Optoelectronic device

Abstract

Optoelectronic Device This description relates to an optoelectronic device comprising a plurality of light-emitting diodes (103), among which at least one first light-emitting diode (103) is surmounted by a first color converter (113G) consisting of a first region of a first perovskite material. Figure for the abstract: Fig. 2B

Description

Title of the invention: Opto-electronic device technical field

[0001] This description relates generally to electronic devices, in particular opto-electronic devices comprising light-emitting diodes (LEDs), for example LED displays, and the manufacturing processes of such devices. Previous technique

[0002] Numerous electronic devices, particularly optoelectronic devices comprising a plurality of LEDs, have been proposed. However, existing optoelectronic devices comprising a plurality of LEDs and existing methods for manufacturing such devices present several drawbacks. Summary of the invention

[0003] There is a need to overcome all or part of the disadvantages of existing optoelectronic devices comprising a plurality of LEDs and of existing manufacturing processes for such devices.

[0004] For this purpose, an embodiment provides an opto-electronic device comprising a plurality of light-emitting diodes, among which at least a first light-emitting diode is surmounted by a first color converter consisting of a first region in a first perovskite material.

[0005] According to one embodiment, the sides of each light-emitting diode are coated with a reflective layer.

[0006] According to one embodiment, each light-emitting diode comprises a nanowire or a microwire.

[0007] According to one embodiment, the device further comprises, among the plurality of light-emitting diodes, at least one second light-emitting diode surmounted by a second color converter consisting of a second region in a second perovskite material different from the first perovskite material.

[0008] According to one embodiment, the device further comprises, among the plurality of light-emitting diodes, at least one third light-emitting diode not surmounted by a color converter.

[0009] According to one embodiment, the device further comprises, among the plurality of light-emitting diodes, at least a third light-emitting diode surmounted by a third color converter consisting of a third region in a third perovskite material different from the first and second perovskite materials.

[0010] According to one embodiment, the light-emitting diodes are adapted to emit ultraviolet radiation.

[0011] According to one embodiment, the device comprises a substrate in which a control circuit for the light-emitting diodes is formed, and a plurality of elementary chips fixed and electrically connected to the substrate, each elementary chip comprising exactly: - one of the first light-emitting diodes; - one of the second light-emitting diodes; and - one of the third light-emitting diodes.

[0012] According to one embodiment, each light-emitting diode is surrounded by an opaque wall.

[0013] One embodiment provides a method for manufacturing an optoelectronic device, the method comprising the following successive steps: a) formation of a plurality of light-emitting diodes; and b) formation, on at least one first light-emitting diode among the plurality of light-emitting diodes, of a first color converter consisting of a first region in a first perovskite material.

[0014] According to one embodiment, the method further comprises, after step b), a step c) of fixing a temporary support substrate to the side of a face of the device opposite a growth substrate on which the light-emitting diodes were formed in step a).

[0015] According to one embodiment, the process further comprises, after step c), a step of transferring and fixing the structure obtained at the end of step c) onto a transfer substrate, and then a step of removing the temporary support substrate.

[0016] According to one embodiment, the process further comprises, after step c), a step of cutting the structure obtained at the end of step c) into a plurality of elementary chips.

[0017] According to one embodiment, the process further comprises, after the cutting step, a step of transferring and fixing the elementary chips onto a transfer substrate, and then a step of removing the temporary support substrate.

[0018] According to one embodiment, the carrier substrate is transparent to the light produced from the light-emitting diodes. Brief description of the drawings

[0019] These features and advantages, as well as others, will be described in detail in the following description of particular embodiments, given by way of non-limiting example, in relation to the accompanying figures, among which:

[0020] Fig.1A, Fig.1B, Fig.1C, Fig.1D, Fig.1E, Fig.1F, Fig.1G, Fig.1H, Fig.II, Fig.U and Fig.1K illustrate, by schematic and partial side and cross-sectional views, successive stages of a manufacturing process for an opto-electronic device according to an embodiment;

[0021] Fig. 2A and Fig. 2B illustrate, by schematic and partial side and cross-sectional views, successive stages of a manufacturing process for an optoelectronic device according to an embodiment;

[0022] [Fig.3A], [Fig.3B] and [Fig.3C] illustrate, by schematic and partial side and cross-sectional views, successive stages of a manufacturing process for an opto-electronic device according to an embodiment;

[0023] [Fig.4] illustrates, by schematic and partial side and section views (A), (B) and (C), a step in a manufacturing process of an opto-electronic device according to an embodiment;

[0024] [Fig.5] illustrates, by a schematic and partial side and cross-sectional view, a step in a manufacturing process of an opto-electronic device according to an embodiment;

[0025] [Fig.6] illustrates, by a schematic and partial side and cross-sectional view, a step in a manufacturing process of an opto-electronic device according to an embodiment;

[0026] [Fig.7A] and [Fig.7B] illustrate, by schematic and partial side and cross-sectional views, successive stages of a manufacturing process for an optoelectronic device according to an embodiment;

[0027] [Fig.8A] and [Fig.8B] illustrate, by schematic and partial side and cross-sectional views, successive stages of a manufacturing process for an optoelectronic device according to an embodiment;

[0028] Figure 9 illustrates, by schematic and partial side and cross-sectional views (A), (B), (C) and (D), several variants of a step in the deposition of a layer of a perovskite material according to one embodiment; and

[0029] Fig.1OA, Fig.1OB and Fig.1OC illustrate, by schematic and partial side and section views, successive stages of a manufacturing process for an opto-electronic device according to an embodiment. Description of the implementation methods

[0030] The same elements have been designated by the same reference numerals in the different figures. In particular, the structural and / or functional elements common to the different embodiments may have the same reference numerals and may have identical structural, dimensional and material properties.

[0031] For the sake of clarity, only the steps and elements useful for understanding the described embodiments have been shown and are detailed. In particular, the various applications of the optoelectronic devices of this description, including the various electronic devices capable of incorporating such devices, have not been detailed, as the described embodiments are compatible with all or most common applications and with all or most common electronic devices implementing at least one optoelectronic device of the type described, possibly with adaptations within the grasp of a person skilled in the art upon reading this description.

[0032] Furthermore, the realization of a control circuit for an opto-electronic device comprising a plurality of LEDs has not been detailed, the embodiments described being compatible with the usual structures and manufacturing processes of such integrated control circuits.

[0033] Unless otherwise specified, when referring to two elements connected together, this means directly connected without intermediate elements other than conductors, and when referring to two elements coupled together, this means that these two elements can be connected or linked through one or more other elements.

[0034] In the following description, when reference is made to absolute position qualifiers, such as the terms "front", "back", "top", "bottom", "left", "right", etc., or relative position qualifiers, such as the terms "above", "below", "superior", "inferior", etc., or to orientation qualifiers, such as the terms "horizontal", "vertical", etc., reference is made, unless otherwise specified, to the orientation of the figures.

[0035] Unless otherwise specified, the expressions "approximately", "about", "substantially", and "in the order of" mean to within 10% or 10°, preferably to within 5% or 5°.

[0036] Unless otherwise specified, the terms "insulator" and "conductor" mean respectively electrically insulating and electrically conductive.

[0037] Unless otherwise specified, the expression "in contact with" means "in mechanical contact with".

[0038] In the following description, "visible light" means electromagnetic radiation with a wavelength between 380 and 780 nm and "ultraviolet radiation" means electromagnetic radiation with a wavelength between 200 and 380 nm.

[0039] A pixel of an image corresponds to the unit element of the image displayed by a display screen. When the display screen is a color image display screen, it generally includes, for the display of each pixel of the image, at least three light emission and / or intensity control components, also These are called display sub-pixels, each emitting light in essentially a single color (for example, red, green, and blue). The superposition of the light emitted by these three display sub-pixels provides the observer with the perceived color corresponding to the pixel of the displayed image. In this case, the expression "display pixel of the display screen" refers to the set of three display sub-pixels used to display a pixel of an image.

[0040] Fig.1A, Fig.1B, Fig.1C, Fig.1D, Fig.1E, Fig.1F, Fig.1G, Fig.1H, Fig.II, Fig.U and Fig.1K illustrate, by schematic and partial side and cross-sectional views, successive stages of a manufacturing process for an opto-electronic device according to an embodiment.

[0041] Fig. 1A represents a structure obtained at the end of a formation step, on a support substrate 101, or growth substrate 101, of a plurality of light-emitting diodes (“Light-Emitting Diode” - LED) 103.

[0042] The support substrate 101 is, for example, a wafer or a piece of wafer made of a semiconductor material, for example silicon, germanium, silicon carbide (SiC), zinc oxide (ZnO), an IILV compound such as gallium nitride (GaN) or gallium arsenide (GaAs), or any other material on which LEDs can be formed. By way of example, the support substrate 101 is predominantly made of monocrystalline silicon. The support substrate 101 may have a multilayer structure, for example of the SOI (Silicon On Insulator) type.

[0043] In the example shown, each LED 103 comprises at least one three-dimensional semiconductor element of nanometer or micrometer size, for example a nanowire or a microwire, forming a light-emitting diode. The term "nanowire" or "microwire" designates a three-dimensional structure elongated in a preferred direction and whose first and second dimensions, called minor dimensions, are between 5 nm and 5 pm, preferably between 100 nm and 3 pm, the third dimension, called major dimension, or height, being greater than or equal to one, preferably greater than or equal to three, more preferably greater than or equal to five, the larger of the two minor dimensions. By way of example, the height of each microwire or nanowire is greater than or equal to 300 nm, preferably between 500 nm and 50 pm.Each nanowire or microwire can present, in a cross-sectional plane substantially orthogonal to its major dimension, a cross-section of any shape, for example polygonal — for example rectangular, square, triangular, hexagonal, etc. — or rounded — for example oval, circular, etc. In the following description, the term "wire" is used to refer indifferently to a nanowire or a microwire.

[0044] Although not detailed in the figures to avoid cluttering the drawing, each LED 103, for example, has a so-called "core-shell" structure. In this case, each LED 103 comprises, for example, at least three concentric semiconductor regions, among which: - a central region, for example doped with type P, for example a nanowire or microwire of substantially cylindrical shape extending vertically along a principal direction substantially orthogonal to the upper face of the support substrate 101; - an active region, for example unintentionally doped, surrounding the central region and having, for example, a hollow cylindrical shape whose inner lateral wall is located on and in contact with the outer lateral wall of the central region; and - a peripheral region, for example doped with type N, surrounding the active region and having for example a hollow cylindrical shape whose inner lateral wall is located on and in contact with the outer lateral wall of the active region, the active region being interposed between the central region and the peripheral region.

[0045] By way of example, each LED 103 is an inorganic LED, the active layer of each LED 103 being exclusively, or predominantly, made of one or more inorganic semiconductor materials. By way of example, the LEDs 103 comprise predominantly, preferably more than 60% by mass, more preferably more than 80% by mass, at least one inorganic semiconductor material, for example selected from silicon, germanium, silicon carbide, a III-V compound, an ILVI compound, or a combination of at least two of these compounds.

[0046] The LEDs 103 are, for example, formed by epitaxial growth from the upper surface of the support substrate 101. Alternatively, the LEDs 103 are formed by epitaxial growth from the upper surface of a germination layer (not shown) covering the upper surface of the support substrate 101, the germination layer being made of a material designed to promote wire growth. In the illustrated example, the upper surface of the support substrate 101 is coated with an insulating layer 105 comprising openings 107 through which the nanowires or microwires of the LEDs 103 extend. The openings 107 are, for example, regularly distributed, for example, according to a grid with a substantially constant pitch. In the illustrated example, each opening 107 has a cross-section strictly smaller than the desired cross-section of the nanowires or microwires of the LEDs 103.As an alternative, the cross-section of each aperture 107 can be substantially equal to the desired cross-section of the nanowires or microwires of the LEDs 103. In the case where the LEDs 103 have a core-shell structure as described above, the central region of each LED 103 is located on and in contact with the top face. of the support substrate 101 — or the germination layer, if applicable — and the peripheral region is located on and in contact with the insulating layer 105.

[0047] The LEDs 103 are, for example, all substantially identical, apart from manufacturing variations. Each LED 103 is, for example, designed to emit light in substantially one color, for example blue.

[0048] Fig.1B represents a structure obtained after a subsequent step of deposition, on the upper face side of the structure of Fig.1A, of a conductive layer 109 and then of formation of openings 111 in the conductive layer 109.

[0049] After deposition, the conductive layer 109 covers, for example, the entire upper surface of the structure of [Fig. 1A]. In the example shown, the conductive layer 109 extends laterally, between the LEDs 103, on and in contact with parts of the upper surface of the insulating layer 105 not covered by the LEDs 103. Furthermore, in this example, the conductive layer 109 is located on and in contact with the lateral and upper surfaces of the LEDs 103.

[0050] The conductive layer 109 is adapted to allow the passage of electromagnetic radiation emitted by the LEDs 103. The conductive layer 109 is, for example, made of a transparent and conductive material, for example indium tin oxide (ITO), zinc oxide doped with aluminum or gallium, etc. By way of example, the conductive layer 109 has a thickness in the range of 10 nm to 1 pm.

[0051] In the illustrated example, the openings 111 laterally delimit portions of the conductive layer 109, each covering a group of three LEDs 103 intended to form part of a PIX display pixel of the optoelectronic device. The portions of the conductive layer 109 are electrically insulated from one another. Each portion of the conductive layer 109 is, for example, intended to form a common cathode electrode for the group of three LEDs 103 it covers. Each opening 111 has, for example, in top view, a rectangular shape surrounding three LEDs 103. The openings 111 form, for example, in top view, a grid in which each square comprises three LEDs 103.

[0052] Fig. 1C represents a structure obtained at the end of a further step of forming color converters 113R and 113G surmounting certain LEDs 103.

[0053] In the example shown, for each group of three LEDs 103 coated with the same portion of the conductive layer 109, one of the LEDs 103 is topped with the color converter 113R, another of the LEDs 103 is topped with the color converter 113G, and the last of the LEDs 103 is not topped with any color converter. In the case where each LED 103 is intended to emit blue light, the color converter 113R is, for example, intended to convert the blue light emitted by the underlying LED 103 into red light, and the converter of color converter 113G, for example, is designed to convert the blue light emitted by the underlying LED 103 into green light. In this case, each pixel PIX of the optoelectronic device comprises a green sub-pixel, including the LED 103 topped with the color converter 113G, a red sub-pixel, including the LED 103 topped with the color converter 113R, and a blue sub-pixel, including the LED 103 without a color converter.

[0054] In the illustrated example, each color converter 113R, 113G covers the upper face and the side face(s) of the underlying LED 103. Each color converter 113R, 113G is, in the example shown, located on and in contact with portions of the conductive layer 109 covering the upper face and the side face(s) of the underlying LED 103. Each color converter 113R, 113G may also extend, as in the example illustrated in [Fig. IC], onto and in contact with portions of the conductive layer 109 located at the periphery of the LED 103.

[0055] According to one embodiment, each color converter 113G, 113R consists of a region made of a perovskite material. A perovskite material is, for example, a material having an "ABX3" crystal structure, in which "A" and "B" represent two positively charged ions, or cations, and in which "X" represents a negatively charged ion, or anion. The anion X, typically a halogen anion, is bonded to the two cations A and B. The cations A and B may be of different sizes, for example, the A cations being larger than the B cations. However, this description is not limited to these examples. By way of alternative, at least one of the A and B sites of the perovskite materials of the color converters 113G and 113R may have an "Alx" type configuration.iA2x and / or Bly _ iB2y, and the anion X can deviate from the ideal coordination configuration, for example when the ions located in the A and B sites undergo changes in their oxidation states.

[0056] Cation A is, for example, an organic cation, such as methylammonium, formamidinium, etc. Alternatively, cation A may be an inorganic cation, such as cesium, rubidium, or potassium. Furthermore, cation B is, for example, a lead, tin, etc. cation. In the case of a halogenated perovskite material, anion X is a halide ion, such as a chloride, bromide, or iodide ion.

[0057] The perovskite material may have a so-called "0D" or "2D" crystalline structure, for example with a composition comprising the same elements as ABX3 type perovskite materials but with different composition ratios. As For example, Cs4PbBr6 is an OD type perovskite material and CsPb2Br5 is a 2D type perovskite material.

[0058] Furthermore, the perovskite material may include additives to the reference ABX3 composition. In this case, the perovskite material includes, for example, one or more doping species intended to improve the optical performance of the color converters.

[0059] The perovskite material of the 113G color converters is different from that of the 113R color converters. For example, the 113G and 113R color converters are respectively made of CsPbBr3 and CsPbI2Br.

[0060] To produce the color converters 113G and 113R, a first layer of a first perovskite material, for example the perovskite material of the color converters 113G, is deposited on the upper face of the structure in [Fig. 1B] and then partially removed so as to retain only regions of the first layer located at the desired positions of the color converters 113G. A second layer of a second perovskite material (the perovskite material of the color converters 113R, in this example) is then deposited on the upper face of the structure and then partially removed so as to retain only regions of the second layer located at the desired positions of the color converters 113R.As an example, the removal steps of portions of the first and second layers leading to the delimitation of the 113G and 113R color converters are implemented by etching, for example by plasma etching using hydrogen bromide (HBr) and argon (Ar). Alternatively, the 113R color converters can be produced before the 113G color converters, with the second layer being deposited before the first layer.

[0061] Fig.1D represents a structure obtained after a subsequent step of depositing an insulating layer 115 and then a reflective layer 117, or mirror layer, on the upper face side of the structure of Fig.1C.

[0062] The insulating layer 115 is, for example, intended to promote the reflection, on the reflective layer 117, of the electromagnetic radiation from the LEDs 103. The insulating layer 115 also fulfills, for example, a protective function for the color converters 113G and 113R. By way of example, the insulating layer 115 is made of a nitride, for example silicon nitride, or of an oxide, for example silicon oxide.

[0063] The reflective layer 117 is intended to reflect the electromagnetic radiation from the LEDs 103. The reflective layer 117 is for example made of a metal, for example aluminium, or of a metal alloy.

[0064] Fig. 1E represents a structure obtained as a result of a subsequent etching step, for example an anisotropic etching, of the reflective layer 117.

[0065] At the end of this step, only portions of the reflective layer 117 covering the sides of the LEDs 103 are retained. These portions of the reflective layer 117 form, for example, reflective walls surrounding the LEDs 103 laterally. In this example, the portions of the reflective layer 117 covering the upper faces of the LEDs 103 and the portions of the reflective layer 117 extending laterally between the LEDs 103 are removed.

[0066] As an example, the etching is of the RIE plasma type (from the English "Reactive Ion Etching"), for example a "spacer" type etching.

[0067] In the illustrated example, the insulating layer 115 remains intact after the etching step. The insulating layer 115 is advantageously used, for example, as an etching stop layer. This example is not, however, limiting. Alternatively, portions of the insulating layer 115, for example, those located directly above the portions of the reflective layer 117 that are removed during the etching step, may also be removed during this step.

[0068] Fig.1F represents a structure obtained after a subsequent step of deposition, on the upper face side of the structure of Fig.1E, of a planarization layer 119 and then of fixing, on the planarization layer 119, of a temporary support substrate 121, or handle.

[0069] In the example shown, the planarization layer 119 extends over and is in contact with the entire upper surface of the structure of [Fig. 1E]. In this example, the planarization layer fills, that is, completely fills, all the free spaces extending laterally between the LEDs 103. The planarization layer 119 is made of a material, for example a silicon oxide, suitable for transmitting electromagnetic radiation from the LEDs 103.

[0070] During this step, optical cavities 123, laterally delimited by reflective walls 125, for example metallic walls, can further be formed directly above each LED 103, as in the example illustrated in [Fig. 1F], using the planarization layer and / or additional layers. Alternatively, the optical cavities 123 can be omitted. In this case, the structure of [Fig. 1F] lacks the reflective walls 125.

[0071] In the example shown, the temporary support substrate 121 is fixed to the upper face of the planarization layer 119 by means of a detachment layer 127.

[0072] Fig. 1G represents a structure obtained after a subsequent step of removing the support substrate 101.

[0073] In the example shown, the structure is reversed with respect to the orientation of [Fig. 1F]. The support substrate 101 is, for example, completely removed, as in the example illustrated in [Fig.1G]. As an example, the support substrate 101 is removed by grinding.

[0074] Fig. 1G further illustrates a step of forming, on the upper face of the structure, for each of the LEDs 103 of the device, a metal connection pad 129 intended to be connected to, or to form, the anode electrode of the LED 103. The metal connection pad 129 allows, for example, a current flowing through the LED 103 and / or a voltage to be applied across the terminals of the LED 103. During this step, other metal connection pads 131 intended to be connected each to the cathode electrode(s) of the LEDs 103 that are part of the same pixel PIX are also formed on the upper face of the structure. This corresponds to a case in which the contact on the cathode electrodes is taken collectively for the three LEDs 103 of each pixel PIX, the metal pad 131 being in contact with the part of the conductive layer 109 covering the group of three LEDs 103 of the display pixel PIX of the opto-electronic device..

[0075] This example is not, however, limiting. As an alternative, it could be provided that each LED 103 is coated with a portion of the conductive layer 109 electrically isolated from portions of the conductive layer 109 coating the other LEDs 103. In this case, a metal pad 131 is formed, for example, for each LED 103, to make contact with the cathode electrode of the LED 103.

[0076] In the example shown, the metal studs 129 and 131 are surrounded laterally by an insulating material, for example silicon oxide, so that the structure has a substantially flat top face comprising an alternation of metallic regions 129, 131 and insulating regions 133.

[0077] The metallic regions 129 and 131 and the insulating regions 133 are, for example, formed by a technique known as "Damascene". An oxide layer intended to form the insulating regions 133 is, for example, deposited on the upper face of the structure, then openings are formed in the oxide layer and filled with the metallic material(s) of the pads 129 and 131. A subsequent polishing step is then carried out, for example, to obtain a substantially flat upper face.

[0078] Figure [1H] represents a structure obtained as a result of a subsequent step of forming trenches 135 extending vertically from the upper face of the structure of Figure [1G] to the detachment layer 127. The trenches 135 laterally delimit a plurality of semiconductor chips 136 corresponding, in this example, to the elementary pixel chips PIX of the display device. The trenches 135 can be formed by plasma etching, sawing, or any other suitable cutting method.

[0079] Figure II represents a structure obtained after a subsequent step of fixing elementary chips 136 onto the upper surface of the same transfer substrate 137 of the display device. The transfer substrate 137 comprises, on its upper surface, a plurality of metal connection pads 139, intended to be fixed and connected electrically and mechanically to corresponding metal connection pads 129 of the elementary chips 136, and a plurality of metal connection pads 141, intended to be fixed and connected electrically and mechanically to corresponding metal connection pads 131 of the elementary chips 136. The transfer substrate 137 has, for example, lateral dimensions strictly greater than those of the temporary support substrate 121.

[0080] In the example shown, the metal studs 139 and 141 are surrounded laterally by an insulating material, for example silicon oxide, so that the structure has a substantially flat upper face comprising an alternation of metal regions 139, 141 and insulating regions 143. By way of example, the metal studs 139 and 141 are made of the same material as the metal studs 129 and 131, and the insulating regions 143 are made of the same material as the insulating regions 133.

[0081] During this step, the structure of [Fig.1H] is for example turned around so as to place the metal connecting pads 129 and 131 of elementary chips 136 opposite corresponding metal connecting pads 139 and 141 of the transfer substrate 137. The opposite pads 129 and 139 and the opposite pads 131 and 141 are then fixed and electrically connected, for example by direct gluing, by welding, by means of microtubes, or by any other suitable method.

[0082] Figure [U] shows a structure obtained, after fixing the elementary chips 136 onto the transfer substrate 137, following a subsequent step of detaching the elementary chips 136 from the temporary support substrate 121 and removing the latter. By way of example, the detachment of the elementary chips 136 is carried out by local peeling or through a mask using a laser beam focused on the peeling layer 127 directly above each elementary chip 136 to be detached, or by mechanical peeling.

[0083] The pitch — that is, the center-to-center distance, viewed from above — of the elementary chips 136 on the transfer substrate 137 is, for example, a multiple of the pitch of the elementary chips 136 on the substrate 121. Thus, only a part of the elementary chips 136 (one chip out of two, in the example shown) is transferred simultaneously from the temporary support substrate 121 to the transfer substrate 137. The other chips 136 remain attached to the temporary support substrate 121 and can be transferred later to another part of the transfer substrate 137 or to another transfer substrate.

[0084] Fig.1K represents a structure obtained after fixing the elementary chips 136 opposite the metal connection pads 139 and 141 of the transfer substrate 137.

[0085] In the example shown, the LEDs 103 of the opto-electronic device are intended to emit light in a direction opposite to the carrier substrate 137 (upwards, in the orientation of [Fig.1K]).

[0086] Although not detailed in Figures II, IJ and 1K in order to avoid overloading the drawing, the substrate 137 includes, for example, a control circuit for the LEDs 103. The control circuit includes, for example, more precisely, for each LED 103 connected to the metal pad 139 dedicated to the LED 103, an elementary control cell comprising one or more transistors, for example thin-film transistors (TFTs), allowing control of the current flowing through the LED 103 and / or the voltage applied across the terminals of the LED 103.

[0087] The optoelectronic device of [Fig. 1K] is, for example, part of a color image display screen. By way of example, the optoelectronic device obtained by the process of Figures IA to 1K is a so-called "microled" display screen.

[0088] Figures IA to 1K illustrate a method used, for example, to create a large display device, such as a television, computer, smartphone, tablet, etc. screen. Such a device comprises, for example, a plurality of elementary chips arranged, for example, in a matrix arrangement, on the same substrate. The elementary chips are mounted securely to the substrate and connected to electrical connection elements of the substrate for control. Each chip, in the example shown, comprises three LEDs 103. In this example, the LEDs 103 are individually controllable and define three emission sub-pixels adapted to emit red, green, and blue light, respectively.

[0089] Fig. 2A and Fig. 2B illustrate, by schematic and partial side and cross-sectional views, successive stages of a manufacturing process for an optoelectronic device according to an embodiment.

[0090] Fig. 2A represents a structure obtained after a step of fixing the structure of Fig. 1G on the upper face of a transfer substrate 237.

[0091] Although not detailed in [Fig. 2A] to avoid cluttering the drawing, control circuits for the LEDs 103 of the optoelectronic device are, for example, pre-formed in the substrate 237. As an example, the control circuits are implemented using CMOS (Complementary Metal-Oxide-Semiconductor) technology. complementary). The transfer substrate 237, for example, has lateral dimensions substantially equal to those of the temporary support substrate 121.

[0092] During this step, the structure of [Fig.1G] is for example turned over so as to place the metal connecting pads 129 and 131 opposite corresponding metal connecting pads 139 and 141 of the transfer substrate 237. The opposite pads 129 and 139 and the opposite pads 131 and 141 are then fixed and electrically connected, for example by direct gluing.

[0093] As an alternative, the cathode electrode can be common to all the PIX pixels of the device. In this case, a single cathode contact is, for example, located at the periphery. This amounts, for example, to providing a structure analogous to that of [Fig. 2A] in which the conductive layer 109 is unstructured, i.e., forms a continuous layer, and comprising a single metal pad 141 located in contact with a single metal pad 131, the pads 131 and 141 being located at the periphery of the PIX pixel matrix.

[0094] Figure 2B represents a structure obtained, after fixing the structure of Figure II onto the transfer substrate 237, following a subsequent step of detaching the temporary support substrate 121 and removing the latter. By way of example, the detachment is carried out by peeling using a laser beam focused on the peel layer 127, or by mechanical peeling.

[0095] The pitch — that is, the center-to-center distance, in top view — of the PIX pixels on the transfer substrate 237 is identical to the pitch of the PIX pixels on the substrate 121. Thus, all the PIX pixels are simultaneously transferred from the temporary support substrate 121 to the transfer substrate 237.

[0096] Unlike the method previously described in relation to Figures IA to 1K, the method described above in relation to Figures 2A and 2B is used, for example, to produce monolithic microdisplays. One advantage of this method is that it allows for display pixels with reduced lateral dimensions, thus enabling high display resolutions. In the example described above, each PIX pixel comprises three emission sub-pixels adapted to emit in three distinct wavelength ranges, for example, red light, green light, and blue light.

[0097] By way of example, the device obtained by the process of Figures 2A and 2B is a micro-screen display microled.

[0098] Fig. 3A, Fig. 3B and Fig. 3C illustrate, by schematic and partial side and cross-sectional views, successive stages of a manufacturing process for an opto-electronic device according to an embodiment.

[0099] Fig. 3A represents a structure obtained after a deposition step, on the upper face side of the structure of Fig. 1A, of the conductive layer 109.

[0100] After deposition, the conductive layer 109 covers, for example, the entire upper face of the structure of [Fig. 1A]. Unlike the structure of [Fig. 1B], the conductive layer 109 of the structure of [Fig. 3A] is devoid of the openings 111.

[0101] Fig. 3B represents a structure obtained after a further step of forming opaque walls 301 laterally surrounding each LED 103. By way of example, the walls 301 are made of an opaque polymer material, i.e. suitable for absorbing the electromagnetic radiation emitted by the LEDs 103. In the example shown, the opaque walls 301 have a height substantially equal to that of the LEDs 103.

[0102] Although this has not been illustrated in [Fig.3B] in order not to overload the drawing, the vertical surfaces of the opaque walls 301 can be coated with a reflective layer, for example analogous or identical to layer 117.

[0103] Fig. 3C represents a structure obtained after a subsequent deposition step, on the upper face side of the structure of Fig. 3B, of the planarization layer 119 and formation of the color converters 113G and 113R.

[0104] In the illustrated example, the planarization layer 119 fills, that is to say completely fills, all the free spaces extending laterally between the LEDs 103. The planarization layer 119 is flush, for example, with the upper faces of the parts of the conductive layer 109 covering the upper faces of the LEDs 103.

[0105] In the example shown, each color converter 113R, 113G extends over and in contact with the part of the conductive layer 109 covering the upper face of the underlying LED 103, and over and in contact with parts of the planarization layer 119 surrounding the LED 103. Each color converter 113R, 113G covers, for example, as in the example illustrated in [Fig.3C], the entire surface delimited laterally by the opaque wall 301 surrounding the underlying LED 103.

[0106] Fig. 4 illustrates, by schematic and partial side and section views (A), (B) and (C), a step in a manufacturing process of an opto-electronic device according to an embodiment.

[0107] View (A) represents a structure 401G obtained after a deposition step, on the upper face side of a structure similar or identical to that of [Fig. 3A], of a layer of the color converter material 113G. In the illustrated example, the color converter 113G covers the entire upper face of the structure. The color converter 113G is, for example, more precisely located on and in contact with the upper face of the conductive layer 109.

[0108] View (B) represents a 401R structure obtained after a deposition step, on the upper face side of a structure analogous or identical to that of [Fig.3A], of a layer of the color converter material 113R. In the illustrated example, the color converter 113R covers the entire upper face of the structure. The color converter 113R, for example, is more precisely located on and in contact with the upper face of the conductive layer 109.

[0109] View (C) represents a 401B structure analogous or identical to that of [Fig.3A].

[0110] [Fig.5] illustrates, by a schematic and partial side and cross-sectional view, a step in a manufacturing process of an opto-electronic device from the structures 401A, 401B and 401C of [Fig.4] according to one embodiment.

[0111] Figure 5 more precisely represents a structure obtained after fixing elementary chips 536G, 536R, and 536B, respectively derived from structures 401G, 401R, and 401B of Figure 4, onto the transfer substrate 137. The fabrication of the elementary chips 536G, 536R, and 536B from structures 401G, 401R, and 401B is, for example, analogous to what was previously described in relation to Figures 1D to 1H for the fabrication of the elementary chips 136 from the structure of Figure 1C. Furthermore, the transfer is, for example, carried out in a manner analogous to what was described above in relation to Figures 11 to 1K in the case of the chips 136.

[0112] In the structure of [Fig. 5], each elementary chip 536G, 536R, 536B corresponds, for example, to a monochromatic S-PIX sub-pixel, each color display PIX pixel of the optoelectronic device comprising three S-PIX sub-pixels comprising respectively the elementary chips 536G, 536R and 536B. Each S-PIX sub-pixel can comprise any number, greater than or equal to one, of nanowires or microwires.

[0113] As an alternative, the optoelectronic device can be made from three monochrome microscreens, for example obtained from structures 401G, 401R and 401B by implementing a manufacturing process analogous to that described in relation to Figures 2A and 2B. In this case, the optical combination of the three monochrome images produced by the three microscreens to reconstruct a color image is, for example, carried out by means of a component known by the English name "combiner cube".

[0114] Fig. 6 illustrates, by a schematic and partial side and cross-sectional view, a step in a manufacturing process of an opto-electronic device according to an embodiment.

[0115] Figure 6 represents a structure obtained after a step of forming color converters 113R and 113G and of forming color converters 113B on LEDs 103 not coated with a color converter 113R or 113G. This corresponds, for example, to a case in which the LEDs 103 emit not blue light, but ultraviolet (UV) radiation. In this case, the LEDs 103 are, for example, gallium nitride (GaN) based, for emission in the near-UV range, for example in the wavelength range from 350 to 400 nm, or based on aluminum gallium nitride (AlGaN), for wavelengths below 350 nm.

[0116] In the example shown, for each group of three LEDs 103 coated with the same part of the conductive layer 109, one of the LEDs 103 is topped with the color converter 113R, another of the LEDs 103 is topped with the color converter 113G, and the last of the LEDs 103 is topped with the color converter 113B. In the case where each LED 103 is intended to emit UV radiation, the color converter 113R is, for example, intended to convert the UV radiation emitted by the underlying LED 103 into red light, the color converter 113G is, for example, intended to convert the UV radiation emitted by the underlying LED 103 into green light, and the color converter 113B is, for example, intended to convert the UV radiation emitted by the underlying LED 103 into blue light.In this case, each pixel PIX of the opto-electronic device comprises a green sub-pixel, including LED 103 surmounted by color converter 113G, a red sub-pixel, including LED 103 surmounted by color converter 113R, and a blue sub-pixel, including LED 103 surmounted by color converter 113B.

[0117] The implementation of the color converters 113B is, for example, analogous to that of the color converters 113G and 113R. The color converters 113B can be implemented before, between, or after the color converters 113G and 113R.

[0118] As an example, the 113B color converters are in CsPbCl3.

[0119] Subsequent steps analogous to those previously described in relation to figures 1D to 1K are then implemented for example to produce an opto-electronic device from the structure of [Fig.6].

[0120] In this process, each LED 103 is fitted with a color converter 113R, 113G, or 113B. This makes it possible to obtain light sources with substantially identical directivity, apart from manufacturing variations. This also allows for better homogeneity. Furthermore, perovskite materials exhibit better absorption in the ultraviolet than in the visible spectrum. The optoelectronic device obtained according to the process described in relation to [Fig. 6] thus has a higher conversion rate than the optoelectronic device obtained according to the process described in relation to Figures IA at 1K.

[0121] Fig. 7A and Fig. 7B illustrate, by schematic and partial side and cross-sectional views, successive stages of a manufacturing process for an optoelectronic device according to an embodiment.

[0122] Fig. 7A represents a structure analogous to that previously described in relation to Fig. U. Unlike the structure of Fig. U, the reflective layer 117 has not been removed above the structure of Fig. 7A. LED 103. This amounts, for example, to omitting the step in [Fig.1E] in the process described above in relation to figures IA to 1K.

[0123] In the case of [Fig.7A], elementary chips 736 analogous to the elementary chips 136 are transferred onto the transfer substrate 137. In this case, the transfer substrate 137 is transparent to the visible light emitted by the LEDs 103.

[0124] Fig. 7B represents a structure obtained after fixing the elementary chips 736 opposite the metal connection pads 139 and 141 of the transfer substrate 137.

[0125] In the illustrated example, the PIX pixels of the opto-electronic device are intended to emit light through the carrier substrate 137 (downwards, in the orientation of [Fig.7B]).

[0126] An advantage of the process described above in relation to Figures 7A and 7B is that it does not involve an etching step of the reflective layer 117. This reduces the risk of damage to the color converters 113R and 113G.

[0127] Fig. 8A and Fig. 8B illustrate, by schematic and partial side and cross-sectional views, successive stages of a manufacturing process for an optoelectronic device according to an embodiment.

[0128] Fig. 8A represents a structure analogous to that previously described in relation to Fig. 1D.

[0129] Unlike the structure of [Fig.1D], the structure of [Fig.8A] is devoid of the reflective layer 117. Furthermore, the color converters 113R and 113G have, in the case of the structure of [Fig.8A], a greater thickness than they do in the case of the structure of [Fig.1D].

[0130] The thickness of the color converters 113R and 113G is chosen, for example, so that the light emitted by the underlying LEDs 103 is totally absorbed by the color converters 113R and 113G.

[0131] Fig. 8B represents a structure analogous to that previously described in relation to Fig. 1F obtained from the structure of Fig. 8A after making the reflective side walls 125 of the optical cavities 123 and deposition, on the side of the upper face of the structure of Fig. 8A, of the planarization layer 119 and then fixing, on the planarization layer 119, of the temporary support substrate 121.

[0132] Steps analogous to those described above in relation to figures IG to 1K can then be implemented from the structure of [Fig.8B] to form an opto-electronic device.

[0133] An advantage of the process described above in relation to Figures 8A and 8B is that it does not involve steps for depositing and structuring a mirror layer coating the LEDs 103. This simplifies the fabrication of the opto device. electronics compared to the process described previously in relation to figures IA to 1K.

[0134] Figure 9 illustrates, by schematic side and cross-sectional views (A), (B), (C) and (D) and partial, several variants of a step of depositing a layer in a perovskite material according to an embodiment.

[0135] View (A) represents a step in the formation of a perovskite-based color converter, for example the 113R color converter, by a non-conforming deposition technique, for example by the so-called pulsed laser ablation technique (“Pulsed Laser Deposition” - PLD).

[0136] View (B) represents a structure obtained, from the structure of view (A), as a result of a further thinning step of the part of the color converter 113R covering the upper face of the LED 103. By way of example, the thinning is carried out by chemical and mechanical polishing (CMP).

[0137] View (C) represents a structure obtained from the structure of view (B) following a subsequent structuring step of the color converter 113R. During this step, the portions of the color converter 113R located on and in contact with the conductive layer 109 at the periphery of the LED 103 are removed. Only portions of the color converter 113R covering the sides and the top face of the LED 103 remain.

[0138] View (D) represents a step in the formation of a perovskite-based color converter, for example the 113R color converter, by a conformal deposition technique, for example by the so-called atomic layer deposition (ALD) technique. In this case, the deposition is followed, for example, by a structuring step analogous or identical to that described above in relation to view (C).

[0139] Although not detailed in the figures, non-conformal deposition techniques can lead to the coating of the LEDs 103 with a layer of perovskite material intended to form each color converter 113R, 113G of the optoelectronic device having a non-constant thickness. In particular, inhomogeneities may appear, after the layer has been deposited, in the portions of the perovskite material layer coating the sides of the LEDs 103. However, such inhomogeneities do not disrupt the operation of the color converters 113R and 113G. In particular, these inhomogeneities do not degrade, or only slightly degrade, the extraction and conversion of the light produced by the LEDs 103.

[0140] Furthermore, the perovskite material layer used to create each color converter 113R, 113G has, for example, a thickness e substantially equal to the wavelength X of the light emitted by the divided LED 103 by the refractive index npk of the perovskite material layer (e = X / npk), or substantially equal to an integer multiple a, greater than or equal to two, of the wavelength X divided by the refractive index npk (e = aX / npk). Various optical effects can be exploited to increase emission efficiency, for example, through stimulated emission, resonance, etc. A person skilled in the art is able, from the information in this description, to calculate optimal thicknesses for the perovskite material layers used to form the color converters 113R and 113G and / or of the assembly formed by the LED 103, the conductive layer 109, and the perovskite material layer of the color converter 113R or 113G, in order to maximize the desired optical effects and thus increase the efficiency of the LED 103.

[0141] Fig.1OA, Fig.1OB and Fig.1OC illustrate, by schematic and partial side and section views, successive stages of a manufacturing process for an opto-electronic device according to an embodiment.

[0142] The [Fig.1OA] represents a structure analogous to that previously described in relation to the [Fig.1D].

[0143] Unlike the structure of [Fig.1D], the structure of [Fig.1OA] is devoid of the color converters 113R and 113G. The structure of [Fig.1OA] is obtained, for example, by depositing the insulating layer 115 and then the reflective layer 117 on the upper face side of the structure of [Fig.1B].

[0144] Fig.1OB represents a structure obtained as a result of a further etching step, for example an anisotropic etching, of the reflective layer 117 of the structure of Fig.1OA.

[0145] At the end of this step, only portions of the reflective layer 117 covering the sides of the LEDs 103 are retained. These portions of the reflective layer 117 form, for example, reflective walls surrounding the LEDs 103 laterally. In this example, the portions of the reflective layer 117 covering the upper faces of the LEDs 103 and the portions of the reflective layer 117 extending laterally between the LEDs 103 are removed.

[0146] The step enabling the structure of [Fig.1OA] to be obtained from the structure of [Fig.1OB] is for example implemented in a manner analogous or identical to the step enabling the structure of [Fig.1E] to be formed from the structure of [Fig.1D].

[0147] Fig. 1OC represents a structure obtained at the end of a further formation step of the color converters 113R and 113G.

[0148] In the example shown, each color converter 113R, 113G extends over and in contact with the part of the insulating layer 115 covering the upper face of the underlying LED 103 and over and in contact with upper faces of parts of the reflective layer 117 which remain after the etching.

[0149] Steps analogous to those described above in relation to Figures 1F to 1K can then be implemented from the structure of [Fig.1OC] to form an opto-electronic device.

[0150] One advantage of the optoelectronic devices described above is that the use of 113R and 113G color converters made of perovskite material allows for higher efficiency, reliability, and longer lifespan than existing optoelectronic devices. Furthermore, the manufacturing processes described above are temperature stable. They also allow for working on entire wafers before transferring them to the substrate containing the TFT transistors.

[0151] Another advantage of the optoelectronic devices described above is that they exhibit a higher absorption coefficient, for example, approximately 10⁶ cm⁻¹ compared to approximately 10³ cm⁻¹ for analogous devices but incorporating quantum dot color converters. This allows the color converters to have much smaller thicknesses, for example, approximately 500 nm compared to approximately 8 to 10 pm for quantum dot color converters, thus making them easier to structure and enabling smaller pixel pitches.

[0152] Various embodiments and variations have been described. Those skilled in the art will understand that certain features of these various embodiments and variations could be combined, and other variations will become apparent to those skilled in the art. In particular, the process described in relation to [Fig. 6], in which the LEDs 103 emit UV radiation and are used in combination with three color converters 113R, 113G, and 113B made of different first, second, and third perovskite materials, is applicable, by those skilled in the art upon reading this description, to the processes described in relation to the other figures.

[0153] Furthermore, the process described in relation to Figures 7A and 7B, in which the transfer substrate 137 is transparent to the light emitted from the LEDs 103, is transposable, by a person skilled in the art upon reading this description, to the processes described in relation to the other figures.

[0154] Although the present description takes as an example the case of optoelectronic devices with light-emitting diodes comprising microwires or nanowires, the embodiments described are not limited to this case and apply more generally to any type of optoelectronic device with light-emitting diodes, for example, optoelectronic devices with light-emitting diodes of micrometer or nanometer size and of conical or truncated pyramidal shape. More generally, a person skilled in the art is able, based on the indications in this description, to transpose the embodiments described to any type of opto-electronic device comprising light-emitting diodes, regardless of the dimensions of these diodes.

[0155] Finally, the practical implementation of the described embodiments and variants is within the reach of a person skilled in the art, based on the functional indications given above. In particular, the described embodiments are not limited to the specific examples of materials and dimensions mentioned in this description.

Claims

Demands

1. Opto-electronic device comprising a plurality of light-emitting diodes (103), among which at least a first light-emitting diode (103) is surmounted by a first color converter (113G) consisting of a first region in a first perovskite material.

2. Device according to claim 1, wherein the sides of each light-emitting diode (103) are coated with a reflective layer (117).

3. Device according to claim 1 or 2, wherein each light-emitting diode (103) comprises a nanowire or a microwire.

4. Device according to any one of claims 1 to 3, further comprising, among the plurality of light-emitting diodes (103), at least a second light-emitting diode (103) surmounted by a second color converter (113R) consisting of a second region in a second perovskite material different from the first perovskite material.

5. Device according to claim 4, further comprising, among the plurality of light-emitting diodes (103), at least one third light-emitting diode (103) not surmounted by a color converter.

6. Device according to claim 4, further comprising, among the plurality of light-emitting diodes (103), at least a third light-emitting diode (103) surmounted by a third color converter (113B) consisting of a third region in a third perovskite material different from the first and second perovskite materials.

7. Device according to claim 6, wherein the light-emitting diodes (103) are adapted to emit ultraviolet radiation.

8. Device according to any one of claims 5 to 7, comprising a carrier substrate (137), in which a control circuit for the light-emitting diodes (103) is formed, and a plurality of elementary chips (136) fixed and electrically connected to the carrier substrate, each elementary chip (136) comprising exactly: - one of the first light-emitting diodes (103); - one of the second light-emitting diodes (103); and - one of the third light-emitting diodes (103).

9. Device according to any one of claims 1 to 8, wherein each light-emitting diode (103) is surrounded by an opaque wall (301).

10. A method for manufacturing an opto-electronic device, the method comprising the following successive steps: a) formation of a plurality of light-emitting diodes (103); and b) formation, on at least a first light-emitting diode (103) among the plurality of light-emitting diodes (103), of a first color converter (113G) consisting of a first region in a first perovskite material.

11. Method according to claim 10, further comprising, after step b), a step c) of fixing a temporary support substrate (121) to the side of a face of the device opposite a growth substrate (101) on which the light-emitting diodes (101) were formed in step a).

12. A method according to claim 11, further comprising, after step c), a step of transferring and fixing the structure obtained at the end of step c) onto a transfer substrate (237), and then a step of removing the temporary support substrate (121).

13. A method according to claim 11, further comprising, after step c), a step of cutting the structure obtained at the end of step c) into a plurality of elementary chips (136; 536R, 536G, 536B; 736).

14. A method according to claim 13, further comprising, after the cutting step, a step of transferring and fixing the elementary chips (136; 536R, 536G, 536B; 736) onto a transfer substrate (137), and then a step of removing the temporary support substrate (121).

15. Method according to claim 12 or 14, wherein the transfer substrate (137; 237) is transparent to the light produced from the light-emitting diodes (103).

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