Electronic device
By introducing single-junction and quantum dot-based heterojunction pixel designs into photodiodes, combined with filters and optical components, the problem of insufficient sensitivity of existing devices to visible and infrared wavelengths is solved, achieving efficient wavelength separation and low noise performance.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- STMICROELECTRONICS INT NV
- Filing Date
- 2025-06-20
- Publication Date
- 2026-07-21
AI Technical Summary
Existing photodiodes are not highly reactive in the near-infrared and short-wave infrared wavelengths, making it difficult to simultaneously be sensitive to both the visible range and infrared wavelengths. Furthermore, existing devices face challenges in achieving high resolution and low noise performance.
The pixel design employs both single-junction and quantum dot-based heterojunctions, combined with filters and optical elements to receive visible and infrared wavelengths respectively. Wavelength separation is achieved through interferometers or optical steering elements, and each pixel is electrically insulated through insulating conductive walls.
It achieves efficient separation of visible and infrared wavelengths, improves external quantum efficiency, reduces dark current and noise, simplifies the manufacturing process, and limits crosstalk between pixels.
Smart Images
Figure CN224538670U_ABST
Abstract
Description
[0001] Priority requirements
[0002] This application claims priority to French patent application No. FR2406705, filed on June 21, 2024, the contents of which are incorporated herein by reference in their entirety to the fullest extent permitted by law. Technical Field
[0003] This disclosure generally relates to electronic devices, and more specifically to optoelectronic devices including photodiodes, and associated methods for manufacturing such electronic devices. Background Technology
[0004] A photodiode is a semiconductor device that has the ability to capture radiation in an optical field and convert it into an electrical signal.
[0005] In common types of photodiodes, the space charge region is located within the semiconductor material, typically silicon. However, silicon is not very reactive at near-infrared (NIR) and short-wave infrared (SWIR) wavelengths.
[0006] Equipment that is sensitive to both visible wavelengths and infrared wavelengths is required.
[0007] It is necessary to overcome all or some of the shortcomings of known devices. Utility Model Content
[0008] According to one aspect of this disclosure, an electronic device is provided, comprising: at least one first pixel having a single junction; at least one second pixel including a heterojunction formed from a semiconductor substrate layer in contact with a quantum dot layer; at least one first filter of a first color configured to allow only wavelengths of the first color and infrared wavelengths to pass through, the at least one first filter being arranged perpendicular to the at least one first pixel and at least partially perpendicular to the at least one second pixel; and an optical element inserted between the at least one first filter and the at least one second pixel; wherein the at least one first filter and the optical element are configured such that the at least one first pixel receives wavelengths of the first color and the at least one second pixel receives only infrared wavelengths.
[0009] In some embodiments, the device further includes: at least one third pixel having a single junction; at least one second filter of a second color configured to allow only wavelengths of the second color and infrared wavelengths to pass through, the at least one second filter being arranged perpendicular to the at least one third pixel and at least partially perpendicular to the at least one second pixel; wherein an optical element is inserted between the at least one second filter and the at least one second pixel; wherein the at least one second filter and the optical element are configured such that the at least one third pixel receives wavelengths of the second color and the at least one second pixel receives only infrared wavelengths.
[0010] In some embodiments, each of the at least one first pixel and the at least one third pixel includes a first region of a first doped layer having a first conductivity type and a second doped region of a second conductivity type.
[0011] In some embodiments, the heterojunction is sensitive to light with an infrared wavelength.
[0012] In some embodiments, the single junction pair is light-sensitive at visible wavelengths.
[0013] In some embodiments, the optical element includes an interferometer configured to allow infrared light to pass toward the at least one second pixel and reflect visible light.
[0014] In some embodiments, the optical element includes an optical steering element configured to direct infrared wavelength light toward the at least one second pixel and to direct visible wavelength light toward a pixel different from the at least one second pixel.
[0015] In some embodiments, the optical element further includes an interferometer configured to allow infrared light to pass toward the at least one second pixel and reflect visible light, wherein the interferometer is inserted between the at least one second pixel and the optical steering element.
[0016] In some embodiments, the optical steering element comprises a metasurface.
[0017] In some embodiments, the metasurface comprises metal oxide columns in a matrix comprising nitrides.
[0018] In some embodiments, the device further includes an insulating conductive wall configured to couple to a voltage rail receiving a negative voltage and positioned to electrically insulate the pixels from each other.
[0019] In some embodiments, the at least one second pixel includes a first doped region of a first conductivity type, the first doped region including the semiconductor substrate layer in contact with the quantum dot layer.
[0020] In some embodiments, the at least one second pixel further includes a second doped region of a second conduction type, the second doped region being in contact with the second layer.
[0021] In some embodiments, the first layer is laterally surrounded by an insulating conductive wall configured to couple to a voltage rail receiving a negative voltage, and wherein the dopant concentration of the first layer is higher than that of the second layer.
[0022] In some embodiments, the first layer of the first doped region of the at least one second pixel includes a notch, and wherein the second layer is at least partially formed in the notch.
[0023] In some embodiments, the at least one first pixel includes a first doped layer of a first conductivity type and a second doped region of a second conductivity type.
[0024] According to another aspect of this disclosure, an electronic device is provided, comprising: at least one first pixel having a single junction; at least one second pixel including a quantum dot-based heterojunction formed from a first region in a semiconductor substrate in contact with a quantum dot layer; at least one first filter of a first color configured to allow only wavelengths of the first color and infrared wavelengths to pass through, the at least one first filter being arranged perpendicular to the at least one first pixel and at least partially perpendicular to the at least one second pixel; and an optical element inserted between the at least one first filter and the at least one second pixel; wherein the at least one first filter and the optical element are configured such that the at least one first pixel receives wavelengths of the first color and the at least one second pixel receives only infrared wavelengths.
[0025] According to another aspect of this disclosure, an electronic device is provided, comprising: a plurality of pixels laterally insulated from each other; wherein each of the plurality of pixels includes a first substrate region doped with a first conductivity type; wherein the plurality of pixels includes a first pixel having a single junction and a second pixel including a quantum dot-based heterojunction; wherein the quantum dot-based heterojunction for each second pixel includes a quantum dot layer in contact with an upper surface of the first substrate region; at least one first filter of a first color, the first filter being configured to allow only wavelengths of the first color and infrared wavelengths to pass through, the at least one first filter being arranged perpendicular to the first pixel and at least partially perpendicular to the second pixel; and an optical element inserted between the at least one first filter and the second pixel; wherein the at least one first filter and the optical element are configured such that the first pixel receives the wavelength of the first color and the second pixel receives only infrared wavelengths.
[0026] In some embodiments, each of the plurality of pixels further includes a second substrate region doped with a second conductivity type, located between a first substrate region and an insulating wall, the insulating wall providing lateral insulation between adjacent pixels of the plurality of pixels, and wherein the quantum dot layer also contacts the upper surface of the second substrate region.
[0027] In one embodiment, an electronic device includes: at least one first pixel having a single junction; at least one second pixel including a quantum dot-based heterojunction; at least one first filter of a first color configured to allow only wavelengths of the first color and infrared wavelengths to pass through, the at least one first filter being arranged perpendicularly to the first pixel and at least partially aligned with the second pixel; and an optical element inserted between the first filter and the second pixel; wherein the first filter and the optical element are configured such that the first pixel receives wavelengths of the first color and the second pixel receives only infrared wavelengths.
[0028] Another embodiment provides a method of manufacturing an apparatus, the method comprising: providing a first filter of a first color, the first filter being configured to allow only wavelengths of the first color and infrared wavelengths to pass through; arranging the first filter in a line perpendicular to at least one first pixel and at least partially in a line with a second pixel; wherein the first pixel has a single junction and the second pixel includes a quantum dot-based heterojunction; inserting an optical element between the first filter and the second pixel; wherein the first filter and the optical element are configured such that the first pixel receives wavelengths of the first color and the second pixel receives only infrared wavelengths.
[0029] According to an embodiment, the device includes: at least one third pixel having a single junction; at least one second filter of a second color configured to allow only wavelengths of the second color and infrared wavelengths to pass through, the at least one second filter being arranged perpendicularly to the third pixel and at least partially aligned with the second pixel; wherein an optical element is inserted between the second filter and the second pixel; wherein the second filter and the optical element are configured such that the third pixel receives wavelengths of the second color and the second pixel receives only infrared wavelengths.
[0030] According to an embodiment, the heterojunction is sensitive to infrared wavelengths.
[0031] According to an embodiment, the (one or more) single junctions are wavelength sensitive in the visible field.
[0032] According to an embodiment, the optical element includes an interferometer configured to allow infrared wavelengths to pass toward the second pixel and reflect visible wavelengths.
[0033] According to an embodiment, the optical element includes an optical steering element configured to direct an infrared wavelength toward a second pixel and a visible wavelength toward a pixel different from the second pixel.
[0034] According to an embodiment, the interferometer is inserted between the second pixel and the optical steering element.
[0035] According to an embodiment, the optical steering element includes a metasurface.
[0036] According to an embodiment, the metasurface comprises metal oxide columns in a matrix including nitrides.
[0037] According to an embodiment, at least two pixels are electrically insulated from each other by an insulating conductive wall configured to couple to a voltage rail that receives a negative voltage.
[0038] According to an embodiment, the second pixel includes a first doped region of a first conductivity type, the first doped region including a first layer and a second layer forming the heterojunction, the first layer being made of a semiconductor material and the second layer including the quantum dot.
[0039] According to an embodiment, the second pixel includes a second doped region of a second conduction type, and the second doped region is in contact with the second layer.
[0040] According to an embodiment, the first layer is laterally surrounded by the insulating conductive wall, and the dopant concentration of the first layer is higher than that of the second layer.
[0041] According to an embodiment, the first pixel and / or the third pixel includes a first region having a first doped layer of a first conductivity type and a second doped region of a second conductivity type.
[0042] According to an embodiment, the first doped layer of the first region of the second pixel includes a notch, and the second layer is at least partially formed in the notch.
[0043] An embodiment provides a method for using the above-described device, including acquiring an image in the visible range from at least a first pixel and acquiring an image in the infrared range from a second pixel. Attached Figure Description
[0044] The above and other features and advantages will be described in detail in the remainder of the disclosure of specific embodiments given by way of illustration and not limitation, with reference to the accompanying drawings, wherein:
[0045] Figure 1 An example of an electronic device is shown schematically;
[0046] Figure 2 An embodiment of an electronic device is illustrated schematically;
[0047] Figure 3 It shows Figure 2 A cross-sectional view of the device along plane AA;
[0048] Figure 4 It shows Figure 2 A cross-sectional view along plane AA of another embodiment of the device; and
[0049] Figure 5 It shows Figure 2 Another embodiment of the device is shown in a cross-sectional view along plane AA. Detailed Implementation
[0050] In the various figures, similar features have been indicated by similar reference numerals. In particular, common structural and / or functional features in the various embodiments may have the same reference numerals and may have the same structure, dimensions, and material properties.
[0051] For clarity, only those steps and elements useful for understanding the embodiments are shown and described in detail.
[0052] Unless otherwise indicated, when referring to two elements connected together, it means a direct connection without any intermediate elements other than the conductor; when referring to two elements coupled together, it means that the two elements can be connected or they can be coupled via one or more other elements.
[0053] In the following description, when referring to absolute position qualifiers (such as “front,” “back,” “top,” “bottom,” “left,” “right,” etc.) or relative position qualifiers (such as “top,” “bottom,” “up,” “down,” etc.) or orientation qualifiers (such as “horizontal,” “vertical,” etc.), the orientation of the accompanying drawings shall be indicated unless otherwise specified.
[0054] Unless otherwise specified, the expressions “approximately,” “about,” “basically,” and “around” indicate addition or subtraction of 10% or 10°, preferably 5% or 5°.
[0055] Figure 1 An example of electronic device 100 is shown schematically.
[0056] In the illustrated example, device 100 includes, for example, a plurality of color filters 122(G), 124(B), 126(R), and 128(G). In this example, each of these filters 122, 124, 126, and 128 allows only the visible wavelengths associated with that color to pass through. For example, filter 122 allows only green (G) wavelengths to pass through, filter 124 allows only blue (B) wavelengths to pass through, filter 126 allows only red (R) wavelengths to pass through, and filter 128 allows only green (G) wavelengths to pass through. In other words, the phrase "allows" should be understood to mean that the wavelengths derived from the filters of a given color, for example, exceed 50%, preferably 80%, and even more preferably 90% of the spectrum associated with that color. In this example, while filters 122, 124, 126, and 128 enable the selection of wavelengths associated with their colors within the visible range, they still allow most of the incident infrared radiation to pass through.
[0057] These filters, 122, 124, 126, and 128, are arranged, for example, in a Bayer matrix format.
[0058] In the example, device 100 includes multiple, even dozens, hundreds, or preferably thousands of components 120 formed by four filters.
[0059] In another example, each component 120 includes a single filter, or only two filters of different colors, or three filters that may or may not be of different colors.
[0060] As described herein, it will be understood that green (G) includes wavelengths approximately in the range of 520 nm to 565 nm, red (R) includes wavelengths approximately in the range of 625 nm to 740 nm, and blue (B) includes wavelengths approximately in the range of 450 nm to 500 nm. Other filters associated with other visible colors are also possible, such as yellow, orange, cyan, indigo, or violet filters.
[0061] As described herein, it will be understood that the infrared range includes, for example, short-wave infrared (SWIR) wavelengths. In other words, as described herein, infrared (IR) includes wavelengths greater than or equal to 1 μm, such as 1.1 μm or 1.130 μm. Near-infrared (NIR) includes wavelengths extending, for example, between 780 and 1 μm, and these wavelengths can also be considered, for example, by modifying the size or properties of the quantum dot.
[0062] In the illustrated example, device 100 also includes an array 130 of four pixels 131(G), 132(B), 133(R), and 134(G) arranged perpendicular to component 120. Each of these pixels 131(G), 132(B), 133(R), and 134(G) includes, for example, a single junction formed in, for example, a semiconductor substrate 135 (such as silicon) and is configured to convert visible wavelengths it receives into electrical charges. These charges generate signals through processing by circuitry (not shown), and these signals are then processed to form, for example, an image.
[0063] In the example shown, each pixel 131, 132, 133, 134 is arranged in a line perpendicular to one of the filters in component 120. For example, pixel 131 is arranged in a line perpendicular to filter 122, pixel 132 is arranged in a line perpendicular to filter 124, pixel 133 is arranged in a line perpendicular to filter 126, and pixel 134 is arranged in a line perpendicular to filter 128.
[0064] In the example, device 100 includes multiple, even dozens, hundreds, or preferably thousands of pixel arrays 130 formed by four pixels 131, 132, 133, 134.
[0065] In another example, each array 130 includes a single pixel, or only two pixels, or three pixels.
[0066] However, the fact that silicon single-junctions are used for pixels does not make it possible to capture infrared spectral data for the same image. This data would be useful for, for example, time-of-flight determination or distance calculation.
[0067] It is possible to capture both visible and infrared wavelengths of the same image using pixels of quantum dots that are sensitive to both infrared and visible wavelengths. However, the efficiency of these devices in the visible range is limited due to their low bandgap values and high defect densities.
[0068] Other technical solutions, known as above interconnect (ABIC), are complex to implement due to the increasing resolution requirements, and also suffer from performance losses due to dark current and noise.
[0069] To overcome these drawbacks, the described embodiments provide an apparatus comprising: at least one first pixel having a single junction; at least one second pixel including a quantum dot-based heterojunction; at least one first filter of a first color configured to allow only wavelengths of the first color and infrared wavelengths to pass through, wherein the first filter is arranged perpendicularly to the first pixel and at least partially aligned with the second pixel; and an optical element inserted between the first filter and the second pixel; wherein the first filter and the optical element are configured such that the first pixel receives wavelengths of the first color and the second pixel receives only infrared wavelengths.
[0070] This technical solution allows the use of standard Bayer grids, thus eliminating the need for complex development for image reconstruction.
[0071] It is simpler to separate visible wavelengths from infrared wavelengths than to separate visible wavelengths from each other.
[0072] This technical solution further enables improvements in the external quantum efficiency (EQE) for each wavelength channel.
[0073] Wavelength rejection has also been improved by separating visible wavelengths from infrared wavelengths.
[0074] The fact that quantum dots are not used in all pixels means that there is no infrared absorption in pixels with a single junction, which ultimately makes it possible to improve the rejection between visible and infrared wavelengths in each channel.
[0075] Since there is no charge injection through the electrodes, this architecture further enables the limitation of dark current.
[0076] Noise has also been reduced, while allowing for simpler manufacturing.
[0077] Because of the physical separation between visible and infrared pixels, this technique also enables the limitation of crosstalk between pixels.
[0078] Figure 2 An embodiment of the electronic device 200 is illustrated schematically.
[0079] In the example shown, device 200 includes optical components similar to component 120.
[0080] In the illustrated example, device 200 also includes an array 230 of five pixels 231(G), 232(B), 233(R), 234(G), and 235(Ir) arranged perpendicular to component 120. Each of the pixels 231(G), 232(B), 233(R), and 234(G) of array 230 includes, for example, a single junction formed in a semiconductor substrate 245 (such as silicon) and is configured to convert the visible wavelength it receives into electrical charge.
[0081] Pixel 235 includes, for example, a heterojunction formed from layer 260, which has quantum dots and is arranged to contact, for example, a silicon-based semiconductor structure (e.g., a region of a bulk semiconductor substrate). Therefore, in this context, the term "heterojunction" is understood to refer to a junction between the quantum dot-containing layer and one of: i) a layer of semiconductor material for the substrate, or ii) a region of the bulk semiconductor substrate. This semiconductor structure is also present, for example, in pixels 231, 232, 233, and 234, which limits design costs.
[0082] For example, layer 260 is disposed only in pixel 235 and does not protrude above pixels 231, 232, 233, and 234 in the visible field (i.e., pixels sensitive to the wavelength range of visible light). This allows for improved optical rejection between pixels 231, 232, 233, and 234 and pixel 235. The positioning of layer 260 is performed, for example, by etching the layer containing quantum dots or by local deposition.
[0083] Quantum dots or semiconductor nanoparticles are nanoscale material structures. When photons are incident on a nanoscale material structure, electron-hole pairs are generated.
[0084] Quantum dots comprise a semiconductor core. They may also include a shell, preferably made of a semiconductor material, that encloses the core to protect and passivate it. Quantum dots also include ligands, organic aliphatic compounds, organometallic molecules, or inorganic molecules that extend from the shell and passivate, protect, and functionalize the semiconductor surface.
[0085] The composition of quantum dots can be selected from the following materials. For example, the core is made of materials or alloys 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 outer shell is made of, for example, materials or alloys of the following: 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.
[0086] Preferably, all core dimensions are less than 20 nm, for example, in the range of 2 nm to 15 nm. Specifically, the diameter of each quantum dot is preferably in the range of 2 nm to 15 nm. Diameter refers to the diameter of the smallest sphere that the quantum dot can inscribe.
[0087] The size and dimensions of quantum dots can be selected to absorb any wavelength over a wide wavelength range with significant absorption rates. For example, sizes and dimensions of quantum dots operating at wavelengths greater than 1 μm (e.g., in the range from 1 μm to 3 μm) can be found, encompassing both near-infrared and short-wave infrared. For instance, layer 260 comprises quantum dots made of InAs, PbS, HgTe, or PbSe with radii less than 10 nm, for example, to obtain absorption peaks associated with quantum confinement in the short-wave infrared (e.g., 1130 nm or 1360 nm).
[0088] Layer 260 has a thickness, for example, in the range of 100 nm to 500 nm.
[0089] In the example shown, pixel 235 is positioned at the center of array 230, surrounded by pixels 231, 232, 233, and 234. Figure 1 Compared to array 130, the area used to receive light incident on each of pixels 231, 232, 233 and 234 is reduced by the portion of space occupied by the central pixel 235.
[0090] In the example shown, pixel 233 is separated from pixel 232 via pixel 235, and pixel 231 is separated from pixel 234 via pixel 235. This allows for improved crosstalk performance.
[0091] In the example, the surface area of array 230 is similar to that of array 130.
[0092] In the example shown, filter 122 is arranged perpendicular to pixel 231 and at least partially perpendicular to pixel 235; filter 126 is arranged perpendicular to pixel 233 and at least partially perpendicular to pixel 235; filter 128 is arranged perpendicular to pixel 234 and at least partially perpendicular to pixel 235; and filter 124 is arranged perpendicular to pixel 232 and at least partially perpendicular to pixel 235.
[0093] In the example, device 200 includes multiple, even dozens, hundreds, or preferably thousands of pixel arrays 230.
[0094] In an example not shown, each array 230 includes a single pixel in pixels 231, 232, 233, or 234, as well as pixel 235. In this case, only one of filters 122, 124, 126, or 128 is present in the associated component 120.
[0095] In an example not shown, each array 230 includes only two pixels from pixels 231, 232, 233, or 234, and pixel 235. In this case, the associated component 120 contains only two filters from filters 122, 124, 126, or 128.
[0096] In an example not shown, each array 230 includes only three pixels from pixels 231, 232, 233, or 234, and pixel 235. In this case, the associated component 120 contains only three filters from filters 122, 124, 126, or 128.
[0097] In the example shown, optical element 210 (OPT) is inserted between at least one filter of filter 122, 124, 126, 128 of component 120 and at least one pixel of pixel 231, 232, 233, 234, 235 of array 230. In other words, optical element 210 is arranged perpendicularly to at least one region of filter 122, 124, 126, 128 of component 120 and between the plane forming the filter and the plane of layer 260 to cover at least pixel 235.
[0098] The filters and optical elements 210 of component 120 are configured such that pixels 231, 232, 233, 234 receive the wavelength of the color associated with the filter and the infrared wavelength, and that pixel 235 receives only the infrared wavelength.
[0099] In the example, optical element 210 includes an interferometer or Bragg mirror configured to allow infrared wavelengths to pass toward pixel 235 and reflect visible wavelengths.
[0100] In the example, the interference mirror is formed by stacking, for example, SiON layers and amorphous silicon a-Si layers with thicknesses of 125 nm and 50 nm, respectively.
[0101] Interferometers or Bragg mirrors enable improved rejection of visible wavelengths, which could contaminate signals generated by pixels dedicated to infrared.
[0102] In another example, optical element 210 includes an optical steering element configured to direct infrared wavelengths toward pixel 235 and visible wavelengths toward one of pixels 231, 232, 233, and 234. In other words, the optical steering element is configured, for example, to deflect wavelengths of the visible range originating from filters 122, 124, 126, or 128 at one angle and wavelengths of the infrared range originating from filters 122, 124, 126, or 128 at another angle. Thus, infrared wavelengths are directed toward pixel 235, while visible wavelengths are directed toward at least one of pixels 231, 232, 233, and 234.
[0103] In the example, the optical steering element 210 includes a metasurface. This metasurface includes pillars or reliefs made of, for example, a material with a high optical index (or refractive index) (e.g., greater than 2), such as a metal oxide (e.g., TiO2). In the example, these pillars are arranged in an array of lower optical indices, such as nitrides (e.g., silicon nitride).
[0104] It can simulate the arrangement and shape of columns or reliefs with high optical index to obtain different deflections according to the desired wavelength.
[0105] The implementation of the optical steering element enables the improvement of the external quantum efficiency of each channel, as this compensates for the size reduction of pixels 231, 232, 233, and 234 used to integrate pixel 235.
[0106] In the example, optical element 210 includes an interferometer or Bragg mirror and an optical steering element, wherein the interferometer is inserted between pixel 235 and the optical steering element.
[0107] In the example shown, the cross-sectional plane AA passes vertically through filters 124 and 126, optical element 210, layer 260, and pixels 232, 233, and 235.
[0108] Figure 3 It shows Figure 2 A cross-sectional view along plane AA of an embodiment of device 200.
[0109] In the example shown, pixels 232, 235, and 233 are arranged one after another. Pixel 235 is placed between pixels 232 and 233, which helps to avoid crosstalk.
[0110] In this example, pixel 232 is arranged in a line perpendicular to filter 124, pixel 235 is arranged in a line perpendicular to a portion of filter 124 and a portion of filter 126, and pixel 233 is arranged in a line perpendicular to filter 126.
[0111] In the example shown, optical element 210 is inserted between the plane formed by filters 124 and 126 and the plane formed by the filter-facing surfaces of pixels 232, 233 and 235.
[0112] In the illustrated example, optical element 210 includes an optical steering element 309 and an interferometer 330. In this example, the optical steering element 309 extends below filters 124 and 126 to allow for differential deflection of visible wavelengths λvis1 and λvis2 relative to the infrared wavelength λswir. Therefore, pixel 232 receives the visible wavelength λvis1 of the color from filter 124, pixel 233 receives the visible wavelength λvis2 of the color from filter 126, and pixel 235 receives the infrared wavelength λswir originating from optical element 210. The optical steering element 309 includes high-optical-index pillars 321 arranged in an array 322 of lower optical index pillars. The optical indexes of the pillars 321 and the array 322 can also be reversed.
[0113] In the example shown, optical element 210 also includes an interferometer 330. In this example, the interferometer comprises a double stack of two layers 332 and 333. Layer 332 is, for example, a layer made of SiON with a thickness of approximately 125 nm, and layer 333 is, for example, a layer made of amorphous silicon with a thickness of approximately 50 nm. The purpose of this interferometer is to allow infrared wavelengths to pass through while rejecting (i.e., by reflection) visible wavelengths λvis1 or λvis2. The number of layers 332 and 333 can be greater than two, for example, approximately ten layers. The interferometer is arranged, for example, such that it covers only pixel 235 in the horizontal direction, without covering pixels 232 and 233.
[0114] In the example shown, the interference mirror is laterally surrounded by, for example, an insulator 354, which is different from, for example, the insulator 322 surrounding the column 321. This insulator is, for example, silicon oxide.
[0115] exist Figure 3 In the example, a layer 260 (QF-N) comprising quantum dots is vertically positioned between the interferometer 330 and the structure 301 of the pixel 235, and is positioned such that it protrudes slightly beyond the structure 301 in the horizontal direction. Layer 260 is laterally surrounded, for example, by an insulator 354.
[0116] In the example shown, pixels 232 and 233, which are dedicated to the visible range, include a structure 301 similar to that of pixel 235.
[0117] Structure 301 is formed in a semiconductor substrate (e.g., silicon). Structure 301 includes a first layer 352 (Si-N) of a first conductivity type (e.g., type N). In the example, the thickness of layer 352 is approximately 5 μm to 10 μm.
[0118] In the example, the first layer 352 of pixel 232 receives the visible wavelength λvis1 of the color of filter 124, and the first layer 352 of pixel 233 receives the visible wavelength λvis2 of the color of filter 126.
[0119] The first layer 352 of the structure 301 of pixel 235 contacts the quantum dot layer 260 on the side facing the optical filter. This forms a heterojunction of pixel 235. Layer 260 includes quantum dots of, for example, the same conduction type as layer 352 (e.g., type N). Layer 260 forms the photosensitive layer of the created photodiode. In pixel 235, the heterojunction receives infrared wavelengths λswir from filters 124, 126 and from optical element 210 and converts them into electron-hole pairs.
[0120] In the example, adjacent pixels 232, 233, and 235 are electrically insulated from each other by conductive walls 357, which are insulated by electrical insulators 358 and configured to be coupled to a voltage rail that receives a negative voltage (e.g., -1V). This further enables the depletion of the first layer 352 of the different pixels and the creation of pinned diodes that absorb photogenerated electrons.
[0121] In the example shown, pixel 235 includes a region 356 (P++Si) doped according to a second conductivity type (e.g., P), which is at least partially in contact with the first layer 352. This region 356 is further disposed between walls 357, 358 and the first layer 352. In the example, the dopant concentration of region 356 is high (P++), for example, 10. 18 at.cm -3 In the case of pixel 235, region 356 advantageously allows for adaptation to the bandgap difference between layer 260 and the first layer 352 of this pixel, thereby allowing the evacuation of photogenerated holes in layer 260. The negatively biased walls and the heavily doped region 356 with a second conduction type create an electric field, thereby improving the field effect. The arrangement of region 356 further facilitates the avoidance of dark current effects. In the example, region 356 is optional or has a lower dopant concentration.
[0122] In the example shown, pixels 232 and 233, dedicated to the visible range, also include a region 356 arranged similarly to pixel 235, except that region 356 does not contact the quantum dot layer, but rather contacts an insulator on the surface of the first layer 352 covering the respective pixel. Region 356 is optional for these pixels dedicated to the visible range, although it is advantageous for amplifying silicon depletion and limiting dark current.
[0123] In the illustrated example, each pixel 232, 233, 235 includes a sensing node 361 coupled (preferably connected) to a structure forming a vertical MOS-type transistor, such as a cylinder. This transistor is formed by a block 368 of a first conduction type (e.g., type N), having a high dopant concentration, contacting the sensing node 361 and configured to form a channel. This block 368 is surrounded by a control gate (e.g., a vertical cylinder), formed by a conductive core 359 (e.g., made of polysilicon), which is insulated from the block 368 by an insulator 365 (e.g., silicon oxide). A block 363, as part of layer 352, is arranged to contact the block 368 while being surrounded by the insulator 365. For example, a region 356 of each pixel is coupled to the control gates 359, 365 according to a block 362 doped according to a second conduction type. This block 362 enables the electrostatic isolation of the pixel's transistors, such as amplifiers and transmission transistors, and controls the potential of layer 356 to expel photogenerated electrons. By negatively biasing the control gate, the channel is closed to store photogenerated electrons; and by positively biasing the control gate, electrons are expelled to form the signal of the corresponding pixel. Thus, pixels 232 and 233 generate signals originating from visible photons related to the color of their respective filters, while pixel 235 generates a signal originating from infrared photons passing through filters 124 and 126.
[0124] In the example shown, color filters 124 and 126 are topped with microlenses 302 and 304, respectively. These microlenses enable the incident light (such as...) to be filtered. Figure 3 (As shown by the arrow in the image) Focuses on the associated filter and pixel.
[0125] Figure 4 It shows Figure 2 A cross-sectional view of another embodiment of the device 200.
[0126] Figure 4 Examples and Figure 3 The example is similar, except that layer 352 of pixel 235 includes a notch 452 in which a portion of layer 260 is disposed. This allows for the addition of a field effect. This notch 452 is obtained, for example, by etching layer 352.
[0127] Figure 5 It shows Figure 2 Another embodiment of the device is shown in a cross-sectional view along plane AA.
[0128] The example shown is the same as Figure 4The example shown is similar, except that an optical guiding and reflecting element 530 is optionally arranged between the photodiode structure 301 and, for example, a metal interconnect layer 520 coupled to different pixels. The optical guiding and reflecting element 530 is arranged in such a way that infrared wavelengths passing through pixels 232 and 233 can be redirected toward pixel 235, causing it to be absorbed by the photosensitive layer 260, thereby increasing the quantum efficiency of pixel 235. In the example shown, infrared wavelengths not absorbed by pixels dedicated to the visible range are reflected on the interconnect (indicated by the arrows in the figure) to be redirected toward pixel 235, which is dedicated to infrared absorption. In this example, the optical guiding and reflecting element 530 includes one or more reflective metasurfaces.
[0129] Device 200 can be used, for example, in smartphones, systems that use cameras, sensors that are sensitive to visible light and used for distance measurement, face or shape detection, or also in the automotive industry.
[0130] Various embodiments and variations have been described. Those skilled in the art will understand that certain features of these various embodiments and variations can be combined, and other variations will become apparent to those skilled in the art. In particular, although... Figure 3 and Figure 4 Optical element 210 is shown as including both optical steering element 309 and interferometer 330, but optical element 210 may also include only optical steering element 309 or only interferometer 330. In the case where optical element 210 includes only interferometer 330, pixels dedicated to visible light can receive infrared wavelengths. However, these pixels are based on, for example, silicon single junctions, and therefore the latter are almost insensitive to these infrared wavelengths.
[0131] Finally, based on the functional indications given above, actually implementing the described embodiments and variations is within the capabilities of those skilled in the art. In particular, regarding... Figure 3 and Figure 4 For example, those skilled in the art can also implement its teachings using a pixel array 230 consisting of only a single pixel dedicated to visible wavelengths and a pixel dedicated to infrared wavelengths. In this case, each component 120 can be conceived as a single visible color filter. Those skilled in the art can also implement a pixel array 230 consisting of only two pixels dedicated to visible wavelengths and one pixel dedicated to infrared wavelengths. In this case, each component 120 can be conceived as two different visible color filters. Those skilled in the art can also implement a pixel array 230 consisting of only three pixels dedicated to visible wavelengths and one pixel dedicated to infrared wavelengths. In this case, each component 120 can be conceived as two or three different visible color filters.
Claims
1. An electronic device, characterized in that, include: At least one first pixel, the first pixel having a single junction; At least one second pixel, the second pixel including a heterojunction formed of a semiconductor substrate layer in contact with the quantum dot layer; At least one first filter of a first color, the first filter being configured to allow only the wavelength and infrared wavelength of the first color to pass through, the at least one first filter being arranged perpendicular to the at least one first pixel and at least partially perpendicular to the at least one second pixel; as well as An optical element inserted between the at least one first filter and the at least one second pixel; The at least one first filter and optical element are configured such that the at least one first pixel receives the wavelength of the first color and the at least one second pixel receives only infrared wavelengths.
2. The device according to claim 1, characterized in that, Also includes: At least one third pixel, which has a single junction; At least one second filter of the second color, the second filter being configured to allow only the wavelength of the second color and the infrared wavelength to pass through, the at least one second filter being arranged perpendicular to the at least one third pixel and at least partially perpendicular to the at least one second pixel; The optical element is inserted between the at least one second filter and the at least one second pixel; The at least one second filter and optical element are configured such that the at least one third pixel receives the wavelength of the second color and the at least one second pixel receives only infrared wavelengths.
3. The device according to claim 1, characterized in that, Each of the at least one first pixel and the at least one third pixel includes a first region of a first doped layer having a first conductivity type and a second doped region of a second conductivity type.
4. The device according to claim 1, characterized in that, The heterojunction is photosensitive with an infrared wavelength.
5. The device according to claim 4, characterized in that, The single-junction pair is light-sensitive at visible wavelengths.
6. The device according to claim 1, characterized in that, The optical element includes an interferometer configured to allow infrared light to pass toward the at least one second pixel and reflect visible light.
7. The device according to claim 1, characterized in that, The optical element includes an optical steering element configured to direct infrared wavelength light toward the at least one second pixel and direct visible wavelength light toward a pixel different from the at least one second pixel.
8. The device according to claim 7, characterized in that, The optical element further includes an interferometer configured to allow infrared light to pass toward the at least one second pixel and reflect visible light, wherein the interferometer is inserted between the at least one second pixel and the optical steering element.
9. The device according to claim 7, characterized in that, The optical steering element includes a metasurface.
10. The device according to claim 9, characterized in that, The metasurface comprises metal oxide columns in a matrix including nitrides.
11. The device of claim 1, further comprising an insulating conductive wall configured to couple to a voltage rail receiving a negative voltage and positioned to electrically insulate the pixels from each other.
12. The device according to claim 1, characterized in that, The at least one second pixel includes a first doped region of a first conductivity type, the first doped region including the semiconductor substrate layer in contact with the quantum dot layer.
13. The device according to claim 12, characterized in that, The at least one second pixel further includes a second doped region of a second conduction type, which is in contact with the second layer.
14. The device according to claim 12, characterized in that, The first layer is laterally surrounded by an insulating conductive wall configured to couple to a voltage rail that receives a negative voltage, and wherein the dopant concentration of the first layer is higher than that of the second layer.
15. The device according to claim 12, characterized in that, The first layer of the first doped region of the at least one second pixel includes a notch, and wherein the second layer is at least partially formed in the notch.
16. The device according to claim 1, characterized in that, The at least one first pixel includes a first doped layer of a first conduction type and a second doped region of a second conduction type.
17. An electronic device, characterized in that, include: At least one first pixel, the first pixel having a single junction; At least one second pixel, the second pixel comprising a quantum dot-based heterojunction formed by a first region in a semiconductor substrate in contact with a quantum dot layer; At least one first filter of a first color, the first filter being configured to allow only the wavelength and infrared wavelength of the first color to pass through, the at least one first filter being arranged perpendicular to the at least one first pixel and at least partially perpendicular to the at least one second pixel; as well as An optical element inserted between the at least one first filter and the at least one second pixel; The at least one first filter and optical element are configured such that the at least one first pixel receives the wavelength of the first color and the at least one second pixel receives only infrared wavelengths.
18. An electronic device, characterized in that, include: Multiple pixels, wherein the multiple pixels are laterally insulated from each other; Each of the plurality of pixels includes a first substrate region doped with a first conductivity type; The plurality of pixels includes a first pixel having a single junction and a second pixel including a quantum dot-based heterojunction; The quantum dot-based heterojunction for each second pixel includes a quantum dot layer in contact with the upper surface of the first substrate region; At least one first filter of a first color, configured to allow only the wavelength and infrared wavelength of the first color to pass through, the at least one first filter being arranged perpendicularly to the first pixel and at least partially perpendicularly to the second pixel; and An optical element inserted between the at least one first filter and the second pixel; The at least one first filter and optical element are configured such that the first pixel receives the wavelength of the first color and the second pixel receives only infrared wavelengths.
19. The device according to claim 18, characterized in that, Each of the plurality of pixels further includes a second substrate region doped with a second conductivity type, located between a first substrate region and an insulating wall, the insulating wall providing lateral insulation between adjacent pixels of the plurality of pixels, wherein the quantum dot layer also contacts the upper surface of the second substrate region.