Electronic device
By using filters and quantum dot photodiodes in a photodiode stack structure, the problem of low reactivity of existing photodiodes at infrared wavelengths is solved, achieving efficient visible and infrared light detection, suitable for multispectral ambient light detectors and proximity sensors.
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
- 2026-06-12
AI Technical Summary
Existing photodiodes are not highly responsive in the near-infrared and short-wave infrared wavelengths, making it difficult to be sensitive to both the visible range and infrared wavelengths simultaneously. Furthermore, existing solutions are either costly or inefficient.
The structure employs a stacked configuration, including a first silicon photodiode and a quantum dot-based second photodiode, with a filter inserted between them. The filter is configured to allow infrared wavelengths to pass through and reflect visible wavelengths, utilizing quantum dots to improve infrared detection performance, while the silicon photodiode is used for visible light detection.
It achieves high-performance multispectral ambient light detection, enabling efficient detection of both visible and infrared light at a limited cost, and is suitable for multispectral ambient light detectors and proximity sensors.
Smart Images
Figure CN224356592U_ABST
Abstract
Description
[0001] Priority requirements
[0002] This application claims priority to French patent application No. FR2406707, 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 particularly to optoelectronic devices including photodiodes, and associated methods for manufacturing optoelectronic devices including photodiodes. 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: a stack including: a first silicon photodiode; a quantum dot-based second photodiode; and a first filter inserted between the first silicon photodiode and the second photodiode; wherein the first silicon photodiode is disposed between a side of the stack configured to receive incident light and the first filter; and wherein the first filter is configured to allow infrared wavelengths of the received incident light to pass through the second photodiode and reflect visible wavelengths of the received incident light back to the first silicon photodiode.
[0009] In some embodiments, the device further includes a second filter of a first color within the visible range, the second filter being configured to allow the infrared wavelength of the incident light and the wavelength of the first color to pass through to a first silicon photodiode.
[0010] In some embodiments, the first silicon photodiode is sensitive only to the visible wavelength of the received incident light.
[0011] In some embodiments, the second photodiode is primarily sensitive to the infrared wavelength of the received incident light.
[0012] In some embodiments, the second photodiode includes: a first layer comprising quantum dots and doped with a first conduction type; and a second layer configured to conduct holes originating from the first layer.
[0013] In some embodiments, the second photodiode includes a third layer comprising quantum dots and doped with a second conduction type; wherein the third layer is disposed between the first layer and the second layer.
[0014] In some embodiments, the device further includes: a second filter of a first color within the visible range, the second filter being configured to allow an infrared wavelength of incident light and a wavelength of the first color to pass through to a first silicon photodiode; and an interconnect stage including conductive interconnects disposed between the first silicon photodiode and the second filter; wherein a first conductive via, insulated from the first silicon photodiode, couples the second photodiode to the interconnect stage through the first silicon photodiode and through the first filter.
[0015] In some embodiments, the second photodiode includes a fourth layer configured to conduct electrons and block the conduction of holes, and couples the first layer to the first conductive via.
[0016] In some embodiments, the first conductive via includes a first portion made of polycrystalline silicon and a second portion made of a metallic material, the second portion being disposed between the first portion and the fourth layer.
[0017] In some embodiments, the metallic material has a work function that facilitates electron extraction.
[0018] In some embodiments, the first conductive via is made of silicon having one of a first conductivity type or a second conductivity type, and the first conductive via is in contact with the first layer.
[0019] In some embodiments, the first silicon photodiode includes a first region doped according to a first conduction type, a second region doped according to a second conduction type, and a third region formed in the first region and doped according to the first conduction type with a dopant concentration higher than that of the first region, wherein the second region is disposed between the first filter and the first region, and the third region is disposed in contact with an interconnect stage.
[0020] In some embodiments, the first filter is an interference filter comprising a periodic alternation of a SiON layer approximately 125 nm thick and an amorphous silicon layer approximately 50 nm thick.
[0021] In some embodiments, the device includes: a further stack comprising: a third silicon photodiode; a quantum dot-based fourth photodiode; and a third filter inserted between the third silicon photodiode and the fourth photodiode; wherein the third silicon photodiode is disposed between the side of the further stack configured to receive incident light and the third filter; wherein the third filter is configured to allow infrared wavelengths of the received incident light to pass through to the fourth photodiode and to reflect visible wavelengths of the received incident light back to the third silicon photodiode; a second filter of a first color in the visible range, the second filter being configured to allow infrared wavelengths of the incident light and wavelengths of the first color to pass through to the first silicon photodiode; and a fourth filter of a second color in the visible range different from the first color, the fourth filter being configured to allow infrared wavelengths of the incident light and wavelengths of the second color to pass through to the third silicon photodiode.
[0022] In some embodiments, the second and fourth filters are interference filters.
[0023] In some embodiments, the second filter is configured to allow only the wavelength of the first color and the infrared wavelength sensitive to the second photodiode to pass through; and the fourth filter is configured to allow only the wavelength of the second color and the infrared wavelength sensitive to the fourth photodiode to pass through.
[0024] In some embodiments, the first filter and the third filter are configured to allow different infrared wavelengths to pass through.
[0025] In some embodiments, a first silicon photodiode is configured to acquire an image in the visible range and a second photodiode is configured to acquire an image in the infrared range.
[0026] An embodiment provides an apparatus comprising a stack formed of at least: a first silicon photodiode; and a quantum dot-based second photodiode; wherein the first silicon photodiode is disposed between the first side of the stack configured to receive incident light and the second photodiode.
[0027] An embodiment provides a method of manufacturing an apparatus, the method comprising: forming a first silicon photodiode; and then forming a quantum dot-based second photodiode to form a stack with the first silicon photodiode; wherein the first silicon photodiode is disposed between the second photodiode and a side of the stack configured to receive incident light.
[0028] In one embodiment, the device includes a first filter inserted between a first silicon photodiode and a second photodiode, the first filter being configured to allow infrared wavelengths to pass through and reflect visible wavelengths.
[0029] In one embodiment, the device includes a second filter of at least one visible color of a first color, configured to allow only the wavelengths of the first color and infrared wavelengths to pass through.
[0030] In this embodiment, the first silicon photodiode is sensitive only to wavelengths within the visible range.
[0031] In this embodiment, the second photodiode is primarily sensitive to infrared light.
[0032] In one embodiment, the second photodiode includes: a first layer comprising quantum dots and doped with a first conduction type; and a second layer configured to conduct holes originating from the first layer.
[0033] In one embodiment, the second photodiode includes a third layer comprising quantum dots and doped with a second conduction type, and is disposed between the first layer and the second layer.
[0034] In one embodiment, the device includes an interconnect stage comprising conductive interconnects disposed between a first silicon photodiode and a second filter; wherein a first conductive via, insulated from the first silicon photodiode, couples a second photodiode to the interconnect stage through the first silicon photodiode and through the first filter.
[0035] In one embodiment, the second photodiode includes a fourth layer configured to conduct electrons and block the conduction of holes, and couples the first layer to the first via.
[0036] In one embodiment, the first via includes a first portion made of polycrystalline silicon and a second portion made of a metallic material, the second portion being disposed between the first portion and the fourth layer.
[0037] In one embodiment, the metallic material has a work function configured to facilitate electron extraction.
[0038] In an embodiment, the first via is made of silicon and has a first conductivity type or a second conductivity type, and the first via is in contact with the first layer.
[0039] In one embodiment, the first silicon photodiode includes a first region doped according to a first conduction type, a second region doped according to a second conduction type, and a third region formed in the first region and doped according to the first conduction type with a dopant concentration higher than that of the first region; the second region is disposed between the first filter and the first region; and the third region is disposed in contact with an interconnect stage.
[0040] In an embodiment, the first filter is an interference filter comprising a periodic alternation of a SiON layer approximately 125 nm thick and an amorphous silicon layer approximately 50 nm thick.
[0041] In one embodiment, the device includes: a second stack of a third silicon photodiode and a quantum dot-based fourth photodiode, the third silicon photodiode being disposed between the side of the second stack configured to receive incident light and the fourth photodiode; a third interference filter, inserted between the third silicon photodiode and the fourth photodiode, and configured to allow infrared wavelengths to pass through and reflect wavelengths in the visible range; and a fourth filter of a second color in the visible range, different from the first color, configured to allow only the wavelengths of the second color and the infrared wavelengths to pass through.
[0042] In this embodiment, the second and fourth filters are interference filters.
[0043] In this embodiment: the second filter allows only the wavelength of the first color and the infrared wavelength sensitive to the second photodiode to pass through; and the fourth filter allows only the wavelength of the second color and the infrared wavelength sensitive to the fourth photodiode to pass through.
[0044] In one embodiment, the first filter and the third filter allow different infrared wavelengths to pass through.
[0045] An embodiment provides a method for using the above-described device, the method comprising acquiring an image in the visible range from the first silicon photodiode and acquiring an image in the infrared range from the second photodiode. Attached Figure Description
[0046] 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:
[0047] Figure 1 A simplified perspective view of an example electronic device is shown;
[0048] Figure 2 It shows Figure 1 A cross-sectional view of the electronic device along plane AA;
[0049] Figure 3 It shows Figure 1 A cross-sectional view of the electronic device along plane AA;
[0050] Figure 4 It shows along Figure 2 A cross-sectional view of plane BB;
[0051] Figure 5a It shows that for Figures 1 to 3 The example is a graph of transmittance versus wavelength;
[0052] Figure 5b It shows that for Figures 1 to 3 The example is a graph of absorbance versus wavelength;
[0053] Figure 5c It shows that for Figures 1 to 3 The example is a graph of transmittance versus wavelength;
[0054] Figure 5d It shows that for Figures 1 to 3 The example is a graph of absorbance versus wavelength;
[0055] Figure 6 It shows along Figure 1 A cross-sectional view of plane AA;
[0056] Figure 7 It shows along Figure 1 A cross-sectional view of plane AA;
[0057] Figure 8a It shows that for Figure 7 The example is a graph of absorbance versus wavelength;
[0058] Figure 8b It shows that for Figure 7 The example is a graph of transmittance versus wavelength;
[0059] Figure 8c It shows that for Figure 7 The example is a graph of absorbance versus wavelength;
[0060] Figure 9 It shows Figure 2 A magnified view; and
[0061] Figure 10 It shows Figure 2 A magnified view. Detailed Implementation
[0062] 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.
[0063] For clarity, only those steps and elements useful for understanding the embodiments are shown and described in detail.
[0064] 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.
[0065] 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.
[0066] Unless otherwise specified, the expressions “approximately,” “about,” “basically,” and “around” indicate addition or subtraction of 10% or 10°, preferably 5% or 5°.
[0067] Optical detection, such as multispectral optical detection in the visible and infrared ranges, can be envisioned using a single or multiple channels of photodiodes, all based on quantum dots. However, due to the generated dark current, the detection level of quantum dots in the visible range is lower than that in the infrared range.
[0068] Using silicon instead of quantum dots to implement this or these channels is inefficient because silicon is not sensitive to infrared light (e.g., wavelengths above 1100 nm).
[0069] It is conceivable to use semiconductor layers without quantum dots for detection in the infrared range, such as SiGe or InGaAs, but obtaining these materials cheaply and satisfactorily from silicon substrates is extremely difficult. Furthermore, SiGe exhibits a considerably lower detection level compared to quantum dots.
[0070] Solutions that assemble multiple substrates are conceivable, but they are expensive.
[0071] Finally, integrating a layer with near-infrared sensitive quantum dots on the front of the device causes absorption of some of the visible radiation reaching this front side. Integrating a layer with near-infrared sensitive quantum dots on the back of the device, however, also causes attenuation of detectable visible light when back-illuminated.
[0072] To overcome these drawbacks, the embodiments provide a device comprising a stack formed of at least: a first silicon photodiode; and a quantum dot-based second photodiode; wherein the first silicon photodiode is disposed between the side of the stack configured to receive incident light and the second photodiode.
[0073] This makes it possible to obtain both high-performance visible light detection using silicon-based photodiodes and high-performance infrared detection using quantum dot-based photodiodes at a limited cost.
[0074] This further enables the development of a device that can operate as a multispectral ambient light detector and can also be integrated into a proximity sensor that operates at infrared wavelengths (such as, for example, 1130 or 1360 nm wavelengths).
[0075] In this paper, the infrared range includes, for example, short-wave infrared (SWIR) wavelengths. In other words, in this paper, infrared includes, for example, wavelengths greater than or equal to 1 μm, such as 1.1 μm, 1.130 μm, or 1360 nm. Near-infrared (NIR) wavelengths between 780 and 1 μm may also be considered in the following examples, for example by modifying the quantum dot size or properties.
[0076] Figure 1 A simplified perspective view of an example of an electronic device 300 is shown.
[0077] Electronic device 300 is, for example, an ambient light sensor for visible spectral analysis, and also a proximity sensor, specifically using short-wave infrared spectroscopy.
[0078] In the example shown, multiple optical detection channels 352, 354, 356, 358, and 360 are adjacent. An optical channel can be considered as a fairly large pixel.
[0079] In the illustrated example, each of these channels 352, 354, 356, 358, and 360 includes a first region or photodiode 312 made of a semiconductor material (such as silicon) and, for example, based on a single junction. Additionally, channels 352, 354, 356, 358, and 360 include a second region or photodiode 316, arranged, for example, at least partially perpendicular to the first photodiode 312 to form a stack. The photodiode 316 is based on quantum dots.
[0080] In the example, each channel 352, 354, 356, 358, 360 is insulated (or separated) from adjacent channels by electrical and / or optical insulators and / or trenches. In another example, each channel is wide enough that no separator or insulator is required between adjacent channels.
[0081] Channels 352, 354, 356, 358, and 360 also include, for example, an optical filter 314 or an optical steering element 314. The filter 314 is configured to allow infrared wavelengths (particularly short-wave infrared wavelengths) to pass through a second photodiode 316 located below, and to redirect visible wavelengths towards a first photodiode 312. In other words, the filter 314 is configured, for example, to deflect wavelengths in the visible region that have passed through the first photodiode without being absorbed at a certain angle, and to allow wavelengths in the infrared range to pass through or be deflected at another very small angle. Thus, infrared wavelengths are directed towards the second photodiode 316, while visible wavelengths are redirected back to the first photodiode 312.
[0082] In the example, optical filter 314 is a first interference filter 314, such as a distributed Bragg reflector, inserted between first region 312 and second region 316. In this example, the same first filter 314 is shared by different channels and arranged across the entire horizontal range of the channel. In another example, each channel has a different first filter, whose filtering characteristics may differ. In this latter example, the range of the first filter 314 is limited to the horizontal range of each channel, and the wavelengths allowed to pass through each first filter 314 can vary from one channel to another.
[0083] In another example, filter 314 is a metasurface. This metasurface includes pillars or raised areas made of a material with a high optical index (or refractive index) (e.g., greater than 2), such as a metal oxide (e.g., TiO2). In this example, these pillars are arranged in a matrix with a lower optical index (e.g., a nitride, such as silicon nitride).
[0084] It can simulate the layout and shape of columnar or protruding regions with high optical index to obtain different deflections according to the desired wavelength.
[0085] Using an optimized distributed Bragg reflector allows visible wavelengths to be reflected toward the silicon photodiode to ensure maximum absorption in the visible range. The distributed Bragg reflector is also used as a bandpass filter to allow a significant portion of the infrared spectrum to pass through the quantum dot-based photodiode. This approach is superior to methods involving the use of material sandwiched between two distributed Bragg reflectors, which produce absorption peaks defined by cavity effects. In fact, the second method produces very concave absorption that is highly sensitive to the angle of incidence of light entering the system, thus impairing sensor operation.
[0086] Each channel 352, 354, 356, 358, and 360 includes, for example, second filters 302, 304, 306, 308, and 310 of different colors in the visible range, allowing only the visible wavelengths and infrared wavelengths of the corresponding colors to pass through. The second filters of each channel are arranged above the first photodiode 312 of that channel, such that the incident light (indicated by arrows in the figure) first passes through the second filters 302, 304, 306, 308, and 310, then through the first photodiode 312, then through the first filter 314, and finally through the second photodiode 316.
[0087] In the example shown, a protective layer 318 (such as a thick oxide layer) is arranged below the photodiode 316.
[0088] In the example, the first region 312 has a thickness of a few micrometers, such as 4 μm or 5 μm, the filter 314 is about 500 nm, and the photodiode 316 is about 500 nm.
[0089] Filter 314 is configured to allow infrared wavelengths to pass through and reflect wavelengths in the visible range.
[0090] In the example, filter 314 is formed by multiple repeated stacks and consists of a high-refractive-index layer and a low-refractive-index layer. In the example, filter 314 is formed by multiple repeated stacks and consists of a SiON layer with a thickness of approximately 125 nm and an amorphous silicon layer with a thickness of approximately 50 nm. This filter allows short-wave infrared wavelengths (e.g., between 1130 nm and 1360 nm) to pass through.
[0091] Filters 302, 304, 306, 308, and 310 are formed, for example, by interference filters (e.g., distributed Bragg reflectors) or by a metasurface formed by a periodic arrangement of pillars with different optical indices. In one example, each filter 302, 304, 306, 308, and 310 is configured to allow only wavelengths centered at a given visible wavelength (different for each of the second filters) and infrared light to pass through. In another example, each of filters 302, 304, 306, 308, and 310 is configured to allow only lengths centered at a given visible wavelength (different for each of the filters 302, 304, 306, 308, and 310) and lengths centered at a given infrared wavelength (e.g., 1130 or 1360 nm) that can advantageously correspond to the wavelength of maximum absorbance of the quantum dot of the associated photodiode 316 to pass through. For example, within the visible range, filter 302 allows only blue wavelengths to pass through, filter 304 allows only green wavelengths to pass through, filter 306 allows only yellow wavelengths to pass through, filter 308 allows only orange wavelengths to pass through, and filter 310 allows only red wavelengths to pass through. In other words, the wavelengths of filters derived from a given color are, for example, more than 50%, preferably more than 80%, and even more preferably more than 90% of the spectrum associated with that color.
[0092] In another example, the device includes a single filter among filters 302, 304, 306, 308, and 310, or only two filters with different colors, or three filters that may or may not be different colors.
[0093] In this paper, green includes wavelengths approximately in the range of 520 nm to 565 nm, red includes wavelengths approximately in the range of 625 nm to 740 nm, and blue 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.
[0094] From a manufacturing perspective, in this example, a photodiode 312 is first formed in a silicon substrate via epitaxy using a back-side technique. Then, for example, passivation is oriented to form a light-receiving interface. Subsequently, a first filter 314 is formed. Then, vias are formed in a deep trench isolation (DTI) trench using ion implantation of a first conduction type or using polysilicon, through the silicon and the first filter. These vias connect a second photodiode 316 to an interconnect network disposed between the second filters 302, 304, 306, 308, 310 and the first photodiode 312. Figure 3(Not shown in the image). Then, a photodiode 316 having quantum dots in the form of one or more colloids is formed in a planar fashion, for example, by spin coating or inkjet printing. Then, the second photodiode 316 is protected, for example, with a thick oxide layer 318. Then, the substrate is flipped and second filters 302, 304, 306, 308, and 310 are formed.
[0095] Quantum dots or semiconductor nanoparticles are nanoscale material structures. When photons are incident on a nanoscale material structure, electron-hole pairs are generated.
[0096] 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.
[0097] 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.
[0098] 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.
[0099] 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 with operating 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, photodiode 316 includes quantum dots made of InAs, PbS, HgTe, or PbSe with radii less than 10 nm, for example, to obtain exciton absorption peaks in the short-wave infrared (e.g., 1130 nm or 1360 nm).
[0100] Therefore, the incident light, composed of visible and infrared wavelengths, is first filtered by filters 302, 304, 306, 308, and 310, and then passes through the first photodiode 312. Only infrared light and a very small amount of visible light pass through the first photodiode 312. Then, the first filter 314 allows only infrared light (e.g., short-wave infrared light) to propagate to the second photodiode 316. Therefore, the second photodiode 316 can be used to form a proximity sensor because infrared light (especially short-wave infrared light) is not absorbed by other components in the stack. For example, this proximity sensor uses the second photodiode (e.g., using...) Figure 3 The interconnect layer (not shown) is coupled to the detection circuit (not shown) in device 300 to obtain the result.
[0101] Figure 1 A plane AA with a thickness that extends laterally through the device 300 is shown.
[0102] Figure 2 A cross-sectional view along plane AA is shown of an example of an electronic device 300.
[0103] exist Figure 2 In the examples, only filters 304, 306, 308, and 310 are shown for clarity.
[0104] In the example shown, layer 480, also referred to as an interconnect stage (containing multiple interconnect stages), is inserted between filters 304, 306, 308, 310 and one or more photodiodes 312. Layer 480 includes, for example, one or more metal lines coupled together through vertical metal vias. Layer 480 is coupled (preferably connected) to photodiodes 312 and 316.
[0105] In the illustrated example, photodiode(s) 312 includes a first region 460 doped according to a first conduction type (e.g., N). Photodiode 312 also includes a second region 438 doped according to a second conduction type (e.g., P), for example, with a higher dopant concentration than the first region 460. In this example, photodiode 312 includes a third region 439 formed in the first region 460 and doped according to the first conduction type, with a higher dopant concentration than the first region 460. In the illustrated example, region 439 is formed, for example, by one or more wells disposed within the first region 460 and with one side contacting an interconnect stage 480. Region 438 enables the combination of holes generated in photodiode 312.
[0106] In the example, multiple photodiodes 312 can be formed adjacent to each other, for example, separated by trenches or insulators, thereby forming photodiodes 312 perpendicular to each filter 304, 306, 308, 310 in a line to form a multispectral visible light sensor.
[0107] In another example, a single photodiode 312 is formed and extends below all filters 304, 306, 308, and 310. In this case, the corresponding connection of the third region to the interconnect stage 480 allows for the definition of the level of corresponding visible light received perpendicular to each of filters 304, 306, 308, and 310, or the overall level of visible light received perpendicular to all filters 304, 306, 308, and 310.
[0108] In the example shown, the same filter 314 is arranged perpendicularly to the entire surface of filters 304, 306, 308, and 310, and is inserted between the second region 438 of photodiode(s) 312 and photodiode(s) 316. Filter 314 reflects visible radiation (λC, λG, λY, λR) that is not absorbed by the corresponding first photodiode 312 and allows infrared radiation (e.g., shortwave infrared radiation (λswir)) to pass through.
[0109] In the illustrated example, filter 314 is in contact with electron transport layer (ETL) 423, which is configured to conduct electrons and block the conduction of holes in photodiode 316. In this example, layer 423 is made of ZnO, TiO2, or AZO. In this example, photodiode 316 also includes a quantum dot layer 422 (QF-N) in contact with layer 423. Layer 422 comprises quantum dots, for example, sensitive to wavelengths centered at 1.130 μm or 1.360 μm. In this example, layer 422 is doped with a first conduction type (e.g., N). In the illustrated example, photodiode 316 also includes a hole transport layer (HTL) 428, which is configured to conduct holes originating from layer 422. This layer 428 is made of, for example, Mox, NiOx, or is p-doped.
[0110] In the example, one or more conductive vias 424, insulated from the photodiode 312, pass through the photodiode 312 and through the filter 316 to couple (preferably connect) layer 423 to interconnect stage 480. Some vias 424, such as Figure 2 The outermost via 424 is coupled (preferably connected) to layer 418 (HTL contact) arranged to contact layer 428. Layer 418 enables the formation of a low-resistance contact for draining holes in the photodiode 316. At these outer vias 424, layer 418 rises to connect to... Figure 2 These are the outermost vias in the structure. For example, this layer is insulated from layers 423 and 422 via layer 412.
[0111] In the example, layer 423 forms an electrode shared by, for example, photodiode 312 and photodiode 316, region 439 forms an electrode for, for example, photodiode 312, and layer 418 forms another electrode for photodiode 316.
[0112] In the example, multiple photodiodes 316 can be formed adjacent to each other, for example separated by trenches or insulators, thereby forming photodiodes 316 perpendicular to each filter 304, 306, 308, 310 in a line to form a proximity sensor, for example, having multiple pixels.
[0113] In the example, device 300 was used for white balance (PPG / ECG).
[0114] In another example, a single photodiode 316 is formed and extends below all filters 304, 306, 308, and 310. In this case, via (one or more) 424 and its corresponding connection to interconnect stage 480 make it possible to define the infrared level received perpendicular to each of filters 304, 306, 308, and 310, or the overall infrared level received perpendicular to all filters 304, 306, 308, and 310.
[0115] Figure 9 and Figure 10 The image shows an enlarged view C of the contact area between one of the through-holes 424 and layer 423.
[0116] exist Figure 2 The image shows a plane BB that passes horizontally through the device 300 at the level of region 439.
[0117] Figure 3 A cross-sectional view along plane AA is shown of an example of an electronic device 300 according to another embodiment.
[0118] Figure 3 Examples and Figure 2 The example is similar, except that photodiode 316 may optionally also include layer 528 (QF-P), which contains quantum dots and is doped according to a second conduction mode (e.g., P). Layer 528 is disposed, for example, between layers 422. Layer 528 forms a junction with layer 422, for example.
[0119] Figure 4 It shows Figure 2 An example of a cross-sectional view along plane BB.
[0120] In the example shown, device 300 includes multiple channels 604, 606, 608, and 610, each dedicated to a single 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, and 310. In the example, each channel extends horizontally along a portion of the horizontal footprint of the corresponding filter 304, 306, 308, and 310. Each channel includes alternating vias 424 and regions 439 arranged in an interleaved manner along multiple parallel lines in region 460 of the corresponding photodiode 312.
[0121] Via 424 includes a conductive internal portion, for example made of heavily doped silicon or polysilicon of the first conductivity type (N+). This internal portion is insulated from region 460 by an insulating trench.
[0122] In an example not shown, the interior portions of two adjacent vias 424 are doped with opposite doping types (P+ and N+) to form a P-Si / N-QF / N-Si heterojunction without a metal electrode on top.
[0123] In the example shown, each channel 604, 606, 608, 610 is insulated from adjacent channels by an insulator or insulating trench 620. This insulating trench extends vertically, for example, through filters 304, 306, 308, 310, the photodiode 312 of the corresponding channel, filter 314, and the photodiode 316 of the corresponding channel.
[0124] In the example shown, region 439 and through-hole 424 have a square cross-section, but any other shape can be imagined.
[0125] Figure 5a Showing the target Figures 1 to 3 The example is a graph of transmittance versus wavelength.
[0126] In particular, Figure 5a The examples illustrate the corresponding transmittances t304, t306, t308, and t310 for filters 304, 306, 308, and 310. In this example, filter 304 allows wavelengths centered in cyan to pass through, filter 306 allows wavelengths centered in green to pass through, filter 308 allows wavelengths centered in yellow to pass through, and filter 310 allows wavelengths centered in red to pass through. Filters 304, 306, 308, and 310 also allow short-wave infrared wavelengths λswir and higher wavelengths to pass through.
[0127] Figure 5b Showing the target Figures 1 to 3 The example is a graph of absorbance versus wavelength. More specifically, Figure 5b The absorbance of the corresponding photodiode 312 for each channel is shown as a304, a306, a308, a310.
[0128] In this example, the photodiode 312 of the corresponding channel of filter 304 absorbs (a304) a wavelength centered on cyan, the photodiode 312 of the corresponding channel of filter 306 absorbs (a306) a wavelength centered on green, the photodiode 312 of the corresponding channel of filter 308 absorbs (a308) a wavelength centered on yellow, and the photodiode 312 of the corresponding channel of filter 310 absorbs (a310) a wavelength centered on red.
[0129] The photodiodes 312 in each channel allow short-wave infrared wavelengths λswir and higher wavelengths to pass through, so that these wavelengths are available to the photodiodes 316 arranged below after passing through the filter 314.
[0130] Figure 5c Showing the target Figures 1 to 3 The example shows a transmittance versus wavelength graph. Specifically, Figure 5cThe example shown represents the transmittance tDBR of filter 314.
[0131] In the example shown, filter 314 allows short infrared wavelengths λswir and higher wavelengths to pass through, while absorbing or reflecting visible wavelengths. This enables an improvement in the blocking efficiency of photodiode 316 for visible photons.
[0132] Figure 5d Showing the target Figures 1 to 3 The example is a graph of absorbance versus wavelength. More specifically, Figure 5d The absorbance aQD of the quantum dot of photodiode 316 is shown. In this example, the absorbance is centered on short-wave infrared wavelengths λswir (e.g., 1.130 μm or 1.360 μm), which correspond to excitonic peaks.
[0133] Figure 6 A cross-sectional view along plane AA is shown of an example of an electronic device according to another embodiment.
[0134] Figure 6 Examples and Figure 3 The example is similar, except that filters 306, 308, and 310 are replaced by interferometric filters 806, 808, and 810. Each of filters 806, 808, and 810 allows only the wavelength of its corresponding color in the visible range, as well as a different infrared narrowband for each filter, to pass through. This creates multiple channels with different infrared wavelengths, each associated with an infrared band of the same dimension as the associated channel in the visible range above it.
[0135] exist Figure 6 In the example, the optional insulating trenches 830 isolate the different channels from each other via insulating filters 806, 808, 810, corresponding interconnect stages, photodiodes 312 and 316, and insulating layer 318. These trenches 830 may not be necessary because the charge carriers generated in photodiode 316 have low mobility, and because applying a vertical electric field is sufficient to prevent crosstalk between channels.
[0136] Figure 7 A cross-sectional view along plane AA is shown of an example of an electronic device according to another embodiment. Specifically, Figure 7 Examples and Figure 6The example is similar, except that filters 806, 808, and 810 are replaced by filters 306, 308, and 310, respectively. Additionally, in the example shown, for each channel, filter 314 is replaced by an interference filter or optical steering element specific to that channel. For example, the channel associated with filter 306 includes filter 906, the channel associated with filter 308 includes filter 908, and the channel associated with filter 310 includes filter 910. In this example, the infrared transmittance is different for each of filters 906, 908, and 910. This allows for the addition of channels specifically for analyzing infrared (e.g., shortwave) wavelengths.
[0137] In the example, to achieve this transmittance difference between the individual filters 906, 908, and 910, it is sufficient to modify the thickness or refractive index of the periodically repeating layers in the filters.
[0138] exist Figure 7 In one example, device 300 may include a computing unit that enables the recalculation of the spectrum in the shortwave infrared via a reconstruction matrix, for example, because photodiodes 316 in certain channels can detect multiple different infrared peaks.
[0139] Figure 8a Showing the target Figure 7 The example is a graph of absorbance versus wavelength.
[0140] In this example, for clarity, only the absorbance associated with filters 306, 308, and 310 is shown. The photodiode 312 of the corresponding channel of filter 306 absorbs (a306) wavelengths centered in green, the photodiode 312 of the corresponding channel of filter 308 absorbs (a308) wavelengths centered in yellow, and the photodiode 312 of the corresponding channel of filter 310 absorbs (a310) wavelengths centered in red.
[0141] Each channel's photodiode 312 absorbs only negligible amounts of short-wave infrared wavelengths λswir and higher wavelengths, so that these wavelengths become available to the photodiode 316 arranged below after passing through the corresponding filters 906, 908, 910.
[0142] Figure 8b Showing the target Figure 7 The example is a graph of transmittance versus wavelength. More specifically, Figure 8bThe transmittances of filters 906, 908, and 910 are shown separately. In this example, these different filters 906, 908, and 910 have corresponding transmittances t906, t908, and t910, which differ for infrared light (especially short-wave infrared). For example, the transmittance t906 of filter 906 in short-wave infrared is higher than that of filter 908, while the transmittance t908 of filter 908 in short-wave infrared is higher than that of filter 910. Before the exciton peak of the quantum dot, the transmittance t910 is almost zero.
[0143] Figure 8c Showing the target Figure 7 The example is a graph of absorbance versus wavelength.
[0144] More specifically, Figure 8c The absorbance 316a, 316b, 316c of the corresponding photodiodes 316 of the channels associated with filters 306, 308, and 310 are shown.
[0145] exist Figure 8c In the absorbance 316a, there are two intensity peaks of the same order of magnitude, and these two intensity peaks are centered on the exciton peak λswir of the quantum dot and on a portion of the infrared spectrum that is slightly shorter than the exciton peak, respectively.
[0146] In the example shown, absorbance 316b includes a first intensity peak that is below the exciton peak centered on the quantum dot's exciton peak λswir. This first peak is located in the infrared spectrum in a portion slightly shorter than the exciton peak.
[0147] In the example shown, absorbance 316c includes only the exciton peak λswir of the quantum dot.
[0148] Figure 9 An example is shown. Figure 4 A magnified view. More specifically, Figure 9 An enlarged view C shows the connection between one of the vias 424 and the layer 422 of the associated channel photodiode 316.
[0149] In the illustrated example, via 424 includes a central region or portion 1104 made of polysilicon (Poly-Si) within a deep trench isolation 1106. The deep trench isolation trench 1106 is disposed between region 460, region 438 (P-Si well), and region 1104, and its base contacts the upper surface of filter 314, thereby electrically isolating via 424 from regions 460 and 438.
[0150] In the illustrated example, the central region 1104 of the via 424 contacts a portion or region 1140 made of a metallic material having a shallow work function to facilitate electron extraction. In this example, the portion 1140 is disposed between the portion 1104 and layer 423. For example, the portion 1140 is partially disposed between region 1104 and filter 314 (DBR), and partially below filter 314, thus disposed between layer 423 (ETL) and filter 314.
[0151] In the example, region 1140 comprises multiple layers of different metallic materials with low work functions.
[0152] In the example shown, layer 423 contacts region 1140 and is sandwiched between region 1140 and layer 422.
[0153] exist Figure 9 In the example, via 424 forms a deep insulating and capacitive trench.
[0154] Figure 9 Examples of this technology advantageously enable the collection of photogenerated charges near the collection electrode, thereby forming absorption channels at different wavelengths, such as... Figure 6 and Figure 7 As described in [the text].
[0155] Figure 10 An illustration is shown according to another embodiment Figure 4 A magnified view. More specifically, Figure 10 An enlarged view C shows the connection between one of the vias 424 and the layer 422 of the associated channel photodiode 316.
[0156] In the illustrated example, via 424 includes a central region or portion 1204 within a deep trench isolation 1206, which is made of doped silicon (N-Si) of a first conductivity type (e.g., N). The deep trench isolation trench 1206 is disposed between region 460, region 438 (P-Si well), and region 1204, and its base contacts the vertical surface of filter 314, thereby electrically isolating via 424 from regions 460 and 438. In this example, region 1204 of via 424 in the illustrated example is in direct contact with layer 422.
[0157] exist Figure 10 In the example, a heterojunction is thus created between the internal region 1204 of the via and layer 422.
[0158] Figure 10 The example advantageously enables the simplification of charge collection by adjusting silicon doping to remove the potential barrier that restricts electron extraction and reduces the topology associated with the presence of metal electrodes.
[0159] For example, this device is designed for use in the automotive industry for incident light analysis.
[0160] For example, the device is intended for use in communication equipment or in computers and peripherals.
[0161] In the example, device 300 is used in an LED (light-emitting diode) lighting system to control the emitted light by analyzing the incident or emitted light.
[0162] 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 them. In particular, while examples with multiple channels have been disclosed, device 300 may include a single visible channel of one color, having a photodiode 312 and a photodiode 316. Furthermore, the use of a filter such as the described filter 314 is not mandatory, but its use is preferred to increase the rejection of visible radiation against photodiode 316.
[0163] 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 , Figure 6 and Figure 7 In the example, the connection between the through-hole 424 and the layer 422 can be understood by those skilled in the art from... Figure 9 or Figure 10 Starting with the technical solution, it was adjusted to the examples in these figures so that the internal region of the via could be coupled or connected to layer 422. As for Figure 2 , Figure 3 , Figure 6 and Figure 7 The examples provided will enable those skilled in the art to implement these examples with the opposite transmission type by using their knowledge.
Claims
1. An electronic device, characterized in that, include: A stack, comprising: First silicon photodiode; A second photodiode based on quantum dots; and A first filter is inserted between the first silicon photodiode and the second photodiode; The first silicon photodiode is disposed between the stacked side configured to receive incident light and the first filter; and The first filter is configured to allow the infrared wavelength of the received incident light to pass through the second photodiode and reflect the visible wavelength of the received incident light back to the first silicon photodiode.
2. The device according to claim 1, characterized in that, It also includes a second filter of a first color within the visible range, the second filter being configured to allow the infrared wavelength of the incident light and the wavelength of the first color to pass through to the first silicon photodiode.
3. The device according to claim 1, characterized in that, The first silicon photodiode is only sensitive to the visible wavelength of the received incident light.
4. The device according to claim 1, characterized in that, The second photodiode is primarily sensitive to the infrared wavelength of the received incident light.
5. The device according to claim 1, characterized in that, The second photodiode includes: A first layer, comprising quantum dots and doped with a first conduction type; and The second layer is configured to conduct holes originating from the first layer.
6. The device according to claim 5, characterized in that, The second photodiode includes: The third layer comprises quantum dots and is doped with a second conduction type; The third layer is located between the first layer and the second layer.
7. The device according to claim 1, characterized in that, Also includes: A second filter of a first color within the visible range, the second filter being configured to allow the infrared wavelength of the incident light and the wavelength of the first color to pass through to a first silicon photodiode; as well as An interconnect stage, the interconnect stage including conductive interconnects disposed between a first silicon photodiode and a second filter; The first conductive via, which is insulated from the first silicon photodiode, couples the second photodiode to the interconnect stage through the first silicon photodiode and the first filter.
8. The device according to claim 7, characterized in that, The second photodiode includes a fourth layer configured to conduct electrons and block the conduction of holes, and couples the first layer to the first conductive via.
9. The device according to claim 8, characterized in that, The first conductive via includes a first portion made of polycrystalline silicon and a second portion made of a metallic material, the second portion being disposed between the first portion and the fourth layer.
10. The device according to claim 9, characterized in that, The metallic material has a work function that promotes electron extraction.
11. The device according to claim 7, characterized in that, The first conductive via is made of silicon having one of a first conductivity type or a second conductivity type, and the first conductive via is in contact with the first layer.
12. The device according to claim 7, characterized in that, The first silicon photodiode includes a first region doped according to a first conduction type, a second region doped according to a second conduction type, and a third region formed in the first region and doped according to the first conduction type with a dopant concentration higher than that of the first region, wherein the second region is disposed between the first filter and the first region, and the third region is disposed in contact with an interconnect stage.
13. The device according to claim 1, characterized in that, The first filter is an interference filter, which includes a periodic alternation of a SiON layer approximately 125 nm thick and an amorphous silicon layer approximately 50 nm thick.
14. The device according to claim 4, characterized in that, include: Further stacking, which includes: Third silicon photodiode; A fourth photodiode based on quantum dots; and A third filter is inserted between the third silicon photodiode and the fourth photodiode; The third silicon photodiode is disposed between the side of the further stack configured to receive incident light and the third filter. The third filter is configured to allow the infrared wavelength of the received incident light to pass through the fourth photodiode and reflect the visible wavelength of the received incident light back to the third silicon photodiode. A second filter of a first color within the visible range, the second filter being configured to allow the infrared wavelength of the incident light and the wavelength of the first color to pass through to a first silicon photodiode; and A fourth filter of a second color, which is different from the first color in the visible range, is configured to allow the infrared wavelength of the incident light and the wavelength of the second color to pass through to a third silicon photodiode.
15. The device according to claim 14, characterized in that, The second and fourth filters are interference filters.
16. The device according to claim 15, characterized in that: The second filter is configured to allow only the wavelength of the first color and the infrared wavelength sensitive to the second photodiode to pass through; and The fourth filter is configured to allow only the wavelength of the second color and the infrared wavelength that the fourth photodiode is sensitive to to pass through.
17. The device according to claim 14, characterized in that, The first and third filters are configured to allow different infrared wavelengths to pass through.
18. The device according to claim 1, characterized in that, A first silicon photodiode is configured to acquire an image in the visible range, and a second photodiode is configured to acquire an image in the infrared range.