Electronic device for capturing x-rays and displaying images

Abstract

The present description relates to an electronic device (100) for capturing and displaying images, comprising a plurality of pixels (PIX) formed in and on a semiconductor substrate (101), each pixel comprising: – a detection element (103) for detecting X-rays (105), located on the side of a first face (101F) of the semiconductor substrate (101); – an emission element (107) for emitting visible light (109), located on the side of a second face (101R) of the semiconductor substrate, opposite the first face; and – a circuit located in and on the semiconductor substrate and connecting the detection element to the emission element, the device (100) not having a pixel (PIX) control circuit external to the pixels (PIX).

Description

DESCRIPTION Electronic X-ray capture and image display device This application is based on, and claims priority from, French patent application FR2314059 filed on December 13, 2023 and entitled “Electronic device for capturing X-rays and displaying images”, which is considered an integral part of this description within the limits provided by law. Technical field

[0001] This description relates generally to electronic devices, and in particular to electronic devices for capturing and displaying images. Prior art

[0002] Electronic devices capable of implementing image capture and display functions have been proposed. Such devices typically comprise an image sensor, comprising an array of image capture pixels, and an image display, comprising an array of image display pixels distinct from the image capture pixels.Depending on the application, the image capture and display pixel matrices of the device may be located on the same side of a semiconductor substrate, for example in the case of a mobile phone, a connected watch or an electronic tablet comprising a display screen integrating an image sensor intended to acquire a user's fingerprints, or be located respectively on either side of the semiconductor substrate, for example in the case of a head-mounted display, a head-up display or smart glasses comprising one or more display screens intended to be placed each facing one another. a user's eye and one or more outward-facing image sensors.

[0003] Existing electronic image capture and display devices, however, suffer from various drawbacks. In particular, in these devices, the pixels of the image sensor are typically connected to a control circuit and a reading circuit, and the pixels of the image display are connected to a control circuit different from the control and reading circuits of the pixels of the image sensor. These circuits, which are for example located at the periphery of the pixel matrices of the sensor and of the image display, implement functions for addressing the pixel matrices to which they are respectively connected, and the images acquired by the sensor are for example stored in a memory circuit before being displayed, possibly after processing. This introduces an undesirable latency time between the acquisition of an image by the sensor and the display of the corresponding image by the display.Furthermore, existing electronic image capture and display devices exhibit high complexity, size, weight, power consumption, and manufacturing cost.

[0004] X-ray imaging devices have been proposed in particular. Among the known X-ray imaging devices, there are more particularly indirect conversion devices and direct conversion devices.

[0005] Indirect conversion devices comprise an array of photodiodes adapted to capture light radiation, and a scintillator arranged above the array of photodiodes. In operation, the scintillator emits light following the absorption of X-rays. The light emitted by the scintillator is converted into electrical charges by the photodiodes. Thus, the array of photodiodes acquires a representative image of the light distribution emitted by the scintillator, this light distribution itself being representative of the distribution of X-rays received by the scintillator.

[0006] Direct conversion devices comprise a layer of a semiconductor conversion material, adapted to directly convert absorbed X-rays into electrical charges. The conversion layer is arranged above a matrix of elementary circuits adapted to read the electrical charges generated in the conversion material. In operation, the conversion layer generates electrical charges following the absorption of X-rays. These charges are read by the matrix of reading circuits. Thus, the matrix of reading circuits directly acquires an image representative of the distribution of X-rays received by the conversion material.

[0007] In any case, the sensor and the display are separate and require complex peripheral circuits to ensure their control. Summary of the invention

[0008] It would be desirable to overcome all or part of the disadvantages of existing electronic image capture and display devices. In particular, there is a need to reduce the weight, size, complexity, power consumption, manufacturing costs and / or latency of these devices.

[0009] For this, one embodiment provides an electronic image capture and display device comprising a plurality of pixels formed in and on a semiconductor substrate, each pixel comprising: - an X-ray detection element, located on the side of a first face of the semiconductor substrate; - a visible light emitting element, located on the side of a second face of the semiconductor substrate opposite the first face; and - a circuit located in and on the semiconductor substrate and connecting the detection element to the emission element, the device being devoid of a pixel control circuit external to the pixels.

[0010] According to one embodiment, the circuit comprises: - an acquisition circuit located in and on the semiconductor substrate and adapted to provide an acquisition signal representative of an intensity of the X-ray radiation received by the detection element of the pixel; and - a control circuit located in and on the semiconductor substrate and adapted to apply a control signal to the emitting element of the pixel.

[0011] According to one embodiment, the acquisition circuit and the control circuit are analog circuits.

[0012] According to one embodiment: - each detection element comprises a photodetector; - each acquisition circuit comprises a comparator having an inverting input connected to a conduction electrode of the photodetector; and - each control circuit comprises an inverter having an input connected to an output of the comparator and an output connected to a gate of a MOS transistor, the MOS transistor comprising a conduction electrode connected to the emission element.

[0013] According to one embodiment, each emitting element comprises a single light-emitting diode.

[0014] According to one embodiment, the light-emitting diode is controlled by a control signal having pulses repeating at a frequency substantially proportional to an intensity of the X-ray radiation detected by the detection element.

[0015] According to one embodiment: - each detection element comprises a photodetector; - each acquisition circuit includes a signal shaping circuit; and - each control circuit comprises a multi-level comparator comprising an input connected to an output of the signal shaping circuit and at least two outputs each connected to a gate of a MOS transistor by an inverter, each MOS transistor comprising a conduction electrode connected to a light-emitting diode of the emission element.

[0016] According to one embodiment, each emitting element comprises exactly three light-emitting diodes.

[0017] According to one embodiment, the detection elements are located opposite the emission elements.

[0018] According to one embodiment, the detection elements and the emission elements are arranged respectively in first and second matrices, the first and second matrices having substantially identical pitches.

[0019] According to one embodiment, the device comprises as many detection elements as emission elements.

[0020] According to one embodiment, the device further comprises a scintillator surmounting the detection elements

[0021] According to one embodiment, the device further comprises a converter based on a perovskite material overlying the detection elements.

[0022] One embodiment provides a method of manufacturing a device as described above, the method comprising a step of transferring, by molecular bonding, a structure comprising the detection elements and the circuits onto another structure comprising the emission elements. Brief description of the drawings

[0023] 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:

[0024] Figure 1 is a schematic and partial isometric view of an image capture and display device according to one embodiment;

[0025] Figure 2 is an equivalent electrical diagram of a pixel of the device of Figure 1 according to one embodiment;

[0026] Figure 3 is an equivalent electrical diagram of a pixel of the device of Figure 1 according to another embodiment;

[0027] Figure 4 is a timing diagram illustrating, schematically and partially, an example of operation of the pixel of Figure 3;

[0028] Figure 5 is an equivalent electrical diagram of a pixel of the device of Figure 1 according to yet another embodiment;

[0029] Figure 6 is a timing diagram illustrating, schematically and partially, an example of operation of the pixel of Figure 5;

[0030] Figure 7A, Figure 7B, Figure 7C, Figure 7D, Figure 7E, Figure 7F, Figure 7G, Figure 7H, Figure 7I, Figure 7J, Figure 7K and Figure 7L illustrate, by means of schematic and partial sectional views, structures obtained at the end of steps of a method of manufacturing the device of figure 1 according to one embodiment;

[0031] Figure 8 is a schematic and partial top view of an interconnection network of the device of Figure 1; and

[0032] Figure 9A and Figure 9B illustrate, by means of schematic and partial sectional views, structures obtained at the end of successive steps of a method of manufacturing the device of Figure 1 according to another embodiment. Description of the embodiments

[0033] 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.

[0034] 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 X-ray imaging devices described may have have not been detailed, the embodiments described being compatible with all or most of the known X-ray imaging applications, and in particular the applications that can benefit from large X-ray imaging devices, for example devices having lateral dimensions greater than 10 cm, preferably greater than 20 cm. In addition, the production of the photosensitive diodes, the electronic control circuits, and the scintillator of the devices described has not been detailed, the production of these elements being within the reach of the person skilled in the art from the indications of this description.

[0035] 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.

[0036] In the following description, when referring to absolute position qualifiers, such as the terms "front", "back", "top", "bottom", "left", "right", etc., or relative, 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.

[0037] Unless otherwise specified, the expressions “about”, “approximately”, “substantially”, and “in the order of” mean to within 10%, preferably to within 5%.

[0038] In the following description, the terms "insulator" and "conductor" mean, unless otherwise specified, electrically insulating and electrically conductive respectively.

[0039] The expression "transmittance of a layer" designates a ratio between an intensity of radiation leaving the layer and an intensity of radiation entering the layer. In the remainder of the description, a layer is said to be opaque to radiation when its transmittance is, for this radiation, strictly less than 40%, preferably less than or equal to 25%, more preferably less than or equal to 10%. Furthermore, a layer is said to be transparent to radiation when its transmittance is, for this radiation, greater than or equal to 40%, preferably greater than or equal to 75%, more preferably greater than or equal to 90%. The definition of the qualifiers opaque and transparent (e) above is not limited to the case of a layer, but applies more generally to any element likely to be exposed to radiation, for example a substrate, a region, a stack of several layers, etc.

[0040] In the present description, the expression "visible light" designates electromagnetic radiation whose wavelength is between 400 nm and 700 nm. Furthermore, the expressions "X-rays" and "X-radiation" designate radiation consisting of photons with an energy of, for example, between 1,000 eV (electronvolts) and 20 MeV (megaelectronvolts).

[0041] Figure 1 is a schematic and partial isometric view of an image capture and display device 100 according to one embodiment.

[0042] According to this embodiment, the image capture and display device 100 comprises a plurality of pixels PIX formed in and on a semiconductor substrate 101.

[0043] Each pixel PIX of the device 100 comprises a detection element 103 of a radiation 105 and, associated with the detection element 103, an emission element 107 of a radiation 109. The detection elements 103 and emission elements 107 are respectively located on either side of the semiconductor substrate 101. More precisely, in the illustrated example, the detection elements 103 are located on the side of a face 101F of the substrate 101 and the emission elements 107 are located on the side of a face 101R of the substrate 101, opposite the face 101F. For the purpose of simplifying the drawing, each detection element 103 and each emission element 107 has been symbolized, in FIG. 1, by a parallelepiped having, in top view, a substantially square-shaped outline. This example is however not limiting, each detection element 103 or emission element 107 being able, as a variant, to have any shape, for example cylindrical.

[0044] In the illustrated example, the pixels DIX of the device 100 are arranged in a matrix according to rows and columns. More precisely, in this example, the detection elements 103 are arranged in a matrix according to rows and columns. Similarly, the emission elements 107 are, in this example, arranged in a matrix according to rows and columns. In each of these matrices, the rows are for example substantially orthogonal to the columns. This example is however not limiting, the rows being able, as a variant, not to be orthogonal to the columns.

[0045] For example, the device 100 comprises as many detection elements 103 as emission elements 107.

[0046] In the example shown, the matrix of emission elements 107 has a pitch, i.e. a center-to-center distance between two adjacent emission elements 107, substantially equal to the pitch of the matrix of detection elements 103, i.e. substantially equal to a center-to-center distance between two adjacent detection elements 103. Furthermore, in this example, the emission elements 107 are located opposite the detection elements 103. In the example illustrated, the center of each emission element 107 is located substantially directly above the center of the detection element 103 located opposite. The emission elements 107 have, for example, in top view, lateral dimensions substantially equal, apart from manufacturing dispersions, to those of the detection elements 103.This example is however not limiting, the emission elements 107 being able, as a variant, to have different lateral dimensions, for example greater or lesser. to those of the detection elements 103. The respective dimensions, for example the respective surfaces, of the detection elements 103 and emission elements 107 are for example chosen as a function of a desired sensitivity on the side of the detection elements 103 and / or of an intensity to be achieved on the side of the emission elements 107.

[0047] For example, the radiation 105 captured by the detection elements 103 is X-ray radiation. Furthermore, the radiation 109 emitted by the emission elements 107 is, for example, visible light.

[0048] Figure 2 is an equivalent electrical diagram of a pixel PIX of the device 100 of Figure 1 according to one embodiment.

[0049] In the example shown, the detection element 103 of the pixel PIX comprises a photodetector 201 adapted to capture the radiation 105. The photodetector 201 is for example adapted to produce, under the effect of the incident radiation 105, a current Iph, also called photocurrent. The photocurrent Iph is for example substantially proportional to an intensity, or to a flux, of the radiation 105 captured by the photodetector 201. In the example illustrated, the photodetector 201 comprises a first conduction terminal, for example an anode electrode, connected to a node 203 for applying a reference potential, for example ground. The photodetector 201 further comprises, in this example, a second conduction terminal, for example a cathode electrode, connected to a circuit 205. By way of example, the photodetector 201 is a photosensitive diode, or photodiode.

[0050] In the illustrated example, the circuit 205 comprises an acquisition circuit 207, also called a conditioner or conditioning circuit. The acquisition circuit 207 is for example adapted to provide an acquisition signal representative of the intensity of the radiation 105 captured by the photodetector 201. The acquisition signal produced by the acquisition circuit 207 is for example a function of the photocurrent Iph, for example substantially proportional to the photocurrent Iph. As a variant, the acquisition signal is a function of a voltage across the terminals of the photodetector 201, for example substantially proportional to this voltage.

[0051] The acquisition circuit 207 makes it possible, for example, to amplify the photocurrent Iph and to provide a voltage for driving the emission element 107. For these purposes, the acquisition circuit 207 comprises, for example, an amplifier symbolized, in FIG. 2, by a transistor. For example, the amplifier is of the CTIA type (from the English "Capacitive Trans-Impedance Amplifier" - capacitive transimpedance amplifier) ​​or of the RTIA type (from the English "Resistive Trans-Impedance Amplifier" - resistive transimpedance amplifier).

[0052] In the example shown, the circuit 205 of the pixel IX further comprises a control circuit 209, or driving circuit. The control circuit 209 is for example adapted to apply a control signal to the emission element 107. The control signal provided by the control circuit 209 is for example a function of the acquisition signal, for example substantially proportional to the acquisition signal.

[0053] In the example shown, the acquisition circuit 207 and the control circuit 209 each receive a calibration signal cal. The calibration signal cal makes it possible, for example, to compensate for manufacturing dispersions between the pixels PIX of the image capture and display device 100, for example manufacturing dispersions affecting the detection element 103 and / or the emission element 107 of the pixels PIX. In practice, the acquisition circuit 207 receives, for example, a calibration signal different from that received by the control circuit 209. The calibration signal cal has, for example, a determined value, for each pixel PIX, at the end of a calibration step subsequent to manufacturing steps of the image capture and display device 100. As a variant, the calibration signal cal can be omitted.

[0054] In the example illustrated, the emission element 107 of the pixel PIX comprises a light-emitting diode 211 adapted to emit the radiation 109. The light-emitting diode 211 is for example more precisely adapted to emit the radiation 109 when it is traversed by a lied current, corresponding for example to the control signal applied by the control circuit 209. The lied current has for example an intensity substantially proportional to that of the photocurrent Iph, for example substantially proportional to the intensity of the radiation 105 captured by the photodetector 201. In the example illustrated in FIG. 2, the light-emitting diode 211 comprises a first conduction terminal, for example an anode electrode, connected to the circuit 205, for example to an output of the control circuit 209.The light-emitting diode 211 further comprises, in this example, a second conduction terminal, for example a cathode electrode, connected to a node 213 for applying a potential -Vk, for example a low potential. The light-emitting diode 211 may be an organic or inorganic light-emitting diode. The diode 211 is for example of the micro-LED type, that is to say that it has micrometric dimensions.

[0055] In the case where the lied current has an intensity substantially proportional to that of the photocurrent Iph, the acquisition circuits 207 and control 209 are for example analog circuits. In this case, the circuit 205 is in particular devoid of an analog-digital converter.

[0056] Figure 3 is an equivalent electrical diagram of a pixel PIX of the device 100 of Figure 1 according to another embodiment. The equivalent electrical diagram illustrated in Figure 3 corresponds more precisely to a case in which the circuit 205 of the pixel PIX is adapted to control the emission element 107 by a pulse signal.

[0057] The diagram of Figure 3 includes elements in common with the diagram of Figure 2. These common elements will not be detailed again below. In particular, the detection 103 and emission 107 elements of the diagram of Figure 3 are for example identical to those of the diagram of Figure 2.

[0058] In the example shown, the acquisition circuit 207 of the pixel PIX comprises a comparator 301 comprising an inverting input (-) connected to a node 303 of the acquisition circuit 207, a non-inverting input (+) connected to a node 305 for applying a reference potential Vref, and an output connected to a node 307 of the acquisition circuit 207. In the example shown, the cathode of the photodetector 201 is connected to the node 303. The nodes 303 and 307 of the acquisition circuit 207 constitute, for example, respectively input and output terminals of the acquisition circuit 207. In the example shown, the nodes 303 and 307 respectively have potentials Vsn and Vo.

[0059] In the example shown, the acquisition circuit 207 further comprises a capacitive element 309, for example a capacitor, connecting the node 303 to another node 311 for applying a reference potential, for example ground. The capacitor may be substituted or supplemented by a parasitic capacitance of the node 303. In the example shown, the acquisition circuit 207 further comprises a transistor 313, for example a MOS (Metal-Oxide-Semiconductor) transistor. In this example, the transistor 313 is more precisely an N-type MOS transistor (NMOS transistor). In the example shown, the transistor 313 comprises a conduction terminal, for example a source electrode, connected to the node 303, another conduction terminal, for example a drain electrode, connected to a node 315 for applying a supply potential Vdd, and a control terminal, for example a gate electrode, connected to the node 307. The potential Vdd is for example strictly greater than the potential Vref.

[0060] In the illustrated example, the control circuit 209 comprises an inverter 317 and a transistor 319. The inverter 317 comprises for example an input connected to the node 307 of the acquisition circuit 207 and an output connected to a control terminal, for example a gate electrode, of the transistor 319. The transistor 319 is for example more precisely a P-type MOS transistor (PMOS transistor). In the example shown, the PMOS transistor 319 comprises a conduction terminal, for example a drain electrode, connected to the anode of the light-emitting diode 211 and another conduction terminal, for example a source electrode, connected to a node 321 for applying a supply potential Va.

[0061] For example, the light-emitting diode 211 is controlled by a control signal having an average value substantially proportional to the intensity of the radiation 105.

[0062] Figure 4 is a timing diagram illustrating, schematically and partially, an example of operation of the PIX pixel of Figure 3. The timing diagram of Figure 4 includes curves 401 and 403 illustrating an example of evolution, as a function of time (t), of the potentials Vsn and Vo, respectively.

[0063] Between a time t0 and a time t1, subsequent to the time t0, the photodetector 201 is exposed to the radiation 105 and produces the photocurrent Iph. During this period, the photocurrent Iph is integrated by the capacitive element 309. The charges photogenerated by the photodetector 201 accumulate at the node 303, thus causing a drop in the potential Vsn. In the example illustrated, the potential Vsn of the node 303 has, between the times t0 and t1, a value between that of the potential Vdd and that of the potential Vref. Between the times t0 and t1, the potential Vo of the node 307 connected to the output of the comparator 301 is for example at a low level.

[0064] At time t1, the potential Vsn reaches a value substantially equal to that of the reference potential Vref. This causes a switching of the output of the comparator 301, thus a transition of the potential Vo from the low level to a high level. The transistor 313 is then controlled to the on state, which has the effect of connecting the node 303 to the node 315. The photogenerated charges accumulated at the node 303 between times t0 and t1 are thus evacuated to the node 315. This tends to bring the potential Vsn back to a value substantially equal to that of the supply potential Vdd.

[0065] At a time t2, after time tl, the potential Vsn becomes higher than the potential Vref. This causes the output of comparator 301 to switch, causing a transition of the potential Vo from the high level to the low level. Curve 403 thus illustrates a pulse of the potential Vo between times tl and t2.

[0066] Between the instant t2 and an instant t3, subsequent to the instant t2, the curve 403 illustrates several other pulses of the potential Vo similar to that present between the instants t1 and t2. These pulses result, as explained above, from successive charges and discharges of the capacitive element 309 when the photodetector 201 is subjected to the radiation 105 and produces the photocurrent Iph. The pulses that curve 403 contains between times t0 and t3 are repeated, for example, periodically, for example at a frequency fh.

[0067] Between an instant t4, subsequent to instant t3, and an instant t5, subsequent to instant t4, curve 403 illustrates still other impulses of the potential Vo, for example analogous to the impulses present between instants t0 and t3.

[0068] The pulses of the potential Vo between the times t4 and t5 differ, for example, from the pulses of the potential Vo between the times t0 and t3 in that they are repeated periodically at a frequency fl strictly lower than the frequency fh. This comes, for example, from the fact that the photodetector 201 produces, during an LF phase between the times t4 and t5, a weaker photocurrent Iph, for example resulting from a drop in the intensity of the radiation 105, than during another HF phase between the times t0 and t3.

[0069] In the example shown, the frequencies fh and fl are representative of the photocurrent Iph, for example substantially proportional to the photocurrent Iph. The frequencies fh and fl are for example substantially proportional to the intensity, or to the flux, of the radiation 105 captured by the photodetector 201. The light-emitting diode 211 is for example thus controlled by a periodic signal of frequency substantially proportional to the intensity of the radiation 105 captured by the photodetector 201.

[0070] For example, the sensitivity of the PIX pixel is adjusted by modifying the value of the reference potential Vref, which limits the extent of the variation range of the potential Vsn. In the example shown, for the same value of radiation intensity 105, the closer the value of the potential Vref is to that of the potential Vdd and the higher the frequency of variation of the potential Vo. Conversely, the further the value of the potential Vref is from that of the potential Vdd and the lower the frequency of variation of the potential Vo.

[0071] The embodiments of the circuit 205 of the pixel PIX are not limited to the examples of the detection 207 and control 209 circuits shown, and the person skilled in the art is capable, based on the indications of the present description, of providing detection and control circuits different from those set out in relation to FIGS. 3 and 4. For example, a counter or a frequency divider may be provided in the control circuit 209 in order to allow an adjustment of the variation frequency of the potential Vo for each pixel PIX independently of the other pixels PIX. The adjustment is then for example carried out in the factory, for example at the end of manufacturing steps of the device 100, and for example implements a step of storing calibration values ​​in memory circuits of the device 100, for example memory circuits of the ROM (Read-Only Memory) or flash type.This avoids the presence of addressing circuits in the device 100. Other types of circuits, for example logarithmic response circuits, could also be provided.

[0072] Figure 5 is an equivalent electrical diagram of a pixel PIX of the device 100 of Figure 1 according to yet another embodiment. The diagram of Figure 5 illustrates more precisely a case in which the emission element 107 of the pixel PIX is capable of emitting radiation 109R, 109G and 109B in different wavelength ranges depending on the energy of the incident X-ray radiation 105.

[0073] The diagram in Figure 5 includes elements in common with the diagram in Figure 2. These common elements will not be detailed again below.

[0074] In the example illustrated in Figure 5, the second conduction terminal of the photodetector 201, for example its cathode electrode, is connected to a node 501 of the detection element 103. In this example, the node 501 is connected to an input of the circuit 205, more precisely to an input of the acquisition circuit 207.

[0075] Furthermore, in the example shown, the detection element 103 comprises a capacitive element 503, for example a capacitor, connecting the node 501 to another node 505 for applying a reference potential, for example ground. The capacitor can be substituted or supplemented by a parasitic capacitance of the node 501.

[0076] In the example shown, the detection circuit 207 comprises a signal shaping circuit 511 (“shaper”, in English), here a circuit for shaping the current Iph. In this example, the circuit 511 comprises an input connected to the node 501 and an output connected to the input of the control circuit 209. The circuit 511 is adapted to provide, at its output, a signal substantially proportional to the energy of the incident X-rays 105 captured by the photodetector 201. By way of example, the circuit 511 is produced by a structure identical or analogous to those described in the publication by B. Dierickx et al. entitled “X-ray Photon Counting and Two-Color X-Ray Imaging Using Indirect Detection”, Sensors, 2016, 16, 764.

[0077] In the example illustrated in Figure 5, potentials Vsn' and Vo' are respectively present at node 501 and at the output of the signal shaping circuit 511.

[0078] In the example shown, the control circuit 209 comprises a multi-level comparator 521, one input of which is connected to the output of the signal shaping circuit 511. The multi-level comparator 521 comprises, for example, more precisely, as in the example illustrated in FIG. 5, three comparators 523R, 523G and 523B. The comparators 523R, 523G and 523B each comprise an inverting input (-) connected to the input of the multi-level comparator 521, i.e. connected to the output of the circuit 511. The connections of the inverting inputs of the comparators 523R, 523G and 523B to the input of the multi-level comparator 521 have not been shown in FIG. 5 so as not to overload the drawing. Furthermore, comparators 523R, 523G and 523B include non-inverting (+) inputs connected to application nodes of a potential VR, VG and VB, respectively.For example, the RV potential is strictly greater than the LV potential and the VB potential is strictly less than the LV potential.

[0079] In the illustrated example, the control circuit 209 further comprises three transistors 319R, 319G and 319B identical or analogous to the transistor 319 previously described in relation to FIG. 3. In this example, the transistors 319R, 319G and 319B each comprise a conduction terminal, for example a drain electrode, connected to a first conduction terminal, for example an anode electrode, of a light-emitting diode 211R, 211G or 211B, and another conduction terminal, for example a source electrode, connected to the node 321 for applying the potential Va. Each transistor 319R, 319G, 319B further comprises a control terminal, for example a gate electrode, connected to the output of the comparator 523R, 523G, 523B by an inverter (not detailed in figure 5), for example analogous to the inverter 317 of figure 3.

[0080] Similarly to the light-emitting diode 211 previously described in relation to FIG. 3, the light-emitting diodes 211R, 211G and 211B comprise another conduction terminal, for example a cathode electrode, connected to the node 213 for applying the potential -Vk.

[0081] In the example shown in Figure 5, the light-emitting diodes 211R, 211G and 211B are respectively traversed by currents IledR, IledG and IledB, and respectively emit the radiations 109R, 109G and 109B. For example: - the 109R radiation is included in a first range of wavelengths of visible light, corresponding for example to red light; - the 109G radiation is included in a second range of wavelengths of visible light, different from the first range and corresponding for example to green light; and - the 109B radiation is included in a third range of wavelengths of visible light, different from the first and second ranges and corresponding for example to blue light.

[0082] Figure 5 illustrates a case in which the multi-level comparator 521 of the control circuit 209 comprises three comparators connected respectively to the control terminals of three transistors, and in which the emission element 107 comprises three light-emitting diodes. This example is however not limiting. As a variant, the multi-level comparator 521 may comprise a number of comparators other than three, for example equal to two or greater than three, each associated with a transistor similar or identical to the transistors 319R, 319G and 319B, and / or the emission element 107 may comprise a number of light-emitting diodes other than three, for example equal to two or greater than three. Furthermore, the number of light-emitting diodes of the emitting element 107 may be different from the number of comparators 523 and the number of transistors 319 of the control circuit 209.

[0083] Figure 6 is a timing diagram illustrating, schematically and partially, an example of operation of the pixel PIX of Figure 5. The timing diagram of Figure 6 comprises a curve 601 illustrating an example of evolution, as a function of time (t), of the potential Vo' present at the output of the signal shaping circuit 511. The timing diagram of Figure 6 further comprises three curves 603R, 603G and 603B illustrating an example of evolution, as a function of time t, of the currents IledR, IledG and IledB, respectively.

[0084] Between an instant t0' and an instant tl', subsequent to the instant t0', the potential Vo' present at the output of the circuit 511 is equal to a minimum value Vmin. The currents IledR, IledG and IledB are for example at a low level, for example substantially zero, between the instants t0' and tl'. This corresponds for example to a period during which no X-ray radiation is detected by the photodetector 201.

[0085] In the example shown, at time tl', the incident X-ray 105 is detected by the photodetector 201. Between time tl' and a time t2', subsequent to time tl', a pulse of potential Vo' having a maximum value greater than the potential VR is produced at the output of the circuit 511. The currents IledR, IledG and IledB then each switch, at time tl', from a low level to a high level and then, at time t2', from the high level to the low level.

[0086] Curves 603R, 603G and 603B illustrate, between time t2' and a time t3', subsequent to time t2', several other pulses of the currents IledR, IledG and IledB similar to those present between times tl' and t2'. These pulses of the currents IledR, IledG and IledB result, as explained above, from pulses of the potential Vo' greater than the potential VR.

[0087] Between the instant t3 ' and an instant t4 ', subsequent to the instant t3 ' , the curves 603G and 603B illustrate other pulses of the currents IledG and IledB, for example analogous to the pulses present between the instants t0 ' and t3 ' . Between the instants t3 ' and t4 ', the current IledR is for example substantially zero. The pulses of the currents IledG and IledB between the instants t3 ' and t4 ' differ for example from the pulses of the currents IledR, IledG and IledB between the instants t0 ' and t3 ' in that they result from pulses of the potential Vo ' each having a maximum value between the potential VG and the potential VR. This comes for example from the fact that the photodetector 201 captures, during a ME phase between times t3' and t4', an incident X-ray of lower energy than during another HE phase between times t0' and t3'.

[0088] Similarly, between the instant t4' and an instant t5', subsequent to the instant t4', the curve 603B illustrates still other pulses of the current IledB, for example analogous to the pulses present between the instants t3' and t4'. Between the instants t4' and t5', the currents IledR and IledG are for example substantially impaired. The pulses of the current IledB between the instants t4' and t5' differ for example from the pulses of the currents IledG and IledB between the instants t3' and t4' in that they result from pulses of the potential Vo' each having a maximum value between the potential VB and the potential VG. This comes for example from the fact that the photodetector 201 captures, during a LE phase between times t4' and t5', X-rays of lower energy than during the ME phase between times t3' and t4'.

[0089] In order to simplify the drawing, Figure 6 illustrates a case in which the pulses of the current IledR, IledG or IledB repeat substantially periodically, at a frequency f ', between the instant t0 ' and the instant t3', t4 ' or t5'. However, in practice, the repetition frequency of the pulses of the current IledR, IledG, IledB may vary between the instant t0 ' and the instant t3', t4 ' or t5', for example as a function of an intensity, or a flux, of the incident X 105 radiation. At constant energy, for example between the instants t3 ' and t4 ', the repetition frequency of the pulses of the currents IledG and IledB is all the higher as the intensity of the X 105 radiation is high.

[0090] The BIX pixel shown above in relation to Figures 5 and 6 has the advantage of being able to represent X-rays, or X-ray photons, of different energies using three different colours. More precisely: - if the energy of the X-ray radiation is such that the potential Vo' is greater than the potential VR (phase HE), the diodes 211R, 211G and 211B are lit; - if the energy of the X-ray radiation is such that the potential Vo' is between VG and VR (ME phase), the diodes 211G and 211B are on and the diode 211R is off; - if the energy of the X-ray radiation is such that the potential Vo' is between VB and VG (LE phase), the diode 211B is on and the diodes 211R and 211G are off; and - if the energy of the X-ray radiation is such that the potential Vo' is less than VB, the diodes 211R, 211G and 211B are switched off.

[0091] Alternatively, the person skilled in the art is able to provide, from the indications of the present description, an electronic circuit interposed for example between the multi-level comparator 521 and the transistors 319R, 319G and 319B and comprising logic making it possible to switch on only one of the diodes 211R, 211G and 211B for each phase HE, ME and LE, respectively.

[0092] In the examples set out above, the image capture and display device 100 is devoid of circuits for addressing the matrices of detection elements 103 and emission elements 107. The device 100 is further devoid of circuits and components for storing, or memorizing, images acquired by the detection elements 103 or images to be displayed by the emission elements 107.

[0093] Furthermore, each pixel PIX of the device 100 has autonomous operation, insofar as each pixel PIX does not receive any external control signal. The device 100 is in particular devoid of a circuit for controlling the pixels PIX external to the pixels PIX. In the example shown, each pixel PIX of the device 100 receives only one or more power supply signals, for example signals having a substantially constant voltage value.

[0094] An advantage of the device 100 is that it has lower weight, size, complexity, power consumption, manufacturing costs and / or latency than existing image capture and display devices.

[0095] Figure 7A, Figure 7B, Figure 70, Figure 7D, Figure 7E, Figure 7F, Figure 7G, Figure 7H, Figure 71, Figure 7J, Figure 7K and Figure 7L illustrate, by means of schematic and partial sectional views, structures obtained at the end of steps of a method of manufacturing the device 100 of Figure 1 according to one embodiment.

[0096] Figure 7A illustrates more precisely a structure obtained at the end of a step of forming a stack active light-emitting diode 703, or active LED stack, on a face 701T side of a support substrate 701 (the top face of the substrate 701, in the orientation of FIG. 7A). For example, the support substrate 701 is a wafer or piece of wafer made of a semiconductor material, for example silicon. Alternatively, the support substrate 701 may be sapphire or glass.

[0097] The support substrate 701 is coated, on one of its faces, with a semiconductor layer 705. In the example shown, the semiconductor layer 705 is located on and in contact with the face 701T of the support substrate 701. For example, the layer 705 is made of silicon.

[0098] The semiconductor layer 705 is for example coated with another semiconductor layer 707, for example a layer made of the same material as the layer 705. In the example shown, the semiconductor layer 707 is located on and in contact with a face of the semiconductor layer 705 opposite the support substrate 701. By way of example, the semiconductor layer 707 is doped with a first conductivity type, for example the N type (N+ doping). The semiconductor layer 705 for example acts as a buffer layer between the support substrate 701 and the semiconductor layer 707.

[0099] In the example shown, the semiconductor layer 707 is coated with an active layer 709. The active layer 709 is, in this example, located on and in contact with a face of the semiconductor layer 707 opposite the substrate 701 (the upper face of the layer 707, in the orientation of FIG. 7A). For example, the layer 709 comprises quantum dots or wells.

[0100] In the illustrated example, the active layer 709 is coated with another semiconductor layer 711. The semiconductor layer 711 is, in this example, located on and in contact with a face of the active layer 709 opposite the support substrate 701 (the upper face of the layer 709, in the orientation of FIG. 7A). The semiconductor layer 711 is for example doped with a conductivity type opposite to that of the semiconductor layer 705 (the P type, in this example).

[0101] In the illustrated example, the semiconductor layers 705 and 707, the active layer 709 and the semiconductor layer 711 form the light-emitting diode stack 703.

[0102] For example, in the case where the substrate 701 is made of silicon, the semiconductor layer 705, the semiconductor layer 707, the active layer 709 and the semiconductor layer 711 are successively formed by epitaxial growth from the face 701T of the support substrate 701.

[0103] In the example shown, the semiconductor layer 711 is coated with a conductive layer 713. The conductive layer 713 is, in this example, located on and in contact with a face of the semiconductor layer 711 opposite the support substrate 701 (the upper face of the layer 711, in the orientation of FIG. 7A). For example, the conductive layer 713 is made of a metal, for example aluminum or titanium, or a metal alloy. The conductive layer 713 makes it possible, for example, to make an ohmic contact with the semiconductor material of the layer 711. The conductive layer 713 may have a single-layer or multi-layer structure.

[0104] Figure 7B illustrates more precisely a structure obtained at the end of a step of forming the circuits 205 of the pixels PIX of the device 100. The step described in relation to Figure 7B can be carried out indifferently before, during or after the step previously described in relation to Figure 7A.

[0105] In the example shown, the structure comprises a support substrate 721. For example, the support substrate 721 is a wafer or piece of wafer made of a semiconductor material, for example silicon.

[0106] The support substrate 721 is for example coated, on one of its faces, with an insulating layer 723. In the example shown, the insulating layer 723 is located on and in contact with a face 721T of the support substrate 721 (the upper face of the substrate 721, in the orientation of FIG. 7B). For example, the insulating layer 723 is made of an oxide, for example silicon oxide.

[0107] The insulating layer 723 is for example coated with a semiconductor layer 725, for example a silicon layer. In the example shown, the semiconductor layer 725 is located on and in contact with a face of the insulating layer 723 opposite the support substrate 721.

[0108] For example, the support substrate 721, the insulating layer 723 and the semiconductor layer 725 are part of a SOI (Silicon On Insulator) type substrate. In this case, the insulating layer 723 corresponds to the buried oxide (BOX) layer of the SOI substrate.

[0109] In this example, the circuits 205 are located on the side of the face 721T of the semiconductor substrate 721. For example, the circuits 205 are formed in and on the semiconductor layer 725.

[0110] Although this has not been detailed in figure 7B in order not to overload the drawing, the structure comprises for example in addition an interconnection stack or network located on the semiconductor layer 725. The interconnection stack comprises for example a stack of conductive layers, for example metal layers or metallization levels, and alternating insulating layers. The interconnect stack comprises, for example, conductive tracks formed in the conductive layers and conductive vias, for example, metal vias, interconnecting conductive tracks located in different conductive layers.

[0111] In the example shown, only a conductive layer 727 of the interconnect stack furthest from the support substrate 721, called the last metallization level, has been symbolized by disjointed hatched rectangles in FIG. 7B.

[0112] The semiconductor layer 725 of the structure illustrated in FIG. 7B corresponds for example to the semiconductor substrate 101 of the device 100 of FIG. 1.

[0113] Although Figure 7B illustrates an example in which the circuits 205 are formed in and on an SOI-type substrate, this example is not limiting. Alternatively, the circuits 205 may be formed in and on a bulk semiconductor substrate, for example, the same or similar to the support substrate 721 of Figure 7B.

[0114] In the example shown, the conductive layer 727 is coated with another conductive layer 729. The conductive layer 729 is, in this example, located on and in contact with a face of the conductive layer 727 opposite the substrate 721 (the upper face of the layer 727, in the orientation of FIG. 7B). For example, the conductive layer 729 is made of a metal, for example titanium, or a metal alloy. The conductive layer 729 is for example made of the same material as the conductive layer 713.

[0115] Figure 7C illustrates more precisely a structure obtained at the end of a subsequent step of transferring the structure previously described in relation to Figure 7A. on the structure previously described in relation to Figure 7B.

[0116] For example, the structure previously described in relation to FIG. 7A is turned over with respect to the orientation of FIG. 7A and then brought into contact, by the face of the conductive layer 713 opposite the support substrate 701 (the lower face of the layer 713, in the orientation of FIG. 7C), with the face of the conductive layer 729 opposite the substrate 721 (the upper face of the layer 729, in the orientation of FIG. 7C). During this step, the structure comprising the support substrate 701 and the active light-emitting diode stack 703 is fixed to the interconnect stack coated with the conductive layer 729.

[0117] For example, the attachment is achieved by molecular bonding between the two surfaces in contact. Molecular bonding is, for example, more precisely of the metal-metal type, each surface comprising a metallic layer.

[0118] The support substrate 701 is then, for example, removed. The support substrate 701 is, for example, completely removed, for example by grinding the side of the face 721T of the substrate 721.

[0119] Figure 7D more specifically illustrates a structure obtained following a subsequent step of forming trenches 731, or openings, in the active stack of light-emitting diodes 703.

[0120] The trenches 731 are for example formed by plasma etching through a mask (not shown) previously deposited on the side of the upper face of the active stack 703. The trenches 731 extend from the upper face of the semiconductor layer 705 through the layers 705, 707, 709 and 711 of the active diode stack. electroluminescent layer 703, the etching being for example interrupted on the upper face of the conductive layer 713. The formation of the trenches 731 through the active stack 703 leads to delimiting, in the active stack 703, a plurality of LEDs 733. Each LED 733 corresponds to an island or mesa formed in the stack 703 and surrounded laterally by a trench 731. Each LED 733 thus comprises a vertical stack comprising, in order from the upper face of the conductive layer 713, a portion of the semiconductor layer 711, corresponding to the anode of the LED, a portion of the emissive layer 709, a portion of the semiconductor layer 707, corresponding to the cathode of the LED, and a portion of the semiconductor layer 707. The trenches 731 can be aligned with respect to marks previously formed on the circuit 205 underlying.More particularly, after the deposition of the etching mask but before the formation of the trenches 731, marks previously formed on the substrate 721 can be released by etching the mask and the active stack 703 in peripheral zones of the assembly, these marks then serving as alignment marks for the positioning of the mask used to produce the trenches 731. In the example shown, each LED 733 is located, in vertical projection, opposite a single contact recovery element 735, for example a conductive pad, formed in the conductive layer 727.

[0121] Furthermore, Figure 7D illustrates a subsequent step of removing, for example by plasma etching, the portions of the metal layers 729 and 713 located at the bottom of the trenches 731, so as to extend the trenches 731 to the last conductive layer 727 of the interconnection stack. At the end of this step, the anodes of the different LEDs 733 are electrically isolated from each other by the trenches 731, and each LED 733 has its anode connected to the portion of the underlying conductive layer 727 via the portions of the metal layers 729 and 713 remaining between the LED and a contact recovery element 735, for example a conductive pad formed in the conductive layer 727. This allows individual control of the LEDs by the circuits 205. Furthermore, at the end of this step, the upper face of other contact recovery elements 737, for example conductive pads, not coated with a portion of the active stack of light-emitting diodes 703, is uncovered.

[0122] Furthermore, Figure 7D illustrates a subsequent step of depositing an insulating layer 741, for example a passivation layer made of silicon oxide or nitride or aluminum oxide, on the side walls and on the bottom of the trenches 731. The layer 741 is for example further deposited on the upper faces of the portions of the active stack 703 of the LEDs 733. The layer 741 is for example deposited on the entire upper face of the structure by a conformal deposition method, for example by successive monoatomic layer deposition (ALD).

[0123] The parts of the layer 741 located at the bottom of the trenches 731 are for example then eliminated. During this step, the layer 741 is kept on the side walls, or flanks, of the trenches 731. For this, the layer 741 is for example etched by vertical anisotropic etching, which also leads to removing the layer 741 on the upper faces of the portions of the active stack 703 surmounting the LEDs 733.

[0124] Figure 7E illustrates more precisely a structure obtained at the end of a subsequent step of depositing a conductive layer 751, for example a metal layer, on the side of the upper face of the structure of Figure 7D.

[0125] In the example shown, the conductive layer 751 fills the trenches 731. In other words, the layer 751 completely fills the spaces left free between the LEDs 733. In the example shown, the conductive layer 751 is flush with the upper face of the active stack of light-emitting diodes 703. By way of example, a chemical-mechanical polishing operation is implemented in order to remove portions of the conductive layer 751 coating the upper faces of the LEDs 733.

[0126] Furthermore, another conductive layer 753 is deposited during this step on the upper face of the structure. For example, the conductive layer 753 forms a cathode electrode common to the LEDs 733. The conductive layer 751 is then for example intended to form contact recovery elements making it possible to connect the pads 737 to the conductive layer 753. For example, the conductive layer 755 is a layer made of a transparent and conductive oxide, for example indium-tin oxide, or a thin metallic layer, for example silver.

[0127] Figure 7F illustrates more precisely a structure obtained at the end of a subsequent step of transferring the structure previously described in relation to Figure 7E onto a temporary support substrate 755.

[0128] For example, the structure previously described in relation to FIG. 7E is turned over with respect to the orientation of FIG. 7E and then brought into contact, by the face of the conductive layer 753 opposite the support substrate 721 (the lower face of the layer 753, in the orientation of FIG. 7F), with the upper face of the temporary support substrate 755. For example, the fixing is obtained by molecular bonding between the two surfaces brought into contact.

[0129] The support substrate 721 is then, for example, removed. The support substrate 721 is, for example, completely removed, for example by grinding the upper face side of the temporary support substrate 755. Using an SOI type substrate has the advantage of facilitating the removal of the support substrate 721 during this step, for example by allowing a stop on the insulating layer 723.

[0130] Furthermore, during this step, conductive vias 757 are formed from the face of the insulating layer 723 opposite the temporary support substrate 755 (the upper face of the insulating layer 723, in the orientation of FIG. 7F). In the example shown, the conductive vias 757 pass through the insulating layer 723 and penetrate into the thickness of the semiconductor layer 725. Although this has not been detailed in FIG. 7F so as not to overload the drawing, the conductive vias 757 are for example connected to the circuits 205. For example, the conductive vias 757 are formed by making openings passing through the insulating layer 723 and penetrating into the semiconductor layer 725, the sides and the bottom of the openings being for example then passivated before completely filling the openings with metal regions.

[0131] Figure 7G illustrates more precisely a structure obtained at the end of a subsequent step of transferring the structure previously described in relation to Figure 7F onto another temporary support substrate 761.

[0132] For example, the structure previously described in relation to Figure 7F is turned over with respect to the orientation of Figure 7F and then brought into contact, by the face of the insulating layer 723 opposite the support substrate 755 (the lower face of the layer 723, in the orientation of Figure 7G), with the upper face of the support substrate 755. temporary support 761. For example, the fixing is obtained by gluing between the two surfaces brought into contact, for example by means of a layer of glue.

[0133] The support substrate 755 is then, for example, removed. The support substrate 755 is, for example, completely removed, for example by grinding the upper side of the temporary support substrate 761.

[0134] Figure 7H illustrates more precisely a structure obtained at the end of a subsequent step of forming, from the upper face of the structure of Figure 7G, trenches 763 extending vertically, from the face of the conductive layer 753 opposite the temporary support substrate 761 (the upper face of the layer 753, in the orientation of Figure 7H), to the upper face of the substrate 761. The trenches 763 laterally delimit a plurality of semiconductor chips corresponding to elementary chips 765 of the PIX pixels of the image capture and display device 100. The trenches 763 are for example formed by plasma etching, by sawing, or by any other suitable cutting method.

[0135] Figure 71 illustrates more precisely a structure obtained at the end of a subsequent step of fixing the elementary chips 765 on the upper face of the same transfer substrate 767. The transfer substrate 767 is for example devoid of contact recovery elements. For example, the transfer substrate 767 is made of glass.

[0136] The structure of figure 7H is for example turned over so as to place the elementary chips 765 opposite the transfer substrate 767. The elementary chips 765 are then fixed, for example by gluing, on the upper face of the transfer substrate 767.

[0137] Once attached to the transfer substrate 767, the elementary chips 765 are detached from the temporary support substrate 761, and the latter is removed. For example, the chips 765 are detached by mechanical detachment or by detachment using a laser beam.

[0138] In the example shown, the pitch (i.e., the center-to-center distance, in front view) of the elementary chips 765 on the transfer substrate 767 is a multiple of the pitch of the elementary chips 765 on the temporary support substrate 761. Thus, only a portion of the elementary chips 765 (one out of two, in the example shown) are simultaneously transferred from the temporary support substrate 761 to the transfer substrate 767. The other chips remain attached to the temporary support substrate 761. These remaining chips can then be transferred to another portion of the transfer substrate 767. Alternatively, the transfer of these remaining elementary chips can be carried out on another transfer substrate.

[0139] Figure 7J illustrates more precisely a structure obtained at the end of a subsequent step of depositing an insulating layer 769 on the side of the upper face of the transfer substrate 767.

[0140] In the example shown, the insulating layer 769 coats parts of the upper face of the transfer substrate 767 not coated with the elementary chips 765, as well as the sides and the upper faces of the elementary chips 765. In this example, the insulating layer 769 fills all the free spaces extending laterally between the elementary chips 765. The insulating layer 769 plays for example the role of a planarization layer. For example, the insulating layer 769 is made of a polymer material.

[0141] Furthermore, during this step, the conductive vias 757 are extended to the upper face of the insulating layer 769. For example, openings are formed in the thickness of the insulating layer 769 directly above the conductive vias 757. These openings, which open onto the conductive vias 757, are for example then passivated and then filled with a conductive material, for example the same material as that of the conductive vias 757.

[0142] Figure 7K illustrates more precisely a structure obtained at the end of a subsequent step of forming an interconnection network 771, or interconnection stack, on the side of the upper face of the structure of Figure 7J.

[0143] The interconnection network 771 comprises, for example, a stack of conductive layers, for example, metal layers or metallization levels, and alternating insulating layers. The interconnection network 771 comprises, for example, conductive tracks formed in the conductive layers and conductive vias, for example, metal vias, interconnecting conductive tracks located in different conductive layers. In FIG. 7K, the metal layers of the interconnection network 771 have been symbolized by hatched rectangles.

[0144] Furthermore, during this stage, electrodes 773, for example lower electrodes of the photodetectors 201 of the device 100, are formed on the side of the upper face of the structure. In the example shown, the electrodes 773 are located on and in contact with a face of the interconnection network 771 opposite the transfer substrate 767 (the upper face of the interconnection network 771, in the orientation of FIG. 7K).

[0145] For example, a conductive layer is deposited over the entire upper face of the structure, then trenches 775 are for example then formed throughout the thickness of the conductive layer so as to delimit parts of the conductive layer insulated from each other and each forming one of the electrodes 773.

[0146] Figure 7L illustrates more precisely a structure obtained at the end of a subsequent step of forming diodes 781, for example PIN diodes (from the English “Positive Intrinsic Negative”) on the side of the upper face of the structure of figure 7K.

[0147] For example, an active PIN diode stack is deposited on the entire upper face of the structure of FIG. 7K. The active PIN diode stack is then structured, for example, by photolithography and then etching, so as to retain only parts of the PIN diode stack each located directly above one of the electrodes 773. For example, the PIN diode stack is based on amorphous silicon, indium-gallium-zinc oxide (IGZO), or one or more organic materials.

[0148] Furthermore, during this step, an insulating layer 783 is then deposited on the side of the upper face of the structure. In the example shown, the insulating layer 783 fills, i.e. completely fills, all the free spaces extending laterally between the PIN diodes 781 and is flush with the upper face of the PIN diodes 781.

[0149] Furthermore, during this step, a conductive layer 785 is deposited on the side of the upper face of the structure. In the example shown, the conductive layer 785 is located on and in contact with the upper faces of the PIN diodes 781 and the insulating layer 783. The conductive layer 785 constitutes for example an electrode common to all the PIN diodes 781 of the device 100. By way of example, the conductive layer 785 is made of an oxide transparent and conductive, for example indium tin oxide (ITO).

[0150] Furthermore, during this step, a scintillator 787 is then formed on the side of the upper face of the structure. In the example shown, the scintillator 787 is located on and in contact with the upper face of the conductive layer 785. The scintillator 787 comprises a layer of a scintillation material, for example cesium iodide (Csl) in crystalline form, gadolinium oxide (GadOx), or any other suitable scintillation material, i.e. a material emitting light following a deposition of energy by interaction with X-rays, extending continuously over the entire upper face of the conductive layer 785.

[0151] The scintillator 787 is for example formed separately on a growth substrate, then transferred to the upper face of the conductive layer 785. Alternatively, the scintillator 787 is formed directly on the upper face of the conductive layer 785.

[0152] In the structure of FIG. 7L, the detection elements 103 comprise, for example, the diodes 781, and the emission elements 107 comprise, for example, the light-emitting diodes 733 formed in the elementary chips 765.

[0153] The method described above in relation to FIGS. 7A to 7L can be used to produce a device 100 comprising a plurality of elementary chips (“smart pixels”) arranged, for example in a matrix arrangement, on the same transfer substrate. For example, the transfer substrate is a flexible substrate (“flex”, in English), that is to say a substrate capable of conforming to the shape of a rounded object.

[0154] Figure 8 is a schematic and partial top view of the interconnection network 771 of the device 100.

[0155] In the example shown, the interconnection network 771 comprises two metallization levels 801 and 803 symbolized, in FIG. 8, by hatched elements. In the orientation of FIG. 8, the metallization level 801 comprises mainly vertical conductive tracks and the metallization level 803 comprises mainly horizontal conductive tracks.

[0156] In the illustrated example, each elementary chip 765 comprises: - a pad 811a connected to a conductive track 821a of the metallization level 801, for example a track for applying the supply potential Va; - a pad 811b connected to a conductive track 821b of the metallization level 801, for example a track for applying the reference potential; and - a pad 811c connected to a conductive track 821c of the metallization level 801, for example a track for applying the potential Vdd.

[0157] Furthermore, in this example, each elementary chip 765 comprises: - a pad 813a connected to a conductive track 823a of the metallization level 803, for example a track for applying the potential Vref; and - a pad 813b connected to a conductive track 823b of the metallization level 803, for example a track for applying the potential -Vk.

[0158] This example is however not limiting, the interconnection network 771 being able, more generally, to have any structure allowing the application of signals adapted to allow the operation of each elementary chip 765.

[0159] Figure 9A and Figure 9B illustrate, by means of schematic and partial sectional views, structures obtained at the end of successive steps of a method of manufacturing the device 100 of Figure 1 according to another embodiment.

[0160] Figure 9A illustrates more precisely a structure obtained at the end of a step of forming a converter 900 based on a perovskite material.

[0161] In the example shown, the converter 900 more precisely comprises an active layer 901 made of a perovskite material. A perovskite material is for example a material having a crystal structure of the form ABX3, where A and B are two positively charged ions, or cations, and where X is a negatively charged ion, or anion. The anion X, typically an oxygen anion (O~), is bound to the cations A and B. The cations A and B may be of different sizes, the cations A being for example larger than the cations B. The present description is however not limited to these examples. As a variant, the site A and / or the site B of the perovskite material of the active layer 901 may have a configuration of the type Al x -iA2 x and / or Bl y-1 B2 y, and the anion X may deviate from the ideal coordination configuration, for example when the ions at sites A and B undergo changes in their respective oxidation states. Alternatively, the active layer may be based on amorphous selenium, gallium arsenide, mercury iodide, lead oxide, or cadmium-zinc telluride.

[0162] In the orientation of Figure 9A, the converter 900 comprises, on its lower face side, electrodes 903 located under and in contact with the active layer 901. In the orientation of Figure 9A, the converter 900 further comprises, on its upper face side, a common electrode 905.

[0163] Figure 9B illustrates more precisely a structure obtained at the end of a subsequent step of transferring the converter 900 of Figure 9A onto the structure previously described in relation to Figure 7K.

[0164] For example, the converter 900 is brought into contact, by the faces of the electrodes 903 opposite the active layer 901 (the lower faces of the electrodes 903, in the orientation of FIG. 9B), with the upper faces of the electrodes 773 opposite the substrate 767 (the upper faces of the electrodes 773, in the orientation of FIG. 9B). During this step, the converter 900 is fixed to the interconnect stack 771.

[0165] For example, the attachment is achieved by molecular bonding between the two surfaces in contact. Molecular bonding is, for example, more precisely of the metal-metal type, each surface comprising a metallic layer.

[0166] In the example shown, the electrodes 773 have, in top view, lateral dimensions substantially equal to those of the electrodes 903. This example is however not limiting, the electrodes 773 being able, as a variant, to have lateral dimensions different from those of the electrodes 903, for example smaller than those of the electrodes 903.

[0167] The device of Figure 9B is for example used to restore color images characteristic of the captured X-ray radiation, for example by means of direct conversion and photon counting.

[0168] 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, although that the described embodiments take as an example a case in which the matrices of detection elements 103 and display elements 107 have a substantially identical pitch, the person skilled in the art is able to predict, from the indications of the present description, that the matrix of display elements 107 of the device 100 has a different pitch, for example greater, than that of the matrix of detection elements 103.

[0169] Finally, the practical implementation of the described embodiments and variants is within the reach of the person skilled in the art from the functional indications given above. In particular, the described embodiments are not limited to the particular examples of materials and dimensions mentioned in the present description.

Claims

CLAIMS 1. Electronic device (100) for capturing and displaying images comprising a plurality of pixels (DIX) formed in and on a semiconductor substrate (101; 705), each pixel comprising: - a detection element (103) of X-ray radiation (105), located on the side of a first face (101F) of the semiconductor substrate (101); - a visible light (109) emitting element (107), located on the side of a second face (101R) of the semiconductor substrate opposite the first face; and - a circuit (205) located in and on the semiconductor substrate and connecting the detection element to the emission element, the device (100) being devoid of a pixel control circuit (PIX) external to the pixels (PIX).

2. Device (100) according to claim 1, wherein the circuit (205) comprises: - an acquisition circuit (207) located in and on the semiconductor substrate (101; 705) and adapted to provide an acquisition signal representative of an intensity of the X-ray radiation (105) received by the detection element (103) of the pixel (PIX); and - a control circuit (209) located in and on the semiconductor substrate and adapted to apply a control signal to the emission element (107) of the pixel.

3. Device (100) according to claim 2, wherein the acquisition circuit (207) and the control circuit (209) are analog circuits.

4. Device (100) according to claim 2, in which: - each detection element (103) comprises a photodetector (201); - each acquisition circuit (207) comprises a comparator (301) having an inverting input connected to a conduction electrode of the photodetector; and - each control circuit (209) comprises an inverter (317) having an input connected to an output of the comparator and an output connected to a gate of a MOS transistor (319), the MOS transistor comprising a conduction electrode connected to the emission element (107).

5. Device (100) according to claim 4, wherein each emitting element (107) comprises a single light-emitting diode (211).

6. Device (100) according to claim 5, wherein the light-emitting diode (211) is controlled by a control signal having pulses repeating at a frequency substantially proportional to an intensity of the X-ray radiation (105) detected by the detection element (103).

7. Device (100) according to claim 2, in which: - each detection element (103) comprises a photodetector (201); - each acquisition circuit (207) comprises a signal shaping circuit (511); and - each control circuit (209) comprises a multi-level comparator (521) comprising an input connected to an output of the signal shaping circuit and at least two outputs each connected to a gate of a MOS transistor (319R, 319G, 319B) by an inverter (317), each MOS transistor comprising a conduction electrode connected to a diode electroluminescent (211R, 211G, 211B) of the emitting element (107).

8. Device (100) according to claim 7, wherein each emitting element (107) comprises exactly three light-emitting diodes (211R, 211G, 211B).

9. Device (100) according to any one of claims 1 to 8, in which the detection elements (103) are located opposite the emission elements (107).

10. Device (100) according to any one of claims 1 to 9, wherein the detection elements (103) and the emission elements (107) are arranged respectively in first and second matrices, the first and second matrices having substantially identical pitches.

11. Device (100) according to any one of claims 1 to 10, comprising as many detection elements (103) as emission elements (107). 12 Device (100) according to any one of claims 1 to 11, further comprising a scintillator (787) surmounting the detection elements (103).

13. Device (100) according to any one of claims 1 to 11, further comprising a converter (900) based on a perovskite material overlying the detection elements (103).

14. Method for manufacturing a device (100) according to any one of claims 1 to 13, comprising a step of transferring, by molecular bonding, a structure comprising the detection elements (103) and the circuits (205) onto another structure comprising the emission elements (107).

Images