area includes a floating gate diffusion structure, the second substrate is connected to the floating gate diffusion structure to transfer the photogenerated electrons overflowing from the floating gate diffusion structure to the first capacitor and the second capacitor, thereby increasing the storage capacity of the photogenerated electrons and further increasing the full well capacity, thereby achieving the purpose of improving the dynamic range of the image sensor.

[0199] For example, refer to Figure 1 When the photogenerated electron storage area 40 includes the floating gate diffusion structure 41 and the photogenerated electron storage structure 42, the second substrate 22 is connected to the photogenerated electron storage structure 42, and is used to transfer the photogenerated electrons overflowing from the photogenerated electron storage structure 42 to the first capacitor and the second capacitor, thereby increasing the storage capacity of the photogenerated electrons, thereby increasing the full well capacity, and achieving the purpose of improving the dynamic range of the image sensor. According to the above description, the photogenerated electron storage structure 42 is used to store the photogenerated electrons overflowing from the floating gate diffusion structure 41. Compared with the structure in which the photogenerated electron storage area 40 only includes the floating gate diffusion structure 41, this structure can further increase the storage capacity of the photogenerated electrons.

[0200] In this example, the floating gate diffusion structure 41 is disposed on a side of the gate structure 30 that is away from the photoelectric conversion region 11 .

[0201] During operation, a light signal is incident on the light incident side 111 of the photoelectric conversion region 11, and photogenerated electrons are generated in the photoelectric conversion region 11. The photogenerated electrons are transmitted outwardly to the photogenerated electron storage region 40 through the gate structure. When the photogenerated electron storage region 40 is full of photogenerated electrons, the overflowing photogenerated electrons are transmitted to the second substrate to ensure that the photoelectric conversion region 11 can generate more photogenerated electrons.

[0202] In this example, the first switch structure 43 is connected to the floating gate diffusion structure 41 and the photogenerated electron storage structure 42 to control the transmission of the photogenerated electrons between the floating gate diffusion structure 41 and the photogenerated electron storage structure 42 .

[0203] Optional, see Figure 1 The second substrate 22 is made of the same material as the gate layer of the gate structure 30 of the image sensor.

[0204] The gate structure 30 includes a trench gate structure. Along the thickness direction of the substrate 10, the second substrate 22 is prepared at the same layer as the top gate layer of the trench gate structure.

[0205] It should be understood that the trench gate structure includes a vertical portion formed in the trench and a top portion formed on the trench, and both the vertical portion and the top portion include a gate dielectric layer and a gate layer formed in sequence.

[0206] Based on this, the second substrate of the first capacitor can be prepared while preparing the trench gate structure, so as to save process steps and further save manufacturing costs.

[0207] Reference Figure 1 Optionally, the image sensor further includes an isolation layer 12 ; the isolation layer 12 is disposed in the substrate 10 and is located on the backlight side of the photoelectric conversion region 11 .

[0208] In this embodiment, the isolation layer is used to isolate the photoelectric conversion region and the capacitor structure, reduce the surface dark current of the photoelectric conversion region and the storage structure, and avoid the storage structure affecting the performance of the photoelectric conversion region.

[0209] On this basis, the first substrate 21 can be arranged inside the base to save the area occupied by the entire capacitor structure on the backlight side surface of the photoelectric conversion region, thereby increasing the integration of the image sensor.

[0210] Optionally, the isolation layer 12 is a layer formed by doping the substrate 10 with first conductive type ions from the backlight side of the substrate 10. On this basis, the first substrate 21 can be set in the isolation layer. At this time, the first substrate 21 is a doping layer formed by doping the isolation layer 12 with second conductive type ions.

[0211] The implementation of the first substrate may include:

[0212] The isolation layer is doped with second conductivity type doping ions to form a second conductivity type doping layer, and the second conductivity type doping layer is formed in the isolation layer as the first substrate.

[0213] The thickness of the first substrate is smaller than the thickness of the isolation layer, so as to ensure that the first substrate is completely wrapped by the isolation layer, thereby ensuring the functionality of the photoelectric conversion region.

[0214] Exemplarily, the ratio of the thickness of the first substrate to the thickness of the isolation layer is in a range of 1 / 5 to 1 / 3.

[0215] Within this numerical range, the functionality of the first substrate can be ensured, and it can also be ensured that the first substrate will not affect the function of the photoelectric conversion region itself.

[0216] For example, the ratio of the thickness of the first substrate to the thickness of the isolation layer is 1 / 5.

[0217] For another example, the ratio of the thickness of the first substrate to the thickness of the isolation layer is 1 / 4.

[0218] For another example, the ratio of the thickness of the first substrate to the thickness of the isolation layer is 1 / 3.

[0219] Furthermore, the doping concentration of the second conductive type doped ions needs to be greater than the doping concentration of the isolation layer to ensure that the region of the isolation layer doped with the second conductive type ions is completely inverted.

[0220] Optional, see Figure 1 A first dielectric layer is disposed between the first substrate 21 and the second substrate 22 , and the first dielectric layer is used to store the photogenerated electrons.

[0221] In some examples, considering the preparation process and manufacturing cost, the first dielectric layer is made of the same material as the gate oxide layer of the trench gate structure. The first dielectric layer is prepared at the same layer as the top gate oxide layer of the trench gate structure.

[0222] Reference Figure 1 A second dielectric layer is disposed between the second substrate 22 and the third substrate 23, and the second dielectric layer is used for storing the photogenerated electrons.

[0223] In some other examples, the second dielectric layer between the second substrate and the third substrate may be a semiconductor material layer and a high dielectric constant material layer. The material of the dielectric layer may be adjusted according to the design requirements of the image sensor.

[0224] When the dielectric layer between the second substrate and the third substrate is made of a semiconductor material layer, the electrical properties of the dielectric layer can be changed by doping and electric field regulation. Using semiconductor material as the dielectric layer can improve the lattice matching between the dielectric layer and the second substrate.

[0225] When the dielectric layer between the second substrate and the third substrate is made of a high dielectric constant material layer, the capacitance of the second capacitor can be increased, thereby increasing the storage capacity of photogenerated electrons.

[0226] The material of the semiconductor material layer may be silicon dioxide, silicon nitride, etc. The material of the high dielectric constant material layer may be aluminum oxide and hafnium dioxide.

[0227] In the second example, the first substrate is connected to the third substrate and to FCVDD, wherein FCVDD is used to provide a fixed voltage value ranging from 0 to VDD, and the second substrate is connected to one end of the dual conversion gain transistor.

[0228] For the third example, refer to Figure 3The capacitor structure includes a first junction capacitor 241 for storing photogenerated electrons. The first junction capacitor 241 is electrically connected to the photogenerated electron storage area 40.

[0229] Here is an explanation of junction capacitance: Junction capacitance exists in the depletion region of the PN junction. The PN junction is composed of a P-type semiconductor and an N-type semiconductor, and a depletion region is formed at the junction of the two. The depletion region is a region without free carriers. Since the carriers in the P-type and N-type regions diffuse and recombine with each other, fixed ionized impurities are left. The width of this region changes with the change of the applied voltage. The junction capacitance is similar to a parallel plate capacitor, whose two plates are respectively composed of the boundaries of the P-type and N-type regions, and the depletion region is equivalent to the dielectric layer. The capacitance of the junction capacitance is inversely proportional to the width of the depletion region.

[0230] In one example, referring to Figure 3 The image sensor includes an isolation layer 12; the isolation layer 12 is arranged in the substrate 10 and is located on the backlight side 112 of the photoelectric conversion area 11; the first junction capacitor 241 is formed in the substrate 10 and is located on the side of the isolation layer 12 away from the photoelectric conversion area 11, so as to increase the integration of the image sensor.

[0231] In this embodiment, the isolation layer is used to isolate the photoelectric conversion region and the first junction capacitor, reduce the surface dark current of the photoelectric conversion region and the storage structure, and avoid the first junction capacitor affecting the performance of the photoelectric conversion region.

[0232] Optionally, the first junction capacitor 241 is disposed in the substrate to save the area occupied by the entire capacitor structure on the backlight side surface of the photoelectric conversion region, thereby increasing the integration of the image sensor.

[0233] Optionally, the isolation layer 12 is a layer formed by doping the substrate 10 with first conductive type ions from the backlight side of the substrate 10 . On this basis, the first junction capacitor 241 may be a junction capacitor formed by doping the isolation layer 12 with second conductive type ions.

[0234] The implementation of the first junction capacitor 241 may include:

[0235] The isolation layer is doped with second conductivity type doping ions to form a second conductivity type doping layer, thereby obtaining a first junction capacitor 241 .

[0236] Furthermore, the doping concentration of the second conductive type doped ions needs to be greater than the doping concentration of the isolation layer to ensure that the region of the isolation layer doped with the second conductive type ions is completely inverted.

[0237] The image sensor further includes a photogenerated electron storage region 40, and the first junction capacitor 241 is connected to the photogenerated electron storage region 40;

[0238] The first junction capacitor 241 is used to store the photogenerated electrons overflowing from the floating gate diffusion structure.

[0239] In this example, the image sensor further includes a gate structure 30, which is connected to the photoelectric conversion region 11. When the gate structure 30 is a vertical gate structure, the bottom end of the vertical gate structure extends into the photoelectric conversion region 11. It should be understood that the gate structure may also be a planar gate structure, which is not specially handled in this embodiment.

[0240] The first junction capacitor 241 may be connected to the photogenerated electron storage area 40 through a conductive wire. Based on this, the first junction capacitor 241 may be used to store the photogenerated electrons overflowing from the photogenerated electron storage area.

[0241] Optionally, based on the above structure, the photogenerated electron storage area 40 is used to preferentially store the photogenerated electrons generated by the photoelectric conversion area 11. When the photogenerated electron storage area 40 is full of photogenerated electrons, the overflowed photogenerated electrons are transferred to the first junction capacitor 241 to store more photogenerated electrons through the first junction capacitor 241, thereby increasing the storage capacity of photogenerated electrons.

[0242] For example, when the photogenerated electron storage area includes a floating gate diffusion structure, the first junction capacitor 241 is connected to the floating gate diffusion structure to transfer the photogenerated electrons overflowing from the floating gate diffusion structure to the first junction capacitor 241, thereby increasing the storage capacity of the photogenerated electrons and further increasing the full well capacity, thereby achieving the purpose of improving the dynamic range of the image sensor.

[0243] For example, refer to Figure 3 When the photogenerated electron storage area 40 includes the floating gate diffusion structure 41 and the photogenerated electron storage structure 42, the first junction capacitor 241 is connected to the photogenerated electron storage structure 42, and is used to transfer the photogenerated electrons overflowing from the photogenerated electron storage structure 42 to the first junction capacitor 241, thereby increasing the storage capacity of the photogenerated electrons, thereby increasing the full well capacity, and achieving the purpose of improving the dynamic range of the image sensor. According to the above description, the photogenerated electron storage structure 42 is used to store the photogenerated electrons overflowing from the floating gate diffusion structure 41. Compared with the structure in which the photogenerated electron storage area 40 only includes the floating gate diffusion structure 41, this structure can further increase the storage capacity of the photogenerated electrons.

[0244] In this example, the floating gate diffusion structure 41 is disposed on a side of the gate structure 30 that is away from the photoelectric conversion region 11 .

[0245] During operation, a light signal is incident on the light incident side 111 of the photoelectric conversion region 11, and photogenerated electrons are generated in the photoelectric conversion region 11. The photogenerated electrons are transmitted outwardly to the photogenerated electron storage region 40 through the gate structure. When the photogenerated electron storage region 40 is full of photogenerated electrons, the overflowing photogenerated electrons are transmitted to the first junction capacitor 241 to ensure that the photoelectric conversion region 11 can generate more photogenerated electrons.

[0246] In this example, the first switch structure 43 is connected to the floating gate diffusion structure 41 and the photogenerated electron storage structure 42 to control the transmission of the photogenerated electrons between the floating gate diffusion structure 41 and the photogenerated electron storage structure 42 .

[0247] For the fourth example, refer to Figure 4 The capacitor structure may include a first junction capacitor 241 and a second junction capacitor 242 , and both the first junction capacitor 241 and the second junction capacitor 242 are used to store photogenerated electrons.

[0248] In one example, the image sensor includes an isolation layer 12; the isolation layer 12 is arranged in the substrate 10 and is located on the backlight side 112 of the photoelectric conversion region 11; the first junction capacitor 241 and the second junction capacitor 242 are formed in the substrate 10 and are located on the side of the isolation layer 12 away from the photoelectric conversion region 11, so as to increase the integration of the image sensor.

[0249] In one example, referring to Figure 4 The image sensor includes an isolation layer 12; the isolation layer 12 is arranged in the substrate 10 and is located on the backlight side 112 of the photoelectric conversion area 11; the first junction capacitor 241 and the second junction capacitor 242 are formed in the substrate 10 and are located on the side of the isolation layer 12 away from the photoelectric conversion area 11, so as to increase the integration of the image sensor.

[0250] In this embodiment, the isolation layer is used to isolate the photoelectric conversion region and the first junction capacitor 241 and the second junction capacitor 242, reducing the surface dark current of the photoelectric conversion region and the storage structure to avoid the first junction capacitor 241 and the second junction capacitor 242 affecting the performance of the photoelectric conversion region.

[0251] Optionally, the first junction capacitor 241 and the second junction capacitor 242 are arranged in the substrate, and the first junction capacitor 241 and the second junction capacitor 242 are located on the backlight side of the photoelectric conversion region 11 to save the area occupied by the entire capacitor structure on the backlight side surface of the photoelectric conversion region, thereby increasing the integration of the image sensor.

[0252] Optionally, the isolation layer 12 is a layer formed by doping the substrate 10 with first conductive type ions from the backlight side of the substrate 10 , and on this basis, the first junction capacitor 241 and the second junction capacitor 242 may be junction capacitors formed by doping the isolation layer 12 with second conductive type ions.

[0253] The implementation of the first junction capacitor 241 and the second junction capacitor 242 may include:

[0254] The isolation layer is doped with second conductivity type doping ions to form a second conductivity type doping layer, thereby obtaining a first junction capacitor 241 and a second junction capacitor 242 .

[0255] Furthermore, the doping concentration of the second conductive type doped ions needs to be greater than the doping concentration of the isolation layer to ensure that the region of the isolation layer doped with the second conductive type ions is completely inverted.

[0256] The image sensor further includes a floating gate diffusion structure 41, and a first junction capacitor 241 and a second junction capacitor 242 are connected to the floating gate diffusion structure;

[0257] The first junction capacitor 241 and the second junction capacitor 242 are used to store the photogenerated electrons overflowing from the floating gate diffusion structure.

[0258] In this example, the image sensor further includes a gate structure 30, which is connected to the photoelectric conversion region 11. When the gate structure 30 is a vertical gate structure, the bottom end of the vertical gate structure extends into the photoelectric conversion region 11. It should be understood that the gate structure may also be a planar gate structure, which is not specially handled in this embodiment.

[0259] During operation, a light signal is incident on the light incident side 111 of the photoelectric conversion region 11, and photogenerated electrons are generated in the photoelectric conversion region 11. The photogenerated electrons are transmitted outwardly to the floating gate diffusion structure 41 through the gate structure 30 to ensure that the photoelectric conversion region 11 can generate more photogenerated electrons.

[0260] In this example, the capacitor structure further includes a second switch structure 25 , and the second switch structure 25 is located at the backlight side of the photoelectric conversion region 11 .

[0261] The second switch structure 25 is disposed on a side of the substrate 10 away from the photoelectric conversion region 11 .

[0262] The second switch structure 25 and the floating gate diffusion structure 41 are located between the first junction capacitor 241 and the second junction capacitor 242 , and are used to control the transmission of photogenerated electrons between the floating gate diffusion structure 41 and the first junction capacitor 241 or the second junction capacitor 242 .

[0263] Optionally, under high light conditions, the second switch structure 25 is turned on to store more photogenerated electrons using the first junction capacitor 241 and the second junction capacitor 242. Under low light conditions, the second switch structure 25 is turned off to save energy consumption of the image sensor, wherein the control of the second switch structure 25 can be achieved by applying an external signal, which will not be described in detail here.

[0264] Based on this, under high light conditions, the stored photogenerated electrons can achieve a larger full-well capacity and thus improve the dynamic range of the image sensor.

[0265] In an optional implementation, the second switch structure 25 , the first junction capacitor 241 , and the second junction capacitor 242 form a dual conversion gain transistor.

[0266] Optionally, the second switch structure 25 forms a control electrode of the dual conversion gain transistor; and / or, the first junction capacitor 241 forms an input electrode of the dual conversion gain transistor; and / or, the second junction capacitor 242 forms an output electrode of the dual conversion gain transistor.

[0267] Based on this, the second switch structure 25 can be prepared in the same layer as the gate structure to save process steps.

[0268] It should be understood that, relative to the first, second and third examples, the second switch structure 25 of the fourth example is arranged on the backlight side of the photoelectric conversion region. In the image sensor, the area where the first switch structure 43 in the first and second examples is arranged can be saved, thereby improving the integration of the image sensor.

[0269] In a second aspect, the present application also provides a method for preparing an image sensor, comprising the following steps:

[0270] Reference Figure 5 , providing a substrate, the substrate comprising a photoelectric conversion region, the photoelectric conversion region having a light incident side and a backlight side opposite to each other, the first side being used to receive an optical signal.

[0271] The photoelectric conversion region 11 is used to realize photoelectric conversion. Photons are incident on the photoelectric conversion region 11 from the light incident side 111 , so that the photoelectric conversion region 11 generates photogenerated electrons.

[0272] Reference Figure 1 , Figure 2 , Figure 3 or Figure 4 , forming a storage structure, wherein the storage structure is arranged on the backlight side of the photoelectric conversion region and is used to store the photogenerated electrons generated by the photoelectric conversion region.

[0273] The storage structure 20 is arranged on the backlight side 112. In the related art, there is no structure on the surface of the backlight side 112. However, in this embodiment, a storage structure is arranged on the surface of the backlight side 112 to store photogenerated electrons. Therefore, this embodiment can improve the integration of the image sensor without affecting the performance of the image sensor.

[0274] This embodiment can also utilize the storage structure 20 to store photogenerated electrons generated in the photoelectric conversion region under high light conditions to achieve a larger full well capacity, thereby improving the dynamic range of the image sensor.

[0275] Moreover, in this embodiment, a storage structure is arranged on the backlight side of the photoelectric conversion region, and the storage structure does not occupy the area of ​​the photoelectric conversion region itself, so it does not squeeze the area of ​​the photoelectric conversion region, thereby avoiding the decrease of the fill factor. Furthermore, the storage structure of this embodiment only needs to be connected to the photogenerated electron transmission structure of the image sensor to achieve the reception and storage of photogenerated electrons, so this application can reduce the overall design complexity of the image sensor.

[0276] Optionally, providing a substrate may include:

[0277] A layer of base material is provided.

[0278] Among them, the base material layer can be made of silicon material, but is not limited to silicon, and can also be any other material suitable for power devices, such as silicon carbide, gallium nitride, diamond, etc. The embodiment of the present application does not make specific limitations on this.

[0279] The base material layer is doped to form the photoelectric conversion region in the base material layer.

[0280] Specifically, the substrate material layer can be doped by ion implantation or diffusion process to form a pn junction or pin structure in the substrate material layer, and the substrate has pad oxide and shallow trench isolation to define the photoelectric conversion area. Among them, the doping concentration and doping range can be controlled according to actual needs to optimize the photoelectric conversion efficiency and charge collection efficiency.

[0281] Optionally, the storage structure is a capacitor structure, and forming the storage structure includes:

[0282] On the backlight side of the photoelectric conversion region, a capacitor structure is formed.

[0283] The capacitor structure can store photogenerated electrons in the photoelectric conversion region, and the present embodiment can improve the storage capacity of the capacitor structure by designing a specific implementation method of the capacitor structure to store more photogenerated electrons, thereby improving the dynamic range of the image sensor.

[0284] In a possible implementation, before forming the storage structure, the method further includes:

[0285] Reference Figure 6 , the photoelectric conversion region is doped with first conductive type ions from the backlight side of the substrate 10 to form an isolation layer 12.

[0286] In this embodiment, the isolation layer 12 is used to isolate the photoelectric conversion region and the storage structure, reduce the surface dark current of the photoelectric conversion region and the storage structure, and avoid the storage structure affecting the performance of the photoelectric conversion region.

[0287] In one example, the capacitor structure includes a first capacitor; and forming the capacitor structure on the backlight side of the photoelectric conversion region includes:

[0288] Reference Figure 7 , from the backlight side of the substrate 10, the isolation layer 12 is doped with second conductive type ions to form a first substrate 21;

[0289] Furthermore, a second substrate 22 is formed on a side of the first substrate 21 away from the photoelectric conversion region 11 ; the first substrate 21 and the second substrate 22 form the first capacitor.

[0290] In another example, the capacitor structure includes a first capacitor and a second capacitor connected in parallel; and forming the capacitor structure on the backlight side of the photoelectric conversion region includes:

[0291] Reference Figure 5 , from the backlight side of the substrate, doping the isolation layer 12 with ions of the second conductive type to form a first substrate 21;

[0292] Reference Fig. 9 A second substrate 22 is formed on a side of the first substrate 21 away from the photoelectric conversion region 11 .

[0293] Afterwards, refer to Fig.12 , forming a third substrate 23 on a side of the second substrate 22 away from the first substrate 21;

[0294] The first substrate 21 and the second substrate 22 form the first capacitor, and the second substrate 22 and the third substrate 23 form the second capacitor.

[0295] In the above two examples, the doping concentration of the second conductive type ions in the first substrate is greater than the doping concentration of the first conductive type ions in the isolation layer, so as to ensure that the region of the first conductive type ions in the first substrate is completely inverted.

[0296] For example, the doping concentration of the second conductive type ion doping is about 2 orders of magnitude greater than the doping concentration of the first conductive type ion doping.

[0297] Optionally, before forming the second substrate on a side of the first substrate away from the photoelectric conversion region, the method further includes:

[0298] Reference Figure 8 , from the backlight side of the substrate, a gate groove 301 is formed in the substrate; the gate groove 301 is arranged on one side of the second substrate 21 , and the bottom of the gate groove is located in the photoelectric conversion region 11 .

[0299] The gate groove is used for subsequently forming a gate structure.

[0300] Specific steps may include:

[0301] The position and shape of the gate groove are defined using photolithography, and then the groove is formed in the substrate from the backlight side of the photoelectric conversion area by dry etching.

[0302] Reference Fig. 9 In an optional embodiment, forming a second substrate on a side of the first substrate away from the photoelectric conversion region comprises:

[0303] From the opening direction of the gate groove, a gate oxide layer 310 and a gate material layer are sequentially formed on the substrate 10 and in the gate groove;

[0304] The gate material layer is patterned to form a second substrate 22 .

[0305] While patterning the gate material layer to form the second substrate 22 , the method further includes: forming a gate structure 30 and a first switch structure 43 .

[0306] Based on this, the gate structure and the second substrate are prepared using a unified step, which reduces the process steps and saves costs. Based on this, the second substrate and the gate structure are prepared using the same material.

[0307] Optionally, after forming the gate structure, the method further includes:

[0308] Reference Fig.10 , a sidewall spacer 302 is formed on both sides of the gate structure 30 , the second substrate 22 and the first switch structure 43 .

[0309] The process of forming the sidewall in this embodiment may include: depositing a uniform insulating material on the substrate, which may be silicon dioxide (SiO2) or silicon nitride (Si3N4). Anisotropic dry etching (such as reactive ion etching, RIE) is used to remove the horizontal portion of the insulating material, leaving only the vertical portion. After etching, the insulating material is retained only on both sides of the gate structure to form a sidewall. The sidewall provides electrical isolation and helps control subsequent ion implantation.

[0310] Reference Fig.11A photo-generated electron storage region 40 is formed in the substrate 10. The photo-generated electron storage region 40 includes a floating gate diffusion structure 41 and a photo-generated electron storage structure 42 connected to each other. The floating gate diffusion structure 41 is disposed on a side of the gate structure 30 away from the second substrate 22 structure.

[0311] In this embodiment, the regions of the floating gate diffusion structure 41 and the photogenerated electron storage structure 42 are first defined, and then ions are implanted into the substrate by ion implantation to form the floating gate diffusion structure 41 and the photogenerated electron storage structure 42 .

[0312] The specific functions and effects of the floating gate diffusion structure 41 and the photogenerated electron storage structure 42 can be referred to the description of the image sensor in the first aspect, and will not be described in detail in this embodiment.

[0313] In yet another example, the capacitor structure includes a first junction capacitor, and forming the capacitor structure includes:

[0314] The designated area of ​​the isolation layer is doped with ions of the second conductive type to form a first junction capacitor.

[0315] In yet another example, the capacitor structure includes a first junction capacitor and a second junction capacitor, and forming the capacitor structure includes:

[0316] In the isolation layer, a first junction capacitor and a second junction capacitor are formed.

[0317] It should be understood that the junction capacitance is a capacitance formed by a pn junction. Specifically, a doping layer of the second conductivity type may be formed in the isolation layer to form a pn junction. This step may generally be achieved by photolithography and ion implantation processes to ensure accurate positioning of the doped region.

[0318] In a possible implementation, the storage structure further includes a second switch structure;

[0319] While patterning the gate material layer to form the second substrate, the method further includes:

[0320] The second switch structure is formed, wherein the second switch structure is located between the first junction capacitance and the second junction capacitance.

[0321] The second switch structure is arranged on the backlight side of the photoelectric conversion region. Compared with the related art, the area of ​​the region where the second switch structure is arranged can be saved, thereby improving the integration of the image sensor.

[0322] In a specific embodiment, the above method may include:

[0323] 1) A semiconductor substrate is provided, wherein the substrate has an oxide pad, shallow trench isolation and a defined photoelectric conversion region. The steps before this process are the same as the manufacturing process of a traditional vertical gate image sensor.

[0324] 2) Using photoresist as a barrier layer, P-type doping is injected into the surface of the photoelectric conversion region through ion implantation to form an isolation layer, which is used to isolate the substrate from the photoelectric conversion region and reduce the dark current caused by surface defects. In the manufacturing process of the traditional vertical gate image sensor, the isolation layer is implanted after the gate material is deposited. In this embodiment, the implantation is advanced to before the gate material is deposited, mainly because the polysilicon gate on the surface of the subsequent photoelectric conversion region needs to be retained, so the implantation on the surface of the photoelectric conversion region needs to be completed before the implantation.

[0325] 3) After the isolation layer is implanted, a high dose of second conductive type ions is implanted into the isolation layer region using the photoresist as a barrier layer through ion implantation, and then the photoresist is removed. The implantation depth of the second conductive type ions is lower than the implantation depth of the isolation layer, which is about 1 / 5 to 1 / 3 of the implantation depth of the isolation layer. The dose of the second conductive type doped layer is greater than the dose of the isolation layer, which is about 2 orders of magnitude, to ensure that the silicon surface is completely inverted. The second conductive type doped layer is used to form the first substrate of the capacitor structure.

[0326] 4) Vertical gate groove etching, silicon oxide growth and polysilicon filling etching are performed in the photoelectric conversion area of ​​the substrate to form a polysilicon gate. At this time, in addition to the gates required by each device, the gate on the surface of the photoelectric conversion area must also be retained. The gate serves as a conductive substrate of the capacitor, namely the above-mentioned second substrate.

[0327] 5) After the gate etching is completed, a sidewall process and a doping process are performed to form a floating gate diffusion structure.

[0328] 6) After the doping is completed, the dielectric layer is filled and CMP (Chemical Mechanical Planarization) is performed.

[0329] 7) Deposit a dielectric layer on the flat surface and deposit polysilicon again; the dielectric layer deposited at this time is called the first dielectric layer. The material of the dielectric layer can be silicon dioxide, silicon nitride, or high dielectric constant materials such as aluminum oxide and hafnium dioxide. The thickness can be the same as the gate oxide layer or slightly thinner, and the thickness of polysilicon is consistent with the gate polysilicon thickness, about 1000A.

[0330] 8) After the deposition of polysilicon is completed, the photoresist is used as a barrier layer, and only the polysilicon on the surface of the photoelectric conversion area is retained as the third substrate of the capacitor structure. After completing the above process, the required connection port is formed. The image sensor is finally formed.

[0331] In a third aspect, an embodiment of the present application further provides a chip, which includes the image sensor described in the first aspect or includes an image sensor prepared using the method of the second aspect.

[0332] In actual applications, the chip is used in new energy vehicles, smart home appliances, rail transit, aerospace and other fields.

[0333] In a fourth aspect, an embodiment of the present application further provides a device, comprising the image sensor of the first aspect, or comprising an image sensor prepared using the method of the second aspect.

[0334] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit it. Although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present application.

Claims

1. An image sensor, characterized in that: include: A substrate (10); the substrate (10) comprises a photoelectric conversion region (11); A storage structure (20); the storage structure (20) is arranged on the backlight side (112) of the photoelectric conversion region (11) and is used to store photogenerated electrons generated by the photoelectric conversion region (11).

2. The image sensor according to claim 1, characterized in that The image sensor further comprises a photogenerated electron storage area (40), and the storage structure (20) is connected to the photogenerated electron storage area (40) and is used to store the photogenerated electrons overflowing from the photogenerated electron storage area (40).

3. The image sensor according to claim 2, characterized in that The image sensor further comprises a gate structure (30); the gate structure (30) is connected to the photoelectric conversion region (11).

4. The image sensor according to claim 3, characterized in that: The photogenerated electron storage region (40) is arranged on a side of the gate structure (30) away from the photoelectric conversion region (11); The gate structure (30) is used to transmit the photogenerated electrons generated by the photoelectric conversion region (11) to the photogenerated electron storage region (40).

5. The image sensor according to claim 4, characterized in that: The photogenerated electron storage area (40) includes a floating gate diffusion structure (41); The gate structure (30) is used to transmit the photogenerated electrons generated by the photoelectric conversion region (11) to the floating gate diffusion structure (41).

6. The image sensor according to claim 5, characterized in that The photogenerated electron storage area (40) further includes a photogenerated electron storage structure (42); The photogenerated electron storage structure (42) is connected to the floating gate diffusion structure (41) and the storage structure (20), and is used to store the photogenerated electrons overflowing from the gate diffusion structure, and to transmit the photogenerated electrons overflowing from the gate diffusion structure to the storage structure (20).

7. The image sensor according to claim 6, characterized in that: The image sensor further comprises a first switch structure (43), which is arranged between the photogenerated electron storage structure (42) and the floating gate diffusion structure (41) and is used to control the transmission of photogenerated electrons between the floating gate diffusion structure (41) and the photogenerated electron storage structure (42).

8. The image sensor according to claim 7, characterized in that: The first switch structure (43), the photogenerated electron storage structure (42) and the floating gate diffusion structure (41) form a dual conversion gain transistor.

9. The image sensor according to claim 8, characterized in that: The first switch structure (43) forms a control electrode of the dual conversion gain transistor; And / or, the floating gate diffusion structure (41) forms an input electrode of the dual conversion gain transistor; And / or, the photogenerated electron storage structure (42) forms the output electrode of the dual conversion gain transistor.

10. The image sensor according to any one of claims 2 to 9, characterized in that: The storage structure (20) comprises a capacitor structure.

11. The image sensor according to claim 10, characterized in that: The capacitor structure includes a first capacitor.

12. The image sensor according to claim 11, characterized in that The first capacitor includes a first substrate and a second substrate.

13. The image sensor according to claim 12, characterized in that: The second substrate (22) is made of the same material as the gate layer of the gate structure (30) of the image sensor.

14. The image sensor according to claim 13, characterized in that: The gate structure (30) comprises a trench gate structure.

15. The image sensor according to claim 14, characterized in that: Along the thickness direction of the base (10), the second substrate (22) is prepared on the same layer as the top gate layer of the trench gate structure.

16. The image sensor according to claim 12, characterized in that: The first substrate or the second substrate is electrically connected to the photogenerated electron storage area (40).

17. The image sensor according to claim 11, characterized in that: The first capacitor includes a first junction capacitor (241).

18. The image sensor according to claim 17, characterized in that: The first junction capacitor (241) is electrically connected to the photogenerated electron storage area (40).

19. The image sensor according to claim 10, characterized in that The capacitor structure includes a plurality of capacitors.

20. The image sensor according to claim 19, characterized in that The plurality of capacitors include a first capacitor and a second capacitor connected in parallel.

21. The image sensor according to claim 20, characterized in that The first capacitor comprises a first substrate (21) and a second substrate (22).

22. The image sensor according to claim 21, characterized in that The second capacitor comprises the second substrate (22) and a third substrate (23).

23. The image sensor according to claim 22, characterized in that The first substrate (21) is electrically connected to the third substrate (23).

24. The image sensor according to claim 22, characterized in that The second substrate (22) is electrically connected to the photogenerated electron storage area (40).

25. The image sensor according to claim 22, characterized in that The second substrate (22) is located between the first substrate (21) and the third substrate (23).

26. The image sensor according to claim 22, characterized in that The second substrate (22) is made of the same material as the gate layer of the gate structure (30) of the image sensor.

27. The image sensor according to claim 26, characterized in that The gate structure (30) comprises a trench gate structure.

28. The image sensor according to claim 27, characterized in that Along the thickness direction of the base (10), the second substrate (22) is prepared on the same layer as the top gate layer of the trench gate structure.

29. The image sensor according to claim 27, characterized in that A first dielectric layer is provided between the first substrate (21) and the second substrate (22), and the first dielectric layer is used for storing the photogenerated electrons.

30. The image sensor according to claim 29, characterized in that The first dielectric layer is made of the same material as the gate oxide layer of the trench gate structure.

31. The image sensor according to claim 30, characterized in that The first dielectric layer is prepared in the same layer as the top gate oxide layer of the trench gate structure.

32. The image sensor according to claim 22, characterized in that A second dielectric layer is provided between the second substrate (22) and the third substrate (23), and the second dielectric layer is used for storing the photogenerated electrons.

33. The image sensor according to claim 32, characterized in that The second dielectric layer is a dielectric layer with a high dielectric constant.

34. The image sensor according to claim 21, characterized in that The first substrate (21) is arranged in the base (10).

35. The image sensor according to claim 34, characterized in that The first substrate (21) is located on the backlight side (112) of the photoelectric conversion region (11).

36. The image sensor according to claim 21, characterized in that The image sensor comprises an isolation layer (12) arranged in the base (10), wherein the isolation layer is used to isolate the first substrate (21) and the photoelectric conversion region (11).

37. The image sensor according to claim 36, characterized in that The isolation layer (12) is at least partially disposed between the first substrate (21) and the photoelectric conversion region (11).

38. The image sensor according to claim 37, characterized in that The isolation layer (12) is a layer formed by doping the substrate (10) with ions of the first conductive type.

39. The image sensor according to claim 38, characterized in that The first substrate (21) is a layer formed by doping the isolation layer (12) with ions of the second conductivity type.

40. The image sensor according to claim 39, characterized in that The thickness of the first substrate (21) is smaller than the thickness of the isolation layer (12).

41. The image sensor according to claim 40, characterized in that The ratio of the thickness of the first substrate (21) to the thickness of the isolation layer (12) is in the range of 1 / 5 to 1 / 3.

42. The image sensor according to claim 19, characterized in that The plurality of capacitors include a first capacitor, a second capacitor and a third capacitor.

43. The image sensor according to claim 19, characterized in that: The capacitor structure includes a first junction capacitor (241) and a second junction capacitor (242).

44. The image sensor according to claim 42, characterized in that The first junction capacitor (241) or the second junction capacitor (242) is electrically connected to the photogenerated electron storage area (40).

45. The image sensor according to claim 43, characterized in that The photogenerated electron storage area (40) comprises a floating gate diffusion structure (41), and the first junction capacitor (241) or the second junction capacitor (242) is electrically connected to the floating gate diffusion structure (41); The first junction capacitor (241) or the second junction capacitor (242) is used to store the photogenerated electrons overflowing from the floating gate diffusion structure (41).

46. ​​The image sensor according to claim 43, characterized in that The image sensor further comprises a second switch structure (25), wherein the second switch structure (25) is located on the backlight side of the photoelectric conversion region (11).

47. The image sensor according to claim 46, characterized in that The second switch structure (25) is arranged on a side of the substrate (10) away from the photoelectric conversion region (11).

48. The image sensor according to claim 47, characterized in that The second switch structure (25) is arranged between the first junction capacitor (241) and the second junction capacitor (242) and is used to control the transmission of photogenerated electrons between the first junction capacitor (241) and the second junction capacitor (242).

49. The image sensor according to claim 48, characterized in that The second switch structure (25), the first junction capacitor (241) and the second junction capacitor (242) form a dual conversion gain transistor.

50. The image sensor according to claim 49, characterized in that The second switch structure (25) forms a control electrode of the dual conversion gain transistor; and / or, one of the first junction capacitor (241) and the second junction capacitor (242) forms an input electrode of the dual conversion gain transistor; And / or, the other of the first junction capacitor (241) and the second junction capacitor (242) forms an output electrode of the dual conversion gain transistor.

51. The image sensor according to claim 42, characterized in that The image sensor comprises an isolation layer (12) arranged in the substrate (10); the isolation layer (12) is used to isolate the first junction capacitor (241) and the second junction capacitor (242) from the photoelectric conversion region (11).

52. The image sensor according to claim 51, characterized in that The isolation layer (12) is at least partially disposed between the first junction capacitor (241) and the second junction capacitor (242) and the photoelectric conversion region (11).

53. The image sensor according to claim 52, characterized in that The isolation layer (12) is a layer formed by doping the substrate (10) with ions of the first conductive type.

54. The image sensor according to claim 53, characterized in that The first junction capacitor (241) and the second junction capacitor (242) are junction capacitor structures formed by doping the isolation layer (12) with ions of the second conductive type.

55. The image sensor according to claim 52, characterized in that The first junction capacitor (241) and the second junction capacitor (242) are arranged in the substrate.

56. The image sensor according to claim 52, characterized in that The first junction capacitor (241) and the second junction capacitor (242) are located on the backlight side of the photoelectric conversion region (11).

57. A method for preparing an image sensor, characterized in that: The preparation method comprises: providing a substrate, the substrate comprising a photoelectric conversion region; A storage structure is formed, wherein the storage structure is arranged on the backlight side of the photoelectric conversion region and is used to store the photogenerated electrons generated by the photoelectric conversion region.

58. The method according to claim 57, characterized in that The providing of a substrate comprises: providing a base material layer; The base material layer is doped to form the photoelectric conversion region in the base material layer.

59. The method according to claim 57, characterized in that The storage structure is a capacitor structure, and forming the storage structure includes: The capacitor structure is formed on the backlight side of the photoelectric conversion region.

60. The method according to claim 59, characterized in that Before forming the capacitor structure, the method further includes: The substrate is doped with first conductive type ions from the backlight side of the substrate to form an isolation layer; the isolation layer is used to isolate the photoelectric conversion area from the capacitor structure.

61. The method according to claim 60, characterized in that The capacitor structure includes a first capacitor; and forming the capacitor structure on the backlight side of the photoelectric conversion region includes: From the backlight side of the substrate, doping the isolation layer with ions of the second conductive type to form a first substrate; A second substrate is formed on a side of the first substrate away from the photoelectric conversion region; the first substrate and the second substrate form the first capacitor.

62. The method according to claim 60, characterized in that The capacitor structure includes a first capacitor and a second capacitor connected in parallel; forming the capacitor structure on the backlight side of the photoelectric conversion region includes: From the backlight side of the substrate, doping the isolation layer with ions of the second conductive type to form a first substrate; forming a second substrate on a side of the first substrate away from the photoelectric conversion region; A third substrate is formed on a side of the second substrate facing away from the first substrate; the first substrate and the second substrate form the first capacitor, and the second substrate and the third substrate form the second capacitor.

63. The method according to any one of claims 61 or 62, characterized in that The doping concentration of the second conductive type ions in the first substrate is greater than the doping concentration of the first conductive type ions in the isolation layer.

64. The method according to claim 61 or 62, characterized in that Before forming a second substrate on a side of the first substrate away from the photoelectric conversion region, the method further includes: A gate groove is formed in the substrate from the backlight side of the substrate; the gate groove is arranged on one side of the capacitor structure, and the bottom of the gate groove is located in the photoelectric conversion area.

65. The method according to claim 64, characterized in that Forming a second substrate on a side of the first substrate away from the photoelectric conversion region comprises: From the opening direction of the gate groove, forming a gate oxide layer and a gate material layer on the substrate and in the gate groove in sequence; The gate material layer is patterned to form the second substrate.

66. The method according to claim 65, characterized in that While patterning the gate material layer to form the second substrate, the method further includes: A gate structure is formed.

67. The method according to claim 66, characterized in that After forming the gate structure, the method further includes: forming sidewalls on both sides of the gate structure and the second substrate; A floating gate diffusion structure is formed in the substrate, and the floating gate diffusion structure is arranged on a side of the gate structure away from the capacitor structure.

68. The method according to claim 65, characterized in that The capacitor structure includes a first junction capacitor, and forming the capacitor structure includes: Doping the designated area of ​​the isolation layer with ions of the second conductive type to form a first junction capacitor.

69. The method according to claim 65, characterized in that: The capacitor structure includes a first junction capacitor and a second junction capacitor, and forming the capacitor structure includes: The designated area of ​​the isolation layer is doped with ions of the second conductive type to form a first junction capacitor and a second junction capacitor.

70. The method according to claim 69, characterized in that The image sensor further comprises a second switch structure, wherein the second switch structure (25) is located on the backlight side of the photoelectric conversion region (11); While patterning the gate material layer to form the second substrate, the method further includes: The second switch structure is formed on a side of the substrate (10) away from the photoelectric conversion region (11), wherein the second switch structure is located between the first junction capacitor and the second junction capacitor.

71. A chip, characterized in that: An image sensor comprising any one of claims 1-56, or an image sensor prepared by the method described in any one of claims 57 to 70.

72. A device, characterized in that An image sensor comprising any one of claims 1-56, or an image sensor prepared by the method described in any one of claims 57 to 70.

Images