阅读说明：本技术 一种图像传感器和电子设备 (Image sensor and electronic equipment ) 是由 雷述宇 于 2020-06-28 设计创作，主要内容包括：本申请提供了一种图像传感器和电子设备,图像传感器包括：第一基板,包括像素阵列,所述像素阵列由像素单元构成,所述像素单元包括：光电转换装置,传输装置和第一电荷存储装置,所述光电转换装置用于接收光信号并生成光生电子,所述传输装置用于控制所述光生电子的传输,所述电荷存储装置用于存储传输装置传输的所述光生电子；第二基板,包括第二电荷存储装置和处理电路,所述第二电荷存储装置,所述处理电路用于处理所述第一电荷存储装置和第二电荷装置中存储的所述光生电子。(The application provides an image sensor and electronic equipment, image sensor includes: a first substrate including a pixel array, the pixel array being formed of pixel units, the pixel units including: a photoelectric conversion device for receiving an optical signal and generating photo-generated electrons, a transfer device for controlling the transfer of the photo-generated electrons, and a first charge storage device for storing the photo-generated electrons transferred by the transfer device; a second substrate comprising a second charge storage device and processing circuitry for processing the photo-generated electrons stored in the first and second charge storage devices.)

1. An image sensor, comprising:

a first substrate including a pixel array, the pixel array being formed of pixel units, the pixel units including:

a photoelectric conversion device for receiving an optical signal and generating photo-generated electrons, a transfer device for controlling the transfer of the photo-generated electrons, and a first charge storage device for storing the photo-generated electrons transferred by the transfer device;

a second substrate comprising a second charge storage device and processing circuitry for processing the photo-generated electrons stored in the first and second charge storage devices.

2. The image sensor of claim 1, the second charge storage device having a storage capacity greater than a storage capacity of the first charge storage device.

3. The image sensor of claim 1 or 2, said pixel cell comprising at least two of said transfer devices and at least two of said first charge storage devices.

4. The image sensor of claim 3, said processing circuitry comprising a reset means for resetting said second charge storage means, a readout means for processing and reading out photo-generated electrons in said charge storage means.

5. The image sensor of claim 4, the first and second substrates being distributed along a vertical direction, the first and second substrates being connected by a bonding conductor, the first and second charge storage devices being electrically connected by a bonding conductor.

6. An electronic device, the electronic device comprising:

a light source for emitting a light signal to a target object;

an image sensor for receiving the optical signal reflected by the target object and generating an electrical signal,

wherein the image sensor includes:

a first substrate including a pixel array constituted by pixel units including a photoelectric conversion device for receiving an optical signal and generating photo-generated electrons, a transfer device for controlling transfer of the photo-generated electrons, and a first charge storage device for storing the photo-generated electrons transferred by the transfer device;

a second substrate comprising a second charge storage device and processing circuitry for processing the photo-generated electrons stored in the first and second charge storage devices.

7. The electronic device of claim 6, the storage capacity of the second charge storage device being greater than the storage capacity of the first charge storage device.

8. An electronic device as claimed in claim 7, the pixel cell comprising at least two of the transfer means and at least two of the first charge storage means.

9. An electronic device as claimed in claim 8, the processing circuit comprising reset means for resetting the second charge storage means, read-out means for processing and reading out the photo-generated electrons in the charge storage means.

10. The electronic device of claim 9, the first substrate and the second substrate being distributed along a vertical direction, the first substrate and the second substrate being connected by a bonding conductor, the first charge storage device and the second charge storage device being electrically connected by a bonding conductor.

Technical Field

The present disclosure relates to the field of image sensors, and more particularly, to an image sensor and an electronic device.

Background

Time of flight (TOF) is a method of finding a distance to an object by continuously transmitting light pulses to the object, receiving light returning from the object with a sensor, and detecting the Time of flight (round trip) of the light pulses.

While Indirect Time of flight (ITOF) is one of TOF, the ITOF technique determines distance information of an object to be measured by measuring the delay of a round trip Time by actively illuminating the object to be measured, i.e. converting the delay information into distance information using a ranging equation of ITOF. In the ranging equation, several different phase information of the reflected signal are typically involved, i.e. the distance of the target object is determined from the phase information. The phase information is generally converted into an electrical signal by a photoelectric conversion device in the sensor, the electrical signal needs to be stored in a charge storage device, and the charge storage device has a large capacity unlike a non-ranging image sensor, and in the sensor, because the layout area of a chip is limited, too much charge storage device consumes too much chip area, which results in reduction of residual area and reduction of circuit scale.

Disclosure of Invention

An object of the present application is to provide an image sensor and an electronic device, which are used for overcoming the defects in the prior art, and the embodiment of the present application adopts the following technical solutions:

in a first aspect, an embodiment of the present application provides an image sensor, including: a first substrate including a pixel array, the pixel array being formed of pixel units, the pixel units including: a photoelectric conversion device for receiving an optical signal and generating photo-generated electrons, a transfer device for controlling the transfer of the photo-generated electrons, and a first charge storage device for storing the photo-generated electrons transferred by the transfer device; a second substrate comprising a second charge storage device and processing circuitry for processing the photo-generated electrons stored in the first and second charge storage devices.

Optionally, the storage capacity of the second charge storage device is greater than the storage capacity of the first charge storage device.

Optionally, the pixel cell comprises at least two of the transfer devices and at least two of the first charge storage devices.

Optionally, the processing circuit comprises a reset means for resetting the second charge storage means, a readout means for processing and reading out photo-generated electrons in the charge storage means.

Optionally, the first substrate and the second substrate are distributed along a vertical direction, the first substrate and the second substrate are connected by a bonding conductor, and the first charge storage device and the second charge storage device are electrically connected by the bonding conductor.

In a second aspect, an embodiment of the present application provides an electronic device, including: a light source for emitting a light signal to a target object; an image sensor for receiving an optical signal reflected by the target object and generating an electrical signal, wherein the image sensor comprises: a first substrate including a pixel array constituted by pixel units including a photoelectric conversion device for receiving an optical signal and generating photo-generated electrons, a transfer device for controlling transfer of the photo-generated electrons, and a first charge storage device for storing the photo-generated electrons transferred by the transfer device; a second substrate comprising a second charge storage device and processing circuitry for processing the photo-generated electrons stored in the first and second charge storage devices.

Optionally, the storage capacity of the second charge storage device is greater than the storage capacity of the first charge storage device.

Optionally, the pixel cell comprises at least two of the transfer devices and at least two of the first charge storage devices.

Optionally, the processing circuit comprises a reset means for resetting the second charge storage means, a readout means for processing and reading out photo-generated electrons in the charge storage means.

Optionally, the first substrate and the second substrate are distributed along a vertical direction, the first substrate and the second substrate are connected by a bonding conductor, and the first charge storage device and the second charge storage device are electrically connected by the bonding conductor.

The beneficial effect of this application is:

an image sensor provided in an embodiment of the present application includes: a first substrate including a pixel array, the pixel array being formed of pixel units, the pixel units including: a photoelectric conversion device for receiving an optical signal and generating photo-generated electrons, a transfer device for controlling the transfer of the photo-generated electrons, and a first charge storage device for storing the photo-generated electrons transferred by the transfer device; a second substrate comprising a second charge storage device and processing circuitry for processing the photo-generated electrons stored in the first and second charge storage devices. In this way, the purpose of distributing the memory devices on the two substrates is achieved, and therefore, the area of the sensor and the circuit can be increased to some extent, the scale of the circuit can be increased, and the cost of the substrate can be saved.

Drawings

In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings that are required to be used in the embodiments will be briefly described below, it should be understood that the following drawings only illustrate some embodiments of the present application and therefore should not be considered as limiting the scope, and for those skilled in the art, other related drawings can be obtained from the drawings without inventive effort.

Fig. 1 is a schematic block diagram of ITOF ranging provided in an embodiment of the present application;

fig. 2 is a block diagram of a pixel unit in an image sensor according to an embodiment of the present disclosure;

fig. 3 is a circuit and a timing diagram of a pixel unit in an image sensor according to an embodiment of the present disclosure;

FIG. 4 is a circuit diagram and a timing diagram of a pixel unit in another image sensor according to an embodiment of the present disclosure;

FIG. 5 is a side view of another image sensor provided in an embodiment of the present application

Fig. 6 is a schematic diagram of another image sensor provided in an embodiment of the present application.

Detailed Description

In order to make the objects, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application, and it is obvious that the described embodiments are some embodiments of the present application, but not all embodiments. The components of the embodiments of the present application, generally described and illustrated in the figures herein, can be arranged and designed in a wide variety of different configurations.

Thus, the following detailed description of the embodiments of the present application, presented in the accompanying drawings, is not intended to limit the scope of the claimed application, but is merely representative of selected embodiments of the application. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present application.

It should be noted that: like reference numbers and letters refer to like items in the following figures, and thus, once an item is defined in one figure, it need not be further defined and explained in subsequent figures.

In recent years, research into 3D imaging systems has been greatly advanced in order for automated driving to be able to be applied in life. The imaging system in automatic driving is mainly required by the following points: the image sensor has the advantages of resisting large background light (the sunlight is strongest by 100klux), improving the distance measurement precision and quickly measuring the distance, so that a pixel circuit in the image sensor is needed to reduce the waste of the area in a pixel and complete partial calculation when the circuit works, the received signals can more comprehensively improve the distance measurement precision, the pressure of the subsequent data processing is reduced, the time of partial data processing is saved, and the distance between the image sensor and an object can be quickly obtained.

Fig. 1 is a general TOF ranging diagram, which obtains the flight time between a sensor and an object to be measured by using the phase difference between a transmitted light signal and an echo signal, and then calculates to obtain distance information. As shown, a beam of emitted light signals is emitted from a light source 101. The emitted light signal may be a laser pulse signal modulated by a pseudo-random sequence or a common laser pulse signal. The emitted optical signal is reflected by the object 102 and focused by the lens 103 on the pixels of the image sensor 104. The signals received by the image sensor are echo signals and background light signals or only background light signals, and the background light signals are assumed to be uniform within a certain time. The received signal is subjected to signal cancellation or signal extraction through a pixel circuit in the image sensor 104, a background light part is removed, a pure echo signal is obtained, and finally, the phase shift of the echo signal relative to the emitted light signal in the returned light is detected through each pixel, so that the distance of the surrounding object can be detected.

Since the image sensor 104 needs to receive the echo signal, perform phase modulation and processing on the echo signal, perform photoelectric conversion on the processed signal, and further store and process the generated electric signal in the ITOF ranging, the 3D image sensor needs to store more electric charges compared to the conventional 2D image sensor, and thus the capacity requirement of the device for storing electric charges is greater.

The following provides an image sensor 200 according to the present application with reference to fig. 2, including: a first substrate 201 and a second substrate 202, the first substrate 201 including a pixel array, the pixel array being constituted by a pixel unit including: a photoelectric conversion device 210, a transfer device 211 and a transfer device 212, a charge storage device 213 and a charge storage device 215, the second substrate 202 comprising a charge storage device 214 and a charge storage device 215, and remaining processing circuitry (not shown) for processing photo-generated electrons stored in said charge storage device 213, charge storage device 214, charge storage device 215 and charge storage device 216.

The photoelectric conversion device 210 is used for receiving an optical signal and generating photo-generated electrons, the transmission device 211 and the transmission device 212 are used for controlling the transmission of the photo-generated electrons generated in the photoelectric conversion device 210, the charge storage device 213 and the charge storage device 214, the charge storage device 215 and the charge storage device 216 are respectively used for storing the photo-generated electrons generated by the photoelectric conversion device 210 transmitted by the transmission device 211 and the transmission device 212, that is, when the transmission device 211 is opened, the charges in the photoelectric conversion device 210 are transferred to the charge storage device 213 and the charge storage device 214 through the transmission device 211, and correspondingly, when the transmission device 212 is opened, the charges in the photoelectric conversion device 210 are transferred to the charge storage device 215 and the charge storage device 216 through the transmission device 212.

With respect to the ITOF technique, the transmission device 211 and the transmission device 212 respectively transmit photo-generated electrons at different phases, for example, the transmission device 211 may transmit photo-generated electrons at 0 ° phase and the transmission device 212 may transmit photo-generated electrons at 180 ° phase; alternatively, transmission device 211 may transmit photo-generated electrons at 90 ° phase and transmission device 212 may transmit photo-generated electrons at 270 ° phase.

It can be seen that the charge storage device 213 and the charge storage device 214 together store photo-generated electrons transferred by the transfer device 211, the charge storage device 215 and the charge storage device 216 together store photo-generated electrons transferred by the transfer device 212, and the charge storage device 213 and the charge storage device 214 are respectively disposed on the first substrate 201 and the second substrate 202, so that the two substrates together provide a device for storing charges, and the situation that the charge storage device occupies a large substrate area when disposed on the first substrate, thereby reducing the usable area of other circuits is avoided. That is, by disposing the charge storage devices on the two substrates, the capacity of the charge storage devices can be increased, thereby increasing the dynamic range of the image sensor.

In one embodiment, the storage capacity of charge storage device 214 is greater than the storage capacity of charge storage device 213, and the storage capacity of charge storage device 216 is greater than the storage capacity of charge storage device 215. Thus, the area occupied by the charge storage device 213 and the charge storage device 215 on the first substrate 201 can be further reduced, so that more pixel units can be placed on the first substrate 201, and the resolution and the dynamic range of the image processor can be further improved.

In another embodiment, the first substrate 201 and the second substrate 202 are distributed along a vertical direction, the first substrate 201 and the second substrate 202 are connected by a bonding conductor (not shown), the charge storage device 213 and the charge storage device 214 are electrically connected by a bonding conductor, and the charge storage devices 2,5 and the charge storage device 216 are electrically connected by a bonding conductor.

As another embodiment, the processing circuit comprises a reset means, a readout means (not shown) for resetting the charge storage means 213, the charge storage means 214, the charge storage means 215, and the charge storage means 216, and a readout means (not shown) for processing and reading out photo-generated electrons in the charge storage means 213, the charge storage means 214, the charge storage means 215, and the charge storage means 216.

An image sensor provided in an embodiment of the present application will be described in detail below with reference to fig. 3, in which the photoelectric conversion device is a photodiode, the transfer device is a transfer transistor, and the charge storage device is a capacitor.

An image sensor 300, comprising: a first substrate 301, the substrate 301 comprising a pixel array, the pixel array being formed by pixel cells, the pixel cells comprising: a photodiode 310, a transfer transistor 311 and a transfer transistor 312, a capacitor 313 and a capacitor 315, a second substrate 302, the substrate 302 comprising a capacitor 314 and a capacitor 316, and processing circuitry (not shown) for processing the photo-generated electrons stored in the capacitor 313, the capacitor 314, the capacitor 315, the capacitor 316.

The working principle of the image sensor 300 is as follows:

the photodiode 310 receives an optical signal and generates photo-generated electrons, the transmission transistor 311 and the transmission transistor 312 control the transmission of the photo-generated electrons generated in the photodiode 310 through TX1 and TX2, respectively, the timing of TX1 and TX2 is as shown in fig. 3, the two transmission transistors are alternately turned on to transfer the photo-generated electrons in the photodiode 310, specifically, the transmission transistor 311 transfers charges into the capacitor 313 and the capacitor 314, and the transmission transistor 312 transfers charges into the capacitor 315 and the capacitor 316. Processing circuitry (not shown) converts the charge stored in these capacitors into a current or voltage signal output.

In one embodiment, the storage capacity of the capacitor 314 is greater than that of the capacitor 313, and the storage capacity of the capacitor 316 is greater than that of the capacitor 315. Thus, the area occupied by the capacitor 313 and the capacitor 315 on the first substrate 301 can be further reduced, so that more pixel units can be placed on the first substrate 301, and the resolution and the dynamic range of the image processor can be further improved.

As another embodiment, the processing circuit may further include a reset device and a readout device. The following describes the operation flow of the image sensor 400 provided in the present application in detail with reference to fig. 4 by taking an example in which the photoelectric conversion device is a photodiode, the transmission device is a transmission transistor, i.e., a transmission gate, the reset device is a reset transistor, and the readout device is a Source Follower (SF).

First, the reset transistors 413 and 414 are turned on, that is, the transistors 413 and 414 are connected to a high level, the charges on the capacitors 417 and 418 are reset, and the reset charges are read out, that is, the corresponding source follower 421 and row selection switch 422 are turned on, and the reset current is read out; accordingly, the reset transistors 415 and 416 are turned on, i.e., the gates of the transistors 415 and 416 are connected to a high level, the charges on the capacitors 419 and 420 are reset, and the reset charges are read out, i.e., the corresponding source follower 423 and row select switch 424 are turned on, and the reset current is read out.

It should be noted that the reset transistors 413, 414 and 415, 416 may be turned on at the same time, or the transistors 413, 414 may be turned on first, and then the transistors 415, 416 may be turned on.

Then, the reset transistors 413, 414, 415, and 416 are turned off, i.e. the gates of these transistors are connected to a low level, the photodiode 410 receives the optical signal and converts it into photo-generated electrons, and the gates of the transmission gate 411 and the transmission gate 412 are connected to modulation signals, whose waveforms can be shown as TXA/PGA and TXB/PGB in fig. 4, respectively, for demodulating the optical signal at the phases of 0 ° and 180 °.

Illustratively, transfer gate 411 transfers photo-generated electrons at 0 ° phase to capacitors 417 and 418 for storage, and transfer gate 412 transfers photo-generated electrons at 180 ° phase to capacitors 419 and 420 for storage.

Alternatively, the transfer gate 411 is turned on first, and the charge in the photodiode 410 at the phase of 0 ° is transferred to the capacitor 417 and the capacitor 418 through the transfer gate 411, so as to read out the modulated charge at the phase of 0 °, that is, turn on the corresponding source follower 423 and row select switch 424, and read out the modulated current at the phase of 0 °; the transfer gate 412 is turned on again, and a part of the charge in the photodiode 410 is transferred to the capacitor 419 and the capacitor 420 through the transfer gate 412, so that the modulated charge at the 180 ° phase is read out, i.e., the corresponding source follower 423 and row selection switch 424 are turned on, and the modulated current at the 180 ° phase is read out.

A subsequent circuit (not shown in the figure) may process the currents read twice and the currents in the two phases to obtain distance information, i.e., depth information, of the target object, and further obtain a 3D image of the target object.

Alternatively, as shown in the image sensor 500 of fig. 5, the first substrate 501 and the second substrate 502 are connected by a bonding conductor 503.

Accordingly, the present application also provides an electronic device comprising a light source for emitting a light signal to a target object; an image sensor for receiving the optical signal reflected by the target object and generating an electrical signal, for example, the image sensor 600 as shown in fig. 6 includes: a first substrate 601 including a pixel array of pixel units 603, the pixel units 603 including a photoelectric conversion device for receiving an optical signal and generating photo-generated electrons, a transfer device for controlling transfer of the photo-generated electrons, and a first charge storage device 604 for storing the photo-generated electrons transferred by the transfer device; a second substrate 602 including a second charge storage device 605 and processing circuitry 606 for processing photo-generated electrons stored in the first charge storage device and the second charge storage device.

Optionally, the image sensor further includes a driving circuit 607 for driving readout of signals of the pixel circuits on the first substrate 601.

The first charge storage device 604 and the second charge storage device 605 are disposed on the first substrate 601 and the second substrate 602, respectively, so that the two substrates together provide a device for storing charges, and the situation that the charge storage device occupies a large substrate area when disposed on the first substrate, thereby reducing the usable area of other circuits is avoided. That is, by disposing the charge storage devices on the two substrates, the capacity of the charge storage devices can be increased, thereby increasing the dynamic range of the image sensor.

Optionally, the storage capacity of the second charge storage 605 is greater than the storage capacity of the first charge storage 604.

Therefore, the area occupied by the first charge storage device 604 on the first substrate 601 can be further reduced, so that more pixel units can be arranged on the substrate 601, and the dynamic range of the image sensor is improved.

Optionally, the processing circuit 606 comprises a reset means for resetting the second charge storage means, and a readout means for processing and reading out the photo-generated electrons in the charge storage means.

Alternatively, the first substrate 601 and the second substrate 602 are distributed along a vertical direction, the first substrate 601 and the second substrate 602 are connected by a bonding conductor, and the first charge storage device 604 and the second charge storage device 605 are electrically connected by a bonding conductor.

It is noted that, in this document, relational terms such as "first" and "second," and the like, may be used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Also, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising an … …" does not exclude the presence of other identical elements in a process, method, article, or apparatus that comprises the element.

The above description is only a preferred embodiment of the present application and is not intended to limit the present application, and various modifications and changes may be made by those skilled in the art. Any modification, equivalent replacement, improvement and the like made within the spirit and principle of the present application shall be included in the protection scope of the present application. It should be noted that: like reference numbers and letters refer to like items in the following figures, and thus, once an item is defined in one figure, it need not be further defined and explained in subsequent figures. The above description is only a preferred embodiment of the present application and is not intended to limit the present application, and various modifications and changes may be made by those skilled in the art. Any modification, equivalent replacement, improvement and the like made within the spirit and principle of the present application shall be included in the protection scope of the present application.