Pixel and image sensor including the same

A pixel included in an image sensor may include: a first control node and a second control node, each configured to receive control signals and generate a hole current in a substrate; and a first detection node and a second detection node, configured to capture electrons which are generated by incident light in the substrate and move by the hole current. Each of the first and second control nodes has a shape including a first surface and second surfaces connected to the first surface and the first surfaces of the first control node and the second control node are disposed to face each other, and an area of the first surface is larger than an area of any one of the second surfaces.

CROSS-REFERENCES TO RELATED APPLICATION

This patent document claims the priority and benefits of Korean application number 10-2020-0027142, filed on Mar. 4, 2020, which is incorporated herein by reference in its entirety.

TECHNICAL FIELD

The technology and implementations disclosed in this patent document generally relate to an image sensor for sensing a distance to a target object.

BACKGROUND

An image sensor is a device for capturing an image using the properties of semiconductor which reacts to light that is incident thereon to produce an image. Recently, with the development of computer industry and communication industry, the demand for an advanced image sensor has been increasing in various electronic devices such as smart phones, digital cameras, video game equipment, devices for use with IOT (Internet of Things), robots, security cameras and medical micro cameras.

The image sensor may be roughly divided into a CCD (Charge Coupled Device) image sensors and CMOS (Complementary Metal Oxide Semiconductor) image sensors. CCD image sensors generates less noise and have better image quality than CMOS image sensors. However, CMOS image sensors have a simpler and more a convenient driving scheme, and thus may be preferred in some applications. CMOS image sensors may integrate a signal processing circuit in a single chip, making it easy to miniaturize the sensors for implementation in a product, with the added benefit of consuming lower power consumption. CMOS image sensors can be fabricated using a CMOS process technology, which results in low manufacturing cost. CMOS image sensing devices have been widely used due to their suitability for implementation in mobile devices.

There have been much development and studies for measuring range and depth by using an image sensor. The demand for the technologies of measuring range and depth are rapidly increases in various fields including security devices, medical devices, vehicles, game consoles, VR/AR and/or mobile devices. The representative technologies include triangulation, ToF (Time of Flight) and interferometry. Among the methods, the ToF method becomes popular because of its wide range of utilization, high processing speed, and cost advantages. The TOF method measures a distance using emitted light and reflected light. The ToF method can be classified into two different types, i.e., a direct method and an indirect method, depending on whether it is a round-trip time or the phase difference that determines the distance. The direct method measures a distance by calculating a round trip time and the indirect method measures a distance using a phase difference. Since the direct method is suitable for measuring a long distance, the direct method is generally used in vehicles. The indirect method is suitable for measuring a short distance and thus is generally used for game devices or mobile cameras that are associated with shorter distances and require faster processing speed. As compared to the direct type ToF systems, the indirect method have several advantages, including having simpler circuitry, low memory requirement, and a relatively low cost.

A CAPD (Current-Assisted Photonic Demodulator) is one type of pixel circuitry used in an indirect ToF sensor. In CAPD, electrons are generated in a pixel circuit by majority current that is created through an application of a substrate voltage, and the generated electrons are detected by using a potential difference of an electric field. Since the majority current is used, the CAPD can rapidly detect electrons. Furthermore, the CAPD has an excellent efficiency by detecting the electrons which are disposed in deep locations.

SUMMARY

Various embodiments of the disclosed technology are related to an image sensor capable of effectively performing a high-speed distance sensing operation.

In an embodiment, a pixel included in an image sensor may include: a first control node and a second control node, each configured to receive control signals and generate a hole current in a substrate in response to the control signals; and a first detection node and a second detection node that are arranged to correspond to the first control node and the second control node, respectively, and configured to capture electrons which are generated by incident light in the substrate and move by the hole current, wherein each of the first and second control nodes has a shape including a first surface and second surfaces connected to the first surface and the first surfaces of the first control node and the second control node are disposed to face each other, and an area of the first surface is larger than an area of any one of the second surfaces.

In another aspect, an image sensor comprising pixels that detect incident light to produce pixel signals indicative of an image carried by the incident light, wherein the pixels include a first CAPD (Current-Assisted Photonic Demodulator) pixel and a second CAPD pixel, which are arranged adjacent to each other. A control node of the first CAPD pixel may include a first surface facing another control node of the first CAPD pixel and a second surface facing a control node of the second CAPD pixel, and the first surface may have a larger area than an area of the second surface.

In accordance with the present embodiments, the image sensor can improve the transmission efficiency of a hole current flowing through a unit pixel while minimizing crosstalk with an adjacent pixel and power consumption of the entire pixel array. Therefore, although the size of a CAPD pixel is reduced, the image sensor can be designed to have the optimal performance.

DETAILED DESCRIPTION

Hereafter, various embodiments will be described with reference to the accompanying drawings. However, it should be understood that the present disclosure is not limited to specific embodiments, but includes various modifications, equivalents and/or alternatives of the embodiments.

FIG. 1is a configuration diagram schematically illustrating a configuration of an image sensor in accordance with embodiments.

Referring toFIG. 1, the image sensor may measure a distance to a target object1using a ToF (Time of Flight) method. Such an image sensor may include a light source10, a lens module20, a pixel array30and a control block40.

The light source10emits light onto the target object1in response to a clock signal MLS (modulated light signal) from the control block40. The light source10may be an LD (laser Diode) or LED (Light Emitting Diode) which emits a specific wavelength of light (for example, near-infrared light, infrared light or visible light), NIR (Near Infrared Laser), a point light source, a white lamp, a monochromatic light source having monochromators combined therein, or a combination of other laser light sources. For example, the light source10may emit infrared light having a wavelength of 800 nm to 1,000 nm. The light emitted from the light source10may be light which is modulated at a predetermined frequency.FIG. 1illustrates only one light source10, for convenience of description. However, a plurality of light sources may be arranged around the lens module20.

The lens module20may collect light reflected from the target object1and focus the collected light on pixels PX of the pixel array30. For example, the lens module20may include a focusing lens with a glass or plastic surface or a cylindrical optical element. The lens module20may include a plurality of lenses aligned with an optical axis.

The pixel array30may include a plurality of unit pixels PX which are successively arranged in a 2D matrix structure, for example, a plurality of unit pixels PX which are successively arranged in column and row directions. The unit pixels PX may be formed on a semiconductor substrate, and each of the unit pixels PX may convert light, incident through the lens module20, into an electrical signal corresponding to the intensity of the light, and output the electrical signal as a pixel signal. At this time, the pixel signal may be a signal which does not indicate the color of the target object1, but indicates the distance to the target object1. Each of the unit pixels PX may be a CAPD (Current-Assisted Photonic Demodulator) pixel. The detailed structure and operation of the unit pixel PX will be described below with reference toFIG. 2Aand the followings.

The control block40may control the light source10to emit light onto the target object1, and drive the unit pixels PX of the pixel array30to process pixel signals corresponding to light reflected from the target object1, thereby measuring the distance to the surface of the target object1.

The control block40may include a control circuit41, a light source driver42, a timing controller43and a logic circuit44.

The control circuit41may drive the unit pixels PX of the pixel array30in response to a timing signal outputted from the timing controller43. For example, the control circuit41may generate a control signal capable of selecting and controlling one or more row lines among a plurality of row lines. Such a control signal may include a demodulation control signal for generating a hole current within a substrate, a reset signal for controlling a reset transistor, a transmission signal for controlling transfer of photoelectric charges accumulated in a detection node, and a selection signal for controlling a selection transistor.FIG. 1illustrates that the control circuit41is disposed in the column direction (or vertical direction) of the pixel array30. According to an embodiment, however, at least a part of the control circuit41(for example, a circuit for generating the demodulation control signal) may be disposed to be elongated in the row direction (or horizontal direction) of the pixel array30.

The light source driver42may generate the clock signal MLS capable of driving the light source10, under control of the timing controller43. The clock signal MLS may be a signal which is modulated at a predetermined frequency.

The timing controller43may generate a timing signal for controlling the operations of the control circuit41, the light source driver42and the logic circuit44.

The logic circuit44may generate pixel data in the form of digital signals by processing pixel signals outputted from the pixel array30, under control of the timing controller43. For this operation, the logic circuit44may include a CDS (Correlated Double Sampler) for performing correlated double sampling on the pixel signals outputted from the pixel array30. The logic circuit44may include an analog-digital converter for converting the output signals from the CDS into digital signals. Furthermore, the logic circuit44may include a buffer circuit which temporarily stores pixel data outputted from the analog-digital converter and outputs the pixel data to the outside under control of the timing controller43. As the pixel array30is composed of CAPD pixels, two column lines per one column of the pixel array30may be provided to transfer pixel signals, and components for processing pixel signals outputted from the column lines may also be provided for the respective column lines.

The light source10may emit modulated light, modulated at a predetermined frequency, toward a scene to be captured by the image sensor, and the image sensor may sense the modulated light (i.e. incident light) reflected from target objects1within the scene, and generate depth information for each of the unit pixels PX. Between the modulated light and the incident light, time delay is present due to the distance between the image sensor and the target object1. Such time delay appears as a phase difference between a signal generated by the image sensor and the clock signal MLS for controlling the light source10. The image processor (not illustrated) may generate a depth image containing depth information for each of the unit pixels PX by calculating a phase difference which occurs in a signal outputted from the image sensor.

FIG. 2Ais a plan view illustrating an embodiment of a pixel included in a pixel array illustrated inFIG. 1.FIG. 2Bis a plan view illustrating another embodiment of a detection node included in the pixel illustrated inFIG. 2A.FIG. 3Ais a cross-sectional view of the pixel illustrated inFIG. 2A.FIG. 3Bis a cross-sectional view of the pixel illustrated inFIG. 2B.

FIG. 2Aillustrates a plan view200including first to fourth pixels P1to P4which are arranged in a 2×2 matrix so as to be adjacent to one another, and the pixel array30may include the first to fourth pixels P1to P4that are arranged in a matrix shape. Each of the first to fourth pixels P1to P4has a substantially similar structure.

The first pixel P1may include first and second control nodes210and220and first and second detection nodes215and225. The first control node210and the first detection node215may constitute a first demodulation node (or first tap), and the second control node220and the second detection node225may constitute a second demodulation node (or second tap).FIG. 2Aillustrates that the first demodulation node including the first control node210and the first detection node215and the second demodulation node including the second control node220and the second detection node225are arranged within the first pixel P1in a line that is parallel to the column direction of the pixel array30. However, the disclosed technology is not limited thereto and other implementations are also possible. For example, the first demodulation node including the first control node210and the first detection node215and the second demodulation node including the second control node220and the second detection node225may be arranged in a line that is parallel to the row direction of the pixel array30.

The first detection node215may be disposed to surround the first control node210, and the second detection node225may be disposed to surround the second control node220. By being arranged to surround the first and second control nodes210and220, the first and second detection nodes215and225can more easily capture signal carriers which migrate along hole currents formed by the first and second control nodes210and220. In some implementations, the first and second detection nodes215and225may surround only parts of the first and second control nodes210and220, respectively instead of completely surrounding the first and second control nodes210and220, respectively. In this case, at least parts of the first and second control nodes210and220are configured as open instead of being provided in a closed shape.

The second pixel P2may include first and second control nodes230and240and first and second detection nodes235and245. The third pixel P3may include first and second control nodes250and260and first and second detection nodes255and265. The fourth pixel P4may include first and second control nodes270and280and first and second detection nodes275and285.

The first control nodes230,250and270and the first detection nodes235,255and275, included in the second to fourth pixels P2to P4, may constitute first demodulation nodes (or first taps) of the second to fourth pixels P2to P4, respectively, and the second control nodes240,260and280and the second detection nodes245,265and285, included in the second to fourth pixels P2to P4, may constitute second demodulation nodes (or second taps) of the second to fourth pixels P2to P4, respectively. Since the second to fourth pixels P2to P4may have a structure corresponding to the first pixel P1, the same descriptions thereof will be omitted herein.

Each of the first to fourth pixels P1to P4may further include a wiring line, a floating diffusion and one or more transistors for applying a driving signal to the corresponding pixel, generating and reading pixel signals from the corresponding pixel. InFIG. 2A, however, the wiring line, the floating diffusion and the one or more transistors are omitted, for convenience of description.

First, the first pixel P1will be described. In the first pixel P1, the first detection node215may be disposed on the left and right sides of the first control node210. Furthermore, the second detection node225may be disposed on the left and right sides of the second control node220.

The first and second control nodes210and220and the first and second detection nodes215and225may be formed in a substrate295. The substrate295may be a P-type semiconductor substrate. As illustrated inFIG. 3A, the first and second control nodes210and220may be P-type impurity regions, and the first and second detection nodes215and225may be N-type impurity regions. In some implementations, each of the first and second control nodes210and220and the first and second detection nodes215and225may include a plurality of impurity layers having different doping concentrations. For example, each of the first and second control nodes210and220may have a structure in which a P+ region with a relatively high impurity concentration and a P− region with a relatively low impurity concentration are sequentially stacked from the top surface of the substrate295. For example, each of the first and second detection nodes215and225may have a structure in which an N+ region with a relatively high impurity concentration and an N− region with a relatively low impurity concentration are sequentially stacked from the top surface of the substrate295.

The depth of each of the first and second control nodes210and220from the top surface of the substrate295may be larger than the depth of each of the first and second detection nodes215and225from the top surface of the substrate295. Through such a structure, a hole current HC between the first and second control nodes210and220may more easily flow without being disturbed by the first and second detection nodes215and225.

The first demodulation nodes and the second demodulation nodes, which are included in the first pixel P1and the second pixel P2, respectively, may be physically isolated by an insulating layer290. Furthermore, the first control node210and the first detection node215may also be physically isolated by the insulating layer290, and the second control node220and the second detection node225may also be physically isolated by the insulating layer290. The insulating layer290may be an oxide layer, but the disclosed technology is not limited thereto. In some implementations, the insulating layer290may be formed through a process of forming a trench in the substrate295using an STI (Shallow Trench Isolation) process and gap-filling the trench with an insulating material.

FIG. 2Billustrates a plan view200′ including first to fourth pixels P1to P4including detection nodes215′,225′,235′,245′,255′,265′,275′ and285′ having different shapes from the detection nodes215,225,235,245,255,265,275and285illustrated inFIG. 2A, andFIG. 3Billustrates a cross-sectional view300′ of some of the detection nodes215′,225′,235′,245′,255′,265′,275′ and285′. unlike the implementation as shown inFIGS. 2A and 3A, there is no separate insulating layer disposed between the first control node210and the first detection node215′ and between the second control node220and the second detection node225′. The first detection node215′ and the second detection node225′ may be formed to surround the first control node210and the second control node220, respectively, while abutting on the first control node210and the second control node220, respectively. In this case, the first control node210and the first detection node215′ may be physically isolated only by junction isolation, and the second control node220and the second detection node225′ may also be physically isolated only by junction isolation. Therefore, while the areas of the first and second detection nodes215′ and225′ are increased, the first and second detection nodes215′ and225′ may be disposed close to the first and second control nodes210and220, respectively, which makes it possible to secure the detection performance of the first and second detection nodes215′ and225′.

Referring toFIG. 3A, the image sensor may be an FSI (Front-Side Illumination)-type image sensor which receives incident light through a front surface of the substrate295(top surface inFIG. 3A). In some implementations, the image sensor may be a BSI (Back-Side Illumination)-type image sensor which receives incident light through a back surface of the substrate295(bottom surface inFIG. 3A).

The first and second control nodes210and220may receive first and second demodulation control signals, respectively, from the control circuit41. A potential difference between the first and second demodulation control signals generates an electric field (or hole current) to control a flow of signal carrier which is generated in the substrate295in response to incident light.

The first and second detection nodes215and225may perform a function of capturing a signal carrier, and be coupled to first and second floating diffusions having specific capacitance, respectively. Each of the first and second floating diffusions may be coupled to a reset transistor for resetting the corresponding floating diffusion and a source follower for generating an electrical signal according to the potential of the corresponding floating diffusion. The source follower may be coupled to a selection transistor for outputting the electrical signal, outputted from the source follower, to a column line. Thus, signals corresponding to the signal carriers captured by the first and second detection nodes215and225may be outputted to independent column lines, respectively. The reset control signal for controlling the reset transistor and the selection control signal for controlling the selection transistor may be provided from the control circuit41.

Hereafter, the operation of the first pixel P1will be described in more detail. The operations occur during a first section in which the first demodulation control signal applied to the first control node210has a higher voltage than the second demodulation control signal applied to the second control node220and second section in which the first demodulation control signal applied to the first control node210has a lower voltage than the second demodulation control signal applied to the second control node220.

In the first section, the substrate295may receive incident light and photoelectrically convert the incident light. The incident light may be photoelectrically converted to generate electron hole pairs in the substrate295according to the intensity of the incident light. At this time, the control circuit41may apply a first demodulation control signal to the first control node210, and apply a second demodulation control signal to the second control node220. Here, the first demodulation control signal may have a higher voltage than the second demodulation control signal. For example, the voltage of the first demodulation control signal may be 1.2V, and the voltage of the second demodulation control signal may be 0V.

Due to a voltage difference between the first and second demodulation control signals, an electric field may be generated between the first and second control nodes210and220, and a hole current HC may flow from the first control node210to the second control node220. Holes within the substrate295may migrate toward the second control node220, and electrons within the substrate295may migrate toward the first control node210.

Thus, electrons may be generated in the substrate295in response to the intensity of incident light, and migrate toward the first control node210so as to be captured by the first detection node215adjacent to the first control node210. Therefore, the electrons within the substrate295may be used as signal carriers for detecting the intensity of incident light.

The electrons captured by the first detection node215may be accumulated in the first floating diffusion and change the potential of the first floating diffusion, and the source follower and the selection transistor may output an electrical signal corresponding to the potential of the first floating diffusion to a column line. Such an electrical signal may be an image signal, and generated as image data through CDS and analog-digital conversion with a reference signal which is an electrical signal corresponding to the potential of the first floating diffusion after the first floating diffusion is reset by the reset transistor.

In the second section after the first section, the substrate295may receive incident light and photoelectrically convert the incident light. The incident light may be photoelectrically converted to generate electron hole pairs in the substrate295according to the intensity of the incident light. At this time, the control circuit41may apply the first demodulation control signal to the first control node210, and apply the second demodulation control signal to the second control node220. Here, the first demodulation control signal may have a lower voltage than the second demodulation control signal. For example, the voltage of the first demodulation control signal may be 0V, and the voltage of the second demodulation control signal may be 1.2V.

Due to a voltage difference between the first and second demodulation control signals, an electric field may be generated between the first and second control nodes210and220, and a current may flow from the second control node220to the first control node210. Thus, holes within the substrate295may migrate toward the first control node210, and electrons within the substrate295may migrate toward the second control node220.

Thus, electrons may be generated in the substrate295in response to the intensity of incident light, and migrate toward the second control node220so as to be captured by the second detection node225adjacent to the second control node220. Therefore, the electrons within the substrate295may be used as signal carriers for detecting the intensity of the incident light.

The electrons captured by the second detection node225may be accumulated in the second floating diffusion and change the potential of the second floating diffusion, and the source follower and the selection transistor may output an electrical signal corresponding to the potential of the second floating diffusion to a column line. Such an electrical signal may be an image signal, and generated as image data through CDS and analog-digital conversion with a reference signal which is an electrical signal corresponding to the potential of the second floating diffusion after the second floating diffusion is reset by the reset transistor.

An image processor (not illustrated) may calculate a phase difference by performing an operation on the image data acquired in the first section and the image data acquired in the second section, calculate depth information, obtain a depth information indicating the distance to the target object1based on a phase difference of a corresponding pixel, and generate a depth image including the depth information of the corresponding pixel.

Since the structure and operation of the second pixel P2are substantially the same as those of the first pixel P1, the detailed descriptions thereof are omitted herein.

The first and second pixels P1and P2are disposed adjacent to each other. As the same first demodulation control signal is applied to the first control node210of the first pixel P1and the first control node230of the second pixel P2, an electric field can be formed between control nodes that are included in different pixels. For example, the electric field may be formed not only between the first control node210and the second control node220to which the second demodulation control signal is applied, but also between the first control node230and the second control node220. Thus, a hole current is likely to be generated between the first control node230and the second control node220. However, the hole current between the first control node230and the second control node220may induce electrons, generated around the boundary between the first and second pixels P1and P2, to the first detection node235, thereby causing noise (or crosstalk). Furthermore, an undesired hole current may be generated to increase power consumption of the image sensor.

Referring back toFIG. 2A, the first control node210of the first pixel P1may have a polygonal shape in which the horizontal length of a first surface211facing the second control node220of the first pixel P1is larger than the horizontal length of any one of a plurality of second surfaces212which do not face the second control node220of the first pixel P1. The first surface211of the first control node210is closer to the second control node220as compared to second surfaces212of the first control node210.FIG. 2Aillustrates that the first control node210has a trapezoidal shape, but the disclosed technology is not limited thereto and other implementations are also possible. For example, the first control node210may have a triangle shape. In the present embodiment, the horizontal length may indicate the length of a specific surface on the plan view.

The second control node220of the first pixel P1may have a polygonal shape in which the horizontal length of a first surface221facing the first control node210of the first pixel P1is larger than the horizontal length of any one of a plurality of second surfaces222which do not face the first control node210of the first pixel P1.FIG. 2Aillustrates that the second control node220has a trapezoidal shape, but the disclosed technology is not limited thereto. For example, the second control node220may have a triangle shape.

In the first pixel P1, the first control node210and the second control node220are disposed to face each other. The first surface211of the first control node210may be disposed closer to the second control node220as compared to second surfaces212of the first control node210. The first surface221of the second control node220may be disposed to face the first control node210as compared to second surfaces222of the second control node220. The second surfaces212and222of the first control node210and the second control node220may be directly/indirectly connected to the corresponding first surfaces211and221.

The first control nodes230,250and270and the second control nodes240,260and280of the second to fourth pixels P2to P4may have shapes and disposition directions corresponding to those of the first control node210and the second control node220of the first pixel P1.

The hole current flowing between two control nodes to which different voltages are applied increases, as (1) the potential difference between the control nodes is increased, (2) the distance between the control nodes is decreased, and/or (3) the areas of surfaces of the control nodes that face each other are increased. Thus, at least one of the conditions (1) to (3) are satisfied, the hole current flowing between the two control nodes increases. On the other hand, the hole current flowing between the control nodes to which different voltages are applied decreases, as (1) the potential difference between the control nodes is decreased, (2) the distance between the control nodes is increased, and/or (3) the areas of surfaces of the control nodes that face each other are decreased. Thus, at least one of the conditions (1) to (3) are satisfied, the hole current flowing between the two control nodes decreases. The hole current may be decided by the potential difference between the control nodes and the resistance between the control nodes. The resistance between the control nodes increases, as (1) the distance between the control nodes is increased and/or (2) the areas of the surfaces of the control nodes that facing each other are decreased. In the present embodiment, it is assumed that a potential difference between the control nodes to which different voltages are applied is constant.

Therefore, among the magnitudes of hole currents between the second control node220and one of the control nodes210,230,250and270around the second control node220, the hole current flowing between the second control node220and the first control node210has the largest magnitude since the first control node210is the closest to the second control node220and its surface facing the second control node220has the largest area. The hole currents between the second control node220and one of the first control nodes230,250and270have relatively small magnitude since the first control nodes230,250and270is located relatively remote from the second control node220and their surfaces facing the second control node220, respectively, have relatively narrow or smaller areas.

Therefore, crosstalk between the pixels adjacent to each other can be reduced, and unnecessary power consumption can be reduced.

When the first control nodes210,230,250and270and the second control nodes220,240,260and280have a circular shape or square shape, the surface of the second control node220facing the first control node230may have horizontal length equal or similar to that of the surface of the second control node220facing the first control node210. In this case, as the hole currents flowing between the second control node220and the first control node230increase, the crosstalk between the adjacent pixels may be increased, and unnecessary power consumption may be increased.

FIG. 4Ais a plan view illustrating another embodiment of the pixel included in the pixel array illustrated inFIG. 1.

FIG. 4Aillustrates a plan view400including first to fourth pixels P1to P4which are arranged in a 2×2 matrix so as to be adjacent to one another, and the pixel array30may have a structure in which substantially the same pixels as the first to fourth pixels P1to P4are arranged in a matrix shape.

The first to fourth pixels P1to P4ofFIG. 4Aare configured and operated in substantially the same manner as the first to fourth pixels P1to P4ofFIG. 2A, except the shapes and positions of the first and second demodulation nodes. Therefore, the following descriptions will be focused on differences fromFIG. 2A.

First, the first pixel P1will be described. In the first pixel P1, a first demodulation node including a first control node410and a first detection node415and a second demodulation node including a second control node420and a second detection node425may be disposed in a diagonal direction of the first pixel P1.FIG. 4Aillustrates that the first demodulation node is disposed at the left top of the first pixel P1, and the second demodulation node is disposed at the right bottom of the first pixel P1. However, the present embodiment is not limited thereto and other implementations are also possible. For example, the first demodulation node including a first control node410and a first detection node415may be disposed at the left bottom of the first pixel P1, and the second demodulation node including a second control node420and a second detection node425may be disposed at the right top of the first pixel P1.

Similarly, first and second demodulation nodes included in each of the second to fourth pixels P2to P4may be disposed similarly to the disposition of the first pixel P1. For example, the first and second demodulation nodes may be disposed at the left top and the right bottom of the corresponding pixel.

First control nodes410,430,450and470and second control nodes420,440,460and480of the respective pixels P1to P4may have the same shapes as the corresponding first control nodes210,230,250and270and the corresponding second control nodes220,240,260and280inFIG. 2A, and be obliquely disposed so that first surfaces of the first and second control nodes belonging to the same pixel face each other. For example, the first surfaces411and421are formed at a predetermined angle with respect to one side (e.g., top or bottom side) of the unit pixel P1. Such arrangement of the first and second control nodes410and420are different from the structure in which the first surfaces211and221of the first and second control nodes210and220are disposed parallel to one side of the unit pixel P1as illustrated inFIG. 2A. As shown inFIG. 4A, second surfaces412and422may be arranged at a predetermined angle with respect to the first surfaces411and421.

According to the diagonal disposition structure illustrated inFIG. 4A, the respective distances between each of the first control nodes410,430,450and470and each of the second control nodes420,440,460and480may be increased, thereby increasing resistance. Therefore, the respective hole currents flowing between each of the first control nodes410,430,450and470and each of the second control nodes420,440,460and480may be decreased to reduce power consumption required for driving the pixel array30.

Thus, the diagonal disposition structure illustrated inFIG. 4Amay not only have the advantages (reduction in power consumption and crosstalk between pixels) of the structure described with reference toFIGS. 2A and 2B, but also reduce the respective hole currents flowing between each of the first control nodes410,430,450and470and each of the second control nodes420,440,460and480, thereby further reducing power consumption.

FIG. 4Bis a plan view illustrating another embodiment of the detection node included in the pixel illustrated inFIG. 4A.

FIG. 4Billustrates a plan view400′ including first to fourth pixels P1to P4having detection nodes415′,425′,435′,445′,455′,465′,475′ and485′ which have different shapes from the detection nodes415,425,435,445,455,465,475and485illustrated inFIG. 4A. That is, no separate insulating layer may be disposed between the first control node410and the first detection node415′ and between the second control node420and the second detection node425′, and the first detection node415′ and the second detection node425′ may be formed to surround the first control node410and the second control node420while abutting on the first control node410and the second control node420, respectively. In this case, the first control node410and the first detection node415′ may be physically isolated only by junction isolation, and the second control node420and the second detection node425′ may also be physically isolated only by junction isolation.

Since the first to fourth pixels P1to P4ofFIG. 4Bare configured and operated in substantially the same manner as the first to fourth pixels P1to P4ofFIG. 4Aexcept the shapes of the first and second detection nodes, the same descriptions will be omitted herein.

FIG. 5Ais a plan view illustrating another embodiment of the control node included in the pixel illustrated inFIG. 2A.

FIG. 5Aillustrates another embodiment500of the first and second control nodes included in the first pixel P1ofFIG. 2A. Since a first pixel P1ofFIG. 5Ais configured and operated in substantially the same manner as the first pixel P1ofFIG. 2Aexcept the shape of first and second control nodes510and520, the following descriptions will be focused on differences fromFIG. 2A, in order to avoid repeating same descriptions. Furthermore, only the first pixel P1is described for convenience of description, but it is obvious that substantially the same structure may be applied to the other pixels.

The first and second control nodes510and520may include protrusions511and521, respectively, which protrude toward each other.

Due to the protrusions511and521, the centers of the first and second control nodes510and520may become close to each other. Thus, the distance between the first and second control nodes510and520may be decreased to reduce the resistance between the first and second control nodes510and520.

A control node may have only one first surface facing the other control node or multiple first surfaces facing the other control node. InFIG. 2A, the first surface may indicate a surface disposed in the region where the first and second control nodes included in the same pixel face each other. When any control node has a plurality of surfaces that face the other control node, there exist connecting surfaces that connect the plurality of the surfaces in the region where the control nodes face each other. In the example ofFIG. 5A, each of the first surfaces512and522of the first and second control nodes510and520may include three surfaces facing the other control node and connecting surfaces connecting the three surfaces facing the other control node (for example, the left and right side surfaces of the protrusions511and521ofFIG. 5A). Furthermore, a plurality of second surfaces513and523of the first and second control nodes510and520may indicate surfaces which are directly/indirectly connected to the first surfaces512and522(for example, the uppermost surface of the first control node510inFIG. 5Aand surfaces directly connected thereto).

In the example as shown inFIG. 5A, when the protrusions511and521are present, each of the first control node510and the second control node520has multiple first surfaces512and522that include facing surfaces that face the other control node and connecting surfaces that connect the facing surfaces. Due to the protrusions511and521, each of the first control node510and the second control node520has the first surfaces, disposed in the region where the first and second control nodes510and520face each other, whose horizontal length is increased as compared to when the protrusions511and521are not present. Therefore, the resistance between the first and second control nodes510and520may be reduced. When the protrusions511and521are not present, each of the first and second control nodes510has a single horizontal length of the first surface disposed in the region where the first and second control nodes510and520face each other, which may correspond to the width of each of the first and second control nodes510and520. When the protrusions511and521are present, the horizontal length of the first surface disposed in the region where the first and second control nodes510and520face each other may be further increased as much as the lateral lengths (e.g., left and right lengths) of each of the protrusions511and521. In the present embodiment, each of the protrusions511and521and structures (for example, isolation control nodes) corresponding to the protrusions511and521may have the horizontal length that is extended due to the protrusions511and521. For example, the boundary of each of the protrusions511and521has lengths in the vertical direction and a width in the horizontal direction perpendicular to the vertical direction.

Therefore, as the resistance between the first and second control nodes510and520is reduced, the hole current flowing between the first and second control nodes510and520may be increased. As the hole current is concentrated between the first and second control nodes510and520, crosstalk between the adjacent pixels may be reduced.

When the protrusions511and521are formed to have an excessively large width, the resistance between the first and second control nodes510and520may be excessively reduced, so that the hole current flowing between the first and second control nodes510and520may be increased more than necessary. In this case, the power consumption of the pixel array30may be increased. Thus, the widths and extension lengths of the protrusions511and521may be experimentally optimized in consideration of the magnitude of the hole current flowing between the first and second control nodes510and520and the crosstalk between adjacent pixels.

FIG. 5Bis a plan view illustrating another embodiment of the detection node included in the pixel illustrated inFIG. 5A.

FIG. 5Billustrates a plan view500′ including a first pixel P1having detection nodes515′ and525′ which have a different shape from detection nodes515and525illustrated inFIG. 5A. That is, no separate insulating layer may be disposed between the first control node510and the first detection node515′ and between the second control node520and the second detection node525′, and the first detection node515′ and the second detection node525′ may be formed to surround the first control node510and the second control node520while abutting on the first control node510and the second control node520, respectively. In this case, the first control node510and the first detection node515′ may be physically isolated only by junction isolation, and the second control node520and the second detection node525′ may also be physically isolated only by junction isolation.

Since the first pixel P1ofFIG. 5Bis configured and operated in substantially the same manner as the first pixel P1ofFIG. 5Aexcept the shapes of the first and second detection nodes, the same descriptions will be omitted herein.

FIG. 6Ais a plan view illustrating still another embodiment of the control node included in the pixel illustrated inFIG. 2A.

FIG. 6Aillustrates still another embodiment600of the first and second control nodes included in the first pixel P1ofFIG. 2A. Since a first pixel P1ofFIG. 6Ais configured and operated in substantially the same manner as the first pixel P1ofFIG. 2Aexcept the shapes of first and second control nodes610and620, the following descriptions will be focused on differences fromFIG. 2A, in order to avoid repeating the same descriptions. Furthermore, since the shapes of the first and second control nodes610and620are similar to the shapes of the first and second control nodes510and520ofFIG. 5A, the following descriptions will be focused on a difference in shape fromFIG. 5A. Furthermore, only the first pixel P1is described for convenience of description, but it is obvious that substantially the same structure may be applied to the other pixels.

Each of the first and second control nodes610and620may include a plurality of protrusions611to614and621to624, respectively, which protrude toward the other control node.

The plurality of protrusions611to614and621to624may perform a similar function to the protrusions511and521described with reference toFIG. 5A. Thus, the plurality of protrusions611to614and621to624may reduce the distance between the control nodes, and increase the horizontal length of the first surfaces that face the other control node in the same pixel. However, when each of the first and second control nodes610and620has a plurality of protrusions with a smaller width than when the control node has one protrusion with a large width as illustrated inFIG. 5A, the self resistance of each of the first and second control nodes610and620may be increased. The self resistance may be decided by the structural complexity of each of the first and second control nodes610and620. For example, when each of the first and second control nodes610and620has a plurality of protrusions with a total width corresponding to a first width, the self resistance may be increased more than when the control node has one protrusion with a width corresponding to the first width.

Therefore, the resistance between the first and second control nodes610and620having the plurality of protrusions611to614and621to624may be increased more than when one protrusion is present. In this case, the hole current may be reduced, which makes it possible to reduce the power consumption of the pixel array30.

Each of the first surfaces616and626of the first and second control nodes610and620may include facing surfaces facing the other control node and connecting surfaces that connect the facing surfaces facing the other control node (for example, the left and right side surfaces of the protrusions612and613, the right side surface of the protrusion611and the left side surface of the protrusion614). Furthermore, a plurality of second surfaces617and627of the first and second control nodes610and620may indicate surfaces which are directly/indirectly connected to the first surfaces616and626(for example, the uppermost surface of the first control node610and surfaces directly connected thereto).

FIG. 6Aillustrates that the first and second control nodes610and620include four protrusions611to614and four protrusions621to624, respectively. However, the present embodiment is not limited thereto and other implementations are also possible. For example, each of the control nodes may include a random number of protrusions equal to or more than two, and the widths and extension lengths of the protrusions may be experimentally decided.

Furthermore, the widths and extension lengths of the protrusions may be equal to one another, or partially different from one another. For example, the extension lengths and widths of the protrusions may be gradually decreased from the center toward the edge of the control node.

FIG. 6Bis a plan view illustrating another embodiment of the detection node included in the pixel illustrated inFIG. 6A.

FIG. 6Billustrates a plan view600′ including a first pixel P1having detection nodes615′ and625′ which have different shapes from detection nodes615and625illustrated inFIG. 6A. That is, no separate insulating layer may be disposed between the first control node610and the first detection node615′ and between the second control node620and the second detection node625′, and the first detection node615′ and the second detection node625′ may be formed to surround the first control node610and the second control node620while abutting on the first control node610and the second control node620, respectively. In this case, the first control node610and the first detection node615′ may be physically isolated only by junction isolation, and the second control node620and the second detection node625′ may also be physically isolated only by junction isolation.

Since the first pixel P1ofFIG. 6Bis configured and operated in substantially the same manner as the first pixel P1ofFIG. 6Aexcept the shapes of the first and second detection nodes, the same descriptions will be omitted herein.

FIG. 7Ais a plan view illustrating still another embodiment of the control node included in the pixel illustrated inFIG. 2A.

FIG. 7Aillustrates still another embodiment700of the first and second control nodes included in the first pixel P1ofFIG. 2A. Since a first pixel P1ofFIG. 7Ais configured and operated in substantially the same manner as the first pixel P1ofFIG. 2Aexcept the shapes of first and second control nodes710and720, the following descriptions will be focused on differences fromFIG. 2A, in order to avoid repeating the same descriptions. Furthermore, since the shapes of the first and second control nodes710and720are similar to the shapes of the first and second control nodes610and620ofFIG. 6A, the following descriptions will be focused on a difference in shape fromFIG. 6A. Furthermore, only the first pixel P1is described for convenience of description, but it is obvious that substantially the same structure may be applied to the other pixels.

The first control node710may include a plurality of first isolation control nodes711to714disposed in a line. The plurality of first isolation control nodes711to714may be formed in such a shape that the plurality of protrusions611to614are independently isolated from the first control node610described with reference toFIG. 6A. Thus, the plurality of first isolation control nodes711to714may be formed in such a shape that the connection portion, which is disposed at the tops of the plurality of protrusions611to614so as to connect the plurality of protrusions611to614, is omitted from the first control node610. Although the plurality of first isolation control nodes711to714are physically isolated from one another, the plurality of first isolation control nodes711to714may receive the same first demodulation control signal.

The second control node720may include a plurality of second isolation control nodes721to724disposed in a line. The plurality of second isolation control nodes721to724may be formed in such a shape that the plurality of protrusions621to624are independently isolated from the second control node620described with reference toFIG. 6A. In other words, the plurality of second isolation control nodes721to724may be formed in such a shape that the connection portion, which is disposed at the bottoms of the plurality of protrusions621to624so as to connect the plurality of protrusions621to624, is omitted from the second control node620. Although the plurality of second isolation control nodes721to724are physically isolated from one another, the plurality of second isolation control nodes714to724may receive the same second demodulation control signal.

Since each of the first and second control nodes710and720is formed in such a shape that the connection portion connecting the plurality of protrusions611to614or621to624is omitted unlike the structure illustrated inFIG. 6A, the horizontal length of a surface facing a control node of an adjacent pixel may be reduced, which makes it possible to reduce crosstalk between the adjacent pixels.

Each of the isolation control nodes711to714and721to724may be extended toward the other control node within the same pixel, such that the extension length thereof is larger than the width thereof.

FIG. 7Aillustrates that the first and second control nodes710and720include four isolation control nodes711to714and four isolation control nodes721to724, respectively. However, the present embodiment is not limited thereto, but each of the control nodes may include a random number of isolation control nodes equal to or more than two, and the widths and extension lengths of the isolation control nodes may be experimentally decided. Furthermore, the widths and extension lengths of the isolation control nodes may be equal to one another, or different from one another. For example, the extension lengths and widths of the isolation control nodes may be gradually decreased from the center toward the edge of the control node.

FIG. 7Bis a plan view illustrating another embodiment of the detection node included in the pixel illustrated inFIG. 7A.

FIG. 7Billustrates a plan view700′ including a first pixel P1having detection nodes715′ and725′ which have different shapes from the detection nodes715and725illustrated inFIG. 7A. That is, no separate insulating layer may be disposed between the first control node710and the first detection node715′ and between the second control node720and the second detection node725′, and the first detection node715′ and the second detection node725′ may be formed to surround the first control node710and the second control node720while abutting on the first control node710and the second control node720, respectively. In this case, the first control node710and the first detection node715′ may be physically isolated only by junction isolation, and the second control node720and the second detection node725′ may also be physically isolated only by junction isolation.

Since the first pixel P1ofFIG. 7Bis configured and operated in substantially the same manner as the first pixel P1ofFIG. 7Aexcept the shapes of the first and second detection nodes, the same descriptions will be omitted herein.

FIG. 8Ais a plan view illustrating yet another embodiment of the control node included in the pixel illustrated inFIG. 2A.

FIG. 8Aillustrates yet another embodiment800of the first and second control nodes included in the first pixel P1ofFIG. 2A. Since a first pixel P1ofFIG. 8Ais configured and operated in substantially the same manner as the first pixel P1ofFIG. 2Aexcept the shapes of first and second control nodes810and820, the following descriptions will be focused on differences fromFIG. 2A, in order to avoid repeating the same descriptions. Furthermore, since the shapes of the first and second control nodes810and820are similar to the shapes of the first and second control nodes710and720ofFIG. 7A, the following descriptions will be focused on a difference in shape fromFIG. 7A. Furthermore, only the first pixel P1will be described for convenience of description, but it is obvious that substantially the same structure may be applied to the other pixels.

The first control node810may be formed in such a shape that the extension length thereof in the vertical direction is larger than the width thereof in the horizontal direction. Compared toFIG. 7A, the first control node810may correspond to the shape in which any one of the plurality of first isolation control nodes711to714included in the first control node710ofFIG. 7Ais included.

The second control node820may be formed in such a shape that the extension length thereof in the vertical direction is larger than the width thereof in the horizontal direction. Compared toFIG. 7A, the second control node820may correspond to the shape in which any one of the plurality of second isolation control nodes721to724included in the second control node720ofFIG. 7Ais included.

Since each of the first and second control nodes810and820is formed in a shape to include only any one of the plurality of isolation control nodes unlike the structure ofFIG. 7A, the current path between the control nodes within the same pixel and the current path between the control nodes of the adjacent pixels may be decreased to reduce the hole current, which makes it possible to reduce the power consumption of the pixel array30.

FIG. 8Bis a plan view illustrating another embodiment of the detection node included in the pixel illustrated inFIG. 8A.

FIG. 8Billustrates a plan view800′ including a first pixel P1which has detection nodes815′ and825′ having different shapes from detection nodes815and825illustrated inFIG. 8A. That is, no separate insulating layer may be disposed between the first control node810and the first detection node815′ and between the second control node820and the second detection node825′, and the first detection node815′ and the second detection node825′ may be formed to surround the first control node810and the second control node820while abutting on the first control node810and the second control node820, respectively. In this case, the first control node810and the first detection node815′ may be physically isolated only by junction isolation, and the second control node820and the second detection node825′ may also be physically isolated only by junction isolation.

Since the first pixel P1ofFIG. 8Bis configured and operated in substantially the same manner as the first pixel P1ofFIG. 8Aexcept the shapes of the first and second detection nodes, the same descriptions will be omitted herein.

FIG. 9is a plan view illustrating still another embodiment of the detection nodes included in the pixel illustrated inFIG. 2A.

FIG. 9illustrates still another embodiment900of the first and second detection nodes included in the first pixel P1ofFIG. 2A. Since a first pixel P1ofFIG. 9is configured and operated in substantially the same manner as the first pixel P1ofFIG. 2Aexcept the shapes of first and second detection nodes915and925, the following descriptions will be focused on differences fromFIG. 2A, in order to avoid repeating the same descriptions. Furthermore, only the first pixel P1is described for convenience of description, but it is obvious that substantially the same structure may be applied to the other pixels.

The first detection node915may have a shape to surround the left, the right and the top of a first control node910. The first detection node915may have a shape that does not surround the bottom of the first control node910. Thus, the first detection node910has an opening in a direction facing the other detection node925within the same pixel. For example, the opening of the first detection node is disposed around the middle part of the first detection node915.

The second detection node925may have a shape to surround the left, the right and the bottom of a second control node920. The second detection node925may have a shape that does not surround the top of the second control node920. Thus, the second detection node920has an opening in a direction facing the other detection node915within the same pixel. For example, the opening of the second detection node920is disposed around the middle part of the second detection node925.

As illustrated inFIG. 3A, the detection node may be not only formed adjacent to the control node so as to capture electrons migrated by the hole current, but also disposed between the adjacent control nodes so as to lengthen the current path of the hole current. When it is assumed inFIG. 3Athat the first and second detection nodes215and225disposed between the first and second control nodes210and220are not present, the current path of the hole current flowing between the first and second control nodes210and220may be shortened. This structure may cause the same effect as the distance between the first and second control nodes210and220is reduced.

Since the first detection node915does not surround the bottom of the first control node910and the second detection node925does not surround the top of the second control node920, the current path between the first and second control nodes910and920may be shortened more than inFIG. 2A. Therefore, the resistance between the first and second control nodes910and920may be reduced to increase the hole current flowing between the first and second control nodes910and920.

Since the first detection node915surrounds the left, right and top of the first control node910and the second detection node925surrounds the left, right and bottom of the second control node920, the length of the current path between any one of the first and second control nodes910and920and the control node of another adjacent pixel may be maintained as inFIG. 2A. Therefore, the first and second detection nodes915and925may relatively increase the resistances and the length of the current paths between any one of the first and second control nodes910and920and the control node of another adjacent pixel, thereby reducing crosstalk between the adjacent pixels.

FIG. 10is a plan view illustrating yet another embodiment of the detection node included in the pixel illustrated inFIG. 2A.

FIG. 10illustrates yet another embodiment1000of the first and second detection nodes included in the first pixel P1ofFIG. 2A. Since a first pixel P1ofFIG. 10is configured and operated in substantially the same manner as the first pixel P1ofFIG. 2Aexcept the shapes of first and second detection nodes1015and1025, the following descriptions will be focused on differences fromFIG. 2A, in order to avoid repeating the same descriptions. Furthermore, only the first pixel P1is described for convenience of description, but it is obvious that substantially the same structure may be applied to the other pixels.

The first detection node1015may have a shape to block the top of a first control node1010. The first detection node1015may have a shape that does not surround the left, right and bottom of the first control node1010, Thus, the first detection node1015may have openings in a direction facing the other detection node1025within the same pixel and directions corresponding to the sides of the first control node1010. For example, the first detection node1015may be disposed above the first control node1010in a direction further away from the second control node1020.

The second detection node1025may have a shape to block the bottom of a second control node1020. The second detection node1025may be formed in such a shape that does not surround the left, right and top of the second control node1020. Thus, the second detection node1025may have openings in a direction facing the other detection node1015within the same pixel and directions corresponding to the sides of the second control node1020. For example, the second detection node1025may be disposed under the second control node1020in a direction further away from the first control node1010.

Since the first detection node1015does not surround the left, right and bottom of the first control node1010and the second detection node1025does not surround the left, right and top of the second control node1020, the current path through which a hole current between the first and second control nodes1010and1020can flow may be further increased around the left and right of each of the first and second control nodes1010and1020than inFIG. 9. Therefore, as the resistance between the first and second control nodes1010and1020is reduced, the hole current flowing between the first and second control nodes1010and1020may be increased more than inFIG. 9.

Since the first detection node1015blocks the top of the first control node1010and the second detection node1025blocks the bottom of the second control node1020, the current path between any one of the first and second control nodes1010and1020and the control node of another adjacent pixel may be lengthened, thereby reducing crosstalk between the adjacent pixels, and concentrating the current path of the hole current between the first and second control nodes1010and1020.

FIG. 11is a plan view illustrating yet another embodiment of the detection node included in the pixel illustrated inFIG. 2A.

FIG. 11illustrates yet another embodiment1100of the first and second detection nodes included in the first pixel P1ofFIG. 2A. Since a first pixel P1ofFIG. 11is configured and operated in substantially the same manner as the first pixel P1ofFIG. 2Aexcept the shapes of first and second detection nodes1115and1125, the following descriptions will be focused on differences fromFIG. 2A, in order to avoid repeating the same descriptions. Furthermore, only the first pixel P1is described for convenience of description, but it is obvious that substantially the same structure may be applied to the other pixels.

The first detection node1115may include a top detection node1116to block the top of a first control node1110and a bottom detection node1117to block the bottom of the first control node1110. The first detection node1115may have a shape that does not surround the left and right of the first control node1110. Thus, the first detection node1115may have openings in directions corresponding to side surfaces of the first control node1110. For example, the first detection node1115has portions that are disposed above and below the first control node1110along a direction that the first control node1110and the second control node1120are arranged.

The second detection node1125may include a top detection node1126to block the top of a second control node1120and a bottom detection node1127to block the bottom of the second control node1120. The second detection node1125may have a shape that does not surround the left and right of the second control node1120. Thus, the second detection node1125may have openings in directions corresponding to side surfaces of the second control node1120. For example, the second detection node1125has portions that are disposed above and below the second control node1120along a direction that the first control node1110and the second control node1120are arranged.

Since the first detection node1115additionally blocks the bottom of the first control node1110and the second detection node1125additionally blocks the top of the second control node1120unlike the structure ofFIG. 10, the current path between the first and second control nodes1110and1120may be lengthened. Therefore, the resistance between the first and second control nodes1110and1120may be increased to decrease the hole current flowing between the first and second control nodes1110and1120, compared toFIG. 10. Thus, the power consumption of the pixel array30may be reduced.

Since the first detection node1115blocks the top of the first control node1110and the second detection node1125blocks the bottom of the second control node1120, the current path between any one of the first and second control nodes1110and1120and the control node of another adjacent pixel may be lengthened, thereby reducing crosstalk between the adjacent pixels, and concentrating the current path of the hole current between the first and second control nodes1110and1120.

FIG. 12is a plan view illustrating still another embodiment of the pixel included in the pixel array illustrated inFIG. 1.

FIG. 12illustrates a plan view1200including first to fourth pixels P1to P4which are arranged in a 2×2 matrix so as to be adjacent to one another, and the pixel array30may have a structure in which substantially the same pixels as the first to fourth pixels P1to P4are arranged in a matrix shape.

The first to fourth pixels P1to P4ofFIG. 12are configured and operated in substantially the same manner as the first to fourth pixels P1to P4ofFIG. 2A, except the shapes of first and second control nodes1210,1220,1230,1240,1250,1260,1270and1280. Therefore, the following descriptions will be focused on differences fromFIG. 2A, in order to avoid repeating the same descriptions.

Each of the first and second control nodes1210,1220,1230,1240,1250,1260,1270and1280may have a rectangular shape (for example, rectangle or square). The rectangular shape is only an example, and each of the first and second control nodes1210,1220,1230,1240,1250,1260,1270and1280may have a random shape including a first surface facing the other control node within the same pixel and a plurality of second surfaces which do not face the other control node within the same pixel. For example, the first control node1210may have a first surface1211facing the second control node1220within the same pixel P1and a plurality of second surfaces1212which do not face the second control node1220within the same pixel P1. The plurality of second surfaces1212may be directly/indirectly connected to the first surface1211.

FIG. 13is a cross-sectional view of the pixel illustrated inFIG. 12.

The first and second pixels P1and P2ofFIG. 13are configured and operated in substantially the same manner as the first and second pixels P1and P2ofFIG. 3A, except the shapes of first and second control nodes1210,1220,1230and1240. Therefore, the following descriptions will be focused on differences fromFIG. 3A, in order to avoid repeating the same descriptions.

First, the first pixel P1will be described. The first control node1210may have a first surface1211facing the second control node1220within the same pixel P1and a plurality of second surfaces1212which do not face the second control node1220within the same pixel P1. The vertical depth of the first surface1211from the top surface of the substrate1295may be larger than the vertical depth of any one of the plurality of second surfaces1212from the top surface of the substrate1295. Specifically, the second surface1212facing the first surface1211, among the plurality of second surfaces1212, may have the smallest vertical depth, and the average vertical depth of the second surfaces1212which does not face the first surface1211, among the plurality of second surfaces1212, i.e. the second surfaces1212directly connected to the first surface1211, may correspond to a value between the vertical depth of the second surface1212facing the first surface1211and the vertical depth of the first surface1211. This is because the vertical depth of one of the second surfaces1212which do not face the first surface1211is equal to the vertical depth of the second surface1212facing the first surface1211, the vertical depth of the other of the second surfaces1212which do not face the first surface1211is equal to the vertical depth of the first surface1211, and the vertical depth gradually increases from the one toward the other.

The second control node1220may have a first surface1221facing the first control node1210within the same pixel P1and a plurality of second surfaces1222which do not face the first control node1210within the same pixel P1. The vertical depth of the first surface1221from the top surface of the substrate295may be larger than the vertical depth of any one of the plurality of second surfaces1222from the top surface of the substrate295. Specifically, the second surface1222facing the first surface1221, among the plurality of second surfaces1222, may have the smallest vertical depth, and the average vertical depth of the second surfaces1222which does not face the first surface1221, among the plurality of second surfaces1222, i.e. the second surfaces1222directly connected to the first surface1221, may correspond to a value between the vertical depth of the second surface1222facing the first surface1221and the vertical depth of the first surface1221. This is because the vertical depth of one of the second surfaces1222which do not face the first surface1221is equal to the vertical depth of the second surface1222facing the first surface1221, the vertical depth of the other of the second surfaces1222which do not face the first surface1221is equal to the vertical depth of the first surface1221, and the vertical depth gradually increases from the one toward the other.

Therefore, the areas of the first surfaces1211and1221may be larger than the area of any one of the plurality of second surfaces1212and1222.

The first and second control nodes1210and1220having such an inclined cross-section may be implemented through at least one of tilt, angle and rotation methods during an implant process.

Since the second pixel P2is configured and operated in substantially the same manner as the first pixel P1, the detailed descriptions thereof are omitted herein.

Therefore, considering the magnitudes of hole currents between the second control node1220and the control nodes1210and1230therearound, the hole current flowing between the second control node1220and the first control node1210has the largest magnitude, because the first control node1210is the closest to the second control node1220and its surface facing the second control node1220has the largest area. Furthermore, the hole currents between the second control node1220and the first control node1230have relatively small magnitude, because the first control node1230is relatively remote from the second control node1220and its surface facing the second control node1220has relatively narrow area.

Therefore, crosstalk between adjacent pixels may be reduced, and unnecessary power consumption may be reduced.

FIGS. 12 and 13are based on the supposition that the first and second control nodes have a rectangular shape. As described above, however, the first and second control nodes have be formed in a random shape having the first surface and the plurality of second surfaces. Furthermore, according to another embodiment, the first and second demodulation nodes may have a plane shape in accordance with any one of the various embodiments described withFIGS. 2A to 11, and the first surfaces of the first and second control nodes may have a larger depth than any one of the plurality of second surfaces of each of the first and second control nodes. That is, the vertical shapes described with reference toFIGS. 12 and 13and the plane shapes described with reference toFIGS. 2A to 11may be implemented in combination.

In accordance with various embodiments, it is possible to not only minimize crosstalk between adjacent pixels and the power consumption of the entire pixel array, but also improve the transmission efficiency of a hole current flowing in a unit pixel. Therefore, although the size of the CAPD pixel is reduced, the pixel may be designed to have the optimal performance.

In accordance with various embodiments, each of the above-described components (for example, module or program) may include a single object or a plurality of objects. In accordance with various embodiments, one or more components of the above-described components or one or more operations may be omitted, or one or more other components or operations may be added. Alternatively or additionally, a plurality of components (for example, modules or programs) may be merged into one component. In this case, the merged component may perform one or more functions of each of the plurality of components in the same or similar manner as or to the corresponding component among the plurality of components before the merge. In accordance with various embodiments, operations performed by modules, programs or other components may be performed sequentially, in parallel, repeatedly or heuristically, one or more of the operations may be performed in another order or omitted, or one or more other operations may be added.

While certain embodiments have been described above, it will be understood to those skilled in the art that the embodiments described are by way of example only. Accordingly, the pixel and the image sensor described herein should not be limited based on the described embodiments. Rather, the pixel and the image sensor described herein should only be limited in light of the claims that follow when taken in conjunction with the above description and accompanying drawings.