Sensor pixel unit, preparation method thereof and electronic equipment

Abstract

The embodiment of the invention discloses a sensor pixel unit and a preparation method thereof, electronic equipment, a photodiode, a reset transistor, a source following transistor and a pixel selection transistor. In the circuit layout, the distance between the active region of the photodiode and the gate end of the source following transistor is smaller than a preset distance, and the photodiode and the source following transistor are connected through a connecting device made of a preset material. The active region of the photodiode is also connected with the source end of the reset transistor, the reset transistor receives a reset signal through the gate end, the active region is connected with a power supply signal through the reset transistor, photoelectric charges in the active region are emptied, and the reset operation of the photodiode is completed; the source electrode end of the source following transistor is connected with the source electrode end of the pixel selection transistor, and the drain electrode end of the source following transistor is connected with a power supply signal; the grid end of the pixel selection transistor receives an external output signal, and the drain end of the pixel selection transistor serves as the output end of the sensor pixel unit.

Description

Technical Field

[0001] The present disclosure relates to the field of sensor technology, and in particular to a sensor pixel unit and a preparation method thereof, and an electronic device. Background Art

[0002] Image sensors have been widely used in digital cameras, mobile phones, medical treatment, automobiles, drones, machine recognition and other fields. In particular, the rapid development of complementary metal oxide semiconductor (CMOS) image sensor technology has led to higher requirements for the output image quality of image sensors. CMOS image sensors can be divided into two categories based on the signal acquisition method: one method is to set the exposure time of the pixel and then measure the change in voltage signal; the second method is to set the voltage change of the pixel and then measure the exposure time. Summary of the invention

[0003] In one aspect of an embodiment of the present disclosure, a sensor pixel unit is provided, comprising: a photodiode, a reset transistor, a source follower transistor, and a pixel selection transistor;

[0004] In the circuit layout, the distance between the active region of the photodiode and the gate terminal of the source follower transistor is less than a preset distance, and they are connected via a connecting device of a preset material;

[0005] The photodiode is used for photoelectric conversion to obtain photoelectric charges, and accumulates the photoelectric charges in the active region. In response to reaching a charge output condition, the photoelectric charges in the active region are input to the gate terminal of the source follower transistor through a path formed by the connecting device.

[0006] The active area of ​​the photodiode is also connected to the source terminal of the reset transistor. In response to the reset transistor receiving a reset signal through the gate terminal, the active area is connected to the power supply signal through the reset transistor to clear the photoelectric charge in the active area, thereby completing the reset operation of the photodiode.

[0007] The source terminal of the source follower transistor is connected to the source terminal of the pixel selection transistor, and the drain terminal of the source follower transistor is connected to the power signal;

[0008] The gate terminal of the pixel selection transistor receives an external output signal, and the drain terminal of the pixel selection transistor serves as an output terminal of the sensor pixel unit.

[0009] Optionally, the preset material is a metal conductor;

[0010] The connecting device, the active area of ​​the photodiode and the gate end of the source follower transistor are not in the same plane, and the connecting device connects the active area of ​​the photodiode and the gate end of the source follower transistor in a bridge shape.

[0011] Optionally, the preset material is polysilicon;

[0012] The connecting device and the gate terminal of the source follower transistor are in the same plane, and the connecting device is connected to the active area of ​​the photodiode via a columnar connecting terminal connecting the two planes.

[0013] Optionally, the photodiode, reset transistor, source follower transistor and pixel selection transistor are fabricated on a semiconductor silicon substrate, and a portion of the active region of the photodiode that is not connected to the connection device and the source terminal of the reset transistor is covered by a gate oxide layer.

[0014] Optionally, shallow trench isolation regions are respectively provided in the semiconductor silicon substrate covered by the gate oxide layer below both sides of the gate terminal of the source follower transistor.

[0015] Another aspect of the present disclosure provides a local preparation method of a sensor pixel unit, comprising:

[0016] Preparing a photodiode, a shallow trench isolation region and a gate oxide layer covering the photodiode on a semiconductor silicon substrate;

[0017] Performing a hole-opening operation on the gate oxide layer covering the active area of ​​the photodiode to obtain a contact hole; the distance between the contact hole and the shallow trench isolation area is less than a preset distance;

[0018] Depositing a polysilicon material on the gate oxide layer, and filling the contact hole with the polysilicon material;

[0019] A gate terminal of a source follower transistor in a sensor pixel unit and a connection device connecting an active area of ​​the photodiode and the gate terminal of the source follower transistor are generated based on the polysilicon material.

[0020] Optionally, the generating of the gate terminal of the source follower transistor in the sensor pixel unit based on the polysilicon material, and the connecting device connecting the active area of ​​the photodiode and the gate terminal of the source follower transistor, include:

[0021] Processing the polysilicon material by photoresist development so that the polysilicon material is processed into a preset shape;

[0022] The gate terminal of the source follower transistor and the connecting device are integrated based on the polysilicon material of a preset shape.

[0023] Optionally, the processing of the polysilicon material by developing a photoresist so that the polysilicon material is processed into a preset shape includes:

[0024] Spin coating a photoresist over the polysilicon material;

[0025] Determining the polysilicon material of a preset shape by developing a photoresist;

[0026] Excess polysilicon material is removed to obtain the polysilicon material of a preset shape.

[0027] Optionally, removing excess polysilicon material to obtain the polysilicon material of a preset shape includes:

[0028] The excess polysilicon material is removed by chemical ion etching.

[0029] Another aspect of the embodiments of the present disclosure provides an electronic device, including:

[0030] An electronic device, characterized in that it comprises: a processor, and a memory communicatively connected to the processor, and further comprises the sensor pixel unit described in any one of the above embodiments;

[0031] The memory stores computer-executable instructions;

[0032] The processor executes computer-implemented instructions stored in the memory to control the sensor pixel unit.

[0033] Optionally, the electronic device is included in any one of the following: image data acquisition equipment, audio / video player, navigation equipment, entertainment equipment, communication equipment, roadside traffic facilities, equipment in motor vehicles, industrial inspection equipment, flight equipment, medical equipment, security equipment.

[0034] The embodiment of the present disclosure provides a sensor pixel unit and a preparation method thereof, an electronic device, a photodiode, a reset transistor, a source follower transistor and a pixel selection transistor; in the circuit layout, the distance between the active area of ​​the photodiode and the gate terminal of the source follower transistor is less than a preset distance, and they are connected through a connection device of a preset material; the photodiode is used to obtain photoelectric charges through photoelectric conversion, and the photoelectric charges are accumulated in the active area. In response to the fulfillment of the charge output condition, the photoelectric charges in the active area are input to the gate terminal of the source follower transistor through the path formed by the connection device; the active area of ​​the photodiode is also connected to the source terminal of the reset transistor. In response to the reset transistor receiving a reset signal through the gate terminal, the active area is connected to the power supply signal through the reset transistor, the photoelectric charges in the active area are cleared, and the reset operation of the photodiode is completed; the source terminal of the source follower transistor is connected to the source terminal of the pixel selection transistor, and the drain terminal of the source follower transistor is connected to the power supply signal; the gate terminal of the pixel selection transistor receives an external output signal, and the drain terminal of the pixel selection transistor serves as the output terminal of the sensor pixel unit. The disclosed embodiments reduce the parasitic capacitance by shortening the distance between the active region of the photodiode and the gate terminal of the source follower transistor, thereby increasing the photoelectric conversion gain of the photocharges collected by the photodiode, thereby improving the photosensitivity of the image sensor pixels to the light signal, and optimizing the image quality captured by the pulse sequence image sensor.

[0035] The technical solution of the present disclosure is further described in detail below through the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] The accompanying drawings, which constitute a part of the specification, illustrate embodiments of the present disclosure and, together with the description, serve to explain the principles of the present disclosure.

[0037] The present disclosure may be more clearly understood from the following detailed description with reference to the accompanying drawings, in which:

[0038] Figure 1 is a circuit diagram of an embodiment of a sensor pixel unit disclosed herein;

[0039] Figure 2 The pixel unit of the sensor disclosed herein corresponds to Figure 1 A schematic diagram of a layout structure of an embodiment provided;

[0040] Figure 3 The pixel unit of the sensor disclosed herein corresponds to Figure 2 A partial cross-sectional view of an embodiment is provided;

[0041] Figure 4 The pixel unit of the sensor disclosed herein corresponds to Figure 1Another schematic diagram of the layout structure of the embodiment provided;

[0042] Figure 5 The pixel unit of the sensor disclosed herein corresponds to Figure 4 A partial cross-sectional view of an embodiment is provided;

[0043] Figure 6 A flow chart of a local preparation method of a sensor pixel unit provided in an embodiment of the present disclosure;

[0044] Figure 7a A schematic diagram of substrate preparation in a local preparation method of a sensor pixel unit provided in an embodiment of the present disclosure;

[0045] Figure 7b A schematic diagram of contact hole preparation in a local preparation method of a sensor pixel unit provided in an embodiment of the present disclosure;

[0046] Figure 7c A schematic diagram of depositing polysilicon in a local preparation method of a sensor pixel unit provided in an embodiment of the present disclosure;

[0047] Figure 7d A schematic diagram of spin coating photoresist in a local preparation method of a sensor pixel unit provided in an embodiment of the present disclosure;

[0048] Figure 7e A schematic diagram of photoresist development in a local preparation method of a sensor pixel unit provided in an embodiment of the present disclosure;

[0049] Figure 7f A schematic diagram of polysilicon etching in a local preparation method of a sensor pixel unit provided in an embodiment of the present disclosure;

[0050] Figure 8 A schematic diagram showing the comparison of photoelectric conversion gains of three pixel units with different structures is shown;

[0051] Fig. 9 The figure is a schematic diagram of the structure of an application embodiment of the electronic device disclosed in the present invention. DETAILED DESCRIPTION

[0052] Various exemplary embodiments of the present disclosure will now be described in detail with reference to the accompanying drawings. It should be noted that the relative arrangement of components and steps, numerical expressions and numerical values ​​set forth in these embodiments do not limit the scope of the present disclosure unless otherwise specifically stated.

[0053] Those skilled in the art can understand that the terms "first" and "second" in the embodiments of the present disclosure are only used to distinguish different steps, devices or modules, etc., and neither represent any specific technical meaning nor indicate the necessary logical order between them.

[0054] It should also be understood that in the embodiments of the present disclosure, “plurality” may refer to two or more than two, and “at least one” may refer to one, two, or more than two.

[0055] It should also be understood that any component, data or structure mentioned in the embodiments of the present disclosure can generally be understood as one or more, unless explicitly limited or otherwise indicated in the context.

[0056] In addition, the term "and / or" in the present disclosure is only a description of the association relationship of associated objects, indicating that three relationships may exist. For example, A and / or B can represent: A exists alone, A and B exist at the same time, and B exists alone. In addition, the character " / " in the present disclosure generally indicates that the associated objects before and after are in an "or" relationship.

[0057] It should also be understood that the description of the various embodiments in the present disclosure focuses on the differences between the various embodiments, and the same or similar aspects thereof can be referenced to each other, and for the sake of brevity, they will not be described one by one.

[0058] At the same time, it should be understood that for the convenience of description, the sizes of the various parts shown in the drawings are not drawn according to the actual proportional relationship.

[0059] The following description of at least one exemplary embodiment is merely illustrative in nature and is in no way intended to limit the present disclosure, its application, or uses.

[0060] Technologies, methods, and equipment known to ordinary technicians in the relevant art may not be discussed in detail, but where appropriate, the technologies, methods, and equipment should be considered as part of the specification.

[0061] It should be noted that like reference numerals and letters refer to similar items in the following figures, and therefore, once an item is defined in one figure, it need not be further discussed in subsequent figures.

[0062] The embodiments of the present disclosure can be applied to electronic devices such as terminal devices, computer systems, servers, etc., which can operate with many other general or special computing system environments or configurations. Examples of well-known terminal devices, computing systems, environments and / or configurations suitable for use with electronic devices such as terminal devices, computer systems, servers, etc. include, but are not limited to: personal computer systems, server computer systems, thin clients, thick clients, handheld or laptop devices, microprocessor-based systems, set-top boxes, programmable consumer electronics, network personal computers, small computer systems, large computer systems, and distributed cloud computing technology environments including any of the above systems, etc.

[0063] Electronic devices such as terminal devices, computer systems, servers, etc. can be described in the general context of computer system executable instructions (such as program modules) executed by computer systems. Generally, program modules can include routines, programs, object programs, components, logic, data structures, etc., which perform specific tasks or implement specific abstract data types. Computer systems / servers can be implemented in a distributed cloud computing environment, where tasks are performed by remote processing devices linked through a communication network. In a distributed cloud computing environment, program modules can be located on local or remote computing system storage media including storage devices.

[0064] In the process of implementing this announcement, the inventor discovered that the pixel unit of the pulse sequence image sensor adopts a three-transistor pixel signal acquisition method, and the photosensitivity of the pixel depends on the capacitance CPD of the photodiode in the pixel unit. Under the condition of a fixed pixel area, the photosensitivity of the pixel unit is inversely proportional to the CPD. In the pixel layout design, a contact hole is usually provided in the active area of ​​the photodiode in the pixel unit on the side close to the reset transistor, and a metal layer is arranged to connect to the gate end of the source follower transistor. The capacitance CPD of the photodiode consists of two parts: the parasitic capacitance CAA of the active area of ​​the photodiode and the parasitic capacitance CM of the metal layer. Under the condition of a fixed pixel area, since it is difficult to optimize and reduce the parasitic capacitance CAA of the active area of ​​the photodiode, based on the technical solution provided in the present disclosure, the parasitic capacitance CM of the metal layer is reduced to improve the photosensitivity of the sensor pixel unit.

[0065] Figure 1 FIG. 1 is a circuit diagram of an embodiment of a sensor pixel unit disclosed in the present invention. Figure 1 As shown, the sensor pixel unit provided by this embodiment includes: a photodiode 101 , a reset transistor 102 , a source follower transistor 103 and a pixel selection transistor 104 .

[0066] The connection relationship between the components in this embodiment is the same as that of the existing 3T pixel unit, wherein one end of the photodiode 101 is grounded, and the other end of the photodiode 101 is connected to the drain end of the reset transistor 102 and the gate end of the source follower transistor 103.

[0067] The source terminal of the reset transistor 102 is connected to the power supply terminal Vdd, and the gate terminal of the reset transistor 102 receives a reset signal and is turned on or off according to the control of the reset signal. When the reset transistor 102 is turned on, the photodiode 101 performs a reset, that is, the photoelectric charge in the active area of ​​the photodiode 101 flows to the power supply terminal Vdd, clearing the active area of ​​the photodiode 101.

[0068] Figure 2 The pixel unit of the sensor disclosed herein corresponds to Figure 1 A schematic diagram of a layout structure of an embodiment is provided. Figure 2 As shown, in the circuit layout, the distance between the active region of the photodiode 101 and the gate terminal of the source follower transistor 103 is less than a preset distance, and they are connected through a connecting device of a preset material.

[0069] This embodiment reduces the distance between the active region and the gate terminal of the source follower transistor 103 to reduce the parasitic capacitance CM and improve the photosensitivity of the sensor pixel unit; therefore, the smaller the preset distance, the better. Figure 2 It can be seen that the gate terminal of the source follower transistor 103 is set as close as possible to the active region directly below.

[0070] The photodiode 101 is used for photoelectric conversion to obtain photoelectric charges and accumulate the photoelectric charges in the active region. In response to the fulfillment of the charge output condition, the photoelectric charges in the active region are input to the gate terminal of the source-following transistor through the path formed by the connecting device.

[0071] In order to more clearly describe the local structural connection structure of the present disclosure, Figure 3 The pixel unit of the sensor disclosed herein corresponds to Figure 2 A partial cross-sectional view of an embodiment is provided. Figure 3 Shows Figure 2 The schematic diagram of the device cross section at position 21 is shown. The shallow trench isolation region 301 is disposed between various devices (eg, a photodiode and a source follower transistor) and may be made of insulating material to isolate adjacent devices. Figure 3 In order to indicate the connection relationship between the active region and the gate terminal of the source follower transistor 103, the active region and the gate terminal of the source follower transistor 103 are additionally marked, wherein the active region 302 is the photoelectric charge collection region of the photodiode 101, the gate terminal of the source follower transistor 103 is marked as 303, and the gate terminal 303 can be made of polysilicon material; Figure 3 , the position of the connecting device 201 is clearly shown, the left side of the connecting device 201 is connected to the gate terminal 303 through a contact hole, and the right side of the connecting device 201 is connected to the active area 302 through a contact hole; in this embodiment, the source follower transistor 103 is arranged at a position close to the photodiode 101, and there is only a small shallow trench isolation area 301 between the two, so that the length of the connecting device 201 is significantly shortened compared with the prior art, thereby reducing the parasitic capacitance. Figure 3 As shown, the pixel unit can be prepared on a semiconductor silicon substrate (P-epi).

[0072] like Figure 2As shown, the active area of ​​the photodiode 101 is also connected to the source terminal of the reset transistor 102. In response to the reset transistor 102 receiving a reset signal through the gate terminal, the active area is connected to the power signal through the reset transistor 102 to clear the photoelectric charge in the active area, thereby completing the reset operation of the photodiode.

[0073] A source terminal of the source follower transistor 103 is connected to a source terminal of the pixel selection transistor 104 , and a drain terminal of the source follower transistor 103 is connected to a power signal.

[0074] The source follower transistor 103 is used to follow the charge change in the photodiode to generate a corresponding target signal (eg, a voltage signal Vpix, etc.), and output it through the pixel selection transistor 104 .

[0075] The gate terminal of the pixel selection transistor 104 receives an external output signal, and the drain terminal of the pixel selection transistor 104 serves as an output terminal of the sensor pixel unit.

[0076] The pixel selection transistor 104 is turned on or off according to the control of the external output signal. In response to the external output signal being at a high level, the pixel selection transistor 104 is turned on to output the target signal generated by the original follower transistor 103 .

[0077] In the circuit layout, you can follow Figure 2 The provided embodiment is laid out in which the reset transistor 102 is located at the lower right corner of the photodiode 101 , the source follower transistor 103 is located at the bottom of the photodiode 101 close to the reset transistor 102 , and the pixel selection transistor 104 is located on the left side of the source follower transistor 103 .

[0078] The disclosed embodiments reduce the parasitic capacitance by shortening the distance between the active region of the photodiode and the gate terminal of the source follower transistor, thereby increasing the photoelectric conversion gain of the photocharges collected by the photodiode, thereby improving the photosensitivity of the image sensor pixels to the light signal, and optimizing the image quality captured by the pulse sequence image sensor.

[0079] In some optional embodiments, the preset material is a metal conductor;

[0080] like Figure 3 As shown, the connecting device 201, the active area 302 of the photodiode and the gate terminal 303 of the source follower transistor are not in the same plane, and the connecting device 301 connects the active area 302 of the photodiode and the gate terminal 303 of the source follower transistor in a bridge shape.

[0081] That is, the connection device 301 not only has a lateral connection part, but also includes a contact hole part connected to the active area 302 and the gate terminal 303 respectively. In this embodiment, during the preparation process, contact holes can be prepared above the active area 302 and the gate terminal 303 respectively, and then the two contact holes are filled by depositing a metal conductor, and a metal connection line is prepared between the two contact holes to realize the preparation of the connection device 301. In this embodiment, the parasitic capacitance CM is reduced by shortening the length of the metal connection device, thereby improving the photosensitivity of the sensor pixel unit.

[0082] Figure 4 The pixel unit of the sensor disclosed herein corresponds to Figure 1 Another schematic diagram of the layout structure of the embodiment provided. Figure 5 The pixel unit of the sensor disclosed herein corresponds to Figure 4 A partial cross-sectional view of an embodiment is provided. Figure 4 The mark 41 in the figure is the tangent position. In this embodiment, the preset material is polysilicon; by using the polysilicon material, the use of metal to prepare the connecting device is avoided, and the parasitic capacitance CM is directly eliminated.

[0083] like Figure 5 As shown, it can be seen from the cross-sectional view that the connecting device 401 and the gate terminal 303 of the source follower transistor are in the same plane, and the connecting device 401 is connected to the active area 302 of the photodiode through a columnar connecting terminal connecting the two planes.

[0084] In this embodiment, Figure 4 The local wiring scheme shown improves and optimizes the connection devices. Figure 4 As shown, the contact hole 402 (which is also a part of the connecting device) in the active area 302 of the photodiode 101 is in contact with the connecting device 401, wherein the material of the contact hole 402 is the same as that of the connecting device 401, both of which are polysilicon materials, and the material of the gate terminal 303 of the source follower transistor is also polysilicon material, therefore, steps can be saved during preparation, and the gate terminal 303 and the connecting device are prepared simultaneously in the same step, thereby reducing the number of preparation steps and improving the preparation efficiency. At the same time, the photosensitivity of the pixel unit is improved due to the absence of parasitic capacitance of the metal layer in the prepared pixel unit. Figure 5 In the figure, the shallow trench isolation region 301 is set between each device (for example, a photodiode and a source follower transistor), and can be made of insulating material to isolate adjacent devices. The active region 302 is the photoelectric charge collection region of the photodiode 101, and the gate terminal of the source follower transistor 103 is marked as 303, and the gate terminal 303 can be made of polysilicon material; Figure 5 , the connection relationship between the connecting device and the active area 302 and the gate terminal 303 is clearly shown. Figure 5As shown, the pixel unit can be prepared on a semiconductor silicon substrate (P-epi).

[0085] The disclosed embodiment shortens the distance between the active region of the photodiode and the gate terminal of the source follower transistor, uses polysilicon to prepare the connecting device, eliminates parasitic capacitance, further improves the photoelectric conversion gain of the photocharge collected by the photodiode, enhances the photosensitivity of the image sensor pixels to the light signal, and optimizes the image quality captured by the pulse sequence image sensor.

[0086] Optionally, the photodiode 101, reset transistor 102, source follower transistor 103 and pixel selection transistor 104 are fabricated on a semiconductor silicon substrate, and the active region of the photodiode 101 that is not connected to the connection device and the source terminal of the reset transistor 102 is covered by a gate oxide layer.

[0087] Optionally, shallow trench isolation regions 301 are respectively provided in the semiconductor silicon substrate covered by the gate oxide layer below both sides of the gate terminal of the source follower transistor 103 .

[0088] like Figure 3 and 5 As shown in FIG. 1 , the gate terminal is isolated from other devices by a shallow trench isolation region 301 .

[0089] Figure 6 Flow chart of a local preparation method of a sensor pixel unit provided in an embodiment of the present disclosure. Figure 6 As shown, the preparation method provided in this embodiment can be used to prepare the above Figure 1 , 4 -5 The sensor pixel unit provided in any embodiment includes:

[0090] Step 602, preparing a photodiode, a shallow trench isolation region and a gate oxide layer covering the photodiode on a semiconductor silicon substrate.

[0091] In this embodiment, the process of preparing the active region of the photodiode, the shallow trench isolation region and the gate oxide layer covering the photodiode on the semiconductor silicon substrate can refer to the common preparation method of the pixel unit in the prior art, which will not be described in detail here. Figure 7a As shown, a part of the preparation of the pixel unit is shown, in which the active region 302 of the photodiode, the shallow trench isolation region 301 and the gate oxide layer are prepared on the semiconductor silicon substrate (P-epi).

[0092] Step 604, performing a hole opening operation on the gate oxide layer covering the active region of the photodiode to obtain a contact hole.

[0093] The distance between the contact hole and the shallow trench isolation region is less than the preset distance. In this embodiment, in order to make the length of the connecting device as short as possible to reduce the parasitic capacitance, this embodiment compresses the distance between the contact hole and the shallow trench isolation region so that the contact hole and the gate end of the source follower transistor are as close as possible. Optionally, Figure 7b As shown, a hole is opened in the gate oxide layer so that the contact hole contacts the active area of ​​the photodiode.

[0094] Step 606 , depositing a polysilicon material on the gate oxide layer, and filling the contact hole with the polysilicon material.

[0095] In this embodiment, corresponding to the above Figure 4 , 5 In the embodiment provided, the gate terminal of the connecting device and the source follower transistor are both made of polysilicon material. Therefore, in this embodiment, the connecting device can be connected to the active area of ​​the photodiode by depositing polysilicon material and filling the contact hole in one step. Figure 7c As shown, by depositing polysilicon material on the gate oxide layer, the polysilicon material will naturally fill the contact hole, thereby achieving connection between the polysilicon material and the active area of ​​the photodiode.

[0096] Step 608 : Generate a gate terminal of a source follower transistor in the sensor pixel unit based on polysilicon material, and a connecting device connecting the active area of ​​the photodiode and the gate terminal of the source follower transistor.

[0097] In this embodiment, the gate terminal of the source follower transistor and the connecting device are directly prepared based on the polysilicon material deposited in the above steps, which improves the preparation efficiency of the pixel unit and avoids the need for multiple deposition and removal of multiple different materials. In addition, since the gate terminal of the source follower transistor is made of the same material as the connecting device, the connection state is more stable and there is no parasitic capacitance, which improves the photosensitivity of the sensor pixel unit.

[0098] In some optional embodiments, step 608 may include:

[0099] The polysilicon material is processed by photoresist development so that the polysilicon material is processed into a preset shape.

[0100] This embodiment improves the preparation efficiency of polysilicon materials by developing photoresist.

[0101] The gate terminal and connecting devices of the integrated source follower transistor are generated based on the polysilicon material with a preset shape.

[0102] In this embodiment, the gate terminal and the connecting device of the source follower transistor are prepared based on the same material (polysilicon material), thereby improving the preparation efficiency of the pixel unit.

[0103] Optionally, the polysilicon material is processed into a preset shape by developing a photoresist, including:

[0104] like Figure 7d As shown, photoresist is spin-coated over the polysilicon material.

[0105] like Figure 7e As shown, the polysilicon material of a preset shape is determined by photoresist development.

[0106] The photoresist development method is used to make the shape of the polysilicon material more in line with the requirements and to form it in one step, thus avoiding the problem of inaccurate shape requiring multiple modifications due to other methods.

[0107] like Figure 7f As shown, the excess polysilicon material is removed to obtain a polysilicon material of a preset shape. Optionally, the excess polysilicon material is removed by chemical ion etching.

[0108] Then remove the photoresist on the surface of the polysilicon material to obtain the gate terminal and connecting devices of the prepared source follower transistor, and obtain Figure 5 The pixel unit shown in the figure. This embodiment uses a chemical ion etching method to remove excess polysilicon material to achieve the shape preparation of the polysilicon material without damaging the electronic performance of the electronic device, which has a great advantage over other physical methods.

[0109] In order to more clearly illustrate the advantages of the embodiments of the present disclosure, Figure 8 The following is a schematic diagram showing the comparison of photoelectric conversion gain of three pixel units with different structures. The three pixel units with different structures include: a conventional pixel unit, a pixel unit of the present disclosure Figure 2-3 The pixel unit of the embodiment provided, and the present disclosure Figure 4-5 The pixel unit of the embodiment provided; the pixel unit of the conventional structure corresponds to the photoelectric conversion gain 801, the present disclosure Figure 2-3 The pixel unit of the embodiment provided corresponds to the photoelectric conversion gain 802, and the present disclosure Figure 4-5 The pixel unit of the embodiment provided corresponds to a photoelectric conversion gain of 803. Figure 8 It can be seen that the present disclosure Figure 2-3 The photoelectric conversion gain of the pixel unit of the embodiment provided is higher than the photoelectric conversion gain of the pixel unit of the conventional structure. Figure 4-5 The photoelectric conversion gain of the pixel unit of the embodiment provided is higher than that of the present disclosure. Figure 2-3 The photoelectric conversion gain of the pixel unit of the embodiment is provided.

[0110] In addition, an embodiment of the present disclosure further provides an electronic device, including:

[0111] A processor, and a memory communicatively connected to the processor, further comprising the sensor pixel unit described in any one of the above embodiments;

[0112] The memory stores computer-executable instructions;

[0113] The processor executes computer-implemented instructions stored in the memory to control the sensor pixel unit.

[0114] The electronic device provided by the present disclosure can be included in any of the following: image data acquisition equipment, audio / video player, navigation equipment, entertainment equipment, communication equipment, roadside traffic facilities, equipment in motor vehicles, industrial inspection equipment, flight equipment, medical equipment, security equipment, etc.

[0115] The electronic device provided by the present disclosure can be applied to any of the following: image data acquisition equipment, audio / video players, navigation equipment, entertainment equipment, communication equipment, roadside traffic facilities, equipment in motor vehicles, industrial inspection equipment, flight equipment, medical equipment, security equipment, etc.

[0116] Fig. 9 This is a schematic diagram of the structure of an application embodiment of the electronic device disclosed in the present invention. Fig. 9 The electronic device according to the embodiment of the present disclosure is described. The electronic device may be any one or both of the first device and the second device, or a stand-alone device independent of them, and the stand-alone device may communicate with the first device and the second device to receive the collected input signals from them.

[0117] like Fig. 9 As shown, the electronic device includes one or more processors and memory.

[0118] The processor may be a central processing unit (CPU) or other forms of processing units having data processing capabilities and / or instruction execution capabilities, and may control other components in the electronic device to perform desired functions.

[0119] The memory may store one or more computer program products, and the memory may include various forms of computer-readable storage media, such as volatile memory and / or non-volatile memory. The volatile memory may include, for example, a random access memory (RAM) and / or a cache memory (cache), etc. The non-volatile memory may include, for example, a read-only memory (ROM), a hard disk, a flash memory, etc. One or more computer program products may be stored on the computer-readable storage medium, and the processor may run the computer program product to implement the sensor pixel unit and its preparation method of each embodiment of the present disclosure described above and / or other desired functions.

[0120] In one example, the electronic device may further include: an input device and an output device, and these components are interconnected via a bus system and / or other forms of connection mechanisms (not shown).

[0121] In addition, the input device may also include, for example, a keyboard, a mouse, and the like.

[0122] The output device can output various information to the outside, including determined distance information, direction information, etc. The output device can include, for example, a display, a speaker, a printer, a communication network and a remote output device connected thereto, and the like.

[0123] Of course, to simplify, Fig. 9 Only some of the components related to the present disclosure in the electronic device are shown, and components such as a bus, an input / output interface, etc. are omitted. In addition, according to specific application situations, the electronic device may further include any other appropriate components.

[0124] In addition to the above-mentioned methods and devices, embodiments of the present disclosure may also be a computer program product, which includes computer program instructions, which, when executed by a processor, enable the processor to execute the steps of the sensor pixel unit and the preparation method thereof according to various embodiments of the present disclosure described in the above part of this specification.

[0125] The computer program product may be written in any combination of one or more programming languages ​​to write program code for performing the operations of the disclosed embodiments, including object-oriented programming languages ​​such as Java, C++, etc., and conventional procedural programming languages ​​such as "C" or similar programming languages. The program code may be executed entirely on the user computing device, partially on the user device, as a separate software package, partially on the user computing device and partially on a remote computing device, or entirely on a remote computing device or server.

[0126] In addition, an embodiment of the present disclosure may also be a computer-readable storage medium having computer program instructions stored thereon, and when the computer program instructions are executed by a processor, the processor executes the steps of the sensor pixel unit and the preparation method thereof according to various embodiments of the present disclosure described in the above part of this specification.

[0127] The computer readable storage medium can adopt any combination of one or more readable media. The readable medium can be a readable signal medium or a readable storage medium. The readable storage medium can include, for example, but is not limited to, a system, device or device of electricity, magnetism, light, electromagnetic, infrared, or semiconductor, or any combination of the above. More specific examples (non-exhaustive list) of readable storage media include: an electrical connection with one or more wires, a portable disk, a hard disk, a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or flash memory), an optical fiber, a portable compact disk read-only memory (CD-ROM), an optical storage device, a magnetic storage device, or any suitable combination of the above.

[0128] The basic principles of the present disclosure are described above in conjunction with specific embodiments. However, it should be noted that the advantages, strengths, effects, etc. mentioned in the present disclosure are only examples and not limitations, and it cannot be considered that these advantages, strengths, effects, etc. are required by each embodiment of the present disclosure. In addition, the specific details disclosed above are only for the purpose of illustration and ease of understanding, and are not limitations. The above details do not limit the present disclosure to the necessity of adopting the above specific details to be implemented.

[0129] Each embodiment in this specification is described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the embodiments can be referred to each other. For the system embodiment, since it basically corresponds to the method embodiment, the description is relatively simple, and the relevant parts can be referred to the partial description of the method embodiment.

[0130] The block diagrams of the devices, apparatuses, equipment, and systems involved in this disclosure are only illustrative examples and are not intended to require or imply that they must be connected, arranged, and configured in the manner shown in the block diagrams. As will be appreciated by those skilled in the art, these devices, apparatuses, equipment, and systems can be connected, arranged, and configured in any manner. Words such as "including," "comprising," "having," and the like are open words, referring to "including but not limited to," and can be used interchangeably therewith. The words "or" and "and" used herein refer to the words "and / or," and can be used interchangeably therewith, unless the context clearly indicates otherwise. The word "such as" used herein refers to the phrase "such as but not limited to," and can be used interchangeably therewith.

[0131] The method and apparatus of the present disclosure may be implemented in many ways. For example, the method and apparatus of the present disclosure may be implemented by software, hardware, firmware, or any combination of software, hardware, and firmware. The above order of steps for the method is for illustration only, and the steps of the method of the present disclosure are not limited to the order specifically described above, unless otherwise specifically stated. In addition, in some embodiments, the present disclosure may also be implemented as a program recorded in a recording medium, which includes machine-readable instructions for implementing the method according to the present disclosure. Therefore, the present disclosure also covers a recording medium storing a program for executing the method according to the present disclosure.

[0132] It should also be noted that in the apparatus, device and method of the present disclosure, each component or each step can be decomposed and / or recombined. Such decomposition and / or recombination should be regarded as equivalent solutions of the present disclosure.

[0133] The above description of the disclosed aspects is provided to enable any person skilled in the art to make or use the present disclosure. Various modifications to these aspects will be readily apparent to those skilled in the art, and the general principles defined herein may be applied to other aspects without departing from the scope of the present disclosure. Therefore, the present disclosure is not intended to be limited to the aspects shown herein, but rather to the widest scope consistent with the principles and novel features disclosed herein.

[0134] The above description has been given for the purpose of illustration and description. In addition, this description is not intended to limit the embodiments of the present disclosure to the forms disclosed herein. Although multiple example aspects and embodiments have been discussed above, those skilled in the art will recognize certain variations, modifications, changes, additions and sub-combinations thereof.

Claims

1. A sensor pixel unit, characterized in that: include: a photodiode, a reset transistor, a source follower transistor, and a pixel select transistor; In the circuit layout, the distance between the active region of the photodiode and the gate terminal of the source follower transistor is less than a preset distance, and they are connected via a connecting device of a preset material; The photodiode is used for photoelectric conversion to obtain photoelectric charges, and accumulates the photoelectric charges in the active region. In response to reaching a charge output condition, the photoelectric charges in the active region are input to the gate terminal of the source follower transistor through a path formed by the connecting device. The active area of ​​the photodiode is also connected to the source terminal of the reset transistor. In response to the reset transistor receiving a reset signal through the gate terminal, the active area is connected to the power supply signal through the reset transistor to clear the photoelectric charge in the active area, thereby completing the reset operation of the photodiode. The source terminal of the source follower transistor is connected to the source terminal of the pixel selection transistor, and the drain terminal of the source follower transistor is connected to the power signal; The gate terminal of the pixel selection transistor receives an external output signal, and the drain terminal of the pixel selection transistor serves as an output terminal of the sensor pixel unit.

2. The pixel unit according to claim 1, characterized in that: The preset material is a metal conductor; The connecting device, the active area of ​​the photodiode and the gate end of the source follower transistor are not in the same plane, and the connecting device connects the active area of ​​the photodiode and the gate end of the source follower transistor in a bridge shape.

3. The pixel unit according to claim 1, characterized in that: The preset material is polysilicon; The connecting device and the gate terminal of the source follower transistor are in the same plane, and the connecting device is connected to the active area of ​​the photodiode via a columnar connecting terminal connecting the two planes.

4. The pixel unit according to any one of claims 1 to 3, characterized in that: The photodiode, reset transistor, source follower transistor and pixel selection transistor are prepared on a semiconductor silicon substrate, and the active region of the photodiode that is not connected to the connection device and the source terminal of the reset transistor is covered by a gate oxide layer.

5. The pixel unit according to claim 4, characterized in that: Shallow trench isolation regions are respectively arranged in the semiconductor silicon substrate covered by the gate oxide layer below both sides of the gate end of the source follower transistor.

6. A local preparation method of a sensor pixel unit, characterized in that: include: Preparing a photodiode, a shallow trench isolation region and a gate oxide layer covering the photodiode on a semiconductor silicon substrate; Performing a hole opening operation on the gate oxide layer covering the active area of ​​the photodiode to obtain a contact hole; The distance between the contact hole and the shallow trench isolation region is less than a preset distance; Depositing a polysilicon material on the gate oxide layer, and filling the contact hole with the polysilicon material; A gate terminal of a source follower transistor in a sensor pixel unit and a connection device connecting an active area of ​​the photodiode and the gate terminal of the source follower transistor are generated based on the polysilicon material.

7. The method according to claim 6, characterized in that The gate terminal of the source follower transistor in the sensor pixel unit is generated based on the polysilicon material, and the connecting device connecting the active area of ​​the photodiode and the gate terminal of the source follower transistor includes: Processing the polysilicon material by photoresist development so that the polysilicon material is processed into a preset shape; The gate terminal of the source follower transistor and the connecting device are integrated based on the polysilicon material of a preset shape.

8. The method according to claim 7, characterized in that The step of processing the polysilicon material by developing a photoresist so that the polysilicon material is processed into a preset shape includes: Spin coating a photoresist over the polysilicon material; Determining the polysilicon material of a preset shape by developing a photoresist; Excess polysilicon material is removed to obtain the polysilicon material of a preset shape.

9. The method according to claim 8, characterized in that The step of removing the excess polysilicon material to obtain the polysilicon material of a preset shape includes: The excess polysilicon material is removed by chemical ion etching.

10. An electronic device, characterized in that: include: A processor, and a memory communicatively connected to the processor, further comprising the sensor pixel unit according to any one of claims 1 to 5; The memory stores computer-executable instructions; The processor executes computer-implemented instructions stored in the memory to control the sensor pixel unit.

11. The device according to claim 10, characterized in that The electronic device is included in any of the following: image data acquisition equipment, audio / video player, navigation equipment, entertainment equipment, communication equipment, roadside traffic facilities, equipment in motor vehicles, industrial testing equipment, flight equipment, medical equipment, and security equipment.

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