Photoelectric conversion element, pixel, time-of-flight sensor, and electronic device

Abstract

The application provides a photoelectric conversion element, a pixel, a time-of-flight sensor and an electronic device. The photoelectric conversion element comprises: a substrate; a photoelectric conversion region arranged in the substrate; a charge collection region arranged in the substrate and arranged adjacent to the photoelectric conversion region; a first flow guide layer extending from a surface of the substrate to the inside of the photoelectric conversion region; a second flow guide layer arranged on the surface of the substrate, the second flow guide layer being connected with the first flow guide layer and extending to the charge collection region; and an electrical isolation layer arranged at the interface between the first flow guide layer and the substrate and the interface between the second flow guide layer and the substrate. The application can effectively improve the transmission efficiency of photoelectric charges generated by the photoelectric conversion element, improve the demodulation contrast performance of the sensor, and effectively improve the time accuracy and ranging quality of the time-of-flight sensor.

Description

Technical Field

[0001] This invention belongs to the field of photoelectric sensing, and in particular relates to a photoelectric conversion element, a pixel, a time-of-flight sensor, and an electronic device. Background Technology

[0002] Time-of-flight (TOF) sensors are an important component of ranging devices, capable of capturing three-dimensional (3D) distance information of target objects and obtaining 3D images. They are widely used in fields such as behavior analysis, surveillance, autonomous driving, artificial intelligence, machine vision perception, and 3D image enhancement. TOF sensors typically employ the time-of-flight method, measuring the travel time of light pulses from the light source's emission point to the target object's reflection and then to the sensor's receiving point, thereby determining the distance information of the target object.

[0003] Time-of-flight (TOF) sensors can obtain the travel time of light directly or indirectly. The indirect method involves recording the phase difference of a light pulse from emission to reception, and then calculating the travel time. A typical TOF sensor includes a light source emitting module and a light source sensing module, the latter containing photosensitive pixels. These photosensitive pixels can obtain time data indirectly; each pixel needs to acquire the phase photoelectric charge signal of the modulated light wave to deduce the time information.

[0004] Photosensitive pixels contain photoelectric conversion elements to convert light into charge. Generally, the frequency of the modulated light wave emitted by the light source is relatively high, for example, up to 100MHz. When the sensor is working to demodulate the phase photoelectric signal, the current photoelectric conversion elements have poor transmission efficiency of the converted photoelectric charge, resulting in poor demodulation contrast performance of the sensor. Summary of the Invention

[0005] In view of the shortcomings of the prior art described above, the purpose of this invention is to provide a photoelectric conversion element, a pixel, a time-of-flight sensor, and an electronic device to solve the problem of low demodulation contrast of photoelectric sensors due to low photoelectric charge transfer efficiency in the prior art.

[0006] To achieve the above and other related objectives, the present invention provides a photoelectric conversion element, the photoelectric conversion element comprising: a substrate; a photoelectric conversion region disposed in the substrate; a charge collection region disposed in the substrate and adjacent to the photoelectric conversion region; a first current-conducting layer extending from the surface of the substrate into the interior of the photoelectric conversion region; a second current-conducting layer disposed on the surface of the substrate, the second current-conducting layer being connected to the first current-conducting layer and extending into the charge collection region; and an electrical isolation layer disposed at the interface between the first current-conducting layer and the substrate and at the interface between the second current-conducting layer and the substrate.

[0007] Optionally, the photoelectric conversion element includes a first current-guiding layer that extends vertically from the substrate surface into the interior of the photoelectric conversion region, and the depth of the first current-guiding layer is less than the depth of the photoelectric conversion region.

[0008] Optionally, the photoelectric conversion element includes multiple first current guiding layers arranged at intervals. The multiple first current guiding layers extend vertically from the surface of the substrate into the interior of the photoelectric conversion region. The depth of the multiple first current guiding layers is less than the depth of the photoelectric conversion region. All of the multiple first current guiding layers are connected to the second current guiding layer.

[0009] Furthermore, the second current-guiding layer includes a cross-shaped intersection and a connecting portion connected to the cross-shaped intersection and extending to the charge collection region, and multiple first current-guiding layers are respectively disposed at the four ends and intersection of the cross-shaped intersection.

[0010] Optionally, the first current-guiding layer is elongated when projected vertically onto the substrate surface, and the second current-guiding layer includes an elongated portion that cooperates with the first current-guiding layer, and a connecting portion that connects to the elongated portion and extends to the charge collection region.

[0011] Optionally, the first current-guiding layer is annular in shape when projected vertically onto the substrate surface, and the second current-guiding layer includes an annular portion that cooperates with the first current-guiding layer, and a connecting portion that connects to the annular portion and extends to the charge collection region.

[0012] Furthermore, the ring includes one of a polygonal ring, an elliptical ring, and a circular ring, and the polygonal ring includes one of a triangular ring, a rectangular ring, a rhombus ring, an equilateral hexagonal ring, and an equilateral octagonal ring.

[0013] Optionally, the photoelectric conversion region includes one of a Pin-type photodiode structure and a photoelectric conversion structure based on a P-type epitaxial layer, wherein the Pin-type photodiode structure includes an n-type region and a surface p-type doped region located on the n-type region, the surface p-type doped region being located around the second current-conducting layer, and the first current-conducting layer extending to the n-type region.

[0014] Optionally, the area of ​​the photoelectric conversion region is greater than or equal to 100 square micrometers, and the depth is greater than or equal to 10 micrometers.

[0015] Optionally, the photoelectric conversion element further includes an isolation structure surrounding the photoelectric conversion region and the charge collection region, wherein the depth of the isolation structure is greater than the depth of the charge collection region.

[0016] Optionally, the first guiding layer is equidistant from the periphery of the photoelectric conversion area, and the second guiding layer is equidistant from the periphery of the edges of the photoelectric conversion area located on both sides thereof.

[0017] Optionally, the distance between the exposed end of the second flow guiding layer and the edge of the photoelectric conversion region is greater than 0.1 μm.

[0018] Optionally, when the photoelectric conversion region is photosensitive and converted into photoelectric charge, the first and second guiding layers apply a first high potential to attract photoelectric charge on the surface of the electrical isolation layer and form a guiding region, and the charge collection region applies a second high potential, which is higher than the first high potential, so that the photoelectric charge is transported along the guiding region to the charge collection region.

[0019] The present invention also provides a pixel, the pixel comprising: a photoelectric conversion element as described in any of the above embodiments; and a photoelectric signal readout circuit connected to the charge collection region.

[0020] Optionally, the photoelectric signal readout circuit includes one of the following: a circuit structure for acquiring single-phase signals, a circuit structure for acquiring dual-phase signals, and a circuit structure for acquiring four-phase signals.

[0021] Optionally, the photoelectric signal readout circuit is used to receive and modulate the photoelectric charge generated by the photoelectric conversion element into a phase photoelectric charge signal corresponding to the modulated light wave emitted by the light source emitter, and convert the phase photoelectric charge signal into a phase photoelectric signal for output.

[0022] The present invention also provides a time-of-flight sensor, the time-of-flight sensor comprising: a light source emitter for emitting modulated light waves toward a target object; a pixel array comprising a plurality of pixels as described in any of the above embodiments, the pixels being used to receive the modulated light waves reflected by the target object and modulate them into a phase photoelectric charge signal corresponding to the modulated light waves, and convert the phase photoelectric charge signal into a phase photoelectric signal; a control circuit for controlling the operation of the light source emitter and the pixel array; and a readout circuit for reading the phase photoelectric signal in the pixel array.

[0023] Optionally, the time-of-flight sensor further includes logic circuitry for processing the phase photoelectric signal read by the reading circuitry to obtain the time information and / or distance information required by the pixel.

[0024] Optionally, the pixels in the pixel array are arranged in a rectangular array, and each column of pixels in the pixel array is connected to the reading circuit by at least one signal line. The reading circuit reads the phase photoelectric signal of the pixel array in one of the following ways: row scrolling reading, selective reading of some pixels, and global reading.

[0025] Optionally, the light source emitter includes one of a vertical cavity surface-emitting laser, an edge-emitting laser, and a light-emitting diode, and the modulated light wave includes one of a sinusoidal modulated light wave and a square pulse light wave.

[0026] The present invention also provides an electronic device configured with a time-of-flight sensor as described above.

[0027] As described above, the photoelectric conversion element, pixel, time-of-flight sensor, and electronic device of the present invention have the following beneficial effects:

[0028] In the photoelectric conversion element of this invention, during the pixel modulation phase photoelectric signal process, the first guiding layer is set to a high potential to form a high electric field gradient around it. This rapidly attracts the photoelectric charge generated within the photoelectric conversion element to the guiding region near the first guiding layer. Combined with the guiding region of the second guiding layer on the surface of the photoelectric conversion element, this forms a high-speed guiding path for the photoelectric charge. This quickly guides the photoelectric charge generated during the modulation phase time period to the charge collection region, avoiding the problem of the photoelectric charge being retained and collected by the next phase signal due to its slow transmission speed. It also eliminates the erroneous collection between adjacent phase photoelectric charges, improving the purity of the phase photoelectric signal. This invention can effectively improve the transmission efficiency of the photoelectric charge generated by the photoelectric conversion element, improve the demodulation contrast performance of the sensor, and effectively improve the time accuracy and ranging quality of the time-of-flight sensor. Attached Figure Description

[0029] Figures 1-2 The diagram shown is a structural schematic of a photoelectric conversion element in a specific embodiment of the present invention.

[0030] Figures 3-4 The diagram shown is a structural schematic of a photoelectric conversion element in another specific embodiment of the present invention.

[0031] Figures 5-6 The diagram shown is a structural schematic of a photoelectric conversion element in another specific embodiment of the present invention.

[0032] Figures 7-8 The diagram shown is a structural schematic of a photoelectric conversion element in another specific embodiment of the present invention.

[0033] Figure 9 The diagram shown is a schematic representation of the photoelectric conversion element according to an embodiment of the present invention.

[0034] Figure 10 The diagram shown is a structural schematic of a pixel according to an embodiment of the present invention.

[0035] Figure 11 The diagram shown is a structural schematic of the time-of-flight sensor according to an embodiment of the present invention.

[0036] Component designation explanation

[0037] 100 Time-of-Flight Sensor

[0038] 101 pixel array

[0039] 102 Reading Circuit

[0040] 103 Control Circuit

[0041] 104 Light Source Emitter

[0042] 105 Logic Circuits

[0043] 200 pixels

[0044] 201 Photoelectric Conversion Element

[0045] 202 Photoelectric signal readout circuit

[0046] 300 substrate

[0047] 301 Photoelectric Conversion Area

[0048] 302a, 302b, 302c, 302d Second Deflection Layer

[0049] 303a, 303b, 303c, 303d, Second Deflection Layer

[0050] 303e, 303f, 303g

[0051] 304 charge collection region

[0052] 305 Isolation Structure

[0053] Electrical isolation layers 401a, 401b, 401c, 401d

[0054] 501a Cross-shaped intersection

[0055] 501b Long Section

[0056] 501c Annular part

[0057] 502a, 502b, 502c connecting parts Detailed Implementation

[0058] The following specific examples illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention.

[0059] In the detailed description of embodiments of the present invention, for ease of explanation, the cross-sectional views illustrating the device structure may be partially enlarged and not to scale. Furthermore, the schematic diagrams are merely examples and should not limit the scope of protection of the present invention. In actual fabrication, the three-dimensional spatial dimensions of length, width, and depth should be included.

[0060] For ease of description, spatial relation terms such as “below,” “under,” “lower than,” “below,” “above,” and “upper” may be used herein to describe the relationship between one element or feature shown in the accompanying drawings and other elements or features. It will be understood that these spatial relation terms are intended to include directions other than those depicted in the drawings for devices in use or operation. Furthermore, when a layer is referred to as being “between” two layers, it may be the only layer between the two layers, or there may be one or more layers in between.

[0061] In the context of this application, the structure described above the first feature may include embodiments in which the first and second features are formed in direct contact, or embodiments in which additional features are formed between the first and second features, such that the first and second features may not be in direct contact.

[0062] It should be noted that the illustrations provided in this embodiment are only schematic representations of the basic concept of the present invention. Therefore, the illustrations only show the components related to the present invention and are not drawn according to the actual number, shape and size of the components in the actual implementation. In the actual implementation, the form, quantity and proportion of each component can be arbitrarily changed, and the layout of the components may also be more complex.

[0063] Photosensitive pixels contain photoelectric conversion elements used to convert light waves into photoelectric charges. In time-of-flight sensors, because the light source is generally near-infrared light, which has a longer wavelength, the conversion efficiency of photoelectric conversion elements for near-infrared light is lower than that for visible light. Furthermore, near-infrared light requires a longer light absorption path. Therefore, photoelectric conversion elements are generally large in area and deep in depth, for example, the area of ​​a photoelectric conversion element is greater than 50 square micrometers and the depth is greater than 10 micrometers.

[0064] However, the frequency of the modulated light waves emitted by the light source is usually high, up to 100MHz. When the sensor is working to demodulate the phase photoelectric signal, the photoelectric charge transfer efficiency of the photoelectric conversion element with a large area and deep depth is not good, which will result in poor demodulation contrast performance of the sensor.

[0065] To solve the above problems, such as Figures 1-9 As shown, an embodiment provides a photoelectric conversion element 201, which includes: a substrate 300, a photoelectric conversion region 301, a charge collection region 304, a first current-conducting layer, a second current-conducting layer, and an electrical isolation layer.

[0066] The substrate 300 can be made of silicon, germanium, silicon-germanium, silicon-on-insulator, germanium-on-insulator, silicon-germanium-on-insulator, silicon carbide, group III-V semiconductor compounds, etc. In this embodiment, the substrate 300 is made of silicon.

[0067] The photoelectric conversion region 301 is arranged in the substrate 300.

[0068] As an example, the photoelectric conversion region 301 includes one of a pin-type photodiode structure and a photoelectric conversion structure based on a p-type epitaxial layer.

[0069] In one example, the substrate 300 is a P-type doped silicon substrate, and a dopant is implanted into the P-type doped silicon substrate to form a P-type epitaxial layer structure to form the electro-conversion charge region. The dopant may be phosphorus or arsenic, etc.

[0070] In another example, the charge conversion region may be the same as the P-type doped silicon substrate, without any implanted dopant, that is, the charge conversion region is an intrinsically undoped P-type epitaxial layer structure.

[0071] In another embodiment, the electro-conversion charge region can be a Pin-type photodiode structure, wherein the Pin-type photodiode structure includes an n-type region and a surface p-type doped region located on the n-type region. The p-type doped region is used to prevent leakage current of the Pin-type photodiode. The surface p-type doped region is located around the second current-conducting layer, and the first current-conducting layer extends to the n-type region.

[0072] In one embodiment, to effectively increase the absorption path length of the light waves in the photoelectric conversion region and meet the conversion efficiency of the photoelectric conversion region for near-infrared light, the area of ​​the photoelectric conversion region 301 is greater than or equal to 100 square micrometers, and the depth is greater than or equal to 10 micrometers. Furthermore, the area of ​​the photoelectric conversion region 301 can be set to be greater than or equal to 200 square micrometers.

[0073] The charge collection region 304 is disposed in the substrate 300 and adjacent to the photoelectric conversion region 301. In one example, a dopant is implanted into the charge collection region 304, and the dopant may be phosphorus or arsenic. The photoelectric conversion element 201 also includes an isolation structure 305 surrounding the photoelectric conversion region 301 and the charge collection region 304. The depth of the isolation structure 305 is greater than the depth of the charge collection region 304 to prevent the charge collection region 304 from coupling and affecting the operation of other devices when the photoelectric conversion element 201 is operating.

[0074] The first current-conducting layer extends from the surface of the substrate 300 into the interior of the photoelectric conversion region 301; the second current-conducting layer is disposed on the surface of the substrate 300, connected to the first current-conducting layer, and extends to the charge collection region 304; the electrical isolation layer is disposed at the interface between the first current-conducting layer and the substrate 300 and the interface between the second current-conducting layer and the substrate 300. When the photoelectric conversion region 301 is photosensitive and converted into photoelectric charge, the first and second current-conducting layers apply a first high potential to attract photoelectric charge on the surface of the electrical isolation layer and form a current-conducting region, and the charge collection region 304 applies a second high potential, which is higher than the first high potential, so that the photoelectric charge is transported along the current-conducting region to the charge collection region 304.

[0075] As an example, the first and second current-conducting layers can be made of polycrystalline silicon, and the electrical isolation layer can be made of silicon dioxide. Of course, in other embodiments, the first and second current-conducting layers can also be made of other conductive materials, such as metals, and the electrical isolation layer can also be made of other dielectric materials, such as high-k dielectrics.

[0076] In one specific embodiment, such as Figures 1-2 As shown, where, Figure 1 The diagram shown is a top view of the photoelectric conversion element 201. Figure 2 Displayed as Figure 1A schematic diagram of the cross-sectional structure cut along line A-A'. The photoelectric conversion element 201 includes a first current-guiding layer 303a, which extends vertically from the surface of the substrate 300 into the interior of the photoelectric conversion region 301 to respond to and attract photoelectric charges generated deep within the photoelectric conversion region 301. The depth of the first current-guiding layer 303a is less than the depth of the photoelectric conversion region 301, and the vertical distance from the first current-guiding layer 303a to the periphery of the photoelectric conversion region 301 is equal. It also includes a second current-guiding layer 302a, which is connected to the upper surface of the first current-guiding layer 303a and extends horizontally to the charge collection region 304. The vertical distance from the second current-guiding layer 302a to the edges of the photoelectric conversion region 301 located on both sides thereon is equal. An electrical isolation layer 401a is disposed at the interface between the first current-guiding layer and the substrate 300 and at the interface between the second current-guiding layer and the substrate 300. In this embodiment, the first guiding layer 303a and the second guiding layer 302a form a "T" shape on the cross-section cut along A-A', and together they serve as a guiding path for the rapid transmission of photoelectric charge.

[0077] In one embodiment, the distance between the exposed end of the second flow guiding layer 302a and the edge of the photoelectric conversion region 301 is greater than 0.1 μm. For example, the distance can be 0.1 μm, 0.15 μm, 0.2 μm, 0.5 μm, etc., thereby increasing the photosensitive area of ​​the photoelectric conversion region 301.

[0078] In another specific embodiment, such as Figures 3-4 As shown, where, Figure 3 The diagram shown is a top view of the photoelectric conversion element 201. Figure 4 Displayed as Figure 3 A schematic diagram of the cross-sectional structure cut along line B-B'. The photoelectric conversion element 201 includes multiple first current-guiding layers arranged at intervals. These multiple first current-guiding layers extend vertically from the surface of the substrate 300 into the interior of the photoelectric conversion region 301. The depth of each of the multiple first current-guiding layers is less than the depth of the photoelectric conversion region 301. All of the multiple first current-guiding layers are connected to a second current-guiding layer. Further, the second current-guiding layer includes a cross-shaped intersection 501a and a connecting portion 502a connected to the cross-shaped intersection 501a and extending into the charge collection region 304. The multiple first current-guiding layers are respectively disposed at the four ends and the intersection of the cross-shaped intersection. Figure 4As shown, multiple first flow guiding layers 303a, 303b, 303d and second flow guiding layer 302b form a trident-shaped structure. Similarly, multiple first flow guiding layers 303a, 303c, 303e and second flow guiding layer 302b can also form a trident-shaped structure on another cut section (not shown in the schematic diagram). The depth of the first flow guiding layers 303a, 303b, 303c, 303d, 303e is less than the depth of the photoelectric conversion region 301. The first flow guiding layers 303a, The distribution of layers 303b, 303c, 303d, and 303e in the photoelectric conversion region 301 is uniform. The distance from the first current guiding layer 303a to the first current guiding layer 303c is equal to the distance to the first current guiding layer 303e. The distance from the first current guiding layer 303a to the first current guiding layer 303b is equal to the distance to the first current guiding layer 303d. Furthermore, the vertical distances of the first current guiding layers 302b, 303d, 303c, and 303e to the edge of the photoelectric conversion region 301 are all equal or comparable. The electrical isolation layer 401b is disposed at the interface between the first current guiding layer and the substrate 300 and at the interface between the second current guiding layer and the substrate 300. The structure in this example can be used for a larger area of ​​photoelectric conversion region 301. For example, the area of ​​the photoelectric conversion region 301 can be set to be greater than or equal to 200 square micrometers. The photoelectric conversion region 301 covered by the first guiding layer 303a, 303b, 303c, 303d, and 303e of the trident-shaped structure is relatively wide, which is beneficial to quickly attract the photoelectric charge generated in the larger area of ​​the photoelectric conversion region 301 to the vicinity of its surface guiding region, effectively improving the transmission efficiency of photoelectric charge.

[0079] In yet another specific embodiment, such as Figures 5-6 As shown, where, Figure 5 The diagram shown is a top view of the photoelectric conversion element 201. Figure 6 Displayed as Figure 5 A schematic diagram of the cross-sectional structure cut along C-C'. The first current-guiding layer, when projected vertically onto the surface of the substrate 300, is elongated. The second current-guiding layer includes an elongated portion 501b that mates with the first current-guiding layer, and a connecting portion 502b that connects to the elongated portion 501b and extends to the charge collection region 304. Specifically, as shown... Figure 5 As shown, both the first guide layer 303f and the second guide layer 302c are elongated strips in the shape of the letter "I", located in the middle of the transverse direction on the surface of the photoelectric conversion region 301, as... Figure 6As shown, the first current-guiding layer 303f extends vertically from the surface of the substrate 300 into the interior of the photoelectric conversion region 301, forming a wall structure. The depth of the first current-guiding layer 303f is less than the depth of the photoelectric conversion region 301, and the two sides of the first current-guiding layer 303f are equidistant from the edge of the photoelectric conversion region 301. The electrical isolation layer 401c is disposed at the interface between the first current-guiding layer and the substrate 300 and at the interface between the second current-guiding layer and the substrate 300. In this example, the wall structure of the first current-guiding layer 303f is more conducive to forming a strong electric field in its vicinity. The first current-guiding layer 303f more effectively and quickly attracts the photoelectric charge generated in the photoelectric conversion region 301 to the vicinity of its surface current-guiding region, thereby improving the photoelectric charge transmission efficiency.

[0080] In yet another specific embodiment, such as Figures 7-8 As shown, where, Figure 7 The diagram shown is a top view of the photoelectric conversion element 201. Figure 8 Displayed as Figure 7 A schematic diagram of the cross-sectional structure cut along line D-D'. The first current-guiding layer, projected vertically onto the surface of the substrate 300, is annular. The second current-guiding layer includes an annular portion 501c that mates with the first current-guiding layer, and a connecting portion 502c that connects to the annular portion 501c and extends to the charge collection region 304. For example, the annulus includes one of a polygonal ring, an elliptical ring, and a circular ring. The polygonal ring includes one of a triangular ring, a rectangular ring, a rhombus ring, an equilateral hexagonal ring, and an equilateral octagonal ring. In this embodiment, the annulus is a rectangular ring. Of course, in practical applications, the annulus can be used as long as it has a uniform critical size and shape.

[0081] like Figure 7 As shown, in a planar top view of the surface of the photoelectric conversion element 201, the second flow guiding layer 302d is a rectangle (annular portion 501c) with a handle (connecting portion 502c), located in the middle of the surface of the photoelectric conversion region 301, and the first flow guiding layer 303g is in the shape of a rectangular loop. Along Figure 7 The cross-section cut at point D-D', as shown Figure 8As shown, the first current-guiding layer 303g and the second current-guiding layer 302d present a door-frame-like structure. The depth of the first current-guiding layer 303g is less than the depth of the photoelectric conversion region 301, and the vertical distances of the two first current-guiding layers 303g from the two side edges of the photoelectric conversion region 301 are the same. The electrical isolation layer 401d is disposed at the interface between the first current-guiding layer and the substrate 300 and at the interface between the second current-guiding layer and the substrate 300. In this specific embodiment, a strong electric field can be formed in the photoelectric conversion region 301 near the first current-guiding layer 303g. The first current-guiding layer 303g can effectively and quickly attract the photoelectric charge generated in the photoelectric conversion region 301 to the vicinity of its surface current-guiding region, thereby improving the photoelectric charge transmission efficiency.

[0082] The above are as follows Figures 1 to 8 Each specific embodiment of the photoelectric conversion element 201 structure can effectively improve the transmission efficiency of the photoelectric charge generated in the photoelectric conversion region 301 of the photoelectric conversion element 201 to the charge collection region 304. The following uses... Figures 1-2 The specific principles are illustrated in detail with examples, as follows: Figure 9 As shown.

[0083] like Figure 9 As shown, when modulating the photoelectric charge signal of the optical wave phase, the photoelectric conversion region 301 receives the optical wave and converts it into photoelectric charge. The second guiding layer 302a and the first guiding layer 303a are given a high potential, for example, 1.2V or 1.8V. A high electric field region is formed near the guiding region on the surface of the second guiding layer 302a and the first guiding layer 303a, such as... Figure 9 As shown. In Figure 9 Within the photoelectric conversion region 301, the electric field lines are directed away from the second current-conducting layer 302a and the first current-conducting layer 303a. The closer to the second current-conducting layer 302a and the first current-conducting layer 303a, the higher the potential. Under the influence of the high electric field, the photoelectric charges in the photoelectric conversion region 301 move rapidly from a distance to the vicinity of the current-conducting regions of the second current-conducting layer 302a and the first current-conducting layer 303a. Because the potential given to the charge collection region 304 is higher, the photoelectric charges will move rapidly from bottom to top along the current-conducting region of the first current-conducting layer 303a, and then from left to right along the current-conducting region of the second current-conducting layer 302a, and are quickly transferred to the charge collection region 304. This avoids the problem of the phase photoelectric charges being stuck in the next phase signal and collected by the next phase signal due to the slow transmission speed of the phase photoelectric charges, eliminates the problem of miscollection between adjacent phase photoelectric charges, and improves the purity of the phase photoelectric signal. Therefore, the present invention effectively improves the transmission efficiency of photoelectric charge generated by photoelectric conversion element 201, improves the demodulation contrast performance of sensor, and effectively improves the time accuracy and ranging quality of sensor.

[0084] like Figure 10As shown, this embodiment also provides a pixel 200, which includes: a photoelectric conversion element 201 as described in the above embodiment, used to receive the modulated light wave signal reflected back from the target object and convert the modulated light wave signal into photoelectric charge; and a photoelectric signal readout circuit 202, which is connected to the charge collection area 304.

[0085] The photoelectric signal readout circuit 202 includes multiple transistor devices (such as a transmission transistor TX, a reset transistor RST, a source follower transistor SF, and a row select transistor RS; in one example, the charge collection region 304 serves as the source of the transmission transistor TX) to achieve the function of acquiring a phase photoelectric signal that modulates the phase of the light wave. The photoelectric signal readout circuit can be a single-phase signal acquisition circuit structure (single tap), a dual-phase signal acquisition circuit structure (dual tap), or a four-phase signal acquisition circuit structure (four tap). The photoelectric signal readout circuit 202 is used to receive and modulate the photoelectric charge generated by the photoelectric conversion element 201 into a phase photoelectric charge signal corresponding to the modulated light wave emitted by the light source emitter 104, and convert the phase photoelectric charge signal into a phase photoelectric signal for output.

[0086] like Figure 11 As shown, this embodiment also provides a time-of-flight sensor 100, which includes: a light source emitter 104 for emitting modulated light waves toward a target object; a pixel array 101 including a plurality of pixels 200 as described in the above embodiment, wherein the pixels 200 are used to receive the modulated light waves reflected by the target object and modulate them into a phase photoelectric charge signal corresponding to the modulated light waves, and convert the phase photoelectric charge signal into a phase photoelectric signal to obtain the time of flight based on the phase photoelectric signal, thereby calculating the required distance information; a control circuit 103 for controlling the operation of the light source emitter 104 and the pixel array 101; and a reading circuit 102 for reading the phase photoelectric signal in the pixel array 101.

[0087] In one embodiment, the light source emitter 104 includes one of a vertical cavity surface-emitting laser, an edge-emitting laser, and a light-emitting diode, and the modulated light wave includes one of a sinusoidal modulated light wave and a square pulse light wave, wherein the modulated light wave is a near-infrared light wave.

[0088] As an example, the pixels 200 in the pixel array 101 are arranged in a rectangular array, such as... Figure 11As shown, the pixels 200P1, P2, ..., Pn form a rectangular array in a two-dimensional structure. In this embodiment, the pixels 200 are arranged in rows (e.g., rows R1 to Ry) and columns (e.g., columns C1 to Cx) to obtain the phase photoelectric charge signal of the target object, person, or other object. The phase photoelectric charge signal can then be used to reconstruct a 3D data image of the distance and depth of the target object, person, or other object. However, in other embodiments, it should be understood that the pixels 200 do not need to be arranged in rows and columns, and other configurations can be used.

[0089] For the pixel array 101 arranged in a rectangular array, each column of pixels 200 in the pixel array 101 is connected to the readout circuit 102 by at least one signal line. The readout circuit 102 reads the phase photoelectric signal of the pixel array 101 in one of the following ways: row scrolling readout, selective readout of a portion of pixels 200, and global readout. That is, the readout circuit can read out one row of phase photoelectric charge signal at a time along the readout column line, or it can use various other techniques, such as serial readout or simultaneous parallel readout of all pixels 200, to read out the phase photoelectric charge signal. The readout circuit 102 may include an amplifier circuit, an analog-to-digital converter (ADC) circuit, or other circuits.

[0090] In one example, each pixel 200 in the pixel array 101 remains globally active; the control circuit 103 is coupled to the pixel array 101 to control the operation of the plurality of pixels 200 in the pixel array 101. For example, the control circuit 103 may generate a shutter signal for controlling the modulated light wave phase photoelectric charge. In one example, the shutter signal is a global shutter signal used to simultaneously activate all pixels 200 within the pixel array 101 to simultaneously capture the corresponding modulated light wave phase photoelectric signals of all pixels 200 during a single acquisition window.

[0091] In another example, the phase photoelectric signal data acquired by the pixel array 101 required for calculating the time is synchronized with the periodic light wave emitted by the light source emitter 104. The synchronized operation of the pixel array 101 and the light source emitter 104 is controlled by the control circuit 103.

[0092] In one embodiment, the time-of-flight sensor 100 further includes a logic circuit 105 for processing the phase photoelectric signal read by the reading circuit 102 to obtain time information and / or distance information for each pixel 200 in the pixel array 101. For example, the logic circuit 105 may store the phase photoelectric signal or perform calculations on the phase photoelectric signal. For instance, the logic circuit 105 may include a digital signal processing module to process the phase photoelectric charge signal into 3D distance data for use by a subsequent terminal platform.

[0093] This embodiment also provides an electronic device, which is equipped with a time-of-flight sensor 100 as described in the embodiment.

[0094] In one example, the time-of-flight sensor 100 may be included in similar products such as automotive radar, mobile phone ranging, and machine vision. Additionally, the time-of-flight sensor 100 system can also be coupled to other hardware components, such as toys, drones, and surveillance cameras. These other hardware components can transmit commands to the time-of-flight sensor 100 to extract the phase photoelectric charge signals required for 3D imaging or manipulate the phase photoelectric charge signals supplied by the time-of-flight sensor 100 system.

[0095] As described above, the photoelectric conversion element, pixel, time-of-flight sensor, and electronic device of the present invention have the following beneficial effects:

[0096] In the photoelectric conversion element of this invention, during the pixel modulation phase photoelectric signal process, the first guiding layer is set to a high potential to form a high electric field gradient around it. This rapidly attracts the photoelectric charge generated within the photoelectric conversion element to the guiding region near the first guiding layer. Combined with the guiding region of the second guiding layer on the surface of the photoelectric conversion element, this forms a high-speed guiding path for the photoelectric charge. This quickly guides the photoelectric charge generated during the modulation phase time period to the charge collection region, avoiding the problem of the photoelectric charge being retained and collected by the next phase signal due to its slow transmission speed. It also eliminates the erroneous collection between adjacent phase photoelectric charges, improving the purity of the phase photoelectric signal. This invention can effectively improve the transmission efficiency of the photoelectric charge generated by the photoelectric conversion element, improve the demodulation contrast performance of the sensor, and effectively improve the time accuracy and ranging quality of the time-of-flight sensor.

[0097] The above embodiments are merely illustrative of the principles and effects of the present invention and are not intended to limit the invention. Any person skilled in the art can modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by those skilled in the art without departing from the spirit and technical concept disclosed in the present invention should still be covered by the claims of the present invention.

Claims

1. A photoelectric conversion element, characterized in that, The photoelectric conversion element includes: Substrate; A photoelectric conversion region is disposed in the substrate; A charge collection region is disposed in the substrate and is adjacent to the photoelectric conversion region; The first current-guiding layer extends from the surface of the substrate into the interior of the photoelectric conversion region; A second current-guiding layer is disposed on the surface of the substrate, the second current-guiding layer is connected to the first current-guiding layer and extends to the charge collection region; An electrical isolation layer is disposed at the interface between the first current-conducting layer and the substrate, and at the interface between the second current-conducting layer and the substrate; The second flow guiding layer is connected to the upper surface of the first flow guiding layer and extends horizontally to the charge collection region; A high potential is applied to the second and first conductive layers to attract photoelectric charges and form a conductive region on the surface of the electrical isolation layer, and a higher potential is applied to the charge collection region to allow the photoelectric charges to be transported along the conductive region to the charge collection region.

2. The photoelectric conversion element according to claim 1, characterized in that: The photoelectric conversion element includes a first current-conducting layer that extends vertically from the substrate surface into the interior of the photoelectric conversion region, and the depth of the first current-conducting layer is less than the depth of the photoelectric conversion region.

3. The photoelectric conversion element according to claim 1, characterized in that: The photoelectric conversion element includes multiple first current guiding layers arranged at intervals. The multiple first current guiding layers extend vertically from the surface of the substrate into the interior of the photoelectric conversion region. The depth of the multiple first current guiding layers is less than the depth of the photoelectric conversion region. All of the multiple first current guiding layers are connected to the second current guiding layer.

4. The photoelectric conversion element according to claim 3, characterized in that: The second current-guiding layer includes a cross-shaped section and a connecting section that connects to the cross-shaped section and extends to the charge collection region. Multiple first current-guiding layers are respectively disposed at the four ends and the cross-shaped section of the cross-shaped section.

5. The photoelectric conversion element according to claim 1, characterized in that: The first current-guiding layer has a long strip shape when projected vertically onto the substrate surface. The second current-guiding layer includes a long strip portion that cooperates with the first current-guiding layer, and a connecting portion that connects to the long strip portion and extends to the charge collection region.

6. The photoelectric conversion element according to claim 1, characterized in that: The first current-guiding layer is annular in shape when projected vertically onto the substrate surface. The second current-guiding layer includes an annular portion that cooperates with the first current-guiding layer and a connecting portion that connects to the annular portion and extends to the charge collection region.

7. The photoelectric conversion element according to claim 6, characterized in that: The ring includes one of a polygonal ring, an elliptical ring, and a circular ring, and the polygonal ring includes one of a triangular ring, a rectangular ring, a rhombus ring, an equilateral hexagonal ring, and an equilateral octagonal ring.

8. The photoelectric conversion element according to claim 1, characterized in that: The photoelectric conversion region includes one of a Pin-type photodiode structure and a photoelectric conversion structure based on a P-type epitaxial layer. The Pin-type photodiode structure includes an n-type region and a surface p-type doped region located on the n-type region. The surface p-type doped region is located around the second current-conducting layer, and the first current-conducting layer extends to the n-type region.

9. The photoelectric conversion element according to claim 1, characterized in that: The area of ​​the photoelectric conversion region is greater than or equal to 100 square micrometers, and the depth is greater than or equal to 10 micrometers.

10. The photoelectric conversion element according to claim 1, characterized in that: The photoelectric conversion element further includes an isolation structure surrounding the photoelectric conversion region and the charge collection region, wherein the depth of the isolation structure is greater than the depth of the charge collection region.

11. The photoelectric conversion element according to claim 1, characterized in that: The first guiding layer is equidistant from the edges of the photoelectric conversion area, and the second guiding layer is equidistant from the edges of the photoelectric conversion area located on both sides thereof.

12. The photoelectric conversion element according to claim 11, characterized in that: The distance between the exposed end of the second flow guiding layer and the edge of the photoelectric conversion region is greater than 0.1 μm.

13. The photoelectric conversion element according to any one of claims 1 to 12, characterized in that: When the photoelectric conversion region is photosensitive and converted into photoelectric charge, the first and second guiding layers apply a first high potential to attract photoelectric charge on the surface of the electrical isolation layer and form a guiding region. The charge collection region applies a second high potential, which is higher than the first high potential, so that the photoelectric charge is transported along the guiding region to the charge collection region.

14. A pixel, characterized in that, The pixels include: The photoelectric conversion element as described in any one of claims 1 to 13; A photoelectric signal readout circuit is connected to the charge collection region.

15. The pixel according to claim 14, characterized in that: The photoelectric signal readout circuit includes one of the following: a circuit structure for acquiring single-phase signals, a circuit structure for acquiring dual-phase signals, and a circuit structure for acquiring four-phase signals.

16. The pixel according to claim 14, characterized in that: The photoelectric signal readout circuit is used to receive and modulate the photoelectric charge generated by the photoelectric conversion element into a phase photoelectric charge signal corresponding to the modulated light wave emitted by the light source emitter, and to convert the phase photoelectric charge signal into a phase photoelectric signal for output.

17. A time-of-flight sensor, characterized in that, The time-of-flight sensor includes: A light source emitter is used to emit modulated light waves toward a target object; A pixel array comprising a plurality of pixels as described in any one of claims 14 to 16, wherein the pixels are configured to receive a modulated light wave reflected by a target object and modulate it into a phase photoelectric charge signal corresponding to the modulated light wave, and convert the phase photoelectric charge signal into a phase photoelectric signal; Control circuitry is used to control the operation of the light source emitter and the pixel array; A readout circuit is used to read the phase photoelectric signals in the pixel array.

18. The time-of-flight sensor according to claim 17, characterized in that: The time-of-flight sensor also includes logic circuitry for processing the phase photoelectric signals read by the readout circuitry to obtain the time information and / or distance information required by the pixel.

19. An electronic device, characterized in that: The electronic device is equipped with a time-of-flight sensor as described in any one of claims 17 to 18.

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