Image sensing device

Abstract

The present application relates to image sensing devices. An image sensing device includes a substrate including a substrate surface and a trench extending from the substrate surface, a plurality of photoelectric conversion elements formed in the substrate and operable to convert incident light into photocharge, an electrode formed in the trench and configured to receive a bias voltage for suppressing dark current, and a light-blocking layer formed over the substrate surface of the substrate to block transmission of light therethrough and configured to be electrically conductive to receive the bias voltage and transmit the received bias voltage to the electrode.

Description

Technical Field

[0001] The technology and implementation disclosed in this patent document generally relate to an image sensing device that includes one or more pixels capable of sensing incident light by generating an electrical signal corresponding to the intensity of the incident light. Background Technology

[0002] Image sensing devices are used to capture optical images by converting light into electrical signals using photosensitive semiconductor materials that react with light. With the development of the automotive, medical, computer, and communications industries, the demand for high-performance image sensing devices is constantly increasing in various fields such as smartphones, digital cameras, game consoles, IoT (Internet of Things), robotics, security cameras, and medical miniature cameras.

[0003] Image sensing devices can be broadly categorized into CCD (Charge-Coupled Device) image sensing devices and CMOS (Complementary Metal-Oxide-Semiconductor) image sensing devices. CCD image sensing devices offer better image quality, but compared to CMOS image sensing devices, they tend to consume more power and are larger. CMOS image sensing devices are smaller and consume less power than CCD image sensing devices. Furthermore, CMOS sensors are manufactured using CMOS fabrication technology, allowing photosensitive elements and other signal processing circuitry to be integrated onto a single chip, enabling the production of miniaturized image sensing devices at a lower cost. For these reasons, CMOS image sensing devices are being developed for many applications, including mobile devices. Summary of the Invention

[0004] Various embodiments of the disclosed technology relate to an image sensing device that includes a deep trench isolation (DTI) layer, such as a back-side DTI (BDTI), thereby reducing optical crosstalk between adjacent pixels.

[0005] According to an embodiment of the disclosed technology, an image sensing device may include: a substrate including a substrate surface and a trench extending from the substrate surface; a plurality of photoelectric conversion elements formed in the substrate and operable to convert incident light into photocharge; electrodes formed in the trenches and configured to receive a bias voltage for suppressing dark current; and a light blocking layer formed above the substrate surface of the substrate to block light transmission through it and configured to be conductive to receive the bias voltage and transmit the received bias voltage to the electrodes.

[0006] According to another embodiment of the disclosed technology, an image sensing device may include: a pixel array comprising an effective pixel region and an optical black pixel region, the effective pixel region comprising a plurality of effective pixels that receive incident light and generate a signal indicating the intensity of the received incident light, the optical black pixel region comprising a plurality of optical black pixels, the optical black pixels comprising a light-blocking layer to block light from entering and generate a signal independent of the intensity of the incident light received by the optical black pixels; an electrode configured to include a vertically extending portion disposed between adjacent pixels of the effective pixels and the optical black pixels, and configured to receive a bias voltage for suppressing dark current generated in at least one of the effective pixel region or the optical black pixel region; and a bias generator configured to generate the bias voltage. The light-blocking layer in the optical black pixel region is configured to conduct electricity to receive the bias voltage from the bias generator and transmit the received bias voltage to the electrode.

[0007] It should be understood that both the foregoing general description of the disclosed technology and the following detailed description are illustrative and explanatory, and are intended to provide a further explanation of the claimed disclosure. Attached Figure Description

[0008] Figure 1 This is a block diagram illustrating examples of image sensing devices based on some implementations of the disclosed technology.

[0009] Figure 2 These are examples of some implementations based on the disclosed technology. Figure 1 A schematic diagram of an example pixel array shown.

[0010] Figure 3 These are examples of some implementations based on the disclosed technology. Figure 1 A schematic diagram of another example of a pixel array is shown.

[0011] Figure 4 These are examples of some implementations based on the disclosed technology. Figure 2 or Figure 3 The circuit diagram shows an example of an effective pixel or optical black pixel included in the pixel array shown.

[0012] Figure 5 It is based on some implementations of the disclosed technology. Figure 2 or Figure 3 An example of the first cross-section of the pixel array shown.

[0013] Figure 6 It is based on some implementations of the disclosed technology. Figure 2 or Figure 3 An example of the second cross section of the pixel array shown.

[0014] Figure 7This is a schematic diagram illustrating examples of pixel arrays based on some implementations of the disclosed technology. Detailed Implementation

[0015] This patent document provides implementations and examples of an image sensing device comprising one or more pixels capable of sensing incident light by generating an electrical signal corresponding to the intensity of the incident light. This image sensing device can be configured to fundamentally solve one or more technical or engineering problems and mitigate limitations or drawbacks encountered in some other image sensing devices. Some implementations of the disclosed technology relate to image sensing devices for reducing optical crosstalk between adjacent pixels. The disclosed technology provides various implementations of image sensing devices having an optimal structure for reducing crosstalk between pixels.

[0016] In the following description, various embodiments will be illustrated with reference to the accompanying drawings. However, it should be understood that the disclosed technology is not limited to specific embodiments, but includes various modifications, equivalents, and / or substitutions of the embodiments. Embodiments of the disclosed technology can provide various effects that can be directly or indirectly recognized through the disclosed technology.

[0017] Figure 1 This is a block diagram illustrating an image sensing device 100 according to an embodiment of the disclosed technology.

[0018] Reference Figure 1 The image sensing device 100 may include a pixel array 110, a row driver 120, a correlated dual sampler (CDS) 130, an analog-to-digital converter (ADC) 140, an output buffer 150, a column driver 160, a timing controller 170, and a bias generator 180. This is discussed by way of example only. Figure 1 The components of the image sensing device 100 shown are included, and this patent document covers many other changes, substitutions, variations, alterations and modifications.

[0019] Pixel array 110 may include a plurality of pixels arranged in rows and columns. In one example, the plurality of pixels may be arranged in a two-dimensional pixel array including rows and columns. In another example, the plurality of unit imaging pixels may be arranged in a three-dimensional pixel array. The plurality of pixels may convert optical signals into electrical signals on a pixel-by-pixel or pixel-group basis, wherein pixels in a pixel group share at least some internal circuitry. Pixel array 110 may receive drive signals including a row selection signal, a pixel reset signal, and a transmission signal from row driver 120. Once a drive signal is received, a corresponding pixel in pixel array 110 may be activated to perform an operation corresponding to the row selection signal, pixel reset signal, and transmission signal.

[0020] The row driver 120 can activate the pixel array 110 to perform certain operations on pixels in corresponding rows based on command and control signals provided by controller circuitry such as timing controller 170. In some implementations, the row driver 120 can select one or more pixels arranged in one or more rows of the pixel array 110. The row driver 120 can generate a row selection signal to select one or more rows among a plurality of rows. The row driver 120 can sequentially enable a pixel reset signal for resetting the imaging pixel corresponding to at least one selected row, and a transmission signal for the pixel corresponding to at least one selected row. Thus, an image signal and a reference signal, which are analog signals generated by each imaging pixel of the selected row, can be sequentially transmitted to the CDS 130. The reference signal can be an electrical signal provided to the CDS 130 when the sensing node (e.g., a floating diffusion node) of the pixel is reset, and the image signal can be an electrical signal provided to the CDS 130 when photocharge generated by the pixel accumulates in the sensing node. The reference signal, indicating the unique reset noise of each pixel, and the image signal, indicating the intensity of the incident light, can be collectively referred to as pixel signals as needed.

[0021] CMOS image sensors can use Correlated Double Sampling (CDS) to remove the difference between two samples by sampling the pixel signal twice, thereby removing unwanted offset values ​​of the pixel, known as fixed-pattern noise. In one example, Correlated Double Sampling (CDS) can remove unwanted offset values ​​of the pixel by comparing the pixel output voltage obtained before and after the photocharge generated by the incident light accumulates in the sensing node, making it possible to measure the pixel output voltage based solely on the incident light. In some embodiments of the disclosed technology, CDS 130 can sequentially sample and hold the voltage levels of the reference signal and the image signal provided from the pixel array 110 to each of the multiple column lines. That is, CDS 130 can sample and hold the voltage levels of the reference signal and the image signal corresponding to each column of the pixel array 110.

[0022] In some implementations, CDS 130 can transmit the reference signal and image signal of each column as correlated double-sampled signals to ADC 140 based on control signals from timing controller 170.

[0023] ADC 140 is used to convert analog CDS signals into digital signals. In some implementations, ADC 140 can be implemented as a ramp-comparison type ADC. A ramp-comparison type ADC may include comparator circuitry and a timer. The comparator circuitry compares the analog pixel signal with a reference signal, such as a ramp signal (ramp-up or ramp-down), and the timer counts until the voltage of the ramp signal matches the analog pixel signal. In some embodiments of the disclosed technology, ADC 140 can convert the correlated double-sampled signal generated by CDS 130 for each column into a digital signal and output a digital signal. ADC 140 can perform counting and calculation operations based on the correlated double-sampled signal for each column and the ramp signal provided from timing controller 170. In this way, ADC 140 can eliminate or reduce noise such as reset noise generated by imaging pixels when generating digital image data.

[0024] The ADC 140 may include multiple column counters. Each column of the pixel array 110 is coupled to a column counter, and image data can be generated by converting the correlated double-sampled signals received from each column into digital signals using the column counters. In another embodiment of the disclosed technology, the ADC 140 may include a global counter to convert the correlated double-sampled signals corresponding to columns into digital signals using a global code provided from the global counter.

[0025] Output buffer 150 can temporarily hold column-based image data provided from ADC 140 for output image data. In one example, image data provided from ADC 140 to output buffer 150 can be temporarily stored in output buffer 150 based on control signals from timing controller 170. Output buffer 150 can provide an interface to compensate for data rate or transmission rate differences between image sensing device 100 and other devices.

[0026] Once a control signal is received from the timing controller 170, the column driver 160 can select a column of the output buffer and sequentially output the image data temporarily stored in the selected column of the output buffer 150. In some implementations, once an address signal is received from the timing controller 170, the column driver 160 can generate a column selection signal based on the address signal and select a column of the output buffer 150, outputting the image data from the selected column of the output buffer 150 as an output signal.

[0027] The timing controller 170 can control the operation of at least one of the row driver 120, ADC 140, output buffer 150, column driver 160 and bias generator 180.

[0028] The timing controller 170 can provide clock signals to the row driver 120, CDS 130, ADC 140, output buffer 150, column driver 160, and bias generator 180 to perform operations of the image sensing device 100. In some implementations, the timing controller 170 may also provide control signals for timing control, address signals for selecting rows or columns, and control signals for controlling the level of the bias voltage applied to the pixel array 110. In embodiments of the disclosed technology, the timing controller 170 may include logic control circuitry, phase-locked loop (PLL) circuitry, timing control circuitry, communication interface circuitry, etc.

[0029] The bias generator 180 can generate a bias voltage and suppress dark currents that will be generated in the pixels of the pixel array 110 by applying the bias voltage to the pixel array 110, as will be referred to below. Figure 5 The subject of discussion.

[0030] The bias voltage can be determined by performing a wafer probe test on the image sensing device 100 and stored in a one-time programmable memory (OTP). For example, the bias voltage can be determined experimentally in a way that minimizes unnecessary power consumption and maximizes dark current suppression without degrading the performance of the image sensing device 100.

[0031] The bias generator 180 can generate a voltage corresponding to the bias voltage stored in the OTP memory. In some implementations, the OTP memory may be included in the image sensing device 100. In one example, the OTP memory may be included in the bias generator 180.

[0032] In some implementations, the bias voltage can include multiple values.

[0033] For example, multiple values ​​can each correspond to multiple operating modes of the image sensing device 100. The dark current generated under low illumination conditions can differ from the dark current generated under high illumination conditions. In order to effectively suppress the dark current in each environment, the bias voltage provided from the bias generator 180 can vary according to the operating mode.

[0034] Alternatively, multiple values ​​can correspond to multiple regions of the pixel array 110. The dark current generated due to the position of the corresponding pixel in the pixel array 110 can be different from each other. In order to effectively suppress the dark current regardless of the position of each pixel, the bias voltage generated by the bias generator 180 can vary according to the corresponding region.

[0035] In some implementations, the bias voltage can be negative.

[0036] Figure 2These are examples of some implementations based on the disclosed technology. Figure 1 A schematic diagram of an example of a pixel array is shown.

[0037] Reference Figure 2 The pixel array 110-1 may include an effective pixel area 200 and an optical black pixel area 300.

[0038] The effective pixel region 200 may include multiple effective pixels arranged in a matrix array having multiple rows and multiple columns. Each effective pixel may be as follows: Figure 1 The pixel described in the text converts incident light signals into electrical signals.

[0039] Optical black pixel region 300 may be configured to surround at least a portion of effective pixel region 200. Each optical black pixel region 300 may include at least one optical black pixel corresponding to an effective pixel. An optical black pixel may be a pixel used to acquire a dark level signal that does not indicate incident light. For example, the dark level signal may have a value regardless of the intensity of the incident light. Optical black pixels have a similar or identical structure to effective pixels belonging to the same row or column, and can be operated by the same pixel control signal as effective pixels belonging to the same row or column. However, unlike effective pixels, optical black pixels may have a light-blocking or light-blocking structure to block light. That is, the signal generated by the optical black pixel may correspond to a signal indicating dark noise generated due to factors other than incident light (e.g., temperature, unique pixel structure, etc.).

[0040] Image data of the effective pixel can be obtained by calculating (e.g., subtracting) the average value of the dark level signal generated by at least one optical black pixel (e.g., an optical black pixel belonging to the same row or column as the effective pixel), such that the image data may include only the values ​​obtained by incident light. In some implementations, such calculation can be performed by an image signal processor (not shown) configured to receive image data from the image sensing device 100.

[0041] The optical black pixel region 300 may include a light-blocking layer to block incident light from at least one optical black pixel. The light-blocking layer may have a specific area corresponding to the optical black pixel region 300 and may be disposed above the optical black pixel region 300. For example, the light-blocking layer may be large enough to cover the area of ​​the optical black pixel region 300. In various implementations, the light-blocking layer may be formed of a conductive material that also blocks light, including, for example, a metal layer formed of one or more metals or a conductive doped layer.

[0042] The optical black pixel region 300 may include a first contact region 310 and a second contact region 320. For transmitting the bias voltage generated by the bias generator 180, each of the first contact region 310 and the second contact region 320 may include a region of the light-blocking layer electrical contact substrate in which the optical black pixel region 300 is located. (Refer to...) Figure 5 Describes the light-blocking layer in the optical black pixel region 300.

[0043] The first contact area 310 may be a region shorter than either the left or right side of the effective pixel area 200. Within the optical black pixel area 300 located on one of the left or right sides of the effective pixel area 200, it may be in the column direction (e.g., in...). Figure 2 At least one first contact area 310 is provided in the vertical direction.

[0044] The second contact area 320 may be a region shorter than the upper or lower side of the effective pixel area 200. Within the optical black pixel area 300 located above or below the effective pixel area 200, it may be in the row direction (e.g., in...). Figure 2 At least one second contact area 320 is provided in the horizontal direction.

[0045] Each of the first contact region 310 and the second contact region 320 may have a relatively short length. The first contact region 310 and the second contact region 320 may be spaced apart from each other, such that each of the first contact region 310 and the second contact region 320 may send a bias voltage received from the light blocking layer to the substrate, thereby minimizing the effects of noise that would otherwise be introduced into the local area.

[0046] Figure 3 These are examples of some implementations based on the disclosed technology. Figure 1 A schematic diagram of another example of a pixel array is shown.

[0047] Reference Figure 3 The pixel array 110-2 may include an effective pixel region 200 and an optical black pixel region 300'. In some implementations, the pixel array 110-2 may have the same... Figure 2 The pixel array 110-1 shown has a similar or identical structure. In some implementations, pixel array 110-2 may have the same structure as... Figure 2 The pixel array 110-1 shown has different characteristics, which will be discussed below.

[0048] The optical black pixel region 300′ may include a third contact region 330 and a fourth contact region 340. Each of the third contact region 330 and the fourth contact region 340 may refer to a region of the light-blocking layer electrical contact substrate of the optical black pixel region 300′.

[0049] The third contact area 330 may be a region with a length equal to or longer than the left or right side of the effective pixel area 200, and the third contact area 330 may be arranged in the column direction within the optical black pixel area 300′ located on one of the left and right sides of the effective pixel area 200.

[0050] The fourth contact area 340 may be an area with a length equal to or longer than the upper or lower side of the effective pixel area 200, and the fourth contact area 340 may be arranged in the row direction within the optical black pixel area 300′ located on one side of the upper side and the upper side of the effective pixel area 200.

[0051] Each of the third contact region 330 and the fourth contact region 340 can have a relatively long length and can transmit the bias voltage received from the light-blocking layer of the optical black pixel region 300 to the substrate over a large area. As a result, the resistive component used to transmit the bias voltage can be reduced as much as possible, thus preventing performance degradation caused by the reduction of the bias voltage.

[0052] Figure 4 This is an example Figure 2 or Figure 3 The circuit diagram shows an example of an effective pixel or optical black pixel included in the pixel array.

[0053] Reference Figure 4 The equivalent circuit 400 for each of the effective pixels and optical black pixels may include a photoelectric conversion element PD, a transmission transistor TX, a reset transistor RX, a drive transistor DX, and a selection transistor SX. Although for ease of description... Figure 4 Only the 4TR (i.e., four transistors) structure is described, but effective pixels or optical black pixels may include 3TR (i.e., three transistors) structures, 5TR (i.e., five transistors) structures, or shared pixel structures in which multiple pixels share at least some transistors.

[0054] A photoelectric conversion element (PD) can accumulate photocharge corresponding to the intensity of incident light. One end of the PD can be connected to a source voltage VSS, and the other end can be connected to one or more transfer transistors TX. In one example, the source voltage VSS can be ground. In some implementations, the PD may include a phototransistor, a photogate, a pinned photodiode, or a combination thereof.

[0055] The transmission transistor TX can be connected between the photoelectric conversion element PD and the floating diffusion node FD. The transmission transistor TX can be turned on or off in response to the transmission control signal TG, so that the transmission transistor TX can send the photocharge accumulated in the photoelectric conversion element PD to the floating diffusion node FD.

[0056] A floating diffusion node (FD) can accumulate photocharge received from a transmitting transistor (TX). For example, the floating diffusion node (FD) can be a region with a predetermined capacitance, such that the potential or voltage can vary depending on the amount of photocharge accumulated. For example, the floating diffusion node (FD) can be a junction capacitor, and other implementations are also possible.

[0057] The reset transistor RX can be connected between the drain voltage (VDD) terminal and the floating diffusion node FD, and can reset the voltage of the floating diffusion node FD to the drain voltage VDD in response to the pixel reset signal RG. In this case, although the drain voltage VDD can be the power supply voltage, the scope or spirit of the disclosed technology is not limited thereto.

[0058] The driving transistor DX can amplify the potential or voltage change of the floating diffusion node FD that has received the accumulated photocharge in the photoelectric conversion element PD, and can send the amplified photocharge to the selection transistor SX. In other words, the driving transistor DX can operate as a source follower transistor.

[0059] The select transistor SX can select at least one pixel to be read, row by row. The select transistor SX can be turned on by the select control signal SEL, so that a signal corresponding to the potential change of the floating diffusion node FD supplied to the select transistor SX can be output as the output voltage Vout or Vref.

[0060] The output voltage Vout or Vref of transistor SX can be selected accordingly. Figure 1 The reference signal depicted (e.g., the signal corresponding to the reset floating diffusion node FD) and the image signal (e.g., the signal corresponding to the floating diffusion node FD in which photocharge received from the photoelectric conversion element PD has accumulated).

[0061] However, if the equivalent circuit 400 corresponds to the optical black pixel, this means that the optical black pixel operates in the same way as in the effective pixel, and the incident light is blocked by the light blocking layer, so that the photoelectric conversion element PD can be configured in such a way that photoelectric conversion photocharge can be generated with the incident light and the photocharge caused by noise factors (e.g., temperature, unique pixel structure, etc.) can accumulate in the photoelectric conversion element PD.

[0062] Figure 5 This is an example Figure 2 or Figure 3 A cross-sectional view of an example of the first section 500 of the pixel array shown.

[0063] Reference Figure 5 The first section 500 can correspond to along Figure 2The first section 500 is a cross-section of the pixel array 110-1 intercepted by the line A1-A1′ or A2-A2′ depicted in the pixel array 110-1. Alternatively, the first section 500 may correspond to a section along... Figure 3 The line C1-C1′ or C2-C2′ depicted in the pixel array 110-2 is a cross section of the pixel array 110-2. The line A1-A1′ or A2-A2′ or the line C1-C1′ or C2-C2′ can be a hypothetical line that extends from a portion of the effective pixel region 200 to the boundary between the effective pixel region 200 and the optical black pixel region 300 or 300′, passing through the contact area 310-340 of the optical black pixel region 300 or 300′.

[0064] The first cross-section may include a substrate 510 and a light incident region 560. Additionally, the first cross-section 500 may be divided into a left effective pixel region and a right optical black pixel region. Each effective pixel (AP) in the effective pixel region may have some characteristics that differ from those of each optical black pixel (OBP) in the optical black pixel region (e.g., the presence or absence of a filter, and the presence or absence of a light-blocking layer). In some implementations, apart from those characteristics, each effective pixel (AP) in the effective pixel region may have the same or similar structure and dimensions as the optical black pixel (OBP) in the optical black pixel region.

[0065] The substrate 510 may be a semiconductor substrate and may include a top surface and a bottom surface facing away from each other. In some implementations, the bottom surface of the substrate 510 may be defined as the front side, and the top surface of the substrate 510 may be defined as the back side. Each of the top and bottom surfaces may be referred to as a substrate surface. The image sensing device 100 may be configured to have a back side illumination (BSI) structure that receives incident light through the back side of the substrate 510. For example, the substrate 510 may be a P-type or N-type body substrate, a substrate formed by growing a P-type or N-type epitaxial layer on a P-type body substrate, or a substrate formed by growing a P-type or N-type epitaxial layer on an N-type body substrate.

[0066] The substrate 510 may include an impurity region 520, a photoelectric conversion element 530, a deep trench isolation (DTI) electrode 540, and a DTI insulating layer 550.

[0067] Impurity region 520 may be a region doped with a specific conductive impurity (e.g., P-type or N-type impurity). For example, impurity region 520 may be a P-type or N-type epitaxial layer.

[0068] The photoelectric conversion element 530 can be formed as a P-type or N-type doped region by implanting P-type or N-type impurities into the substrate 510. In some implementations, the photoelectric conversion element 530 can be formed by stacking multiple doped regions with different doping concentrations. The photoelectric conversion element 530 can be arranged to span as large a region as possible to increase the fill factor indicating the light receiving (Rx) efficiency. The photoelectric conversion element 530 can correspond to... Figure 4 The photodiode PD shown is shown.

[0069] At least a portion of the DTI electrode 540 and the DTI insulating layer 550 may be disposed in a DTI structure (i.e., a BDTI (back-side DTI) structure) that is vertically recessed from one side (i.e., the back side) of the substrate 510 by a DTI process on the back surface of the substrate 510.

[0070] The DTI electrode 540 may include a conductive material filling trenches or recesses formed in the substrate. In one example, the DTI electrode 540 is formed in an internal region of the DTI insulating layer 550 in the BDTI structure. For example, the DTI electrode 540 may be formed of metal, polysilicon, or impurity-doped polysilicon. Additionally, the DTI electrode 540 may be disposed between two adjacent pixels (or within the boundary between two adjacent pixels).

[0071] The DTI electrode 540 can receive a bias voltage generated by the bias generator 180. When a negative bias voltage is applied to the DTI electrode 540, holes in the impurity region 520 can move to the interface between the BDTI (or DTI insulating layer 550) and the impurity region 520, and can accumulate at the interface. As described above, since holes in the impurity region 520 can accumulate at the interface between the BDTI (or DTI insulating layer 550) and the impurity region 520, it is possible to suppress the charge flow (i.e., dark current) of defect electrons that may be generated from the BDTI surface due to the DTI process.

[0072] The DTI insulating layer 550 may include an insulating material with a refractive index different from that of the impurity region 520. For example, the DTI insulating layer 550 may be formed of at least one of a silicon oxide layer, a silicon nitride layer, and a silicon oxynitride layer. The DTI insulating layer 550 may be formed in a manner capable of preventing optical crosstalk, where light incident on the effective pixel AP or optical black pixel OBP passes through another adjacent pixel, thereby preventing the occurrence of optical crosstalk that leads to a decrease in signal-to-noise ratio (SNR).

[0073] The BDTI, including the DTI electrode 540 and the DTI insulating layer 550, can be disposed between adjacent photoelectric conversion elements 530 of adjacent pixels (AP or OBP) to suppress dark current and reduce optical crosstalk.

[0074] The light incident region 560 may include an anti-reflection layer 570, a filter 575, an optical grating structure 580, a microlens 585, and a light blocking layer 590.

[0075] The anti-reflective layer 570 allows light that has passed through the microlens 585 and filter 575 to efficiently incident on the substrate 510 without being reflected from the back surface of the substrate 510. Furthermore, the anti-reflective layer 570 can be disposed between the substrate 510 and the light-blocking layer 590. For this purpose, the anti-reflective layer 570 can have a higher refractive index than the microlens 585 and filter 575, while having a lower refractive index than the substrate 510 and the DTI insulating layer 550. For example, the anti-reflective layer 570 can be formed of at least one of a silicon oxide layer, a silicon nitride layer, and a silicon oxynitride layer.

[0076] On the other hand, the DTI electrode extension portion 545 and the light blocking layer extension portion 595 can be disposed in the anti-reflection layer 570 disposed in the optical black pixel region.

[0077] In some implementations, the DTI electrode extension 545 can be a branch of the DTI electrode 540, and therefore the DTI electrode extension 545 can be electrically connected to the DTI electrode 540. Alternatively, the DTI electrode extension 545 can extend from the DTI electrode 540 toward the light-blocking layer 590. (Refer to...) Figure 5 The DTI electrode extension 545 can be configured to cover at least a portion of the back surface of the substrate 510 and can be electrically connected to the DTI electrodes 540 disposed on both sides of the photoelectric conversion element 530 of the optical black pixel (OBP). That is, the DTI electrode extension 545 can have a wider width than the optical black pixel (OBP). In one implementation, the DTI electrode extension 545 has a wider width than a single optical black pixel (OBP) while having a narrower width than two optical black pixels (OBPs). In another implementation, the DTI electrode extension 545 can have a wider width than at least two optical black pixels (OBPs).

[0078] Since the DTI electrode extension 545 is a branch of the DTI electrode 540, the DTI electrode extension 545 can be formed of the same material as the DTI electrode 540.

[0079] In some implementations, the light-blocking layer extension 595 can be a branch of the light-blocking layer 590, configured to prevent light incident on the optical black pixel region from transmitting to the substrate 510, and thus can be electrically connected to the light-blocking layer. Alternatively, the light-blocking layer extension 595 can extend from the light-blocking layer 590 toward the DTI electrode extension 545. For example... Figure 5As shown, the light-blocking layer extension 595 can be configured to contact the DTI electrode extension 545 while covering at least a portion of the DTI electrode extension 545. That is, the light-blocking layer extension 595 can have a smaller width than the DTI electrode extension 545, and other implementations are also possible. It should be noted that the width of the light-blocking layer extension 595 can be equal to or greater than the width of the DTI electrode extension 545.

[0080] Since the light-blocking layer extension 595 is a branch of the light-blocking layer 590, the light-blocking layer extension 595 can have the same material as the light-blocking layer 590.

[0081] The DTI electrode extension 545 can protrude from the DTI electrode 540, and the light-blocking layer extension 595 can protrude from the light-blocking layer 590. Therefore, the protruding DTI electrode extension 545 and the protruding light-blocking layer extension 595 can contact each other while being formed as a plug structure, allowing the resulting DTI electrode extension 545 and the resulting light-blocking layer extension 595 to be in electrical contact with each other. In this case, the area where the DTI electrode extension 545 contacts the light-blocking layer extension 595 can correspond to... Figure 2 or Figure 3 The contact areas shown are 310 to 340.

[0082] Since the DTI electrode extension 545 and the light blocking layer extension 595 are connected to each other by a plug structure, the contact area can have any shape and position in the optical black pixel area.

[0083] Depend on Figure 1 The bias voltage generated by the bias generator 180 can be sent to the light-blocking layer 590 in the optical black pixel region, and the light-blocking layer 590 can send the bias voltage to the DTI electrode 540 in the optical black pixel region through the DTI electrode extension portion 545 and the light-blocking layer extension portion 595. Since the DTI electrode 540 in the optical black pixel region is connected to the DTI electrode 540 in the effective pixel region, the DTI electrode 540 in the effective pixel region can receive the bias voltage as input.

[0084] In some implementations, since the light-blocking layer 590 is used to apply the bias voltage to the DTI electrode 540, the bias voltage can be effectively applied to the DTI electrode 540 without adding a separate voltage delivery structure.

[0085] Furthermore, since the DTI electrode 540 and the light blocking layer 590 are connected to each other through a plug structure, the DTI electrode 540 and the light blocking layer 590 can be connected to each other.

[0086] In some implementations, the DTI electrode extension 545 and the light-blocking layer extension 595 can be formed as will be discussed below. After the BDTI (e.g., trenches or recesses) of the substrate 510 is sequentially filled with the DTI insulating layer 550 and the DTI electrode 540, the remaining areas of the conductive material disposed above the substrate 510, except for the DTI electrode extension 545, can be selectively etched and removed. Subsequently, an anti-reflective layer 570 can be disposed, and the area corresponding to the light-blocking layer extension 595 can be selectively etched. Then, conductive material for forming the light-blocking layer 590 and the optical grating structure 580 is disposed above the anti-reflective layer 570, resulting in the light-blocking layer extension 595.

[0087] Filter 575 can be formed above anti-reflection layer 570 and can selectively transmit light with the desired wavelength (e.g., red, green, blue, magenta, yellow, cyan, white, etc.). In some implementations, when the effective pixel AP corresponds to a depth pixel, filter 575 can be omitted or replaced by an infrared (IR) filter.

[0088] Optical grating structure 580 may be disposed between adjacent filters 575 to prevent optical crosstalk between adjacent filters 575. In some implementations, optical grating structure 580 may include a metallic material (e.g., tungsten) with high light absorption.

[0089] Each microlens 585 can be formed above the filter 575 and the light-blocking layer 590, and can increase the focusing ability of incident light, thereby improving the light receiving (Rx) efficiency of the photoelectric conversion element. The microlens 585 can be arranged to correspond to one effective pixel or one optical black pixel (OBP). In another embodiment, if the effective pixel AP corresponds to a phase detection autofocus (PDAF) pixel, the microlens 585 can be arranged to correspond to two or more effective pixels (AP).

[0090] A light-blocking layer 590 can be disposed above the entire optical black pixel area to block incident light from passing through it. The light-blocking layer 590 can be spaced apart from the back surface of the substrate 510 and can be electrically connected to the DTI electrode 540 of the substrate 510 via a light-blocking layer extension 595 of a plug structure. The light-blocking layer 590 can be formed of a metallic material (e.g., tungsten, copper, silver, aluminum, titanium) with high light absorption and high conductivity.

[0091] As described above, the light-blocking layer 590 can be connected to the light-blocking layer extension 595 of the plug structure. The light-blocking layer 590 can be... Figure 1The bias generator 180 receives the bias voltage and can send the bias voltage to the DTI electrode extension 545 through the light blocking layer extension 595.

[0092] The light blocking layer 590 can be formed together with the optical grating structure 580 using only one process, so that the light blocking layer 590 can have the same height as the optical grating structure 580 and be formed of the same material as the optical grating structure 580.

[0093] Figure 6 This is an example Figure 2 or Figure 3 A cross-sectional view of an example of the second section 600 of the pixel array shown.

[0094] Reference Figure 6 The second section 600 can correspond to the pixel array 110-1 along... Figure 2 The cross section 600 is the section cut by the line B1-B1′ or B2-B2′ depicted in the pixel array 110-1. Alternatively, the second cross section 600 may correspond to the section along the pixel array 110-2. Figure 3 The cross section of line DD′ depicted in pixel array 110-2. Line B1-B1′ or B2-B2′ or line DD′ can be an imaginary line that extends from a portion of the effective pixel region 200 to the boundary between the effective pixel region 200 and the optical black pixel region 300 or 300′, passing through the contact area 310 to 340 of the optical black pixel region 300 or 300′.

[0095] The second section 600 may include a substrate 510 and a light incident region 560′.

[0096] In some implementations, the second section 600 can have the same characteristics as... Figure 5 The first section 500 shown has some characteristics different from those of the second section 600. In some implementations, the second section 600 may have the same characteristics as the first section 500. Figure 5 The structure shown in the first section 500 is similar to or the same as the structure shown. This will be discussed. Figure 5 The second section 600 shown is to illustrate the relationship with Figure 5 The first section 500 shown has different characteristics.

[0097] DTI electrode extension portion 545 (see also) Figure 5 ) and light-blocking layer extension 595 (see Figure 5 The anti-reflection layer may not be present in the light incident region 560′. In other words, the second section 600 may not include the structure for the electrical interconnect DTI electrode 540 and the light blocking layer 590.

[0098] Figure 7 This is a schematic diagram illustrating an example of some regions of a pixel array.

[0099] Reference Figure 7 , Figure 1 A portion 700 of the pixel array 110 shown may include some effective pixels (APs) and some optical black pixels (OBPs) arranged around the boundary between the effective pixel region and the optical black pixel region. For ease of description and better understanding of the disclosed technology, it should be noted that... Figure 7 The effective pixels (AP) and optical black pixels (OBP) shown represent the area excluding the DTI electrode 540. Therefore, as Figure 7 As shown, the DTI electrode 540 is formed around each effective pixel AP and each optical black pixel OBP.

[0100] although Figure 5 or Figure 6 The cross-sectional view shown illustrates multiple DTI electrodes 540 arranged separately from each other, but other implementations are also possible. For example, from Figure 7 As can be seen, the DTI electrodes 540 arranged around each effective pixel AP and each optical black pixel OBP can have a mesh structure, so that the corresponding DTI electrodes 540 are connected to each other.

[0101] Therefore, the DTI electrode 540 of the optical black pixel region, which is configured to receive the bias voltage through the contact region provided in the optical black pixel region, can send the bias voltage to the DTI electrode 540 of the effective pixel region.

[0102] In some implementations, the DTI electrodes 540 disposed in the pixel array 110 can be divided into multiple mesh structures instead of just a single mesh structure. In this case, it can be achieved by, for example... Figure 2 or Figure 3 The isolated contact areas shown apply different bias voltages to the DTI electrodes of each mesh structure. Because of the characteristics of the objective module (not shown) configured to converge incident light and transmit the converged light to the pixel array 110, differences in the amount of light will occur between corresponding positions within the pixel array 110. The above method can be efficiently applied to situations where differences in the amount of dark current occur between corresponding regions of the pixel array 110.

[0103] For example, a first bias voltage with a relatively high level can be applied to some DTI electrodes in the effective pixel region that generate relatively large amounts of dark current, and a second bias voltage with a relatively low level can be applied to other DTI electrodes in the effective pixel region that generate relatively small amounts of dark current. As a result, the amount of dark current generated throughout the pixel array 110 can be equalized, making it easy to remove noise components caused by such dark current.

[0104] It is clear from the above description that some implementations of image sensing devices based on the disclosed technology have an optimal structure for reducing crosstalk between pixels.

[0105] The implementation of the disclosed technology can provide various effects that can be directly or indirectly understood through the aforementioned patent documents.

[0106] Although numerous exemplary embodiments have been described, it should be understood that modifications and enhancements to the disclosed embodiments, as well as other embodiments, can be designed based on the descriptions and / or examples in this patent document.

[0107] Cross-reference to related applications

[0108] This patent document claims priority and benefit to Korean Patent Application No. 10-2021-0148003, filed on November 1, 2021, the disclosure of which is incorporated herein by reference in its entirety as part of the disclosure of this patent document.

Claims

1. An image sensing device, the image sensing device comprising: A substrate, the substrate including a substrate surface and trenches extending from the substrate surface; A plurality of photoelectric conversion elements are formed in the substrate and are operable to convert incident light into photocharge. An electrode, the electrode being formed in the trench and receiving a bias voltage for suppressing dark current; A light-blocking layer is formed above the substrate surface of the substrate to block light from being transmitted through the light-blocking layer, and is conductive to receive the bias voltage and send the received bias voltage to the electrode; An effective pixel region, comprising a plurality of effective pixels, for generating a signal indicating the intensity of the incident light; as well as An optical black pixel region, comprising a plurality of optical black pixels, for generating a signal independent of the intensity of the incident light. The light-blocking layer is disposed above the optical black pixel area to cover the optical black pixel area. The light-blocking layer prevents light from entering the photoelectric conversion element in the optical black pixel region. The bias voltage is transmitted to the electrode through the light-blocking layer at the contact area, wherein the light-blocking layer is electrically connected to the electrode at the contact area but not electrically connected to the electrode outside the contact area. The electrodes are divided into multiple electrically isolated mesh structures, and The bias voltage includes different bias voltages applied to the plurality of mesh structures to compensate for the difference in dark current between regions of the pixel array, including the effective pixel region and the optical black pixel region.

2. The image sensing device according to claim 1, further comprising: An anti-reflective layer is disposed between the substrate and the light-blocking layer; The anti-reflective layer includes: An electrode extension portion extends from the electrode toward the light-blocking layer; and A light-blocking layer extension portion extends from the light-blocking layer toward the electrode extension portion.

3. The image sensing device according to claim 2, wherein, The electrode extension and the light-blocking layer extension are in contact with each other in the anti-reflective layer.

4. The image sensing device according to claim 2, wherein, The electrode extension has a wider width than each pixel disposed in the substrate.

5. The image sensing device according to claim 4, wherein, The light-blocking layer extension has a smaller width than the electrode extension.

6. The image sensing device according to claim 2, wherein, The light-blocking layer extension is a branch extending from the light-blocking layer.

7. The image sensing device according to claim 2, wherein, The electrode extension portion is a branch extending from the electrode.

8. The image sensing device according to claim 1, wherein, The light-blocking layer comprises tungsten.

9. The image sensing device according to claim 1, wherein, The bias voltage is a negative voltage.

10. The image sensing device according to claim 1, wherein, Each of the effective pixel and the optical black pixel includes one of the photoelectric conversion elements.

11. The image sensing device according to claim 10, wherein, The optical black pixel region is configured to surround the effective pixel region, and The light-blocking layer is disposed in the optical black pixel region.

12. The image sensing device according to claim 10, wherein, The optical black pixel region includes: A first contact area is disposed on the lateral side of the effective pixel area; and The second contact area is located above or below the effective pixel area. Each of the first contact area and the second contact area includes a region where the light-blocking layer and the electrode are electrically connected to each other. in, The first contact area has a shorter length than the lateral side of the effective pixel area, and The second contact area has a shorter length than the upper or lower side of the effective pixel area.

13. The image sensing device according to claim 10, wherein, The optical black pixel region includes: A third contact area, wherein the third contact area is disposed on the lateral side of the effective pixel area; and The fourth contact area is located above or below the effective pixel area. Each of the third contact region and the fourth contact region includes a region where the light-blocking layer and the electrode are electrically connected to each other. in, The third contact area has a length that is longer than the lateral side of the effective pixel area, and The fourth contact area has a length that is longer than the upper or lower side of the effective pixel area.

14. The image sensing device according to claim 10, wherein, The electrodes are configured to surround each of the effective pixels and each of the optical black pixels. The electrodes surrounding each effective pixel and the electrodes surrounding each optical black pixel are arranged in a mesh structure.

15. An image sensing device, the image sensing device comprising: A pixel array comprising an effective pixel region and an optical black pixel region, the effective pixel region comprising a plurality of effective pixels that receive incident light and generate a signal indicating the intensity of the received incident light, the optical black pixel region comprising a plurality of optical black pixels, the plurality of optical black pixels comprising a light blocking layer to block light from entering a photoelectric conversion element in the optical black pixel region and to generate a signal independent of the intensity of the incident light received by the optical black pixels; An electrode is configured to include a vertically extending portion disposed between adjacent pixels of an effective pixel and an optical black pixel, and to receive a bias voltage for suppressing dark current generated in at least one of the effective pixel region or the optical black pixel region. as well as A bias generator that generates the bias voltage. The light-blocking layer in the optical black pixel region is conductive to receive the bias voltage from the bias generator and send the received bias voltage to the electrode. The light-blocking layer is disposed above the optical black pixel area to cover the optical black pixel area. The bias voltage is transmitted to the electrode through the light-blocking layer at the contact region, wherein the light-blocking layer is electrically connected to the electrode at the contact region but not electrically connected to the electrode at the contact region. The electrodes are divided into multiple electrically isolated mesh structures, and The bias voltage includes different bias voltages applied to the plurality of mesh structures to compensate for differences in dark current between regions comprising the pixel array.

16. The image sensing device according to claim 15, wherein, The electrode includes a horizontally extending portion disposed between at least one of the optical black pixels and the light-blocking layer disposed above the at least one of the optical black pixels.

17. The image sensing device according to claim 16, further comprising a light-blocking layer extension portion disposed between the light-blocking layer and the horizontal extension portion of the electrode.

18. The image sensing device according to claim 17, further comprising an anti-reflective layer disposed above the effective pixel region and the optical black pixel region and below the light blocking layer.

19. The image sensing device according to claim 18, wherein, The light-blocking layer extension and the horizontal extension of the electrode are disposed in the anti-reflective layer.

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