Image sensing device

Abstract

An image sensing device includes a pixel array. The pixel array includes: a sensing region in which a plurality of unit pixels for generating photo charges corresponding to incident light and capturing the generated photo charges are arranged; a bias field region provided along an edge of the sensing region; and a contact portion for supplying a bias voltage to the bias field region. The photo charges are moved by the bias voltage.

Description

Technical Field

[0001] The technology and implementation disclosed in this patent document generally relate to an image sensing device that includes pixels configured to detect incident light and measure the distance between the image sensing device and a target object. Background Art

[0002] An image sensing device is a device that captures an optical image by converting light into an electrical signal using a photosensitive semiconductor material that responds to light. With the development of the automotive, medical, computer, and communication industries, the demand for high-performance image sensing devices is increasing in various fields such as smart phones, digital cameras, game consoles, IoT (Internet of Things), robots, security cameras, and medical micro cameras.

[0003] Image sensing devices can be roughly classified into CCD (Charge-Coupled Device) image sensing devices and CMOS (Complementary Metal Oxide Semiconductor) image sensing devices. Compared with CMOS image sensing devices, CCD image sensing devices provide better image quality, but they tend to consume more power and are larger in size.

[0004] CMOS image sensing devices are smaller in size and consume less power than CCD image sensing devices. In addition, CMOS sensors are manufactured using CMOS manufacturing technology, so photosensitive elements and other signal processing circuits can be integrated into a single chip, enabling the manufacture of miniaturized image sensing devices at low cost. For these reasons, CMOS image sensing devices are being developed for many applications including mobile devices. Summary of the Invention

[0005] Various embodiments of the disclosed technology relate to an image sensing device capable of improving the light charge detection efficiency and reducing the noise generated by dark current.

[0006] According to an embodiment of the disclosed technology, an image sensing device may include a pixel array. The pixel array includes: a sensing region including a plurality of unit pixels, each unit pixel detecting incident light to generate a light charge indicative of the detected incident light; a bias field region doped with impurities and disposed along an edge of the sensing region; and a contact portion connected to the bias field region to apply a bias voltage to the bias field region to move the light charge in the sensing region.

[0007] In some implementations, the pixel array further includes: a passivation region formed to overlap the sensing region, wherein the pixel array is formed in a semiconductor layer, wherein the bias field region is located at a first depth within the semiconductor layer, and the passivation region is located at a second depth within the semiconductor layer, and wherein the first depth is greater than the second depth.

[0008] In some implementations, the bias field region is formed to surround the passivation region, and the bias field region is formed to contact the contact portion.

[0009] In some implementations, the bias field region is disposed along the edge of the passivation region; and the passivation region is formed to overlap with the bias field region.

[0010] In some implementations, each unit pixel includes: a control region that generates a current in a semiconductor layer in which the unit pixel is provided; and a detection region that captures optical charges that move through the current.

[0011] In some implementations, a demodulation control signal is applied to the control region, where the demodulation control signal is formed by repeating a first voltage and a second voltage at a predetermined time interval.

[0012] In some implementations, the demodulation control signal is any one of two different demodulation control signals having a 180-degree phase difference between them.

[0013] In some implementations, the demodulation control signal is any one of four different demodulation control signals having a 90-degree phase difference between them.

[0014] In some implementations, the optical charges move in a direction from the bias field region to the control region.

[0015] In some implementations, the bias voltage is lower than each of the first voltage and the second voltage.

[0016] According to another embodiment of the disclosed technology, an image sensing device may include: a sensing region including a plurality of unit pixels, each unit pixel including a control region for receiving a first voltage or a second voltage and a detection region for capturing electrons that move through the first voltage or the second voltage; a bias field region disposed along the edge of the sensing region; a contact portion connected to the bias field region to apply a bias voltage to the bias field region; and a bias voltage controller that transmits the bias voltage to the contact portion, where the bias voltage is lower than each of the first voltage and the second voltage.

[0017] In some other implementations, the image sensing device may further include: a passivation region formed to overlap with the sensing region, where the bias field region is at a first depth within the semiconductor layer and the passivation region is at a second depth within the semiconductor layer, and where the first depth is greater than the second depth.

[0018] In some other implementations, the bias field region is formed to surround the passivation region; and the bias field region is formed to contact the contact portion.

[0019] In some other implementations, the bias field region is disposed along an edge of the passivation region; and the passivation region is formed to overlap with the bias field region.

[0020] According to another embodiment of the disclosed technology, an image sensing device may include: a sensing region including a plurality of unit pixels formed in a substrate to generate photo charges and capture the generated photo charges; a bias field region doped with a first impurity and formed from a surface of the substrate to a first depth in the substrate along an edge of the sensing region; a passivation region doped with the first impurity and formed from the surface of the substrate to a second depth in the substrate above the sensing region; and a contact portion connected to the bias field region to apply a bias voltage to the bias field region to move the photo charges, wherein the first depth is greater than the second depth.

[0021] In some other implementations, the bias field region is formed to surround the passivation region; and the bias field region is formed to contact the contact portion.

[0022] In some other implementations, the bias field region is disposed along an edge of the passivation region; and the passivation region is formed to overlap with the bias field region.

[0023] In some other implementations, each unit pixel includes: a control region that generates a current in a semiconductor layer where the unit pixel is disposed; and a detection region that captures photo charges moved by the current.

[0024] It should be understood that the foregoing general description and the following detailed description of the disclosed technology are both exemplary and explanatory and are intended to provide further explanation of the claimed disclosure. Description of the Drawings

[0025] Figure 1 is a block diagram illustrating an example of an image sensing device based on some implementations of the disclosed technology.

[0026] Figure 2 is a schematic diagram illustrating an example of a pixel array based on some implementations of the disclosed technology.

[0027] Figure 3 is illustrative of a cross-section of a unit pixel taken along Figure 2 line A-A' shown and a circuit diagram of a constituent circuit connected to the unit pixel based on some implementations of the disclosed technology.

[0028] Figure 4 is illustrative of a cross-section of an example of a pixel array taken along Figure 2 line B-B' shown based on some implementations of the disclosed technology.

[0029] Figure 5 is illustrative of a cross-section taken alongFigure 2 A cross-sectional view of another example of a pixel array taken along line B-B' as shown.

[0030] Figure 6 Illustrates some implementations based on the disclosed technology along Figure 2 A cross-sectional view of yet another example of a pixel array taken along line B-B' as shown.

[0031] Figure 7 A cross-sectional view of a partial structure of a pixel array including a contact portion that illustrates some other implementations based on the disclosed technology.

[0032] Figure 8 A timing diagram that illustrates an example of the phase difference between demodulation control signals based on some implementations of the disclosed technology.

[0033] Figure 9 A timing diagram that illustrates an example of the phase difference between demodulation control signals based on some implementations of the disclosed technology.

[0034] Figure 10 A graph that illustrates an example of the potential gradient generated in response to a bias voltage based on some implementations of the disclosed technology. Detailed Description

[0035] This patent document provides implementations and examples of image sensor device designs that can be used in configurations to substantially solve one or more technical or engineering problems and alleviate limitations or disadvantages encountered in some other image sensor device designs. Some implementations of the disclosed technology relate to image sensor devices that can improve the optical charge detection efficiency while reducing noise generated by dark current. To solve the above problems, the disclosed technology can be implemented in some embodiments to provide such an image sensor device that includes a bias field region disposed along the edge of the sensing region, thereby adjusting the electric field of the substrate by applying a bias voltage to the bias field region. The disclosed technology can be implemented in some embodiments to mitigate the recombination phenomenon of electrons generated in response to incident light by adjusting the depth of the bias field region, thereby reducing the occurrence of dark current caused by forming a contact region.

[0036] Hereinafter, various embodiments will be described with reference to the accompanying drawings. However, it should be understood that the disclosed technology is not limited to specific embodiments, but includes various modifications, equivalents, and / or alternatives of the embodiments. The embodiments of the disclosed technology can provide various effects that can be directly or indirectly recognized through the disclosed technology.

[0037] Distance and depth measurement techniques that enable an image sensing device to measure the distance between the image sensing device and a target object have seen significant development and progress. The rapid growth of electronic devices that use image sensors, such as safety devices, medical devices, vehicles, gaming machines, virtual reality (VR) / augmented reality (AR) devices, and mobile devices, has led to a greater demand for advanced methods of measuring depth information. Such methods of measuring depth information using one or more image sensors include triangulation, time-of-flight (TOF) methods, and interferometry. The time-of-flight (TOF) method is applicable to various technical fields, can be performed at higher speeds, and has superior cost-effectiveness.

[0038] The ToF method is mainly divided into a direct method and an indirect method. Although both the direct method and the indirect method use transmitted light and reflected light to calculate the distance (i.e., depth) between the image sensor and the target object, the direct method and the indirect method can have different measurement methods.

[0039] The direct method can calculate the round-trip time and use the calculated round-trip time to measure the distance between the image sensor and the target object. The indirect method can use the phase difference to measure the distance between the image sensor and the target object. The direct method is used to measure longer distances and is thus widely used in vehicles. The indirect method is used to measure shorter distances and is thus widely used in various high-speed devices designed to operate at higher speeds, such as gaming machines, mobile cameras, etc. The indirect method has a simple circuit design and can thus be implemented at a lower cost.

[0040] As an example of an indirect TOF sensor, the current-assisted photon demodulator (CAPD) method is performed to detect electrons that have been generated in a pixel using the majority carrier current obtained by applying a control voltage to a unit pixel and using the voltage difference caused by electrons. Thus, the CAPD method can detect electrons faster by using the majority carrier current and can detect electrons formed at a deeper depth.

[0041] Figure 1 FIG. is a block diagram illustrating an example of an image sensing device ISD that exemplifies some implementations of the disclosed technology.

[0042] Referring to Figure 1 , the image sensing device ISD can measure the distance between the image sensing device ISD and the target object 1 using the time-of-flight (TOF) principle. The image sensing device ISD can include a light source 10, a lens module 20, a pixel array 30, and a control block 40.

[0043] The light source 10 can emit light to the target object 1 when receiving the light modulation signal MLS from the control block 40. The light source 10 can be a laser diode (LD) or a light emitting diode (LED) for emitting light with a specific wavelength band (e.g., near-infrared (NIR) light, infrared (IR) light, or visible light). In another implementation, the light source 10 can be any one of a near-infrared laser (NIR), a point light source, a monochromatic light source combined with a white light or a monochromator, and a combination of other laser sources. For example, the light source 10 can emit infrared light with a wavelength of 800 nm to 1000 nm. The light emitted from the light source 10 can be light modulated by a predetermined frequency (e.g., modulated light). Although for ease of illustration, Figure 1 only one light source 10 is shown, multiple light sources can also be arranged near the lens module 20.

[0044] The lens module 20 can collect the light reflected from the target object 1 and can allow the collected light to converge onto the pixels (PX) of the pixel array 30. For example, the lens module 20 can include a converging lens having a surface formed of glass or plastic, or another cylindrical optical element having a surface formed of glass or plastic. The lens module 20 can include a plurality of lenses arranged to converge on the optical axis.

[0045] The pixel array 30 can include unit pixels (PX) continuously arranged in rows and columns in a two-dimensional (2D) matrix array. The unit pixel (PX) can be the smallest unit repeatedly arranged in the same shape within the pixel array.

[0046] In some implementations, each unit pixel can include a plurality of sub-pixels arranged in a matrix array.

[0047] The unit pixel (PX) can be formed above a semiconductor substrate or an epitaxial layer. Each unit pixel (PX) can convert the incident light received through the lens module 20 into an electrical signal corresponding to the intensity of the incident light and can generate a pixel signal using the electrical signal. In this case, the pixel signal can be a signal indicating the distance between the unit pixel and the target object 1 without indicating the color of the target object 1.

[0048] The area where the unit pixel (PX) is disposed above the pixel array 30 will be hereinafter referred to as the sensing area. The unit pixel (PX) located in the sensing area can convert the incident light into an electrical signal corresponding to the intensity of the incident light, and thus can output a pixel signal.

[0049] The pixel array 30 can include a bias field area positioned along the edge of the sensing area. The bias field area can be formed in the semiconductor substrate or the epitaxial layer. The image sensing device ISD can adjust the pixel signal output from the unit pixel (PX) by adjusting the voltage applied to the bias field area.

[0050] Each unit pixel (PX) can be a current-assisted photon demodulator (CAPD) pixel. The structure and operation of each unit pixel (PX) will be described below with reference to Figures 2 to 10 the description of the structure and operation of each unit pixel (PX).

[0051] The control block 40 can emit light from the light source 10 to the target object 1, can process each pixel signal corresponding to the light reflected from the target object 1 by driving the unit pixels (PX) of the pixel array 30, and can use the processed result to measure the distance between the unit pixel and the surface of the target object 1.

[0052] The control block 40 can include a row driver 41, a demodulation driver 42, a light source driver 43, a timing controller 44, and a readout circuit 45.

[0053] The row driver 41 can activate the unit pixels (PX) of the pixel array in response to the timing signal generated by the timing controller 44. For example, the row driver 41 can generate a control signal for selecting and controlling at least one of a plurality of row lines. The control signal can include a reset signal RST for controlling a reset transistor, a transfer signal TRG for controlling the transfer of the optical charges accumulated in the detection region, a floating diffusion signal FDG for providing an additional capacitance at a high illumination level, a selection signal SEL for controlling a selection transistor, etc.

[0054] Although, for ease of description, Figure 1 the row driver 41 is illustrated as being arranged in the column direction (e.g., the vertical direction) of the pixel array 30, at least a part of the row driver 41 can be arranged in the row direction (e.g., the horizontal direction) of the pixel array 30.

[0055] The demodulation driver 42 can generate a demodulation control signal to be applied to at least one of a plurality of unit pixels in response to the timing signal generated by the timing controller 44. The demodulation control signal can generate a potential difference in the substrate. The potential difference generated in the substrate can generate a hole current for moving electrons in the substrate.

[0056] The light source driver 43 can generate a light modulation signal MLS for operating the light source 10 in response to a control signal from the timing controller 44. The light modulation signal MLS can be a signal modulated at a predetermined frequency.

[0057] The timing controller 44 can generate a timing signal to control the row driver 41, the demodulation driver 42, the light source driver 43, and the readout circuit 45.

[0058] The readout circuit 45 can process the pixel signals received from the pixel array 30 under the control of the timing controller 44, and thus can generate pixel data such as digital pixel data. To this end, the readout circuit 45 can include a correlated double sampler (CDS) circuit for performing correlated double sampling (CDS) on the pixel signals generated by the pixel array 30.

[0059] In addition, the readout circuit 45 can include an analog-to-digital converter (ADC) for converting the output signal of the CDS circuit into a digital signal. In addition, the readout circuit 45 can include a buffer circuit that temporarily stores the pixel data generated by the analog-to-digital converter (ADC) and outputs the pixel data under the control of the timing controller 44. Since the pixel array 30 includes CAPD pixels, two column lines for transmitting pixel signals can be assigned to each column of the pixel array 30, and the structure for processing the pixel signals generated from each column line can correspond to each column line.

[0060] The light source 10 can emit light modulated at a predetermined frequency (e.g., modulated light) toward the scene captured by the image sensing device ISD. The image sensing device ISD can sense the modulated light (i.e., incident light) reflected from the target object 1 included in the scene, and thus can generate depth information for each unit pixel (PX).

[0061] A time delay based on the distance between the image sensing device ISD and each target object 1 can occur between the modulated light and the incident light. The time delay can be represented by the phase difference between the signal generated by the image sensing device ISD and the light modulation signal MLS that controls the light source 10. An image processor (not shown) can calculate the phase difference generated in the output signal of the image sensing device ISD, and thus can generate a depth image.

[0062] Figure 2 is a schematic diagram illustrating an example of the pixel array 30 based on some implementations of the disclosed technology.

[0063] Referring to Figure 2 , the pixel array 30 can include: a sensing region 31 that includes a plurality of unit pixels such as image sensing pixels and phase detection pixels; and a bias field region 32 that is disposed along the edge of the sensing region 31. In some implementations, a contact portion 33 is formed in or in electrical contact with the bias field region 32 to apply a bias voltage to the bias field region 32.

[0064] In addition, the contact portion 33 can be coupled to a bias voltage controller (not shown) that is configured to provide a bias voltage to the contact portion 33. In some implementations, the bias voltage controller can be included in a control block (e.g., Figure 1 of 40).

[0065] To enable a unit pixel (PX) to detect incident light based on control or timing signals received from a timing controller (e.g., Figure 1 44), a bias voltage controller can transmit a bias voltage to a substrate including a sensing region 31.

[0066] A plurality of unit pixels (PX) disposed in the sensing region 31 can respectively generate pixel signals in response to the incident light they each receive. A cross-sectional view of each unit pixel (PX) and other circuits connected to the unit pixel (PX) will be described later with reference to Figure 3 description.

[0067] In some implementations, a bias field region 32 can be disposed along the edge of the sensing region 31. The bias field region 32 can be formed in a semiconductor substrate or an epitaxial layer on which a pixel array 30 is provided. Since the bias field region 32 is disposed along the edge of the sensing region 31, the image sensing device ISD can effectively adjust the potential gradient inside the pixel array 30.

[0068] In some implementations, the semiconductor substrate or epitaxial layer in which the bias field region 32 is formed can be doped with P-type impurities. Additionally, the bias field region 32 can be a P-type impurity region having a higher doping concentration than the semiconductor substrate or epitaxial layer.

[0069] The lens module 20 can be formed to overlap with the pixel array 30. Since the incident light is converged by the lens module 20, the amount of light reaching one unit pixel (PX) disposed adjacent to the edge of the pixel array 30 can be different from the amount of light reaching another unit pixel (PX) disposed adjacent to the center of the pixel array 30.

[0070] Depending on the position of the unit pixel (PX) on the pixel array 30, this difference in the amount of light between unit pixels (PX) can cause a difference between pixel signals. Specifically, a unit pixel (PX) disposed adjacent to the edge of the pixel array 30 can receive a smaller amount of incident light than other unit pixels (PX) disposed adjacent to the center of the pixel array 30. Thus, depending on the position of the unit pixel (PX), the unit pixel (PX) can collect different amounts of photo charges generated in response to the incident light, thereby creating a difference between pixel signals.

[0071] In some implementations, since the bias field region 32 has a different doping concentration from the semiconductor substrate or epitaxial layer, a potential gradient may occur between the bias field region 32 and other regions of the pixel array 30.

[0072] Such a potential gradient causes the photo-generated charges generated in the region adjacent to the bias field region 32 to move from the region adjacent to the bias field region 32 to the unit pixel (PX). As a result, the unit pixel (PX) adjacent to the bias field region 32 can collect photo-generated charges more easily than other unit pixels (PX) far from the bias field region 32.

[0073] Therefore, the difference in pixel signals between one pixel disposed adjacent to the edge of the pixel array 30 and another pixel (PX) disposed adjacent to the center of the pixel array 30 can be compensated by the bias field region 32.

[0074] The contact portion 33 may be formed to overlap with the bias field region 32. In some implementations, the contact portion 33 may include a metal. For example, the metal may include at least one of tungsten (W), aluminum (Al), and copper (Cu). In some other implementations, the contact portion 33 may include polysilicon (Si).

[0075] The contact portion 33 may be in contact with the bias field region 32. The contact portion 33 may apply a bias voltage to the bias field region 32. In some implementations, the bias voltage may be a negative (-) voltage. As the negative (-) voltage is applied to the bias field region 32, a potential gradient may appear between the bias field region 32 and other regions of the pixel array 30.

[0076] The potential gradient generated when the negative (-) voltage is applied to the bias field region 32 may be greater than the potential gradient generated when the negative (-) voltage is not applied to the bias field region 32.

[0077] In other words, the negative (-) voltage applied to the bias field region 32 can promote the movement of photo-generated charges. Therefore, when the negative (-) voltage is applied to the bias field region 32, the unit pixel (PX) can collect photo-generated charges more easily than when the negative (-) voltage is not applied to the bias field region 32.

[0078] In some implementations, the bias field region 32 and the contact portion 33 do not overlap with the sensing region 31, so that the sensing region 31 can maximize the light receiving area.

[0079] Figure 3 Illustrates a schematic diagram 300 of a cross-section of a unit pixel (PX) taken along line A-A' shown in some implementations based on the disclosed technology and a circuit diagram of a constituent circuit connected to the unit pixel (PX). Figure 2 The following will describe the cross-sectional structure of the unit pixel (PX) and the method for operating the unit pixel (PX) with reference to

[0080] Hereinafter, the cross-sectional structure of the unit pixel (PX) and the method for operating the unit pixel (PX) will be described with reference to Figure 3 Describe the cross-sectional structure of the unit pixel (PX) and the method for operating the unit pixel (PX).

[0081] A unit pixel (PX) may include a photoelectric conversion region 311, a detection region 312, and a control region 313. In some implementations, the unit pixel (PX) may be formed in a semiconductor layer 310. The semiconductor layer 310 may include a semiconductor substrate or an epitaxial layer. For example, the semiconductor substrate may include a silicon wafer, and the epitaxial layer may include a crystal growth layer formed on the silicon wafer. In some implementations, the detection region 312 collects photo charges generated by the photoelectric conversion region 311, and the control region 313 receives control signals for controlling these operations.

[0082] In Figure 3 the example of, the photoelectric conversion region 311 may be formed in the semiconductor layer 310, and light rays may be incident on one surface of the semiconductor layer 310. The surface on which the light is incident will be referred to as the light receiving surface hereinafter.

[0083] In some implementations, the unit pixel (PX) is located at Figure 2 the sensing region 31 shown, and thus the photoelectric conversion region 311, the detection region 312, and the control region 313 may be included in the sensing region 31.

[0084] The semiconductor layer 310 may further include a passivation region (not shown) and a bias field region (not shown), but Figure 3 the circuit elements shown in are not limited to certain elements of each unit pixel (PX) drawn for the purpose of describing the characteristics and operations of the unit pixel.

[0085] In an implementation, the photoelectric conversion region 311 in each unit pixel (PX) is configured to respond to incident light and generate photo charges corresponding to the incident light received by the unit pixel (PX). The photoelectric conversion region 311 may include a plurality of doped regions or layers stacked on top of each other. For example, the photoelectric conversion region 311 may include a plurality of N-type doped regions and a plurality of P-type doped regions.

[0086] Each of the detection region 312 and the control region 313 may be formed to have a predetermined depth from the surface facing or opposite to the light receiving surface of the incident light with respect to the semiconductor substrate or the epitaxial layer.

[0087] Each of the detection region 312 and the control region 313 may be included in the unit pixel (PX). The detection region 312 may be doped with impurities different from those of the semiconductor layer 310. For example, when the semiconductor layer 310 is doped with P-type impurities, the detection region 312 may be doped with N-type impurities. The detection region 312 may include a plurality of doped regions having different impurity concentrations.

[0088] The detection region 312 can receive a detection voltage as an input. With the application of the detection voltage, the detection region 312 can easily collect the photo-charges generated in the photoelectric conversion region 311. A plurality of circuits can be connected to the detection region 312 to process the collected electrons and convert the electrons into an electrical signal. A plurality of circuits can be formed for each unit pixel (PX) including each detection region 312.

[0089] The control region 313 can be doped with the same impurities as the semiconductor layer 310. For example, when the semiconductor layer 310 is doped with P-type impurities, the control region 313 can be doped with P-type impurities. The control region 313 can include a plurality of doped regions having different impurity concentrations.

[0090] Although by way of example, Figure 3 it is illustrated that the lengths of the detection region 312 and the control region 313, each extending from one surface facing or opposite to the light receiving surface towards the light receiving surface, are similar, it should be noted that the control region 313 can be formed to have a longer length than the detection region 312. When the control region 313 has a longer length than the detection region 312, the detection region 312 can more easily capture photo-charges through the potential gradient formed between the photoelectric conversion region 311 and the control region 313.

[0091] In some implementations, a demodulation control signal (V cs ) corresponding to the unit pixel (PX) can be applied to the control region 313 respectively. The demodulation control signals (V cs ) applied to adjacent unit pixels (PX) can have different phase differences.

[0092] In some implementations, the demodulation control signal (V cs ) can be either of two signals having a 180-degree phase difference, and either of the two signals can be applied to two adjacent unit pixels (PX).

[0093] In other implementations, the demodulation control signal (V cs ) can be either of four different signals having a 90-degree phase difference, and either of the four signals can be applied to four adjacent unit pixels (PX).

[0094] The demodulation control signal (V cs ) can cause the first voltage (V 1 ) or the second voltage (V 2 ) to be repeatedly applied to the control region 313 at a predetermined time interval.

[0095] When the first voltage (V 1)When applied to the control region 313, current can flow between the control region 313 and the photoelectric conversion region 311 or between the control region 313 and a bias voltage region (not shown).

[0096] This current caused by the first voltage (V 1 ) can be a hole current. With the generation of the hole current, the detection region 312 adjacent to the control region 313 can capture electrons. For example, the first voltage (V 1 ) can be 1.2 volts (1.2V). The logic value of the demodulation driver 42 for applying the first voltage (V 1 ) can be at a logic high level (H).

[0097] When no current flows between the control region 313 and the photoelectric conversion region 311 or between the control region 313 and the bias voltage region included in each unit pixel (PX), a second voltage (V 2 ) applied to the control region 313 can be generated. For example, the second voltage (V 2 ) can be a ground voltage (V gnd ). The logic value of the demodulation driver 42 for applying the second voltage (V 2 ) can be at a logic low level (L).

[0098] The demodulation control signal (V cs ) can cause the first voltage (V 1 ) and the second voltage (V 2 ) to be applied to the control region 313 at a predetermined time interval. The demodulation control signals applied to the unit pixels will be described later with reference to Figure 8 and Figure 9 .

[0099] In some implementations, the unit pixels (PX) included in the sensing region 31 can be arranged in the photoelectric conversion region 311. The photoelectric conversion region 311 can occupy as large an area as possible within the pixel array 30.

[0100] Figure 3 Also illustrated is a circuit connected to the detection region 312 included in the unit pixel (PX).

[0101] In some implementations, the circuit connected to the detection region 312 can be formed above the same substrate on which the semiconductor layer 310 is formed. Hereinafter, the region where the above circuit is formed will be referred to as the circuit region 320.

[0102] The circuit region 320 may include multiple circuits to generate an electrical signal based on electrons captured by the detection region 312 and process the electrical signal. Control signals RST, TRG, FDG, and SEL may be received from the row driver 41. Additionally, the pixel voltage (V px ) may be the power supply voltage (VDD) or the source voltage or the ground voltage (VSS).

[0103] Although Figure 3 not shown in the figure, in some implementations, the circuit region 320 may be disposed between unit pixels (PX). In other implementations, the circuit region 320 may be formed to overlap with the sensing region 31 in which the unit pixels (PX) are disposed. The position of the circuit region 320 may vary according to the layout and structure of the unit pixels.

[0104] The circuit region 320 may include a reset transistor RX, a transfer transistor TX, a first capacitor C1, a second capacitor C2, a floating diffusion transistor FDX, a driving transistor DX, and a selection transistor SX.

[0105] The reset transistor RX may be activated in response to a logic high level (logic high voltage level) of the reset signal RST applied to its gate electrode, such that the voltage of the floating diffusion node (i.e., the floating diffusion region) FD and the voltage of the detection region 312 may be reset to a predetermined level (e.g., the pixel voltage V px ). Additionally, when the reset transistor RX is activated (e.g., in an active state), the transfer transistor TX may also be activated (e.g., in an active state) to reset the floating diffusion node FD.

[0106] The transfer transistor TX may be activated (e.g., in an active state) in response to a logic high level of the transfer signal TRG applied to its gate electrode, such that electrons accumulated in the detection region 312 may be transferred to the floating diffusion node FD.

[0107] The first capacitor C1 may be connected to the floating diffusion node FD, and the first capacitor C1 may provide a predetermined capacitance.

[0108] The second capacitor C2 may be selectively connected to the floating diffusion node FD according to the operation performed by the floating diffusion transistor FDX, and the second capacitor C2 may provide an additional predetermined capacitance.

[0109] Each of the first capacitor C1 and the second capacitor C2 may include at least one of, for example, a metal-insulator-metal (MIM) capacitor, a metal-insulator-polysilicon (MIP) capacitor, a metal-oxide-semiconductor (MOS) capacitor, and a junction capacitor.

[0110] The floating diffusion transistor FDX can be activated (e.g., in an active state) in response to a logic high level of the floating diffusion signal FDG applied to its gate electrode, so that the floating diffusion transistor FDX can connect the second capacitor C2 to the floating diffusion node FD.

[0111] For example, when the amount of incident light is sufficient and the image sensor is under relatively high illuminance conditions, the row driver 41 can activate the floating diffusion transistor FDX, such that the floating diffusion transistor FDX enters the active state and the floating diffusion node FD can be connected to the second capacitor C2. As a result, when the amount of incident light is sufficient and the image sensor is at a high illuminance level, the amount of photo-charge accumulated in the floating diffusion node FD increases, enabling high dynamic range (HDR) imaging.

[0112] On the other hand, when the amount of incident light is insufficient and the image sensor is at a relatively low illuminance level, the row driver 41 can control the floating diffusion transistor FDX to be deactivated (e.g., in a non-active state), such that the floating diffusion node FD can be isolated from the second capacitor C2.

[0113] In some other implementations, the floating diffusion transistor FDX and the second capacitor C2 can be omitted as needed.

[0114] The drain electrode of the driving transistor DX is connected to the pixel voltage (V px ), and the source electrode of the driving transistor DX is connected to the vertical signal line SL through the selection transistor SX, so that a load (MOS) and a source follower circuit of the constant current source circuit CS connected to one end of the vertical signal line SL can be constructed. Therefore, the driving transistor DX can output a current corresponding to the voltage of the floating diffusion node FD connected to the gate electrode to the vertical signal line SL through the selection transistor SX.

[0115] The selection transistor SX can be activated (i.e., in an active state) in response to a logic high level of the selection signal SEL applied to its gate electrode, such that the pixel signal generated from the driving transistor DX can be output to the vertical signal line SL.

[0116] The circuit region 320 can include a plurality of reset transistors (RX), a plurality of transfer transistors (TX), a plurality of first capacitors (C1), a plurality of second capacitors (C2), a plurality of floating diffusion transistors (FDX), a plurality of driving transistors (DX), and a plurality of selection transistors (SX) corresponding to a plurality of unit pixels (PX) included in the sensing region 31. That is, each unit pixel (PX) can include a reset transistor (RX), a transfer transistor (TX), a first capacitor (C1), a second capacitor (C2), a floating diffusion transistor (FDX), a driving transistor (DX), and a selection transistor (SX).

[0117] In some implementations, noise cancellation and analog-to-digital (ADC) conversion processing may be performed on pixel signals transmitted from the circuit region 320 to the vertical signal line SL, and each pixel signal may be converted into image data.

[0118] An image processor (not shown) may calculate the image data obtained from electrons captured by a plurality of unit pixels (PX), and thus may calculate a phase difference using the obtained image data.

[0119] Figure 4 is a cross-sectional view 400 illustrating an example of the pixel array 30 taken along the Figure 2 line B-B′ shown, which is an example based on some implementations of the disclosed technology.

[0120] Referring to Figure 4 , the photoelectric conversion region 411, the plurality of unit pixels (PX), and at least one bias voltage region (i.e., bias field region) 430 may be part of the semiconductor layer 410. At least one contact portion 440 may be formed in electrical contact with the bias voltage region 430 to apply a bias voltage to the bias voltage region 430. In some implementations, the contact portion 440 may include one of various suitable contacts such as metal contacts, doped contact regions, or contact plugs configured to connect transistors and other devices in the semiconductor substrate to each other.

[0121] Each unit pixel (PX) may include a detection region 412 and a control region 413, and at least a part of the photoelectric conversion region 411.

[0122] In some implementations, Figure 4 the structures and other technical features of the photoelectric conversion region 411, the detection region 412, and the control region 413 shown in Figure 3 may be the same as or similar to the structures and other technical features of the corresponding regions in Figure 4 . The bias field region 430 and the contact portion 440 will be described below with reference to

[0123] The bias field region 430 may be formed to extend from the light-receiving surface of the semiconductor layer 410 toward a surface facing the light-receiving surface.

[0124] The bias field region 430 may be formed below the contact portion 440 and may be formed in the edge of the pixel array 30. In this case, the edge of the pixel array 30 may be the edge region of the semiconductor layer 410.

[0125] The bias field region 430 can be formed in the edge of the pixel array 30 that is outside the pixel array 30 without overlapping any unit pixel (PX), so that the effective area of the light receiving region of the unit pixel (PX) is as large as possible to receive incident light, thereby generating a sufficient amount of photo charges.

[0126] The bias field region 430 can be formed to have a first depth (D1) from the light receiving surface of the semiconductor layer 410. Here, the first depth D1 can be deep enough to prevent the dark current component in the contact portion 440 from affecting the depth of the unit pixel (PX). Additionally, at the first depth (D1), the potential gradient inside the pixel array 30 can be easily adjusted by applying a bias voltage to the bias field region 430.

[0127] In some implementations, the depth of one surface of the bias field region 430 from the light receiving surface of the semiconductor layer 410 can be referred to as the first depth D1. In this case, the one surface of the bias field region 430 can be parallel to the light receiving surface of the semiconductor layer 410 and can be positioned away from the light receiving surface of the semiconductor layer 410.

[0128] However, when the area size of the region occupied by the bias field region 430 in the semiconductor layer 410 is large, it may not be possible to fully guarantee the region occupied by the photoelectric conversion region 411. Additionally, the photo charges generated from the photoelectric conversion region 411 by the bias field region 430 may recombine, thereby reducing the photoelectric conversion efficiency of the pixel array 30.

[0129] Therefore, the first depth D1 can be a depth that can easily adjust the potential gradient generated in the pixel array 30 and the occurrence of the dark current component and can prevent the recombination of photo charges.

[0130] Multiple unit pixels (PX) included in the sensing region 31 can be spaced apart from each other by a predetermined distance. Since the unit pixels (PX) are spaced apart from each other by a predetermined distance, the photo charges collected by each unit pixel can be isolated from each other. In some implementations, an isolation structure capable of electrically isolating the unit pixels (PX) from each other can be provided between the unit pixels (PX) so that the unit pixels (PX) can be easily isolated from each other through the isolation structure.

[0131] The potential gradient generated by the difference in doping concentration between the bias field region 430 and the semiconductor layer 410 and the potential gradient generated by the bias voltage can cause the photo charges to be generated by the photoelectric conversion region 411 included in the semiconductor layer 410 to easily flow into each unit pixel (PX). Specifically, the generated photo charges can flow into the control region 413 included in each unit pixel (PX) and can be captured by the detection region 412.

[0132] Figure 5 FIG. 500 is a cross-sectional view illustrating another example of the pixel array 30 taken along the line B-B′ shown in FIG. 1, which exemplifies some implementations of the disclosed technology. Figure 2 Referring to FIG. 1, in the semiconductor layer 510, a photoelectric conversion region 511, a plurality of unit pixels (PX), a bias voltage region 530, a contact portion 540, and a passivation region 550 may be formed.

[0133] Referring Figure 5 , in the semiconductor layer 510, a photoelectric conversion region 511, a plurality of unit pixels (PX), a bias voltage region 530, a contact portion 540, and a passivation region 550 may be formed.

[0134] In some implementations, the structures and other technical features of the photoelectric conversion region 511, the detection region 512, the control region 513, the bias field region 530, and the contact portion 540 may be the same as or similar to the structures and other technical features of the corresponding regions in FIG. 1. The passivation region 550 will be described below with reference to FIG. 1. Figure 4 Referring Figure 5 to FIG. 1, the passivation region 550 will be described below.

[0135] The passivation region 550 may be doped with the same impurities as the semiconductor layer 510. For example, the passivation region 550 may be doped with P-type impurities. The passivation region 550 may have the same doping concentration as the bias field region 530.

[0136] The passivation region 550 may extend from the light-receiving surface of the semiconductor layer 510 to a second depth D2. In some implementations, within the semiconductor layer 510, the second depth D2 may be less than the first depth D1 formed by the bias field region 530.

[0137] In some implementations, the depth of one surface of the passivation region 550 from the light-receiving surface of the semiconductor layer 510 may be referred to as the second depth D2. In this case, the one surface of the passivation region 550 may be parallel to the light-receiving surface of the semiconductor layer 510 and may be positioned away from the light-receiving surface of the semiconductor layer 510.

[0138] Since the passivation region 550 is formed to have a smaller depth than the bias field region 530, recombination of photo-charges generated in the passivation region 550 can be reduced. The photo-charges recombined in the passivation region 550 may be photo-charges generated by the photoelectric conversion region 511 provided below the passivation region 550.

[0139] The photo-charges generated by the photoelectric conversion region 511 may recombine with the holes of the passivation region 550 doped with the same impurities as the semiconductor layer 510, making it possible for distortion of the pixel signal to occur due to recombination of the photo-charges.

[0140] The passivation region 550 can be electrically connected to the bias field region 530. Since the passivation region 550 is electrically connected to the bias field region 530, a potential gradient can occur between the control region 513 of the unit pixel (PX) disposed adjacent to the center of the pixel array 30 and the passivation region 550.

[0141] Since the passivation region 550 is connected to the bias field region 530, a bias voltage can be applied to the passivation region 550. As the bias voltage is applied to the passivation region 550, a potential gradient can occur between the passivation region 550 and the control region 513. Compared with the case where the passivation region 550 is not formed, the photo charges generated by the photoelectric conversion region 511 adjacent to the center of the pixel array 30 can easily flow into the unit pixel (PX).

[0142] In some implementations, as the passivation region 550 is disposed closer to the bias field region 530, the potential gradient formed between the passivation region 550 and the control region 513 can increase. In other words, as the distance from the passivation region 550 to the edge of the pixel array 30 becomes shorter, the potential gradient between the passivation region 550 and the control region 513 can increase.

[0143] In some implementations, the passivation region 550 can be formed to be isolated from the region formed by the bias voltage region 530.

[0144] For example, a mask pattern (e.g., photoresist) is formed over the remaining regions except the region where the passivation region 550 is formed, and then the passivation region 550 is formed by an implantation process. Subsequently, a mask pattern is formed over the formed passivation region 550, and the bias field region 530 can be formed along the edge of the passivation region 550 by an implantation process.

[0145] In this case, a mask pattern is formed over the passivation region 550 by forming the bias field region 530, and the passivation region 550 overlaps with the sensing region 31.

[0146] Figure 6 Illustrates another example of a cross-sectional view 600 of the pixel array 30 taken along the line B - B' shown based on some implementations of the disclosed technology. Figure 2 as shown.

[0147] Referring to Figure 6 , a photoelectric conversion region 611, a plurality of unit pixels (PX), a bias voltage region 630, a contact portion 640, and a passivation region 650 can be formed in the semiconductor layer 610.

[0148] In some implementations, except for the passivation region 650 and the bias voltage region 630, the structures and other technical features of the photoelectric conversion region 611, the detection region 612, and the control region 613 can be the same asFigure 5 The structure and other technical features of the corresponding region are the same or similar.

[0149] In some other implementations, the passivation region 650 may extend from the light-receiving surface of the semiconductor layer 610 to a second depth D2. Additionally, the bias field region 630 may be formed to have a first depth D1 from the semiconductor layer 610. Within the semiconductor layer 610, the second depth D2 may be less than the first depth D1 formed by the bias field region 630.

[0150] In some implementations, the depth of one surface of the bias field region 630 from the light-receiving surface of the semiconductor layer 610 may be referred to as the first depth D1. In this case, the said one surface of the bias field region 630 may be parallel to the light-receiving surface of the semiconductor layer 610 and may be positioned away from the light-receiving surface of the semiconductor layer 610.

[0151] In some implementations, the depth of one surface of the passivation region 650 from the light-receiving surface of the semiconductor layer 610 may be referred to as the second depth D2. In this case, the said one surface of the passivation region 650 may be parallel to the light-receiving surface of the semiconductor layer 610 and may be positioned away from the light-receiving surface of the semiconductor layer 610.

[0152] The passivation region 650 and the bias field region 630 may have the same impurity type and the same doping concentration.

[0153] Additionally, the passivation region 650 may be electrically connected to the bias field region 630. Since the passivation region 650 is electrically connected to the bias field region 630, a potential gradient may occur between the control region 613 of the unit pixel (PX) adjacent to the center of the pixel array 30 and the passivation region 650.

[0154] In some other implementations, after forming the passivation region 650, the bias voltage region 630 may be formed by an implantation process.

[0155] For example, after the passivation region 650 is formed to have a second depth D2 from the light-receiving surface of the semiconductor layer 610, a mask pattern is formed over a part of the formed passivation region 650, and the bias field region 630 may be formed along the edge of the passivation region 650 by an implantation process. In this case, when forming the bias field region 630, the masked passivation region 650 may be formed to overlap with the sensing region 31.

[0156] In some other implementations, the formed bias field region 630 may be formed to overlap with the passivation region 650.

[0157] Figure 7FIG. 12 is a cross-sectional view of a partial structure 700 including a contact portion 740 of a pixel array 30 that illustrates some other implementations based on the disclosed technology.

[0158] In some implementations, Figure 7 the structures and other technical features of the photoelectric conversion region 711 and the passivation region 750 shown in FIG. 12 are the same as or similar to Figure 6 the structures and other technical features of the corresponding regions of FIG. 11. The constituent elements shown in FIG. 12 will be described below, and the bias field region 730 and the contact portion 740 will be specifically discussed below. Figure 7 Shown in FIG. 12,

[0159] Referring to FIG. 12, Figure 7 the contact portion 740 can etch a part of the bias field region 730 such that the contact portion 740 can be formed in contact with the etched bias field region 730. Since the contact portion 740 is formed at the position where the bias field region 730 is etched, the contact portion 740 and the bias field region 730 can be stably coupled to each other.

[0160] In addition, since the contact portion 740 is formed at the position where the bias field region 730 is etched, the bias voltage provided by the contact portion 740 can effectively move the electrons in the photoelectric conversion region 711.

[0161] In other words, since the contact portion 740 is formed at the position where the bias field region 730 is etched, the bias voltage can more greatly affect the photoelectric conversion region 711, enabling the optical charges to be easily moved by the bias voltage.

[0162] When the bias field region 730 is etched to form the contact portion 740, damage to the surface of the bias field region 730 may occur, and a dark current component may also appear in the etched region. Therefore, since the depth of the bias field region 730 can be sufficiently ensured, the dark current component generated in the etched region can be prevented from infiltrating into the photoelectric conversion region 711.

[0163] Figure 8 FIG. 13 is an example timing diagram that illustrates the phase difference between the demodulation control signals V cs1 and V cs2 based on some implementations of the disclosed technology.

[0164] Referring to FIG. 13, Figure 8 FIG. 14 Figure 8 illustrates the modulated light (ML), the incident light (IL), and the first demodulation control signal V cs1 and the second demodulation control signal V cs2 .

[0165] Associated with a plurality of unit pixels (PX) included in the sensing region 31, different demodulation control signals can be applied to adjacent unit pixels (PX).

[0166] The first demodulation control signal (V Figure 3 ) and the second demodulation control signal (V cs1 ) can be applied to control regions (e.g., cs2 ) respectively included in the unit pixels (PX).

[0167] The first demodulation control signal (V cs1 ) can have a phase difference of 180° (π) relative to the second demodulation control signal (V cs2 ). For example, the first demodulation control signal (V cs1 ) can have the same phase as the modulated light (ML), and the second demodulation control signal (V cs2 ) can have a phase difference of 180° (π) relative to the modulated light (ML).

[0168] The first demodulation control signal (V cs1 ) can be a signal for periodically applying a first voltage (V 1 ) and a second voltage (V 2 ) to the control region (e.g., Figure 3 's 313) included in each unit pixel (PX).

[0169] Similarly, the second demodulation control signal (V cs2 ) can be a signal for periodically applying a first voltage (V 1 ) and a second voltage (V 2 ) to the control region (e.g., Figure 3 's 313) included in each unit pixel (PX).

[0170] Each unit pixel can detect electrons corresponding to incident light received at a time point when the demodulation control signal V cs1 or V cs2 has the first voltage (V 1 ).

[0171] For example, when each of the first demodulation control signal V cs1 and the second demodulation control signal V cs2 has the first voltage (V 1 ), the optical charges generated by each photoelectric conversion region (e.g., Figure 3 's 311) respectively included in the unit pixels (PX) can be captured by the detection region 312.

[0172] After the captured electrons have moved through the transfer transistor TX, the electrons can be accumulated in the floating diffusion region (FD). The electrons accumulated in the floating diffusion region (FD) can be output as a pixel signal after passing through the drive transistor DX and the select transistor SX.

[0173] After the pixel signal has been output, the unit pixel (PX) can be reset to a predetermined voltage (e.g., the pixel voltage V px ) by the reset transistor RX.

[0174] While detecting the pixel signal of the unit pixel (PX), a bias voltage can be applied to the bias field region (e.g., Figure 2 32). As described above, due to the application of the bias voltage to the bias field region, the detection region 312 can easily detect electrons.

[0175] The modulated light (ML) can refer to the light emitted from the light source 10 controlled by the control block 40 to the target object 1. The modulated light (ML) can be generated to alternately have a high level section (i.e., the period of emitting light) and a low level section (i.e., the period of not emitting light).

[0176] The incident light (IL) can refer to the light incident on the substrate to generate electron-hole pairs through the photoelectric conversion effect. The incident light (IL) can have a phase difference (θ) that changes with the distance between the image sensor device ISD and the target object 1.

[0177] Figure 8 The level of each of the shown modulated light (ML) and incident light (IL) can refer to the intensity of the light. For example, "H" can refer to high-intensity light, and "L" can refer to low-intensity light.

[0178] While capturing the electrons generated by the incident light (IL) in the detection region 312 included in each unit pixel (PX), each of the first demodulation control signal (V cs1 ) and the second demodulation control signal (V cs2 ) can alternately apply a first voltage (V 1 ) and a second voltage (V 2 ) to the connected control region 313 at a predetermined time interval.

[0179] The logic level of the demodulation driver 42 for applying the first voltage (V 1 ) to the control region 313 in accordance with the demodulation control signal can be regarded as a logic high level (H). In addition, the logic level of the demodulation driver 42 for applying the second voltage (V 2 ) to the control region 313 in accordance with the demodulation control signal can be regarded as a logic low level (L). For example, the first voltage (V 1) can be 1.2V, and the second voltage (V 2 ) can be zero volts (0V).

[0180] Additionally, the first demodulation control signal (V cs1 ) can have the same phase as the modulated light (ML), and the second demodulation control signal (V cs2 ) can have a phase difference of 180° (π) relative to the modulated light (ML).

[0181] In some implementations, for ease of description, it is assumed that there is no phase difference between the optical modulation signal that generates the modulated light (ML) and the modulated light (ML), such that the optical modulation signal and the modulated light (ML) can have the same phase.

[0182] Incident light (IL) having a phase difference (θ) relative to the modulated light (ML) can be incident on the substrate. A unit pixel can capture the optical charge generated by the incident light (IL) during the periods when the demodulation control signals (V cs1 and V cs2 ) applied to the unit pixel (PX) have a logic high level (H).

[0183] The image sensing device ISD can perform a sensing operation and distance information detection in units of two adjacent unit pixels (PX).

[0184] Each unit pixel (PX) arranged in the sensing region 31 can receive a demodulation control signal corresponding to either the first demodulation control signal and the second demodulation control signal (V cs1 and V cs2 ). Each unit pixel (PX) can output a pixel signal corresponding to the electrons applied to the floating diffusion region (FD). An image processor (not shown) can obtain the distance from the image sensing device ISD to the target object 1 by processing the output pixel signal.

[0185] The image sensing device ISD can use the pixel signals detected by the unit pixels (PX) to calculate the phase difference (θ). In some implementations, one pixel signal detected by one unit pixel that receives the first demodulation control signal (V cs1 ) will be referred to as Q(0) hereinafter, and another pixel signal detected by another unit pixel that receives the second demodulation control signal (V cs2 ) will be referred to as Q(π) hereinafter.

[0186] The electrons generated by the incident light (IL) applied to the pixel array 30 can be separately captured by two adjacent unit pixels (PX) in different ways according to their respective phases.

[0187] An image processor (not shown) may receive image data corresponding to a pixel signal Q(0) and image data corresponding to a pixel signal Q(π) from adjacent unit pixels (PX), and may calculate a phase difference based on the received image data.

[0188] Figure 9 is a timing diagram exemplifying the phase difference between some implementations of the demodulation control signals (V cs1′ 、V cs2′ 、V cs3′ 、V cs4′ ) based on the disclosed technology.

[0189] Refer to Figure 9 , Figure 9 which exemplifies modulated light (ML), incident light (IL), and the first to fourth demodulation control signals (V cs1′ to V cs4′ ).

[0190] Associated with a plurality of unit pixels (PX) included in the sensing region 31, different demodulation control signals may be applied to adjacent unit pixels (PX). For example, the first to fourth demodulation control signals (V Figure 3 ) may be applied to control regions (e.g., cs1′ to V cs4′ ) included in four adjacent unit pixels (PX) arranged in a (2×2) matrix array, respectively.

[0191] The first demodulation control signal (V cs1′ ) may have a phase difference of 180° (π) with respect to the second demodulation control signal (V cs2′ ). The third demodulation control signal (V cs3′ ) may have a phase difference of 90° with respect to the first demodulation control signal (V cs1′ ). The fourth demodulation control signal (V cs4′ ) may have a phase difference of 270° with respect to the first demodulation control signal (V cs1′ ).

[0192] Each of the first to fourth demodulation control signals (V cs1′ to V cs4′ ) may be a signal for periodically applying each of a first voltage (V Figure 3 ) and a second voltage (V 1 ) to a control region (e.g., 2 ) included in each unit pixel (PX).

[0193] Each unit pixel (PX) may detect the phase difference between the demodulation control signal (V cs1′to V cs4′ ) each have electrons corresponding to the incident light received at the time of the first voltage (V 1 ).

[0194] For example, when each of the first demodulation control signal to the fourth demodulation control signal (V cs1′ to V cs4′ ) has the first voltage (V 1 ), the detection region 312 can capture the optical charges generated respectively in each photoelectric conversion region (for example, Figure 3 311) included in the unit pixel (PX).

[0195] While detecting the pixel signal of the unit pixel (PX), a bias voltage can be applied to the bias field region (for example, Figure 2 32). As described above, since the bias voltage is applied to the bias field region, the detection region 312 can easily detect electrons.

[0196] The modulated light (ML) can refer to the light emitted from the light source 10 controlled by the control block 40 to the target object 1. The modulated light (ML) can be generated to alternately have a high level section (i.e., the period of emitting light) and a low level section (i.e., the period of not emitting light).

[0197] The incident light (IL) can refer to the light incident on the substrate to generate electron-hole pairs through the photoelectric conversion effect. The incident light (IL) can have a phase difference (θ) that varies with the distance between the image sensor device ISD and the target object 1.

[0198] Figure 9 The level of each of the modulated light (ML) and the incident light (IL) shown can refer to the intensity of the light. For example, "H" can refer to high-intensity light, and "L" can refer to low-intensity light.

[0199] While capturing the electrons generated by the incident light (IL) in the detection region 312 included in each unit pixel (PX), each of the first demodulation control signal (V cs1′ ) and the second demodulation control signal (V cs2′ ) can alternately apply the first voltage (V 1 ) and the second voltage (V 2 ) to the connected control region 313 at a predetermined time interval.

[0200] The logic level of the demodulation driver 42 for applying the first voltage (V 1 ) to the control region 313 according to the demodulation control signal can be regarded as a logic high level (H). In addition, the logic level of the demodulation driver 42 for applying the second voltage (V2 )'s logic level can be considered as a logic low level (L). For example, the first voltage (V 1 ) can be 1.2V, while the second voltage (V 2 ) can be zero volts (0V).

[0201] In addition, the first demodulation control signal (V cs1′ ) can have the same phase as the modulated light (ML), the second demodulation control signal (V cs2′ ) can have a 180° (π) phase difference relative to the modulated light (ML), the third demodulation control signal (V cs3′ ) can have a 90° (π / 2) phase difference relative to the modulated light (ML), and the fourth demodulation control signal (V cs4′ ) can have a 270° (3π / 2) phase difference relative to the modulated light (ML).

[0202] In some implementations, for ease of description, it is assumed that there is no phase difference between the optical modulation signal that generates the modulated light (ML) and the modulated light (ML), such that the optical modulation signal and the modulated light (ML) can have the same phase.

[0203] The incident light (IL) having a phase difference (θ) relative to the modulated light (ML) can be incident on the substrate. The unit pixel can capture the optical charge generated by the incident light (IL) during the time period when the demodulation control signals (V cs1′ to V cs4′ ) applied to the unit pixel (PX) respectively have a logic high level (H).

[0204] The image sensing device ISD can perform a sensing operation and distance information detection in units of four adjacent unit pixels (PX).

[0205] Each unit pixel (PX) arranged in the sensing area 31 can receive a demodulation control signal corresponding to any one of the first to fourth demodulation control signals (V cs1′ to V cs4′ ). Each unit pixel (PX) can output a pixel signal corresponding to the electrons applied to the floating diffusion region (FD). An image processor (not shown) can obtain the distance from the image sensing device ISD to the target object 1 by processing the output pixel signal.

[0206] The image sensing device ISD can calculate the phase difference (θ) using the pixel signals detected by the respective unit pixels (PX). In some implementations, the pixel signal detected by the unit pixel that receives the first demodulation control signal (V cs1′ ) will be referred to as Q(0) hereinafter, and the pixel signal detected by the unit pixel that receives the second demodulation control signal (V cs2′The pixel signal detected by the unit pixel of ( ) will hereinafter be referred to as Q(π). In addition, the pixel signal detected by the unit pixel receiving the third demodulation control signal (V cs3′ ) will hereinafter be referred to as Q(π / 2), and the pixel signal detected by the unit pixel receiving the fourth demodulation control signal (V cs4′ ) will hereinafter be referred to as Q(3π / 2).

[0207] The electrons generated by the incident light (IL) applied to the pixel array 30 can be separately captured in different ways by four adjacent unit pixels (PX) according to their respective phases.

[0208] An image processor (not shown) can receive the image data corresponding to the pixel signal Q(0), the image data corresponding to the pixel signal Q(π), the image data corresponding to the pixel signal Q(π / 2), and the image data corresponding to the pixel signal Q(3π / 2) from the adjacent unit pixels (PX), and can calculate the phase difference based on the received image data.

[0209] Figure 10 is a graph exemplifying an example of the potential gradient generated in response to a bias voltage in some implementations based on the disclosed technology.

[0210] Specifically, Figure 10 exemplifies an example of the electrostatic potential of the bias field region, the photoelectric conversion region, and the detection region.

[0211] Referring to Figure 10 , the bias voltage (bias potential) can be a negative (-) voltage. As the bias voltage is applied to the bias field region, the electrostatic potential of the bias field region can be a negative (-) voltage.

[0212] When a bias voltage is provided to the bias field region (see "Bias Potential Curve"), compared with other cases where no bias voltage is provided to the bias field region (see "No Bias Potential Curve"), the potential gradient between the bias field region and the photoelectric conversion region can be greatly increased.

[0213] Therefore, when a bias voltage is provided to the bias field region (see "Bias Potential Curve"), compared with other cases where no bias voltage is provided to the bias field region (see "No Bias Potential Curve"), the photo charges can move more easily from the bias field region to each of the photoelectric conversion region and the detection region. In addition, when a bias voltage is provided to the bias field region (see "Bias Potential Curve"), compared with other cases where no bias voltage is provided to the bias field region (see "No Bias Potential Curve"), the photo charges can move more easily from the photoelectric conversion region to the detection region.

[0214] As is apparent from the above description, an image sensing device based on some implementations of the disclosed technology can have a bias field region disposed along an edge of a sensing region and can adjust an electric field of a substrate by a bias voltage provided in the bias field region.

[0215] An image sensing device based on some implementations of the disclosed technology can mitigate a recombination phenomenon of electrons generated in response to incident light by adjusting a depth of the bias field region and can prevent occurrence of dark current caused by formation of a contact region.

[0216] Embodiments of the disclosed technology can provide various effects that can be directly or indirectly recognized through the above patent documents.

[0217] Those skilled in the art will understand that the disclosed technology can be implemented in other specific manners than those set forth herein. Additionally, claims not explicitly set forth in the appended claims can be included as combinations of embodiments or as new claims through subsequent amendments after the filing of the application.

[0218] Although numerous exemplary embodiments have been described, it should be understood that various modifications and / or enhancements of the disclosed embodiments and other embodiments can be designed based on what is described and / or illustrated in this patent document.

[0219] Cross - reference to related applications

[0220] This patent document claims the priority and benefit of Korean Patent Application No. 10 - 2021 - 0106902, filed on August 12, 2021, the disclosure of which is incorporated herein by reference in its entirety as part of the disclosure of this patent document.

Claims

1. An image sensing device, the image sensing device comprises: a pixel array; wherein, the pixel array comprises: a sensing region, the sensing region including a plurality of unit pixels, each unit pixel detecting incident light to generate photo - charges indicative of the detected incident light; a bias field region, the bias field region being doped with impurities and disposed along an edge of the sensing region; and a contact portion, the contact portion being connected to the bias field region to apply a bias voltage to the bias field region to move the photo - charges in the sensing region, wherein, the pixel array further comprises: a passivation region, the passivation region being formed to overlap with the sensing region, wherein, the pixel array is formed in a semiconductor layer, wherein the bias field region is located at a first depth within the semiconductor layer, and the passivation region is located at a second depth within the semiconductor layer, and wherein the first depth is greater than the second depth.

2. The image sensing device according to claim 1, wherein, the bias field region is formed to surround the passivation region; and the bias field region is formed to contact the contact portion.

3. The image sensing device according to claim 1, wherein, the bias field region is disposed along an edge of the passivation region; and the passivation region is formed to overlap with the bias field region.

4. The image sensing device according to claim 1, wherein, each of the unit pixels comprises: a control region, the control region generating a current in the semiconductor layer where the unit pixel is disposed; and a detection region, the detection region capturing the photo - charges moved by the current.

5. The image sensing device according to claim 4, wherein, a demodulation control signal is applied to the control region, wherein, the demodulation control signal is formed by repeating a first voltage and a second voltage at a predetermined time interval.

6. The image sensing device according to claim 5, wherein, the demodulation control signal is any one of two different demodulation control signals having a phase difference of 180 degrees between each other.

7. The image sensing device according to claim 5, wherein, the demodulation control signal is any one of four different demodulation control signals having a phase difference of 90 degrees between each other.

8. The image sensing device according to claim 5, wherein, the photo - charges move in a direction from the bias field region to the control region.

9. The image sensing device according to claim 5, wherein, the bias voltage is lower than each of the first voltage and the second voltage.

10. An image sensing device, the image sensing device comprises: a sensing region, the sensing region including a plurality of unit pixels, each unit pixel including a control region for receiving a first voltage or a second voltage and a detection region for capturing electrons moved by the first voltage or the second voltage; a bias field region, the bias field region being disposed along an edge of the sensing region; a contact portion, the contact portion being connected to the bias field region to apply a bias voltage to the bias field region; and A bias voltage controller that transmits the bias voltage to the contact portion, wherein the bias voltage is lower than each of the first voltage and the second voltage.

11. The image sensing device according to claim 10, the image sensing device further comprises: A passivation region formed to overlap with the sensing region, wherein the bias field region is located at a first depth within the semiconductor layer and the passivation region is located at a second depth within the semiconductor layer, and wherein the first depth is greater than the second depth.

12. The image sensing device according to claim 11, wherein, the bias field region is formed to surround the passivation region; and the bias field region is formed to contact the contact portion.

13. The image sensing device according to claim 11, wherein, the bias field region is disposed along the edge of the passivation region; and the passivation region is formed to overlap with the bias field region.

14. An image sensing device, the image sensing device comprises: A sensing region including a plurality of unit pixels formed in a substrate to generate photo charges and capture the generated photo charges; A bias field region doped with a first impurity and formed from the surface of the substrate to a first depth within the substrate along the edge of the sensing region; A passivation region doped with a first impurity and formed from the surface of the substrate to a second depth within the substrate above the sensing region; and A contact portion connected to the bias field region to apply a bias voltage to the bias field region to move the photo charges, wherein the first depth is greater than the second depth.

15. The image sensing device according to claim 14, wherein, the bias field region is formed to surround the passivation region; and the bias field region is formed to contact the contact portion.

16. The image sensing device according to claim 14, wherein, the bias field region is disposed along the edge of the passivation region; and the passivation region is formed to overlap with the bias field region.

17. The image sensing device according to claim 14, wherein, each of the unit pixels includes: A control region that generates a current in the semiconductor layer where the unit pixel is disposed; and A detection region that captures the photo charges moved by the current.

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