Opto-electronic device

Abstract

The present description relates to an 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 made of a first perovskite material.

Description

DESCRIPTION Optoelectronic device This application is based on, and claims priority from, French patent application no. FR2414323 filed on December 17, 2024, entitled "Optoelectronic Device", which is considered to be an integral part of this description within the limits provided by law. technical field

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

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

[0003] There is a need to overcome all or part of the drawbacks of existing opto-electronic devices with a plurality of LEDs and of existing manufacturing processes for such devices.

[0004] To this end, one embodiment provides an optoelectronic device comprising a plurality of light-emitting diodes, among which at least one first light-emitting diode is surmounted by a first color converter consisting of a first region in a first perovskite material located on and in contact with a part of a conductive layer located on and in contact with the lateral and upper faces of the light-emitting diodes.

[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 a 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, 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 for carrying, 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 opto-electronic device, the method comprising the following successive steps: a) formation of a plurality of light-emitting diodes; and b) formation, on at least a 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 substrate for the transfer 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 attached figures, among which:

[0020] Figure IA, Figure IB, Figure IC, Figure 1D, Figure 1E, Figure 1F, Figure IG, Figure 1H, Figure II, Figure IJ and Figure 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] Figure 2A and Figure 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] Figure 3A, Figure 3B and Figure 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] Figure 4 illustrates, by schematic and partial side and cross-sectional views (A), (B) and (C), a step in a manufacturing process of an opto-electronic device according to an embodiment;

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

[0025] Figure 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 one embodiment;

[0026] Figure 7A and Figure 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] Figure 8A and Figure 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 layer deposition step in a perovskite material according to one embodiment; and

[0029] Figure 10A, Figure 10B and Figure 10C 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. Description of the implementation methods

[0030] The same elements have been designated by the same reference numerals in the different figures. In particular, 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 implementation methods described are included. have been represented and are detailed. In particular, the various applications of the opto-electronic devices of this description, including the various electronic devices capable of integrating such devices, have not been detailed, the embodiments described being compatible with all or most common applications and with all or most common electronic devices implementing at least one opto-electronic device of the type described, possibly subject to 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 connected elements, this means directly connected without any intermediate elements other than conductors, and when referring to two coupled elements, this means that these two elements can be connected or linked through one or more other elements.

[0034] In the description that follows, when referring to absolute positional qualifiers, such as the terms "front", "back", "top", "bottom", "left", "right", etc., or relative terms such as "above", "below", "superior", "inferior", etc., or orientation qualifiers such as "horizontal", "vertical", etc., refers, unless otherwise specified, to the orientation of the figures.

[0035] Unless otherwise specified, the expressions "approximately", "roughly", "about", 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 electrically insulating and electrically conductive, respectively.

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

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

[0039] A pixel in an image corresponds to the unit of the image displayed by a display screen. When the display screen is a color image display, it generally comprises, for the display of each pixel of the image, at least three light emission and / or intensity control components, also called display sub-pixels, each of which emits 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 color perception 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] In this description, the term "conformal deposition" refers to a thin-film formation technique where the thickness of the deposited material is uniform across all surfaces of the structure, regardless of their geometry or orientation, and the term "conformal layer" refers to a layer obtained by conformal deposition. Thus, a conformal layer has a substantially constant thickness and follows the geometry of the structure it covers.

[0041] Figure IA, Figure IB, Figure IC, Figure 1D, Figure 1E, Figure 1F, Figure IG, Figure 1H, Figure II, Figure IJ and Figure 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.

[0042] Figure IA 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, in English) 103.

[0043] The support substrate 101 is, for example, a wafer or a piece of wafer made of a semiconductor material, such as silicon, germanium, silicon carbide (SiC), zinc oxide (ZnO), a III-V compound such as gallium nitride (GaN) or gallium arsenide (GaAs), or any other material on which LEDs can be formed. As an example, the support substrate 101 is predominantly made of single-crystal silicon. The support substrate 101 may have a multilayer structure, for example, of the SOI (Silicon On Insulator) type.

[0044] 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" refers to a three-dimensional structure elongated along a preferred direction and whose first and second dimensions, called minor dimensions, are included between 5 nm and 5 pm, preferably between 100 nm and 3 pm, the third dimension, called the major dimension, or height, being greater than or equal to one time, preferably greater than or equal to three times, more preferably greater than or equal to five times, 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 have, in a plane of section substantially orthogonal to its major dimension, a cross-section of any shape, for example polygonal—e.g., rectangular, square, triangular, hexagonal, etc.—or rounded—e.g., oval, circular, etc. In the following description, the term "wire" is used to refer interchangeably to a nanowire or a microwire.

[0045] Although not detailed in the figures to avoid cluttering the drawing, each LED 103 exhibits, for example, a so-called "core-shell" structure. In this case, each LED 103 comprises, for example, at least three concentric semiconductor regions, including: - a central region, for example P-type doped, 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 N-doped, 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 region active, the active region being interposed between the central region and the peripheral region.

[0046] For 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. For example, 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, a II-VI compound, or a combination of at least two of these compounds.

[0047] 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, in 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 upper face of the. support substrate 101 — or germination layer, if applicable — and the peripheral region is located on and in contact with the insulating layer 105.

[0048] For example, the 103 LEDs are all essentially identical, apart from manufacturing variations. Each 103 LED is designed to emit light in essentially a single color, for example, blue.

[0049] Figure IB represents a structure obtained after a subsequent step of deposition, on the upper face side of the structure of Figure IA, of a conductive layer 109 and then of formation of openings 111 in the conductive layer 109.

[0050] After deposition, the conductive layer 109 covers, for example, the entire upper surface of the structure in Figure IA. In the example shown, the conductive layer 109 extends laterally, between the LEDs 103, onto 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.

[0051] 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, such as indium tin oxide (ITO), aluminum- or gallium-doped zinc oxide, etc. As an example, the conductive layer 109 has a thickness ranging from 10 nm to 1 pm.

[0052] In the illustrated example, the openings 111 laterally delimit parts of the conductive layer 109, each covering a group of three LEDs 103 intended to be part of a DIX display pixel of the opto-electronic device. The portions of the conductive layer 109 are electrically insulated from one another. Each portion of the conductive layer 109 is, for example, designed to form a common cathode electrode for the group of three LEDs 103 it covers. Each opening 111, for example, has a rectangular shape surrounding three LEDs 103 when viewed from above. The openings 111 form, for example, a grid when viewed from above, in which each square contains three LEDs 103.

[0053] Figure IC represents a structure obtained at the end of a further step of forming color converters 113R and 113G surmounting some LEDs 103.

[0054] 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. If 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 color converter 113G is, for example, intended to convert the blue light emitted by the underlying LED 103 into green light.In this case, each PIX pixel of the opto-electronic device includes a green sub-pixel, comprising the LED 103 surmounted by the color converter 113G, a red sub-pixel, comprising the LED 103 surmounted by the color converter 113R, and a blue sub-pixel, comprising the LED 103 without a color converter.

[0055] In the illustrated example, each color converter 113R, 113G covers the top 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 can further extend, as in the example illustrated in Figure IC, onto and in contact with portions of the conductive layer 109 located at the periphery of the LED 103.

[0056] 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 "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. As an alternative, at least one of the A and B sites of the perovskite materials of the color converters 113G and 113R may have an "A1" type configuration. X -!A2 X » and / or « B 1 y > ! B 2 y" and the X anion can deviate from the ideal coordination configuration, for example when the ions located in sites A and B undergo changes in their oxidation states.

[0057] Cation A is, for example, an organic cation, such as methylammonium, formamidinium, etc. Alternatively, cation A can be an inorganic cation, such as cesium, rubidium, or potassium. Furthermore, cation B is, for example, a lead, tin, etc. In the case of a halogenated perovskite material, anion X is a halide ion, such as chloride, bromide, or iodide.

[0058] Perovskite materials can exhibit either a "0D" or "2D" crystal structure, for example, with a composition containing the same elements as ABX3-type perovskite materials but with different composition ratios. For example, Cs4PbBr6 is a 0D-type perovskite material and CsPb2Br5 is a 2D-type perovskite material.

[0059] Furthermore, the perovskite material may contain 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 color converters.

[0060] 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 CsPbI3Br.

[0061] To fabricate the 113G and 113R color converters, a first layer of a first perovskite material, for example, the perovskite material of the 113G color converters, is deposited on the top face side of the structure shown in Figure IB and then partially removed, leaving only regions of the first layer at the desired locations for the 113G color converters. A second layer of a second perovskite material (the perovskite material of the 113R color converters, in this example) is then deposited on the top face side of the structure and then partially removed, leaving only regions of the second layer at the desired locations for the 113R color converters. The first and second perovskite layers are, for example, conformal layers. As an example, the steps of removing portions of the first and second layers leading to the The delineation of the 113G and 113R color converters is 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.

[0062] Figure 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 Figure IC.

[0063] The insulating layer 115 is, for example, designed to promote the reflection of electromagnetic radiation from the LEDs 103 onto the reflective layer 117. The insulating layer 115 also serves, for example, to protect the color converters 113G and 113R. As an example, the insulating layer 115 is made of a nitride, for example silicon nitride, or of an oxide, for example silicon oxide.

[0064] 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 aluminum, or of a metal alloy.

[0065] In the example shown, parts of the reflective layer 117 cover the sides of the LEDs 103.

[0066] Figure 1E represents a structure obtained after a subsequent etching step, for example an anisotropic etching, of the reflective layer 117.

[0067] At the end of this step, only parts of the reflective layer 117 coating the sides of the LEDs 103 are retained. These parts of the reflective layer 117 form, for example, reflective walls surrounding laterally the LEDs 103. In this example, the parts of the reflective layer 117 covering the upper faces of the LEDs 103 and the parts of the reflective layer 117 extending laterally between the LEDs 103 are removed.

[0068] As an example, the etching is of the RIE plasma type (from the English "Reactive Ion Etching"), for example a "spacer" type etching.

[0069] 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, can also be removed during this step.

[0070] Figure 1F represents a structure obtained after a subsequent step of deposition, on the upper face side of the structure of Figure 1E, of a planarization layer 119 and then of fixing, on the planarization layer 119, of a temporary support substrate 121, or handle.

[0071] In the example shown, the planarization layer 119 extends over and is in contact with the entire upper face of the structure in Figure 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 the electromagnetic radiation from the LEDs 103.

[0072] During this stage, optical cavities 123, laterally delimited by reflective walls 125, by For example, metallic walls can also be formed directly above each LED 103, as in the example shown in Figure 1F, using the planarization layer and / or additional layers. Alternatively, the optical cavities 123 can be omitted. In this case, the structure in Figure 1F lacks the reflective walls 125.

[0073] In the example shown, the temporary support substrate 121 is fixed to the upper face of the planarization layer 119 via a detachment layer 127.

[0074] Figure IG represents a structure obtained after a subsequent step of removing the support substrate 101.

[0075] In the example shown, the structure is reversed relative to the orientation of Figure 1F. The support substrate 101 is, for example, completely removed, as in the example illustrated in Figure IG. As an example, the support substrate 101 is removed by grinding.

[0076] Figure IG further illustrates a step in the formation, on the upper face of the structure, of a metal contact pad 129 for each of the LEDs 103 of the device. This contact pad is intended to be connected to, or to form, the anode electrode of the LED 103. The metal contact 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, additional metal contact pads 131, each intended to be connected to the cathode electrode(s) of the LEDs 103 belonging to the same pixel DIX, are also formed on the upper face of the structure. This corresponds to a case in which contact on the cathode electrodes is made collectively for the three LEDs 103 of each pixel DIX, with the metal contact pad 131 being in contact with the part of the conductive layer 109 coating the group of three LEDs 103 of the pixel DIX display of the opto-electronic device.

[0077] This example is not exhaustive. As an alternative, each LED 103 could be 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 re-establish contact with the cathode electrode of the LED 103.

[0078] 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 metal regions 129, 131 and insulating regions 133.

[0079] 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 deposited on the upper surface 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 to obtain a substantially flat upper surface.

[0080] Figure 1H shows a structure obtained after a subsequent step of forming trenches 135 extending vertically from the upper face of the structure in Figure IG 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 DIX of the display device. The trenches 135 can be formed by plasma etching, sawing, or any other suitable cutting method.

[0081] Figure II shows a structure obtained after a subsequent step of attaching elementary chips 136 to 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 electrically and mechanically connected to corresponding metal connection pads 129 of the elementary chips 136, and a plurality of metal connection pads 141, intended to be fixed and electrically and mechanically connected to corresponding metal connection pads 131 of the elementary chips 136. The transfer substrate 137, for example, has lateral dimensions strictly greater than those of the temporary support substrate 121.

[0082] 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 top 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.

[0083] During this step, the structure of Figure 1H is, for example, reversed 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.

[0084] Figure IJ shows a structure obtained after fixing the elementary chips 136 to the transfer substrate 137, following a subsequent step of detaching the elementary chips 136 from the temporary support substrate 121 and removing the latter. For example, the detachment of the elementary chips 136 is achieved by local peeling or through a mask using a laser beam focused on the peel layer 127 directly above each elementary chip 136 to be detached, or by mechanical peeling.

[0085] 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.

[0086] Figure 1K represents a structure obtained after fixing the elementary chips 136 opposite the metal connection pads 139 and 141 of the transfer substrate 137.

[0087] 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 Figure 1K).

[0088] Although this was not detailed in the figures II, IJ, and 1K, in order to avoid cluttering the drawing, the substrate 137 includes, for example, a control circuit for the LEDs 103. More specifically, the control circuit includes, for each LED 103 connected to the metal pad, the following components: 139 dedicated to LED 103, an elementary control cell comprising one or more transistors, for example thin-film transistors ("Thin-Film Transistor" - TFT), allowing control of the current flowing in LED 103 and / or the voltage applied to the terminals of LED 103.

[0089] The optoelectronic device in Figure 1K is, for example, part of a color image display screen. As an example, the optoelectronic device obtained by the process shown in Figures IA to 1K is a so-called "micro LED" display screen.

[0090] Figures IA to 1K illustrate a method used, for example, to create a large display device, such as a television, computer, smartphone, or tablet screen. Such a device comprises, for example, a plurality of elementary chips arranged, for example, in a matrix arrangement, on a single substrate. The elementary chips are mounted directly onto the substrate and connected to electrical connection elements on the substrate for control. Each chip, in the example shown, contains three LEDs 103. In this example, the LEDs 103 are individually controllable and define three emission sub-pixels, each designed to emit red, green, and blue light.

[0091] Figure 2A and Figure 2B illustrate, by schematic and partial side and cross-sectional views, successive stages of a manufacturing process for an optoelectronic device according to one embodiment.

[0092] Figure 2A represents a structure obtained after a step of fixing the structure of figure IG onto the upper face of a transfer substrate 237.

[0093] Although not detailed in Figure 2A to avoid cluttering the drawing, control circuits for the LEDs 103 of the opto-electronic device are, for example, pre-formed in the transfer substrate 237. As an example, the control circuits are made using CMOS technology (from the English "Complementary Metal-Oxide-Semiconductor"). The transfer substrate 237, for example, has lateral dimensions substantially equal to those of the temporary support substrate 121.

[0094] During this step, the structure of figure IG is for example reversed 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.

[0095] Alternatively, the cathode electrode can be common to all DIX pixels of the device. In this case, a single cathode contact is used, for example, at the periphery. This is equivalent, for example, to a structure analogous to that of Figure 2A in which the conductive layer 109 is unstructured, i.e., forms a continuous layer, and includes 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 DIX pixel matrix.

[0096] Figure 2B represents a structure obtained, after fixing the structure of Figure II on the transfer substrate 237, following a subsequent step of detachment of the temporary support substrate 121 and removal of the latter. As an example, the detachment is carried out by peeling using a laser beam focused on the peeling layer 127, or by mechanical peeling.

[0097] 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 PIX pixels are simultaneously transferred from the temporary support substrate 121 to the transfer substrate 237.

[0098] Unlike the process described previously in relation to Figures IA to 1K, the process described above in relation to Figures 2A and 2B is used, for example, to create monolithic microdisplays. One advantage of this process 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, green, and blue light.

[0099] As an example, the device obtained by the process of Figures 2A and 2B is a micro-screen microled display.

[0100] Figure 3A, Figure 3B and Figure 3C illustrate, by schematic and partial side and cross-sectional views, successive stages of a manufacturing process for an opto-electronic device according to one embodiment.

[0101] Figure 3A represents a structure obtained after a deposition step, on the upper face side of the structure in Figure IA, of the conductive layer 109.

[0102] After deposition, the conductive layer 109, for example, covers the entire upper surface of the structure in Figure IA. Unlike the structure in Figure IB, the conductive layer 109 of the structure in Figure 3A lacks the openings 111.

[0103] Figure 3B represents a structure obtained after a subsequent step of forming opaque walls 301 laterally surrounding each LED 103. As an 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.

[0104] Although not shown in Figure 3B in order to avoid overloading the drawing, the vertical surfaces of opaque walls 301 can be coated with a reflective layer, for example similar or identical to layer 117.

[0105] Figure 3C represents a structure obtained after a subsequent deposition step, on the upper face side of the structure of Figure 3B, of the planarization layer 119 and formation of the color converters 113G and 113R.

[0106] 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.

[0107] 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 Figure 3C, the entire surface delimited laterally by the opaque wall 301 surrounding the underlying LED 103.

[0108] Figure 4 illustrates, by schematic and partial side and cross-sectional views (A), (B) and (C), a step in a manufacturing process of an opto-electronic device according to an embodiment.

[0109] View (A) shows a 401G structure obtained by deposition, on the upper face of a structure similar or identical to that of Figure 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. More precisely, the color converter 113G is located on and in contact with the upper face of the conductive layer 109.

[0110] View (B) shows a 401R structure obtained after a deposition step, on the upper face side of a structure similar or identical to that of Figure 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. More precisely, the color converter 113R is located on and in contact with the upper face of the conductive layer 109.

[0111] View (C) represents a 401B structure similar or identical to that in Figure 3A.

[0112] Figure 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 Figure 4 according to one embodiment.

[0113] Figure 5 more precisely represents a structure obtained after fixing, on the transfer substrate 137, elementary chips 536G, 536R and 536B from respectively structures 401G, 401R, and 401B of Figure 4. The fabrication of 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 elementary chips 136 from the structure in Figure IC. Furthermore, the transfer is, for example, performed in a manner analogous to what was described above in relation to Figures II to 1K in the case of chips 136.

[0114] In the structure of Figure 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 the elementary chips 536G, 536R and 536B respectively. Each S-PIX sub-pixel can contain any number, greater than or equal to one, of nanowires or microwires.

[0115] Alternatively, the optoelectronic device can be made from three monochrome microdisplays, 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 microdisplays to reconstruct a color image is, for example, achieved by means of a component known by the English name "combiner cube".

[0116] Figure 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 one embodiment.

[0117] 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 without a 113R or 113G color converter coating. This corresponds, for example, to a case where 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 aluminum-gallium nitride (AlGaN) based, for wavelengths below 350 nm.

[0118] In the example shown, for each group of three LEDs 103 coated by 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 optoelectronic device includes a green sub-pixel, comprising the LED 103 surmounted by the color converter 113G, a red sub-pixel, comprising the LED 103 surmounted by the color converter 113R, and a blue sub-pixel, comprising the LED 103 surmounted by the color converter 113B.

[0119] The implementation of the 113B color converters is, for example, analogous to that of the 113G and 113R color converters. The 113B color converters can be performed before, between or after the 113G and 113R color converters.

[0120] As an example, 113B color converters are in CsPbCl3.

[0121] Further steps similar to those previously described in relation to figures 1D to 1K are then implemented, for example, to create an optoelectronic device from the structure of figure 6.

[0122] In this process, each LED 103 is fitted with a color converter 113R, 113G, or 113B. This allows for light sources with virtually identical directivity, apart from manufacturing variations. It also results in improved homogeneity. Furthermore, perovskite materials exhibit better absorption in the ultraviolet than in the visible spectrum. The optoelectronic device obtained using the process described in relation to Figure 6 thus has a higher conversion rate than the optoelectronic device obtained using the process described in relation to Figures IA at 1K.

[0123] Figure 7A and Figure 7B illustrate, by schematic and partial side and cross-sectional views, successive stages of a manufacturing process for an optoelectronic device according to one embodiment.

[0124] Figure 7A represents a structure analogous to that previously described in relation to Figure IJ. Unlike the structure in Figure IJ, the reflective layer 117 has not been removed above the LEDs 103 in the structure of Figure 7A. This is equivalent, for example, to omitting the step in Figure 1E in the process described above in relation to Figures IA to 1K.

[0125] In the case of Figure 7A, elementary chips 736 analogous to elementary chips 136 are shown on the transfer substrate 137. In this case, the transfer substrate 137 is transparent to the visible light emitted by the LEDs 103.

[0126] Figure 7B represents a structure obtained after fixing the elementary chips 736 opposite the metal connection pads 139 and 141 of the transfer substrate 137.

[0127] In the illustrated example, the DIX pixels of the opto-electronic device are intended to emit light through the carrier substrate 137 (downwards, in the orientation of Figure 7B).

[0128] One 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 helps to reduce the risk of damage to the color converters 113R and 113G.

[0129] Figure 8A and Figure 8B illustrate, by schematic and partial side and cross-sectional views, successive stages of a manufacturing process for an optoelectronic device according to one embodiment.

[0130] Figure 8A represents a structure analogous to that previously described in relation to Figure 1D.

[0131] Unlike the structure in Figure 1D, the structure in Figure 8A lacks the reflective layer 117. Furthermore, the color converters 113R and 113G have a greater thickness in the structure in Figure 8A than in the structure in Figure 1D.

[0132] 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.

[0133] Figure 8B represents a structure analogous to that previously described in relation to Figure 1F obtained, from the structure of Figure 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 Figure 8A, of the planarization layer 119 and then fixing, on the planarization layer 119, of the temporary support substrate 121.

[0134] Steps analogous to those described above in relation to figures IG to 1K can then be implemented from the structure of figure 8B to form an opto-electronic device.

[0135] One advantage of the process described above in relation to figures 8A and 8B is that it does not involve steps of deposition and structuring of a mirror layer coating the LEDs 103. This simplifies the realization of the opto-electronic device compared to the process described previously in relation to figures IA to 1K.

[0136] Figure 9 illustrates, by schematic and partial side and cross-sectional views (A), (B), (C) and (D), several variants of a layer deposition step in a perovskite material according to one embodiment.

[0137] 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).

[0138] View (B) represents a structure obtained, starting from the structure of view (A), after a subsequent thinning step of the portion of the color converter 113R covering the upper surface of the LED 103. As an example, the thinning is achieved by polishing chemical and mechanical polishing (CMP).

[0139] 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 parts 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 parts of the color converter 113R covering the sides and the top face of the LED 103 remain.

[0140] 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 similar or identical to that described above in relation to view (C).

[0141] Although not detailed in the figures, non-conformal deposition techniques can result in the LEDs 103 being coated with a layer of perovskite material intended to form each color converter 113R, 113G of the optoelectronic device, resulting in a non-constant thickness. In particular, inhomogeneities may appear after the layer is depositioned, especially in the portions of the perovskite layer coating the sides of the LEDs 103. However, such inhomogeneities do not disrupt the operation of the color converters 113R and 113G. Specifically, these inhomogeneities do not degrade, or only slightly degrade, the extraction and conversion of the light produced by the LEDs 103.

[0142] Furthermore, the perovskite material layer used to create each 113R color converter, 113G, for example, has a thickness e approximately equal to the wavelength of the light emitted by LED 103 divided by the refractive index n pk of the layer made of perovskite material (e = X / n pk ), or approximately equal to an integer multiple a, greater than or equal to two, of the wavelength divided by the refractive index n pk (e = aX / n pkVarious 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 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.

[0143] Figure 10A, Figure 10B and Figure 10C 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.

[0144] Figure 10A represents a structure analogous to that previously described in relation to Figure 1D.

[0145] Unlike the structure in Figure 1D, the structure in Figure 10A lacks the color converters 113R and 113G. The structure in Figure 10A is obtained, for example, by depositing the insulating layer 115 and then the reflective layer 117 on the upper face side of the structure in Figure 1B.

[0146] Figure 10B represents a structure obtained after a subsequent etching step, for example a anisotropic engraving, of the reflective layer 117 of the structure of figure 10A.

[0147] 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.

[0148] The step to obtain, from the structure of figure 10A, the structure of figure 10B is for example implemented in a similar or identical way to the step to form the structure of figure 1E from the structure of figure 1D.

[0149] Figure 10C represents a structure obtained at the end of a subsequent step of forming the color converters 113R and 113G.

[0150] 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.

[0151] Steps analogous to those described above in relation to Figures 1F to 1K can then be implemented from the structure of Figure 10C to form an opto-electronic device.

[0152] One advantage of the optoelectronic devices described above is that the use of 113R and 113G color converters made of perovskite material results in superior efficiency, reliability, and lifespan. to that of existing optoelectronic devices. Furthermore, the manufacturing processes described above are temperature stable. They also allow working on entire wafers before the transfer step onto the substrate containing the TFT transistors.

[0153] Another advantage of the optoelectronic devices described above is that they exhibit a higher absorption coefficient, for example of about 10 6 cm -1 against approximately 10 3 cm -1 for analogous devices but incorporating quantum dot color converters. This allows the color converters to have much smaller thicknesses, for example, around 500 nm compared to around 8 to 10 pm for quantum dot color converters, thus making them easier to structure and enabling smaller pixel pitches.

[0154] 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 them. In particular, the process described in relation to Figure 6, in which LEDs 103 emit UV radiation and are used in combination with three color converters 113R, 113G, and 113B in 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.

[0155] 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 to the reading of the present description, to the processes described in relation to the other figures.

[0156] Although this description uses as an example the case of optoelectronic devices with light-emitting diodes (LEDs) comprising microwires or nanowires, the embodiments described are not limited to this case and apply more generally to any type of optoelectronic device with LEDs, for example, optoelectronic devices with LEDs of micrometer or nanometer size and of conical or truncated pyramidal shape. Even more generally, a person skilled in the art is able, based on the indications in this description, to adapt the embodiments described to any type of optoelectronic device comprising LEDs, regardless of the dimensions of these LEDs.

[0157] 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 specifications 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 located on and in contact with a part of a conductive layer (109) located on and in contact with the lateral and upper faces of the light-emitting diodes (103).

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 made of 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. A 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. Method for manufacturing an optoelectronic 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. 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), then a step of removing the temporary support substrate (121).

13. 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. 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), 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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