Light receiving elements and electronic devices

Abstract

The objective of this invention is to provide a light-receiving element with good performance. One embodiment of the light-receiving element disclosed herein comprises: a metal oxide film having a maximum extinction coefficient of 0.1 or more in the wavelength range of 200 nm to 380 nm; and a light-receiving portion that receives ultraviolet light transmitted through the aforementioned metal oxide film.

Description

Technical Field

[0001] This disclosure relates to a light-receiving element and an electronic device. Prior Technology

[0002] The industry has proposed a photoelectric conversion element having an anti-reflective film composed of a silicon oxide film and a silicon nitride film having an extinction coefficient k of less than 0.01 in the wavelength region of 200 nm to 380 nm (Patent Document 1). [Previous Technical Documents] [Patent Literature]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2017-92054 Summary of the Invention

[0004] [The problem the invention aims to solve]

[0005] We seek to improve the performance of components that receive light in the ultraviolet region.

[0006] The goal is to provide a light-receiving element with good performance.

[0007] One embodiment of the present disclosure includes a light-receiving element comprising: a metal oxide film having a maximum extinction coefficient of 0.1 or more in the wavelength range of 200 nm to 380 nm; and a light-receiving portion that receives ultraviolet light transmitted through the metal oxide film. An electronic device according to one embodiment of this disclosure includes a light-receiving element, which comprises: a metal oxide film and a light-receiving portion for receiving ultraviolet light transmitted through the metal oxide film. The maximum extinction coefficient of the metal oxide film in the wavelength range of 200 nm to 380 nm is 0.1 or more. Simple Explanation of the Diagram

[0008] Figure 1 is a block diagram showing an example of the overall structure of the camera device according to the first embodiment of this disclosure. Figure 2 is a diagram showing an example of the pixel portion of the camera device according to the first embodiment of this disclosure. Figure 3 is a cross-sectional view showing an example of the camera device according to the first embodiment of this disclosure. Figure 4 shows one example of the results of an ultraviolet irradiation experiment. Figure 5 is a diagram showing an example of the extinction coefficient of the metal oxide film of the first embodiment of this disclosure. Figure 6 is a diagram showing an example of the relationship between the thickness and transmittance of the metal oxide film in the first embodiment of the present disclosure. Figure 7 is a diagram showing an example of a method for manufacturing a camera device according to the first embodiment of this disclosure. Figure 8 is a diagram showing an example of a method for manufacturing a camera device according to the first embodiment of this disclosure. Figure 9 is a diagram showing an example of a method for manufacturing a camera device according to the first embodiment of this disclosure. Figure 10 is a diagram showing an example of a method for manufacturing a camera device according to the first embodiment of the present disclosure. Figure 11 is a diagram showing an example of a method for manufacturing a camera device according to the first embodiment of this disclosure. Figure 12 is a block diagram showing an example of the overall structure of the camera device according to the second embodiment of this disclosure. Figure 13 is a diagram showing an example of the pixel configuration of the camera device according to the second embodiment of this disclosure. Figure 14 is a cross-sectional view showing an example of the camera device according to the second embodiment of this disclosure. Figure 15 is a block diagram showing an example of the configuration of an electronic device with a camera. Implementation

[0009] The following describes in detail, with reference to the illustrations, an embodiment of this disclosure. Furthermore, the description is presented in the following order. 1. First Implementation Form 2. Second Implementation Form 3. Variation Examples 3-1. Variation Example 1 3-2. Variation Example 2 4. Application Examples

[0010] <1. First Implementation Form> Figure 1 is a block diagram showing an example of the overall configuration of an imaging device as an example of a light-receiving element in the first embodiment of this disclosure. The imaging device 1, as the light-receiving element, is an element that receives ultraviolet light and is sensitive to ultraviolet light. The imaging device (light-receiving element) 1 can be used as an ultraviolet sensor (UV sensor) for detecting ultraviolet light. The imaging device 1 is, for example, a CMOS (Complementary Metal Oxide Semiconductor) image sensor. The imaging device 1 can be used in electronic devices such as digital still cameras and video cameras.

[0011] In the imaging device 1, pixels P, each having a light-receiving unit (photoelectric conversion unit), are arranged in a matrix. As shown in FIG. 2, the imaging device 1 has a pixel section 100, consisting of a matrix of multiple pixels P arranged in two dimensions, serving as the imaging area. Furthermore, as shown in FIG. 2, the incident direction of light from the subject is defined as the Z-axis direction, the left-right direction of the paper plane orthogonal to the Z-axis direction is defined as the X-axis direction, and the up-down direction of the paper plane orthogonal to both the Z-axis and X-axis directions is defined as the Y-axis direction. In subsequent figures, the direction is sometimes described based on the direction of the arrow in FIG. 2.

[0012] [Brief Composition of the Camera Device] The imaging device 1 captures incident light (image light) from the subject via an optical lens system (not shown). The imaging device 1 captures an image of the subject. The imaging device 1 converts the amount of incident light imaged on the imaging surface into an electrical signal in pixels and outputs it as a pixel signal. The imaging device 1 has, for example, a vertical drive circuit 111, a horizontal signal processing circuit 113, a horizontal drive circuit 114, an output circuit 115, a control circuit 116, and input / output terminals 117 in the peripheral area of ​​the pixel unit 100.

[0013] In the pixel unit 100, a plurality of pixels P are arranged in a matrix-like two-dimensional configuration. The pixel unit 100 includes a pixel column consisting of a plurality of pixels P arranged in the horizontal direction (horizontal direction of the paper) and a pixel row consisting of a plurality of pixels P arranged in the vertical direction (vertical direction of the paper). The pixel unit 100 may have: an effective pixel area for reading out a signal based on a signal charge generated by photoelectric conversion of light received from a subject; and a black reference pixel area for outputting an optical black as a reference for black levels. The black reference pixel area is disposed, for example, at the periphery of the effective pixel area.

[0014] In the pixel section 100, for example, a pixel drive line Lread (column select line and reset control line) is provided for each pixel column, and a vertical signal line Lsig is provided for each pixel row. The pixel drive line Lread transmits the drive signal used for reading signals from the pixel. One end of the pixel drive line Lread is connected to the output terminal corresponding to each pixel column of the vertical drive circuit 111.

[0015] The vertical drive circuit 111 is composed of a shift register and an address decoder, etc. The vertical drive circuit 111 drives the pixel drive unit of each pixel P in the pixel unit 100 in column units, for example. The horizontal signal processing circuit 113 is composed of an amplifier and a horizontal selection switch for each vertical signal line Lsig, etc. The signal output from each pixel P of the pixel column selected for scanning by the vertical drive circuit 111 is supplied to the horizontal signal processing circuit 113 via the vertical signal line Lsig.

[0016] The horizontal drive circuit 114 is composed of a shift register and an address decoder, etc., and scans and sequentially drives each horizontal selection switch of the line signal processing circuit 113. Through the selection scan performed by the horizontal drive circuit 114, the signals of each pixel transmitted through the vertical signal lines Lsig are sequentially output to the horizontal signal line 121, and transmitted to the outside of the substrate (semiconductor substrate) 10 through the horizontal signal line 121.

[0017] The output circuit 115 processes and outputs the signals sequentially supplied to each of the self-signal processing circuits 113 via the horizontal signal line 121. The output circuit 115 may perform only buffering, or it may perform black level adjustment, horizontal unevenness correction, and various digital signal processing. Furthermore, the horizontal signal processing circuit 113 can perform noise removal and signal amplification based on the signal from the black reference pixel area.

[0018] The circuitry including the vertical drive circuit 111, the horizontal signal processing circuit 113, the horizontal drive circuit 114, the horizontal signal line 121, and the output circuit 115 can be formed on the substrate 10 or disposed on an external control IC. Alternatively, these circuitry portions can be formed on other substrates connected by cables or the like.

[0019] The control circuit 116 receives clock and instruction operation mode data from the external source of the substrate 10, and outputs data such as internal information of the camera device 1. The control circuit 116 has a timing generator that generates various timing signals, and performs drive control of peripheral circuits such as the vertical drive circuit 111, the horizontal signal processing circuit 113, and the horizontal drive circuit 114 based on the various timing signals generated by the timing generator.

[0020] The control circuit 116 generates clock signals and control signals, for example, based on the vertical synchronization signal, horizontal synchronization signal, and main clock, which serve as the reference for the operation of the vertical drive circuit 111, the horizontal signal processing circuit 113, and the horizontal drive circuit 114. The clock signals and control signals generated by the control circuit 116 are input to the vertical drive circuit 111, the horizontal signal processing circuit 113, and the horizontal drive circuit 114. The input / output terminals 117 are used for exchanging signals with external devices.

[0021] [Pixel Composition] Figure 3 shows an example of the cross-sectional configuration of the imaging device according to the first embodiment. The imaging device 1, for example, has a substrate 10, a light guide 20, and a multilayer wiring layer 90 laminated in the Z-axis direction. The substrate 10 is a semiconductor substrate 10 having opposing first surfaces 11S1 and second surfaces 11S2. The light guide 20 is provided on the first surface 11S1 side of the semiconductor substrate 10, and the multilayer wiring layer 90 is provided on the second surface 11S2 side of the semiconductor substrate 10. Alternatively, the light guide 20 can be provided on the side where light from the optical lens system is incident, and the multilayer wiring layer 90 is provided on the side opposite to the light incident side. The imaging device 1 is a so-called back-illuminated imaging device.

[0022] The semiconductor substrate 10 is, for example, made of a silicon substrate. The light-receiving portion of the pixel P is a photoelectric conversion portion 12 made of, for example, a photodiode (PD), and has a pn junction in a specific region of the semiconductor substrate 10. In the example shown in FIG3, the photoelectric conversion portion 12 is formed to cover the entire thickness direction of the semiconductor substrate 10, and is configured as a pn junction type photodiode formed by an n-type semiconductor region and p-type semiconductor regions facing both sides of the semiconductor substrate 10. In addition, the p-type semiconductor regions facing both sides of the semiconductor substrate 10 also serve as hole charge accumulation regions for suppressing dark current. Furthermore, the substrate 10 does not necessarily have to be a silicon substrate and can be made of other semiconductor materials.

[0023] The photoelectric conversion unit 12 of this embodiment is configured to have sensitivity in the wavelength range of ultraviolet light, which includes a wavelength range of 200 nm to 380 nm. The photoelectric conversion unit 12 can generate an electric charge by photoelectric conversion of incident ultraviolet light. A plurality of photoelectric conversion units 12 are disposed along the first surface 11S1 and the second surface 11S2 in the semiconductor substrate 10.

[0024] The multilayer wiring layer 90 is, for example, a configuration consisting of multiple wiring layers stacked together with interlayer insulating layers. Circuits (transmission transistors, reset transistors, amplification transistors, etc.) for reading pixel signals based on charges generated by the photoelectric conversion unit 12 are formed on the semiconductor substrate 10 and the multilayer wiring layer 90. Furthermore, the aforementioned vertical drive circuit 111, horizontal signal processing circuit 113, horizontal drive circuit 114, output circuit 115, control circuit 116, and input / output terminals 117 are, for example, formed on the semiconductor substrate 10 and the multilayer wiring layer 90.

[0025] Pixel P may include, for example, transmission transistors, reset transistors, selection transistors, and amplifier transistors, serving as pixel transistors. Alternatively, pixel P may not have a selection transistor. Each pixel, including the photoelectric conversion unit 12 and the pixel transistor, is separated by a separation section 15 formed from a p-type semiconductor region. The separation section 15 is disposed at the boundary of adjacent pixels P, separating the pixels P. The separation section 15 is disposed between adjacent photoelectric conversion units 12, and can also be considered a component separation region. Furthermore, in FIG3, one pixel transistor represents a plurality of pixel transistors, and is schematically shown using the gate electrode 91.

[0026] The plurality of wiring layers 90 are formed using materials such as aluminum (Al), copper (Cu), or tungsten (W). Alternatively, the wiring layers can be formed using polycrystalline silicon (Poly-Si). The interlayer insulating layer is formed, for example, a monolayer film containing one of silicon oxide (SiOx), silicon nitride (SiNx), and silicon oxynitride (SiOxNy), or a laminated film containing two or more of these materials.

[0027] The light guide portion 20 includes a lens portion 21 for focusing light, an insulating film 24, a metal oxide film 25, and a charge-fixing film 26, and guides the light incident from above in FIG. 3 toward the semiconductor substrate 10. The light guide portion 20 is deposited on the semiconductor substrate 10 in a thickness direction orthogonal to the first surface 11S1 of the semiconductor substrate 10.

[0028] Lens section 21, also known as an optical component of a crystal-borne lens, is disposed on insulating film 24. Light from the subject is incident through an optical lens system, such as a camera lens, in lens section 21. Lens section 21 is made of a material that allows ultraviolet light to pass through, guiding the incident light toward photoelectric conversion section 12. The height of lens section 21 in the Z-axis direction, that is, the thickness of lens section 21 in the Z-axis direction, is set to concentrate the light incident toward lens section 21 onto photoelectric conversion section 12.

[0029] In this embodiment, the lens portion 21 is made of silicon oxide. This allows incident ultraviolet light to pass through the lens portion 21 and focuses it towards the photoelectric conversion unit 12. The lens portion 21 can be formed using P-TEOS. In this case, the film deposition yield can be improved. Furthermore, the lens portion 21 can be constructed using a material containing silicon oxide, or other materials.

[0030] The insulating film 24 is an insulating layer disposed between the lens section 21 and the photoelectric conversion section 12. The insulating film 24 is, for example, composed of an oxide film such as silicon oxide. The insulating film 24 can be formed by P-TEOS. In addition, the insulating film 24 can be composed of a material containing silicon oxide, or other materials can be used.

[0031] A fixed charge film 26 is disposed between the insulating film 24 and the photoelectric conversion unit 12. The fixed charge film 26 is disposed, for example, on an oxide film (not shown) formed on the first surface 11S1 of the semiconductor substrate 10. The fixed charge film 26 is formed to cover the first surface 11S1 of the semiconductor substrate 10.

[0032] In the example shown in Figure 3, the fixed charge film 26 is configured to cover the portion of the semiconductor substrate 10 on the first surface 11S1 where the photoelectric conversion portion 12 is formed and the portion where the separation portion 15 is formed. The fixed charge film 26 is formed to have a specific thickness along the first surface 11S1 of the semiconductor substrate 10.

[0033] The fixed charge film 26 is, for example, a film with a negative fixed charge, formed using a high dielectric material. By forming the fixed charge film 26 with a negative fixed charge, an electric field is applied at the interface with the photoelectric conversion unit 12 by means of the negative fixed charge. By forming a positive charge (hole) accumulation region by the electric field, the generation of dark current in the interface of the semiconductor substrate 10 can be suppressed. The fixed charge film 26 is, for example, formed as an oxide containing at least one of elements such as hafnium (Hf), zirconium (Zr), aluminum (Al), tantalum (Ta), titanium (Ti), magnesium (Mg), yttrium (Y), and lanthanum (La).

[0034] As an example, the fixed charge film 26 is made of aluminum oxide (Al₂O₃). Aluminum oxide (Al₂O₃) films are suitable for ultraviolet sensors because they exhibit strong pinning and have a low extinction coefficient in the ultraviolet region. Alternatively, a film with a positive fixed charge can be provided as the fixed charge film 26.

[0035] As shown in FIG3, the camera device 1 has a light-shielding portion 31 on the insulating film 24. The light-shielding portion 31 is composed of a light-blocking component and is disposed at the boundary of adjacent pixels P. The light-shielding portion 31 is, for example, made of a metal material that blocks light, specifically tungsten or aluminum. In the example shown in FIG3, the light-shielding portion 31 is a light-shielding film disposed around the photoelectric conversion unit 12 to suppress light leakage to the surrounding pixels.

[0036] By forming a light-shielding portion 31 in the portion of the insulating film 24 corresponding to the pixel boundary, crosstalk between pixels can be suppressed. Furthermore, the light-shielding portion 31 can be made of any material that blocks light, but it is preferable to use a material with strong light-shielding properties that can be precisely processed using fine machining methods such as etching. In addition, a member 32 can be provided between the light-shielding portion 31 and the insulating film 24 to improve the adhesion between them. This member 32 can be made of a barrier metal such as titanium. The member 32 can also be called a bonding layer. Also, although not shown, trenches for separating pixels P can be formed, and an oxide film or a metal film can be embedded in the trenches.

[0037] The metal oxide film 25, such as tantalum oxide (Ta₂O₅), is disposed on the fixed charge film 26. The metal oxide film 25 is deposited on the fixed charge film 26 between, for example, the lens portion 21 and the photoelectric conversion portion 12. The photoelectric conversion portion 12 receives light transmitted through the lens portion 21 and the metal oxide film 25. The photoelectric conversion portion 12 generates a charge corresponding to the amount of light received by the ultraviolet light incident through the lens portion 21 and the metal oxide film 25.

[0038] Furthermore, in the example shown in Figure 3, the metal oxide film 25 is formed over almost the entire surface of the fixed charge film 26. However, the metal oxide film 25 may not necessarily be formed over almost the entire surface of the fixed charge film 26; for example, it may only be formed above the portion where the photoelectric conversion section 12 is formed. Both the metal oxide film 25 and the fixed charge film 26 can serve as anti-reflective films to reduce reflection.

[0039] The metal oxide film 25 can be composed of a single film or multiple films stacked together. For example, the metal oxide film 25 can be composed of tantalum oxide (Ta₂O₅) film, niobium oxide (Nb₂O₅) film, tungsten oxide (WO₃) film, or a stacked film of the like.

[0040] In this embodiment, the metal oxide film 25 is formed such that the maximum extinction coefficient in the wavelength range of 200 nm to 380 nm is 0.1 or higher. This ensures quantum efficiency (QE) for ultraviolet light in the wavelength range and suppresses performance degradation caused by ultraviolet irradiation. The imaging device 1 of this embodiment will be further described below in comparison with a comparative example.

[0041] The comparative example is the imaging device 1 in Figure 3 without the metal oxide film 25. The inventors have confirmed that the sensitivity to ultraviolet light (UV sensitivity) can be improved in the imaging device 1 without the metal oxide film 25. However, the results of ultraviolet irradiation experiments over a long period of time clearly show that in the comparative example, the increase in dark current and the decrease in UV sensitivity (hereinafter referred to as UV irradiation damage) are greater.

[0042] Furthermore, the inventors investigated the relationship between the extinction coefficient of the metal oxide film 25 and the magnitude of UV irradiation damage (the increase in dark current and the decrease in UV sensitivity). The results showed that UV irradiation damage could be suppressed by using a metal oxide film 25 with a maximum extinction coefficient of 0.1 or higher in the wavelength range of 200 nm to 380 nm. The reason for suppressing UV irradiation damage is believed to be that by using such a metal oxide film 25, ultraviolet radiation to the Si interface of the semiconductor substrate 10 is reduced, thereby suppressing the generation of interface energy levels.

[0043] Figure 4 shows one example of the results of an ultraviolet irradiation experiment. The wavelength of the irradiated ultraviolet light was 193 nm, and the radiation intensity was 1.0 mW / cm². The irradiation time was 1 hour, and the total radiation energy was 3.6 J / cm². Figure 4 shows the quantum efficiency and UV irradiation damage for the case without a tantalum oxide (Ta₂O₅) film and the case with a tantalum oxide (Ta₂O₅) film with a thickness of approximately 5 nm.

[0044] Without the tantalum oxide film, the quantum efficiency Qe is high, but the reduction in UV sensitivity increases significantly to 55%. Furthermore, the dark signal, corresponding to the dark current, also increases by 1500 times. On the other hand, with the tantalum oxide film, the quantum efficiency Qe decreases, but the reduction in UV sensitivity is suppressed to 15%. Furthermore, the dark signal is suppressed by an 80-fold increase. Thus, it can be seen that with the metal oxide film 25, a decrease in quantum efficiency Qe occurs, but the suppression effect of UV irradiation damage is high.

[0045] Figure 5 shows an example of the extinction coefficient of the metal oxide film 25 in the first embodiment. In Figure 5, the horizontal axis represents the wavelength, and the vertical axis represents the extinction coefficient k. The extinction coefficient is measured, for example, by a spectroradiometer. For the extinction coefficient below 250 nm, considering atmospheric absorption, it can be measured in a nitrogen-purified environment.

[0046] In Figure 5, the solid line represents the extinction coefficient of the tantalum oxide film (Ta₂O₅ film). The tantalum oxide film has an extinction coefficient of ≥0.1 in the wavelength range of 200 nm to 380 nm. Also in Figure 5, the dotted line represents the extinction coefficient of the niobium oxide film (Nb₂O₅ film), and the dashed line represents the extinction coefficient of the tungsten oxide film (WO₃ film). Both the niobium oxide and tungsten oxide films also have extinction coefficients of ≥0.1 in the wavelength range of 200 nm to 380 nm. It can be seen that such metal oxide films 25 absorb a certain amount of light in the ultraviolet region.

[0047] In the imaging device 1 with the metal oxide film 25, compared to the imaging device 1 without the metal oxide film 25, UV irradiation damage can be reduced. The increase in interface energy levels caused by ultraviolet light irradiation can be suppressed, as can the increase in dark current. Furthermore, the sensitivity of pixel P to incident ultraviolet light can be suppressed, and the decrease in the quantum efficiency of pixel P can be suppressed.

[0048] Furthermore, a metal oxide film 25 can be provided with a minimum extinction coefficient of 0.4 or higher in the wavelength range of 200 nm to 250 nm and an average extinction coefficient of 0.09 or higher in the wavelength range of 250 nm to 380 nm. By forming a tantalum oxide film, tungsten oxide film, or the like that that meets these conditions as the metal oxide film 25, UV irradiation damage can be effectively suppressed.

[0049] Figure 6 shows an example of the relationship between the thickness and transmittance of the metal oxide film 25 in the first embodiment. In Figure 6, the horizontal axis represents the film thickness, and the vertical axis schematically represents the transmittance for ultraviolet light. In Figure 6, the solid line represents the transmittance of the tantalum oxide film (Ta₂O₅ film). The dotted line represents the transmittance of the niobium oxide film (Nb₂O₅ film), and the dashed line represents the transmittance of the tungsten oxide film (WO₃ film). As shown in Figure 6, if the thickness of the metal oxide film 25 is greater than 20 nm, the transmittance is lower, the amount of transmitted light is reduced, and the quantum efficiency is significantly decreased.

[0050] Therefore, in this embodiment, the metal oxide film 25 is formed with a thickness of 1 nm to 20 nm. This suppresses the reduction in light received by the photoelectric conversion unit 12, ensuring the quantum efficiency required by the imaging device 1. Furthermore, the thickness of the metal oxide film 25 can be set to 1 nm to 10 nm. This effectively suppresses the reduction in quantum efficiency.

[0051] Figures 7 to 11 are illustrations showing one example of a manufacturing method for the imaging device according to the first embodiment. First, as shown in Figure 7, a photodiode PD corresponding to each pixel P separated by an element separation region 15 formed by a p-type semiconductor region is formed in the region of the silicon semiconductor substrate 10 where the pixel region is to be formed. Furthermore, the photodiode PD is formed to cover the entire thickness direction of the semiconductor substrate 10, and is configured as a pn junction type photodiode formed by an n-type semiconductor region and p-type semiconductor regions facing both sides of the semiconductor substrate 10.

[0052] On the surface of the semiconductor substrate 10 opposite to the light incident surface, in the region corresponding to each pixel P, a p-type semiconductor well region is formed, each connected to the element separation region 15. Pixel transistors for each pixel P are formed within these p-type semiconductor well regions. Furthermore, each pixel transistor comprises a source region, a drain region, a gate insulating film, and a gate electrode. Next, on the upper part of the surface of the semiconductor substrate 10 opposite to the light incident surface, a multilayer wiring layer 90 is formed, with multiple layers of wiring disposed across interlayer insulating films. Additionally, a chemical oxide film is formed on the back side of the substrate by a chemical solution treatment.

[0053] Next, as shown in FIG8, a fixed charge film 26 is formed on the surface of the semiconductor substrate 10 on the light incident side. For example, by means of ALD (Atomic Layer Deposition) method, a film such as aluminum oxide (Al 2O 3 film) is formed at a film formation temperature of 200~300°C to a film thickness of 1~20 nm, thereby forming the fixed charge film 26.

[0054] Then, as shown in Figure 9, a metal oxide film 25 is formed on the fixed charge film 26. For example, tantalum oxide (Ta₂O₅) can be deposited as the metal oxide film 25 by reactive sputtering using a mixture of oxygen and argon. In this case, the tantalum oxide film is formed at a film-forming temperature of room temperature to 400°C in a manner that does not damage the wiring layer. Considering the transmittance of ultraviolet light, the film thickness of tantalum oxide is set to about 1 nm to 20 nm. More ideally, the film thickness of tantalum oxide is about 1 nm to 10 nm.

[0055] Subsequently, as shown in Figure 10, an oxide film as an insulating film 24 is formed on the metal oxide film 25. This oxide film 24 is formed, for example, by plasma CVD (Chemical Vapor Deposition) at a film-forming temperature below 400°C in a manner that does not damage the wiring layer. Furthermore, a film of silicon oxide (SiO2) is formed as the oxide film 24 with a film thickness of about 50 nm to 200 nm in a manner that does not generate bubbles.

[0056] Furthermore, as shown in Figure 11, a light-shielding portion 31 can be formed on the oxide film 24. The light-shielding portion 31 is formed on the surface of the oxide film 24 using, for example, a metal film, more specifically tungsten (W), by sputtering. The light-shielding portion 31 can have a film thickness of 100 to 400 nm to block stray light components other than ultraviolet light. In cases where the adhesion is poor, a film of materials such as titanium with a thickness of about 1 to 50 nm can be formed as a barrier metal, i.e., component 32. In addition, if crosstalk in the effective pixel area for sensing light is not a concern, the light-shielding portion 31 may not be provided. However, it is more ideal to have the light-shielding portion 31 in the pixels of the black reference pixel area.

[0057] Subsequently, in order to form an opening for ultraviolet light introduction in the region corresponding to the photodiode PD, a patterning process is applied. This patterning process can be performed by selectively etching away the light-shielding portion 31 through a resist mask (not shown), forming the light-shielding portion 31 at the boundary of each pixel. In addition, etching can be performed using wet etching or dry etching, with dry etching being able to obtain fine linewidths of the light-shielding portion 31 with high precision.

[0058] Subsequently, a lens portion 21 is formed on the light incident surface side of the semiconductor substrate 10. The material for the lens portion 21 is, for example, silicon oxide, and more specifically, a silicon oxide film formed at a deposition temperature of 400°C or lower using plasma-enhanced chemical vapor deposition (PECVD) with a gas containing tetraethoxysilane (TEOS). The silicon oxide film formed using PECVD with this TEOS gas is called a P-TEOS film.

[0059] Secondly, after exposure and development following resist coating, the resist shape is formed by reflow achieved through heat treatment, followed by dry etching. This transfers a curved shape onto silicon oxide, enabling lens functionality. The imaging device 1 shown in Figure 3 can be manufactured using the above manufacturing method. Furthermore, the above-described manufacturing method for the imaging device is ultimately only one example; other manufacturing methods may be used.

[0060] [Functions and Effects] The light-receiving element (camera device) 1 of this embodiment includes: a metal oxide film 25, the maximum value of which has an extinction coefficient of 0.1 or more in the wavelength range of 200 nm to 380 nm; and a light-receiving part (photoelectric conversion part 12) that receives ultraviolet light transmitted through the metal oxide film 25.

[0061] In the imaging device 1 of this embodiment, since it has a metal oxide film 25 with a maximum extinction coefficient of 0.1 or more in the wavelength range of 200 nm to 380 nm, UV sensitivity can be ensured and UV irradiation damage can be suppressed. An imaging device 1 with high performance for ultraviolet light can be realized.

[0062] <2. Second Implementation Form> Next, a description will be given regarding the second embodiment of this disclosure. Hereinafter, the same reference numerals will be used for components identical to those in the above-described embodiment, and descriptions may be omitted as appropriate.

[0063] Figure 12 is a block diagram showing an example of the overall configuration of an imaging device, which is an example of a light-receiving element according to the second embodiment of this disclosure. The imaging device 1 is, for example, a CMOS image sensor. As shown in Figure 12, the imaging device 1 includes: a pixel unit 100, a vertical drive circuit 111, a horizontal readout circuit 112, a horizontal signal processing circuit 113, a horizontal drive circuit 114, an output circuit 115, and a control circuit 116. The pixel unit 100, the vertical drive circuit 111, the horizontal readout circuit 112, the horizontal signal processing circuit 113, the horizontal drive circuit 114, the output circuit 115, and the control circuit 116 are disposed on the same semiconductor substrate or on a plurality of electrically connected multilayer semiconductor substrates.

[0064] In the pixel section 100, a plurality of pixels P are arranged in a two-dimensional matrix. Furthermore, the pixel section 100 may sometimes include dummy pixels that do not have a photodiode structure, and light-blocking pixels that block light incident from the outside by blocking the light-receiving surface, etc., arranged in rows and / or columns.

[0065] In the pixel section 100, for a matrix-like pixel arrangement, a pixel driving line LD is formed for each column along the left-right direction in the diagram (the arrangement direction of pixels in a pixel column), and a vertical pixel wiring (vertical signal line) LV is formed for each row along the up-down direction in the diagram (the arrangement direction of pixels in a pixel row). One end of the pixel driving line LD is connected to the output terminal corresponding to each column of the vertical driving circuit 111.

[0066] The row readout circuit 112 includes at least: a circuit that supplies a constant current to each row of pixels P in the selected column within the pixel section 100, a current mirror circuit, and a switching switch for the pixel P to be read out. The row readout circuit 112, together with the transistors in the selected pixels within the pixel section 100, forms an amplifier that converts the photocharge signal into a voltage signal and outputs it to the vertical signal line LV.

[0067] The vertical drive circuit 111 includes a shift register and an address decoder, etc., and drives each pixel P of the pixel section 100 simultaneously or in column units. The specific configuration of the vertical drive circuit 111 is not shown in the figure, but it is configured to have a readout scanning system, an exclusion scanning system, or a batch exclusion and batch transfer system.

[0068] In order to read out the pixel signal from pixel P, the readout scanning system sequentially selects pixels P of the 100 scanning pixel section in column units. In the case of column drive (rolling shutter action), regarding exclusion, for the readout column scanned by the readout scanning system, exclusion scanning is performed by advancing the shutter speed by a time fraction of the readout scan.

[0069] Furthermore, in the case of global exposure (global shutter action), batch elimination is performed by advancing the shutter speed by a fraction of a time compared to batch transmission. Through this elimination, unnecessary charge is removed (reset) from the photodiodes of the self-readout pixels P. Moreover, this removal (resetting) of unnecessary charge enables what is known as electronic shutter action. Here, electronic shutter action refers to the action of discarding unnecessary charge accumulated in the photodiodes up to the moment electronic shutter action is performed and restarting exposure (starting the accumulation of photocharge).

[0070] The signal level of the pixel signal read out by the readout action of the readout scanning system corresponds to the amount of light incident immediately following the preceding readout action or electronic shutter action. In the case of column drive, the period from the readout timing of the preceding readout action or the exclusion timing of the electronic shutter action to the readout timing of the current readout action is the accumulation time (exposure time) of photocharge in pixel P. In the case of full-area exposure, the time from batch exclusion to batch transfer is the accumulation time (exposure time).

[0071] The pixel signals output from each pixel P of the pixel column selected for scanning by the vertical drive circuit 111 are supplied to the horizontal signal processing circuit 113 via the vertical signal line LV. The horizontal signal processing circuit 113 performs specific signal processing on the pixel signals output from each pixel P of the self-selected column via the vertical signal line LV for each pixel row of the pixel section 100, and temporarily holds the processed pixel signals.

[0072] Specifically, the horizontal signal processing circuit 113 performs at least noise removal processing, such as CDS (Correlated Double Sampling) processing, as a signal processing function. Through the CDS processing performed by the horizontal signal processing circuit 113, pixel-inherent fixed-pattern noise, such as reset noise or threshold deviation of the amplifying transistor (AMP), is removed. Furthermore, the horizontal signal processing circuit 113 may also be configured to, in addition to noise removal processing, have, for example, an AD conversion function to output the pixel signal as a digital signal.

[0073] The horizontal drive circuit 114 includes a shift register and an address decoder, which sequentially selects the unit circuits corresponding to the pixel rows of the line signal processing circuit 113. Through the selection scan performed by the horizontal drive circuit 114, the pixel signals processed by the line signal processing circuit 113 are sequentially output to the output circuit 115.

[0074] The control circuit 116 includes a timing generator that generates various timing signals, and performs drive control of the vertical drive circuit 111, the horizontal signal processing circuit 113, the horizontal drive circuit 114, etc. based on the various timing signals generated by the timing generator.

[0075] The imaging device 1 further includes an output circuit 115 and a data storage unit (not shown). The output circuit 115 has at least an addition processing function, performing various signal processing such as addition processing on the pixel signal output by the self-signal processing circuit 113. The data storage unit temporarily stores the data required for the signal processing during the signal processing of the output circuit 115. The output circuit 115 and the data storage unit can be processed by an external signal processing unit, such as a DSP (Digital Signal Processor) or software, located on a substrate different from that of the imaging device 1, or they can be mounted on the same substrate as the imaging device.

[0076] [Pixel Composition] Figure 13 shows an example of the pixel configuration of the imaging device in the second embodiment. Pixel P has a photodiode PD. The photodiode PD is an example of a light-receiving part (photoelectric conversion part 12). The photodiode PD is formed, for example, by forming a p-type layer on the surface side of the substrate for a p-type well layer formed on an n-type substrate, and embedding an n-type buried layer therein. That is, the above-described photodiode system is an embedded type photodiode. Furthermore, the n-type buried layer is configured to have an impurity concentration that becomes depleted when charge is discharged.

[0077] In addition to the photodiode PD, the pixel P also includes a TRY gate 41, a TX1 gate 42, a TX2 gate 43, and a charge retention section (MEM) 44. The TRY gate 41 is a transmission section connected between the photodiode PD and the charge retention section 44. The TX1 gate 42 and TX2 gate 43 are transmission sections, located near the charge retention section 44.

[0078] The charge holding portion 44 is formed, for example, by forming a p-type layer on the substrate surface side relative to a p-type well layer formed on an n-type substrate, and embedding an n-type buried layer therein. Furthermore, the n-type buried layer of the charge holding portion 44 can be formed by an n-type diffusion region. Specifically, it is sufficient to form an n-type diffusion region inside the p-type well layer and a p-type layer on the substrate surface side. This suppresses the accumulation of dark current at the Si-SiO2 interface in the n-type diffusion region of the charge holding portion 44, thereby improving the image quality of the imaging device 1.

[0079] The TRY gate 41 transfers the charge stored inside the photodiode PD, which has undergone photoelectric conversion by the photodiode PD, to the charge holding section 44 by applying a drive signal TRY to the gate electrode. Furthermore, the TRY gate 41 also functions as a gate to prevent the charge from flowing back from the charge holding section 44 to the photodiode PD.

[0080] The TX1 gate 42 functions as a gate for transferring charge from the charge holding section 44 to the floating diffusion region (FD, described later). Furthermore, the TX1 gate 42 also functions as a gate for maintaining charge in the charge holding section 44. The TX2 gate 43 functions as a gate for transferring charge from the photodiode PD to the charge holding section 44. Furthermore, the TX2 gate 43 also functions as a gate for maintaining charge in the charge holding section 44.

[0081] In the charge holding section 44, a modulation is applied to the charge holding section 44 by applying drive signals TX2 and TX1 to the gate electrodes of gate TX2 43 and gate TX1 42, respectively. That is, by applying drive signals TX2 and TX1 to the gate electrodes of gate TX2 43 and gate TX1 42, respectively, the potential of the charge holding section 44 can be increased. This increases the saturated charge in the charge holding section 44 compared to the case where no modulation is applied.

[0082] Furthermore, pixel P further includes a TRG gate 45 and a floating diffusion region 46. The TRG gate 45 is a transmission unit that transmits the charge stored in the charge holding unit 44 to the floating diffusion region 46 by applying a drive signal TRG to the gate electrode. The floating diffusion region 46 is a charge-voltage conversion unit containing an n-type layer that converts the charge transmitted from the charge holding unit 44 by the TRG gate into voltage.

[0083] Pixel P further includes a reset transistor (RST) 47, an amplifying transistor (AMP) 48, and a select transistor (SEL) 49. Furthermore, in the example shown in Figure 13, an example using an n-channel MOS transistor is illustrated for the reset transistor 47, the amplifying transistor 48, and the select transistor 49. However, the configuration of the reset transistor 47, the amplifying transistor 48, and the select transistor 49 is not limited to the example shown in Figure 13.

[0084] A reset transistor 47 is connected between the power supply Vrst and the floating diffusion region 46. The reset transistor 47 resets the floating diffusion region 46 by applying a drive signal RST to its gate electrode. An amplifying transistor 48 connects its drain electrode to the power supply Vdd and its gate electrode to the floating diffusion region 46, reading the voltage of the floating diffusion region 46. A select transistor 49 connects its drain electrode to the source electrode of the amplifying transistor 48 and its source electrode to the vertical signal line LV. The select transistor 49 selects the pixel P from which the pixel signal should be read by applying a drive signal SEL to its gate electrode.

[0085] Furthermore, in the example shown in Figure 13, the select transistor 49 is connected between the source electrode of the amplifying transistor 48 and the vertical signal line LV. However, the select transistor 49 can also be connected between the power supply Vdd and the drain electrode of the amplifying transistor 48. In addition, one or more of the reset transistor 47, amplifying transistor 48, and select transistor 49 can be omitted depending on the readout method of the pixel signal.

[0086] Furthermore, an overflow gate (OFG) 50 is provided at pixel P to prevent overflow. The aforementioned overflow gate 50 discharges the charge of the photodiode PD to the n-type layer 51 connected to the power supply Vdd by applying a drive signal OFG to the gate electrode at the start of exposure.

[0087] The imaging device 1, which has the pixel P described so far, can achieve global shutter action (global exposure) by simultaneously starting exposure for all pixels and performing exposure for all pixels simultaneously. Furthermore, this global shutter action enables imaging without distortion caused by the uniform exposure period for all pixels. In the example shown in Figure 13, an example is shown where an n-type buried channel is formed in a p-type well layer to constitute pixel P, but opposite conductivity types can be used. In this case, the potential relationships are completely reversed.

[0088] [Pixel Structure] Figure 14 is a cross-sectional view showing an example of the imaging device in the second embodiment. A charge retention section (MEM) 44 is provided on the semiconductor substrate 10 for each pixel P. The light-shielding film 31 prevents light from entering the area other than the photoelectric conversion section (photodiode) 12 by forming an opening only in the area corresponding to the photoelectric conversion section (photodiode) 12, allowing incident light toward the photoelectric conversion section 12 to pass through.

[0089] Furthermore, in the case where ultraviolet light is absorbed only by the surface layer of the semiconductor substrate 10, since the charge holding portion 44 is located on the wiring layer side of the semiconductor substrate 10 and is far from the irradiated surface side, the light-shielding portion 31 may not be required. However, it is more ideal for the pixels in the black reference pixel area to have the light-shielding portion 31.

[0090] Ultraviolet (UV) sensors are primarily used in machine vision inspections for production applications. Machine vision systems strongly require the detection of high-speed moving objects to minimize inspection time, but there is a risk of shutter distortion or blurring of moving objects during rolling shutter operations.

[0091] On the other hand, since a global shutter can receive the light from the object being inspected at any given moment in all pixels, it avoids the aforementioned problems and improves inspection accuracy. That is, the imaging device 1 in this embodiment is preferably combined with a global shutter function. Furthermore, by employing the crosstalk suppression structure described above, costs can be reduced.

[0092] Secondly, variations of this disclosure will be explained. Hereinafter, the same symbols will be used for the constituent elements that are the same as those in the above embodiments, and explanations will be omitted where appropriate.

[0093] (3-1. Variation Example 1) The metal oxide film 25 can be composed of niobium oxide or tungsten oxide. Alternatively, the metal oxide film 25 can be a multilayer film containing two or more of tantalum oxide, niobium oxide, and tungsten oxide. This type of oxide film 25 is a material that absorbs a certain amount of ultraviolet light, thus inhibiting UV irradiation damage.

[0094] (3-2. Variation Example 2) Ideally, the metal oxide film 25 should be composed of a material whose standard formation free energy (refer to "Revised 4th Edition of the Handbook of Metals, edited by the Japan Society for Metals, Maruzen Publishing Co., Ltd.") is greater than or equal to the standard formation free energy of silicon oxide. The standard formation free energies of tantalum oxide, niobium oxide, and tungsten oxide are respectively greater than or equal to the standard formation free energy of silicon oxide.

[0095] In the case where a metal oxide film 25 has a "standard formation free energy of oxides" that is larger than that of silicon oxide constituting the oxide film on the semiconductor substrate 10, the removal of oxygen atoms from the metal oxide film 25 is more energy-stable in chemical reactions than the removal of oxygen atoms from the oxide film. Therefore, the phenomenon of oxygen atom removal from the oxide film due to ultraviolet irradiation can be suppressed, protecting the interface layer between the oxide film and the light-incident surface of the semiconductor substrate 10, and suppressing the generation of dark current caused by the formation of interface energy levels. In the experimental results of the inventors, tantalum oxide, niobium oxide, and tungsten oxide were found to be more ideal in the characteristic evaluation of defects in solid-state imaging elements, with tantalum oxide being particularly suitable.

[0096] <4. Application Examples> The aforementioned camera device 1 can be applied to camera systems such as digital still cameras or video cameras, or to all types of electronic devices with video recording capabilities, such as mobile phones with video recording capabilities. Figure 15 shows a schematic configuration of the electronic device 1000.

[0097] The electronic device 1000 includes, for example, a lens group 1001, a camera device 1, a DSP (Digital Signal Processor) circuit 1002, a frame memory 1003, a display unit 1004, a recording unit 1005, an operation unit 1006, and a power supply unit 1007, and is interconnected via a busbar 1008.

[0098] The lens group 1001 captures incident light (image light) from the subject and images it onto the imaging surface of the imaging device 1. The imaging device 1 converts the amount of incident light imaged onto the imaging surface by the lens group 1001 into an electrical signal in pixel units and supplies it to the DSP circuit 1002 as a pixel signal.

[0099] The DSP circuit 1002 is a signal processing circuit that processes signals supplied from the camera device 1. The DSP circuit 1002 outputs image data obtained by processing signals from the camera device 1. The frame memory 1003 temporarily stores the image data processed by the DSP circuit 1002 in frame units.

[0100] The display unit 1004 includes a panel-type display device such as a liquid crystal panel or an organic EL (Electro Luminescence) panel, and records the image data of animation or still images captured by the camera device 1 on a recording medium such as a semiconductor memory or a hard disk.

[0101] The operation unit 1006 outputs operation signals related to the various functions of the electronic device 1000 according to the user's operation. The power supply unit 1007 is a suitable supplier of various power supplies for the operation of the DSP circuit 1002, frame memory 1003, display unit 1004, recording unit 1005 and operation unit 1006.

[0102] The present invention has been described above with examples of embodiments and variations, but the technology is not limited to the above embodiments and various variations are possible. For example, the above variations are described as variations of the above embodiments, but the configurations of each variation can be appropriately combined. For example, the present disclosure is not limited to back-illuminated image sensors, but can also be applied to surface-illuminated image sensors.

[0103] Furthermore, the effects described in this specification are ultimately illustrative only and not limited to those described, and may have other effects. Also, this disclosure may also take the following form. (1) A light-receiving element, comprising: The metal oxide film has an extinction coefficient of ≥0.1 in the wavelength range of 200 nm to 380 nm; and The light-receiving part receives ultraviolet light that passes through the aforementioned metal oxide film. (2) As described in (1) above, the minimum extinction coefficient of the aforementioned metal oxide film in the wavelength range of 200 nm to 250 nm is 0.4 or higher; and The average extinction coefficient of the aforementioned metal oxide film is above 0.09 in the wavelength range of 250 nm to 380 nm. (3) As in the aforementioned (1) or (2) light-receiving element, wherein the wavelength range of the aforementioned ultraviolet light includes a wavelength range of 200 nm to 380 nm; and The aforementioned light-receiving part will perform photoelectric conversion using ultraviolet light transmitted through the aforementioned metal oxide film. (4) The light-receiving element of any one of (1) to (3) above, wherein the aforementioned metal oxide film contains at least one of tantalum oxide, niobium oxide and tungsten oxide. (5) The light-receiving element is any one of (1) to (4) above, wherein the thickness of the aforementioned metal oxide film is more than 1 nm and less than 20 nm. (6) The light-receiving element is as described in any of (1) to (5) above, wherein the aforementioned metal oxide film contains tantalum oxide; and The thickness of the aforementioned metal oxide film is between 1 nm and 20 nm. (7) The light-receiving element is any one of (1) to (6) above, wherein the standard generation free energy of the aforementioned metal oxide film is greater than or equal to the standard generation free energy of silicon oxide. (8) A light-receiving element, comprising: A lens that allows ultraviolet light to pass through; A metal oxide film, which allows light passing through the aforementioned lens to enter; and The light-receiving part receives light transmitted through the aforementioned lens and the aforementioned metal oxide film; and The maximum extinction coefficient of the aforementioned metal oxide film in the wavelength range of 200 nm to 380 nm is 0.1 or higher. (9) As described in (8) above, the light-receiving element, wherein the aforementioned lens is made of silicon oxide. (10) As in the aforementioned light-receiving element (8) or (9), the minimum extinction coefficient of the aforementioned metal oxide film in the wavelength range of 200 nm to 250 nm is 0.4 or higher; and The average extinction coefficient of the aforementioned metal oxide film is above 0.09 in the wavelength range of 250 nm to 380 nm. (11) The light-receiving element is any one of (8) to (10) above, wherein the wavelength range of the aforementioned ultraviolet light includes a wavelength range of 200 nm to 380 nm. (12) The light-receiving element of any one of (8) to (11) above, wherein the aforementioned metal oxide film contains at least one of tantalum oxide, niobium oxide and tungsten oxide. (13) The light-receiving element is any one of (8) to (12) above, wherein the thickness of the aforementioned metal oxide film is more than 1 nm and less than 20 nm. (14) The light-receiving element is as described in any of (8) to (13) above, wherein the aforementioned metal oxide film contains tantalum oxide; and The thickness of the aforementioned metal oxide film is between 1 nm and 20 nm. (15) The light-receiving element is any one of (8) to (14) above, wherein the standard generation free energy of the aforementioned metal oxide film is greater than or equal to the standard generation free energy of silicon oxide. (16) The light-receiving element of any one of (1) to (15) above has a fixed charge film disposed between the aforementioned metal oxide film and the aforementioned light-receiving part. (17) The light-receiving element as described in (16) above, wherein the aforementioned fixed charge film contains aluminum oxide. (18) The light-receiving element as described in any of (1) to (17) above has the following features: A substrate having a plurality of the following portions: a light-receiving portion that receives light and generates an electric charge; a holding portion that holds the electric charge; and a transfer portion that transfers the electric charge generated by the light-receiving portion to the holding portion; The wiring layer is located on the opposite side to the side where light is incident; and The control unit controls multiple of the aforementioned transmission units using a global shutter method. (19) An electronic device includes a light-receiving element comprising: a metal oxide film and a light-receiving portion for receiving ultraviolet light transmitted through the aforementioned metal oxide film; and The maximum extinction coefficient of the aforementioned metal oxide film in the wavelength range of 200 nm to 380 nm is 0.1 or higher. (20) An electronic device includes a light-receiving element comprising: a lens through which ultraviolet light passes; a metal oxide film through which light passing through the lens is incident; and a light-receiving section for receiving light passing through the lens and the metal oxide film; and The maximum extinction coefficient of the aforementioned metal oxide film in the wavelength range of 200 nm to 380 nm is 0.1 or higher.

[0104] 1: Camera device (light receiving element) 10: Semiconductor substrate / substrate 11S1: Page 1 11S2: Page 2 12: Photoelectric conversion unit (photodiode) 15: Separation section 20: Light guide section 21: Lens section 24: Insulating film 25: Metal oxide film 26: Fixed charge film 31:Light shielding part 32: Components / Seamless Layer 41: TRY gate 42:TX1 gate 43: TX2 gate 44: Charge Holding Section (MEM) 45: TRG gate 46: Floating diffusion area 47: Reset Transistor (RST) 48: Amplifying Transistor (AMP) 49: Selective Transistor (SEL) 50: Overflow Gate (OFG) 51: n-type layer 90: Multilayer wiring 91: Gate electrode 100: Pixels 111: Vertical drive circuit 112: Line Readout Circuit 113: Linear Signal Processing Circuit 114: Horizontal drive circuit 115: Output Circuit 116: Control Circuit 117: Input / output terminals 121: Horizontal signal line 1000: Electronic Machines 1001: Lens Group 1002: DSP Circuit 1003: Frame Memory 1004: Display Section 1005: Recording Department 1006: Operations Department 1007: Power Supply Department 1008: Busbar FD: Floating Diffusion Region LD: Pixel drive line Lread: Pixel driving line Lsig: Vertical signal line LV: Vertical pixel wiring (vertical signal line) P: pixel PD: Photodiode Qe: Quantum efficiency RST, SEL: Drive signals Vdd, Vrst: Power supply X, Y, Z: axes

Claims

1. A light-receiving element comprising: a metal oxide film having a maximum extinction coefficient of 0.1 or more in a wavelength range of 200 nm to 380 nm; and a light-receiving portion receiving ultraviolet light transmitted through the metal oxide film; wherein the wavelength range of the ultraviolet light includes a wavelength range of 200 nm to 380 nm; and the light-receiving portion performing photoelectric conversion on the ultraviolet light transmitted through the metal oxide film.

2. The light-receiving element of claim 1, wherein the minimum extinction coefficient of the aforementioned metal oxide film in the wavelength range of 200 nm to 250 nm is 0.4 or more; and the average extinction coefficient of the aforementioned metal oxide film in the wavelength range of 250 nm to 380 nm is 0.09 or more.

3. The light-receiving element of claim 1, wherein the aforementioned metal oxide film contains at least one of tantalum oxide, niobium oxide, and tungsten oxide.

4. The light-receiving element as claimed in claim 1, wherein the thickness of the aforementioned metal oxide film is more than 1 nm and less than 20 nm.

5. The light-receiving element of claim 1, wherein the aforementioned metal oxide film contains tantalum oxide; and the thickness of the aforementioned metal oxide film is more than 1 nm and less than 20 nm.

6. The light-receiving element as claimed in claim 1, wherein the standard generation free energy of the aforementioned metal oxide film is greater than or equal to the standard generation free energy of silicon oxide.

7. A light-receiving element comprising: a lens that transmits ultraviolet light; a metal oxide film that allows light transmitted through the lens to be incident upon; and a light-receiving portion that receives light transmitted through the lens and the metal oxide film; wherein the maximum value of the extinction coefficient of the metal oxide film in the wavelength range of 200 nm to 380 nm is 0.1 or more; wherein the wavelength range of the ultraviolet light includes the wavelength range of 200 nm to 380 nm; and the light-receiving portion performs photoelectric conversion on the ultraviolet light transmitted through the lens and the metal oxide film.

8. The light-receiving element as claimed in claim 7, wherein the aforementioned lens is made of silicon oxide.

9. The light-receiving element of claim 7, wherein the minimum extinction coefficient of the aforementioned metal oxide film in the wavelength range of 200 nm to 250 nm is 0.4 or more; and the average extinction coefficient of the aforementioned metal oxide film in the wavelength range of 250 nm to 380 nm is 0.09 or more.

10. The light-receiving element of claim 7, wherein the aforementioned metal oxide film contains at least one of tantalum oxide, niobium oxide, and tungsten oxide.

11. The light-receiving element as claimed in claim 7, wherein the thickness of the aforementioned metal oxide film is more than 1 nm and less than 20 nm.

12. The light-receiving element of claim 7, wherein the aforementioned metal oxide film contains tantalum oxide; and the thickness of the aforementioned metal oxide film is more than 1 nm and less than 20 nm.

13. The light-receiving element as claimed in claim 7, wherein the standard generation free energy of the aforementioned metal oxide film is greater than or equal to the standard generation free energy of silicon oxide.

14. The light-receiving element of claim 1, which includes a fixed charge film disposed between the aforementioned metal oxide film and the aforementioned light-receiving portion.

15. The light-receiving element of claim 14, wherein the aforementioned fixed charge film contains aluminum oxide.

16. The light-receiving element of claim 1, comprising: a substrate having a plurality of the aforementioned light-receiving portions, a plurality of holding portions, and a plurality of transmitting portions, wherein the aforementioned light-receiving portions receive light and generate charge, the aforementioned holding portions hold charge, and the aforementioned transmitting portions transmit the charge generated by the aforementioned light-receiving portions to the aforementioned holding portions; a wiring layer disposed on the side opposite to the side on which light is incident; and a control unit that controls the plurality of the aforementioned transmitting portions by means of a global shutter method.

17. An electronic device comprising a light-receiving element having: a metal oxide film and a light-receiving portion for receiving ultraviolet light transmitted through the metal oxide film; wherein the maximum value of the extinction coefficient of the metal oxide film in the wavelength range of 200 nm to 380 nm is 0.1 or more; wherein the wavelength range of the ultraviolet light includes the wavelength range of 200 nm to 380 nm; and wherein the light-receiving portion performs photoelectric conversion on the ultraviolet light transmitted through the metal oxide film.

18. An electronic device comprising a light-receiving element, the light-receiving element having: a lens that transmits ultraviolet light; a metal oxide film that allows light transmitted through the lens to be incident upon it; and a light-receiving section that receives light transmitted through the lens and the metal oxide film; wherein the maximum value of the extinction coefficient of the metal oxide film in the wavelength range of 200 nm to 380 nm is 0.1 or more; wherein the wavelength range of the ultraviolet light includes the wavelength range of 200 nm to 380 nm; and the light-receiving section performs photoelectric conversion on the ultraviolet light transmitted through the lens and the metal oxide film.

Images