Image sensing device

Abstract

An image sensing device includes: a first photoelectric conversion region configured to generate photocharges based on incident light; a first photogate disposed above the first photoelectric conversion region to collect the photocharges generated by the first photoelectric conversion region; a first transfer gate disposed on one side of the first photogate to transfer the photocharges collected by the first photogate to a first floating diffusion region; a first photogate contact coupled to a first region of the first photogate; and a second photogate contact coupled to a second region of the first photogate, the second region being located closer to the first transfer gate than the first region in the first photogate. The second region is etched deeper than the first region.

Description

Technical Field

[0001] Technologies and implementations disclosed in this patent document generally relate to image sensing devices. Background Art

[0002] Image sensing devices are devices for capturing 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 communication industries, there is an increasing demand for high-performance image sensing devices in various devices such as smartphones, digital cameras, game consoles, IOT (Internet of Things), robots, security cameras, and medical micro cameras.

[0003] Image sensing devices can be roughly divided into CCD (charge coupled device) image sensing devices and CMOS (complementary metal oxide semiconductor) image sensing devices. Compared with CMOS image sensing devices, CCD image sensing devices provide better image quality, but they tend to consume more power and are larger in size. Compared with CCD image sensing devices, CMOS image sensing devices are smaller in size and consume less power. In addition, CMOS manufacturing technology can be used to merge photosensitive elements and other signal processing circuits into a single chip, making it possible to produce 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 are directed to an image sensing device capable of improving the transfer efficiency of photocharges generated by incident light.

[0005] According to an embodiment of the disclosed technology, an image sensing device may include: a first photoelectric conversion region configured to generate photocharges based on incident light; a first photogate disposed above the first photoelectric conversion region to collect photocharges generated by the first photoelectric conversion region; a first transfer gate disposed on one side of the first photogate to transfer the photocharges collected by the first photogate to a first floating diffusion region; a first photogate contact coupled to a first region of the first photogate; and a second photogate contact coupled to a second region of the first photogate, the second region being positioned closer to the first transfer gate than the first region in the first photogate. The second region is etched deeper than the first region.

[0006] It is to be understood that both the foregoing general description and the following detailed description of the disclosed technology are exemplary and explanatory and are intended to provide further explanation of the disclosure as claimed. BRIEF DESCRIPTION OF THE DRAWINGS

[0007] The above and other features and advantageous aspects of the disclosed technology will become apparent with reference to the following detailed description when considered in conjunction with the accompanying drawings.

[0008] Figure 1 is a plan view illustrating an example of a unit pixel included in an image sensing device based on some implementations of the disclosed technology.

[0009] Figure 2 This is an example of an embodiment based on the disclosed technology. Figure 1 2 is a cross-sectional view of an example of a unit pixel taken along line A1 - A1 ′ shown in FIG.

[0010] FIG. 3A to FIG. 3C Illustrated in Figure 1 and Figure 2 An example of how photocharges are collected and moved in a unit pixel is shown.

[0011] Figure 4 is a timing diagram illustrating an example of control signals applied through the photo gate contact and the transfer gate contact.

[0012] FIG. 5A to FIG. 5D An example method for forming contacts based on embodiments of the disclosed technology is illustrated.

[0013] FIG. 6A to FIG. 6C An example method for forming contacts based on another embodiment of the disclosed technology is illustrated.

[0014] FIG. 7A to FIG. 7C is a plan view illustrating an example structure of a unit pixel according to another embodiment of the disclosed technology.

[0015] Figure 8 is a plan view illustrating an example of a unit pixel included in an image sensing device according to another embodiment of the disclosed technology.

[0016] Fig. 9 Another embodiment of the disclosed technology is illustrated along the Figure 8 2 is a cross-sectional view of an example of a unit pixel taken along line A2 - A2 ′ shown in FIG.

[0017] Fig.10 is a timing diagram illustrating an example of control signals applied to the photo gate contact and the transfer gate contact.

[0018] Fig.11 is a schematic diagram illustrating an example structure of a unit pixel included in an image sensing device according to another embodiment of the disclosed technology.

[0019] Fig.12 is a schematic diagram illustrating an example structure of a unit pixel included in an image sensing device according to another embodiment of the disclosed technology. DETAILED DESCRIPTION

[0020] This patent document provides implementations and examples of image sensing devices, and the disclosed features can be implemented to achieve one or more advantages in more applications. The disclosed technology can be implemented in some embodiments to provide an image sensing device with improved photocharge transfer efficiency.

[0021] Reference will now be made in detail to certain embodiments, examples of which are shown in the accompanying drawings. As much as possible, the same reference numerals will be used throughout the accompanying drawings to refer to the same or similar parts. In the following description, detailed descriptions of related known configurations or functions incorporated herein will be omitted to avoid confusing the subject matter.

[0022] Hereinafter, various embodiments will be described with reference to the accompanying drawings. However, it should be understood that the disclosed technology is not limited to a specific embodiment, but includes various modifications, equivalents and / or substitutions of the embodiments. The embodiments of the disclosed technology can provide various effects that can be directly or indirectly recognized by the disclosed technology.

[0023] Figure 1 is a plan view illustrating an example of a unit pixel (PX) included in an image sensing device based on some implementations of the disclosed technology. Figure 2 is an example of Figure 1 A cross-sectional view of an example of a unit pixel (PX) taken along line A1 - A1 ′ is shown.

[0024] Reference Figure 1 and Figure 2 , a unit pixel (PX) may include a photoelectric conversion region 110, a floating diffusion region 120, a photogate 210, a transfer gate 220, a plurality of first photogate contacts 310, at least one second photogate contact 320, and a readout circuit 500. Here, the first photogate contact 310 and the second photogate contact 320 may include a contact plug or any type of metal or conductor component configured to electrically connect the photogate 210 to different layers. In some implementations, at least one second photogate contact 320 may be formed by performing an over-etching process, and the first photogate contact 310 may be formed without performing an over-etching process. In this patent document, an etching process and an over-etching process may include any technique for selectively removing material from a substrate or a structure on a substrate. An over-etching process may include any etching process that causes a greater degree of etching than a normal etching operation. The degree of etching may depend on many factors, such as etching time, material type, thickness of a mask pattern, etchant, and ion energy.

[0025] The photoelectric conversion region 110 may be formed in the semiconductor substrate 100 and may generate photocharges based on incident light. The photoelectric conversion region 110 may include a photodiode, a phototransistor, a pinned photodiode, or a combination thereof.

[0026] In some implementations, the floating diffusion region 120 may be formed in an upper portion of the semiconductor substrate 100. In one example, the floating diffusion region 120 may be in contact with a top surface of the semiconductor substrate 100. Photoelectric charges generated by the photoelectric conversion region 110 are transferred by the transfer gate 220 and accumulated at the floating diffusion region 120. In some implementations, the bottom surface (i.e., the opposite surface of the top surface) of the semiconductor substrate 100 is configured to receive incident light. The floating diffusion region 120 may include an N-type (N-type) with a high doping concentration. + The floating diffusion region 120 may be coupled to the readout circuit 500 .

[0027] The photogate 210 may be formed above the semiconductor substrate 100 to vertically overlap the photoelectric conversion region 110. The photogate 210 may be formed in a rectangular shape so that its length in a first direction (e.g., X-axis direction) is longer than its length in a second direction (e.g., Y-axis direction). An insulating layer (e.g., gate oxide layer) may be formed between the photogate 210 and the semiconductor substrate 100, and the photogate 210 may be coupled to the second photogate contact 320 and the first photogate contact 310. In some implementations, the photogate 210 may be formed by performing a first etching process in one portion and performing a second etching process in another portion, so that the first etching process results in a greater degree of etching than the second etching process. In one example, a portion of the photogate 210 connected to the second photogate contact 320 is formed by a first etching process, and another portion connected to the first photogate contact 310 is formed by a second etching process. In other implementations, the photogate 210 may be formed by performing an over-etching process in one portion and performing a normal etching process in another portion. In one example, a portion of the photo gate 210 connected to the second photo gate contact 320 is formed by an over-etching process, and another portion connected to the first photo gate contact 310 is formed by a normal etching process.

[0028] The photogate 210 may receive different control signals (e.g., photogate control signals) PGS1 and PGS2 through the first photogate contact 310 and the second photogate contact 320. The photogate 210 may collect photocharges based on the control signals (e.g., photogate control signals) PGS1 and PGS2, and may move the collected photocharges to a region adjacent to the transfer gate 220. For example, the photogate 210 may collect photocharges generated by the photoelectric conversion region 110 in the first charge collection region 112 based on the photogate control signal PGS1 received through the first photogate contact 310, and may move the photocharges collected in the first charge collection region 112 to the second charge collection region 114 based on the photogate control signal PGS2 received through the second photogate contact 320.

[0029] The photogate 210 may include polysilicon or a transparent conductive oxide (TCO). For example, the photogate 210 may include a transparent conductive oxide (TCO) such as indium tin oxide (ITO), indium zinc oxide (IZO), zinc oxide (ZnO), titanium dioxide (TiO2), or a combination thereof.

[0030] The transmission gate 220 may be disposed adjacent to the photogate 210 in a first direction over the semiconductor substrate 100. An insulating layer (e.g., a gate oxide layer) may be formed between the transmission gate 220 and the semiconductor substrate 100. The transmission gate 220 may be controlled by a transmission control signal (TS). The transmission gate 220 may receive the transmission control signal (TS) by being connected to the conductive line 430 via the transmission gate contact 330. The transmission gate 220 may transfer the photocharges collected by the photogate 210 to the floating diffusion region 120 based on the transmission control signal (TS).

[0031] The first photogate contact 310 may electrically couple the conductive line 410 to the photogate 210 to apply the photogate control signal PGS1 to the first region of the photogate 210. The second photogate contact 320 may electrically couple the conductive line 420 to the photogate 210 to apply another photogate control signal PGS2 to the second region of the photogate 210. In some implementations, the second region may be positioned closer to the transfer gate 220 than the first region. Here, the first region may be formed in the photogate 210 to overlap with the first charge collection region 112, and the second region may overlap with the second charge collection region 114 in the photogate 210. In some implementations, the first photogate contact 310 and the second photogate contact 320 are isolated from each other, and the first photogate contact 310 is coupled to the conductive line 410 and the second photogate contact 320 is coupled to the conductive line 420. Therefore, different photogate control signals PGS1 and PGS2 may be sequentially applied to different regions (i.e., the first region and the second region) of the photogate 210.

[0032] The first photogate contact 310 and the second photogate contact 320 may be arranged in a row in the first direction. In some implementations, the second photogate contact 320 may be positioned closer to the transmission gate 220 than the first photogate contact 310 .

[0033] In some implementations, the lower region of the second photogate contact 320 may be formed at a deeper depth in the photogate 210 than the lower region of the first photogate contact 310. For example, in the photogate 210, the portion connected to the second photogate contact 320 may be formed by performing an over-etching process that causes a greater degree of etching than the portion connected to the first photogate contact 310, so that the bottom surface of the second photogate contact 320 may be positioned closer to the semiconductor substrate 100 than the bottom surface of the first photogate contact 310. As described above, the second photogate contact 320 may be formed at a deeper depth in the photogate 210 than the first photogate contact 310, thereby increasing the intensity of the electric field generated by the photogate control signal PGS2 within the photoelectric conversion region 110.

[0034] As described above, in some implementations where the contacts 310 and the contacts 320 are coupled to the photogate 210, the contacts 320 positioned closer to the transfer gate 220 may be isolated from the other contacts 310, so that the contacts 320 and the other contacts 310 may receive different photogate control signals. In addition, the bottom surface of the contact 320 may be positioned closer to the semiconductor substrate 100 than the bottom surface of the contact 310. The image sensing device based on some implementations of the disclosed technology enables the photocharges generated by the photoelectric conversion region 110 to be collected near the transfer gate 220, thereby improving the photocharge transfer efficiency in each pixel.

[0035] The readout circuit 500 may output a pixel signal corresponding to the photocharge accumulated in the floating diffusion area 120. The readout circuit 500 may include a reset transistor RX, a source follower transistor DX, and a selection transistor SX. The source / drain region of the reset transistor RX may be coupled to a power supply voltage node (VDD) and the floating diffusion area 120, so that the reset transistor RX may initialize the floating diffusion area 120 based on a reset signal (RS) applied to its gate electrode. The source / drain region of the source follower transistor DX may be coupled to the power supply voltage node VDD and the selection transistor SX, and its gate electrode may be coupled to the floating diffusion area 120. The source follower transistor DX may generate a pixel signal corresponding to a voltage value generated by the photocharge accumulated in the floating diffusion area 120. The source / drain region of the selection transistor SX may be coupled to the source follower transistor DX and an output node (OUT), so that the selection transistor SX may output a pixel signal generated from the source follower transistor DX to the output node (OUT) based on a selection signal (SS) applied to its gate electrode.

[0036] FIG. 3A to FIG. 3C Illustrated in Figure 1 and Figure 2 An example of how photocharges are collected and moved in a unit pixel is shown. Figure 4 is a timing diagram illustrating an example of control signals applied through the photo gate contact and the transfer gate contact.

[0037] Reference Figure 3A and Figure 4 , light incident on the semiconductor substrate 100 may be converted into photocharges by the photoelectric conversion region 110. When the photogate control signal PGS1 having a high level is applied to the first region of the photogate 210 through the wire 410 and the first photogate contact 310, the photocharges generated by the photoelectric conversion region 110 may be collected in the first charge collection region 112 by the electric field generated by the photogate control signal PGS1.

[0038] Then, refer to Figure 3B and Figure 4 , when the photogate control signal PGS1 is changed to a low level, and then another photogate control signal PGS2 having a high level is applied to the second region of the photogate 210 through the wire 420 and the second photogate contact 320, the photocharges collected in the first charge collection region 112 can be moved to the second charge collection region 114 by the electric field generated by the photogate control signal PGS2. In this case, since the second photogate contact 320 is positioned closer to the semiconductor substrate 100, the intensity of the electric field formed in the semiconductor substrate 100 by the photogate control signal PGS2 can be at a relatively high level, which is conducive to the photocharges collected in the first charge collection region 112 moving to the second charge collection region 114.

[0039] Although Figure 4 The photogate control signals PGS1 and PGS2 having the same logic level (e.g., logic high or logic low) are illustrated, but it should be noted that the high levels of the photogate control signals PGS1 and PGS2 may be different from each other. For example, the high level of the photogate control signal PGS2 may be greater than the high level of the photogate control signal PGS1. In addition, after the photogate control signal PGS1 has been turned to a low level, the photogate control signal PGS2 may be activated to a high level. Alternatively, once the photogate control signal PGS1 is turned to a low level, the photogate control signal PGS2 may also be activated to a high level.

[0040] Reference Figure 3C and Figure 4When the photogate control signal PGS2 is transformed into a low level and the transmission control signal TS with a high level is applied to the transmission gate 220 through the wire 430 and the transmission gate contact 330, a channel can be formed under the transmission gate 220, so that the photocharges collected in the second charge collection area 114 can move to the floating diffusion area 120.

[0041] In this case, the transmission control signal TS applied to the transmission gate 220 may have a higher level than the photogate control signal PGS2. In addition, after the photogate control signal PGS2 has been turned to a low level, the transmission control signal TS may be applied at a high level. Alternatively, once the photogate control signal PGS2 is turned to a low level, the transmission control signal TS may be applied at a high level.

[0042] FIG. 5A to FIG. 5D An example method for forming contacts 310 and 320 based on an embodiment of the disclosed technology is illustrated.

[0043] Reference Figure 5A , a photogate 210 may be formed over the semiconductor substrate 100, and a gate spacer 212 may be formed on a side surface of the photogate 210. Subsequently, a cell spacer 214 may be formed to cover the semiconductor substrate 100, the photogate 210, and the gate spacer 212.

[0044] Subsequently, an interlayer insulating layer 302 may be formed over the cell spacers 214, and a first mask pattern (not shown) for defining a region to be used as a formation region for the first photogate contact 310 may be formed over the interlayer insulating layer 302. Then, the interlayer insulating layer 302 may be etched using the first mask pattern as an etching mask until the top surface of the photogate 210 is exposed, thereby forming a plurality of recesses 304.

[0045] Reference Figure 5B , a first photogate contact 310 may be formed by filling the recess 304 with a conductive material.

[0046] Reference Figure 5C A second mask pattern (not shown) for defining a region to be used as a formation region of the second photo gate contact 320 may be formed over the interlayer insulating layer 302 in which the first photo gate contact 310 is formed.

[0047] Subsequently, the photo grating 210 may be etched using the second mask pattern as an etching mask, thereby forming the recess 306. In this case, Figure 5C The recess 306 shown can be compared to Figure 5A Each of the recesses 304 shown in FIG. 3 is overetched more deeply.

[0048] Reference Figure 5D, the recess 306 may be filled with a conductive material to form a second photogate contact 320 .

[0049] Next, after forming a conductive layer over the interlayer insulating layer 302 to be coupled to the first photogate contact 310 and the second photogate contact 320 , the conductive layer is patterned to form conductive lines 410 and 420 .

[0050] FIG. 6A to FIG. 6C An example method for forming contacts 310 and 320 based on another embodiment of the disclosed technology is illustrated.

[0051] Reference Fig. 6A , a photogate 210 may be formed over the semiconductor substrate 100, and a gate spacer 212 may be formed on a side surface of the photogate 210. Subsequently, a cell spacer 214 may be formed to cover the semiconductor substrate 100, the photogate 210, and the gate spacer 212.

[0052] The cell spacer 214 to be used as a formation region of the second photo gate contact 320 may be partially removed. An interlayer insulating layer 302 may be formed over the cell spacer 214 and the photo gate 210 from which the cell spacer 214 is removed.

[0053] Reference Figure 6B , a mask pattern for defining a formation region of the second photogate contact 320 and a formation region of the first photogate contact 310 may be formed over the interlayer insulating layer 302. The interlayer insulating layer 302 may be etched using the mask pattern as an etching mask to form recesses or contact holes 304 and 306. Because the cell spacer 214 is present in the region where the recess 304 is formed, and the cell spacer 214 is not present in the region where the recess 306 is formed, the recesses 304 and 306 may have different depths even if the same etching process is performed thereon. In other words, the recess 306 may have a greater depth than each of the recesses 304.

[0054] Reference Figure 6C , the recesses or contact holes 304 and 306 are filled with a conductive material. In this way, a first photogate contact 310 and a second photogate contact 320 may be formed.

[0055] Subsequently, after forming a conductive layer over the interlayer insulating layer 302 to be coupled to the first photo gate contact 310 and the over-etched photo gate contact 320 , the conductive layer may be patterned to form conductive lines 410 and 420 .

[0056] FIG. 7A to FIG. 7C is a plan view illustrating an example structure of a unit pixel according to another embodiment of the disclosed technology.

[0057] Reference Fig. 7A , the first photogate contact 340 and the second photogate contact 350 may be arranged in a first direction (e.g., the X-axis direction). In this case, two second photogate contacts 350 may be arranged in a second direction (e.g., the Y-axis direction), and a plurality of pairs of first photogate contacts 340 may be arranged at intervals in the first direction, such that each pair of first photogate contacts 340 is arranged in the second direction (e.g., the Y-axis direction). In some implementations, such as from Fig. 7A It can be seen that two second photogate contacts 350 are arranged along one column (eg, the second direction), and six (three pairs) first photogate contacts 340 are arranged in three columns. In this case, the photogate 230 may be larger in width than Figure 2 The photoelectric grating 210 is shown. In some implementations, Fig. 7A The second direction width (ie, the length in the Y-axis direction) of the photoelectric grating 230 shown in the figure may be greater than Figure 1 The second direction width of the photogate 210 shown in FIG.

[0058] The first photogate contacts 340 may be commonly coupled to the conductive line 440 , and the second photogate contacts 350 may be commonly coupled to the conductive line 450 .

[0059] Reference Figure 7B The photogate 240 may include a first region 240a and a second region 240b. The first photogate contact 310 may be arranged in the first region 240a along a first direction, such as Figure 1 The two second photogate contacts 350 may be arranged along the second direction in the second region 240b, as shown. Fig. 7A As shown. The second region 240b is connected to the second photogate contact 350 and is larger in width than the first region 240a connected to the first photogate contact 310. In some implementations, each of the first region 240a and the second region 240b can be formed in a rectangular shape. In one example, the width of the first region 240a in the first direction is longer than the width of the first region 240a in the second direction, and the width of the second region 240b in the second direction is longer than the width of the second region 240b in the first direction.

[0060] Reference Figure 7C , the photogate 240 may include a first region 240a and a second region 240b, and the first photogate contact 310 is arranged in the first region 240a and the second photogate contact 320 is arranged in the second region 240b. The first photogate contact 310 and the second photogate contact 320 may be as follows: Figure 1 As shown, they are arranged in a row in the first direction. Figure 7CIt can be seen that the second region 240 b in which the second photo gate contact 320 is formed may have a greater width than the first region 240 a in which the first photo gate contact 310 is formed.

[0061] Figure 8 is a plan view illustrating an example of a unit pixel included in an image sensing device according to another embodiment of the disclosed technology. Fig. 9 Another embodiment of the disclosed technology is illustrated along the Figure 8 2 is a cross-sectional view of an example of a unit pixel taken along line A2 - A2 ′ shown in FIG.

[0062] Reference Figure 8 and Fig. 9 , the photogate contacts 362, 364, 366, and 368 connected to the photogate 210 can be connected to the wires 462, 464, 466, and 468, respectively, so that the photogate contacts 362, 364, 366, and 368 can receive the photogate control signals PGS1, PGS2, PGS3, and PGS4, respectively. For example, the photogate contact 362 can receive the photogate control signal PGS1 by connecting to the wire 462, and the photogate contact 364 can receive the photogate control signal PGS2 by connecting to the wire 464. In addition, the photogate contact 366 can receive the photogate control signal PGS3 by connecting to the wire 466, and the photogate contact 368 can receive the photogate control signal PGS4 by connecting to the wire 468.

[0063] The photogate contacts 362, 364, 366, and 368 may be arranged in a row in the first direction (the X-axis direction). The closer the photogate contacts 362, 364, 366, and 368 are positioned to the transmission gate 220, the deeper the bottom ends of the photogate contacts 362, 364, 366, and 368 are positioned in the photogate 210. In some implementations, such as from Fig. 9 It can be seen that the photogate contact 368 positioned closest to the transmission gate 220 has the greatest depth in the photogate 210 , while the photogate contact 362 positioned farthest from the transmission gate 220 has the smallest depth in the photogate 210 .

[0064] As from Fig. 9 and Fig.10It can be seen that the photogate control signals PGS1, PGS2, PGS3 and PGS4 can be applied to the photogate contacts 362, 364, 366 and 368 in sequence according to the order of the distances of the photogate contacts 362, 364, 366 and 368 from the transmission gate 220. For example, the photogate control signal PGS1 with a high level is applied to the photogate contact 362. Subsequently, when the photogate control signal PGS1 is turned to a low level or after it is turned to a low level, the photogate control signal PGS2 with a high level can be applied to the photogate contact 364. Then, when the photogate control signal PGS2 is turned to a low level or after it is turned to a low level, the photogate control signal PGS3 with a high level can be applied to the photogate contact 366. Finally, when the photogate control signal PGS3 is turned to a low level or after it is turned to a low level, the photogate control signal PGS4 with a high level can be applied to the photogate contact 368. In this case, in order to collect photo charges in a region close to the transfer gate 220 , the photogate control signal PGS4 applied to the photogate contact 368 located closest to the transfer gate 220 may be maintained at a high level for a longer period than the other photogate control signals PGS1 to PGS3 .

[0065] When or after the photo gate control signal PGS4 transitions to a low level, the transfer control signal TS may be applied at a high level so that the photo charges can move to the floating diffusion area 120 .

[0066] Fig.11 is a schematic diagram illustrating an example structure of a unit pixel (PX) included in an image sensing device according to another embodiment of the disclosed technology.

[0067] Reference Fig.11 , the unit pixel (PX) may include a first photoelectric conversion region 110a, a second photoelectric conversion region 110b, a first floating diffusion region 120a, a second floating diffusion region 120b, a first photogate 210a, a second photogate 210b, a first transfer gate 220a, a second transfer gate 220b, a plurality of third photogate contacts 310a, a plurality of fourth photogate contacts 310b, at least one fifth photogate contact 320a, at least one sixth photogate contact 320b, a first readout circuit 500a, and a second readout circuit 500b. In some implementations, at least one fifth photogate contact 320a and at least one sixth photogate contact 320b may be formed by performing an over-etching process, and the third photogate contact 310a and the fourth photogate contact 310b may be formed without performing an over-etching process.

[0068] The first photoelectric conversion region 110 a and the second photoelectric conversion region 110 b may be formed in the semiconductor substrate 100 , and may generate photo charges by converting incident light into electrons and holes.

[0069] The first floating diffusion region 120a may be used to hold or store photocharges transferred by the first transfer gate 220a. For example, photocharges collected by the first photogate 210a move toward the first floating diffusion region 120a through the first transfer gate 220a, and the photocharges are accumulated at the first floating diffusion region 120a. The first floating diffusion region 120a may be coupled to the first readout circuit 500a.

[0070] The second floating diffusion region 120b may be used to hold or store the photocharges transferred by the second transfer gate 220b. For example, the photocharges collected by the second photogate 210b move toward the second floating diffusion region 120b through the second transfer gate 220b, and the photocharges are accumulated at the second floating diffusion region 120b. The second floating diffusion region 120b may be coupled to the second readout circuit 500b.

[0071] Each of the first floating diffusion region 120a and the second floating diffusion region 120b may include an N-type (N + The first floating diffusion region 120a and the second floating diffusion region 120b may be positioned to be opposite to each other with respect to the photoelectric conversion regions 110a and 110b.

[0072] The first photogate 210a may be formed over the semiconductor substrate 100 to vertically overlap the first photoelectric conversion region 110a, and the second photogate 210b may be formed over the semiconductor substrate 100 to vertically overlap the second photoelectric conversion region 110b. Each of the first photogate 210a and the second photogate 210b may be formed in a line shape extending in a first direction (e.g., an X-axis direction), and the first photogate 210a and the second photogate 210b may be disposed adjacent to each other in a second direction (e.g., a Y-axis direction).

[0073] The first photogate 210a may be coupled to the third photogate contact 310a and the fifth photogate contact 320a, while the second photogate 210b may be coupled to the fourth photogate contact 310b and the sixth photogate contact 320b. The third photogate contact 310a may be coupled to the wire 410a, while the fourth photogate contact 310b may be coupled to the wire 410b. The fifth photogate contact 320a may be coupled to the wire 420a, while the sixth photogate contact 320b may be coupled to the wire 420b.

[0074] The first photogate 210a may collect photo charges based on photogate control signals PGS1 and PGS2 received through the third photogate contact 310a and the fifth photogate contact 320a. The second photogate 210b may collect photo charges based on photogate control signals PGS3 and PGS4 received through the fourth photogate contact 310b and the sixth photogate contact 320b. Fig.11 The first photogate 210a, the third photogate contact 310a, the fifth photogate contact 320a, and the wires 410a and 420a shown in the figure can be respectively structurally Figure 1 and Figure 2 The photogate 210, the first photogate contact 310, the second photogate contact 320, and the wires 410 and 420 are the same as shown. The second photogate 210b, the fourth photogate contact 310b, the sixth photogate contact 320b, and the wires 410b and 420b can be arranged in a shape opposite to the first photogate 210a, the third photogate contact 310a, the sixth photogate contact 320a, and the wires 410a and 420a in the first direction. In some implementations, the arrangement of the second photogate 210b, the fourth photogate contact 310b, the sixth photogate contact 320b, and the wires 410b and 420b can be symmetrical with the arrangement of the first photogate 210a, the third photogate contact 310a, the fifth photogate contact 320a, and the wires 410a and 420a about the center of the boundary between the first photoelectric conversion region 110a and the second photoelectric conversion region 110b.

[0075] The first transfer gate 220a may be formed on one side (e.g., the left side) of the first photogate 210a over the semiconductor substrate 100, and the second transfer gate 220b may be formed on the other side (e.g., the right side) of the second photogate 210b over the semiconductor substrate 100. The first transfer gate 220a may transfer photocharges collected by the first photogate 210a to the first floating diffusion region 120a based on the first transfer control signal TS1, and the second transfer gate 220b may transfer photocharges collected by the second photogate 210b to the second floating diffusion region 120b based on the second transfer control signal TS2.

[0076] The first readout circuit 500a may output a first pixel signal corresponding to the photocharge accumulated in the first floating diffusion area 120a to the first output node OUT1, and the second readout circuit 500b may output a second pixel signal corresponding to the photocharge accumulated in the second floating diffusion area 120b to the second output node OUT2. The first readout circuit 500a may include a first reset transistor RX1, a first source follower transistor DX1, and a first selection transistor SX1. The second readout circuit 500b may include a second reset transistor RX2, a second source follower transistor DX2, and a second selection transistor SX2. Fig.11 The first readout circuit 500a and the second readout circuit 500b shown can be similar in structure and function to Figure 1 and Figure 2 The readout circuit 500 shown is identical.

[0077] exist Fig.11 In the illustrated unit pixel (PX), the first photogate 210a and the second photogate 210b may be periodically turned on so that each of the first photogate 210a and the second photogate 210b may collect photo charges therein.

[0078] The photocharges collected by the first photogate 210a may be transferred to the first floating diffusion area 120a by the first transfer gate 220a, and the first readout circuit 500a may output a first pixel signal corresponding to the photocharges accumulated in the first floating diffusion area 120a to the output node OUT1. The photocharges collected by the second photogate 210b may be transferred to the second floating diffusion area 120b by the second transfer gate 220b, and the second readout circuit 500b may output a second pixel signal corresponding to the photocharges accumulated in the second floating diffusion area 120b to the output node OUT2.

[0079] Can be followed with FIG. 3A to FIG. 3C In the same manner, the first photogate 210a is used to collect the photocharges and the first transfer gate 220a is used to transfer the photocharges to the first floating diffusion region 120a. FIG. 3A to FIG. 3C In the same manner, the photo charges are collected using the second photo gate 210 b and transferred to the second floating diffusion region 120 b using the second transfer gate 220 b .

[0080] include Fig.11 The unit pixel image sensing device shown can measure the delay time of light by comparing the first pixel signal with the second pixel signal for each unit pixel, and can use the measured delay time to calculate the distance between the image sensing device and the target object to be captured. In some implementations, more than one unit pixel can be formed in each unit pixel of the image sensing device. Figure 1The structure shown in is used as a time-of-flight (TOF) sensing device for calculating the distance between the image sensing device and the target object to be captured.

[0081] Fig.12 is a schematic diagram illustrating an example structure of a unit pixel (PX) included in an image sensing device according to another embodiment of the disclosed technology.

[0082] Reference Fig.12 ,and Figure 1 Different from the content shown, the first photogate contact 310 and the second photogate contact 320 are connected to the same wire 470. That is, Fig.12 The first photogate contact 310 and the second photogate contact 320 shown may receive the same photogate control signal.

[0083] In some implementations, the bottom end of the second photogate contact 320 is positioned deeper in the photogate 210 than the first photogate contact 310, so that even when the same photogate control signal is applied to the first photogate contact 310 and the second photogate contact 320, more photocharges can be collected near the lower portion of the second photogate contact 320, thereby improving the transmission efficiency of the photocharges.

[0084] Although a number of exemplary embodiments have been described, it should be understood that variations and modifications of the disclosed embodiments and other embodiments may be designed based on what is described and / or illustrated in this patent document.

[0085] CROSS-REFERENCE TO RELATED APPLICATIONS

[0086] This patent document claims priority to and the benefits of Korean Patent Application No. 10-2021-0038196, filed on March 24, 2021, the entire contents of which are incorporated herein by reference as a part of the disclosure of this patent document.

Claims

1. An image sensing device, comprising: a first photoelectric conversion region that generates photocharges based on incident light; a first photoelectric grating disposed above the first photoelectric conversion region to collect photocharges generated by the first photoelectric conversion region; a first transfer gate, the first transfer gate being arranged at one side of the first photogate to transfer the photocharges collected by the first photogate to the first floating diffusion region; a first photogate contact coupled to a first region of the first photogate; as well as a second photogate contact coupled to a second region of the first photogate, the second region being located closer to the first transfer gate than the first region in the first photogate, The second region is etched deeper than the first region.

2. The image sensing device according to claim 1, wherein: A bottom surface of the second photo gate contact is positioned closer to the first photoelectric conversion region than a bottom surface of the first photo gate contact.

3. The image sensing device according to claim 1, wherein: The second photogate contact includes a bottom end positioned at a deeper depth in the first photogate than a bottom end of the first photogate contact.

4. The image sensing device according to claim 1, wherein: The first photogate contact is coupled to a first conductive line to receive a first photogate control signal at a first time point, and The second photogate contact is coupled to a second conductive line to receive a second photogate control signal at a second time point later than the first time point.

5. The image sensing device according to claim 1, wherein: The first photoelectric grating contact comprises: A plurality of photogate contacts are connected to the same wire to receive the same photogate control signal simultaneously.

6. The image sensing device according to claim 5, wherein: The first photogate contact and the second photogate contact are arranged in a row in a first direction.

7. The image sensing device according to claim 1, wherein: The first photoelectric grating contact comprises: A plurality of photogate contacts are provided, wherein the plurality of photogate contacts are connected to different wires to respectively receive different photogate control signals.

8. The image sensing device according to claim 7, wherein: The closer the plurality of photogate contacts are positioned to the first transfer gate, the deeper bottom ends of the plurality of photogate contacts are positioned in the first photogate.

9. The image sensing device according to claim 7, wherein: The plurality of photoelectric barrier contacts respectively receive the photoelectric barrier control signal at different time points.

10. The image sensing device according to claim 9, wherein: The closer the plurality of photogate contacts are positioned to the first transmission gate, the later the plurality of photogate contacts receive the photogate control signal.

11. The image sensing device according to claim 1, wherein: The second photogate contact comprises: A plurality of photogate contacts are connected to the same wire to receive the same photogate control signal simultaneously.

12. The image sensing device according to claim 11, wherein: The first photogate contact comprises a plurality of photogate contacts arranged in a row in a first direction, and The second photogate contact includes a plurality of photogate contacts arranged in a row in a second direction perpendicular to the first direction.

13. The image sensing device according to claim 1, wherein: The first photogate contact and the second photogate contact are commonly connected to the same wire to simultaneously receive the same photogate control signal.

14. The image sensing device according to claim 1, wherein: The first photoelectric conversion region comprises: a first charge collection region disposed below the first region and collecting photo charges by a first photogate control signal applied to the first photogate contact; and A second charge collection region is disposed below the second region and moves the photo charges collected in the first charge collection region by a second photogate control signal applied to the second photogate contact.

15. The image sensing device according to claim 1, wherein: The first region is formed in a rectangular shape having a width in a first direction longer than a width in a second direction perpendicular to the first direction, and The second region is formed in a rectangular shape whose width in the second direction is longer than that in the first direction.

16. The image sensing device according to claim 1, further comprising: A first readout circuit outputs a first pixel signal corresponding to the photocharge accumulated in the first floating diffusion area.

17. The image sensing device according to claim 1, further comprising: a second photoelectric conversion region that is located adjacent to the first photoelectric conversion region within the same unit pixel and generates photocharges by converting the incident light; a second photoelectric gate disposed above the second photoelectric conversion region and collecting photocharges generated by the second photoelectric conversion region; a second transfer gate disposed at one side of the second photogate and transferring the photocharges collected by the second photogate to a second floating diffusion region; a third photogate contact coupled to the first region of the second photogate; as well as A fourth photogate contact is coupled to a second region of the second photogate, the second region being located closer to the second transfer gate than the first region in the second photogate.

18. The image sensing device according to claim 17, wherein: The first transfer grating and the second transfer grating are positioned opposite to each other with respect to the first photo grating and the second photo grating.

19. The image sensing device according to claim 17, further comprising: A second readout circuit outputs a second pixel signal corresponding to the photocharge accumulated in the second floating diffusion area.

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