Optoelectronic device with reduced optical crosstalk

Abstract

Title: Optoelectronic device with reduced optical crosstalk The invention relates to an optoelectronic device (1) comprising a matrix of diodes (100a, 100b, 100c, 100d, 100e) based on a first material. A first diode (100a) and a second diode (100b) of the matrix are respectively surmounted by a first convex lens (200a) and a second convex lens (200b). They are separated by a wall (300) having an upper face (301) in contact with the two lenses (200a, 200b). The latter are at a distance from each other, and the wall comprises a stopping layer (310) based on a stopping material extending from a portion (301*) of the upper face of the wall not being covered by either the first convex lens or the second convex lens. For at least one etch chemistry of the first material, the etch selectivity between the first material and the stop material is greater than or equal to 3:1. Figure for abstract: Fig.1K

Description

Title of the invention: Optoelectronic device with reduced optical crosstalk Technical field

[0001] The present invention relates to the field of microelectronics and optoelectronics technologies, in particular the manufacture of arrays of light-emitting or light-receiving diodes such as LEDs (from the English "Light-Emitting Diode", translating into French as electroluminescent diode), and more particularly micro-LEDs. It finds particularly advantageous but non-limiting application in micro-LED-based display systems, or optical communication systems. STATE OF THE ART

[0002] Diodes are theoretically a very efficient converter of electrical energy into light energy, or vice versa. They therefore constitute a promising technology to replace conventional light sources and detectors: high efficiency diodes would allow considerable energy savings accompanied by other advantages such as robustness, high compactness, long life and good control of color rendering and light intensity.

[0003] One of the crucial issues in the field of diodes concerns, for emitting diodes, the extraction of the emitted light, and for receiving diodes, the detection of the received light. This extraction or detection is in fact limited by the often very high refractive index of the material constituting the diodes, typically GaN. In the case of emitting diodes, the emitted light remains trapped in the diode by internal reflection. If nothing is done to improve the extraction, only a few percent of the emitted light is actually extracted from the diode.

[0004] Solutions developed in the field of millimeter diodes have made it possible to obtain satisfactory results. However, these solutions are often difficult or even impossible to implement on micrometer diodes. For example, the manufacture of diodes with an inverted pyramid shape, whose geometry optimizes light extraction, is more complex to achieve on a micrometer scale. The option of integrating a network of photonic crystals is not a serious avenue on the micrometer scale because too few diffracting elements can be integrated on this scale to significantly improve extraction. Finally, it is not possible to use structured substrates because the characteristic dimensions of their patterns are incompatible with micrometer diode networks.

[0005] A first solution applicable to micrometric diodes consists of texturing the surface of the diode in order to break the conservation of the angle at reflection. The protrusions created by the texturing act as diffracting elements, which effectively improve light extraction. However, this technique has the significant drawback of causing the diode to lose its directivity, which is particularly disadvantageous when it is coupled to an optical system with reduced numerical aperture.

[0006] A second solution consists of the formation of a microlens surmounting the diode. This solution not only increases light extraction but also improves the directivity of the diode.

[0007] Diodes topped with microlenses based on a polymer or dielectric material are described in Eun Kyu Kang et al, IEEE PHOTONICS TECHNOLOGY LETTERS, VOL. 25, NO. 12, JUNE 15, 2013. The publication Dongwoo Kim, Japanese Journal of Applied Physics Vol. 44, No. 1, 2005, pp. L 18-L 20 particularly shows the effectiveness of GaN microlenses in increasing light extraction.

[0008] However, it has been noted that an optical crosstalk phenomenon (commonly referred to as "optical crosstalk") occurs between the LEDs described in these documents when they are networked. This phenomenon is very detrimental since it causes a reduction in the contrast ratio between pixels.

[0009] An objective of the present invention is therefore to reduce the phenomenon of optical cross-talk between diodes of the same network surmounted by lenses. Preferably, the solution will make it possible to maintain satisfactory optical properties, in particular in terms of light extraction and directivity. SUMMARY

[0010] To achieve this objective, a first object of the invention relates to an optoelectronic device comprising: a. a substrate having an upper face extending mainly parallel to a plane called the transverse plane, b. a matrix of light-emitting or light-receiving diodes arranged on the upper face of the substrate, a first diode of the matrix being surmounted by a first convex lens and a second diode of the matrix being surmounted by a second convex lens, the first convex lens and the second convex lens being based on a first material, the first diode and the second diode being separated, in the transverse plane, by a wall having an upper face in contact with each of the first lens and the second lens.

[0011] The first lens and the second lens are spaced apart from each other. The wall preferably comprises a stop layer extending at least from a portion of the upper face of the wall not being covered by the first convex lens or by the second convex lens, the stop layer being based on a material, called a stop material. Furthermore, the first material and the stop material are preferably such that, for at least one etching chemistry of the first material, the etching selectivity between the first material and the stop material is greater than or equal to 3:1, and preferably greater than or equal to 4:1.

[0012] The first lens and the second lens make it possible to improve light extraction in the case of emitting diodes and light detection in the case of receiving diodes. Their convex shape is ideal for giving the device good light directivity.

[0013] Furthermore, the fact that the first and second diodes are separated by the wall and that the first lens and the second lens are at a distance from each other makes it possible to avoid any optical transmission from one diode to the other. No residual layer which could potentially guide light from one diode to the other creates material continuity between the first diode and the second diode. The two diodes are thus much better optically isolated from each other.

[0014] The invention therefore makes it possible to reduce or even eliminate the optical crosstalk phenomenon between two neighboring diodes, while maintaining satisfactory optical performance, for example in terms of light extraction and directivity of the source.

[0015] A second object of the invention relates to a method of manufacturing an electronic device comprising the following steps: a. Provide a stack comprising: i. a substrate having an upper face extending mainly parallel to a plane called the transverse plane, ii. a matrix of light-emitting or light-receiving diodes arranged on the upper face of the substrate, a first diode of the matrix and a second diode of the matrix being separated, in the transverse plane, by a wall having an upper face, the wall comprising a stop layer extending at least partially from at least a portion of the upper face of the wall, the stop layer being based on a material called a stop material, iii. a continuous layer based on a first material, covering at least the first diode, the upper face of the wall and the second diode, b. Forming in the continuous layer a first convex lens overlying the first diode and a second convex lens overlying the second diode, the first convex lens and the second convex lens being distance from each other, the formation of the first convex lens and the second convex lens comprising selective etching of the first material with respect to the stopping material, the etch selectivity between the first material and the stopping material preferably being greater than or equal to 3:1, and preferably greater than or equal to 4:1.

[0016] The advantages of the device explained above also apply to the method according to the invention. The characteristics of the stop layer also allow the formation of the lenses to be better controlled than in the prior art. BRIEF DESCRIPTION OF THE FIGURES

[0017] The aims, objects, as well as the characteristics and advantages of the invention will emerge more clearly from the detailed description of an embodiment thereof which is illustrated by the following accompanying drawings in which:

[0018] [Fig.1A] Figures 1A to 11L illustrate a first embodiment of the manufacturing method according to the invention in which the stop layer is metallic.

[0019] [Fig.lB]

[0020] [Fig. 1C] Figures 1C, 1E, 1G, 1H, 1I, 1J and 1K relate to a case in which the passivation layer extends over the entire height of the sides of the diodes.

[0021] [Fig. 1D] Figures 1D, 1F, and 11 refer to a case in which the passivation layer extends over only a portion of the height of the sides of the diodes.

[0022] [Fig.lE]

[0023] [Fig.lF]

[0024] [Fig.lG]

[0025] [Fig.lH]

[0026] [Fig. II]

[0027] [Fig.lJ]

[0028] [Fig.lK]

[0029] [Fig. IL]

[0030] [Fig.lM] [Fig.lM] represents the device according to the invention comprising a matrix of five diodes and convex lenses.

[0031] [Fig.2A] Figures 2A to 2K illustrate a second embodiment of the manufacturing method according to the invention in which the barrier layer is dielectric.

[0032] [Fig.2B] Figures 2B, 2D, 2F, 2H and 2J show an example in which two neighboring diodes share the same cathode.

[0033] [Fig.2C] Figures 2C, 2E, 2G, 21 and 2K show an example in which two neighboring diodes have distinct cathodes.

[0034] [Fig.2D]

[0035] [Fig.2E]

[0036] [Fig.2F]

[0037] [Fig.2G]

[0038] [Fig.2H]

[0039] [Fig.2I]

[0040] [Fig.2J]

[0041] [Fig.2K]

[0042] [Fig.3] [Fig.3] represents a variant of integration of the cathode common to the two neighboring diodes.

[0043] [Fig.4A] Figures 4A to 4D illustrate a method of manufacturing secondary walls intended to separate the convex lenses of the device according to the invention.

[0044] [Fig.4B]

[0045] [Fig.4C]

[0046] [Fig.4D]

[0047] [Fig.4E] [Fig.4E] is a top view of the device according to the invention when the latter comprises secondary walls separating the convex lenses.

[0048] The drawings are given as examples and are not limiting of the invention. They constitute schematic representations of principle intended to facilitate the understanding of the invention and are not necessarily on the scale of practical applications. In particular, the dimensions are not representative of reality. DETAILED DESCRIPTION

[0049] Before beginning a detailed review of embodiments of the invention, optional features which may possibly be used in combination or alternatively are set out below:

[0050] According to a preferred example, the first diode, the second diode, the first convex lens and the second convex lens are based on the same material, for example GaN. This avoids any difference in refractive index between the diodes and the convex lenses. This makes it possible to limit the refraction of light at the interface between the diodes and the lenses. The extraction is thus better than in the case of convex lenses based on a material different from that of the diodes (SiN or a polymer for example). Preferably, the first diode, the second diode and the convex lenses have been formed in the same layer, preferably previously formed by epitaxy. This makes it possible to avoid the presence of an interface between the diodes and the lenses, to avoid any light refraction between these elements and therefore to improve the light extraction.

[0051] According to a preferred example, the first diode and the second diode each have a flank defined by the interface of said diode with the wall, the device further comprising an electrically insulating element extending from the flank of each of the first diode and the second diode.

[0052] According to one embodiment, the device further comprises a second electrical contact in electrical continuity with the first convex lens and with the second convex lens.

[0053] According to one embodiment, the device further comprises a first metal element in electrical continuity with the first convex lens and a second metal element in electrical continuity with the second convex lens, the first metal element and the second metal element being electrically isolated from each other. This makes it possible to single out the control of the two diodes.

[0054] According to one embodiment, the stop layer is based on a metallic material. By using a metallic material for the stop layer, this layer is given, in addition to the function of a stop layer for the formation of the lenses, a function of resuming contact of the diodes. This greatly simplifies the structure and the manufacture of the device.

[0055] According to a preferred example, when the stop layer is based on a metallic material, the stop layer extends from the upper face of the wall under each of the first lens and the second lens, preferably from the entire extent of the upper face of the wall. This makes it possible to make electrical contact between the stop layer and the lenses, which is advantageous for making electrical contact resumption of the diodes.

[0056] According to one embodiment, the barrier layer is based on a dielectric material. The etching selectivity between materials commonly used for diodes and lenses and dielectric materials is important. The thickness of the barrier layer can therefore be reduced compared to other materials. This saves space and therefore limits the size of the device.

[0057] According to a preferred example, when the barrier layer is based on an insulating material, a portion of the barrier layer is part of the electrically insulating element.

[0058] According to an advantageous embodiment, the device further comprises a secondary wall extending above the wall, between the first lens and the second lens, the secondary wall extending at least as far as the first convex lens and the second convex lens, preferably beyond the first convex lens and the second convex lens, away from the upper face of the wall in a third direction perpendicular to the transverse plane, the secondary wall being at a distance from the first lens and the second lens. This secondary wall makes it possible to absorb or reflect the light emitted by emitting diodes and which, in the absence of this secondary wall, would be transmitted via the air or the filling material above the diodes. The secondary wall thus makes it possible to reduce the phenomenon of optical cross-talk which can occur in the air or in any material covering the diode matrix.

[0059] According to an advantageous embodiment, each convex lens defines a convex surface, said convex surface corresponding to a portion of the external surface of a sphere of diameter D2Oo, each of the first diode and the second diode having a dimension DiOo, DiOo being measured in projection in the transverse plane, perpendicular to the projection of the wall in the transverse plane, with D2Oo >2*Dloo- H has been shown that this dimensioning is optimal for maximizing the extraction (or detection) coefficient. The size caused by a lens of such a dimension (i.e. with D2OO>2*DiOo) is moreover entirely reasonable compared to the dimensions of the underlying diode. Furthermore, the center of the sphere is preferably located at the same level in the third direction as the upper face of the wall.

[0060] According to an advantageous embodiment, the first convex lens and the second convex lens are surmounted by an anti-reflection layer. The anti-reflection layer makes it possible to avoid internal refraction of the light emitted by the diodes, in the case of emitting diodes, or refraction towards the medium located above the diodes, in the case of receiving diodes. It therefore makes it possible to improve light extraction (or light detection).

[0061] According to one embodiment of the method according to the invention, the provision of the stack comprises the following steps: a. Providing an initial stack comprising: i. The continuous layer, ii. A continuous active layer, iii. The substrate, b. Carry out a so-called singularization etching from a lower face of the substrate opposite its upper face into the substrate, so as to form the first diode and the second diode in the continuous active layer, and to form a trench between the first diode and the second diode, c. Form the stop layer in the trench.

[0062] According to one embodiment of the method according to the invention, the first diode and the second diode each have a flank defined by the interface of said diode with the trench, the method further comprising the following steps: a. Forming in the trench an electrically insulating element extending from the flanks of the first diode and the second diode, b. At least partially filling the trench with an electrically conductive material.

[0063] “Selective etching with respect to” or “etching exhibiting selectivity with respect to” means etching configured to remove a material A or a layer A with respect to a material B or a layer B, and having an etching rate of material A greater than the etching rate of material B. Selectivity is the ratio between the etching rate of material A and the etching rate of material B. The selectivity between A and B is noted SA:B.

[0064] The present patent application can be applied to both a photoreceiving diode and a light-emitting diode (as well as to networks of such diodes). The term "diode" is therefore understood indifferently as "photoreceiving diode" or "light-emitting diode". In the present patent application, the terms "light-emitting diode", "light-emitting diode" and "LED" are used synonymously. A "diode" can also be understood as a "micro-diode". A "micro-diode" is a diode whose dimensions do not exceed 1 mm (1 mm = 103 μm), and typically not 10 μm (10 μm = 105 μm).

[0065] Two elements are said to be “electrically connected” when they are each in contact with the same continuous electrical connection element having an electrical conduction preferably greater than 108 S / m.

[0066] It is specified that, in the context of the present invention, the terms "on", "overcomes", "covers", "underlying", "facing" and their equivalents do not necessarily mean "in contact with". Thus, for example, the deposition, transfer, bonding, assembly or application of a first layer on a second layer does not necessarily mean that the two layers are directly in contact with each other, but means that the first layer at least partially covers the second layer by being either directly in contact with it or by being separated from it by at least one other layer or at least one other element.

[0067] A layer may also be composed of several sub-layers of the same material or of different materials.

[0068] A substrate, a layer, a device, “based” on a material M, is understood to mean a substrate, a layer, a device comprising this material M only or this material M and possibly other materials, for example alloying elements, impurities or doping elements. Thus a material based on an IILN material may comprise an IILN material with added dopants.

[0069] A reference frame, preferably orthonormal, comprising the axes X, Y, Z is represented in figures 1A, 1K, 2A, 3 and 4A. This reference frame is applicable by extension to the other figures.

[0070] In the present patent application, we will preferably speak of thickness for a layer and of height for a structure or a device. The height is taken perpendicular to the transverse plane XY. The thickness is taken in a direction normal to the main extension plane of the layer. Thus, a layer typically has a thickness along Z, when it extends mainly along the transverse plane XY, and a projecting element, for example a trench, has a height along Z. The relative terms “on”, “under”, “underlying” refer preferentially to positions taken along the Z direction.

[0071] The terms “substantially”, “approximately”, “of the order of” mean “to within 10%, preferably to within 5%”.

[0072] Optoelectronic device according to the invention

[0073] The device according to the invention will now be described with reference to FIGS. 1K, 11I, 11M, 2J, 2K, 3, 4D and 4E.

[0074] The device 1 according to the invention comprises a substrate 10' having an upper face 11' extending mainly in a plane parallel to a transverse plane XY. The transverse plane XY is defined by a first direction X and a second direction Y. The substrate 10' comprises or even corresponds to the dielectric layer 10 which will be described further with reference to the method according to the invention.

[0075] The device 1 further comprises a matrix of diodes 100a, 100b, 100c, 100d, 100e arranged on the upper face 11' of the substrate 10'. A matrix of five diodes 100a, 100b, 100c, 100d, 100e is shown in [Fig.lM]. The other figures only illustrate two diodes 100a, 100b, called first diode 100a and second diode 100b, but it is understood that the characteristics described below with reference to these two diodes 100a, 100b and to the elements surrounding them can perfectly apply to the other diodes of the matrix, if the device 1 comprises more than two diodes.

[0076] The diodes 100a, 100b are based on a semiconductor material such as GaN. Each diode 100a, 100b comprises an active region 110a, 110b being the site of radiative recombinations of electron-hole pairs making it possible to obtain or absorb light radiation. An active region 110a, 110b typically comprises a plurality of quantum wells, for example formed by layers based on GaN, InN, InGaN, AlGaN, AIN, AlInGaN, GaP, AlGaP, AlInGaP, AlGaAs, GaAs, InGaAs, AlIlAs, or a combination of several of these materials. Each diode 100a, 100b also comprises a P-doped region 120a, 120b, located above the active region 110a, 110b, and making it possible to generate hole-type carriers, and an N-doped region 130a, 130b located above the active region 110a, 110b, and making it possible to generate electron-type carriers.

[0077] The device 1 preferably comprises a first electrode 15a, 15b under each diode 100a, 100b. The first electrodes 15a, 15b are typically at least partially included in the substrate 10'. Each of the first electrodes 15a, 15b may be in contact with an underlying first metal pad 16a, 16b. The first electrodes 15a, 15b may for example be copper-based. The first metal pads 16a, 16b may for example be copper-based.

[0078] Each first electrode 15a, 15b is electrically connected to the diode 100a, 100b which overcomes it when the device 1 is functional. The first electrodes 15a, 15b may be separated from the diodes 100a, 100b, and in particular from the layer 120a, 120b by one or more conductive layers, such as for example a secondary mirror layer 63, a secondary metal layer 61 and the contact layer 30, which may itself be composed of a primary contact layer 30' and a primary mirror layer 30”.

[0079] Each of the diodes 100a, 100b is surmounted by a convex lens 200a, 200b. The assembly consisting of a diode 100a, 100b and the convex lens surmounting it 200a, 200b is designated module 1000a, 1000b.

[0080] The convex lenses 200a, 200b are preferably made from the same material as the diodes 100a, 100b. Advantageously, each diode 100a, 100b and the convex lens 200a, 200b surmounting it have been formed simultaneously, for example during the same epitaxial growth step. Each module 1000a, 1000b thus preferably forms a continuous layer. In other words, preferably, no interface is present between each diode 100a, 100b and the convex lens 200a, 200b surmounting it.

[0081] The first diode 100a and the second diode 100b are separated in the transverse plane XY by a wall 300. The wall 300 has an upper face 301 extending preferentially in a plane parallel to the transverse plane XY. It also has flanks 303 extending at least partially against the diodes 100a, 100b. The wall 300 may extend partially into the substrate 10'.

[0082] Each of the first convex lens 200a and the second convex lens 200b extends above the wall 300. These two convex lenses 200a, 200b are in contact with the upper face 301 of the wall 300. The two convex lenses 200a, 200b are entirely at a distance from each other. In other words, the first convex lens 200a and the second convex lens 200b are not in contact. They do not touch each other at any point. In particular, a portion 301* of the upper face 301 of the wall 300 is not surmounted by either the first convex lens 200a or the second convex lens 200b.

[0083] The wall 300 comprises in particular a stop layer 310. This stop layer 310 extends at least from the portion 301* of the upper face 301 of the wall 300 not being covered by the first lens 200a nor by the second lens 200b.

[0084] The barrier layer 310 may be based on different types of materials.

[0085] According to a first example, the barrier layer 310 is based on a metallic material. This is particularly the case in the embodiments illustrated in FIGS. 1K, 11K, 11M, 3 and 4D. The metallic material may for example be chosen from TiN, AlSi and indium tin oxide (commonly referred to as ITO). The metallic barrier layer 310 may also be composed of an em stacking of layers of several metallic materials, for example an AlSi / TiN stack. In this last example, the metallic stop layer 310 may optionally comprise a Ti bonding film or an ITO contact film.

[0086] According to a second example, the barrier layer 310 is based on a dielectric material. This is particularly the case in the embodiments illustrated in FIGS. 2J and 2K. The dielectric material may for example be chosen from the following materials: SiO2, SiN, SiON.

[0087] Whatever the material chosen for the stop layer 310, called the stop material, and whatever the material forming the convex lenses 100a, 100b, called the first material, for at least one etching chemistry of the first material, the etching selectivity between the first material and the stop material is preferably greater than or equal to 3:1, preferably greater than or equal to 4:1.

[0088] Examples of possible first material and stop material pairs as well as associated etching chemistries are given further on in the description of the method according to the invention. The dimensions of the stop layer 310 are also described in more detail further on in the description of the method according to the invention.

[0089] In addition to separating the diodes 100a, 100b, the wall 300 advantageously has the function of allowing electrical contact to be reestablished between the diodes 100a, 100b. Thus, the wall 300 advantageously comprises at least one electrically conductive element intended to be electrically connected, when the device is in operation, to at least one of the convex lenses 200a, 200b. It will appear in the different embodiments described below that the two diodes 200a, 200b can be electrically connected to a common electrically conductive element or to separate electrically conductive elements.

[0090] The device 1 further advantageously comprises an electrically insulating element at least partially separating the diodes 100a, 100b from the electrically conductive element(s). This electrically insulating element extends for example from the flank 103a, 103b of each diode 100a, 100b towards a central region of the wall 300. In other words, the electrically insulating element extends from the flank 103a, 103b of each of the first diode 100a and the second diode 100b and in a direction perpendicular to this flank 103a, 103b. The different shapes that can be taken by this electrically insulating element will appear in the examples presented below.

[0091] Several examples of the device 1 will now be described. These examples differ from each other in particular by the structure of the wall 300.

[0092] A first example of the device 1 will first be described with reference to [Fig. 1K]. In this example, the wall 300 comprises a metallic stop layer 310. Advantageously, this layer 310 extends not only from the portion 301* not covered with the upper face 301 of the wall 300 but also from other portions of this face 301, and is therefore in contact with the convex lenses 200a, 200b. Thus, a part of the layer 310 is formed by the portion 301* and at least a portion of the rest of the upper face 301 of the wall 300. This layer 310 extends towards a central region of the wall 300. Thanks to this, the stop layer 310 is electrically connected to the diodes 100a, 100b. Preferably, as illustrated in [Fig. 1K], the barrier layer 310 extends from the entirety of the upper face 301 of the wall 300. The barrier layer 310 extends towards a central region of the wall 300. This makes it possible to maximize the electrical contact recovery area by the barrier layer 310.

[0093] The wall 300 further comprises a main metal layer 350. This main metal layer 350 is the electrically conductive element mentioned above. It forms part of the electrode connected to the two convex lenses 200a, 200b, via the contact layer 310.

[0094] The main metal layer 350 may be in contact with an underlying second metal pad 17. The main metal layer 350 may for example be copper-based. The second metal pad 17 may for example be copper-based.

[0095] The main metal layer 350 typically has an upper face 351 parallel to the upper face 301 of the wall 300. It also has sides 353, for example perpendicular to its upper face 301.

[0096] The metallic barrier layer 310 may cover, for example entirely, the upper face 351 and the sides 353 of the main metallic layer 350. It may be separated from the main metallic layer 350 by one or more conductive layers, such as for example a layer called a mirror layer 330 based on a metallic material such as AlSi. The mirror layer 330 preferably also covers the upper face 350 and the sides of the main metallic layer 350.

[0097] The wall 300 further comprises a passivation layer 320 extending from each of its sides 303 towards the main metal layer 350, and typically towards the metal stop layer 310. The passivation layer 320 is based on an electrically insulating material. It may for example be based on one of the following materials: A12O3, SiN, AIN, or a combination thereof. It makes it possible to electrically isolate the diodes 100a, 100b in the transverse plane XY.

[0098] In the example illustrated in [Fig. 1K], the passivation layer 320 extends as much along the third direction Z as the stop layer 310. In other words, it completely covers the sides 313 of the stop layer 310. It is thus flush with the upper face 301 of the wall 300.

[0099] A second example of the device 1 is illustrated in [Fig.11]. This example differs from the first in that the passivation layer 320 is set back along the third direction Z relative to the stop layer 310. It is also set back relative to the main metal layer 350. In other words, in this example, the passivation layer 320 does not extend over the entire height of the sides 303. Thus, the sides 313 of the metal stop layer 310 are partially in contact with the modules 1000a, 1000b.

[0100] In these first two examples, the electrically insulating element comprises, or even consists of, the passivation layer 320.

[0101] A third example of the device 1 will now be described with reference to [Fig.2J]. In this example, the wall 300 comprises a dielectric barrier layer 310. In order to ensure the electrical connection of the modules 1000a, 1000b at the upper face 301 of the wall 300, the barrier layer 310 does not extend from the entirety of this upper face 301. As illustrated in [Fig.2J], typically, the barrier layer 310 forms a discontinuous layer and thus comprises several portions, one of which extends at least partially from the portion 301* not covered by the lenses 200a, 200b. The barrier layer 310 extends towards a central region of the wall 300. This portion is designated barrier portion 310*. It is also conceivable that the barrier layer 310 is continuous and only comprises the barrier portion 310*.

[0102] The wall 300 comprises, as in the first example, a main metal layer 350. This main metal layer 350 is electrically connected on the one hand to the first lens 200a and on the other hand to the second lens 200b. The main metal layer 350 thus typically comprises a first protuberance 350a' and a second protuberance 350b', both electrically conductive. These two protuberances 350a', 350b' are separated, over at least part of their height in the third direction Z, by the stop portion 310*.

[0103] Again, the main metal layer 350 may be in contact with an underlying second metal pad 17. The second metal pad 17 is then electrically connected to both the first lens 200a and the second lens 200b. In this example, the electrical contact resumption at the wall 300 of the modules 1000a, 1000b is therefore done in a common manner.

[0104] The main metal layer 350 has flanks 353 which can be covered with a metal layer 340 and / or a mirror layer 330. The metal layer 340 and the mirror layer 330 can also extend between the protrusions 350a', 350b' and the convex lenses 200a, 200b. The electrical connection between the main metal layer 350 and the convex lenses 200a, 200b is thus made via these layers 340, 330.

[0105] Advantageously, the wall 300 comprises a passivation layer 320 as described in the context of the first example.

[0106] The dielectric barrier layer 310 may comprise portions, called lateral portions 315, extending between the sides 303 of the wall 300 and the second electrical contact 350. These lateral portions 315 typically extend over the entire height of the wall 300.

[0107] In order to ensure electrical insulation between the anode and the cathode of the diode, it is necessary that at least one electrically insulating element separates in the transverse plane XY the lenses 100a, 100b from the second electrical contact 350. A single electrically insulating layer, sufficiently thick, can play this role. The simultaneous presence of the passivation layer 320 and the lateral portions 315 of the stop layer 310 is therefore not necessarily necessary.

[0108] In this third example, the electrically insulating element therefore comprises either the passivation layer 320, or a part of the barrier layer 310, or both.

[0109] A fourth example of the device 1 will now be described with reference to [Fig.2K].

[0110] This example differs from the previous example in that the electrically conductive element comprises a first metal element 350a and a second metal element 350b electrically insulated from each other. The first metal element 350a is electrically connected to the first lens 200a and the second metal element 350b is electrically connected to the second lens 200b. The metal elements 350a, 350b may each be in contact with an underlying second metal pad 17a, 17b.

[0111] The first metal element 350a and the second metal element 350b are separated over their entire height by the insulation portion 310* of the dielectric stop layer 310. Preferably, the insulation portion 310* extends over the entire height of the wall 300 in the third direction Z. The stop portion 310* thus plays in this example not only a role of stop layer during the manufacture of the device 1 but also a role of electrical insulator making it possible to individualize the operation of the two diodes 100a, 100b.

[0112] The first metal element 350a and the second metal element 350b each have an upper face 351a, 351b, preferably parallel to the upper face 301 of the wall 300, and sides 353a, 353b, preferably perpendicular to their upper faces 351a, 351b.

[0113] A metal layer 340 may cover, and preferably is in contact with, the upper faces 351a, 351b and the sides 353a, 353b of the metal elements 350a, 350b. The electrical connection between the metal elements 350a, 350b and the convex lenses 200a, 200b may thus be made via the metal layer 340.

[0114] The barrier layer 310 may also comprise side portions 315 extending between the sides 303 of the wall 300 and the first metal element 350a on the one hand and the second metal element 350b on the other hand. These lateral portions 315 typically extend over the entire height of the wall 300.

[0115] Advantageously, the wall 300 comprises a passivation layer 320 as described in the context of the first example.

[0116] The wall 300 may also comprise a mirror layer 330 extending between the passivation layer 320 and the lateral portions 315 of the dielectric barrier layer 310. The mirror layer 330 also typically extends over the entire height of the wall 300 in the third direction Z and is thus flush with the upper face 301 of the wall 300.

[0117] The lateral portions 315 of the barrier layer 310 typically completely separate the passivation layer and the mirror layer from the metal layer 340 and the metal elements 350a, 350b.

[0118] In this fourth example, the electrically insulating element comprises, or even consists of, the passivation layer 320. If the mirror layer 330 is omitted, it will also comprise the lateral portions 315 of the barrier layer 310.

[0119] In the third and fourth examples, no metal layer is present between the diodes 100a, 100b and the mirror layer 330. This makes it possible to improve the reflectivity of the mirror layer 330, which contributes to increasing the light extraction. It is optionally possible to add a second metal layer between the diodes 100a, 100b and the mirror layer 330, which will improve the quality of the contact at the expense of the light extraction.

[0120] Furthermore, it will be noted that unlike what was the case in the first two examples, in the third and fourth examples, the electrical connection and stop layer functions are decorrelated.

[0121] [Fig. 3] illustrates another example of a structure for the wall 300. In this example, the barrier layer 310 is metallic. The wall 300 comprises a second electrical contact 350 electrically connected and preferably in contact with the metallic barrier layer 310.

[0122] The wall 300 further comprises a passivation layer 320 extending from the sides 103a, 103b of the diodes 100a, 100b towards a central region of the wall 300. It also comprises a mirror layer 330 extending between the passivation layer 320 and the metal stop layer 310. The mirror layer 330 preferably extends to the upper face 301 of the wall 300. It is thus electrically connected to the convex lenses 200a, 200b when the device 1 is in operation.

[0123] In this example, the mirror layer 330 and the metallic stop layer 310 are also partially separated by an insulating layer 360.

[0124] The resumption of contact of the modules 1000a, 1000b is therefore done both by means of the stop layer 310 and the second electrical contact 350 and via the mirror layer 330.

[0125] This embodiment allows, in the case where the stop layer 310 is metallic, that it is not located between the diodes 100a, 100b and the mirror layer 330. This makes it possible to improve the reflectivity of the mirror layer 330, which contributes to increasing the light extraction.

[0126] As illustrated in [Fig.3], the wall 300 may have sides 303 inclined relative to the third direction Z. This is applicable to the other embodiments.

[0127] Different configurations of the wall 300 have been presented, but it is understood that other configurations are conceivable.

[0128] According to an example also illustrated in [Fig.3], the device 1 further comprises an anti-reflection layer 400 covering the upper faces 201a, 201b of the convex lenses 200a, 200b. This is typically a quarter-wave layer known to those skilled in the art. It makes it possible to avoid destructive interference on the surface 201a, 201b of the lenses 200a, 200b.

[0129] The anti-reflection layer 400 has a thickness e40o typically measured radially, in a direction passing through the center of the sphere of which the convex surface 201a, 201b of the convex lens 200a, 200b corresponds to a portion. e40o is chosen as a function of the wavelength emitted or received by the diodes 200a, 200b, the refractive index of the material composing the lenses 200a, 200b and the refractive index of the material overlying the anti-reflection layer 400 (air, filling material, etc.). e40o must not be too large to prevent modes from being guided in the anti-reflection layer, which would be detrimental to light extraction. e400 is typically between 100 and 150 nm depending on the emitted wavelength.

[0130] It is understood that the use of an anti-reflective layer 400 can be combined with any embodiment previously described and does not apply solely to the embodiment of the device shown in [Fig.3].

[0131] According to an example illustrated in [Fig.4D], the device 1 further comprises a secondary wall 300' surmounting the wall 300.

[0132] The secondary wall 300' is intended to absorb the radiation emitted by the diodes 100a, 100b which could be transmitted to a higher level, for example an optical element located above the neighboring diode. It thus makes it possible to limit the cross-talk phenomenon which can take place between the diodes and their surroundings by means of the material surmounting the diodes (air, filling material). For example, if a single diode 100a, 100b (corresponding to a pixel) is lit, the presence of the secondary wall 300' makes it possible to render a more intense black in the zones adjacent to this diode. The arrow 3 shown in [Fig.4D] illustrates the path of radiation emitted by the second diode 100b and reflected by the secondary wall 300'.

[0133] Arrow 3 is shown for explanatory purposes only. The angles of reflection of the radiation at the different interfaces are not representative of reality.

[0134] The secondary wall 300' may be based on a metallic material absorbing at the emission wavelength for emitting diodes or at the received wavelength for receiving diodes, such as TiN for the visible, or a charged organic material such as those used to produce black matrices (commonly referred to by the English term “black matrix”).

[0135] The secondary wall 300' is located at a distance from the convex lenses 200a, 200b. In other words, it is not in contact with the convex lenses 200a, 200b.

[0136] The secondary wall 300' has a height H300' measured along the third direction Z. It also has a width l300' measured in the transverse plane XY between its two main flanks 303' located opposite the lenses 200a, 200b (in [Fig.4D], along the first direction X). In the classic case of a secondary wall 300' in the form of a straight block, l300' is invariant along the third direction Z. However, it is also conceivable that the secondary wall 300' has other shapes, such as for example a trapezoidal shape, or that its main flanks 303' have a parabolic profile. In these latter cases, the width of the secondary wall 300' varies according to the third direction Z. l300' is then assimilated to the smallest width of the secondary wall 300', typically taken at the level of the upper face 301 of the wall 300.

[0137] The convex lenses 200a, 200b protrude relative to the plane in which the upper face 301 of the wall 300 extends over a height H2Oo, measured along the third direction Z.

[0138] Preferably, the secondary wall 300' extends at least as far as the convex lenses 200a, 200b away from the upper face 301 of the wall 300: H3Oo'>H2Oo. In other words, preferably, the first convex lens 200a and the second convex lens 200b are separated in planes parallel to the transverse plane XY over the entire height H200 by the secondary wall 300'.

[0139] Typically, H3Oo > 2 pm. Furthermore, preferably, l300- > 0.3 pm.

[0140] A shape ratio r=H3Oo / l3oo' of the secondary wall 300' is defined. Preferably, r is greater than 5, preferably greater than 7.

[0141] Converters may optionally be housed in the spaces defined by the secondary wall 300' and the convex lenses 200a, 200b.

[0142] A method of manufacturing such a secondary wall 300' is described further.

[0143] Method of manufacturing the optoelectronic device according to the invention

[0144] A first example of embodiment of a device according to the invention will be described with reference to Figures 1A to 11I. Figures 1A to 11J illustrate an example of a method for obtaining the stack provided at the start of the method according to the invention.

[0145] For the sake of clarity, the steps illustrated by Figures 1A to 11I illustrate the fabrication of a device with only two diodes. Naturally, these steps can make it possible to simultaneously obtain a diode array comprising numerous lens-covered diodes from a single initial stack.

[0146] [Fig.1A] illustrates the provision of an initial stack 1' comprising a support substrate 20, a continuous layer 200, a continuous active layer 100 and a dielectric layer 10. The continuous layer 200 and the continuous active layer 100 are in contact with each other.

[0147] The support substrate 20 has an upper face 21 extending mainly in a plane parallel to the transverse plane XY. The support substrate 20 also has a lower face 22 opposite and preferably parallel to its upper face 21. The support substrate 20 is typically a GaN on Si, or GaN on sapphire growth substrate.

[0148] The continuous active layer 100 is based on a semiconductor material. The continuous active layer 100 comprises an active region 110. This active region 110 is the site of radiative recombinations of electron-hole pairs making it possible to obtain or absorb light radiation. The active region 110 typically comprises a plurality of quantum wells, for example formed by layers based on GaN, InN, InGaN, AlGaN, AIN, AlInGaN, GaP, AlGaP, AlInGaP, AlGaAs, GaAs, InGaAs, AlIlAs, or a combination of several of these materials. The continuous active layer 100 further comprises a P-doped layer 120 and an N-doped layer 130 located on either side of the active region 110.

[0149] Preferably, the continuous layer 200 and the continuous active layer 100 are based on the same material. They have advantageously been formed simultaneously, for example by epitaxial growth on the support substrate 20. Together, they form a layer called the epitaxial layer 1000, which, when the continuous layer 200 and the continuous active layer 100 have been formed during the same growth step, forms a single continuous layer. The epitaxial layer 1000 is preferably based on GaN. It may also be based on InN, InGaN, AlGaN, AIN, AlInGaN, GaP, AlGaP, AlInGaP, AlGaAs, GaAs, InGaAs, AlIlAs, or a combination of several of these materials. The epitaxial layer 1000 may in particular comprise sub-layers such as AlGaN-based buffer layers.

[0150] The epitaxial layer 1000 has a thickness eiooo along the third direction Z. This thickness eiooo is typically between 2 and 6 pm.

[0151] The dielectric layer 10 has an upper face 11 extending mainly in a plane parallel to the transverse plane XY. The dielectric layer 10 also has a lower face 12 opposite and preferably parallel to its upper face 11. The dielectric layer 10 may for example be based on SiO2 or SiN. It has a thickness ei0 along the third direction Z. This thickness ei0 can for example be substantially equal to 300 nm.

[0152] The initial stack may comprise other layers, which may in particular be intercalated between the dielectric layer 10 and the continuous active layer 100. For example, an electrically conductive layer called the contact layer 30 may be inserted between the dielectric layer 10 and the continuous active layer 100. The contact layer 30 may for example be based on AISi or be a stack of sub-layers of AISi and ITO.

[0153] As illustrated in [Fig.lB], an etching is then carried out from the lower face 12 of the dielectric layer 10. This etching makes it possible to form a trench 50 passing completely through the dielectric layer 10 in the third direction Z and extending into the epitaxial layer 1000. The trench 50 does not completely pass through the epitaxial layer 1000 in the third direction Z. This etching step may comprise several successive etching sub-steps. A first etching sub-step with a stop on the contact layer 30 may firstly make it possible to make an opening in the dielectric layer 10. A second etching sub-step may then make it possible to remove an underlying portion of the contact layer 30 and of the epitaxial layer 1000, thus completing the formation of the trench 50.

[0154] An optional chemical treatment step, for example a wet chemical treatment based on tetramethylammonium hydroxide (commonly referred to as TMA) or potassium hydroxide (KOH) for example. This makes it possible to reduce the defects of the sides 53 of the trench 50.

[0155] The formation of the trench 50 makes it possible to single out the continuous active layer 100 into a first diode 100a and a second diode 100b. These two diodes 100a, 100b are separated in the transverse plane XY by the trench 50. Each diode 100a, 100b has a flank 103a, 103b merged with a flank 53 of the trench 50. The formation of the trenches 50 also makes it possible to single out the active region 110, the P-doped layer 120 and the N-doped layer 130.

[0156] The sides 53 of the trench 50 are shown in the figures parallel to the third direction Z, but it is understood that they can be inclined relative to this direction Z, for example by an angle between 75° and 85°.

[0157] As illustrated in [Fig.lB], a passivation layer 320 is then deposited against the sides 53 and on the bottom 51 of the trench 50. The passivation layer 320 can be deposited in a conformal manner. It can for example be based on one of the following materials: Al2O3, SiN, AlN.

[0158] As illustrated by the passage from [Fig.lB] to [Fig.lC], the portion of the passivation layer 320 covering the bottom 51 of the trench 50 is then removed. This allows to update again an intermediate surface 1001 of the epitaxial layer 1000. The portions of the passivation layer 320 extending from the sides 103a, 103b of the diodes 100a, 100b are preserved.

[0159] According to a first example, the epitaxial layer 1000 does not undergo an over-etching step at this stage and the rest of the process takes place from the assembly as illustrated in [Fig.lC] (option 1).

[0160] According to a second example illustrated in [Fig. 1D], a step of over-etching the epitaxial layer 1000 is implemented so as to extend the trench 50 and expose internal flanks 1003 of the epitaxial layer 1000 (option 2). The internal flanks 1003 of the epitaxial layer 1000 are then in the extension of the passivation layer 320.

[0161] The passivation layer 320 has a thickness e320, measured perpendicular to the sides 103a, 103b of the diodes 100a, 100b. e320 is measured from the sides 103a, 103b of the diodes 100a, 100b to the internal sides 323 of the passivation layer 320 opposite the sides 103a, 103b of the diodes 100a, 100b. The role of the passivation layer 320 is to electrically insulate the anode and the cathode of the same diode 100a, 100b. It must therefore be thick enough to withstand the potential difference between the anode and the cathode of the diodes 100a, 100b during operation of the device 1 (typically greater than 4V). To limit the size of the device, however, one will avoid unnecessarily increasing the thickness of the passivation layer 320. Thus, typically, e320 is between 50 and 100 nm.

[0162] The intermediate surface 1001 and the internal flanks 1003 of the epitaxial layer 1000 preferably undergo at this stage of the process a chemical surface preparation step, for example based on hydrogen fluoride (HF), buffered oxide etch (commonly referred to as BOE, from the English “Buffered Oxide Etch”), or tetramethylammonium hydroxide (TMAH).

[0163] As illustrated in Figures 1E and 1F, a stop layer 310 based on a metallic material is then deposited in this embodiment against the internal flank 323 of the passivation layer 320 and on the intermediate surface 1001 of the epitaxial layer 1000. The metallic stop layer 310 is preferably deposited conformally. It may for example be based on TiN or ITO. It may also be composed of a stack of sub-layers of AISi and TiN. In this last example, the metallic stop layer 310 may optionally comprise a Ti bonding film or an ITO contact film.

[0164] The metallic barrier layer 310 has an external flank 314 located opposite and preferably in contact with the internal flank 323 of the passivation layer 320. It also has an internal flank 313, opposite its external flank 314.

[0165] The metallic stop layer 310 has a thickness e3i0, measured along the third direction Z for its portion covering the intermediate surface 1001 of the epitaxial layer 1000. Typically, its thickness is substantially the same or less in its portions covering the internal sides 323 of the passivation layer 320.

[0166] The thickness e3i0 of the metallic barrier layer 310 is chosen as a function of the material(s) composing it and in particular of their selectivity relative to the material of the continuous layer 200.

[0167] For example, in the case of an ITO-based metal barrier layer 310, e3i0 may be substantially equal to 60 nm. When the metal barrier layer 310 is TiN-based, e3i0 may be substantially equal to 200 nm.

[0168] The value of e3i0 for a given stop material is determined in particular as a function of the total thickness variation (commonly referred to as TTV) of the continuous layer 200 appearing during the manufacturing steps, as will be discussed further. The thicknesses mentioned above were determined for a TTV value of 300 nm.

[0169] [Fig. 1E] and [Fig. 1F] correspond respectively to the deposition of the stop layer 310 on the assemblies illustrated in FIGS. 1C and 1D.

[0170] In the example illustrated in [Fig.lE], the metal stop layer 310 is in contact with the epitaxial layer 1000 only at its intermediate surface 1001 (option 1). In the case of an epitaxial layer 1000 based on raw GaN from a GaN support substrate 20 on Si, the contact between the metal stop layer 310 and the intermediate surface 1001 of the epitaxial layer 1000 is made in Ga polarity.

[0171] In the example illustrated in [Fig. 1F], the metal stop layer 310 is also in contact with the internal sides 1003 of the epitaxial layer 1000 previously exposed by the over-etching (option 2). This creates an additional contact zone, which can be designated lateral contact, between the metal stop layer 310 and the epitaxial layer 1000. This example thus makes it possible to increase the contact surface between the metal stop layer 310 and the epitaxial layer 1000.

[0172] When the metallic barrier layer 310 is based on ITO, option 1 is preferred.

[0173] Figures IG to 1K illustrate the continuation of the process in the case of option 1, but it is understood that the same steps apply when the second option is implemented.

[0174] As illustrated in [Fig.lG], an opening 60 is then formed in the dielectric layer 10 above each diode 100a, 100b. These openings 60 are intended to accommodate the first electrodes 15a, 15b electrically connected to the diodes 100a, 100b. The openings 60 advantageously open onto the contact layer 30. They are typically formed by lithography.

[0175] Following the formation of the openings 60 in the dielectric layer 10, a secondary metal layer 61 is advantageously deposited against the sides and in the bottom thereof, then a secondary mirror layer 63. The secondary metal layer 61 is preferably based on the same metallic material as the metallic stop layer 310. In this case, it can advantageously be provided that, during the deposition of the secondary metal layer 61, this material is again deposited in the trench 50 in order to increase the thickness of the metallic stop layer 310. It is also conceivable that the stop layer 310 is entirely formed after the formation of the openings 60, at the same time as the secondary metal layer 61.

[0176] As illustrated in [Fig. 1H], a layer called a mirror layer 330 is advantageously deposited in the trench 50, preferably in a conformal manner. The mirror layer 330 has external flanks 334 located opposite and preferably in contact with the internal flanks 313 of the metallic stop layer 310. It also has internal flanks 333, opposite its external flanks 334. The mirror layer 330 is based on a metallic material such as AlSi.

[0177] The trench 50 and the openings 60 are then filled with a conductive material in order to form a main metal layer 350 in the trench 50 and a first electrode 15a, 15b in each opening 60. For this, it is first possible to deposit seed layers (not shown, typically of the Ti / TiN / Cu type), then a damascene copper brick produced by filling with copper by electrochemical deposition (commonly referred to as ECD). Chemical-mechanical polishing of the Cu can then be implemented in order to free the lower face 12 of the dielectric layer 10 from any trace of Cu outside the trench 50 and 60. For this, the deposition of the stop layer in two stages as illustrated in [Fig.lG] / lH can allow better control of the CMP stop.

[0178] A passivation bilayer 10', for example of the SiN / SiO2 type, is then advantageously deposited, then a lithography and etching step is carried out in order to define through openings in the passivation bilayer 10'. The etching step may comprise a first sub-step of etching the SiO2 with a stop on the SiN, then a second sub-step of etching the SiN with a stop on the material constituting the main metal layer 350 and on the first electrodes 15a, 15b (typically copper). These openings open onto the main metal layer 350 and onto the first electrodes 15a, 15b. Gentle deoxidation of the copper may be carried out at this stage of the process. The openings in the bilayer 10' are then filled with an electrically conductive material such as Cu, preferably again using a damascene-type filling strategy. Once these openings are filled, we obtain the assembly illustrated in [Fig.II].

[0179] This step makes it possible to extend the main metal layer 350 and the first electrodes 15a, 15b by ensuring that their dimensions in the transverse plane XY at the level of the passivation bilayer 10' are smaller than their dimensions in the dielectric layer 10. This makes it possible to ensure the possibility of hybrid bonding of the assembly with a support substrate 20.

[0180] As illustrated by the passage from [Fig. II] to [Fig.U], a substrate of interest 5 is bonded by hybrid bonding to the passivation bilayer 10', the assembly is turned over and the support substrate 20 is removed. The removal of the support substrate 20 can for example be done by a polishing step then a finishing step by chemical etching.

[0181] Buffer layers present in the epitaxial layer 1000 may also be removed at this stage of the process. This removal may be carried out by dry etching or by more selective processes involving electropolishing or stopping on a selective buried layer.

[0182] The step of etching the buffer layers induces variations in the thickness of the continuous layer 200 (and therefore of the epitaxial layer 1000) along the third direction Z. It is thus possible to determine a total thickness variation (TTV) of the continuous layer 200. The TTV of a continuous layer 200 after removal of AIN-based buffer layers is typically of the order of 300 nm.

[0183] Finally, the lenses 200a, 200b are formed in the continuous layer 200. To do this, a resin can be deposited on the continuous layer 200 and then structured by a grayscale lithography step or a thermal reflux step. In both cases, the structuring of the resin into a convex shape is followed by a step of etching the continuous layer 200 through the resin mask in order to transfer the resin pattern into the continuous layer 200 and thus form the convex lenses 200a, 200b.

[0184] The etching is for example a dry etching. It is a selective etching between the material constituting the continuous layer 200 and the stop material.

[0185] The etching can for example be based on Cl2, a Cl2 / Ar mixture, a C12 / BC13 mixture, or even CH4. All these chemistries make it possible to etch GaN-based lenses 200a, 200b with very high selectivity with respect to a dielectric stop layer 310, whether it is based on an oxide or a nitride. The chemistries based on Cl2, a Cl2 / Ar mixture and a C12 / BC13 mixture make it possible to etch GaN-based lenses with satisfactory selectivity with respect to a metal stop layer 310 based on AISi, TiN, ITO and AlSi / TiN. A chemistry based on Ch4 can also be used in the case of a metal stop layer 310 based on AISi, TiN or ITO. In the case of an AISi-based 310 metallic barrier layer, a CH4-based chemistry is even particularly preferred.

[0186] Etching parameters other than chemistry (bias voltage, flux of gas...) are adapted in a conventional manner depending on the materials constituting the lenses 200a, 200b and the stopping layer 310.

[0187] As mentioned previously, the thickness e3i0 of the stop layer 310 is chosen according to the anticipated TTV for the continuous layer 200. The greater the TTV, the greater the thickness e3i0 of the stop layer 310. This allows, during the etching of the formation of the lenses 200a, 200b, for the stop layer 310 to absorb this TTV. The stop layer 310 thus makes it possible to compensate for the TTV of the continuous layer 200, which results in a good definition of the convex shape of the lenses 200a, 200b and in a good uniformity of height of the convex lenses 200a, 200b, without residual continuous layer between two lenses.

[0188] A second example of a method for manufacturing a device according to the invention will be described with reference to FIGS. 2A to 2K. FIGS. 2A, 2B, 2D, 2F, 2H and 2J illustrate the steps for obtaining a device according to the third example described previously. FIGS. 2A, 2C, 2E, 2G, 2I and 2K illustrate the steps for obtaining a device according to the fourth example described previously.

[0189] Figures 2A to 21 illustrate an example of a method for obtaining the stack provided at the start of the method according to the invention.

[0190] Again, for clarity, the steps illustrated in Figures 2A to 2K illustrate the fabrication of a two-diode device only. Naturally, these steps can simultaneously produce a diode array comprising many lens-covered diodes from a single initial stack.

[0191] [Fig.2A] illustrates the provision of an assembly similar to that shown in [Fig.1C]. It is obtained by the same steps as those previously described with reference to Figures 1A to 1C.

[0192] As illustrated in Figures 2B and 2C, in this embodiment, a stop layer 310 based on a dielectric material is then deposited in the trench 50. This dielectric material can in particular be chosen from the following materials: SiO2, SiN.

[0193] The dielectric barrier layer 310 has external flanks 314 located opposite the internal flanks 323 of the passivation layer 320.

[0194] According to a first example illustrated in [Fig.2B], the dielectric barrier layer 310 does not completely fill the trench. It can in particular be deposited conformally against the internal flanks 323 of the passivation layer 320 and on the intermediate surface 1001 of the epitaxial layer 1000. The dielectric barrier layer 310 then also has internal flanks 313, opposite its external flanks 314. In this example, the external flanks 314 of the dielectric barrier layer 310 are preferably in contact with the internal flanks 323 of the passivation layer 320.

[0195] In this example, the portion of the barrier layer 310 covering the intermediate surface 1001 has a thickness e3i0, measured along the third direction Z. In the case of a barrier layer 310 based on SiO2 or SiN, e3i0 can be substantially equal to 100 nm.

[0196] According to a second example illustrated in [Fig.2C], the stop layer 310 is deposited at this step so as to completely fill the trench 50.

[0197] In this example, a mirror layer 330 and a second metal layer 340' may have previously been deposited against the internal sides 323 of the passivation layer 320 and possibly partially on the intermediate surface 1001 of the epitaxial layer 1000. Thus, in this example, the stop layer 210 is typically separated from the passivation layer 320 by the mirror layer 330 and the second metal layer 340'.

[0198] In the context of the first example, openings 70 are then formed in the portion of the stop layer 310 covering the intermediate surface 1001 ([Fig.2D]). They make it possible to partially expose this surface 1001. The openings 70 are separated by a portion of the stop layer 310 left in place, called stop portion 310*.

[0199] The openings 70 typically have in the transverse plane XY a width l70 of the order of 1 μm.

[0200] In the context of the second example, openings 80 are then formed in the stop layer 310 ([Fig.2E]). These openings 80 pass entirely through the stop layer 310 in the third direction Z and make it possible to partially expose the intermediate surface 1001. The openings 80 are also separated by a portion of the stop layer 310 left in place, called stop portion 310*.

[0201] The openings 80 typically have in the transverse plane XY a width l80 of the order of 0.5 pm to 1 pm.

[0202] As illustrated in Figures 2D and 2E, in both examples, openings 60 are also formed in the dielectric layer 10, as in the first embodiment.

[0203] As illustrated in [Fig.2F], a mirror layer 330 and a metal layer 340 can be deposited in a conformal manner in the trench 50 and in particular in the openings 70. These layers 330, 340 thus completely cover the internal sides 313 of the stop layer 310 and its sides defined by the etching of the openings 70. They also cover the portions of the intermediate surface 1001 accessible by the openings 70.

[0204] Furthermore, it is possible to deposit at the same time against the sides and in the bottom of the openings 60 in the dielectric layer 10 a secondary metal layer 61 then a secondary mirror layer 63.

[0205] The trench 50, including in particular the openings 70, as well as the openings 60 are then filled with a conductive material in order to form a main metal layer 350 in the trench 50 and a first electrode 15a, 15b in each opening 60. For this, it is possible first of all to deposit seed layers (not shown), then a damascene copper brick (typically of the Ti / TiN / Cu type), and finally to carry out a filling with copper by electrochemical deposition (commonly referred to as ECD, from the English “Electrochemical Deposition”).

[0206] As illustrated in [Fig.2G], in the context of the second example, it is also possible to deposit in a conformal manner a mirror layer 330 (not shown) and a metal layer 340 in the openings 80 provided in the stop layer 310. These openings 80 and the openings 60 in the dielectric layer 10 are then filled with a conductive material in order to form a metal element 350a, 350b in each of the openings 80 and a first electrode 15a, 15b in each of the openings 60.

[0207] This step can be followed by a chemical-mechanical polishing step with a stop on the dielectric layer 10.

[0208] As in the first embodiment, the main metal layer 350 or the metal elements 350a, 350b, and the first electrodes 15a, 15b are extended in a passivation bilayer 10' deposited on the dielectric layer 10, a substrate of interest 5 is bonded by hybrid bonding to the passivation bilayer 10', the assembly is turned over and the support substrate 20 is removed. The assembly illustrated in [Fig.2H] (first example) or in [Fig.21] (second example) is thus obtained. The characteristics of these steps described in the context of the first embodiment can be applied mutatis mutandis in this second embodiment.

[0209] Finally, the continuous layer 200 is structured so as to form the convex lenses 200a, 200b, as illustrated by the transition on the one hand from [Fig.2H] to [Fig.2J] (first example) and on the other hand the transition from [Fig.21] to [Fig.2K] (second example). The formation of the lenses 200a, 200b is done in the same way as in the first embodiment, this time with a dielectric stop layer 310.

[0210] According to an advantageous variant, the method according to the invention further comprises the formation of a secondary wall 300' surmounting the wall 300 and separating the first lens 200a from the second lens 200b, as described previously.

[0211] Figures 4A to 4D illustrate steps for forming such a secondary wall 300'. These figures represent the device 1 according to an embodiment in which the barrier layer is based on a metallic material, but it is understood that the addition of a secondary wall 300' can be combined with any other embodiment. lization of the device 1 just described. The manufacturing method described below does not present any incompatibility with another embodiment of the device.

[0212] As illustrated by the transition from [Fig.4A] to [Fig.4B], the device 1 is first covered with a sacrificial layer 500 based on a sacrificial material, typically dielectric (SiO2, low dielectric constant material (in English “ultra-low k”), ...). A trench is then formed in the sacrificial layer 500 by a lithography process. This trench entirely crosses the sacrificial layer 500 and typically opens onto the upper face 301 of the wall 300. The trench does not extend in particular into the lenses 100a, 100b. The trench is then filled with an absorbent material such as TiN or Cu. The filling is typically carried out by an electrochemical process.

[0213] As illustrated in [Fig.4D], the sacrificial layer 500 is then removed by a wet chemical process. For example, in the case where the sacrificial material is SiO2, the removal can be carried out using a so-called buffered oxide etch (BOE) solution or a hydrogen fluoride (HF) solution.

[0214] This manufacturing method makes it possible to form a secondary wall 300' having a high aspect ratio between its height and its width.

[0215] Again, it is understood that the steps just described allowing the obtaining of a secondary wall 300' can be implemented so as to simultaneously form several secondary walls, each separating two convex lenses from an array of numerous convex lenses.

[0216] All the characteristics described with reference to the device according to the invention are applicable to the method according to the invention, and vice versa.

[0217] Through the different embodiments described above, it clearly appears that the invention proposes an effective solution for reducing optical crosstalk in a micro-LED matrix while retaining good optical properties of the device 1, in particular good light extraction and good directivity.

[0218] The invention is not limited to the embodiments previously described and extends to all embodiments covered by the invention.

Claims

Claims

1. Optoelectronic device (1) comprising: • a substrate (10') having an upper face (11') extending mainly parallel to a plane called the transverse plane (XY), • a matrix of light-emitting or photoreceiving diodes (100a, 100b, 100c, 100d, 100e) arranged on the upper face (11') of the substrate (10'), a first diode (100a) of the matrix being surmounted by a first convex lens (200a) and a second diode (100b) of the matrix being surmounted by a second convex lens (200b), the first convex lens (200a) and the second convex lens (200b) being based on a first material, the first diode (100a) and the second diode (100b) being separated, in the transverse plane (XY), by a wall (300) having an upper face (301) in contact with each of the first lens (200a) and the second lens (200b),characterized in that the first lens (200a) and the second lens (200b) are spaced apart from each other, and in that the wall (300) comprises a stop layer (310) extending at least from a portion (301*) of the upper face (301) of the wall (300) not being covered by either the first convex lens (200a) or the second convex lens (200b), the stop layer (310) being based on a material, called a stop material, the first material and the stop material being such that, for at least one etching chemistry of the first material, the etching selectivity between the first material and the stop material is greater than or equal to 3:1.,

2. Device (1) according to the preceding claim in which the first diode (100a), the second diode (100b), the first convex lens (200a) and the second convex lens (200b) are based on the same material, for example GaN.

3. Device (1) according to any one of the preceding claims in which the first diode (100a) and the second diode (100b) each have a flank (103a, 103b) defined by the interface of said diode (100a, 100b) with the wall (300), the device (1) comprising in further an electrically insulating element (320; 315) extending from the flank (103a, 103b) of each of the first diode (100a) and the second diode (100b).

4. Device (1) according to any one of the preceding claims further comprising a main metal layer (350) in electrical continuity with the first convex lens (200a) and with the second convex lens (200b).

5. Device (1) according to any one of the preceding claims further comprising a first metallic element (350a) in electrical continuity with the first convex lens (200a) and a second metallic element (350b) in electrical continuity with the second convex lens (200b), the first metallic element (350a) and the second metallic element (350b) being electrically insulated from each other.

6. Device (1) according to any one of the preceding claims, wherein the barrier layer (310) is based on a metallic material.

7. Device (1) according to the preceding claim in which the stopping layer (310) extends from the upper face (301) of the wall (300) under each of the first lens (200a) and the second lens (200b), preferably from the entire extent of the upper face (301) of the wall (300).

8. Device (1) according to any one of claims 1 to 5, wherein the barrier layer (310) is based on a dielectric material.

9. Device (1) according to the preceding claim in combination with claim 3 in which a part of the barrier layer (310) is part of the electrically insulating element.

10. Device (1) according to any one of the preceding claims further comprising a secondary wall (300') extending above the wall (300), between the first lens (200a) and the second lens (200b), the secondary wall (300') extending at least as far as the first convex lens (200a) and the second convex lens (200b), preferably beyond the first convex lens (200a) and the second convex lens (200b), away from the upper face (301) of the wall (300) in a third direction (Z) perpendicular to the transverse plane (XY), the secondary wall (300') being at a distance from the first lens (200a) and the second lens (200b).

11. Device (1) according to any one of the preceding claims in which each convex lens (200a, 200b) defines a surface convex (201a, 201b), said convex surface (201a, 201b) corresponding to a portion of the external surface of a sphere of diameter D200, each of the first diode (100a) and the second diode (100b) having a dimension D100, D100 being measured in projection in the transverse plane (XY), perpendicular to the projection of the wall (300) in the transverse plane (XY), with D200>2*D100.

12. Device (1) according to any one of the preceding claims in which the first convex lens (200a) and the second convex lens (200b) are surmounted by an anti-reflection layer (400).

13. A method of manufacturing an electronic device (1) comprising the following steps: • Provide a stack (2) comprising: i. a substrate (10') having an upper face (11') extending mainly parallel to a plane called the transverse plane (XY), ii. a matrix of photo-emitting or photo-receiving diodes (100a, 100b, 100c, 100d) arranged on the upper face (11') of the substrate (10'), a first diode (100a) of the matrix and a second diode (100b) of the matrix being separated, in the transverse plane (XY), by a wall (300) having an upper face (301), the wall (300) comprising a stop layer (310) extending at least partially from a portion at least of the upper face (301) of the wall (300), the stop layer (310) being based on a material called a stop material, iii. a continuous layer (200) based on a first material, covering at least the first diode (100a), the upper face (301) of the wall (300) and the second diode (100b), • Forming in the continuous layer (200) a first convex lens (200a) overlying the first diode (100a) and a second convex lens (200b) overlying the second diode (100b), the first convex lens (200a) and the second convex lens (200b) being spaced apart from each other, the formation of the first convex lens (200a) and the second convex lens (200b) comprising a selective etching of the first material with respect to the stop material, the etch selectivity between the first material and the stop material being greater than or equal to 3:

1.

14. Method according to the preceding claim in which the first diode (100a), the second diode (100b) and the continuous layer (200) are based on the same material.

15. Method according to any one of the two preceding claims in which the provision of the stack comprises the following steps: • Providing an initial stack comprising: i. The continuous layer (200), ii. A continuous active layer (100), iii. The substrate (10'), • Carrying out a so-called singularization etching from a lower face (12') of the substrate (10') opposite its upper face (11') into the substrate (10'), so as to form the first diode (100a) and the second diode (100b) in the continuous active layer (100), and to form a trench (50) between the first diode (100a) and the second diode (100b), • Forming the stop layer (310) in the trench (50).

16. Method according to the preceding claim, in which the first diode (100a) and the second diode (100b) each have a flank (103a, 103b) defined by the interface of said diode (100a, 100b) with the trench (50), the method further comprising the following steps: • Forming in the trench (50) an electrically insulating element extending from the flanks (103a, 103b) of the first diode (100a) and the second diode (100b), • At least partially filling the trench (50) with an electrically conductive material.

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