Sensor pixel unit, preparation method thereof and electronic equipment
By shortening the gate distance between the diffusion active region and the source follow transistor, the parasitic capacitance in the CMOS image sensor is reduced, the photoelectric conversion gain of the photodiode and the photosensitive sensitivity of the image sensor are improved, the problem of excessive parasitic capacitance in the prior art is solved, and the image quality is optimized.
Patent Information
- Application Number
- CN202411997065.8
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-12-31
- Publication Date
- 2025-04-25
AI Technical Summary
In the existing CMOS image sensors, the distance between the diffusion active region and the gate terminal of the source follow transistor is large, resulting in an increase in parasitic capacitance, reducing the photoelectric conversion gain of the photodiode, and thus affecting the photosensitive sensitivity and image quality of the image sensor.
By shortening the distance between the diffusion active region and the gate terminal of the source follow transistor, and connecting it through a conductive device with a preset structure, the parasitic capacitance is reduced and the photoelectric conversion gain of the photodiode is improved.
The parasitic capacitance is reduced, the sensitivity of image sensor pixels to optical signals is improved, and the image quality of pulse-sequence image sensor acquisition is optimized.
Smart Images
Figure CN119894131A_ABST
Abstract
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 charge transfer transistor, a reset transistor, a source follower transistor, and a pixel selection transistor;
[0004] The source terminal of the charge transfer transistor is connected to the photodiode, the gate terminal receives an external switch signal, the drain terminal is connected to the source terminal of the reset transistor, and the drain terminal active area of the charge transfer transistor is connected to the source terminal active area of the reset transistor as a diffusion active area;
[0005] The photodiode is used for photoelectric conversion to obtain photoelectric charges, and accumulate the photoelectric charges, and in response to reaching a charge output condition, transmit the photoelectric charges to the diffusion active region through the charge transfer transistor;
[0006] The gate terminal of the reset transistor receives a reset signal, and in response to the reset signal, the reset transistor is controlled to be turned on, and the charge transfer transistor is turned on, so as to perform a reset operation on 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] In the circuit layout, the distance between the diffusion active region and the gate terminal of the source follower transistor is less than a preset distance, and they are connected through a conduction device with a preset structure.
[0010] Optionally, the source follower transistor receives the photoelectric charge accumulated in the diffusion active area through the path formed by the conductive device, generates a corresponding target signal according to the change of the photoelectric charge, and outputs the target signal through the drain terminal of the pixel selection transistor.
[0011] Optionally, the conductive device comprises a connecting member made of a first material and two contact members made of a second material; the first material and the second material are different;
[0012] The connecting member connects the diffusion active region and the gate terminal of the source follower transistor through the contact member;
[0013] The two contacts are respectively arranged at the contact position between the connecting member and the diffusion active region, and at the contact position between the connecting member and the gate terminal of the source follower transistor.
[0014] Optionally, the first material is a metal material or a metal composite material; and the second material is a metal silicide.
[0015] Optionally, the thickness of the connecting member is 10 nm to 200 nm.
[0016] Another aspect of the present disclosure provides a local preparation method of a sensor pixel unit, comprising:
[0017] A diffusion active region shared by the drain terminal of the charge transfer transistor and the source terminal of the reset transistor, a shallow trench isolation region and a gate region of the source follower transistor are prepared on a semiconductor silicon substrate to obtain an initial device;
[0018] Depositing a layer of metal material on the upper surface of the initial device;
[0019] According to the positional relationship between the diffusion active region and the gate region, determine the position and shape of the connector connecting the diffusion active region and the gate region, and only retain the metal material corresponding to the position of the connector;
[0020] The diffusion active region and the position where the gate region is connected to the connection piece are subjected to silicidation treatment to obtain two contacts of a preset thickness, and the diffusion active region and the gate region are connected by the connection piece and the two contacts.
[0021] Optionally, determining the position and shape of a connector connecting the diffusion active region and the gate region according to the positional relationship between the diffusion active region and the gate region, and retaining only the metal material corresponding to the position of the connector, comprises:
[0022] Determine the position and shape of the connector connecting the diffusion active area and the gate area by photoresist development technology;
[0023] The metal material at the remaining positions except the connecting parts is removed.
[0024] Optionally, the determining the position and shape of the connector connecting the diffusion active region and the gate region by using a photoresist development technology includes:
[0025] Spin-coating photoresist on the upper surface of the metal material;
[0026] The photoresist is exposed and developed, and the position and shape of the connector connecting the diffusion active area and the gate area are determined according to the developed shape, and the photoresist outside the connector area is removed;
[0027] The step of removing the metal material from other locations except the connecting piece comprises:
[0028] The exposed metal material is etched away by covering with photoresist.
[0029] Optionally, depositing a layer of metal material on the upper surface of the initial device includes:
[0030] A layer of metal material is deposited on the upper surface of the initial device using a PVD sputtering process.
[0031] Another aspect of the embodiments of the present disclosure provides an electronic device, including:
[0032] 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;
[0033] The memory stores computer-executable instructions;
[0034] The processor executes computer-implemented instructions stored in the memory to control the sensor pixel unit.
[0035] 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.
[0036] The embodiment of the present disclosure provides a sensor pixel unit and a preparation method thereof, an electronic device, a photodiode, a charge transfer transistor, a reset transistor, a source follower transistor and a pixel selection transistor; the source terminal of the charge transfer transistor is connected to the photodiode, the gate terminal receives an external switch signal, the drain terminal is connected to the source terminal of the reset transistor, and the drain terminal active area of the charge transfer transistor is connected to the source terminal active area of the reset transistor as a diffusion active area; the photodiode is used for photoelectric conversion to obtain photoelectric charge, and accumulates the photoelectric charge, and in response to reaching the charge output condition, the photoelectric charge is transmitted to the diffusion active area through the charge transfer transistor The gate terminal of the reset transistor receives a reset signal, controls the reset transistor to turn on in response to the reset signal, and the charge transfer transistor turns on to perform a reset operation on 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 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; in the circuit layout, the distance between the diffuse active area and the gate terminal of the source follower transistor is less than a preset distance, and is connected through a conductive device of a preset structure. The disclosed embodiment reduces the parasitic capacitance by shortening the distance between the diffuse active area and the gate terminal of the source follower transistor, improves the photoelectric conversion gain of the photocharge collected by the photodiode, thereby improving the photosensitivity of the image sensor pixel to the light signal, and optimizes the image quality captured by the pulse sequence image sensor.
[0037] The technical solution of the present disclosure is further described in detail below through the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS
[0038] 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.
[0039] The present disclosure may be more clearly understood from the following detailed description with reference to the accompanying drawings, in which:
[0040] Figure 1 is a circuit diagram of an embodiment of a sensor pixel unit disclosed herein;
[0041] 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;
[0042] Figure 3 The pixel unit of the sensor disclosed herein corresponds to Figure 2 A partial cross-sectional view of an embodiment is provided;
[0043] Figure 4 The pixel unit of the sensor disclosed herein corresponds to Figure 2 A partial cross-sectional view of another embodiment is provided;
[0044] Figure 5 A flow chart of a local preparation method of a sensor pixel unit provided in an embodiment of the present disclosure;
[0045] Figure 6a A schematic diagram of substrate preparation in a local preparation method of a sensor pixel unit provided in an embodiment of the present disclosure;
[0046] Figure 6b A schematic diagram of depositing metal materials in a local preparation method of a sensor pixel unit provided in an embodiment of the present disclosure;
[0047] Figure 6c 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 6d 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 6e A schematic diagram of etching a metal material in a local preparation method of a sensor pixel unit provided in an embodiment of the present disclosure;
[0050] Figure 6f A schematic diagram of removing photoresist in a local preparation method of a sensor pixel unit provided in an embodiment of the present disclosure;
[0051] Figure 6g A schematic diagram of a silicide treatment in a local preparation method of a sensor pixel unit provided in an embodiment of the present disclosure;
[0052] Figure 7 The figure is a schematic diagram of the structure of an application embodiment of the electronic device disclosed in the present invention. DETAILED DESCRIPTION
[0053] 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.
[0054] 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.
[0055] 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.
[0056] 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.
[0057] 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.
[0058] 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.
[0059] 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.
[0060] 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.
[0061] 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.
[0062] 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.
[0063] 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.
[0064] 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.
[0065] Image sensors are usually used to convert optical signals into electrical signals. They are an important part of digital cameras. According to the different pixel devices of image sensors, they can be divided into two categories: charge coupled device (CCD) and CMOS image sensor (CIS). Usually, the active pixel unit in the pixel array of a CMOS image sensor contains a photodiode (PD) and several transistors. Figure 1 FIG. 4 is a circuit diagram of an embodiment of a sensor pixel unit disclosed in the present invention. Figure 1 Taking a 4-transistor CMOS image sensor pixel as an example, the pixel unit includes: a photodiode 101, a charge transfer transistor (Transfer, TX) 102, a reset transistor (Reset, RST) 105, a drain follower transistor (Source Follow, SF) 103 and a pixel selection transistor (Row Select, SEL) 104.
[0066] The connection relationship between the components in this embodiment is the same as that of the existing 4T pixel unit, wherein one end of the photodiode 101 is grounded, and the other end of the photodiode 101 is connected to the source end of the charge transfer transistor 102 .
[0067] The source terminal of the charge transfer transistor 102 is connected to the photodiode 101, the gate terminal receives an external switch signal, the drain terminal is connected to the source terminal of the reset transistor 105, and the drain terminal active area of the charge transfer transistor 102 is connected to the source terminal active area of the reset transistor 105 as a diffusion active area FD (floating diffusion). In the prior art, a metal wire is used to connect the FD and the gate terminal of the SF together.
[0068] Figure 1The working principle of the pixel shown is that the PD collects photoelectric charges during the pixel exposure process. When the pixel exposure ends, the TX tube is turned on to transfer the photoelectric charges in the PD to the FD. The SF tube detects the FD potential signals before and after the aforementioned photoelectric charge transmission and transmits them to the subsequent circuit for processing through the Vpix terminal. The difference between the two signals is called the photoelectric signal. The intensity of the photoelectric signal, that is, the photosensitivity of the pixel, is determined by the photoelectric conversion gain at the FD and is inversely proportional to the parasitic capacitance of the FD. The parasitic capacitance of the FD consists of two parts: the parasitic capacitance of the FD active area and the FD metal wiring capacitance. In the conventional pixel design in the prior art, the FD metal wiring capacitance will account for about half of the total parasitic capacitance of the FD. The parasitic capacitance of the FD active area is limited by the process node of the process manufacturing platform, and it is difficult to reduce this part of the capacitance.
[0069] The photodiode 101 is used for photoelectric conversion to obtain photoelectric charges and accumulate the photoelectric charges. In response to reaching a charge output condition, the photoelectric charges are transferred to the diffusion active region FD through the charge transfer transistor 102 .
[0070] The source terminal of the reset transistor 105 is connected to the power supply terminal Vdd to receive the power supply signal. The gate terminal of the reset transistor 105 receives the reset signal and is turned on or off according to the control of the reset signal. In response to the reset signal, the reset transistor 105 is turned on and the charge transfer transistor 102 is turned on to perform a reset operation on the photodiode 101.
[0071] In order to improve the photoelectric conversion gain at the FD to increase the photosensitivity of the pixel and thus enhance the image quality of the CMOS image sensor, especially in a low-light environment, the present disclosure proposes the following circuit layout scheme to reduce the parasitic capacitance of the FD.
[0072] 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 diffusion active region FD and the gate terminal of the source follower transistor 103 is less than a preset distance, and they are connected through a conductive device with a preset structure.
[0073] This embodiment reduces the distance between the diffusion active region FD 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 diffusion active region FD.
[0074] In order to more clearly describe the local structural connection structure of the present disclosure, Figure 3The 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 A schematic diagram of a cross-sectional device at position 22 is shown. A shallow trench isolation region 301 is provided 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 diffusion active region and the gate terminal of the source follower transistor 103, the diffusion active region and the gate terminal of the source follower transistor 103 are additionally marked, wherein the diffusion active region 302 is formed by connecting the drain end active region of the charge transfer transistor 102 and the source end active region of the reset transistor 105, 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 3 , the position of the connecting device 201 is clearly shown, one side of the connecting device 201 is connected to the gate terminal 303, and the other side of the connecting device 201 is connected to the diffusion active area 302; in this embodiment, the source follower transistor 103 is arranged at a position close to the diffusion active area 302, 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).
[0075] like Figure 2 As shown, the diffusion active area 302 is also connected to the source terminal of the reset transistor 105. In response to the reset transistor 105 receiving a reset signal through the gate terminal, the diffusion active area 302 is connected to the power signal through the reset transistor 102 to clear the photoelectric charge in the diffusion active area 302.
[0076] 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.
[0077] The source follower transistor 103 is used to follow the charge change in the diffusion active region 302 to generate a corresponding target signal (eg, a voltage signal Vpix, etc.), and output it through the pixel selection transistor 104 .
[0078] 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.
[0079] 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 .
[0080] In the circuit layout, you can follow Figure 2 The provided embodiment is laid out, wherein the charge transfer transistor 102 is directly connected to the photodiode, the reset transistor 105 is located at the lower right corner of the photodiode 101, the reset transistor 105 is connected to the source follower transistor 103 through the diffused active region FD and the conductive device, 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.
[0081] The disclosed embodiments reduce the parasitic capacitance by shortening the distance between the diffusion active region and the gate terminal of the source follower transistor, thereby improving 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.
[0082] The source follower transistor 103 receives the photoelectric charges accumulated in the diffusion active region through the path formed by the conductive device 201 , generates a corresponding target signal according to the change of the photoelectric charges, and outputs the target signal through the drain terminal of the pixel selection transistor 104 .
[0083] Figure 4 Shows Figure 2 Another schematic diagram of a cross-sectional device at position 22 is shown. Figure 4 As shown, the conductive device 201 includes a connecting member 202 made of a first material and two contact members 203 made of a second material.
[0084] The first material and the second material are different.
[0085] The connection member 202 connects the diffusion active region 302 and the gate terminal of the source follower transistor 103 through a contact.
[0086] The two contacts 203 are respectively disposed at the contact position between the connector 202 and the diffusion active region 302 , and at the contact position between the connector 202 and the gate terminal of the source follower transistor 103 .
[0087] Since the length of the connecting piece is short, no parasitic capacitance is generated, thereby improving the photosensitivity of the sensor pixel unit.
[0088] This embodiment reduces the contact resistance between the connector and the diffusion active area by directly setting a contact in the diffusion active area; and a contact is set at the contact point between the connector and the gate polysilicon of the source follower transistor 103 to reduce the contact resistance between the connector and the gate polysilicon of the source follower transistor 103.
[0089] In some optional embodiments, the first material is a metal material or a metal composite material; and the second material is a metal silicide.
[0090] Optionally, the metal material may be cobalt Co or titanium nitride TiN, or a composite of Co and TiN, or a platinum-nickel alloy NiPt, or a composite of NiPt and TiN.
[0091] This embodiment reduces the contact resistance between the connector and other devices by providing a contact made of metal silicide on the connection surface between the connector made of metal material or metal composite material and other devices (diffusion active area or gate terminal of source follower transistor).
[0092] In some optional embodiments, the thickness of the connecting member is 10 nm to 200 nm.
[0093] The disclosed embodiment shortens the distance between the diffusion active region and the gate terminal of the source follower transistor, and by providing a contact piece made of metal silicide on the contact surface of the connector, parasitic capacitance is eliminated, the photoelectric conversion gain of the photocharge collected by the photodiode is further improved, the photosensitivity of the image sensor pixels to the light signal is enhanced, and the image quality captured by the pulse sequence image sensor is optimized.
[0094] Optionally, the photodiode 101, the charge transfer transistor 102, the reset transistor 105, the source follower transistor 103 and the pixel selection transistor 104 are fabricated on a semiconductor silicon substrate, and the portion of the diffused active region that is not connected to the conduction device and the source terminal of the reset transistor 102 is covered by a gate oxide layer.
[0095] 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 .
[0096] like Figure 3 As shown in FIG. 1 , the gate terminal is isolated from other devices by a shallow trench isolation region 301 .
[0097] Figure 5 Flow chart of a local preparation method of a sensor pixel unit provided in an embodiment of the present disclosure. Figure 5 As shown, the preparation method provided in this embodiment can be used to prepare the above Figure 1-3 The sensor pixel unit provided in any embodiment includes:
[0098] Step 502 , a diffusion active region shared by the drain terminal of the charge transfer transistor and the source terminal of the reset transistor, a shallow trench isolation region, and a gate region of the source follower transistor are prepared on a semiconductor silicon substrate to obtain an initial device.
[0099] In this embodiment, the process of preparing the diffusion active region shared by the drain terminal of the charge transfer transistor and the source terminal of the reset transistor, the shallow trench isolation region and the gate region of the source follower transistor on the semiconductor silicon substrate can refer to the common preparation method of the 4-transistor pixel unit in the prior art, which will not be described in detail here. Figure 6a As shown, a part of the preparation of the pixel unit is shown, in which a diffusion active area 302, a shallow trench isolation area 301 and a gate area of a source follower transistor are prepared on a semiconductor silicon substrate (P-epi).
[0100] Step 504: depositing a layer of metal material on the upper surface of the initial device.
[0101] Optionally, the metal material may be cobalt Co or titanium nitride TiN, or a composite of Co and TiN, or a platinum-nickel alloy NiPt, or a composite of NiPt and TiN.
[0102] Optionally, the thickness of the deposited metal material may be 10 nm to 200 nm, and a thin layer of metal may be deposited to prepare a connector later. Figure 6b As shown, a thin layer of metal material is deposited on the initial device.
[0103] Step 506 , determining the position and shape of a connector connecting the diffusion active region and the gate region according to the positional relationship between the diffusion active region and the gate region, and only retaining the metal material corresponding to the position of the connector.
[0104] Optionally, in order to reduce the contact resistance, the present embodiment sets the distance between the diffusion active region and the gate region to a smaller value to reduce the parasitic capacitance.
[0105] Step 508 , performing silicidation processing on the position where the diffusion active region and the gate region are connected to the connecting member to obtain two contacts of a preset thickness, and the diffusion active region and the gate region are connected by the connecting member and the two contacts.
[0106] In this embodiment, the contact resistance of the connector is reduced by performing silicidation on the diffusion active region and the gate region contacted by the connector.
[0107] In this embodiment, the diffusion active region FD is connected to the gate terminal of the source follower transistor using a thin layer of metal; the contact resistance between the diffusion active region and the thin layer of metal is low, and the contact resistance between the thin layer of metal and the gate terminal of the source follower transistor is low, which is conducive to the stability of the semiconductor manufacturing process, and the contact resistance is further reduced by silicide treatment of the contact surface between the gate terminal and the thin layer of metal. The diffusion active region FD is connected to the gate terminal of the source follower transistor using a thin layer of metal, which can greatly reduce the metal parasitic capacitance formed by the FD metal connection compared to the conventional aluminum or copper process used in the prior art to make metal connections, thereby improving the photosensitivity of the prepared sensor pixel unit.
[0108] In some optional embodiments, step 506 may include:
[0109] The position and shape of the connector connecting the diffusion active area and the gate area are determined by photoresist development technology.
[0110] This embodiment improves the preparation efficiency of the connector by developing the photoresist.
[0111] Remove all metal material except for the connector.
[0112] In this embodiment, only the metal material at the connector position is retained through photoresist development, so that the shape of the prepared connector is more in line with the required length, the excessive contact between the connector and the gate area is reduced, the contact resistance is reduced, and the preparation efficiency of the pixel unit is improved.
[0113] Optionally, determining the position and shape of the connector connecting the diffusion active region and the gate region by photoresist development technology includes:
[0114] like Figure 6c As shown, photoresist is spin-coated on the surface of the metal material.
[0115] like Figure 6d As shown, the photoresist is exposed and developed, and the position and shape of the connector connecting the diffusion active area and the gate area are determined according to the developed shape, and the photoresist outside the connector area is removed.
[0116] 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.
[0117] Optionally, removing metal materials from other locations except the connecting parts includes:
[0118] like Figure 6e As shown, the exposed metal material is removed by etching through the covering of the photoresist. Optionally, the excess metal material is removed by chemical ion etching.
[0119] Then remove the photoresist on the surface of the polysilicon material, and you can get Figure 6f The structure shown.
[0120] Afterwards, if Figure 6g As shown, the diffusion active region and the position where the gate region is connected to the connecting member are silicided to obtain two contacts of a preset thickness, and the connecting member and the two contacts are used to connect the diffusion active region and the gate region. The gate terminal and connecting device of the prepared source follower transistor are obtained. Figure 4The pixel unit shown in the figure. This embodiment uses a chemical ion etching method to remove excess metal material to achieve the shape preparation of the metal material without damaging the electronic performance of the electronic device, which has a great advantage over other physical methods.
[0121] In addition, an embodiment of the present disclosure further provides an electronic device, including:
[0122] A processor, and a memory communicatively connected to the processor, further comprising the sensor pixel unit described in any one of the above embodiments;
[0123] The memory stores computer-executable instructions;
[0124] The processor executes computer-implemented instructions stored in the memory to control the sensor pixel unit.
[0125] 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.
[0126] 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.
[0127] Figure 7 This is a schematic diagram of the structure of an application embodiment of the electronic device disclosed in the present invention. Figure 7 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.
[0128] like Figure 7 As shown, the electronic device includes one or more processors and memory.
[0129] 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.
[0130] 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.
[0131] 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).
[0132] In addition, the input device may also include, for example, a keyboard, a mouse, and the like.
[0133] 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.
[0134] Of course, to simplify, Figure 7 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.
[0135] 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.
[0136] 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.
[0137] 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.
[0138] 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.
[0139] 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.
[0140] 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.
[0141] 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.
[0142] 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.
[0143] 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.
[0144] 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.
[0145] 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: photodiode, charge transfer transistor, reset transistor, source follower transistor, and pixel select transistor; The source terminal of the charge transfer transistor is connected to the photodiode, the gate terminal receives an external switch signal, the drain terminal is connected to the source terminal of the reset transistor, and the drain terminal active area of the charge transfer transistor is connected to the source terminal active area of the reset transistor as a diffusion active area; The photodiode is used for photoelectric conversion to obtain photoelectric charges, and accumulate the photoelectric charges, and in response to reaching a charge output condition, transfer the photoelectric charges to the diffusion active region through the charge transfer transistor; The gate terminal of the reset transistor receives a reset signal, and in response to the reset signal, the reset transistor is controlled to be turned on, and the charge transfer transistor is turned on, so as to perform a reset operation on 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; In the circuit layout, the distance between the diffusion active region and the gate terminal of the source follower transistor is less than a preset distance, and they are connected through a conduction device with a preset structure.
2. The pixel unit according to claim 1, characterized in that: The source follower transistor receives the photoelectric charge accumulated in the diffusion active area through the path formed by the conductive device, generates a corresponding target signal according to the change of the photoelectric charge, and outputs the target signal through the drain terminal of the pixel selection transistor.
3. The pixel unit according to claim 1 or 2, characterized in that: The conductive device comprises a connecting piece made of a first material and two contact pieces made of a second material; the first material and the second material are different; The connecting member connects the diffusion active region and the gate terminal of the source follower transistor through the contact member; The two contacts are respectively arranged at the contact position between the connecting member and the diffusion active region, and at the contact position between the connecting member and the gate terminal of the source follower transistor.
4. The pixel unit according to claim 3, characterized in that: The first material is a metal material or a metal composite material; the second material is a metal silicide.
5. The pixel unit according to claim 3 or 4, characterized in that: The thickness of the connecting member is 10nm-200nm.
6. A local preparation method of a sensor pixel unit, characterized in that: include: A diffusion active region shared by the drain terminal of the charge transfer transistor and the source terminal of the reset transistor, a shallow trench isolation region and a gate region of the source follower transistor are prepared on a semiconductor silicon substrate to obtain an initial device; Depositing a layer of metal material on the upper surface of the initial device; According to the positional relationship between the diffusion active region and the gate region, determine the position and shape of the connector connecting the diffusion active region and the gate region, and only retain the metal material corresponding to the position of the connector; The diffusion active region and the position where the gate region is connected to the connecting member are subjected to silicidation treatment to obtain two contacts of a preset thickness, and the diffusion active region and the gate region are connected by the connecting member and the two contacts.
7. The method according to claim 6, characterized in that The step of determining the position and shape of a connector connecting the diffusion active region and the gate region according to the positional relationship between the diffusion active region and the gate region, and retaining only the metal material corresponding to the position of the connector, comprises: Determine the position and shape of the connector connecting the diffusion active area and the gate area by photoresist development technology; The metal material at the remaining positions except the connecting parts is removed.
8. The method according to claim 7, characterized in that The step of determining the position and shape of the connector connecting the diffusion active area and the gate area by using a photoresist development technique includes: Spin-coating photoresist on the upper surface of the metal material; The photoresist is exposed and developed, and the position and shape of the connector connecting the diffusion active area and the gate area are determined according to the developed shape, and the photoresist outside the connector area is removed; The step of removing the metal material from the remaining positions except the connecting member comprises: The exposed metal material is etched away by covering with photoresist.
9. The method according to any one of claims 6 to 8, characterized in that: The step of depositing a layer of metal material on the upper surface of the initial device comprises: A layer of metal material is deposited on the upper surface of the initial device using a PVD sputtering process.
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.