Method of manufacturing an optoelectronic device

Abstract

Method for manufacturing an optoelectronic device The present description relates to a method for manufacturing an optoelectronic device, comprising the following steps: a) arranging an active stack of photosensitive diodes (103) on a first substrate; b) arranging an active stack of LEDs (113) on a second substrate; c) after steps a) and b), transferring the active stack of photosensitive diodes (103) onto the active stack of LEDs (113), then removing the first substrate; and d) after step c), transferring the assembly comprising the active stack of photosensitive diodes (103) and the active stack of LEDs (113) onto a control integrated circuit (151) previously formed in and on a third semiconductor substrate, then removing the second substrate. Figure for abstract: Fig. 1K

Description

Title of the invention: Method for manufacturing an optoelectronic device Technical field

[0001] The present description relates generally to the field of optoelectronic devices, and more particularly relates to a method of manufacturing an optoelectronic device combining a light emission function and an optical capture function. Prior art

[0002] Various applications are likely to benefit from an optoelectronic device combining a light emission function and an optical capture function. Such a device can for example be used to produce an interactive display screen. Summary of the invention

[0003] An object of an embodiment is to overcome all or part of the drawbacks of known solutions for producing an optoelectronic device combining a light emission function and an optical capture function.

[0004] One embodiment provides a method of manufacturing an optoelectronic device, comprising the following steps: a) arranging an active stack of photosensitive diodes on a first substrate; b) arranging an active stack of LEDs on a second substrate; c) after steps a) and b), transfer the active stack of photosensitive diodes onto the active stack of LEDs, then remove the first substrate; and d) after step c), transfer the assembly comprising the active stack of photosensitive diodes and the active stack of LEDs onto a control integrated circuit previously formed in and on a third semiconductor substrate, then remove the second substrate.

[0005] According to one embodiment, the method comprises, before step b), a step of depositing a metal layer on the face of the active LED stack opposite the second substrate.

[0006] According to one embodiment, in step c), the active stack of photosensitive diodes is fixed to the active stack of LEDs by direct bonding.

[0007] According to one embodiment, in step c), when transferring the active stack of photosensitive diodes onto the active stack of LEDs, the active stack of photosensitive diodes extends continuously over the entire surface of the first substrate and the active stack of LEDs extends continuously over the entire surface of the second substrate.

[0008] According to one embodiment, the active photosensitive diode stack comprises at least one inorganic semiconductor layer, for example made of a III-V material, and the active LED stack comprises at least one inorganic semiconductor layer, for example made of a III-V material.

[0009] According to one embodiment, the active stack of photosensitive diodes comprises first, second and third semiconductor layers, the second layer being arranged between the first and third layers, and the third layer being arranged on the side of the active stack of LEDs at the end of step c).

[0010] According to one embodiment, the method comprises a step of P-type doping of localized portions of the first layer, the portions defining anode regions of photosensitive diodes of the device.

[0011] According to one embodiment, the step of P-type doping of localized portions of the first layer is implemented after step c) and before step d).

[0012] According to one embodiment, the method comprises, after the step of P-type doping of localized portions of the first layer and before step d), a step of forming connection metallizations on and in contact with the localized portions of the first layer.

[0013] According to one embodiment, the method further comprises, after step c) and before step d), a step of forming conductive vias passing through the active stack of photosensitive diodes.

[0014] According to one embodiment, in step d), the conductive vias are electrically connected to metal connection pads of the integrated circuit.

[0015] According to one embodiment, the method further comprises, after step d), a step of localized etching of the active stack of LEDs so as to form in the active stack of LEDs a plurality of blocks each defining an LED.

[0016] According to one embodiment, the method comprises forming color conversion elements above at least some of the LEDs.

[0017] According to one embodiment, at least one of the LEDs is surmounted by a photoluminescent conversion element adapted to convert the light emitted by the LED to a visible wavelength and at least one other of the LEDs is surmounted by a photoluminescent conversion element adapted to convert the light emitted by the LED into light radiation in the sensitivity wavelength range of the active stack of photosensitive diodes, preferably infrared radiation.

[0018] According to one embodiment, at least one of the LEDs is not surmounted by a photoluminescent conversion element.

[0019] According to one embodiment, the photoluminescent conversion elements are made from quantum dots or perovskite materials.

[0020] According to one embodiment, the method comprises, after step d), a step of fixing a temporary support substrate on the side of the active LED stack opposite the integrated circuit, followed by a step of cutting the assembly comprising the integrated circuit, the active photosensitive diode stack and the active LED stack into a plurality of elementary chips.

[0021] According to one embodiment, the method further comprises a step of transferring and fixing the elementary chips on a transfer substrate of the device, then a step of removing the temporary support substrate.

[0022] Another embodiment provides an optoelectronic device comprising a transfer substrate, and a plurality of elementary chips fixed and electrically connected to the transfer substrate, each elementary chip comprising a stack comprising, in order from the upper face of the transfer substrate, an integrated control circuit formed in and on a semiconductor substrate, a photodetection stage comprising at least one photosensitive diode, and an emission stage comprising at least one LED.

[0023] According to one embodiment, in each elementary chip, the photodetection stage is arranged between the control integrated circuit and the emission stage, and the photosensitive diode has a cathode semiconductor layer arranged on the side of the emission stage and an anode semiconductor layer arranged on the side of the control integrated circuit.

[0024] Another embodiment provides a system comprising an optoelectronic device produced by a method as defined above, and a light source adapted to emit light radiation in the sensitivity wavelength range of the active stack of photosensitive diodes, preferably infrared radiation.

[0025] According to one embodiment, the light source is a remote source.

[0026] According to one embodiment, the light source is integrated into the optoelectronic device electronics and includes at least one LED formed in the active LED stack. Brief description of the drawings

[0027] These characteristics and advantages, as well as others, will be explained in detail in the following description of particular embodiments given without limitation in relation to the attached figures among which:

[0028] [Fig.lA] ;

[0029] [Fig.lB] ;

[0030] [Fig.lC] ;

[0031] [Fig.lD] ;

[0032] [Fig.lE] ;

[0033] [Fig.lF] ;

[0034] [Fig.lG] ;

[0035] [Fig.lH] ;

[0036] [Fig. II] ;

[0037] [Fig.U] ;

[0038] [Fig.lK] ;

[0039] Figures 1A, 1B, 1C, 1D, 1E, 1F, 1G, 1H, 1I, 1J, and 1K are sectional views illustrating successive steps of an example of a method of manufacturing an optoelectronic device according to one embodiment;

[0040] [Fig.2A] ;

[0041] [Fig.2B] ;

[0042] [Fig.2C] ;

[0043] [Fig.2D] ;

[0044] [Fig.2E] ;

[0045] [Fig.2F] ;

[0046] [Fig.2G] ;

[0047] Figures 2A, 2B, 2C, 2D, 2E, 2F, and 2G are sectional views illustrating other successive steps of an example of a method of manufacturing an optoelectronic device according to an embodiment;

[0048] [Fig.3] schematically represents an example of a system comprising an optoelectronic device according to one embodiment;

[0049] [Fig.4] is a sectional view schematically and partially illustrating another example of an optoelectronic device according to one embodiment; and

[0050] [Fig.5] is a sectional view schematically and partially illustrating an alternative embodiment of the device of [Fig.4]. Description of the embodiments

[0051] 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.

[0052] 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 production of the photosensitive diodes, the light-emitting diodes (LEDs) and the integrated control circuits of the devices described has not been detailed, the detailed production of these elements being within the reach of the person skilled in the art from the indications of the present description. In addition, the various applications that the devices described may have have not been detailed, the embodiments described being compatible with all or most of the applications likely to benefit from a device combining a light emission function and an optical capture function (photodetection).

[0053] Unless otherwise specified, when referring to two elements connected to each other, this means directly connected without intermediate elements other than conductors, and when referring to two elements connected (in English "coupled") to each other, this means that these two elements can be connected or be connected by means of one or more other elements.

[0054] 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 corresponding figures.

[0055] Unless otherwise specified, the expressions "about", "approximately", "substantially", and "of the order of" mean to within 10%, preferably to within 5%.

[0056] According to one aspect of an embodiment, it is provided, in order to produce an optoelectronic device combining a light emission function and a photodetection function, to implement the following steps: a) arranging an active stack of photosensitive diodes on a first substrate; b) arranging an active stack of LEDs on a second substrate; c) after steps a) and b), transfer the active stack of photosensitive diodes onto the active stack of LEDs, then remove the first substrate; and d) after step c), transfer the assembly comprising the active stack of photosensitive diodes and the active stack of LEDs onto a control integrated circuit previously formed in and on a third substrate, then remove the second substrate.

[0057] Figures 1A to 1K are sectional views illustrating successive steps of a non-limiting example of implementing such a method. Various variants are within the reach of those skilled in the art based on the indications of the present description.

[0058] [Fig. 1A] schematically illustrates, in the upper part, the structure obtained at the end of steps of forming an active stack of photosensitive diode 103 on the upper face of a substrate 101.

[0059] The stack 103 is preferably a stack of inorganic semiconductor layers. The stack 103 comprises, for example, one or more layers of a III-V type semiconductor material. The stack 103 is, for example, an active stack of a photodiode sensitive in the infrared or near infrared. As a variant, the stack 103 is an active stack of a photodiode sensitive in the visible. For example, the stack 103 comprises, in order from the upper face of the substrate 101, a layer 103a of unintentionally doped indium phosphide (InP), an absorption layer 103b of indium-gallium arsenide (InGaAs), for example intrinsic or weakly doped N-type (for example of the order of 1015 atoms / cm3), and a layer 103c of indium phosphide (InP) doped N-type. For example, the N-type doping level of the layer 103c is between 1016 and 1018 atoms / cm3. In this example, the layer 103b is in contact, by its lower face, with the upper face of the layer 103a, and the layer 103c is in contact, by its lower face, with the upper face of the layer 103b.

[0060] The substrate 101 is for example made of indium phosphide. The layers 103a, 103b and 103c can be formed successively by epitaxy on the upper face of the substrate 101. The substrate 101 is then a growth substrate. A buffer layer, not shown, for example made of indium phosphide, can optionally form an interface between the substrate 101 and the layer 103a. The buffer layer is for example in contact, by its lower face, with the upper face of the substrate 101, and, by its upper face, with the lower face of the layer 103a. The buffer layer can also be formed by epitaxy from the upper face of the substrate 101, before the formation of the layers 103a, 103b and 103c.

[0061] As a variant, rather than forming the active stack of photosensitive diode 103 by epitaxy on the upper face of the substrate 101, the active stack can be formed in the reverse order on a growth substrate, not shown, then transferred and fixed on the substrate 101. In this case, the layers 103c, 103b and 103a are successively formed by epitaxy on one face of the growth substrate. A buffer layer, for example in indium phosphide, can optionally provide an interface between the growth substrate and the layer 103c. The stack 103 is then fixed to the upper face of the substrate 101, for example by direct bonding or molecular bonding of the lower face of the layer 103a to the upper face of the substrate 101. The growth substrate, and, where appropriate, the buffer layer forming an interface between the growth substrate and the layer 103c, can then be removed so as to free access to the upper face of the layer 103c.In this variant, the substrate 101 is a support substrate, for example made of silicon, or any other material suitable for serving as a support for receiving the active stack 103.

[0062] [Fig. 1A] further illustrates schematically, in the lower part, the structure obtained at the end of steps of forming an active stack of LEDs 113 on the upper face of a substrate 111.

[0063] The stack 113 is preferably a stack of inorganic semiconductor layers. The stack 113 comprises, for example, one or more layers of a III-V type semiconductor material. The stack 113 is, for example, an active stack of LEDs suitable for emitting visible light, for example predominantly blue light. By way of example, the stack 113 is an active stack of gallium nitride (GaN) LEDs. By way of example, the stack 113 comprises, in order from the upper face of the substrate 111, an N-type doped semiconductor layer 113a, forming a cathode layer of the LED stack, an active layer 113b, and a P-type doped semiconductor layer 113c, forming an anode layer of the LED stack. The layer 113a is for example made of gallium nitride. The active layer 113b is for example a multiple quantum well stack (not detailed in the figure), consisting of an alternation of semiconductor layers of a first material, for example a type IILV material, and semiconductor layers of a second material, for example a type IILV material, each layer of the first material being sandwiched between two layers of the second material and defining a quantum well. The layer 113c is for example made of gallium nitride. The active layer 113b is for example in contact, by its lower face, with the upper face of the layer 113a.The layer 113c is for example in contact, by its lower face, with the upper face of the active layer 113b.

[0064] The substrate 111 is for example made of silicon, sapphire, or gallium nitride. For example, the layers 113a, 113b and 113c are successively formed by epitaxy on the upper face of the substrate 111. A buffer layer, not shown, may optionally form an interface between the upper face of the substrate 111 and the lower face of the layer 113a.

[0065] At this stage, each of the layers of the active stack of photosensitive diodes 103 extends for example continuously and with a substantially uniform thickness over the entire upper surface of the substrate 101. In addition, each of the layers of the active stack of LEDs 113 extends for example continuously and with a substantially uniform thickness over the entire upper surface of the substrate 111. The substrates 101 and 111 have for example substantially the same lateral dimensions.

[0066] [Fig. 1 A] further illustrates a step of depositing a conductive layer 115 on and in contact with the upper face of the semiconductor layer 113c. The layer 115 forms an ohmic contact with the semiconductor material of the layer 113c. The layer 115 is for example made of aluminum, nickel, or a transparent conductive oxide, for example indium-tin oxide (ITO). At this stage, the metal layer 115 extends continuously and with a substantially uniform thickness over the entire upper surface of the layer 113c. The layer 115 may also have an optical reflector function. By way of example, the layer 115 may comprise two superimposed layers respectively ensuring the function of ohmic contact with the semiconductor material of the layer 113c and the optical reflector function.

[0067] [Fig. 1 A] further illustrates a step of depositing a dielectric layer 117, for example made of silicon oxide or silicon nitride, on and in contact with the face upper surface of the metal layer 115. In this example, the dielectric layer 117 extends continuously and with a substantially uniform thickness over the entire upper surface of the layer 115.

[0068] [Fig. 1A] further illustrates a step of depositing a dielectric layer 105, for example made of silicon oxide or silicon nitride, for example made of the same material as the layer 117, on and in contact with the upper face of the upper layer 103c of the active stack of photosensitive diodes 103. In this example, the dielectric layer 105 extends continuously and with a substantially uniform thickness over the entire upper surface of the layer 103c.

[0069] [Fig. 1B] illustrates the structure obtained at the end of a step of transferring and fixing the active stack of photosensitive diodes 103 onto the active stack of LEDs 113, then removing the substrate 101. During this step, the active stack of photosensitive diodes 103 is transferred onto the active stack of LEDs 113, using the substrate 101 as a support handle. In [Fig. 1B], the structure comprising the substrate 101 and the stack 103 is turned over with respect to the orientation of [Fig. 1A]. The stack 103 is then fixed to the stack 113. In this example, the stack 103 is fixed by direct bonding or molecular bonding of the lower face (in the orientation of [Fig.lB], corresponding to the upper face in the orientation of [Fig.lA]) of the layer 105, on the upper face (in the orientation of [Fig.lB], corresponding to the upper face in the orientation of [Fig.lA]) of the layer 117.The substrate 101 is then removed, for example by grinding and / or chemical etching, so as to free access to the upper face of the layer 103a. At this stage, each of the layers of the active photosensitive diode stack 103 extends, for example, continuously and with a substantially uniform thickness, over the entire surface of the active LED stack 113. It will be noted that in this example, the active stacks 113 and 103 are unstructured and have not undergone any localized treatment step before the transfer step. Thus, the transfer step does not require precise alignment.

[0070] [Fig.1C] illustrates a step of depositing a dielectric layer 121, for example made of silicon nitride or silicon oxide, on the upper face of the layer 103a, for example in contact with the upper face of the layer 103a. The layer 121 is for example deposited by a plasma-enhanced chemical vapor deposition (PECVD) process.

[0071] [Fig. 1D] illustrates a step of forming localized through-openings 123 in the dielectric layer 121. The openings 123 are for example formed by photolithography and etching. The openings are arranged opposite future P-type contact recovery zones corresponding to anode regions of the photosensitive diodes of the device.

[0072] [Fig.lE] illustrates a P-type doping step of localized regions 125 of the layer 103a, located opposite the openings 123. The doping of the regions 125 can be carried out by diffusion or implantation of P-type doping elements, for example zinc (Zn) or beryllium (Be), opposite the openings 123. An activation annealing of the doping elements can then be implemented. For example, the activation annealing can be a surface laser annealing, which makes it possible not to alter the quality of the bonding between the active stack of LEDs 113 and the active stack of photosensitive diodes 103. The P-type doped regions 125 form anode regions of the photosensitive diodes of the device. In this example, the regions 125 extend over the entire thickness of the layer 103a, and come into contact, by their lower face, with the upper face of the absorption layer 103b.

[0073] [Fig. 1F] illustrates a step of forming contact recovery metallizations 127 in the openings 123. Each metallization 127 individually contacts the underlying region 125, through the corresponding opening 123. By way of example, a metal layer is first deposited continuously over the entire upper surface of the structure, i.e. on and in contact with the upper face of the dielectric layer 121 and in the openings 123, then removed by photolithography and etching so as to retain only the metallizations 127. In this example, each metallization 127 constitutes an anode electrode of a photosensitive diode 171 of the device.

[0074] [Fig. 1G] illustrates the structure obtained at the end of steps of forming laterally insulated conductive vias 129, passing through the active stack of photosensitive diodes 103. More particularly, in this example, the conductive vias 129 pass through the layer 121, the layers 103a, 103b and 103c of the stack 103, the insulating layers 105 and 117, and open onto and in contact with the upper face of the metal layer 115. The production of the vias 129 comprises a step of etching, from the upper face of the insulating layer 121, through openings in the stack formed by the layers 117, 105, 103c, 103b, 103a and 121. The openings are for example formed by plasma etching, for example of the ICP type (of English: Inductively Coupled Plasma - inductively coupled plasma). A passivation step of the sides of the openings is then implemented.In this step, a layer 131 of an insulating material, for example silicon oxide, is deposited on the side walls and at the bottom of the openings. A vertical anisotropic etching step can then be implemented to remove the insulating layer at the bottom of the openings, without removing it on the side walls. The openings are then filled with metal to form the conductive vias 129.

[0075] [Fig. 1H] illustrates the structure obtained at the end of a step of fixing the structure of [Fig. 1G] on the upper face of an integrated control circuit 151, then removing the substrate 111.

[0076] The integrated circuit 151 may have been previously formed in and on a semiconductor substrate, for example made of silicon. It comprises circuits for controlling and reading the LEDs and photosensitive diodes of the device. For example, the integrated circuit 151 comprises a set of elementary control and reading cells, making it possible to control and read each LED and each photosensitive diode of the device individually. The integrated circuit 151 is for example a CMOS circuit (from the English "Complementary Metal Oxide Semiconductor"). In this example, the circuit 151 comprises a plurality of metal connection pads 153 arranged on the side of its upper face. In [Fig.lH], the structure comprising the active stacks 103 and 113 is inverted with respect to the orientation of [Fig.lG].

[0077] During the transfer, the lower face (in the orientation of [Fig.lH], corresponding to the upper face in the orientation of [Fig.lG]) of each metallization 127 is brought into contact with the upper face of one of the connection pads 153 of the integrated circuit 151. In addition, the lower face (in the orientation of [Fig.lH], corresponding to the upper face in the orientation of [Fig.lG]) of each conductive via 129 is brought into contact with the upper face of one of the connection pads 153. The fixing of the structure of [Fig.lG] on the integrated circuit 151 is for example obtained by hybrid direct bonding. By direct bonding, we mean here a molecular bonding, without adding material between the surfaces brought into contact.

[0078] The substrate 111 is then removed, for example by grinding and / or chemical etching, or by a laser detachment process, so as to free access to the upper face of the layer 113a.

[0079] [Fig. II] illustrates the structure obtained at the end of a localized etching step of the stack formed by the metal layer 115 and the active stack of LEDs 113. During this step, only the blocks 161 of the active stack of LEDs 113 are retained, corresponding respectively to the different LEDs of the device. The portion of metal layer 115 located under each LED 161 forms an anode electrode of the LED and is electrically connected to a pad 153 of the integrated circuit 151 by means of a via 129.

[0080] Apart from the LED tiles 161, the stack 113 and the metal layer 115 are completely removed, so as to expose the upper face of the dielectric layer 117.

[0081] [Fig.U] illustrates the structure obtained at the end of a step of passivation of the sides of the LEDs 161.

[0082] During this step, a layer 163 of an insulating material, for example silicon oxide, silicon nitride or alumina (A12O3) is deposited in a conformal manner on the side of the upper face of the structure, that is to say on the upper face of the insulating layer 117 and of the LEDs 161 and on the sides of the LEDs 161. A step of vertical anisotropic etching can then be implemented to remove the horizontal portions of the layer 163 while retaining the vertical portions of the layer 163, coating the sides of the LEDs 161.

[0083] [Fig.U] further illustrates a step of forming, in each photosensitive diode, a localized opening 164 passing through the insulating layers 117 and 105 and freeing access to the upper face of the semiconductor layer 103c.

[0084] [Fig. 1K] illustrates the structure obtained at the end of steps of deposition and etching of a conductive layer 165, for example made of a transparent conductive material, for example indium tin oxide (ITO), or of a metal sufficiently thin to be transparent, for example silver, to form cathode electrodes of the LEDs 161 and cathode electrodes of the photosensitive diodes 171 of the device.

[0085] By way of example, each LED 161 comprises an electrode 165(a) disposed on and in contact with the upper face of the N-type semiconductor layer 113a. In the example shown, the electrode 165(a) extends over at least one side of the LED and over the upper face of the insulating layer 117, and comes into contact, via its lower face, with the upper face of a conductive via 129. The electrode 165(a) is thus electrically connected to a pad 153 of the integrated circuit 151 via the via 129.

[0086] Furthermore, in this example, each photosensitive diode 171 comprises an electrode 165(b), preferably electrically insulated from the electrodes 165(a), arranged on the upper face of the insulating layer 117. In the example shown, each electrode 165(b) comes into contact, by its lower face, with the upper face of a conductive via 129. The electrode 165(b) is thus electrically connected to a pad 153 of the integrated circuit 151 by means of the via 129. The electrode 105b also comes into contact with the upper face of the semiconductor layer 103c through the opening 164 ([Fig.U]). Alternatively, the contact on the upper face of the semiconductor layer 103c, via the electrode 165(b) and the opening 164, can be made only at the periphery of the device, the doped layer 103c then ensuring the equipotential over the entire surface of the device.

[0087] It will be noted that in the example shown, the anode electrodes 127 and the cathode electrodes 165(b) of the photosensitive diodes 171, and the anode electrodes 115 and the cathode electrodes 165(a) of the LEDs 161 are all individually connected to connection pads 153 of the integrated circuit 151. Alternatively, the cathode electrodes 165(a) may be common to all the LEDs 161 of the device, and connected to the integrated circuit 151 at the periphery of the device, so as to limit the number of conductive vias 129 and pads 153. Similarly, the cathode electrodes 165(b) may be common to all the photosensitive diodes 171 of the device, and connected to the integrated circuit 151 at the periphery of the device, so as to limit the number of conductive vias 129 and pads 153. Alternatively, the common cathode electrodes of the photosensitive diodes and the common cathode electrodes of the LEDs can be connected to each other.

[0088] Depending on the application envisaged, light conversion elements, not shown, may optionally be arranged opposite LEDs 161, on their upper face side, to obtain, on the same device, emission pixels adapted to emit in different wavelength ranges, for example red pixels, green pixels and blue pixels. Furthermore, filtering elements, not shown, may optionally be arranged opposite photosensitive diodes 171, on their upper face side, to obtain, on the same device, detection pixels adapted to detect radiation in different wavelength ranges.

[0089] The method described in relation to Figures 1A to 1K can be used to produce monolithic micro-screens, combining an image display function and an optical capture function, for example to produce an interactive screen suitable for implementing functions of face or shape recognition, motion detection, identification, etc. An advantage of the method described is that it makes it possible to produce display pixels and capture pixels of small lateral dimensions, and thus obtain high display resolutions and capture resolutions. It will be noted that in the example described above, each pixel of the device comprises a photosensitive diode 171 and an LED 161. As a variant, the resolution of the display device and the resolution of the optical sensor may be different. For example, the number of photosensitive diodes 171 of the device may be less than the number of LEDs 161.

[0090] As a variant, the method described in relation to figures 1A to 1K can be used to produce larger interactive display devices, for example a television screen, computer screen, smartphone screen, digital tablet screen, etc. Such a device can comprise a plurality of elementary electronic chips arranged, for example in a matrix arrangement, 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 LEDs 161, one or more photosensitive diodes 171, and a circuit 151 for controlling said one or more LEDs and said one or more photosensitive diodes. Each chip corresponds for example to a pixel of the device.For example, each chip comprises three individually controllable LEDs 161, respectively defining three sub-pixels adapted to emit red light, green light and blue light respectively, and a photosensitive diode 171 adapted to detect infrared radiation or . near infrared.

[0091] Figures 2A to 2G are sectional views illustrating successive steps of an example of a method of manufacturing such a device.

[0092] [Fig. 2A] illustrates very schematically a starting structure which corresponds to a structure of the type obtained by the method of figures 1A to 1K, comprising a control integrated circuit stage 151, surmounted by a photo-detection stage 201, itself surmounted by an emission stage 203. The photo-detection stage 201 comprises a plurality of photosensitive diodes 171 (not detailed in figures 2A to 2G) individually controllable by the integrated circuit 151. The emission stage comprises a plurality of LEDs 161 (not detailed in figures 2A to 2G) individually controllable by the integrated circuit 151. In [Fig. 2A], only the electrical connection pads 153 of the integrated circuit 151, arranged on the side of the upper face of the integrated circuit 151, have been detailed.

[0093] [Fig.2B] illustrates a step of bonding the structure of [Fig.2A] onto a temporary support substrate 210, for example made of silicon. The structure of [Fig.2A] is fixed to the support substrate 210 by its face opposite the integrated control circuit 151, that is to say by its lower face in the orientation of [Fig.2B], corresponding to its upper face in the orientation of [Fig.2A].

[0094] [Fig.2C] illustrates an optional step of thinning the semiconductor substrate of the integrated circuit 151, by its face opposite the stages 201 and 203. For example, the integrated circuit 151 is initially formed in and on a SOI (Semiconductor On Insulator) type substrate. The SOI substrate comprises for example a silicon support, coated with an insulating layer, itself coated with a layer of monocrystalline silicon (not detailed in the figures). The components, in particular transistors, of the integrated circuit 151, can be formed in and on the monocrystalline silicon layer of the SOI substrate. The thinning step of [Fig.2C] can consist of removing the support substrate from the SOI substrate, so as to retain only the monocrystalline silicon layer and the insulating layer of the SOI substrate.

[0095] As a variant, the integrated circuit 151 is formed in and on a solid silicon substrate, the thinning step then being able to consist of reducing the thickness of the substrate, for example by grinding, from its upper face (in the orientation of [Fig.2C]). An insulating passivation layer (not detailed in the figure) can then be deposited on the upper face of the thinned substrate.

[0096] [Fig.2D] illustrates a step of forming, on the side of the upper face of the integrated circuit 151, metal connection pads 221, connected to the connection pads 153 and / or to connection terminals of electronic components, for example MOS transistors, of the integrated circuit 151, by means of non-conductive vias. detailed in the figure, crossing the semiconductor substrate of the integrated circuit 151.

[0097] [Fig.2E] illustrates a step of forming, from the upper face of the integrated circuit 151, trenches 230 vertically passing through the integrated circuit 151, the detection stage 201 and the emission stage 203, and opening onto the upper face of the temporary support substrate 210. The trenches 230 laterally delimit a plurality of semiconductor chips 232 corresponding to the elementary pixel chips of the display device. The trenches 230 can be formed by plasma etching, by sawing, or by any other suitable cutting method.

[0098] Figures 2F and 2G illustrate a step of fixing elementary chips 232 on the upper face of the same transfer substrate 250 of the display device. The transfer substrate 250 comprises, on its upper face side, a plurality of metal connection pads 252, intended to be fixed and connected electrically and mechanically to corresponding metal connection pads 221 of the elementary chips 232.

[0099] The structure of [Fig.2E] is turned over ([Fig.2F]) so as to place the metal connection pads 221 of elementary chips 232 opposite corresponding metal connection pads 252 of the transfer substrate 250. The pads 221 and 252 opposite each other are then fixed and electrically connected, for example by direct bonding, by soldering, by means of microtubes, or by any other suitable method.

[0100] Once fixed to the transfer substrate 250, the elementary chips 232 are detached from the temporary support substrate 210, and the latter is removed ([Fig.2G]). For example, the detachment of the chips is carried out by mechanical detachment or by detachment using a laser beam.

[0101] In the example shown, the pitch (center-to-center distance in front view) of the elementary chips 232 on the transfer substrate 250 is a multiple of the pitch of the elementary chips 232 on the substrate. Thus, only a portion of the elementary chips 232 (one out of two in the example shown) are simultaneously transferred from the temporary support substrate 210 to the transfer substrate 250. The other chips remain attached to the temporary support substrate 210 and can be transferred later to another portion of the transfer substrate 250 or to another transfer substrate 250.

[0102] 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 described embodiments are not limited to the examples of materials and / or dimensions mentioned in this description.

[0103] Furthermore, in the example described in relation to FIGS. 1A to 1K, the anode regions 125 and the anode metallizations 127 of the photosensitive diodes are made after the transfer of the active stack of photosensitive diodes 103 onto the active stack of LEDs 113. As a variant, not detailed in the figures, the anode regions 125 and the anode metallizations 127 of the photosensitive diodes can be produced before the transfer of the active stack of photosensitive diodes 103 onto the active stack of LEDs 113. In this case, the order of the layers of the stack 103 is reversed compared to the example of [Fig.lA]. An advantage is that the activation annealing of the dopants of the regions 125 can then be carried out before the transfer of the stack 103 onto the stack 113, which avoids any degradation of the bonding between the stack 103 and the stack 113 during annealing.

[0104] [Fig.3] schematically represents an example of a system comprising an optoelectronic device 300 according to one embodiment.

[0105] The device 300 may be a monolithic micro-screen type device, for example produced by a method of the type described in relation to FIGS. 1A to 1K.

[0106] As a variant, the device 300 may be a device of larger dimensions, for example produced by a method of the type described in relation to FIGS. 2A to 2G.

[0107] The device 300 combines an image display function and an optical capture function, for example to produce an interactive screen suitable for implementing functions of face or shape recognition, movement detection, identification, etc.

[0108] The system of [Fig. 3] further comprises a light source 310. The source 310 is adapted to emit light radiation in the sensitivity range of the photosensitive diodes 171 (not detailed in [Fig. 3]) of the device 300. By way of example, the source 310 is an infrared source, for example a laser source.

[0109] In operation, the source 310 illuminates a scene 320 of which an image is to be acquired. The light emitted by the source 310 is reflected by the scene 320 and returned to the device 300. The photosensitive diodes 171 of the device 300 then make it possible to acquire an image of the scene 320 and / or to measure depth information relating to the scene 320.

[0110] In the example of [Fig.3], the light source 310 is a remote source, that is to say it is distinct from the device 300. The control of the light source 310 and the control of the detection pixels of the device 300 are for example synchronized.

[0111] [Fig.4] is a sectional view schematically and partially illustrating another example of an optoelectronic device according to one embodiment.

[0112] In this example, the optoelectronic device integrates a distributed light source emitting in the sensitivity range of the photodiodes 171, for example an infrared source. This makes it possible to do without the remote source 310 of the system of the [Fig.3].

[0113] The device of [Fig.4] includes elements in common with the device of [Fig.1K]. These elements will not be detailed again below, and only the differences compared to the device of [Fig.1K] will be highlighted.

[0114] In the example of [Fig. 4], two LEDs 161(a) and 161(b) of the device are shown, for example identical or similar. The LEDs 161(a) and 161(b) are adapted to emit light in the same wavelength range, for example predominantly blue light. The embodiments described are however not limited to this particular example and the person skilled in the art will be able to adapt the embodiment described in relation to [Fig. 4] to other emission colors of the LEDs 161.

[0115] In this example, the LED 161 (a) is coated, on its upper face, with a photoluminescent conversion element 18 l(a) adapted to convert the light emitted by the LED into visible light at another wavelength, for example into red or green light in the case of an LED emitting blue light.

[0116] For example, in the case of LEDs emitting blue light, three types of visible light emitting pixels may be provided, each adapted to respectively emit red light (by means of a photoluminescent conversion element converting the blue light emitted by the underlying LED into red light), green light (by means of a photoluminescent conversion element converting the blue light emitted by the underlying LED into green light), and blue light (without a conversion element).

[0117] The LED 161 (b) is coated, on its upper face, with a photoluminescent conversion element 18 l(b) adapted to convert the light emitted by the LED into light radiation in the wavelength range detected by the photosensitive diodes 171 of the device, for example infrared radiation.

[0118] Thus, the LED 161 (b) defines a PIR emissive pixel of a light source integrated into the optoelectronic device, adapted to cooperate with the photosensitive diodes 171 and replacing the source 310 of the system of [Fig.3].

[0119] As described previously, the device of [Fig.4] may be a monolithic micro-screen type device, or a pixel of a larger device.

[0120] The number and repetition pitch of the PIR pixels may be chosen according to the needs of the application. For example, the device may comprise fewer PIR pixels than visible pixels (defined by the LEDs 161 (a)) of the same emission color. Preferably, the final device (monolithic micro-screen or extended device) comprises several PIR pixels distributed over the surface of the device.

[0121] The conversion elements 18l(a), 18l(b) surmounting the LEDs 161(a), 16l(b) are for example made from quantum dots or from perovskite materials, preferably inorganic perovskite materials, preferably epitaxially grown inorganic perovskite materials. Conversion elements based on perovskite materials are for example deposited by pulsed laser deposition (PLD).

[0122] [Fig.5] is a sectional view schematically and partially illustrating an alternative embodiment of the device of [Fig.4].

[0123] The variant of [Fig.5] differs from the example of [Fig.4] in that it further comprises opaque walls 191, for example made of resin, laterally separating the emissive pixels from each other and laterally separating the emissive pixels from the detection pixels. This makes it possible in particular to prevent light emitted by the PIR pixels from directly reaching the photosensitive diodes 171, without passing through the scene of which an image is to be acquired.

Claims

Claims

1. A method of manufacturing an optoelectronic device, comprising the following steps: a) arranging an active stack of photosensitive diodes (103) on a first substrate (101); b) arranging an active stack of LEDs (113) on a second substrate (111); c) after steps a) and b), transferring the active stack of photosensitive diodes (103) onto the active stack of LEDs (113), then removing the first substrate (101); and d) after step c), transferring the assembly comprising the active stack of photosensitive diodes (103) and the active stack of LEDs (113) onto a control integrated circuit (151) previously formed in and on a third semiconductor substrate, then removing the second substrate (111).

2. Method according to claim 1, comprising, before step b), a step of depositing a metal layer (115) on the face of the active LED stack (113) opposite the second substrate (111).

3. A method according to claim 1 or 2, wherein, in step c), the active photosensitive diode stack (103) is fixed to the active LED stack (113) by direct bonding.

4. A method according to any one of claims 1 to 3, wherein, in step c), when transferring the active stack of photosensitive diodes (103) onto the active stack of LEDs (113), the active stack of photosensitive diodes (103) extends continuously over the entire surface of the first substrate (101) and the active stack of LEDs (113) extends continuously over the entire surface of the second substrate (111).

5. A method according to any one of claims 1 to 4, wherein the active photosensitive diode stack (103) comprises at least one inorganic semiconductor layer, for example of a III-V material, and wherein the active LED stack (113) comprises at least one inorganic semiconductor layer, for example of a III-V material.

6. The method of any one of claims 1 to 5, wherein the active photosensitive diode stack (103) comprises first (103a), second (103b) and third (103c) semiconductor layers, the second layer (103b) being disposed between the first (103a) and third (103c) layers, and the third layer (103c) being disposed on the side of the active LED stack (113) at the end of step c).

7. Method according to claim 6, comprising a step of P-type doping of localized portions (125) of the first layer (103a), said portions defining anode regions of photosensitive diodes (171) of the device.

8. The method of claim 7, wherein said step of P-type doping of localized portions (125) of the first layer (103a) is carried out after step c) and before step d).

9. The method of claim 8, further comprising, after said step of P-type doping localized portions (125) of the first layer (103a) and before step d), a step of forming connection metallizations (127) on and in contact with said localized portions (125) of the first layer (103a).

10. Method according to any one of claims 1 to 9, further comprising, after step c) and before step d), a step of forming conductive vias (129) crossing the active stack of photosensitive diodes (103).

11. The method of claim 10, wherein, in step d), the conductive vias (129) are electrically connected to metal connection pads of the integrated circuit (151).

12. Method according to any one of claims 1 to 11, further comprising, after step d), a step of localized etching of the active stack of LEDs (113) so as to form in the active stack of LEDs a plurality of tiles (161) each defining an LED.

13. The method of claim 12, comprising forming color conversion elements (181(a), 181(b)) above at least some of the LEDs (161).

14. The method of claim 13, wherein at least one (161(a)) of said LEDs is surmounted by a photoluminescent conversion element (181(a)) adapted to convert the light emitted by the LED to a visible wavelength and at least one other (161(b)) of said LEDs is surmounted by a photoluminescent conversion element (181(b)) adapted to convert the light emitted by the LED into light radiation in the sensitivity wavelength range of the active photosensitive diode stack, preferably infrared radiation.

15. The method of claim 14, wherein at least one of said LEDs (161) is not surmounted by a photoluminescent conversion element. minescent.

16. A method according to claim 14 or 15, wherein said photoluminescent conversion elements (181(a), 181(b)) are made from quantum dots or perovskite materials.

17. Method according to any one of claims 1 to 16, comprising, after step d), a step of fixing a temporary support substrate (210) on the side of the active LED stack (113) opposite the integrated circuit (151), followed by a step of cutting the assembly comprising the integrated circuit (151), the active photosensitive diode stack (103) and the active LED stack (113) into a plurality of elementary chips (232).

18. Method according to claim 17, further comprising a step of transferring and fixing said elementary chips (232) on a transfer substrate (250) of the device, then a step of removing the temporary support substrate (210).

19. Optoelectronic device comprising a transfer substrate (250), and a plurality of elementary chips (232) fixed and electrically connected to the transfer substrate (250), each elementary chip (232) comprising a stack comprising, in order from the upper face of the transfer substrate (250), an integrated control circuit (151) formed in and on a semiconductor substrate, a photodetection stage (201) comprising at least one photosensitive diode (171), and an emission stage (203) comprising at least one LED (161).

20. Device according to claim 19, wherein, in each elementary chip, the photodetection stage (201) is arranged between the control integrated circuit (151) and the emission stage (203), and wherein said at least one photosensitive diode (171) has a cathode semiconductor layer (103c) arranged on the side of the emission stage (203) and an anode semiconductor layer (103a) arranged on the side of the control integrated circuit (151).

21. System comprising an optoelectronic device (300) produced by a method according to any one of claims 1 to 18, and a light source adapted to emit light radiation in the sensitivity wavelength range of the active stack of photosensitive diodes (103), preferably infrared radiation.

22. The system of claim 21, wherein the light source is a remote source (310).

23. The system of claim 21, wherein the light source is integrated into the optoelectronic device (300) and comprises at least one LED (161(b)) formed in the active LED stack (113).

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