Display screen with light emitting diodes

Abstract

This specification relates to a display screen (25) comprising a support (26) having opposing first and second surfaces (30 and 28) with holes (32) in the first surface (30), photoluminescent blocks (34, 36) in at least some of the holes, an adhesive layer (40) covering the first surface, display subpixels (SPix) bonded to the support by the adhesive layer, each display subpixel having a third surface (59) on the support side and a fourth surface (54) opposite the third surface and a conductive pad (56) exposed on the fourth surface, a filler layer (42) covering the first surface between the display subpixels, and a conductive track (44) extending to the filler layer and the fourth surface of the display subpixel and in electrical and mechanical contact with the conductive pad.

Description

[Technical field]

[0001] The present disclosure relates generally to display screens with light emitting diodes. [Background technology]

[0002] A pixel of an image corresponds to a unit element of an image displayed by a display screen. To display a color image, a display screen generally comprises at least three elements, also called display sub-pixels, each emitting radiation light in a substantially single color (e.g. red, green and blue) to display each pixel of the image. The superposition of the radiation emitted by the three display sub-pixels gives the observer a sense of coloring corresponding to the pixel of the displayed image. In this case, the ensemble formed by the three display sub-pixels used to display a pixel of the image is called a display pixel of the display screen. Each display sub-pixel may have a light source, in particular a light-emitting diode.

[0003] The display pixels may be distributed in an array, with each display pixel located at the intersection of a row (or line) and a column of the array. Typically, each row of display pixels is selected in succession and the display pixels of the selected row are programmed to display a desired image pixel.

[0004] Depending on the light emitting diode fabrication technology used, for a particular display subpixel it may be necessary to cover the light emitting diode of the display subpixel with a photoluminescent block containing luminophores that are adapted to emit light at a wavelength different from the wavelength of the light emitted by the associated light emitting diode when excited by the light emitted by the associated light emitting diode.

[0005] An active array is a screen driving configuration that can keep all pixel rows active for the entire duration of an image, as opposed to an array called passive, where each row is only active for T=Tframe / N (where Tframe is the duration of the image and N is the number of rows on the screen). This allows for increased brightness of the display screen. Furthermore, a larger data flow can be displayed, since lower voltage or current levels can be sent across the control lines of the array. Summary of the Invention [Problem to be solved by the invention]

[0006] In a method for manufacturing a display screen using an active array, light-emitting diodes are deposited on a support, also called a panel, which contains the driving electronics of the display pixels, and a photoluminescent block is formed over the light-emitting diode of the corresponding display subpixel. In order to improve the contrast of the display screen, it is further possible to form a black opaque layer on the panel with an opening at the level of each display subpixel. A disadvantage of such a manufacturing method is that it can be complicated.

[0007] It is an object of the embodiments to provide a display screen with light emitting diodes that overcomes all or part of the disadvantages of existing display screens with light emitting diodes. [Means for solving the problem]

[0008] An embodiment is a display screen, comprising: a support having opposed first and second surfaces, the first surface having holes; A glittering block provided in at least a portion of the hole; an adhesive layer covering the first surface; a display subpixel bonded to the support by the adhesive layer, the display subpixel having a third surface on the support side, a fourth surface located opposite the third surface, and a conductive pad exposed on the fourth surface; a filler layer covering the first surface between the display subpixels; a conductive track extending over the filler layer and over a fourth surface of the display subpixel, the conductive track being in electrical and mechanical contact with the conductive pad; The present invention provides a display screen comprising:

[0009] Such a structure allows the display subpixels to be transferred directly to a substrate containing the photoluminescent blocks, as opposed to the conventional method of depositing the display pixels / subpixels on a panel containing the control electronics and then forming the photoluminescent blocks on the display pixels / subpixels, thus facilitating the manufacture of the photoluminescent blocks.

[0010] According to an embodiment, each display sub-pixel has a light emitting diode closer to the third surface than to the fourth surface.

[0011] According to an embodiment, each display subpixel comprises a stack of a first electronic circuit comprising said light emitting diode and a second electronic circuit comprising electronic components configured to control said light emitting diode. For each display subpixel, it is therefore possible to integrate the control electronics of the light emitting diode of the display subpixel directly in the display subpixel. Thus, the number of transfers of the components forming the display screen is limited. The second electronic circuit does not interfere with the radiation emitted by the light emitting diode and does not occupy too much space on the surface of the support. Furthermore, after transfer to the support, there is no need to form an electrical link or electrical connection between the first electronic circuit and the second electronic circuit.

[0012] According to an embodiment, the filler layer reflects radiation emitted by the display sub-pixels and the photoluminescent block, so that for each display sub-pixel, there may be an improved guidance of radiation emitted by the light emitting diode of the display sub-pixel towards the hole facing the display sub-pixel.

[0013] According to an embodiment, the display screen further comprises a first layer that is opaque to radiation emitted by the display subpixels and the photoluminescent blocks facing the first surface and has openings facing the third surface of each display subpixel, thereby improving the contrast of the display screen.

[0014] According to an embodiment, the display screen comprises, in at least another part of the hole, a block of material scattering the radiation emitted by the display sub-pixels, so that for each display sub-pixel located opposite a block of scattering material, it is possible to improve the uniformity of the intensity of the radiation emitted by the display sub-pixels.

[0015] According to an embodiment, the support has a base that is transparent to radiation emitted by the display sub-pixels and radiation emitted by the photoluminescent block covered by the second layer that includes the holes, which may facilitate the manufacture of the support.

[0016] According to an embodiment, the second layer reflects the radiation emitted by the display sub-pixel and the photoluminescent block, which may improve the guidance of the radiation emitted by the light emitting diode of the display sub-pixel to the hole.

[0017] According to an embodiment, the display screen further comprises a third layer between the base and the second layer, the third layer being transparent to emitted light emitted by the display subpixels and the photoluminescent blocks and having a refractive index less than 2. The third layer may enable bonding of the second layer to the base.

[0018] According to an embodiment, the display screen comprises a coating that reflects radiation emitted by the display sub-pixels and the photoluminescent blocks and covers the side walls of each hole, thereby improving the guidance of radiation emitted by the light emitting diodes of the display sub-pixels to the holes.

[0019] According to an embodiment, the display screen includes a fourth layer that is transparent to the radiation emitted by the display subpixels and the photoluminescent block, has a refractive index of less than 1.5, and covers the bottom of each hole. The fourth layer can increase the conversion efficiency of the photoluminescent block.

[0020] According to an embodiment, the display screen includes a color filter layer disposed in the hole containing the photoluminescent block between the photoluminescent block and the bottom of the hole, thereby improving the emission spectrum of the radiation emitted from the emission surface.

[0021] According to an embodiment, the photoluminescent block comprises quantum dots.

[0022] An embodiment is a method for manufacturing a display screen as previously defined, comprising the steps of: forming the holes in a first surface of the support; forming the photoluminescent block in at least a portion of the hole; depositing an adhesion layer overlying the first surface; disposing the display subpixels on the third surface side and bonding them to the support by the adhesive layer; forming the fill layer covering the first surface between the display subpixels; and forming a conductive track extending over the filler layer and over a fourth surface of the display subpixel; The method further comprises:

[0023] In contrast to the conventional method of depositing display pixels / subpixels on a panel containing control electronics and then forming photoluminescent blocks on the display pixels / subpixels, the present method transfers the display pixels / subpixels directly onto a support containing photoluminescent blocks, thus simplifying the manufacture of display screens.

[0024] According to an embodiment, the method comprises: forming a wafer including a plurality of display subpixels; and sawing the wafer to separate the display sub-pixels. has. [Brief description of the drawings]

[0025] The foregoing and other features and advantages are described in detail in the remainder of the present disclosure of specific embodiments, given by way of non-limiting example with reference to the accompanying drawings, in which:

[0026] [Figure 1] FIG. 2 illustrates, partially and diagrammatically, an example of a display screen. [Diagram 2] 1 is a schematic partial cross-sectional view illustrating an embodiment of a display screen. [Diagram 3] 1 is a schematic partial cross-sectional view illustrating another embodiment of a display screen. [Figure 4] 1 is a schematic partial cross-sectional view illustrating another embodiment of a display screen. [Diagram 5] 1 is a schematic partial cross-sectional view illustrating another embodiment of a display screen. [Figure 6] 1 is a schematic partial cross-sectional view illustrating another embodiment of a display screen. [Figure 7] 1 is a schematic partial cross-sectional view illustrating another embodiment of a display screen. [Figure 8] 1 is a schematic partial cross-sectional view illustrating another embodiment of a display screen. [Figure 9] 1 is a simplified partial cross-sectional view illustrating an embodiment of a display subpixel. [Figure 10] 3A-3D illustrate steps of an embodiment of a method for manufacturing the display screen of FIG. 2. [Figure 11] FIG. 2 illustrates another step of the method. [Figure 12] FIG. 2 illustrates another step of the method. [Figure 13] FIG. 2 illustrates another step of the method. [Figure 14] FIG. 2 illustrates another step of the method. [Figure 15] FIG. 2 illustrates another step of the method. [Figure 16] FIG. 2 illustrates another step of the method. [Figure 17] 7A-7D illustrate steps of an embodiment of a method for manufacturing the display screen of FIG. [Figure 18] FIG. 2 illustrates another step of the method. [Figure 19] FIG. 2 illustrates another step of the method. [Figure 20] FIG. 2 illustrates another step of the method. [Figure 21] FIG. 2 illustrates another step of the method. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0027] In the various figures, similar features are indicated by similar reference numerals. In particular, structural and / or functional features common to the various embodiments may have the same reference numerals and may have the same structural, dimensional and material characteristics. For clarity, only those steps and elements useful for understanding the embodiments described herein are shown and described in detail.

[0028] Unless otherwise indicated, when referring to two elements connected together, this refers to a direct connection without any intermediate elements other than conductors, and when referring to two elements coupled together, this refers to the two elements may be connected or may be coupled through one or more other elements. Further, in this specification, the terms "insulating" and "conducting" are deemed to refer to "electrically insulating" and "electrically conducting", respectively.

[0029] In the following description, when reference is made to terms defining absolute positions such as "front", "back", "top", "bottom", "left" and "right", or terms defining relative positions such as "above", "below", "upper" and "lower", or terms defining orientations such as "horizontal" and "vertical", this term refers to the display screen in its drawing orientation or normal position of use, unless otherwise specified.

[0030] Unless otherwise specified, the terms "about," "approximately," "substantially," and "to the extent of" refer to within 10%, preferably within 5%, of the relevant value.

[0031] In the following description, the internal transmittance of a layer corresponds to the ratio of the intensity of the radiation leaving the layer to the intensity of the radiation entering the layer. The absorptance of a layer is the difference between 1 (corresponding to perfect transmittance where the entire incident light is transmitted) and the internal transmittance. In the following description, a layer is transparent to radiation if the absorption of radiation through the layer is less than 75%. In the following description, a layer is absorbing or opaque to radiation if the absorption of radiation in the layer is more than 75%. In the following description, a layer is reflective to radiation if the reflectance of radiation by the layer is more than 75%. In the following description, the refractive index of a material corresponds to the refractive index of the material for the wavelength range of the radiation emitted by the light source of the image acquisition system. If not otherwise indicated, the refractive index is considered to be substantially constant over the wavelength range of the radiation emitted by the light source of the image acquisition system, e.g., equal to the average of the refractive index over the wavelength range of the radiation emitted by the light source of the image acquisition system.

[0032] 1 partially and diagrammatically illustrates an example of a display screen 10. The display screen 10 comprises display pixels 12 arranged, for example, in M ​​rows and N columns. i,j where M is an integer ranging from 1 to 8,000, N is an integer ranging from 1 to 16,000, i is an integer ranging from 1 to M, and j is an integer ranging from 1 to N. As an example, in FIG. 1, M and N are 6. Each display pixel 12 i,j Electrode 14 i via a low reference potential source Gnd, e.g., ground, and the electrode 16 j 1. The electrode 14 is connected to a high reference potential source Vcc via i are shown aligned along a row in FIG. 1, and electrodes 16 j are shown aligned along a column in Figure 1, although an inverse arrangement is possible. The power supply voltage of the display screen corresponds to a voltage between a high reference potential Vcc and a low reference potential Gnd.

[0033] For each row, 12 display pixels in the row i,j Row electrode 18 i For each column, the display pixels 12 in the column are connected to i,j is column electrode 20 j The display screen 10 is connected to row electrodes 18. i The selection circuit 22 is coupled to each row electrode 18. i Select Timing Signal Com i The display screen 10 is adapted to provide column electrodes 20 j The data supply circuit 24 is coupled to each column electrode 20. j Data signal j The selection circuit 22 and the data supply circuit 24 are controlled by a circuit 23 which may for example include a microprocessor.

[0034] According to an embodiment, each display pixel comprises a number of display sub-pixels, each of which may comprise a control circuit covered by the display circuit. The display circuit may comprise one or more light-emitting diodes. According to another embodiment, the sub-pixels of one and the same pixel are integrated into one display circuit associated to one control circuit. The control circuit may correspond to an integrated circuit including electronic components, in particular insulated gate field effect transistors, also called MOS transistors, or thin film transistors, also called TFT transistors, arranged to control the light-emitting diode or diodes of the display circuit. Such a display pixel is called a smart pixel.

[0035] 2 is a partial cross-sectional schematic diagram illustrating an embodiment of a display screen 25 having smart display sub-pixels SPix. From bottom to top in FIG. a support 26 having two opposite surfaces 28 and 30 (surface 28 corresponds to the emitting surface of the display screen); - holes 32 provided in the surface 30 at the location of certain display sub-pixels SPix, each having a bottom 33 and a sidewall 35; - the glittering blocks 34, 36 filling the holes 32; an opaque layer 38 covering the surface 30 of the support 26, the opaque layer 38 being intersected by openings 39 exposing the glittering blocks 34, 36 and a portion of the surface 30 of the support 26; an adhesive layer 40 covering the opaque layer 38 and covering the surface 30 of the photoluminescent block 34, 36 or the support 26 within the opening 39; - display sub-pixels SPix (three display sub-pixels are shown as an example in FIG. 2) facing the openings 39 and bonded to the support 26 by adhesive layers 40; a filler layer 42 covering the adhesive layer 40 between the display sub-pixels SPix; a conductive track 44 extending over the fill layer 42 and over the display subpixel SPix; It is equipped with:

[0036] Each display sub-pixel SPix has a control circuit 50 which is covered by a display circuit 52 .

[0037] The control circuit 50 has two opposite, preferably parallel, surfaces 54 and 55. The control circuit 50 is bonded to the display circuit 52 at the surface 55. The control circuit 50 further comprises a conductive pad 56 exposed at the surface 54. The control circuit 50 may comprise a semiconductor substrate, not shown, covered with at least one metallization level, not shown. In particular, the control circuit 50 may correspond to an integrated circuit including electronic components, in particular MOS transistors or TFT transistors. The control circuit 50 may further comprise conductive through-vias, not shown, extending over a portion of the thickness of the control circuit 50, by means of which the conductive pads 56 can be connected to other electronic components of the general control circuit or directly to the display circuit 52. All electrical connections of the display sub-pixels SPix are made on the side of the surface 54.

[0038] The display circuit 52 has two opposite, preferably parallel, surfaces 58 and 59. The surface 59 of the display circuit 52 forms the emission surface of the display sub-pixel SPix. The surface 58 of the display circuit 52 is bonded to a surface 55 of the control circuit 50. The display circuit 52 comprises at least one light emitting diode LED, preferably at least three light emitting diodes LED. A large proportion, preferably all, of the emitted light emitted by the light emitting diodes LED of the display sub-pixel is emitted at the surface 59 of the display circuit 52. The display circuit 52 preferably comprises only the light emitting diodes LED and the conductive elements of these light emitting diodes LED, and the control circuit 50 comprises all the electronic components necessary for controlling the light emitting diodes LED of the display circuit 52. As a variant, the display circuit 52 may further comprise other electronic components in addition to the light emitting diodes LED. The light emitting diodes LED may be two-dimensional light emitting diodes, also called planar light emitting diodes, with a stack of planar layers, or three-dimensional light emitting diodes, each comprising a three-dimensional semiconductor element covered with an active area that emits a large proportion of the emitted light of the light emitting diode.

[0039] Each display subpixel SPix may be generally cylindrical in cross section, which may have various shapes, for example oval, circular or polygonal, in particular triangular, rectangular, square or hexagonal. The maximum lateral dimension of the display subpixel SPix in plan view may be in the range of 4 μm to 2 mm, preferably 20 μm to 200 μm. The thickness of the display subpixel SPix, i.e. the distance between the surface 54 and the surface 59, may be in the range of 0.5 μm to 1 mm, preferably 10 μm to 150 μm. The thickness of the control circuit 50 may be in the range of 0.5 μm to 750 μm. The thickness of the display circuit 52 may be in the range of 2 μm to 100 μm. The distance between two adjacent display subpixels SPix in plan view may be in the range of 10 μm to 10 mm.

[0040] The support 26 corresponds to a structure on which the display subpixels SPix are placed. The support 26 may be monolithic or may have a multi-layer structure. In the embodiment shown in FIG. 2, the support 26 has an integral base 27. At least a portion of the support 26 is transparent to the emitted light of the light-emitting diodes LED of the display subpixels SPix and the emitted light by the photoluminescent blocks 34, 36. The portion of the support 26 extending from the emission surface 28 to the bottom 33 of the hole 32 is preferably transparent to the emitted light of the light-emitting diodes LED of the display subpixels SPix and the emitted light by the photoluminescent blocks 34, 36. In this embodiment, the base 27 is transparent to the emitted light of the light-emitting diodes LED of the display subpixels SPix and the emitted light by the photoluminescent blocks 34, 36. The base 27 is formed, for example, of glass or a polymer, such as polyethylene naphthalene (PEN), polyethylene terephthalate (PET), polyimide (PI) or polyether ether ketone (PEEK). The maximum thickness of the support 26, i.e. the distance between the surface 28 and the surface 30, may be in the range of 1 μm to 1 cm, preferably 40 μm to 5 mm.

[0041] The maximum depth of each hole 32 may be in the range of 1 μm to 200 μm, preferably 4 μm to 50 μm. The maximum lateral dimension of each hole 32 in plan view may be in the range of 40 μm to 200 μm, preferably in the range of 100 μm to 110 μm. Each hole 32 may have a cross-section at the level of the upper surface 30, which may have various shapes, for example oval, circular or polygonal, in particular triangular, rectangular, square or hexagonal shapes. Each hole 32 may have a cross-section at the level of the upper surface 30, which has an area larger than the area of ​​the cross-section of the display subpixel SPix. Each hole 32 is arranged opposite one of the display subpixels SPix. This means that the projection of the cross-section of the display subpixel SPix onto the surface 30 along a direction perpendicular to the surface 30 is mainly, preferably more than 75%, more preferably completely contained in the cross-section of the hole 32 associated with it at the level of the upper surface 30.

[0042] Each photoluminescent block 34, 36 may comprise a luminophore, which, when excited by the light emitted by the light emitting diode LED of the display sub-pixel SPix covering the photoluminescent block 34, 36, is capable of emitting light at a wavelength different from the wavelength of the light emitted by the associated light emitting diode LED. According to an embodiment, the display screen 25 comprises at least two types of photoluminescent blocks 34, 36. Each photoluminescent block 34 of a first type is capable of converting the light emitted by the light emitting diode of the associated display sub-pixel SPix into a first emitted light of a first wavelength, and each photoluminescent block 36 of a second type is capable of converting the light emitted by the light emitting diode of the associated display sub-pixel SPix into a second emitted light of a second wavelength. According to an embodiment, the display screen 25 comprises at least three types of photoluminescent blocks, each photoluminescent block of a third type being adapted to convert the light emitted by the light emitting diode of the associated display sub-pixel SPix into a third emitted light of a third wavelength. The first, second and third wavelengths may be different.

[0043] According to an embodiment, all the light emitting diodes LED are adapted to emit blue light, i.e. radiation light with a wavelength in the range of 430 nm to 480 nm. According to an embodiment, the first wavelength corresponds to green light and lies in the range of 510 nm to 570 nm. According to an embodiment, the second wavelength corresponds to red light and lies in the range of 600 nm to 720 nm.

[0044] According to another embodiment, the light emitting diodes LED are all adapted to emit radiation in the ultraviolet range, typically radiation having a wavelength of less than 400 nm. According to an embodiment, the first wavelength corresponds to blue light and lies in the range of 430 nm to 480 nm. According to an embodiment, the second wavelength corresponds to green light and lies in the range of 510 nm to 570 nm. According to an embodiment, the third wavelength corresponds to red light and lies in the range of 600 nm to 720 nm.

[0045] According to an embodiment, each photoluminescent block 34, 36 comprises a matrix in which nanometer-sized, single-crystalline particles of semiconductor material, hereinafter also referred to as semiconductor nanocrystals or nanoluminophore particles, are dispersed. int The internal quantum efficiency, QY, of semiconductor nanocrystals is equal to the ratio of the number of emitted photons to the number of photons absorbed by the photoluminescent material. int is higher than 5%, preferably higher than 10%, and more preferably higher than 20%.

[0046] According to an embodiment, the average size of the semiconductor nanocrystals is in the range of 0.5 nm to 1,000 nm, preferably 0.5 nm to 500 nm, more preferably 1 nm to 100 nm, in particular 2 nm to 30 nm. At sizes smaller than 50 nm, the light conversion properties of the semiconductor nanocrystals are essentially determined by the quantum confinement phenomenon. Therefore, the semiconductor nanocrystals correspond to quantum dots.

[0047] According to an embodiment, the semiconductor material of the semiconductor crystal is selected from the group comprising cadmium selenide (CdSe), indium phosphide (InP), cadmium sulfide (CdS), zinc sulfide (ZnS), zinc selenide (ZnSe), cadmium telluride (CdTe), zinc telluride (ZnTe), cadmium oxide (CdO), cadmium zinc oxide (ZnCdO), cadmium zinc sulfide (CdZnS), cadmium zinc selenide (CdZnSe), silver indium sulfide (AgInS2), perovskites of the PbScX3 type (where X is a halogen atom, in particular iodine (I), bromine (Br) or chlorine (Cl)) and mixtures of at least two of these compounds. According to an embodiment, the semiconductor material of the semiconductor nanocrystals is selected from the materials described in the publication by Le Blevenec et al., Physica Status Solidi (RRL) - Rapid Research Letters Volume 8, No. 4, p. 349-352, April 2014.

[0048] According to an embodiment, the size of the semiconductor nanocrystals is selected according to the desired wavelength of the radiation emitted by the semiconductor nanocrystals. As an example, CdSe nanocrystals with an average size of about 3.6 nm can convert blue light to red light, and CdSe nanocrystals with an average size of about 1.3 nm can convert blue light to green light. According to another embodiment, the composition of the semiconductor nanocrystals is selected according to the desired wavelength of the radiation emitted by the semiconductor nanocrystals.

[0049] The matrix is ​​at least partially transparent, preferably more than 80%, of the radiation emitted by the photoluminescent particles and / or the light-emitting diodes LED. The matrix is ​​formed, for example, of silica. The matrix is ​​formed, for example, of any at least partially transparent polymer, in particular silicone, an acrylic resin of the polymethylmethacrylate (PMMA) type, or polylactic acid (PLA). The matrix may in particular be formed of an at least partially transparent polymer used with three-dimensional printers. The matrix may correspond to a photosensitive or non-photosensitive glass (SOG, spin-on glass) deposited by centrifugation. According to an embodiment, the matrix contains 2 to 90% by weight, preferably 10 to 60% by weight, of nanocrystals, for example about 30% by weight. The thickness of the photoluminescent blocks 34, 36, which is equal to the depth of the holes 32, depends on the concentration of the nanocrystals and on the type of nanocrystals used.

[0050] The opaque layer 38 does not transmit the radiation emitted by the light emitting diode LED. The opaque layer 38 is preferably black. The opaque layer 38 may be made of a resin. The thickness of the opaque layer 38 may be within a range of 1 μm to 10 μm.

[0051] The adhesive layer 40 is transparent to the radiation emitted by the light emitting diode LED. The adhesive layer 40 may be an optically transparent adhesive (OCA), in particular a liquid optically transparent adhesive (LOCA). The refractive index of the adhesive layer 40 is preferably less than 2. The maximum thickness of the adhesive layer 40 may be in the range of 10 nm to 5 μm. According to an embodiment, the adhesive layer 40 is electrically insulating. Each display sub-pixel SPix does not have an electrical connection on the side of the adhesive layer 40.

[0052] The filling layer 42 surrounds each display subpixel SPix. The filling layer 42 has two oppositely located surfaces 60 and 61, which are preferably flat and parallel. The surface 60 is in mechanical contact with the adhesive layer 40. The surface 61 of the filling layer 42 forms the back surface 62 of the display screen 25 together with the surface 54 of each display subpixel SPix. The back surface 62 is preferably flat, since the surface 61 of the filling layer 42 and the surface 54 of the display subpixel SPix are flat and coplanar. The filling layer 42 is preferably made of an insulating material. The filling layer 42 reflects the radiation emitted by the light-emitting diodes LED. The filling layer 42 is preferably white. By way of example, the filling layer 42 is made of a PMMA-type acrylic resin filled with particles, in particular titanium oxide (TiO2) particles. The thickness of the filling layer 42 may be substantially equal to the thickness of the display subpixel SPix reduced by the maximum thickness of the adhesive layer 40.

[0053] The conductive tracks 44 extend over the surfaces 54 of some of the display sub-pixels SPix and over a surface 61 of the filling layer 42. The conductive tracks 44 are made of, for example, copper (Cu). The thickness of each conductive track 44 may be in the range of 200 nm to 100 μm.

[0054] Figure 3 shows a schematic partial cross-sectional view of an embodiment of a display screen 65. The display screen 65 comprises all the elements of the display screen 25 shown in figure 2, and further comprises a layer 66 corresponding to a colour filter covering at least the bottom 33 of at least some of the holes 32. The layer 66 makes it possible to more finely adapt the spectrum of the radiation emitted towards the emission surface 28 of the display screen 65. In particular, the layer 66 makes it possible to block residual radiation of blue colour. The layer 66 corresponds for example to a yellow colour filter.

[0055] FIG. 4 is a partial cross-sectional schematic diagram showing an embodiment of a display screen 70. The display screen 70 includes all the elements of the display screen 65 shown in FIG. 3, except that the support 26 includes a layer 72 covering the base 27, and the holes 32 are formed in the layer 72. Furthermore, the holes 32 are disposed opposite each display subpixel SPix. The layer 72 defines the surface 30 of the support 26 and has a lower surface 73 opposite the surface 30, which is in mechanical contact with the base 27. The layer 72 preferably reflects the radiation emitted by the light-emitting diode LED. The layer 72 is preferably white. The thickness of the layer 72 is substantially equal to the maximum depth of the holes 32, so that the holes 32 traverse the layer 72 completely, and the bottoms 33 of the holes 32 correspond to a portion of the base 27. The layer 72 may be formed of a resist. In this embodiment, the opaque layer 38 rests on the base 27 and is in mechanical contact with the base 27. Alternatively, the opaque layer 38 may be placed on the layer 72. The holes 32 are filled with photoluminescent blocks 34, 36 or blocks 74 of scattering material. The scattering properties of the scattering material may be characterized by a bidirectional scattering distribution function (BSDF), which includes in particular a bidirectional reflectance distribution function (BRDF) and a bidirectional transmittance distribution function (BTDF). The bidirectional scattering distribution function may be determined by a dedicated measurement tool. According to an embodiment, the scattering material of the block 74 comprises a matrix in which reflective particles are dispersed. The matrix may be made of a material that is transparent to the radiation emitted by the light emitting diode LED. The matrix may comprise silicon oxide (SiO2), a silicone polymer, an epoxide polymer, an acrylic polymer or a polycarbonate. The particles are for example titanium oxide (TiO2) particles.

[0056] FIG. 5 is a partial cross-sectional schematic diagram showing an embodiment of a display screen 75. The display screen 75 comprises all the elements of the display screen 70 shown in FIG. 4, except that the support 26 has an additional layer 76 arranged between the base 27 and the layer 72 containing the holes 32. The additional layer 76 is an adhesive layer that allows the bonding of the additional layer 72 containing the holes 32 to the base 27. The additional layer 76 is transparent to the emitted light of the light emitting diodes LED of the display sub-pixels SPix and to the emitted light emitted by the photoluminescent blocks 34, 36. The additional layer 76 may be formed of an optically clear adhesive (OCA), in particular a liquid optically clear adhesive (LOCA). The refractive index of the additional layer 76 is preferably less than 2. The thickness of the additional layer 76 may be in the range of 10 nm to 10 μm.

[0057] 6 is a partial cross-sectional schematic diagram showing an embodiment of a display screen 80. The display screen 80 includes all the elements of the display screen 25 shown in FIG. 2, except that the holes 32 are arranged opposite each display subpixel SPix, the display screen 80 further includes a reflective coating 82 covering the sidewalls 35 of the holes 32, a color filter 84 covering the bottom 33 of the first holes 32, a layer 86 transparent to the emitted light of the photoluminescent blocks 34, 36 on the sidewalls 35 and bottom 33 of the first holes 32, and only a transparent layer 86 on the sidewalls 35 and bottom 33 of the second holes 32. The transparent layer 86 can increase the conversion efficiency of the photoluminescent blocks 34, 36. As a variant, the transparent layer 86 may be provided only on the bottom 33 of the first holes 32 and / or the second holes 32. The color filter layer 84 corresponds to a yellow color filter, for example. The first hole 32 is filled with a photoluminescent block 34, 36 and the second hole 32 is filled with a block 74 of scattering material as described above with respect to the display screen 70. The reflective coating 82 may be a metal layer, for example an aluminum or silver layer, or may comprise a stack of dielectric layers forming a Bragg mirror. The thickness of the reflective coating 82 may be in the range of 50 nm to 1.5 μm. The thickness of the color filter layer 84 may be in the range of 250 nm to 3 μm. The refractive index of the transparent layer 86 is preferably less than 1.5. The transparent layer 86 may be formed of a polymer. The thickness of the transparent layer 86 may be in the range of 250 nm to 2 μm.

[0058] Figure 7 is a schematic partial cross-sectional view illustrating an embodiment of a display screen 90. Display screen 90 includes all of the elements of display screen 75 shown in Figure 5, and further includes reflective coating 82, color filter layer 84, and transparent layer 86 as previously described with respect to display screen 80.

[0059] Fig. 8 is a schematic partial cross-sectional view showing an embodiment of a display screen 95. The display screen 95 comprises all the elements of the display screen 25 shown in Fig. 2, except that, at least for certain display pixels, the sub-pixels SPix of the display pixel are integrated into one display circuit 52 associated with one control circuit 50. According to an embodiment, the display circuit 52 comprises isolation elements 96 separating the light-emitting diodes LED of the display sub-pixels SPix. The isolation elements 96 do not pass the emitted light emitted by the light-emitting diodes LED. These isolation elements 96 therefore make it possible to prevent the light emitted by the light-emitting diodes LED of the display sub-pixels SPix from reaching the openings facing the photoluminescent blocks 34, 36 of other display sub-pixels SPix or display sub-pixels SPix with no associated photoluminescent blocks, thereby modifying the spectrum and luminescent intensity of the display sub-pixels SPix and adversely affecting the clarity of the displayed image.

[0060] FIG. 9 is a schematic partial cross-sectional view showing a more detailed embodiment of a display sub-pixel SPix.

[0061] According to the embodiment, the control circuit 50 is shown in FIG. a semiconductor substrate 100, for example monocrystalline silicon, an insulating layer 102 defining a surface 54, and conductive pads 56 exposed on the underlying surface 54; a MOS transistor 104 formed in and on top of a semiconductor substrate 100; a stack 105 of insulating layers, for example made of silicon oxide and / or silicon nitride, covering the substrate 100, with conductive tracks 106 of several metallization levels formed between the insulating layers of the stack 105, in particular having pads 108 exposed on the surface 55 of the control circuit 50, the conductive tracks 106 of a first metallization level being made of polysilicon and in particular forming the gates of the MOS transistors 104, the conductive tracks 106 of the other metallization levels being metallic tracks, for example made of aluminium, silver, copper or zinc, - conductive, laterally isolated vias 107, also called TSVs (Through Silicon Vias), connecting the pads 56 across the substrate 100 to pads 110 of the first metallization level of the stack 105; It has.

[0062] According to the embodiment, the display circuit 52 includes, from top to bottom in FIG. a support 111 forming a surface 58 of the display circuit 52 in contact with the surface 55 of the control circuit 50, the support 111 having conductive pads 112 exposed on the surface 58 and in contact with the pads 108, and a multilayer insulating structure 113, for example made of silicon oxide and silicon nitride, extending between the pads 112, covering them and having openings 114 exposing parts of the pads 112; - a microwire or nanowire 115 (hereinafter referred to as wire) (two wires are shown) passing through one of the openings 114 and each in contact with one of the pads 112; an insulating layer 116 extending over the sides of the lower portion of each wire 115 and over the insulating layer 113 between the wires 115; a shell 118 comprising a stack of semiconductor layers covering the upper part of each wire 115 and extending onto the insulating layer 116 between the wires 115, the shell 118 comprising in particular an active layer, which is the layer from which the majority of the radiation emitted by the light emitting diode is emitted, and a confinement means, for example a multiple quantum well; a reflective conductive layer 120 extending over the shell 118 between the wires 115; a transparent conductive layer 122 covering the shell 118 for each wire 115 to form electrodes which further extend on the conductive layer 120 between the wires 115; - a transparent or scattering block 124 covering the light emitting diode LED; - an encapsulation layer 126 covering the entire structure; It has.

[0063] Each wire 115 may have an elongated semiconducting structure. Each wire 115 may be generally cylindrical in cross section, which may have various shapes, for example oval, circular or polygonal, in particular triangular, rectangular, square or hexagonal shapes. Each wire 115 has, for example, an average diameter corresponding to the diameter of a disk having the same area as the cross-sectional area of ​​the wire 115, for example in the range of 5 nm to 5 μm, preferably in the range of 100 nm to 2 μm, more preferably in the range of 200 nm to 1.5 μm, and a height which is equal to or greater than the average diameter, preferably equal to or greater than three times the average diameter, even more preferably equal to or greater than five times the average diameter, in particular greater than 500 nm, preferably in the range of 1 μm to 50 μm. The wire 115 comprises at least one semiconducting material. The semiconducting material may be silicon carbide, a III-V compound, for example GaN, AlN, InN, InGaN, AlGaN or AlInGaN, a II-VI compound, or a combination of at least two of these compounds.

[0064] The conductive layer 122 is capable of passing electromagnetic radiation emitted by the light emitting diode when the active layer of the shell 118 is biased. The material forming the conductive layer 122 may be a transparent conductive material such as graphene or a transparent conductive oxide (TCO), in particular indium tin oxide (ITO), zinc oxide doped or undoped with aluminum, gallium or boron, or silver nanowires. By way of example, the thickness of the conductive layer 122 is in the range of 20 nm to 500 nm, preferably in the range of 20 nm to 100 nm.

[0065] The conductive layer 120, the conductive tracks 106 and the conductive pads 56, 108, 112 may be made of a metal, for example aluminum, silver, platinum, nickel, copper, gold or ruthenium, or an alloy containing at least two of these compounds, in particular a PdAgNiAu alloy or a PtAgNiAu alloy. The conductive layer 120 may have a thickness in the range of 100 nm to 3 μm. The conductive pads 56, 108, 112 may have a thickness in the range of 0.5 μm to 2 μm.

[0066] The insulating layers 105, 111, and 116 are made of silicon oxide (SiO2), silicon nitride (Si x N y , where x is approximately 3 and y is approximately 4, e.g., Si3N4), (particularly of the general formula SiO x N y The first and second electrodes are each formed of a material selected from the group including silicon oxynitride (eg, Si2ON2), hafnium oxide (HfO2), titanium oxide (TiO2), or aluminum oxide (Al2O3).

[0067] 10 to 16 are schematic, partial cross-sectional views showing structures obtained in successive steps of a mode of implementation of the display screen 25 shown in FIG.

[0068] 10 shows the resulting structure after the step of forming an opaque layer 38 on surface 30 of support 26. In this step, the material that will form opaque layer 38 may be deposited over surface 30 and then etched to form openings 39 at the intended locations of the display subpixels.

[0069] 11 shows the structure obtained after a step of forming holes 32 in the support 26. The holes 32 may be formed by etching, in particular by reactive ion etching (RIE).

[0070] 12 shows the structure obtained after a step of forming the photoluminescent blocks 34, 36 in the holes 32. Depending on the material in question, the method of forming the photoluminescent blocks 34, 36 may correspond, for example, to so-called additive methods by direct printing of the material forming the photoluminescent blocks 34, 36 at the desired locations, for example by inkjet printing, gravure printing, silkscreen printing, flexographic printing, spray coating or drop casting. Depending on the material in question, the method of forming the photoluminescent blocks 34, 36 may correspond to so-called subtractive processes, in which the material forming the photoluminescent blocks 34, 36 is deposited over the entire structure and then the unused parts are removed, for example by photolithography or laser ablation. Methods such as spin coating, spray coating, heliography, slot-die coating, blade coating, flexographic printing or silkscreening may in particular be used.

[0071] Figure 13 shows the resulting structure after a step of depositing an adhesive layer 40 on the surface of the structure shown in Figure 12, in particular on the opaque layer 38, the photoluminescent blocks 34, 36, and the exposed portions of the support 26 in the openings 39 in the opaque layer 38. In this step, the adhesive layer 40 may be in liquid form and may have some viscosity. Deposition of the adhesive layer 40 may be by one of the methods previously described with respect to the formation of the photoluminescent blocks 34, 36.

[0072] Fig. 14 shows the structure obtained after a step of arranging the display subpixels SPix on the support 26, each of which is arranged opposite a hole 32 or opposite an exposed part of the support 26 in an opening 39 of the opaque layer 38. According to an embodiment, this step comprises a step of immersing each of the display subpixels SPix in an adhesive layer 40 on the side of the display circuit 32 and a step of adhesive solidification, which may include a heating step and / or a step of exposure to ultraviolet or infrared light. A film of the adhesive layer 40 may remain between the display subpixels SPix and the support 26 or the photoluminescent blocks 34, 36 after arranging the display subpixels SPix. The adhesive layer 40 is therefore transparent to the radiation emitted by the light-emitting diodes LED. The refractive index of the adhesive layer 40, preferably less than 2, is adapted to the extraction and propagation of the radiation emitted by the light-emitting diodes. A method of manufacturing display subpixels includes forming a number of display circuits on a wafer referred to as an optoelectronic wafer, forming a number of control circuits on a wafer referred to as a logic wafer, bonding the optoelectronic wafer to the logic wafer, and sawing the stack of optoelectronic and logic wafers to separate the display pixels.

[0073] 15 shows the resulting structure after the step of forming infill layer 42. Deposition of infill layer 42 may be performed by one of the methods previously described for forming photoluminescent blocks 34, 36. A planarization step may be performed to form surface 61.

[0074] 16 shows the structure obtained after the step of forming the conductive tracks 44. The material forming the conductive tracks is deposited, for example by evaporation or cathodic sputtering, over the fill layer 42, and the surfaces 54 of the display sub-pixels SPix and the conductive tracks 44 are defined by etching.

[0075] In the embodiment described above, each display pixel / display subpixel comprises a control circuit 50 integrating the control electronics of the light emitting diode LED of the display pixel / display subpixel. Thus, in contrast to the conventional method of depositing the display pixel / display subpixel on a panel including the control electronics and then forming the photoluminescent blocks on the display pixel / display subpixel, the conductive tracks 44 can be formed directly on the surface 61, in particular after a possible planarization step, and thus the display subpixels can be directly transferred onto the support 26 including the photoluminescent blocks 34, 36 before forming the conductive tracks 44. If each pixel / display subpixel did not comprise a control circuit 50, it would be difficult or impossible to deposit the pixels / display subpixels onto the support 26 including the photoluminescent blocks 34, 36. In fact, the electronic components would have to be formed or deposited on structures already transferred, which may not be compatible with the precision constraints for the formation / deposition of the electronic components.

[0076] The embodiment of the method of manufacturing the display screen 65 shown in Figure 3 includes all of the steps described above in relation to Figures 10-12, and further includes the step of forming a color filter layer 66 in the holes 32 prior to the step of forming the photoluminescent blocks 34, 36 described above in relation to Figure 12.

[0077] The embodiment of the method of manufacturing display screen 70 shown in Figure 4 includes all of the steps previously described in relation to Figures 10-16, except that it further includes the step of forming layer 72 on base 27 prior to the step of forming holes 32, and forming holes 32 in layer 72, for example by etching layer 72. Advantageously, the material forming layer 72 may be selected such that the step of etching layer 72 is easier to perform than the step of etching base 27.

[0078] The embodiment of the method of manufacturing display screen 75 shown in FIG. 5 includes all of the steps previously described for manufacturing display screen 70, and further includes the step of forming layer 76 prior to the step of forming layer 72.

[0079] 17-21 are schematic partial cross-sectional views showing successively processed structures of the embodiment of the display screen 80 shown in FIG.

[0080] FIG. 17 shows the resulting structure after the steps of forming an opaque layer 38 on the support 26 and forming holes 32, for example as described above in connection with FIGS.

[0081] 18 shows the structure obtained after a step of forming a reflective coating 82 on the sidewalls 35 of the holes 32. The material forming the reflective coating 82 is deposited, for example, by evaporation or cathode sputtering over the entire support 26, and the reflective coating 82 is defined by etching.

[0082] FIG. 19 shows the resulting structure after the step of forming in each hole 32 configured to receive a photoluminescent block 34 or a photoluminescent block 36 a color filter layer 84 covering the bottom 33 of the hole.

[0083] FIG. 20 shows the resulting structure after the steps of forming a transparent layer 86 covering the color filter layer 84 and the reflective coating 82 in each hole 32 configured to receive a photoluminescent block 34 or a photoluminescent block 36, and forming a transparent layer 86 directly covering the reflective coating 82 and the bottom 33 of the hole 32 in each hole 32 configured to receive a scattering block 74.

[0084] FIG. 21 shows the resulting structure after the steps of forming the photoluminescent blocks 34, 36 and scattering blocks 74 in the holes 32, for example as described above in connection with FIG.

[0085] A method for manufacturing the screen 80 shown in FIG. 6 may include the steps described above in relation to FIGS.

[0086] Various embodiments and variants have been described. Those skilled in the art will understand that certain features of these various embodiments and variants may be combined, and other variants will occur to those skilled in the art. Furthermore, while in the above-described embodiment the display sub-pixel SPix has two chips bonded together, it should be clear that a group of pixels may have one chip, and a general circuit for controlling the light-emitting diode may be formed to be integrated with the light-emitting diode. Finally, the actual implementation of the described embodiments and variants is within the skill of a person skilled in the art based on the functional representations set forth above.

[0087] This patent application claims priority from French Patent Application No. 21 / 14167, which is incorporated herein by reference.

Claims

1. A display screen (25; 65; 70; 75; 80; 90), a support (26) having opposed first and second surfaces (30 and 28), the first surface (30) having holes (32) therein; A glittering block (34, 36) provided in at least a part of the hole; an adhesive layer (40) covering the first surface; a display subpixel (SPix) bonded to the support by the adhesive layer, the display subpixel having a third surface (59) on the support side, a fourth surface (54) located opposite the third surface, and a conductive pad (56) exposed on the fourth surface; a filler layer (42) covering the first surface between the display subpixels; a conductive track (44) extending over the fill layer and over a fourth surface of the display subpixel and in electrical and mechanical contact with the conductive pad; A display screen comprising:

2. 2. A display screen as claimed in claim 1, wherein each display sub-pixel (SPix) comprises a light emitting diode (LED) closer to the third surface (59) than to the fourth surface (54).

3. 3. The display screen of claim 2, wherein each display subpixel (SPix) comprises a stack of a first electronic circuit (52) having the light emitting diode (LED) and a second electronic circuit (50) having electronic components configured to control the light emitting diode.

4. 4. A display screen according to claim 1, wherein the filler layer (42) reflects radiant light emitted by the display sub-pixels (SPix) and the photoluminescent blocks (34, 36).

5. 5. The display screen of claim 1, further comprising a first layer (38) that is opaque to radiation emitted by the display sub-pixels (SPix) and the photoluminescent blocks (34, 36) facing the first surface (30) and has openings (39) facing the third surface of each display sub-pixel (SPix).

6. A display screen as claimed in any one of the preceding claims, comprising in at least another portion of the aperture (32) a block (74) of material which scatters the radiated light emitted by the display sub-pixel.

7. 7. A display screen as claimed in any one of claims 1 to 6, wherein the support (26) has a base (27) which is transparent to radiation emitted by the display sub-pixels (SPix) and by the photoluminescent blocks (34, 36) which are covered with a second layer (72) comprising the holes (32).

8. 8. The display screen of claim 7, wherein the second layer (72) reflects radiation emitted by the display sub-pixels (SPix) and the photoluminescent blocks (34, 36).

9. 9. A display screen as claimed in claim 7 or 8, further comprising a third layer (76) between the base (27) and the second layer (72) that is transparent to the emitted light emitted by the display sub-pixels (SPix) and the photoluminescent blocks (34, 36) and has a refractive index of less than 2.

10. 10. A display screen as claimed in any one of claims 1 to 9, comprising a covering (82) which reflects the emitted light emitted by the display sub-pixels (SPix) and the photoluminescent blocks (34, 36) and covers the side walls (35) of each hole (32).

11. 11. A display screen as claimed in any one of claims 1 to 10, further comprising a fourth layer (86) which is transparent to the radiation emitted by the display sub-pixels (SPix) and the photoluminescent blocks (34, 36), has a refractive index of less than 1.5 and covers the bottom (33) of each hole (32).

12. 12. The display screen of claim 1, wherein the hole (32) containing the photoluminescent block (34, 36) is provided with a color filter layer (84) disposed between the photoluminescent block (34, 36) and a bottom of the hole (32).

13. The display screen of any one of claims 1 to 12, wherein the photoluminescent blocks (34, 36) comprise quantum dots.

14. A method for manufacturing a display screen (25; 65; 70; 75; 80; 90) according to any one of claims 1 to 13, comprising the steps of: forming the holes (32) in a first surface (30) of the support (26); forming the photoluminescent block (34, 36) in at least a portion of the hole; depositing an adhesion layer (40) overlying the first surface; disposing the display sub-pixels (SPix) on the third surface (59) side and bonding them to the support by the adhesive layer; forming the fill layer (42) covering the first surface between the display subpixels; and forming a conductive track (44) extending over the filler layer and over a fourth surface of the display subpixel; The method comprising:

15. forming a wafer including a plurality of display sub-pixels (SPix); cutting the wafer to separate the display sub-pixels (SPix); 15. The method of claim 14, comprising:

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