Electronic device comprising a quantum dot-based photodiode

Abstract

Electronic device comprising a quantum dot photodiode. This description relates to a device comprising a stack consisting of at least: - a first silicon photodiode (312); and - a second quantum dot photodiode (316); the first photodiode being arranged between one side of the stack configured to receive incident light and the second photodiode (316). Figure for the abstract: Fig. 2

Description

Title of the invention: Electronic device comprising a quantum dot-based photodiode. Technical field

[0001] This description relates generally to electronic devices and more specifically to optoelectronic devices comprising photodiodes and associated processes. Previous technique

[0002] A photodiode is a semiconductor component having the ability to capture radiation from the optical domain and transform it into an electrical signal.

[0003] In a common type of photodiode, the space charge region is located in a semiconductor material, usually silicon. However, silicon is poorly reactive to near-infrared (NIR) and short-wave infrared (SWIR) wavelengths. Summary of the invention

[0004] There is a need to provide devices that are sensitive to both wavelengths in the visible range and wavelengths in the infrared range.

[0005] An embodiment overcomes all or part of the disadvantages of known devices.

[0006] One embodiment provides a device comprising a stack made up of less : - of a first silicon photodiode; and - a second photodiode based on quantum dots; the first photodiode being arranged between one side of the stack configured to receive incident light and the second photodiode.

[0007] One embodiment provides a method for manufacturing a device comprising: - the formation of a first silicon photodiode; then - the formation of a second photodiode based on quantum dots so as to form a stack with the first photodiode; the first photodiode being arranged between one side of the stack configured to receive incident light and the second photodiode.

[0008] In one embodiment, the device includes a first filter, interposed between the first photodiode and the second photodiode, and configured to allow infrared wavelengths to pass through and to reflect visible wavelengths.

[0009] In one embodiment, the device includes at least a second filter, of a first color in the visible range, allowing only wavelengths of said first color and infrared wavelengths to pass through.

[0010] In one embodiment, the first photodiode is sensitive only to wavelengths in the visible range.

[0011] In one embodiment, the second photodiode is sensitive mainly to infrared.

[0012] In one embodiment, said second photodiode comprises a first layer comprising the quantum dots and doped with a first type of conductivity, and a second layer configured to conduct holes from the first layer.

[0013] In one embodiment, said second photodiode comprises a third layer comprising quantum dots and doped with a second type of conductivity, and arranged between said first layer and said second layer.

[0014] In one embodiment, the device includes an interconnection level comprising conductive interconnections arranged between the first photodiode and the second filter; in which a first via conductor, isolated from the first photodiode, connects, through the first photodiode and through the first filter, the second photodiode at the level of interconnections.

[0015] In one embodiment, the second photodiode includes a fourth layer configured to conduct electrons and block hole conduction, and to connect the first layer to the first via.

[0016] In one embodiment, said first via comprises a first portion of polysilicon and a second portion of metallic material, said second portion being arranged between the first portion and the fourth layer.

[0017] In one embodiment, said metallic material has an output work adapted to facilitate electron extraction.

[0018] In one embodiment, said first via is made of silicon and with the first or second type of conductivity, said first via being in contact with said first layer.

[0019] In one embodiment, the first photodiode comprises a first region doped according to the first type of conductivity, a second region doped according to a second type of conductivity, and a third region, formed in the first region and doped according to the first type of conductivity with a concentration of dopants higher than that of the first region; the second region being arranged between the first filter and the first region; the third region being arranged in contact with the level of interconnections.

[0020] In one embodiment, said first filter is an interference filter comprising a periodic alternation of a SiON layer of about 125 nm and an amorphous silicon layer of about 50 nm.

[0021] In one embodiment, the device comprises: - a second stack of a third silicon photodiode, and a fourth photodiode based on quantum dots, the third photodiode being arranged between one side of the second stack configured to receive incident light and the fourth photodiode; - a third interference filter, inserted between the third photodiode and the fourth photodiode, and configured to allow infrared wavelengths to pass through and reflect wavelengths from the visible range; - a fourth filter, of a second color in the visible range different from the first color, allowing only the wavelengths of said second color and infrared wavelengths to pass through.

[0022] In one embodiment, the second and fourth filters are interference filters.

[0023] In one embodiment: - the second filter only allows the wavelengths of said first color and infrared wavelengths to pass through, to which the second photodiode is sensitive; and - the fourth filter only allows through the wavelengths of said second color and infrared wavelengths to which the fourth photodiode is sensitive.

[0024] In one embodiment, the first filter and the third filter allow different infrared wavelengths to pass through.

[0025] One embodiment provides a method of using the device described above, comprising the acquisition of images in the visible from said first photodiode and in the infrared from said second photodiode. Brief description of the drawings

[0026] 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:

[0027] [Fig.1] represents a schematic perspective view of an example of an electronic device according to one embodiment;

[0028] [Fig.2] represents a cross-sectional view along plane AA of an example of an electronic device according to one embodiment;

[0029] [Fig.3] represents a cross-sectional view along plane AA of an example of an electronic device according to another embodiment;

[0030] [Fig.4] represents a cross-sectional view along a plane BB of the example in [Fig.2];

[0031] Figure 5a represents a graph of transmittance as a function of wavelength examples from figures 1 to 3;

[0032] [Fig.5b] represents an absorbance graph as a function of wavelength of the examples in Figures 1 to 3;

[0033] [Fig.5c] represents a transmittance graph as a function of wavelength of the examples in Figures 1 to 3;

[0034] [Fig.5d] represents an absorbance graph as a function of wavelength of the examples in Figures 1 to 3;

[0035] [Fig.6] represents a cross-sectional view along plane AA of an example of an electronic device according to another embodiment;

[0036] [Fig.7] represents a cross-sectional view along plane AA of an example of an electronic device according to another embodiment;

[0037] [Fig.8a] represents absorbance graphs as a function of wavelength from the example in [Fig.7];

[0038] [Fig.8b] represents transmittance graphs as a function of wavelength from the example in [Fig.7];

[0039] [Fig.8c] represents absorbance graphs as a function of wavelength from the example in [Fig.7];

[0040] [Fig. 9] represents an enlarged view of [Fig. 2] according to one embodiment; and

[0041] [Fig. 10] represents an enlarged view of [Fig. 2] according to another embodiment. Description of the implementation methods

[0042] The same elements have been designated by the same reference numerals in the different figures. In particular, the 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.

[0043] For the sake of clarity, only the steps and elements useful for understanding the described embodiments have been represented and are detailed.

[0044] 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.

[0045] In the following description, when referring to absolute positional qualifiers, such as the terms "front", "back", "top", "bottom", "left", "right", etc., or relative, such as the terms "above", "below", "superior", "inferior", etc., or to orienting qualifiers, such as the terms "horizontal", "vertical", etc., it refers, unless otherwise specified, to the orientation of the figures.

[0046] Unless otherwise specified, the expressions "approximately", "roughly", and "on the order of" mean to within 10% or 10°, preferably to within 5% or 5°.

[0047] Light detection, for example multispectral in both the visible and infrared ranges, can be envisaged using a single channel or multiple channels with photodiodes all based on quantum dots. However, the detection level in the visible range is lower for quantum dots than in the infrared due to the generated dark currents.

[0048] Implementing this or these channels, but with silicon instead of quantum dots, is not efficient since silicon is not sensitive to infrared, for example, for wavelengths beyond 1100 nm.

[0049] It could be considered to use a semiconductor layer without quantum dots for detection in the infrared range, for example with SiGe or InGaAs; however, it is extremely difficult to obtain these materials satisfactorily and inexpensively from a silicon substrate. Furthermore, SiGe has a rather low detection level compared to quantum dots.

[0050] Solutions for assembling several substrates could be considered but they are costly.

[0051] Finally, the integration of near-infrared sensitive quantum dot layers on the front face of a device results in the absorption of some of the visible radiation arriving at that front face. The integration of near-infrared sensitive quantum dot layers on the rear face of a device, but with rear-facing illumination, also results in an attenuation of the detectable visible light.

[0052] To overcome these drawbacks, the described embodiments provide for a device comprising a stack made up of at least: - of a first silicon photodiode; and - a second photodiode based on quantum dots; the first photodiode being arranged between one side of the stack configured to receive incident light and the second photodiode.

[0053] This makes it possible to obtain both high-performance visible light detection with a silicon-based photodiode, and high-performance infrared detection with a quantum dot-based photodiode, and this at limited costs.

[0054] This also makes it possible to obtain a device that can function both as a multispectral ambient light detector and as an integrated sensor of proximity working with infrared wavelengths such as wavelengths of 1130 or 1360 nm.

[0055] In the text, the infrared range includes, for example, short-wave infrared (SWIR) wavelengths. In other words, in the text, infrared includes, for example, wavelengths greater than or equal to 1 pm, for example 1.1 pm, 1.130 pm, or 1360 nm. Near-infrared (NIR), whose wavelengths extend between 780 and 1 pm, may also be considered in the following examples, for example by modifying the size or nature of quantum dots.

[0056] Fig. 1 represents a schematic perspective view of an example of an electronic device 300 according to one embodiment.

[0057] The electronic device 300 is, for example, an ambient light sensor for visible spectral analysis and at the same time a proximity sensor specifically exploiting the short infrared spectrum.

[0058] In the example shown, several optical detection channels 352, 354, 356, 358, 360 are adjacent. An optical channel can be seen as a fairly large pixel.

[0059] In the example shown, each of these channels 352, 354, 356, 358, 360 comprises a first region or photodiode 312 formed in a semiconductor material, such as silicon, and, for example, based on a monojunction. Furthermore, the channels 352, 354, 356, 358, 360 comprise, for example, a second region or photodiode 316, arranged at least partially above the first photodiode 312 so as to form a stack. The photodiode 316 is based on quantum dots.

[0060] In one example, each channel 352, 354, 356, 358, 360 is isolated (or separated) from the adjacent channel by an electrical and / or optical insulator and / or a trench. In another example, each channel is wide enough that no separator or insulator is required between adjacent channels.

[0061] Channels 352, 354, 356, 358, and 360 also include, for example, an optical filter 314 or optical switching element 314. The filter 314 is configured to allow infrared wavelengths, particularly short-wave infrared, to pass through to the second photodiode 316 located below it, and to redirect visible wavelengths to the first photodiode 312. In other words, the filter 314 is configured to, for example, deflect by a certain angle wavelengths from the visible range that have passed through the first photodiode without being absorbed, and to allow or deflect by another very small angle wavelengths from the infrared range. In this way, infrared wavelengths are directed to the second photodiode 316, while visible wavelengths are reflected back to the first photodiode 312.

[0062] In one example, the optical filter 314 is a first interference filter 314, for example a Bragg mirror (Distributed Bragg reflector) which is intercalated between the first region 312 and the second region 316. In another example, the same The first filter 314 is common to all channels and is arranged across the entire horizontal span of the channels. In another example, each channel has a different first filter whose filtering properties may vary. In this latter example, the span of the first filter 314 is limited to the horizontal span of each channel, and the wavelengths that each first filter 314 allows to pass through may vary from one channel to another.

[0063] In another example, the filter 314 is a meta-surface. This meta-surface comprises, for example, pillars or reliefs formed in a material with a high optical index (or refractive index), for example above 2, for example in a metal oxide, for example in TiO2. In one example, these pillars are arranged in a matrix with a lower optical index, for example a nitride, for example silicon nitride.

[0064] The arrangement and shape of the pillars or reliefs with a high optical index can be simulated to obtain the different deviations according to the desired wavelengths.

[0065] The use of an optimized Bragg mirror allows the reflection of visible wavelengths towards the silicon photodiodes to ensure maximum absorption of the photodiodes in the visible range. The Bragg mirror is also used as a low-frequency pass-through filter to allow a very large portion of the infrared spectrum to pass through the quantum dot-based photodiodes. This approach is more optimal than the approach of using materials sandwiched between two Bragg mirrors, which results in an absorption peak defined by cavity effects. Indeed, this second approach creates a very sharp absorption that is highly sensitive to the angle of incidence of the incoming light into the system, to the detriment of the sensor's performance.

[0066] Each channel 352, 354, 356, 358, 360 includes, for example, a second filter 302, 304, 306, 308, 310 of a different color in the visible range, allowing only visible wavelengths of the respective color and wavelengths in the infrared range to pass through. The second filter of each channel is arranged above the first photodiode 312 of the channel so that the incident light, symbolized by an arrow in the figure, first passes through the second filter 302, 304, 306, 308, 310, then the first diode 312, then the first filter 314, and finally the second photodiode 316.

[0067] In the example shown, a protective layer 318, for example a thick oxide, is arranged under the photodiodes 316.

[0068] In one example, the first region 312 is a few micrometers thick, for example 4 or 5 pm, the filter 314 is about 500 nm, and the photodiodes 316 are about 500 nm.

[0069] The filter 314 is configured to allow infrared wavelengths to pass through and to reflect wavelengths in the visible range.

[0070] In one example, the filter 314 is composed of a repeated stack of a layer with a high refractive index and a layer with a lower refractive index. In another example, the filter 314 is composed of a repeated stack of a SiON layer approximately 125 nm thick and an amorphous silicon layer approximately 50 nm thick. Such a filter allows short-infrared wavelengths to pass through, for example, between 1130 nm and 1360 nm.

[0071] Filters 302, 304, 306, 308, 310 are, for example, made with an interference filter, for example a Bragg mirror, or with metasurfaces composed of periodic arrangements of pillars with different refractive indices. In one example, each of the filters 302, 304, 306, 308, 310 is configured to allow only wavelengths centered around a given visible wavelength, different for each second filter, as well as infrared light to pass through. In another example, each of the filters 302, 304, 306, 308, 310, is configured to allow through only lengths centered around a given visible wavelength, different for each filter 302, 304, 306, 308, 310, as well as lengths centered around a given infrared wavelength, for example 1130 or 1360 nm and which may advantageously correspond to the maximum absorbance wavelength of the quantum dots of the associated photodiode 316.For example, filter 302 only allows wavelengths of blue light to pass through in the visible spectrum, filter 304 only wavelengths of green light, filter 306 only wavelengths of yellow light, filter 308 only wavelengths of orange light, and filter 310 only wavelengths of red light. In other words, the wavelengths passing through a filter of a given color are, for example, more than 50%, preferably more than 80%, and even more preferably more than 90%, within the spectrum associated with that color.

[0072] In another example, the device includes only one of the filters 302, 304, 306, 308, 310 or only two filters of different colors or even three filters of different colors or not.

[0073] In the text, the color green includes wavelengths between approximately 520 and 565 nm, the color red includes wavelengths between approximately 625 and 740 nm, and the color blue includes wavelengths between approximately 450 and 500 nm. Other filters associated with other visible colors are also possible, such as yellow, orange, cyan, indigo, or violet filters.

[0074] From a manufacturing perspective, in one example, the photodiodes 312 are first formed using back-side technology, by epitaxy, in a silicon substrate. An interface oriented to receive light is then, for example, passivated. This is followed by the formation of the first filter 314. Then, through the silicon and the first filter, vias are formed by ion implantation of the first type of conductivity, or with polysilicon, in deep trench isolation (DTI). These vias connect the second photodiode 316 to an interconnection network, not shown in [Fig.3], and arranged between the second filter 302, 304, 306, 308, 310 and the first photodiode 312. The photodiode 316 is then formed in a planar manner with, for example, one or more layers of quantum dots in colloid form, for example by spin coating or by ink jet printing.The second photodiode 316 is then protected, for example, with a thick oxide layer 318. The substrate is then inverted and the second filters 302, 304, 306, 308, 310 are formed.

[0075] A quantum dot or semiconductor nanoparticle is a nanoscopic material structure that produces electron-hole pairs in the presence of the incidence of photons on the nanoscopic material structure.

[0076] A quantum dot comprises a semiconductor core. A quantum dot may also comprise an envelope, preferably made of a semiconductor material, surrounding the core to protect and passivate it. A quantum dot further comprises ligands, aliphatic organic compounds, organometallic or inorganic molecules that extend from the envelope and passivate, protect, and functionalize the semiconductor surface.

[0077] The composition of a quantum dot can be chosen from the following materials. The core is, for example, made of one of the following materials or an alloy of the following materials: CdSe, CdS, CdTe, CdSeS, CdTeSe, AgS, ZnO, ZnS, ZnSe, CuInS, CuInSe, CuInGaS, CuInGaSe, PbS, PbSe, PbSeS, PbTe, InAsSb, InAs, InSb, InGaAs, InP, InGaP, InAlP, InGaAlP, InZnS, InZnSe, InZnSeS, HgTe, HgSe, HgSeTe, Ge, Si. The shell is, for example, made of one of the following materials or an alloy of the following materials: CdSe, CdS, CdTe, CdSeS, CdTeSe, AgS, ZnO, ZnS, ZnSe, CuInS, CuInSe, CuInGaS. CuInGaSe, PbS, PbSe, PbSeS, PbTe, InAsSb, InAs, InSb, InGaAs, InP, InGaP, InAlP, InGaAlP, InZnS, InZnSe, InZnSeS, HgTe, HgSe, HgSeTe, Ge, Si.

[0078] Preferably, all dimensions of the core are less than 20 nm, for example in the range of 2 to 15 nm. In particular, the diameter of each quantum dot is preferably in the range of 2 to 15 nm. By diameter, we mean the diameter of the smallest sphere in which the quantum dot can be inscribed.

[0079] It is possible to choose a size and dimension of quantum dots capable of absorbing, with significant absorption, any wavelength within a wide wavelength range. For example, it is possible to find a size and dimension of quantum dots having an operating wavelength greater than 1 pm, for example between 1 pm and 3 pm, which includes the near-infrared and short-wave infrared. For example, the 316 photodiode includes quantum dots made of InAs, PbS, HgTe, or PbSe, with, for example, a radius less than 10 nm, to obtain an excitonic absorption peak in the short-wave infrared, for example at 1130 nm or 1360 nm.

[0080] The incident light, composed of visible and infrared wavelengths, is first filtered by filters 302, 304, 306, 308, and 310, then passes through the first photodiodes 312. Only infrared and a very small amount of visible light pass through the first photodiodes 312. The first filter 314 then allows only the propagation of infrared, for example, short-wave infrared, to the second photodiode 316. The second photodiode 316 can therefore be used to form a proximity detector because infrared, particularly short-wave infrared, is not absorbed by the other elements of the stack. This proximity detector is obtained, for example, by coupling the second photodiode, for example, using the interconnection layer not shown in [Fig. 3], with a detection circuit not shown in the device 300.

[0081] Figure 1 shows a plane AA passing transversely through the thickness of the device 300.

[0082] Fig. 2 represents a cross-sectional view along plane AA of an example of the electronic device 300 according to one embodiment.

[0083] In the example in [Fig.2], only filters 304, 306, 308 and 310 are shown for clarity.

[0084] In the example shown, a layer 480, also called an interconnection layer, comprising interconnection layers, is interposed between the filters 304, 306, 308, 310 and the photodiode(s) 312. The layer 480 comprises, for example, one or more layers of metal lines connected to each other by vertical metal vias. The layer 480 is, for example, connected, preferably linked, to the photodiodes 312 and 316.

[0085] In the example shown, the photodiode(s) 312 comprises a first region 460 doped according to the first type of conductivity, for example N. The photodiode 312 further comprises a second region 438 doped according to a second type of conductivity, for example P, with, for example, a dopant concentration higher than that of the first region 460. In this example, the photodiode 312 comprises a third region 439, formed in the first region 460 and doped according to the first type of conductivity with a dopant concentration higher than that of the first region 460. In the example shown, region 439 is for example formed by one or more boxes arranged within the first region 460 and with one face in contact with the interconnection level 480. Region 438 allows combining the holes generated in the photodiode 312.

[0086] In one example, several photodiodes 312 can be formed adjacently, for example separated by trenches or an insulator, so as to form a photodiode 312 directly above each filter 304, 306, 308, 310 to form a multispectral visible light sensor.

[0087] In another example, a single photodiode 312 is formed and extends under the set of filters 304, 306, 308, 310. In this case, the respective connections of the third regions at the level of interconnections 480 can allow to define a level of the respective visible light received at the level of each of the filters 304, 306, 308, 310, or the overall level of visible light received at the level of the set of filters 304, 306, 308, 310.

[0088] In the example shown, the same filter 314 is arranged vertically over the entire surface of the filters 304, 306, 308, 310 and is interposed between the second region 438 of the photodiode(s) 312 and the photodiode(s) 316. The filter 314 reflects the visible radiation that has not been absorbed by the first respective photodiode 312 (XC, XG, XY, XR) and allows infrared radiation to pass through, for example short infrared radiation (Xswir).

[0089] In the example shown, the filter 314 is in contact with an electron transfer layer 423 (ETL), configured to conduct electrons and block hole conduction in the photodiode 316. In one example, the layer 423 is made of ZnO, TiO2, or AZO. In another example, the photodiode 316 also includes a layer 422 (QF-N) with quantum dots that is in contact with the layer 423. The layer 422 includes quantum dots, for example, sensitive to wavelengths centered on 1.130 pm or 1.360 pm. In one example, layer 422 is doped with the first type of conductivity, for example N. In the example shown, the photodiode 316 also includes a hole transfer layer 428 (HTL) which is configured to conduct holes from layer 422. This layer 428 is, for example, made of Mox, NiOx, or P-doped.

[0090] In one example, one or more conductive vias 424, insulated from the photodiode 312, connect, preferably connect, through the photodiode 312 and through the filter 316, the layer 423 at the interconnection points 480. Some vias 424, such as, for example, the outermost vias in [Fig. 2], are connected, preferably connected, to a layer 418 (HTL Contact) which is arranged in contact with the layer 428. The layer 418 makes it possible to form a low-resistance discharge contact. holes in photodiode 316. At these external vias 424, layer 418 rises to connect to the outermost vias in [Fig. 2]. The layer is, for example, isolated from layers 423 and 422 by layer 412.

[0091] In one example, layer 423 constitutes, for example, a common electrode for photodiode 312 and photodiode 316, region 439 constitutes, for example, an electrode for photodiode 312, and layer 418 constitutes another electrode for photodiode 316.

[0092] In one example, several photodiodes 316 can be formed adjacently, for example separated by trenches or an insulator, so as to form a photodiode 316 directly above each filter 304, 306, 308, 310 to form a proximity sensor for example with several pixels.

[0093] In one example, device 300 is used for white balance (PPG / ECG).

[0094] In another example, a single photodiode 316 is formed and extends under the set of filters 304, 306, 308, 310. In this case, the via(s) 424 and their respective connection at the interconnection level 480 can allow the definition of an infrared level received directly above each of the filters 304, 306, 308, 310, or the overall infrared level received directly above the set of filters 304, 306, 308, 310.

[0095] An enlarged view C of the contact zone between one of the vias 424 and layer 423 is illustrated in Figures 11 and 12.

[0096] Figure [Fig.2] shows a plane BB crossing horizontally through device 300 at regions 439.

[0097] Fig. 3 represents a cross-sectional view along plane AA of an example of an electronic device 300 according to another embodiment.

[0098] The example in [Fig.3] is similar to that in [Fig.4] except that the photodiode 316 also has, optionally, a 528 (QF-P) layer, containing quantum dots and doped according to the second mode of conductivity, for example P. The 528 layer is arranged for example between the 422 and 428 layers. The 528 layer forms for example a junction with the 422 layer.

[0099] Figure 4 shows a cross-sectional view along plane BB of the example in Figure 2.

[0100] In the example shown, the device 300 comprises several channels 604, 606, 608, 610, each dedicated to a color, and shown in cross-section in a top view. Each channel extends horizontally along the entire horizontal footprint of the corresponding filter 304, 306, 308, 310. In one example, each channel extends horizontally along a portion of the horizontal footprint of the corresponding filter 304, 306, 308, 310. Each channel comprises an alternation of vias 424 and regions 439 arranged in a staggered pattern and along several parallel lines in the region 460 of the respective photodiode 312.

[0101] The vias 424 comprise an internal conductive portion, for example of highly doped silicon of the first type of conductivity (N+) or of polysilicon. This internal portion is isolated from the region 460 by insulating trenches.

[0102] In an example not shown, the internal portions of two adjacent 424 vias are doped with an opposite type of doping (P+ and N+), so as to form a P-Si / N-QF / N-Si heterojunction without a metallic electrode above.

[0103] In the example shown, each channel 604, 606, 608, 610 is isolated from the adjacent channel by an insulator or an insulating trench 620. This insulating trench extends vertically for example through the filter 304, 306, 308, 310, the photodiode 312 of the respective channel, the filter 314 and the photodiode 316 of the respective channel.

[0104] In the example shown, regions 439 and vias 424 have a square cross-section, however any other shape may be envisaged.

[0105] Fig. 5a represents a transmittance graph as a function of wavelength of the examples in Figures 1 to 3.

[0106] In particular, the example in [Fig. 5a] represents the respective transmittances t304, t306, t308, t310 of filters 304, 306, 308, and 310. In this example, filter 304 transmits wavelengths centered around the color cyan, filter 306 transmits wavelengths centered around the color green, filter 308 transmits wavelengths centered around the color yellow, and filter 310 transmits wavelengths centered around the color red. Filters 304, 306, 308, and 310 also transmit short-wave infrared Xswir and longer wavelengths.

[0107] Fig. 5b represents an absorbance graph as a function of wavelength of the examples in Figures 1 to 3. In particular, Fig. 5b represents the absorbance a304, a306, a308, a310 of the respective photodiode 312 of each channel.

[0108] In this example, the photodiode 312 of the channel respective to the filter 304 absorbs, a304, wavelengths centered around the color cyan, the photodiode 312 of the channel respective to the filter 306 absorbs, a306, wavelengths centered around the color green, the photodiode 312 of the channel respective to the filter 308 absorbs, a308, wavelengths centered around the color yellow, and the photodiode 312 of the channel respective to the filter 310 absorbs a310 wavelengths centered around the color red.

[0109] The photodiode 312 of each channel allows short infrared Xswir and higher wavelengths to pass through, which thus become available for the photodiode 316 which is arranged below after passing through the filter 314.

[0110] Figure 5c represents a transmittance-wavelength graph of the examples in Figures 1 to 3. In particular, the example in Figure 5c represents the tDBR transmittance of filter 314.

[0111] In the example shown, filter 314 allows short-wave infrared Xswir and longer wavelengths to pass through and absorbs or reflects visible wavelengths. This improves the visible photon rejection ratio for photodiode 316.

[0112] Fig. 5d represents an absorbance-wavelength graph of the examples in Figures 1 to 3. In particular, Fig. 5d represents the absorbance aQD of the quantum dots of photodiode 316. In this example, the absorbance is centered on short infrared Xswir wavelengths, for example 1.130 pm or 1.360 pm, which correspond to the excitonic peaks.

[0113] Fig. 6 represents a cross-sectional view along plane AA of an example of an electronic device according to another embodiment.

[0114] The example in [Fig. 6] is similar to that in [Fig. 3], except that filters 306, 308, 310 are replaced by interference filters 804, 806, 808. Each of the 804, 806, 808 filters allows only the wavelengths of their respective color in the visible spectrum to pass through, as well as a narrow band in the infrared, different for each filter. In this way, it is possible to create several channels of different wavelengths in the infrared, each channel associated with an infrared frequency band having the same dimensions as the corresponding visible channel located above it.

[0115] In the example of [Fig.6], optional insulating trenches 830 isolate the different channels from each other by isolating the filters 806, 808, 810 from each other, the respective interconnection levels, the photodiodes 312, the photodiodes 316 and the insulating layer 318. These trenches 830 are not necessarily required because the charge carriers generated in the photodiode 316 have low mobility and the application of a vertical electric field is sufficient to prevent crosstalk between channels.

[0116] Figure 7 shows a cross-sectional view along plane AA of an example of an electronic device according to another embodiment. More specifically, the example in Figure 7 is similar to that in Figure 6, except that filters 806, 808, and 810 are replaced by filters 306, 308, and 310, respectively. Furthermore, in the example shown, filter 314 is replaced, for each channel, by an interference filter or an optical switching element specific to each channel. For example, the channel associated with filter 306 includes a filter 906, the channel associated with filter 308 includes a filter 908, and the channel associated with filter 310 includes a filter 910. In this example, the infrared transmittance is different for each of the 906, 908, and 910 filters. This allows for the addition of channels specifically for the analysis of short-wave infrared, for example.

[0117] In one example, to obtain such a difference in transmittance between each filter 906, 908, 910, it is sufficient to modify the thickness or the refractive index of the layers repeated periodically in the filters.

[0118] In the example of [Fig.7], the device 300 may include a computing unit allowing, via a reconstruction matrix, to recalculate the spectrum in the short infrared for example since several distinct infrared peaks can be detected by the photodiode 316 of certain channels.

[0119] Fig. 8a represents absorbance graphs as a function of wavelength from the example in Fig. 7.

[0120] In this example, only the absorbance associated with filters 306, 308, and 310 is shown for clarity. The photodiode 312 of the channel corresponding to filter 306 absorbs, a306, wavelengths centered around the color green, the photodiode 312 of the channel corresponding to filter 308 absorbs, a308, wavelengths centered around the color yellow, and the photodiode 312 of the channel corresponding to filter 310 absorbs, a310, wavelengths centered around the color red.

[0121] The photodiode 312 of each channel does not absorb, or negligibly absorbs, the short infrared Xswir wavelengths and higher wavelengths which thus become available for the photodiode 316 which is arranged below after passing through the respective filters 906, 908, 910.

[0122] Figure 8b shows transmittance graphs as a function of wavelength for the example in Figure 7. More specifically, Figure 8b shows the transmittance of filters 906, 908, and 910, respectively. In this example, these different filters 906, 908, and 910 have transmittances t906, t908, and t910, respectively, which differ for infrared, particularly short-wave infrared. For example, filter 906 has a transmittance t906 in the short-wave infrared that is higher than that of filter 908, which itself has a transmittance t908 in the short-wave infrared that is higher than that t910 of filter 910. The transmittance t910 is almost zero before the excitonic peak of the quantum dots.

[0123] Fig. 8c represents absorbance graphs as a function of wavelength from the example in Fig. 7.

[0124] In particular, [Fig.8c] represents the absorbance 316a, 316b, 316c of the respective photodiode 316 of the channels associated with the filters 306, 308 and 310.

[0125] In [Fig.8c], the absorbance 316a comprises two peaks of intensity of the same order of magnitude and centered respectively on the excitonic peak Xswir of the quantum dots and on a part of the infrared spectrum having lengths slightly shorter than the excitonic peak.

[0126] In the example shown, the absorbance 316b includes a first peak of lower intensity than the excitonic peak centered on the excitonic peak Xswir of the boxes quantum. The first peak is on a part of the infrared spectrum with slightly shorter wavelengths than the excitonic peak.

[0127] In the example shown, the absorbance 316c includes only the excitonic peak Xswir of the quantum dots.

[0128] Figure 9 shows an enlarged view of Figure 4 according to one embodiment. More particularly, Figure 9 shows the enlarged view C of the connection between one of the vias 424 and layer 422 of the photodiode 316 of the associated channel.

[0129] In the example shown, the via 424 comprises a central region, or portion, 1104 made of polysilicon (Poly-Si) within deep trench isolation 1106. The deep trench isolation 1106 is arranged between region 460, region 438 (P-Si well), and region 1104, and has its base in contact with an upper surface of the filter 314 so as to electrically isolate the via 424 from regions 460 and 438.

[0130] In the example shown, the central region 1104 of via 424 is in contact with a portion or region 1140 of metallic material having a shallow exit work to facilitate electron extraction. In one example, the portion 1140 is arranged between the portion 1104 and the layer 423. The portion 1140 is, for example, arranged partly between the region 1104 and the filter 314 (DBR), and partly below the filter 314 so as to be arranged between the layer 423 (ETL) and the filter 314.

[0131] In one example, region 1140 comprises several layers of different metallic materials having a low output work.

[0132] In the example shown, layer 423 is in contact with region 1140 and is sandwiched between region 1140 and layer 422.

[0133] In the example of [Fig.9], the vias 424 form deep insulating and capacitive trenches.

[0134] The example of [Fig.9] advantageously allows the photogenerated charges to be collected near the collecting electrode and thus to be made into absorption channels at different wavelengths, as described in figures 6 and 7.

[0135] [Fig. 10] shows an enlarged view of [Fig. 4] according to another embodiment. More particularly, [Fig. 10] shows the enlarged view C of the connection between one of the vias 424 and layer 422 of the photodiode 316 of the associated channel.

[0136] In the example shown, the via 424 comprises a central region, or portion, 1204 of silicon doped with the first type of conductivity, for example N, (N-Si) within deep trench isolation 1206. The deep trench isolation 1206 is arranged between region 460, region 438 (P-Si well), and region 1204, and has its base in contact with a vertical surface of the filter 314 so as to electrically isolate the via 424 from regions 460 and 438. In this For example, region 1204 of via 424 in the example shown is in direct contact with layer 422.

[0137] In the example of [Fig. 10], a heterojunction is thus created between the internal region 1204 of the via and layer 422.

[0138] The example of [Fig. 10] advantageously allows the collection of charges to be simplified by adjusting the doping of the silicon to remove the potential barriers limiting the extraction of electrons, and to reduce the topology related to the presence of metallic electrodes.

[0139] The device is intended for example for the automotive industry for the analysis of incident light.

[0140] The device is intended for use, for example, in communication equipment, or in computers and peripherals.

[0141] In one example, device 300 is used in LED (Light Emitting Diode) lighting systems to control the emitted light by analyzing incident or emitted light.

[0142] 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 be apparent to those skilled in the art. In particular, although examples with multiple channels have been presented, the device 300 may contain only a single visible channel of one color with a photodiode 312 and a photodiode 316. Furthermore, the use of a filter 314 as described is not mandatory but preferable to increase the rejection of visible radiation with respect to the photodiode 316.

[0143] Finally, the practical implementation of the described embodiments and variants is within the grasp of a person skilled in the art, based on the functional indications given above. In particular, with regard to the connection between the vias 424 and layer 422 in the examples of Figures 3, 6, and 7, a person skilled in the art can start with the solutions in Figures 9 or 10 and adapt them to the examples in those figures so that the internal region of the vias can be connected to layer 422. With regard to the examples in Figures 2, 3, 6, and 7, a person skilled in the art can implement these examples with inverted conductivity types using their knowledge.

Claims

Demands

1. Device comprising a stack consisting of at least: - a first photodiode (312) made of silicon; and - a second photodiode (316) based on quantum dots; the first photodiode being arranged between one side of the stack configured to receive incident light and the second photodiode (316).

2. Device according to claim 1, comprising a first filter (314, 906, 908, 910), interposed between the first photodiode (312) and the second photodiode (316), and configured to allow infrared wavelengths to pass through and to reflect visible wavelengths.

3. Device according to claim 1 or 2, comprising at least a second filter (302, 304, 306, 308, 310, 806, 808, 810), of a first color in the visible range, allowing only wavelengths of said first color and infrared wavelengths to pass through.

4. Device according to any one of claims 1 to 3, wherein the first photodiode (312) is sensitive only to wavelengths in the visible range.

5. Device according to any one of claims 1 to 4, wherein the second photodiode (316) is mainly sensitive to infrared.

6. Device according to any one of claims 1 to 5, wherein said second photodiode (316) comprises a first layer (422) comprising the quantum dots and doped with a first type of conductivity, and a second layer (428) configured to conduct holes from the first layer.

7. Device according to the preceding claim, wherein said second photodiode (316) comprises a third layer (528) comprising quantum dots and doped with a second type of conductivity, and arranged between said first layer (422) and said second layer (428).

8. A device according to claim 3, or any one of claims 4 to 7 in their dependence on claim 3, comprising an interconnection level (480) comprising conductive interconnections arranged between the first photodiode (312) and the second filter (302, 304, 306, 308, 310, 806, 808, 810); in which a first via conductor (424), isolated from the first photodiode (312), connects, through the first photodiode (312) and through the first filter (314), the second photodiode (316) at the level of interconnections (480).

9. Device according to claim 8, wherein the second photodiode (316) comprises a fourth layer (423) configured to conduct electrons and block hole conduction, and to connect the first layer (422) to the first via (424).

10. Device according to claim 9, wherein said first via (424) comprises a first portion (1104) of polysilicon and a second portion (1140) of metallic material, said second portion (1140) being arranged between the first portion (1104) and the fourth layer (423).

11. Device according to the preceding claim, wherein said metallic material has an output work adapted to facilitate electron extraction.

12. Device according to claim 8 in its dependence on claim 6, wherein said first via (424) is made of silicon and with the first or second type of conductivity, said first via being in contact with said first layer (422).

13. Device according to any one of claims 8 to 12 in their dependence on claim 2, wherein the first photodiode (312) comprises a first region (460) doped according to the first type of conductivity, a second region (438) doped according to a second type of conductivity, and a third region (439), formed in the first region (460) and doped according to the first type of conductivity with a concentration of dopants higher than that of the first region (460); the second region (438) being arranged between the first filter (314, 906, 908, 910) and the first region (460); the third region (439) being arranged in contact with the interconnection level (480).

14. A device according to any one of claims 2 or 3 to 13 in their dependence on claim 2, wherein said first filter (314) is an interference filter comprising an alternating periodic of a SiON layer of about 125 nm and an amorphous silicon layer of about 50 nm.

15. A device according to any one of claims 3, or 4 to 14 in their dependence on claim 3, comprising: - a second stack of a third silicon photodiode (312), and a fourth quantum dot-based photodiode (316), the third photodiode (312) being arranged between one side of the second stack configured to receive incident light and the fourth photodiode (316); - a third interference filter (314, 906, 908, 910), intercalated between the third photodiode (312) and the fourth photodiode (316), and configured to allow infrared wavelengths to pass through and to reflect wavelengths in the visible range; - a fourth filter (302, 304, 306, 308, 310), of a second color in the visible range different from the first color, allowing only the wavelengths of said second color and infrared wavelengths to pass through.

16. Device according to claim 15, wherein the second and fourth filters (302, 304, 306, 308, 310) are interference filters.

17. Device according to claim 16, wherein: - the second filter (302, 304, 306, 308, 310, 806, 808, 810) only allows the wavelengths of said first color and infrared wavelengths to which the second photodiode (316) is sensitive to pass through; and - the fourth filter (302, 304, 306, 308, 310, 806, 808, 810) only allows the wavelengths of said second color and infrared wavelengths to which the fourth photodiode (316) is sensitive to pass through.

18. Device according to any one of claims 15 to 17, wherein the first filter and the third filter (906, 908, 910) allow different infrared wavelengths to pass through.

19. A method of manufacturing the device according to any one of claims 1 to 18, comprising: - the formation of the first photodiode (312); then - the formation of the second photodiode (316) so as to form a stack with the first photodiode (312); the first photodiode (312) being arranged between the side of the stack configured to receive incident light and the second photodiode (316).

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