PATENT DOCUMENT

Publication Number: US-10690970-B2
Application Number: US-201615260082-A
Country: US
Kind Code: B2

Title: Display with hybrid column spacer structures

Abstract:
A liquid crystal display may have main column spacers and subspacer column spacers. The column spacers may have cross shapes formed from overlapping perpendicular rectangular column spacer portions respectively located on a color filter layer and a thin-film transistor layer. The column spacers may have a hybrid configuration in which some of the rectangular portions on the thin-film transistor layer extend vertically and some extend horizontally. Column spacers may be formed from planarization layer material, may be formed from locally thickened portions of a planarization layer, and may have circular shapes.

Claims:
What is claimed is: 
     
       1. A display having perpendicular first and second lateral dimensions, comprising:
 a color filter layer having an inner surface that lies plane parallel to a plane defined by the first and second lateral dimensions and an opposing outer surface; 
 a thin-film transistor layer having an outer surface and having an opposing inner surface that faces the inner surface of the color filter layer; 
 a layer of liquid crystal material between the color filter layer and the thin-film transistor layer; 
 main column spacers each of which has a first elongated portion on the inner surface of the thin-film transistor layer having a length along the first lateral dimension and having a width along the second lateral dimension that is shorter than its length and a second elongated portion on the inner surface of the color filter layer having a length along the second lateral dimension and having a width along the first lateral dimension that is shorter than its length, wherein the first elongated portion of each main column spacer is separated from the second elongated portion of that main column spacer by a first distance; and 
 subspacers each of which has a first elongated portion on the inner surface of the thin-film transistor layer having a length along the second lateral dimension and having a width along the first lateral dimension that is shorter than its length and a second elongated portion on the inner surface of the color filter layer having a length along the first lateral dimension and having a width along the second lateral dimension that is shorter than its length, wherein the first elongated portion of each subspacer is separated from the second elongated portion of that subspacer by a second distance, wherein the second distance is less than the first distance. 
 
     
     
       2. The display defined in  claim 1  wherein the thin-film transistor layer comprises a substrate layer, thin-film transistor circuitry on the substrate layer, and a planarization layer on the thin-film transistor circuitry. 
     
     
       3. The display defined in  claim 2  further comprising contact holes. 
     
     
       4. The display defined in  claim 3  wherein the first elongated portion of each subspacer fills at least one of the contact holes. 
     
     
       5. The display defined in  claim 3  wherein the first elongated portion of each subspacer fills three of the contact holes. 
     
     
       6. The display defined in  claim 3  further comprising indium-tin-oxide electrodes on the planarization layer. 
     
     
       7. The display defined in  claim 6  further comprising indium-tin-oxide structures in at least part of the contact holes. 
     
     
       8. The display defined in  claim 1  wherein the first elongated portion of each of the main column spacers and the second elongated portion of each of the main column spacers have rectangular outlines. 
     
     
       9. The display defined in  claim 8  wherein the first elongated portion of each of the subspacers and the second elongated portion of each of the subspacers have rectangular outlines. 
     
     
       10. The display defined in  claim 9  wherein the first and second elongated portions of each of the subspacers do not contact each other in absence of pressure that compresses the layer of liquid crystal material between the inner surface of the color filter layer and the inner surface of the thin-film transistor layer. 
     
     
       11. The display defined in  claim 1  further comprising polymer alignment layers on the inner surface of the color filter layer and the inner surface of the thin-film transistor layer. 
     
     
       12. The display defined in  claim 11  wherein the thin-film transistor layer comprises the planarization layer with contact holes and wherein at least some of the contact holes are filled with a polymer other than polymer from the polymer alignment layers. 
     
     
       13. A display, comprising:
 a color filter layer having an inner surface and an opposing outer surface; 
 a thin-film transistor layer having an outer surface and having an opposing inner surface that faces the inner surface of the color filter layer, wherein the thin-film transistor layer comprises a substrate layer, thin-film transistor circuitry on the substrate layer, and a planarization layer on the thin-film transistor circuitry; 
 contact holes which extend from the inner surface of the thin-film transistor layer through a portion of the thin-film transistor layer; 
 a layer of liquid crystal material between the color filter layer and the thin-film transistor layer; 
 subspacers that each have a color filter layer portion that is formed on the inner surface of the color filter layer and that extends along a first lateral dimension and have an opposing thin-film-transistor layer portion that is formed on the thin-film transistor layer and that extends along a second lateral dimension, wherein one of the thin-film-transistor layer portions fills first and second contact holes and wherein the first and second contact holes are in an active area of the display; and 
 main column spacers that each have a color filter layer portion that is formed on the inner surface of the color filter layer and that extends along the second lateral dimension and have an opposing thin-film-transistor layer portion that is formed on the thin-film transistor layer and that extends along the first lateral dimension. 
 
     
     
       14. The display defined in  claim 13  wherein the color filter layer comprises red, blue, and green color filter elements and wherein the thin-film transistor layer has chevron-shaped electrodes. 
     
     
       15. A display, comprising:
 a color filter layer having an inner surface and an opposing outer surface; 
 a thin-film transistor layer having an outer surface and having an opposing inner surface that faces the inner surface of the color filter layer, wherein the thin-film transistor layer comprises a substrate layer, thin-film transistor circuitry on the substrate layer, a planarization layer over the thin-film transistor circuitry; 
 contact holes which extend from the inner surface of the thin-film transistor layer through a portion of the thin-film transistor layer; 
 a layer of liquid crystal material between the color filter layer and the thin-film transistor layer; 
 main column spacers, wherein each of the main column spacers comprises:
 a first elongated portion on the inner surface of the thin-film transistor layer that extends along a first lateral dimension; and 
 a second elongated portion on the inner surface of the color filter layer that extends along a second lateral dimension; and 
 
 subspacers, wherein each of the subspacers comprises:
 a first elongated portion on the inner surface of the thin-film transistor layer that extends along the second lateral dimension and that at least partially fills at least two of the contact holes; and 
 a second elongated portion on the inner surface of the color filter layer that extends along the first lateral dimension. 
 
 
     
     
       16. The display defined in  claim 13  further comprising:
 an alignment layer on the thin-film transistor layer, wherein the alignment layer extends into a third contact hole and the one of the thin-film-transistor layer portions is interposed between the alignment layer and the first and second contact holes.

Description:
This application claims the benefit of provisional patent application No. 62/320,374, filed Apr. 8, 2016, which is hereby incorporated by reference herein in its entirety. 
    
    
     BACKGROUND 
     This relates generally to electronic devices, and more particularly, to electronic devices with displays. 
     Electronic devices often include displays. For example, cellular telephones and portable computers often include displays for presenting information to a user. 
     Liquid crystal displays contain a layer of liquid crystal material. Pixels in a liquid crystal display contain thin-film transistors and electrodes for applying electric fields to the liquid crystal material. The strength of the electric field in a pixel controls the polarization state of the liquid crystal material and thereby adjusts the brightness of the pixel. 
     Substrate layers such as color filter layers and thin-film transistor layers are used in liquid crystal displays. The thin-film transistor layer contains an array of the thin-film transistors that are used in controlling electric fields in the liquid crystal layer. The color filter layer contains an array of color filter elements such as red, blue, and green elements. The color filter layer provides the display with the ability to display color images. 
     In an assembled display, the layer of liquid crystal material is sandwiched between the thin-film transistor layer and the color filter layer. Alignment layers for aligning liquid crystals in the liquid crystal material cover the inner surface of the color filter layer and the upper surface of the thin-film transistor layer. An array of column spacers is formed in the liquid crystal layer between the color filter layer and the thin-film transistor layer to maintain a desired gap between the color filter layer and the thin-film transistor layer. 
     It can be challenging to design column spacers for a liquid crystal display. If care is not taken, the column spacers may not be sufficiently strong or may allow the alignment layers or other structures in a display to become damaged during use of the display. 
     SUMMARY 
     A display may have a color filter layer and a thin-film transistor layer. A layer of liquid crystal material may be located between the color filter layer and the thin-film transistor layer. Column spacers may be formed in the liquid crystal layer. 
     The column spacers may include color filter layer column spacer portions on the color filter layer and associated thin-film-transistor layer column spacer portions on the thin-film transistor layer. The column spacers may include main column spacers and subspacers and may be used to maintain a desired gap between the color filter and thin-film transistor layers and protect the inner surfaces of the color filter and thin-film transistor layers. 
     The column spacers may have cross shapes formed from overlapping perpendicular elongated portions on the color filter layer and thin-film transistor layer. The column spacers may have a hybrid configuration in which some of the rectangular portions on the thin-film transistor layer extend vertically and some extend horizontally. 
     Column spacers may be formed from planarization layer material, may be formed from locally thickened portions of a planarization layer, and may have circular shapes. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view of an illustrative electronic device with a display in accordance with an embodiment. 
         FIG. 2  is a cross-sectional side view of an illustrative display in accordance with an embodiment. 
         FIG. 3  is a cross-sectional side view of an illustrative color filter layer in accordance with an embodiment. 
         FIG. 4  is a cross-sectional side view of an illustrative thin-film transistor layer in accordance with an embodiment. 
         FIG. 5  is a top view of thin-film circuitry for three illustrative pixels in a display in accordance with an embodiment. 
         FIG. 6  is a cross-sectional side view of an illustrative display with column spacers in accordance with an embodiment. 
         FIG. 7  is a top view of an illustrative column spacer having a vertically extending thin-film transistor layer column spacer portion and a horizontally extending color filter layer column spacer portion in accordance with an embodiment. 
         FIG. 8  is a top view of an illustrative column spacer having a horizontally extending thin-film transistor layer column spacer portion and a vertically extending color filter layer column spacer portion in accordance with an embodiment. 
         FIG. 9  is a cross-sectional side view of an illustrative display in which a column spacer has a portion that covers and fills contact holes in the planarization layer of a thin-film transistor layer in accordance with an embodiment. 
         FIGS. 10 and 11  are top views of illustrative column spacer designs in accordance with embodiments. 
         FIG. 12  is a cross-sectional side view of an illustrative display in which a portion of a column spacer on a planarization layer in a thin-film transistor layer has been formed from thin-film transistor layer planarization layer material in accordance with an embodiment. 
         FIG. 13  is a cross-sectional side view of an illustrative display in which a thin-film transistor layer has a planarization layer that has been patterned with a half-tone mask so that regions of the planarization layer locally thickened and serve as portions of column spacers in accordance with an embodiment. 
         FIG. 14  is a top view of an illustrative circular column spacer in accordance with an embodiment. 
     
    
    
     DETAILED DESCRIPTION 
     Electronic devices may include displays. The displays may be used to display images to a user. An illustrative electronic device with a display is shown in  FIG. 1 . As shown in  FIG. 1 , electronic device  10  may have a housing such as housing  12 . Display  14  may be mounted in housing  12 . 
     Electronic device  10  may be a laptop computer, a computer monitor containing an embedded computer, a tablet computer, a cellular telephone, a media player, or other handheld or portable electronic device, a smaller device such as a wrist-watch device, a pendant device, a headphone or earpiece device, or other wearable or miniature device, a computer display that does not contain an embedded computer, a gaming device, a navigation device, an embedded system such as a system in which electronic equipment with a display is mounted in a kiosk or automobile, equipment that implements the functionality of two or more of these devices, or other electronic equipment. 
     Housing  12  of device  10 , which is sometimes referred to as a case, may be formed of materials such as plastic, glass, ceramics, carbon-fiber composites and other fiber-based composites, metal (e.g., machined aluminum, stainless steel, or other metals), other materials, or a combination of these materials. Device  10  may be formed using a unibody construction in which most or all of housing  12  is formed from a single structural element (e.g., a piece of machined metal or a piece of molded plastic) or may be formed from multiple housing structures (e.g., outer housing structures that have been mounted to internal frame elements or other internal housing structures). 
     Display  14  may be a touch sensitive display that includes a touch sensor or may be insensitive to touch. Touch sensors for display  14  may be formed from an array of capacitive touch sensor electrodes, a resistive touch array, touch sensor structures based on acoustic touch, optical touch, or force-based touch technologies, or other suitable touch sensor components. 
     Display  14  may be a liquid crystal display or other suitable display. A display cover layer may cover the surface of display  14  or a display layer such as a color filter layer or other portion of a display may be used as the outermost (or nearly outermost) layer in display  14 . The outermost display layer may be formed from a transparent glass sheet, a clear plastic layer, or other transparent member. 
     A cross-sectional side view of an illustrative configuration for display  14  of device  10  is shown in  FIG. 2 . As shown in  FIG. 2 , display  14  may include backlight structures such as backlight unit  42  for producing backlight  44 . During operation, backlight  44  travels outwards (vertically upwards in dimension Z in the orientation of  FIG. 2 ) and passes through pixels in display layers  46 . This illuminates any images that are being produced by the pixels for viewing by a user. For example, backlight  44  may illuminate images on display layers  46  that are being viewed by viewer  48  in direction  50 . 
     Display layers  46  may be mounted in chassis structures such as a plastic chassis structure and/or a metal chassis structure to form a display module for mounting in housing  12  or display layers  46  may be mounted directly in housing  12  (e.g., by stacking display layers  46  into a recessed portion in housing  12 ). 
     Display layers  46  may include a liquid crystal layer such a liquid crystal layer  52 . Liquid crystal layer  52  may be sandwiched between display layers such as display layers  58  and  56 . Layers  56  and  58  may be interposed between lower polarizer layer  60  and upper polarizer layer  54 . 
     Layers  58  and  56  may be formed from transparent substrate layers such as clear layers of glass or plastic. Layers  56  and  58  may be layers such as a thin-film transistor layer and/or a color filter layer. Conductive traces, color filter elements, transistors, and other circuits and structures may be formed on the substrates of layers  58  and  56  (e.g., to form a thin-film transistor layer and/or a color filter layer). Touch sensor electrodes may also be incorporated into layers such as layers  58  and  56  and/or touch sensor electrodes may be formed on other substrates. 
     With one illustrative configuration, layer  58  may be a thin-film transistor layer that includes an array of thin-film transistors and associated electrodes (pixel electrodes) for applying electric fields to liquid crystal layer  52  and thereby displaying images on display  14 . Layer  56  may be a color filter layer that includes an array of color filter elements for providing display  14  with the ability to display color images. If desired, layer  58  may be a color filter layer and layer  56  may be a thin-film transistor layer. Configurations in which layer  56  includes both color filter elements and thin-film transistor structures and in which layer  58  is a clear substrate layer may also be used. Configurations in which layer  56  is a color filter layer and layer  58  is a thin-film transistor layer are sometimes described herein as an example. 
     During operation of display  14  in device  10 , control circuitry (e.g., one or more integrated circuits on a printed circuit) may be used to generate information to be displayed on display  14  (e.g., display data). The information to be displayed may be conveyed to a display driver integrated circuit such as circuit  62 A or  62 B using a signal path such as a signal path formed from conductive metal traces in a rigid or flexible printed circuit such as printed circuit  64  (as an example). 
     Backlight structures  42  may include a light guide plate such as light guide plate  78 . Light guide plate  78  may be formed from a transparent material such as clear glass or plastic. During operation of backlight structures  42 , a light source such as light source  72  may generate light  74 . Light source  72  may be, for example, an array of light-emitting diodes. 
     Light  74  from light source  72  may be coupled into edge surface  76  of light guide plate  78  and may be distributed in dimensions X and Y throughout light guide plate  78  due to the principal of total internal reflection. Light guide plate  78  may include light-scattering features such as pits or bumps. The light-scattering features may be located on an upper surface and/or on an opposing lower surface of light guide plate  78 . 
     Light  74  that scatters upwards in direction Z from light guide plate  78  may serve as backlight  44  for display  14 . Light  74  that scatters downwards may be reflected back in the upward direction by reflector  80 . Reflector  80  may be formed from a reflective material such as a layer of white plastic, a dielectric stack that forms a mirror coating on a carrier film, or other shiny materials. 
     To enhance backlight performance for backlight structures  42 , backlight structures  42  may include optical films  70 . Optical films  70  may include diffuser layers for helping to homogenize backlight  44  and thereby reduce hotspots, compensation films for enhancing off-axis viewing, and brightness enhancement films (also sometimes referred to as turning films) for collimating backlight  44 . Optical films  70  may overlap the other structures in backlight unit  42  such as light guide plate  78  and reflector  80 . For example, if light guide plate  78  has a rectangular footprint in the X-Y plane of  FIG. 2 , optical films  70  and reflector  80  may have a matching rectangular footprint. If desired, compensation films may be incorporated into other layers in display  14  (e.g., a polarizer layer). 
     Display  14  may include an array of pixels. The pixels may be controlled using control signals produced by display driver circuitry. Display driver circuitry may be implemented using one or more integrated circuits (ICs) and/or thin-film circuitry (e.g., thin-film circuitry on layer  58 ). 
     During operation of device  10 , control circuitry in device  10  such as memory circuits, microprocessors, and other storage and processing circuitry may provide data to the display driver circuitry. The display driver circuitry may convert the data into signals for controlling the pixels of display  14 . Display  14  may contain rows and columns of pixels. The pixels may be controlled using signals such as data line signals on data lines and gate line signals on gate lines. 
     The pixels may contain thin-film transistor circuitry and associated structures for producing electric fields across liquid crystal layer  52  in display  14 . Each pixel may have a respective thin-film transistor to control the application of a voltage to a set of electrodes and thereby control electric fields applied to a respective pixel-sized portion of liquid crystal layer  52 . 
     The thin-film transistor structures that are used in forming the pixels of display  14  may be located on a substrate such as a layer of glass. The substrate and the structures of the pixels that are formed on the surface of the thin-film transistor substrate collectively form thin-film transistor layer  58 . 
     Gate driver circuits in the display driver circuitry may be used to generate gate signals on gate lines in display  14 . The gate driver circuitry may be formed from thin-film transistors on thin-film transistor layer  58  or may be implemented in separate integrated circuits. Gate driver circuitry may be located on both the left and right sides of the array of pixels in display  14  or on one side of the pixel array. 
     The data line signals on the data lines of display  14  carry analog image data (e.g., voltages with magnitudes representing pixel brightness levels). The data line signals on the data lines are distributed to the columns of pixel. Gate line signals on gate lines that run perpendicular to the data lines are provided to the rows of pixels. During operation of display  14 , gate line signals may be asserted in sequence to load successive rows of pixels with image data. Storage capacitors in the pixels may be used to retain data between frames. Electrodes in each pixel may be used to apply electric files to liquid crystal layer  52 . The electric field that is produced across liquid crystal material  52  causes a change in the orientations of the liquid crystals in liquid crystal material. This changes the polarization of light passing through liquid crystal material in the pixel associated with the electrodes. The change in polarization may, in conjunction with polarizers  60  and  54  of  FIG. 2 , be used in controlling the amount of light  44  that is transmitted through each pixel of display  14 . 
     A cross-sectional side view of an illustrative color filter layer is shown in  FIG. 3 . As shown in  FIG. 3 , color filter layer  56  may have a color filter layer substrate such as substrate  90  (e.g., a layer of clear glass or transparent plastic, etc.). An array of color filter elements  92  may be formed in openings in black matrix  94 . Color filter elements  92  may include red, green, and blue color filter elements or color filter elements of other colors. Each color filter element imparts color to the light exiting a respective pixel in display  14 . Color filter elements  92  and substrate  90  (sometimes collectively referred to as color filter layer  56 - 1 ) may be coated with a polymer alignment layer such as alignment layer  56 - 2 . Alignment layer  56 - 2  may be processed so that alignment layer  56 - 2  imparts a desired liquid crystal alignment to the liquid crystals in layer  52  when layer  56  is used in display  14  (i.e., layer  56 - 2  may serve as a liquid crystal alignment layer). 
     A cross-sectional side view of a portion of thin-film transistor layer  58  is shown in  FIG. 4 . As shown in  FIG. 4 , thin-film transistor layer  58  may include substrate  96  (e.g., a transparent glass substrate layer, a layer of clear plastic, etc.). Thin-film circuitry for forming pixel circuits for the pixels of display  14  may be formed on substrate  96 . This circuitry may include thin-film circuitry layer  98 , planarization layer  100 , and structures such as pixel electrodes  102 . Thin-film circuitry  98  may be used in forming thin-film transistors, capacitors, and other circuitry. In the active area of display  14  that contains pixels, circuitry  98  may form pixel circuits. In the inactive border regions of display  14 , circuitry  98  may form display driver circuitry (e.g., thin-film gate driver circuitry, etc.). 
     Planarization layer  100  may be deposited as a polymeric liquid and cured to form a polymer planarization layer. Electrodes  102  may include multiple chevron-shaped fingers or other electrode structures for applying electric fields to liquid crystal layer  52 . Indium tin oxide or other transparent conductive materials may be used in forming electrodes  102 . Openings may be formed in planarization layer  100  such as contact hole opening  104 . A transistor terminal may be located at the bottom of hole  104  and may be contacted by conductive indium tin oxide structures  102 ′, which short the transistor terminal to electrodes  102 . Substrate  96 , thin-film circuitry  98 , and planarization layer  100 , which may sometimes be collectively referred to as thin-film transistor layer  56 - 1 , may be coated with a polymer that serves as liquid crystal alignment layer  58 - 2 . 
       FIG. 5  is a top view of a portion of display  14  showing where contact holes  104  may be located relative to electrodes  102  in three illustrative pixels (e.g. green pixel GP, blue pixel BP, and red pixel RP) in display  14 .  FIG. 5  also shows illustrative locations for data lines D and gate lines G. Areas such as illustrative area  106  (e.g., an area between blue and red pixel contact holes  104 ) or other suitable areas of display  14  may be provided with column spacers that prevent direct contact between the inner surfaces of color filter layer  56  and thin-film transistor layer  58 . 
     The column spacers may be distributed more sparsely than the pixels of display  14 . For example, there may be a main column spacer (i.e., a spacer that completely spans layer  52  between layers  56  and  58 ) every 40-50 pixels in display  14 . The column spacers may also include subspacers (i.e., spacers that do not completely span layer  52  except when layer  52  is compressed by applied pressure on display  14 ). There may be 10-20 subspacer column spacers for every 45 pixels in display  14 . Other densities of column spacers may be used, if desired. 
       FIG. 6  is a cross-sectional side view of an illustrative display with column spacers. As shown in  FIG. 14 , display  14  may have a color filter layer  56 , a thin-film transistor layer  58 , and liquid crystal layer  52  between layers  56  and  58 . Column spacers  108  may be used to prevent direct contact between the inner surface of layer  56  and the opposing inner surface of layer  58 . Direct contact could lead to scratching of alignment layers  58 - 2  and  56 - 2  and other damage. 
     Column spacers  108  may include main column spacers such as main column spacer  108 A. Main column spacer  108 A may have a thin-film transistor layer column spacer portion  110  of height T 3  and an opposing color filter layer column spacer portion  112  of height T 1 . Portions  110  and  112  normally contact each other as shown in  FIG. 6  and maintain a desired cell gap (thickness T 5 ) between layers  56  and  58 . Column spacers  108  may also include subspacers such as subspacer  108 B. Subspacer  108 B may include thin-film transistor layer sub spacer column spacer portion  114  of height T 4  and a corresponding color filter layer subspacer column spacer portion  108  of height T 2 . The magnitude of T 1  plus T 3  establishes cell gap T 5 . The magnitude of T 2  plus T 4  is less than T 1  plus T 3  (i.e., column spacer portions  114  and  108  do not normally touch each other unless force is being applied to display  14 ). In general, T 1 , T 2 , T 3 , and T 4  may have any suitable magnitudes. As one example, T 5  may be 1.7 to 1.8 microns (or more than 1 micron or less than 3 microns), T 1  may be 1.7 microns (or more than 1 micron or less than 2 microns), T 3  may be 1.5 to 2 microns (or more than 1 micron or less than 3 microns), T 2  may be 1.3 microns (or more than 1 micron or less than 2 microns), T 4  may be 1.8 microns or more than 1 or less than 3 microns, etc. 
     The column spacer portions that form column spacers  108  may have elongated shapes (e.g., rectangular shapes) that extend vertically (along lateral dimension Y when display  14  is viewed from the top) or that extend horizontally (along lateral dimension X when display  14  is viewed from the top). These perpendicular column spacer portions may cross over each other so that the outline (footprint) of column spacers  108  has a cross shape when viewed from above, as shown in  FIGS. 7 and 8 . Configurations in which the thin-film transistor layer column spacer portion (e.g., portion  110  or portion  114  of  FIG. 6 ) of a main column spacer or subspacer extends vertically while the color filter layer column spacer portion (e.g., portion  112  or portion  116  of  FIG. 6 ) of a main column spacer or subspacer extends horizontally may sometimes be referred to as “vertical bump” column spacers. Configurations in which the thin-film transistor layer column spacer portion (e.g., portion  110  or portion  114  of  FIG. 6 ) of a main column spacer or subspacer extends horizontally while the color filter layer column spacer portion (e.g., portion  112  or portion  116  of  FIG. 6 ) of a main column spacer or subspacer extends vertically may sometimes be referred to as “horizontal bump” column spacers. 
     Column spacer portions may be rectangular or may have other shapes. Rectangular column spacers may have narrower lateral dimensions (widths) of about 7-10 microns, more than 5 microns, or less than 15 microns) and may have longer lateral dimensions (lengths) of about 15-50 microns, more than 10 microns, or less than 50 microns). 
     An illustrative vertical bump column spacer is shown in  FIG. 7 . The column spacer portion on layer  58  (labeled “TFT”) has longitudinal axis  122  running parallel to vertical dimension Y and the column spacer portion on layer  56  (labeled “CF”) has longitudinal axis  120  running parallel to horizontal dimension X. 
     An illustrative horizontal bump column spacer is shown in  FIG. 8 . The column spacer portion on layer  58  (labeled “TFT”) has longitudinal axis  124  running parallel to horizontal dimension X and the column spacer portion on layer  56  (labeled “CF”) has longitudinal axis  126  running parallel to vertical dimension Y. 
     Display  14  may have any suitable combination of vertical and/or horizontal bump column spacers for forming its main column spacers and/or subspacers. The vertical bump configuration may exhibit better mechanical strength than the horizontal bump configuration, so it may be desirable to use the vertical bump configuration in forming the main column spacers. There is a relatively large step in height between the top of the thin-film transistor layer column spacer portion and the bottom of contact holes  104  in vertical bump designs, which can cause some of the polymer that forms layer  58 - 2  to enter contact holes  104  and produce non-uniformity in layer  58 - 2  that results in undesired visible artifacts. Horizontal bump designs can be configured so that the thin-film-transistor layer column spacer portion covers and therefore fills contact holes  104 , reducing non-uniformity in layer  58 - 2 . In view of these considerations, it may be desirable for display  14  to have a hybrid column spacer design in which the main column spacers are formed using vertical bump column spacer configurations and in which the subspacer column spacers are formed using horizontal bump column spacer configurations. This type of configuration is shown in  FIG. 9  in which main column spacer  108 A has a vertical bump configuration and in which subspacer  108 B has a horizontal bump configuration. 
     As shown in  FIG. 9  and as illustrated in the top view of  FIG. 10 , portion  114  may overlap and fill contact holes  104  (e.g., a pair of adjacent contact holes  104 ), thereby helping to improve uniformity for alignment layer  58 - 2 . If desired, portions  114  may extend sufficiently to cover three or more contact holes  104  (see, e.g., portion  114  in illustrative subspacer  108 B of display  14  of  FIG. 11 ). As illustrated in  FIGS. 10 and 11 , portions  110  and  112  extend perpendicular to each other to form cross-shaped main column spacers  108 A and portions  114  and  116  may extend perpendicular to each other to form cross-shaped subspacers  108 B (as an example). 
     If desired, column spacer structures on thin-film transistor layer  58  may be formed from the same material as planarization layer  100  (e.g., positive photoresist such as positive acrylic photoresist or other photoimageable polymer). This reduces process complexity and facilitates fabrication. An illustrative display with this type of column spacer is shown in  FIG. 12 . As shown in  FIG. 12 , planarization layer  100  may be formed on thin-film circuitry  98  and substrate  96 . Column spacer  108  (a main column spacer or subspacer) may have thin-film-transistor layer portion  108 - 1  on layer  100  of layer  58  and may have color filter layer portion  108 - 2  on color filter layer  56 . Portion  108 - 1  may be formed from the same material as layer  100 . 
     In the illustrative configuration of  FIG. 13 , planarization layer  100  has been photolithographically patterned using a half-tone photolithographic mask. The half-tone mask exposes portion  100 ′ of planarization layer  100  under column spacer portion  108 - 1  of column spacer  108  differently than the rest of layer  100 , so that, following development, planarization layer portion  100 ′ has a thickness TA that is greater than the thickness (TB) of layer  100  elsewhere in display  14 . As a result, the column spacer portion  108 - 2  is formed as an integral portion of thickened planarization layer portion  100 ′. 
     If desired, column spacers  108  may have circular shapes. As shown in  FIG. 14 , for example, column spacer  108  may have a first circular portion (portion CF) that is formed on color filter layer  56  and a second circular portion (portion TFT) that is formed on thin-film-transistor layer  58 . The circular shapes of portions CF and TFT may help ensure a constant contact area between the upper and lower portions of the column spacer even when layers  56  and  58  are slightly misaligned. 
     The foregoing is merely illustrative and various modifications can be made by those skilled in the art if desired.

Metadata:
Filing Date: 20160908
Publication Date: 20200623
Grant Date: 20200623
Priority Date: 20160408
Inventors: TAI, CHIA HSUAN
CHEN, CHENG
YU, Da
DORJGOTOV, ENKHAMGALAN
CHOI, SANG UN
FAN JIANG, SHIH-CHYUAN
CHA, TAE WOON
HAM, YEON SIK
CHEN, YUAN
GE, ZHIBING
NEMATI, HOSSEIN
Assignee: APPLE INC
CPC Classifications: [{"code": "G02F1/133357", "inventive": false, "first": false, "tree": "[]"}, {"code": "G02F1/133357", "inventive": false, "first": false, "tree": "[]"}, {"code": "G02F1/13396", "inventive": false, "first": false, "tree": "[]"}, {"code": "G02F1/13398", "inventive": false, "first": false, "tree": "[]"}, {"code": "G02F1/136227", "inventive": false, "first": false, "tree": "[]"}, {"code": "G02F1/133514", "inventive": true, "first": false, "tree": "[]"}, {"code": "G02F1/13394", "inventive": true, "first": true, "tree": "[]"}, {"code": "G02F1/136227", "inventive": false, "first": false, "tree": "[]"}, {"code": "G02F1/13394", "inventive": true, "first": true, "tree": "[]"}, {"code": "G02F1/1368", "inventive": true, "first": false, "tree": "[]"}, {"code": "G02F1/137", "inventive": false, "first": false, "tree": "[]"}, {"code": "G02F1/136286", "inventive": false, "first": false, "tree": "[]"}, {"code": "G02F1/133528", "inventive": false, "first": false, "tree": "[]"}, {"code": "G02F1/13338", "inventive": false, "first": false, "tree": "[]"}, {"code": "G06F3/0412", "inventive": false, "first": false, "tree": "[]"}, {"code": "G02F1/13439", "inventive": true, "first": false, "tree": "[]"}, {"code": "G02F1/13394", "inventive": true, "first": true, "tree": "[]"}, {"code": "G02F1/133711", "inventive": true, "first": false, "tree": "[]"}, {"code": "G02F2201/123", "inventive": false, "first": false, "tree": "[]"}, {"code": "G02F1/1368", "inventive": true, "first": false, "tree": "[]"}, {"code": "G02F1/133528", "inventive": false, "first": false, "tree": "[]"}, {"code": "G02F1/137", "inventive": false, "first": false, "tree": "[]"}, {"code": "G02F1/136227", "inventive": false, "first": false, "tree": "[]"}, {"code": "G02F2001/13398", "inventive": false, "first": false, "tree": "[]"}, {"code": "G02F1/136286", "inventive": false, "first": false, "tree": "[]"}, {"code": "G02F1/133711", "inventive": true, "first": false, "tree": "[]"}, {"code": "G02F1/13439", "inventive": true, "first": false, "tree": "[]"}, {"code": "G02F2201/123", "inventive": false, "first": false, "tree": "[]"}, {"code": "G02F2001/133357", "inventive": false, "first": false, "tree": "[]"}, {"code": "G06F3/0412", "inventive": false, "first": false, "tree": "[]"}, {"code": "G02F1/13338", "inventive": false, "first": false, "tree": "[]"}, {"code": "G02F1/13394", "inventive": true, "first": true, "tree": "[]"}, {"code": "G02F1/133514", "inventive": true, "first": false, "tree": "[]"}]
Family ID: 59998699