Abstract:
An image sensor including: a plurality of pixels, wherein a first pixel of the pixels includes: a first photoelectric conversion element; and a first microlens overlapping the first photoelectric conversion element, wherein the first microlens reflects wavelengths of a first region of visible light and allows wavelengths of second and third regions of visible light to pass through to the first photoelectric conversion element.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application claims priority under 35 U.S.C. §119(a) to Korean Patent Application No. 10-2013-0134425 filed on Nov. 6, 2013, the disclosure of which is incorporated by reference herein in its entirety. 
     TECHNICAL FIELD 
     The present inventive concept relates to an image sensor, and more particularly, to an image sensor including a photonic crystal which may increase light transmittance and may be used as a reflective color filter, an operating method thereof, and a data processing system including the image sensor. 
     DISCUSSION OF THE RELATED ART 
     In an image sensor including a color filter per pixel, the color filter may allow only one third of incident visible light to pass through. 
     Due to this loss of incident visible light, the number of photons reaching a photoelectric conversion element formed at a lower part of the color filter is decreased. 
     A photonic crystal may have a bandgap or a photonic bandgap which blocks light of a specific frequency. For example, when two types of materials with different refractive indexes are periodically arranged at about a half wavelength of a specific light, a photonic bandgap which blocks the specific light is generated. 
     SUMMARY 
     An exemplary embodiment of the inventive concept provides an image sensor comprising: first, second and third pixels, the first pixel includes a first microlens overlapping a first photoelectric conversion element, the second pixel includes a second microlens overlapping a second photoelectric conversion element, and the third pixel includes a third microlens overlapping a third photoelectric conversion element, the first, second and third photoelectric conversion elements are formed in a semiconductor substrate; an intermediate layer is disposed on the first, second and third photoelectric conversion elements, the first, second and third microlenses each has a curved surface, protrusions and grooves are arranged in each of the curved surfaces, and the protrusions or the grooves are arranged at uniform intervals in each of the curved surfaces, the first microlens reflects wavelengths of a first region of visible light and allows wavelengths of second and third regions of visible light to pass through to the first photoelectric conversion element, the second microlens reflects the wavelengths of the second region of visible light and allows the wavelengths of the first and third regions of visible light to pass through to the second photoelectric conversion element, and the third microlens reflects the wavelengths of the third region of visible light and allows the wavelengths of the first and second regions of visible light to pass through to the third photoelectric conversion element. 
     The image sensor is a backside illumination (BSI) CMOS image sensor. 
     A dimension of the protrusions or grooves are different from each other between two adjacent pixels. 
     A refractive index of the protrusions is greater than a refractive index of a material disposed in the grooves. 
     The first photoelectric conversion element includes a photodiode, a photo transistor or a photo gate. 
     When the first region of visible light reflected by the first microlens is a red region of visible light, the second and third regions of visible light passing through the first microlens are green and blue regions of visible light, when the first region of visible light reflected by the first microlens is the green region of visible light, the second and third regions of visible light passing through the first microlens are the red and blue regions of visible light, or when the first region of visible light reflected by the first microlens is the blue region of visible light, the second and third regions of visible light passing through the first microlens are the red and green regions of visible light. 
     A horizontal width of the first microlens is greater than a horizontal width of the first photoelectric conversion element. 
     An exemplary embodiment of the inventive concept provides an image sensor comprising: a plurality of pixels, wherein a first pixel of the pixels includes: a first photoelectric conversion element; a first microlens overlapping the first photoelectric conversion element; and a first photonic crystal disposed between the first photoelectric conversion element and the first microlens, wherein the first photonic crystal reflects wavelengths of a first region of visible light passing through the first microlens and allows wavelengths of second and third regions of visible light to pass through to the first photoelectric conversion element. 
     The image sensor is a backside illumination (BSI) CMOS image sensor. 
     The first microlens has a curved surface, protrusions and grooves are arranged in the curved surface, and the protrusions or the grooves are arranged at uniform intervals. 
     The first photonic crystal includes a plurality of unit photonic crystals stacked with respect to each other in a vertical direction. 
     Each of the unit photonic crystals includes protrusions and grooves, and the protrusions or grooves are alternately arranged in the vertical direction. 
     A unit photonic crystal includes protrusions and grooves formed between the protrusions. 
     The protrusions and grooves are alternately arranged. 
     The grooves of a first unit photonic crystal overlap the protrusions of a second unit photonic crystal, wherein the first and second unit photonic crystals are disposed adjacent to each other. 
     A refractive index of a protrusion is greater than a refractive index of a material disposed in a groove. 
     A second pixel of the pixels includes: a second photoelectric conversion element; a second microlens overlapping the second photoelectric conversion element; and a second photonic crystal disposed between the second photoelectric conversion element and the second microlens, wherein the second photonic crystal reflects the wavelengths of the second region of visible light passing through the second microlens and allows the wavelengths of the first and third regions of visible light to pass through to the second photoelectric conversion element. 
     The second photonic crystal includes a plurality of unit photonic crystals stacked with respect to each other in a vertical direction, the unit photonic crystals of the second photonic crystals include protrusions and grooves formed between the protrusions, and a dimension of a protrusion or a groove of the unit photonic crystals of the second photonic crystals is different from a dimension of a protrusion or a groove of the unit photonic crystals of the first photonic crystals. 
     The protrusions and grooves of the unit photonic crystals of the second photonic crystals are alternately arranged in a vertical direction. 
     An exemplary embodiment of the inventive concept provides a data processing system comprising: an image sensor including: a pixel array, the pixel array including a plurality of pixels configured to output pixel signals corresponding to an object; and a readout circuit configured to output a digital image signal corresponding to the pixel signals, wherein a first pixel of the pixels includes: a first photoelectric conversion element; and a first microlens overlapping the first photoelectric conversion element, wherein the first microlens reflects wavelengths of a first region of visible light and allows wavelengths of second and third regions of visible light to pass through to the first photoelectric conversion element. 
     The first microlens includes protrusions and grooves disposed on its surface. 
     The data processing system is included in a mobile device. 
     The data processing system further comprises: a timing generator; a row driver configured to drive control signals for controlling an operation of the pixels according to a control of the timing generator; and a control register block configured to control an operation of the timing generator. 
     The data processing system further comprises a reference signal generator configured to operate according to a control of the timing generator and the control register block. 
     The data processing system further comprises a buffer configured to operate according to a control of the control register block. 
     The data processing system further comprises an image signal processor configured to receive the digital image signal corresponding to the pixel signals output from the readout circuit from the buffer. 
     An exemplary embodiment of the inventive concept provides a data processing system comprising: an image sensor including: a pixel array, the pixel array including a plurality of pixels configured to output pixel signals corresponding to an object; and a readout circuit configured to output a digital image signal corresponding to the pixel signals, wherein a first pixel of the pixels includes: a first photoelectric conversion element; a first microlens overlapping the first photoelectric conversion element; and a first photonic crystal disposed between the first photoelectric conversion element and the first microlens, wherein the first photonic crystal reflects wavelengths of a first region of visible light passing through the first microlens and allows wavelengths of second and third regions of visible light to pass through to the first photoelectric conversion element. 
     The first photonic crystal includes a, plurality of nit photonic crystals arranged in stacked rows. 
     A unit photonic crystal includes protrusions and grooves formed between the protrusions. 
     The data processing system is included in a mobile device. 
     The data processing system further comprises: a timing generator; a row driver configured to drive control signals for controlling an operation of the pixels according to a control of the timing generator; and a control register block configured to control an operation of the timing generator. 
     The data processing system further comprises a reference signal generator configured to operate according to a control of the timing generator and the control register block. 
     The data processing system further comprises a buffer configured to operate according to a control of the control register block. 
     The data processing system further comprises an image signal processor configured to receive the digital image signal corresponding to the pixel signals output from the readout circuit from the buffer. 
     An exemplary embodiment of the inventive concept provides an image sensor comprising: first and second pixels, the first pixel including a first photonic crystal disposed between a first photoelectric conversion element and a first microlens, wherein the first photonic crystal reflects wavelengths of first light passing through the first microlens and allows wavelengths of second and third light to pass through to the first photoelectric conversion element, and the second pixel including a second photonic crystal disposed between a second photoelectric conversion element and a second microlens, wherein the second photonic crystal reflects wavelengths of the second light passing through the second microlens and allows wavelengths of the first light and the third light to pass through to the second photoelectric conversion element, wherein the first photonic crystal includes a plurality of unit photonic crystals, wherein each of the unit photonic crystals includes protrusions and grooves alternately arranged in a horizontal direction, and the unit photonic crystals are stacked with respect to each other in a vertical direction. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The above and other features of the present inventive concept will become more apparent by describing in detail exemplary embodiments thereof, with reference to the accompanying drawings of which. 
         FIG. 1  is a cross-sectional view of pixels of an image sensor according to an exemplary embodiment of the present inventive concept; 
         FIG. 2  is a cross-sectional view of pixels of an image sensor according to an exemplary embodiment of the present inventive concept; 
         FIG. 3  is a graph showing a reflectance per wavelength of light; 
         FIGS. 4 to 6  each show a plan view and a cross-sectional view photonic crystals according to an exemplary embodiment of the present inventive concept; 
         FIGS. 7A and 7B  are diagrams each for describing a method of generating protrusions and grooves included in a photonic crystal according to an exemplary embodiment of the present inventive concept; 
         FIG. 8  is a block diagram of a data processing system including the pixels illustrated in  FIG. 1 or 2 , according to an exemplary embodiment of the present inventive concept; 
         FIG. 9  is a block diagram of a data processing system including the pixels illustrated in  FIG. 1 or 2 , according to an exemplary embodiment of the present inventive concept; 
         FIG. 10  is a block diagram of a, data processing system including the pixels illustrated in  FIG. 1 or 2 , according to an exemplary embodiment of the present inventive concept; 
         FIG. 11  is a flowchart describing a method of manufacturing a two-dimensional (2D) photonic crystal illustrated in  FIG. 1 , according to an exemplary embodiment of the present inventive concept; and 
         FIG. 12  is a flowchart describing a method of manufacturing a three-dimensional (3D) photonic crystal illustrated in  FIG. 2 , according to an exemplary embodiment of the present inventive concept. 
     
    
    
     DETAILED DESCRIPTION OF THE EMBODIMENTS 
     Hereinafter, exemplary embodiments of the present inventive concept will be described in detail with reference to the accompanying drawings. Like reference numerals may refer to like elements throughout the accompanying drawings and written description. 
     A photonic crystal in accordance with an exemplary embodiment of the present inventive concept may include an uneven pattern, e.g., protrusions and grooves. The protrusions and the grooves may be formed through an etching process. Here, a protrusion may be a portion which is not etched by the etching process, and a groove may be a portion which is etched by the etching process. 
       FIG. 1  is a cross-sectional view of pixels of an image sensor according to an example embodiment of the present inventive concept. Referring to  FIG. 1 , pixels  10 A of an image sensor include a plurality of photoelectric conversion elements  20 - 1 ,  20 - 2 , and  20 - 3  and a plurality of microlenses  40 - 1 ,  40 - 2 , and  40 - 3 . The image sensor may be embodied in a front side illumination (FSI) image sensor or a back side illumination (BSI) image sensor. 
     The plurality of photoelectric conversion elements  20 - 1 ,  20 - 2 , and  20 - 3  may be formed in a semiconductor substrate  10 . Each of the plurality of photoelectric conversion elements  20 - 1 ,  20 - 2 , and  20 - 3  may be embodied in a photodiode, a photo transistor, a photogate, or a pinned photo diode. 
     Each of the plurality of microlenses  40 - 1 ,  40 - 2 , and  40 - 3  may be formed or arranged on or above each of the plurality of photoelectric conversion elements  20 - 1 ,  20 - 2 , and  20 - 3 . 
     Each of the plurality of microlenses  40 - 1 ,  40 - 2 , and  40 - 3  may perform a function of a two-dimensional (2D) photonic crystal color reflector. 
     Each of a plurality of photonic crystals may be formed by etching an upper surface of each of the plurality of microlenses  40 - 1 ,  40 - 2 , and  40 - 3 . Accordingly, each of the plurality of microlenses  40 - 1 ,  40 - 2 , and  40 - 3  may function as a color filter and a microlens. 
     A first microlens  40 - 1  including a first photonic crystal has a structure to reflect wavelengths RC of a red region among visible light IL and to allow wavelengths GC of a green region and wavelengths BC of a blue region to pass through. 
     A second microlens  40 - 2  including a second photonic crystal has a structure to reflect the wavelengths GC of the green region among the visible light IL and to allow the wavelengths RC of the red region and the wavelengths BC of the blue region to pass through. 
     A third microlens  40 - 3  including a third photonic crystal has a structure to reflect the wavelengths BC of the blue region among the visible light IL and to allow the wavelengths RC of the red region and the wavelengths GC of the green region to pass through. 
     The pixels  10 A of the image sensor may further include an intermediate layer  30  formed between the semiconductor substrate  10  and the plurality of photonic crystals  40 - 1 ,  40 - 2 , and  40 - 3 . For example, the intermediate layer  30  may include at least one of a metal layer and a dielectric layer. 
     According to an exemplary embodiment of the present inventive concept, the wavelengths GC and BC passing through the first microlens  40 - 1  are directly incident on the first photoelectric conversion element  20 - 1  or incident on the first photoelectric conversion element  20 - 1  through the intermediate layer  30 . 
     The wavelengths RC and BC passing through the second microlens  40 - 2  are directly incident on the second photoelectric conversion element  20 - 2  or incident on the second photoelectric conversion element  20 - 2  through the intermediate layer  30 . The wavelengths RC and GC passing through the third microlens  40 - 3  are directly incident on the third photoelectric conversion element  20 - 3  or incident on the third photoelectric conversion element  20 - 3  through the intermediate layer  30 . 
     Each photonic crystal embodied in each microlens  40 - 1 ,  40 - 2 , and  40 - 3  may include protrusions and grooves. Here, the refractive index of a material corresponding to the protrusions is greater than the refractive index of a material corresponding to a space material formed between the grooves. 
     The protrusions may be embodied in a plurality of pillars spaced apart from each other. 
     The refractive index of the pillars may be greater than the refractive index of the space material. For example, the space material may be air. When the pillars are embodied in a pillar material having a specific, refractive index, the space material will be any material whose refractive index is less than the refractive index of the pillar material. In other words, areas between the grooves can be filled with a space material whose refractive index is less than the refractive index of the pillar material. 
     Wavelengths reflected from a photonic crystal are determined according to a height, a width, and/or a pitch of each protrusion and/or each groove included in the photonic crystal. 
     A horizontal dimension, e.g., a horizontal length, of each photonic crystal embodied in each microlens  40 - 1 ,  40 - 2 , and  40 - 3  may be longer than the horizontal dimension of each photoelectric conversion element  20 - 1 ,  20 - 2 , and  20 - 3 . 
       FIG. 2  is a cross-sectional view of pixels of an image sensor according to an exemplary embodiment of the present inventive concept. Referring to  FIG. 2 , pixels  10 B of an image sensor include a plurality of photoelectric conversion elements  20 - 1 ,  20 - 2 , and  20 - 3 , a plurality of PHOTONIC crystals  41 - 1 ,  41 - 2 , and  41 - 3 , and a plurality of microlenses  50 - 1 ,  50 - 2 , and  50 - 3 . 
     When the image sensor is embodied in a BSI image sensor, the plurality of photonic crystals  41 - 1 ,  41 - 2 , and  41 - 3  may be easily formed. 
     The plurality of photoelectric, conversion elements  20 - 1 ,  20 - 2 , and  20 - 3  may be formed in the semiconductor substrate  10 . Each of the plurality of photonic crystals  41 - 1 ,  41 - 2 , and  41 - 3  may be formed or arranged on or above each of the plurality of photoelectric conversion, elements  20 - 1 ,  20 - 2 , and  20 - 3 . Each of the plurality of photonic crystals  41 - 1 ,  41 - 2 , and  41 - 3  may function as a three-dimensional (3D) photonic crystal color reflector. 
     Each photonic crystal  41 - 1 ,  41 - 2 , and  41 - 3  includes a plurality of unit photonic crystals L1, L2, L3, and L4, and each unit photonic crystal L1, L2, L3, and L4 is stacked with respect to each other. 
     The visible light IL passing through the first microlens  50 - 1  is incident on the first photonic crystal  41 - 1 . The first photonic crystal  41 - 1  has a structure to reflect the wavelengths RC of the red region among the visible light IL and to allow the wavelengths GC of the green region and the wavelengths BC of the blue region to pass through. 
     The visible light IL passing through the second microlens  50 - 2  is incident on the second photonic crystal  41 - 2 . The second photonic crystal  41 - 2  has a structure to reflect the wavelengths of the green region GC among the visible light IL, and to allow the wavelengths RC of the red region and the wavelengths BC of the blue region to pass through. 
     The visible light IL passing through the third microlens  50 - 3  is incident on the third photonic crystal  41 - 3 . The third photonic crystal  41 - 3  has a structure to reflect the wavelengths BC of the blue region among the visible light IL, and to allow the wavelengths RC of the red region and the wavelengths GC of the green region to pass through. 
     The wavelengths GC and BC passing through the first photonic crystal  41 - 1  are incident on the first photoelectric conversion element  20 - 1 . The wavelengths RC and BC passing through the second photonic crystal  41 - 2  are incident on the second photoelectric conversion element  20 - 2 . The wavelengths RC; and GC passing through the third photonic crystal  41 - 3  are incident on the third photoelectric conversion element  20 - 3 . Each unit photonic crystal L1, L2, L3, and L4 of each photonic crystal  41 - 1 ,  41 - 2 , and  41 - 3  may include uneven patterns, e.g., protrusions (e.g., pillars), and grooves formed between the protrusions. 
     The refractive index of the pillars is greater than the refractive index of a space material between the grooves. For example, the space material may be air. When the pillars are embodied in a pillar material with a specific refractive index, the refractive index of the space material is less than the refractive index of the pillar material. 
     Wavelengths reflected by each photonic crystal  41 - 1 ,  41 - 2 , and  41 - 3  are determined according to a height, a width, and/or a pitch of each protrusion and/or each groove included in each photonic crystal  41 - 1 ,  41 - 2 , and  41 - 3 . The horizontal dimension of each photonic crystal  41 - 1 ,  41 - 2 , and  41 - 3  may be longer than the horizontal dimension of each photoelectric conversion element  20 - 1 ,  20 - 2 , and  20 - 3 . 
       FIG. 3  is a graph showing a reflectance per wavelength of light. The X-axis of  FIG. 3  indicates a wavelength, the Y axis indicates reflectance. In  FIG. 3 , there can be seen the wavelengths BC, GC and RC of a blue region, a green region and a red region and their corresponding reflectances.  FIGS. 4 to 6  each show a plan view and a cross-sectional view of photonic crystals according to an exemplary embodiment of the present inventive concept. Referring to  FIGS. 4 to 6 , each 2D photonic crystal includes a plurality of protrusions and a space material formed between the protrusions. 
     Each pitch or each pattern size L1, L2, or L3 may be determined based on wavelengths to be reflected. In  FIGS. 4 to 6 , a height H of each pillar is equally illustrated, however, the height H of each pillar may be determined based on the wavelengths to be reflected. 
     In other words, the height H of a protrusion, the width W1, W2, and W3 of the protrusion, and/or the pitch L1, L2, and L3 of the protrusion can be determined and designed according to the wavelengths to be reflected. 
     Moreover, the depth of a groove, the width of the groove, and/or the pitch of the groove may be determined and designed according to the wavelength to be reflected. Here, a width may be a horizontal length or a vertical length of a protrusion. 
     For example, the 2D photonic crystal of  FIG. 4  may reflect the wavelengths RC of the red region and allow the wavelengths GC of the green region and the wavelengths BC of the blue region to pass through. 
     The 2D photonic crystal of  FIG. 5  may reflect the wavelengths GC of the green region and allow the wavelengths RC of the red region and the wavelengths BC of the blue region to pass through. 
     The 2D photonic crystal of  FIG. 6  may reflect the wavelengths BC of the blue region and allow the wavelengths RC of the red region and the wavelengths GC of the green region to pass through. 
       FIGS. 7A and 7B  are diagrams each for describing a method of generating protrusions and grooves included in a photonic crystal according to an exemplary embodiment of the present inventive concept. Referring to  FIG. 7A , protrusions included in the photonic crystal may be embodied in a groove (e.g., hole)-based structure. Referring to  FIG. 7B , the protrusions included in the photonic crystal may be embodied in a pillar (e.g., pole)-based structure. 
     A horizontal cross-sectional shape of a protrusion or a groove included in the photonic crystal may have a circular, rectangular, pentagonal or polygonal shape. As described above, portions which are etched using a mask become grooves, and portions which are not etched become protrusions. 
       FIG. 8  is a block diagram of a data processing system including the pixels illustrated in  FIG. 1 or 2 , according to an exemplary embodiment of the present inventive concept. Referring to  FIGS. 1, 2, and 8 , a data processing system  500  may be embodied in a, digital camera, a camcorder, or a portable electronic device including a CMOS image sensor  505 . The portable electronic device may be embodied in a mobile phone, a smart phone, a tablet personal computer (PC), a mobile internet device (MID), or a wearable computer. 
     The data processing system  500  includes an optical lens  503 , the CMOS image sensor  505 , a digital signal processor  600 , and a display  640 . The CMOS image sensor  505  may generate image data IDATA of an object  501  incident through the optical lens  503 . 
     The CMOS image sensor  505  includes a pixel array  510 , a row driver  520 , a readout circuit  525 , a timing generator  530 , a control register block  550 , a reference signal generator  560 , and a buffer  570 . The pixel array  510  includes a plurality of pixels  10 A or  10 B, collectively referred to hereinafter as  10 . The pixels  10  may be manufactured using a CMOS manufacturing process. The pixel array  510  includes the pixels  10  arranged in a matrix shape. The pixels  10  transmit output signals to column lines. 
     The row driver  520  drives control signals for controlling an operation of each, of the pixels  10  to the pixel array  510  according to a control of the timing generator  530 . The row driver  520  may perform a function of a control signal generator which may generate control signals. 
     The timing generator  530  controls an operation of the row driver  520 , the readout circuit  525 , and the reference signal generator  560  according to a control of the control register block  550 . 
     The readout circuit  525  includes an analog-to-digital converter  526  per column and a memory  527  per column. According to an exemplary embodiment of the present inventive concept, the analog-to-digital converter  526  may perform a correlated double sampling function. The readout circuit  525  outputs a digital image signal corresponding to a pixel signal output from each pixel  10 . 
     The control register block  550  controls an operation of the timing generator  530 , the reference signal generator  560 , and the buffer  570  according to a control of the digital signal processor  600 . 
     The buffer  570  transmits image data IDATA corresponding to a plurality of digital image signals output from the readout circuit  525  to the digital signal processor  600 . 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 the sensor controller  620  which controls the control register block  550 , and the interface  630 . According to an exemplary embodiment of the present inventive concept, the CMOS image sensor  505  and the digital signal processor  600  may be embodied in one package, e.g., a multi-chip package. According to an exemplary embodiment of the present inventive concept, the CMOS image sensor  505  and the image signal processor  610  may be embodied in one package, e.g., a multi-chip package. 
     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  may generate various control signals for controlling the control register block  550  according to a control of the image signal processor  610 . The interface  630  may transmit the image data processed by the image signal processor  610  to the display  640 . 
     The display  640  may display image data output from the interface  630 . The display  640  may be embodied in a 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. 
       FIG. 9  is a block diagram of a data processing system including the pixels illustrated in  FIG. 1 or 2 , according to an exemplary embodiment of the present inventive concept. Referring to  FIGS. 8 and 9 , the data processing system  600  may be embodied in a portable electronic device which may use or support a mobile industry processor interface (MIPI®). As described above, the portable electronic device includes the CMOS image sensor  505  and a processing circuit which may receive image data IDATA output from the CMOS image sensor  505 . 
     The image processing system  600  includes an application processor (AP)  610 , the image sensor  505 , and a display  630 . A camera serial interface (CSI) host  613  embodied in the AP  610  may perform a serial communication with a CSI device  506  of the image sensor  505  through a camera serial interface (CSI). 
     According to an exemplary embodiment of the present inventive concept, a de-serializer DES may be embodied in the CSI host  613 , and a serializer SER may be embodied in the CSI device  506 . 
     A display serial interface (DSI) host  611  embodied in the AP  610  may perform a serial communication with a DSI device  631  of the display  630  through a display serial interface. According to an exemplary embodiment of the present inventive concept, the serializer SER may be embodied in the DSI host  611 , and the de-serializer DES may be embodied in the DSI device  631 . Each of the de-serializer DES and the serializer SER may process an electrical signal or a photo signal. 
     The image processing system  600  may further include a radio frequency (RF) chip  640  which may communicate with the AP  610 . A physical layer (PHY)  615  of the AP  610  and a PHY  641  of the RF chip  640  may transmit or receive data to/from each other according to MIPI DigRF. A central processing unit (CPU)  617  embodied in the AP  610  may control operations of the DSI host  611 , the CSI host  613  and the PHY  615 . The CPU  617  may further control operations of the RF chip  640 . For example, the CPU  617  may perform a function of the master for the RF chip  640 . 
     The image processing system  600  may further include a GPS receiver  650 , a memory  651  such as a dynamic random access memory (DRAM), a data storage device  653  embodied in a non-volatile memory such as a NAND flash-based memory, a microphone  655 , or a speaker  657 . The image processing system  600  may communicate with an external device using at least one communication protocol or communication standard, e.g., worldwide interoperability for microwave access (WiMAX)  659 , Wireless Local Area Network (WLAN)  661 , ultra-wideband (UWB)  663 , or long term evolution (LTE™)  665 . The image processing system  600  may communicate with an external wireless communication device using Bluetooth or WiFi. 
     According to an exemplary embodiment of the present inventive concept, the AP  610  may further include each component  711 ,  720 ,  740 , and  750  illustrated in  FIG. 10 . 
       FIG. 10  is a block diagram of a data processing system including the pixels illustrated in  FIG. 1 or 2 , according to an exemplary embodiment of the present inventive concept. Referring to  FIGS. 8 and 10 , a data processing system  700  may be embodied in a PC or a portable electronic device. As described above, the portable electronic device includes the CMOS image sensor  505  and a processing circuit which may receive image data IDATA output from the CMOS image sensor  505 . 
     The image processing system  700  may include the image sensor  505 , a processor  710 , a memory  760 , and a display (or display device)  770 . The image sensor  505  may be included in a camera module. The camera module may include mechanical components which may control an operation of the image sensor  505 . 
     The processor  710  may be embodied in an integrated circuit, a system-on-chip (SoC), an application processor, or a mobile application processor. The processor  710  may control an operation of the image sensor  505 , the memory  760 , and the display  770 , process image data output from the image sensor  505 , and store the processed image data in the memory  760  or display the processed image data through the display  770 . 
     The processor  710  includes a CPU  720 , a camera interface  730 , a memory interface  740 , and a display controller  750 . The CPU  720  may control operations of the camera interface  730 , the memory interface  740 , and the display controller  750  through a bus  711 . 
     The CPU  720  may be embodied in a multi-core processor or a multi-CPU. According to a control of the CPU  720 , the camera interface  730  may transmit control signals for controlling the image sensor  505  to the image sensor  505 , and transmit an image data signal output from the image sensor  505  to the CPU  720 , the memory interface  740 , and/or the display controller  750 . 
     The memory interface  740  may interface data transmitted or received between the processor  710  and the memory  760 . The display controller  750  may transmit data to be displayed on the display  770  to the display  770 . 
     The memory  760  may be a volatile memory such as a DRAM, or a flash-based memory. The flash-based memory may be embodied in a multimedia card (MMC), an embedded MMC (eMMC), an embedded solid state drive (eSSD), or a universal flash memory (UFS). 
       FIG. 11  is a flowchart which describes a method of manufacturing the 2D photonic crystal illustrated in  FIG. 1 , according to an exemplary embodiment of the present inventive concept. Referring to  FIGS. 1 and 11 , each photoelectric conversion element  20 - 1 ,  20 - 2 , and  20 - 3  is formed in the semiconductor substrate  10  (S 100 ). Each microlens  40 - 1 ,  40 - 2 , and  40 - 3  including a corresponding photonic crystal is formed on or above each photoelectric conversion element  20 - 1 ,  20 - 2 , and  20 - 3  (S 110 ). The photonic crystal includes protrusions and grooves defined according to the etching process used to form the protrusions and grooves. 
       FIG. 12  is a flowchart which describes a method of manufacturing the 3D photonic crystal illustrated in  FIG. 2 , according to an exemplary embodiment of the present inventive concept. Referring to  FIGS. 2 and 12 , each photoelectric conversion element  20 - 1 ,  20 - 2 , and  20 - 3  is formed in the semiconductor substrate  10  (S 100 ). Each 3D photonic crystal  41 - 1 ,  41 - 2 , and  41 - 3  is formed on its corresponding photoelectric conversion element  20 - 1 ,  20 - 2 , and  20 - 3  (S 210 ). 
     Each microlens  50 - 1 ,  50 - 2 , and  50 - 3  is formed on or above its corresponding 3D photonic crystal  41 - 1 ,  41 - 2 , and  41 - 3  (S 220 ). The shorter a wavelength reflected by a photonic crystal is, the smaller a structure of each of the uneven patterns formed in the photonic crystal, e.g., a 3D image of a protrusion, a 3D image of a groove, a distance or pitch between protrusions, and/or a distance or pitch between grooves, becomes. 
     An image sensor including a photonic crystal which may be used as a reflective color filter according to an exemplary embodiment of the present inventive concept may increase light transmittance incident on a photoelectric conversion element. 
     Although the present inventive concept has been shown and described with reference to exemplary embodiments thereof, it will be appreciated by those of ordinary skill in the art that various changes in form and detail may be made thereto without departing from the spirit and scope of the present inventive concept as defined by the appended claims.