Device for acquiring a 2D image and a depth image of a scene

Abstract

Device for acquiring a 2D image and a depth image of a scene. This description relates to a method for manufacturing a device (100) for acquiring a 2D image and a depth image, the method comprising the following steps: a) forming, on a first face (101F) of a first semiconductor support substrate (101), a first sensor (C1) comprising a plurality of depth pixels (P1); b) forming, in the first support substrate (101), on the side of a second face (101R) of the first substrate opposite to the first face (101F), at least one optical concentrator (103); and c) forming, in and on a second semiconductor substrate (123), a second sensor (C2) comprising a plurality of 2D image pixels (P2); and d) attach the second sensor (C2) to the first support substrate (101) on the side of the second face (101R) of the first support substrate (101). Figure for the abbreviation: Fig. 1

Description

Title of the invention: Device for acquiring a 2D image and a depth image of a scene. Technical field

[0001] This description relates generally to image acquisition devices. More specifically, this description relates to image acquisition devices adapted to acquire a 2D visible image and a depth image of a scene. Previous technique

[0002] Devices for acquiring depth images of a scene, for example Time-of-Flight (ToF) sensors for a light signal emitted towards the scene and then reflected back towards the sensor by objects in the scene, have been proposed. Furthermore, structured light sensors, projecting a pattern such as fringes or a grid onto the scene and capturing an image of this pattern distorted by the relief of the objects in the scene in order to estimate their distance from the sensor, have been proposed.

[0003] In certain applications, it would be desirable to be able to simultaneously acquire a visible 2D image and a depth image of the same scene. One solution to achieve this objective is to use separate image sensors placed side by side to acquire the 2D image and the depth image. A drawback of this solution is that it implies that the image sensors have different viewpoints of the scene, thus leading to misalignment between the pixels of the corresponding images and an increase in the cost and size of the device. Summary of the invention

[0004] It would be desirable to have a device for acquiring a 2D image and a depth image of a scene which at least partially overcomes one or more of the drawbacks of known devices.

[0005] To this end, one embodiment provides a method for manufacturing a device for acquiring a 2D image and a depth image, the method comprising the following steps: a) form, on a first face of a first semiconductor support substrate, a first sensor comprising a plurality of depth pixels; b) form, in the first support substrate, on the side of a second face of the first substrate opposite to the first face, at least one optical concentrator; c) form, in and on a second semiconductor substrate, a second sensor comprising a plurality of 2D image pixels; and d) attach the second sensor to the first support substrate on the side of the second face of the first support substrate.

[0006] According to one embodiment, in step a), photodiodes of the depth pixels of the first sensor are formed in a region in a semiconductor material.

[0007] According to one embodiment, the material of said region is a III-V or II-VI semiconductor.

[0008] According to one embodiment, said region is made of indium-gallium arsenide.

[0009] According to one embodiment, said region is attached to the first substrate of support, on the side of the first face of the first support substrate, prior to the formation of the depth pixel photodiodes.

[0010] According to one embodiment, said region is attached to the first support substrate by means of an oxide layer.

[0011] According to one embodiment, the method further comprises, between steps a) and b), a step of gluing the first sensor, on the side of the first face of the first support substrate, onto an interconnect stack forming part of a third CMOS substrate.

[0012] One embodiment provides a device for acquiring a 2D image and a depth image, comprising: - a first sensor formed on a first face of a first semiconductor support substrate, the first sensor comprising a plurality of depth pixels, and at least one optical concentrator formed in the first support substrate, on the side of a second face of the first support substrate opposite the first face; and - attached to the first support substrate, on the side of the second face of the first support substrate, a second sensor formed in and on a second semiconductor substrate and comprising a plurality of 2D image pixels.

[0013] According to one embodiment, each optical concentrator is a re-fractive microlens, a diffractive microlens, a Fresnel microlens or a metasurface.

[0014] According to one embodiment, the second sensor is a color image sensor, each 2D image pixel comprising a color filter preferentially transmitting red, green or blue light.

[0015] According to one embodiment, the first and second substrates are made of monocrystalline silicon.

[0016] According to one embodiment, the depth pixels of the first sensor have a step larger than that of the 2D image pixels of the second sensor. Brief description of the drawings

[0017] These features and advantages, as well as others, will be described in detail in the following description of particular embodiments, given by way of non-limiting example, in relation to the accompanying figures, among which:

[0018] [Fig. 1] is a schematic and partial cross-sectional view of an example of a device for acquiring a 2D image and a depth image of a scene according to one embodiment; and

[0019] Figures [Fig. 2A], [Fig. 2B], [Fig. 2C], [Fig. 2D], [Fig. 2E], [Fig. 2F], and [Fig. 2G] are schematic, partial cross-sectional views illustrating steps in an example of a manufacturing process for the device of [Fig. 1] according to one embodiment. Description of embodiments

[0020] The same elements have been designated by the same reference numerals in the different figures. In particular, structural and / or functional elements common to the different embodiments may have the same reference numerals and may have identical structural, dimensional and material properties.

[0021] For the sake of clarity, only the steps and elements necessary for understanding the described embodiments have been shown and are detailed. In particular, the implementation of the photodiodes and the pixel control circuits has not been detailed, as the implementation of such pixels is within the capabilities of a person skilled in the art, based on the information provided in this description.

[0022] Unless otherwise specified, when referring to two elements connected together, this means directly connected without intermediate elements other than conductors, and when referring to two elements coupled together, this means that these two elements can be connected or linked through one or more other elements.

[0023] 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", "superior", "inferior", etc., or to orientation qualifiers, such as the terms "horizontal", "vertical", etc., reference is made, unless otherwise specified, to the orientation of the figures.

[0024] Unless otherwise specified, the expressions "approximately", "about", "substantially", and "in the order of" mean within 10%, preferably within 5%.

[0025] Fig. 1 is a schematic and partial cross-sectional view of an example of a device 100 for acquiring a 2D image and a depth image of a scene according to one embodiment.

[0026] Device 100 of [Fig. 1] comprises: - a first Cl sensor arranged on a first face 101F of a first substrate semiconductor support 101 (the upper face of substrate 101, in the orientation of [Fig.l]), the first sensor Cl comprising a plurality of depth PI pixels; - at least one optical concentrator 103 formed in the support substrate 101, on the side of a second face 101R of the substrate 101 (the lower face of the substrate 101, in the orientation of [Fig. 1]) opposite the first face 101F; and - attached to the support substrate 101, on the side of the second face 101R of the substrate 101, a second sensor C2 comprising a plurality of 2D image pixels P2.

[0027] In the example shown, the substrate 101 acts as a mechanical support for the sensor Cl and is in particular devoid of any electrical function. By way of example, the support substrate 101 is made of monocrystalline silicon.

[0028] In this description, the term "front face" of a substrate refers to the face of the substrate on which an interconnection stack associated with elements formed in and / or on the substrate is made, while the term "back face" of a substrate refers to the face of the substrate opposite its front face.

[0029] In practice, the device 100 is intended to be used in combination with a light source emitting radiation in a wavelength range detected by the depth pixels of the sensor Cl, for example, an infrared source. In the case of a time-of-flight (ToF) depth measurement, the light source is, for example, a laser source emitting at a wavelength, or in a narrow wavelength range, outside the visible spectrum, for example, in the near-infrared (short-wave infrared - SWIR). By way of example, the light source is a laser source whose main emission peak has a central wavelength between 700 and 1500 nm, preferably between 1100 and 1500 nm, and a lower full width at half maximum (FWHM) on the order of a few nanometers, for example, less than 3 nm.In operation, the light signal produced by the light source is emitted towards the scene (for example, via one or more lenses) in the form of light pulses, such as periodic pulses. The light signal reflected back by the scene is captured by the depth pixels (PI) of sensor C1, in order to measure the time of flight of the light signal at different points in the scene and deduce the distance to the acquisition device at those points. Alternatively, the PI pixels of sensor C1 can perform depth measurements using structured light. The P2 pixels of sensor C2 are capable of capturing radiation in a range of wavelengths below 1100 nm. For example, the P2 pixels capture visible light emitted by the scene, in a wavelength range between 400 and 700 nm, to form a 2D image of the scene.

[0030] In the example shown, each pixel PI of the sensor Cl comprises a photodiode 105 having one or more localized implanted regions formed in a semiconductor region 107. In this example, the implanted region(s) are arranged on the side of the face 101F of the substrate 101 and extend vertically in the thickness of the semiconductor region 107 from the face of the region 107 opposite the substrate 101 (the top face of the region 107, in the orientation of [Fig.1]).

[0031] In the illustrated example, the sensor Cl further comprises a CMOS (Complementary Metal-Oxide-Semiconductor) substrate 108, including, for example, an interconnect stack 109, consisting of alternating dielectric and conductive layers in which contact elements 111 are formed, for example, traces and / or terminals for electrical connection, and a readout circuit 112, located on the side of a face of the interconnect stack 109 opposite the substrate 101, in which, for example, readout and address transistors for the PI pixels of the sensor Cl are formed (these transistors have not been shown in [Fig. 1] so as not to clutter the drawing). The circuit 112 is, for example, a Read-Out Integrated Circuit (ROIC).A peripheral circuit (not shown) for controlling and powering the PI pixels of sensor Cl can also be formed in the CMOS substrate 108. Although not detailed in [Fig.1], the contact resumption elements 111 can be interconnected by conductive vias.

[0032] In the example illustrated in [Fig. 1], the face 101F of the semiconductor substrate 101 is coated with a layer 113, for example, a layer transparent to the operating wavelengths of the PI pixels. The semiconductor region 107 covers a portion of the face of the layer 113 opposite the substrate 101 (the upper face of the layer 113, in the orientation of [Fig. 1]). In the example shown, the sides and the upper face of the semiconductor region 107 are coated with an electrically insulating layer 115.

[0033] Contact elements 117a, arranged above the photodiodes 105, and a contact element 117b, arranged above an area of ​​the semiconductor region 107 lacking a photodiode 105, are, for example, formed within the insulating layer 115. In the orientation of [Fig. 1], the contact elements 117a and 117b are flush with the upper surface of the insulating layer 115. In the example shown, each contact element 117a is connected to an underlying photodiode 105, for example, via a conductor 118a extending vertically within the insulating layer 115 from the contact element 117a to the corresponding photodiode 105, and the contact element 117b is connected to the semiconductor region 107, for example via a conductor 118b extending vertically in the layer insulating 115 from the contact resumption element 117b to the semiconducting region 107.

[0034] As an alternative, the contact resumption element 117b can be connected, via the via 118b, to a transparent and electrically conductive layer, for example acting as a common electrode for the photodiodes 105, interposed between the semiconducting region 107 and the transparent layer 113. In this case, the transparent and conductive layer is for example made of a transparent and conductive oxide, for example indium tin oxide (“Indium Tin Oxide” - ITO).

[0035] In the example shown, the CMOS substrate 108 of the sensor Cl covers the face of the insulating layer 115 opposite the substrate 101 (the upper face of the layer 115, in the orientation of [Fig. 1]). Contact elements 111 of the CMOS substrate 108 contact the contact elements 117a and 117b, for example, in order to connect each photodiode 105 of the sensor Cl to the readout circuit 112.

[0036] Optionally, another CMOS substrate 119 can, as in the example illustrated in [Fig. 1], be arranged on and in contact with the face of the CMOS substrate 108 opposite the semiconductor substrate 101 (the upper face of the CMOS substrate 108, in the orientation of [Fig. 1]). Although not detailed in [Fig. 1], an interconnect stack as well as memory and signal processing circuits associated with the P1 and P2 pixels of sensors C1 and C2 can be formed in the CMOS substrate 119.

[0037] In the illustrated example, each pixel P2 of the sensor C2 comprises a photodiode 121 having one or more localized implanted regions formed in a semiconductor substrate 123, for example, a single-crystal silicon substrate. In this example, the implanted region(s) of the photodiode 121 are arranged on the side of a front face 123F of the substrate 123 (the upper face of the substrate 123, in the orientation of [Fig. 1]). Each pixel P2 may further comprise one or more additional components (not shown), for example, readout and addressing transistors, formed on the side of the front face 123F of the substrate 123, for example, in the substrate 123 and on the front face 123F of the substrate 123.The sensor C2 further comprises an interconnect stack 125 consisting of alternating dielectric and conductive layers covering the front face 123F of the substrate 123, in which contact re-establishment elements 127 are formed, for example tracks and / or electrical connection terminals, connecting the pixels P2 of the sensor C2 to a peripheral control and power supply circuit (not shown). As illustrated in [Fig. 1], each photodiode 121 is, for example, connected to an overlying contact re-establishment element 127 by a conductive via 128.

[0038] The sensor C2 is, for example, a 2D color image sensor, that is to say, it comprises pixels P2 of different types, adapted to measure light intensities miners in distinct ranges of visible wavelengths. For this purpose, each pixel P2 includes a color filter 129, for example, a layer of colored resin, arranged on the rear side 123R of the substrate 123. As an example, the sensor C2 comprises three types of pixels P2. More precisely, the sensor C2 comprises, for example, first P2 pixels called blue pixels, whose color filter 129 preferentially transmits blue light; second P2 pixels called red pixels, whose color filter 129 preferentially transmits red light; and third P2 pixels called green pixels, whose color filter 129 preferentially transmits green light. In [Fig. 1], the different types of pixels P2 are not differentiated. As an example, the color filters 129 form a Bayer matrix.

[0039] In the illustrated example, each pixel P2 of the sensor C2 further includes a microlens 131 disposed on the side of the rear face 123F of the substrate 123, for example on and in contact with the color filter 129 of the pixel, adapted to focus the incident light on the photodiode 121 of the underlying pixel P2.

[0040] In this example, sensor Cl is bonded to sensor C2 by molecular bonding. For this purpose, an electrically insulating layer 133, for example made of silicon oxide, is disposed on the side of face 101R of the substrate 101 and covers, in particular, the optical concentrators 103. The face of the insulating layer 133 opposite the substrate 101 (the lower face of layer 133, in the orientation of [Fig. 1]) is brought into contact with the face of the interconnect stack 125 opposite the substrate 123 so as to achieve molecular bonding of sensor C2 to sensor Cl (or of sensor Cl to sensor C2). By way of example, the dielectric layers of the interconnect stack 125 of sensor C2 are made of the same material as layer 133, for example silicon oxide.

[0041] In device 100 of [Fig. 1], the depth pixels PI are, for example, individually controlled so as to produce a depth image with a resolution equal to the number of PI pixels of the sensor CL

[0042] In the example shown, the device 100 has as many depth PI pixels in the sensor Cl as there are 2D image P2 pixels in the sensor C2. This example is not limiting, however, as a person skilled in the art can adapt the described embodiments to a case where the sensor Cl of the device 100 has any proportion of PI pixels relative to the P2 pixels of the sensor C2, for example, one depth PI pixel for each group of four visible image P2 pixels of the sensor C2.

[0043] Furthermore, although only three depth PI pixels and three 2D image P2 pixels are shown in [Fig. 1], the device 100 can of course include more than three PI pixels and P2 pixels. For example, the device 100 contains several thousand or several million PI pixels, and several thousand or several million P2 pixels.

[0044] Furthermore, although the depth sensor Cl and the 2D image sensor C2 have, in the illustrated example, substantially identical pixel pitches PI and P2, this example is not limiting, as sensors Cl and C2 can have any pixel pitches. In this description, the term "pixel pitch" corresponds, for example, to the center-to-center distance between two adjacent pixels that are part of the same sensor. By way of example, the pixel pitch PI of sensor Cl is greater, for example, twice greater, than the pixel pitch P2 of sensor C2. In this case, the pixels PI have, in top view, a larger surface area than the pixels P2, and sensor PI has, for example, four times fewer pixels PI than sensor C2 has pixels P2.

[0045] One advantage of device 100 lies in the fact that the superposition of the depth sensor Cl and the 2D image sensor C2 allows for a reduction in size compared to a case where depth sensors and 2D image sensors are placed side by side. Another advantage of device 100 is that it allows the use of a semiconductor material other than silicon to create the PI pixels of sensor Cl, for example, a material better suited to capturing the illumination wavelength of the scene by the light source, particularly in a case where the illumination wavelength is greater than 1100 nm, i.e., beyond the sensitivity range of silicon.Furthermore, the placement of optical concentrators 103 between the 2D image pixels P2 of sensor C2 and the depth pixels PI of sensor PI advantageously optimizes the transmission of radiation received from the rear face 123R of sensor C2 to the photodiodes 105 of the PI pixels of sensor Cl. More precisely, the optical concentrators 103 of sensor Cl allow for better focusing of the radiation received from face 123R onto the photodiodes 105.

[0046] Figs. 2A, 2B, 2C, 2D, 2E, 2F and 2G are schematic and partial cross-sectional views illustrating steps, for example successive steps, of an example of a manufacturing process for device 100 of Fig. 1 according to one embodiment.

[0047] Figure 2A illustrates more particularly a step of transferring the semiconductor region 107 onto the semiconductor substrate 101, on the side of face 101F of the substrate 101. In the example shown, the region 107 is bonded to face 101F of the substrate 101 by means of the transparent layer 113. Face 101F of the substrate 101 is coated with the transparent layer 113, which is itself partially coated, once bonding has been completed, with the semiconductor region 107. The semiconductor region 107 is fixed to face 101F of the substrate 101, via layer 113, by means of a bonding "definitive". In other words, the substrate 101 is not intended to be separated from the semiconductor region 107 during subsequent steps in the fabrication process of the device 100. One advantage of implementing a definitive bonding of the region 107 to the substrate 101, compared to a case where a temporary bonding would be implemented and the substrate 101 would be removed during the fabrication of the device 100, is that it allows for the use of larger thermal budgets during subsequent steps of the process.

[0048] The bonding layer 113 is, for example, an oxide layer, for example, a silicon oxide layer. The layer 113 may have a single-layer or multi-layer structure, for example, a bilayer oxide / nitride structure comprising a silicon nitride layer coating face 101F of the substrate 101 and a silicon oxide layer coating the silicon nitride layer. More generally, a person skilled in the art is able to design one or more layers of dielectric materials to achieve the bonding of region 107 to substrate 101. Furthermore, a person skilled in the art is able to determine the thicknesses of this layer or these layers in order to optimize the bonding and the optical properties, for example, to obtain an anti-reflective function at the detection wavelength of the PI pixels of the CL sensor.

[0049] Region 107 is generally made of a material incompatible with CMOS-type processes. The material of region 107 is, for example, an inorganic semiconductor material, for example, an IILV compound comprising at least one first element from Group III, a second element from Group V, and optionally, a third element, for example, a Group III element other than the first element. By way of example, the material of region 107 is indium gallium arsenide (with the chemical formula InGaAs or InxGaAs). Alternatively, the material of region 107 may be an ILVI compound comprising at least one first element from Group II, a second element from Group VI, and optionally, a third element, for example, a Group II element other than the first element.

[0050] Fig. 2B illustrates more particularly subsequent steps in the formation of the photodiodes 105 of the PI pixels of the sensor Cl and in the realization of the insulating layer 115.

[0051] The photodiodes 105 are, for example, formed in the semiconductor region 107 by a masking and diffusion process of doping species, for example zinc atoms. Alternatively, the photodiodes 105 can be formed by ion implantation on the 101F face side of the substrate 101.

[0052] The insulating layer 115 is, for example, then deposited on the structure on the side of face 101F of the substrate 101 and then planarized, for example by chemical and mechanical polishing (CMP). The conductive vias 118a and 118b, as well as the contact re-establishment elements 117a and 117b, are then formed in layer 115, for example, by at least one photolithography and etching step, so as to form cavities in layer 115, followed by at least one step of filling these cavities with a conductive material, for example, a metal or a metal alloy. By way of example, each photodiode 105 comprises, after these steps, a first individual electrode, for example, an electrode formed by one of the contact re-establishment elements 117a, and a second electrode, for example, an electrode formed by the contact re-establishment element 117b, the second electrode being, for example, common to several or all of the photodiodes 105 of the sensor Cl.

[0053] Fig. 2C illustrates more particularly a subsequent step of transferring, for example by hybrid bonding, the structure previously described in relation to Fig. 2B onto the CMOS 108 substrate.

[0054] In the example shown, the face of layer 115 opposite the substrate 101 is placed in contact with the face of the interconnect stack 109 of the CMOS substrate 108 opposite the readout circuit 112. In the example shown, the contact resumption elements 117a and 117b flush with the face of layer 115 opposite the substrate 101 (the lower face of layer 115, in the orientation of [Fig.2C]) are brought into contact with contact resumption elements 111 flush with the face of the interconnect stack 109 opposite the readout circuit 112 (the upper face of the interconnect stack 109, in the orientation of [Fig.2C]).

[0055] Fig. 2D illustrates more particularly a structure obtained after a subsequent thinning step of the semiconductor substrate 101, from its face 101R.

[0056] The semiconductor substrate 101 is, for example, thinned by chemical-mechanical polishing. Once thinned, the substrate 101 has, for example, a thickness of between a few hundred nanometers and a few micrometers.

[0057] Fig. 2E illustrates more particularly a structure obtained at the end of a subsequent step of formation of the optical concentrator(s) 103 on the side of the face 101R of the substrate 101.

[0058] Optical concentrators 103 are, for example, produced by a technique known as "shape transfer". For this, structures identical or similar to the optical concentrators 103 are, for example, first formed in a layer of resin previously deposited on the face 101R of the substrate 101. A subsequent etching step then transfers the relief of the resin layer onto the face 101R of the substrate 101, the depth of etching from the face 101R of the substrate 101 depending on the thickness of the overlying resin layer.

[0059] In the example shown, each pixel PI of the sensor Cl comprises an optical concentrator 103 different from the optical concentrators 103 of the other pixels PI. This example is not limiting, however, as each optical concentrator 103 could, alternatively, be common to several pixels PI of the sensor Cl. Furthermore, the optical concentrators 103 are, in the example illustrated in [Fig. 2E], refractive microlenses, for example converging. This example is not limiting, however, as the optical concentrators 103 could, alternatively, be diffractive lenses, Fresnel lenses, metasurfaces, etc. A person skilled in the art is capable of adapting the indications in this description to produce these elements.

[0060] [Fig. 2F] illustrates a structure obtained after a subsequent step of deposition of layer 133 on the side of face 101R of the substrate 101.

[0061] By way of example, layer 133 is made of an oxide, for example silicon oxide. After deposition, layer 133 is, for example, planarized, for example by chemical polishing.

[0062] Although not shown, the deposition of a layer of a material with a refractive index different from that of layer 133, for example a nitride layer, such as silicon nitride, can be carried out between the fabrication of the optical concentrators 103 ([Fig. 2E]) and the deposition of layer 133 ([Fig. 2F]). In this case, the nitride layer covers, for example, the entire face 101R of the substrate 101, and layer 133 completely covers the face of the nitride layer opposite the substrate 101. A person skilled in the art can determine the material and thickness of this layer so as to optimize the optical properties, for example, to obtain an anti-reflective function, such as spectral filtering, at the detection wavelength of the PI pixels of the CL sensor.

[0063] Figure 2G illustrates in particular one step in the fabrication of sensor C2. The fabrication of sensor C2 can take place before, simultaneously with, or after the fabrication of sensor CL.

[0064] The fabrication of sensor C2 is within the capabilities of a person skilled in the art, based on the indications in this description. For example, the photodiodes 121 and the readout circuits are first formed in the semiconductor substrate 123. The interconnect stack 125 is then, for example, fabricated on the front face 123F of the substrate 123. Then, the structure previously described in relation to [Fig. 2F] is, for example, transferred, for example by molecular bonding, onto the structure previously described in relation to [Fig. 2G] so as to attach sensor C2 to sensor CL. The face of the stack 125 opposite the substrate 123 is thus kept in contact with the face of the layer 133 opposite the substrate 101.

[0065] The semiconductor substrate 123 can then be thinned, for example by chemical polishing, on the side opposite its face to the substrate 101, and then passivated. Connections between the sensors Cl and C2, not shown, are then made, for example, at the periphery, for example using TSV technology (from the English A "Through-Silicon Via" (via passing through the silicon) is used to transmit control and power signals to the pixels. Finally, the color filters 129 and microlenses 131 are formed on the back side 123R of the substrate 123.

[0066] Although not illustrated, the optional CMOS substrate 119 comprising the memory and signal processing circuits can then be attached to the CMOS substrate 108, on the side of a face of the readout circuit 112 opposite the interconnect stack 109, for example after realization of the color filters 129 and the microlenses 131.

[0067] In the process described above in relation to Figures 2A to 2G, the substrate 101 is retained after the manufacturing steps of the device 100. This advantageously allows us to take advantage of the presence of the substrate 101 to perform optical functions of light concentration.

[0068] Various embodiments and variations have been described. A person skilled in the art will understand that certain features of these various embodiments and variations could be combined, and other variations will become apparent to a person skilled in the art.

[0069] Finally, the practical implementation of the described embodiments and variants is within the reach of a person skilled in the art, based on the functional specifications given above. In particular, the described embodiments are not limited to the specific examples of materials and dimensions mentioned in this description.

Claims

Demands

1. A method for manufacturing a device (100) for acquiring a 2D image and a depth image, the method comprising the following steps: a) forming, on a first face (101F) of a first semiconductor support substrate (101), a first sensor (Cl) comprising a plurality of depth pixels (PI); b) forming, in the first support substrate (101), on the side of a second face (101R) of the first substrate opposite to the first face (101F), at least one optical concentrator (103); c) forming, in and on a second semiconductor substrate (123), a second sensor (C2) comprising a plurality of 2D image pixels (P2); and d) attaching the second sensor (C2) to the first support substrate (101) on the side of the second face (101R) of the first support substrate (101).

2. A method according to claim 1, wherein, in step a), photodiodes (105) of the depth pixels (PI) of the first sensor (Cl) are formed in a region (107) in a semiconductor material.

3. Method according to claim 2, wherein the material of said region (107) is a III-V or II-VI semiconductor.

4. Method according to claim 3, wherein said region (107) is indium-gallium arsenide.

5. Method according to claim 2, 3 or 4, wherein said region (107) is attached to the first support substrate (101), on the side of the first face (101F) of the first support substrate, prior to the formation of the photodiodes (105) of the depth pixels (PI).

6. Method according to claim 5, wherein said region (107) is bonded to the first support substrate (101) via an oxide layer (113).

7. A method according to any one of claims 1 to 6, further comprising, between steps a) and b), a step of gluing the first sensor (Cl), on the side of the first face (101F) of the first support substrate (101), onto an interconnect stack (109) forming part of a third CMOS substrate (108).

8. Device (100) for acquiring a 2D image and a depth image, comprising: - a first sensor (Cl) formed on a first face (101F) of a first semiconductor support substrate (101), the first sensor (Cl) comprising a plurality of depth pixels (PI), and at least one optical concentrator (103) formed in the first support substrate (101), on the side of a second face (101R) of the first support substrate (101) opposite to the first face (101F); and - attached to the first support substrate (101), on the side of the second face (101R) of the first support substrate (101), a second sensor (C2) formed in and on a second semiconductor substrate (123) and comprising a plurality of 2D image pixels (P2).

9. Device according to claim 8, wherein each optical concentrator (103) is a refractive microlens, a diffractive microlens, a Fresnel microlens or a metasurface.

10. Device according to claim 8 or 9, wherein the second sensor (C2) is a color image sensor, each 2D image pixel (P2) comprising a color filter (129) preferentially transmitting red, green or blue light.

11. Device according to any one of claims 8 to 10, wherein the first and second substrates (101, 123) are made of monocrystalline silicon.

12. Device according to any one of claims 8 to 11, wherein the depth pixels (PI) of the first sensor (Cl) have a pitch greater than that of the 2D image pixels (P2) of the second sensor (C2).

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