Multi-photodiode pixel unit

Abstract

In one example, a device includes: a semiconductor substrate including a front side surface; a first photodiode for generating a first charge; a second photodiode for generating a second charge; a barrier layer located between the first photodiode and the second photodiode and configured to control the flow of the second charge from the second photodiode to the first photodiode; and a drain region for storing at least a first portion of the second charge and the first charge. The device also includes a gate on the front side surface above a first channel region between the first photodiode and the drain region to control the flow of at least the first portion of the second charge and the first charge to the drain region, and a second channel region to conduct at least a second portion of the second charge away from the barrier layer when the second photodiode is saturated.

Description

[0001] Related Applications

[0002] This patent application claims priority to U.S. Provisional Patent Application Serial No. 62 / 683,599, filed on June 11, 2018, entitled “PIXEL WITH STACKED DUALPHOTODIODES AND ANTI-BLOOMING CHANNEL,” and U.S. Patent Application Serial No. 16 / 435,449, filed on June 7, 2019, entitled “MULTI-PHOTODIODE PIXEL CELL,” the entire contents of which are incorporated herein by reference.

[0003] background

[0004] The present disclosure relates generally to image sensors, and more particularly, to a pixel cell including a plurality of photodiodes.

[0005] A typical pixel unit in an image sensor includes a photodiode, which is used to sense incident light by converting photons into charge (e.g., electrons or holes). During the exposure period, the charge can be temporarily stored in the photodiode. To improve noise and dark current performance, a pinned photodiode can be included in the pixel to convert photons into charge. The pixel can also include a capacitor (e.g., a floating diffusion) to collect charge from the photodiode and convert the charge into a voltage.

[0006] Image sensors typically include an array of pixel cells. Pixel cells can receive light of varying intensities and can generate varying amounts of charge. Image blooming occurs when the intensity of light received by a pixel cell is so high that the pixel cell becomes saturated and cannot store additional charge, and the additional charge leaks into adjacent pixel cells and destroys the charge stored in the adjacent pixel cells.

[0007] Overview

[0008] The present disclosure relates to image sensors. More particularly, but not limited to, the present disclosure relates to image sensors having an array of pixel cells.

[0009] In one example, a device is provided. The device includes a semiconductor substrate, the semiconductor substrate including: a front side surface, a first photodiode for generating a first charge, a second photodiode for generating a second charge, a barrier layer between the first photodiode and the second photodiode and configured to control the flow of the second charge from the second photodiode to the first photodiode, and a drain region storing at least a first portion of the second charge and the first charge. The device also includes a gate on the front side surface above a first channel region between the first photodiode and the drain region to control the flow of at least the first portion of the second charge and the first charge to the drain region, and a second channel region to conduct at least a second portion of the second charge away from the second photodiode and the barrier layer when the second photodiode is saturated.

[0010] In some aspects, the second channel region is part of the semiconductor substrate and intersects the barrier layer.

[0011] In some aspects, the second channel region is connected between the second photodiode and the drain region.

[0012] In some aspects, each of the drain region and the second channel region includes an N-type semiconductor material. The second channel region is connected to the N-type region of the second photodiode.

[0013] In some aspects, the semiconductor substrate further includes a P-well surrounding the N-type region of the second photodiode. The N-type second channel region is formed in the P-well.

[0014] In some aspects, the first dopant concentration of the second channel region is lower than the second dopant concentration of the N-type region of the second photodiode.

[0015] In some aspects, the drain region is a first drain region. The semiconductor substrate also includes a second drain region. The second channel region is connected between the second photodiode and the second drain region.

[0016] In some aspects, the second channel region is formed by an ion implantation process.

[0017] In some aspects, the second photodiode is sandwiched between the barrier layer and the second channel region.

[0018] In some aspects, the drain region is a first drain region. The semiconductor substrate also includes a second drain region. The second channel region is sandwiched between the second photodiode and the second drain region.

[0019] In some aspects, the second channel region includes an epitaxial layer formed on a backside surface of the semiconductor substrate, the backside surface opposite the frontside surface of the semiconductor substrate.

[0020] In some aspects, the semiconductor substrate further includes a first conductive region and a second conductive region extending from the front side surface, which are configured to receive a first voltage and a second voltage, respectively. The first conductive region extends from the front side surface to the second channel region and is configured to bias the second channel region with the first voltage. The second conductive region extends from the front side surface to the second drain region and is configured to bias the second drain region with the second voltage.

[0021] In some aspects, the second channel region includes a P-type semiconductor material. The second drain region includes an N-type semiconductor material.

[0022] In some aspects, the semiconductor substrate includes a backside surface opposite the frontside surface configured as a light receiving surface. The first photodiode is configured to convert a first component of light in the infrared wavelength range into a first charge. The second photodiode is configured to convert a second component of light in the visible wavelength range into a second charge.

[0023] In some aspects, the front side surface is configured as a light receiving surface. The first photodiode is configured to convert a first component of light in the visible light wavelength range into a first charge. The second photodiode is configured to convert a second component of light in the infrared light wavelength range into a second charge.

[0024] In some aspects, the first channel region includes a buried layer.

[0025] In some aspects, the device further includes a conductive deep trench isolation (C-DTI) structure extending from the front side surface and spanning the N-type region of the first photodiode and the barrier layer. The C-DTI structure is configured to receive a voltage and bias the barrier layer based on the voltage.

[0026] In some aspects, the C-DTI structure extends through the N-type region of the second photodiode.

[0027] In some aspects, the device further includes: a backside surface opposite the frontside surface, and a CDT structure extending from the backside surface and across the N-type region of the second photodiode and the barrier layer. The C-DTI structure is configured to receive a voltage signal and bias the barrier layer based on the voltage signal.

[0028] In some aspects, the gate is a first gate. The device also includes a second gate extending from the front surface to reach the barrier layer. The second gate is configured to receive a voltage signal and bias the barrier layer based on the voltage signal. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Illustrative embodiments are described with reference to the following drawings:

[0031] Figure 1A and Figure 1B is a schematic diagram of an embodiment of a near-eye display.

[0032] Figure 2 is an embodiment of a cross-section of a near-eye display.

[0033] Figure 3 An isometric view of an embodiment of a waveguide display is shown.

[0034] Figure 4 A cross section of an embodiment of a waveguide display is shown.

[0035] Figure 5 is a block diagram of an embodiment of a system including a near-eye display.

[0036] Figure 6 An example of an image sensor including multiple photodiode pixel cells is shown.

[0037] Fig. 7A and Figure 7B Shows Figure 6 An example of the operation of an image sensor.

[0038] Figure 8 It shows that it can be Figure 6 An example of a pixel cell array of a portion of an image sensor.

[0039] Fig. 9A and Fig. 9B Shows Figure 8 An example of the internal components of a pixel unit.

[0040] Fig. 10A and Fig. 10B Shown for Figure 8 FIG. 1 is an example of the potential distribution of the readout charge of a pixel cell array.

[0041] Fig.11 Shows Figure 8 Example of image haloing in pixel units.

[0042] Fig. 12A , Fig. 12B and Fig. 12C Shows Figure 8 Components of a pixel unit for reducing image blur and examples of their operation.

[0043] Fig.13 Shows Figure 8 Another example of image blurring in pixel cells.

[0044] Fig.14A , Fig. 14B , Fig. 14C and Fig.14D Shows Figure 8 Components of a pixel unit for reducing image blur and examples of their operation.

[0045] Fig.15A and Fig. 15B Shows Fig.14A , Fig. 14B , Fig. 14C and Fig.14D Additional components of an example pixel unit.

[0046] Fig.16A , Fig. 16B , Fig. 16C and Fig.16D Shows Figure 8 Further examples of components of pixel cells for reducing image blur and their operation.

[0047] Fig.17A and Fig. 17B Shows Fig.16A , Fig. 16B , Fig. 16C and Fig. 16C Additional components of an example pixel unit.

[0048] The accompanying drawings depict embodiments of the present disclosure for purposes of illustration only. Those skilled in the art will readily recognize from the following description that alternative embodiments of the illustrated structures and methods may be employed without departing from the principles and benefits of the present disclosure.

[0049] In the drawings, similar components and / or features may have the same reference label. In addition, components of the same type may be distinguished by following the reference label with a dash and a second label that distinguishes between similar components. If only the first reference label is used in the specification, the description applies to any one of the similar components having the same first reference label, regardless of the second reference label.

[0050] Detailed Description

[0051] In the following description, specific details are set forth for the purpose of explanation in order to provide a thorough understanding of certain inventive embodiments. However, it is apparent that various embodiments can be implemented without these specific details. The drawings and descriptions are not intended to be limiting.

[0052] A typical image sensor generally includes an array of pixel cells. Each pixel cell may have a photodiode for sensing incident light by converting photons into charges (e.g., electrons or holes). In order to improve noise and dark current performance, a pinned photodiode may be included in the pixel to convert photons into charges. During the exposure period, the charge may be temporarily stored in the photodiode. Each pixel cell may also include a floating diffusion node to convert the charge into a voltage. A pixel value may be generated based on a voltage. The pixel value may represent the intensity of light received by the pixel cell. An image including a pixel array may be derived from a digital output of a voltage output by the pixel cell array.

[0053] The image sensor can be used to perform different imaging modes, such as 2D and 3D sensing. 2D and 3D sensing can be performed based on light of different wavelength ranges. For example, visible light can be used for 2D sensing, while invisible light (e.g., infrared light) can be used for 3D sensing. The image sensor may include an optical filter array to allow visible light of different light wavelength ranges and colors (e.g., red, green, and blue) to reach a first set of pixel units designated for 2D sensing, while invisible light reaches a second set of pixel units designated for 3D sensing.

[0054] To perform 2D sensing, a photodiode at a pixel cell can generate charge at a rate proportional to the intensity of visible light incident on the pixel cell, and the amount of charge accumulated during an exposure period can be used to represent the intensity of the visible light (or a certain color component of the visible light). The charge can be temporarily stored at the photodiode and then transferred to a capacitor (e.g., a floating diffusion) to generate a voltage. The voltage can be sampled and quantized by an analog-to-digital converter (ADC) to generate an output corresponding to the intensity of the visible light. Image pixel values ​​can be generated based on outputs from multiple pixel cells that are configured to sense different color components of visible light (e.g., red, green, and blue).

[0055] In addition, to perform 3D sensing, light of different wavelength ranges (e.g., infrared light) can be projected onto the object, and the reflected light can be detected by the pixel unit. The light can include structured light, light pulses, etc. The pixel unit output can be used to perform depth sensing operations based on, for example, detecting a pattern of reflected structured light, measuring the flight time of light pulses, etc. In order to detect the pattern of reflected structured light, the distribution of the amount of charge generated by the pixel unit during the exposure time can be determined, and a pixel value can be generated based on a voltage corresponding to the amount of charge. For time-of-flight measurement, the timing of charge generation at the photodiode of the pixel unit can be determined to represent the time when the reflected light pulse is received at the pixel unit. The time difference between when the light pulse is projected onto the object and when the reflected light pulse is received at the pixel unit can be used to provide a time-of-flight measurement.

[0056] The pixel cell array can be used to generate scene information. In some examples, a subset of pixel cells in the array (e.g., a first set) can be used to perform 2D sensing of the scene, while another subset of pixel cells in the array (e.g., a second set) can be used to perform 3D sensing of the scene. The fusion of 2D and 3D imaging data is useful for many applications that provide virtual reality (VR), augmented reality (AR), and / or mixed reality (MR) experiences. For example, a wearable VR / AR / MR system can perform scene reconstruction of the environment in which the system user is located. Based on the reconstructed scene, VR / AR / MR can generate display effects to provide an interactive experience. In order to reconstruct the scene, a subset of pixel cells in the pixel cell array can perform 3D sensing to, for example, identify a set of physical objects in the environment and determine the distance between the physical objects and the user. Another subset of pixel cells in the pixel cell array can perform 2D sensing to, for example, capture visual properties including texture, color, and reflectivity of these physical objects. Then, the 2D and 3D image data of the scene can be merged to create a 3D model of the scene including, for example, the visual properties of the object. As another example, a wearable VR / AR / MR system may also perform head tracking operations based on a fusion of 2D and 3D image data. For example, based on 2D image data, the VR / AR / AR system may extract certain image features to identify an object. Based on 3D image data, the VR / AR / AR system may track the location of the identified object relative to a wearable device worn by the user. The VR / AR / AR system may track head movement based on, for example, tracking changes in the location of the identified object relative to the wearable device as the user's head moves.

[0057] However, using different pixel sets for 2D and 3D imaging presents a number of challenges. First, because only a subset of the array's pixel cells are used to perform either 2D or 3D imaging, the spatial resolution of both 2D and 3D images is lower than the maximum spatial resolution achievable at the pixel cell array. Although the resolution can be increased by including more pixel cells, this approach results in an increase in the form-factor of the image sensor and in the power consumption, both of which are undesirable for wearable devices.

[0058] In addition, since the pixel units assigned to measure light of different wavelength ranges (for 2D and 3D imaging) are not collocated, different pixel units may capture information of different spots of the scene, which may complicate the mapping between 2D and 3D images. For example, a pixel unit that receives a certain color component of visible light (for 2D imaging) and a pixel unit that receives invisible light (for 3D imaging) may also capture information of different spots of the scene. The outputs of these pixel units cannot be simply merged to generate 2D and 3D images. When the pixel unit array captures 2D and 3D images of moving objects, the lack of correspondence between the outputs of the pixel units becomes worse due to their different positioning. Although there are processing techniques that can be used to associate the outputs of different pixel units to generate pixels of 2D images and to associate 2D and 3D images (e.g., interpolation), these techniques are generally computationally intensive and also increase power consumption.

[0059] The present disclosure relates to an image sensor capable of providing juxtaposed 2D and 3D imaging. The image sensor includes an array of pixel units. Each pixel unit includes a light receiving surface, and a first photodiode and a second photodiode stacked relative to the light receiving surface. The first photodiode and the second photodiode both receive incident light via the light receiving surface, but the incident light propagates through different distances to reach the first photodiode and the second photodiode, which enables these photodiodes to absorb different wavelength components of the incident light and convert them into charges. For example, in the case where the first photodiode is farther away from the light receiving surface than the second photodiode, the visible light component of the incident light can be absorbed by the first photodiode and converted into a first charge for 2D imaging, while the infrared light component can propagate through a longer distance and can be absorbed by the second photodiode and converted into a second charge for 3D imaging. With such an arrangement, measurements of different components of light received at the same position on the pixel array can be performed, which allows juxtaposed 2D and 3D imaging.

[0060] The pixel unit also includes a transfer gate and a readout drain region to read out charges from the first photodiode and the second photodiode. The transfer gate can be formed on the front side surface, which can be a light receiving surface or opposite to the light receiving surface. The readout drain region can be formed below the front side surface. The transfer gate can be controlled to transfer the first charge from the first photodiode to the readout drain region for readout. After the first charge has been removed from the first photodiode, the second charge can also flow from the second photodiode to the readout drain region through the first photodiode for readout. The pixel unit includes a barrier layer sandwiched between the first photodiode and the second photodiode. The barrier layer can be controlled to prevent the second charge from flowing into the first photodiode before the first charge is read out, and the barrier layer can be controlled to allow the second charge to flow into the first photodiode for readout after the readout of the first charge is completed.

[0061] While stacked photodiode structures allow for juxtaposed 2D and 3D sensing, such structures can be susceptible to image blooming. Image blooming occurs when the intensity of light received by a pixel cell is so high that the pixel cell becomes saturated and cannot store additional charge, and the additional charge leaks into adjacent pixel cells and destroys the charge stored in adjacent pixel cells. In the case of a stacked photodiode structure, image blooming can also occur when one of the first photodiode or the second photodiode is no longer able to store additional charge, and the additional charge leaks into another photodiode or other pixel cells in the stack. The first photodiode is particularly susceptible to receiving leakage charge from the second photodiode because the first photodiode provides the only path to the readout drain region. As a result, when the pixel cell is illuminated by a mixture of strong visible light and mid / weak infrared light, the second photodiode may be saturated when the first photodiode is not saturated, and excess second charge leaks into the first photodiode through the barrier region and destroys the first charge.

[0062] In order to reduce the flow of excess second charges from the second photodiode into the first photodiode, the pixel unit may include an anti-halation channel region, which may be provided to conduct the excess second charges away from the second photodiode and the barrier layer. The anti-halation channel region may be connected to the second drain region and / or the readout drain region within the pixel unit to prevent excess charges from leaking out of the pixel unit.

[0063] The anti-corona channel region can have various structures. In some examples, the anti-corona channel region can be formed in a semiconductor substrate including a first photodiode and a second photodiode, and can intersect with the barrier layer. The anti-corona channel region can be connected between the second photodiode and the readout drain region and / or the second drain region formed below the front surface. The readout drain region (when not used for readout) and the second drain region can be connected to a charge absorber to discharge excess second charges received from the corona channel region. The anti-corona channel region can be formed by multiple ion implantation processes.

[0064] In some examples, the anti-corona channel region and the second drain region may also be formed on the back side surface of the semiconductor substrate so that the second photodiode is sandwiched between the barrier layer and the anti-corona channel region. Each of the anti-corona channel region and the second drain region may be connected to a voltage source to set their respective potentials to drain excess second charges from the second photodiode. The anti-corona channel region may be formed as an epitaxial layer.

[0065] Examples of the present disclosure may include an artificial reality system or be implemented in conjunction with an artificial reality system. Artificial reality is a form of reality that has been adjusted in some way before being presented to a user, which may include, for example, virtual reality (VR), augmented reality (AR), mixed reality (MR), hybrid reality, or some combination and / or derivative thereof. Artificial reality content may include fully generated content or content generated in combination with captured (e.g., real-world) content. Artificial reality content may include video, audio, tactile feedback, or some combination thereof, any of which may be presented in a single channel or multiple channels (e.g., stereoscopic video that produces a three-dimensional effect to the viewer). In addition, in some embodiments, artificial reality may also be associated with applications, products, accessories, services, or some combination thereof, which are used, for example, to create content in artificial reality and / or to be used in other ways in artificial reality (e.g., to perform activities in artificial reality). Artificial reality systems that provide artificial reality content can be implemented on a variety of platforms, including a head-mounted display (HMD) connected to a host computer system, a standalone HMD, a mobile device or computing system, or any other hardware platform capable of providing artificial reality content to one or more viewers.

[0066] Figure 1Ais a schematic diagram of an example of a near-eye display 100. The near-eye display 100 presents media to a user. Examples of media presented by the near-eye display 100 include one or more images, videos, and / or audio. In some embodiments, the audio is presented via an external device (e.g., a speaker and / or a headphone), which receives audio information from the near-eye display 100, a console, or both, and presents audio data based on the audio information. The near-eye display 100 is typically configured to operate as a virtual reality (VR) display. In some embodiments, the near-eye display 100 is modified to operate as an augmented reality (AR) display and / or a mixed reality (MR) display.

[0067] The near-eye display 100 includes a frame 105 and a display 110. The frame 105 is coupled to one or more optical elements. The display 110 is configured to allow a user to see content presented by the near-eye display 100. In some embodiments, the display 110 includes a waveguide display component for directing light from one or more images to the user's eyes.

[0068] The near-eye display 100 also includes image sensors 120a, 120b, 120c, and 120d. Each of the image sensors 120a, 120b, 120c, and 120d may include a pixel cell array (the pixel cell array includes an array of pixel cells) and is configured to generate image data representing different fields of view along different directions. For example, sensors 120a and 120b may be configured to provide image data representing two fields of view along the Z axis toward direction A, while sensor 120c may be configured to provide image data representing a field of view along the X axis toward direction B, and sensor 120d may be configured to provide image data representing a field of view along the X axis toward direction C.

[0069] In some embodiments, the sensors 120a-120d may be configured as input devices to control or affect the display content of the near-eye display 100, thereby providing an interactive VR / AR / MR experience to a user wearing the near-eye display 100. For example, the sensors 120a-120d may generate physical image data of the physical environment in which the user is located. The physical image data may be provided to a positioning tracking system to track the user's position and / or movement path in the physical environment. The system may then update the image data provided to the display 110 based on, for example, the user's position and orientation to provide an interactive experience. In some embodiments, as the user moves within the physical environment, the positioning tracking system may run a SLAM algorithm to track a set of objects in the physical environment and within the user's field of view. The positioning tracking system may build and update a map of the physical environment based on the set of objects, and track the user's position within the map. By providing image data corresponding to multiple fields of view, the sensors 120a-120d may provide a more comprehensive view of the physical environment to the positioning tracking system, which may result in more objects being included in the construction and updating of the map. With this arrangement, the accuracy and robustness of tracking the user's position within the physical environment can be improved.

[0070] In some embodiments, the near-eye display 100 may also include one or more active illuminators 130 to project light into the physical environment. The projected light may be associated with different spectra (e.g., visible light, infrared light, ultraviolet light, etc.) and may be used for various purposes. For example, the illuminator 130 may project light and / or light patterns in a dark environment (or in an environment with low-intensity infrared light, ultraviolet light, etc.) to help the sensor 120a-120d capture 3D images of different objects in a dark environment. The 3D image may include, for example, pixel data representing the distance between the object and the near-eye display 100. The distance information may be used, for example, to build a 3D model of the scene, track the user's head movement, track the user's position, etc. As discussed in more detail below, the sensors 120a-120d may operate in a first mode for 2D sensing and a second mode for 3D sensing at different times. The 2D and 3D image data may be merged and provided to the system to provide more robust tracking of, for example, user positioning, user head movement, etc.

[0071] Figure 1B is a schematic diagram of another embodiment of a near-eye display 100 . Figure 1B 1 shows a side of the near-eye display 100 that faces the eyeball 135 of the user wearing the near-eye display 100. Figure 1BAs shown, the near-eye display 100 may further include a plurality of illuminators 140a, 140b, 140c, 140d, 140e, and 140f. The near-eye display 100 further includes a plurality of image sensors 150a and 150b. The illuminators 140a, 140b, and 140c may face a direction D (with respect to the direction D). Figure 1A The system may emit light of a specific optical frequency range (e.g., NIR) in the opposite direction of A). The emitted light may be associated with a certain pattern and may be reflected by the user's left eyeball. Sensor 150a may include an array of pixel units to receive the reflected light and generate an image of the reflected pattern. Similarly, illuminators 140d, 140e, and 140f may emit NIR light carrying a pattern. The NIR light may be reflected by the user's right eyeball and may be received by sensor 150b. Sensor 150b may also include an array of pixel units to generate an image of the reflected pattern. Based on the images of the reflected patterns from sensors 150a and 150b, the system may determine the user's gaze point and update the image data provided to display 100 based on the determined gaze point to provide an interactive experience to the user. In some examples, image sensors 150a and 150b may include the same pixel units as sensors 120a-120d.

[0072] Figure 2 yes Figure 1A-1B 1 shows an embodiment of a cross-section 200 of a near-eye display 100. The display 110 includes at least one waveguide display assembly 210. The exit pupil 230 is the location of a single eye 220 of a user in the eyebox region when the user wears the near-eye display 100. For illustration purposes, Figure 2 A cross section 200 is shown associated with an eyeball 220 and a single waveguide display assembly 210, but with a second waveguide display for the user's second eye.

[0073] The waveguide display assembly 210 is configured to direct image light to an eye zone located at an exit pupil 230 and to an eyeball 220. The waveguide display assembly 210 may be composed of one or more materials (e.g., plastic, glass, etc.) having one or more refractive indices. In some embodiments, the near-eye display 100 includes one or more optical elements between the waveguide display assembly 210 and the eyeball 220.

[0074] In some embodiments, the waveguide display assembly 210 includes a stack of one or more waveguide displays, including but not limited to a stacked waveguide display, a zoom waveguide display, and the like. A stacked waveguide display is a multicolor display (e.g., a red-green-blue (RGB) display) created by stacking waveguide displays, and the corresponding monochromatic sources of the waveguide displays have different colors. A stacked waveguide display is also a multicolor display (e.g., a multi-plane color display) that can be projected on multiple planes. In some configurations, a stacked waveguide display is a monochromatic display (e.g., a multi-plane monochromatic display) that can be projected on multiple planes. A zoom waveguide display is a display that can adjust the focus position of image light emitted from a waveguide display. In alternative embodiments, the waveguide display assembly 210 may include a stacked waveguide display and a zoom waveguide display.

[0075] Figure 3 An isometric view of an embodiment of a waveguide display 300 is shown. In some embodiments, the waveguide display 300 is a component of the near-eye display 100 (e.g., the waveguide display assembly 210). In some embodiments, the waveguide display 300 is part of some other near-eye display or other system that directs image light to a specific location.

[0076] The waveguide display 300 includes a source component 310, an output waveguide 320, an illuminator 325, and a controller 330. The illuminator 325 may include Figure 1A For the purpose of illustration, Figure 3 The waveguide display 300 is shown associated with a single eyeball 220, but in some embodiments, another waveguide display that is separate or partially separate from the waveguide display 300 provides image light to the user's other eye.

[0077] The source component 310 generates image light 355. The source component 310 generates image light 355 and outputs it to the coupling element 350 located on the first side 370-1 of the output waveguide 320. The output waveguide 320 is an optical waveguide that outputs the expanded image light 340 to the eyeball 220 of the user. The output waveguide 320 receives the image light 355 at one or more coupling elements 350 located on the first side 370-1 and guides the received input image light 355 to the guide element 360. In some embodiments, the coupling element 350 couples the image light 355 from the source component 310 into the output waveguide 320. The coupling element 350 can be, for example, a diffraction grating, a holographic grating, one or more cascade reflectors, one or more prismatic surface elements, and / or a holographic reflector array.

[0078] The guiding element 360 redirects the received input image light 355 to a decoupling element 365, such that the received input image light 355 is decoupled from the output waveguide 320 via the decoupling element 365. The guiding element 360 is part of a first side 370-1 of the output waveguide 320 or is fixed to the first side 370-1 of the output waveguide 320. The decoupling element 365 is part of a second side 370-2 of the output waveguide 320 or is fixed to the second side 370-2 of the output waveguide 320 such that the guiding element 360 is opposite to the decoupling element 365. The guiding element 360 and / or the decoupling element 365 may be, for example, a diffraction grating, a holographic grating, one or more cascade reflectors, one or more prismatic face elements, and / or a holographic reflector array.

[0079] The second side 370-2 represents a plane along the x-dimension and the y-dimension. The output waveguide 320 can be composed of one or more materials that facilitate total internal reflection of the image light 355. The output waveguide 320 can be composed of, for example, silicon, plastic, glass, and / or a polymer. The output waveguide 320 has a relatively small form factor. For example, the output waveguide 320 can be about 50 mm wide along the x-dimension, about 30 mm long along the y-dimension, and about 0.5 mm-1 mm thick along the z-dimension.

[0080] The controller 330 controls the scanning operation of the source component 310. The controller 330 determines the scanning instructions of the source component 310. In some embodiments, the output waveguide 320 outputs the expanded image light 340 to the user's eyeball 220 with a large field of view (FOV). For example, the expanded image light 340 is provided to the user's eyeball 220 with a diagonal FOV (in x and y) of 60 degrees and / or greater and / or 150 degrees and / or less. The output waveguide 320 is configured to provide an eye zone having a length of 20 mm or greater and / or equal to or less than 50 mm; and / or a width of 10 mm or greater and / or equal to or less than 50 mm.

[0081] In addition, controller 330 also controls image light 355 generated by source assembly 310 based on image data provided by image sensor 370. Image sensor 370 may be located on first side 370-1 and may include, for example Figure 1A370-1. The image sensors 120a-120d can be operated to perform 2D sensing and 3D sensing of, for example, an object 372 in front of a user (e.g., facing the first side 370-1). For 2D sensing, each pixel unit of the image sensors 120a-120d can be operated to generate pixel data representing the intensity of light 374 generated by the light source 376 and reflected by the object 372. For 3D sensing, each pixel unit of the image sensors 120a-120d can be operated to generate pixel data representing the time-of-flight measurement results of light 378 generated by the illuminator 325. For example, each pixel unit of the image sensors 120a-120d can determine a first time when the illuminator 325 is enabled to project light 378 and a second time when the pixel unit detects light 378 reflected from the object 372. The difference between the first time and the second time can indicate the flight time of the light 378 between the image sensors 120a-120d and the object 372, and the flight time information can be used to determine the distance between the image sensors 120a-120d and the object 372. The image sensors 120a-120d can be operated to perform 2D and 3D sensing at different times and provide 2D and 3D image data to a remote control console 390, which may (or may not) be located within the waveguide display 300. The remote control console can combine the 2D and 3D images to, for example, generate a 3D model of the user's environment, track the user's position and / or orientation, etc. The remote control console can determine the content of the image to be displayed to the user based on the information derived from the 2D and 3D images. The remote control console can transmit instructions related to the determined content to the controller 330. Based on these instructions, the controller 330 can control the source component 310 to generate and output image light 355 to provide an interactive experience to the user.

[0082] Figure 4 An embodiment of a cross-section 400 of a waveguide display 300 is shown. The cross-section 400 includes a source component 310, an output waveguide 320, and an image sensor 370. Figure 4 In the example of , the image sensor 370 may include a set of pixel cells 402 located on the first side 370-1 to generate an image of the physical environment in front of the user. In some embodiments, a mechanical shutter 404 and an optical filter array 406 may be inserted between the set of pixel cells 402 and the physical environment. The mechanical shutter 404 can control the exposure of the set of pixel cells 402. In some embodiments, as will be discussed below, the mechanical shutter 404 can be replaced by an electronic shutter gate. As described below, the optical filter array 406 can control the optical wavelength range of light to which the set of pixel cells 402 is exposed. Each pixel cell 402 may correspond to a pixel of the image. Although Figure 4 It is not shown, but it should be understood that each pixel unit 402 may also be superimposed with a filter to control the optical wavelength range of light to be sensed by the pixel unit.

[0083] After receiving the instruction from the remote console, the mechanical shutter 404 may open and expose the group of pixel units 402 in an exposure period. During the exposure period, the image sensor 370 may obtain light samples incident on the group of pixel units 402, and generate image data based on the intensity distribution of the incident light samples detected by the group of pixel units 402. The image sensor 370 may then provide the image data to the remote console, which determines the display content, and provides the display content information to the controller 330. The controller 330 may then determine the image light 355 based on the display content information.

[0084] Source assembly 310 generates image light 355 according to instructions from controller 330. Source assembly 310 includes source 410 and optical system 415. Source 410 is a light source that generates coherent light or partially coherent light. Source 410 can be, for example, a laser diode, a vertical cavity surface emitting laser, and / or a light emitting diode.

[0085] The optical system 415 includes one or more optical components that condition the light from the source 410. Conditioning the light from the source 410 may include, for example, expanding, collimating, and / or adjusting the orientation according to instructions from the controller 330. The one or more optical components may include one or more lenses, liquid lenses, mirrors, apertures, and / or gratings. In some embodiments, the optical system 415 includes a liquid lens with multiple electrodes that allows the light beam to be scanned with a threshold scanning angle to move the light beam to an area outside the liquid lens. The light emitted from the optical system 415 (and the source assembly 310) is referred to as image light 355.

[0086] The output waveguide 320 receives the image light 355. The coupling element 350 couples the image light 355 from the source component 310 into the output waveguide 320. In embodiments where the coupling element 350 is a diffraction grating, the pitch of the diffraction grating is selected such that total internal reflection occurs in the output waveguide 320, and the image light 355 propagates internally in the output waveguide 320 (e.g., by total internal reflection) toward the decoupling element 365.

[0087] The guiding element 360 redirects the image light 355 to the decoupling element 365 for decoupling from the output waveguide 320. In embodiments where the guiding element 360 is a diffraction grating, the pitch of the diffraction grating is selected so that the incident image light 355 exits the output waveguide 320 at an angle oblique to the surface of the decoupling element 365.

[0088] In some embodiments, the guide element 360 and / or the decoupling element 365 are similar in structure. The expanded image light 340 exiting the output waveguide 320 is expanded along one or more dimensions (e.g., can be elongated along the x dimension). In some embodiments, the waveguide display 300 includes a plurality of source components 310 and a plurality of output waveguides 320. Each source component 310 emits a monochromatic image light of a specific wavelength band corresponding to a primary color (e.g., red, green, or blue). Each output waveguide 320 can be stacked together at a certain spacing distance to output a multi-color expanded image light 340.

[0089] Figure 5 is a block diagram of an embodiment of a system 500 including a near-eye display 100. The system 500 includes the near-eye display 100, an imaging device 535, an input / output interface 540, and image sensors 120a-120d and 150a-150b, each of which is coupled to a control circuit 510. The system 500 may be configured as a head mounted device, a wearable device, or the like.

[0090] The near-eye display 100 is a display that presents media to the user. Examples of media presented by the near-eye display 100 include one or more images, videos, and / or audio. In some embodiments, the audio is presented via an external device (e.g., a speaker and / or headphones), which receives audio information from the near-eye display 100 and / or the control circuit 510 and presents audio data to the user based on the audio information. In some embodiments, the near-eye display 100 can also act as AR glasses. In some embodiments, the near-eye display 100 uses computer-generated elements (e.g., images, videos, sounds, etc.) to enhance the view of the physical, real-world environment.

[0091] The near-eye display 100 includes a waveguide display assembly 210, one or more position sensors 525, and / or an inertial measurement unit (IMU) 530. The waveguide display assembly 210 includes a source assembly 310, an output waveguide 320, and a controller 330.

[0092] The IMU 530 is an electronic device that generates rapid calibration data based on measurement signals received from one or more position sensors 525 , the rapid calibration data indicating an estimated position of the near-eye display 100 relative to an initial position of the near-eye display 100 .

[0093] The imaging device 535 can generate image data for various applications. For example, the imaging device 535 can generate image data based on calibration parameters received from the control circuit 510 to provide slow calibration data. The imaging device 535 can include, for example, Figure 1AThe image sensors 120a-120d are used to generate 2D image data and 3D image data of the user's physical environment to track the user's position and head movement. The imaging device 535 may also include, for example Figure 1B The image sensors 150a-150b are used to generate image data (eg, 2D image data) for determining a user's gaze point to identify an object of interest to the user.

[0094] The input / output interface 540 is a device that allows a user to send an action request to the control circuit 510. An action request is a request to perform a specific action. For example, the action request may be to start or end an application, or to perform a specific action within an application.

[0095] The control circuit 510 provides media to the near-eye display 100 for presentation to the user based on information received from one or more of the imaging device 535, the near-eye display 100, and the input / output interface 540. In some examples, the control circuit 510 can be housed within the system 500 configured as a head mounted device. In some examples, the control circuit 510 can be a stand-alone console device that is communicatively coupled to other components of the system 500. Figure 5 In the example shown, the control circuit 510 includes an application storage 545 , a tracking module 550 , and an engine 555 .

[0096] Application storage 545 stores one or more applications for execution by control circuit 510. An application is a set of instructions that, when executed by a processor, generates content for presentation to a user. Examples of applications include: gaming applications, conferencing applications, video playback applications, or other suitable applications.

[0097] Tracking module 550 uses one or more calibration parameters to calibrate system 500 , and may adjust the one or more calibration parameters to reduce errors in the determination of the position of near-eye display 100 .

[0098] The tracking module 550 uses the slow calibration information from the imaging device 535 to track the movement of the near-eye display 100. The tracking module 550 also uses the position information from the fast calibration information to determine the position of a reference point of the near-eye display 100.

[0099] The engine 555 executes applications within the system 500 and receives position information, acceleration information, velocity information, and / or predicted future position of the near-eye display 100 from the tracking module 550. In some embodiments, the information received by the engine 555 can be used to generate a signal (e.g., a display instruction) to the waveguide display assembly 210, which determines the type of content presented to the user. For example, in order to provide an interactive experience, the engine 555 can determine the content to be presented to the user based on the user's position (e.g., provided by the tracking module 550), the user's gaze point (e.g., based on image data provided by the imaging device 535), and the distance between the object and the user (e.g., based on image data provided by the imaging device 535).

[0100] Figure 6 An example of an image sensor 600 is shown. The image sensor 600 may use the same pixel unit for 2D sensing and 3D sensing. For example, the same pixel unit may be configured to detect a color component of visible light (e.g., red, green, or blue) for 2D sensing and to detect infrared light for 3D sensing. The image sensor 600 may be part of the near eye display 100 and may be provided to the user. Figure 5 The control circuit 510 provides 2D and 3D image data to control the display content of the near-eye display 100. Figure 6 In the example of , the image sensor 600 may include an illuminator 602 , an optical filter array 604 , a pixel unit array 606 including a pixel unit 606 a , and a digitization module 608 .

[0101] The illuminator 602 may be an infrared illuminator (e.g., a laser, a light emitting diode (LED), etc.) that can project infrared light for 3D sensing. The projected light may include, for example, structured light, light pulses, etc. The optical filter array 604 may include an array of filter elements, each of which corresponds to a pixel unit (e.g., pixel unit 606a) of the pixel unit array 606. Each filter element may be configured to absorb incident light of a certain wavelength range and transmit the remaining light to the corresponding pixel unit. The incident light may include ambient visible light and infrared light projected by the illuminator 602 and reflected by the object. For example, one filter element may transmit the green component of visible light and infrared light to the pixel unit, while another filter element may transmit the blue component of visible light and infrared light to another pixel unit. In some examples, the optical filter array 604 may be configured to select the color component of the visible light to be transmitted together with the infrared light, so that the pixel unit 606a can be used to detect different color components of visible light and infrared light.

[0102] In addition, the pixel unit 606a may include a plurality of photodiodes to detect different color components of visible light and infrared light in the incident light. Figure 6 As shown, the pixel unit 606a may include a photodiode 612 and a photodiode 614. The photodiode 612 and the photodiode 614 may be pinned photodiodes. The photodiode 612 may detect a first component of incident light of a first wavelength range (e.g., one of red, blue, or green visible light) during an exposure period, convert the detected photons into charge, and store the charge. In addition, the photodiode 614 may detect a second component of incident light of a second wavelength range (e.g., infrared light) during the same or different exposure period, convert the detected photons into charge, and store the charge. The pixel unit 606a may also include a charge storage device 616, which may include a floating drain node, a metal capacitor, or a combination of the two. At the end of the exposure period, the charge stored at the photodiodes 612 and 614 may be transferred to the charge storage device 616 to generate a voltage for 2D and 3D sensing.

[0103] The image sensor 600 also includes a measurement module 608. The measurement module 608 may also include a 2D measurement module 622 to perform a 2D imaging operation based on the charge generated by the photodiode 612. The 2D imaging operation may include, for example, generating a pixel value based on the magnitude of the voltage generated at the charge storage device 616, the pixel value reflecting the total amount of charge stored at the photodiode 612 during the exposure period. The measurement module 608 may include a 3D measurement module 624 to perform a 3D imaging operation based on the charge generated by the photodiode 614. The 3D imaging operation may include, for example, detecting a pattern of structured light reflected by a surface of an object and comparing the detected pattern with a pattern of structured light projected by the illuminator 602 to determine the depth of different points of the surface relative to the pixel unit array. To detect the pattern of reflected light, the 3D measurement module 624 may generate a pixel value based on the magnitude of the voltage generated at the charge storage device 616, the pixel value reflecting the total amount of charge stored at the photodiode 614 during the exposure period. As another example, 3D measurement module 624 can generate pixel values ​​that represent time-of-flight measurements of light pulses transmitted by illuminator 602 and reflected by an object.

[0104] The image sensor 600 also includes a sensing controller 610 to control the different components of the image sensor 600 to perform 2D and 3D imaging of an object. Fig. 7A and Figure 7B , Fig. 7A and Figure 7B An example of the operation of an image sensor 600 for 2D and 3D imaging is shown. Fig. 7AAn example of operation for 2D imaging is shown. For 2D imaging, pixel unit array 606 can detect visible light in the environment, including visible light reflected from an object. For example, referring to Fig. 7A , a visible light source 700 (e.g., a light bulb, the sun, or other ambient visible light source) can project visible light 702 onto an object 704. Visible light 706 can be reflected from a point 708 of the object 704. The visible light 706 can be filtered by an optical filter array 604 to pass a predetermined wavelength range w0 of the reflected visible light 706, thereby producing filtered light 710a. The wavelength range w0 can correspond to a first color component of the visible light 706 reflected from the point 708 (e.g., a red component having a wavelength range of 620-750 nanometers (nm)). The filtered light 710a can be captured by a first photodiode 612 of a pixel unit 606a to generate and accumulate a first charge during an exposure period. At the end of the exposure period, the sensing controller 610 can direct the first charge to the charge storage device 616 to generate a voltage representing the intensity of the first color component and provide the first voltage to the 2D measurement module 622. The 2D measurement module 622 may include an analog-to-digital converter (ADC) and may be controlled by the sensing controller 610 to sample and quantize the first voltage to generate a digital value representing the intensity of the first color component of the visible light 706.

[0105] In addition, the image sensor 600 may also perform 3D imaging of the object 704. Figure 7B , the sensing controller 610 can control the illuminator 602 to project infrared light 728 onto the object 704, and the infrared light 728 may include light pulses, structured light, etc. The infrared light 728 may have a wavelength range of 700 nanometers (nm) to 1 millimeter (mm). The infrared photon 730 may be reflected from the object 704, propagate toward the pixel unit array 606, and pass through the optical filter 604. In some examples, the second photodiode 614 of the pixel unit 606a may convert the infrared photon 730 into a second charge. The detection and conversion of the infrared photon 730 by the second photodiode 614 may occur within the same exposure period as the detection and conversion of the visible light 706 by the first photodiode 612. This arrangement allows each pixel unit to perform 2D and 3D imaging of the same point of the object, which can improve the correspondence between the 2D and 3D images. The sensing controller 610 can guide the second charge to the charge storage device 616 to generate a voltage representing the intensity of the infrared light received at the pixel unit.

[0106] The 3D measurement module 624 can perform different types of depth sensing operations based on the type of light 728 projected onto the object 704. In the case where the structured light 728 is projected onto the object 704, the 3D measurement module 624 can include an ADC and can be controlled by the sensing controller 610 to sample and quantize the second voltage to generate a digital value representing the intensity of the infrared light reflected by the point 708. A pattern of the intensity of the infrared light reflected by the object 704 can be obtained from the digital value. The pattern can be compared with the structured light pattern projected by the illuminator 602 to determine the depth of different points (including the point 708) on the surface of the object 704 relative to the pixel unit array 606. In the case where the infrared light 728 includes a light pulse, the 3D measurement module 624 can detect a change in the charge stored at the second photodiode 614. The flight time of the infrared light pulse can be determined based on the time difference between the time when the light pulse leaves the illuminator 602 and the time when the change in the charge stored at the second photodiode 614 is detected. Based on the information provided by each pixel unit, a 3D image of the object 704 can be generated.

[0107] Figure 8 An example of an array of pixel cells 800 (e.g., pixel cells 800a, 800b, 800c, and 800d) is shown, which can perform collocated 2D and 3D image sensing and can be part of image sensor 600. Figure 8 As shown, each pixel unit 800 may include a first semiconductor substrate 802, a second semiconductor substrate 804, and a metal layer 805 sandwiched between the substrates. The first semiconductor substrate 802 may include a light receiving surface 806, a first photodiode 808, a second photodiode 810, and a charge storage device 616, and the second semiconductor substrate 804 may include an interface circuit 850. The first photodiode 808 and the second photodiode 810 may form a stack along an axis perpendicular to the light receiving surface 806 (e.g., along the z-axis). The second photodiode 810 may be configured as a visible light sensing photodiode ("VIS PD"), and the first photodiode 808 may be configured as an infrared light sensing photodiode ("IR PD"). Specifically, the second photodiode 810 may be closer to the light receiving surface 806 than the first photodiode 808. When light 816 enters via the light receiving surface 806 and propagates within the first semiconductor substrate 802, a first light component 822 of the light 816 having a relatively longer infrared light wavelength range may propagate through the second photodiode 810 and may be absorbed by the first photodiode 808. In addition, a second light component 824 of the light 816 having a relatively shorter visible light wavelength range stops at the second photodiode 810 and may be absorbed by the second photodiode 810.

[0108] Each pixel unit 800 also includes optical components to control the properties of the first light component 822 and the second light component 824 of the light 816. For example, each pixel unit 800 includes a microlens 832 for focusing the light 816, and an optical filter 834 for selecting, for example, a wavelength range (e.g., one of red, green, or blue) of the second light component 824 to be absorbed / measured by the second photodiode 810. Figure 8 As shown, based on the configuration of the color filter 834, each of the pixel units 800a, 800b, 800c, and 800d can receive infrared light as the first light component 822, but receive visible light of a different wavelength range as the second light component 824. Figure 8 In the example of , pixel unit 800 a may receive red light as the second light component 824 , and pixel units 800 b and 800 d may receive green light as the second light component 824 , while pixel unit 800 c may receive blue light as the second light component 824 .

[0109] Each of the first photodiode 808 and the second photodiode 810 can generate charge in response to the first light component 822 and the second light component 824, respectively. The charge generation rate of each photodiode can represent the intensity of the first light component 822 and the second light component 824. The charge generated by the first photodiode 808 and the second photodiode 810 can be stored in the charge storage device 616. Figure 8 In the example of FIG. 8 , the charge storage device 616 may include a floating drain node 818 in the first semiconductor substrate 802 and an auxiliary metal capacitor 820 in the metal layer 805. The amount of charge accumulated in the charge storage device 616 and the rate of charge accumulation in the charge storage device 616 may be measured by the interface circuit 850. The interface circuit 850 may include Figure 6 The measurement module 608 of the second semiconductor substrate 804 can be connected to the measurement module 608 to determine, for example, the intensity of the first light component 822 and the second light component 824. The metal layer 105 also includes a metal interconnect 830, which can couple the floating drain node 818 and the auxiliary metal capacitor 820 with the measurement module 608 of the second semiconductor substrate 804. The metal interconnect 830 can transmit the voltage generated at the charge storage device 616 corresponding to the charge generated by the first photodiode 808 and the second photodiode 810 to the measurement module 608 to perform measurements for 2D and 3D image sensing operations as described above.

[0110] Although Figure 8The first photodiode 808 and the second photodiode 810 of the pixel unit 800 are shown to form a stacked structure, which enables the two photodiodes to sense different light components, but the pixel unit 800 can adopt other configurations to separate the light components. For example, the two photodiodes can be arranged adjacent to each other along an axis parallel to the light receiving surface 806 (e.g., along the x-axis or y-axis), and an optical structure can be provided on the light receiving surface 806 to separate the light components and project / guide the different light components to the photodiodes.

[0111] Reference now Fig. 9A and Fig. 9B , which shows Figure 8 Examples of other components of the semiconductor substrate 802 are not shown. Fig. 9A and Fig. 9B FIG. 8 shows a pixel unit 800 formed in a P-type semiconductor substrate 802. Fig. 9A and Fig. 9B In the embodiment, the semiconductor substrate 802 may have a front side surface 902 and a back side surface 904. The front side surface 902 is where additional semiconductor processing is performed, such as forming a polysilicon gate 918, and doping and / or ion implantation to form a first photodiode 808, a second photodiode 810, a floating drain node 818, a pinning layer 915, etc. Fig. 9A In the embodiment, the pixel unit 800 can be configured as a backside illumination (BSI) device, wherein the backside surface 904 is configured as a light receiving surface 806, and the microlens 832 and the optical filter 834 can be placed on the backside surface 904 to control the properties of the first light component 822 and the second light component 824 of the light 816. Fig. 9B , the pixel unit 800 can be configured as a front side illumination (FSI) device, wherein the front side surface 902 is configured as a light receiving surface 806. An insulating layer 952 can be placed over the polysilicon gate 918 and the oxide layer 916 on the front side surface 902, and a microlens 832 and an optical filter 834 can be placed on the insulating layer 952 to control the properties of the first light component 822 and the second light component 824 of the light 816.

[0112] exist Fig. 9A and Fig. 9B In the example of , the first photodiode 808 and the second photodiode 810 can be configured as pinned photodiodes. Fig. 9A and Fig. 9B In the embodiment, the pixel unit 800 includes a P-well 908 and an N-type region 912 embedded in the P-well 908 to form a first pinned photodiode 808. In addition, a second pinned photodiode 810 can be formed by including an N-type region 906 embedded in a P-type semiconductor substrate 802. Fig. 9AIn FIG. 8 , the N-type region 912 is further away from the backside surface 904 (configured as the light receiving surface 806) than the N-type region 906, which allows the first pinned photodiode 808 to mainly detect the infrared component of the light 816 (e.g., the first light component 822) and allows the second pinned photodiode 810 to mainly detect the visible light component of the light 824 (e.g., the second light component 824). Fig. 9B In the embodiment, the N-type region 912 is closer to the front side surface 902 (configured as the light receiving surface 806) than the N-type region 906, and the roles of the first pinned photodiode 808 and the second pinned photodiode 810 may be reversed. Fig. 9B In the embodiment of the present invention, the first pinned photodiode 808 can detect a visible light component (e.g., the second light component 824), while the second pinned photodiode 810 can detect an infrared component (e.g., the first light component 822). The first pinned photodiode 808 and the second pinned photodiode 810 can have the same or different pinning voltages (e.g., the maximum voltage difference across the photodiodes). In the first pinned photodiode 808 and the second pinned photodiode 810, the complete isolation of the N-type region 906 and the N-type region 912 within the P-type substrate 901 and the P-well 908 can provide better dark current and noise performance.

[0113] exist Fig. 9A and Fig. 9B In the embodiment of the present invention, a barrier layer 914 is also formed between the first pinned photodiode 808 and the second pinned photodiode 810, and the first pinned photodiode 808, the barrier layer 914 and the second pinned photodiode 810 can form a stack along the propagation direction of light in the P-type semiconductor substrate 802 (e.g., along the z-axis). As described in more detail below, the barrier layer 914 can prevent the charge stored in the first pinned photodiode 808 from entering the second pinned photodiode 810. The barrier layer 914 can also regulate the flow of charge from the second pinned photodiode 810 to the first pinned photodiode 808 for readout and quantization. In some examples, the barrier layer 914 can be a P-type layer and is part of the P-well 908 (or the P-type semiconductor substrate 802), or can be part of a P+ region with a higher P-type doping concentration. In some examples, the barrier layer 914 can also be an N-type layer (e.g., having a lower N-type doping concentration than both the N-type region 906 and the N-type region 912).

[0114] As described above, the pixel unit 800 also includes a pinning layer 915, an oxide layer 916, a polysilicon gate 918, and a floating drain 818 on the front side surface 902. The pinning layer 915 can be configured to separate the N-type region 912 and avoid direct contact with the oxide layer 916 to reduce the dark current caused by the surface-hole combination at the interface between the oxide layer 916 and the substrate, which can further improve the dark current performance of the first pinned photodiode. In some examples, the pinning layer 915 can form a second pinned photodiode having an N-type region 912, and the P well 908 can be removed from the device 900. The polysilicon gate 918 can receive a voltage and apply an electric field via the oxide layer 916 to create a channel at the channel region 922 between the N-type region 912 and the floating drain 818. A channel can be created to read out the charge generated by one of the first photodiode 808 or the second photodiode 810.

[0115] Fig. 10A and Fig. 10B An example of a potential distribution within the first semiconductor substrate 802 for reading out charges from the first or second photodiodes 808 and 810 is shown. Fig. 10A An example is shown in which the potential of the barrier layer 914 is modulated with respect to time to perform readout. Fig. 10A At time 1000, the N-type region 912 and the N-type region 906 store negative charges generated in response to the first and second light components 822 and 824, and each may have a potential P 电荷 . Potential P 电荷 The charge quantity, the capacity of the quantum wells of the N-type region 912 and the N-type region 906, and the potential P when the quantum well is empty can be used as the basis. 空 At the same time, the channel region 922 may be in a closed state, and no channel has been created at the channel region 922. The potential at the channel region 922 may be lower than P 电荷 In addition, the barrier layer 914 may be in a cut-off state and may be set to a potential that prevents charges from flowing between the N-type region 912 and the N-type region 906, and the potential at the N-type region 912 may also be lower than the potential at the P-type region 914. 电荷 The electric potential. Fig. 10A In the embodiment, the potentials at the channel region 922 and the barrier layer 914 may be similar to P sub .

[0116] At time 1000, the storage capacity of N-type region 912 and N-type region 906 may be maximum. The maximum amount of charge that can be stored in N-type region 912 may be defined based on the quantum well capacity of N-type region 912 and the potential of channel region 912 and barrier substrate 914 when both are in the off state. With this arrangement, when the maximum amount of charge is stored in N-type region 912, P 电荷 The potential at the channel region 922 may be maintained higher than the potential barrier substrate 914 and the channel region 912 to trap charges in the N-type region 912. As will be described in detail below, the potential at the channel region 922 may be configured to set the storage capacity of the N-type region 912. In addition, the potential P of the first semiconductor substrate 802 may be determined based on the quantum well capacity of the N-type region 906, the potential P of the first semiconductor substrate 802, and the storage capacity of the N-type region 906. sub and the potential of the barrier substrate 914 in the off state and P 空 To define the maximum amount of charge that can be stored in the N-type region 906, when the maximum amount of charge is stored in the N-type region 906, P 电荷 A potential higher than that of the first semiconductor substrate 802 and the barrier layer 914 is maintained to trap charges in the N-type region 906 .

[0117] At time 1002, the charge stored in the N-type region 912 can be read out. To read out the charge, the potential in the channel region 922 can be increased to P by applying a voltage at the polysilicon gate 918 to form a channel in the channel region 922. 沟道-导通 The negative charges stored in the N-type region 912 can flow to the channel region 922 and then to the floating drain 818. Meanwhile, the potential of the barrier layer 914 is maintained at P sub , which is lower than the potential P of the charge stored in the N-type region 906 电荷 As a result, the charge stored in N-type region 906 remains trapped in that region.

[0118] At time 1004, the potential of barrier layer 914 may increase to a level equal to or higher than P 电荷. The pixel unit 800 may include various structures to adjust the potential of the barrier layer 914. As an example, the pixel unit 800 may include a pair of conductive deep trench isolations (C-DTIs) on both sides of the barrier layer 914. The pair of C-DTIs may extend from the front side surface 902 or the back side surface 904. Each C-DTI may conduct a voltage to generate an electric field on the barrier layer 914, thereby carrying away negative charges, which may increase the potential of the barrier layer 914. As another example, the pixel unit 800 may include a second polysilicon gate extending from the front side surface 902 to reach the barrier layer 914. The oxide layer 916 may also extend from the front side surface 902 along the second polysilicon gate to insulate the second polysilicon gate from the barrier layer 914. The second polysilicon gate may conduct a voltage that may push negative charges away from the barrier layer 914 to increase its potential.

[0119] As the potential of the barrier layer 914 increases, the negative charges stored in the N-type region 906 may flow to the N-type region 912. Fig. 10A In the example, the potential in the channel region 922 can be maintained at P 沟道-导通 , and all the charge from the N-type region 906 can be transferred to the floating drain 818. In some examples, as will be described below, the charge stored in the N-type region 906 can be transferred to the floating drain 818 in multiple steps for measurement operations of different light intensities.

[0120] Fig. 10B Another example is shown, in which the potential of the barrier layer 914 is kept constant, but the potential of the first semiconductor substrate 802 is modulated to perform readout of the charge at the N-type region 906. Fig. 10B As shown, at time 1012, a negative potential may be applied to the first semiconductor substrate 802, which causes the potential of the barrier layer 914 to become higher than the potential of the first semiconductor substrate 802. Negative charges stored at the N-type region 906 may then flow through the barrier layer 914, and then through the channel region 922 and the floating drain 818, all of which may have a higher potential than the N-type region 906 when the negative potential is applied to the first semiconductor substrate 802.

[0121] although Fig. 9A and Fig. 9BThe stacked photodiode structure allows for collocated 2D and 3D sensing by measuring different components of light 816 received via the front side surface 902 or the back side surface 904, but such a structure may be susceptible to image blooming. Image blooming occurs when the intensity of the first light component 822 and / or the second light component 824 is so high that the first pinned photodiode 808 and / or the second pinned photodiode 810 becomes saturated and cannot store additional charge, and the additional charge leaks into another photodiode and / or other pixel cells that are not saturated and corrupts the charge stored there.

[0122] Fig.11 An example of image blooming caused by saturation of the first photodiode 808 is shown. Fig.11 As shown, since, for example, the first light component 822 or the second light component 824 has a very high intensity, a large amount of negative charge can be accumulated in the N-type region 912 (of the first photodiode 808). In addition, the polysilicon gate 918 can receive an off-state signal (e.g., a voltage lower than a channel formation threshold voltage) to set the channel region 922 to an off-state, and a channel has not yet been generated at the channel region 922. The potentials at the channel region 922 and the barrier layer 914 can be P sub As more negative charges including charge 1102 accumulate in N-type region 912, the potential of N-type region 912 continues to decrease and may become equal to or lower than P sub At this point, the charge 1102 may leak from the N-type region 912 through the barrier layer 914 and move into the N-type region 906 (of the second photodiode 810 ) and contaminate the charge accumulated in the N-type region 906 , which represents a measurement of a different light component.

[0123] Fig. 12A and Fig. 12B Examples of components of the pixel cell 800 that may reduce or prevent image blooming caused by saturation of the first photodiode 808 are shown. Fig. 12A Pixel cell 800 is shown as a BSI device, while Fig. 12B Pixel unit 800 is shown as a FSI device. Fig. 12A and Fig. 12B As shown, the channel region 922 may include a dopant layer 1202 formed in the P-well 908. The dopant layer 1202 may be formed along a horizontal / lateral direction (e.g., parallel to the x / y axis and / or the front side surface 902). When the polysilicon gate 918 receives an off-state signal, the dopant layer 1202 may adjust the potential of the channel region 922 relative to the bias voltage of the P-well 908. As a result, the potential of the channel region 922 relative to the empty quantum well P 空Having a lower potential difference than the barrier layer 914, which allows the channel region 922 to provide a lower barrier to negative charges than the barrier layer 914. As a result, an N-type anti-halo channel can be formed in the channel region 922, between the N-type region 912 and the floating drain 818, to conduct excess charge from the first photodiode 808 and the barrier layer 914. The anti-halo channel can be formed along a horizontal / lateral direction (e.g., parallel to the x / y axis and / or parallel to the front side surface 902). The dopant layer 1202 may include an N-type dopant and may have a lower dopant concentration than, for example, the N-type region 912 and the floating drain 818 to avoid excessive reduction of the barrier, which may reduce the full well capacity of the N-type region 912. In some examples, the dopant layer 1202 may be positioned away from the front side surface 902 so that the anti-halo channel can be formed as a buried channel away from the front side surface 902. The buried channel may be formed away from the crystal defects at the interface between the front side surface 902 and the oxide layer 916, compared to a surface channel formed directly below the front side surface 902 and the oxide layer 916. With this arrangement, the buried channel may be less susceptible to dark current caused by charge recombination at the crystal defects and may provide improved dark current performance.

[0124] Fig. 12C An exemplary anti-halation operation provided by the dopant layer 1202 is shown. Fig. 12C As shown, using the dopant layer 1202, the potential of the channel region 922 can be set at P 922 , which is relative to P 空 Higher than P sub As a result, the channel region 922 may present a lower potential barrier than the barrier layer 914. After a certain amount of negative charge is accumulated, the potential of the N-type region 912 reaches P 922 Afterwards, the additional negative charge generated in the N-type region 912 can flow to the floating drain 818 via the channel region 922, so that the potential of the N-type region 912 is maintained at P 922 . The potential of the barrier layer 914 (P sub ) remains below P 922 When the N-type region 906 is not filled with negative charges, the additional negative charges will not flow through the barrier layer 914 into the N-type region 906. The floating drain 818 can be connected to a charge absorber to discharge the additional negative charges.

[0125] Although the dopant layer 1202 can reduce or prevent the image blooming caused by the first photodiode 808, it cannot solve the image blooming caused by the saturation of the N-type region 906 (of the second photodiode 810). Fig.13As shown, since, for example, the first light component 822 or the second light component 824 has a very high intensity, a large amount of negative charges may be accumulated in the N-type region 906. As more negative charges including the charge 1302 are accumulated in the N-type region 906, the potential of the N-type region 906 continues to decrease and may become equal to or lower than P sub At this time, since there is no other conduction path to conduct the charge 1302, the charge 1302 can leak from the N-type region 906 through the barrier layer 914 and move to the N-type region 912 (of the first photodiode 808) and contaminate the charge accumulated in the N-type region 912, which represents the measurement of different light components. The charge 1302 can also leak into adjacent pixel units and contaminate the charge stored in these pixel units.

[0126] Fig.14A and Fig. 14B Examples of components of the pixel unit 800 that may reduce or prevent image blooming caused by saturation of the second photodiode 810 are shown. Fig.14A The pixel unit 800 is shown as a BSI device, while Fig. 14B The pixel unit 800 is shown as a FSI device. Fig.14A and Fig. 14B As shown, the pixel unit 800 may include a channel region 1402 extending from the N-type region 906 (of the second photodiode 810), through the barrier layer 914, and to the floating drain 818. The channel region 1402 may be formed, for example, by one or more ion implantation processes to form a strip that intersects the P-well 908, the P-type barrier layer 914, and the N-type dopant in the P-type semiconductor substrate 802 in a vertical direction (e.g., parallel to the z-axis). The N-type dopant may set the potential of the channel region 1402 relative to the bias voltage of the P-well 908, the P-type barrier layer 914, and the P-type semiconductor substrate 802. As a result, the potential of the channel region 1402 relative to the empty quantum well is P 空 Having a lower potential difference than the barrier layer 914, this allows the channel region 1402 to provide a lower barrier to negative charges than the barrier layer 914. As a result, the channel region 1402 can conduct excess charge from the N-type region 906 and the barrier layer 914. A vertical anti-blooming channel (e.g., parallel to the z-axis) can be formed between the floating drain 818 and the N-type region 906. The dopant concentration of the channel region 1402 can be lower than, for example, the N-type region 906 and the floating drain 818 to avoid excessively lowering the barrier, which may reduce the full well capacity of the N-type region 906. Multiple ion implantation steps with different implantation energies and doses can be performed from the front side surface 902 to allow the N-type dopant to penetrate deeply into the semiconductor substrate 802 while maintaining a certain distance from the N-type region 912.

[0127] Fig. 14C An example anti-blooming operation provided by channel regions 922 and 1402 is shown. Fig. 14C As shown, the potential of the channel region 1402 can be set at a relative potential to P 空 Higher than P sub P 1402 As a result, the channel region 1402 may present a lower potential barrier than the barrier layer 914. After a certain amount of negative charge is accumulated, the potential of the N-type region 906 reaches P 1402 Afterwards, the additional negative charge generated in the N-type region 906 can flow to the floating drain 818 via the channel region 1402, so that the potential of the N-type region 906 is maintained at P 1402 Since the potential of the barrier layer 914 (P sub ) remains below P 1402 , so the extra negative charge does not flow through the barrier layer 914 into the N-type region 912. In addition, as described above, another anti-blooming channel can be formed in the channel region 922 to conduct the extra negative charge away from the N-type region 912 and the barrier layer 914. The extra negative charge from the two N-type regions 906 and 912 can flow to the floating drain 818, which can be connected to a charge absorber to discharge the extra negative charge.

[0128] In some examples, such as Fig.14D As shown, the pixel unit 800 may include a second drain 1420 connected to the channel region 1402 to drain excess negative charge from the N-type region 906. This arrangement can reduce the interference of the anti-blooming operation of the channel region 1402 on the charge readout from the first photodiode 808. Specifically, in Fig.14A and Fig. 14B In the arrangement of , while the polysilicon gate 918 transfers charge from the N-type region 912 to the floating drain 818 for readout, the channel region 1402 can transfer excess charge from the N-type region 906 to the floating drain 818. As a result, excess charge from the anti-blooming operation of the N-type region 912 contaminates the readout charge at the floating drain 818. On the other hand, moving the excess charge to the second drain 1420 can avoid interfering with the readout operation at the floating drain 818. Alternatively, during the readout operation, a shutter device (e.g., shutter 404) can be used to stop the exposure of the N-type regions 906 and 912 to the light 816, which can also reduce the interference of the anti-blooming operation of the N-type region 912 with the readout operation at the floating drain 818.

[0129] Fig.15A and Fig. 15B An example of a pixel cell 800 having a channel region 1402 and components for controlling the potential of a barrier layer 914 is shown. Fig.15A and Fig. 15BThe pixel unit 800 in FIG. 8 can be configured as an FSI device or a BSI device. Fig.15A As shown, the pixel unit 800 may include conductive deep trench insulation (C-DTI) 1502a and 1502b, which extend from the front side surface 902 into the first semiconductor substrate 802 along a vertical direction (e.g., parallel to the z-axis). The C-DTI includes an insulating layer 1504 (e.g., an oxide layer) and a conductive material 1506 (e.g., polysilicon). The C-DTI 1502a and 1502b can reach the lateral sides of the barrier layer 914. Each of the C-DTI 1502a and 1502b can conduct a signal received from the front side surface 902 to form a lateral electric field (e.g., parallel to the x / y axis) on the barrier layer 914, which can push charges from the barrier layer 914 to adjust its potential. The C-DTI 1502a and 1502b can also provide insulation between the photodiodes of adjacent pixel units. As shown Fig.15A As shown on the left side of FIG. 1 , C-DTI 1502a and 1502b can reach the lateral sides of the P-well 908 (of the first photodiode 808) and the N-type region 912 and the barrier layer 914 to provide insulation for the first photodiode 808 and the barrier layer 914. In addition, as shown in FIG. Fig.15A As shown on the right side of FIG. 8 , C-DTI 1502 a and 1502 b may extend through barrier layer 914 and reach the lateral sides of N-type region 906 , thereby also providing insulation for second photodiode 810 .

[0130] Fig. 15B Other examples of pixel cells 800 that control the potential of barrier layer 914 are shown. Fig. 15B As shown on the left side of the figure, C-DTI 1502a and 1502b can extend from the back surface 904 to insulate the first semiconductor substrate 802, N-type region 906, barrier layer 914, N-type region 912 and P well 908. This arrangement can further improve the insulation between adjacent pixel units. A contact 1508 can also be provided on the back surface 904 to provide access to C-DTI 1502a and 1502b and the first semiconductor substrate 802.

[0131] In some examples, such as Fig. 15BAs shown on the right side of , the pixel unit 800 may include a polysilicon gate 1510 extending from the front side surface 902 through the N-type region 912 to the barrier layer 914. The polysilicon gate 1510 is insulated from the N-type region 912 and the barrier layer 914 by the oxide layer 916. The polysilicon gate 1510 can conduct a voltage to the barrier layer 914. The voltage can apply an electric field on the oxide layer 916 to push negative charges from the barrier layer 914, which can adjust the potential of the barrier layer 914. The pixel unit 800 may also include a guard ring 1516 to insulate the polysilicon gate 1510 from the N-type region 906, thereby preventing the voltage from affecting the potential of the N-type region 906. The pixel unit 800 also includes DTIs 1522a and 1522b to provide insulation between adjacent pixel units. The DTI does not need to be conductive because the DTI does not need to conduct an electric field to change the potential of the barrier layer 914 , which can be adjusted by the polysilicon gate 1510 .

[0132] Fig.16A and Fig. 16B Additional examples of components of the pixel cell 800 are shown that may reduce or prevent image blooming caused by saturation of the second photodiode 810 . Fig.16A Pixel cell 800 is shown as a BSI device, while Fig. 16B Pixel unit 800 is shown as a FSI device. Fig.16A and Fig. 16B As shown, the pixel unit 800 may include a drain 1604 and a channel region 1602 formed on the back surface 904. The channel region 1602 may be connected to a voltage source ( Fig.16A and Fig. 16B ), to set the potential of the channel region 1602, while the drain 1604 may be connected to a charge absorber. Fig. 16C , the periphery of the pixel unit 800 may include a heavily doped P-type region 1606 and a heavily doped N-type region 1608. Both the P-type region 1606 and the N-type region 1608 may be embedded with the P-type well 908 and the P-type first semiconductor substrate 802, and extend from the front surface 902 and pass through the pixel unit 800 along the vertical axis. The P-type region 1606 may be connected to an electrical contact 1610 on the front surface 902 to provide a path from the front surface 902 to the channel region 1602 for connecting a bias voltage source, and the N-type region 1608 may be connected to an electrical contact 1612 on the front surface 902 to provide a path from the front surface 902 to the drain 1604 for connecting a charge absorber. The channel region 1602 may be biased to a potential P relative to the empty quantum well. 空Having a lower potential difference than the barrier layer 914 allows the channel region 1602 to provide a lower barrier to negative charges than the barrier layer 914. As a result, the channel region 1602 can conduct excess charge from the N-type region 906 and the barrier layer 914. The drain 1604 can be connected to a charge absorber to drain excess charge from the channel region 1602. As a result, a vertical anti-halation channel (e.g., parallel to the z-axis) can be formed between the N-type region 906 and the drain 1604. The channel region 1602 can be formed as a P-type epitaxial layer on the back surface 904, and the drain 1604 can be formed by N-type dopants on the P-type epitaxial layer. Fig.16A In the embodiment, the pixel unit 800 is configured as a BSI device, and the channel region 1602 and the drain 1604 can be in the propagation path of the light 816. The thickness of the channel region 1602 and the drain 1604 can be minimized to reduce the absorption of the second light component 824 of the light 816 by the channel region 1602 and the drain 1604.

[0133] Fig.16D An example anti-blooming operation provided by channel regions 922 and 1602 is shown. Fig.16D As shown, the potential of the channel region 1602 can be set at a relative potential to P 空 Higher than P sub P 1502 As a result, the channel region 1602 may present a lower potential barrier than the barrier layer 914. After a certain amount of negative charge is accumulated, the potential of the N-type region 906 reaches P 1502 Afterwards, the additional negative charge generated in the N-type region 906 can flow to the drain 1604 via the channel region 1602, so that the potential of the N-type region 906 is maintained at P 1502 Since the potential of the barrier layer 914 (P sub ) remains below P 1502 , so the extra negative charge does not flow through the barrier layer 914 into the N-type region 912. In addition, as described above, another anti-blooming channel can be formed in the channel region 922 to conduct the extra negative charge from the N-type region 912 and the barrier layer 914 to the floating drain 818.

[0134] Fig.17A and Fig. 17B 1 shows an example of a pixel unit 800 having a channel region 1602 and a drain 1604 and a component for controlling the potential of a barrier layer 914. The component for controlling the potential of the barrier layer 914 is connected to Fig.15A and Fig. 15B The components described in are the same as those described in , and their description will not be repeated here. Fig. 17B In , electrical contacts 1702 and 1704 may be provided to provide access to the channel region 1602 and the drain 1604, respectively. Fig.17A and Fig. 17B In the embodiment, if the channel regions 1602 and drains 1604 of adjacent pixel cells are not insulated from each other by DTI or CDTI, they can be shorted together. Shorting the channel regions 1602 and drains 1604 of adjacent pixel cells can further reduce the resistance of the conductive path from the second photodiode 810 of each pixel cell to the charge absorber, which can accelerate the transfer of excess charge from the pixel cell and further improve the anti-blooming operation.

[0135] The foregoing description of the embodiments of the present disclosure is presented for illustrative purposes; it is not intended to be exhaustive or to limit the disclosure to the precise form disclosed. Those skilled in the relevant art can recognize that many modifications and variations are possible in light of the above disclosure.

[0136] Some parts of this description describe embodiments of the present disclosure from the aspect of algorithms and symbolic representations of operations on information. Those skilled in the art of data processing typically use these algorithmic descriptions and representations to effectively convey the essence of their work to other technicians in the field. Although these operations are described functionally, computationally, or logically, it should be understood that they will be implemented by computer programs or equivalent circuits, microcodes, etc. In addition, it is sometimes proven to be convenient to refer to these arrangements of operations as modules without loss of generality. The described operations and their associated modules can be embodied in software, firmware, and / or hardware.

[0137] The steps, operations or processes described may be performed or implemented using one or more hardware or software modules alone or in combination with other devices. In some embodiments, the software modules are implemented using a computer program product including a computer-readable medium containing computer program code, which may be executed by a computer processor to perform any or all of the steps, operations or processes described.

[0138] Embodiments of the present disclosure may also relate to an apparatus for performing the described operations. The apparatus may be specially constructed for the desired purpose, and / or it may include a general-purpose computing device selectively activated or reconfigured by a computer program stored in a computer. Such a computer program may be stored in a non-transitory, tangible computer-readable storage medium, or any type of medium suitable for storing electronic instructions, which may be coupled to a computer system bus. In addition, any computing system mentioned in the specification may include a single processor, or may be an architecture that uses a multi-processor design to increase computing power.

[0139] Embodiments of the present disclosure may also relate to products produced by the computing processes described herein. Such products may include information produced by the computing processes, wherein the information is stored on a non-transitory, tangible computer-readable storage medium and may include any embodiment of a computer program product or other data combination described herein.

[0140] The language used in the specification is selected primarily for readability and instructional purposes, and it may not be selected to describe or limit the subject matter of the invention. Therefore, it is intended that the scope of the present disclosure is not limited by this detailed description, but by any claims issued on an application based thereon. Therefore, the disclosure of the embodiments is intended to be illustrative, rather than restrictive, of the scope of the present disclosure, which is set forth in the appended claims.

Claims

1. A multi-photodiode pixel unit device, comprising: A semiconductor substrate comprising: Front surface, a first photodiode for generating a first charge, A second photodiode for generating a second charge, wherein the first photodiode and the second photodiode are stacked; a barrier layer located between the first photodiode and the second photodiode and configured to control the flow of the second charges from the second photodiode to the first photodiode, and a drain region for storing at least a first portion of the second charge and the first charge; a gate located on the front side surface above a first channel region between the first photodiode and the drain region to control flow of the at least a first portion of the second charges and the first charges to the drain region; and a second channel region for conducting at least a second portion of the second charge away from the second photodiode and the barrier layer when the second photodiode is saturated; The second photodiode is sandwiched between the barrier layer and the second channel region. 2 . The multi-photodiode pixel cell device of claim 1 , wherein the second channel region is a portion of the semiconductor substrate and intersects the barrier layer. 3 . The multi-photodiode pixel cell device of claim 2 , wherein the second channel region is connected between the second photodiode and the drain region.

4. The multi-photodiode pixel unit device according to claim 3, wherein: Each of the drain region and the second channel region comprises an N-type semiconductor material; and The second channel region is connected to the N-type region of the second photodiode.

5. The multi-photodiode pixel unit device of claim 4, wherein the semiconductor substrate further comprises a P-well surrounding the N-type region of the second photodiode; and The second channel region is formed in the P well. 6 . The multi-photodiode pixel cell device of claim 4 , wherein a first dopant concentration of the second channel region is lower than a second dopant concentration of the N-type region of the second photodiode.

7. The multi-photodiode pixel unit device of claim 1, wherein: The drain region is a first drain region; The semiconductor substrate further includes a second drain region; and The second channel region is connected between the second photodiode and the second drain region. 8 . The multi-photodiode pixel unit device of claim 1 , wherein the second channel region is formed by an ion implantation process. 9 . The multi-photodiode pixel cell device of claim 7 , wherein the second channel region comprises an epitaxial layer formed on a backside surface of the semiconductor substrate, the backside surface being opposite to the frontside surface of the semiconductor substrate.

10. The multi-photodiode pixel unit device of claim 7, wherein: The semiconductor substrate further includes a first conductive region and a second conductive region extending from the front side surface and configured to receive a first voltage and a second voltage, respectively; The first conductive region extends from the front side surface to the second channel region and is configured to bias the second channel region with the first voltage; and The second conductive region extends from the front-side surface to the second drain region and is configured to bias the second drain region with the second voltage.

11. The multi-photodiode pixel cell device of claim 7, wherein the second channel region comprises a P-type semiconductor material; and The second drain region includes an N-type semiconductor material.

12. The multi-photodiode pixel unit device of claim 1, wherein: The semiconductor substrate includes a backside surface opposite to the frontside surface, the backside surface being configured as a light receiving surface; The first photodiode is configured to convert a first component of light in the infrared wavelength range into the first charge; and The second photodiode is configured to convert a second component of light in the visible wavelength range into the second charge.

13. The multi-photodiode pixel unit device of claim 1, wherein: The front side surface is configured as a light receiving surface; The first photodiode is configured to convert a first component of light in the visible wavelength range into the first charge; and The second photodiode is configured to convert a second component of light in the infrared wavelength range into the second charge.

14. The multiple photodiode pixel cell device of claim 1, wherein the first channel region comprises a buried layer.

15. The multi-photodiode pixel unit device of claim 14, further comprising a conductive deep trench isolation (C-DTI) structure extending from the front side surface and spanning the N-type region of the first photodiode and the barrier layer; and The C-DTI structure is configured to receive a voltage and bias the barrier layer based on the voltage. 16 . The multi-photodiode pixel cell device of claim 15 , wherein the C-DTI structure extends across an N-type region of the second photodiode.

17. The multi-photodiode pixel unit device of claim 1, further comprising: a dorsal surface opposite to the anterior surface; and a C-DTI structure extending from the backside surface and spanning the N-type region of the second photodiode and the barrier layer, The C-DTI structure is configured to receive a voltage signal and bias the barrier layer based on the voltage signal.

18. The multi-photodiode pixel cell device of claim 1, wherein: The gate is a first gate; The device also includes a second gate extending from the front side surface to the barrier layer; and The second gate is configured to receive a voltage signal and bias the barrier layer based on the voltage signal.

Images