Patent Abstract:
An image sensor comprising: a first layer having a plurality of groups of photodiodes formed in a semiconductor substrate, each group representing a 2×2 array of photodiodes, with 2 first pixels configured to detect light of a first wavelength and 2 second pixels configured to detect light of a second wavelength, each first pixel positioned adjacent to the second pixels; and a second layer overlapping the first layer, the second layer is organic, having a plurality of organic photodiodes configured to detect light of a third wavelength, each organic photodiode positioned to partially overlap 2 first photodiodes and 2 second photodiodes of the first layer.

Full Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application is a continuation of U.S. application Ser. No. 15/004,494, filed Jan. 22, 2016, which is a continuation of U.S. application Ser. No. 14/310,305, filed Jun. 20, 2014, now U.S. Pat. No. 9,287,327, which claims the benefit of Korean Patent Application No. 10-2013-0071589, filed on Jun. 21, 2013, in the Korean Intellectual Property Office, the disclosure of which is incorporated by reference herein. 
     
    
     TECHNICAL FIELD 
       [0002]    Embodiments of the present inventive concept relate to an image sensor, and more particularly to an image sensor for generating a high-resolution image in which a pixel is in effect decreased in size without a decrease in the physical size of the pixel, a method for manufacturing the same, and an image processing device having the image sensor. 
       DISCUSSION OF RELATED ART 
       [0003]    To increase the resolution of a CMOS image sensor of a given size, the number of pixels included in an active pixel array need to be increased and the physical size of each pixel need to be decreased, so that more pixels can fit in a given light receiving area. 
         [0004]    As the pixel decreases in size, a photo-electronic conversion element, e.g., a photo diode, included in the pixel also decreases in size, and it may be difficult to embody circuitry for reading an output signal of the photo-electronic conversion element. 
       SUMMARY 
       [0005]    According to an embodiment of the present inventive concept, an image sensor is provided, comprising: a first layer having a plurality of groups of photodiodes formed in a semiconductor substrate, each group representing a 2×2 array of photodiodes, with 2 first photodiodes configured to detect light of a first wavelength and 2 second photodiodes configured to detect light of a second wavelength, each first photodiode positioned adjacent to the second photodiodes; and a second layer overlapping the first layer, the second layer is organic, having a plurality of organic photodiodes configured to detect light of a third wavelength, each organic photodiode positioned to partially overlap 2 first photodiodes and 2 second photodiodes of the first layer. According to an embodiment, the area of overlap of each of the partially overlapped first photodiodes and second photodiodes is substantially the same. 
         [0006]    According to an embodiment of the present inventive concept, the image sensor further includes a circuit part configured to read the detected light from the first and second photodiodes of the first layer, the circuit part positioned relative to the semiconductor substrate for front side illumination, wherein the circuit part is positioned between the first layer and the second layer. The image sensor further including a color filter positioned between the first layer and the second layer. 
         [0007]    According to an embodiment of the present inventive concept, the image sensor may further include a circuit part configured to read the detected light of the first layer, the circuit part positioned relative to the semiconductor substrate for back side illumination. 
         [0008]    According to an embodiment of the present inventive concept, the image sensor may further include a floating diffusion region formed adjacent to each photo diode on the semiconductor substrate, each floating diffusion region is shared by an organic photo diode. 
         [0009]    The image sensor may further include a first readout circuit configured to read the light detected by each photo diode on the semiconductor substrate and a second readout circuit configured to read the light detected by each organic photo diode. 
         [0010]    According to an embodiment of the present inventive concept, an image sensor is provided, comprising: a first layer having a plurality of first photodiodes and a plurality of second photodiodes formed on a semiconductor substrate, the first photodiodes configured to detect light of a first wavelength and the second photodiodes configured to detect light of a second wavelength, wherein the first photodiodes and the second photodiodes are alternately positioned with each of the first photodiodes positioned adjacent to a second photodiode and vice versa; and a second layer overlapping the first layer, the second layer is organic, having a plurality of organic photodiodes configured to detect light of a third wavelength, wherein the organic photodiodes are skewed with respect to alignment with the first photodiodes and the second photodiodes when viewed perpendicularly to the semiconductor substrate, wherein the light of the third wavelength is green. 
         [0011]    According to an embodiment of the present inventive concept, a plurality of storage regions is formed in the semiconductor substrate, each of the storage regions corresponding to a photodiode configured to store electrical charges transmitted through a corresponding metallic contact. 
         [0012]    According to an embodiment of the present inventive concept, the skew in alignment between the organic photodiodes and the first and second photo pixels is about 50% in width and length of a photodiode. 
         [0013]    The image sensor may further include a circuit part configured to read the detected light of the first layer, the circuit part positioned relative to the semiconductor substrate for front side illumination, and may further include a color filter positioned between the first layer and the second layer. 
         [0014]    According to an embodiment of the present inventive concept, the image sensor may include a circuit part configured to read the detected light of the first layer, the circuit part positioned relative to the semiconductor substrate for back side illumination. 
         [0015]    According to an embodiment of the present inventive concept, the number of photodiodes on the semiconductor substrate is the same as the number of organic photodiodes on the second layer. 
         [0016]    According to an embodiment of the present inventive concept, a method of forming an image sensor is provided, comprising: forming a first layer having a plurality of first photodiodes and a plurality of second photodiodes on a semiconductor substrate, the first photodiodes configured to detect light of a first wavelength and the second photodiodes configured to detect light of a second wavelength including positioning the first photodiodes and the second photodiodes alternately with each of the first photodiodes positioned adjacent to a second photodiode and vice versa; and forming a second layer overlapping the first layer, the second layer is organic, having a plurality of organic photodiodes configured to detect light of a third wavelength, wherein the organic photodiodes are skewed with respect to alignment with the first photodiodes and the second photodiodes when viewed perpendicularly to the semiconductor substrate. 
         [0017]    The method may further include positioning the semiconductor substrate in between a circuit part configured to read the detected light of the first layer and the second layer. 
         [0018]    The method may include forming color filters over the semiconductor substrate; and forming photo-electric conversion regions of the organic material on pixel electrodes. According to an embodiment of the present inventive concept, a method of processing image detection data comprising each pixel having four overlapped sections, each section having overlapped one pixel on the first layer and one pixel on the second layer, with data detected represented by G=GS/4; B=B 1 S/4; and R=avg(R 2 S/4+R 1 S/4). According to an embodiment of the present inventive concept, a portable electronic device is provided, comprising: an image processing device; an optical lens; a digital signal processor; a display; and an image sensor, comprising a first layer having a plurality of first photodiodes and a plurality of second photodiodes formed on a semiconductor substrate, the first photodiodes configured to detect light of a first wavelength and the second photodiodes configured to detect light of a second wavelength, wherein the first photodiodes and the second photodiodes are alternately positioned with each of the first photodiodes positioned adjacent to a second photodiode and vice versa; and a second layer overlapping the first layer, the second layer is organic, having a plurality of organic photodiodes configured to detect light of a third wavelength, wherein the organic photodiodes are skewed with respect to alignment with the first photodiodes and the second photodiodes when viewed perpendicularly to the semiconductor substrate. 
         [0019]    The portable electronic device may further include a wireless transceiver configured to transmit and receive signals wirelessly. 
         [0020]    The portable electronic device may further include a memory, wherein the memory is a DRAM or a NAND flash memory. 
         [0021]    According to an embodiment of the present inventive concept, the portable electronic device may be embodied in one of a digital camera, a camcorder, a mobile phone, a smart phone, or a tablet personal computer (PC). 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0022]    Illustrative, non-limiting example embodiments will be more clearly understood from the following detailed description taken in conjunction with the accompanying drawings. 
           [0023]      FIG. 1  shows a structure of an image sensor according to an example embodiment of the present inventive concept; 
           [0024]      FIGS. 2 to 4  depict embodiments of an image sensor including a green pixel disposed to overlap other pixels; 
           [0025]      FIG. 5  is a cross-sectional view of the image sensor of  FIG. 2  taken along line V-V′, embodied in a frontside illumination (FSI) manner; 
           [0026]      FIG. 6  is a top view of a green pixel partially overlapped with a red pixel or a blue pixel, according to an embodiment of the present inventive concept; 
           [0027]      FIG. 7  shows a semiconductor substrate and a circuit part of the image senor shown in  FIG. 5 ; 
           [0028]      FIG. 8  is a cross-sectional view of the image sensor of  FIG. 2 , taken along line V-V′, embodied in a backside illumination (BSI) manner; 
           [0029]      FIG. 9  is an example embodiment of a readout circuit including a green pixel and a red pixel; 
           [0030]      FIG. 10  is an example embodiment of the readout circuit including a green pixel and a red pixel; 
           [0031]      FIG. 11  is a flow diagram of a method of manufacturing an image sensor according to an example embodiment of the present inventive concept; 
           [0032]      FIG. 12  is a block view of an image processing device including an image sensor according to an embodiment of the present inventive concept; 
           [0033]      FIG. 13  is a flow diagram showing of an signal processing operation of image signals from an image sensor according to an embodiment of the present inventive concept; and 
           [0034]      FIG. 14  is a block view of a portable electronic device including an image processing device and an image sensor according to an embodiment of the present inventive concept. 
       
    
    
     DETAILED DESCRIPTION OF EMBODIMENTS 
       [0035]    Various example embodiments will be described more fully hereinafter with reference to the accompanying drawings, in which some example embodiments are shown. The present inventive concept may, however, be embodied in many different forms and should not be construed as limited to the example embodiments set forth herein. In the drawings, the sizes and relative sizes of layers and regions may be exaggerated for clarity. Like numerals refer to like elements throughout. 
         [0036]    It will be understood that, although the terms first, second, third etc. may be used herein to describe various elements, these elements should not be limited by these terms. These terms are used to distinguish one element from another. Thus, a first element discussed below could be termed a second element without departing from the teachings of the present inventive concept. As used herein, the term “and/or” includes any and all combinations of one or more of the associated listed items. 
         [0037]    It will be understood that when an element is referred to as being “connected” or “coupled” to another element, it can be directly connected or coupled to the other element or intervening elements may be present. In contrast, when an element is referred to as being “directly connected” or “directly coupled” to another element, there are no intervening elements present. Other words used to describe the relationship between elements should be interpreted in a like fashion (e.g., “between” versus “directly between,” “adjacent” versus “directly adjacent,” etc.). 
         [0038]    The terminology used herein is for the purpose of describing particular example embodiments only and is not intended to be limiting of the present inventive concept. As used herein, the singular forms “a,” “an” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. 
         [0039]    It should also be noted that in some alternative implementations, the functions/acts noted in the blocks may occur out of the order noted in the flowcharts. For example, two blocks shown in succession may in fact be executed substantially concurrently or the blocks may sometimes be executed in the reverse order, depending upon the functionality/acts involved. 
         [0040]    Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this inventive concept belongs. It will be further understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the relevant art and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein. 
         [0041]      FIG. 1  shows a structure of an image sensor according to an example embodiment of the present inventive concept; 
         [0042]    Referring to  FIG. 1 , an image sensor  100 A, which may be referred to as a pixel array, includes a first layer  100 BT including a plurality of blue B and red R pixels, and a second layer  100 TP including a plurality of green pixels G. 
         [0043]    The second layer  100 TP and the first layer  100 BT are partially overlapped with each other. The first layer  100 BT may be referred to as an overlapped plane, and the second layer  100 TP may be referred to as an overlapping plane. As shown, the overlapping of the first and second layer is not a direct overlap; rather, the overlapping is skewed so that each green pixel G overlaps a portion of two blue pixels B and two red pixels R. 
         [0044]    Each of the plurality of green pixels G is partially overlapped with each of n*n pixels among a plurality of B and R pixels, wherein n is a natural number greater than 1. For purposes of illustration, n is 2 in the present embodiment. 
         [0045]    ‘R’ indicates a red pixel which may generate an electrical signal corresponding to red wavelengths (or red color range). ‘B’ indicates a blue pixel which may generate an electrical signal corresponding to blue wavelengths (or blue color range). ‘G’ indicates a green pixel which may generate an electrical signal corresponding to green wavelengths (or green color range). 
         [0046]      FIGS. 2 to 4  depict structures of an image sensor including a green pixel disposed so as to be partially overlapped with each of the n*n pixels. 
         [0047]    Referring to  FIGS. 1 and 2 , an image sensor  100 B corresponding to a portion of the image sensor  100 A includes 2*2 pixels B 1 , R 1 , R 2 , and B 2  disposed in the first layer  100 BT, and a green pixel G arranged in the second layer  100 TP. 
         [0048]    The plurality of pixels B and R arranged in the first layer  100 BT of  FIG. 1  include 2*2 pixels with alternating B and R pixels, for example, B 1 , R 1 , R 2  and B 2 . Each of the 2*2 pixels B 1 , R 1 , R 2 , and B 2  may be partially overlapped with the green pixel G. Each of overlapping regions  11 ,  12 ,  13 , and  14  of the green pixel G partially overlapped with each of the 2*2 pixels B 1 , R 1 , R 2 , and B 2 . 
         [0049]    The sum of the partially overlapped overlapping regions  11 ,  12 ,  13 , and  14  is equal to the size of the green pixel G, with each overlapped portion in B 1 , R 1 , R 2 , and B 2  having substantially the same size. As shown in  FIGS. 1 and 2 , the skew in the alignment of the green pixel G with respect to the pixels B and R is about 50% in width and length of an overlapped pixel, when viewed perpendicularly to the first layer or the second layer. In other embodiments, the amount of skew of the green pixel G layer with the B and R pixel layer may vary to not overlap precisely equally over the B and R pixels. 
         [0050]    In a section (or region)  11  where two pixels G+B 1  are overlapped, a signal corresponding to green wavelengths (or a green region of visible light) and a signal corresponding to blue wavelengths (or a blue region of visible light) are generated. 
         [0051]    In a section (or region)  12  where two pixels G+R 1  are overlapped with each other, a signal corresponding to green wavelengths and a signal corresponding to red wavelengths (or a red region of visible light) are generated. 
         [0052]    In a section (or region)  13  where two pixels G+R 2  are overlapped with each other, a signal corresponding to green wavelengths and a signal corresponding to red wavelengths are generated. 
         [0053]    In a section (or region)  14  where two pixels G+B 2  are overlapped, a signal corresponding to green wavelengths and a signal corresponding to blue wavelengths are generated. 
         [0054]    Referring to  FIGS. 1 and 3 , an image sensor  100 C corresponding to a portion of the image sensor  100 A includes a red pixel R disposed in the first layer  100 BT and 2*2 green pixels G 1 , G 2 , G 3 , and G 4  disposed in the second layer  100 TP. 
         [0055]    A plurality of green pixels arranged on the second layer  100 TP of  FIG. 1  includes 2*2 green pixels G 1 , G 2 , G 3 , and G 4 . 
         [0056]    A portion of the plurality of green pixels of  FIG. 1  may be expressed as the 2*2 green pixels G 1 , G 2 , G 3 , and G 4 . Each of the 2*2 green pixels G 1 , G 2 , G 3 , and G 4  and a red pixel R is partially overlapped with each other. 
         [0057]    In a section  21  where two pixels R+G 1  are overlapped with each other, a signal corresponding to red wavelengths and a signal corresponding to green wavelengths are generated. 
         [0058]    In a section  22  where two pixels R+G 2  are overlapped with each other, a signal corresponding to red wavelengths and a signal corresponding to green wavelengths are generated. 
         [0059]    In a section  23  where two pixels R+G 3  are overlapped with each other, a signal corresponding to red wavelengths and a signal corresponding to green wavelengths are generated. 
         [0060]    In a section  24  where two pixels R+G 4  are overlapped with each other, a signal corresponding to red wavelengths and a signal corresponding to green wavelengths are generated. 
         [0061]    Referring to  FIGS. 1 and 4 , an image sensor  100 D corresponding to a portion of the image sensor  100 A includes a blue pixel B disposed on the first layer  100 BT and 2*2 green pixels G 1 , G 2 , G 3 , and G 4  disposed on the second layer  100 TP. 
         [0062]    A plurality of green pixels arranged on the second layer  100 TP of  FIG. 1  includes 2*2 green pixels G 1 , G 2 , G 3 , and G 4 . 
         [0063]    A portion of the plurality of green pixels G of  FIG. 1  may be expressed as the 2*2 green pixels G 1 , G 2 , G 3 , and G 4 . Each of the 2*2 green pixels G 1 , G 2 , G 3 , and G 4  and the blue pixel B are partially overlapped with each other. 
         [0064]    Each overlapping region  31 ,  32 ,  33 , and  34  of the 2*2 green pixels G 1 , G 2 , G 3 , and G 4  are partially overlapped with the blue pixel B. 
         [0065]    In a section  31  where two pixels B+G 1  are overlapped with each other, a signal corresponding to blue wavelengths and a signal corresponding to green wavelengths are generated. 
         [0066]    In a section  32  where two pixels B+G 2  are overlapped with each other, a signal corresponding to blue wavelengths and a signal corresponding to green wavelengths are generated. 
         [0067]    In a section  33  where two pixels B+G 3  are overlapped with each other, a signal corresponding to blue wavelengths and a signal corresponding to green wavelengths are generated. 
         [0068]    In a section  34  where two pixels B+G 4  are overlapped with each other, a signal corresponding to blue wavelengths and a signal corresponding to green wavelengths are generated. 
         [0069]    The 2*2 pixels as shown and described with reference to  FIGS. 1 to 4  are duplicated throughout the first layer  100 BT. 
         [0070]      FIG. 5  is an embodiment of an image sensor embodied in a frontside illumination (FSI) manner, shown in a cross-sectional view of the image sensor of  FIG. 2  taken along line V-V′. Referring to  FIGS. 1, 2, and 5 , a blue photo-electric conversion region  201 , a red photo-electric conversion region  202 , and a plurality of green storage regions  203 ,  205 , and  207  are formed in a semiconductor substrate  200 , which may be a silicon substrate. 
         [0071]    Each of the plurality of green storage regions  203 ,  205 , and  207  accumulates or stores electrical charges transmitted through each metallic contact  311 ,  313 , and  315 . 
         [0072]    A circuit part  300  may be formed on or over the semiconductor substrate  200 . 
         [0073]    Circuitry disposed in the circuit part  300  includes transistors for transmitting charges accumulated in each region  201 ,  202 ,  203 ,  205 , and  207  to respective floating diffusion regions FD. The circuit part  300  also includes metal interconnects MC connecting each region  201 ,  202 ,  203 ,  205 , and  207  to a readout circuit. 
         [0074]    Color filters  321  and  323  may be formed on or over the circuit part  300 . 
         [0075]    A blue color filter  321  allows blue wavelengths which have passed through pixel electrodes  331  and  333  to pass through the blue photo-electric conversion region  201 . 
         [0076]    The blue photo-electric conversion region  201  performs a photo-electric conversion operation based on the blue wavelengths. Pixel electrodes  331  and  333 , which are separated from each other, are formed on the blue color filter  321 . 
         [0077]    For convenience of description in  FIG. 5 , it is illustrated that the length where a blue color filter  321  and a pixel electrode  331  are overlapped with each other is the same as the length where the blue color filter  321  and the pixel electrode  333  are overlapped with each other; however, according to other embodiments, the amount of overlap between the G pixels with the B and R pixels can vary and may not be the same, depending on the variation in the skew between the layers  100 BT and  100 TP. 
         [0078]    Portions of electrodes  331  and  333  cover corresponding color filter  321 , and portions of electrodes  331  and  335  cover corresponding color filter  323 . 
         [0079]    A red color filter  323  allows red wavelengths which have passed through the pixel electrodes  331  and  335  to pass through the red photo-electric conversion region  202 . The red photo-electric conversion region  202  performs a photo-electric conversion operation based on the red wavelengths. 
         [0080]    The pixel electrodes  331  and  335  separated from each other are formed on the red color filter  323 . 
         [0081]    For convenience of description in  FIG. 5 , it is illustrated that the length where a red color filter  323  and a pixel electrode  331  are overlapped with each other is the same as the length where the red color filter  323  and the pixel electrode  335  are overlapped with each other; however, according to other embodiments, the amount of overlap between the G pixels with the B and R pixels can vary and may not be the same, depending on the variation in the skew between the layers  100 BT and  100 TP. 
         [0082]    The pixel electrodes  331 ,  333 , and  335  that are formed on color filters  321  and  323  are separated from each other. 
         [0083]    On each pixel electrode  331 ,  333 , and  335 , a photo-electric conversion region  340  is formed. The photo-electric conversion region  340  is made of an organic material. The photo-electric conversion region  340  performs a photo-electric conversion operation based on green wavelengths, generates electrical charges, and allows blue wavelengths and red wavelengths to pass through. 
         [0084]    The photo-electric conversion region  340  may include an electron donating organic material and/or an electron accepting organic material. For example, a first organic layer may be formed on each pixel electrode  331 ,  333 , and  335 , and a second organic layer may be formed on the first organic layer. 
         [0085]    When the first organic layer includes an electron donating organic material, the second organic layer may be formed to include an electron accepting organic material, or vice versa. For example, when the first organic layer is embodied from one of a p-type organic material and a n-type organic material, e.g., a n-type organic material, the second organic layer may be embodied from the other of the p-type organic material and the n-type organic material, e.g., the p-type organic material. 
         [0086]    Accordingly, the first organic layer and the second organic layer may form a hetero p-n junction. Here, the electron donating organic material is a material which may generate a donor ion in response to light, and the electron accepting organic material is a material which may generate an acceptor ion in response to the light. 
         [0087]    According to another example embodiment, the photo-electronic conversion region  340  of an organic material may be embodied from an organic material which is a compound (or mixed) of the electron donating organic material and the electron accepting organic material. 
         [0088]    Each pixel electrode  331 ,  333 , and  335  collects electrical charges generated based on green wavelengths in the photo-electric conversion region  340  of an organic material and allows blue wavelengths and red wavelengths to pass through. 
         [0089]    Each pixel electrode  331 ,  333 , and  335  may be embodied in a transparent electrode. For example, each pixel electrode  331 ,  333 , and  335  may be embodied in zinc oxide (ZnO) or Indium tin oxide or tin-doped indium oxide (ITO). Each pixel electrode  331 ,  333 , and  335  may be embodied in a pixel electrode film. 
         [0090]    Electrical charges collected by each pixel electrode  331 ,  333 , and  335  are transmitted to each green storage region  203 ,  205 , and  207  through each wiring or each contact plug  311 ,  313 , and  315 . 
         [0091]    A common electrode  350  is formed on the photo-electric conversion region  340  of an organic material. The common electrode  350  supplies a bias voltage to the photo-electric conversion region  340  of an organic material. 
         [0092]    The common electrode  350  may be embodied in a transparent electrode, ZnO, or ITO. The common electrode  350  may be embodied in a pixel electrode film. 
         [0093]    The green pixel G includes the pixel electrode  331 , the photo-electric conversion region of an organic material  340 , and the common electrode  350 . The green pixel G may be defined by the pixel electrode  331 . 
         [0094]      FIG. 6  is a top view of a green pixel and a red pixel which are partially overlapped with each other, or a top view of a green pixel and a blue pixel which are partially overlapped with each other. In  FIG. 6 , OPD denotes the photo-electric conversion region  340  of an organic material or a photo diode of an organic material, B_PD denotes a blue photo-electric conversion region  201  or a photodiode related to (or defined by) the blue photo-electric conversion region  201 , and R_PD denotes a red photo-electric conversion region  202  or a photo diode related to (or defined by) the red photo-electric conversion region  202 . 
         [0095]    FD denotes a floating diffusion region, and TG 1 , TG 2 , TG 3 , and TG 4  each denote a transfer transistor or a gate electrode of a transfer gate. RG denotes a reset transistor or a gate electrode of a reset gate. 
         [0096]    For example, a green pixel including OPD and a blue pixel including B_PD may share the floating diffusion region FD. Moreover, the green pixel including OPD and a red pixel including R_PD may share a floating diffusion region FD. The floating diffusion region FD may be embodied in the semiconductor substrate  200 , and TG 1 , TG 2 , TG 3 , and TG 4  may be embodied in the circuit part  300 . 
         [0097]      FIG. 7  is a diagram of the semiconductor substrate and the circuit part  300  of  FIG. 5 . As illustrated in  FIG. 7 , each floating diffusion region corresponding to each region  201 ,  202 ,  203 ,  205 , and  207  may be formed in the semiconductor substrate  200 . 
         [0098]      FIG. 8  shows a cross-sectional view of an image sensor embodied in a backside illumination (BSI) manner according to an embodiment of the present inventive concept. 
         [0099]    Referring to  FIGS. 1, 2, and 8 , a blue photo-electric conversion region  401 , a red photo-electric conversion region  402 , a plurality of green storage regions  406 ,  407 , and  408  are formed in the semiconductor substrate  400 . 
         [0100]    Each of the plurality of green storage regions  406 ,  407 , and  408  accumulates or stores electrical charges transmitted through each metal or each contact plug  403 ,  404 , and  405 . Each floating diffusion region corresponding to each region  401 ,  402 ,  406 ,  407 , and  408  may be formed in the semiconductor substrate  400 . 
         [0101]    A circuit part  410  may be formed under the semiconductor substrate  400 . A gate electrode of each transmission transistor may be embodied in the circuit part  410 . The transmission transistor transmits charges accumulated in each region  401 ,  402 ,  406 ,  407 , and  408  to each floating diffusion region. Metal interconnectors MC are embodied in the circuit part  410  to transmit the charges accumulated in each region  401 ,  402 ,  406 ,  407 , and  408  to a readout circuit. 
         [0102]    Color filters  421  and  423  may be formed on or over the semiconductor substrate  400 . The color filters  421  and  423  are embodied at an opposite side of the circuit part  410  based on the semiconductor substrate  400 . 
         [0103]    A blue color filter  421  allows blue wavelengths which have passed through pixel electrodes  431  and  433  to pass through the blue photo-electric conversion region  401 . The blue photo-electric conversion region  401  performs a photo-electric conversion operation based on the blue wavelengths. The pixel electrodes  431  and  433  which are separated from each other are formed on the blue color filter  421 . 
         [0104]    For convenience of description in  FIG. 8 , it is illustrated that the length where the blue color filter  421  and the pixel electrode  431  are overlapped with each other is essentially the same length where the blue color filter  421  and the pixel electrode  433  are overlapped with each other; however, the length of overlapping may not be the same in other example embodiments. 
         [0105]    A red color filter  423  allows red wavelengths which have passed through pixel electrodes  431  and  435  to pass through a red photo-electric conversion region  402 . The red photo-electric conversion region  402  performs a photo-electric conversion operation based on the red wavelengths. The pixel electrodes  431  and  435  which are separated from each other are formed on the red color filter  423 . 
         [0106]    For convenience of description in  FIG. 8 , it is illustrated that the length where the red color filter  423  and the pixel electrode  431  are overlapped with each other is essentially the same length where the red color filter  423  and the pixel electrode  435  are overlapped with each other; however, the length of overlapping may not be the same in other example embodiments. 
         [0107]    Each pixel electrode  431 ,  433 , and  435  is separated from each other. The pixel electrodes may be formed on color filters  421  and  423 . The photo-electric conversion region  440  of an organic material may be formed on each pixel electrode  431 ,  433 , and  435 . 
         [0108]    Each pixel electrode  431 ,  433 , and  435  collects electrical charges generated based on green wavelengths in the photo-electric conversion region  440  of an organic material, and allows blue wavelengths and red wavelengths to pass through. Each pixel electrode  431 ,  433 , and  435  may be embodied in a transparent electrode such as ZnO or ITO. Each pixel electrode  431 ,  433 , and  435  may be embodied in a pixel electrode film. 
         [0109]    Electrical charges collected by each pixel electrode  431 ,  433 , and  435  are transmitted to each green storage region  406 ,  407 , and  408  through each wiring or each contact plug  403 ,  404 , and  405 . 
         [0110]    A common electrode  450  is formed on the photo-electric conversion region  440  of an organic material. The common electrode  450  supplies a bias voltage to the photo-electric conversion region  440  of an organic material. The common electrode  450  may be embodied in a transparent electrode such as ZnO or ITO. The common electrode  450  may be embodied in a pixel electrode film. 
         [0111]    A green pixel G includes the pixel electrode  431 , the photo-electric conversion region  440  of an organic material, and the common electrode  450 . The green pixel G is defined by the pixel electrode  431 . 
         [0112]    A configuration of components as illustrated in  FIGS. 6 and 7  and described in connection therewith is applicable to an image sensor of  FIG. 8 . 
         [0113]      FIG. 9  is an example embodiment of a readout circuit including a green pixel and a red pixel. Referring to  FIGS. 5 to 9 , OPD and R_PD share one floating diffusion region FD. Moreover, in another example embodiment, OPD and B_PD share one floating diffusion region FD. The floating diffusion region FD may be referred to as a floating diffusion node. 
         [0114]    From a pixel viewpoint, a green pixel and a red pixel share one floating diffusion region FD. 
         [0115]    A readout circuit includes two transmission transistors TG 1  and TG 2 , the floating diffusion region FD, a reset transistor RX, a drive transistor DX, and a selection transistor SX. 
         [0116]    A first transmission transistor TG 1  operates in response to a first transmission control signal TS 1 , a second transmission transistor TG 2  operates in response to a second transmission control signal TS 2 , the reset transistor RX operates in response to a reset control signal RS, and the selection transistor SX operates in response to a selection signal SEL. 
         [0117]    When activation time of the first transmission control signal TS 1  and activation time of the second transmission control signal TS 2  are adequately controlled, a signal corresponding to electrical charges generated by OPD and a signal corresponding to electrical charges generated by R_PD may be transmitted to a column line COL according to an operation of each transistor DX and SX. Here, OPD, R_PD, or B_PD may be embodied in a photo transistor, a photo gate, a pinned photo diode (PPD), or a combination of these. 
         [0118]      FIG. 10  is another example embodiment of a readout circuit including a green pixel and a red pixel. 
         [0119]    Referring to  FIGS. 5, 8, and 10 , a first readout circuit which reads electrical charges generated by R_PD (or B_PD) and a second readout circuit which reads electrical charges generated by OPD are separated from each other. From a pixel viewpoint, a green pixel and a red pixel are separated from each other. The first readout circuit includes a first transmission transistor TGA, a first floating diffusion region FD 1 , a first reset transistor RX 1 , a first drive transistor DX 1 , and a first selection transistor SX 1 . 
         [0120]    The first transmission transistor TGA operates in response to a first transmission control signal TS 1 , the first reset transistor RX 1  operates in response to a first reset control signal RS 1 , and the first selection transistor SX 1  operates in response to a first selection signal SEL 1 . 
         [0121]    The second readout circuit includes a second transmission transistor TGB, a second floating diffusion region FD 2 , a second reset transistor RX 2 , a second drive transistor DX 2 , and a second selection transistor SX 2 . 
         [0122]    The second transmission transistor TGB operates in response to a second transmission control signal TS 2 , the second reset transistor RX 2  operates in response to a second reset control signal RS 2 , and the second selection transistor SX 2  operates in response to a second selection signal SEL 2 . 
         [0123]    When activation time of the first transmission control signal TS 1  and activation time of the second transmission control signal TS 2  are adequately controlled, a signal corresponding to electrical charges generated by OPD and a signal corresponding to electrical charges generated by R_PD may be transmitted to a column line COL according to an operation of each transistor DX 1  and SX 1 , and DX 2  and SX 2 . 
         [0124]      FIG. 11  is a flowchart describing a method for manufacturing an image sensor according to an example embodiment of the present inventive concept. 
         [0125]    A method for manufacturing an image sensor in an FSI manner according to an example embodiment of the present inventive concepts will be described referring to  FIGS. 1 to 7, and 11 . 
         [0126]    The blue photo-electric conversion region  201 , the red photo-electric conversion region  202 , and a plurality of green storage regions  203 ,  205 , and  207  are formed in the semiconductor substrate  200  (S 110 ). 
         [0127]    The circuit part  300  is formed on or above the semiconductor substrate  200 (S 120 ). 
         [0128]    Color filters  321  and  323  are formed on the circuit part  300  (S 130 ). 
         [0129]    Pixel electrodes  331 ,  333 , and  335  which are separated from each other are formed to partially overlap with each of the color filters  321  and  323 (S 140 ). 
         [0130]    The photo-electric conversion region  340 , made of an organic material, is formed on each pixel electrode  331 ,  333 , and  335  (S 150 ). The common electrode  350  is formed on the photo-electric conversion region  340  of an organic material (S 160 ). 
         [0131]    A method for manufacturing an image sensor in a BSI manner according to an example embodiment of the present inventive concepts will be described referring to  FIGS. 1 to 4, 6, 7, 8, and 11 . 
         [0132]    A blue photo-electric conversion region  401 , a red photo-electric conversion region  402 , and a plurality of green storage regions  406 ,  407 , and  408  are formed in the semiconductor substrate  400  (S 110 ). 
         [0133]    The circuit part  410  is formed under the semiconductor substrate  400  (S 120 ). 
         [0134]    The color filters  421  and  423  are formed on the semiconductor substrate  400  at the opposite side of the circuit part  410  (S 130 ). 
         [0135]    Pixel electrodes  431 ,  433 , and  435  are formed, which are separated from each other, to partially overlap with each of the color filter  421  and  423  (S 140 ). 
         [0136]    The photo-electric conversion region  440  of an organic material is formed on each pixel electrode  431 ,  433 , and  435  (S 150 ). 
         [0137]    The common electrode  450  is formed on the photo-electric conversion region  440  of an organic material (S 160 ). 
         [0138]      FIG. 12  is a block diagram of an image processing device including an image sensor according to at least one of the above described embodiments. 
         [0139]    Referring to  FIGS. 1 and 12 , an image processing device  500  may be embodied in a portable electronic device, e.g., a digital camera, a camcorder, a mobile phone, a smart phone, or a tablet personal computer (PC). 
         [0140]    The image processing device  500  includes an optical lens  503 , a digital signal processor  600 , a display  640 , and an image sensor  510  according to at least one of the above described embodiments. 
         [0141]    According to an example embodiment, the image processing device  500  may or may not include the optical lens  503 . 
         [0142]    The CMOS image sensor  510  generates image data IDATA for an object  501  incident through the optical lens  503 . 
         [0143]    The CMOS image sensor  510  includes a pixel array  100 , a row driver  520 , a timing generator  530 , a correlated double sampling (CDS) block  540 , a comparison block  542 , and an analog-to-digital conversion (ADC) block  544 , a control register block  550 , a ramp signal generator  560 , and a buffer  570 . 
         [0144]    The pixel array  100  collectively includes the image sensor  100 A,  100 B,  100 C, and  100 D described referring to  FIGS. 1 to 4 . 
         [0145]    The pixel array  100  includes pixels  10  arranged in a matrix form. As described referring to  FIGS. 1 to 11 , the pixel array  100  includes a first layer  100 BT having a plurality of pixels R and B, and a second layer  100 TP having a plurality of green pixels G. 
         [0146]    The row driver  520  drives control signals (at least two of TS 1 , TS 2 , RS, RS 1 , RS 2 , SEL, SEL 1 , and/or SEL 2 ) for controlling an operation of each of the pixels  10  to the pixel array  100  according to a control of the timing generator  530 . 
         [0147]    The timing generator  530  controls an operation of the row driver  520 , the CDS block  540 , the ADC block  542 , and the ramp signal generator  560 . 
         [0148]    The CDS block  540  performs correlated double sampling on a pixel signal P 1  to Pm, where m is a natural number, output from each of the plurality of column lines embodied in the pixel array  100 . 
         [0149]    The comparison block  542  compares each of the plurality of correlated double sampled pixel signals output from the CDS block  540  with a ramp signal output from the ramp signal generator  560 , and outputs a plurality of comparison signals. 
         [0150]    The ADC block  544  converts each of the comparison signals output from the comparison block  542  into a digital signal, and outputs a plurality of digital signals to the buffer  570 . 
         [0151]    The control register block  550  controls an operation of the timing generator  530 , the ramp signal generator  560 , and the buffer  570  according to a control of a digital signal processor  600 . The buffer  570  transmits image data IDATA corresponding to the plurality of digital signals output from the ADC block  544  to the digital signal processor  600 . 
         [0152]    The digital signal processor  600  includes an image signal processor  610 , a sensor controller  620 , and an interface  630 . The image signal processor  610  controls a sensor controller  620  controlling the control register block  550 , and an interface  630 . 
         [0153]    According to an example embodiment, the CMOS image sensor  510  and the digital signal processor  600  may be embodied in one package, e.g., a multi-chip package. According to another example embodiment, the CMOS image sensor  510  and the image signal processor  610  may be embodied in one package, e.g., a multi-chip package. 
         [0154]    The image signal processor  610  processes image data IDATA transmitted from the buffer  570 , and transmits the processed image data to the interface  630 . The sensor controller  620  generates various control signals for controlling the control register block  550  according to a control of the image signal processor  610 . 
         [0155]    The interface  630  transmits image data processed by the image signal processor  610  to the display  640 . The display  640  displays image data output from the interface  630 . 
         [0156]    The display  640  may be embodied in thin film transistor-liquid crystal display (TFT-LCD), a light emitting diode (LED) display, an organic LED (OLED) display, an active-matrix OLED (AMOLED) display, or a flexible display. 
         [0157]      FIG. 13  is a flowchart describing an exemplary operation of an image signal processor in processing and interpolating the image signals received from the image sensor. According to an exemplary embodiment of the present inventive concept and referring to  FIGS. 1 to 13 , the image signal processor  610  performs processing twice. As an example, processing of the overlapping region  11  may yield G′=GS/4, B′=B 1 S/4, R′=avg(R 2 S/4+R 1 S/4), wherein G′ represents ¼ of the entire G pixel, B′ is ¼ of the blue pixel B 1  and R′ is the combination and average of the ¼ regions of R 1  and R 2 . 
         [0158]    A method for acquiring a green signal GS′ and GS″ is described referring to  FIGS. 2, 12, and 13 . A green image signal output from each overlapping region  11 ,  12 ,  13 , and  14  may be different from each other due to variations in a process, a voltage, and temperature (PVT); however, for convenience of description, it is assumed that a green image signal GS output from each overlapping region  11 ,  12 ,  13 , and  14  is the same as each other. 
         [0159]    A first processing for output signals of each overlapping region  11 ,  12 ,  13 , and  14  may be performed simultaneously or at different times. The first processing means generation of a blue signal and a red signal from the first layer and generation of a green signal from the second layer. 
         [0160]    The second processing of the overlapping region  11  may yield G′=GS/4, B′=BIS/4, R′=avg(R 2 S/4+R 1 S/4). 
         [0161]    The second processing, e.g., interpolation, on output signals of each overlapping region  11 ,  12 ,  13 , and  14  may utilize known interpolation processes such as for Bayer, Panchromatic or EXR filters. According to exemplary embodiments of the present inventive concept, a modified bilinear interpolation process is utilized; further, such processing can be performed simultaneously or at different times for the red, green, and blue signals. 
         [0162]      FIG. 14  is a block diagram of portable electronic device including an image processing device and an image sensor according to the above described embodiments. 
         [0163]    Referring to  FIGS. 1 and 14 , the image processing device  200  may be embodied in a portable electronic device which may use or support a mobile industry processor interface (MIPI®) or high speed serial interface. 
         [0164]    The portable electronic device may be embodied in a laptop computer, a personal digital assistant (PDA), a portable media player (PMP), a mobile phone, a smart phone, a tablet personal computer (PD), or a digital camera. 
         [0165]    The image processing device  700  includes an application processor (AP)  710 , an image sensor  120 , and a display  730 . A camera serial interface (CSI) host  713  embodied in an AP  710  may perform a serial communication with a CSI device  101  of the image sensor  100  through a camera serial interface (CSI). 
         [0166]    According to an example embodiment, a de-serializer (DES) may be embodied in the CSI host  713 , and a serializer (SER) may be embodied in the CSI device  101 . The image sensor  100  may denote the image sensor  100 A described referring to  FIGS. 1 to 6 . 
         [0167]    A display serial interface (DSI) host  711  embodied in the AP  710  may perform a serial communication with a DSI device  731  of the display  730  through a display serial interface. According to an example embodiment, a serializer (SER) may be embodied in the DSI host  711 , and a de-serializer (DES) may be embodied in the DSI device  731 . Each of the de-serializer (DES) and a serializer (SER) may process an electrical signal or an optical signal. 
         [0168]    The image processing device  700  may further include a radio frequency (RF) chip  740  which may communicate with the AP  710 . A physical layer (PHY)  715  of the AP  710  may transmit or receive data to/from a PHY  741  of a RF chip  740  according to MIPI DigRF. 
         [0169]    The image processing device  700  may further include a GPS receiver  750 , a memory  751  like a dynamic random access memory (DRAM), a data storage device  753  embodied in a non-volatile memory like a NAND flash memory, a mike  755 , or a speaker  757 . 
         [0170]    The image processing device  700  may communicate with an external device using at least one communication protocol or communication standard, e.g., worldwide interoperability for microwave access (WiMAX)  759 , Wireless LAN (WLAN)  761 , ultra-wideband (UWB)  763 , or long term evolution (LTE™)  765 . The image processing device  700  may communicate with an external device using a Bluetooth or WiFi. 
         [0171]    While the inventive concept has been particularly shown and described with reference to exemplary embodiments thereof, it will be understood that various changes in form and details may be made therein without departing from the spirit and scope of the following claims.

Technology Classification (CPC): 7