KR20120015257A - Unit pixel, photo-detection device and method of measuring a distance using the same - Google Patents

Abstract

PURPOSE: An apparatus for sensing a unit pixel and light and a method for measuring a distance using the same are provided to produce a high signal to noise ratio by using variable and empty signals according to a distance to a subject. CONSTITUTION: A floating diffusion area(110) is formed on a semiconductor substrate. A collect gate(120) is formed on the semiconductor substrate to surround the floating diffusion area. A drain gate(130) is formed on the semiconductor substrate to surround the collect gate. A drain region(140) is formed on the semiconductor substrate to surround the drain gate. A photo charge storing area(150) is doped with a conductive impurity which is opposite to the semiconductor substrate.

Description

Unit pixel of photosensitive device, photosensitive device and distance measuring method using same {UNIT PIXEL, PHOTO-DETECTION DEVICE AND METHOD OF MEASURING A DISTANCE USING THE SAME}

The present invention relates to a light sensing device, and more particularly, to an optical sensing device including an annular unit pixel, at least one unit pixel, and a distance measuring method using the unit pixel.

The image sensor is an optical sensing device that converts an optical signal including image information or distance (depth) information about a subject into an electrical signal. In order to provide high quality image information of a subject, research on various image sensors such as a charge image device (CCD) and a CMOS image sensor (CIS) is being conducted. In addition, research and development of a 3D image sensor (3D image sensor) that provides distance information together is in progress.

The 3D image sensor may acquire distance information about a subject using infrared rays or near infrared rays as a light source. Compared with the conventional two-dimensional image sensor for image information, the three-dimensional image sensor has a weak sensitivity in the process of acquiring distance information, and it is difficult to secure a signal-to-noise ratio (SNR). There is a problem of obtaining distance information.

One object of the present invention is to provide a unit pixel of a light sensing device having a structure capable of realizing high sensitivity and improved signal-to-noise ratio.

An object of the present invention is to provide a light sensing device including at least one unit pixel.

An object of the present invention to provide a method for measuring the distance of the subject using the light sensing device.

In order to achieve the above object, the unit pixel of the optical sensing device according to the embodiments of the present invention, a floating diffusion region formed in the semiconductor substrate, the annular collector gate formed on the semiconductor substrate so as to surround the floating diffusion region And an annular drain gate formed on the semiconductor substrate to surround the collect gate, and a drain region formed on the semiconductor substrate to surround the drain gate.

The annular collect gate and the annular drain gate may be circular or regular polygonal.

Complementaryly activated collector and drain gate signals are applied to the collector gate and the drain gate, respectively, so that photocharges generated in the semiconductor substrate are collected into the floating diffusion region while the collector gate signal is activated. While the gate signal is activated, photocharges generated in the semiconductor substrate may be emitted to the drain region.

The unit pixel may further include a photocharge storage region that is doped with impurities of a conductivity type opposite to that of the semiconductor substrate and is formed in an annular shape in the semiconductor substrate between the floating diffusion region and the drain region.

The collect gate may be formed in an annular shape to cover an inner portion of the photocharge storage region, and the drain gate may be formed in an annular shape to cover an outer portion of the photocharge storage region.

The collect gate may be formed annularly between the photocharge storage region and the floating diffusion region, and the drain gate may be formed annularly between the photocharge storage region and the drain region.

The unit pixel may further include a pinning layer formed in an annular shape on the semiconductor substrate to be doped with impurities of an opposite conductivity type to the photocharge storage region to cover the photocharge storage region.

The unit pixel may further include an annular photo gate formed on the semiconductor substrate to be disposed between the collect gate and the drain gate to cover the photocharge storage region.

The semiconductor substrate may include a plurality of photocharge generating regions which are distinguished by doping impurities of the same conductivity type at different concentrations.

In order to achieve the above object, the optical sensing device according to the embodiments of the present invention includes a sensing unit including at least one unit pixel for converting received light into an electrical signal, and a control unit for controlling the sensing unit. . The unit pixel may include a floating diffusion region formed on a semiconductor substrate, an annular collector gate formed on the semiconductor substrate to surround the floating diffusion region, an annular drain gate formed on the semiconductor substrate to surround the collect gate, and And a drain region formed in the semiconductor substrate to surround the drain gate.

The sensing unit may include a pixel array in which the plurality of unit pixels are arranged in a rectangular lattice structure or a triangular lattice structure.

The drain regions of the unit pixels adjacent to each other may be spatially connected to each other in the semiconductor substrate so that the drain regions of the plurality of unit pixels may be integrally formed.

Floating diffusion regions of two or more of the unit pixels may be electrically connected to each other to form a pixel group.

The unit pixels are regularly omitted among the grid points of the lattice structure, and the optical sensing device may further include a readout circuit formed in an area where the unit pixels are omitted to provide an output value of the unit pixels.

The plurality of unit pixels may include color pixels and distance pixels, and the light sensing device may be a 3D image sensor.

In order to achieve the above object, the distance measuring method according to the embodiments of the present invention, irradiating the transmission light to the subject, using a plurality of empty signals having an increasing number of cycles in accordance with the phase difference with the transmission light Converting the received light reflected by the subject and incident into an electrical signal, and calculating a distance to the subject based on the electrical signal.

The duty ratio of the plurality of empty signals may increase according to a phase difference from the transmitted light.

The converting of the received light into an electrical signal may include collecting photocharges generated by the received light in a floating diffusion region while the empty signals are activated, and by the received light while the empty signals are inactive. And discharging the generated photocharges to the drain region.

The converting of the received light into an electrical signal may include using a single-tap pixel having an annular structure having the floating diffusion region at the center and the drain region at the outermost position.

The distance measuring method may include adjusting a phase and a duty ratio of the plurality of empty signals to concentrate on a phase corresponding to the calculated distance, and using the plurality of empty signals having the adjusted phase and duty ratio to the subject. The method may further include correcting a distance of.

The unit pixel according to the embodiments of the present invention has an annular single-tap structure capable of effectively collecting and emitting photocharges in order to accurately measure the distance to the subject.

In addition, in the pixel array and the light sensing device including the unit pixels according to the exemplary embodiments of the present invention, drain regions corresponding to the outermost portions of the unit pixels are integrally formed so that a separate anti-blooming structure is not required and overall design margin is increased. This can be improved.

In addition, the optical sensing device and the distance measuring method according to the embodiments of the present invention can realize a high signal-to-noise ratio in obtaining distance information using empty signals that vary according to the distance to the subject.

1 is a diagram illustrating a layout of unit pixels of a light sensing device according to embodiments of the present invention.
2 is a plan view illustrating a unit pixel of a light sensing device according to an embodiment of the present invention.
3 and 4 are cross-sectional views illustrating examples of a vertical structure of a unit pixel of FIG. 2.
5 and 6 are diagrams for describing horizontal movement of photocharges in a unit pixel according to example embodiments.
7 is a plan view illustrating a unit pixel of a light sensing device according to an embodiment of the present invention.
8 and 9 are cross-sectional views illustrating examples of a vertical structure of a unit pixel of FIG. 7.
10 is a plan view illustrating a unit pixel of a light sensing device according to an embodiment of the present invention.
11 and 12 are cross-sectional views illustrating examples of a vertical structure of a unit pixel of FIG. 10.
13 through 17 are diagrams illustrating pixel arrays according to example embodiments.
18 is a diagram illustrating an example of a read circuit for providing an output value of a unit pixel.
19 is a block diagram illustrating a light sensing device according to embodiments of the present invention.
20 is a flowchart illustrating a distance measuring method according to embodiments of the present invention.
21 is a timing diagram illustrating signals for converting received light into an electrical signal.
22 and 23 are timing diagrams for describing variable bin signals used in the distance measuring method of FIG. 20.
24 is a diagram illustrating an example of variable bin signals.
FIG. 25 is a diagram illustrating examples of phases, lengths of activation intervals, and cycles of empty signals of FIG. 24.
26 is a flowchart illustrating a distance measuring method according to embodiments of the present invention.
27 is a diagram illustrating an example of variable bin signals.
FIG. 28 is a diagram illustrating examples of phases, lengths of activation intervals, and cycles of empty signals of FIG. 27.
29 is a diagram illustrating an example of corrected empty signals.
30 is a block diagram illustrating a sensing unit of a 3D image sensor according to an exemplary embodiment.
FIG. 31 is a diagram illustrating an example of a pixel array included in the sensing unit of FIG. 30.
32 is a block diagram illustrating an example in which a 3D image sensor is applied to a camera, according to an exemplary embodiment.
33 is a block diagram illustrating an example in which a 3D image sensor is applied to a computing system according to an exemplary embodiment.
FIG. 34 is a block diagram illustrating an example of an interface used in the computing system of FIG. 33.

With respect to the embodiments of the present invention disclosed in the text, specific structural to functional descriptions are merely illustrated for the purpose of describing embodiments of the present invention, embodiments of the present invention may be implemented in various forms and It should not be construed as limited to the embodiments described in.

As the inventive concept allows for various changes and numerous modifications, particular embodiments will be illustrated in the drawings and described in detail in the text. However, this is not intended to limit the present invention to a specific disclosed form, it should be understood to include all modifications, equivalents, and substitutes included in the spirit and scope of the present invention.

The terms first, second, etc. may be used to describe various components, but the components should not be limited by the terms. The terms may be used for the purpose of distinguishing one component from another. For example, without departing from the scope of the present invention, the first component may be referred to as a second component, and similarly, the second component may also be referred to as a first component.

It is to be understood that when an element is referred to as being "connected" or "connected" to another element, it may be directly connected or connected to the other element, . On the other hand, when an element is referred to as being "directly connected" or "directly connected" to another element, it should be understood that there are no other elements in between. Other expressions that describe the relationship between components, such as "between" and "between" or "neighboring to" and "directly adjacent to" should be interpreted as well.

The terminology used herein is for the purpose of describing particular example embodiments only and is not intended to be limiting of the present invention. Singular expressions include plural expressions unless the context clearly indicates otherwise. In this application, the terms "comprise" or "having" are intended to indicate that there is a feature, number, step, action, component, part, or combination thereof that is described, and that one or more other features or numbers are present. It should be understood that it does not exclude in advance the possibility of the presence or addition of steps, actions, components, parts or combinations thereof.

Unless defined otherwise, all terms used herein, including technical or scientific terms, have the same meaning as commonly understood by one of ordinary skill in the art. Terms such as those defined in the commonly used dictionaries should be construed as meanings consistent with the meanings in the context of the related art and shall not be construed in ideal or excessively formal meanings unless expressly defined in this application. .

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. The same or similar reference numerals are used for the same components in the drawings.

1 is a diagram illustrating a layout of unit pixels of a light sensing device according to embodiments of the present invention.

Referring to FIG. 1, a unit pixel may include a first region REG1, a second region REG2, and a third region REG3. The first region REG1 is positioned at the center of the unit pixel, the second region REG2 surrounds the first region REG1, and the third region REG3 surrounds the second region REG2. The pixel has an annular structure as a whole. Although a circular unit pixel is illustrated in FIG. 1, the annular structure of the unit pixel is not limited to a circle but may be any polygon, in particular, an arbitrary polygon.

As described below with reference to FIGS. 2 to 12, the first region REG1 corresponds to a floating diffusion region for collecting photocharges and the third region REG3 corresponds to a drain region for emitting photocharges. . The second region REG2 corresponding to the first region REG1 and the third region REG3 corresponds to a gate region in which at least one gate is formed.

In an embodiment, the unit pixel may be formed through a CMOS process using a semiconductor substrate. As in the general CMOS process, the floating diffusion region, which is the first region REG1, and the drain region, which is the third region REG3, may be formed on the semiconductor substrate through an ion implantation process, and the second region REG2 may be formed. Gates formed in the gate region may be formed on the semiconductor substrate through a deposition process, an etching process, or the like.

2 is a plan view illustrating a unit pixel of a light sensing device according to an embodiment of the present invention.

Referring to FIG. 2, the unit pixel 100 includes a floating diffusion region 110, a collect gate 120, a drain gate 130, and a drain region 140. When the unit pixel 100 is viewed from above, the collect gate 120 is formed in an annular shape on the semiconductor substrate so as to surround the floating diffusion region 110 formed in the semiconductor substrate, and the drain gate 130 forms the collect gate 120. It is formed in an annular shape on the semiconductor substrate to surround. The drain region 140 formed in the semiconductor substrate is formed to surround the drain gate 130.

As described below with reference to FIGS. 3 and 4, the unit pixel 100 may be formed through a CMOS process using a semiconductor substrate. In this case, the floating diffusion region 110 and the drain region 140 are formed on the semiconductor substrate, and the collect gate 120 and the drain gate 130 are formed on the semiconductor substrate.

The annular collect gate 120 and the annular drain gate 130 are circular and are shown in FIG. 2, but as shown in FIGS. 15 and 16, the annular collect gate 120 and the annular drain gate 130 are illustrated. ) May be a regular polygon.

The inner boundary of the drain region 140 may have the same shape as the collect gate 120 and the drain gate 130, but the outer boundary of the drain region 140 may have a different shape. In particular, when a plurality of unit pixels are arranged in an array form as illustrated in FIG. 13, drain regions of adjacent unit pixels are spatially connected to each other on a semiconductor substrate, and drain regions of the plurality of unit pixels are integrally formed. Can be. In this case, since the drain regions are integrally formed, it can be seen that the outer boundary of the drain region exclusive to each unit pixel is not defined.

3 and 4 are cross-sectional views illustrating examples of a vertical structure of a unit pixel of FIG. 2. 3 and 4 are vertical cross-sectional views taken along the line I1-I2 of FIG. Since the unit pixel 100 of FIG. 2 is an annular structure having substantially circular symmetry, the line I1-I2 may be any cut line passing through the center of the unit pixel 100.

Referring to FIG. 3, the unit pixel 100a includes the floating diffusion region 110 and the drain region 140 formed on the semiconductor substrate 10, and the collect gate 120 and the drain gate 130 formed on the semiconductor substrate 10. It includes. As described above, the floating diffusion region 110, the drain region 140, the collect gate 120, and the drain gate 130 have a substantially circularly symmetrical annular structure with respect to the vertical center axis VC.

The floating diffusion region 110 and the drain region 140 may be formed in the semiconductor substrate 10 through an ion implantation process to the upper surface of the semiconductor substrate 10, and the collect gate 120 and the drain gate 130 may be formed. ) May be formed to be spaced apart from the semiconductor substrate 10 through a deposition process, an etching process, or the like. Although not illustrated, an insulating layer such as an oxide layer may be interposed between the upper surface of the semiconductor substrate 10 and the gates 120 and 130.

The collect gate 120 and the drain gate 130 may include polysilicon or may include transparent conducting oxide (TCO). For example, the collect gate 120 and the drain gate 130 may include indium tin oxide (ITO), indium zinc oxide (IZO), zinc oxide (ZnO), and titanium oxide ( titanium dioxide, TiO2), or a combination thereof.

Light incident on the unit pixel 100a may be incident from the upper surface of the semiconductor substrate 10, and in this case, the collector gate 120 and the drain gate 130 may be formed of a transparent conductive oxide. On the other hand, light incident on the unit pixel 100a may be incident from the lower surface of the semiconductor substrate 10, and in this case, the collect gate 120 and the drain gate 130 may include an opaque conductive oxide.

The unit pixel 100a is doped with impurities of an opposite conductivity type to the semiconductor substrate 10 to form an annular charge storage region 150 formed in an annular shape in the semiconductor substrate 10 between the floating diffusion region 110 and the drain region 140. ) May be further included. That is, the photocharge storage region 150 may be formed under the gates 120 and 130 of the annular shape so as to be spaced apart from the floating diffusion region 110 and the drain region 140. In one embodiment, the semiconductor substrate 10 is a P-type substrate and the photocharge storage region 150 may be doped with N-type impurities. In another embodiment, the semiconductor substrate 10 may be an N-type semiconductor substrate or an N-type well formed in a P-type substrate and the photocharge storage region 150 may be doped with P-type impurities.

As shown in FIG. 3, the collect gate 120 is formed in an annular shape to cover an inner portion of the photocharge storage region 150, and the drain gate 130 covers an outer portion of the photocharge storage region 150. It may be formed in an annular shape so that. In this case, the photocharge storage region 150 may be formed in an annular shape first, and the gates 120 and 130 may be formed later in the annular shape along the photocharge storage region 150.

The collect gate signal CG and the drain gate signal DRG are applied to the collect gate 120 and the drain gate 130, respectively. In one embodiment, the collect gate signal CG and the drain gate signal DRG may be signals complementarily activated as shown in FIGS. 5 and 6. When the collect gate signal CG is activated, a channel is formed only in the semiconductor substrate 10 below the collect gate 120, that is, between the photocharge storage region 150 and the floating diffusion region 110. When the DRG is activated, a channel is formed only in the semiconductor substrate 10 under the drain gate 130, that is, between the photocharge storage region 150 and the drain region 140.

As a result, the photoelectric charges generated in the semiconductor substrate 10 while the collect gate signal CG is activated are collected into the floating diffusion region 110 and the photoelectric generated in the semiconductor substrate 10 while the drain gate signal DRG is activated. Is discharged to the drain region 140. The drain voltage DR applied to the drain region 140 may have an appropriate voltage level according to the conductivity type of the semiconductor substrate 10 and the voltage level of the drain gate signal DRG.

In the time-of-flight (TOF) light sensing device, the light reflected by the subject and incident to measure the distance to the subject are measured. For this purpose, a lock-in type detection method using two bins or four bins is generally used.

Typically, in lock-in type detection, these bins have a phase difference of 180 degrees (for 2-bins) or 90 degrees (for 4-bins) with the transmitted light irradiated on the subject, and are sinusoidally modulated waves or duty. A ratio 50% pulse train signal is used. For the lock-in type detection, multi-tap structured unit pixels in which the photocharge storage region and / or the photocharge generation region are shared by a plurality of floating diffusion regions are used.

Alternatively, the unit pixel 100 according to the embodiments of the present invention has an annular structure around the floating diffusion region 110, and output is provided only through one floating diffusion region 110 per unit pixel. . The outermost drain region 140 is included to emit photocharge generated during an undesired time.

The photocharges collected in the floating diffusion region 110 are converted into electrical signals corresponding to the amount of photocharges that have been read and collected through a readout circuit described below as a floating diffusion voltage FD. As such, the unit pixel 100 may be used as a single-tap detector in which output is provided only through the floating diffusion region 110.

Referring to FIG. 4, the unit pixel 100b is formed on the floating diffusion region 110, the drain region 140, and the semiconductor substrate 10 formed on the semiconductor substrate 10, similarly to the unit pixel 100a of FIG. 3. The gate 120 and the drain gate 130 are included. In addition, the photocharge storage region 150 may be further included. In FIG. 3 and FIG. 4, overlapping descriptions of components denoted by the same or similar reference numerals will be omitted.

Compared to the unit pixel 100a of FIG. 3, the semiconductor substrate 10 of the unit pixel 100b of FIG. 4 includes a plurality of regions 11, 13, and 15 in which impurities of the same conductivity type are doped to different concentrations. ). For example, when the semiconductor substrate 10 is a P type conductivity type, the semiconductor substrate 10 may include the P region 11, the P− region 13, and the P + region 15 sequentially from above. . The P− region 13 shows a lower impurity concentration than the P region 11, and the P + region 15 shows a higher impurity concentration than the P region 11.

When Near Infrared Radiation (NIR) having a wavelength of 700 nm to 850 nm is used as the transmission light of the TOF photosensitive device, a P type semiconductor substrate may be used rather than an N type semiconductor substrate. The penetration of the P-region 13 may be about 2 um to 20 um, in particular 3 um to 5 um.

Photons incident on the unit pixel 100b penetrate into the P-region 13 to generate electron-hole pairs. That is, the P- region 13 corresponds to the main photocharge generating region. Photoelectrons as generated minority carriers move to the depletion region of the NP junction corresponding to the boundary between the photocharge storage region 150 and the P- region 13 and into the photocharge storage region 150. Is spread and collected. The photocharge storage region 150 is substantially fully depleted and resembles a buried channel of a charge-coupled device (CCD). At this time, since the P + region 15 having a higher impurity concentration is located below the P- region 13, the optoelectronics generated near the boundary between the P- region 13 and the P + region 15 are transferred to the NP junction region ( The tendency to move to the NP junction portion increases.

As described above, by forming the plurality of photocharge generating regions 11, 13, and 15 on the semiconductor substrate 10, in which impurities are doped at different concentrations, the sensitivity of the unit pixel 100b may be further improved. .

5 and 6 are diagrams for describing horizontal movement of photocharges in a unit pixel according to example embodiments.

5 illustrates a collection mode in the unit pixel 100b of FIG. 4, and FIG. 6 illustrates a rejection mode in the unit pixel 100b of FIG. 4.

Referring to FIG. 5, in the acquisition mode, the collect gate signal CG applied to the collect gate 120 is activated and the drain gate signal DRG applied to the drain gate 130 is deactivated. For example, the collect gate signal CG may be activated at a relatively high voltage such as 3.3V and the drain gate signal DRG may be deactivated at a relatively low voltage such as 0.0V.

In this case, as shown in FIG. 5, an electric potential wall is formed between the drain region 140 and the photocharge storage region 150 to limit the movement of the photoelectrons and to the photocharge storage region 150. Diffused photoelectrons are collected into the floating diffusion region 110 through a channel formed near the surface of the semiconductor substrate 10 between the photocharge storage region 150 and the floating diffusion region 110. At this time, the photoelectrons are collected in the floating diffusion region 110 through horizontal movement in the centripetal direction by the annular structure of the unit pixels.

Referring to FIG. 6, in the emission mode, the collect gate signal CG applied to the collect gate 120 is inactivated and the drain gate signal DRG applied to the drain gate 130 is activated. For example, the collect gate signal CG may be deactivated at a relatively low voltage such as 0.0V and the drain gate signal DRG may be activated at a relatively high voltage such as 3.3V.

In this case, a potential barrier is formed between the floating diffusion region 110 and the photocharge storage region 150 as shown in FIG. 6, thereby restricting the movement of the photoelectrons. It is emitted to the drain region 140 through a channel formed near the surface of the semiconductor substrate 10 between the charge storage region 150 and the drain region 140. At this time, the photoelectrons are emitted to the drain region 140 by horizontal movement in the centrifugal direction by the annular structure of the unit pixel.

The drain voltage DR may be maintained at an appropriate level of bias voltage at which the potential distributions of FIGS. 5 and 6 can be formed. For example, the drain voltage DR may be a power supply voltage of the photosensitive device including the unit pixel.

As described above, the unit pixel of the annular structure according to the exemplary embodiments of the present invention may induce collection of photocharges through horizontal movement in the centripetal direction or emission of photocharges through horizontal movement in the centrifugal direction according to the gate signals CG and DRG. Improved sensitivity and high signal-to-noise ratio can be achieved. That is, accurate distance information may be obtained by repeating a collection mode for moving a desired charge carrier to the floating diffusion region 110 and an emission mode for discharging unwanted charge carriers to the drain region 140.

5 and 6 illustrate the case of the acquisition mode and the emission mode, respectively, but the unit pixel may operate in different modes according to a voltage application method. For example, an intermediate level bias voltage may be applied to the collect gate 120 and the drain gate 130. In this case, carriers generated in the P− region 13, which is a photocharge generating region, are accumulated in the photocharge storage region 150. At this time, the outer drain region 140 may function as an anti-blooming drain. After the collect gate signal CG is activated, carriers accumulated in the photocharge storage region 150 are transmitted to the floating diffusion region 110. By applying this mode to the unit pixel 100, correlated double sampling (CDS) may be performed, or image information may be provided instead of distance information.

5 and 6, the specific structure of the unit pixel for implementing the potential distribution, the gate voltages CG and DRG for driving the unit pixel 100, the specific voltage levels of the drain voltage DR, and the like. May be determined by process simulation and modeling.

7 is a plan view illustrating a unit pixel of the light sensing device according to an embodiment of the present invention, and FIGS. 8 and 9 are cross-sectional views illustrating examples of a vertical structure of the unit pixel of FIG. 7.

Referring to FIG. 7, the unit pixel 200 includes a floating diffusion region 210, a collect gate 220, a drain gate 230, and a drain region 240. Similarly to the unit pixel 100 of FIG. 2, when the unit pixel 200 is viewed from above, the collect gate 220 is formed in an annular shape on the semiconductor substrate to surround the floating diffusion region 210 formed in the semiconductor substrate and has a drain gate. 230 is formed in an annular shape on the semiconductor substrate so as to surround the collect gate 220. The drain region 240 formed in the semiconductor substrate is formed to surround the drain gate 230.

As shown in FIG. 8, the unit pixel 200a is doped with impurities of a conductivity type opposite to that of the semiconductor substrate 10 to form an annular shape in the semiconductor substrate 10 between the floating diffusion region 210 and the drain region 240. The photocharge storage region 250 may be further included.

In the unit pixel 100 of FIG. 2, the collect gate 120 and the drain gate 130 are formed in an annular shape to cover a portion of the photocharge storage region 150. In the unit pixel 200a of FIG. 8, the collect gate ( 220 may be annularly formed between the photocharge storage region 250 and the floating diffusion region 210, and the drain gate 230 may be annularly formed between the photocharge storage region 250 and the drain region 240. have.

Referring to FIG. 8, the pinning layer of the unit pixel 200a is formed in an annular shape on the semiconductor substrate 10 to be doped with impurities of the opposite conductivity type to the photocharge storage region 250 to cover the photocharge storage region 250. (pinning layer) 270 may be further included. For example, when the photocharge storage region 250 is doped with N-type impurities, the pinning layer 270 may be doped with P-type impurities. The pinning layer 270 reduces the dark current and at the same time reduces the effect of defects that may be present on the surface of the semiconductor substrate 10 to reduce the potential across the photocharge storage region 250. It can serve to make the flatter. At this time, if the doping concentration of the photocharge storage region 250 is further lowered, the potentials of the drain gate 230 and the collect gate 220 may be more rapidly formed, and as a result, the horizontal movement of the photocharges may be promoted. have.

Compared to the unit pixel 200a of FIG. 8, the semiconductor substrate 10 of the unit pixel 200b of FIG. 9 may include a plurality of photocharge generation regions 11, in which impurities of the same conductivity type are doped at different concentrations to distinguish them. 13, 15).

For example, when the semiconductor substrate 10 is a P type conductivity type, the semiconductor substrate 10 may include the P region 11, the P− region 13, and the P + region 15 sequentially from above. . The P− region 13 shows a lower impurity concentration than the P region 11, and the P + region 15 shows a higher impurity concentration than the P region 11. In this case, the pinning layer 270 may be doped with a high concentration of P-type impurities, similar to the P + region 15.

As described above, the photoelectrons generated near the boundary between the P- region 13 and the P + region 15 are located at the bottom of the P- region 13 by placing the P + region 15 having a higher impurity concentration. The tendency to move to the region NP junction portion is increased. As described above, by forming the plurality of photocharge generating regions 11, 13, and 15 on the semiconductor substrate 10 which are different from each other by being doped with impurities at different concentrations, the sensitivity of the unit pixel 200b may be further improved. .

FIG. 10 is a plan view illustrating a unit pixel of a light sensing device according to an embodiment of the present invention, and FIGS. 11 and 12 are cross-sectional views illustrating examples of a vertical structure of a unit pixel of FIG. 10.

Referring to FIG. 10, the unit pixel 300 includes a floating diffusion region 310, a collect gate 320, a drain gate 330, and a drain region 340. Similarly to the unit pixel 100 of FIG. 2 and the unit pixel 200 of FIG. 7, when the unit pixel 300 is viewed from above, the collect gate 320 may surround the floating diffusion region 310 formed in the semiconductor substrate. An annular shape is formed on the semiconductor substrate, and the drain gate 330 is annularly formed on the semiconductor substrate to surround the collect gate 320. The drain region 340 formed in the semiconductor substrate is formed to surround the drain gate 330.

As shown in FIG. 11, the unit pixel 300a is doped with impurities of a conductivity type opposite to that of the semiconductor substrate 10 to form an annular shape in the semiconductor substrate 10 between the floating diffusion region 310 and the drain region 340. The photocharge storage region 350 may be further included.

In the unit pixel 100 of FIG. 2, the collect gate 120 and the drain gate 130 are formed in an annular shape to cover a part of the photocharge storage region 150, but in the unit pixel 300a of FIG. 320 is annularly formed between the photocharge storage region 350 and the floating diffusion region 310, and the drain gate 330 is annularly formed between the photocharge storage region 350 and the drain region 340. Can be.

Referring to FIG. 11, the unit pixel 300a is disposed between the collect gate 320 and the drain gate 330 and is formed on the semiconductor substrate 10 to cover the photocharge storage region 350. ) May be further included. In this case, a constant bias voltage VB may be applied to the photo gate 370 to replace the pinning layer 270 of FIG. 8 and induce a similar potential distribution. The photo gate 370 to which the bias voltage VB is applied has a function of reducing dark current, and at the same time, reduces the influence of defects that may exist on the surface of the semiconductor substrate 10, thereby reducing photoelectric storage region ( 350 may serve to flatten the potential even more. At this time, if the doping concentration of the photocharge storage region 350 is further lowered, potentials of the drain gate 330 and the collect gate 320 may be more rapidly formed, and as a result, the horizontal movement of the photocharges may be promoted. have.

Compared to the unit pixel 300a of FIG. 11, the semiconductor substrate 10 of the unit pixel 300b of FIG. 12 includes a plurality of photocharge generating regions 11, in which impurities of the same conductivity type are doped to different concentrations. 13, 15).

For example, when the semiconductor substrate 10 is a P type conductivity type, the semiconductor substrate 10 may include the P region 11, the P− region 13, and the P + region 15 sequentially from above. . The P− region 13 shows a lower impurity concentration than the P region 11, and the P + region 15 shows a higher impurity concentration than the P region 11.

As described above, the photoelectrons generated near the boundary between the P- region 13 and the P + region 15 are located at the bottom of the P- region 13 by placing the P + region 15 having a higher impurity concentration. The tendency to move to the region NP junction portion is increased. As described above, by forming the plurality of photocharge generating regions 11, 13, and 15 on the semiconductor substrate 10, in which impurities are doped at different concentrations, the sensitivity of the unit pixel 300b may be further improved. .

13 through 17 are diagrams illustrating pixel arrays according to example embodiments.

Referring to FIG. 13, the pixel array 410 includes a plurality of unit pixels 412 arranged in a rectangular grid structure. The unit pixel 412 has an annular structure described with reference to FIGS. 1 to 12. Here, the rectangular lattice structure indicates that the four nearest unit pixels form a rectangle 415, and one unit pixel may be disposed for each grid point.

As such, when the plurality of unit pixels 412 are arranged in an array form, drain regions of unit pixels adjacent to each other are spatially connected to each other in a semiconductor substrate, so that the drain regions 417 of the plurality of unit pixels are integrally formed. It can be formed as. In this case, it can be seen that the outer boundary of the drain region exclusive to each unit pixel is not defined. As described above, in the pixel array using the unit pixel according to the exemplary embodiments of the present invention, since the integrated drain regions 417 perform an antiblooming function by themselves, a separate anti-blooming structure is not required. Can be.

In addition, the overall layout margin can be improved because all drain regions are substantially connected to each other and each unit pixel acts as a single-tap detector providing only one output.

Referring to FIG. 14, the pixel array 420 includes a plurality of unit pixels 412 arranged in a triangular lattice structure. The unit pixel 412 has an annular structure described with reference to FIGS. 1 to 12. The triangular lattice structure indicates that three adjacent unit pixels form a triangle 425, and one unit pixel may be disposed for each lattice point.

Referring to FIG. 15, the pixel array 430 includes a plurality of unit pixels 432 arranged in a rectangular grid structure. The unit pixel 432 has an annular structure described with reference to FIGS. 1 to 12. In particular, as shown in FIG. 15, each unit pixel 432 may have an octagonal annular structure.

Referring to FIG. 16, the pixel array 440 includes a plurality of unit pixels 442 arranged in a triangular lattice structure. The unit pixel 442 has an annular structure described with reference to FIGS. 1 to 12. In particular, as shown in FIG. 16, each unit pixel 442 may have a hexagonal annular structure.

As illustrated in FIGS. 13 to 16, it will be appreciated that the unit pixel according to the embodiments of the present invention may have a circular or arbitrary polygonal annular structure. Although not shown in the drawing, for example, the unit pixel may have a rectangular annular structure. In addition, the unit pixels having any annular structure may be arranged in a rectangular lattice structure to form a pixel array, or may be arranged in a triangular lattice structure to form a pixel array.

Referring to FIG. 17, the pixel array 450 includes a plurality of unit pixels 452 arranged in a triangular lattice structure. In one embodiment, floating diffusion regions of two or more unit pixels included in the pixel array may be electrically connected to each other to form a pixel group.

For example, as illustrated in FIG. 17, the floating diffusion regions of the seven unit pixels 452 may be electrically connected to each other to form one pixel group 451. 17 illustrates a structure in which such pixel groups 451 are regularly arranged. The electrical connection 453 of the floating diffusion regions may include interlayer connectors such as vias that electrically connect the floating diffusion regions and the upper metal layer, and wiring patterned to the metal layer. As such, by grouping the plurality of unit pixels, high sensitivity required by the TOF photosensitive device may be realized.

In one embodiment, unit pixels among the grid points of the grid structure may be regularly omitted. Regions in which the unit pixels are omitted may include a readout circuit for providing an output value of the unit pixel 452 or the pixel group 451. The read circuit may include transistors described later in FIG. 18. As such, the overall design margin of the pixel array 450 may be improved by grouping the plurality of unit pixels and efficiently providing an area for a read circuit.

18 is a diagram illustrating an example of a read circuit for providing an output value of a unit pixel.

Referring to FIG. 18, the output of the unit pixel 100 according to embodiments of the present invention may be converted into an electrical signal through the readout circuit 30 and provided to the outside. The unit pixel 100 has an annular structure as described above and operates as a single-tap detector. The floating diffusion region 110, the collect gate 120, the drain gate 130, the drain region 140, the gate voltages CG and DRG, and the drain voltage DR are as described above.

The read circuit 30 may include a source follower transistor T1, a select transistor T2, and a reset transistor T3. The reset transistor T3 initializes the voltage FD of the floating diffusion region 110 to the reset voltage VRST in response to the reset signal RST. The floating diffusion region 110 is connected to the gate of the source follower transistor T1. When the selection transistor T2 is turned on in response to the selection signal SEL after the collection of the photocharges is completed, a signal corresponding to the voltage FD of the floating diffusion region 110 is provided to the outside through the output line LO. .

As such, the voltage FD of the floating diffusion region 110 corresponding to the output value of the unit pixel 100 may be provided to the outside using the readout circuit 30 illustrated in FIG. 18. ) May be disposed in the region RDC in which the unit pixel of FIG. 17 is omitted. Meanwhile, the read circuit 30 may be disposed outside the pixel array.

19 is a block diagram illustrating a light sensing device according to embodiments of the present invention.

Referring to FIG. 19, the light sensing device 600 includes a sensing unit 610 and a control unit 630 for controlling the same. The sensing unit 610 includes at least one unit pixel that converts the reception light RX into an electrical signal DATA. The unit pixel includes a single-tap pixel having an annular structure described with reference to FIGS. 1 to 12. That is, as described above, the unit pixel may have a floating collector region 120 formed on the semiconductor substrate 10 to surround the floating diffusion region 110 and the floating diffusion region 110 formed in the semiconductor substrate 10. ), An annular drain gate 130 formed on the semiconductor substrate 10 to surround the collect gate 120, and a drain region 140 formed on the semiconductor substrate 10 to surround the drain gate 130. do.

The controller 630 may include a light source LS for generating the transmission light TX for irradiating the subject 60, an empty signal generator BN for generating the collect gate signal CG, and a drain gate signal DRG, and light. It may include a controller (CTRL) for controlling the overall operation of the sensing device 600.

The light source LS may output light having a predetermined wavelength (for example, infrared rays or near infrared rays). The transmission light TX generated by the light source LS may be focused on the subject 60 through the lens 51. The light source LS may be controlled by the controller CTRL to output the transmission light TX whose intensity changes periodically. For example, the transmission light TX may be a pulse train signal having successive pulses. The light source LS may be implemented as a light emitting diode (LED), a laser diode, or the like.

The empty signal generator BN generates the collect gate signal CG and the drain gate signal DRG for driving the annular unit pixel included in the sensing unit 610. The collect gate signal CG and the drain gate signal DRG may be signals that are complementarily activated. As described above, when the collect gate signal CG is activated, a channel is formed only in the semiconductor substrate 10 under the collect gate 120, that is, between the photocharge storage region 150 and the floating diffusion region 110. When the drain gate signal DRG is activated, a channel is formed only in the semiconductor substrate 10 under the drain gate 130, that is, between the photocharge storage region 150 and the drain region 140.

As a result, the photoelectric charges generated in the semiconductor substrate 10 while the collect gate signal CG is activated are collected into the floating diffusion region 110 and the photoelectric generated in the semiconductor substrate 10 while the drain gate signal DRG is activated. Is discharged to the drain region 140.

As will be described later, the collect gate signal CG may include a plurality of empty signals CGi having a cycle number that increases with a phase difference from the transmission light TX. Distance information may be obtained by converting the received light RX reflected by the subject 60 through the plurality of empty signals CGi and incident through the lens 53 into an electrical signal.

In one embodiment, the sensing unit 610 may include one unit pixel (or one pixel group) as described above, and may include an analog-to-digital converter (ADC) for converting the output of the unit pixel into a digital signal. It may include.

In another embodiment, the sensing unit 610 may include a pixel array PX in which a plurality of unit pixels (or a plurality of pixel groups) are arranged. In this case, the sensing unit 610 may include an analog-digital converter ADC and selection circuits ROW and COL for selecting a specific unit pixel in the pixel array PX.

According to an embodiment, the analog-to-digital converter ADC performs a column analog-to-digital conversion for converting analog signals in parallel using an analog-to-digital converter connected to each column line, or uses a single analog-to-digital converter. A single analog-to-digital conversion can be performed to sequentially convert the analog signals.

In some embodiments, the analog-to-digital converter ADC may include a correlated double sampling (CDS) unit for extracting an effective signal component.

In one embodiment, the CDS unit may perform analog double sampling to extract the valid signal component based on a difference between an analog reset signal representing a reset component and an analog data signal representing a signal component.

In another embodiment, the CDS unit converts the analog reset signal and the analog data signal into digital signals, and then performs digital double sampling to extract a difference between two digital signals as the effective signal component. can do.

In another embodiment, the CDS unit may perform dual correlation double sampling that performs both the analog double sampling and the digital double sampling.

20 is a flowchart illustrating a distance measuring method according to embodiments of the present invention.

19 and 20, first, the transmission light TX is irradiated onto the subject 60 using the light source LS (step S110). The sensing unit 610 may receive the received light RX that is reflected by the subject 60 and is incident on the electrical signal DATA using a plurality of empty signals having an increasing number of cycles according to the phase difference with the transmission light TX. To step S120. The plurality of empty signals may be included in gate signals CG and DRG generated by the empty signal generator BN. The collect gate signal CG including the variable plurality of empty signals and the drain gate signal DRG complementary thereto will be described later with reference to FIGS. 21 through 25. The controller CTRL calculates a distance to the subject 60 based on the electrical signal DATA provided from the sensing unit 610 (step S130).

21 is a timing diagram illustrating signals for converting received light into an electrical signal.

Referring to FIG. 21, the transmission light TX generated from the light source LS of the light sensing device 600 may be a pulse train signal including pulses at regular intervals To. The transmission light TX is reflected by the subject 60 positioned at a predetermined distance Z and is incident on the light sensing device 600 again as the reception light RX. When the speed of light is C and the phase difference between the transmission light TX and the reception light RX is Tf, the distance Z from the light sensing device 600 to the subject 60 is expressed by the equation Tf = It can be obtained from 2Z / C.

A plurality of empty signals may be used to obtain a phase difference Tf between the transmission light TX and the reception light RX. In FIG. 21, the phase difference with the transmission light TX is Ti and the period To One empty signal CGi is shown, wherein each activation time is Wi. The relationship between the plurality of empty signals will be described later with reference to FIGS. 22 and 23. For example, the empty signal CGi and the inverted empty signal DRGi which are inverted may be used as the gate signal of the unit pixel 100 described with reference to FIGS. 2 to 6.

The empty signal CGi may be applied to the collect gate 120 as the collect gate signal CG and the inverted empty signal DRGi may be applied to the drain gate 130 as the drain gate signal DRG. In this case, during the first time Tr, the generated photocharges are emitted to the drain region 140 among the time when the photocharges are generated in the semiconductor substrate 10 by the reception light RX, and during the second time Tc. The generated photocharges are collected into the floating diffusion region 110.

The emission and collection of the photocharges is repeated by the number of cycles of the empty signal CGi during the sensing time TS, and collected and accumulated in the floating diffusion region 110 during the read time TR after the sensing time TS. The amount is read out via the readout circuit 30 illustrated in FIG.

22 and 23 are timing diagrams for describing a plurality of empty signals used in the distance measuring method of FIG. 20.

Referring to FIG. 22, the variable plurality of empty signals CGi, i = 1, 2,... K have a cycle number ni that increases with a phase difference Ti with the transmission light TX. . The number of cycles n1 of the first empty signal CG1 having a zero phase difference from the transmission light is the smallest, and as the phase difference from the transmission light increases, the cycle number gradually increases, so that the phase difference from the transmission light is Tk, which is the largest. The number of cycles nk of the k-th empty signal CGk is largest. In other words, the first sensing time TS1 = To * n1 using the first empty signal CG1 is shortest and the kth sensing time TSk = To * nk using the kth empty signal CGk is longest.

Inversely proportional to the square of the distance Z as the distance Z between the light sensing device 600 and the subject 60 increases, that is, as the phase difference Tf between the transmission light TX and the reception light RX increases. The intensity of the received light RX decreases. Therefore, as described above, the distance Z to the subject 60 is increased by using the plurality of empty signals CGi having a cycle number ni that increases with the phase difference Ti with the transmission light TX. As it increases, the sensing time TSi may be increased to improve the signal-to-noise ratio SNR. In addition, by applying a gain depending on the distance Z, the dynamic range of the light sensing device may be increased.

In one embodiment, the plurality of empty signals CGi may be varied such that the duty ratio Wi / T0 is increased according to the phase difference Ti with the transmission light TX. That is, the activation time Wi for each period To of the plurality of empty signals CGi may be increased according to the phase difference Ti with the transmission light TX.

In general, as the distance Z to the subject 60 increases, the need for accuracy of the distance Z may be lowered. In this case, as the distance Z increases, the gain may be increased by increasing the activation time Wi of the empty signals CGi, thereby improving the signal-to-noise ratio.

The plurality of empty signals CGi illustrated in FIG. 22 may be signals applied to different unit pixels. For example, in a pixel array in which a plurality of unit pixels are arranged in a matrix of rows and columns, the same empty signal is applied to unit pixels belonging to the same row, and different empty signals are applied to unit pixels belonging to different rows. Can be applied. In this case, a read time TR for a read operation may be given immediately after each sensing time TS1, and an efficient rolling frame operation may be implemented in the image sensor.

FIG. 23 is a timing diagram when a plurality of empty signals CGi are applied to one unit pixel. In FIG. 23, only the waveforms of the two empty signals CG2 and CGk are enlarged for convenience, but the waveforms of the remaining empty signals are the same as those described with reference to FIG. 22. That is, the plurality of variable empty signals CGi, i = 1, 2, ... k have a cycle number ni that increases with the phase difference Ti with the transmission light TX, and consequently the transmission The first sensing time TS1 = To * n1 using the first empty signal CG1 having the smallest phase difference T1 with the light TX is the shortest and the phase difference Tk with the transmission light TX is the largest. The k-th sensing time TSk = To * nk using the k-th empty signal CGk is the longest. In addition, as described above, the plurality of empty signals CGi may be varied so that the duty ratio Wi / T0 is increased according to the phase difference Ti with the transmission light TX. When the plurality of empty signals CGi are sequentially applied to one unit pixel, each read time TR is given after each sensing time TSi.

FIG. 24 is a diagram illustrating an example of variable bin signals, and FIG. 25 is a diagram illustrating an example of a phase, an length of an activation interval, and a cycle number of bin signals of FIG. 24.

Referring to FIG. 24, a plurality of variable empty signals CGi, i = 1, 2, ..., 10 for measuring the phase difference Tf between the transmission light TX and the reception light RX are illustrated. It is.

For example, when a 3D image sensor providing distance information together with moving image information operates at 30 fps, a pulse train signal including 30 million optical pulses per second at 20% duty ratio may be used. Can be. In this case, when ignoring the read time, the number of cycles of the transmission light TX corresponding to one frame is one million. The width of each bin signal CGi shown in FIG. 24 represents an activation time Wi. As illustrated in FIG. 24, activation times of adjacent empty signals may overlap each other.

For example, a 50% of the rear portion of the activation time W2 of the second empty signal CG2 overlaps with the activation time W3 of the third empty signal CG3, and the activation time of the third empty signal CG3 may be W3) may be increased by 10% than the activation time W2 of the second empty signal CG2. The phase difference Ti, the activation time Wi, and the cycle number ni of each of the empty signals CGi determined as described above with the transmission light TX are summarized in FIG. 25. In FIG. 25, M represents the sum of all cycle numbers ni.

In this way, photocharges may be collected using the variable bin signals CGi, and the distance Z to the subject may be calculated by combining the amount of collected photocharges with the phase of the bin signals CGi.

26 is a flowchart illustrating a distance measuring method according to embodiments of the present invention.

19 and 26, first, the transmission light TX is irradiated onto the subject 60 using the light source LS (step S210). Using the variable empty signals, the sensing unit 610 converts the received light RX reflected by the subject 60 into an electrical signal DATA (step S220). As described above, the variable empty signals may have a cycle number that increases with a phase difference from the transmission light TX. In addition, the duty ratio of the variable empty signals may increase according to a phase difference from the transmission light TX. The controller CTRL calculates a distance to the subject 60 based on the electrical signal DATA provided from the sensing unit 610 (step S230). The controller CTRL controls the empty signal generator BN to adjust the phase and duty ratio of the empty signals so as to focus on the phase corresponding to the calculated distance (step S240). The distance to the subject is corrected using a plurality of empty signals whose phase and duty ratio are adjusted (step S250).

FIG. 27 is a diagram illustrating an example of variable bin signals, FIG. 28 is a diagram illustrating an example of a phase, an length of an activation interval, and a cycle number of bin signals of FIG. 27, and FIG. 29 is an example of corrected bin signals. It is a figure which shows.

Referring to FIG. 27, four variable empty signals CGi, i = 1, 2, 3, and 4 for measuring the phase difference Tf between the transmission light TX and the reception light RX are illustrated. . In FIG. 27, an example of the reception light RX reflected and incident by the subject when the transmission light TX having a duty ratio of 50% is used is indicated by a dotted line. 28 illustrates the phase difference Ti, the activation time Wi, and the cycle number ni of the four empty signals CGi with the transmission light TX. As shown in FIGS. 27 and 28, the four empty signals CGi have the same activation time Wi but have a cycle number ni that increases with the phase difference Ti with the transmission light TX. Can be.

The controller CTRL calculates the distance to the subject 60 based on the electrical signal DATA provided from the sensing unit 610 using the empty signals CGi, and controls the empty signal generator BN. The phase and duty ratios of the empty signals CGi are adjusted to be focused on the phase corresponding to the calculated distance. An example of the corrected empty signals CGi ′ is shown in FIG. 29.

As shown in FIG. 29, more accurate data can be obtained using the empty signals CGi ′ which are adjusted to focus on the pulse of the reception light RX, and the distance Z to the subject can be corrected precisely. have. For example, in the case of a face recognition security system, the average distance to the face is measured using the empty signals CGi as shown in FIGS. 27 and 28, and the empty signal of FIG. 29 corrected based on the result. You can use CGi 'to rescan around the average distance to get a more precise distance.

30 is a block diagram illustrating a sensing unit of a 3D image sensor according to an exemplary embodiment. 30 illustrates an example of the sensing unit 610a when the light sensing device 600 of FIG. 19 is a 3D image sensor.

Referring to FIG. 30, the sensing unit 610a includes a pixel array C / Z PX in which a plurality of color pixels and a plurality of distance pixels are arranged, a color pixel selection circuit CROW and CCOL, and a distance pixel selection circuit ZROW. , ZCOL), a color pixel converter (CADC), and a distance pixel converter (ZADC). The color pixel selection circuits CROW and CCOL and the color pixel converter CADC control the color pixels in the pixel array C / Z PX to provide image information CDATA and the distance pixel selection circuits ZROW and ZCOL. The distance pixel converter ZADC controls distance pixels in the pixel array C / Z PX to provide distance information ZDATA.

As such, in the 3D image sensor, components for controlling the color pixels and components for controlling the distance pixels are separately provided to provide the color data CDATA and the distance data ZDATA of the image. have.

FIG. 31 is a diagram illustrating an example of a pixel array included in the sensing unit of FIG. 30.

Referring to FIG. 31, the pixel array C / Z PX includes a plurality of unit pixels R, G, B, and Z arranged in a triangular lattice structure. The unit pixels R, G, B, and Z have an annular structure described with reference to FIGS. 2 through 12. The unit pixels R, G, B, and Z include color pixels R, G, and B, and a plurality of distance pixels Z. The color pixels may include a green pixel G, a red pixel R, and a blue pixel B. As shown in FIG. 31, the color pixels R, G, and B perform independent light sensing functions for each unit pixel in order to increase the resolution, and the distance pixels Z are used to increase the sensitivity. The unit pixels may form a pixel group 80 that operates integrally. For example, as described above, the floating diffusion regions of the four distance pixels Z belonging to one pixel group 80 may be electrically connected to each other.

The color pixel selection circuits CROW and CCOL and the color pixel converter CADC of FIG. 30 are responsible for sensing and reading operations of the color pixels R, G and B, and the distance pixel selection circuits ZROW and ZCOL. The distance pixel converter ZADC may be in charge of sensing and reading the distance pixels Z. The variable plurality of empty signals CGi described above may be applied to the gate of the distance pixel Z to obtain data ZDATA representing distance information. The color pixels R, G, and B may operate at a frequency different from that of the distance pixel Z, and may operate in response to a gate signal different from the above-described empty signals CGi.

32 is a block diagram illustrating an example in which a 3D image sensor is applied to a camera, according to an exemplary embodiment.

Referring to FIG. 32, the camera 800 may include a light receiving lens 810, a 3D image sensor 900, and an engine unit 840. The 3D image sensor 900 may include a 3D image sensor chip 820 and a light source module 830. In some embodiments, the 3D image sensor chip 820 and the light source module 830 may be implemented as separate devices, or at least some components of the light source module 830 may be included in the 3D image sensor chip 820. Can be implemented. Also, the light receiving lens 810 may be included as some component of the 3D image sensor 900.

The light receiving lens 810 may focus incident light into a light receiving region (eg, distance pixels and / or color pixels included in the pixel array 110 of FIG. 1) of the 3D image sensor chip 820. . The 3D image sensor chip 820 may generate data DATA1 including distance information and / or color image information based on light incident through the light receiving lens 810. For example, the data DATA1 generated by the 3D image sensor chip 820 may include distance data generated by using infrared or near infrared rays emitted from the light source module 830, and Bayer pattern generated by using external visible light. It may include RGB data. The 3D image sensor chip 820 may provide the data DATA1 to the engine unit 840 based on the clock signal CLK. According to an embodiment, the 3D image sensor chip 820 may interface with the engine unit 840 through a mobile industry processor interface (MIPI) and / or a camera serial interface (CSI).

The engine unit 840 controls the 3D image sensor 900. In addition, the engine unit 840 may process data DATA1 received from the 3D image sensor chip 820. For example, the engine unit 840 may generate stereoscopic color data based on the data DATA1 received from the 3D image sensor chip 820. In another example, the engine unit 840 generates YUV data including a luminance component, a difference between the luminance component and a blue component, and a difference between the luminance component and a red component based on the RGB data included in the data DATA1. Or compressed data, for example, Joint Photography Experts Group (JPEG) data. The engine unit 840 may be connected to the host / application 850, and the engine unit 840 may provide data DATA2 to the host / application 850 based on the master clock MCLK. In addition, the engine unit 840 may interface with the host / application 850 through a Serial Peripheral Interface (SPI) and / or an Inter Integrated Circuit (I2C).

33 is a block diagram illustrating an example in which a 3D image sensor is applied to a computing system according to an exemplary embodiment.

Referring to FIG. 33, the computing system 1000 includes a processor 1010, a memory device 1020, a storage device 1030, an input / output device 1040, a power supply 1050, and a three-dimensional image sensor 900. can do. Although not shown in FIG. 33, the computing system 1000 may further include ports for communicating with a video card, a sound card, a memory card, a USB device, or the like, or communicating with other electronic devices. .

Processor 1010 may perform certain calculations or tasks. According to an embodiment, the processor 1010 may be a micro-processor, a central processing unit (CPU). The processor 1010 may communicate with the memory device 1020, the storage device 1030, and the input / output device 1040 through an address bus, a control bus, and a data bus. have. In some embodiments, the processor 1010 may also be connected to an expansion bus, such as a Peripheral Component Interconnect (PCI) bus. The memory device 1020 may store data necessary for the operation of the computing system 1000. For example, the memory device 1020 may be embodied as DRAM, mobile DRAM, SRAM, PRAM, FRAM, RRAM, and / or MRAM. have. The storage device 1030 may include a solid state drive, a hard disk drive, a CD-ROM, and the like. The input / output device 1040 may include input means such as a keyboard, a keypad, a mouse, and the like, and output means such as a printer or a display. The power supply 1050 can supply the operating voltage required for operation of the electronic device 1000. [

The 3D image sensor 900 may be connected to the processor 1010 through the buses or other communication links to perform communication. As described above, the 3D image sensor 900 may include a unit pixel having an annular structure used as a single-tap detector. In addition, the 3D image sensor 900 may use a plurality of variable empty signals as described above to measure the distance to the subject. This improves light sensitivity and improves signal-to-noise ratio. The 3D image sensor 900 may be integrated on one chip together with the processor 1010 or may be integrated on different chips, respectively.

The 3D image sensor 900 may be implemented in various types of packages. For example, at least some components of the three-dimensional image sensor 900 may be packaged on packages (PoP), ball grid arrays (BGAs), chip scale packages (CSPs), plastic leaded chip carriers (PLCC), plastic dual in- Line Package (PDIP), Die in Waffle Pack, Die in Wafer Form, Chip On Board (COB), Ceramic Dual In-Line Package (CERDIP), Plastic Metric Quad Flat Pack (MQFP), Thin Quad Flatpack (TQFP), Small Outline (SOIC), Shrink Small Outline Package (SSOP), Thin Small Outline (TSOP), Thin Quad Flatpack (TQFP), System In Package (SIP), Multi Chip Package (MCP), Wafer-level Fabricated Package (WFP), It can be implemented using packages such as Wafer-Level Processed Stack Package (WSP).

Meanwhile, the computing system 1000 should be interpreted as any computing system using a 3D image sensor. For example, the computing system 1000 may include a digital camera, a mobile phone, a personal digital assistant (PDA), a portable multimedia player (PMP), a smartphone, or the like.

FIG. 34 is a block diagram illustrating an example of an interface used in the computing system of FIG. 33.

Referring to FIG. 34, the computing system 1100 may be implemented as a data processing apparatus capable of using or supporting a MIPI interface, and includes an application processor 1110, a 3D image sensor 1140, a display 1150, and the like. can do. The CSI host 1112 of the application processor 1110 may perform serial communication with the CSI device 1141 of the 3D image sensor 1140 through a camera serial interface (CSI). In one embodiment, the CSI host 1112 may include a deserializer DES, and the CSI device 1141 may include a serializer SER. The DSI host 1111 of the application processor 1110 may perform serial communication with the DSI device 1151 of the display 1150 through a display serial interface (DSI).

In one embodiment, the DSI host 1111 may include a serializer (SER), and the DSI device 1151 may include a deserializer (DES). In addition, the computing system 1100 may further include a Radio Frequency (RF) chip 1160 that may communicate with the application processor 1110. The PHY 1113 of the computing system 1100 and the PHY 1161 of the RF chip 1160 may perform data transmission / reception in accordance with Mobile Industry Processor Interface (MIPI) DigRF. In addition, the application processor 1110 may further include a DigRF MASTER 1114 for controlling data transmission and reception according to the MIPI DigRF of the PHY 1161.

The computing system 1100 may include a Global Positioning System (GPS) 1120, a storage 1170, a microphone 1180, a dynamic random access memory (DRAM) 1185, and a speaker 1190. Can be. In addition, the computing system 1100 utilizes an ultra wideband (UWB) 1210, a wireless local area network (WLAN) 1220, a worldwide interoperability for microwave access (WIMAX) 1230, and the like. Communication can be performed. However, the structure and interface of the computing system 1100 is one example and is not limited thereto.

The unit pixel and the distance measuring method of the annular structure according to the embodiments of the present invention can be used in any light sensing device for providing distance information, in particular a three-dimensional image that provides both the image information and the distance information of the subject It can be usefully used for the sensor. The present invention is also useful for face recognition security systems, computers, digital cameras, 3D cameras, mobile phones, PDAs, scanners, car navigation systems, video phones, surveillance systems, auto focus systems, tracking systems, motion detection systems, image stabilization systems, and the like. Can be used.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it will be understood by those skilled in the art that various changes and modifications may be made therein without departing from the spirit and scope of the invention as defined in the appended claims. You will understand.

100, 200, 300: unit pixels
110, 210, 310: floating diffusion region
120, 220, 320: Collect gate
130, 230, 330: drain gate
140, 240, 340: drain region
150, 250, 350: photocharge storage area
270: pinning layer
370: photogate

Claims (13)

A floating diffusion region formed on the semiconductor substrate;
An annular collect gate formed on the semiconductor substrate to surround the floating diffusion region;
An annular drain gate formed over the semiconductor substrate to surround the collect gate; And
And a drain region formed in the semiconductor substrate to surround the drain gate. The method according to claim 1,
Complementaryly activated collector and drain gate signals are applied to the collector gate and the drain gate, respectively, so that photocharges generated in the semiconductor substrate are collected into the floating diffusion region while the collector gate signal is activated. The unit pixel of the photosensitive device, wherein the photocharge generated in the semiconductor substrate is emitted to the drain region while a gate signal is activated. The method according to claim 1,
And a photocharge storage region that is doped with impurities of an opposite conductivity type to the semiconductor substrate and is formed in an annular shape in the semiconductor substrate between the floating diffusion region and the drain region. The method of claim 3,
The collect gate is formed in an annular shape to cover an inner portion of the photocharge storage region,
And the drain gate is formed in an annular shape to cover an outer portion of the photocharge storage region. The method of claim 3,
The collect gate is formed annularly between the photocharge storage region and the floating diffusion region,
The drain gate is a unit pixel of the photosensitive device, characterized in that formed in the annular between the photocharge storage region and the drain region. The method of claim 5,
And a pinning layer annularly formed on the semiconductor substrate to be doped with impurities of an opposite conductivity type to the photocharge storage region to cover the photocharge storage region. The method of claim 5,
And an annular photo gate formed between the collector gate and the drain gate to cover the photocharge storage region, the annular photo gate being formed on the semiconductor substrate. A sensing unit including at least one unit pixel to convert received light into an electrical signal; And
A control unit for controlling the sensing unit,
The unit pixel is,
A floating diffusion region formed on the semiconductor substrate;
An annular collect gate formed on the semiconductor substrate to surround the floating diffusion region;
An annular drain gate formed over the semiconductor substrate to surround the collect gate; And
And a drain region formed in the semiconductor substrate to surround the drain gate. The method of claim 8,
The sensing unit includes a pixel array in which the plurality of unit pixels are arranged in a rectangular lattice structure or a triangular lattice structure.
And the drain regions of the unit pixels adjacent to each other are spatially connected to each other in the semiconductor substrate so that the drain regions of the plurality of unit pixels are integrally formed. 10. The method of claim 9,
The unit pixels are regularly omitted among the grid points of the grid structure,
And a readout circuit formed in an area in which the unit pixels are omitted to provide an output value of the unit pixels. Irradiating transmission light onto a subject;
Converting received light reflected and incident by the subject into an electrical signal using a plurality of empty signals having a number of cycles increasing with a phase difference from the transmitted light; And
And calculating a distance to the subject based on the electrical signal. The method of claim 11, wherein
And the duty ratio of the plurality of empty signals increases in accordance with a phase difference from the transmitted light. The method of claim 11, wherein
Adjusting phase and duty ratios of the plurality of empty signals to be concentrated in a phase corresponding to the calculated distance; And
And correcting a distance to the subject by using the plurality of empty signals whose phase and duty ratio are adjusted.

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