Image sensing device

Abstract

An image sensing device includes a photoelectric conversion region that generates photoelectric charges corresponding to incident light, a photoelectric gate region that overlaps the photoelectric conversion region and causes the photoelectric charges generated in the photoelectric conversion region to be collected in the photoelectric conversion region, and a transfer gate that is disposed adjacent to the photoelectric gate region in a first direction and transfers the photoelectric charges collected in the photoelectric conversion region to a floating diffusion region. The photoelectric gate region includes a first photoelectric gate that extends in a second direction for a length longer than a length in the second direction in which the photoelectric conversion region extends, and a second photoelectric gate that extends in the second direction for a length shorter than the length in the second direction in which the photoelectric conversion region extends. The first photoelectric gate includes a recessed region that is formed in contact with a side surface of the photoelectric conversion region and extends perpendicularly from one surface of a substrate in which an area in which the photoelectric conversion region is located.

Description

Technical Field

[0001] The technologies and implementations disclosed in this patent document generally relate to image sensing devices. Background Technology

[0002] Image sensing devices are devices that capture optical images by converting light into electrical signals using photosensitive semiconductor materials that react to light. With the development of the automotive, medical, computer, and communications industries, the demand for high-performance image sensing devices is 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. Compared to CMOS image sensing devices, CCD image sensing devices offer better image quality, but 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 low-cost production of miniaturized image sensing devices. 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 image sensing devices capable of improving the transmission efficiency of photocharge generated by incident light.

[0005] According to an embodiment of the disclosed technology, an image sensing device may include: a substrate having two opposing surfaces; a photoelectric conversion region located in the substrate and configured to generate photocharge in response to incident light; a photoelectric grating region configured to overlap with the photoelectric conversion region and configured to collect the photocharge generated in the photoelectric conversion region; and a transmission grating disposed adjacent to the photoelectric grating region in a first direction and configured to transmit the photocharge collected in the photoelectric conversion region to a floating diffusion region, wherein the photoelectric grating region includes: a first photoelectric grating having a length extending in a second direction and longer than the length of the photoelectric conversion region extending in the second direction; and a second photoelectric grating having a length extending in the second direction and shorter than the length of the photoelectric conversion region extending in the second direction, wherein the first photoelectric grating includes a recessed region that contacts a side surface of the photoelectric conversion region and extends vertically from a surface of the substrate that contacts or is positioned close to the photoelectric conversion region.

[0006] In some implementations, the first photoelectric grating is disposed between the second photoelectric grating and the transmission grating, and the first photoelectric grating and the second photoelectric grating are in contact with each other.

[0007] In some implementations, the image sensing device may further include a trench region formed around the photoelectric conversion region, wherein a recessed region is disposed in the trench region.

[0008] In some implementations, the trench region has an etched portion, and the recessed region is located within the etched portion of the trench region.

[0009] In some implementations, the transmission gate is configured to receive a transmission control signal and, based on the transmission control signal, move photocharge from the photoelectric conversion region to the floating diffusion region.

[0010] In some implementations, the transmission gate overlaps with the photoelectric conversion region and the floating diffusion region.

[0011] In some implementations, the first photoelectric grating is connected to a first photoelectric grating contact; and the second photoelectric grating is connected to a second photoelectric grating contact.

[0012] In some implementations, the first photoelectric grating contact is closer to the photoelectric conversion region than the second photoelectric grating contact.

[0013] In some implementations, a first photogate contact is connected to a first signal line; and a second photogate contact is connected to a second signal line, wherein a first photogate control signal applied to the first signal line and a second photogate control signal applied to the second signal line are activated at different times.

[0014] In some implementations, when the first photograting control signal has an activation level, the first collection region is disposed in the photoelectric conversion region; and when the second photograting control signal has an activation level, the second collection region is disposed in the photoelectric conversion region, wherein the length of the first collection region extending in the second direction is greater than the length of the second collection region extending in the second direction.

[0015] In some implementations, the second collection region extends a longer length in the first direction than the first collection region extends in the first direction.

[0016] In some implementations, the first photogate contact and the second photogate contact are connected to a signal line.

[0017] In some implementations, the floating diffusion region is connected to a readout circuit, which includes at least one of a drive transistor, a reset transistor, and a select transistor.

[0018] In some implementations, the length of the floating diffusion region extending in the second direction is shorter than the length of the transmission gate extending in the second direction.

[0019] According to an embodiment of the disclosed technology, an image sensing device may include: a substrate; a photoelectric conversion region located in the substrate and having a thickness extending from the surface of the substrate, and configured to generate photocharge in response to light incident on the substrate; a first photogate region disposed above the photoelectric conversion region and configured to receive a first control signal to collect photocharge in a first portion of the photoelectric conversion region; a second photogate region disposed above the photoelectric conversion region and configured to receive a second control signal to collect photocharge in a second portion of the photoelectric conversion region; and a trench region disposed on the side of the photoelectric conversion region and having a thickness greater than the thickness of the photoelectric conversion region, wherein a portion of the first photogate region is disposed in the trench region.

[0020] In some implementations, the first photogate region extends in one direction at a length longer than the photoelectric conversion region extends in the same direction.

[0021] In some implementations, the length of the second photogate region extending in one direction is shorter than the length of the photoelectric conversion region extending in that same direction.

[0022] In some implementations, the image sensing device may further include: a floating diffusion region configured to contact the surface of a substrate; and a transfer gate disposed above the substrate to transfer photocharge collected in the photoelectric conversion region to the floating diffusion region.

[0023] In some implementations, the image sensing device may further include: a first photograting contact disposed on a first photograting region and configured to provide a first control signal to the first photograting region; and a second photograting contact disposed on a second photograting region and configured to provide a second control signal to the second photograting region.

[0024] In some implementations, the first photogate contact is positioned closer to the photoelectric conversion region than the second photogate contact.

[0025] It should be understood that both the foregoing general description of the disclosed technology and the following detailed description are exemplary and explanatory, and are intended to provide a further explanation of the claimed disclosure. Attached Figure Description

[0026] The above and other features and advantages of the disclosed technology will become apparent from the following detailed description taken in conjunction with the accompanying drawings.

[0027] Figure 1 This is a schematic diagram illustrating an example of a local structure of a unit pixel used in an image sensing device according to an exemplary embodiment of the disclosed technology.

[0028] Figure 2This is a cross-sectional view illustrating an example of a unit pixel taken along a first cutting line according to an exemplary embodiment of the disclosed technology.

[0029] Figure 3 This is a cross-sectional view illustrating an example of a unit pixel taken along a second cutting line according to an exemplary embodiment of the disclosed technology.

[0030] Figure 4 This is a cross-sectional view illustrating an example of a unit pixel cut along a third cutting line according to an exemplary embodiment of the disclosed technology.

[0031] Figure 5 This is a cross-sectional view illustrating an example of a unit pixel cut along a first cutting line according to another embodiment of the disclosed technology.

[0032] Figure 6 This is a cross-sectional view illustrating an example of a unit pixel cut along a first cutting line according to another embodiment of the disclosed technology.

[0033] Figure 7 This is a cross-sectional view illustrating an example of a unit pixel cut along a first cutting line according to another embodiment of the disclosed technology.

[0034] Figure 8 This is a timing diagram illustrating the operation time points of the transmission control signal and the photograting control signal according to an exemplary embodiment of the disclosed technology.

[0035] Figure 9 This is a timing diagram illustrating the operation time points of the transmission control signal, the first photograting control signal, and the second photograting control signal according to another embodiment of the disclosed technology.

[0036] Figures 10A to 10E This is a diagram illustrating a method for forming a unit pixel according to an exemplary embodiment of the disclosed technology.

[0037] Figure 11 This is a schematic diagram illustrating an example of a partial structure of an image sensing device according to another embodiment of the disclosed technology. Detailed Implementation

[0038] This patent document provides implementations and examples of image sensing device designs that can be used in configurations that substantially solve one or more technical or engineering problems and mitigate some limitations or drawbacks encountered in other image sensing device designs. Some implementations of the disclosed technology provide image sensing devices capable of improving the transmission efficiency of photocharge generated by incident light. Some implementations of the disclosed technology are able to adjust the photocharge transmission efficiency according to the shape of the photograting included in a unit pixel.

[0039] Some embodiments will now be described in detail with reference to the accompanying drawings, which illustrate examples of some embodiments. Wherever possible, the same reference numerals will be used throughout the drawings to refer to the same or similar components. In the following description, detailed descriptions of relevant known configurations or functions incorporated herein will be omitted to avoid obscuring the subject matter. However, it should be understood that the disclosed techniques are not limited to the specific embodiments, but include various modifications, equivalents, and / or substitutions of the embodiments.

[0040] Figure 1 This is a schematic diagram illustrating an example of a local structure 10 of a unit pixel used in an image sensing device according to an exemplary embodiment of the disclosed technology.

[0041] An image sensing device may include a controller for controlling constituent elements (e.g., a pixel array and pixel transistors included in the pixel array), a sensing unit for sensing incident light and outputting pixel signals, and a processor for generating digital signals by processing the pixel signals.

[0042] In some implementations, the sensing unit may include a pixel array in which multiple unit pixels are arranged in a matrix. The controller may include a line driver, timing controller, etc., for each pixel array, capable of applying control signals to the pixel array. The processor may include, for example, a correlated dual sampler (CDS), an analog-to-digital converter (ADC), etc.

[0043] Reference Figure 1 Unit pixels can be formed in the substrate 100. In some implementations, unit pixels can be included in a pixel array and can be the smallest repeating unit in the pixel array. Therefore, the pixel array can include multiple unit pixels in rows and columns.

[0044] A unit pixel may include a photoelectric conversion area 110, a photoelectric grating area 120, a transmission grating 130, a floating diffusion area 140, a trench area 150, and a readout circuit 600.

[0045] Additionally, a unit pixel may include photogate contacts 221 and 222 connected to photogate region 120, a transmission gate contact 230 connected to transmission gate 130, and a floating diffusion contact 240 connected to floating diffusion region 140.

[0046] The photoelectric conversion region 110 may be formed in the substrate 100 to contact or be close to the top surface of the substrate 100. The substrate 100 may include, for example, a silicon substrate doped with impurities, an epitaxial layer, or a stacked structure of a silicon substrate and an epitaxial layer.

[0047] The photoelectric conversion region 110 can generate photocharge corresponding to incident light. The photoelectric conversion region 110 may include a photodiode, a phototransistor, a pinned photodiode, and / or combinations thereof. The photoelectric conversion region 110 may have a suitable photosensitive structure capable of generating photocharge in response to received incident light.

[0048] A photogate region 120 may be formed above the substrate 100 to overlap perpendicularly with the photoelectric conversion region 110. The photogate region 120 may include a first photogate 121 and a second photogate 122 that are adjacent to each other in a first direction (X direction). An insulating layer may be formed between the photogate region 120 and the substrate 100. The insulating layer may include, for example, a silicon oxide layer.

[0049] The first photoelectric grating 121 can be formed as a rectangle whose length extending in the second direction (Y direction) is longer than its length extending in the first direction (X direction). Similarly, the second photoelectric grating 122 can also be formed as a rectangle whose length extending in the first direction (X direction) is longer than its length extending in the second direction (Y direction). The photoelectric grating region 120, including the first and second photoelectric gratings 121 and 122, can be formed in a T-shape. The first and second photoelectric gratings 121 and 122 can be formed to be in contact with each other.

[0050] The photogate region 120 may include polycrystalline silicon or transparent conductive oxide (TCO). For example, the photogate region 120 may include transparent conductive oxide (TCO), such as indium tin oxide (ITO), indium zinc oxide (IZO), zinc oxide (ZnO), titanium dioxide (TiO2), or combinations thereof.

[0051] The transmission gate 130 can be formed to overlap with the photoelectric conversion region 110 and the floating diffusion region 140. The transmission gate 130 can be disposed adjacent to the photoelectric gate region 120 in the first direction on the upper part of the substrate 100.

[0052] An insulating layer may be formed between the transfer gate 130 and the substrate 100. The insulating layer may include, for example, silicon oxide.

[0053] The transfer gate 130 can be controlled by a transfer control signal applied to it, and can transfer the charge generated by the photoelectric conversion region 110 to the floating diffusion region 140. The transfer gate 130 may include a conductor. For example, the conductor may include metal or polysilicon.

[0054] For example, a transmission control signal can be transmitted from a controller included in the image sensing device to the transmission gate 130.

[0055] The floating diffusion region 140 can be formed in the substrate 100 to contact or be close to the top surface of the substrate 100. The floating diffusion region 140 can accumulate photocharge that has been transferred by the transfer gate 130 from the photoelectric conversion region 110.

[0056] The substrate 100 has two surfaces located on opposite sides of the substrate 100, namely, a top surface and a bottom surface. In implementation, the device can be used in a back-illuminated mode to receive incident light from the bottom surface of the substrate 100, such that the incident light passes through the substrate 100 toward the top surface to enter the photoelectric conversion region 110, where photocharge is generated and transmitted via a transfer gate 130 to a floating diffusion region 140 near the top surface of the substrate 100. The floating diffusion region 140 may include N-type impurities (N+ impurities). The floating diffusion region 140 may have a higher doping concentration than the semiconductor substrate 100.

[0057] The floating diffusion region 140 can be connected to the readout circuit 600 via the floating diffusion contact 240.

[0058] The trench 150 can be formed around the photoelectric conversion region 110 and can be formed to contact the top surface of the substrate 100.

[0059] In some implementations, trench 150 may include an insulating material. Trench 150 may allow electrical isolation between a photoelectric conversion region 110 in a particular unit pixel and a photoelectric conversion region 110 included in another unit pixel adjacent to that particular unit pixel.

[0060] The readout circuit 600 can output a pixel signal corresponding to the charge accumulated in the floating diffusion region 140.

[0061] The readout circuit 600 may include a reset transistor RX, a drive transistor DX, and a select transistor SX. A power supply voltage node (VDD) may be connected to one side of the reset transistor RX, and a floating diffusion region 140 may be connected to the other side of the reset transistor RX. The floating diffusion region 140 may be initialized by applying a reset signal RS to the reset transistor RX.

[0062] The gate of the driving transistor DX can be connected to the floating diffusion region 140. Furthermore, one side of the driving transistor DX can be connected to the power supply voltage node (VDD), and the other side of the driving transistor DX can be connected to the select transistor SX.

[0063] The driving transistor DX can generate and output a pixel signal corresponding to the voltage generated by the charge accumulated in the floating diffusion region 140. The selected transistor SX can be an output node, with one side connected to the driving transistor DX and the other side outputting the pixel signal.

[0064] The select transistor SX can output a signal from the drive transistor DX as a pixel signal in response to a select signal SS applied to its gate.

[0065] The photograting contacts 221 and 222 can contact the photograting region 120 and electrically connect the photograting region 120 to a signal line, so that a photograting control signal can be applied to the photograting region 120. In some implementations, the photograting control signal can be applied to the photograting region 120 through a controller included in the image sensing device.

[0066] In some implementations, photogate contacts 221 and 222 may include a first photogate contact 221 connected to the first photogate 121 and a second photogate contact 222 connected to the second photogate 122. Each of the first photogate contact 221 and the second photogate contact 222 can transmit a photogate control signal to the corresponding photogate.

[0067] For example, the first photoelectric grating contact 221 can transmit the first photoelectric grating control signal to the first photoelectric grating 121, while the second photoelectric grating contact 222 can transmit the second photoelectric grating control signal to the second photoelectric grating 122.

[0068] In another embodiment, the first photogate contact 221 and the second photogate contact 222 can be connected to a signal line, and the same photogate control signal can be applied to the first photogate 121 and the second photogate 122 through the first photogate contact 221 and the second photogate contact 222.

[0069] Each of the photograting contacts 221 and 222 may include a conductive material. For example, the conductive material may include polycrystalline silicon or a metal.

[0070] The transmission gate contact 230 can be connected to the transmission gate 130 and can transmit transmission control signals to the transmission gate 130. The floating diffusion contact 240 can be connected to the floating diffusion region and can transmit a signal corresponding to the charge accumulated in the floating diffusion region 140 to the readout circuit 600. The transmission gate contact 230 and the floating diffusion contact 240 can be formed of or comprise the same material as the photogate contacts 221 and 222.

[0071] In some implementations, the transmission control signal can be applied to the transmission gate contact 230 by a controller included in the image sensing device.

[0072] Figure 2 This is a cross-sectional view 20 illustrating an example of a unit pixel cut along the first cutting line AA′ according to an exemplary embodiment of the disclosed technology.

[0073] Figure 2 The vertical structure of substrate 100, photoelectric conversion region 110, first photogate 121, second photogate 122, transmission gate 130, floating diffusion region 140, photogate contacts 221 and 222, transmission gate contact 230, and floating diffusion contact 240 is illustrated.

[0074] like Figure 2 As shown in the example, the photoelectric conversion region 110 may be located in the substrate 100 to contact or be close to the top surface, and is configured to include a first charge collection region 111 and a second charge collection region 112.

[0075] In some implementations, in response to a control signal PGS applied to the photogate region 120, the photogate region 120 can move the charge generated by the photoconversion region 110 within the photoconversion region 110. For example, the photogate region 120 can move the photocharge generated by the photoconversion region 110 to collect it in a first charge collection region 111 and a second charge collection region 112.

[0076] For example, the photograting control signal PGS can be a signal with an activation voltage or a deactivation voltage. When the photograting control signal PGS with an activation voltage is applied to the photograting region 120, the photocharge generated in the photoelectric conversion region 110 can be moved to a specific area within the photoelectric conversion region 110 through the electric field generated by the photograting control signal PGS.

[0077] The photograting control signal PGS can be applied to the photograting region 120 through the photograting contacts 221 and 222.

[0078] When a transmission control signal TS with an activation voltage is applied to the transmission gate 130, the photocharge that has moved to the first charge collection region 111 can move from the first charge collection region 111 to the floating diffusion region 140.

[0079] The transmission control signal TS can be transmitted from the signal line to the transmission gate 130 through the transmission gate contact 230.

[0080] Figure 3 This is a cross-sectional view 30 illustrating an example of a unit pixel cut along the second cutting line BB′ according to an exemplary embodiment of the disclosed technology.

[0081] Reference Figure 3 Examples include a substrate 100, a photoelectric conversion region 110 formed on the substrate 100, a trench 150, a first photoelectric grating 121 formed to overlap with the photoelectric conversion region 110, and a first photoelectric grating contact 221 connected to the first photoelectric grating 121.

[0082] The first photogate 121 may include a horizontal region 121L and a recessed region 121V. The horizontal region 121L may be in contact with a surface of the substrate 100, and the length of the horizontal region 121L extending in the second direction (Y direction) may be longer than the length of the photoelectric conversion region 110 extending in the second direction.

[0083] When a photograting control signal is applied to the first photograting 121, an electric field can be formed in the photoelectric conversion region 110 located below the horizontal region 121L. At this time, photocharge can be collected in the first charge collection region 111 by the electric field. The shape of the first charge collection region 111 can be determined according to the shape of the first photograting 121 and the photograting control signal applied to the first photograting 121.

[0084] The trench region 150 can allow the photoelectric conversion region 110 to be electrically / physically separated from another photoelectric conversion region 110 included in another unit pixel adjacent to the photoelectric conversion region 110.

[0085] The trench region 150 can be formed to be deeper than the photoelectric conversion region 110 relative to a surface of the substrate 100. In this case, a surface of the substrate 100 can be a surface facing the light receiving surface or a surface opposite to the light receiving surface.

[0086] Because the trench region 150 is formed to be deeper than the photoelectric conversion region 110 relative to the surface of the substrate 100, the movement of photocharge between adjacent unit pixels can be restricted. Since this movement of photocharge between adjacent unit pixels is restricted, noise in the pixel signal can be reduced.

[0087] The recessed region 121V can be formed in the trench 150. The recessed region 121V can extend from one surface of the substrate 100 in a direction perpendicular to the other surface of the substrate 100 (e.g., in a direction perpendicular to the X or Y direction).

[0088] The recessed region 121V can contact the horizontal region 121L. In addition, the recessed region 121V can be formed to extend from the horizontal region 121L toward the interior of the groove 150.

[0089] The recessed region 121V can contact the side surface of the photoelectric conversion region 110. When the photoelectric grating control signal is applied to the first photoelectric grating 121, an electric field can be formed on the side surface of the photoelectric conversion region 110 through the recessed region 121V.

[0090] The charge generated in the photoelectric conversion region 110 can be easily collected in the region adjacent to the recessed region 121V by an electric field. When the recessed region 121V is formed, the charge is easily collected in the first charge collection region 111 and the amount of charge collected can be increased.

[0091] The recessed region 121V and the horizontal region 121L can be physically and electrically interconnected. In some implementations, the recessed region 121V and the horizontal region 121L can comprise the same conductive material (e.g., metal or polysilicon).

[0092] The first photogate 121 can be formed by interconnecting the recessed region 121V and the horizontal region 121L. The first photogate 121 can be separated from the photoelectric conversion region 110 through an insulating layer.

[0093] Figure 4 This is a cross-sectional view 40 illustrating an example of a unit pixel cut along the third cutting line CC′ according to an exemplary embodiment of the disclosed technology.

[0094] Reference Figure 4 Examples include a substrate, a photoelectric conversion region 110 formed on the substrate 100, a trench 150, a second photoelectric grating 122 formed to overlap with the photoelectric conversion region 110, and a second photoelectric grating contact 222 connected to the second photoelectric grating 122.

[0095] The second photogate 122 can contact one surface of the substrate 100, and the length of the second photogate 122 extending in the second direction (Y direction) can be shorter than the length of the photoelectric conversion region 110 extending in the second direction.

[0096] When a photograting control signal is applied to the second photograting 122, an electric field can be formed in the photoelectric conversion region 110 located below the second photograting 122. At this time, photocharge can be collected in the second charge collection region 112 through the electric field.

[0097] In some implementations, the length of the second charge collection region 112 extending in the second direction (Y direction) can be equal to the length of the second photoelectric grating 122 extending in the second direction. The shape of the second charge collection region 112 can be determined based on the shape of the second photoelectric grating 122 and the photoelectric grating control signal applied to the second photoelectric grating 122.

[0098] Figure 5 This is a cross-sectional view 50 illustrating an example of a unit pixel cut along the first cutting line AA′ according to another embodiment of the disclosed technology.

[0099] like Figure 5 The implementation shown has the same Figure 2 The structure is basically the same as that of [other structures]. Therefore, for ease of description, this redundant description of the structure will be omitted here. The description here will focus on [other structures]. Figure 2 The structures and features are different.

[0100] In terms of the shape of the first photograting contact 221, the cross section 50 of a unit pixel according to another embodiment of the disclosed technology may be different from the cross section 20 of a unit pixel according to one embodiment of the disclosed technology.

[0101] The first photoelectric grating contact 221 can be formed to extend into the first photoelectric grating 121. Since the first photoelectric grating contact 221 extends into the first photoelectric grating 121, the first photoelectric grating contact 221 can be closer to the photoelectric conversion region than the second photoelectric grating contact 222.

[0102] Compared to the area where the second photogate contact 222 is connected to the second photogate 122, the area where the first photogate contact 221 is connected to the first photogate 121 can be over-etched more. Therefore, the first photogate contact 221 can be positioned closer to the photoelectric conversion region 110 than the second photogate contact 222.

[0103] When the first photoelectric grating contact 221 is positioned closer to the photoelectric conversion region 110 than the second photoelectric grating contact 222, the electric field generated by the first photoelectric grating contact 221 can have a greater impact on the photoelectric conversion region 110 than the electric field generated by the second photoelectric grating contact 222.

[0104] For example, the electric field strength applied to the first charge collection region 111 located below the first photogate 121 can be greater than the electric field strength applied to the second charge collection region 112 located below the second photogate 122.

[0105] Due to the intensity difference between the electric field applied to the first charge collection region 111 and the electric field applied to the second charge collection region 112, charge collection and transfer in the first charge collection region 111 can be faster than those in the second charge collection region 112. Furthermore, the amount of photocharge collected in the first charge collection region 111 can be greater than the amount of photocharge collected in the second charge collection region 112.

[0106] Figure 6 This is a cross-sectional view 60 illustrating an example of a unit pixel cut along the first cutting line AA′ according to another embodiment of the disclosed technology.

[0107] like Figure 6 The implementation shown has the same Figure 2 The structure is basically the same as that of [other structures]. Therefore, for ease of description, this redundant description of the structure will be omitted here. The description here will focus on [other structures]. Figure 2 The structures and features are different.

[0108] In terms of the shape of the signal lines connected to the first photograting contact 221 and the second photograting contact 222, the cross-section 60 of a unit pixel according to another embodiment of the disclosed technology may differ from the cross-section 20 of a unit pixel according to one embodiment of the disclosed technology.

[0109] The signal lines connected to the first photograting contact 221 and the signal lines connected to the second photograting contact 222 can be separated from each other. Therefore, different photograting control signals can be applied to the first photograting contact 221 and the second photograting contact 222.

[0110] In some implementations, the signal line connected to the first photogate contact 221 can be referred to as the first signal line, while the signal line connected to the second photogate contact 222 can be referred to as the second signal line.

[0111] In addition, the photograting control signal applied to the first photograting contact 221 can be called the first photograting control signal PGS1, and the photograting control signal applied to the second photograting contact 222 can be called the second photograting control signal PGS2.

[0112] The first photogate control signal PGS1 and the second photogate control signal PGS2 can have different operating time points. In some implementations, the second photogate control signal PGS2 has an activation voltage at a time point that is faster than the first photogate control signal PGS1. At the time when the second photogate control signal PGS2 transitions to a deactivation voltage, the first photogate control signal PGS1 can sequentially activate itself. Here, the activation voltage can refer to the voltage at which charge is collected and transferred in the charge collection regions 111 and 112 adjacent to photogates 121 and 122.

[0113] Since the first photograting control signal PGS1 and the second photograting control signal PGS2 have activation voltages in sequence, the photocharge generated in the photoelectric conversion region 110 can move sequentially from the second charge collection region 112 to the first charge collection region 111.

[0114] Furthermore, since the photogate control signals applied to the first photogate 121 and the second photogate 122 are separate from each other, the first photogate control signal PGS1 and the second photogate control signal PGS2 can have different activation voltages. For example, the photogate control signal with a larger activation voltage can be applied to regions requiring rapid charge collection and rapid charge transfer.

[0115] Figure 7 This is a cross-sectional view 70 illustrating an example of a unit pixel cut along the first cutting line AA′ according to another embodiment of the disclosed technology.

[0116] Compared to the cross-section 20 of a unit pixel according to one embodiment of the disclosed technology, the cross-section 70 of a unit pixel according to another embodiment of the disclosed technology may have a shape in which the first photoelectric grating contact 221 extends into the first photoelectric grating 121. As the first photoelectric grating contact 221 extends into the first photoelectric grating 121, the first photoelectric grating contact 221 may be closer to the photoelectric conversion region than the second photoelectric grating contact 222.

[0117] Furthermore, the signal lines through which the first photograting control signal PGS1 is applied to the first photograting contact 221 and the signal lines through which the second photograting control signal PGS2 is applied to the second photograting contact 222 can be separated from each other.

[0118] The first photograting contact 221 is formed closer to the photoelectric conversion region than the second photograting contact 222, and the first photograting control signal PGS1 and the second photograting control signal PGS2 are separated from each other, so that the intensity of the electric field applied to the photoelectric conversion region 110 can be controlled more precisely.

[0119] Figure 8 This is a timing diagram illustrating the operation time points of the transmission control signal and the photograting control signal according to an exemplary embodiment of the disclosed technology.

[0120] from Figure 8 As can be seen, the operating time points of the photoelectric grating control signal PGS and the transmission control signal TS are illustrated when the first photoelectric grating contact and the second photoelectric grating contact are connected to the common signal line.

[0121] The photograting control signal PGS can have an activation voltage earlier than the transmission control signal TS, and the transmission control signal TS can have an activation voltage at the point when the photograting control signal PGS changes from the activation voltage to the deactivation voltage.

[0122] At the point when the photoelectric grating control signal PGS has an activation voltage, the photocharge generated in the photoelectric conversion region can be collected at the lower end of the photoelectric grating. At the point when the photoelectric grating control signal PGS changes to a deactivation voltage and the transmission control signal TS has an activation voltage, the photocharge can be transferred from the photoelectric conversion region to the floating diffusion region.

[0123] Because the first photoelectric grating has a recessed area and the length of the first photoelectric grating extending in the second direction is longer than the length of the photoelectric conversion region extending in the second direction, the amount of charge collected in the first charge collection region located below the first photoelectric grating can be increased.

[0124] Figure 9 This is a timing diagram illustrating the operation time points of the transmission control signal, the first photograting control signal, and the second photograting control signal according to another embodiment of the disclosed technology.

[0125] Reference Figure 9 This illustrates the operating time points when the first photogate contact and the second photogate contact are connected to different signal lines, and the first photogate control signal PGS1 is applied to the first photogate contact, the second photogate control signal PGS2 is applied to the second photogate contact, and the transmission control signal TS is applied to the transmission gate contact.

[0126] The second photograting control signal PGS2 can have an activation voltage earlier than the first photograting control signal PGS1. The first photograting control signal PGS1 can have an activation voltage at the point when the second photograting control signal PGS2 changes from an activation voltage to a deactivation voltage.

[0127] In addition, the transmission control signal TS can have an activation voltage at the point when the first photograting control signal PGS1 changes from the activation voltage to the deactivation voltage.

[0128] The photocharge generated in the photoelectric conversion region at each time point with an activation voltage in the photoelectric grating control signals PGS1 and PGS2 can be collected at the lower end of the first or second photoelectric grating.

[0129] For example, at the time point when the second photograting control signal PGS2 has an activation voltage, photocharge is collected in the second charge collection region located at the lower end of the second photograting. At the time point when the second photograting control signal GPS2 changes to a deactivation voltage and the first photograting control signal PGS1 has an activation voltage, photocharge is collected in the first charge collection region.

[0130] exist Figure 9 In this implementation, the first photograting control signal PGS1 and the second photograting control signal PGS2 are activated at different time points, so the regions where photocharge is concentrated can be determined differently based on the activated signals.

[0131] For example, at the point in time when the second photograting control signal PGS2 changes to a deactivation voltage and the first photograting control signal PGS1 has an activation voltage, the amount of photocharge concentrated in the first charge collection region can be greater than the amount of photocharge concentrated in the second charge collection region.

[0132] When the amount of photocharge concentrated in the first charge collection region is large, the amount of photocharge planned to move from the photoelectric conversion region to the floating diffusion region can be increased at the time point when the photoelectric grating control signal PGS changes to the deactivation voltage and the transmission control signal TS has the activation voltage.

[0133] Therefore, when the photogate control signals applied to the first photogate and the second photogate are distinguished from each other, photocharge can be easily collected and moved.

[0134] Figures 10A to 10E This is a diagram illustrating a method for forming a unit pixel according to an exemplary embodiment of the disclosed technology.

[0135] Figure 10A An example of a process for forming a photoelectric conversion region 110 and a floating diffusion region 140 in a substrate 100 is illustrated. The photoelectric conversion region 110 and the floating diffusion region 140 can be formed on the substrate 100 by ion implantation. The photoelectric conversion region 110 and the floating diffusion region 140 may include impurity doped regions.

[0136] Figure 10B An example of a process for forming a trench region 150 in contact with the photoelectric conversion region 110 is illustrated. The trench region 150 may be formed at locations where adjacent photoelectric conversion regions 110 may be electrically / physically separated from each other.

[0137] According to one embodiment, the trench region 150 can be formed by etching the substrate 100 and doping the etched area with insulating material. According to another embodiment, the trench region 150 can be formed by stacking multiple doped regions.

[0138] Figure 10C The process of forming the etched region 121V′ in the trench region 150 is illustrated.

[0139] The etched region 121V′ can be formed by an etching process, and the depth of the etched region 121V′ can be less than the depth of the trench region 150.

[0140] Figure 10D The process for forming the transmission gate 130 and the photogate region 120 is illustrated.

[0141] The transmission gate 130 and the photogate region 120 may be formed above one surface of the substrate 100, and an insulating layer may be formed between the transmission gate 130 and the substrate 100. Similarly, an insulating layer may be formed between the photogate region 120 and the substrate 100.

[0142] Due to the insulating layer, the transmission gate 130 and the floating diffusion region 140 can be separated from each other, and the transmission gate 130 and the photoelectric conversion region 110 can be separated from each other. Similarly, the photoelectric gate region 120 and the photoelectric conversion region 110 can be separated from each other through the insulating layer.

[0143] The transmission gate 130 may be formed to overlap with the floating diffusion region 140 and the photoelectric conversion region 110. The photoelectric gate region 120 may be formed to overlap with the photoelectric conversion region 110.

[0144] The first photogate 121 included in the photogate region 120 may include those formed in Figure 10CThe recessed region in the etched area 121V′. Since the first photogate 121 includes a recessed region, charge can be easily collected in the lower part of the first photogate 121.

[0145] Furthermore, the first photoelectric grating 121 extending in the second direction (Y direction) may be longer than the photoelectric conversion region 110 extending in the second direction. The second photoelectric grating 122 extending in the second direction (Y direction) may be shorter than the photoelectric conversion region 110 extending in the second direction.

[0146] The first photoelectric grating 121 can be formed as a rectangle whose length extending in the second direction (Y direction) is longer than its length extending in the first direction (X direction). The second photoelectric grating 122 can be formed as a rectangle whose length extending in the first direction is longer than its length extending in the second direction.

[0147] Therefore, the photograting including the first photograting 121 and the second photograting 122 can be formed in a T-shape.

[0148] The photogate region 120 can be formed by a deposition process and may include metal, polysilicon, transparent conductive oxide or a combination thereof.

[0149] Figure 10E The process for forming the floating diffusion region contact 240, the transmission gate contact 230, and the photoelectric gate contacts 221 and 222 is illustrated.

[0150] Reference Figure 10E The regions to be formed for contacts 221, 222, 230, and 240 can be formed by an etching process, and conductive material can be deposited in these regions to form contacts 221, 222, 230, and 240. For example, the contacts may include metal, polysilicon, or a combination thereof.

[0151] Figure 11 This is a schematic diagram of an example of a partial structure 10′ of an image sensing device according to another embodiment of the disclosed technology.

[0152] Reference Figure 11A unit pixel may include photoelectric conversion area A (110a), photoelectric conversion area B (110b), photoelectric grating A (120a), photoelectric grating B (120b), transmission grating A (130a), transmission grating B (130b), floating diffusion area A (140a), floating diffusion area B (140b), photoelectric grating contact A (221a, 222a), photoelectric grating contact B (221b, 222b), transmission grating contact A (230a), transmission grating contact B (230b), floating diffusion contact A (240a), floating diffusion contact B (240b), readout circuit A (600a) and readout circuit B (600b).

[0153] Photoelectric conversion region A (110a) and photoelectric conversion region B (110b) can be formed in substrate 100 and can generate photocharge corresponding to incident light.

[0154] The photoelectric conversion region A (110a) and the photoelectric conversion region B (110b) can be arranged to face each other in the substrate 100.

[0155] The photoelectric grating A (120a) can be formed to overlap with the photoelectric conversion region A (110a).

[0156] The photoelectric conversion regions 110a and 110b included in the unit pixel 10′ can be configured to face each other.

[0157] The photocharge generated in the photoelectric conversion region A (110a) can be transferred to the floating diffusion region A (140a) by the photogate A (120a) and the transmission gate A (130a). The photocharge accumulated in the floating diffusion region A (140a) can be connected to the readout circuit A (600a) through the floating diffusion contact A (240a).

[0158] In addition, the photocharge generated in the photoelectric conversion region B (110b) can be transferred to the floating diffusion region B (140b) through the photogate B (120b) and the transmission gate B (130b). The photocharge accumulated in the floating diffusion region B (140b) can be connected to the readout circuit B (600b) through the floating diffusion contact B (240b).

[0159] Readout circuit A (600a) can output a pixel signal A corresponding to the photocharge accumulated in floating diffusion region A (140a). Additionally, readout circuit B (600b) can output a pixel signal B corresponding to the photocharge accumulated in floating diffusion region B (140b).

[0160] Each of the readout circuits 600a and 600b may include a reset transistor, a drive transistor, and a select transistor.

[0161] A photogate A (120a) can be formed on the substrate 100 to vertically overlap the photoelectric conversion region A (110a). A photogate B (120b) can be formed on the substrate 100 to vertically overlap the photoelectric conversion region B (110b).

[0162] exist Figure 11 In the unit pixel 10′ shown, activation voltages can be periodically applied to photogate A (120a) and photogate B (120b). Additionally, activation voltages can be periodically applied to transmission gate A (130a) and transmission gate B (130b).

[0163] Therefore, pixel signals can be periodically output from readout circuit A (600a) and readout circuit B (600b). According to the disclosed embodiment, the time delay of incident light is measured by comparing pixel signal A output from readout circuit A (600a) with pixel signal B output from readout circuit B (600b), and the distance to the target object to be sensed can be calculated based on the measured time delay.

[0164] It is evident from the above description that some implementations of the disclosed technology of image sensing devices can improve the transmission efficiency of photocharge generated by incident light.

[0165] Some implementations of the disclosed technology can adjust the photoelectric charge transfer efficiency according to the shape of the photograting included in a unit pixel.

[0166] The implementation of the disclosed technology can provide various effects that can be directly or indirectly understood through the aforementioned patent documents.

[0167] Those skilled in the art will understand that the disclosed technology can be implemented in other specific ways besides those described herein. Furthermore, claims not explicitly stated in the appended claims may be proposed as a combination of embodiments through subsequent amendments after filing the application or included as new claims.

[0168] While many exemplary embodiments have been described, it should be understood that modifications and / or enhancements to the disclosed embodiments and other embodiments can be designed based on the descriptions and / or examples in this patent document.

[0169] Cross-references to related applications

[0170] This patent document claims priority and benefit to Korean Patent Application No. 10-2021-0127205, filed on September 27, 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 comprising: a substrate having two opposite surfaces; a photoelectric conversion region located in the substrate and generating photocharge corresponding to incident light; a photoelectric gate region overlapping the photoelectric conversion region and causing photocharge generated in the photoelectric conversion region to be collected in the photoelectric conversion region; and a transfer gate disposed adjacent to the photoelectric gate region in a first direction and transferring photocharge collected in the photoelectric conversion region to a floating diffusion region, wherein the photoelectric gate region includes: a first photoelectric gate having a length extending in a second direction and longer than a length in the second direction in which the photoelectric conversion region extends; and a second photoelectric gate having a length extending in the second direction and shorter than the length in the second direction in which the photoelectric conversion region extends, wherein the first photoelectric gate includes: a recessed region contacting a side surface of the photoelectric conversion region and extending perpendicularly from one surface of the substrate contacting or positioned close to the photoelectric conversion region.

2. The image sensing device according to claim 1, wherein the first photoelectric gate is disposed between the second photoelectric gate and the transfer gate, and the first photoelectric gate and the second photoelectric gate contact each other.

3. The image sensing device according to claim 1, further comprising: a trench region formed so as to surround the photoelectric conversion region, wherein the recessed region is disposed in the trench region.

4. The image sensing device according to claim 3, wherein the trench region has an etched portion, and the recessed region is disposed in the etched portion of the trench region.

5. The image sensing device according to claim 1, wherein the transfer gate receives a transfer control signal and causes the photocharge to move from the photoelectric conversion region to the floating diffusion region based on the transfer control signal.

6. The image sensing device according to claim 1, wherein the transfer gate overlaps the photoelectric conversion region and the floating diffusion region.

7. The image sensing device according to claim 1, wherein the first photoelectric gate is connected to a first photoelectric gate contact, and the second photoelectric gate is connected to a second photoelectric gate contact.

8. The image sensing device according to claim 7, wherein the first photoelectric gate contact is positioned closer to the photoelectric conversion region than the second photoelectric gate contact.

9. The image sensing device according to claim 7, wherein the first photoelectric gate contact is connected to a first signal line, and the second photoelectric gate contact is connected to a second signal line, wherein a first photoelectric gate control signal applied to the first signal line and a second photoelectric gate control signal applied to the second signal line are activated at different points in time.

10. The image sensing device according to claim 9, wherein when the first photoelectric gate control signal has an activation level, a first collection region is disposed in the photoelectric conversion region, and when the second photoelectric gate control signal has the activation level, a second collection region is disposed in the photoelectric conversion region. When the second photograting control signal has an activation level, the second collection area is disposed in the photoelectric conversion area. Wherein, the length of the first collection area extending in the second direction is longer than the length of the second collection area extending in the second direction.

11. The image sensing device according to claim 10, wherein, The second collection area extends longer in the first direction than the first collection area extends in the first direction.

12. The image sensing device according to claim 7, wherein, The first photoelectric grating contact and the second photoelectric grating contact are connected to a signal line.

13. The image sensing device according to claim 1, wherein, The floating diffusion region is connected to the readout circuit. The readout circuit includes at least one of a drive transistor, a reset transistor, and a select transistor.

14. The image sensing device according to claim 1, wherein, The length of the floating diffusion region extending in the second direction is shorter than the length of the transmission gate extending in the second direction.

15. An image sensing device, the image sensing device comprising: substrate; A photoelectric conversion region is located in the substrate and has a thickness extending from the surface of the substrate, and generates photocharge in response to light incident on the substrate; A first photoelectric grating region is disposed above the photoelectric conversion region and receives a first control signal to collect photocharge in a first part of the photoelectric conversion region; A second photoelectric grating region is disposed above the photoelectric conversion region and receives a second control signal to collect photocharge in a second part of the photoelectric conversion region; as well as A trench region is provided on the side of the photoelectric conversion region and has a thickness greater than the thickness of the photoelectric conversion region. A portion of the first photograting region is disposed within the trench region.

16. The image sensing device according to claim 15, wherein The length of the first photograting region extending in one direction is longer than the length of the photoelectric conversion region extending in the same direction.

17. The image sensing device according to claim 15, wherein The length of the second photograting region extending in one direction is shorter than the length of the photoelectric conversion region extending in the same direction.

18. The image sensing device according to claim 15, further comprising: A floating diffusion region, which is configured to contact the surface of the substrate; as well as A transfer gate is disposed above the substrate to transfer photocharge collected in the photoelectric conversion region to the floating diffusion region.

19. The image sensing device according to claim 15, further comprising: A first photoelectric grating contact is disposed on the first photoelectric grating region and provides the first control signal to the first photoelectric grating region; as well as The second photoelectric grating contact is disposed on the second photoelectric grating area and provides the second control signal to the second photoelectric grating area.

20. The image sensing device according to claim 19, wherein The first photoelectric grating contact is positioned closer to the photoelectric conversion region than the second photoelectric grating contact.

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