Monolithic emissive optoelectronic chip

Abstract

The present description relates to a monolithic integrated circuit chip (501) comprising: - a plurality of individually controllable LEDs that are formed in a same active LED stack (113) and are separated laterally from one another by insulation trenches (127) filled with a dielectric material (131); and - underneath each LED, a first Bragg reflector (119) on the side of the face of the active LED stack (113) opposite the emission face of the LED.

Description

DESCRIPTION TITLE: Monolithic emissive optoelectronic chip This application is based on, and claims priority from, French patent application FR2211830 filed on November 14, 2022 and entitled "Monolithic emissive optoelectronic chip", which is considered to be an integral part of this description within the limits provided by law. Technical field

[0001] The present description relates generally to the field of image display devices, and more particularly aims at an integrated optoelectronic chip combining light emission functions at distinct wavelengths. Prior art

[0002] It has already been proposed, for example in patent applications WO2017089676, EP3401958 and WO2018185433 previously filed by the applicant, image display devices comprising a plurality of elementary monolithic electronic chips, for example microchips, arranged in a matrix on the same transfer substrate. The elementary chips are mounted integral with the transfer substrate and connected to electrical connection elements of the transfer substrate for their control. Each chip comprises one or more light-emitting diodes (LEDs) and an integrated circuit for controlling said one or more LEDs, and corresponds to a pixel of the device. The integrated control circuit comprises a connection face opposite said one or more LEDs, comprising a plurality of electrical connection pads intended to be connected to the transfer substrate for controlling the microchip. The transfer substrate comprises a face of connection comprising, for each microchip, a plurality of electrical connection pads intended to be connected respectively to the electrical connection pads of the microchip. The chips are attached to the transfer substrate, connection faces facing the connection face of the transfer substrate, and fixed to the transfer substrate so as to connect the electrical connection pads of each microchip to the corresponding electrical connection pads of the transfer substrate.

[0003] This type of display device is particularly suitable for making large-area display screens, for example computer screens, television screens, tablet screens, etc.

[0004] The focus here is more particularly on the production of an interactive image display device. More particularly, the focus here is on the production of an interactive image display device combining a visible light emission function for displaying images, and a light emission-reception function, for example infrared, for detection applications. Summary of the invention

[0005] One embodiment provides a monolithic integrated circuit chip comprising: - a plurality of individually controllable LEDs formed in a single active LED stack and laterally separated from each other by isolation trenches filled with a dielectric material; and - under each LED, on the side of the face of the active LED stack opposite the emission face of the LED, a first Bragg reflector.

[0006] According to one embodiment, the LEDs are adapted to emit at a first wavelength, at least a first LED of said plurality of LEDs being coated, on its upper face side, with a first element for converting said first wavelength into a second wavelength, and at least one second LED of said plurality of LEDs not being coated, on its upper face side, with an element for converting said first wavelength into said second wavelength.

[0007] According to one embodiment, the second LED is coated, on its upper face, with a second element for converting said first wavelength into a third wavelength.

[0008] According to one embodiment, at least a third LED of the plurality of LEDs is coated, on its upper face side, with a third element for converting said first wavelength into a fourth wavelength.

[0009] According to one embodiment, at least a fourth LED of the plurality of LEDs is not coated, on its upper face side, with a wavelength conversion element

[0010] According to one embodiment, the first wavelength is a visible wavelength and said second wavelength is an infrared wavelength.

[0011] According to one embodiment, the chip further comprises, on the side of the face of the first Bragg reflector opposite the active stack of LEDs, a control circuit integrated in and on a silicon layer, said control circuit being electrically connected to the LEDs via conductive vias passing through the first Bragg reflector.

[0012] According to one embodiment, at least one LED of the plurality of LEDs is coated, on its upper face, with a second Bragg reflector, so as to form a vertical cavity laser diode emitting from the surface.

[0013] According to one embodiment, the first Bragg reflector consists of alternating dielectric layers.

[0014] According to one embodiment, the second Bragg reflector consists of alternating dielectric layers.

[0015] According to one embodiment, the second Bragg reflector consists of an alternation of semiconductor layers.

[0016] Another embodiment provides a device comprising: - a transfer substrate comprising electrical connection elements; and - a plurality of monolithic elementary chips as defined above, fixed and electrically connected to the transfer substrate.

[0017] According to one embodiment, the device further comprises, associated with at least one of the elementary chips, a photosensitive detector, said at least one elementary chip integrating an electronic circuit for reading the photosensitive detector.

[0018] According to one embodiment, the photosensitive detector is external to said at least one elementary chip. Brief description of the drawings

[0019] These and other features and advantages will be set forth in detail in the following description of particular embodiments given without limitation 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, Figure 1K, Figure IL, Figure Figure 1M, Figure 1N and Figure 10 are sectional views illustrating steps of an example of a method for manufacturing elementary pixel chips of an interactive display device according to one embodiment;

[0021] Figure 2A, Figure 2B, Figure 2C, Figure 2D, Figure 2E, Figure 2F, Figure 2G, Figure 2H, Figure 2I, Figure 2J and Figure 2K are sectional views illustrating steps of another example of a method for manufacturing pixel element chips of an interactive display device according to one embodiment;

[0022] Figure 3 illustrates yet another exemplary embodiment of an elementary pixel chip of an interactive display device according to one embodiment;

[0023] Figure 4 is a top view schematically and partially illustrating an example of a transfer substrate of an interactive display device according to one embodiment; and

[0024] Figure 5A, Figure 5B and Figure 5C are sectional views illustrating successive steps of an example of a method of manufacturing an interactive display device according to one embodiment. Description of the embodiments

[0025] The same elements have been designated by the same references in the different figures. In particular, the structural and / or functional elements common to the different embodiments may have the same references and may have identical structural, dimensional and material properties.

[0026] For the sake of clarity, only the steps and elements useful for understanding the embodiments described have been shown and are detailed. In particular, the various applications that the devices may have interactive display devices described have not been detailed, the described embodiments being compatible with all or most of the known applications of an emissive display device integrating a light emission-reception function, for example applications of motion detection, face recognition, identification, etc.

[0027] Unless otherwise specified, when referring to two elements connected together, this means directly connected without intermediate elements other than conductors, and when referring to two elements connected (in English "coupled") together, this means that these two elements can be connected or be connected by means of one or more other elements.

[0028] In the following description, when reference is made to absolute position qualifiers, such as the terms "front", "back", "top", "bottom", "left", "right", etc., or relative position qualifiers, such as the terms "above", "below", "upper", "lower", etc., or to orientation qualifiers, such as the terms "horizontal", "vertical", etc., reference is made unless otherwise specified to the orientation of the figures.

[0029] Unless otherwise specified, the expressions "about", "approximately", "substantially", and "of the order of" mean to within 10%, preferably to within 5%.

[0030] According to one aspect of an embodiment, an image display device is provided comprising a plurality of elementary monolithic electronic chips arranged in a matrix on a single transfer substrate. As in the examples described in patent applications WO2017089676, EP3401958 and WO2018185433 previously filed by the applicant, the elementary chips are mounted integrally with the transfer substrate and connected to connection elements electrical connection of the transfer substrate. Each chip comprises several LEDs formed in the same active stack of LEDs, and an integrated circuit adapted to individually control said LEDs. The control circuit comprises a connection face opposite the LEDs, comprising a plurality of electrical connection pads (also called terminals or pads) intended to be connected to the transfer substrate for controlling the microchip. The transfer substrate comprises a connection face comprising, for each microchip, a plurality of electrical connection pads (also called terminals or pads) intended to be connected respectively to the electrical connection pads of the microchip.The chips are placed on the transfer substrate, with the connection faces facing the connection face of the transfer substrate, and fixed on the transfer substrate so as to connect the electrical connection pads of each microchip to the corresponding electrical connection pads of the transfer substrate.

[0031] According to one aspect of an embodiment, each elementary chip comprises, under each LED, between the LED and the control integrated circuit, a Bragg reflector.

[0032] For example, each LED defines a VCSEL (Vertical-cavity surface-emitting laser). For this, each elementary chip comprises, for each LED, in addition to the lower Bragg reflector arranged under the LED, an upper Bragg reflector arranged on the LED, that is to say on the face of the LED opposite the integrated control circuit. Each VCSEL is defined by the assembly comprising the lower Bragg reflector, the LED, the upper Bragg reflector, and possibly a wavelength conversion element covering the upper face of the upper Bragg reflector.

[0033] According to one embodiment, the image display device comprises a function for transmitting and receiving light radiation, for example infrared, making it possible to detect elements or variations in the environment of the device, and, for example, to modify accordingly an image displayed by the pixels of the device.

[0034] For this, the device comprises a plurality of photosensitive detectors, for example organic photodetectors, for example arranged in a matrix according to rows and columns, defining an image sensor.

[0035] The display device further comprises one or more LED emissive cells adapted to emit in a wavelength range of sensitivity of the photosensitive detectors.

[0036] For example, each elementary chip of the display device integrates one or more VCSELs adapted to emit visible light to display a pixel of an image, and a VCSEL adapted to emit light in a sensitivity wavelength range of the photosensitive detectors, for example infrared light.

[0037] The photodetectors are, for example, external to the elementary pixel chips of the display device, and are arranged on the transfer substrate of the device, on the same side of the transfer substrate as the elementary pixel chips. The photodetectors are, for example, connected to electrical connection terminals of the transfer substrate for their reading.

[0038] For example, the device comprises a photodetector per elementary pixel chip of the device, arranged in the vicinity of said elementary pixel chip. In other words, the matrix of elementary pixel chips of the display device and photodetector array are interleaved arrays of the same dimensions and pitch.

[0039] Each elementary pixel chip of the display device integrates for example an electronic circuit for reading an electrical signal representative of a light intensity received by the corresponding photodetector, that is to say of the same position in the pixel matrix, of the device. For this, each elementary pixel chip of the device can comprise a connection terminal individually connected to an electrode of the associated photodetector via a conductive track of the transfer substrate.

[0040] Examples of embodiments of such a display device will be described in more detail below in relation to the figures.

[0041] Figures 1A to 10 are sectional views illustrating an example of a method of manufacturing the elementary pixel chips of the device.

[0042] Figure 1A illustrates a starting structure comprising a substrate 111, on the upper face of which rests an active LED stack 113. The active LED stack 113 is for example an inorganic LED stack, for example based on one or more III-V type semiconductor materials, for example based on gallium nitride. The substrate 111 is for example made of sapphire or silicon.

[0043] The active LED stack 113 comprises, for example, in order starting from the upper face of the substrate 111, an N-type doped semiconductor layer 113a forming a cathode layer, an active layer 113b, and a P-type doped semiconductor layer 113c forming an anode layer. The cathode 113a and anode 113c layers are, for example, made of gallium nitride. The active layer comprises, for example, example an alternation of layers of quantum wells in a first semiconductor material and barrier layers in a second semiconductor material defining a stack of multiple quantum wells.

[0044] The active stack 113 can be formed by epitaxy on the upper face of the substrate 111. As a variant, the active stack 113 is formed by epitaxy on a growth substrate, not shown, then transferred to the upper face of the substrate 111.

[0045] In the example of Figure 1A, a buffer layer 112, for example made of gallium nitride, forms an interface between the substrate 111 and the active stack 113. By way of example, the buffer layer 112 is in contact, by its lower face, with the upper face of the substrate 111, and, by its upper face, with the lower face of the layer 113a of the active stack 113.

[0046] At this stage, the stack 113 is not yet structured into individual LEDs. In other words, the layers of the stack 113 each extend continuously and with a substantially uniform thickness over the entire upper surface of the substrate 111.

[0047] Figure 1B illustrates the structure obtained at the end of a step of localized neutralization of at least one upper part 114 of the upper semiconductor layer 113c of the active LED stack, so as to define, for each VCSEL of each elementary chip, a confinement zone 115 of the LED. The confinement zone 115 corresponds to a non-neutralized part of the layer 113c, surrounded laterally by the neutralized part 114.

[0048] In this example, an upper portion of the 113c semiconductor layer is oxidized over the entire surface of the active stack except for the confinement areas of confinement 115 of the LEDs. The oxidized region corresponds to the neutralized part of the layer 113c. For example, the oxidation can be carried out by means of an oxygenated plasma through a masking layer protecting the confinement zones 115.

[0049] In the example of Figures 1A to 10, the formation of five VCSELs each comprising a confinement zone 115 is shown. Thus, in Figure 1B, five confinement zones 115 are shown, laterally surrounded and separated from each other by the oxidized region 114.

[0050] From a top view, the containment zones 115 have, for example, a circular, square or rectangular shape.

[0051] The thickness of the oxidized region 114 is for example less than half, for example less than a quarter, of the thickness of the layer 113c. For example, the oxidized region 114 has a thickness of the order of 20 nm.

[0052] Alternatively, the neutralized region 114 can be obtained by localized implantation of doping elements in the layer 113c, or by localized deposition then etching of an oxide layer on the layer 113c.

[0053] Figure IC illustrates the structure obtained at the end of a deposition step, on and in contact with the upper face of the structure of Figure 1B, of an electrically conductive layer 117. Layer 117 is transparent to the emission wavelength of the LEDs. Layer 117 is for example made of a transparent conductive oxide, for example indium-tin oxide (ITO).

[0054] In this example, the layer 117 is deposited continuously and with a substantially uniform thickness over the entire upper surface of the structure of FIG. 1B. Thus, the layer 117 is in contact, by its lower face, with the upper face of the neutralized region 114 of the layer 113c and with the upper face of the confinement zones 115.

[0055] The thickness of layer 117 is for example between 50 and 100 nm.

[0056] Figure 1D schematically represents a control structure comprising a substrate 101 in and on which a plurality of elementary control integrated circuits 103 have been formed, for example identical or similar, corresponding respectively to the integrated circuits for controlling the LEDs of the future elementary pixel chips of the device.

[0057] In the example shown, the substrate 101 is an SOI (Semiconductor On Insulator) type substrate, comprising a support semiconductor substrate 101a, for example made of silicon, an insulating layer 101b, for example made of silicon oxide, arranged on and in contact with the upper face of the support substrate 101a, and an upper semiconductor layer 101c, for example made of monocrystalline silicon, arranged on and in contact with the upper face of the insulating layer 101b.

[0058] In this example, the elementary control circuits 103 are formed in and on the upper semiconductor layer 101c of the substrate 101. Each elementary control circuit 103 comprises, for example, a plurality of MOS transistors (not detailed in the figures). The elementary control circuits 103 are, for example, produced in CMOS (Complementary Metal Oxide Semiconductor) technology. Each elementary control circuit 103 may comprise a circuit adapted to individually control the emission of light by each LED of the future elementary pixel chip of the device. Each elementary control circuit 103 may further comprise a reading circuit for the photodetector associated with the future elementary pixel chip of the device.

[0059] In this example, each elementary control circuit 103 comprises, on its upper face side, one or more metal connection pads 105. By way of example, the pads 105 are flush on the upper face side of an upper insulating layer, for example made of silicon oxide, of an interconnection stack (not detailed in the figures) covering the upper face of the upper semiconductor layer 103c of the substrate 101.

[0060] For example, each elementary control circuit 103 comprises a specific metal pad 105 for each LED of the future elementary pixel chip of the device, intended to be connected to an anode region of the LED and making it possible to individually control the emission of light by said LED. The cathode contact (not detailed in the figure) may be common to all the LEDs of the chip.

[0061] For example, each elementary pixel chip of the device comprises four individually controllable VCSELs adapted to emit blue light, green light, red light and infrared light respectively. In this case, each elementary control circuit 103 may comprise four separate metal pads 105 intended to be connected respectively to the anode regions of the four corresponding LEDs.

[0062] Figure 1D further illustrates a step of forming, on the upper face of the control structure, a Bragg reflector 119. In this example, the Bragg reflector extends continuously and with a substantially uniform thickness over the entire upper surface of the structure. The Bragg reflector 119 is for example in contact, by its lower face, with the upper face of the control structure, comprising an alternation of metallic regions (the pads 105) and insulating regions.

[0063] The Bragg reflector consists of a stack of alternating transparent layers of distinct refractive indices. For example, the Bragg reflector consists of alternating transparent layers of a first material having a first refractive index and transparent layers of a second material having a second refractive index. The stack comprises, for example, 10 to 15 pairs of layers of the first and second materials. The first and second materials are, for example, dielectric materials. For example, the first and second materials are respectively silicon oxide (SiC>2) and tantalum oxide (Ta2Os). Alternatively, the first and second materials are respectively silicon oxide (SiCb) and niobium oxide (Nb2Os). Alternatively, the first and second materials are respectively silicon oxide (SiCh) and silicon nitride (SiN).The total thickness of the Bragg reflector 119 is for example between 0.5 and 1 pm.

[0064] Figure 1E illustrates the structure obtained at the end of a step of forming conductive vias 121 extending vertically through the Bragg reflector 119 and allowing the resumption, on the side of the upper face of the Bragg reflector, of an electrical contact on the underlying metal pads 105. The conductive vias 121 are in contact, by their lower face, with the metal pads 105. The vias 121 are preferably located outside the confinement zone of the future LEDs of the device so as not to hinder the light emission.

[0065] For example, the conductive vias 121 are formed by plasma etching through openings in the Bragg reflector, then filling the openings with metal.

[0066] Figure 1F illustrates the structure obtained at the end of a deposition step, on and in contact with the upper face of the structure of Figure 1E, of an electrically conductive layer 123. The layer 123 is transparent to the emission wavelength of the LEDs. The layer 123 is for example made of a transparent conductive oxide, for example indium-tin oxide (ITO).

[0067] In this example, the layer 123 is deposited continuously and with a substantially uniform thickness over the entire upper surface of the structure of FIG. 1E. Thus, the layer 123 is in contact, by its lower face, with the upper face of the Bragg reflector 119 and with the upper face of the conductive vias 121.

[0068] The thickness of layer 123 is for example between 50 and 100 nm.

[0069] Figure 1G illustrates the structure obtained following a step of transferring and fixing the structure of Figure 1C to the structure of Figure 1F.

[0070] In Figure 1G, the orientation of the structure in Figure 1F remains unchanged. In contrast, the structure in Figure 1C is flipped.

[0071] In this step, the structure of figure IC is attached to the upper face of the structure of figure 1F, using the substrate 111 as a handle. The lower face (in the orientation of figure 1G, corresponding to the upper face in the orientation of figure IC) of the conductive layer 117 is fixed to the upper face of the conductive layer 123. The fixing is for example obtained by direct bonding or molecular bonding of the lower face of layer 117 to the upper face of layer 123, that is to say without adding material between the two layers.

[0072] During this step, the two structures are aligned so as to arrange the confinement zones 115 of the future elementary LEDs of the device outside the direction of the conductive vias 121. For example, in each LED, the confinement zone 115 of the LED is located opposite a central part of the pad 105, one or more conductive vias 121 being located opposite a peripheral part of each metal pad 105.

[0073] Figure 1H illustrates the structure obtained at the end of a step of removing the substrate 111, for example by laser detachment or by grinding.

[0074] Figure II illustrates the structure obtained at the end of a step of removing the buffer layer 112 and, possibly, thinning the semiconductor layer 113a, for example by plasma etching, so as to obtain the desired vertical cavity thickness of the VCSELs (i.e. the distance between the lower Bragg reflector 119 and the upper Bragg reflector (figure IM) of the VCSELs).

[0075] Figure 1J illustrates the structure obtained at the end of a step of depositing a transparent conductive layer 125 on and in contact with the upper face of the semiconductor layer 113a, then of structuring the upper conductive layer 125, the active stack of LEDs 113, and the lower conductive layers 117 and 123. The layer 125 is for example made of a transparent conductive oxide, for example ITO. By way of example, the layer 125 is first deposited continuously and with a substantially uniform thickness over the entire surface of the layer 113a. Trenches 127 extending vertically in the layer 125, the stack active LED stack 113, and layers 117 and 123, are then formed from the upper face of the structure. The trenches 127 laterally delimit a plurality of islands 129 defining the individual LEDs of the future elementary chips of the device. The trenches 127 are for example formed by plasma etching. For example, the etching of layer 125, the etching of the active LED stack 113 and the etchings of layers 123 and 117 are self-aligned. For this, the same masking layer (not shown in the figures) can be used to etch layer 125, the active LED stack 113 and layers 123 and 117. This advantageously makes it possible to structure layer 125, the active LED stack 113 and layers 123 and 117 by means of a single photolithography step.

[0076] In the example of Figure 1J, the trenches 127 are interrupted on the upper face of the lower Bragg reflector 119 of the structure. As a variant, an etch stop layer, not shown, may be present between the upper face of the Bragg reflector 119 and the lower face of the lower conductive layer 123. In another variant, not shown, the trenches 127 are extended through the lower Bragg reflector 119 and are interrupted on the upper face of the control integrated circuit. In top view (not shown), the trenches 127 form a grid laterally separating the elementary LEDs from each other.

[0077] The portion of the stack of lower conductive layers 117 and 123 remaining under each LED at the end of this step constitutes an anode electrode of the LED. This anode electrode is electrically connected to a metal connection pad 105 of the underlying elementary control circuit 103 by means of one or more conductive vias 121 passing through the reflector of Lower Bragg 119 on the periphery of the confinement zone 115 of the LED. Thus, each LED has its anode electrode individually connected to a metal connection pad 105 of the elementary control circuit.

[0078] The portion of the upper conductive layer 125 located on each LED constitutes a cathode electrode of the LED.

[0079] Figure 1K illustrates the structure obtained at the end of a step of filling the trenches 127 with an electrically insulating material 131, for example an oxide, for example silicon oxide.

[0080] Figure 11 illustrates a subsequent step of depositing a transparent conductive layer 133 on and in contact with the upper face of the structure of Figure 1K. The layer 133 extends, for example, continuously and with a substantially uniform thickness over the entire upper surface of the structure. Thus, the layer 133 is in contact, by its lower face, with the upper face of the cathode electrodes 125 of the LEDs and with the upper face of the dielectric material 131 laterally insulating the LEDs.

[0081] At the end of this step, the cathode electrodes of the LEDs are electrically connected to each other via the conductive layer 133. In each elementary chip of the device, the common cathode conductive layer 133 can be electrically connected to a metal connection pad 105 of the integrated control circuit of the chip at a peripheral contact recovery zone, not shown.

[0082] As a variant, not shown, the transparent conductive layer 133 can be replaced by an opaque conductive layer, for example metallic, comprising a through opening opposite a central part of each LED of the device, so as to form a common cathode conductive grid.

[0083] Figure IM illustrates a subsequent step of forming an upper Bragg reflector 135 above each elementary LED of the device. For example, the upper Bragg reflector is first formed continuously over the entire structure, then structured into elementary pads located respectively opposite the elementary LEDs. As a variant, the step of structuring the reflector into elementary pads can be omitted. The Bragg reflector 135 is for example in contact, by its lower face, with the upper face of the common cathode conductive layer 133 of the structure.

[0084] The Bragg reflector 135 consists of a stack of alternating transparent layers of distinct refractive indices. For example, the Bragg reflector consists of alternating transparent dielectric layers. The structure of the upper Bragg reflector 135 is, for example, identical or similar to that of the lower Bragg reflector 119.

[0085] At this stage, each elementary chip comprises a plurality of VCSELs each comprising an elementary LED between a lower Bragg reflector 119 and an upper Bragg reflector. The thickness of the resonant cavity of the VCSELs, corresponding to the distance between the lower Bragg reflector 119 and the upper Bragg reflector 135, is chosen as a function of the emission wavelength of the LEDs. For example, the thickness of the resonant cavity of the VCSELs is a multiple of the emission wavelength of the LEDs.

[0086] In this example, the LEDs are formed from the same active LED stack and thus all have the same emission wavelength, for example a wavelength visible, for example a blue wavelength, for example between 480 and 460 nm.

[0087] Figure IN illustrates the structure obtained at the end of a step of forming wavelength conversion elements opposite one or more elementary LEDs of each elementary chip. The wavelength conversion elements are arranged on the side of the emission face of the VCSELs, that is to say on the side of the upper face of the upper Bragg reflector 135 of the VCSELs. In this way, in each elementary chip, VCSELs adapted to emit at different wavelengths are obtained.

[0088] In this example, the elementary LEDs are adapted to emit blue light, and each elementary pixel chip comprises four individually controllable VCSELs adapted to emit blue light, green light, red light and infrared light respectively. For this, in each elementary chip, a first VCSEL VB, intended to emit blue light, does not comprise a wavelength conversion element surmounting the upper Bragg reflector 135 of the VCSEL, a second VCSEL VR, intended to emit red light, comprises a wavelength conversion element 137R surmounting the upper Bragg reflector 135 of the VCSEL, a third VCSEL VG, intended to emit green light, comprises a wavelength conversion element 137G surmounting the upper Bragg reflector 135 of the VCSEL, and a fourth VCSEL VIR, intended to emit infrared light,comprises a 137IR wavelength conversion element surmounting the upper 135 Bragg reflector of the VCSEL. The 137R, 137G and 137IR elements are adapted to convert blue light into red light, blue light into green light, and blue light into infrared light, respectively.

[0089] Alternatively (not shown), the elementary LEDs are adapted to emit ultraviolet light, and the VCSELs VB, VR, VG and VIR include wavelength conversion elements adapted to convert ultraviolet light to blue light, ultraviolet light to red light, ultraviolet light to green light, and ultraviolet light to infrared light, respectively.

[0090] The wavelength conversion elements of the VCSELs are, for example, made of photoluminescent conversion materials, for example phosphors, perovskite materials or quantum dot (QD) based materials. For example, a layer of a polymer material 136 is first deposited over the entire upper surface of the structure of Figure 1M, then removed locally opposite the elementary LEDs so as to form cavities. The wavelength conversion elements are then deposited in the cavities.

[0091] Figure 10 illustrates the structure obtained at the end of a subsequent step of transferring the structure of figure IN onto a temporary support substrate 140. In figure 10, the orientation of the structure is reversed with respect to the orientation of figure IN. The temporary support substrate is fixed on the light-emitting face of the structure, that is to say its lower face in the orientation of figure 10 (corresponding to its upper face in the orientation of figure IN). The temporary support substrate 140 is for example a silicon substrate. The fixing of the temporary support substrate 140 onto the structure layer can be obtained by means of an adhesive bonding layer, not detailed.

[0092] Figure 10 further illustrates a subsequent step of removing the support substrate 101a from the SOI structure of departure, for example by grinding and / or chemical etching, so as to free access to the upper face of the insulating layer 101b of the SOI structure.

[0093] It will be noted that the embodiments described are not limited to the example described above in which the substrate 101 is an SOI type substrate. Alternatively, the substrate 101 may be a bulk semiconductor substrate, for example made of silicon. In this case, in the step of FIG. 1A, the substrate 101 may be thinned by its rear face (upper face in the orientation of FIG. 10), for example by grinding. An insulating passivation layer, for example made of silicon oxide, may then be deposited on the upper face of the thinned substrate, replacing the layer 101b of the SOI substrate. Alternatively, the layer 101b may be omitted.

[0094] Figure 10 further illustrates a subsequent step of forming contact recovery openings in the layers 101b and 101c, and of forming contact recovery metallizations 141 in and on said openings. The contact metallizations 141 make it possible to make electrical contacts on metal levels (not detailed in the figures) of the interconnection stack arranged on the side of the lower face of the semiconductor layer 101c. The metallizations 141 are for example electrically connected to transistors of the control circuit, these transistors themselves being electrically connected or linked to connection metallizations 105 of the LEDs.

[0095] The metallizations 141 form connection terminals of the future elementary pixel chips of the device, intended to be connected to corresponding connection terminals of the transfer substrate of the device.

[0096] At the end of these steps, the structure of figure 10 can be distinguished into elementary chips 501 each corresponding to a pixel of the display device, during a cutting step, not detailed in the figure. For this, trenches (not shown) extending vertically through the layers 101b, 101c, 119, 131, 133 and 136 are formed from the upper face of the structure, along cutting lines LD. For example, the trenches open onto the upper face of the temporary support substrate 140. In top view, the trenches form a continuous grid laterally delimiting a plurality of elementary pixel chips, for example identical or similar, each comprising an elementary control circuit 103 and a plurality of LED emissive cells adapted to emit in distinct wavelength ranges. The chip singulation trenches are for example produced by plasma etching.

[0097] The elementary pixel chips 501 thus defined are intended to be transferred onto a transfer substrate 400 of the display device, as will be described in more detail below in relation to FIGS. 5A to 5C.

[0098] Figures 2A to 2K are sectional views illustrating steps of another example of a method for manufacturing pixel element chips of an interactive display device according to one embodiment;

[0099] The embodiment of Figures 2A-2K differs from the embodiment of Figures 1A-10 primarily in that, in the example of Figures 2A-2K, the upper Bragg reflector layers of the VCSELs are epitaxially grown semiconductor layers.

[0100] Figure 2A illustrates a starting structure which differs from the structure of Figure 1A essentially in that it further comprises, between the cathode semiconductor layer 113a and the buffer layer 112, a Bragg reflector 201 comprising alternating semiconductor layers of a first material having a first refractive index and semiconductor layers of a second material having a second refractive index. The Bragg reflector 201 corresponds to the upper Bragg reflector of the future VCSELs of the device, replacing the upper Bragg reflector 135 of the example of Figures 1A to 10.

[0101] The stack constituting the Bragg reflector 201 comprises, for example, 20 to 50 pairs of layers of the first and second materials. The first and second materials are, for example, III-V type semiconductor materials. For example, the first and second materials are respectively aluminum nitride (AIN) and gallium nitride (GaN). Alternatively, the first and second materials are respectively aluminum indium nitride (AlInN) and gallium nitride (GaN). The total thickness of the Bragg reflector 119 is, for example, between 1.5 and 2.5 μm.

[0102] The Bragg reflector 201 and the active stack 113 can be formed successively by epitaxy on the upper face of the substrate 111. As a variant, the active stack 113 and the Bragg reflector 201 are formed by epitaxy on a growth substrate, not shown, then transferred to the upper face of the substrate 111. For example, the Bragg reflector 201 is in contact, by its upper face, with the lower face of the semiconductor layer 113a.

[0103] In this example, the thickness of the semiconductor layer 113a corresponds directly to the desired thickness to define the desired thickness of the vertical resonant cavity of the VCSELs.

[0104] In the example of Figure 2A, a buffer layer 112, for example made of gallium nitride, provides an interface between the substrate 111 and the Bragg reflector 201. For example, the buffer layer 112 is in contact, by its lower face, with the upper face of the substrate 111, and, by its upper face, with the lower face of the Bragg reflector 201.

[0105] The following steps of the method are identical or similar to the steps described in relation to figures 1B and 1C (neutralization of portions 114 of an upper part of the layer 113c to define the confinement zones 115, and deposition of the transparent conductive layer 117 on the upper face of the structure).

[0106] Figure 2B illustrates a step of transferring and fixing the structure obtained at the end of these steps, on a structure identical or similar to the structure of Figure 1F.

[0107] This reporting step is similar to what was described above in relation to Figure IG.

[0108] Figure 2C illustrates a step of removing the substrate 111, identical or similar to the step of Figure 1H.

[0109] Figure 2D illustrates a step of removing the buffer layer 112, identical or similar to the step of Figure II. At the end of this step, the upper face of the Bragg reflector 201 is exposed.

[0110] Figure 2E illustrates the structure obtained at the end of a subsequent step of structuring the upper Bragg reflector 201 into elementary pads or islands located respectively opposite the elementary LEDs of each chip. The structuring is for example carried out by photolithography then etching, for example by plasma, the etching being interrupted on the upper face of the semiconductor layer 113a.

[0111] Figure 2F illustrates a step of depositing a conductive contact layer 203 on the upper face of the structure of Figure 2E. The layer 203 extends for example continuously and with a uniform thickness over the entire upper surface of the structure. In particular, in the example shown, the conductive layer 203 extends on and in contact with the upper face and the flanks of the Bragg reflector pads 201, and on and in contact with the upper face of the semiconductor layer 113a between the Bragg reflector pads 201.

[0112] Layer 203 may be transparent, for example made of a transparent conductive oxide, for example ITO, or opaque, for example made of metal, for example aluminum or nickel.

[0113] Layer 203 forms a cathode contact recovery layer common to the elementary LEDs of each elementary chip of the device.

[0114] Figure 2G illustrates a step of forming, from the upper face of the structure, trenches 127 extending vertically in the layer 203, the active stack of LEDs 113, and the layers 117 and 123. The trenches 127 laterally delimit a plurality of islands 129 defining the individual LEDs of the future elementary chips of the device. The trenches 127 are for example formed by plasma etching. For example, the etching of the layer 203, the etching of the active stack of LEDs 113 and the etchings of the layers 123 and 117 are self-aligned. For this, the same masking layer (not shown in the figures) can be used to etch the layer 203, the active stack of LEDs 113 and the layers 123 and 117.

[0115] In the example of Figure 2G, the trenches 127 are interrupted on the upper face of the lower Bragg reflector 119 of the structure. Alternatively, an etch stop layer, not shown, may be present between the upper face of the Bragg reflector 119 and the lower face of the lower conductive layer 123. In another variant, not shown, the trenches 127 are extended through the lower Bragg reflector 119 and interrupted on the upper face of the control integrated circuit. In top view (not shown), the trenches 127 form a grid laterally separating the elementary LEDs from each other. In top view, the trenches extend between the Bragg reflector pads 201 and have, for example, a width less than the width of the trenches laterally separating the Bragg reflector pads 201 from each other.

[0116] The portion of the upper conductive layer 203 located on each LED constitutes an anode electrode of the LED.

[0117] Figure 2H illustrates the structure obtained at the end of a step of filling the trenches 127 with an electrically insulating material 131, for example an oxide, for example silicon oxide. In this example, the filling material 131 does not extend to the upper face of the Bragg reflector pads 201. In other words, the upper face of the filling material 131 is set back relative to the upper face of the Bragg reflector pads 201. For example, the filling material 131 extends to an intermediate level between the upper face of the active layer 113b of the active LED stack 113 and the upper face of the Bragg reflector pads 201. For example, the filling material 131 extends substantially to the upper face of the cathode semiconductor layer 113a.

[0118] Figure 21 illustrates a subsequent step of depositing a conductive layer 205 on and in contact with the upper face of the structure of Figure 2H. The layer 205 extends for example continuously and with a substantially uniform thickness over the entire upper surface of the structure. Thus, the layer 205 is in contact, by its lower face, with the upper face of the cathode electrodes 203 of the LEDs and with the upper face of the dielectric material 131 laterally insulating the LEDs.

[0119] At the end of this step, the cathode electrodes of the LEDs are electrically connected to each other via the conductive layer 205. In each elementary chip of the device, the common cathode conductive layer 205 can be electrically connected to a metal connection pad 105 of the integrated control circuit of the chip at a peripheral contact recovery zone, not shown.

[0120] The conductive layer 205 may be made of a transparent material, for example a conductive oxide, for example ITO. Preferably, the conductive layer 205 is made of an opaque material, for example a metal, which makes it possible to limit optical crosstalk between the pixels.

[0121] Figure 2J illustrates the structure obtained at the end of a planarization step, for example a mechanical-chemical planarization, leading to the removal of the portions of the conductive layers 203 and 205 covering the upper face of the upper Bragg reflectors 201 of the VCSELs. The layers 203 and 205 are, however, preserved on the sides of the Bragg reflector pads 201, and on the upper face of the upper semiconductor layer 113a as well as on the upper face of the filling dielectric material 131 between the Bragg reflector pads 201.

[0122] Figure 2K illustrates the structure obtained at the end of a step of forming wavelength conversion elements opposite one or more elementary LEDs of each elementary chip. The wavelength conversion elements are arranged on the side of the emission face of the VCSELs, that is to say on the side of the upper face of the upper Bragg reflector 201 of the VCSELs. This results in, in each elementary chip, VCSELs adapted to emit at different wavelengths.

[0123] This step is for example identical or similar to the step described previously in relation to figure IN.

[0124] The following steps are the same or similar to what was described above in relation to Figure 10.

[0125] Figure 3 illustrates yet another exemplary embodiment of an elementary pixel chip of an interactive display device according to one embodiment.

[0126] The embodiment of Figure 3 differs from that of Figures 1A to 10 in that, in the example of Figure 3, the upper Bragg reflector 135 is not present on at least some of the elementary LEDs of each elementary pixel chip of the display device. In the example shown, the upper Bragg reflector 135 is omitted in line with the elementary LEDs intended to emit visible light. It is, however, present in line with the LED intended to emit infrared light. Thus, the visible emission cells VB, VR, VG of each elementary chip are not, in this example, VCSELs but cells with a single Bragg reflector, also called RC-LED (from the English "Resonant Cavity LED"). The infrared emission cell VIR is, on the other hand, a VCSEL identical or similar to what has been described in relation to Figures 1A to 10.

[0127] Alternatively, the upper Bragg reflector 135 may be omitted on all elementary LEDs of each elementary chip of the display device, i.e. in the visible emission cells VB, VR, VG and infrared VIR of each elementary chip.

[0128] Figure 3 represents more particularly the structure obtained at an intermediate stage of the process, corresponding to the stage of figure IN in the example of figures 1A to 10.

[0129] Removal of the upper Bragg reflector 135 can be accomplished during the etching step of Figure IM.

[0130] The following steps are the same or similar to what was described above in relation to Figure 10.

[0131] The variant of Figure 3 may, in a similar manner, be combined with the variant of Figures 2A to 2K. In this case, the removal of the upper Bragg reflector 201 may be carried out during the etching step of Figure 2E.

[0132] Figure 4 is a schematic and partial top view of an exemplary embodiment of the transfer substrate 400 of the display device.

[0133] The transfer substrate 400 comprises, for example, a support plate or sheet 401 made of an insulating material, for example glass or plastic. As a variant, the support plate or sheet 401 comprises a conductive support, for example metal, covered by a layer of an insulating material. The transfer substrate further comprises electrical connection elements, and in particular conductive tracks and conductive pads, formed on the upper face of the support plate 401. These electrical connection elements are, for example, formed by printing a succession of conductive and insulating levels on the upper face of the support plate 401. The electrical connection elements are, for example, formed by a deposition or printing process of the inkjet printing type, for example screen printing, rotogravure, vacuum deposition, or any other suitable method, for example lithography.

[0134] In the example shown, the transfer substrate 401 comprises two conductive metal levels M1 and M2 separated by an insulating level (not visible in the figure), and metal vias V connecting the two metal levels through the insulating level. In this example, the transfer substrate 401 further comprises metal connection pads formed on the upper metal level M2, intended to be connected to corresponding connection pads 141 of the elementary pixel chips of the device

[0135] Active control circuits of the display device, adapted to power and control the elementary chips of the device via the electrical connection elements of the transfer substrate, are for example connected to the electrical connection elements of the transfer substrate at the periphery of the transfer substrate 400.

[0136] In the example shown, the manufacture of the transfer substrate comprises the following three successive deposition steps.

[0137] During a first deposition step, a plurality of conductive tracks substantially parallel to the direction of the columns of the display device (vertical direction in the orientation of FIG. 4) are formed on the upper face of the support plate 401. More particularly, in this example, during the first deposition step, four conductive tracks C1, C2, C3 and C4 are formed for each column of the display device, extending over substantially the entire length of the columns of the display device. The tracks C1 are intended to carry a DATA-V signal for adjusting the light intensity emitted by the LEDs of the visible light emitting cells of the elementary pixel chips of the column (it will be noted that in this example - not limiting - the intensity adjustment signals of the different colors (red, green, blue) are transmitted sequentially via track C1. As a variant, not shown, several separate tracks can be provided to transmit in parallel, on separate terminals of each elementary chip, the intensity adjustment signals of the different colors). Tracks C2 are intended to carry a DATA-IR signal for adjusting the light intensity emitted by the LEDs of the infrared emission cells of the elementary chips of the pixels of the column. Tracks C3 are intended to carry a DATA-S signal representative of the light intensity received by the photodetectors of the pixels of the column. Tracks C4 are intended to distribute a high supply potential VDD to the different elementary pixel chips.

[0138] The conductive elements formed during this first deposition step define the first conductive level Ml of the transfer substrate.

[0139] In a second deposition step, the first conductor is covered with an insulating material (not visible in the figure), so as to allow the subsequent deposition of conductive tracks extending above tracks C1, C2, C3 and C4, without creating a short circuit with tracks C1, C2, C3 and C4.

[0140] In a third deposition step, a plurality of conductive tracks substantially parallel to the direction of the lines of the display device are formed on the upper face of the support plate 401. More particularly, in this example, in the third deposition step, three conductive tracks L1, L2 and L3 are printed for each line of the display device, extending over substantially the entire length of the lines of the display device. The tracks L1 are intended to carry a signal SEL-L of selection of the corresponding pixel row. Tracks L2 are intended to carry a SEL-V signal for selecting the corresponding VCSEL diode row. Tracks L3 are intended to carry a SEL-S signal for selecting the corresponding photodetector row.

[0141] In this example, during the third deposition step, an ELI metal region defining a lower electrode of the photodetector of the display device is further printed for each pixel of the device.

[0142] The conductive elements printed during this third deposition step define the second conductive level M2 of the transfer substrate.

[0143] After the third deposition step, for each pixel, eight metal pads PI, P2, P3, P4, P5, P6, P7 and P8 are formed on conductive areas of the metal level M2, intended to receive respectively eight distinct connection pads 141 of the elementary chip of the pixel. The pads P5, P6 and P7 are connected respectively to the conductive tracks LI, L2 and L3 of the pixel. The pads Pl, P2, P3 and P4 are connected respectively to the conductive tracks Cl, C2, C3 and C4 of the pixel. The pad P8 is connected to the electrode ELI of the pixel. The aforementioned connections are made by conductive elements formed in the metal level M2, and, possibly, by vias V (open between the second and third deposition steps) and conductive elements formed in the metal level M1.

[0144] Figures 5A to 5C are sectional views illustrating successive steps of an example of a method of manufacturing an interactive display device according to one embodiment.

[0145] Figures 5A and 5B illustrate more particularly a step of collective transfer of elementary pixel chips onto the transfer substrate 400.

[0146] The elementary pixel chips, referenced 501 in FIGS. 5A to 5C, are initially fixed to one face of the temporary support substrate 140. The structure comprising the temporary support substrate 140 and the elementary chips 501 is for example produced by a method of the type described in relation to FIGS. 1A to 10 or in relation to FIGS. 2A to 2K or in relation to FIG. 3. In the example shown, the structure is turned over with respect to the orientation of FIG. 10, that is to say that the elementary chips 501 are arranged on the side of the lower face of the temporary support substrate 140.

[0147] For the sake of simplification, in Figures 5A to 50, the elementary chips 501 and the transfer substrate 400 have been represented schematically, and many elements have been omitted compared to the representations of the previous figures.

[0148] The elementary chips 501 are collectively attached opposite the connection face of the transfer substrate 400, namely its upper face in the orientation of FIGS. 5A and 5B, using the temporary support substrate 140 as a handle (FIG. 5A).

[0149] The connection terminals 141 of elementary chips 501, located on the lower face side of said chips, are then brought into contact with the corresponding connection pads P1, P2, P3, P4, P5, P6, P7, P8 of the transfer substrate 400, and fixed to said connection pads P1, P2, P3, P4, P5, P6, P7, P8. The fixing of the connection terminals 141 of the elementary chips 501 to the connection pads of the transfer substrate is for example carried out by direct bonding, by thermocompression, by soldering, by means of metallic microstructures (e.g. micro-pillars) previously formed on the terminals 141, or by any other suitable fixing and connection method.

[0150] Once fixed, by their connection terminals 141, to the transfer substrate 400, the elementary chips 501 are detached from the temporary support substrate 140 and the latter is removed (figure 5B), freeing access to the emission face of the LED emissive cells (not detailed in figures 5A to 5C).

[0151] The pitch of the elementary chips 501 on the transfer substrate 400 may be greater than the pitch of the elementary microchips 501 on the temporary support substrate 140. Preferably, the pitch of the elementary chips 501 on the transfer substrate 400 is a multiple of the pitch of the elementary microchips 501 on the temporary support substrate 140. In this case, only a portion of the chips 501 is taken from the support substrate 140 at each transfer, as illustrated in FIGS. 5A and 5B. The other chips 501 remain secured to the temporary support substrate 140 and may be used during another collective transfer step to populate another portion of the transfer substrate 400 or another transfer substrate.

[0152] Figure 5C illustrates the device after fixing all of the elementary chips 501 on the transfer substrate 400.

[0153] Figure 5C further illustrates a subsequent step of depositing, in each pixel, a portion of photosensitive organic layer 403, for example sensitive in the infrared or in the near infrared, on and in contact with the upper face of the ELI electrode of the pixel. The portions of layer 403 are for example deposited by a localized printing process, for example by screen printing or by a slot-die coating process. In each pixel, the portion of organic layer 203 extends for example over the entire upper surface of the ELI electrode of the pixel.

[0154] Figure 5C further illustrates a subsequent step of depositing, in each pixel, an upper electrode EL2 on and in contact with the upper face of the photosensitive organic layer portion 403 of the pixel. The electrode EL2 extends for example over the entire upper surface of the photosensitive organic layer portion 403 of the pixel. The electrode EL2 is transparent to the sensitivity wavelengths of the layer 403. For example, the electrode EL2 is made of a transparent conductive oxide, for example ITO. In this example, in each pixel, the stack of the layers ELI, 403 and EL2 forms a photodetector 511. The electrodes ELI and EL2 correspond for example respectively to the cathode electrode and the anode electrode of the photodetector.

[0155] The electrodes EL2 can be deposited locally through a stencil. For example, the upper electrode EL2 is common to all the pixels of the device. The electrode EL2 forms, for example, in top view, a continuous grid covering the portions of photosensitive layer 403 of all the pixels of the device. The common electrode EL2 can then be connected to a node for applying a fixed bias potential at the periphery of the pixel matrix.

[0156] Alternatively, the photodetectors 511 can be formed before the steps of transferring and fixing the elementary chips 501 on the transfer substrate 400.

[0157] 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 occur to those skilled in the art. In particular, the The embodiments described are not limited to the particular examples of embodiment of the elementary pixel chips and the transfer substrate described in relation to Figures 1A to 10, 2A to 2K, 3, 4 and 5A to 5C.

[0158] Furthermore, the described embodiments are not limited to the particular case described above in which the photodetectors of the device are organic photodiodes. As a variant, the organic photodetectors of the described device may be replaced by inorganic photodetectors, for example based on III-V type semiconductor materials, for example based on indium-gallium arsenide, or based on amorphous silicon. In another variant, the photodetectors 511 may consist of a matrix layer, for example made of resin, in which quantum dots are incorporated.

[0159] Furthermore, the embodiments described are not limited to the particular example described above in which the electronic reading circuit of each photodetector 511 is integrated into the elementary chip 501 of the corresponding pixel. As a variant, the electronic reading circuit of the photodetector may be integrated into a separate chip. In this case, the photodetector 511 may not be connected to the elementary chip 501 of the pixel. For example, the photodetector 511 and the electronic reading circuit of the photodetector 511 may be integrated into the same monolithic chip separate from the chip 501 and electrically connected to corresponding electrical connection pads of the transfer substrate 400.

[0160] In another variant, the photodetector and its reading circuit can be integrated into the chip 501.

[0161] For example, the photodetectors may be of the type described in French patent applications FR21 / 05156, FR21 / 05160 or FR21 / 09136, previously filed by the applicant.

[0162] Furthermore, the embodiments described in relation to FIGS. 1A to 10, 2A to 2K and 3 are not limited to the production of elementary pixel chips of an extended display device. As a variant, these methods can be adapted to the production of monolithic micro-screens each integrating a large number of pixels each comprising several LED emissive cells adapted to emit in different wavelength ranges. The pixels are for example arranged in a matrix according to rows and columns. For example, each monolithic micro-screen chip can integrate several thousand pixels. In this case, the manufacturing method can for example be interrupted at the end of the steps of FIG. 1M.

[0163] Furthermore, the embodiments described are not limited to the examples described above in which the monolithic chips produced integrate an electronic circuit for controlling the LEDs. As a variant, each chip comprises a plurality of individually controllable LEDs formed in the same active stack of LEDs covering the upper face of the support substrate, the support substrate being a passive substrate and the chip not integrating an electronic circuit for controlling the LEDs. In this case, the LEDs are controlled by an electronic circuit external to the chip, for example a circuit arranged on a peripheral region of the transfer substrate 400.

[0164] Furthermore, the described embodiments are not limited to the above-mentioned examples of emission wavelengths. For example, the above-mentioned infrared transceiver devices for implementing detection functions may be replaced by transmitting-receiving devices operating at other wavelengths, for example visible or ultraviolet.

[0165] Furthermore, the described embodiments are not limited to the above-described examples of application to interactive display devices, but may apply more generally to other LED emissive devices that may benefit from the use of VCSEL or RC-LED type emissive cells, for example a non-interactive color display device.

[0166] Finally, the practical implementation of the embodiments and variants described is within the reach of those skilled in the art from the functional indications given above.

Claims

CLAIMS A monolithic integrated circuit chip (501) comprising: a plurality of individually controllable LEDs formed in a common active LED stack (113) and laterally separated from each other by isolation trenches (127) filled with a dielectric material (131); and - under each LED, on the side of the face of the active stack of LEDs (113) opposite the emission face of the LED, a first Bragg reflector (119), the chip further comprising, on the side of the face of the first Bragg reflector (119) opposite the active stack of LEDs (113), a control circuit integrated in and on a silicon layer, said control circuit being electrically connected to the LEDs by means of conductive vias (121) passing through the first Bragg reflector (119).Chip (501) according to claim 1, wherein the LEDs are adapted to emit at a first wavelength, at least one first LED of said plurality of LEDs being coated, on its upper face side, with a first element (137IR) for converting said first wavelength into a second wavelength, and at least one second LED of said plurality of LEDs not being coated, on its upper face side, with an element for converting said first wavelength into said second wavelength. Chip (501) according to claim 2, wherein the second LED is coated, on its upper face side, with a second element (137R) for converting said first wavelength into a third wavelength. Chip according to claim 3, wherein at least a third LED of said plurality of LEDs is coated, on its upper face side, with a third element (137G) for converting said first wavelength into a fourth wavelength. Chip (501) according to claim 4, wherein at least a fourth LED of said plurality of LEDs is not coated, on its upper face side, with a wavelength conversion element. Chip (501) according to any one of claims 2 to 5, wherein said first wavelength is a visible wavelength and said second wavelength is an infrared wavelength. Chip (501) according to any one of claims 1 to 6, wherein at least one LED of said plurality of LEDs is coated, on its upper face side, with a second Bragg reflector (135; 201), so as to form a vertical cavity laser diode emitting by the surface.Chip (501) according to any one of claims 1 to 7, wherein the first Bragg reflector (119) is made up of alternating dielectric layers. Chip (501) according to claim 7 or according to claim 8 in its attachment to claim 7, wherein the second Bragg reflector (135) is made up of alternating dielectric layers. Chip according to claim 7 or according to claim 9 in its attachment to claim 8, wherein the second Bragg reflector (201) is made up of alternating semiconductor layers. Image display device comprising: - a transfer substrate (400) comprising electrical connection elements; and - a plurality of monolithic elementary chips (501) according to any one of claims 1 to 11 fixed and electrically connected to the transfer substrate (400). Device according to claim 11, further comprising, associated with at least one of the elementary chips (501), a photosensitive detector (511), said at least one elementary chip (501) integrating an electronic circuit for reading the photosensitive detector (511). Device according to claim 12, in which the photosensitive detector (511) is external to said at least one elementary chip.

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