Classifications

• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
  • H01L27/00—Devices consisting of a plurality of semiconductor or other solid-state components formed in or on a common substrate
  • H01L27/15—Devices consisting of a plurality of semiconductor or other solid-state components formed in or on a common substrate including semiconductor components having potential barriers, specially adapted for light emission
  • H01L27/153—Devices consisting of a plurality of semiconductor or other solid-state components formed in or on a common substrate including semiconductor components having potential barriers, specially adapted for light emission in a repetitive configuration, e.g. LED bars
  • H01L27/156—Devices consisting of a plurality of semiconductor or other solid-state components formed in or on a common substrate including semiconductor components having potential barriers, specially adapted for light emission in a repetitive configuration, e.g. LED bars two-dimensional arrays
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
  • H01L33/00—Semiconductor devices having potential barriers specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
  • H01L33/02—Semiconductor devices having potential barriers specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof characterised by the semiconductor bodies
  • H01L33/10—Semiconductor devices having potential barriers specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof characterised by the semiconductor bodies with a light reflecting structure, e.g. semiconductor Bragg reflector
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
  • H01L33/00—Semiconductor devices having potential barriers specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
  • H01L33/02—Semiconductor devices having potential barriers specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof characterised by the semiconductor bodies
  • H01L33/08—Semiconductor devices having potential barriers specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof characterised by the semiconductor bodies with a plurality of light emitting regions, e.g. laterally discontinuous light emitting layer or photoluminescent region integrated within the semiconductor body

Definitions

• the present invention relates to a method of manufacturing an optoelectronic device comprising a plurality of light-emitting diodes.
• the invention also relates to an optoelectronic device as such.
• the invention finds an application in particular in display screens or image projection systems.
• optoelectronic device is meant here a device suitable for converting an electrical signal into electromagnetic radiation to be emitted, in particular light.
• optoelectronic devices comprising light-emitting diodes, also known by the acronym LED for “light-emitting diode” according to the English terminology devoted, formed on a substrate.
• each light-emitting diode comprises a semiconductor portion doped according to a first type of doping to play the role of N-doped portion, another portion comprising an active area exploiting or not quantum wells, and a third semiconductor portion doped according to a second type of doping to play the role of P-doped portion
• Each light-emitting diode can be formed on the basis of three-dimensional or two-dimensional semiconductor elements, themselves at least partially obtained by growth by epitaxy by means of techniques such as the “Molecular Beam Epitaxy” MBE, or the “Molecular Organic Vapor Phase” MOVPE.
• Epitaxy accordinging to English terms or chemical vapor deposition of organometallic (MOCVD) or by chemical vapor deposition assisted by plasma or by (PECVD) or by PVD (physical vapor deposition).
• Light-emitting diodes are typically formed from semiconductor materials comprising, for example, elements from column III and column V of the periodic table, such as a III-V compound, including gallium nitride (GaN), nitride d indium and gallium (InGaN) or aluminum and gallium nitride (AIGaN).
• III-V compound including gallium nitride (GaN), nitride d indium and gallium (InGaN) or aluminum and gallium nitride (AIGaN).
• optoelectronic devices comprising a matrix of light-emitting diodes having a certain emission surface through which the light radiation emitted by the light-emitting diodes is transmitted.
• Such optoelectronic devices can in particular be used in the constitution of display screens or image projection systems, where the matrix of light-emitting diodes in fact defines a matrix of light pixels where each pixel comprises at least one sub-pixel itself containing at least one light-emitting diode.
• a sub-pixel can for example contain from 1 to 100,000 light-emitting diodes.
• One of the difficulties is to achieve that the light radiation emitted by the light-emitting diodes of a sub-pixel does not mix with the light radiation emitted by the light-emitting diodes of an adjacent sub-pixel in order to improve the contrasts.
• one problem is to succeed in avoiding excitations of crosstalk-like colors between the sub-pixels, a phenomenon also known as “cross-talk” in the technical field concerned.
• this problem proves increasingly difficult to solve given the increasing miniaturization of light emitting diodes.
• One known solution consists in forming light confinement walls capable of blocking the transmission of light radiation emitted by at least one given light-emitting diode to at least one adjacent light-emitting diode.
• a known technique for forming such light confinement walls consists in carrying out an additional step, after the formation of the light-emitting diodes, by depositing a layer of resin on the light-emitting diodes, the resin being photolithographed while respecting a pattern guaranteeing the presence of trenches intended to then be filled with a material, for example by a growth technique, capable of blocking the light radiation or even of ensuring a reflection thereof.
• This technique has the disadvantage that it is difficult to comply with precise alignment between the confinement walls and the light-emitting diodes. This problem is all the more present in view of the increasing miniaturization of light-emitting diodes in order to ultimately obtain a high resolution.
• Another difficulty is to be able to obtain light-emitting diodes in the same sub-pixel which are homogeneous with one another in terms of height and width when said light-emitting diodes are arranged on the edges of rows.
• the supply of material, around the edge light emitting diodes is surplus compared to the situation of light emitting diodes completely surrounded by other light emitting diodes.
• the state of the art shows that the average diameter of the light-emitting diode elements located on the periphery is on average greater than 20% than the average diameter of the light-emitting diode elements in the area. It is the same for heights.
• Another difficulty is to be able to manufacture light-emitting diodes whose wavelength emitted by each diode does not vary by more than 2% over an entire sub-pixel.
• the present invention aims to respond to all or part of the problems presented above.
• one goal is to provide a solution that meets at least one of the following objectives:
• This object can be achieved by implementing a method of manufacturing an optoelectronic device comprising a step a) of forming a substrate having a support face.
• the method also includes a step b) of forming a first series of first zones on the support face suitable for the formation of all or part of light-emitting diodes, said light-emitting diodes comprising a first portion doped according to a first type of doping, a second portion forming an active area and a third portion doped according to a second type of doping.
• the method further comprises a step c) of forming a second series of second zones on the support face, adapted to the formation of at least one element of light confinement walls capable of forming a light confinement wall, the second zones being distinct from the first zones, the second zones defining between them sub-pixel zones.
• An additional step d) of the method consists of the formation, from the first zones, of all or part of light-emitting diodes.
• the method includes a step e) of forming, by the same technique as in step d), from the second zones, all or part of elements of light confinement walls, concomitantly with all or part of the diodes. electroluminescent formed in step d).
• At least two of the second zones suitable for the formation of luminous confinement wall elements are arranged to allow obtaining of luminous confinement walls by coalescence of luminous confinement wall elements.
• All or part of the second zones suitable for the formation of luminous confinement wall elements are arranged to allow the formation of luminous confinement wall elements in one piece.
• the light confinement walls contain at least partially portions of electrically insulating material.
• the light-emitting diodes have an elongated wire shape along a longitudinal axis, extending in a transverse direction of the optoelectronic device oriented transversely to the support face.
• the first, second and third portions of the light emitting diodes are stacked parallel to the support face. All or part of the light-emitting diodes of the same sub-pixel zone are positioned at a distance DI with respect to the elements of light confinement walls, the distance satisfying at least one of the following conditions:
• the distance DI is between half and 100 times the pitch separating all or part of two adjacent light-emitting diodes
• the distance DI is between once and 500 times the diameter of all or part of the light-emitting diodes
• the distance DI is less than or equal to twice the diffusion length of the atomic species making up all or part of the light-emitting diodes.
• the elements of light confinement walls formed in step e) have an ability to capture all or part of the material used during step d) for the formation of the first, second and third portions of light-emitting diodes.
• the elements of light confinement walls are formed, in whole or in part, substantially from the same materials as the first, second and third portions of light-emitting diodes.
• All or part of the light confinement walls is produced concomitantly with the formation of the first portion of the light-emitting diodes, and concomitantly with the formation of the second portion of the light-emitting diodes.
• the light confinement walls comprise a first element doped according to a first type of doping formed concomitantly with the first doped portion according to a first type of doping of light-emitting diodes, the light confinement walls further comprising a second element, capable of constituting a zone active, obtained concomitantly with the second portion forming the active zone of the light-emitting diodes.
• the method comprises an additional step f), implemented after step e), of forming a layer of an electrically insulating material, said layer of electrically insulating material being selectively formed on the outer surfaces of the light confinement walls, on the surfaces defined by the spacing between the light confinement walls and the light emitting diodes, and on the surfaces defined by the spacing between all or part of the light emitting diodes.
• the method includes a step g) of forming an upper electrode on the surface free of electrically insulating material resulting from step f).
• Each light confinement wall is electrically isolated from at least one element chosen from: the other light confinement walls of the sub-pixel zone, all or part of the upper electrodes and all or part of the conductive parts of the substrate.
• the light containment walls do not emit light.
• the method comprises a step h) of forming a layer of a material blocking electromagnetic waves from or towards the light-emitting diodes, said layer of material blocking electromagnetic waves being formed on the free surfaces resulting from step g) except the side and top surfaces of the light emitting diodes.
• the layer of opaque material or reflecting electromagnetic waves is formed directly on all or part of the exterior surfaces of the light confinement walls, on all or part of the surfaces defined by the spacing between the light confinement walls and the light emitting diodes and on all or part of the surfaces defined by the spacing between the light-emitting diodes with the exception of the side and top walls of the light-emitting diodes.
• the layer of material blocking the electromagnetic waves is formed directly on all or part of the free surfaces of the layer of insulating material obtained in step f), with the exception of the side and top walls of the light-emitting diodes.
• the method comprises a step i) of forming an encapsulation layer at least partially surrounding the light-emitting diodes contained in the same sub-pixel zone.
• the invention also relates to an optoelectronic device obtained by the implementation of a manufacturing method according to the invention where all or part of the light confinement walls are formed from the same materials as all or part of the first, second and third portions of light emitting diodes.
• All the light-emitting diodes in the same sub-pixel area have a diameter of between 0.8 times the average diameter of the light-emitting diodes in the sub-pixel area and 1.2 times the average diameter of the light-emitting diodes in the area of subpixel and a height between 0.8 times the average height of the light-emitting diodes of the sub-pixel area and 1.2 times the average height of the light-emitting diodes of the sub-pixel area.
• All light emitting diodes in the same sub-pixel area emit light with a wavelength between 0.98 times the average wavelength of light emitted by light emitting diodes in the sub-pixel area and 1.02 times the average wavelength of the light emitted by the light-emitting diodes of the sub-pixel area.
• FIG. 1 represents a top view of an example of creation of zones preliminary to the formation of light-emitting diode portions on the one hand and of zones preliminary to the formation of elements of light confinement walls on the other hand.
• FIG. 2 represents a top view of a variant of FIG. 1 where the zones preliminary to the formation of elements of light confinement walls are formed in one piece.
• FIG. 3 represents a top view of a variant of FIG. 2.
• Figure 4 illustrates a cross section of a three-dimensional light emitting diode.
• FIGS. 5 to 8 show, in side section, successive steps of an example of a manufacturing process according to the invention implemented from the situation in FIG. 1 or 2.
• Figure 9 shows a perspective view of the formation of light confinement wall elements.
• FIG. 10 illustrates a perspective view of the formation of elements of light confinement walls.
• FIG. 11 represents a perspective view of light confinement walls.
• Figures 12 and 13 show, in sectional view, two variants of optoelectronic devices manufactured according to the manufacturing process.
• FIGS. 14 and 15 show, in section view, two variants of optoelectronic devices manufactured according to the manufacturing process. DETAILED PRESENTATION OF PARTICULAR EMBODIMENTS
• Figures 1 or 2, 5 to 9 are partial views from above and in section of different stages of a first example of implementation of a manufacturing method according to the invention.
• each of FIGS. 5 to 9 or 12 and 15 represents only an assembly comprising three light-emitting diodes 13 and two light confinement walls 15.
• the number of light-emitting diodes 13 and walls of light confinement 15 is not however limited to the particular examples illustrated in the figures.
• the invention relates firstly to a method of manufacturing an optoelectronic device 10 comprising light-emitting diodes 13, arranged in sub-pixel zones 14 defined by the light confinement walls 15 situated opposite, said light-emitting diodes 13 d ' the same sub-pixel zone 14 having a homogeneity of dimensions between them improved compared to the prior art.
• a particularly targeted application is the provision of an image display screen or an image projection device.
• the invention can target other applications, in particular the detection or measurement of electromagnetic radiation or even photovoltaic and lighting applications.
• Figures 5 to 8 illustrate different steps of a first example of implementation of a manufacturing method according to the invention.
• the manufacturing method comprises a step of forming a substrate 11 having a support face 111.
• the substrate 11 is constituted for example by a stack of a monolithic layer (not shown), a lower electrode layer (not shown) which can be a conductive germination layer and a first layer of electrical insulation (not shown).
• a monolithic layer not shown
• a lower electrode layer not shown
• a first layer of electrical insulation not shown.
• the support face 111 of the substrate 11 is constituted for example by the free face of said first layer of electrical insulation.
• the monolithic layer can be formed in a semiconductor material doped or not, for example GAI2O3 or silicon or even germanium, and more particularly monocrystalline silicon. It can also be formed from sapphire or even from a III-V semiconductor material, for example GaN. It can alternatively be a substrate of silicon on insulator type or “SOI” for “Silicon On Insulator” according to the English terminology used. Alternatively, the monolithic layer can be formed from an electrically insulating material.
• the lower electrode layer can serve as a germination layer for the growth of portions of light-emitting diodes 13a, 13b, 13c or elements of light confinement walls 152.
• the lower electrode layer can be continuous or discontinuous.
• the material making up the lower electrode layer may be a nitride, a carbide or a boride of a transition metal from column IV, V or VI of the periodic table of the elements or a combination of these compounds.
• the lower electrode layer may be made of aluminum nitride, aluminum oxide, boron, boron nitride, titanium, titanium nitride, tantalum, tantalum nitride, in hafnium, in hafnium nitride, in niobium, in niobium nitride, in zirconium, in zirconium boride, in zirconium nitride, in silicon carbide, in nitride and in tantalum carbide, or in magnesium nitride in the form Mg x N y , where x is approximately equal to 3 and y is approximately equal to 2, for example magnesium nitride in the form Mg3N2.
• the lower electrode layer can be doped and of the same type of conductivity as that of the semiconductor elements intended to grow, and have a thickness for example between 1 nm and 200 nm, preferably between 10 nm and 50 nm.
• the lower electrode layer can be composed of an alloy or a stack of at least one material mentioned in the list above.
• Said first layer of electrical insulation may include a first intermediate insulating layer which covers said lower electrode layer. It forms a growth mask authorizing the epitaxial growth, for example, of the first portions 13a doped with light-emitting diodes 13 to from through openings locally emerging on the surfaces of the lower electrode layer. Said first layer of electrical insulation also forms a growth mask allowing the growth, for example epitaxial growth, of the confinement wall elements 152 from through openings opening locally onto the surfaces of the lower electrode layer.
• the first intermediate insulating layer is produced in at least one dielectric material (s) such as, for example, a silicon oxide (for example Si0 2 or SiON) or a silicon nitride (for example S13N4 or SiN), or even a silicon oxynitride, an aluminum oxide (for example AI2O3) or a hafnium oxide (for example Hf0 2 ).
• the thickness of the first intermediate insulating layer can be between 5 nm and 1 ⁇ m, preferably between 20 nm and 500 nm, for example equal to approximately 100 nm.
• Said first layer of electrically insulating material may also comprise a second electrically intermediate insulating layer (not shown) which covers the first lower electrodes and helps to provide electrical insulation between the first lower electrodes and the second upper electrodes.
• Said second electrically intermediate insulating layer can also cover the growth mask formed by the first intermediate insulating layer.
• the second intermediate insulating layer can be made of a dielectric material identical or different from that of the growth mask, such as, for example, a silicon oxide (for example S1O2) or a silicon nitride (for example S1 3 N4 or SiN ), or even a silicon oxynitride, or a hafnium oxide (for example Hf0 2 ).
• the thickness of the second intermediate insulating layer can be between 5 nm and 1 ⁇ m, preferably between 20 nm and 500 nm, for example equal to approximately 100 nm.
• a second step called b is the formation of a first series of first zones 131, 131a adapted to the formation of portions of light-emitting diodes 13a, 13b, 13c on the support face 111.
• Each zone 131, 131a suitable for the formation of first portions 13a of light-emitting diodes 13 can be formed for example by openings obtained through said first electrically insulating layer and opening onto the lower electrode layer. These openings can also be partially filled with germination materials as described above. This deposit, delimited by the openings in the first insulating layer, constitutes germination pads making it possible to facilitate the growth of the elements of light-emitting diodes 13a, 13b, 13c and of the elements of light confinement walls 152.
• the material constituting the seed pads may be a transition metal from column IV, V or VI of the periodic table of the elements or a nitride, carbide or boride from a transition metal from column IV, V or VI, or a combination of these compounds.
• a third step called c), common to the various embodiments, is the formation of a second series of second zones 151, 151a adapted to the formation of wall elements of light confinement 152 on the support face 111.
• Each zone 151, 151a suitable for the formation of elements of light confinement walls 152 can be formed for example by openings obtained through said first electrically insulating layer and opening onto the lower electrode layer. These openings can also be partially filled with germination materials as described above.
• steps b), c) are carried out in whole or in part at the same time and according to the same techniques, this makes it possible to save process time and gain in precision.
• a fourth step, called d), common to the various embodiments, is the successive formation of portions 13a, 13b, 13c of light-emitting diodes from the areas 131, 131a.
• each light-emitting diode 13 comprises semiconductor elements, a first portion 13a doped according to a first doping type, a second portion 13b forming an active part and a third portion 13c doped according to a second type of doping.
• These semiconductor elements can be arranged in a two-dimensional organization or, as shown in FIG. 4, in three-dimensional manner, according to micrometric or nanometric dimensions.
• the semiconductor elements of the light-emitting diodes 13a, 13b, 13c of each sub-pixel zone 14 have a substantially wire, conical or frustoconical shape.
• the terms “light-emitting diode element” refer to a first portion doped according to a first type of doping 13a and / or a second portion 13b forming an active part and / or a third portion doped according to a second type doping 13c, as well as the stacking of these different portions.
• the embodiments are described for three-dimensional light-emitting diodes 13 of the core-shell type as shown in FIG. 4. However, these embodiments can equally be implemented for diodes three-dimensional light-emitting elements 13 having an axial structure where the first doped portion 13a, the active part 13b and the third doped portion 13c are stacked in a direction transverse to the plane of the substrate 11.
• the embodiments can also be applied for light-emitting diodes having a stack of layers parallel to the support face 111 of a first portion 13a, a second portion 13b and a third portion 13c.
• presenting a multitude of zones 131 to form a multitude of light-emitting diodes per sub-pixel zone 14 an embodiment shown in FIG.
• the method according to the invention will make it possible to homogenize the thicknesses of the layers 13a, 13b, 13c, between the outer edges of the light-emitting diode 13 and its center.
• each first portion 13a of light-emitting diode 13a of the same sub-pixel zone 14 is connected to a first lower electrode, formed in the substrate (not shown and which may be the germination layer), continuous or not. .
• a first lower electrode formed in the substrate (not shown and which may be the germination layer), continuous or not.
• Those skilled in the art can refer to patent FR3053530 to produce the substrate containing the appropriate lower electrodes.
• An upper electrode 17 in contact with the third doped portions 13c is formed on all the light-emitting diodes 13 of the same sub-pixel zone 14.
• the terms "diameter” or “mean diameter” of a wire or of a light-emitting diode 13 or of a layer deposited around or on a light-emitting diode 13 designate an amount of diameter associated with the surface of the straight section of the wire 13 or of the light-emitting diode 13, for example this corresponds to the diameter of the disc whose area is equivalent to that of the straight section of the diode 13.
• each light-emitting diode 13 can have a wire shape formed by the stack three-dimensional of a first portion doped according to a first type of doping 13a, of a second portion 13b and of a third portion 13c, the stack extending transversely to the plane of the first face 111.
• wires "and" light emitting diode elements are equivalent.
• the light-emitting diodes 13 can be, at least in part, formed from group IV semiconductor materials such as silicon or germanium or else mainly comprising a compound III-V, for example compounds III-N .
• group III include gallium, indium or aluminum.
• III-N compounds are GaN, AIN, InGaN or AlInGaN.
• Other elements of group V can also be used, for example, phosphorus, arsenic or antimony.
• the elements in compound III-V can be combined with different molar fractions.
• the light-emitting diodes 13 can equally be formed from semiconductor materials mainly comprising a compound II-VI.
• the dopant can be chosen, in the case of a compound III-V, from the group comprising a P type dopant from group II, for example magnesium, zinc, cadmium or mercury, a P type dopant from group IV, for example carbon, or an N type dopant from group IV, for example silicon, germanium, selenium, sulfur, terbium or tin.
• a P type dopant from group II for example magnesium, zinc, cadmium or mercury
• P type dopant from group IV for example carbon
• an N type dopant from group IV for example silicon, germanium, selenium, sulfur, terbium or tin.
• the cross section of the wires 13 can have different shapes such as, for example, an oval, circular or polygonal shape (for example square, rectangular, triangular, hexagonal).
• an oval, circular or polygonal shape for example square, rectangular, triangular, hexagonal.
• the shape of the cross section of the light-emitting diodes 13 is hexagonal
• the cross section is rectangular.
• the active layer 13b is the layer from which the majority of the radiation supplied by the light-emitting diode 13 is emitted. It may include means for confining the carriers of electric charge, such as quantum wells. It is, for example, made up of alternating layers of GaN and InGaN. The GaN layers can be doped. Alternatively, the active layer consists of a single layer of InGaN.
• the different layers 13a, 13b, 13c constituting the light-emitting diodes 13 can be obtained by any technique skilled in the art, for example: chemical vapor deposition (CVD), acronym for Chemical Layer deposition, deposition atomic layer (ALD) acronym for Atomic Layer Deposition, or physical vapor deposition (PVD) acronym English for Physical Vapor Deposition or by epitaxy (for example MBE, MOVPE).
• CVD chemical vapor deposition
• ALD deposition atomic layer
• PVD physical vapor deposition
• a fifth step called e), common to the various embodiments, is the formation of light confinement wall elements 152 from the zones 151, 151a.
• light confinement wall elements 152 is intended to mean the portions of the light confinement walls 15 formed during step e) which takes place in whole or in part at the same time as the formation of the light-emitting diode elements 13a, 13b, 13c. .
• a light confinement wall element 152 may for example consist of a first portion which is substantially identical (in material composition and thickness) to the first portion 13a of a light-emitting diode 13 or even comprise a second substantially identical portion (in composition of material and thickness) to a second portion 13b of light-emitting diode 13 or else to comprise a third portion substantially identical (in material composition and of thickness) to a third portion 13c of light-emitting diode 13.
• the elements of light confinement walls 152 can be considered as themselves luminous confinement walls 15.
• the elements of light confinement walls 152 are arranged so as to obtain a dispersion of less than 20% in heights and widths of the light-emitting diodes 13 contained in the same sub-pixel zone 14 and this without any additional step compared to the steps. for the formation of light-emitting diodes 13.
• the confinement wall elements 152 are obtained at the same time and by the same technique as the light-emitting diode elements 13.
• the formation of the light confinement wall elements 152 will influence the formation of the elements of the light-emitting diodes 13a, 13b, 13c.
• the elements of light confinement walls can coalesce in whole or in part during step e).
• the coalescence of the elements 152 forms luminous confinement walls in one piece.
• the elements of light confinement walls 152 are made wholly or partly by the same materials as the portions 13a, 13b, 13c of light-emitting diodes.
• the similar nature of the light confinement wall elements 152 and of the portions 13a, 13b and 13c of the light-emitting diodes and the arrangement of the light confinement walls of the method of the invention thus advantageously make it possible to reduce the parasitic residues of material constituting the elements. of light-emitting diodes by their adsorption or absorption by the elements of light confinement walls 152 in the zones where the light-emitting diodes are absent.
• the elements of light confinement walls 152 and therefore also the light confinement walls 15 are, by way of example, at least in part, formed from group IV semiconductor materials such as silicon or germanium or else mainly comprising a compound III-V, for example compounds III-N.
• group III include gallium, indium or aluminum.
• III-N compounds are GaN, AIN, InGaN or AlInGaN.
• Other elements of group V can also be used, for example, phosphorus, arsenic or antimony.
• the elements in compound III-V can be combined with different molar fractions.
• the elements of light confinement walls 152 can either be formed from semiconductor materials mainly comprising a compound II-VI.
• the dopant can be chosen, in the case of a compound III-V, from the group comprising a P type dopant from group II, for example magnesium, zinc, cadmium or mercury, a P type dopant from group IV, for example carbon, or an N type dopant from group IV, for example silicon, germanium, selenium, sulfur, terbium or tin.
• a P type dopant from group II for example magnesium, zinc, cadmium or mercury
• P type dopant from group IV for example carbon
• an N type dopant from group IV for example silicon, germanium, selenium, sulfur, terbium or tin.
• the different layers constituting the light confinement wall elements 152 can be obtained by any technique skilled in the art, for example: chemical vapor deposition (CVD), atomic layer deposition (ALD), or physical vapor deposition (PVD) or by epitaxy (MOVPE, MBE) or epitaxy by molecular jets or by laser assisted deposition (PLD for Pulsed Laser deposition).
• CVD chemical vapor deposition
• ALD atomic layer deposition
• PVD physical vapor deposition
• MOVPE, MBE epitaxy
• PLD laser assisted deposition
• the light confinement walls 15 are not electrically connected to the substrate 11.
• Those skilled in the art can use any technique to electrically isolate the light confinement walls 15 for example by creating a discontinuity in the conductive germination layer around the walls of light confinement 15.
• Those skilled in the art may also for example create deep insulation trenches in the substrate 11 by the face opposite to the support face 111 and fill them with an electrical insulator.
• the man of profession may also choose to create a discontinuity in the upper electrode layer 17 to electrically isolate, by the free face, the light confinement walls 15.
• FIG. 14 illustrates an example of insulating trenches 20 placed at the level of the light confinement walls 15.
• the light confinement walls advantageously do not emit light, which is advantageous so as not to emit interference light with that coming from the light-emitting diodes 13.
• the zones 151a adapted to the formation of elements of luminous confinement walls 152 are arranged and dimensioned so as to obtain sub-zones 151a inter spaced from 50 nm to 5 pm.
• the complete formation of the light confinement walls 15 is done by coalescence of the elements of the light confinement walls 152.
• FIGS. 10 and 11 illustrate this method, where from elements 152 of discontinuous light confinement walls, by growth and coalescence of each of these elements 152 of light confinement walls, a light confinement wall is obtained in a single block. The coalescence may nevertheless not be completely total and allow free spaces 152a to appear within or between the light confinement walls 152.
• An electrical insulating layer 16 can then be deposited in these free spaces 152a for example during one of the steps specified later.
• the zones 151 adapted to the formation of light confinement wall elements 152 are arranged and dimensioned so as to obtain by growth wall elements of light confinement 152 directly in one piece.
• the zones 151 preliminary to the formation of the elements of light confinement walls 152 are arranged at a distance DI from the zones preliminary to the formation of portions of light-emitting diodes 131 situated on the periphery of the same under zone.
• -pixel 14 defined by the arrangement of the light confinement walls 15.
• the distance DI can advantageously verify at least one of the following conditions:
• the distance DI is between half and 100 times the pitch separating all or part of two adjacent light-emitting diodes 13,
• the distance DI is between once and 500 times the diameter of all or part of the light-emitting diodes 13, the distance DI is less than or equal to twice the diffusion length of the atomic species comprising at least all or part of at least one light-emitting diode 13.
• step The periodic distance separating at least two light-emitting diodes 13 is called "step".
• DI is between 2.5 and 50 pm and ideally between 5 and 25 pm.
• the distance DI is advantageous because for cases where the heights of light-emitting diodes 13 are of the order of 0.5 to 40 ⁇ m in height, with a step of 5 ⁇ m between diodes 13, the light confinement wall elements 152 make it possible to limit by capture of residual material, during their formation, to less than 20% the difference between the individual diameter of the light-emitting diode elements 13 located on the periphery of the same sub-pixel zone 14 and the average diameter of the diode elements light emitting 13a, 13b, 13c of the sub-pixel area 14 concerned.
• the elements of light confinement walls 152 are formed, with the same technique, with the same materials as the portions of light-emitting diodes 13a, 13b, 13c, under the same conditions as the portions of diodes light emitting diodes 13a, 13b, 13c and obtained at the same time as the portions of light emitting diodes 13a, 13b, 13c.
• the similarity of material between the light-emitting diode portions 13a, 13b, 13c and the elements of light confinement walls 152 advantageously allows the elements of light confinement walls 152 to have the ability to capture all or part of the material used for the formation of the light-emitting diode elements 13a, 13b, 13c during the common part of their training stage e).
• attitude for capturing matter is understood to mean the ability of structures to attract matter (atoms or molecules) to them in order to grow or enlarge during growth, and this by adsorption, absorption, epitaxy transformation or uptake of atoms / molecules supplied during the growth phase.
• This step e) advantageously takes place in whole or in part concomitantly with the step of forming the elements of the light-emitting diodes 13a, 13b, 13c so that the formation d) of the elements of light-emitting diodes 13a, 13b, 13c situated on the periphery of the same sub-pixel zone 14 defined by the arrangement of the light confinement walls 15 is controlled by the formation, preferably with the same technique to save time, at the same time elements of light confinement walls limiting the sub-pixel zone 14.
• “Concurrently” means an action taking place at the same time or simultaneously. This may involve the use of the same production technique to guarantee temporal simultaneity. This can also imply a spatial proximity, of the order of Dl, of the elements of diodes 13a, 13b, 13c and of elements of light confinement walls 152 so that the simultaneity of the growth of the elements of light-emitting diodes 13a, 13b, 13c and light confinement wall elements 152 could allow the latter to influence the former.
• the presence of elements of light confinement walls 152 described above advantageously makes it possible to limit the supply of material, by absorption or adsorption of material by the elements of light confinement walls 152 during their growth, which is usually calibrated by a person skilled in the art to form elements of light-emitting diodes 13a, 13b, 13c arranged according to a given density and which therefore becomes surplus for the portions of diodes 13a, 13b, 13c situated on the periphery of the sub-pixel zone 14 in absence of light containment walls 15.
• this method makes it possible to limit the difference between the diameter of the light-emitting diode elements 13a, 13b, 13c located at the periphery of the zone to less than 20%. of sub-pixel 14 defined by the arrangement of the light confining walls 15 and the average diameter of the light-emitting diode elements 13a, 13b, 13c of the sub-pixel area 14 concerned.
• this method also makes it possible to limit to less than 20% the difference between the height of the light-emitting diode elements 13a, 13b, 13c situated on the periphery of a sub-pixel zone 14 and the average height of the light-emitting diodes 13 of the sub-pixel area 14 concerned.
• the method of the invention allows the wavelength emitted by each of the light-emitting diodes 13 of the same sub-pixel zone 14 to be substantially homogeneous from one diode to the other including for a light-emitting diode 13 located on the periphery compared to those located in the center. More preferably, all the light-emitting diodes 13 included in the same sub-pixel zone 14 emit light with a wavelength between 0.98 times the average wavelength of the light emitted by the diodes light-emitting diodes 13 of the sub-pixel area 14 and 1.02 times the average wavelength of the light emitted by the light-emitting diodes 13 of the sub-pixel area 14. For example, for a target wavelength of 450 nm then the wavelength emitted by applying the method resulting from the invention makes it possible to obtain a light emission of between 441 nm and 459 nm.
• the method comprises a step f), after step e), of forming a layer of electrically insulating material 16, said layer of electrically insulating material 16 being selectively formed on the external surfaces 153 of the wall elements of light confinement 152 as well as on the surfaces 112 defined by the spacing between the elements of confinement walls t luminous 152 and the light-emitting diode elements 13a, 13b, 13c as well as on the surfaces 113 defined by the spacing between the light-emitting diode elements 13a, 13b, 13c.
• the insulating layer 16 may be a dielectric material, for example silicon oxide, silicon nitride, silicon oxynitride, aluminum oxide, hafnium oxide, or diamond. This insulating layer 16 has a thickness for example between 5 nm and 800 nm.
• the method comprises a step g) of forming an upper electrode layer 17 composed of at least one preferentially transparent conductive material, such as oxide d 'indium tin ITO (for Indium Tin Oxide in English) or ZnO doped for example with aluminum or gallium, on the free surface of the layer formed in step f).
• This upper electrode layer 17 makes it possible to make electrical contact on the third portion 13c of the light-emitting diodes 13.
• the upper electrode layer 17 can comprise a stack of several layers of conductive materials.
• the method comprises a step h) of forming a layer 18 of a material blocking the electromagnetic waves coming from or being in the direction of the light-emitting diodes 13.
• blocking the electromagnetic waves means "Be opaque or reflective".
• the layer 18 of material blocking the electromagnetic waves can also reflect or be opaque for the electromagnetic waves converted by the color converters such as for example quantum dots or else phosphors.
• Said layer 18 of opaque or reflecting material is formed on the free surfaces resulting from step g) with the exception of the side 171 and top 172 surfaces of the light-emitting diodes 13.
• the material opaque or reflecting electromagnetic waves can be formed from the same material or a plurality of different materials deposited on top of each other.
• the reflective materials can be chosen from aluminum, silver, nickel, platinum, or any other suitable material such as materials with different optical indices.
• the material 18 opaque or reflecting the electromagnetic waves emitted by the light-emitting diodes 13 is formed directly on all or part of the exterior surfaces 153 of the elements of light confinement walls 152 and all or part of the surfaces 112 defined by the spacing between the elements of light confinement walls 152 and the light-emitting diodes 13 as well as on all or part of the surfaces 113 defined by the spacing between the light-emitting diodes 13 with the exception of the walls side 171 and top 172 of light-emitting diodes 13.
• the material 18 opaque or reflecting the electromagnetic waves emitted by the light-emitting diodes 13, is formed directly on all or part of the free surfaces 171 of the layer of insulating material 16 obtained at step f), with the exception of the side walls 171 and the top walls 172 of the light-emitting diodes 13.
• an eleventh embodiment corresponds to the realization of the electrical insulation of the elements of light confinement walls 152 by the formation of insulating trenches 20, by any technique known to those skilled in the art, from the rear side 114.
• a twelfth embodiment corresponds to a step i) at least partially covering the light-emitting diodes 13 of the same sub-pixel zone 14 by an encapsulation layer 21.
• the layer of encapsulation 21 can be made of an at least partially transparent insulating material.
• the minimum thickness of the encapsulation layer 21 is between 250 nm and 50 ⁇ m so that the encapsulation layer 21 covers all or part of the light-emitting diodes and all or part of at least one and the same sub-pixel zone 14.
• the encapsulation layer 21 can be made of an at least partially transparent inorganic material.
• the inorganic material is chosen from the group comprising silicon oxides of the SiOx type where x is a real number between 1 and 2 or SiOyNz where y and z are real numbers between 0 and 1 and the aluminum oxides, for example AI 2 O 3 .
• the encapsulation layer 21 can be made of an organic material at least partially transparent.
• the encapsulation layer 21 is a silicone polymer, an epoxy polymer, an acrylic polymer or a polycarbonate.
• the encapsulation layer 21 is composed with at least one phosphor. Said phosphor can for example absorb deep blue or UV light emitted by light-emitting diodes and transform it into green or red, or even blue.
• a method of selective phosphor deposition consists in mixing the grains of phosphor of a first color with photosensitive silicone resin, then after spreading over the whole of the substrate and light-emitting diodes, in fixing phosphors on the zones 14 desired by photolithography. The operation is repeated with a second phosphor for a second color and as many times as there are zones 14 defined by the arrangement of the light confinement walls 15 of different colors.
• Another method is to use inkjet type printing equipment with an “ink” composed of the silicone-phosphor mixture and of specific additives.
• the phosphors are deposited at the required locations.
• the encapsulation layer 21 can contain quantum dots (“Quantum dot” according to the appropriate English terminology).

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• 2018
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