Patent Publication Number: US-2022231063-A1

Title: Image sensor

Description:
CROSS-REFERENCE TO RELATED APPLICATION(S) 
     This application claims priority under 35 U.S.C. 119 from Korean Patent Application No. 10-2021-0006944, filed on Jan. 18, 2021 in the Korean Intellectual Property Office, the contents of which are herein incorporated by reference in their entirety. 
     BACKGROUND 
     Technical Field 
     The present inventive concept relates to an image sensor. 
     Discussion of the Related Art 
     Image sensors that capture images and convert the images into electrical signals can be used not only in electronic devices for general consumers, such as digital cameras, mobile phone cameras, portable camcorders, etc., but also cameras installed in vehicles, security devices, or robots, etc. Since the image sensors can be miniaturized and should have high resolution, research has been conducted to meet these needs. 
     SUMMARY 
     An embodiment of the present inventive concept provides an image sensor that has increased resolution. 
     According to an embodiment of the present inventive concept, an image sensor includes a first chip structure that includes a first substrate; and a second chip structure disposed on the first chip structure. The second chip structure includes: a second substrate that has a first surface that faces the first chip structure and a second surface opposite to the first surface; photoelectric conversion devices disposed in the second substrate; an insulating structure disposed on the second surface of the second substrate; a grid pattern structure disposed on the insulating structure; color filters disposed on the insulating structure and the grid pattern structure; and microlenses disposed on the color filters. The grid pattern structure includes a first pattern portion and second pattern portions, where the first pattern portion includes a first material pattern and a second material pattern disposed on the first material pattern. The first material pattern is formed of a first material, the second pattern portions and the second material pattern are formed of a second material that differs from the first material, and a center of each of the microlenses does not overlap the second pattern portions. 
     According to an embodiment of the present inventive concept, an image sensor includes a substrate that includes a plurality of pixel regions; an insulating structure disposed on the substrate and that includes a plurality of sequentially stacked layers; a grid pattern structure disposed on the insulating structure; color filters disposed on the insulating structure; and microlenses disposed on the color filters. The grid pattern structure includes a first pattern portion and second pattern portions. When viewed in a plan view, the first pattern portion includes first horizontal straight portions that are parallel to each other, and first vertical straight portions that are parallel to each other and perpendicular to the first horizontal straight portions, each of the second pattern portions includes a second horizontal straight portion parallel to the first horizontal straight portions, and a second vertical straight portion parallel to the first vertical straight portions, and the second horizontal straight portion is perpendicular to the second vertical straight portion. 
     According to an embodiment of the present inventive concept, an image sensor includes a substrate that includes a plurality of first pixel regions, a plurality of second pixel regions, and a plurality of third pixel regions; an insulating structure disposed on the substrate and that includes a plurality of sequentially stacked layers; a grid pattern structure disposed on the insulating structure; color filters disposed on the insulating structure; and microlenses disposed on the color filters. The color filters include a first color filter of a first color, a second color filter of a second color that differs from the first color, and a third color filter of a third color that differs from the first and second colors. The grid pattern structure includes a first pattern portion and second pattern portions, the first pattern portion is disposed between color filters of different colors of the first to third color filters, and the first to third color filters cover side surfaces and an upper surface of the second pattern portions. The microlenses include a plurality of microlenses disposed on the first color filter, a plurality of microlenses disposed on the second color filter, and a plurality of microlenses disposed on the third color filter. Each of the second pattern portions is covered by any one of the first to third color filters. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  schematically illustrates an image sensor according to an embodiment of the present inventive concept. 
         FIG. 2  is a cross-sectional view of an image sensor according to an embodiment of the present inventive concept. 
         FIG. 3  is a partially enlarged cross-sectional view of an image sensor according to an embodiment of the present inventive concept. 
         FIGS. 4A and 4B  are plan views of some components of an image sensor according to an embodiment of the present inventive concept. 
         FIGS. 5 and 6  are cross-sectional views of an image sensor according to an embodiment of the present inventive concept. 
         FIGS. 7 to 10  are partial enlarged cross-sectional views of various modified examples of an image sensor according to an embodiment of the present inventive concept. 
         FIGS. 11A to 11E  are partial enlarged cross-sectional views of various modified examples of an image sensor according to an embodiment of the present inventive concept. 
         FIG. 12A  schematically illustrates another modified example of an image sensor according to an embodiment of the present inventive concept. 
         FIG. 12B  schematically illustrates another modified example of an image sensor according to an embodiment of the present inventive concept. 
         FIGS. 13, 14, and 15A to 15C  are cross-sectional views that illustrate a method of forming an image sensor according to an embodiment of the present inventive concept. 
     
    
    
     DETAILED DESCRIPTION 
     Hereinafter, exemplary embodiments of the present inventive concept will be described with reference to the accompanying drawings. 
     First, an example of an image sensor according to an embodiment of the present inventive concept will be described with reference to  FIG. 1 .  FIG. 1  is an exploded perspective view that illustrates an image sensor according to an embodiment of the present inventive concept, and a partially enlarged portion that illustrates ‘portion A’ in  FIG. 1  represents a planar shape in which a portion of the image sensor illustrated in the exploded perspective view is enlarged. 
     Referring to  FIG. 1 , an image sensor  1  according to an embodiment includes a first chip structure  3  and a second chip structure  103  disposed on the first chip structure  3 . The first chip structure  3  can be a logic chip, and the second chip structure  103  can be an image sensor chip that includes a plurality of pixel regions G 1  to G 4 , R 1  to R 4 , and B 1  to B 4 . In another embodiment, the first chip structure  3  is a stacked chip structure that includes a logic chip and a memory chip. 
     In an embodiment, the second chip structure  103  of the image sensor  1  includes a first region CA, a second region EA, and a third region PA. 
     In an embodiment, the third region PA is disposed on at least one side of a central region that includes the first region CA and the second region EA. For example, the third region PA is disposed on both sides of a central region that includes the first region CA and the second region EA, or can be disposed to surround the central region. The second region EA is disposed on at least one side of the first region CA. For example, the second region EA may be disposed on either side of the first region CA, may be disposed on both sides of the first region CA, or may surround the first region CA. 
     In an embodiment, the first region CA includes an active pixel sensor array region, and the second region EA includes an optical black region OB and a chip-connection region CB. The third region PA includes a pad region in which input/output pads are disposed. The third region PA may be referred to as a pad region. 
     In an embodiment, the first region CA is an active pixel sensor array region onto which light is incident, and the optical black region OB of the second region EA is a region onto which no light is incident, and the chip-connection region CB of the second region EA electrically connects an interconnection structure of the first chip structure  3  and an interconnection structure of the second chip structure  103 . In embodiments, the optical black region OB and the chip-connection region CB may be arranged in various patterns. 
     In an embodiment, the second chip structure  103  includes a plurality of color filters  160 . The color filters  160  include first color filters  160   a  of a first color, second color filters  160   b  of a second color, different from the first color, and third color filters  160   c  of a third color, different from the first and second colors. For example, the first color may be green, the second color may be red, and the third color may be blue. 
     In an embodiment, the first region CA, which is an active pixel sensor array region, includes a plurality of pixel regions G 1  to G 4 , R 1  to R 4 , and B 1  to B 4 . The plurality of pixel regions G 1  to G 4 , R 1  to R 4 , and B 1  to B 4  have a planar shape indicated by portion ‘A’ in  FIG. 1 . A first pixel group (G 1  to G 4 ) that includes a G 1  pixel region, a G 2  pixel region, a G 3  pixel region, and a G 4  pixel region, adjacent to each other, overlaps one of the first color filters  160   a , a second pixel group (R 1  to R 4 ) that includes a R 1  pixel region, a R 2  pixel region, a R 3  pixel region, and a R 4  pixel region, adjacent to each other, overlaps one of the second color filters  160   b , and a third pixel group (B 1  to B 4 ) that includes a B 1  pixel region, a B 2  pixel region, a B 3  pixel region, and a B 4  pixel region, adjacent to each other, overlaps one of the third color filters  160   c.    
     In an embodiment, when ‘portion A’ in  FIG. 1  is viewed in a plan view, the second chip structure  103  further includes a grid pattern structure  150  disposed between each of the pixel regions G 1  to G 4 , R 1  to R 4 , and B 1  to B 4 . The grid pattern structure  150  includes a first pattern portion  150   a  and second pattern portions  150   b . The second pattern portions  150   b  extend from the first pattern portion  150   a.    
     In an embodiment, when viewed in a plan view, the first pattern portion  150   a  includes first horizontal straight portions  150   a _ 1  parallel to each other and first vertical straight portions  150   a _ 2  parallel to each other. The first vertical straight portions  150   a _ 2  are perpendicular to the first horizontal straight portions  150   a _ 1 . The first pattern portion  150   a  has a grid shape in which the first horizontal straight portions  150   a _ 1  and the first vertical straight portions  150   a _ 2  vertically intersect. 
     In an embodiment, the first pattern portion  150   a  is disposed between color filters of different colors of the first to third color filters  160   a ,  160   b , and  160   c . Therefore, each of the first horizontal straight portions  150   a _ 1  and the first vertical straight portions  150   a _ 2  are disposed between color filters of different colors of the first to third color filters  160   a ,  160   b , and  160   c.    
     In an embodiment, when viewed in a plan view, each of the second pattern portions  150   b  includes a second horizontal straight portion  150   b _ 1  and a second vertical straight portion  150   b _ 2  perpendicular to the second horizontal straight portion  150   b _ 1 . The second horizontal straight portion  150   b _ 1  is parallel to the first horizontal straight portions  150   a _ 1  and spaced apart from the first horizontal straight portions  150   a _ 1 , and extends from a side surface of an adjacent first vertical straight portion  150   a _ 2 . The second vertical straight portion  150   b _ 2  is parallel to the first vertical straight portions  150   a _ 2  and spaced apart from the first vertical straight portions  150   a _ 2 , and extends from a side surface of an adjacent first horizontal straight portion  150   a _ 1 . 
     In an embodiment, when viewed in a plan view, each of the second pattern portions  150   b  overlaps a color filter of one color of the first to third color filters  160   a ,  160   b , and  160   c.    
     Next, an example of the image sensor  1  described with reference to  FIG. 1  will be described with reference to  FIGS. 2, 3, 4A, and 4B .  FIG. 2  is a cross-sectional view taken along line I-I′ in  FIG. 1 , and  FIG. 3  is a partially enlarged view that illustrates “portion B 1 ” and “portion B 2 ” of  FIG. 2 , respectively.  FIG. 4A  is a plan view that illustrates a planar shape of some components of the image sensor, such as a second material pattern  147  in the enlarged portion ‘A’ in  FIG. 1 , and  FIG. 4B  is a plan view that illustrates a planar shape of some components of the image sensor, such as a first material pattern  145  in the enlarged portion ‘A’ in  FIG. 1 . 
     Referring to  FIGS. 2, 3, 4A and 4B , together with  FIG. 1 , in an embodiment, the first chip structure  3  of the image sensor  1  includes a first substrate  6 , a device isolation layer  9   s  disposed on the first substrate  6  and that defines an active region  9   a , a first circuit device  12  and a first interconnection structure  15  disposed on the first substrate  6 , and a first insulating layer  18  disposed on the first substrate  6  and that covers the first circuit device  12  and the first interconnection structure  15 . The first substrate  6  is a semiconductor substrate. For example, the first substrate  6  is formed of a semiconductor material, such as a single crystal silicon substrate. The first circuit device  12  includes a transistor that includes a gate  12   a  and a source/drain  12   b.    
     In an embodiment, the pixel regions G 1  to G 4 , R 1  to R 4 , and B 1  to B 4  of the second chip structure  103  of the image sensor  1  include photoelectric conversion devices PD. For example, each of the pixel regions G 1  to G 4 , R 1  to R 4 , and B 1  to B 4  includes a photoelectric conversion device PD. The photoelectric conversion devices PD generate and accumulate electric charges that correspond to incident light. For example, the photoelectric conversion devices PD may any one of a photo diode, a photo transistor, a photo gate, a pinned photo diode (PPD), or a combination thereof. 
     In an embodiment, the second chip structure  103  is formed on a second substrate  106  that includes a first surface  106   s   1  and a second surface  106   s   2  that are opposite to each other, a device isolation layer  118  disposed on the first surface  106   s   1  of the second substrate  106  and that defines an active region, a second circuit device  124  and a second interconnection structure  127  disposed between the first surface  106   s   1  of the second substrate  106  and the first chip structure  3 , and a second insulating layer  130  disposed between the first surface  106   s   1  of the second substrate  106  and the first chip structure  3  and that covers the second circuit device  124  and the second interconnection structure  127 . The first surface  106   s   1  of the second substrate  106  faces the first chip structure  3 . 
     In an embodiment, the first photoelectric conversion devices PD are formed in the second substrate  106 , and are spaced apart from each other. The second substrate  106  is a semiconductor substrate. For example, the second substrate  106  is formed of a semiconductor material, such as a single crystal silicon substrate. 
     In an embodiment, the second chip structure  103  further includes a separation structure  115 . The separation structure  115  surrounds each of the photoelectric conversion devices PD. The separation structure  115  is disposed in a through-opening  112  that penetrates through the second substrate  106 . The separation structure  115  penetrates through the second substrate  106 . The through-opening  112  is connected to the device isolation layer  118 . Therefore, the separation structure  115  is connected to the device isolation layer  118 . The device isolation layer  118  is formed of an insulating material such as silicon oxide, etc. The separation structure  115  includes a separation pattern  115   b  and a separation insulating layer  115   a  that covers side surfaces of the separation pattern  115   b . For example, the separation insulating layer  115   a  includes silicon oxide, and the separation pattern  115   b  includes polysilicon. 
     In an embodiment, the second circuit device  124  includes a transfer gate TG and active devices  121 . The active devices  121  are transistors that include a gate  121   a  and a source/drain  121   b . The transfer gate TG transfers electric charges from an adjacent photoelectric conversion device PD to an adjacent floating diffusion region, and the active devices  121  are at least one of a source follower transformer, a reset transistor, or a select transistor. The transfer gate TG is a vertical transfer gate that includes a portion that extends into the second substrate  106  from the first surface  106   s   1  of the second substrate  106 . 
     In an embodiment, the second interconnection structure  127  includes multilayer interconnection lines located at different levels, and vias that electrically connect the multilayer interconnection lines and electrically connect the multilayer interconnection lines to the second circuit device  124 . 
     In an embodiment, the first insulating layer  18  and the second insulating layer  130  are bonded together and in contact with each other. Each of the first and second insulating layers  18  and  130  has a multilayer structure that includes different types of insulating layers. For example, the second insulating layer  130  is a multilayer structure that includes at least two types of silicon oxide layers, a low-k dielectric layer, and a silicon nitride layer. 
     In an embodiment, the second chip structure  103  further includes an insulating structure  140  disposed on the second surface  106   s   2  of the second substrate  106 . The insulating structure  140  covers the separation structure  115 . 
     As illustrated in  FIG. 3 , in an embodiment, the insulating structure  140  includes a plurality of sequentially stacked layers. The insulating structure  140  includes an antireflection layer that can adjust a refractive index such that incident light propagates to the photoelectric conversion devices PD with high transmittance. For example, the insulating structure  140  includes at least two or more of an aluminum oxide layer, a hafnium oxide layer, a silicon oxynitride layer, a silicon oxide layer, or a silicon nitride layer. For example, the insulating structure  140  includes a first layer  140   a , a second layer  140   b , a third layer  140   c , and a fourth layer  140   d  that are sequentially stacked. The first layer  140   a  may be an aluminum oxide layer, each of the second and fourth layers  140   b  and  140   d  may be a hafnium oxide layer, and the third layer  140   c  may be a silicon oxide layer. 
     In an embodiment, a thickness of the first layer  140   a  is substantially the same as a thickness of the fourth layer  140   d.    
     In an embodiment, a thickness of the second layer  140   b  is greater than a thickness of each of the first and fourth layers  140   a  and  140   d . For example, a thickness of the second layer  140   b  ranges from about 5 times to about 7 times a thickness of the first layer  140   a.    
     In an embodiment, a thickness of the third layer  140   c  is greater than a thickness of the second layer  140   b . A thickness of the third layer  140   c  ranges from about 6 times to about 8 times a thickness of the first layer  140   a.    
     As described in  FIG. 1 , in an embodiment, the second chip structure  103  includes the grid pattern structure  150  that includes the first pattern portion  150   a  and the second pattern portions  150   b . The grid pattern structure  150  is disposed on the insulating structure  140 . 
     In an embodiment, the first pattern portion  150   a  includes a first material pattern  145  and a second material pattern  147  disposed on the first material pattern  145 . The first material pattern  145  of the first pattern portion  150   a  and the second pattern portions  150   b  are in contact with the insulating structure  140 . A thickness of the second material pattern  147  is greater than a thickness of the first material pattern  145 . 
     In an embodiment, the first material pattern  145  includes a first material, and the second material pattern  147  and the second pattern portions  150   b  include a second material that differs from the first material. 
     In an embodiment, the first material of the first material pattern  145  includes a conductive material. For example, the first material pattern  145  is formed of a conductive material that includes at least one of a metal or a metal nitride. For example, the first material pattern  145  includes at least one of Ti, Ta, TiN, TaN, or W. 
     In an embodiment, the second material of the second material pattern  147  and the second pattern portions  150   b  includes an insulating material. The second material of the second material pattern  147  and the second pattern portions  150   b  is a low refractive index (LRI) material. For example, the second material pattern  147  and the second pattern portions  150   b  each have a refractive index in the range from about 1.1 to about 1.8. The second material pattern  147  and the second pattern portions  150   b  each include an oxide or a nitride that includes Si, Al, or a combination thereof. For example, the second material pattern  147  and the second pattern portions  150   b  each includes a silicon oxide that has a porous structure or silica nanoparticles that have a network structure. 
     In an embodiment, the second pattern portions  150   b  is formed of the same second material as the second material pattern  147  of the first pattern portion  150   a . Therefore, the first pattern portion  150   a  and the second pattern portions  150   b  can be described as including the second material pattern  147  commonly formed of the second material. None of the second pattern portions  150   b  include the first material in a region in which the second horizontal straight portion  150   b _ 1  and the second vertical straight portion  150   b _ 2  intersect. The second pattern portions  150   b  do not include the first material. 
     In  FIG. 4A , in an embodiment, a portion indicated by reference numeral  147 ′ indicates a layer of the second material of the second material pattern  147  and the second pattern portions  150   b . Therefore, as illustrated in  FIG. 4A , a second material layer  147 ′ is disposed in a grid shape in which intersections of vertical portions and horizontal portions are separated by a first interval D 1 . In  FIG. 4B , a portion indicated by reference numeral  145 ′ indicates a layer of the first material of the first material pattern  145 . Therefore, the first material layer  145 ′ is disposed in a grid shape in which intersections of vertical portions and horizontal portions are separated by a second interval D 2  that is greater than the first interval D 1 , as illustrated in  FIG. 4B . 
     As described with reference to  FIG. 1 , the second chip structure  103  includes the color filters  160  that include the first to third color filters  160   a ,  160   b , and  160   c . The color filters  160  are disposed on the insulating structure  140 . The color filters  160  pass light of a specific wavelength to reach the photoelectric conversion devices PD. For example, the color filters  160  are formed of a material obtained by mixing a resin with a pigment that includes a metal or a metal oxide. The thickness of each of the color filters  160  is greater than the thickness of the grid pattern structure  150 . The color filters  160  are disposed on the insulating structure  140  and cover the grid pattern structure  150 . The color filters  160  cover side and upper surfaces of the grid pattern structure  150 . 
     In an embodiment, in the grid pattern structure  150 , the first pattern portion  150   a  are disposed between filters of different colors of the first to third color filters  160   a ,  160   b , and  160   c.    
     In an embodiment, the first pattern portion  150   a  may include side surfaces opposite to each other, and the side surfaces of the first pattern portion  150   a  are in contact with or adjacent to filters of different colors. For example, a portion of the first pattern portion  150   a  includes a first side surface that contacts the first color filter  160   a  and a second side surface that contacts the second color filter  160   b . In an embodiment, an upper surface of the first pattern portion  150   a  is in contact with different color filters, such as the first color filter  160   a  and the second color filter  160   b.    
     In an embodiment, each of the second pattern portions  150   b  includes side surfaces opposite to each other, and the side surfaces of a second pattern  150   b  are in contact with or adjacent to filters of the same color. For example, a second pattern portion  150   b  includes side surfaces that contact the first color filter  160   a . In an embodiment, a second pattern portion includes side surfaces that contact the first color filter  160   a  and an upper surface that contacts the first color filter  160   a . One of the color filters  160  covers the upper surface and the side surfaces of one of the second pattern portions  150   b.    
     In an embodiment, the second chip structure  103  further includes microlenses  170  disposed on the color filters  160 . The microlenses  170  are disposed as a plurality of microlenses on the first color filter  160   a , as a plurality of microlenses on the second color filter  160   b , and as a plurality of microlenses on the third color filter  160   c . Each of the microlenses  170  overlaps a corresponding photoelectric conversion device PD. Each of the microlenses  170  has a convex shape in a direction away from the first chip structure  3 . The microlenses  170  condense incident light into the photoelectric conversion devices PD. The microlenses  170  may be formed of a transparent photoresist material or a transparent thermosetting resin material. For example, the microlenses  170  may be formed of a TMR series resin (manufactured by Tokyo Ohka Kogo, Co.) or an MFR series resin (manufactured by Japan Synthetic Rubber Corporation), but embodiments are not limited to these materials. 
     In an embodiment, each of the microlenses  170  is convex in a direction away from the first chip structure  3 , such as a direction away from the second substrate  106 . The centers of each of the microlenses  170  do not overlap the second pattern portions  150   b . For example, in the cross-sectional structure of  FIG. 2 , a first microlens  170   a  and a second microlens  170   b  that are adjacent to each other in a horizontal direction are disposed on one of the first color filters  160   a . The second pattern portion  150   b  does not overlap a center of the first microlens  170   a  or a center of the second microlens  170   b , but overlaps a boundary region between the first microlens  170   a  and the second microlens  170   b . In this case, the center of each of the microlenses  170  is the most convex portion of each of the microlenses  170 . One of the second pattern portions  150   b  includes a portion that overlaps a boundary between the adjacent first microlens  170   a  and second microlens  170   b.    
     According to above-described embodiments, any one of the color filters  160 , such as the first color filter  160   a , overlaps a plurality of photoelectric conversion devices PD in the plurality of pixel regions G 1  to G 4 , to improve sensitivity of the same color in the image sensor  1 , such as the first color of the first color filter  160   a . Likewise, sensitivity of the second and third colors may also be improved for the same reason as the first color. 
     According to above-described embodiments, in the grid pattern structure  150 , the first pattern portion  150   a  disposed between color filters of different colors includes the first material pattern  145  formed of a conductive material that serve as a charge path that removes charge, and the second pattern portions  150   b , which have side surfaces and the upper surface covered by color filters of the same color, do not include a conductive material, which reduces sensitivity in pixel regions that overlap color filters of the same color, to further improve sensitivity of the same color of the image sensor  1 , and reduce optical cross-talk. 
     Next, in an embodiment, referring to  FIGS. 5 and 6 , a cross-sectional structure of the image sensor  1  that includes the optical black region OB, a cross-sectional structure of the image sensor  1  that includes the chip-connection region CB, and a cross-sectional structure of the image sensor  1  that includes the pad region PA, described in  FIG. 1 , will be described.  FIG. 5  is a cross-sectional view taken along line II-IF of  FIG. 1 , and  FIG. 6  is a cross-sectional view taken along lines III-III′ and IV-IV′ of  FIG. 1 , The cross-sectional structure of  FIG. 5  that illustrates  FIG. 1  along line II-IF is a cross-section of the image sensor  1  that includes the optical black region OB shown in  FIG. 1 . The cross-sectional structure of  FIG. 6  that illustrates  FIG. 1  along line III-III′ is a cross-section of the image sensor  1  that includes the chip-connection region CB shown in  FIG. 1 , and the cross-sectional structure of  FIG. 6  that illustrates  FIG. 1  along line IV-IV′ is a cross-section of the image sensor  1  that includes the pad region PA shown in  FIG. 1 . Hereinafter, in describing the cross-sectional structures of the image sensor  1  with reference to each of  FIGS. 5 and 6 , descriptions of components that described with reference to  FIGS. 1 to 4B  will be omitted. 
     Referring to  FIG. 5 , in an embodiment, together with  FIGS. 1 to 4B , in the optical black region OB of the second chip structure  103 , a region in which a photoelectric conversion device PD′ is formed in the same manner as the photoelectric conversion devices PD described above is defined as a first reference region, and a region NPD in which no photoelectric conversion device PD is formed is defined as a second reference region. 
     In an embodiment, the first reference region PD′ and the second reference region NPD are disposed in the second substrate  106 , and are separated by the separation structure  115 . For example, the separation structure  115  surrounds side surfaces of the first reference region PD′ and side surfaces of the second reference region NPD. 
     In an embodiment, the second reference region NPD is a comparison region that does not include the photoelectric conversion devices PD or the photodiodes of the photoelectric conversion devices PD. 
     In an embodiment, in the optical black region OB of the second region EA of the image sensor  1 , the second chip structure  103  includes the insulating structure  140 , as described above, disposed on the second surface  106   s   2  of the second substrate  106 . 
     In an embodiment, in the optical black region OB of the second region EA of the image sensor  1 , the second chip structure  103  further includes light blocking conductive layers  210  and  215 , a light blocking color filter layer  230 , and an upper capping layer  240  that are sequentially stacked on the insulating structure  140 . 
     In an embodiment, the light blocking conductive layers  210  and  215  and the light blocking color filter layer  230  form a light blocking pattern that blocks light. The light blocking pattern blocks light from entering the first reference region PD′ and the second reference region NPD. The light blocking conductive layers  210  and  215  include a metal nitride layer, such as TiN or WN, etc., and a metal layer, such as Ti, W, Cu, Al, Cu, or Ag, etc., that are sequentially stacked. The light blocking color filter layer  230  includes a blue color filter. The upper capping layer  240  includes the same material as the microlenses  170 . 
     In an embodiment, the optical black region OB removes noise caused by a dark current. For example, when light is blocked by the light blocking conductive layers  210  and  215  and the light blocking color filter layer  230 , the first reference region PD′, which includes a photodiode, is used as a reference pixel to remove noise by a photodiode. In addition, when light is blocked by the light blocking conductive layers  210  and  215  and the light blocking color filter layer  230 , the second reference region NPD, which does not include a photodiode, is used to check process noise for noise removal by components other than a photodiode. 
     Referring to  FIG. 6 , together with  FIGS. 1 to 5 , in an embodiment, the image sensor  1  includes a first via hole  310   a  in the chip-connection region CB of the second region EA that penetrates through at least a portion of the second chip structure  103  and extends into the first chip structure  3 , and a second via hole  310   b  in the third region PA that penetrates through at least a portion of the second chip structure  103  and extends into the first chip structure  3 . 
     In an embodiment, the first via hole  310   a  sequentially penetrates through the insulating structure  140  and the second substrate  106 , extends downward to sequentially penetrate through the device isolation layer  118  and the second insulating layer  130 , and extends into the first insulating layer  18 . The second via hole  310   b  sequentially penetrates through the insulating structure  140  and the second substrate  106 , extends downward to sequentially penetrate through the device isolation layer  118  and the second insulating layer  130 , and extends into the first insulating layer  18 . 
     In an embodiment, the first via hole  310   a  exposes a first pad  15   p   1  of the first interconnection structure  15  and a pad portion  127   p  of the second interconnection structure  127 , and the second via hole  310   b  exposes a second pad  15   p   2  of the first interconnection structure  15  and is spaced apart from the second interconnection structure  127 . 
     In an embodiment, the image sensor  1  includes a connection conductive layer  326  in the first via hole  310   a  and an input/output conductive layer  328 V in the second via hole  310   b . The connection conductive layer  326  electrically connects the first and second interconnection structures  15  and  127 . 
     In an embodiment, the connection conductive layer  326  and the input/output conductive layer  328 V each include a first conductive layer  322  and a second conductive layer  324 . The first conductive layer  322  is a barrier material, such as TiN, etc., and the second conductive layer  324  is a metal, such as W, Cu, or Al, etc. 
     In an embodiment, the image sensor  1  further includes gap-fill insulating layers  340   a  and  340   b  disposed on the connection conductive layer  326  and the input/output conductive layer  328 V and respectively filling the first and second via holes  310   a  and  310   b , respectively, and that have concave-shaped upper surfaces, and buffer insulating layers  345   a  and  345   b  that respectively cover the gap-fill insulating layers  340   a  and  340   b  and that have upper surfaces located higher than an upper surface of the insulating structure  140 . The buffer insulating layers  345   a  and  345   b  each include a cured photoresist material. 
     In an embodiment, the image sensor  1  further includes a light blocking color filter layer  350  disposed in the chip-connection region CB of the second region EA and that covers the buffer insulating layer  345   a  and the insulating structure  140 . The light blocking color filter layer  350  in the chip-connection region CB of the second region EA extends from the light blocking color filter layer  230  in the optical black region OB of the second region EA. The light blocking color filter layers  230  and  350  may be formed of the same material, and may be, for example, a blue color filter. 
     In an embodiment, the image sensor  1  further includes an input/output pad  355  in the third region PA. The input/output pad  355  is disposed on an extension portion  328 C that extends from the input/output conductive layer  328 V. At least a portion of the input/output pad  355  is buried in the second substrate  106 . For example, the input/output pad  355  has an upper surface located higher than the second surface  106   s   2  of the second substrate  106 , and a lower surface located lower than the second surface  106   s   2  of the second substrate  106 . The insulating structure  140  is disposed on the second surface  106   s   2  of the second substrate  106 , and the extension portion  328 C of the input/output conductive layer  328 V is disposed on the insulating structure  140 . The upper capping layer  240  in the optical black region OB of the second region EA extends into the chip-connection region CB of the second region EA and the third region PA. The upper capping layer  240  covers the chip-connection region CB of the second region EA, exposes the input/output pad  355  in the third region PA, and covers a remaining portion of the third region PA. 
     In an embodiment, the image sensor  1  further includes a separation pattern  140   p  that penetrates through the second substrate  106  in the third region PA. For example, the separation pattern  140   p  extends into the second substrate  106  from at least a portion of the insulating structure  140 . 
     Referring to  FIGS. 1 to 4B  again, in an embodiment, each of the second pattern portions  150   b  has a width and a height that are substantially the same as a width and a height of the first pattern portion  150   a , respectively. However, embodiments of the technical concept of the present inventive concept are not limited thereto. For example, in other embodiments, at least one of the second pattern portions  150   b  is modified to have a width or a height that differs from a width or a height of the first pattern portion  150   a . Hereinafter, a modified example of the second pattern portion will be described with reference to  FIGS. 7 to 10 .  FIGS. 7 to 10  illustrate modified examples of the partially enlarged regions “B 1 ” and “B 2 ” of  FIG. 3 . Hereinafter, with reference to each of  FIGS. 7 to 10 , a description will be given that focuses on a modified example of the second pattern portion  150   b  of the components of  FIG. 3 . 
     In a modified example according to an embodiment, referring to  FIG. 7 , in the grid pattern structure  150 , the first pattern portion  150   a  has a first height T 1 , and a second pattern portion  250   b  may have a second height T 2  that is less than the first height T 1  and greater than half the first height T 1 . 
     In a modified example according to an embodiment, referring to  FIG. 8 , in the grid pattern structure  150 , the first pattern portion  150   a  may have a first height T 1 , and a second pattern portion  350   b  may have a third height T 3  that is equal to or less than half the first height T 1 . 
     In a modified example according to an embodiment, referring to  FIG. 9 , in the grid pattern structure  150 , the first pattern portion  150   a  has a first width W 1 , and a second pattern portion  450   b  has a second width W 2  that is less than the first width W 1 . 
     In a modified example according to an embodiment, referring to  FIG. 10 , in the grid pattern structure  150 , the first pattern portion  150   a  has a first width W 1  and a first height T 1 , and a second pattern portion  550   b  has a second width W 2  that is less than the first width W 1 , and a fourth height T 4  that is less than the first height T 1 . 
     Referring to  FIG. 3  again, in an embodiment, side surfaces of the first material pattern  145  and side surfaces of the second material pattern  147  of the first pattern portion  150   a  are vertically aligned, and a width of the first material pattern  145  and a width of the second material pattern  147  are substantially the same. Alternatively, in another embodiment, side surfaces of the first material pattern  145  and side surfaces of the second material pattern  147  of the first pattern portion  150   a  are not vertically aligned, or a width of the first material pattern  145  and a width of the second material pattern  147  are not the same. Hereinafter, modified examples of the first pattern portion  150   a  of the grid pattern structure  150  will be described with reference to  FIGS. 11A to 11E , respectively.  FIGS. 11A to 11E  illustrate modified examples of the partially enlarged region “B 2 ” in  FIG. 3 . 
     In a modified example according to an embodiment, referring to  FIG. 11A , in a first pattern portion  150   a  of the grid pattern structure  150 , a width of a first material pattern  245  is less than a width of the second material pattern  147 . One of the side surfaces of the first material pattern  245  is in contact with the second material pattern  147 , and the other side surface thereof is in contact with a color filter, such as the second color filter  160   b . In the first pattern portion  150   a  of the grid pattern structure  150 , the second material pattern  147  covers one of the side surfaces of the first material pattern  245  and contacts the insulating structure  140 . 
     In a modified example according to an embodiment, referring to  FIG. 11B , in a first pattern portion  150   a  of the grid pattern structure  150 , a width of a first material pattern  345  is less than a width of the second material pattern  147 . In addition, side surfaces of the first material pattern  345  are in contact with the second material pattern  147 . The second material pattern  147  is in contact with the insulating structure  140  while covering the side surfaces of the first material pattern  345 . 
     In a modified example according to an embodiment, referring to  FIG. 11C , in a first pattern portion  150   a  of the grid pattern structure  150 , a portion of an upper surface of a first material pattern  445  is in contact with a color filter, such as the second color filter  160   b . One of the side surfaces of the first material pattern  445  is in contact with the second material pattern  147 , and the other side surface thereof is in contact with a color filter, such as the second color  160   b . The second material pattern  147  is in contact with the insulating structure  140 . 
     In a modified example according to an embodiment, referring to  FIG. 11D , in a first pattern portion  150   a  of the grid pattern structure  150 , a width of a first material pattern  545  is greater than a width of the second material pattern  147 . In addition, side surfaces of the second material pattern  147  overlap an upper surface of the first material pattern  645 . The color filters  160  located on side surfaces of the first pattern portion  150   a  are in contact with a portion of the upper surface of the first material pattern  645 . 
     In a modified example according to an embodiment, referring to  FIG. 11E , in a first pattern portion  150   a  of the grid pattern structure  150 , a width of a first material pattern  645  is less than a width of the second material pattern  147 . In addition, side surfaces of the first material pattern  645  overlap a lower surface of the second material pattern  147 . The color filters  160  located on side surfaces of the first pattern portion  150   a  are in contact with a portion of the lower surface of the second material pattern  147 . 
     Referring to  FIG. 1  again, in embodiment, when viewed in a plan view, in the grid pattern structure  150 , the first pattern portion  150   a  includes the first horizontal straight portions  150   a _ 1  parallel to each other, and the first vertical straight portions  150   a _ 2  that are perpendicular to the first horizontal straight portions  150   a _ 1  and parallel to each other, and the second pattern portions  150   b  include the second horizontal straight portions  150   b _ 1  parallel to the first horizontal straight portions  150   a _ 1 , and the second vertical straight portion  150   b _ 2  parallel to the first vertical straight portions  150   a _ 2 . 
     In another embodiment, between a pair of first horizontal straight portions  150   a _ 1  parallel and adjacent to each other, the second horizontal straight portions  150   b _ 1  are provided as a plurality of second horizontal straight portions parallel to each other, and between a pair of first vertical straight portions  150   a _ 2  parallel and adjacent to each other, the second vertical straight portions  150   b _ 2  are provided as a plurality of second vertical straight portions parallel to each other. 
     Next, modified examples of the grid pattern structure  150  and the color filters  160  described above will be described with reference to  FIGS. 12A and 12B , respectively. 
     In an embodiment, referring to  FIG. 12A , color filters  1160  include first color filters  1160   a  of a first color, second color filters  1160   b  of a second color, and third color filters  1160   c  of a third color. One of the first color filters  1160   a  overlaps nine pixel regions indicated by G 1  to G 9 , one of the second color filters  1160   b  overlaps nine pixel regions indicated by R 1  to R 9 , and one of the third color filters  1160   c  overlaps nine pixel regions indicated by B 1  to B 9 . 
     In an embodiment like the grid pattern structure  150  described in  FIG. 1 , a grid pattern structure  1150  includes a first pattern portion  1150   a  disposed between color filters of different colors, and a second pattern portions  1150   b  that overlap color filters of one color. The first pattern portion  1150   a  includes first horizontal straight portions  1150   a _ 1  that are parallel to each other, and first vertical straight portions  1150   a _ 2  that are perpendicular to the first horizontal straight portions  1150   a _ 1  and parallel to each other, and each of the second pattern portions  1150   b  includes a plurality of second horizontal straight portions  1150   b _ 1  that are parallel to the first horizontal straight portions  1150   a _ 1 , and a plurality of second vertical straight portions  1150   b _ 2  that are parallel to the first vertical straight portions  1150   a _ 2 . 
     In an embodiment between a pair of adjacent and parallel first horizontal straight portions  1150   a _ 1 , a plurality of the second horizontal straight portions  1150   b _ 1  of the second pattern portion  1150   b  are provided, such as two parallel second horizontal straight portions. Between a pair of adjacent and parallel first vertical straight portions  1150   a _ 2 , a plurality of the second vertical straight portions  1150   b _ 2  of the second pattern portion  1150   b  are provided, such as two parallel second vertical straight portions. 
     In an embodiment, referring to  FIG. 12B , color filters  2160  include first color filters  2160   a  of a first color, second color filters  2160   b  of a second color, and third color filters  2160   c  of a third color. Any one of the first to third color filters  2160   a ,  2160   b , and  2160   c , such as the first color filters  2160   a , overlaps sixteen pixel regions indicated by G 1  to G 16 . Like the grid pattern structure  1150  described in  FIG. 12A , a grid pattern structure  2150  includes a first pattern portion  2150   a  that is disposed between color filters of different colors, and a second pattern portions  2150   b  that overlaps color filters of one color. The first pattern portion  2150   a  includes first horizontal straight portions  2150   a _ 1  that are parallel to each other, and first vertical straight portions  2150   a _ 2  that are perpendicular to the first horizontal straight portions  2150   a _ 1  and parallel to each other, and each of the second pattern portions  2150   b  includes a plurality of second horizontal straight portions  2150   b _ 1  that are parallel to the first horizontal straight portions  2150   a _ 1 , and a plurality of second vertical straight portions  2150   b _ 2  that are parallel to the first vertical straight portions  2150   a _ 2 . 
     In an embodiment, between a pair of parallel and adjacent first horizontal straight portions  2150   a _ 1 , a plurality of the second horizontal straight portions  2150   b _ 1  of the second pattern portion  2150   b  are provided, such as three parallel second horizontal straight portions. Between a pair of parallel and adjacent first vertical straight portions  2150   a _ 2 , a plurality of the second vertical straight portions  2150   b _ 2  of the second pattern portion  2150   b  are provided, such as three parallel second vertical straight portions. 
     In an embodiment, between the pair of parallel and adjacent first horizontal straight portions  2150   a _ 1  and between the pair of parallel and adjacent first vertical straight portions  2150   a _ 2 , the number of the second vertical straight portions  2150   b _ 2  and the number of the second horizontal straight portions  2150   b _ 1  in the second pattern portion  2150   b  are the same. 
     Although the above-described embodiments have been described in terms of one color filter in  FIG. 1 , such as the first color filter  160   a , overlapping four pixel regions indicated by G 1  to G 4 , any color filter in  FIG. 12A , such as the first color filter  1160   a , overlaps nine pixel regions indicated by G 1  to G 9 , and any color filter in  FIG. 12B , such as the first color filter  2160   a , overlaps sixteen pixel regions indicated by G 1  to G 16 . However, embodiments of the technical concept of the present inventive concept are not limited thereto. For example, in other embodiments of the technical concept of the present inventive concept, a color filter can overlap sixteen or more pixel regions. 
     Next, an example of a method of forming an image sensor according to an embodiment of the present inventive concept will be described.  FIGS. 13, 14, and 15A to 15C  are cross-sectional views of  FIG. 1 , taken along line I-I′ that illustrate a method of forming an image sensor according to an embodiment of the present inventive concept. 
     Referring to  FIG. 13 , in an embodiment, a first chip structure  3  is formed. The formation of the first chip structure  3  includes preparing a first substrate  6 , forming a device isolation layer  9   s  on the first substrate  6  that defines an active region  9   a , forming a first circuit device  12  on the first substrate  6 , forming a first interconnection structure  15  on the first substrate  6  that is electrically connected to the first circuit device  12 , and forming a first insulating layer  18  that covers the first circuit device  12  and the first interconnection structure  15 . 
     Referring to  FIG. 14 , in an embodiment, a second chip  103   a  is formed. The formation of the second chip  103   a  includes preparing a second substrate  106  that has a first surface  106   s   1  and a second surface  106   s   2  that are opposite to each other, forming a separation structure  115  and photoelectric conversion devices PD in the second substrate  106 , forming a device isolation layer  118  on the first surface  106   s   1  of the second substrate  106  that defines an active region, forming a second circuit device  124  on the first surface  106   s   1  of the second substrate  106 , forming a second interconnection structure  127  on the first surface  106   s   1  of the second substrate  106 , and forming a second insulating layer  130  that covers the second circuit device  124  and the second interconnection structure  127 . However, the order of forming the separation structure  115 , the photoelectric conversion devices PD, and the device isolation layer  118  can be changed in other embodiments. 
     Referring to  FIG. 15A , in an embodiment, a wafer bonding process that bonds two wafers is performed that bond the first chip structure  3  and the second chip  103   a  to each other. The first insulating layer  18  of the first chip structure  3  and the second insulating layer  130  of the second chip  103   a  are bonded to each other. A grinding process is performed that reduces a thickness of the second substrate  106  of the second chip  103   a  and exposes the separation structure  115  in the second substrate  106 . 
     In an embodiment, the insulating structure  140  described in  FIGS. 2 and 3  is formed on the second surface  106   s   2  of the reduced thickness second substrate  106 . The first material pattern  145  illustrated in  FIGS. 2 and 4B  is formed on the insulating structure  140 . Therefore, a structure  103   b  that is formed up to the insulating structure  140  and the first material pattern  145  is prepared on the first chip structure  3 . 
     Referring to  FIG. 15C , in an embodiment, the second material pattern  147  is formed on the first material pattern  145 . Therefore, the grid pattern structure  150 , which includes the first pattern portion  150   a  that includes the first material pattern  145  and the second material pattern  147 , and the second pattern portions  150   b  formed of the same material as the second material pattern  147  are prepared. 
     Referring again to  FIGS. 1 and 2 , in an embodiment, the color filters  160  that cover the grid pattern structure  150  are formed on the insulating structure  140 , and the microlenses  170  are formed on the color filters  160 . 
     According to embodiments of the present inventive concept, one color filter overlaps a plurality of photoelectric conversion devices in a plurality of pixel regions to improve sensitivity of the color in an image sensor. 
     According to embodiments of the present inventive concept, a grid pattern structure includes a first pattern portion that includes a conductive material and is disposed between color filters of different colors and a second pattern portion that does not include a conductive material and has side surfaces and an upper surface that are covered by color filters of the same color. An image sensor with this grid pattern structure has increased sensitivity to the same color and reduced optical cross-talk. Therefore, the image sensor has increased resolution. 
     While exemplary embodiments have been illustrated and described above, it will be apparent to those skilled in the art that modifications and variations could be made without departing from the scope of embodiments of the present inventive concept as defined by the appended claims.