Electromagnetic radiation sensor device equipped with a photodiode capable of operating in photovoltaic mode
The back-to-back configuration of photodiodes with varying energy gaps in photovoltaic mode reduces dark current, enhancing sensitivity and enabling dual-band imaging by switching sensitivity bands with control voltage, addressing the limitations of existing dual photodiode sensors.
Patent Information
- Authority / Receiving Office
- JP · JP
- Patent Type
- Applications
- Current Assignee / Owner
- EYE4NIR SRL
- Filing Date
- 2024-04-17
- Publication Date
- 2026-06-30
AI Technical Summary
Dual photodiode sensors suffer from high dark current, which reduces signal-to-noise ratio and complicates readout circuit design, especially when operating in photoconductive mode.
A back-to-back configuration of photodiodes with differing energy gaps is used, where one photodiode operates in photovoltaic mode to suppress dark current, and the other operates in photovoltaic or photovoltaic mode to generate photocurrent, with control voltage switching between states to select sensitivity bands.
The solution significantly reduces dark current, allowing for higher sensitivity and improved signal-to-noise ratio, enabling operation in low-light environments and facilitating integration with CMOS technology for dual-band imaging applications.
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Figure 2026521329000001_ABST
Abstract
Description
[Technical Field]
[0001] This invention relates to a dual photodiode type electromagnetic radiation sensor. [Background technology]
[0002] Dual photodiode electromagnetic radiation sensors detect optical signals in two different spectral bands.
[0003] The first demonstration of the ability to detect optical signals in two different spectral bands by using dual photodiodes in a back-to-back configuration was reported in the paper "Dual-wavelength demultiplexing InGaAsP photodiode" by JC Campbell et al. (Applied Physics Letters 34, 401 (1979)).
[0004] This paper describes the use of two layers of InGaAsP (with different concentrations of each chemical element) as a photosensitive element in the 0.8–1.1 μm and 1.0–1.3 μm bands. This structure is deposited on an InP substrate and has three independent metal contacts.
[0005] The paper "Bias-Switchable Dual-Band HgCdTe Infrared Photodetector" by ER Blazejewski et al. (J. Vac. Sci. Tech. B, 10, 1626 (1992)) describes a back-to-back configuration for realizing a mid-infrared and far-infrared active photodetector using two HgCdTe alloys deposited on a CdZnTe substrate as active layers. In this case, the device exhibits photosensitivity in the 2–4.3 μm and 4.5–8.2 μm bands.
[0006] In the paper "Solid-state wavelength meter with InGaAsP / lnGaAs 2-diode heterostructure" by L. Colace et al. (Electronics Letters 38.735 (2002)), a method for measuring laser wavelengths in the 30 nm band is described using a back-to-back configuration with two layers of InGaAsP having different band gaps deposited on InP.
[0007] U.S. Patent No. 6342720 describes a photodetector composed of a double diode consisting of a silicon Schottky diode and a PIN-type SiGe diode.
[0008] U.S. Patent No. 6043517 discloses a photodetector that operates in two wavelength ranges and consists of two detectors positioned vertically. A silicon Schottky diode constitutes the first detector, which absorbs light with wavelengths less than 0.9 μm. The second detector (Si / SiGe diode) absorbs light with wavelengths greater than 1 μm and less than 2 μm.
[0009] The paper "Voltage-tunable dual-band Ge / Si photodetector operating in the visible and near-infrared spectral range" by E. Talamas Simola et al. (Vol. 27, No. 6; March 18, 2019, OPTICS EXPRESS 8529) describes a device that operates as a broadband photodetector, having a germanium-on-silicon (Ge-on-Si) epitaxial structure with two photodiodes connected back-to-back.
[0010] International Publication No. 2022 / 024025 describes a dual-diode device that utilizes a back-to-back electronic diode configuration and allows the absorption band to be selected by the voltage applied to the device itself.
[0011] As is well known, photodiodes can generate dark current, that is, a current unrelated to the light generation being targeted. For example, in the case of germanium photodiodes, the dark current is mainly due to generation and recombination phenomena occurring both in the bulk (i.e., inside the germanium crystal) and on the surface of the germanium itself. These phenomena can be electric field dependent and are particularly important because they reduce the signal-to-noise ratio of the photodetector when the diode is reverse-polarized, i.e., when the photodiode is operating in photoconductive mode.
[0012] More generally, high dark current limits the sensitivity of the device (the minimum amount of light it can detect) and complicates the design of readout circuits that can handle the dark current without saturation.
[0013] U.S. Patent Application Publication 2021 / 227156 describes a technique for duplicating the current of a reference diode held in the dark state to each pixel in order to reduce the effects of dark current on a pixel-by-pixel basis. It should be noted that the sensor in this document does not have a double absorption band because, by its nature, it uses unipolar pixels that cannot operate in reverse polarity.
[0014] U.S. Patent No. 10225504 discloses a dark current reduction system using dynamic electric polarization. [Overview of the project] [Means for solving the problem]
[0015] This invention addresses the challenge of providing two back-to-back photodiode type electromagnetic radiation sensors that reduce dark current by using a different implementation method than that of the prior art.
[0016] The present invention relates to an electromagnetic radiation sensor device as defined in independent claim 1, and specific embodiments thereof as defined in dependent claims 2 to 13. [Brief explanation of the drawing]
[0017] Hereinafter, the present invention will be described in detail using non-limiting examples while referring to the accompanying drawings. [Figure 1] FIG. 1 shows a circuit diagram of two photodiode sensor devices arranged back-to-back. [Figure 2] FIG. 2 shows a cross-sectional view of the structure of a sensor device integrated on a substrate of a semiconductor material in the first embodiment. [Figure 3] FIG. 3 shows a cross-sectional view of the structure of a sensor device integrated on a substrate of a semiconductor material in the second embodiment.
Embodiments for Carrying Out the Invention
[0018] In this specification, in the drawings, similar or identical elements or components are denoted by the same reference numerals.
[0019] FIG. 1 shows an example of a circuit diagram of a dual photodiode sensor device 10 (hereinafter, also simply referred to as "sensor"). The sensor device 10 includes a first photodiode PD1, a second photodiode PD2, and a control device CT.
[0020] In the illustrated example, the first photodiode PD1 includes a first anode A1 connected to the ground terminal GND and a first cathode C1 connected to the node N. The second photodiode PD2 includes a second cathode C2 connected to the node N and a second anode A2 connected to the output or readout terminal SNS. The readout terminal SNS is connected to a virtual ground terminal VGND provided by a measurement circuit (not shown) that measures the current output from the sensor device 10. This measurement circuit includes, for example, an adjustment circuit and an acquisition circuit.
[0021] Specifically, the first photodiode PD1 (hereinafter also referred to as the "PD1 diode") is obtained from a semiconductor material having an energy gap (i.e., a forbidden band) Eg1, and the second photodiode PD2 is obtained from another semiconductor material having an energy gap Eg2 < Eg1. That is, the forbidden band Eg1 is wider than the forbidden band Eg2.
[0022] The first photodiode PD1 is configured to collect radiation having a wavelength λ within a first sensitivity band that depends on its forbidden band Eg1 and convert it into an electrical signal (i.e., a photocurrent Iph). This first sensitivity band is between a first minimum wavelength λmin(PD1) and a first maximum wavelength λmax(PD1) = hc / Eg1 (where h and c are constants).
[0023] The second photodiode PD2 (hereinafter also referred to as the "PD2 diode") is configured to collect radiation within a second sensitivity band that depends on its forbidden band Eg2 and convert it into an electrical signal (the corresponding photocurrent Iph). The second sensitivity band includes wavelengths in the range from a second minimum wavelength λmin(PD2) to a second maximum wavelength λmax(PD2) = hc / Eg2, and λmin(PD2) < λmax(PD1).
[0024] For example, when the first photodiode PD1 is made of silicon, the index values of λmin(PD1) and λmax(PD1) are 400 nm and 1100 nm, respectively. When the second photodiode PD2 is made of germanium, the index values of λmin(PD2) and λmax(PD2) are 400 nm and 1600 nm, respectively.
[0025] As already described, a photodiode generates a dark current. That is, a current is generated independently of the target light generation. In the case of a germanium photodiode, the dark current is mainly due to generation and recombination phenomena occurring both in the bulk (i.e., inside the germanium crystal) and on the surface of the germanium itself. These phenomena are field-dependent and are important because they reduce the signal-to-noise ratio of the photodetector, especially in reverse polarization, i.e., when the photodiode operates in the photoconductive mode.
[0026] As illustrated in the example below, the first photodiode PD1 and the second photodiode PD2 are implemented in a back-to-back configuration. The term “back-to-back configuration” means, as used herein, that the cathodes or anodes of the two photodiodes are in direct contact. In particular, such “direct contact” can also be achieved by sharing a semiconductor material layer between the two photodiodes, which functions as a common anode or common cathode for both photodiodes.
[0027] In the circuit diagram of Figure 1, node N is introduced to indicate the direct contact region between the first cathode C1 and the second cathode C2.
[0028] The control device CT includes a control terminal CTR for applying a control voltage VCTR, a first terminal S connected to a ground terminal GND, and a second terminal D connected to a node N.
[0029] Preferably, the control device CT is a transistor, more specifically a MOSFET, and the control terminal CTR is its gate terminal. For example, the control transistor CT is an N-channel MOSFET, the first terminal S is the source terminal, and the second terminal D is the drain terminal. As can be seen from the implementation examples described later, the first photodiode PD1 and the second photodiode PD2 can be realized using semiconductor integration technology compatible with conventional CMOS (complementary metal-oxide-semiconductor) integration technology.
[0030] The following explanation will use the example where the first photodiode PD1 is made of silicon and the second photodiode PD2 is made of germanium.
[0031] The first photodiode PD1 is made of silicon and focuses visible and near-infrared light, converting it into an electrical signal (i.e., current Iph). In this case, the infrared light has, for example, a minimum wavelength λmin(PD1) of 400 nm and a maximum wavelength λmax(PD1) of 1100 nm. As is well known, the visible light (VIS) band includes the wavelength range from 400 nm to 700 nm. The near-infrared (NIR) band is the wavelength range from 700 nm to 1100 nm.
[0032] The second photodiode PD2 is composed of at least partially germanium and can focus radiation with a minimum wavelength λmin(PD2) of 400 nm and a maximum wavelength λmax(PD2) of 1600 nm, and convert it into an electrical signal (i.e., current Iph).
[0033] As is well known, the near-infrared (NIR) band is the wavelength range from 700 nm to 1100 nm, while the short-wave infrared (SWIR) band is the wavelength range from 1100 nm to 3000 nm.
[0034] In other words, as shown in the specific implementation shown in Figure 1, a sensor device 10 manufactured using silicon for the first photodiode PD1 and germanium for the second photodiode PD2 can operate in the range from visible light and near-infrared to a portion of the short-wave infrared.
[0035] Regarding the operation of the sensor device 10, please note that since no external voltage is applied to the readout terminal SNS, the potential difference between the first anode A1 and the second anode A2 is zero.
[0036] In the first operating state, the control transistor CT is turned off because a zero control voltage VCTR is applied to the control terminal CTR.
[0037] In this situation, the first photodiode PD1 and the second photodiode PD2 are connected in series. Due to the matching of the energy bands of the two different materials in contact with the two photodiodes, only the first photodiode PD1 (which has a higher energy band than the second photodiode PD2) can generate a relative photocurrent, while the second photodiode PD2 (made of germanium in this example) cannot generate a photocurrent, i.e., is suppressed. More specifically, due to the different physical properties of the two semiconductor materials (band gap width, relative permittivity, and intrinsic density of free carriers), an electric field is generated at the interface when they come into contact, and without external polarization applied, photocurrent generation is possible only by the first photodiode PD1. Even more specifically, due to the matching of the energy bands of the two semiconductors and the presence of an intrinsic electric field (internal electric field) at the interface between the two semiconductors, the charge photogenerated by the second photodiode PD2 cannot flow between the readout terminal SNS and the ground terminal GND, and as a result cannot be measured as a photocurrent.
[0038] The first photodiode PD1 is in photovoltaic mode because it is not polarized, and when it is struck by radiation within the first sensitivity band associated with the first photodiode PD1, it generates a first photocurrent Iph itself. It should also be noted that in photovoltaic mode, unlike when it is operating in photoconductive mode, no dark current flows through the first photodiode PD1.
[0039] On the other hand, as mentioned above, the second photodiode PD2 cannot generate a photocurrent even when irradiated with radiation within the second sensitivity band (simply put, due to energy band matching, the probability of collecting photogenerated charge from the second photodiode PD2 is low). Furthermore, it should be noted that in this situation without external polarization, no dark current flows through the second photodiode PD2 (this needs to be confirmed).
[0040] The second photodiode PD2 cannot generate photocurrent, but the photocurrent Iph generated by the first photodiode PD1 passes through it. The photocurrent then reaches the readout terminal SNS and is supplied from there to the adjustment circuit and acquisition circuit.
[0041] In this first operating state, the sensor device 10 exhibits a sensitivity band corresponding to the sensitivity band of the first photodiode PD1, namely the visible light (VIS) band and a portion of the near-infrared (NIR) band.
[0042] In the second operating state, the control transistor CT operates to short-circuit the first photodiode PD1 to the ground terminal GND. More specifically, a control voltage VCTR higher than the threshold of the control transistor CT itself is applied to the control terminal CTR, and the control transistor CT operates in the triode region. In this situation, the control transistor CT electrically connects its source terminal S to the drain terminal D connected to node N, and then connects its two cathodes C1 and C2 to the ground terminal GND. In this case as well, no external bias voltage is applied to the first photodiode PD1 and the second photodiode PD2.
[0043] In this second operating state, the energy band alignment of the two photodiodes differs from the previous condition, and the second photodiode PD2 enters photovoltaic mode. Therefore, when radiation within the second sensitivity band is irradiated, the second photodiode PD2 generates a corresponding photocurrent Iph. This photocurrent Iph flows into the circuit formed by the control transistor CT and the second photodiode PD2 and is drawn out from the readout terminal SNS.
[0044] In this state, note that the cathode C2 of the second photodiode PD2 is directly connected to the ground terminal GND via the control transistor CT. Therefore, the photogenerated charge from the second photodiode PD2 is collected at the ground terminal GND and does not need to pass through the first photodiode PD1 to generate a measurable photocurrent via the readout terminal SNS. In other words, by activating the control transistor CT, the photocurrent generated by the second photodiode PD2 becomes measurable via the readout terminal SNS while suppressing the collection of carriers photogenerated by the first photodiode PD1.
[0045] Furthermore, it should be noted that the second photodiode PD2, operating in photovoltaic mode, does not generate dark current, unlike when operating in photoconductive mode.
[0046] In this second operating state, the first photodiode PD1 is also in photovoltaic mode, and the photocurrent generated by the first photodiode PD1 (when exposed to radiation within the first sensitivity band) flows through the control transistor CT, effectively short-circuiting the first photodiode PD1. As a result, it does not flow through the second photodiode PD2 and does not reach the readout terminal SNS.
[0047] In the second operating state, the sensitivity band of the sensor device 10 is equal to only the second sensitivity band associated with the second photodiode PD2, that is, the range from near-infrared (NIR) to short-wave infrared (SWIR) according to the example described.
[0048] As is clear from the above explanation, the switching between sensitivity bands of the sensor device 10 is performed according to the control voltage VCTR applied to the control terminal CTR. This control voltage VCTR is lower than the threshold voltage of the control transistor CT under one operating condition, and higher than this threshold voltage under the other operating condition.
[0049] Figure 2 shows a first example of the structure of a sensor device 10 that can be realized using conventional semiconductor material integration technology compatible with CMOS integration technology. In the following description, silicon and germanium materials are referred to as examples.
[0050] As shown in Figure 2, the sensor device 10 includes a substrate 25 made of a first semiconductor material (silicon in the illustrated example) that is p-doped (weakly doped). The substrate 25 defines a first surface 30 and a second surface 32 on the opposite side.
[0051] The first surface 30 constitutes an exposed area through which electromagnetic radiation is transmitted. Note that the substrate 25 of the sensor device 10 in Figure 3 may be n-type according to another embodiment.
[0052] The first doped region 31 is formed on the substrate 25 and is made of the same material as the substrate. However, it is doped in the opposite way to the substrate 25; in this example, it is n-type doping, preferably n+-type doping. The first doped region 31 extends from the second surface 32 of the substrate 25 toward the interior of the substrate 25 itself, but does not reach the first surface 30.
[0053] Furthermore, this first doped region 31 is intended to function as a common electrode (cathode in this example) for the first photodiode PD1 and the second photodiode PD2, and therefore, according to the circuit diagram in Figure 1, it also functions as node N.
[0054] The second doped region 33 is formed within the substrate 25 and, in this example, has the same type of doping as the substrate 25, but with higher doping, i.e., p+ doping. The second doped region 33 is formed from the second surface 32 toward the interior of the substrate 25, without reaching the first surface 30, for example, to the same depth as the first doped region 31.
[0055] For example, the second doped region 33 is formed inside the substrate 25 and surrounds the first doped region 31 laterally in an open loop shape.
[0056] The second doped region 33 is intended to function as an additional electrode (anode in this example) for the first photodiode PD1.
[0057] Furthermore, the sensor device 10 includes a layer made of a second semiconductor material 34 (germanium in this example) which is positioned on the second surface 32 of the substrate 25 in contact with and completely covering the first doped region 31. Such a germanium layer 34 is, for example, intrinsic germanium. In this example, the germanium layer 34 is intended to function as the intrinsic layer of the second photodiode PD2.
[0058] In this example, a doped layer 36 (germanium) with high-concentration p-type doping (i.e., p+ doping) is placed on top of the intrinsic germanium layer 34. The doped layer 36 is intended to function as the anode of the second photodiode PD2.
[0059] A separation trench 26, preferably made of silicon dioxide, is formed within the substrate 25, which electrically isolates the second doped region 33 from the first doped region 31. The separation trench 26 is formed around the first doped region 31 to block the substrate 25 and prevent the horizontal movement of charge to the second doped region 33. The separation trench 26 may be formed in an open ring shape, similar to that described for the second doped region 33.
[0060] The third doped region 35 is formed within the substrate 25 and is made of the same material as the substrate, but has the opposite doping to the substrate 25, i.e., n-type doping, preferably strongly doped n+-type doping in this example. The third doped region 35 extends from the second surface 32 of the substrate 25 toward the interior of the substrate 25, but does not reach the first surface 30. This third doped region is intended to function as the source terminal of the control transistor CT.
[0061] An insulating material layer 27 (e.g., silicon dioxide) is formed on the second surface 32, having a central portion facing the portion of the substrate 25 located between the first doped region 31 and the third doped region 35. Preferably, the insulating material layer 27 has sides facing the first extension 28 of the third doped region 35 and the second extension 29 of the first doped region 31, respectively. The first extension 28 has the same doping as the third doped region 35, but is thinner than that region. The second extension 29 has the same doping as the first doped region 31, but is thinner than that region.
[0062] The sensor device 10 has a metal contact positioned on the second surface 32 to contact the second doped region 33, the doped layer 36, and the insulating material layer 27.
[0063] In particular, the sensor device 10 has a first metal layer positioned on a second doped region 33 (i.e., in this example, a portion of the anode of the first photodiode PD1) and a first contact C connected to the GND terminal. A1 It forms.
[0064] Furthermore, the sensor device 10 has a second metal layer positioned on top of the doped layer 36 (i.e., the anode of the second photodiode PD2 in this example), and a second contact C corresponding to the readout terminal SNS in Figure 1. A2 The third metal layer, placed on top of the insulating material layer 27, forms the control contact C, which corresponds to the control terminal CTR in Figure 1. CTR It forms.
[0065] Above the third doped region 35, in this example, is the source contact C of the control transistor CT. S There is a fourth metal layer that forms it.
[0066] In summary, the first photodiode PD1 consists of a first doped region 31 (i.e., the first cathode C1), a portion of the substrate 25, and a second doped region 33 (forming the first anode A1). The second photodiode PD2 consists of a first doped region 31 (i.e., the second cathode C2), an intrinsic germanium layer 34, and a doped layer 36 (i.e., the second anode A2). Note that the first doped region 31 functions as a common cathode for both the first photodiode PD1 and the second photodiode PD2.
[0067] The control transistor CT has a third doped region 35 that constitutes the source terminal and a control contact C that constitutes the gate terminal. CTR It consists of a first doped region 31 which also functions as a drain contact.
[0068] Furthermore, it should be noted that the fact that the first doped region 31 is common to the first photodiode PD1, the second photodiode PD2, and the control transistor CT is very advantageous because it increases the density of devices that can be realized on a single substrate.
[0069] Figure 3 shows another implementation of the sensor device 10, in which the control transistor CT does not share a common layer with the two first photodiodes PD1 and the second photodiodes PD2. In Figure 3, the same numbers as in Figure 2 represent the same layers.
[0070] The two first photodiodes PD1 and the second photodiode PD2 are, This is implemented in a manner similar to that described with reference to Figure 2, which will be easily understood by those skilled in the art from Figure 3. The control transistor CT also includes a third doped region 35 that functions as the source terminal, as already described, as well as a fourth doped region 37 that functions as the drain terminal (in this example, n-type doping, preferably high-concentration doping of n+).
[0071] In the implementation example shown in Figure 3, the doped layer 36 (i.e., the anode of the second photodiode PD2 in this example) is subjected to a first vertical metallization 38 that penetrates multiple insulating material layers (preferably silicon dioxide) 44 to form the second contact C A2 It is connected to this.
[0072] Metal ground contact C GND It is electrically connected to the second doped region 33 via the second vertical metallization 39 and to the third doped region 35 via the third vertical metallization 40.
[0073] Control Contact C CTR The integrated metal structure 42 is in contact with the insulating material layer 27 via a fourth vertical metallization 41. The integrated metal structure 42 is in contact with the first doped region 31 (i.e., the cathodes of the two photodiodes in this example) and the fourth doped region 37 (i.e., the drain terminal of the control transistor CT).
[0074] Figure 3 also shows a metallic region 43 separated from the integrated metallic structure 42 (in a direction perpendicular to the plane of Figure 3). Regarding the integration techniques that can be used for the structures in Figures 2 and 3, for example, the first doped region 31, the second doped region 33, the third doped region 35, the doped layer 36, and the fourth doped region 37 can be formed by ion implantation techniques and / or spin-on dopant and / or deposition techniques (including epitaxy, sputtering, and vapor deposition).
[0075] The intrinsic germanium layer 34 can be realized by chemical and / or physical deposition techniques such as epitaxy, sputtering, vapor deposition, or transfer such as wafer bonding.
[0076] Although the above description mentions the use of silicon and germanium, the sensor device 10 can also be manufactured from other semiconductor materials. For example, other materials that can satisfy the aforementioned relationship between the photoresponse bands of the first photodiode PD1 and / or the second photodiode PD2 include semiconductor materials selected from any of the following types. (a) III-V semiconductors (e.g., GaAs, InAs, InP) and their alloys. (b) Group II-VI semiconductors (e.g., ZnSe, ZnTe, CdSe, CdTe, HgTe, PbS, PbSe) and their alloys. (c) Group IV semiconductors (e.g., Si, Ge, GeSn) and their alloys.
[0077] Referring to Figures 2 and 3, the embodiment of the sensor device 10 described above has the advantage of being easy to manufacture and, furthermore, being a "planar" type because the metal contacts of the sensor are located on the same side as the integration surface of the substrate 25.
[0078] Because the sensor device 10 is flat, it can be monolithically integrated onto a silicon substrate together with other electronic circuits manufactured using CMOS process technology. This makes it possible to simultaneously manufacture the sensor device and the adjustment / acquisition electronic circuits on the same substrate using industry-standard similar process technologies.
[0079] The sensor device 10 can be connected to an external circuit via microsoldering technology (bump bonding, wire bonding, Cu-Cu bonding) or an electronic connection board (PCB).
[0080] The sensor device 10 can be used to realize a camera capable of acquiring images in two different frequency bands (e.g., VIS-NIR and SWIR). Furthermore, the sensor device 10 can be used to realize a spectral detection system for spectral analysis of incident light, or a hyperspectral imaging sensor system.
[0081] For example, in order to realize a two-band image acquisition camera or a hyperspectral imaging sensor system, a plurality of sensor devices 10 having the same structure as described above can be integrated on the same substrate 25 to form a two-dimensional array.
[0082] The sensor device 10 has the advantage that it can operate in two different sensitivity bands and can achieve very low dark currents in both bands, thereby realizing higher sensitivity than the prior art.
[0083] Due to the improvement in sensitivity, the sensor device 10 can be used under conditions more severe than those required by current technologies. In fact, due to the improvement in sensitivity, the sensor device 10 can be used, for example, in low-light environments where it is often impossible to use both VIS and SWIR lighting systems, such as in the automotive field.
[0084] Another advantage is that the sensor device 10 can be realized by a monolithic integration approach and is compatible with the manufacturing processes typical of CMOS electronics.
Explanation of Reference Numerals
[0085] 10 Dual Photodiode Sensor Device PD1 First Photodiode PD2 Second Photodiode CT Control Device A1 First Anode GND Ground Terminal C1 First Cathode N Node C2 Second Cathode A2 Second Anode SNS Readout Terminal VGND Virtual Ground CTR Control Terminal V CTR Control Voltage S First Terminal D Second Terminal Iph Photoelectric Current 25 Substrate 26 Separation Channels 27 Insulating material layer 28 First extension 29 Second extension 30 Page 1 31. First doping area 32 2nd page 33. Second doping area 34. Second semiconductor material layer 35. Third Doping Area 36 Doping Layers C A1 First Contact C A2 Second Contact C CTR Control Contact C S Source Contact 37. The fourth doping area 38. First Vertical Metallization 39. Second Vertical Metallization 40. The Third Vertical Metallization 41 Vertical Metallization 42 Integrated Metal Structures 43 Metal area 44 Insulating layer
Claims
1. An electromagnetic radiation sensor device (10), A first photodiode (PD1) is made of a first semiconductor having a first band gap, and its first terminal (A1) is connected to a ground terminal (GND) and a second terminal (C1). A second photodiode (PD2) is made of a second semiconductor having a second band gap different from the first band gap, and a third terminal (A2) is connected to a readout terminal (SNS) and a fourth terminal (C2) that is in direct contact with the second terminal (C1). A control device (CT) including a control terminal (CTR) that receives a control voltage (VCTR), a terminal connected to a ground terminal (GND), and a control terminal (D) connected to the second terminal (C1), Equipped with, The sensor device (10) is configured to selectively take on the following operating states: In the first state, The control device (CT) operates as an open circuit, The first photodiode (PD1) adopts a photovoltaic configuration and generates a first photocurrent (Iph), As a result of matching between the band gaps, the generation of photocurrent is suppressed in the second photodiode (PD2), and the first photocurrent reaches the readout terminal (SNS). In the second state, The control device (CT) short-circuits the first photodiode (PD1) to the ground terminal. The second photodiode (PD2) adopts a photovoltaic configuration and generates a second photocurrent (Iph) that reaches the readout terminal (SNS). Electromagnetic radiation sensor device (10).
2. The control device (CT) includes a transistor configured to be off in the first state and to take on a triode configuration in the second state. The sensor device (10) according to claim 1.
3. The second terminal (C1) and the fourth terminal (C2) are, The terminals are selected from one of the following types: both are anode terminals, or both are cathode terminals. The sensor device (10) according to claim 1.
4. The first photodiode (PD1) has a first dark current in its photoconductive configuration, The second photodiode (PD2) has a second dark current with a higher intensity than the first dark current in its photoconductive configuration. The sensor device (10) according to claim 1.
5. The first photodiode (PD1) has a first dark current in a photovoltaic configuration that is of a lower intensity than the first dark current in a photoconductive configuration. The second photodiode (PD2) has a second dark current in a photovoltaic configuration that is of a lower intensity than the second dark current in a photoconductive configuration. The sensor device (10) according to claim 2.
6. The first band gap Eg1 is larger than the second band gap Eg2. The sensor device (10) according to claim 1.
7. The sensor device (10) is A substrate (25) made of a first semiconductor material defining a first surface (30) exposed to electromagnetic radiation (EMR) and a second surface (32) opposite to the first surface, Equipped with, The substrate (25) is The substrate (25) is included in the substrate (25) so as to extend to the second surface (32), and includes a first doped region (31) having first type doping, A second doped region (33) is included in the substrate (25) so as to extend to the second surface (32), is separated from the first doped region (31) by a portion of the substrate (25), and has type 2 (p+) doping. The first photodiode (PD1) includes, Including the first doped region (31), A layer made of a second semiconductor material (34) disposed on the second surface (32) and in contact with the first doped region (31), A doped layer (36) is made of the second semiconductor material having the second type (p+) doping and is superimposed on a layer made of the second semiconductor material (34), The second photodiode (PD2) includes, A metal contact (CA1; CGND) is provided on the second surface (32) to be in contact with the second doped region (33), and a metal contact (CA2) is provided to be in contact with the doped layer (36), Equipped with, The sensor device (10) according to claim 1.
8. The first doped region (31) functions as a common anode / cathode for the first photodiode (PD1) and the second photodiode (PD2). The sensor device (10) according to claim 7.
9. A transistor is A third doped region (35) is included in the substrate (25) so as to extend to the second surface (32), has first-type doping, and is connected to the ground terminal (GND), A fourth doped region (37) is included in the substrate (25) so as to extend to the second surface (32), has the first type of doping, and is connected to the control terminal, An electrically insulating material layer (27) is disposed on the second surface (32) and has at least a central portion facing the region of the substrate (25) sandwiched between the third doped region (35) and the fourth doped region (37), A metal contact (CCTR) is placed on the electrical insulating material layer (27) and connected to the control terminal (CTR), Equipped with, The sensor device (10) according to claim 2 or 8.
10. The first doped region (31) is a first doped region (31) common to the first photodiode (PD1) and the second photodiode (PD2). The sensor device (10) according to claim 9.
11. The first semiconductor and / or the second semiconductor is a material selected from one of the following types: a) Group III-V semiconductors and their alloys; b) Group II-VI semiconductors and their alloys; c) Group IV semiconductors and their alloys. The sensor device (10) according to claim 1.
12. The first semiconductor and the second semiconductor are selected so that the sensor device (10) operates in a range from visible light and near-infrared to a portion of short-wave infrared. The sensor device (10) according to claim 1.
13. The first photodiode (PD1) and the second photodiode (PD2) are manufactured using semiconductor material integration technology compatible with complementary metal-oxide-semiconductor (CMOS) integration technology. The sensor device (10) according to claim 1.