CN215932126U - Photoelectric conversion element, pixel, time-of-flight sensor, and electronic device - Google Patents

Abstract

The utility model provides a photoelectric conversion element, a pixel, a time-of-flight sensor, and an electronic device, the photoelectric conversion element including: a substrate; a photoelectric conversion region disposed in the substrate; a charge collection region disposed in the substrate and disposed adjacent to the photoelectric conversion region; the first current guide layer extends from the surface of the substrate to the inside of the photoelectric conversion region; the second flow guide layer is arranged on the surface of the substrate, is connected with the first flow guide layer and extends to the charge collection region; and an electrical isolation layer disposed at an interface between the first current guiding layer and the substrate and an interface between the second current guiding layer and the substrate. The utility model 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 precision and the distance measurement quality of the flight time sensor.

Description

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

Technical Field

The utility model belongs to the field of photoelectric sensing, and particularly relates to a photoelectric conversion element, a pixel, a time-of-flight sensor and electronic equipment.

Background

A time-of-flight sensor is an important part of a ranging apparatus, and is capable of capturing three-dimensional (3D) distance information of a target object to obtain a 3D image; the method is widely applied to the fields of behavior analysis, monitoring, automatic driving of automobiles, artificial intelligence, machine vision perception, image 3D enhancement and the like. The time-of-flight sensor generally adopts a time-of-flight method, and measures the travel time of light from a light pulse to a receiving end of the sensor after the light pulse is reflected from a light source transmitting end to a target object, so as to determine the distance information of the target object.

The flight time sensor can obtain the travel time of the light by adopting a direct method or an indirect method, wherein the indirect method is to record the phase difference of the time period from the emission to the receiving of the light pulse and further calculate the travel time of the light. Time-of-flight sensors generally include a light source emitting module and a light source sensing module that contains light-sensitive pixels. The light sensing pixels can obtain time data by adopting an indirect method, and each light sensing pixel needs to acquire a phase photoelectric charge signal of a modulated light wave so as to calculate time information.

The photosensitive pixels include photoelectric conversion elements for converting light into charges, generally, the frequency of modulated light waves emitted by a light source is high, for example, up to 100MHz, and when the sensor demodulates phase photoelectric signals, the transmission efficiency of photoelectric charges converted by the conventional photoelectric conversion elements is poor, so that the demodulation contrast performance of the sensor is poor.

SUMMERY OF THE UTILITY MODEL

In view of the above-mentioned drawbacks of the prior art, an object of the present invention is to provide a photoelectric conversion element, a pixel, a time-of-flight sensor, and an electronic device, which are used to solve the problem of low demodulation contrast of the photoelectric sensor due to low photoelectric charge transfer efficiency in the prior art.

To achieve the above and other related objects, the present invention provides a photoelectric conversion element including: a substrate; a photoelectric conversion region disposed in the substrate; a charge collection region disposed in the substrate and disposed adjacent to the photoelectric conversion region; the first current guide layer extends from the surface of the substrate to the inside of the photoelectric conversion region; the second flow guide layer is arranged on the surface of the substrate, is connected with the first flow guide layer and extends to the charge collection area; and an electrical isolation layer disposed at an interface between the first current guiding layer and the substrate and an interface between the second current guiding layer and the substrate.

Optionally, the photoelectric conversion element includes one first current guiding layer, the first current guiding layer extends vertically from the surface of the substrate to the inside of the photoelectric conversion region, and the depth of the first current guiding layer is smaller than that of the photoelectric conversion region.

Optionally, the photoelectric conversion element includes a plurality of first current guiding layers arranged at intervals, the plurality of first current guiding layers extend from the surface of the substrate to the inside of the photoelectric conversion region, the depth of the plurality of first current guiding layers is smaller than the depth of the photoelectric conversion region, and the plurality of first current guiding layers are connected to the second current guiding layer.

Further, the second flow guiding layer comprises a cross-shaped part and a connecting part which is connected with the cross-shaped part and extends to the charge collecting area, and the first flow guiding layers are respectively arranged at four ends and the cross-shaped part of the cross.

Optionally, the first flow guiding layer projects perpendicularly to the surface of the substrate and is in a strip shape, and the second flow guiding layer includes a strip portion arranged in cooperation with the first flow guiding layer and a connecting portion connected to the strip portion and extending to the charge collecting region.

Optionally, the shape of the vertical projection of the first flow guiding layer to the surface of the substrate is annular, and the second flow guiding layer includes an annular portion disposed in cooperation with the first flow guiding layer, and a connecting portion connected to the annular portion and extending to the charge collecting region.

Further, the annular shape 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 diamond ring, an equilateral hexagonal ring, and an equilateral octagonal ring.

Optionally, the photoelectric conversion region includes one of a Pin-type photodiode structure and a P-type epitaxial layer-based photoelectric conversion structure, where 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 correspondingly on the periphery of the second current guiding layer, and the first current guiding layer extends to the n-type region.

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.

Optionally, the photoelectric conversion element further comprises an isolation structure surrounding the photoelectric conversion region and the charge collection region, and the depth of the isolation structure is greater than that of the charge collection region.

Optionally, the first current guiding layer is vertically equidistant from the peripheral edge of the photoelectric conversion region, and the second current guiding layer is vertically equidistant from the edges of the photoelectric conversion region on both sides of the first current guiding layer.

Optionally, a distance between an exposed end of the second guide layer and an edge of the photoelectric conversion region is greater than 0.1 μm.

Optionally, when the photoelectric conversion region is photosensitive and converted into photoelectric charges, the first current guiding layer and the second current guiding layer apply a first high potential to attract the photoelectric charges on the surface layer of the electrical isolation layer and form a current guiding region, and the charge collection region applies a second high potential, wherein the second high potential is higher than the first high potential, so that the photoelectric charges are transmitted to the charge collection region along the current guiding region.

The present invention also provides a pixel, comprising: the photoelectric conversion element according to any one of the above aspects; and a photo signal readout circuit connected to the charge collection region.

Optionally, the optoelectronic signal readout circuit includes one of a circuit structure for collecting single-phase signals, a circuit structure for collecting double-phase signals, and a circuit structure for collecting four-phase signals.

Optionally, the photoelectric signal readout circuit is configured 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.

The present invention also provides a time-of-flight sensor, comprising: a light source emitter for emitting a modulated light wave to a target object; a pixel array including a plurality of pixels according to any one of the above aspects, the pixels being configured to receive a modulated light wave reflected by a target object and modulate the modulated light wave into a phase photoelectric charge signal corresponding to the modulated light wave, 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 the reading circuit is used for reading the phase photoelectric signals in the pixel array.

Optionally, the time-of-flight sensor further includes a logic circuit, configured to process the phase photoelectric signal read by the reading circuit to obtain time information or/and distance information required by the pixel.

Optionally, the pixels in the pixel array are arranged in a rectangular array, each column of pixels of the pixel array is connected to the reading circuit by at least one signal line, and the manner of reading the phase photoelectric signals of the pixel array by the reading circuit includes one of row rolling manner reading, selecting a part of pixels for reading, and global reading.

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 wave pulse light wave.

The utility model also provides an electronic device, which is provided with the time-of-flight sensor.

As described above, the photoelectric conversion element, the pixel, the time-of-flight sensor, and the electronic device according to the present invention have the following advantageous effects:

in the photoelectric conversion element, in the process of modulating phase photoelectric signals by pixels, the first current guide layer is set to be at a high potential so as to form a high electric field gradient around the first current guide layer, so that photoelectric charges generated in the photoelectric conversion element can be quickly attracted to the current guide area near the first current guide layer, and a high-speed current guide path of the photoelectric charges is formed jointly by combining the current guide area of the second current guide layer on the surface of the photoelectric conversion element, so that the photoelectric charges generated in the phase time period of modulated light waves can be quickly guided to the charge collection area, the problem that the photoelectric charges are retained to a next phase signal and are collected by the next phase signal due to low transmission speed of the phase photoelectric charges is solved, the miscollection between adjacent phase photoelectric charges is eliminated, and the purity of the phase photoelectric signals is improved. The utility model 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 precision and the distance measurement quality of the flight time sensor.

Drawings

Fig. 1 to 2 are schematic structural diagrams of a photoelectric conversion element according to an embodiment of the present invention.

Fig. 3 to 4 are schematic structural diagrams of a photoelectric conversion element according to another embodiment of the present invention.

Fig. 5 to 6 are schematic structural diagrams of a photoelectric conversion element according to still another embodiment of the present invention.

Fig. 7 to 8 are schematic structural diagrams of a photoelectric conversion element according to still another embodiment of the present invention.

Fig. 9 is a schematic view of a photoelectric conversion element according to an embodiment of the present invention.

Fig. 10 is a schematic structural diagram of a pixel according to an embodiment of the utility model.

Fig. 11 is a schematic structural diagram of a time-of-flight sensor according to an embodiment of the present invention.

Description of the element reference numerals

100 time-of-flight sensor

101 pixel array

102 read circuit

103 control circuit

104 light source emitter

105 logic circuit

200 pixels

201 photoelectric conversion element

202 photoelectric signal reading circuit

300 substrate

301 photoelectric conversion region

302a, 302b, 302c, 302d second flow guiding layer

303a, 303b, 303c, 303d, a second flow guiding layer

303e、303f、303g

304 charge collection region

305 isolation structure

401a, 401b, 401c, 401d electrical isolation layer

501a cross section

501b long strip part

501c annular portion

502a, 502b, 502c connection

Detailed Description

The embodiments of the present invention are described below with reference to specific embodiments, and other advantages and effects of the present invention will be easily understood by those skilled in the art from the disclosure of the present specification. The utility model is capable of other and different embodiments and of being practiced or of being carried out in various ways, and its several details are capable of modification in various respects, all without departing from the spirit and scope of the present invention.

As in the detailed description of the embodiments of the present invention, the cross-sectional views illustrating the device structures are not partially enlarged in general scale for convenience of illustration, and the schematic views are only examples, which should not limit the scope of the present invention. In addition, the three-dimensional dimensions of length, width and depth should be included in the actual fabrication.

For convenience in description, spatial relational terms such as "below," "beneath," "below," "under," "over," "upper," and the like may be used herein to describe one element or feature's relationship to another element or feature as illustrated in the figures. It will be understood that these terms of spatial relationship are intended to encompass other orientations of the device in use or operation in addition to the orientation depicted in the figures. Further, when a layer is referred to as being "between" two layers, it can be the only layer between the two layers, or one or more intervening layers may also be present.

In the context of this application, a structure described as having a first feature "on" a second feature may include embodiments in which the first and second features are formed in direct contact, and may also include embodiments in which additional features are formed in between the first and second features, such that the first and second features may not be in direct contact.

It should be noted that the drawings provided in the present embodiment are only for illustrating the basic idea of the present invention, and the drawings only show the components related to the present invention rather than being drawn according to the number, shape and size of the components in actual implementation, and the type, quantity and proportion of each component in actual implementation may be changed arbitrarily, and the layout of the components may be more complicated.

The photosensitive pixel comprises a photoelectric conversion element for converting light waves into photoelectric charges; in the time-of-flight sensor, since the light source generally employs near-infrared light, the wavelength of the light is long, the photoelectric conversion element has low conversion efficiency for the near-infrared light with respect to visible light, and the absorption path of the light required for the near-infrared light is long, the photoelectric conversion element is generally large in area and deep, for example, the photoelectric conversion element has an area larger than 50 square micrometers and a depth larger than 10 micrometers.

However, the frequency of the modulated light wave emitted by the light source is usually high, which can be as high as 100MHz, and when the sensor is used for demodulating the phase photoelectric signal, the photoelectric conversion element with a large area and a deep depth has poor transmission efficiency of the photoelectric charges converted, which results in poor demodulation contrast performance of the sensor.

In order to solve the above problem, as shown in fig. 1 to 9, an embodiment provides a photoelectric conversion element 201, the photoelectric conversion element 201 including: a substrate 300, a photoelectric conversion region 301, a charge collection region 304, a first current guiding layer, a second current guiding layer and an electrical isolation layer.

The material of the substrate 300 may be silicon, germanium, silicon on insulator, germanium on insulator, silicon carbide, iii-v semiconductor compound, or the like. In the present embodiment, the material of the substrate 300 is selected to be silicon.

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

As an example, the photoelectric conversion region 301 includes one of a Pin-type photodiode structure and a P-type epitaxial layer-based photoelectric conversion structure.

In one example, the substrate 300 is a P-type doped silicon substrate to which a dopant, which may be phosphorus or arsenic, etc., is implanted to form a P-type epitaxial layer type structure to form the electrical conversion charge region.

In another example, the electrically converting charge region may be the same as the P-doped silicon substrate, without implanted dopants, i.e., the electrically converting charge region is an intrinsic undoped P-type epitaxial layer type structure.

In a further embodiment, the electrical conversion charge region may 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 for preventing a leakage current of the Pin-type photodiode, the surface P-type doped region is located at a periphery of the second current guiding layer, and the first current guiding layer extends to the n-type region.

In one embodiment, in order to effectively increase the absorption path length of the photoelectric conversion region for light waves and satisfy 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. Further, the area of the photoelectric conversion region 301 may be set to be greater than or equal to 200 square micrometers.

The charge collection region 304 is disposed in the substrate 300 and is disposed adjacent to the photoelectric conversion region 301. In one example, a dopant is implanted into the charge collection region 304, which may be phosphorous or arsenic. The photoelectric conversion element 201 further comprises an isolation structure 305 surrounding the photoelectric conversion region 301 and the charge collection region 304, wherein the depth of the isolation structure 305 is greater than the depth of the charge collection region 304, so as to prevent the charge collection region 304 from coupling to affect the operation of other devices when the photoelectric conversion element 201 is in operation.

The first current guiding layer extends from the surface of the substrate 300 to the inside of the photoelectric conversion region 301; the second current guiding layer is disposed on the surface of the substrate 300, connected to the first current guiding layer and extending to the charge collecting region 304; the electrically isolating layers are disposed at an interface between the first current guiding layer and the substrate 300 and an interface between the second current guiding layer and the substrate 300. When the photoelectric conversion region 301 is photosensitive and converted into photoelectric charges, the first current guiding layer and the second current guiding layer apply a first high potential to attract the photoelectric charges on the surface layer of the electrical isolation layer and form a current guiding region, and the charge collecting region 304 applies a second high potential, which is higher than the first high potential, so that the photoelectric charges are transmitted to the charge collecting region 304 along the current guiding region.

As an example, the material of the first current guiding layer and the second current guiding layer may be polysilicon, and the material of the electrical isolation layer may be silicon dioxide. Of course, in other embodiments, the material of the first current guiding layer and the second current guiding layer may also be other conductive materials, such as metal materials, and the electrical isolation layer may also be other dielectric materials, such as high-K dielectric.

In an embodiment, as shown in fig. 1 to fig. 2, fig. 1 is a schematic top view of the photoelectric conversion element 201, and fig. 2 is a schematic cross-sectional view of fig. 1 taken along a-a'. The photoelectric conversion element 201 includes one first current guiding layer 303a, the first current guiding layer 303a extending vertically from the surface of the substrate 300 to the inside of the photoelectric conversion region 301 to play a role of responding to and attracting the generation of the photoelectric charges in the depth of the photoelectric conversion region 301, the depth of the first current guiding layer 303a being smaller than the depth of the photoelectric conversion region 301, and the vertical distance from the first current guiding layer 303a to the peripheral edge of the photoelectric conversion region 301 being equal, and one second current guiding layer 302a, the second current guiding layer 302a being connected to the upper surface of the first current guiding layer 303a and extending horizontally to the charge collecting region 304, and the vertical distance from the second current guiding layer 302a to the edge of the photoelectric conversion region 301 located on both sides thereof being equal. The electrically isolating layer 401a is disposed at an interface between the first current guiding layer and the substrate 300 and an interface between the second current guiding layer and the substrate 300. In this embodiment, the first current guiding layer 303a and the second current guiding layer 302a form a "T" shape on a cross section cut along a-a', and both of them together function as a current guiding path for rapidly transmitting photoelectric charges.

In one embodiment, the distance between the exposed end of the second current guiding layer 302a and the edge of the photoelectric conversion region 301 is greater than 0.1 μm, for example, the distance may be 0.1 μm, 0.15 μm, 0.2 μm, 0.5 μm, or the like, so as to increase the photosensitive area of the photoelectric conversion region 301.

In another embodiment, as shown in fig. 3 to 4, fig. 3 is a schematic top view of the photoelectric conversion element 201, and fig. 4 is a schematic cross-sectional view of the photoelectric conversion element taken along B-B' in fig. 3. The photoelectric conversion element 201 comprises a plurality of first current guide layers which are arranged at intervals, the first current guide layers vertically extend to the inside of the photoelectric conversion area 301 from the surface of the substrate 300, the depth of the first current guide layers is smaller than that of the photoelectric conversion area 301, and the first current guide layers are connected with the second current guide layers. Further, the second flow guiding layer includes a cross portion 501a and a connecting portion 502a connected to the cross portion 501a and extending to the charge collecting region 304, and the plurality of first flow guiding layers are respectively disposed at four end portions and a cross portion of the cross. As shown in fig. 4, the plurality of first guiding layers 303a, 303b, 303d and the second guiding layer 302b have a three-pointed finger structure, and similarly, the plurality of first guiding layers 303a, 303c, 303e and the second guiding layer 302b can also form a three-pointed finger structure on another cutting section (not shown in the diagram); the depth of the first current guiding layer 303a, 303b, 303c, 303d, 303e is smaller than the depth of the photoelectric conversion region 301; the first current guiding layers 303a, 303b, 303c, 303d, 303e are distributed uniformly in the photoelectric conversion region 301, the distance from the first current guiding layer 303a to the first current guiding layer 303c is equal to the distance from 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 from the first current guiding layer 303d, and the vertical distances from the first current guiding layers 302b, 303d, 303c, 303e to the edge of the photoelectric conversion region 301 are equal or equivalent. The electrically isolating layer 401b is disposed at an interface between the first current guiding layer and the substrate 300 and an interface between the second current guiding layer and the substrate 300. The structure of this example can be used for a larger area of the 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, and the photoelectric conversion region 301 covered by the first current guiding layers 303a, 303b, 303c, 303d, and 303e of the three-finger-shaped structure is wider, which is beneficial to rapidly attracting the photoelectric charges generated in the larger area of the photoelectric conversion region 301 to the vicinity of the current guiding region on the surface thereof, and effectively improving the transmission efficiency of the photoelectric charges.

In yet another embodiment, as shown in fig. 5 to 6, fig. 5 is a schematic top view of the photoelectric conversion element 201, and fig. 6 is a schematic cross-sectional view of fig. 5 taken along C-C'. The first flow guiding layer is vertically projected to the surface of the substrate 300 and has a strip shape, and the second flow guiding layer includes a strip portion 501b provided in cooperation with the first flow guiding layer, and a connecting portion 502b connected to the strip portion 501b and extending to the charge collecting region 304. Specifically, as shown in fig. 5, the first current guiding layer 303f and the second current guiding layer 302c are both in a shape of a "straight" long strip and are located at a position laterally intermediate to the surface of the photoelectric conversion region 301, as shown in fig. 6, the first current guiding layer 303f extends vertically from the surface of the substrate 300 to the inside of the photoelectric conversion region 301 to present a wall structure, the depth of the first current guiding layer 303f is smaller than the depth of the photoelectric conversion region 301, and two side surfaces of the first current guiding layer 303f are at the same vertical distance from the edge of the photoelectric conversion region 301. The electrically isolating layer 401c is disposed at an interface between the first current guiding layer and the substrate 300 and an interface between the second current guiding layer and the substrate 300. The first current guiding layer 303f of the wall structure of this example is more favorable for forming a strong electric field in the vicinity thereof, and the first current guiding layer 303f more effectively and rapidly attracts photoelectric charges generated in the photoelectric conversion region 301 to the vicinity of the surface current guiding region thereof, thereby improving the transmission efficiency of the photoelectric charges.

In yet another embodiment, as shown in fig. 7 to 8, fig. 7 is a schematic top view of the photoelectric conversion element 201, and fig. 8 is a schematic cross-sectional view of the photoelectric conversion element taken along D-D' in fig. 7. The first current guiding layer is vertically projected to the surface of the substrate 300 and has a ring shape, and the second current guiding layer includes a ring portion 501c disposed in cooperation with the first current guiding layer, and a connecting portion 502c connected to the ring portion 501c and extending to the charge collecting region 304. For example, the annular shape 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 diamond ring, an equilateral hexagonal ring, and an equilateral octagonal ring, and in the present embodiment, the annular shape is a rectangular ring. Of course, in practical applications, the ring shape may be employed as long as it has uniform critical dimensions and shape.

As shown in fig. 7, the second current guiding layer 302d has a rectangular shape (annular portion 501c) with a handle (connecting portion 502c) at a middle position of the surface of the photoelectric conversion region 301, and the first current guiding layer 303g has a rectangular loop shape, when the surface of the photoelectric conversion element 201 is viewed in plan. Along a cross section cut at D-D' of fig. 7, as shown in fig. 8, the first current guiding layer 303g and the second current guiding layer 302D present a similar frame structure, the depth of the first current guiding layer 303g is smaller than the depth of the photoelectric conversion region 301, and the vertical distances from the first current guiding layers 303g at two sides to two side edges of the photoelectric conversion region 301 are the same. The electrically isolating layer 401d is disposed at an interface between the first current guiding layer and the substrate 300 and an interface between the second current guiding layer and the substrate 300. This embodiment can form a strong electric field in the photoelectric conversion region 301 near the first current guiding layer 303g, and the first current guiding layer 303g can effectively and rapidly attract the photoelectric charges generated in the photoelectric conversion region 301 to the vicinity of the current guiding region on the surface thereof, thereby improving the transmission efficiency of the photoelectric charges.

The structure of the photoelectric conversion element 201 of each of the embodiments shown in fig. 1 to 8 described above can effectively improve the efficiency of transferring the photoelectric charges generated in the photoelectric conversion region 301 of the photoelectric conversion element 201 to the charge collection region 304, and is described in detail with reference to the examples shown in fig. 1 to 2, and the specific principle thereof is shown in fig. 9.

As shown in fig. 9, when the optical wave phase photoelectric charge signal is modulated, the photoelectric conversion region 301 receives an optical wave and converts the optical wave into photoelectric charges, the second current guiding layer 302a and the first current guiding layer 303a give a high potential, for example, 1.2V or 1.8V, and a high electric field region is formed near the surface current guiding regions of the second current guiding layer 302a and the first current guiding layer 303a, as shown in fig. 9. In fig. 9, in the photoelectric conversion region 301, electric field lines are directed away from the second current guiding layer 302a and the first current guiding layer 303a, and the closer to the second current guiding layer 302a and the first current guiding layer 303a, the higher the electric potential, the photoelectric charges in the photoelectric conversion region 301 rapidly move from the far to the vicinity of the current guiding regions of the second current guiding layer 302a and the first current guiding layer 303a under the action of a high electric field, because the electric potential given to the charge collecting region 304 is higher, the photoelectric charges are rapidly transferred to the charge collection region 304 along the conduction region of the first conduction layer 303a from bottom to top, then along the conduction region of the second conduction layer 302a from left to right, therefore, the problem that the photoelectric charges are retained to the next phase signal and are collected by the next phase signal due to the low transmission speed of the photoelectric charges of the phases is avoided, the problem of mistaken collection between the photoelectric charges of adjacent phases is solved, and the purity of the photoelectric signals of the phases is improved. Therefore, the present invention effectively enhances the transmission efficiency of photoelectric charges generated by the photoelectric conversion element 201, improves the demodulation contrast performance of the sensor, and effectively enhances the time accuracy and the ranging quality of the sensor.

As shown in fig. 10, the present embodiment further provides a pixel 200, where the pixel 200 includes: the photoelectric conversion element 201 as described in the above embodiment, configured to receive the modulated lightwave signal reflected back from the target object, and convert the modulated lightwave signal into photoelectric charges; and a photo signal readout circuit 202, said photo signal readout circuit 202 being connected to said charge collection region 304.

The photo signal readout circuit 202 includes a plurality of transistor devices (e.g., a transmission transistor TX, a reset transistor RST, a source follower transistor SF, and a row selection transistor RS, in an example, the charge collection region 304 serves as a source of the transmission transistor TX) to achieve a function of collecting a phase photo signal modulating a phase of a light wave, and the circuit for collecting a photo signal alone may be a circuit structure for collecting a single phase signal (single tap), a circuit structure for collecting a dual phase signal (double tap), or a circuit structure for collecting a four phase signal (four tap). The photoelectric signal readout circuit 202 is configured 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.

As shown in fig. 11, the present embodiment further provides a time-of-flight sensor 100, where the time-of-flight sensor 100 includes: a light source emitter 104 for emitting modulated light waves towards a target object; a pixel array 101, including a plurality of pixels 200 as described in the above embodiments, where the pixels 200 are configured to receive a modulated light wave reflected by a target object and modulate the modulated light wave into a phase photoelectric charge signal corresponding to the modulated light wave, and convert the phase photoelectric charge signal into a phase photoelectric signal, so as to obtain a flight time based on the phase photoelectric signal, thereby obtaining required distance information through calculation; a control circuit 103 for controlling the operation of the light source emitter 104 and the pixel array 101; a reading circuit 102, configured to read the phase photoelectric signal in the pixel array 101.

In one embodiment, the light source emitters 104 comprise one of vertical cavity surface emitting lasers, edge emitting lasers, and light emitting diodes, and the modulated light waves comprise one of sinusoidal modulated light waves and square wave pulsed light waves, which are near infrared light waves.

As an example, the pixels 200 in the pixel array 101 are arranged in a rectangular array, and as shown in fig. 11, the pixels 200P1, P2, …, Pn form a rectangular array on a two-dimensional structure, and the pixels 200 are arranged in rows (for example, rows R1 to Ry) and columns (for example, columns C1 to Cx) in the present embodiment to acquire phase photoelectric charge signals of a target object or a person or an object or the like, and then a distance depth 3D data image of the target object or the person or the object or the like can be reproduced using the phase photoelectric charge signals. However, in other examples, it should be appreciated that the pixels 200 need not be arranged in rows and columns, and other configurations may be employed.

For the pixel array 101 arranged in the rectangular array, each column of pixels 200 of the pixel array 101 is connected to the reading circuit 102 by at least one signal line, and the way for the reading circuit 102 to read the phase photoelectric signals of the pixel array 101 includes one of reading in a row rolling manner, selecting a part of the pixels 200 to read, and reading globally. I.e., the readout circuitry may readout a row of phase photoelectric charge signals at a time along readout column lines or may readout the phase photoelectric charge signals using a variety of other techniques such as serial readout or readout of all pixels 200 all in parallel at the same time. The read circuit 102 may include an amplification circuit, an analog-to-digital (ADC) conversion circuit, or other circuits.

In one example, each pixel 200 in the pixel array 101 remains globally operational; the control circuit 103 is coupled to the pixel array 101 to control the operation of a plurality of pixels 200 in the pixel array 101. For example, the control circuit 103 may generate a shutter signal for controlling the modulated lightwave phase photoelectric charges. In one example, the shutter signal is a global shutter signal that is used to simultaneously enable all pixels 200 within the pixel array 101 to simultaneously capture the respective modulated lightwave phase optoelectronic signals of all pixels 200 during a single acquisition window.

In another example, the phase photo-signal data acquired by the pixel array 101 required for calculating time is kept synchronized with the periodic light waves emitted by the light source emitter 104, the synchronized operation of the pixel array 101 and the light source emitter 104, and controlled by the control circuit 103.

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

The present embodiment also provides an electronic device configured with the time-of-flight sensor 100 as described in the embodiments.

In one example, the time-of-flight sensor 100 may be included in automotive radar, cell phone ranging, machine vision, and the like. In addition, the time of flight sensor 100 system can also be coupled to other hardware parts, such as toys, drones, surveillance cameras, etc. Other hardware parts may communicate instructions to the time-of-flight sensor 100, extract phase photoelectric charge signals required for 3D images from the time-of-flight sensor 100 or manipulate the phase photoelectric charge signals supplied by the time-of-flight sensor 100 system.

As described above, the photoelectric conversion element, the pixel, the time-of-flight sensor, and the electronic device according to the present invention have the following advantageous effects:

in the photoelectric conversion element, in the process of modulating phase photoelectric signals by pixels, the first current guide layer is set to be at a high potential so as to form a high electric field gradient around the first current guide layer, so that photoelectric charges generated in the photoelectric conversion element can be quickly attracted to the current guide area near the first current guide layer, and a high-speed current guide path of the photoelectric charges is formed jointly by combining the current guide area of the second current guide layer on the surface of the photoelectric conversion element, so that the photoelectric charges generated in the phase time period of modulated light waves can be quickly guided to the charge collection area, the problem that the photoelectric charges are retained to a next phase signal and are collected by the next phase signal due to low transmission speed of the phase photoelectric charges is solved, the miscollection between adjacent phase photoelectric charges is eliminated, and the purity of the phase photoelectric signals is improved. The utility model 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 precision and the distance measurement quality of the flight time sensor.

The foregoing embodiments are merely illustrative of the principles and utilities of the present invention and are not intended to limit the utility model. Any person skilled in the art can modify or change the above-mentioned embodiments without departing from the spirit and scope of the present invention. Accordingly, it is intended that all equivalent modifications or changes which can be made by those skilled in the art without departing from the spirit and technical spirit of the present invention be covered by the claims of the present invention.

Claims (19)

1. A photoelectric conversion element characterized by comprising:

a substrate;

a photoelectric conversion region disposed in the substrate;

a charge collection region disposed in the substrate and disposed adjacent to the photoelectric conversion region;

the first current guide layer extends from the surface of the substrate to the inside of the photoelectric conversion region;

the second flow guide layer is arranged on the surface of the substrate, is connected with the first flow guide layer and extends to the charge collection area;

and the electric isolation layer is arranged at the interface between the first current guide layer and the substrate and the interface between the second current guide layer and the substrate.

2. The photoelectric conversion element according to claim 1, wherein: the photoelectric conversion element comprises one first current guide layer, the first current guide layer vertically extends from the surface of the substrate to the inside of the photoelectric conversion region, and the depth of the first current guide layer is smaller than that of the photoelectric conversion region.

3. The photoelectric conversion element according to claim 1, wherein: photoelectric conversion component includes many first water conservancy diversion layers that the interval was arranged, many first water conservancy diversion layer certainly the surface of the substrate extends to perpendicularly inside the photoelectric conversion district, many the degree of depth on first water conservancy diversion layer is less than the degree of depth in photoelectric conversion district, many first water conservancy diversion layer utmost point all with the second water conservancy diversion layer is connected.

4. The photoelectric conversion element according to claim 3, wherein: the second flow guide layer comprises a cross-shaped part and a connecting part which is connected with the cross-shaped part and extends to the charge collecting area, and the first flow guide layers are respectively arranged at four ends and the cross-shaped part of the cross.

5. The photoelectric conversion element according to claim 1, wherein: the first diversion layer vertical projection to the shape of the substrate surface is a long strip, the second diversion layer comprises a long strip portion and a connecting portion, the long strip portion is matched with the first diversion layer, the connecting portion is connected with the long strip portion and extends to the charge collecting region.

6. The photoelectric conversion element according to claim 1, wherein: the first diversion layer vertical projection is annular in shape on the surface of the substrate, and the second diversion layer comprises an annular part matched with the first diversion layer and a connecting part connected with the annular part and extending to the charge collecting region.

7. The photoelectric conversion element according to claim 6, wherein: the annular shape 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 diamond ring, an equilateral hexagonal ring, and an equilateral octagonal ring.

8. The photoelectric conversion element according to claim 1, wherein: the photoelectric conversion region comprises 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 comprises an n type region and a surface P type doped region located on the n type region, the surface P type doped region is correspondingly located on the periphery of the second current guide layer, and the first current guide layer extends to the n type region.

9. The photoelectric conversion element according to claim 1, wherein: the photoelectric conversion region has an area greater than or equal to 100 square micrometers and a depth greater than or equal to 10 micrometers.

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

11. The photoelectric conversion element according to claim 1, wherein: the first current guiding layer is equal to the edge of the periphery of the photoelectric conversion region in vertical distance, and the second current guiding layer is equal to the edge of the photoelectric conversion region on two sides of the second current guiding layer in vertical distance.

12. The photoelectric conversion element according to claim 11, wherein: the distance between the exposed end part of the second diversion layer and the edge of the photoelectric conversion region is larger than 0.1 μm.

13. The photoelectric conversion element according to any one of claims 1 to 12, wherein: when the photoelectric conversion region is photosensitive and converted into photoelectric charges, the first current guide layer and the second current guide layer apply a first high potential to attract the photoelectric charges on the surface layer of the electric isolation layer and form a current guide region, and the charge collection region applies a second high potential which is higher than the first high potential so that the photoelectric charges are transmitted to the charge collection region along the current guide region.

14. A pixel, comprising:

the photoelectric conversion element according to any one of claims 1 to 13;

a photo signal readout circuit connected to the charge collection region.

15. The pixel of claim 14, wherein: the photoelectric signal reading circuit comprises one of a circuit structure for collecting single-phase signals, a circuit structure for collecting double-phase signals and a circuit structure for collecting four-phase signals.

16. The pixel of claim 14, wherein: the photoelectric signal reading circuit is used for receiving and modulating the photoelectric charges generated by the photoelectric conversion element into phase photoelectric charge signals corresponding to the modulated light waves emitted by the light source emitter, and converting the phase photoelectric charge signals into phase photoelectric signals to be output.

17. A time-of-flight sensor, comprising:

a light source emitter for emitting a modulated light wave to a target object;

a pixel array comprising a plurality of pixels according to any one of claims 14 to 16 for receiving a modulated light wave reflected by a target object and modulating it into a phase photoelectric charge signal corresponding to the modulated light wave, and converting 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 the reading circuit is used for reading the phase photoelectric signals in the pixel array.

18. The time-of-flight sensor of claim 17, wherein: the time-of-flight sensor further comprises a logic circuit, and the logic circuit is used for processing the phase photoelectric signals read by the reading circuit to obtain time information or/and distance information required by the pixels.

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

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