Pixel array of autofocus image sensor and autofocus image sensor including same

Abstract

To provide a pixel array included in an auto-focus image sensor, capable of having improved full well capacity (FWC) characteristics.SOLUTION: A pixel array included in an auto-focus image sensor includes a substrate 101, a plurality of pixels, a deep device isolation part 110 and a plurality of first ground regions 115. The substrate includes: a first surface 101a on which a gate electrode is disposed; and a second surface 101b opposite to the first surface. The plurality of pixels are disposed in the substrate, and include a plurality of AF pixels 21R, 21L used to detect a phase difference and a plurality of general pixels 23 used to detect an image. The deep device isolation part is disposed in the substrate, extends vertically from the second surface of the substrate to isolate the plurality of pixels from each other, and is not in direct contact with the first surface of the substrate. The plurality of first ground regions are disposed adjacent to the first surface in the substrate and adjacent to only at least some of the plurality of first pixels.SELECTED DRAWING: Figure 7

Description

[Technical field]

[0001] The present invention relates to an image sensor, and more particularly to a pixel array included in an autofocus image sensor and an autofocus image sensor including the pixel array. [Background technology]

[0002] A CMOS (complementary metal-oxide semiconductor) image sensor is an image pickup device manufactured using a CMOS process. The CMOS image sensor has advantages of lower manufacturing costs, smaller pixel size, and lower power consumption compared to a CCD (charge-coupled device) image sensor that includes a high-voltage analog circuit. As the performance of CMOS image sensors improves, CMOS image sensors are widely used in mobile electronic devices such as smartphones, tablet PCs, and digital cameras.

[0003] Recently, an automatic focus adjustment function has been provided in digital image pickup devices such as cameras, and in order to realize this function, it is necessary to detect the focus adjustment state of the photographing lens. If a focus detection element is included separately from the image sensor for the automatic focus adjustment function, the cost of manufacturing the digital image pickup device may increase or the size of the entire device may become large. Therefore, an autofocus image sensor that can perform both the image pickup function and the automatic focus adjustment function is being researched. Summary of the Invention [Problem to be solved by the invention]

[0004] An object of the present invention is to provide a pixel array of an autofocus image sensor capable of improving FWC (Full Well Capacity) characteristics.

[0005] Another object of the present invention is to provide an autofocus image sensor including the pixel array, which can improve FWC characteristics. [Means for solving the problem]

[0006] In order to achieve the object, a pixel array of an autofocus image sensor according to an embodiment of the present invention includes a substrate, a plurality of pixels, a deep isolation portion, and a plurality of first ground regions. The substrate includes a first surface on which a gate electrode is disposed and a second surface opposite to the first surface. The plurality of pixels are disposed within the substrate and include a plurality of first pixels used to detect a phase difference and a plurality of second pixels used to detect an image. The deep isolation portion is disposed within the substrate and extends vertically from the second surface of the substrate to separate each of the plurality of pixels from each other and does not directly contact the first surface of the substrate. The plurality of first ground regions are disposed within the substrate adjacent to the first surface and adjacent to at least some of the plurality of first pixels.

[0007] In order to achieve the other object, an autofocus image sensor according to an embodiment of the present invention includes a pixel array and a plurality of column driving circuits. The pixel array detects incident light and generates a plurality of analog pixel signals representing phase difference information and image information. The plurality of column driving circuits are connected to a plurality of columns of the pixel array and convert the plurality of analog pixel signals into a plurality of digital signals. The pixel array includes a substrate, a plurality of pixels, a deep device isolation portion, and a plurality of first ground regions. The substrate includes a first surface on which a gate electrode is disposed and a second surface opposite to the first surface. The plurality of pixels are disposed within the substrate and include a plurality of first pixels used to detect a phase difference and a plurality of second pixels used to detect an image. The deep device isolation portion is disposed within the substrate and extends vertically from the second surface of the substrate to separate each of the plurality of pixels from each other, and does not directly contact the first surface of the substrate. The plurality of first ground regions are disposed within the substrate to be adjacent to the first surface and to be adjacent to at least some of the plurality of first pixels.

[0008] In order to achieve the object, a pixel array of an autofocus image sensor according to an embodiment of the present invention includes a substrate, a plurality of pixels, a deep isolation portion, and a plurality of ground regions. The substrate includes a first surface on which a gate electrode is disposed and a second surface opposite to the first surface. The plurality of pixels are disposed within the substrate and are used to detect a phase difference and detect an image. The deep isolation portion is disposed within the substrate and extends vertically from the second surface of the substrate to separate each of the plurality of pixels from each other and does not directly contact the first surface of the substrate. The plurality of ground regions are disposed within the substrate adjacent to the first surface and adjacent to at least some of the plurality of pixels. Effect of the Invention

[0009] In the pixel array of the autofocus image sensor according to the embodiment of the present invention, a first pixel for acquiring AF information and a second pixel for acquiring an image may be arranged in one pixel array, and a first ground region for improving dark current may be arranged only in the first pixel and not in the second pixel. As a result, even if the pixel size is reduced, the photoelectric conversion unit included in the second pixel may be expanded, and therefore the FWC characteristics may be improved.

[0010] Embodiments of the present invention may be applicable to cases where a first ground area is arranged only in a portion of a first pixel and where a second ground area is additionally arranged in a portion of a second pixel, and may also be applicable to cases where one pixel acquires both AF information and image information. [Brief description of the drawings]

[0011] [Figure 1] FIG. 2 is a plan view illustrating a pixel array of an autofocus image sensor according to an embodiment of the present invention. [Diagram 2] 2 is a plan view showing a schematic layout of a portion of a pixel array of the autofocus image sensor of FIG. 1; [Diagram 3] 3, 4a, and 4b are diagrams illustrating an example of performing autofocus using an autofocus image sensor according to an embodiment of the present invention. [Figure 4a] 3, 4a, and 4b are diagrams illustrating an example of performing autofocus using an autofocus image sensor according to an embodiment of the present invention. [Figure 4b] 3, 4a, and 4b are diagrams illustrating an example of performing autofocus using an autofocus image sensor according to an embodiment of the present invention. [Diagram 5] FIG. 2 is a circuit diagram illustrating an example of a pixel included in a pixel array of an autofocus image sensor according to an embodiment of the present invention. [Figure 6] 2 is a plan view showing the layout of the bottom of a portion of a pixel array of the autofocus image sensor of FIG. 1. FIG. [Figure 7] 7 is a cross-sectional view showing an example of a pixel array of the autofocus image sensor of FIG. 6 cut along line A-A'. [Figure 8a] 8a, 8b, 8c, 8d, 8e, and 8f are cross-sectional views illustrating a method for manufacturing the pixel array of the autofocus image sensor of FIGS. [Figure 8b] 8a, 8b, 8c, 8d, 8e, and 8f are cross-sectional views illustrating a method for manufacturing the pixel array of the autofocus image sensor of FIGS. [Figure 8c] 8a, 8b, 8c, 8d, 8e, and 8f are cross-sectional views illustrating a method for manufacturing the pixel array of the autofocus image sensor of FIGS. [Figure 8d] 8a, 8b, 8c, 8d, 8e, and 8f are cross-sectional views illustrating a method for manufacturing the pixel array of the autofocus image sensor of FIGS. [Figure 8e] 8a, 8b, 8c, 8d, 8e, and 8f are cross-sectional views illustrating a method for manufacturing the pixel array of the autofocus image sensor of FIGS. [Figure 8f] 8a, 8b, 8c, 8d, 8e, and 8f are cross-sectional views illustrating a method for manufacturing the pixel array of the autofocus image sensor of FIGS. [Figure 9] 9, 10, 11, 12, 13, 14, and 15 are cross-sectional views showing other examples of the pixel array of the autofocus image sensor of FIG. 6 taken along line A-A'. [Figure 10] 9, 10, 11, 12, 13, 14, and 15 are cross-sectional views showing other examples of the pixel array of the autofocus image sensor of FIG. 6 taken along line A-A'. [Figure 11] 9, 10, 11, 12, 13, 14, and 15 are cross-sectional views showing other examples of the pixel array of the autofocus image sensor of FIG. 6 taken along line A-A'. [Figure 12]9, 10, 11, 12, 13, 14, and 15 are cross-sectional views showing other examples of the pixel array of the autofocus image sensor of FIG. 6 taken along line A-A'. [Figure 13] 9, 10, 11, 12, 13, 14, and 15 are cross-sectional views showing other examples of the pixel array of the autofocus image sensor of FIG. 6 taken along line A-A'. [Figure 14] 9, 10, 11, 12, 13, 14, and 15 are cross-sectional views showing other examples of the pixel array of the autofocus image sensor of FIG. 6 taken along line A-A'. [Figure 15] 9, 10, 11, 12, 13, 14, and 15 are cross-sectional views showing other examples of the pixel array of the autofocus image sensor of FIG. 6 taken along line A-A'. [Figure 16] FIG. 2 is a plan view illustrating a pixel array of an autofocus image sensor according to an embodiment of the present invention. [Figure 17] FIG. 17 is a plan view showing a schematic layout of a portion of a pixel array of the autofocus image sensor of FIG. 16. [Figure 18] FIG. 2 is a plan view illustrating a pixel array of an autofocus image sensor according to an embodiment of the present invention. [Figure 19] 19 is a cross-sectional view showing an example of a pixel array of the autofocus image sensor of FIG. 18. [Figure 20] FIG. 2 is a plan view illustrating a pixel array of an autofocus image sensor according to an embodiment of the present invention. [Figure 21] 21 and 22 are cross-sectional views illustrating an example of a pixel array of the autofocus image sensor of FIG. [Figure 22] 21 and 22 are cross-sectional views illustrating an example of a pixel array of the autofocus image sensor of FIG. [Figure 23] FIG. 2 is a plan view illustrating a pixel array of an autofocus image sensor according to an embodiment of the present invention. [Figure 24] FIG. 24 is a cross-sectional view showing an example of a pixel array of the autofocus image sensor of FIG. 23. [Diagram 25] FIG. 2 is a plan view illustrating a pixel array of an autofocus image sensor according to an embodiment of the present invention. [Figure 26] FIG. 4 is a circuit diagram illustrating another example of a pixel included in a pixel array of an autofocus image sensor according to an embodiment of the present invention. [Figure 27] FIG. 26 is a cross-sectional view showing an example of a pixel array of the autofocus image sensor of FIG. 25. [Figure 28] FIG. 2 is a plan view illustrating a pixel array of an autofocus image sensor according to an embodiment of the present invention. [Figure 29] FIG. 29 is a plan view showing a schematic layout of a portion of a pixel array of the autofocus image sensor of FIG. 28. [Diagram 30] FIG. 29 is a cross-sectional view showing an example of a pixel array of the autofocus image sensor of FIG. 28. [Diagram 31] 2 is a cross-sectional view illustrating an example pixel array of an autofocus image sensor according to an embodiment of the present invention. [Diagram 32] FIG. 2 is a block diagram illustrating an autofocus image sensor in accordance with an embodiment of the present invention. [Diagram 33] FIG. 1 is a block diagram illustrating an electronic system including an autofocus image sensor according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. The same reference numerals are used to refer to the same elements in the drawings, and duplicated descriptions of the same elements will be omitted.

[0013] FIG. 1 is a plan view showing a pixel array of an autofocus image sensor according to an embodiment of the present invention.

[0014] Referring to FIG. 1, a pixel array 100 of an auto-focus image sensor includes a plurality of pixels and a plurality of first ground regions GR1.

[0015] The plurality of pixels include a plurality of first pixels AFP and a plurality of second pixels NP. The plurality of first pixels AFP are used to detect a phase difference and can be called auto-focus (AF) pixels. The plurality of second pixels NP are used to detect an image and can be called normal pixels. In an embodiment of the present invention, the pixels AFP for acquiring AF information and the normal pixels NP can be arranged in one pixel array 100.

[0016] As will be described below with reference to, for example, FIG. 7, the plurality of pixels are disposed within a substrate, and pixel array 100 includes deep isolation portions that separate each of the plurality of pixels from one another.

[0017] The first ground regions GR1 are arranged to be adjacent to at least some of the first pixel AFPs. In the embodiment of FIG. 1, the number of the first ground regions GR1 is the same as the number of the first pixel AFPs, and the first ground regions GR1 may be arranged to be adjacent to all of the first pixel AFPs. In other words, each of the first pixel AFPs may include one of the first ground regions GR1. A reference voltage (e.g., a ground voltage) may be applied to the first ground regions GR1 to reduce dark current.

[0018] In one embodiment, the plurality of first ground regions GR1 may be uniformly and regularly arranged across the pixel array 100.

[0019] The pixels may be divided into a plurality of pixel groups PG, each of which includes a portion of the plurality of first pixels AFP and a portion of the plurality of second pixels NP. The pixel groups PG may be repeatedly arranged along a first direction (DR1) and a second direction (DR2) that intersect (e.g., perpendicular to) each other. Each of the pixel groups PG may include the same number of first pixels AFP.

[0020] In FIG. 1, one pixel group PG is illustrated as including 4*4 pixels, and in particular including two first pixels AFP and 14 second pixels NP, but the present invention is not limited to this and the structure of the pixel group may be changed depending on the embodiment.

[0021] The pixel array 100 of the autofocus image sensor according to the embodiment of the present invention has a structure in which a first pixel AFP for acquiring AF information and a second pixel NP for acquiring an image are arranged in one pixel array 100, and a first ground region GR1 for improving dark current is arranged only in the first pixel AFP and not in the second pixel NP. As a result, even if the pixel size shrinks, the photoelectric conversion unit included in the second pixel NP can be expanded, and therefore, the FWC (Full Well Capacity) characteristic can be improved.

[0022] Fig. 2 is a plan view showing a schematic layout of a portion of a pixel array of the autofocus image sensor of Fig. 1. For ease of illustration, Fig. 2 shows the layout of one pixel group PG included in the pixel array 100 of Fig. 1.

[0023] 1 and 2, a pixel array 100 of an autofocus image sensor may include a focus detection area 11 and an image detection area 13. The focus detection area 11 may include a first AF pixel 21R and a second AF pixel 21L adjacent to each other and used for detecting a phase difference. The image detection area 13 may include a general pixel 23 used for detecting an image.

[0024] A color filter array including a plurality of color filters may be disposed on the focus detection area 11 and the image detection area 13. For example, the color filter array may be a Bayer pattern array including R (red), G (green), and B (blue). However, the present invention is not limited thereto, and the color filter array may adopt a complementary color system (e.g., a system using magenta, cyan, and yellow) or may further include a W (white or transparent) filter. The color filters disposed on the AF pixels 21R and 21L are not used to realize colors, but may be disposed on the AF pixels 21R and 21L simply for the convenience of a manufacturing process of the color filter array. A microlens array including a plurality of microlenses 35 may be disposed on the color filter array.

[0025] Meanwhile, although not shown, the color filters disposed on the AF pixels 21R and 21L of the focus detection area 11 according to the embodiment may be omitted.

[0026] A light-shielding pattern for controlling the amount of light received by at least the AF pixels 21R and 21L may be disposed under the color filters. Accordingly, the light-shielding pattern may include a plurality of first openings 31 formed on the AF pixels 21R and 21L. The light-shielding pattern may further include a plurality of second openings 33 formed on the general pixels 23. The area of ​​the first openings 31 may be smaller than the area of ​​the second openings 33. For example, the area of ​​the first openings 31 may be about 50% of the area of ​​the second openings 33, and the first openings 31 may be disposed biased to one side with respect to a light axis into which light is incident. The first openings 31 of the adjacent first and second AF pixels 21R and 21L may be disposed symmetrically to each other. The first openings 31 of the light-shielding pattern serve to adjust the amount of light incident on the AF pixels 21R and 21L to be smaller than the amount of light incident on the general pixels 23.

[0027] 3, 4a, and 4b are diagrams illustrating an example of performing autofocus using an autofocus image sensor according to an embodiment of the present invention.

[0028] 3, 4a, and 4b, incident light passing through a lens 51 of an image capturing device (or an image processing device) passes through a microlens array 54 including a plurality of microlenses (e.g., the microlens 35 in FIG. 2) and is directed to a first AF pixel R and a second AF pixel L. A mask or limited opening 57, 58 (e.g., the first opening 31 in FIG. 2) is provided in a part of the first AF pixel R and the second AF pixel L to limit light entering from the pupils 52, 53 of the lens 51. Among the pupils of the lens 51, light from the pupil 52 located above the optical axis 50 of the lens 51 is directed to the second AF pixel L, and light from the pupil 53 located below the optical axis 50 of the lens 51 is directed to the first AF pixel R. The AF pixels R and L receiving light within a range that is back-projected at the positions of the pupils 52 and 53 through the mask or opening 57, 58 by the microlens array 54 is called pupil division.

[0029] If the array of the first AF pixel R and the second AF pixel L is drawn along the microlens array 54 as a continuous output of the pupil-divided pixel output, it will be as shown in FIG. 4a and FIG. 4b. In FIG. 4a and FIG. 4b, the horizontal axis is the position of the first AF pixel R and the second AF pixel L, and the vertical axis is the output value of the first AF pixel R and the second AF pixel L. Looking at the output values ​​of the first AF pixel R and the second AF pixel L, it can be seen that they have the same shape. However, the positions, i.e., the phases, are different from each other. This is because the image formation positions of the light from the decentered pupils 52 and 53 of the photographing lens 51 are different. Therefore, when the focus is not achieved, the phases are shifted as shown in FIG. 4a, and when the focus is achieved, the images are formed at the same position as shown in FIG. 4b. From this, the direction of the focus difference can also be determined. When the focus is on a point in front of the object, this is called front-focusing, and in this case, the phase of the output value of the first AF pixel R shifts to the left from the focused state phase, and the phase of the output value of the second AF pixel L shifts to the right from the focused state phase. Conversely, when the focus is on a point behind the object, this is called back-focusing, and in this case, the phase of the output value of the first AF pixel R shifts to the right from the focused state phase, and the phase of the output value of the second AF pixel L shifts to the left from the focused state phase. The shift amount between the phases of the output values ​​of the first AF pixel R and the second AF pixel L can be converted into the deviation amount between the focuses.

[0030] FIG. 5 is a circuit diagram illustrating an example of a pixel included in a pixel array of an autofocus image sensor according to an embodiment of the present invention.

[0031] 5, a pixel or unit pixel 600 includes a photoelectric conversion part 610 and a signal generation part 612. The first pixel AFP and the second pixel NP shown in FIG 1 may have the same pixel structure and circuit structure, except that openings of different sizes are formed therein as described above with reference to FIG 2.

[0032] The photoelectric conversion unit 610 performs photoelectric conversion. That is, the photoelectric conversion unit 610 converts incident light in a light integration mode to generate photocharges. If the image sensor including the unit pixel 600 is a CMOS image sensor, in the light integration mode, a shutter of the CMOS image sensor is opened and charge carriers such as electron-hole pairs are generated in the photoelectric conversion unit 610 by the incident light, and information about an image of a subject is collected.

[0033] The signal generator 612 generates an analog pixel signal (VP) based on the photocharge generated by the photoelectric conversion in a readout mode. If the image sensor including the unit pixel 600 is a CMOS image sensor, the shutter is closed in the readout mode after the light integration mode, and an analog pixel signal (VP) is generated based on information about the image of the object collected in the form of charge carriers. FIG. 5 illustrates the signal generator 612 having a 4-transistor structure.

[0034] Specifically, the signal generating unit 612 may include a transfer transistor 620, a reset transistor 640, a drive transistor 650, and a selection transistor 660, and may include a floating diffusion node 630. The transfer transistor 620 is connected between the photoelectric conversion unit 610 and the floating diffusion node 630, and may include a gate to which a transfer signal (TX) is applied. The reset transistor 640 is connected between a power supply voltage (VDD) and the floating diffusion node 630, and may include a gate to which a reset signal (RX) is applied. The drive transistor 650 is connected between the power supply voltage (VDD) and the selection transistor 660, and may include a gate connected to the floating diffusion node 630. The selection transistor 660 is connected between the drive transistor 650 and an output terminal that outputs an analog pixel signal (VP), and may include a gate to which a selection signal (SEL) is applied.

[0035] According to an embodiment, as will be described later with reference to FIG. 26, a structure in which a plurality of photoelectric conversion units share one signal generation unit may be implemented.

[0036] Fig. 6 is a plan view showing a layout of a lower portion of a pixel array of the autofocus image sensor of Fig. 1. Fig. 7 is a cross-sectional view showing an example of the pixel array of the autofocus image sensor of Fig. 6 cut along line A-A'. For convenience of illustration, Fig. 6 shows a layout of the upper half of one pixel group PG included in the pixel array 100 of Fig. 1.

[0037] 1, 6 and 7, the pixel array 100 of the autofocus image sensor includes a substrate 101, a plurality of pixels AFP, NP, a deep element isolation portion 110, and a plurality of first ground regions GR1 115. The pixel array 100 may further include a photoelectric conversion portion PD, a floating diffusion region FD, a transfer gate TG, contacts C1, C2, signal wiring L1, L2, a gate insulating film 121, first to third interlayer insulating films 123, 125, 127, a first passivation film 129, a fixed charge film 131, first and second insulating films 133, 135, a light blocking pattern 140, a second passivation film 141, a planarization film 143, a color filter 145, and a microlens 35.

[0038] The substrate 101 includes a first surface 101a and a second surface 101b facing each other. A gate electrode (e.g., a transfer gate TG) and wiring (e.g., signal wirings L1 and L2) are disposed on the first surface 101a. A light-shielding pattern 140, a color filter 145, a microlens 35, and the like are disposed on the second surface 101b, and light is incident through the second surface 101b. For example, the first surface 101a may be a front surface, the second surface 101b may be a rear surface, and the autofocus image sensor including the pixel array 100 may be a backside illuminated image sensor (BIS) that operates in response to incident light incident through the rear surface of the substrate 101.

[0039] In the rear-illumination type image sensor, the distance from the microlens 35 to the photoelectric conversion unit PD is relatively short, and light is not diffusely reflected or blocked due to the gate electrode and wiring, so that the image sensor can have relatively improved light receiving efficiency and light sensitivity. In addition, there are no restrictions on the arrangement of the signal wirings L1 and L2 arranged on the first surface 101a, and the signal wirings L1 and L2 can be arranged so as to overlap with the photoelectric conversion unit PD.

[0040] The plurality of pixels AFP, NP are disposed in the substrate 101 and include a plurality of first pixels AFP used to detect a phase difference and a plurality of second pixels NP used to detect an image. The AF pixels 21R, 21L in the focus detection area 11 and the general pixel 23 in the image detection area 13 described above with reference to Fig. 2 may correspond to the plurality of first pixels AFP and the plurality of second pixels NP, respectively. Each of the plurality of pixels AFP, NP may include a photoelectric conversion unit PD, a floating diffusion region FD, a transfer gate TG, etc.

[0041] The photoelectric conversion unit PD corresponds to the photoelectric conversion unit 610 in FIG. 5, and is disposed adjacent to both the first and second surfaces 101a and 101b of the substrate 101, and can perform photoelectric conversion based on incident light to generate photocharges. For example, an electron-hole pair corresponding to incident light is generated in the photoelectric conversion unit PD, and the photoelectric conversion unit PD can collect the electrons or holes, respectively. For convenience, the photoelectric conversion unit PD has been described as a photodiode, but the photoelectric conversion unit PD can include a photodiode, a phototransistor, a photogate, a pinned photodiode (PPD), or a combination thereof.

[0042] 5, is disposed on the first surface 101a of the substrate 101 via a gate insulating film 121, and can transfer the photocharges collected in the photoelectric conversion unit PD to the floating diffusion region FD. The floating diffusion region FD corresponds to the floating diffusion node 630 in FIG. 5, is disposed adjacent to the first surface 101a of the substrate 101, and can accumulate the photocharges collected in the photoelectric conversion unit PD through the photoelectric conversion. AF information and / or image information can be generated based on the amount of photocharges transferred to the floating diffusion region FD.

[0043] The deep isolation portion 110 is disposed in the substrate 101 and extends vertically from the second surface 101b of the substrate 101 so as to penetrate the substrate 101, isolating each of the pixels AFP, NP from each other, and does not directly contact the first surface 101a of the substrate 101. The deep isolation portion 110 extends in a direction perpendicular to the first and second surfaces 101a, 101b of the substrate 101 in a cross-sectional view and has both ends, one end of which is in direct contact with the second surface 101b and located on the same plane, while the other end of which is not located on the same plane as the first surface 101a. Thus, the depth of the deep isolation portion 110 may be smaller than the thickness of the substrate 101. The deep isolation portion 110 may have a mesh structure in a plan view.

[0044] The deep isolation portion 110 may have a deep trench isolation (DTI) structure that is formed relatively deep. For example, when the autofocus image sensor including the pixel array 100 is a back-illumination type image sensor, the deep isolation portion 110 may have a back DTI (BDTI) structure that extends from the back surface of the substrate 101.

[0045] The first ground regions 115 are disposed in the substrate 101 adjacent to the first surface 101a and adjacent to at least some of the first pixel AFPs. For example, the first ground regions 115 may be disposed to be included in all of the first pixel AFPs. All of the second pixel NPs may not include a ground region. Since the deep isolation portion 110 does not directly contact the first surface 101a, a ground voltage applied to the first ground regions 115 in the first pixel AFPs may be provided to the adjacent second pixel NPs through a space between the deep isolation portion 110 and the first surface 101a, and therefore the second pixel NPs may operate stably even if they do not include a ground region.

[0046] The first surface 101a of the substrate 101 may be covered with a first interlayer insulating film 123. A contact C1 may penetrate the first interlayer insulating film 123. The contact C1 may be in contact with the floating diffusion region FD. A signal line L1 may be disposed on the first interlayer insulating film 123. The signal line L1 may be in contact with the contact C1. The first interlayer insulating film 123 and the signal line L1 may be covered with a second interlayer insulating film 125. A contact C2 may penetrate the first and second interlayer insulating films 123 and 125. The contact C2 may be in contact with the first ground region 115. A signal line L2 may be disposed on the second interlayer insulating film 125. The signal line L2 may be in contact with the contact C2. The second interlayer insulating film 125 and the signal line L2 may be covered with a third interlayer insulating film 127. The third interlayer insulating film 127 may be covered with a first passivation film 129.

[0047] Although not shown in detail, components for forming the reset transistor 640, drive transistor 650, and selection transistor 660 of FIG. 5 may be additionally arranged on the first surface 101a of the substrate 101 and / or within the substrate 101 adjacent to the first surface 101a, and contacts and signal wiring connected to such components may be additionally arranged between the interlayer insulating films 123, 125, and 127.

[0048] A fixed charge film 131 may be disposed on the second surface 101b of the substrate 101. For example, the fixed charge film 131 may have a negative fixed charge. The fixed charge film 131 causes hole accumulation around the second surface 101b, thereby effectively reducing dark current and white spots. A first insulating film 133 and a second insulating film 135 may be sequentially stacked on the fixed charge film 131.

[0049] A light blocking pattern 140 may be disposed on the second insulating film 135 (i.e., on the second surface 101b of the substrate 101). The light blocking pattern 140 may adjust the amount of light incident on the first pixel AFPs to be less than the amount of light incident on the second pixel NPs. For example, the light blocking pattern 140 may be disposed only in the focus detection region 11. The light blocking pattern 140 may have a mesh structure overlapping with the deep element isolation portion 110 in a plan view, and may have a larger area on the first pixel AFPs than on the second pixel NPs. The light blocking pattern 140 may include a plurality of first openings 31 that partially expose the first pixel AFPs.

[0050] Meanwhile, although not shown, according to an embodiment, the light blocking pattern 140 may be partially disposed on the image detection area 13 to form a plurality of second openings 33 .

[0051] A second passivation film 141 may be conformally laminated on the light-shielding pattern 140. A planarization film 143 may be disposed on the second passivation film 141. A color filter array including a plurality of color filters 145 may be disposed on the planarization film 143, and a microlens array including a plurality of microlenses 35 may be disposed on the color filter array. The microlenses 35 may adjust a path of incident light so that the incident light entering the microlenses 35 can be focused on the photoelectric conversion unit PD.

[0052] In one embodiment, the color filter array may have a Bayer pattern including a red filter, a green filter, and a blue filter. In another embodiment, the color filter array may include a yellow filter, a magenta filter, and a cyan filter. The color filter array may further include a white filter.

[0053] Although not shown, an anti-reflection layer may be further formed between the planarization film 143 and the color filter 145. The anti-reflection layer may prevent the incident light from being reflected by the second surface 101b of the substrate 101. According to an embodiment, the anti-reflection layer may be formed by alternately stacking materials having different refractive indexes, and in this case, the more materials having different refractive indexes are alternately stacked, the more the transmittance of the anti-reflection layer may be improved.

[0054] 8a, 8b, 8c, 8d, 8e and 8f are cross-sectional views illustrating a method for manufacturing the pixel array of the autofocus image sensor of FIGS.

[0055] 8a, a substrate 101 is provided having first and second surfaces 101a, 101b facing each other. The substrate 101 is a semiconductor substrate, and may be, for example, a P-type silicon substrate.

[0056] 8b, a photoelectric conversion unit PD, a floating diffusion region FD, and a first ground region GR1 are formed in a substrate 101. For example, the photoelectric conversion unit PD, the floating diffusion region FD, and the first ground region GR1 may be provided using an ion implantation process. For example, the photoelectric conversion unit PD and the floating diffusion region FD may be doped with N-type impurities having an opposite conductivity type to that of the substrate 101, and the first ground region GR1 may be doped with P-type impurities having the same conductivity type as that of the substrate 101, and may be doped at a higher concentration than that of the substrate 101.

[0057] The floating diffusion region FD and the first ground region GR1 may be formed adjacent to the first surface 101a. The photoelectric conversion unit PD may be formed adjacent to both the first and second surfaces 101a and 101b. In this case, since the floating diffusion region FD and the first ground region 115 are disposed adjacent to the first surface 101a, the width (or area) of the portion of the photoelectric conversion unit PD adjacent to the first surface 101a may be smaller than the width of the portion of the photoelectric conversion unit PD adjacent to the second surface 101b. Since the FWC is largest at the portion adjacent to the first surface 101a, it may be advantageous to form the portion of the photoelectric conversion unit PD adjacent to the first surface 101a large in order to improve the FWC characteristics.

[0058] According to an embodiment, the photoelectric conversion unit PD may be formed in a form in which two or more doped regions are stacked, and the floating diffusion region FD may be doped at a higher concentration than the photoelectric conversion unit PD.

[0059] 8c, a gate insulating film 121 and a transfer gate TG are formed on the first surface 101a, and a first interlayer insulating film 123 is formed to cover the first surface 101a. Referring to FIG. 8d, a contact C1 penetrating the first interlayer insulating film 123 is formed, a signal line L1 is formed on the first interlayer insulating film 123, and a second interlayer insulating film 125 is formed on the first interlayer insulating film 123. In addition, a contact C2 penetrating the first and second interlayer insulating films 123 and 125 is formed, a signal line L2 is formed on the second interlayer insulating film 125, and a third interlayer insulating film 127 and a first passivation film 129 are sequentially formed on the second interlayer insulating film 125.

[0060] For example, the transfer gate TG may be formed by stacking a gate conductive film using polysilicon, metal and / or metal compound, and then patterning the stacked gate conductive film. The contacts C1, C2 and the signal lines L1, L2 may be formed by stacking and patterning a conductive material including a metal such as copper, tungsten, titanium, or aluminum. The interlayer insulating films 123, 125, and 127 may be formed using silicon oxide (SiOx), silicon oxynitride (SiOxNy), silicon nitride (SiNx), germanium oxynitride (GeOxNy), germanium silicon oxide (GeSixOy), or a material having a high dielectric constant. Meanwhile, examples of such a high dielectric constant material include hafnium oxide (HfOx), zirconium oxide (ZrOx), aluminum oxide (AlOx), tantalum oxide (TaOx), hafnium silicate (HfSix), zirconium silicate (ZrSix), and the like. Also, the interlayer insulating films 123, 125, and 127 may be formed in a multi-layer structure using two or more selected materials from the above-mentioned materials.

[0061] 8e, the substrate 101 is turned over so that the second surface 101b faces up, and a back-grinding process is performed on the second surface 101b to remove a portion of the substrate 101 adjacent to the second surface 101b. For example, the grinding process on the rear surface of the substrate 101 can be performed by a mechanical method and / or a chemical method. The mechanical method can be performed by contacting a polishing pad with the rear surface to generate friction, and the chemical method can be performed by injecting a chemical substance called slurry between the polishing pad and the rear surface to cause a reaction.

[0062] 8e, the substrate 101 is turned over and a portion of the substrate 101 is removed, and then a deep isolation portion 110 is formed in the substrate 101. The deep isolation portion 110 includes an insulating material, and may include, for example, a silicon oxide film. By forming an insulating material for providing the deep isolation portion 110 from the second surface 101b of the substrate 101, one end of the deep isolation portion 110 may be in direct contact with the second surface 101b, and the other end may not be in direct contact with the first surface 101a.

[0063] In one embodiment, the deep isolation region 110 may be formed of an insulating material having a smaller refractive index for incident light than the substrate 101. In this case, the leakage component of the incident light generated by the microlens 35 is totally reflected on the surface of the deep isolation region 110 to prevent it from reaching an adjacent pixel, and the leakage component is reflected by the deep isolation region 110 to reach the photoelectric conversion unit PD. In addition, by forming the deep isolation region 110 of the insulating material, charge carriers generated by the incident light can be prevented from reaching the adjacent pixel due to diffusion.

[0064] In one embodiment, the deep isolation region 110 may be formed by injecting the insulating material multiple times using different energies, and by performing the injection multiple times as described above, the deep isolation region 110 may have an uneven surface structure.

[0065] Referring to FIG. 8f, the fixed charge film 131, the first and second insulating films 133 and 135, and the light-shielding pattern 140 are sequentially formed on the second surface 101b. For example, the fixed charge film 131 may be formed using a metal oxide in which a metal element such as hafnium (Hf), zirconium (Zr), aluminum (Al), tantalum (Ta), titanium (Ti), yttrium (Y), and lanthanoid is oxidized, and may have a region that is at least partially crystallized within the film. For example, the fixed charge film 131 may be a hafnium oxide film or an aluminum fluoride film. For example, the first insulating film 133 may be a silicon oxide film, and the second insulating film 135 may be a silicon nitride film. For example, the light-shielding pattern 140 may be made of an opaque metal.

[0066] In the manufacturing process, the rear light receiving type image sensor may generate noise due to surface defects present on the second surface 101b of the substrate 101, and when the fixed charge layer 131 is formed, the surface defects can be passivated using holes accumulated around the second surface 101b of the substrate 101. For example, the generation of dark current can be reduced by combining electrons (i.e., dark current) generated in a dark state with the accumulated holes, thereby improving light receiving efficiency and photosensitivity.

[0067] 7, the second passivation film 141, the planarization film 143, the plurality of color filters 145, and the plurality of microlenses 35 are sequentially formed on the light-shielding pattern 140. For example, the color filters 145 can be formed using a dyeing process, a pigment dispersion process, a printing process, etc. For example, a pattern corresponding to the photoelectric conversion unit PD can be formed using a light-transmitting photoresist, and the pattern can be reflowed to form the microlenses 35 having a certain curvature and a convex shape toward the direction in which the incident light is provided.

[0068] Figures 9, 10, 11, 12, 13, 14, and 15 are cross-sectional views showing other examples of the pixel array of the autofocus image sensor of Figure 6 cut along A-A'. Hereinafter, descriptions overlapping with Figures 6 and 7 will be omitted.

[0069] 9, the embodiment may be substantially the same as that of FIG. 7, except that the deep isolation portion 110a is implemented by including an insulating layer 111 and a polysilicon pattern 113. As shown in FIG.

[0070] The insulating film 111 may surround the polysilicon pattern 113. The polysilicon pattern 113 may be formed in the deep device isolation portion 110a, i.e., inside the insulating film 111. For example, the polysilicon pattern 113 may be formed using polysilicon, metal and / or metal compound. Since the polysilicon pattern 113 has a thermal expansion coefficient substantially the same as that of silicon constituting the substrate 101, physical stress caused by the difference in thermal expansion coefficient of materials may be reduced. According to the embodiment, the insulating film 111 may be formed after the polysilicon pattern 113 is formed, or the polysilicon pattern 113 may be formed after the insulating film 111 is formed.

[0071] 10, the embodiment may be substantially the same as that of FIG. 7, except that the deep device isolation portion 110b is embodied to include a fixed charge layer 131 and a first insulating layer 133. For example, the fixed charge layer 131 may be a hafnium oxide layer. The first insulating layer 133 may be a silicon oxide layer or a silicon nitride layer. The fixed charge layer 131 is formed to cover not only the second surface 101b but also all of the side surfaces of the photoelectric conversion unit PD, thereby further improving dark current characteristics.

[0072] 11, the embodiment may be substantially the same as that of FIG 7, except that a portion 110g of the deep isolation portion 110 may be modified. For example, the portion 110g of the deep isolation portion 110 may extend to directly contact the first surface 101a of the substrate 101.

[0073] In one embodiment, as described above with reference to FIG. 1, the pixels are divided into a plurality of pixel groups PG, each including a portion of the plurality of first pixels AFP and a portion of the plurality of second pixels NP, and a portion 110g of the deep device isolation portion 110 may extend to directly contact the first surface 101a of the substrate 101 so that the plurality of pixel groups PG are separated from one another. In this case, the plurality of first ground regions GR1 may be disposed in the substrate 101 so that the plurality of pixel groups PG include at least one of the plurality of first ground regions GR1. If the portion 110g of the deep device isolation portion 110 directly contacts the first surface 101a of the substrate 101, a ground voltage applied to the plurality of first ground regions 115 may not be provided to adjacent pixels. Therefore, if the plurality of pixel groups PG are separated from one another by the portion 110g of the deep device isolation portion 110, each of the plurality of pixel groups PG must include at least one of the plurality of first ground regions GR1 in order to operate stably.

[0074] 12, the embodiment may be substantially the same as that of FIG. 7, except that the deep isolation portion includes a first sub-deep isolation portion 110g1 and a second sub-deep isolation portion 110g2. The first sub-deep isolation portion 110g1 may be substantially the same as the deep isolation portion 110 of FIG. 7. The second sub-deep isolation portion 110g2 may be substantially the same as a portion 110g of the deep isolation portion 110 of FIG. 11. For example, the first sub-deep isolation portion 110g1 is formed by forming an insulating material from the second surface 101b of the substrate 101, and the second sub-deep isolation portion 110g2 is formed by forming an insulating material from the first surface 101a of the substrate 101.

[0075] 13, the embodiment may be substantially the same as that of FIG. 7, except that a shallow device isolation portion 150 is further included. The shallow device isolation portion 150 may have a shallow trench isolation (STI) structure formed relatively shallowly. The shallow device isolation portion 150 may separate the photoelectric conversion portion PD from the floating diffusion region FD and the first ground region GR1. For example, the shallow device isolation portion 150 may be formed by etching the substrate 101 to form a shallow trench and filling the trench with a buried insulating film.

[0076] 14, except for the change in the structure of the photoelectric conversion unit PD, this may be substantially the same as the embodiment of FIG 7. Unlike the embodiment of FIG 7 in which the side of the photoelectric conversion unit PD is separated from the deep device isolation unit 110, in the embodiment of FIG 14, the side of the photoelectric conversion unit PD may be formed to be in full contact with the deep device isolation unit 110, thereby increasing the size of the photoelectric conversion unit PD.

[0077] Referring to Fig. 15, except for a change in the structure of some of the photoelectric conversion units PD, this may be substantially the same as the embodiment of Fig. 7. In the embodiment of Fig. 15, the size of the photoelectric conversion units PD included in the plurality of second pixels NP (i.e., general pixels 23) may be larger than the size of the photoelectric conversion units PD included in the plurality of first pixels AFP (i.e., AF pixels 21R, 21L). As described above, the plurality of second pixels NP do not include a ground region, and therefore the size of the photoelectric conversion units PD can be increased only in the portions where the ground regions are not formed.

[0078] Meanwhile, two or more of the embodiments described above with reference to Figures 7, 9, 10, 11, 12, 13, 14, and 15 may be combined to implement a pixel array of an autofocus image sensor according to an embodiment of the present invention.

[0079] Fig. 16 is a plan view showing a pixel array of an autofocus image sensor according to an embodiment of the present invention. Fig. 17 is a plan view showing a schematic layout of a part of the pixel array of the autofocus image sensor of Fig. 16. Hereinafter, the description overlapping with Figs. 1 and 2 will be omitted.

[0080] 16 and 17, the embodiment may be substantially the same as the embodiment of FIGS. 1 and 2, except that the arrangement and structure of the first pixels AFP are changed.

[0081] The pixel array 100a of the autofocus image sensor may include a focus detection area 11a and an image detection area 13a. The focus detection area 11a may include a third AF pixel 21U and a fourth AF pixel 21D adjacent to each other and used for detecting a phase difference. The image detection area 13a may include a general pixel 23 used for detecting an image.

[0082] A light-shielding pattern for controlling the amount of light received by the AF pixels 21U and 21D may be disposed. The light-shielding pattern may include a plurality of first openings 31 formed on the AF pixels 21U and 21D. The first openings 31 of the adjacent third and fourth AF pixels 21U and 21D may be disposed symmetrically with respect to each other vertically. The first openings 31 of the light-shielding pattern serve to adjust the amount of light incident on the AF pixels 21U and 21D to be smaller than the amount of light incident on the general pixels 23.

[0083] Meanwhile, a pixel array of an autofocus image sensor according to an embodiment of the present invention may be implemented to include all of the AF pixels 21R and 21L described above with reference to FIG. 2 and the AF pixels 21U and 21D described above with reference to FIG.

[0084] Fig. 18 is a plan view showing a pixel array of an autofocus image sensor according to an embodiment of the present invention. Fig. 19 is a cross-sectional view showing an example of a pixel array of the autofocus image sensor of Fig. 18. Hereinafter, descriptions overlapping with Figs. 1, 6, and 7 will be omitted.

[0085] 18 and 19, the embodiments may be substantially the same as those of FIGS. 1, 6, and 7, except that a portion (AFP') of the plurality of first pixels AFP, AFP' is changed.

[0086] In the pixel array 100b of the autofocus image sensor, the number of the first contact regions GR1 is less than the number of the first pixels AFP, AFP', and the first contact regions GR1 may be disposed adjacent to some AFPs of the first pixels AFP, AFP'. In other words, some AFPs of the first pixels AFP, AFP' may include one of the first contact regions GR1, and the other part (AFP') may not include the first contact regions GR1. The first pixel not including the first contact region GR1 is denoted as AFP'. Similar to what has been described above with reference to FIG. 1, the first contact regions GR1 may be uniformly and regularly arranged throughout the pixel array 100b.

[0087] Fig. 20 is a plan view showing a pixel array of an autofocus image sensor according to an embodiment of the present invention. Figs. 21 and 22 are cross-sectional views showing an example of a pixel array of the autofocus image sensor of Fig. 20. Hereinafter, descriptions overlapping with Figs. 1, 6, and 7 will be omitted.

[0088] Referring to Figures 20, 21, and 22, the embodiments may be substantially the same as those of Figures 1, 6, and 7, except that a portion (NP') of the plurality of second pixels NP, NP' is changed.

[0089] The pixel array 100c of the autofocus image sensor may further include a plurality of second ground regions GR2. The plurality of second ground regions GR2 may be disposed adjacent to the first surface 101a in the substrate 101, and may be disposed adjacent to only a portion (NP') of the plurality of second pixels NP, NP'. In other words, a portion (NP') of the plurality of second pixels NP, NP' may be embodied to include one of the plurality of second ground regions GR2. The second pixel including the second ground region GR2 is denoted as NP'. Similar to the first ground region GR1, a ground voltage may be applied to the plurality of second ground regions GR2 to reduce dark current. The first and second ground regions GR1, GR2 may be uniformly and regularly arranged throughout the pixel array 100c.

[0090] In one embodiment, as shown in Figure 21, the size (or area) of the second ground region 165 may be substantially the same as the size of the first ground region 115. In another embodiment, as shown in Figure 22, the size (or area) of the second ground region 165a may be smaller than the size of the first ground region 115. As described above with reference to Figure 7, the ground voltage is provided to the peripheral pixels through the space between the deep device isolation portion 110 and the first surface 101a, and therefore stable operation may be possible even if the second ground region 165a is relatively small.

[0091] Fig. 23 is a plan view showing a pixel array of an autofocus image sensor according to an embodiment of the present invention. Fig. 24 is a cross-sectional view showing an example of a pixel array of the autofocus image sensor of Fig. 23. Hereinafter, descriptions overlapping with Figs. 1, 6, and 7 will be omitted.

[0092] 23 and 24, the embodiment may be substantially the same as the embodiment of FIGs. 1, 6, and 7, except that a part (AFP') of the plurality of first pixels AFP, AFP' and a part (NP') of the plurality of second pixels NP, NP' are changed. The first pixel (AFP') included in the pixel array 100d of the autofocus image sensor may be substantially the same as that described above with reference to FIGs. 18 and 19. The second pixel (NP') may be substantially the same as that described above with reference to FIGs. 20, 21, and 22.

[0093] Meanwhile, the structures of the pixel arrays shown in Figures 19, 21, 22, and 24 may be modified as in the embodiments described above with reference to Figures 7, 9, 10, 11, 12, 13, 14, and 15, or may be embodied by combining two or more of the above-mentioned embodiments.

[0094] Fig. 25 is a plan view showing a pixel array of an autofocus image sensor according to an embodiment of the present invention. Fig. 26 is a circuit diagram showing another example of a pixel included in the pixel array of an autofocus image sensor according to an embodiment of the present invention. Fig. 27 is a cross-sectional view showing an example of a pixel array of the autofocus image sensor of Fig. 25. Below, descriptions overlapping with Figs. 1, 5, 6, and 7 will be omitted.

[0095] 25, 26, and 27, the embodiments may be substantially the same as those of FIGS. 1, 5, 6, and 7, except that some of the adjacent pixels AFP, NP are implemented to share a floating diffusion region FD.

[0096] In the pixel array 100e of the autofocus image sensor, four adjacent pixels may share a floating diffusion region FD. For example, as shown in FIG 26, the first to fourth pixels 600a include first, second, third and fourth photoelectric conversion parts 610a, 610b, 610c and 610d, and a signal generation part 612a shared by the first to fourth photoelectric conversion parts 610a to 610d.

[0097] The signal generating unit 612a may include first, second, third, and fourth transfer transistors 620a, 620b, 620c, and 620d connected to the first to fourth photoelectric conversion units 610a to 610d and receiving first, second, third, and fourth transfer signals TX1, TX2, TX3, and TX4, a floating diffusion node 630 connected to the first to fourth transfer transistors 620a to 620d, a reset transistor 640 connected to the floating diffusion node 630, a drive transistor 650, and a selection transistor 660.

[0098] Although FIG. 26 illustrates four adjacent pixels sharing the signal generator 612a, the present invention is not limited thereto, and the number of pixels sharing the signal generator 612a may vary according to embodiments.

[0099] By adjacent pixels sharing the signal generation unit 612a, one floating diffusion region FD can be arranged between adjacent AF pixels 21R, 21L, and one floating diffusion region FD can be arranged between adjacent general pixels 23, as shown in FIG. 27.

[0100] Meanwhile, the arrangement of the ground regions shown in Figures 25 and 27 may be modified as in the embodiments described above with reference to Figures 18 to 24. Also, the structure of the pixel array shown in Figure 27 may be modified as in the embodiments described above with reference to Figures 7, 9, 10, 11, 12, 13, 14, and 15, or may be embodied by combining two or more of the above-described embodiments.

[0101] Fig. 28 is a plan view showing a pixel array of an autofocus image sensor according to an embodiment of the present invention. Fig. 29 is a plan view showing a schematic layout of a portion of the pixel array of the autofocus image sensor of Fig. 28. Fig. 30 is a cross-sectional view showing an example of the pixel array of the autofocus image sensor of Fig. 28. Below, descriptions overlapping with Figs. 1, 2, 6, and 7 will be omitted.

[0102] 28, 29, and 30, a pixel array 100f of an autofocus image sensor includes a substrate 101, a plurality of pixels DP, a deep isolation portion 110, and a plurality of ground regions GR. The substrate 101, the deep isolation portion 110, and other components may be substantially the same as those described above with reference to FIGS. 6 and 7.

[0103] In the embodiments described above with reference to Figures 1 to 27, a plurality of first pixels AFP used to detect a phase difference and a plurality of second pixels NP used to detect an image are implemented separately, but in the embodiments shown in Figures 28, 29, and 30, each of a plurality of pixels DP can perform both a function of detecting a phase difference and a function of detecting an image. Each pixel DP can be called a dual pixel.

[0104] As shown in Fig. 29, the focus detection area 11b and the image detection area 13b of the pixel array 100f of the autofocus image sensor may be the same area. A third opening 37 and a fourth opening 39 may be formed on each dual pixel 25 by a light blocking pattern. The third opening 37 and the fourth opening 39 are similar to the first opening 31 of Fig. 2, and the third opening 37 and the fourth opening 39 may simply be formed under one microlens 35. Light corresponding to an L signal may be received through the third opening 37, and light corresponding to an R signal may be received through the fourth opening 39.

[0105] As shown in Fig. 30, each dual pixel 25 may include two photoelectric conversion units PD. The left photoelectric conversion unit is disposed to correspond to the third opening 37 and may operate similarly to the second AF pixel L of Figs. 2 and 7, and the right photoelectric conversion unit is disposed to correspond to the fourth opening 39 and may operate similarly to the first AF pixel R of Figs. 2 and 7. In addition, signals from the two photoelectric conversion units may be summed to generate an image signal. One photoelectric conversion unit may be defined as one subpixel, and two subpixels may be described as sharing one microlens 35.

[0106] The ground regions GR are disposed adjacent to at least some of the pixels DP. The number of the ground regions GR is less than the number of the pixels DP, and only some of the pixels DP may include one of the ground regions GR.

[0107] FIG. 31 is a cross-sectional view illustrating an example pixel array of an autofocus image sensor according to an embodiment of the present invention.

[0108] 31, adjacent first pixels AFP (i.e., AF pixels 21R and 21L) may be implemented to share a microlens 35, and each of a plurality of second pixels NP (i.e., general pixels 23) may be implemented to include one microlens per pixel. In other words, a structure may be formed by combining the embodiments described above with reference to FIGS. 1 to 27 and the embodiments described above with reference to FIGS. 28 to 30.

[0109] Meanwhile, in the embodiments of Figures 28 to 31, the arrangement of the ground region may be changed to that of the embodiments described above with reference to Figures 18 to 24. Also, in the embodiments of Figures 28 to 31, the structure of the pixel array may be changed to that of the embodiments described above with reference to Figures 7, 9, 10, 11, 12, 13, 14, and 15, or two or more of the above embodiments may be combined.

[0110] FIG. 32 is a block diagram illustrating an autofocus image sensor according to an embodiment of the present invention.

[0111] 32, the autofocus image sensor 500 includes a pixel array 510, a correlated double sampling (CDS) block 530, and an analog-to-digital conversion (ADC) block 540. The autofocus image sensor 500 may further include a row driver 520, an image processor 550, a ramp signal generator 560, and a timing controller 580.

[0112] The pixel array 510 includes a plurality of unit pixels or pixels PX arranged in a matrix form. Each of the plurality of unit pixels PX may be connected to one of a plurality of rows RW1, RW2, ..., RWX (X is a natural number equal to or greater than 2) and one of a plurality of columns CL1, CL2, ..., CLY (Y is a natural number equal to or greater than 2). The pixel array 510 senses incident light and generates a plurality of analog pixel signals VP1, VP2, ..., VPY corresponding to the incident light. The pixel array 510 may be a pixel array according to the embodiment of the present invention described above with reference to FIGS. 1 to 31.

[0113] The row driver 520 is connected to the rows RW1 to RWX of the pixel array 510 and can generate driving signals to drive the rows RW1 to RWX. For example, the row driver 520 can drive the unit pixels PX included in the pixel array 510 on a row-by-row basis.

[0114] The correlated double sampling block 530 may include a plurality of correlated double sampling circuits 530a, 530b, ..., 530c. The correlated double sampling circuits 530a to 530c are connected to a plurality of columns CL1 to CLY of the pixel array 510 and may perform CDS operations on a plurality of analog pixel signals VP1 to VPY output from the pixel array 510.

[0115] The analog-to-digital conversion block 540 includes a plurality of analog-to-digital converters 540a, 540b, ..., 540c. The plurality of analog-to-digital converters 540a to 540c are connected to the plurality of columns CL1 to CLY of the pixel array 510 through the plurality of correlated double sampling circuits 530a to 530c, and perform column ADC for converting the plurality of analog pixel signals VP1 to VPY (i.e., CDS-processed analog pixel signals output from the plurality of correlated double sampling circuits 530a to 530c) output from the pixel array 510 into a plurality of digital signals CNT1, CNT2, ..., CNTY in parallel (i.e., simultaneously).

[0116] Each of the plurality of analog-to-digital converters 540a to 540c may include one of a plurality of comparators 542a, 542b, ..., 542 and one of a plurality of counters (CNT) 544a, 544b, ..., 544c. For example, the first analog-to-digital converter 540a may include a first comparator 542a that compares the first analog pixel signal VP1 with a ramp signal VRAMP to generate a first comparison signal CS1, and a first counter 544a that counts a level transition time of the first comparison signal CS1 to generate a first digital signal CNT1.

[0117] The operations of the correlated double sampling block 530 and the analog-to-digital conversion block 540 described above can be performed on a row-by-row basis in the pixel array 510 .

[0118] The plurality of correlated double sampling circuits 530a-530c and the plurality of analog-to-digital converters 540a-540c may form a plurality of column driving circuits. For example, the first correlated double sampling circuit 530a and the first analog-to-digital converter 540a may form a first column driving circuit.

[0119] The image processor 550 may perform image processing based on the digital signals CNT1 to CNTY. For example, the image processor 550 may perform an AF information acquisition operation using the AF pixels and an image acquisition operation using the general pixels.

[0120] According to an embodiment, the image processor 550 may be omitted, in which case the image processing described above may be performed by an external processor (eg, the application processor 1110 of FIG. 33).

[0121] The ramp signal generator 560 may generate a ramp signal VRAMP. The timing controller 580 may control the overall operation timing of the autofocus image sensor 500 and may generate control signals such as a count enable signal CNT_EN and a clock signal (not shown).

[0122] FIG. 33 is a block diagram illustrating an electronic system including an autofocus image sensor according to an embodiment of the present invention.

[0123] 33, the electronic system 1000 may be implemented as a data processing device that can use or support a MIPI interface, and may include an application processor 1110, an autofocus image sensor 1140, and a display 1150. The electronic system 1000 may further include an RF chip 1160, a GPS 1120, a storage 1170, a microphone 1180, a DRAM 1185, and a speaker 1190, and may perform communication using UWB 1210, WLAN 1220, WIMAX 1230, etc.

[0124] The application processor 1110 may represent a controller or processor that controls the operation of the autofocus image sensor 1140. The autofocus image sensor 1140 may be an autofocus image sensor according to an embodiment of the present invention.

[0125] The application processor 1110 may include a DSI host 1111 that communicates with a DSI device 1151 in the display 1150, a CSI host 1112 that communicates with a CSI device 1141 in the autofocus image sensor 1140, a PHY 1161 in the RF chip 1160 and a PHY 1113 that transmits and receives data according to DigRF, and a DigRF MASTER 1114 that controls a DigRF SLAVE 1162 in the RF chip 1160.

[0126] In one embodiment, DSI host 1111 can include an optical serializer SER and DSI device 1151 can include an optical deserializer DES. In one embodiment, CSI host 1112 can include an optical deserializer DES and CSI device 1141 can include an optical serializer SER. [Industrial Applicability]

[0127] The embodiments of the present invention can be usefully applied to any electronic device or system that includes an autofocus image sensor, for example, to a variety of electronic devices, such as computers, notebooks, mobile phones, smartphones, MP3 players, PDAs, PMPs, digital TVs, digital cameras, portable game consoles, navigation devices, wearable devices, Internet of Things devices, VR devices, and AR devices.

[0128] Although the present invention has been described above with reference to preferred embodiments, those skilled in the art will understand that the present invention can be modified and changed in various ways without departing from the spirit and scope of the present invention as set forth in the claims below. [Explanation of symbols]

[0129] 11 Focus detection area 13 Video detection area 21 AF pixels 23 General Pixels 25 Dual Pixel 31 First opening 33 Second Opening 35 Microlens 100 pixel array 101 Substrate 110 Deep isolation 115 1st grounding area 140 Shading Pattern 165 2nd ground area 500 Autofocus Image Sensor 510 pixel array

Claims

1. a substrate including a first surface on which a gate electrode is disposed and a second surface opposite to the first surface; A plurality of pixels are disposed within the substrate, the pixels including a plurality of first pixels used for detecting a phase difference and a plurality of second pixels used for detecting an image; a deep isolation region disposed within the substrate, the deep isolation region extending vertically from the second surface of the substrate to isolate each of the plurality of pixels from one another, the deep isolation region being out of direct contact with the first surface of the substrate; a plurality of first ground regions disposed in the substrate adjacent to the first surface and adjacent to at least some of the plurality of first pixels; A pixel array of an autofocus image sensor, wherein a ground voltage applied to the first ground region is provided to the adjacent second pixel through a space between the deep element isolation portion and the first surface of the substrate.

2. the number of the first ground regions is equal to the number of the first pixels; The pixel array of the autofocus image sensor of claim 1 , wherein the first ground regions are disposed adjacent to all of the first pixels.

3. the number of the first ground regions is less than the number of the first pixels; The pixel array of the autofocus image sensor of claim 1 , wherein the first ground regions are disposed adjacent to some of the first pixels.

4. 2. The pixel array of the autofocus image sensor of claim 1, wherein the first ground regions are formed by doping the substrate with a first impurity of the same conductivity type as the impurity doped in the substrate at a concentration higher than that of the substrate.

5. 2. The pixel array of claim 1, further comprising a plurality of second ground regions disposed in the substrate adjacent to the first surface and adjacent to only some of the plurality of second pixels.

6. 6. The pixel array of the autofocus image sensor of claim 5, wherein a size of the second contact areas is smaller than a size of the first contact areas.

7. The pixel array of the autofocus image sensor of claim 1 , wherein none of the second pixels includes a ground region.

8. 2. The pixel array of claim 1, further comprising a light blocking pattern disposed on the substrate and configured to adjust an amount of light incident on the first pixels so that an amount of light incident on the second pixels is less than an amount of light incident on the first pixels.

9. Light is incident through the second surface of the substrate; The pixel array of an autofocus image sensor as claimed in claim 8 , wherein the light blocking pattern is disposed on the second surface of the substrate.

10. the deep element isolation portion has a mesh structure, 9. The pixel array of claim 8, wherein the light blocking pattern has a mesh structure overlapping the deep device isolation portion and has a larger area in the first pixels than in the second pixels.

11. The light-shielding pattern is The pixel array of the autofocus image sensor of claim 10 , further comprising a plurality of first openings that partially expose the plurality of first pixels.

12. A plurality of color filters disposed on the light-shielding pattern; The pixel array of claim 8 , further comprising a plurality of microlenses disposed on the plurality of color filters.

13. the deep element isolation portion has a mesh structure, 2. The pixel array of claim 1, wherein a portion of the deep isolation portion extends to directly contact the first surface of the substrate.

14. The plurality of pixels are divided into a plurality of pixel groups, each of which includes a portion of the plurality of first pixels and a portion of the plurality of second pixels; 14. The pixel array of claim 13, wherein a portion of the deep isolation portion extends to directly contact the first surface of the substrate such that the plurality of pixel groups are isolated from one another.

15. 15. The pixel array of claim 14, wherein the plurality of first ground regions are disposed within the substrate such that the plurality of pixel groups includes at least one of the plurality of first ground regions.

16. 2. The pixel array of the autofocus image sensor as claimed in claim 1, wherein the depth of the deep isolation portion is less than a thickness of the substrate.

17. 2. The pixel array of the autofocus image sensor of claim 1, further comprising a polysilicon pattern formed within the deep device isolation portion.

18. Each of the plurality of pixels comprises: a photoelectric conversion unit that performs photoelectric conversion based on incident light; 2. The pixel array of the autofocus image sensor according to claim 1, further comprising a floating diffusion region for accumulating photocharges collected in the photoelectric conversion unit through the photoelectric conversion.

19. 20. The pixel array of claim 18, wherein some of the pixels adjacent to each other share the floating diffusion region.

20. 20. The pixel array of claim 18, wherein a size of a photoelectric conversion unit included in the second pixels among the plurality of pixels is larger than a size of a photoelectric conversion unit included in the first pixels among the plurality of pixels.

21. a pixel array for detecting incident light and generating a plurality of analog pixel signals representing phase difference information and image information; a plurality of column driving circuits coupled to the plurality of columns of the pixel array for converting the plurality of analog pixel signals into a plurality of digital signals; The pixel array comprises: a substrate including a first surface on which a gate electrode is disposed and a second surface opposite to the first surface; A plurality of pixels are disposed within the substrate, the pixels including a plurality of first pixels used for detecting a phase difference and a plurality of second pixels used for detecting an image; a deep isolation region disposed within the substrate, the deep isolation region extending vertically from the second surface of the substrate to isolate each of the plurality of pixels from one another, the deep isolation region being out of direct contact with the first surface of the substrate; a plurality of first ground regions disposed in the substrate adjacent to the first surface and adjacent to at least some of the plurality of first pixels; a ground voltage applied to the first ground region is provided to the adjacent second pixel through a space between the deep isolation region and the first surface of the substrate;

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