Light detection device and electronic equipment

Abstract

This can improve the detection efficiency of photocurrent. [Solution] The photodetector comprises a semiconductor layer having a roughened main surface and a charge potential gradient in the direction normal to the main surface, and a metal layer arranged along the main surface that moves charges generated by plasmon resonance in response to the amount of incident light, which have energy greater than the potential barrier of the main surface, to the semiconductor layer.

Description

Technical Field

[0001] The present disclosure relates to a photodetection device and an electronic device.

Background Art

[0002] Infrared detection elements can acquire information that cannot be obtained with visible light, and are expected to have a wide range of applications such as in image sensors. As an infrared detection element, an infrared detection element is known that forms a metal film on the surface of a substrate and converts light into an electric current (hereinafter also referred to as a photocurrent) using a Schottky barrier formed at the interface between the substrate and the metal film. In addition, an infrared detection element with improved sensitivity to infrared rays has been proposed by forming a concave portion on the surface of the substrate (see Patent Document 1).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, in the configuration of the infrared detection element of Patent Document 1, the light absorption rate is low, and light absorption loss occurs. In addition, since the converted photocurrent becomes a diffusion current inside the substrate, the detection loss is large. Therefore, the quantum efficiency Qe becomes a low value of several percent or less.

[0005] Therefore, the present disclosure provides a photodetection device capable of improving the detection efficiency of a photocurrent.

Means for Solving the Problems

[0006] In order to solve the above problems, according to the present disclosure, a semiconductor layer having a roughened one main surface and having a potential gradient of charges in the normal direction of the one main surface, The device comprises a metal layer arranged along one main surface, which moves charges generated by plasmon resonance in response to the amount of incident light, having energy greater than the potential barrier of the one main surface, to the semiconductor layer. A light detection device is provided.

[0007] The semiconductor layer comprises a transfer circuit located on the side opposite to the main surface of the semiconductor layer, The semiconductor layer has a floating diffusion region that holds the charge transferred from the metal layer to the semiconductor layer. The transfer circuit may transfer the charge moved from the metal layer to the semiconductor layer to the floating diffusion region.

[0008] The semiconductor layer has a photoelectric conversion region, The transfer circuit may transfer the charge moved from the metal layer to the semiconductor layer and the charge photoelectrically converted in the photoelectric conversion region to the floating diffusion region.

[0009] The semiconductor layer has an impurity distribution region from the main surface to the transfer circuit in which the concentration of impurity ions changes. The charge transferred from the metal layer to the semiconductor layer may move along the internal electric field of the impurity distribution region.

[0010] Of the impurity distribution region, the region on the one-main surface side may have a lower concentration of impurity ions than the region on the transfer circuit side.

[0011] The metal layer and the semiconductor layer may be connected by a Schottky junction.

[0012] The metal layer may be disposed between the semiconductor layer and the potential barrier region having a higher potential barrier than the semiconductor layer.

[0013] The potential barrier region may have a dielectric layer.

[0014] The semiconductor layer may have at least one of a plurality of convex portions or a plurality of concave portions that are arranged two-dimensionally on the one main surface side.

[0015] The plurality of convex portions or the plurality of concave portions may have tapered side surfaces.

[0016] The inclination angle of the side surface may be 60 degrees or more.

[0017] The inclination angle of the side surface may be less than 60 degrees.

[0018] A plurality of pixels each including the semiconductor layer and the metal layer may be provided.

[0019] A pixel isolation region disposed between two adjacent pixels may be further provided.

[0020] Each of the plurality of pixels may be disposed on the one main surface side of the semiconductor layer or on the surface side facing the one main surface, and may include an optical element that controls the traveling direction of incident light. [[ID=2,5]]

[0021] The optical element may have greater asymmetry as it moves away from the optical axis of the optical element.

[0022] The metal layer may include at least one of TiN, Cu, Au, Ag, AuAg, or Al.

[0023] When the charge moving from the semiconductor layer to the metal layer is an electron, the semiconductor layer contains n-type impurity ions, When the charge moving from the semiconductor layer to the metal layer is a hole, the semiconductor layer may contain p-type impurity ions.

[0024] An optical filter that shields the metal layer from visible light and near-infrared light and transmits SWIR (Short-wave infrared radiation) light may be provided.

[0025] Furthermore, according to this disclosure, a photodetector that outputs image data, The system comprises a signal processing unit that performs signal processing on the aforementioned image data, Electronic devices will be provided. [Brief explanation of the drawing]

[0026] [Figure 1] A block diagram showing the configuration of an electronic device according to the first embodiment of this disclosure. [Figure 2] A block diagram showing the configuration of a photodetector according to the first embodiment of this disclosure. [Figure 3A] A diagram showing the first example of a stacked structure for a photodetector. [Figure 3B] A diagram showing a second example of a stacked structure for a photodetector. [Figure 4] A cross-sectional view of a pixel according to the first embodiment of this disclosure. [Figure 5] A plan view of a pixel according to the first embodiment of this disclosure. [Figure 6] A diagram showing the relationship between the charge generated by plasmon resonance and the Schottky barrier. [Figure 7] A diagram illustrating the hot carrier emission process and the drift current generated within the semiconductor layer. [Figure 8] A cross-sectional view of a pixel according to the second embodiment of this disclosure. [Figure 9] A plan view of a pixel according to a second embodiment of the present disclosure. [Figure 10] A bird's-eye view of a pixel according to the second embodiment of this disclosure. [Figure 11] Waveform diagrams showing the absorption rate of incident light at different wavelengths for multiple types of metal layers. [Figure 12A] Figure 4 shows plasmon resonance in the pixel's fine structure. [Figure 12B] Enlarged view of Figure 12A. [Figure 13A] Figure 8 shows plasmon resonance in the pixel's fine structure. [Figure 13B] Enlarged view of Figure 13A. [Figure 14] A bird's-eye view of a pixel relating to the first modification of the second embodiment of the present disclosure. [Figure 15] A cross-sectional view of a pixel relating to a second modified example of the second embodiment of the present disclosure. [Figure 16] A cross-sectional view of a pixel according to the third embodiment of this disclosure. [Figure 17] Figure 16 shows the IV characteristics of the pixels. [Figure 18] A diagram illustrating the potential barrier of a photodetector according to a fourth embodiment of this disclosure. [Figure 19] A cross-sectional view of a pixel according to the fifth embodiment of this disclosure. [Figure 20A] A first figure showing a pixel array portion according to a fifth embodiment of the present disclosure. [Figure 20B] A second figure showing a pixel array portion according to a fifth embodiment of the present disclosure. [Figure 21] A block diagram showing a solid-state imaging device according to a sixth embodiment of this disclosure. [Figure 22] A diagram showing an example of the general configuration of an endoscope system. [Figure 23] Figure 22 is a block diagram showing an example of the functional configuration of the camera and CCU. [Figure 24] A diagram showing an example of a schematic configuration of a microsurgical system. [Modes for carrying out the invention]

[0027] Embodiments of the photodetector and electronic equipment will be described below with reference to the drawings. While the main components of the photodetector and electronic equipment will be described below, there may be components and functions not shown or described. The following description does not exclude any components or functions not shown or described.

[0028] (First Embodiment) Figure 1 is a block diagram showing the configuration of an electronic device 1 equipped with a photodetector 10 according to a first embodiment of this disclosure. The electronic device 1 is, for example, a device that receives SWIR (Short-Wavelength InfraRed) light and generates image data based on the incident light. The electronic device 1 can be applied to, for example, an infrared camera or an infrared sensor. However, it is not limited to this, and the specific application and configuration of the electronic device 1 are arbitrary. Furthermore, the electronic device 1 may be configured to receive FIR (Far Infrared) light, MIR (Mid InfraRed) light, NIR (Near InfraRed) light, or visible light.

[0029] The electronic device 1 comprises a light detection device 10, an imaging lens 2, a recording unit 3, and a control unit 4.

[0030] The light detection device 10 converts incident light into photoelectric data to generate image data having grayscale information, for example. The light detection device 10 is, for example, a Contact Image Sensor (CIS).

[0031] The imaging lens 2 focuses the incident light and guides it to the photodetector 10. The recording unit 3 records the image data input from the photodetector 10 via the transmission line 5. The recording unit 3 may be located on a server connected via a network. The control unit 4 controls the imaging timing of the photodetector 10 via the control line 6. The electronic device 1 may have a signal processing unit 7 that performs image processing or machine learning processing on the image data output by the photodetector 10.

[0032] Figure 2 is a block diagram showing the configuration of a photodetector 10 according to the first embodiment of the present disclosure. The photodetector 10 comprises a pixel array section 11, a plurality of noise cancellers 12, a plurality of switches 13, and an output circuit 14.

[0033] The pixel array section 11 has multiple pixels 20 arranged in a first direction X and a second direction Y. In this specification, the left-right (horizontal) direction in Figure 2 is referred to as the first direction X, and the up-down (vertical) direction in Figure 2 is referred to as the second direction Y. A group of multiple pixels 20 arranged along the first direction X is referred to as a pixel row, and a group of multiple pixels 20 arranged along the second direction Y is referred to as a pixel column.

[0034] Multiple pixels 20 each have a photoelectric conversion element 21 and an amplifier (pixel circuit) 22. The photoelectric conversion element 21 outputs a voltage (or current) corresponding to the amount of incident light. The amplifier 22 amplifies the voltage of the photoelectric conversion element 21. When a selection signal SEL is input from a selection circuit or the like (not shown), the amplifier 22 outputs a pixel signal Vimg which is the amplified voltage of the photoelectric conversion element 21.

[0035] Multiple noise cancellers 12 and multiple switches 13 are provided, for example, for each pixel row. The noise cancellers 12 remove noise components from the pixel signal Vimg output by the amplifier 22. The switches 13 switch whether or not to input the pixel signal Vimg output by the noise cancellers 12 to the output circuit 14.

[0036] The output circuit 14 outputs the pixel signal Vimg to a device downstream of the light detection device 10, or to an image processing unit not shown in the diagram.

[0037] The light detection device 10 can be composed of, for example, a stacked chip made by stacking multiple chips. Figure 3A shows a first example of the stacked structure of the light detection device 10. The light detection device 10 in Figure 3A has a two-layer structure composed of a pixel chip b1 and a logic chip b2 bonded together in that order. These chips are joined by vias or the like. Note that the pixel chip b1 and the logic chip b2 may be joined by Cu-Cu bonding or bumps in addition to vias.

[0038] For example, multiple pixels 20 within the pixel array section 11 are arranged on the pixel chip b1. For example, multiple noise cancellers 12, multiple switches 13, and an output circuit 14 are arranged on the logic chip b2. The logic chip b2 may also contain a selection circuit that inputs a selection signal SEL to the pixel array section 11, or a control circuit that controls the noise cancellers 12 and switches 13, etc.

[0039] Figure 3B shows a second example of the stacked structure of the photodetector 10. The photodetector 10a in Figure 3B has a three-layer structure formed by bonding a first pixel chip b3, a second pixel chip b4, and a logic chip b2 in that order. For example, multiple photoelectric conversion elements 21 are arranged on the first pixel chip b3. For example, multiple amplifiers 22 are arranged on the second pixel chip b4. By arranging multiple amplifiers 22 on the second pixel chip b4, the photodetector 10a can increase the ratio of the area of ​​the photoelectric conversion elements 21 to the total chip area, thereby improving sensitivity and enabling miniaturization of the chip.

[0040] Furthermore, the components placed on each chip are not limited to those described above. The photodetector 10 may also be composed of four or more stacked chips, or it may be composed of a single flat chip.

[0041] Figure 4 is a cross-sectional view of a pixel 20 according to the first embodiment of the present disclosure. Figure 5 is a plan view of a pixel 20 according to the first embodiment of the present disclosure. Figures 4 and 5 show two adjacent pixels 20. Figure 4 shows a cross-section along the line A-A' in Figure 5.

[0042] The pixel 20 in Figure 4 has a semiconductor layer 25 and a metal layer 26. The semiconductor layer 25 and the metal layer 26 constitute at least a part of the photoelectric conversion element 21.

[0043] The semiconductor layer 25 has a roughened main surface (hereinafter also referred to as surface A1). Specifically, surface A1 of the semiconductor layer 25 has a microstructure (metasurface structure) that includes a plurality of fine recesses. Specifically, the microstructure of the semiconductor layer 25 has a plurality of pores 27.

[0044] The holes 27 are arranged periodically in a two-dimensional direction, as shown in Figure 5. The holes 27 are, for example, square holes. The planar shape of the holes 27 is arbitrary. For example, the holes 27 may be circular holes. Alternatively, the semiconductor layer 25 may have periodically arranged protrusions (for example, projections) instead of holes 27.

[0045] The semiconductor layer 25 has a photoelectric conversion region PD and a floating diffusion region FD on the surface opposite to surface A1 (hereinafter also referred to as surface A2). The photoelectric conversion region PD receives incident light to the pixel 20 and generates an electric charge through photoelectric conversion.

[0046] The semiconductor layer 25 contains, for example, silicon (Si). The semiconductor layer 25 also contains impurities of a first conductivity type (e.g., n-type). Furthermore, the photoelectric conversion region PD and the floating diffusion region FD contain higher concentrations of the first conductivity type impurities than other regions of the semiconductor layer 25.

[0047] Furthermore, the semiconductor layer 25 has a potential gradient of charge in the direction S normal to surface A1. The semiconductor layer 25 has a potential gradient such that charge moves from surface A1 to surface A2. Details of the potential gradient of the semiconductor layer 25 will be described later.

[0048] The metal layer 26 is positioned along the surface A1 of the semiconductor layer 25. The metal layer 26 is, for example, a thin metal film deposited on the microstructure on the surface A1 side of the semiconductor layer 25. The metal layer 26 is connected to the microstructure of the semiconductor layer 25 by a Schottky junction, forming a Schottky barrier at the interface between the metal layer 26 and the semiconductor layer 25.

[0049] The metal layer 26 contains a metal with a high work function. The metal layer 26 may contain at least one of the following: titanium nitride (TiN), copper (Cu), gold (Au), silver (Ag), gold-silver alloy (AuAg), or aluminum (Al).

[0050] The metal layer 26 absorbs incident light through plasmon resonance. Furthermore, the metal layer 26 transfers at least some of the charge (e.g., electrons e) generated by plasmon resonance to the photoelectric conversion region PD within the semiconductor layer 25.

[0051] A transfer circuit TRG is positioned on the A2 side of the semiconductor layer 25. The transfer circuit TRG is, for example, a transfer transistor. The transfer transistor turns on when a transfer signal is input to the gate electrode or base electrode, and transfers the charge generated by the photoelectric conversion region PD and the charge that has moved from the metal layer 26 to the semiconductor layer 25 to the floating diffusion region FD. The transfer circuit TRG constitutes at least a part of the amplifier 22.

[0052] The floating diffusion region FD holds the charge transferred to the transfer circuit TRG. Amplifier 22 outputs a pixel signal Vimg based on the charge held in the floating diffusion region FD.

[0053] Pixel separation regions 28 are placed between multiple adjacent pixels 20. The pixel separation regions 28 prevent color mixing by preventing photons incident on a pixel 20 from flowing into adjacent pixels 20.

[0054] The pixel isolation region 28 may have, for example, DTI (Deep Trench Isolation) or FTI (Full Trench Isolation). The pixel isolation region 28 may be formed of an insulator such as silicon oxide (SiO2) or alumina (AlO2), or it may be formed of a metal (for example, Al). Alternatively, the pixel isolation region 28 may be formed of a multilayer film of metal and semiconductor, or a dielectric multilayer film (for example, a multilayer film of SiO2 and AlO2).

[0055] The pixel 20 may be configured to receive incident light La from the A1 side of the semiconductor layer 25 (hereinafter also referred to as the surface-illuminated type). Alternatively, the pixel 20 may be configured to receive incident light Lb from the A2 side of the semiconductor layer 25 (hereinafter also referred to as the back-illuminated type). If the semiconductor layer 25 contains Si, it can transmit SWIR light. As a result, the metal layer 26 and the photoelectric conversion region PD can receive incident light Lb from the A2 side.

[0056] The following section describes the movement of charges generated by plasmon resonance. Figure 6 shows the relationship between the charges generated by plasmon resonance and the Schottky barrier. The following section describes an example of a surface-irradiated type.

[0057] When the metal layer 26 receives incident light La, the free charge (carrier, e, for example, electron e) on the surface of the metal layer 26 is excited, and a plasmon is generated corresponding to the amount of incident light La. When the vibration of the incident light La resonates with the plasmon (plasmon resonance), the energy of the incident light La is absorbed by the metal layer 26. Note that in Figure 6, the free charge (carrier) is shown as one representative charge from among the multiple charges inside the metal layer 26.

[0058] The energy of a photon in incident light La is expressed as hv (h: Planck's constant, v: frequency of incident light La). The free charge inside the metal layer 26 absorbs this energy hv and becomes excited, becoming a hot carrier with excess energy E0.

[0059] The semiconductor layer 25 in Figure 6 has a Fermi level Ef, conduction band energy Ec, and valence band energy Ev. A Schottky barrier exists at the interface between the semiconductor layer 25 and the metal layer 26. φb is formed.

[0060] When the excess energy E0 of the hot carriers is greater than the Schottky barrier (i.e., E0 > φb), the hot carriers move to the semiconductor layer 25 with an emission probability P(E0) corresponding to the excess energy E0.

[0061] Figure 7 illustrates the hot carrier emission process and the drift current generated within the semiconductor layer 25. When hot carriers with excess energy E0 collide with the Schottky barrier, they are emitted into the semiconductor layer 25 with a predetermined probability P0. Of the hot carriers, those that are not emitted into the semiconductor layer 25 with probability (1-P0) travel back and forth across the metal layer 26 and collide with the Schottky barrier again. In other words, hot carriers may collide with the Schottky barrier multiple times.

[0062] The excess energy of the hot carrier decays with each round trip of the metal layer 26. The hot carrier has excess energy E0 when it collides with the Schottky barrier for the first time. In the second collision, the excess energy of the hot carrier becomes E1, which is less than E0. The excess energy En of the hot carrier after the (n+1)th collision (where n is a non-negative integer) is given by En = E0exp(-(2n-1)t / L), where t is the thickness of the metal layer 26 and L is the attenuation length of the hot carrier.

[0063] Furthermore, the probability Pn that a hot carrier with the above excess energy En collides with the Schottky barrier and is emitted into the semiconductor layer 25 in that collision is given by Pn = (1 - √(φb / En)) / 2, where En > φb. The probability P that a hot carrier is emitted into the semiconductor layer 25 for the first time in the (n+1)th collision is... t n is P t n = (1-P0)(1-P1)···(1-Pn-1)Pn. Note that the probability P of hot carriers being emitted into semiconductor layer 25 in the first collision is given by P. t 0 is P t 0 = P0 = (1 - √(φb / E0)) / 2. Also, if we let k be the largest value of n that satisfies En > φb (i.e., Ek > φb and Ek + 1 ≤ φb), then the release probability P(E0) in Figure 6 is P(E0) = Pt 0+P t 1+···+P t It is represented as k.

[0064] The larger the emission probability P(E0) mentioned above, the larger the photocurrent obtained in the semiconductor layer 25. Also, the smaller the Schottky barrier φb, the larger the emission probability P(E0). Therefore, to increase the photocurrent in the semiconductor layer 25, it is desirable for the Schottky barrier φb to be small. On the other hand, it is desirable for the Schottky barrier φb to be large enough to suppress the dark current.

[0065] Furthermore, the efficiency of plasmon resonance in the metal layer 26 varies depending on the thickness, material, and microstructure of the metal layer 26. To improve the overall light absorption efficiency of the pixel 20, it is desirable to adjust not only the emission probability P(E0) but also the composition of the metal layer 26.

[0066] Figure 7 illustrates the impurity distribution region D and potential gradient of the semiconductor layer 25. Figure 7 shows the change in the concentration of impurity ions (hereinafter also simply referred to as impurity concentration) in the normal direction S, i.e., the depth direction, in the impurity distribution region D. In Figure 7, the impurity concentration is shown by the density of hatches, and the higher the impurity concentration, the higher the density of hatches.

[0067] As shown in Figure 7, the impurity distribution region D of the semiconductor layer 25 is formed such that the impurity concentration decreases from the A2 side to the A1 side. The above impurity distribution region D can be formed, for example, by implanting impurity ions from the A2 side of the semiconductor layer 25. As a result, the impurity concentration is high on the A2 side and low on the A1 side, thus forming the impurity distribution region D shown in Figure 7.

[0068] Due to the impurity distribution region D described above, a potential gradient is formed in the semiconductor layer 25 in Figure 7 in the normal direction S.

[0069] Charges that have moved from the metal layer 26 to the semiconductor layer 25 generate a drift current directed toward the photoelectric conversion region PD by the internal electric field of the impurity distribution region D in the semiconductor layer 25. This allows for efficient transfer of charges generated in the metal layer 26 to the photoelectric conversion region PD, thereby improving the detection efficiency of the photocurrent in the pixel 20.

[0070] As a comparative example, consider the case where the impurity distribution region D shown in Figure 7 is not formed in the semiconductor layer 25. In this case, the charge that moves from the metal layer 26 to the semiconductor layer 25 moves randomly due to diffusion current and cannot be efficiently collected in the photoelectric conversion region PD, resulting in a loss of photocurrent readout.

[0071] As described above, in pixel 20, SWIR light can be efficiently detected due to the impurity distribution region D and microstructure of the metal layer 26 and semiconductor layer 25.

[0072] The pixel array 11 may include pixels that detect visible light or the like. For example, the pixel array 11 may contain a mixture of pixels in which at least a part of the metal layer 26, the impurity distribution region D of the semiconductor layer 25, and the microstructure of the semiconductor layer 25 is omitted, and the pixels 20 shown in Figure 4.

[0073] As described above, the photodetector 10 according to the first embodiment of this disclosure includes a semiconductor layer 25 having a charge potential gradient in the direction S normal to the roughened main surface A1. In the semiconductor layer 25, the drift current directed toward the photoelectric conversion region PD can efficiently move the charge generated in the metal layer 26 to the photoelectric conversion region PD, thereby improving the detection efficiency of the photocurrent of the pixel 20.

[0074] The potential gradient of the semiconductor layer 25 can be formed, for example, by an impurity distribution region D such that the impurity concentration decreases from the A2 side to the A1 side.

[0075] Furthermore, in the light detection device 10 according to the first embodiment of this disclosure, the pixel separation region 28 can prevent color mixing between pixels 20.

[0076] (Second embodiment) Figure 8 is a cross-sectional view of a pixel 20a according to the second embodiment of the present disclosure. Figure 9 is a plan view of a pixel 20a according to the second embodiment of the present disclosure. Figure 10 is a bird's-eye view of a pixel 20a according to the second embodiment of the present disclosure. The pixels 20a in Figures 8 to 10 differ from the pixel 20 in Figure 4 in that they have a plurality of protrusions having tapered sides instead of holes 27. Specifically, the pixels 20a in Figures 8 to 10 have a plurality of needle-like structures 31.

[0077] Similar to pixel 20 in Figure 4, a potential gradient in the normal direction S can be applied to pixel 20a in Figure 8. This improves the photocurrent detection efficiency of pixel 20a.

[0078] The multiple needle-like structures 31 may be arranged periodically, as shown in Figure 9. In the example of Figure 10, each of the multiple needle-like structures 31 has a square pyramidal shape, but is not limited to this. For example, the needle-like structures 31 may have any conical shape, such as a cone or a polygonal pyramidal shape. Alternatively, some of the multiple needle-like structures 31 may have a cone shape, while others may have any polygonal pyramidal shape.

[0079] Figure 8 shows the base angle Ra (angle of inclination of the tapered side surface) of the needle-like structure 31. The base angle Ra is, for example, 60 degrees or more.

[0080] In the pixel 20a of Figure 8, the surface area of ​​the metal layer 26 can be increased compared to the pixel 20 of Figure 4 due to the multiple needle-like structures 31. This improves the light absorption rate of the metal layer 26 and enhances the efficiency of plasmon resonance in the metal layer 26, thereby further improving the photocurrent detection efficiency of the pixel 20a.

[0081] Furthermore, the pixel 20a may have a configuration having multiple frustums or the like instead of multiple needle-like structures 31. The pixel 20a can also increase the surface area of ​​the metal layer 26 by having a frustum with tapered sides.

[0082] Below, we will explain the effect of improving the light absorption rate and plasmon resonance efficiency of pixel 20a in Figure 8, based on the simulation results. Figure 11 is a waveform diagram showing the absorption rate of incident light at different wavelengths for multiple types of metal layers 26. In Figure 11, the horizontal axis represents wavelength λ (μm), and the vertical axis represents the absorption rate A. In Figure 11, an absorption rate of 100% A is represented as "1", and an absorption rate of 0% A is represented as "0".

[0083] Figure 11 shows the first to eighth curves from top to bottom. The first to sixth curves show the absorption rate of incident light in the photodetector 10 when the metal layer 26 contains TiN. In the first to second curves, the photodetector 10 has a needle-like structure similar to that in Figure 8. In the third to sixth curves, the photodetector 10 has a square-hole structure similar to that in Figure 4. The seventh curve shows the absorption rate of incident light in the photodetector 10 when the metal layer 26 contains Cu. The thicknesses of the metal layer 26 in the first to seventh curves are 7.5nmt, 4.0nmt, 7.5nmt, 15nmt, 30nmt, 4.0nmt, and 15nmt, respectively. The eighth curve shows the absorption rate of incident light in a photodetector without a metal layer 26, where the microstructure of the semiconductor layer 25 is a square-hole structure similar to that in Figure 4, as a comparative example.

[0084] In the wavelength range shown in Figure 11 (1.3 μm to 1.7 μm), the needle-like structure in Figure 8 has a higher light absorption rate than the tetragonal pore structure.

[0085] In a photodetector 10 having a needle-like structure, in which the metal layer 26 contains TiN and the thickness of the metal layer 26 is 7.5 nmt (i.e., the photodetector 10 of the first curve), for example, it has a light absorption rate of 90% or more in the wavelength range of 2.0 μm or less.

[0086] Figure 12A shows the plasmon resonance in the microstructure of pixel 20 in Figure 4. Figure 12B is a magnified view of Figure 12A. Figure 13A shows the plasmon resonance in the microstructure of pixel 20a in Figure 8. Figure 13B is a magnified view of Figure 13A.

[0087] In Figures 12A, 12B, 13A, and 13B, the horizontal axis represents the horizontal position of the semiconductor layer 25, and the vertical axis represents the depth position of the semiconductor layer 25. The grayscale indicates the strength of the plasmon resonance.

[0088] The darker areas in the grayscale represent regions with strong plasmon resonance. Figures 12B and 13B are enlarged views of areas B1 and B2 in Figures 12A and 13A, respectively. Note that the pixels 20 in Figures 12A and 12B have periodically arranged square holes (i.e., pores 27) as part of their fine structure.

[0089] Comparing Figure 12B and Figure 13B, pixel 20a in Figure 13B exhibits remarkably strong plasmon resonance in areas B3 and B4 surrounding the needle-like structure 31 (e.g., the tapered side portion).

[0090] Figure 14 is a bird's-eye view of a pixel 20b according to a first modification of a second embodiment of the present disclosure. While the pixel 20a in Figure 10 has a plurality of convex portions (specifically, needle-like structures 31) having tapered sides, the pixel 20b in Figure 14 has a plurality of concave portions having tapered sides. Specifically, the pixel 20b in Figure 14 has needle-like structures 31a in the holes. Any cone-shaped hole can be applied as the needle-like structure 31a. The pixel 20b may also have a configuration having a plurality of frustoconical holes. In this specification, the microstructure of the pixel 20b is also referred to as an inverted needle-like structure. Furthermore, the microstructure of the pixel 20b may include concave portions in some parts and convex portions similar to those of the pixel 20a in other parts.

[0091] In the pixel 20b of Figure 14, the surface area of ​​the metal layer 26 can be increased to the same extent as in the pixel 20a of Figure 10. In other words, the pixel 20b of Figure 14 can further improve the photocurrent detection efficiency, similar to the pixel 20a of Figure 10.

[0092] Figure 15 is a cross-sectional view of a pixel 20c according to a second modification of a second embodiment of the present disclosure. The pixel 20c in Figure 15 has a plurality of pyramidal structures 31b instead of a plurality of needle-like structures 31. The pyramidal structures 31b differ from the needle-like structures 31 in that the base angle (angle of inclination of the tapered side surface) Rb is less than 60 degrees. The base angle Rb is, for example, 50 degrees or more (for example, 57 to 58 degrees, etc.).

[0093] The pixel 20c in Figure 15 can have a larger surface area of ​​the metal layer 26 than the pixel 20 in Figure 4. Also, the pyramidal structure 31b in Figure 15 can be formed more easily than the needle-like structure 31 in Figure 8. Therefore, the manufacturing process for the pixel 20c in Figure 15 can be simplified compared to the pixel 20a in Figure 8, and manufacturing costs can be reduced.

[0094] Pixel 20c may have a configuration having a convex portion of the pyramidal structure 31b, similar to pixel 20a in Figure 10. Alternatively, it may have a configuration having a concave portion of the pyramidal structure 31b, similar to pixel 20b in Figure 14. Pixel 20c may include both the convex and concave portions of the pyramidal structure 31b, or it may include a needle-shaped structure 31 or an inverted needle-shaped structure 31a in part.

[0095] Thus, the photodetector 10 according to the second embodiment of this disclosure has a plurality of needle-like structures 31 as a microstructure. This allows the surface area of ​​the metal layer 26 to be increased. According to experimental results, the needle-like structures can achieve a remarkably high light absorption rate (for example, 90% or more for wavelengths of 1.3 μm to 1.7 μm), and the efficiency of plasmon resonance can be significantly improved. Therefore, the photodetector 10 according to the second embodiment of this disclosure can further improve the photocurrent detection efficiency.

[0096] Furthermore, the photodetector 10 according to the second embodiment of this disclosure may have a configuration having a plurality of pyramidal structures 31b as its microstructure. This configuration is simpler than the configuration having a plurality of needle-shaped structures 31 and can improve the photocurrent detection efficiency.

[0097] (Third embodiment) In the first and second embodiments, examples are described in which the semiconductor layer 25 has silicon implanted with a first conductivity type, specifically n-type impurities. The semiconductor layer 25 may also have a second conductivity type, specifically p-type impurities, implanted.

[0098] Figure 16 is a cross-sectional view of a pixel 20d according to a third embodiment of the present disclosure. In the pixel 20d, holes h generated by plasmon resonance in the metal layer 26 can be read out from the photoelectric conversion region PD.

[0099] Furthermore, in the semiconductor layer 25 shown in Figure 16, an impurity distribution region can be formed in which the impurity concentration decreases from the A2 side to the A1 side. As a result, holes h that have moved from the metal layer 26 to the semiconductor layer 25 can generate a drift current directed toward the photoelectric conversion region PD.

[0100] For example, TiN can be used for the metal layer 26 in Figure 16. Figure 17 shows the IV characteristics of a pixel 20d using a metal layer 26 containing TiN and a semiconductor layer 25 containing p-type Si. In Figure 17, the horizontal axis represents voltage (V) and the vertical axis represents current (A). In Figure 17, the curve w1 representing the photocurrent is shown as a solid line, and the curve w2 representing the dark current is shown as a dashed line.

[0101] A metal layer 26 containing TiN and a semiconductor layer 25 containing p-type Si can be formed to obtain, for example, a Schottky barrier φb of 0.7 eV and a contact series resistance of 822 Ω.

[0102] As shown in Figure 17, in a pixel 20d using a metal layer 26 containing TiN and a semiconductor layer 25 containing p-type Si, the dark current can be suppressed to the order of 1 / 100th of the photocurrent.

[0103] The semiconductor layer 25 and metal layer 26 according to the third embodiment of this disclosure can be applied to either of the pixels 20 to 20c of the first and second embodiments.

[0104] (Fourth embodiment) The first to third embodiments show examples of forming a Schottky barrier at the interface between the metal layer 26 and the semiconductor layer 25. Other potential barriers may be formed between the metal layer 26 and the semiconductor layer 25. Figure 18 illustrates a potential barrier in a photodetector 10b according to a fourth embodiment of the present disclosure. The photodetector 10b in Figure 18 has a dielectric layer 41 disposed between the metal layer 26 and the semiconductor layer 25.

[0105] The dielectric layer 41 can form a potential barrier (potential barrier region) φi between itself and the metal layer 26 that is larger than the Schottky barrier φb (i.e., φi > φb). By forming the potential barrier φi, the potential distribution of the metal layer 26 and the semiconductor layer 25 can be adjusted more flexibly. By controlling the potential barrier φi, the potential distribution can be optimized, achieving both suppression of dark current and improvement of quantum efficiency.

[0106] In the photodetector 10b shown in Figure 18, a potential barrier φi may be formed by a material other than the dielectric layer 41. For example, a wide-gap insulating film may be placed between the metal layer 26 and the semiconductor layer 25 instead of the dielectric layer 41. Alternatively, a dielectric multilayer film, or a multilayer film of a semiconductor film and a metal film, may be placed between the metal layer 26 and the semiconductor layer 25.

[0107] In the photodetector 10b shown in Figure 18, for example, by adjusting the potential barrier φi to approximately 0.7 eV, a high photocurrent can be obtained while suppressing the dark current, as shown in Figure 17.

[0108] (Fifth embodiment) Figure 19 is a cross-sectional view of a pixel 20e according to a fifth embodiment of this disclosure. The pixel 20e in Figure 19 differs from the pixel 20a in Figure 8 in that it has an optical element 51 disposed on the A1 side of the semiconductor layer 25. The optical element 51 may also be applied to the pixel 20 in Figure 4.

[0109] The optical element 51 is, for example, a metalens and controls the direction of incident light propagation. The optical element 51 has a microstructure formed from a plurality of optical members 52. The optical element 51 deflects obliquely incident light Lc, which is incident at an angle to the horizontal plane on the A1 side, into perpendicularly incident light Ld, which is perpendicular to the horizontal plane. As a result, the pixel 20e can absorb incident light more efficiently.

[0110] A joint 53 having a resin film or insulating film may be placed between the optical element 51 and the metal layer 26. The optical member 52 may also have a resin film or insulating film. The optical member 52 may be formed of a different material from the joint 53, or it may be formed of the same material as the joint 53, or it may be formed integrally with the joint 53.

[0111] When the pixel 20e receives incident light from the A2 side (for example, incident light Lb in Figure 4), the optical element 51 may be placed on the A2 side of the semiconductor layer 25.

[0112] The microstructure of the optical element 51 (hereinafter also referred to as the metalens structure) is preferably adjusted to match the position of the pixel 20e. Specifically, the asymmetry of the metalens structure is increased as the image height increases from the center of the image plane of the pixel array 11, that is, as it moves away from the optical axis of the optical element 51. By adjusting the metalens structure for each image height, the shading characteristics (image height-dependent characteristics) can be improved.

[0113] Figure 20A is a first diagram showing a pixel array 11 according to a fifth embodiment of the present disclosure. The pixels 20e in Figure 20A have different optical elements 51a for each image height. The optical elements 51a in Figure 20A are, for example, circular metalens. In addition, the pixels 20e in the center of the pixel array 11 have substantially symmetrical optical elements 51b.

[0114] Figure 20B is a second diagram showing a pixel array 11 according to a fifth embodiment of the present disclosure. The optical element 51c in Figure 20B is, for example, a rectangular metalens. The pixels 20e in the center of the pixel array 11 have an optical element 51d that is substantially symmetrical.

[0115] Figures 19, 20A, and 20B illustrate the direction U away from the center of the image plane.

[0116] The shape of the optical element 51 is not limited to the examples in Figures 20A and 20B. For example, the optical element 51 may be a polygonal metalens. Also, in the examples in Figures 20A and 20B, the optical elements 51a to 51d include multiple line-shaped (e.g., annular) optical members 52, but are not limited to this, and the optical element 51 may also include pillar-shaped optical members 52 (for example, the optical members 52 may be arranged in a dot pattern in a plan view).

[0117] (Sixth embodiment) Figure 21 is a block diagram showing a solid-state imaging device 60 according to the sixth embodiment of this disclosure. The solid-state imaging device 60 in Figure 21 includes the photodetector 10 according to the first to fifth embodiments. The solid-state imaging device 60 includes an optical filter 61 and one or more optical lenses 62. At least a part of the electronic equipment 1 in Figure 1 may be applied to the solid-state imaging device 60. In this specification, the solid-state imaging device 60 may be referred to as a photodetector.

[0118] The optical filter 61, for example, cuts out visible light and near-infrared light and transmits SWIR light. This allows the solid-state imaging device 60 to generate image data based on SWIR light. The solid-state imaging device 60 can be applied to infrared cameras, biosensors such as blood glucose sensors, analytical sensors such as moisture sensors, or thermal sensors. The optical lens 62, for example, adjusts the focus to SWIR light.

[0119] The optical filter 61 in Figure 21 is positioned between the optical lens 62 and the light detection device 10, but the positioning of the optical filter 61 is not limited to this. The optical filter 61 may be positioned so as to sandwich the optical lens 62 between it and the light detection device 10, or it may be positioned between multiple optical lenses 62.

[0120] The solid-state imaging device 60 may have a cooling element. In other words, the solid-state imaging device 60 may be a cooled infrared sensor. This allows the solid-state imaging device 60 to reduce dark current due to thermal noise, enabling detection of MIR light or FIR light, etc. This makes it applicable to gas detection sensors or high-sensitivity thermal sensing sensors, etc.

[0121] (Examples of application) The technology relating to this disclosure can be applied to medical imaging systems. Medical imaging systems are medical systems that use imaging technology, such as endoscope systems and microscope systems.

[0122] [Endoscopy System] An example of an endoscopic system will be explained using Figures 22 and 23. Figure 22 is a diagram showing an example of the schematic configuration of an endoscopic system 5000 to which the technology relating to this disclosure can be applied. Figure 23 is a diagram showing an example of the configuration of an endoscope 5001 and a CCU (Camera Control Unit) 5039. Figure 22 illustrates a surgeon (e.g., a physician) 5067, who is a participant in the surgery, performing surgery on a patient 5071 on a patient bed 5069 using the endoscopic system 5000. As shown in Figure 22, the endoscopic system 5000 consists of an endoscope 5001, which is a medical imaging device, a CCU 5039, a light source device 5043, a recording device 5053, an output device 5055, and a support device 5027 that supports the endoscope 5001.

[0123] In endoscopic surgery, an insertion aid called a trocca 5025 is inserted into the patient 5071. Then, via the trocca 5025, the scope 5003 connected to the endoscope 5001 and surgical instruments 5021 are inserted into the patient 5071's body. Surgical instruments 5021 include, for example, energy devices such as electrosurgical units or forceps.

[0124] Surgical images, which are medical images of the inside of patient 5071 taken by endoscope 5001, are displayed on display device 5041. The surgeon 5067 performs the procedure on the surgical target using surgical instruments 5021 while viewing the surgical images displayed on display device 5041. Note that the medical images are not limited to surgical images; they may also be diagnostic images taken during diagnosis.

[0125] [Endoscopy] The endoscope 5001 is an imaging unit that images the inside of the patient 5071's body. For example, as shown in Figure 23, it is a camera 5005 that includes a focusing optical system 50051 that focuses incident light, a zoom optical system 50052 that changes the focal length of the imaging unit to enable optical zoom, a focusing optical system 50053 that changes the focal length of the imaging unit to enable focus adjustment, and a light-receiving element 50054. The endoscope 5001 generates a pixel signal by focusing light onto the light-receiving element 50054 via the connected scope 5003 and outputs the pixel signal to the CCU 5039 through a transmission system. The scope 5003 is an insertion unit that has an objective lens at its tip and guides light from the connected light source device 5043 into the patient 5071's body. The scope 5003 is, for example, a rigid scope in the case of a rigid endoscope, or a flexible scope in the case of a flexible endoscope. The scope 5003 may be a straight-viewing endoscope or an oblique-viewing endoscope. Furthermore, the pixel signal can be any signal based on the signal output from the pixel, such as a RAW signal or an image signal. Alternatively, the transmission system connecting the endoscope 5001 and the CCU 5039 may be equipped with memory to store parameters related to the endoscope 5001 and the CCU 5039. The memory may be located, for example, at the connection point of the transmission system or on the cable. For example, the factory settings of the endoscope 5001 and parameters that change during power-up may be stored in the transmission system's memory, and the operation of the endoscope may be modified based on the parameters read from the memory. The endoscope and transmission system may also be referred to as a set. The photodetector 50054 is a sensor that converts received light into a pixel signal, and is, for example, a CMOS (Complementary Metal Oxide Semiconductor) type image sensor. Preferably, the photodetector 50054 is a color image sensor with a Bayer array. Furthermore, the light-receiving element 50054 is preferably an image sensor having a number of pixels corresponding to a resolution of, for example, 4K (3840 horizontal pixels × 2160 vertical pixels), 8K (7680 horizontal pixels × 4320 vertical pixels), or square 4K (3840 or more horizontal pixels × 3840 or more vertical pixels). The light-receiving element 50054 may be a single sensor chip or multiple sensor chips.For example, a prism may be provided to separate the incident light into predetermined wavelength bands, and each wavelength band may be imaged by a different photodetector. Alternatively, multiple photodetectors may be provided for stereoscopic viewing. The photodetector 50054 may be a sensor containing an image processing circuit within its chip structure, or it may be a Time of Flight (ToF) sensor. The transmission system may be, for example, an optical fiber cable or wireless transmission. Wireless transmission is only required if the pixel signals generated by the endoscope 5001 can be transmitted. For example, the endoscope 5001 and the CCU 5039 may be wirelessly connected, or the endoscope 5001 and the CCU 5039 may be connected via a base station in the operating room. In this case, the endoscope 5001 may simultaneously transmit not only the pixel signals but also information related to the pixel signals (e.g., pixel signal processing priority and synchronization signals). The endoscope may integrate the scope and camera, or a photodetector may be provided at the tip of the scope.

[0126] [CCU (Camera Control Unit)] The CCU5039 is a control device that comprehensively controls the connected endoscope 5001 and light source device 5043. For example, as shown in Figure 23, it is an information processing device having an FPGA 50391, CPU 50392, RAM 50393, ROM 50394, GPU 50395, and I / F 50396. The CCU5039 may also comprehensively control the connected display device 5041, recording device 5053, and output device 5055. For example, the CCU5039 controls the irradiation timing, irradiation intensity, and type of light source of the light source device 5043. The CCU5039 also performs image processing such as development processing (e.g., demosaicing) and correction processing on the pixel signals output from the endoscope 5001, and outputs the processed pixel signals (e.g., images) to external devices such as the display device 5041. The CCU5039 also transmits control signals to the endoscope 5001 to control its operation. The control signal is, for example, information regarding imaging conditions such as the magnification and focal length of the imaging unit. The CCU 5039 may also have an image downconversion function and be configured to simultaneously output high-resolution (e.g., 4K) images to the display device 5041 and low-resolution (e.g., HD) images to the recording device 5053.

[0127] Furthermore, the CCU5039 may be connected to external devices (e.g., recording devices, display devices, output devices, support devices) via an IP converter that converts signals to a predetermined communication protocol (e.g., IP (Internet Protocol)). The connection between the IP converter and the external devices may consist of a wired network, or some or all of the network may be constructed as a wireless network. For example, the IP converter on the CCU5039 side may have a wireless communication function and transmit the received video to an IP switcher or output-side IP converter via a wireless communication network such as a fifth-generation mobile communication system (5G) or a sixth-generation mobile communication system (6G).

[0128] [Light source device] The light source device 5043 is a device capable of irradiating light in a predetermined wavelength band, and includes, for example, a plurality of light sources and a light source optical system that guides the light from the plurality of light sources. The light sources are, for example, xenon lamps, LED light sources, and LD light sources. The light source device 5043 has, for example, LED light sources corresponding to each of the three primary colors R, G, and B, and emits white light by controlling the output intensity and output timing of each light source. In addition, the light source device 5043 may have a light source capable of irradiating special light used for special light observation, separate from the light source that irradiates normal light used for normal light observation. Special light is light in a predetermined wavelength band different from the normal light used for normal light observation, and includes, for example, near-infrared light (light with a wavelength of 760 nm or more), infrared light, blue light, and ultraviolet light. Normal light is, for example, white light or green light. In narrow-band light observation, a type of special light observation, by alternately irradiating with blue light and green light, it is possible to take high-contrast images of predetermined tissues such as blood vessels on the surface of mucous membranes by utilizing the wavelength dependence of light absorption in body tissues. Furthermore, in fluorescence observation, a type of special light observation, excitation light is irradiated to excite a drug injected into body tissue, and a fluorescence image is obtained by receiving the fluorescence emitted by the body tissue or the labeling drug. This makes it easier for the operator to visualize body tissues and other areas that are difficult to see with normal light. For example, in fluorescence observation using infrared light, infrared light having an excitation wavelength band is irradiated onto a drug such as indocyanine green (ICG) injected into body tissue, and the structure of the body tissue and the affected area can be made easier to visualize by receiving the fluorescence of the drug. In addition, in fluorescence observation, a drug that is excited by special light in the blue wavelength band and emits fluorescence in the red wavelength band (e.g., 5-ALA) may be used. The type of irradiation light of the light source device 5043 is set by the control of the CCU 5039. The CCU 5039 may have a mode in which normal light observation and special light observation are performed alternately by controlling the light source device 5043 and the endoscope 5001. In this case, it is preferable that information based on the pixel signal obtained in special light observation is superimposed on the pixel signal obtained in normal light observation. Furthermore, special light observation may include infrared light observation, which involves irradiating with infrared light to view areas deeper than the organ surface, or multispectral observation utilizing hyperspectral spectroscopy. In addition, photodynamic therapy may be combined with this method.

[0129] [Recording device] The recording device 5053 is a device that records pixel signals (e.g., images) acquired from the CCU 5039, and is, for example, a recorder. The recording device 5053 records the images acquired from the CCU 5039 onto an HDD, SSD, or optical disc. The recording device 5053 may be connected to the hospital network and made accessible from equipment outside the operating room. The recording device 5053 may also have an image down-conversion or up-conversion function.

[0130] [Display device] The display device 5041 is a device capable of displaying images, such as a display monitor. The display device 5041 displays a display image based on pixel signals acquired from the CCU 5039. The display device 5041 may also function as an input device that enables eye-tracking, voice recognition, and gesture-based instruction input by equipping it with a camera and microphone.

[0131] [Output device] The output device 5055 is a device that outputs information acquired from the CCU 5039, and is, for example, a printer. The output device 5055 prints a print image on paper based on the pixel signals acquired from the CCU 5039.

[0132] [Support device] The support device 5027 is a multi-joint arm comprising a base portion 5029 having an arm control device 5045, an arm portion 5031 extending from the base portion 5029, and a holding portion 5032 attached to the tip of the arm portion 5031. The arm control device 5045 is composed of a processor such as a CPU and controls the driving of the arm portion 5031 by operating according to a predetermined program. The support device 5027 controls parameters such as the length of each link 5035 constituting the arm portion 5031 and the rotation angle and torque of each joint 5033 by the arm control device 5045, thereby controlling, for example, the position and orientation of the endoscope 5001 held by the holding portion 5032. This allows the endoscope 5001 to be changed to a desired position or orientation, enabling the scope 5003 to be inserted into the patient 5071 and changing the observation area inside the body. The support device 5027 functions as an endoscope support arm that supports the endoscope 5001 during surgery. This allows the support device 5027 to act as a substitute for the scopist, who is an assistant holding the endoscope 5001. The support device 5027 may also be a device that supports the microscope device 5301, which will be described later, and can also be called a medical support arm. The support device 5027 may be controlled autonomously by the arm control device 5045, or it may be controlled by the arm control device 5045 based on user input. For example, the control method may be a master-slave system in which the support device 5027, acting as a slave device (replica device) that is a patient cart, is controlled based on the movement of the master device (primary device), which is the operator console at the user's location. Furthermore, the support device 5027 may be controlled remotely from outside the operating room.

[0133] The above describes an example of an endoscope system 5000 to which the technology described herein may be applied. For example, the technology described herein may be applied to a microscope system.

[0134] [Microscope System] Figure 24 shows an example of a schematic configuration of a microsurgical system to which the technology described herein may be applied. In the following description, components similar to those in the endoscopic system 5000 are denoted by the same reference numerals, and redundant explanations are omitted.

[0135] Figure 24 schematically shows a surgeon 5067 performing surgery on patient 5071 on a patient bed 5069 using a microsurgical system 5300. For simplicity, Figure 24 omits the cart 5037 from the configuration of the microsurgical system 5300, and the microscope device 5301, which replaces the endoscope 5001, is shown in a simplified form. However, in this description, the microscope device 5301 may refer to the microscope unit 5303 located at the tip of the link 5035, or it may refer to the entire configuration including the microscope unit 5303 and the support device 5027.

[0136] As shown in Figure 24, during surgery, the image of the surgical area captured by the microscope device 5301 is displayed on a display device 5041 installed in the operating room using the microsurgery system 5300. The display device 5041 is positioned opposite the surgeon 5067, and the surgeon 5067 observes the surgical area through the image displayed on the display device 5041 and performs various procedures on the surgical area, such as excising the affected area. The microsurgery system is used, for example, in ophthalmic surgery and neurosurgery.

[0137] Examples of endoscopic systems 5000 and microsurgical systems 5300 to which the technology relating to this disclosure may be applied have been described above. However, the systems to which the technology relating to this disclosure may be applied are not limited to these examples. For example, the support device 5027 may support other observation devices or surgical instruments at its tip in place of the endoscope 5001 or the microscope unit 5303. Such other observation devices may include, for example, forceps, insufflation tubes for pneumoperitoneum, or energy treatment instruments for tissue incision or blood vessel sealing by cauterization. By supporting these observation devices and surgical instruments with the support device, their position can be fixed more stably than when medical staff support them manually, and the burden on medical staff can be reduced. The technology relating to this disclosure may also be applied to support devices that support components other than the microscope unit.

[0138] The technology relating to this disclosure can be suitably applied to the endoscope 5001 or the microscope unit 5303 among the configurations described above. Specifically, by applying the light detection device 10 of Figure 2 to the light receiving element 50054, a clearer image of the surgical site can be obtained, making it possible to perform surgery more safely and reliably.

[0139] Furthermore, this technology can take the following configuration. (1) A semiconductor layer having a roughened main surface and having a charge potential gradient in the direction normal to the main surface, The device comprises a metal layer arranged along one main surface, which moves charges generated by plasmon resonance in response to the amount of incident light, having energy greater than the potential barrier of the one main surface, to the semiconductor layer. Light detection device. (2) The semiconductor layer is provided with a transfer circuit located on the side opposite to the one main surface, The semiconductor layer has a floating diffusion region that holds the charge transferred from the metal layer to the semiconductor layer. The transfer circuit transfers the charge moved from the metal layer to the semiconductor layer to the floating diffusion region. (1) The light detection device described above. (3) The semiconductor layer has a photoelectric conversion region, The transfer circuit transfers the charge moved from the metal layer to the semiconductor layer and the charge photoelectrically converted in the photoelectric conversion region to the floating diffusion region. (2) The light detection device described above. (4) The semiconductor layer has an impurity distribution region from the main surface to the transfer circuit in which the concentration of impurity ions changes, The charge transferred from the metal layer to the semiconductor layer moves along the internal electric field of the impurity distribution region. (2) or (3) the light detection device described above. (5) Of the impurity distribution region, the region on the one main surface side has a lower concentration of impurity ions than the region on the transfer circuit side. (4) The light detection device described above. (6) The metal layer and the semiconductor layer are connected by a Schottky junction. A light detection device as described in any one of (1) to (5). (7) A potential barrier region disposed between the metal layer and the semiconductor layer, having a potential barrier higher than that of the semiconductor layer, A light detection device as described in any one of (1) to (5). (8) The potential barrier region has a dielectric layer, (7) The light detection device described above. (9) The semiconductor layer has at least one of a plurality of protrusions or a plurality of recesses arranged in two dimensions on the one main surface side, A light detection device as described in any one of items (1) to (8). (10) The plurality of protrusions or the plurality of recesses have tapered sides, (9) The light detection device described above. (11) The inclination angle of the side surface is 60 degrees or more. (10) The light detection device described above. (12) The inclination angle of the side surface is less than 60 degrees. (10) The light detection device described above. (13) comprising a plurality of pixels, each including the semiconductor layer and the metal layer, A light detection device as described in any one of (1) to (12). (14) further comprising a pixel isolation region located between two adjacent pixels, (13) The light detection device described above. (15) Each of the plurality of pixels is provided with an optical element that controls the direction of incident light, which is arranged on the side of the one main surface of the semiconductor layer or on the side of the surface opposite to the one main surface. The light detection device described in (13) or (14). (16) The optical element has greater asymmetry as it moves away from the optical axis of the optical element. (15) Light detection device as described. (17) The metal layer comprises at least one of TiN, Cu, Au, Ag, AuAg, or Al. A light detection device as described in any one of items (1) to (13). (18) When the charge that moves from the semiconductor layer to the metal layer is an electron, the semiconductor layer contains n-type impurity ions, If the charge moving from the semiconductor layer to the metal layer is a hole, the semiconductor layer contains p-type impurity ions. A light detection device as described in any one of items (1) to (13). (19) The metal layer is provided with an optical filter that shields it from visible light and near-infrared light and transmits SWIR (Short-wave infrared radiation) light. A light detection device as described in any one of items (1) through (18). (20) A light detection device according to any one of items (1) to (19) that outputs image data, The system comprises a signal processing unit that performs signal processing on the aforementioned image data, electronic equipment.

[0140] The aspects of this disclosure are not limited to the individual embodiments described above, but include various modifications that a person skilled in the art could conceive, and the effects of this disclosure are not limited to those described above. In other words, various additions, modifications, and partial deletions are possible, as long as they do not depart from the conceptual idea and spirit of this disclosure derived from the claims and their equivalents. [Explanation of Symbols]

[0141] 1 Electronic device, 2 Imaging lens, 3 Recording unit, 4 Control unit, 5 Transmission line, 6 Control line, 7 Signal processing unit, 10, 10a, 10b Photodetector, 11 Pixel array unit, 12 Noise canceller, 13 Switch, 14 Output circuit, 20, 20a, 20b, 20c, 20d, 20e Pixel, 21 Photoelectric conversion element, 22 Amplifier, 25 Semiconductor layer, 26 Metal layer, 27 Hole, 28 Pixel isolation region, 31, 31a Needle-shaped structure, 31b Pyramid structure, 41 Dielectric layer, 51, 51a, 51b, 51c, 51d Optical element, 52 Optical component, 53 Bonding part, 60 Solid-state imaging device, 61 Optical filter, 62 Optical lens

Claims

1. A semiconductor layer having a roughened main surface and a charge potential gradient in the direction normal to the main surface, The device comprises a metal layer arranged along one main surface, which moves charges generated by plasmon resonance in response to the amount of incident light, having energy greater than the potential barrier of the one main surface, to the semiconductor layer. Light detection device.

2. The semiconductor layer comprises a transfer circuit located on the side opposite to the main surface of the semiconductor layer, The semiconductor layer has a floating diffusion region that holds the charge transferred from the metal layer to the semiconductor layer. The transfer circuit transfers the charge moved from the metal layer to the semiconductor layer to the floating diffusion region. The light detection device according to claim 1.

3. The semiconductor layer has a photoelectric conversion region, The transfer circuit transfers the charge moved from the metal layer to the semiconductor layer and the charge photoelectrically converted in the photoelectric conversion region to the floating diffusion region. The light detection device according to claim 2.

4. The semiconductor layer has an impurity distribution region from the main surface to the transfer circuit in which the concentration of impurity ions changes. The charge transferred from the metal layer to the semiconductor layer moves along the internal electric field of the impurity distribution region. The light detection device according to claim 2.

5. Of the impurity distribution region, the region on the one main surface side has a lower concentration of impurity ions than the region on the transfer circuit side. The light detection device according to claim 4.

6. The metal layer and the semiconductor layer are connected by a Schottky junction. The light detection device according to claim 1.

7. The metal layer is disposed between the semiconductor layer and the potential barrier region having a higher potential barrier than the semiconductor layer, The light detection device according to claim 1.

8. The aforementioned potential barrier region has a dielectric layer, The light detection device according to claim 7.

9. The semiconductor layer has at least one of a plurality of protrusions or a plurality of recesses arranged two-dimensionally on one main surface side. The light detection device according to claim 1.

10. The plurality of protrusions or the plurality of recesses have tapered sides, The light detection device according to claim 9.

11. The inclination angle of the aforementioned side surface is 60 degrees or more. The light detection device according to claim 10.

12. The inclination angle of the aforementioned side surface is less than 60 degrees. The light detection device according to claim 10.

13. A plurality of pixels comprising the semiconductor layer and the metal layer, respectively, The light detection device according to claim 1.

14. The present invention further comprises a pixel isolation region located between two adjacent pixels. The light detection device according to claim 13.

15. Each of the plurality of pixels is provided with an optical element that controls the direction of incident light, and is arranged on the side of the semiconductor layer facing the main surface or the side facing the main surface. The light detection device according to claim 13.

16. The optical element has greater asymmetry as it moves away from the optical axis of the optical element. A light detection device according to claim 15.

17. The metal layer comprises at least one of TiN, Cu, Au, Ag, AuAg, or Al. The light detection device according to claim 1.

18. When the charge moving from the semiconductor layer to the metal layer is an electron, the semiconductor layer contains n-type impurity ions. If the charge moving from the semiconductor layer to the metal layer is a hole, the semiconductor layer contains p-type impurity ions. The light detection device according to claim 1.

19. The aforementioned metal layer is shielded from visible light and near-infrared light, and is equipped with an optical filter that transmits SWIR (Short-wave infrared radiation) light. The light detection device according to claim 1.

20. A light detection device according to claim 1 that outputs image data, The system comprises a signal processing unit that performs signal processing on the aforementioned image data, electronic equipment.

Images