Dark current detection structure and dark current detection method of image sensor

Abstract

The application relates to a dark current detection structure and a dark current detection method of an image sensor. The structure comprises a detection unit and a plurality of pixel units arranged in parallel. The pixel units are used for collecting dark current. The detection unit comprises a dark current amplification module and a plurality of control transistors. The sources of the control transistors are connected with the drains of the plurality of pixel units. The drains of the control transistors are electronic storage nodes for storing dark current. The electronic storage nodes are connected with the input ends of the dark current amplification module. In the process of dark current detection, the pixel units transmit the collected dark current to the control transistors. The electronic storage nodes store or output the dark current. The dark current amplification module amplifies the dark current output by the electronic storage nodes. The output ends of the dark current amplification module output the amplified dark current. The application realizes the dark current detection of the image sensor and improves the working dynamic range and stability of the dark current detection structure.

Description

Technical Field

[0001] This application relates to the field of semiconductor testing technology, and in particular to a dark current detection structure and a dark current detection method for an image sensor. Background Technology

[0002] A CMOS image sensor (CIS) is a device that converts optical images into electronic signals. It uses photodiodes to convert light signals into photoelectric charges, collects and processes the photoelectric charges, converts them into voltage or current signals, and finally outputs them in the form of digital signals.

[0003] Dark current (DC, i.e., electrons not generated by photoelectric conversion) collected within the photodiode (PD) of a CIS device has a significant impact on the imaging performance of the CIS device, especially under dark conditions. The presence of dark current can cause white spots in the image output by the CIS device. Since the amount of dark current causing white spots is very small, currently, only chip probing (CP) can be used to measure this portion of non-photoelectric conversion electrons. However, CP testing has a long testing cycle, and using CP testing to detect the presence of dark current seriously affects the development efficiency of CIS devices. Summary of the Invention

[0004] Therefore, it is necessary to provide a dark current detection structure and a dark current detection method for an image sensor to realize dark current detection in the image sensor.

[0005] This application provides a dark current detection structure for detecting the presence of dark current in an image sensor, including:

[0006] Multiple pixel units connected in parallel, the pixel units being used to collect dark current;

[0007] The detection unit includes a dark current amplification module and a plurality of control transistors, wherein the source of the control transistor is connected to the drain of a plurality of the pixel units, the drain of the control transistor is an electron storage node for storing dark current, and the electron storage node is connected to the input terminal of the dark current amplification module.

[0008] During the dark current detection process, the pixel unit transmits the collected dark current to the control transistor, the electron storage node stores or outputs the dark current, the dark current amplification module amplifies the dark current output by the electron storage node, and the output terminal of the dark current amplification module outputs the amplified dark current.

[0009] In one embodiment, the plurality of pixel units are arranged in a two-dimensional array, and the number of control transistors is the same as the number of rows of pixel units, wherein pixel units in the same row are connected to the same control transistor, and pixel units in different rows are connected to different control transistors.

[0010] In one embodiment, the pixel unit includes a photosensitive element and a transmission transistor, the drain of the transmission transistor being a floating diffusion region, and the floating diffusion region being connected to the source of the control transistor.

[0011] In one embodiment, the dark current amplification module includes a first amplifying transistor and a second amplifying transistor, wherein the drain of the first amplifying transistor and the drain of the second amplifying transistor are both connected to a power supply, the source of the first amplifying transistor is connected to the gate of the second amplifying transistor, the gate of the first amplifying transistor is the input terminal of the dark current amplification module, and the source of the second amplifying transistor is the output terminal of the dark current amplification module.

[0012] In one embodiment, the dark current detection structure includes a dark current accumulation state, a first dark current reading state, and a second dark current reading state; wherein,

[0013] When the dark current detection structure is in a dark current accumulation state, both the transmission transistor and the control transistor are in a turned-off state, and the photosensitive element collects and accumulates the dark current.

[0014] When the dark current detection structure is in the first dark current reading state, both the first amplifying transistor and the second amplifying transistor are in the on state, and both the transmission transistor and the control transistor are in the off state, and the output terminal outputs the first output current.

[0015] When the dark current detection structure is in the second dark current reading state, the first amplifying transistor, the second amplifying transistor, the transmission transistor, and the control transistor are all in the open state, the output terminal outputs a second output current, and the difference between the first output current and the second output current is the quantized value of the dark current stored in the photosensitive element.

[0016] In one embodiment, the detection unit further includes a reset transistor, the drain of which is connected to the power supply, and the source of which is connected to the electronic storage node.

[0017] The dark current detection structure also includes a reset state, and when the dark current detection structure is in the reset state, the reset transistor, the transmission transistor and the control transistor are all in the open state to clear the residual electrons in the photosensitive element.

[0018] When the dark current detection structure is in the dark current accumulation state, the reset transistor is in the on state; when the dark current detection structure is in the first dark current reading state and the second dark current reading state, the reset transistor is in the off state.

[0019] In one embodiment, the image sensor is disposed between two adjacent dicing channels within the wafer, the dark current detection structure is disposed within the dicing channel, and the pixel units in the image sensor are arranged in the same manner as the pixel units in the dark current detection structure.

[0020] Alternatively, the detection unit is disposed within the cutting channel, the pixel unit is located in the image sensor, and the dark current detection structure and the image sensor share the pixel unit.

[0021] This application also provides a dark current detection method for an image sensor, including:

[0022] An image sensor and a dark current detection structure as described above are provided;

[0023] The dark current detection structure is used to detect dark current and obtain the quantized value of the dark current collected by the pixel unit in order to detect whether there is dark current in the image sensor.

[0024] In one embodiment, the process of using the dark current detection structure to perform dark current detection on the image sensor includes:

[0025] The dark current detection structure is adjusted to the reset state to remove residual electrons in the pixel unit;

[0026] The dark current detection structure is adjusted to a dark current accumulation state and maintained for a preset accumulation time so that the photosensitive element in the pixel unit accumulates dark current.

[0027] The dark current detection structure is adjusted to the first dark current reading state, and the first output current output by the dark current detection structure is obtained;

[0028] The dark current detection structure is adjusted to the second dark current reading state, and the second output current output by the dark current detection structure is obtained after a preset transfer time.

[0029] The difference between the first output current and the second output current is the quantized value corresponding to the dark current collected by the pixel unit.

[0030] In one embodiment, when the dark current detection structure includes at least two control transistors, the test range of the dark current detection structure is controlled by adjusting the number of control transistors in the on state.

[0031] An unexpected effect of this application is that by setting several control transistors containing electronic storage nodes connected to the pixel units, and using the electronic storage nodes to store the dark current collected by multiple pixel units, the problem that the dark current collected by a single pixel unit is too low to reach the amplification sensitivity of the dark current amplification module is effectively avoided, while the influence of the parasitic capacitance of the metal wire is reduced; by amplifying the dark current in multiple stages through the dark current amplification module, the working dynamic range and stability of the dark current detection structure are effectively improved. Attached Figure Description

[0032] To more clearly illustrate the technical solutions in the embodiments of this application or the conventional technology, the drawings used in the description of the embodiments or the conventional technology will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0033] Figure 1 This is a schematic diagram of the 4T-APS pixel structure in a related technology.

[0034] Figure 2 This is a schematic diagram of the working timing of the 4T-APS pixel structure in a related technology.

[0035] Figure 3 This is a schematic diagram of the circuit structure of a dark current detection structure provided in one embodiment of this application.

[0036] Figure 4 This is a schematic cross-sectional view of the dark current detection structure provided in one embodiment of the present application along the direction perpendicular to the wafer surface.

[0037] Figure 5 This is a schematic diagram of the operating timing of a dark current detection structure provided in one embodiment of this application.

[0038] Figure 6 This is a flowchart of a dark current detection method for an image sensor provided in one embodiment of this application.

[0039] The reference numerals in the accompanying drawings include: 100-dark current detection structure; 110-detection unit; 111-dark current amplification module; 112-control transistor; 120-pixel unit. Detailed Implementation

[0040] To facilitate understanding of this application, a more complete description will be provided below with reference to the accompanying drawings, which illustrate embodiments of the present application. However, the present application can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided so that the disclosure of this application will be thorough and complete.

[0041] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the application.

[0042] It should be understood that when an element or layer is referred to as "on," "adjacent to," "connected to," or "coupled to" other elements or layers, it may be directly on, adjacent to, connected to, or coupled to other elements or layers, or there may be intervening elements or layers. Conversely, when an element is referred to as "directly on," "directly adjacent to," "directly connected to," or "directly coupled to" other elements or layers, there are no intervening elements or layers. It should be understood that although the terms first, second, third, etc., may be used to describe various elements, parts, regions, layers, doping types, and / or portions, these elements, parts, regions, layers, doping types, and / or portions should not be limited by these terms. These terms are only used to distinguish one element, part, region, layer, doping type, or portion from another element, part, region, layer, doping type, or portion. Therefore, without departing from the teachings of this application, the first element, component, region, layer, doping type, or portion discussed below may be represented as a second element, component, region, layer, or portion; for example, the first doping type may be referred to as the second doping type, and similarly, the second doping type may be referred to as the first doping type; the first doping type and the second doping type are different doping types, for example, the first doping type may be P-type and the second doping type may be N-type, or the first doping type may be N-type and the second doping type may be P-type.

[0043] Spatial relation terms such as “below,” “under,” “below,” “under,” “above,” “above,” etc., are used herein to describe the relationship between one element or feature shown in the figure and other elements or features. It should be understood that, in addition to the orientation shown in the figure, spatial relation terms also include different orientations of the device in use and operation. For example, if the device in the figure is flipped, the element or feature described as “below,” “under,” or “below” will be oriented “above” the other element or feature. Therefore, the exemplary terms “below” and “under” can include both above and below orientations. Furthermore, the device may also include other orientations (e.g., rotated 90 degrees or other orientations), and the spatial descriptive terms used herein will be interpreted accordingly.

[0044] When used herein, the singular forms of “a,” “an,” and “ / the” may also include the plural forms unless the context clearly indicates otherwise. It should also be understood that the terms “comprising / including” or “having,” etc., specify the presence of the stated features, wholes, steps, operations, components, parts, or combinations thereof, but do not preclude the possibility of the presence or addition of one or more other features, wholes, steps, operations, components, parts, or combinations thereof. Meanwhile, in this specification, the term “and / or” includes any and all combinations of the associated listed items.

[0045] Figure 1 This is a schematic diagram of a four-tube active pixel structure (i.e., a 4T-APS pixel structure) in a related technology. (See also...) Figure 1 Typical image sensors (such as CIS devices) are mainly based on the 4T-APS (Active Pixel Sensor) structure, which consists of a photodiode (PD), a transfer gate (TG), a floating diffusion region (FD), a reset transistor, a source follower, and a select transistor.

[0046] See Figure 2 The image sensor operating sequence described above includes: before light sensing, the transmission control gate is opened to reset the photosensitive element, at which time the output voltage is Vout1. Subsequently, the transmission control gate is closed to perform the light sensing operation. After light sensing, the transmission control gate is opened, and photogenerated electrons are transmitted to the floating diffusion region, causing the potential of the floating diffusion region to decrease. After being amplified by the signal processing MOS transistor, the output voltage is Vout2. The optical image signal collected by the image sensor is the difference between Vout1 and Vout2.

[0047] During normal exposure, the photosensitive element generates almost no photoelectrons in a dark environment. Therefore, the output color of the corresponding pixel should be black. If there is a problem with high dark current (DC), it means that the photosensitive element collects electrons that are not generated by photoelectric conversion during the exposure period. These electrons are amplified and output as optical signals during normal operation, causing pixels that should be black in the image to become white, thus causing the image sensor to present incorrect optical image information.

[0048] However, the dark current of a single pixel is on the order of magnitude small, making it difficult to measure using conventional testing structures. Therefore, the current standard method for dark current testing relies on chip probing (CP testing). However, CP testing has a long testing cycle, and using this method to detect dark current would severely impact the development efficiency of image sensors.

[0049] Therefore, it is necessary to provide a dark current detection structure and a dark current detection method for an image sensor to realize dark current detection in the image sensor.

[0050] Figure 3 This is a schematic diagram of the circuit structure of a dark current detection structure provided in one embodiment of this application. (See also...) Figure 3 One embodiment of this application provides a dark current detection structure 100 for detecting the presence of dark current in an image sensor. The dark current detection structure 100 includes a detection unit 110 and a plurality of pixel units 120 arranged in parallel. The pixel units 120 are used to collect dark current. The detection unit 110 includes a dark current amplification module 111 and a plurality of control transistors 112. The source of the control transistors 112 is connected to the drain of the plurality of pixel units 120. The drain of the control transistors 112 is an electronic storage node (Floating Diffusion Store, FDS) for storing dark current. The electronic storage node FDS is connected to the input terminal of the dark current amplification module 111.

[0051] During the dark current detection process, the pixel unit 120 transmits the collected dark current to the control transistor 112, the electronic storage node FDS stores or outputs the dark current, the dark current amplification module 111 amplifies the dark current output by the electronic storage node FDS, and the output terminal of the dark current amplification module 111 outputs the amplified dark current.

[0052] The dark current detection structure described above effectively avoids the problem that the dark current collected by a single pixel unit is too low to reach the amplification sensitivity of the dark current amplification module by setting several control transistors containing electron storage nodes connected to the pixel units and using the electron storage nodes to store the dark current collected by multiple pixel units. At the same time, it reduces the influence of parasitic capacitance of metal lines. By amplifying the dark current in multiple stages through the dark current amplification module, the working dynamic range and stability of the dark current detection structure are effectively improved.

[0053] Continue reading Figure 3 In one embodiment, a plurality of pixel units 120 are arranged in a two-dimensional array, and the number of control transistors 112 is the same as the number of rows of pixel units. Pixel units 120 in the same row are connected to the same control transistor 112, while pixel units 120 in different rows are connected to different control transistors 112.

[0054] It should be noted that connecting multiple pixel units in parallel can solve the problem of insufficient dark current collected by a single pixel unit. By increasing the number of pixel units connected in parallel, the magnitude of the dark current is increased, thereby ensuring that the total dark current is sufficient to reach the amplifier sensitivity of the dark current amplification module.

[0055] See Figure 3 and Figure 4 In one embodiment, pixel unit 120 includes a photo-diode (PD) and a transfer gate (TG), the drain of the transfer gate (TG) being a floating diffusion region (FD), and the floating diffusion region (FD) being connected to the source of the control transistor 112.

[0056] Continue reading Figure 4 In one embodiment, the control transistor 112 includes an N+ doped region, a control gate (CG), and an electron storage node FDS, wherein the electron storage node FDS is used to store dark current from the pixel unit 120. In other embodiments of this application, the number of control transistors can be adjusted according to actual needs, and during testing using the dark current detection structure, the test range and sensitivity of the dark current detection structure can be dynamically adjusted by adjusting the number of control gates CG that are turned on (i.e., adjusting the test range and sensitivity of the dark current detection structure by adjusting the number of control transistors in the on state).

[0057] It should be noted that by setting at least two control transistors, at least two electron transfer paths are established to control different pixel arrays. This effectively avoids the problem of the entire dark current detection structure failing due to process issues when using only one control transistor (i.e., a single transfer path), thus improving the stability and compatibility of the dark current detection structure. Furthermore, by introducing the electron storage node FDS, the impact of metal parasitic capacitance on the operating dynamic range of the dark current amplification module can be reduced or eliminated, further enhancing the stability of the dark current detection structure.

[0058] See Figure 3 and Figure 4 In one embodiment, the dark current amplification module 111 includes a first amplifying transistor (Amplifying Gain, AG) and a second amplifying transistor (Super Gain, SG), wherein the drain of the first amplifying transistor AG and the drain of the second amplifying transistor SG are both connected to a power supply Vdd, the source of the first amplifying transistor AG is connected to the gate of the second amplifying transistor SG, the gate of the first amplifying transistor AG is the input terminal of the dark current amplification module 111, and the source of the second amplifying transistor SG is the output terminal of the dark current amplification module 111.

[0059] It should be noted that the dark current amplification module can be used to amplify the dark current output by the control transistor in multiple stages, which effectively improves the working dynamic range of the dark current detection structure, thereby realizing the quantization of dark current.

[0060] Continue reading Figure 3 In one embodiment, the detection unit 110 further includes a reset transistor (ControlReset, CR). The drain of the reset transistor CR is connected to the power supply Vdd, and the source of the reset transistor CR is connected to the drain of the control transistor 112. It should be noted that by turning on the reset transistor CR, residual electrons within the photosensitive element PD in the pixel unit can be cleared, thereby reducing or even eliminating the influence of residual electrons on the dark current detection results and improving the accuracy of the dark current detection results.

[0061] See Figure 5 In one embodiment, the dark current detection structure includes a reset state S1, a dark current accumulation state S2, a first dark current reading state S3, and a second dark current reading state S4.

[0062] When the dark current detection structure is in reset state S1, the reset transistor CR, the transfer transistor TG, and the control transistor (i.e., Figure 5 The CG in the image sensor is turned on to clear any residual electrons from the image sensor.

[0063] When the dark current detection structure is in the dark current accumulation state S2, the reset transistor CR is in the on state, keeping the electron storage node FDS at a high potential, thereby continuously clearing the electrons in the electron storage node FDS to reduce or even avoid interference from other factors during the dark current accumulation state S2 stage; at the same time, the transfer transistor TG and the control transistor (i.e. Figure 5 The CG in the image is in the off state, and the photosensitive element collects and accumulates dark current.

[0064] When the dark current detection structure is in the first dark current reading state S3, both the first amplifying transistor AG and the second amplifying transistor SG are in the on state, and the transmission transistor TG and the control transistor (i.e. Figure 5 When the CG in the dark current amplifier module is in the off state, the output terminal of the dark current amplifier module outputs the first output current.

[0065] When the dark current detection structure is in the second dark current readout state S4, the first amplifying transistor AG, the second amplifying transistor SG, the transfer transistor TG, and the control transistor (i.e. Figure 5 When both the first and second output currents are turned on, the output terminal of the dark current amplification module outputs the second output current, and the difference between the first and second output currents is the quantized value of the dark current (DC) stored in the photosensitive element.

[0066] In one embodiment, the image sensor is disposed between two adjacent dicing channels within the wafer, and the dark current detection structure is disposed within the dicing channel. The pixel units in the image sensor are arranged in the same manner as those in the dark current detection structure to ensure that the dark current present in the pixel units of the image sensor is the same as the dark current collected in the pixel units of the dark current detection structure. This ensures that the presence of dark current in the image sensor can be detected by the dark current detection structure. Optionally, the pixel units in the image sensor and the pixel units in the dark current detection structure are manufactured simultaneously in the same process step.

[0067] In one embodiment, the detection unit of the dark current detection structure is disposed within the dicing channel of the wafer, and the pixel unit of the dark current detection structure is located in the image sensor; that is, the dark current detection structure and the image sensor share the pixel unit. In other embodiments of this application, the specific arrangement of the dark current detection structure within the wafer can also be adjusted according to actual needs, and this application does not impose any limitations on this.

[0068] Figure 6 A flowchart of a dark current detection method for an image sensor provided in one embodiment of this application. See also... Figure 6One embodiment of this application provides a dark current detection method for an image sensor, which includes the following steps S01 to S02.

[0069] Step S01: Provide an image sensor and the dark current detection structure as described above.

[0070] Step S02: Use the dark current detection structure to perform dark current detection, obtain the quantized value of the dark current collected by the pixel unit, and detect whether there is dark current in the image sensor.

[0071] It should be noted that since the pixel units in the dark current detection structure can collect the dark current in the image sensor, the quantized value of the dark current in the image sensor can be obtained through the dark current detection structure, thereby realizing the dark current detection of the image sensor.

[0072] The dark current detection method for image sensors described above collects dark current in the image sensor through pixel units in the dark current detection structure, and obtains the quantized value of the dark current collected by the pixel units through the detection structure in the dark current detection structure, thereby realizing the dark current detection of the image sensor and improving the testing efficiency and accuracy.

[0073] In one embodiment, the process of using a dark current detection structure to detect dark current in an image sensor includes: first, adjusting the dark current detection structure to a reset state to clear residual electrons in the pixel units of the dark current detection structure, thereby reducing or even avoiding the influence of residual electrons on the accuracy of the dark current detection structure; next, adjusting the dark current detection structure to a dark current accumulation state and maintaining it for a preset accumulation time to allow the photosensitive elements in the pixel units to accumulate dark current; subsequently, adjusting the dark current detection structure to a first dark current readout state and acquiring the first output current output by the dark current detection structure; next, adjusting the dark current detection structure to a second dark current readout state and acquiring the second output current output by the dark current detection structure after a preset transfer time; wherein, the difference between the first output current and the second output current is the quantized value corresponding to the dark current collected by the pixel units.

[0074] Since the specific structure and working principle of the dark current detection structure have been described in detail above, they will not be repeated here. It should be noted that, because the pixel unit collects the dark current in the image sensor, the dark current detection of the image sensor can be achieved by obtaining the quantized value corresponding to the dark current collected by the pixel unit.

[0075] In one embodiment, when the dark current detection structure includes at least two control transistors, the test range of the dark current detection structure can be controlled by adjusting the number of control transistors in the on state. Furthermore, while adjusting the number of control transistors, the amplification factor of the amplification transistors (including the first and second amplification transistors) in the dark current amplification module must also be considered. By balancing the amplification factor of the amplification transistors and the number of control transistors, the influence of metal parasitic capacitance can be eliminated, thereby ensuring the accuracy of the dark current detection structure.

[0076] An unexpected effect of this application is that by setting up several control transistors connected to the pixel units and using an electronic storage node to store the dark current collected by multiple pixel units, the problem that the dark current collected by a single pixel unit is too low to reach the amplification sensitivity of the dark current amplification module is effectively avoided, while the influence of the parasitic capacitance of the metal wire is reduced; by amplifying the dark current through the dark current amplification module in multiple stages, the working dynamic range and stability of the dark current detection structure are effectively improved.

[0077] In the description of this specification, the references to terms such as "some embodiments," "other embodiments," "ideal embodiments," etc., refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example that are included in at least one embodiment or example of this application. In this specification, the illustrative descriptions of the above terms do not necessarily refer to the same embodiments or examples.

[0078] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features of the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0079] The embodiments described above are merely illustrative of several implementation methods of this application, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of the application. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these modifications and improvements all fall within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the appended claims.

Claims

1. A dark current detection structure for detecting the presence of dark current in an image sensor, characterized in that, include: Multiple pixel units connected in parallel, the pixel units being used to collect dark current; The detection unit includes a dark current amplification module and a plurality of control transistors, wherein the source of the control transistor is connected to the drain of a plurality of the pixel units, the drain of the control transistor is an electron storage node for storing dark current, and the electron storage node is connected to the input terminal of the dark current amplification module. During the dark current detection process, the pixel unit transmits the collected dark current to the control transistor, the electron storage node stores or outputs the dark current, the dark current amplification module amplifies the dark current output by the electron storage node, and the output terminal of the dark current amplification module outputs the amplified dark current.

2. The dark current detection structure according to claim 1, characterized in that, The pixel units are arranged in a two-dimensional array, and the number of control transistors is the same as the number of rows of the pixel units. Pixel units in the same row are connected to the same control transistor, while pixel units in different rows are connected to different control transistors.

3. The dark current detection structure according to claim 1, characterized in that, The pixel unit includes a photosensitive element and a transmission transistor, the drain of the transmission transistor is a floating diffusion region, and the floating diffusion region is connected to the source of the control transistor.

4. The dark current detection structure according to claim 3, characterized in that, The dark current amplification module includes a first amplifying transistor and a second amplifying transistor, wherein the drain of the first amplifying transistor and the drain of the second amplifying transistor are both connected to a power supply, the source of the first amplifying transistor is connected to the gate of the second amplifying transistor, the gate of the first amplifying transistor is the input terminal of the dark current amplification module, and the source of the second amplifying transistor is the output terminal of the dark current amplification module.

5. The dark current detection structure according to claim 4, characterized in that, The dark current detection structure includes a dark current accumulation state, a first dark current reading state, and a second dark current reading state; wherein... When the dark current detection structure is in a dark current accumulation state, both the transmission transistor and the control transistor are in a turned-off state, and the photosensitive element collects and accumulates the dark current. When the dark current detection structure is in the first dark current reading state, both the first amplifying transistor and the second amplifying transistor are in the on state, and both the transmission transistor and the control transistor are in the off state, and the output terminal outputs the first output current. When the dark current detection structure is in the second dark current reading state, the first amplifying transistor, the second amplifying transistor, the transmission transistor, and the control transistor are all in the open state, the output terminal outputs a second output current, and the difference between the first output current and the second output current is the quantized value of the dark current stored in the photosensitive element.

6. The dark current detection structure according to claim 5, characterized in that, The detection unit further includes a reset transistor, the drain of which is connected to the power supply, and the source of which is connected to the electronic storage node. The dark current detection structure also includes a reset state, and when the dark current detection structure is in the reset state, the reset transistor, the transmission transistor and the control transistor are all in the open state to clear the residual electrons in the photosensitive element. When the dark current detection structure is in the dark current accumulation state, the reset transistor is in the on state; when the dark current detection structure is in the first dark current reading state and the second dark current reading state, the reset transistor is in the off state.

7. The dark current detection structure according to claim 1, characterized in that, The image sensor is disposed between two adjacent dicing channels within the wafer, the dark current detection structure is disposed within the dicing channel, and the pixel units in the image sensor are disposed in the same manner as the pixel units in the dark current detection structure. Alternatively, the detection unit is disposed within the cutting channel, the pixel unit is located in the image sensor, and the dark current detection structure and the image sensor share the pixel unit.

8. A method for detecting dark current in an image sensor, characterized in that, include: An image sensor and a dark current detection structure as described in any one of claims 1 to 7 are provided; The dark current detection structure is used to detect dark current and obtain the quantized value of the dark current collected by the pixel unit in order to detect whether there is dark current in the image sensor.

9. The dark current detection method for an image sensor according to claim 8, characterized in that, The process of performing dark current detection on the image sensor using the dark current detection structure includes: The dark current detection structure is adjusted to the reset state to remove residual electrons in the pixel unit; The dark current detection structure is adjusted to a dark current accumulation state and maintained for a preset accumulation time so that the photosensitive element in the pixel unit accumulates dark current. The dark current detection structure is adjusted to the first dark current reading state, and the first output current output by the dark current detection structure is obtained; The dark current detection structure is adjusted to the second dark current reading state, and the second output current output by the dark current detection structure is obtained after a preset transfer time. The difference between the first output current and the second output current is the quantized value corresponding to the dark current collected by the pixel unit.

10. The dark current detection method for an image sensor according to claim 8, characterized in that, When the dark current detection structure includes at least two control transistors, the test range of the dark current detection structure can be controlled by adjusting the number of control transistors in the on state.

Images