Solid-state imaging element and electronic device

Abstract

Provided are a solid-state imaging element and an electronic device provided with the solid-state imaging element, the solid-state imaging element having a photoelectric conversion unit that performs photoelectric conversion, the photoelectric conversion unit being provided with a metal-based particle aggregate in which a plurality of metal-based particles are arranged so as to be separated from each other, each of the plurality of metal-based particles is disposed such that the average distance between the metal-based particles and adjacent metal-based particles is 1 nm to 25 [mu] m, and the standard deviation of the average distance is 10 [mu] m or less.

Description

Technical Field

[0001] The present invention relates to a solid-state imaging element and an electronic device including the solid-state imaging element. Background Art

[0002] In recent years, pixel size has been shrinking in solid-state imaging devices, such as CMOS (Complementary Metal Oxide Semiconductor) devices. This reduction in pixel size reduces the amount of light received per pixel, leading to a demand for increased sensitivity. For example, Patent Document 1 describes forming a fine concave-convex structure on the light-receiving surface of a substrate where a photoelectric conversion region is provided as one method for improving sensitivity.

[0003] Prior art literature

[0004] Patent Literature

[0005] Patent Document 1: Japanese Patent Application Laid-Open No. 2022-075774 Summary of the Invention

[0006] Problems to be solved by the invention

[0007] An object of the present invention is to provide a solid-state imaging element capable of improving sensitivity and an electronic device including the solid-state imaging element.

[0008] Solutions for solving problems

[0009] The present invention provides the following.

[0010] [1] A solid-state imaging element having a photoelectric conversion unit for performing photoelectric conversion,

[0011] The solid-state imaging element includes a metal-based particle aggregate in which a plurality of metal-based particles are arranged separately from each other.

[0012] In the metal-based particle aggregate, the plurality of metal-based particles are arranged such that an average distance between adjacent metal-based particles is 1 nm or more and 25 μm or less, and a standard deviation of the average distance is 10 μm or less.

[0013] [2] A solid-state imaging element having a photoelectric conversion unit for performing photoelectric conversion,

[0014] The solid-state imaging element includes a metal-based particle aggregate in which a plurality of metal-based particles are arranged separately from each other.

[0015] The plurality of metal-based particles have an average particle size of 200 nm to 600 μm, an average height of 3.0 nm to 150 μm, and an aspect ratio defined as the ratio of the average particle size to the average height of 1 to 8.

[0016] In the metal-based particle aggregate, the plurality of metal-based particles are arranged such that an average distance between adjacent metal-based particles is 1 nm or more and 25 μm or less.

[0017] [3] The solid-state imaging element according to [1] or [2], wherein the metal-based particles contain a noble metal.

[0018] [4] The solid-state imaging element according to [3], wherein the noble metal is silver or gold.

[0019] [5] The solid-state imaging device according to any one of [1] to [4], further comprising a covering layer covering the metal-based particle aggregate.

[0020] [6] The solid-state imaging element according to [5], wherein the cover layer is a silicon atom-containing layer having a first surface,

[0021] The signal intensity of carbon atoms on the first surface of the covering layer measured by X-ray photoelectron spectroscopy is 20.0 atomic % or less.

[0022] [7] The solid-state imaging element according to any one of [1] to [6], wherein the electromagnetic wave photoelectrically converted by the photoelectric conversion portion includes an electromagnetic wave having a maximum wavelength of 200 nm to 3 mm.

[0023] [8] A solid-state imaging element having a photoelectric conversion unit for performing photoelectric conversion,

[0024] The solid-state imaging element comprises a metal-based particle aggregate in which a plurality of metal-based particles are arranged separately from each other, and

[0025] a covering layer covering the aforementioned metal-based particle aggregates,

[0026] The aforementioned covering layer is a silicon-containing atom layer having a first surface,

[0027] The signal intensity of carbon atoms on the first surface of the covering layer measured by X-ray photoelectron spectroscopy is 20.0 atomic % or less.

[0028] [9] An electronic device comprising the solid-state imaging element according to any one of [1] to [8].

[0029] Effects of the Invention

[0030] In a solid-state imaging element, it is possible to improve sensitivity. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 This is a cross-sectional view schematically showing an example of a metal-based particle aggregate.

[0032] Figure 2 This is a cross-sectional view schematically showing an example of a metal-based particle assembly covered with a coating layer.

[0033] Figure 3 It is a cross-sectional view schematically showing a pixel included in the solid-state imaging element according to the first embodiment of the present invention.

[0034] Figure 4 It is a cross-sectional view schematically showing a pixel included in a solid-state imaging element according to a second embodiment of the present invention.

[0035] Figure 5 It is a cross-sectional view schematically showing a pixel included in a solid-state imaging element according to a third embodiment of the present invention.

[0036] Figure 6 It is a cross-sectional view schematically showing a pixel included in a solid-state imaging element according to a fourth embodiment of the present invention.

[0037] Figure 7 It is a cross-sectional view schematically showing a pixel included in a solid-state imaging element according to a fifth embodiment of the present invention.

[0038] Figure 8 It is a cross-sectional view schematically showing a pixel included in a solid-state imaging element according to a sixth embodiment of the present invention.

[0039] Figure 9 It is a cross-sectional view schematically showing a pixel included in a solid-state imaging element according to a seventh embodiment of the present invention.

[0040] Figure 10 It is a cross-sectional view schematically showing a pixel included in a solid-state imaging element according to an eighth embodiment of the present invention.

[0041] Figure 11 It is a cross-sectional view schematically showing a pixel included in a solid-state imaging element according to a ninth embodiment of the present invention.

[0042] Figure 12 It is a cross-sectional view schematically showing a pixel included in the solid-state imaging element according to the tenth embodiment of the present invention.

[0043] Figure 13 It is a cross-sectional view schematically showing a pixel included in the solid-state imaging element according to the eleventh embodiment of the present invention.

[0044] Figure 14 It is a cross-sectional view schematically showing a pixel included in the solid-state imaging element according to the twelfth embodiment of the present invention.

[0045] Figure 15 Schematic cross-sectional view of a light absorbing element produced in the experimental example.

[0046] Figure 16 This is a cross-sectional view schematically showing an optical system for measuring the light absorptivity of a light absorbing element. DETAILED DESCRIPTION

[0047] The following describes embodiments of the present invention with reference to the accompanying drawings, but the present invention is not limited to the following embodiments. All of the following drawings are provided to aid understanding of the present invention, and the sizes and shapes of the components shown in the drawings are not necessarily consistent with the sizes and shapes of the actual components.

[0048] Solid-state imaging device

[0049] (1) Summary

[0050] The solid-state imaging element of the present invention comprises a photoelectric conversion unit for photoelectrically converting electromagnetic waves and a metal-based particle aggregate. The solid-state imaging element of the present invention can be formed by incorporating the metal-based particle aggregate into a conventional solid-state imaging element. The electromagnetic waves photoelectrically converted by the photoelectric conversion unit can include those having a maximum wavelength of 200 nm to 3 mm.

[0051] The solid-state imaging element of the present invention may be, for example, a CMOS solid-state imaging element or a CCD (Charge Coupled Devices) solid-state imaging element, and is preferably a CMOS solid-state imaging element.

[0052] The metal-based particle aggregate is a structure composed of a plurality of metal-based particles arranged separately from each other, preferably a plasmon structure. "Plasmon structure" refers to a structure that can show localized plasmon resonance. Plasmon refers to a compression wave of free electrons generated by the collective oscillation of free electrons in the structure. By incorporating a metal-based particle aggregate, preferably a metal-based particle aggregate that is a plasmon structure, into a solid-state imaging element, the electromagnetic wave absorption efficiency (also referred to as photoelectric conversion efficiency) in the photoelectric conversion unit such as a photodiode (PD) can be enhanced. Thereby, it is possible to solve the problem of reduced sensitivity caused by, for example, a reduction in the amount of light received by each pixel due to the reduction in pixel size, and to improve the sensitivity of each pixel. Alternatively, the sensitivity can be maintained, and the thin filmization of the photoelectric conversion unit in each pixel can be achieved.

[0053] In order to effectively enhance the electromagnetic wave absorption efficiency of the metal-based particle aggregates, the metal-based particle aggregates are preferably arranged near the photoelectric conversion unit, more preferably adjacent to the photoelectric conversion unit, in the solid-state imaging element. As described below, by appropriately controlling the structure of the metal-based particle aggregates, the range of action of the plasmon resonance shown by the metal-based particle aggregates as plasmon structures can be expanded. Therefore, the distance between the metal-based particle aggregates and the photoelectric conversion unit can be, for example, 10 nm or more, further tens of nm (e.g., 20 nm, 30 nm, or 40 nm) or more, and further 100 nm or more or 200 nm or more. In the case where the electromagnetic wave absorbed by the photoelectric conversion unit is, for example, visible light, from the perspective of effectively enhancing the electromagnetic wave absorption efficiency, the distance is preferably 200 nm or less, more preferably 150 nm or less, further preferably 100 nm or less, further preferably 50 nm or less, and particularly preferably 30 nm or less. When the electromagnetic waves absorbed by the photoelectric conversion unit are other than visible light, the distance is preferably less than 1 / 2 of the wavelength of the electromagnetic wave, more preferably less than 1 / 3, and even more preferably less than 1 / 4. Specifically, when the electromagnetic waves are in the near-infrared region, the distance is preferably less than 1250 nm, more preferably less than 830 nm, and even more preferably less than 625 nm. Furthermore, when the electromagnetic waves are in the terahertz wavelength band, the distance is preferably less than 150 μm, more preferably less than 100 μm, and even more preferably less than 75 μm.

[0054] In a solid-state imaging element, the metal-based particle aggregate is preferably disposed at a position that does not obstruct electromagnetic waves from reaching the photoelectric conversion portion. This position refers to, for example, a position to the side of or below the photoelectric conversion portion, with the incident side of the photoelectric conversion portion being the upper side and the incident side of the electromagnetic wave entering the solid-state imaging element being the upper side.

[0055] (2) Metallic particle aggregates

[0056] Figure 1 This is a cross-sectional view schematically showing an example of a metal-based particle aggregate. Figure 1 In the example shown, the metal-based particle aggregate 20 is stacked on the substrate 10. The metal-based particle aggregate layer 20 is a collection of a plurality of metal-based particles 21, and is a layer composed of a plurality of metal-based particles 21 that are arranged separately from each other. Figure 1 As shown, the plurality of metal-based particles 21 are preferably arranged two-dimensionally and separated from each other.

[0057] The metal-based particle aggregation layer preferably satisfies any one of the structural characteristics selected from the following [A] and [B], and more preferably satisfies both.

[0058] [A] In a metal-based particle aggregate, a plurality of metal-based particles are arranged such that the average distance between adjacent metal-based particles (hereinafter also referred to as "average inter-particle distance") is greater than 1 nm and less than 25 μm, and the standard deviation of the average inter-particle distance is less than 10 μm.

[0059] [B] The average particle size of the plurality of metal-based particles constituting the metal-based particle aggregate is greater than or equal to 200 nm and less than or equal to 600 μm, the average height is greater than or equal to 3.0 nm and less than or equal to 150 μm, the aspect ratio defined as the ratio of the average particle size to the average height is greater than or equal to 1 and less than or equal to 8, and in the metal-based particle aggregate, the plurality of metal-based particles are arranged so that the average inter-particle distance is greater than or equal to 1 nm and less than or equal to 25 μm.

[0060] A metal-based particle aggregate having a structure satisfying the above-mentioned prescribed conditions [A] and / or [B] can exhibit the following characteristics [a] and [b]. These characteristics are believed to be manifested by the interaction between localized plasmons exhibited by the plurality of metal-based particles constituting the metal-based particle aggregate.

[0061] [a] The plasmon resonance exhibited by the metal-based particle aggregate has a wide range of action. This can expand the range of the effect of enhancing the electromagnetic wave absorption efficiency caused by the plasmon, thereby relatively extending the distance from the metal-based particle aggregate to the photoelectric conversion unit.

[0062] [b] The metal-based particle aggregates exhibit strong plasmon resonance, thereby achieving a strong enhancement effect on the electromagnetic wave absorption efficiency of the photoelectric conversion unit.

[0063] Regarding [b] above, the intensity of plasmon resonance exhibited by a metallic particle aggregate is not the simple sum of the localized plasmon resonances exhibited by each metallic particle at a specific wavelength, but rather an intensity greater than that sum. In a metallic particle aggregate having a structure satisfying [A] and / or [B] above, the metallic particles interact with each other, exhibiting strong plasmon resonance. This strong plasmon resonance is believed to be manifested by the interaction between the localized plasmons of the metallic particles.

[0064] Generally speaking, when measuring the absorption spectrum of a plasmon structure using absorption spectrophotometry, a plasmon resonance peak (hereinafter referred to as a "plasmon peak") is observed. The intensity of the plasmon resonance of the plasmon structure can be evaluated based on the absorbance at the maximum wavelength of the plasmon peak. The intensity of the plasmon resonance tends to increase with increasing absorbance.

[0065] The absorption spectrum of the plasmon structure can be measured using absorption spectrophotometry. Specifically, the absorption spectrum is obtained as follows: using an integrating sphere spectrophotometer, incident light is irradiated from the back side of the glass substrate stacked with metal-based particle aggregates (the opposite side of the metal-based particle aggregates) and perpendicular to the substrate surface, and the intensity I of the transmitted light in all directions transmitted to the metal-based particle aggregate side, and the intensity I0 of the transmitted light in all directions transmitted from the opposite side of the incident surface when the incident light is irradiated from a direction perpendicular to the surface of the substrate having the same thickness and material as the substrate of the measurement sample and not stacked with metal-based particle aggregates. At this time, the vertical axis of the absorption spectrum, i.e., the absorbance, is expressed by the following formula:

[0066] Absorbance = -log 10 (I / I0)

[0067] Absorption spectra can be measured using a standard spectrophotometer. When measuring the maximum wavelength of the plasmon peak and its absorbance, it is also possible to narrow the field of view using an objective lens and spectrophotometer.

[0068] In order to form a plasmon structure from a metal-based particle aggregate, the metal-based particles preferably contain a plasmon-resonant material. A plasmon-resonant material is one that, when formed into particles or aggregates thereof, exhibits a plasmon peak in absorption spectra measured by absorption spectrophotometry.

[0069] Examples of metal-based materials capable of plasmon resonance in the visible light region include: precious metals such as gold, silver, copper, platinum, and palladium; metals other than precious metals such as aluminum and tantalum; alloys containing a metal selected from the precious metal and metals other than precious metals; and metal compounds (metal oxides, metal salts, etc.) containing a metal selected from the precious metal and metals other than precious metals. Preferred metal-based materials capable of plasmon resonance are precious metals such as gold, silver, copper, platinum, and palladium, with gold and silver being more preferred. The metal-based material constituting the metal-based particles is preferably selected based on the wavelength region of the electromagnetic wave absorbed and photoelectrically converted by the photoelectric conversion unit. This is because the appropriate wavelength region for effectively exhibiting plasmon resonance may differ depending on the type of metal-based material. When the wavelength of the electromagnetic wave subjected to photoelectric conversion exceeds 1 μm, the metal-based material may be a metal other than a precious metal. For example, iron, stainless steel, etc. are also preferably used.

[0070] For example, when the electromagnetic wave incident on the solid-state imaging element, that is, the electromagnetic wave absorbed and photoelectrically converted by the photoelectric conversion portion of the solid-state imaging element, is in the visible light region, the above-mentioned metal-based materials are preferably gold, silver, copper, and aluminum; in the near-infrared region, gold and silver are preferably used; in the electromagnetic field wavelength region of several μm including the terahertz band, in addition to precious metals such as gold, silver, and copper, metals other than precious metals such as iron, stainless steel, and aluminum can also be used.

[0071] From the perspective of effectively achieving the effects of [a] and [b] above, the average particle size of the plurality of metal-based particles constituting the metal-based particle aggregate is preferably 200 nm or more and 600 μm or less, more preferably 250 nm or more and 540 μm or less, further preferably 300 nm or more and 500 nm or less, and may also be 400 μm or less, 300 μm or less, 100 μm or less, 50 μm or less, 20 μm or less, 10 μm or less, 5 μm or less, or 3 μm or less. The average particle size of the metal-based particles is preferably appropriately selected according to the type of metal-based material constituting the metal-based particles. In addition, the average particle size of the metal-based particles is preferably selected according to the wavelength region of the electromagnetic wave absorbed and photoelectrically converted by the photoelectric conversion unit. The reason for this is that the appropriate wavelength region for effectively exhibiting plasmon resonance may be different depending on the average particle size of the metal-based particles.

[0072] For example, when the electromagnetic wave incident on the solid-state imaging element, that is, the electromagnetic wave absorbed and photoelectrically converted by the photoelectric conversion portion of the solid-state imaging element, is in the visible light region, the average particle size of the metal particles is preferably greater than 200 nm and less than 1600 nm, more preferably greater than 200 nm and less than 1200 nm, further preferably greater than 250 nm and less than 500 nm, and even more preferably greater than 300 nm and less than 500 nm.

[0073] When the electromagnetic wave absorbed by the photoelectric conversion unit is other than visible light, the average particle size is preferably 1 / 4 times or more and 2 times or less of the wavelength of the electromagnetic wave, more preferably 1 / 3 times or more and 1.8 times or less, further preferably 2 / 5 times or more and 1.7 times or less, and further preferably 1 / 2 times or more and 1.5 times or less. Specifically, when the electromagnetic wave is in the near-infrared region, the average particle size is preferably 200 nm or more and 5000 nm or less, more preferably 260 nm or more and 4500 nm or less, further preferably 312 nm or more and 4250 nm or less, and further preferably 340 nm or more and 3750 nm or less. In addition, when the electromagnetic wave is in the terahertz wavelength band, the average particle size is preferably 7500 nm or more and 600 μm or less, more preferably 10 μm or more and 540 μm or less, further preferably 12 μm or more and 510 μm or less, and further preferably 15 μm or more and 450 μm or less.

[0074] The average particle size of the plurality of metal-based particles is the average particle size of the 10 selected metal-based particles obtained by randomly selecting 10 metal-based particles from a SEM image of a metal-based particle aggregate formed from the plurality of metal-based particles, drawing five tangent diameters at random within each metal-based particle image (wherein each of the tangent diameters passes solely through the interior of the metal-based particle image, with one of the tangent diameters being the longest straight line drawn solely through the interior of the metal-based particle), and setting the average of these five tangent diameters (hereinafter referred to as the "tangent diameter average") as the particle size of each metal-based particle. The tangent diameter is defined as the perpendicular line connecting the distance between two parallel lines that connect the contour (projected image) of the metal-based particle (Nikkan Kogyo Shimbun, "Particle Measurement Technology," 1994, p. 5).

[0075] If the method for measuring the average particle size is described in more detail, first, a scanning electron microscope "JSM-5500" manufactured by JEOL Ltd. or an equivalent device is used to measure the SEM observation image. Then, the free image processing software "ImageJ" manufactured by the National Institutes of Health of the United States is used to read the obtained observation image with a horizontal resolution of 1280 pixels and a vertical resolution of 960 pixels. Then, the random number generation function "RANDBETWEEN" of the spreadsheet software "Excel" manufactured by Microsoft Corporation is used to obtain 10 random numbers (x1, x2, x3, x4, x5, x6, x7, x8, x9, x10, x110, x120, x130, x140, x150, x160, x170, x180, x190, x200, x210, x220, x230, x240, x250, x260, x270, x280, x290, x30 ... 10 ), get 10 random numbers (y1, y2, y3, y4, y5, y6, y7, y8, y9, y 10). From the 10 random numbers obtained, 10 groups of random number combinations (x1, y1), (x2, y2), (x3, y3), (x4, y4), (x5, y5), (x6, y6), (x7, y7), (x8, y8), (x9, y9) and (x 10 ,y 10 ). Set the value of the random number generated from 1 to 1280 as the x coordinate, and the value of the random number generated from 1 to 960 as the y coordinate, and obtain 10 sets of coordinate points (x1, y1), (x2, y2), (x3, y3), (x4, y4), (x5, y5), (x6, y6), (x7, y7), (x8, y8), (x9, y9) and (x1, y1). 10 ,y 10 Next, the above-mentioned tangent diameter average value is obtained for each of the 10 metal-based particle images containing the coordinate point, and then the average particle size is obtained as the average of the 10 tangent diameter average values. If at least one of the 10 coordinate points in the 10 random number combinations is not included in the metal-based particle image, or if two or more coordinate points are included in the same metal-based particle, the random number combination is discarded, and random numbers are repeatedly generated until all 10 coordinate points are included in different metal-based particle images.

[0076] In the metal-based particle aggregate, the plurality of metal-based particles are preferably arranged in such a manner that the average distance between the metal-based particles adjacent thereto (the average inter-particle distance) is 1 nm or more and 25 μm or less, more preferably 1 nm or more and 15 μm or less, further preferably 1 nm or more and 10 μm or less, and may also be 5 μm or less, 3 μm or less, 1 μm or less, 500 nm or less, 200 nm or less, 100 nm or less, 50 nm or less, or 30 nm or less. In particular, when the electromagnetic wave absorbed by the photoelectric conversion unit is visible light, it is preferably arranged in such a manner that the average inter-particle distance is 1 nm or more and 1000 nm or less, more preferably 1 nm or more and 500 nm or less, further preferably 1 nm or more and 250 nm or less. By arranging a plurality of metal-based particles at such an average inter-particle distance, it is advantageous in terms of exhibiting effects such as strong plasmon resonance and extending the range of action of plasmon resonance.

[0077] In particular, when the electromagnetic wave absorbed by the photoelectric conversion unit is visible light, from the perspective of effectively achieving the effects of [a] and [b] above, the average inter-particle distance is more preferably 1 nm to 150 nm, further preferably 1 nm to 60 nm, even more preferably 1 nm to 50 nm, particularly preferably 1 nm to 30 nm, and most preferably 1 nm to 20 nm. If the average inter-particle distance is less than 1 nm, electron transfer based on the Dexter mechanism occurs between particles, which is disadvantageous in terms of deactivation of localized plasmons.

[0078] When the electromagnetic wave is in the near-infrared region, the average inter-particle distance is preferably 1 nm to 250 nm, more preferably 1 nm to 225 nm, even more preferably 1 nm to 200 nm, and even more preferably 1 nm to 100 nm. Furthermore, when the electromagnetic wave is in the terahertz wavelength band, the average inter-particle distance is preferably 1 nm to 25 μm, more preferably 1 nm to 15 μm, and even more preferably 1 nm to 10 μm.

[0079] The average inter-particle distance is the average value of the inter-particle distances of 10 randomly selected metal-based particles in a SEM observation image of a metal-based particle aggregate composed of multiple metal-based particles, when the inter-particle distance between each selected metal-based particle and the adjacent metal-based particle is determined. The inter-particle distance to the adjacent metal-based particle is the value obtained by measuring the distances to all adjacent metal-based particles (the minimum distance between the surfaces of adjacent metal-based particles) and averaging these distances.

[0080] If the method for measuring the average inter-particle distance is described in more detail, first, a scanning electron microscope "JSM-5500" manufactured by JEOL Ltd. or an equivalent device is used to measure the SEM observation image. Then, the free image processing software "ImageJ" manufactured by the National Institutes of Health of the United States is used to read the obtained observation image with a horizontal resolution of 1280 pixels and a vertical resolution of 960 pixels. Then, the random number generation function "RANDBETWEEN" of the spreadsheet software "Excel" manufactured by Microsoft Corporation is used to obtain 10 random numbers (x1 to x2) from 1 to 1280 respectively. 10 ), get 10 random numbers (y1~y 10 ). 10 groups of random number combinations (x1, y1) to (x1, y1) are obtained from each of the 10 random numbers obtained. 10 ,y 10). Set the value of the random number generated from 1 to 1280 as the x coordinate, and the value of the random number generated from 1 to 960 as the y coordinate, and obtain 10 sets of coordinate points (x1, y1) to (x 10 ,y 10 Next, for a total of 10 metal-based particle images containing the coordinate point, the inter-particle distance between the metal-based particle and adjacent metal-based particles is obtained, and then the average inter-particle distance is obtained as the average of the 10 inter-particle distances with adjacent metal-based particles. If at least one of the 10 coordinate points in the 10 random number combinations is not included in the metal-based particle image, or if two or more coordinate points are included in the same metal-based particle, the random number combination is discarded, and random numbers are repeatedly generated until all 10 coordinate points are included in different metal-based particle images.

[0081] In particular, when the electromagnetic wave absorbed by the photoelectric conversion unit is visible light, in order to effectively achieve the effects of [a] and [b] above, the plurality of metal-based particles in the metal-based particle aggregate are preferably arranged so that the standard deviation of the average inter-particle distance is 25 nm or less. In order to effectively achieve the effects of [a] and [b] above, the standard deviation of the average inter-particle distance is more preferably 20 nm or less, and is preferably 0.1 nm or more, more preferably 0.2 nm or more, and even more preferably 0.3 nm or more.

[0082] When the electromagnetic wave is in the near-infrared region, the standard deviation of the average interparticle distance is preferably 50 nm or less. Furthermore, when the electromagnetic wave is in the terahertz wavelength band, the standard deviation of the average interparticle distance is preferably 10 μm or less. In these cases, the standard deviation of the average interparticle distance is preferably 0.1 nm or more, more preferably 0.2 nm or more, and even more preferably 0.3 nm or more.

[0083] The standard deviation of the average interparticle distance is defined as follows. In the SEM observation image of the metal-based particle aggregate composed of a plurality of metal-based particles from directly above, first randomly select one metal-based particle, and for this metal-based particle, find the interparticle distance with the adjacent metal-based particle. The interparticle distance with adjacent metal-based particles refers to the value obtained by measuring all the distances to adjacent metal-based particles (the minimum distance between the surfaces) and averaging these. In the above-mentioned SEM observation image, 9 metal-based particles different from the above-mentioned one are randomly selected, and for these 9 metal-based particles, the interparticle distance with the adjacent metal-based particles is found in the same manner as above. The standard deviation of the interparticle distance with adjacent metal-based particles for a total of 10 metal-based particles obtained in this way is defined as the standard deviation of the average interparticle distance.

[0084] If the method for measuring the standard deviation of the average inter-particle distance is specifically described, first, a scanning electron microscope "JSM-5500" manufactured by JEOL Ltd. or an equivalent device is used to measure the SEM observation image. Then, the free image processing software "ImageJ" manufactured by the National Institutes of Health of the United States is used to read the obtained observation image with a horizontal resolution of 1280 pixels and a vertical resolution of 960 pixels. Then, the random number generation function "RANDBETWEEN" of the spreadsheet software "Excel" manufactured by Microsoft Corporation is used to obtain 10 random numbers (x1 to x2) from 1 to 1280 respectively. 10 ), get 10 random numbers (y1~y 10 ). 10 groups of random number combinations (x1, y1) to (x1, y1) are obtained from each of the 10 random numbers obtained. 10 ,y 10 ). Set the value of the random number generated from 1 to 1280 as the x coordinate, and the value of the random number generated from 1 to 960 as the y coordinate, and obtain 10 sets of coordinate points (x1, y1) to (x 10 ,y 10 Next, for a total of 10 metal-based particle images containing the coordinate point, the interparticle distance between the metal-based particle and adjacent metal-based particles is obtained, and then the standard deviation of the average interparticle distance is obtained as the standard deviation of the 10 interparticle distances with adjacent metal-based particles. If at least one of the 10 coordinate points in the 10 random number combinations is not included in the metal-based particle image, or if two or more coordinate points are included in the same metal-based particle, the random number combination is discarded, and random numbers are repeatedly generated until all 10 coordinate points are included in different metal-based particle images.

[0085] From the perspective of effectively achieving the effects of [a] and [b] above, the average height of the plurality of metal-based particles constituting the metal-based particle aggregate is preferably 3.0 nm or more and 150 μm or less, more preferably 5.0 nm or more and 150 μm or less, further preferably 55 nm or more and 150 μm or less, and even more preferably 55 nm or more and 100 μm or less. It may also be 50 μm or less, 20 μm or less, 10 μm or less, 5 μm or less, 3 μm or less, 2 μm or less, or 1 μm or less. When the electromagnetic wave absorbed by the photoelectric conversion portion is visible light, the average height is preferably 3.0 nm or more and 500 nm or less, more preferably 5.0 nm or more and 500 nm or less, further preferably 55 nm or more and 500 nm or less, further preferably 55 nm or more and 300 nm or less, and particularly preferably 70 nm or more and 150 nm or less.

[0086] When the electromagnetic wave is in the near-infrared region, the average height is preferably 1250 nm or less. Furthermore, when the electromagnetic wave is in the terahertz wavelength band, the average height is preferably 150 μm or less.

[0087] The average height of the plurality of metal-based particles is the average value of 10 measured values obtained by randomly selecting 10 metal-based particles from an AFM observation image of the metal-based particle aggregate and measuring the heights of these 10 metal-based particles.

[0088] Regardless of the wavelength range of the electromagnetic waves absorbed by the photoelectric conversion unit, from the perspective of effectively achieving the effects of [a] and [b] above, the aspect ratio of the plurality of metal-based particles constituting the metal-based particle aggregate is preferably 1 or more and 8 or less, more preferably 2 or more and 8 or less, and even more preferably 2.5 or more and 8 or less. The aspect ratio is defined by the ratio of the average particle diameter to the average height (average particle diameter / average height). The metal-based particles may be spherical, but from the perspective of effectively achieving the effects of [a] and [b] above, they preferably have a flat shape with an aspect ratio greater than 1.

[0089] Regardless of the wavelength region of the electromagnetic waves absorbed by the photoelectric conversion unit, from the perspective of plasmon excitation with a high effect, the metal-based particles preferably have a surface containing a smooth curved surface, and particularly preferably have a flat shape with a surface containing a smooth curved surface. The surface may also contain some tiny bumps (roughness). In this sense, the metal-based particles may also be amorphous.

[0090] Regardless of the wavelength region of the electromagnetic wave absorbed by the photoelectric conversion unit, the number of metal-based particles contained in the metal-based particle aggregate is usually more than 10, preferably more than 30. By forming a metal-based particle aggregate containing more than 10 metal-based particles, it is easy to express strong plasmon resonance and extend the range of action of the plasmon resonance by utilizing the interaction between the localized plasmons of the metal-based particles. The number of metal-based particles contained in the metal-based particle aggregate can also be, for example, more than 50, more than 300, more than 500, more than 1,000 or more than 10,000. The number density of the metal-based particles in the metal-based particle aggregate is preferably 7 / μm 2 More than 15 / μm 2 above.

[0091] Regardless of the wavelength region of the electromagnetic waves absorbed by the photoelectric conversion unit, the metal-based particle aggregate preferably does not exhibit conductivity in the form of the aggregate, and more preferably, the metal-based particles constituting the metal-based particle aggregate are non-conductive with respect to the adjacent metal-based particles. In the metal-based particle aggregate, if there is a site capable of exchanging electrons between the metal-based particles, there is a tendency for the plasmon resonance effect to be reduced. Therefore, it is preferred that the metal-based particles are reliably separated and that no conductive material is intercalated between the metal-based particles. The metal-based particles themselves may also have conductivity.

[0092] The fact that the metal-based particle aggregates do not exhibit conductivity in the form of the aggregates can be confirmed, for example, by the following method: when a pair of testing machine probes of a multimeter [testing machine ("E2378A" manufactured by Hewlett-Packard Company)] are brought into contact with the metal-based particle aggregates at a distance of 10 mm to 15 mm, when the range is set to "30 MΩ", the resistance value under this measurement condition is greater than 30 MΩ, and the result indicates "overload".

[0093] (3) Method for producing metal-based particle aggregates

[0094] The metal-based particle aggregate can be produced, for example, by the following method.

[0095] [W] Method of pattern coating of metal raw material liquid using a template such as screen printing,

[0096] [X] A bottom-up method in which a plurality of metal-based particles are grown from tiny seeds on a substrate.

[0097] [Y] A method of covering a plurality of metal-based particles with a protective film containing an amphiphilic material having a predetermined thickness and then forming the protective film on a substrate using the Langmuir Blodgett (LB) film method,

[0098] [Z] Also, post-processing methods for thin films produced by vapor deposition or sputtering, such as resist processing, etching processing, and a casting method using a dispersion liquid in which metal-based particles are dispersed.

[0099] In the above method [X], it is preferred to include a step of growing metal-based particles at an extremely low rate on a substrate adjusted to a predetermined temperature (hereinafter also referred to as a "particle growth step"). According to the production method including this particle growth step, metal-based particle aggregates having the above-mentioned preferred average particle size, average height, aspect ratio, average inter-particle distance, and standard deviation of the average inter-particle distance can be obtained with good control.

[0100] During the particle growth step, the growth rate of the metallic particles on the substrate is preferably less than 1 nm / minute, and more preferably less than 0.5 nm / minute, as measured by the average height growth rate. The average height growth rate herein may also be referred to as the average deposition rate or the average thickness growth rate of the metallic particles, and is defined by the following formula:

[0101] Average height of metal-based particles / growth time of metal-based particles

[0102] The definition of "average height of metal-based particles" is as described above.

[0103] The metallic particle growth time refers to the time from the start to the end of metallic particle growth; specifically, it refers to the supply time of the metallic material. When metallic particle aggregates are obtained in the form of a film, the metallic particle growth time can also be referred to as the film formation time. When the metallic particle growth method is sputtering, the metallic particle growth time is the sputtering time.

[0104] The temperature of the substrate in the particle growth step is preferably 100°C to 450°C, more preferably 200°C to 450°C, further preferably 250°C to 350°C, and even more preferably 300°C or thereabouts (approximately 300°C±10°C).

[0105] By adjusting the average height growth rate, substrate temperature and / or metal-based particle growth time, the average inter-particle distance and its standard deviation, average particle size, average height, and aspect ratio of multiple metal-based particles grown on the substrate can be controlled.

[0106] The pressure (pressure within the equipment chamber) during the growth of the metal-based particles is not particularly limited as long as it is a pressure at which the particles can grow, and is generally less than atmospheric pressure. The lower limit of the pressure is not particularly limited, but is preferably 0.5 Pa or higher, more preferably 6 Pa or higher, and even more preferably 10 Pa or higher, from the perspective of easily adjusting the average height growth rate to within the above range.

[0107] The specific method for growing the metal-based particles on the substrate is not particularly limited as long as it is a method that can grow the particles at an average height growth rate of less than 1 nm / minute, and examples thereof include sputtering, vacuum evaporation, and other evaporation methods. Among sputtering methods, direct current (DC) sputtering is preferably used because it can relatively easily grow metal-based particle aggregates and can easily maintain an average height growth rate of less than 1 nm / minute.

[0108] The sputtering method is not particularly limited, and a DC argon ion sputtering method, in which argon ions generated by an ion gun or plasma discharge are accelerated in an electric field and irradiated onto a target, may be used. Other conditions in the sputtering method, such as the current value, voltage value, and substrate-target distance, are appropriately adjusted so that particles can grow at an average height growth rate of less than 1 nm / minute.

[0109] It should be noted that in order to obtain a metal-based particle aggregate having the above-mentioned preferred average particle size, average height, aspect ratio, average inter-particle distance and standard deviation of the average inter-particle distance under good control, it is preferred to set the average particle size growth rate to less than 5 nm / minute on the basis of setting the average height growth rate in the particle growth process to less than 1 nm / minute. However, when the average height growth rate is less than 1 nm / minute, the average particle size growth rate is usually less than 5 nm / minute. The average particle size growth rate is more preferably less than 1 nm / minute. The average particle size growth rate is defined by the following formula:

[0110] Average particle size of metal-based particles / growth time of metal-based particles.

[0111] The definitions of "average particle size of the metal-based particles" and "growth time of the metal-based particles" are as described above.

[0112] In order to obtain metal-based particle aggregates having the above-mentioned preferred average particle size, average height, aspect ratio, average inter-particle distance and standard deviation of the average inter-particle distance, it is preferred to consider the above-mentioned preferred manufacturing conditions and appropriately adjust the metal-based particle growth time in the particle growth process.

[0113] The substrate on which the metal-based particle aggregates are formed may be a component included in a solid-state imaging device. Examples of such components include a supporting substrate (e.g., a silicon substrate) that can be provided as the bottom layer of the solid-state imaging device, a multilayer wiring layer, a semiconductor substrate on which a photoelectric conversion unit is formed, an insulating layer, and a passivation layer.

[0114] (4) Covering layer

[0115] The solid-state imaging element may also include a covering layer covering the metal-based particle aggregates. By having a covering layer, the surface of the metal-based particle aggregates can be protected. In addition, having a covering layer comprising an insulating material is also advantageous in ensuring the non-conductivity of the metal-based particle aggregates. In a solid-state imaging element having metal-based particle aggregates and a covering layer, the stacking order of the photoelectric conversion unit, the metal-based particle aggregates, and the covering layer is not particularly limited. The metal-based particle aggregates, the covering layer, and the photoelectric conversion unit may be stacked in this order, or the photoelectric conversion unit, the metal-based particle aggregates, and the covering layer may be stacked in this order.

[0116] Figure 2This is a cross-sectional view schematically showing an example of a metal-based particle assembly covered with a coating layer. Figure 2 The laminate shown includes a substrate 10, a metal-based particle aggregate 20 disposed on the surface of the substrate 10, and a coating layer 30 disposed on the metal-based particle aggregate 20. Figure 2 In the example shown, the covering layer 30 is disposed on the side opposite to the substrate 10 relative to the metal-based particle aggregate 20 and covers the entire surface of the metal-based particle aggregate 20 on the side opposite to the substrate 10. Therefore, from the perspective of protecting the metal-based particle aggregate 20, etc., the covering layer 30 is preferably disposed so as to cover the entire surface of the metal-based particle aggregate 20 on the side opposite to the substrate 10. Furthermore, the covering layer 30 is preferably formed so as to fill the gaps between the metal-based particles 21.

[0117] The material constituting the cover layer is preferably one having good insulating properties, and examples thereof include spin-on glass (SOG; for example, one containing an organic siloxane material), SiO 2 , Si 3 N 4 , TiO 2 , and Al 2 O 3 .

[0118] In a preferred embodiment, the covering layer is a silicon-atom-containing layer having a first surface, and the signal intensity of carbon atoms on the first surface measured by X-ray photoelectron spectroscopy is less than 20.0 atomic % (hereinafter, the silicon-atom-containing layer is also referred to as "silicon-atom-containing layer (S)"). The first surface mentioned here refers to at least a portion of the surface that defines the outer edge of the silicon-atom-containing layer (S), and in the stack including the substrate 10, it is preferably at least a portion of the surface on the side opposite to the substrate 10. Figure 2 In the illustrated laminate, the surface of the cover layer 30 opposite to the substrate 10 is the first surface 31 , and the entire surface of the laminate opposite to the substrate 10 is constituted by the first surface.

[0119] The silicon-atom-containing layer (S) has excellent heat resistance and oxidation resistance. Therefore, by pre-coating the metal-based particle aggregates with the silicon-atom-containing layer (S), even when the manufacturing process of the solid-state imaging element containing the metal-based particle aggregates includes a high-temperature process, it is possible to manufacture the solid-state imaging element containing the metal-based particle aggregates without reducing the performance of the metal-based particle aggregates (the effect of enhancing the electromagnetic wave absorption efficiency). Examples of high-temperature processes include the process of forming a photoelectric conversion unit such as a photodiode (PD).

[0120] From the viewpoint of improving heat resistance, the signal intensity of the carbon atoms is preferably 18 atomic % or less, more preferably 15 atomic % or less, further preferably 12 atomic % or less, and even more preferably 10 atomic % or less.

[0121] The signal intensity of the carbon atoms is preferably 0.2 atomic % or more, more preferably 0.5 atomic % or more, further preferably 1 atomic % or more, and may be 5 atomic % or more. In the case of forming a silicon-containing atom layer (S) having too low a signal intensity of the carbon atoms, in terms of the selection of the formation process, damage may be caused to the metal-based particle aggregates during the formation process. Specifically, for example, there is a concern that the following process has to be adopted, which requires oxygen introduction and heating at a level that may cause damage to the metal-based particle aggregates. In addition, in the case of forming a silicon-containing atom layer (S) having too low a signal intensity of the carbon atoms, a composition having a higher signal intensity of carbon atoms can be used as the following silicon-containing atom layer-forming composition. By using such a composition to form a silicon-containing atom layer (S), the coating properties of the composition and the formation efficiency of the silicon-containing atom layer (S) can be improved, and the smoothness of the surface (first surface) of the silicon-containing atom layer (S) can be improved.

[0122] The signal intensity of the carbon atoms on the first surface can be measured using X-ray photoelectron spectroscopy using the following equipment and according to the following measurement conditions. In X-ray photoelectron spectroscopy, the signal intensity of each atom including carbon atoms is defined as the ratio (%) of the area of the signal of each atom possessed by the spectrum obtained using X-ray photoelectron spectroscopy to the total area of all signals. The ratio (%) of the area of the signal of each atom described above is measured at any three locations on the first surface, and the average of these measured values is used as the intensity of the atomic signal.

[0123] (Equipment and measurement conditions)

[0124] Equipment: K-Alpha X-ray Photoelectron Spectroscopy System, manufactured by Thermo Fisher Scientific

[0125] ·Measurement range: 400×800mm ·Measured elements (accumulated times): O(4), C(4), Si(4)

[0126] Dwell time: 50ms

[0127] Neutralizing electron gun: Yes

[0128] GCIB: Yes (for removing surface contamination)

[0129] The silicon-containing atom layer (S) may contain, in addition to silicon (Si) and carbon (C) atoms, oxygen (O) atoms, nitrogen (N) atoms, etc. as atoms that can be identified by X-ray photoelectron spectroscopy. Specific constituent materials of the silicon-containing atom layer include, for example, Si a O b C c 、Si d N eC f 、Si g O h N i C j 、Si k O l 、Si m N n 、Si o O p N q etc., preferably Si a O b C c 、Si d N e C f 、Si g O h N i C j a to q represent the composition ratio of each atom in each compound. The silicon atom-containing layer (S) may be composed of two or more materials and may have a single layer structure or a multilayer structure containing different materials.

[0130] The silicon-atom-containing layer (S) is preferably an amorphous layer. The following manufacturing method can make the silicon-atom-containing layer (S) an amorphous layer, even though it includes a heat treatment step at a relatively high temperature. The silicon-atom-containing layer (S) being an amorphous layer is advantageous in that a material that can be applied to a coating process can be selected as the raw material for the silicon-atom-containing layer (S), and industrially, high productivity can be achieved.

[0131] Whether the silicon-atom-containing layer (S) is an amorphous layer can be confirmed by obtaining an XRD spectrum of the first surface using the following equipment and the following measurement conditions by X-ray diffraction. Specifically, the silicon-atom-containing layer (S) can be determined to be an amorphous layer based on the absence of a peak having a full width at half maximum (FWHM) of 5° or less derived from crystals within the range of 2θ = 5° to 85° (preferably, the range of 0° to 90°).

[0132] (Equipment and measurement conditions)

[0133] Equipment: SmartLab manufactured by Rigaku

[0134] ·Measurement method: θ / 2θ measurement method

[0135] Measuring range: 2θ = 5° to 90°

[0136] Tube voltage: 45kV

[0137] Tube current: 200mA

[0138] The average thickness of the silicon-containing atom layer (S) is generally more than 10nm and less than 300nm, preferably more than 15nm and less than 250nm, more preferably more than 20nm and less than 200nm. The average thickness of the silicon-containing atom layer (S) can also be more than 30nm, more than 40nm, more than 50nm, more than 55nm or more than 60nm. By making the average thickness of the silicon-containing atom layer (S) be above-mentioned range, the function of protecting the metal-based particle aggregate and the function of improving the heat resistance of the metal-based particle aggregate can be fully given, in addition, the surface unevenness of the metal-based particle aggregate can be flattened. The above-mentioned record relevant to the average thickness can also be applied to the covering layer containing the silicon-containing atom layer (S).

[0139] The silicon-atom-containing layer (S) preferably has an average thickness within the above range and has a thickness that covers the entire surface of the metal-based particle aggregate on the opposite side of the substrate. The silicon-atom-containing layer (S) covers the entire surface of the metal-based particle aggregate on the opposite side of the substrate by obtaining a surface image using a scanning electron microscope "JSM-5500" manufactured by JEOL Ltd. or an equivalent device. Alternatively, it can be confirmed as follows: the surface on the opposite side of the substrate is measured using X-ray photoelectron spectroscopy in the same manner as the signal intensity of the carbon atoms on the first surface, and the signal intensity of the metal atoms constituting the metal-based particles is less than 1 atomic % (preferably less than the detection limit).

[0140] The average thickness of the silicon atom-containing layer (S) is the average value of the thicknesses measured at any 10 points of the silicon atom-containing layer. The thickness of the silicon atom-containing layer can be measured by height difference measurement using an AFM or cross-sectional observation using an SEM. In the case where the surface on which the silicon atom-containing layer (S) is formed is uneven, the thickness can also be measured at any 10 points of the silicon atom-containing layer by observing an SEM cross-sectional image, and the average value thereof is set as the average thickness of the silicon atom-containing layer (S).

[0141] The silicon atom-containing layer (S) is preferably a wet coating layer. The wet coating layer refers to a layer formed by applying a coating liquid (the following silicon atom-containing layer forming composition). The silicon atom-containing layer (S) is a wet coating layer, which is advantageous in that the surface (the first surface) of the silicon atom-containing layer (S) is smooth. By making the silicon atom-containing layer (S) a wet coating layer, it is easy to obtain a silicon atom-containing layer (S) having a small roughness of the surface (the first surface). If the surface roughness of the silicon atom-containing layer (S) is small, then when subsequent processing such as coating is applied to the surface, it is easy to improve the processing uniformity of the subsequent processing, and in addition, it is easy to reduce the failures caused by the generation of defects accompanying the subsequent processing.

[0142] It should be noted that the silicon atom-containing layer (S) can also be formed by vapor deposition, sputtering, CVD, etc. In this case, the obtained silicon atom-containing layer (S) is likely to become a layer having surface unevenness (large surface roughness) following the surface unevenness of the metal-based particle aggregate. In addition, it is likely to become a crystalline silicon atom-containing layer (S).

[0143] The surface (first surface) of the silicon atom-containing layer (S) has an arithmetic mean roughness Ra of preferably 10 nm or less, more preferably 8 nm or less, even more preferably 5 nm or less, still more preferably 3 nm or less, and particularly preferably 2 nm or less, as measured in accordance with JIS B 0601:2001. Ra may also be 0.1 nm or more.

[0144] The silicon atom-containing layer (S) can be formed by a method comprising the steps of: coating a composition for forming a silicon atom-containing layer on a substrate having metal-based particle aggregates formed thereon to form a coating layer; and heat-treating the coating layer at a temperature of 300° C. to 800° C. Examples of methods for coating the composition for forming a silicon atom-containing layer include spin coating, slit coating, and slit and spin coating.

[0145] The composition for forming a silicon-containing atom layer contains a substance (a silicon-containing atom layer-forming component) that can form a silicon-containing atom layer comprising, for example, the materials exemplified above, by heat-treating the coating layer. Examples of such substances include spin-on-glass (SOG), polysilazane, tetraethyl orthosilicate (TEOS), and methyltrimethoxysilane (MTMS). Spin-on-glass (SOG) has a siloxane structure, and examples thereof include silica glass, alkylsiloxane polymers, alkylsilsesquioxane polymers, hydrogenated silsesquioxane polymers, and hydrogenated alkylsilsesquioxane polymers.

[0146] In particular, from the perspective of forming a silicon-atom-containing layer with a carbon atom signal intensity exceeding the preferred lower limit, the composition for forming a silicon-atom-containing layer preferably includes a silicon-atom-containing layer-forming component having carbon atoms, such as an organic SOG having an organic group or an organic structure. Examples of the organic SOG include SOG having a methyl group or an ethyl group. The use of an organic SOG can also improve the coating properties of the composition for forming a silicon-atom-containing layer.

[0147] The composition for forming a silicon-atom-containing layer may further contain a solvent, a reaction catalyst, water, a surfactant, and the like in addition to the silicon-atom-containing layer-forming components.

[0148] After forming the coating layer, a process of heat treating the coating layer at a temperature of 300°C to 800°C is implemented. The temperature of the heat treatment is preferably 350°C to 700°C, more preferably 400°C to 650°C, further preferably 450°C to 600°C, and particularly preferably 500°C to 600°C. If the heat treatment temperature is too low, when a silicon-containing atom layer having carbon atoms is used to form a component, the signal intensity of the carbon atoms of the silicon-containing atom layer (S) is likely to be greater than the preferred range, and in this case, the heat resistance is reduced. If the heat treatment temperature is too high, there is concern that the metal-based particle aggregates may be damaged.

[0149] The time of heat treatment is, for example, more than 1 minute and less than 720 minutes, preferably more than 2 minutes and less than 480 minutes, more preferably more than 2 minutes and less than 240 minutes. Heat treatment can be carried out in air or inert gas (such as nitrogen, argon) atmosphere. The pressure of heat treatment can be normal pressure. Alternatively, heat treatment can also be carried out in a vacuum atmosphere.

[0150] Hereinafter, several embodiments are illustrated for a solid-state imaging element having a metal-based particle aggregate. The solid-state imaging element of the embodiment shown below may be, for example, a CMOS solid-state imaging element, or a CCD solid-state imaging element, preferably a CMOS solid-state imaging element. The solid-state imaging element of the embodiment shown below may or may not have a wavelength selective absorption layer, unless otherwise specified, regardless of whether it is illustrated. The wavelength selective absorption layer is usually provided when the electromagnetic wave subjected to photoelectric conversion is in the visible light region, and the absorption wavelength light (red light, green light, blue light, near-infrared light, etc.) of the wavelength selective absorption layer is selected according to the wavelength of the electromagnetic wave to be photoelectrically converted. In addition, the metal-based particle aggregate possessed by the solid-state imaging element of the embodiment shown below is preferably appropriately selected in shape and material according to the wavelength of the electromagnetic wave received by the photoelectric conversion portion (photodiode) provided with the metal-based particle aggregate.

[0151] (5) First embodiment of solid-state imaging element

[0152] Figure 3 It is a cross-sectional view schematically showing a pixel included in the solid-state imaging element according to the first embodiment. Figure 3The illustrated pixel includes an on-chip lens 100, a wavelength-selective absorption layer 101, a multilayer wiring layer 102, a semiconductor substrate 103 (photoelectric conversion unit), a metal-based particle assembly 20, a cover layer 30 covering the metal-based particle assembly, and a support substrate 104. The solid-state imaging element of this embodiment is a front-illuminated image sensor that includes, in this order, the on-chip lens 100, the multilayer wiring layer 102, the semiconductor substrate 103 (photoelectric conversion unit), the cover layer 30, and the metal-based particle assembly 20.

[0153] The multilayer wiring layer 102 includes a plurality of wiring layers 102b and an interlayer insulating film 102a. A plurality of pixel transistors for reading out charges accumulated in the photodiodes PD are also formed in the multilayer wiring layer 102.

[0154] The semiconductor substrate 103 is a semiconductor substrate having a semiconductor region forming a photoelectric conversion unit or a component constituting a pixel circuit. The semiconductor substrate 103 can be made of silicon (Si), for example. In the semiconductor substrate 103, for example, a P-type (first conductivity type) first semiconductor region 103a is formed, and an N-type (second conductivity type) second semiconductor region 103b is formed in each pixel, thereby forming a photodiode PD as a photoelectric conversion unit in the pixel unit. If electromagnetic waves such as light are irradiated on the second semiconductor region 103b, photoelectric conversion occurs. The charge generated by this photoelectric conversion is stored in the second semiconductor region 103b. Based on this stored charge, an image signal is generated by a pixel circuit (not shown).

[0155] The metal-based particle aggregate 20 is arranged near the photoelectric conversion unit (when the electromagnetic wave incident surface side (on-chip lens 100 side) is set to the top, it is the lower part of the photoelectric conversion unit), and can function as a component that enhances the electromagnetic wave absorption efficiency in the photoelectric conversion unit. This can solve the problem of reduced sensitivity caused by the reduction in the amount of light received by each pixel as the pixel size is reduced, and the sensitivity of each pixel can be improved. Or it can maintain sensitivity and realize the thin filmization of the photoelectric conversion unit in each pixel. The metal-based particle aggregate 20 is preferably a plasmon structure, more preferably satisfies any one of the structural characteristics selected from [A] and [B] above, and further preferably satisfies both of [A] and [B] above.

[0156] The metal-based particle aggregate 20 is well protected by being covered by the cover layer 30. For the reasons already mentioned, the cover layer 30 preferably comprises an insulating material, more preferably the aforementioned silicon atom-containing layer (S).

[0157] In the solid-state imaging element of this embodiment, it is preferred that the metal-based particle aggregate 20 is a plasmon structure and the cover layer 30 is a silicon-atom-containing layer (S). It is more preferred that the metal-based particle aggregate 20 satisfies any one of the structural characteristics selected from [A] and [B] above and the cover layer 30 is a silicon-atom-containing layer (S). It is further preferred that the metal-based particle aggregate 20 satisfies both [A] and [B] above and the cover layer 30 is a silicon-atom-containing layer (S). It should be noted that the solid-state imaging element of this embodiment includes an embodiment in which the metal-based particle aggregate 20 does not satisfy [A] and [B] above and the cover layer 30 is a silicon-atom-containing layer (S).

[0158] (6) Second embodiment of solid-state imaging element

[0159] Figure 4 It is a cross-sectional view schematically showing a pixel included in the solid-state imaging element according to the second embodiment. Figure 4 The illustrated pixel includes an on-chip lens 100, a wavelength-selective absorption layer 101, a semiconductor substrate 103 (photoelectric conversion unit), a metal-based particle assembly 20, a cover layer 30 covering the metal-based particle assembly, and a multilayer wiring layer 102. The solid-state imaging element of this embodiment is a back-illuminated image sensor that includes, in this order, the on-chip lens 100, the semiconductor substrate 103 (photoelectric conversion unit), the metal-based particle assembly 20, the cover layer 30, and the multilayer wiring layer 102. Regarding the semiconductor substrate 103 and the multilayer wiring layer 102, the description in the first embodiment is cited (unless otherwise specified, the same is also cited in the other embodiments shown below).

[0160] In this embodiment, the metal-based particle aggregate 20 is also positioned near the photoelectric conversion unit (directly below the photoelectric conversion unit when the electromagnetic wave incident surface (on-chip lens 100 side) is positioned upward), thereby functioning as a component that enhances the electromagnetic wave absorption efficiency of the photoelectric conversion unit. For the reasons already mentioned, the cover layer 30 preferably comprises an insulating material, more preferably the aforementioned silicon atom-containing layer (S).

[0161] In the solid-state imaging element of this embodiment, it is preferred that the metal-based particle aggregate 20 is a plasmon structure and the cover layer 30 is a silicon-atom-containing layer (S). It is more preferred that the metal-based particle aggregate 20 satisfies any one of the structural characteristics selected from [A] and [B] above and the cover layer 30 is a silicon-atom-containing layer (S). It is further preferred that the metal-based particle aggregate 20 satisfies both [A] and [B] above and the cover layer 30 is a silicon-atom-containing layer (S). It should be noted that the solid-state imaging element of this embodiment includes an embodiment in which the metal-based particle aggregate 20 does not satisfy [A] and [B] above and the cover layer 30 is a silicon-atom-containing layer (S).

[0162] (7) Third embodiment of solid-state imaging element

[0163] Figure 5 It is a cross-sectional view schematically showing a pixel included in the solid-state imaging element according to the third embodiment.

[0164] Figure 5 The illustrated pixel is a back-illuminated image sensor having the following configuration. This configuration is identical to the second embodiment, except that the metal-based particle aggregate 20 is disposed to the side of the second semiconductor region 103b (photodiode PD) instead of below the photoelectric conversion unit. In this embodiment, a configuration can be made without providing the cover layer 30 covering the metal-based particle aggregate 20. The description of the semiconductor substrate 103 and the multilayer wiring layer 102 is the same as that of the first embodiment.

[0165] From the perspective of more effectively enhancing electromagnetic wave absorption efficiency, the metal-based particle aggregates 20 are preferably arranged so as to contact the side surfaces of the second semiconductor region 103b (photodiode PD). This arrangement of the metal-based particle aggregates 20 can be achieved by forming a hole in the semiconductor substrate 103 to embed the second semiconductor region 103b, then forming the metal-based particle aggregates 20 on the side surfaces of the hole, and then forming the second semiconductor region 103b within the hole.

[0166] From the perspective of more effectively enhancing the electromagnetic wave absorption efficiency, the metal-based particle assembly 20 may be arranged on the side of the second semiconductor region 103 b (photodiode PD), or may be arranged below the photoelectric conversion unit as in the second embodiment.

[0167] An insulating layer 105 may be interposed between the semiconductor substrate 103 and the multilayer wiring layer 102. Alternatively, the insulating layer 105 may be omitted. Figure 5 The embodiment shown is a back-illuminated type, but the stacking order can be changed to a front-illuminated type.

[0168] In the solid-state imaging element of this embodiment, the metal-based particle aggregate 20 is preferably a plasmon structure, more preferably satisfies any one of the structural features selected from [A] and [B] above, and even more preferably satisfies both [A] and [B] above.

[0169] (8) Fourth embodiment of solid-state imaging element

[0170] Figure 6 It is a cross-sectional view schematically showing a pixel included in the solid-state imaging element according to the fourth embodiment. Figure 6The pixel shown has an anti-reflection portion 106, a pinning layer 107, and a light shielding portion 108 (groove structure). Solid-state imaging elements with such a structure are well known (for example, Japanese Patent Publication No. 2022-075774). The anti-reflection portion 106 has a moth-eye structure. This prevents reflection of incident light, thereby suppressing color mixing deterioration and improving sensitivity. The pinning layer 107 is formed of a high dielectric. The light shielding portion 108 prevents leakage of incident light from adjacent pixels.

[0171] The solid-state imaging element of this embodiment is a solid-state imaging element in which at least a portion of the pinning layer 107 that divides the light-shielding portion 108 in the conventional solid-state imaging element described above is replaced with a metal-based particle aggregate 20 (not shown), or a solid-state particle aggregate 20 is formed on the pinning layer 107. In this embodiment, the metal-based particle aggregate 20 is also arranged on the side of the photoelectric conversion portion, and can function as a component that enhances the electromagnetic wave absorption efficiency in the photoelectric conversion portion. In addition, it can have the effect of suppressing the above-mentioned deterioration of color mixing. The metal-based particle aggregate 20 is preferably a plasmon structure, more preferably satisfies any one of the structural features selected from [A] and [B] above, and further preferably satisfies both of [A] and [B] above. In this embodiment, a structure can be made in which the covering layer 30 covering the metal-based particle aggregate 20 is not provided.

[0172] In addition, a solid-state imaging element having a light-shielding wall that is inclined obliquely relative to the semiconductor substrate and separates the photoelectric conversion part is well known (for example, Japanese Patent Publication No. 2021-114538). The document records that the light-shielding wall is made of metals such as W or Al. By providing a light-shielding wall, the sensitivity reduction of the pixel can be suppressed. Another example of this embodiment is a solid-state imaging element having a light-shielding wall that separates the photoelectric conversion part, in which the light-shielding wall is formed by a metal-based particle aggregate 20. In this embodiment, the metal-based particle aggregate 20 is also arranged on the side of the photoelectric conversion part and can act as a component that enhances the electromagnetic wave absorption efficiency in the photoelectric conversion part. The metal-based particle aggregate 20 is preferably a plasma exciton structure, more preferably satisfies any one of the structural features selected from [A] and [B] above, and further preferably satisfies both of [A] and [B] above. In this embodiment, a structure in which a covering layer 30 covering the metal-based particle aggregate 20 is not provided can also be made.

[0173] (9) Fifth embodiment of solid-state imaging element

[0174] Figure 7 It is a cross-sectional view schematically showing a pixel included in the solid-state imaging element according to the fifth embodiment. Figure 7The pixel shown has a first reflective film 71, a second reflective film 72, a first scattering portion 73, a second scattering portion 74, a first reflective portion 75, a second reflective portion 76, and a third reflective portion 77. Solid-state imaging devices having such a structure are well known (e.g., Japanese Patent Application Laid-Open No. 2021-090022). Separation region 78 is a region that optically separates the pixels.

[0175] The first reflective film 71 reflects electromagnetic waves transmitted through the semiconductor substrate 103 toward the semiconductor substrate 103. The second reflective film 72, located on the back side of the semiconductor substrate 103, further reflects the light reflected from the first reflective film 71 toward the semiconductor substrate 103. The first scattering portion 73, a concave-convex structure located on the back side of the semiconductor substrate 103, scatters reflected light leaking from the opening 79, thereby returning it to the second semiconductor region 103b. The second scattering portion 74, a concave-convex structure located on the multilayer wiring layer 102, scatters light that reaches the second scattering portion 74, thereby returning it to the second semiconductor region 103b. The first reflective portion 75, the second reflective portion 76, and the third reflective portion 77, located within the second semiconductor region 103b, serve to increase the amount of electromagnetic waves that can return to the second semiconductor region 103b. Providing these reflecting and scattering mechanisms increases the amount of electromagnetic waves that contribute to photoelectric conversion, thereby improving the sensitivity of each pixel. It should be noted that part of the above-mentioned reflection and scattering mechanisms may be omitted.

[0176] The solid-state imaging element of this embodiment is a conventional solid-state imaging element described above, with a portion of its structure replaced by a metal-based particle aggregate 20 (not shown), or with a metal-based particle aggregate 20 attached. For example, the metal-based particle aggregate 20 may be disposed in place of the concavo-convex structure serving as the second scattering portion 74, on the concavo-convex structure serving as the second scattering portion 74, below the second scattering portion 74, or to the side of the second semiconductor region 103b. The metal-based particle aggregate 20 may be disposed in a combination of any of these configurations.

[0177] The metal-based particle aggregate 20 is preferably a plasmon structure, more preferably satisfies any one of the structural characteristics selected from [A] and [B] above, and even more preferably satisfies both [A] and [B]. In this embodiment, a configuration can be made without providing the covering layer 30 covering the metal-based particle aggregate 20.

[0178] (10) Sixth embodiment of solid-state imaging element

[0179] Figure 8 It is a cross-sectional view schematically showing a pixel included in the solid-state imaging element according to the sixth embodiment. Figure 8The pixel shown has a feature in that the structure of the metal-based particle aggregate 20 arranged near the photodiode PD of each pixel is different according to the wavelength of the electromagnetic wave received by each pixel, and the other structures are similar to the solid-state imaging element of the third embodiment. Figure 8 In the embodiment, the metal-based particle aggregates 20 are arranged on the side and below the second semiconductor region 103b (photodiode PD), or the metal-based particle aggregates 20 may be arranged only on one of them. Figure 8 The embodiment shown is a back-illuminated type, but the stacking order can also be changed to a front-illuminated type. The metal-based particle assembly 20 is preferably a plasmon structure, more preferably satisfies any one of the structural characteristics selected from [A] and [B] above, and even more preferably satisfies both [A] and [B] above.

[0180] exist Figure 8 2 pixels are shown in FIG. 2 . In this embodiment, the two pixels receive electromagnetic waves of different wavelengths. There is no particular limitation on the combination of different wavelengths, and examples thereof include visible light (R, G, B) and near infrared light.

[0181] Examples of the configuration of the metal-based particle aggregates 20 that can be differentiated include the material of the metal-based particles, the average particle size, the average height, the aspect ratio, the average inter-particle distance, and the number of metal-based particles constituting the metal-based particle aggregates 20. The metal-based particle aggregates 20 provided for each pixel preferably have a configuration that effectively improves the absorption efficiency of electromagnetic waves received by each pixel.

[0182] (11) Seventh embodiment of solid-state imaging element

[0183] Figure 9 : is a cross-sectional view schematically showing a pixel included in the solid-state imaging element according to the seventh embodiment. Figure 9 The pixel shown has two photodiodes PD1 and PD2 of different sizes. The different sizes of the photodiodes PD1 and PD2 result in different receiving sensitivities. This type of solid-state imaging element is well known (for example, Japanese Patent Application Publication No. 2022-097519), and this configuration enables an expansion of the dynamic range.

[0184] exist Figure 9 In the illustrated embodiment, the photodiode PD1 is formed by the second semiconductor region 103b, and the photodiode PD2 is formed by the third semiconductor region 103c. The photodiodes PD1 and PD2 may have different thicknesses and widths.

[0185] exist Figure 9In the embodiment, the metal-based particle aggregate 20 is arranged below the photodiodes PD1 and PD2, and the metal-based particle aggregate 20 may be arranged on the side and below. Figure 9 The embodiment shown is a front-side irradiation type, but the stacking order can also be changed to a back-side irradiation type. The metal-based particle aggregate 20 is preferably a plasmon structure, more preferably satisfies any one of the structural characteristics selected from [A] and [B] above, and even more preferably satisfies both [A] and [B] above.

[0186] (12) Eighth embodiment of solid-state imaging element

[0187] Figure 10 It is a cross-sectional view schematically showing a pixel included in the solid-state imaging element according to the eighth embodiment. Figure 10 The pixel shown does not make the receiving sensitivities different by making the sizes of the two photodiodes PD1 and PD2 different from each other as in the seventh embodiment, but makes the receiving sensitivities of the two photodiodes different by utilizing the metal-based particle aggregate 20. That is, the number of metal-based particles constituting the metal-based particle aggregate 20 provided for the photodiode PD1 is made different from the number of metal-based particles constituting the metal-based particle aggregate 20 provided for the photodiode PD2, thereby making the receiving sensitivities of the two photodiodes different. This configuration can expand the dynamic range. As Figure 10 As shown in the example of , a configuration may be adopted in which the metal-based particle assembly 20 is provided for only one of the photodiodes PD1 and PD2 and the metal-based particle assembly 20 is not provided for the other.

[0188] exist Figure 10 In the embodiment, the metal-based particle aggregate 20 is arranged below the photodiode, and the metal-based particle aggregate 20 may be arranged on the side and below. Figure 10 The embodiment shown is a front-side irradiation type, but the stacking order can also be changed to a back-side irradiation type. The metal-based particle aggregate 20 is preferably a plasmon structure, more preferably satisfies any one of the structural characteristics selected from [A] and [B] above, and even more preferably satisfies both [A] and [B] above.

[0189] (13) Ninth embodiment of solid-state imaging element

[0190] Figure 11 It is a cross-sectional view schematically showing a pixel included in the solid-state imaging element according to the ninth embodiment. Figure 11The pixel shown is a pixel with an avalanche diode. This type of solid-state imaging element is well known (for example, Japanese Patent Application Publication No. 2018-064086). Through this configuration, it is possible to suppress noise and improve sensitivity. In this embodiment, a metal-based particle aggregate 20 is arranged below the avalanche structure 109. This can further improve sensitivity. A covering layer 30 covering the metal-based particle aggregate 20 may also be provided.

[0191] The metal-based particle aggregate 20 may also be arranged on the side, or on the side and below the avalanche structure 109. The metal-based particle aggregate 20 is preferably a plasmon structure, more preferably satisfies any one of the structural features selected from [A] and [B] above, and further preferably satisfies both [A] and [B] above. Figure 11 The embodiment shown is a back-illuminated type, but the stacking order can be changed to a front-illuminated type.

[0192] (14) Tenth embodiment of solid-state imaging element

[0193] Figure 12 It is a cross-sectional view schematically showing a pixel included in the solid-state imaging element according to the tenth embodiment. Figure 12 The pixel shown is characterized in that the photodiode PD comprises an organic material ( Figure 12 Solid-state imaging devices including photodiodes PD made of organic materials are conventionally known.

[0194] In this embodiment, the metallic particle aggregate 20 is also positioned near (directly below) the organic PD 200, thereby enhancing electromagnetic wave absorption efficiency. The metallic particle aggregate 20 is preferably a plasmon structure, more preferably meeting any one of the structural characteristics selected from [A] and [B] above, and even more preferably meeting both [A] and [B]. Figure 12 The embodiment has the covering layer 30, but a structure without the covering layer 30 may also be made. Figure 12 The embodiment shown is a back-illuminated type, but the stacking order can be changed to a front-illuminated type. In this embodiment, in which the photodiode PD is made of an organic material, the features of the solid-state imaging elements of the first to ninth embodiments can also be incorporated.

[0195] The wavelength of the electromagnetic wave received by the solid-state imaging element of this embodiment is not particularly limited, and may be visible light, near-infrared light, electromagnetic waves in the terahertz band, etc., but is preferably near-infrared light.

[0196] (15) Eleventh embodiment of solid-state imaging element

[0197] Figure 13It is a cross-sectional view schematically showing a pixel included in the solid-state imaging element according to the eleventh embodiment. Figure 13 The pixel shown is characterized by stacking multiple photodiodes PD in the thickness direction. This type of solid-state imaging element is well known (for example, Japanese Patent Application Publication No. 2021-073689 and Japanese Patent Application Publication No. 2017-174936), and this structure can achieve miniaturization of the component and improve sensitivity.

[0198] Figure 13 The embodiment shown has three photodiodes PD1 ( Figure 13 PD1 can be formed of an organic material. Photodiode PD2 is formed in the second semiconductor region 103b, and photodiode PD3 is formed in the third semiconductor region 103c. However, the materials of each photodiode are not limited to the above.

[0199] like Figure 13 As shown, when the electromagnetic wave incident surface side (on-chip lens 100 side) is positioned upward, the metal-based particle aggregate 20 can be positioned below (e.g., directly below) the lowest photodiode PD3, for example. Thus, the metal-based particle aggregate 20 can function as a component that enhances the electromagnetic wave absorption efficiency of each photodiode PD. The metal-based particle aggregate 20 is preferably a plasmon structure, more preferably satisfies any one of the structural characteristics selected from [A] and [B] above, and even more preferably satisfies both [A] and [B] above.

[0200] Generally speaking, the closer the distance between the metal-based particle aggregate 20 and the photodiode PD, the higher the electromagnetic wave absorption efficiency of the photodiode PD by the metal-based particle aggregate 20. Therefore, in a solid-state imaging element having a plurality of photodiodes PD stacked in the thickness direction, if the plurality of photodiodes PD are arranged so that the lower the sensitivity of the PD, the shorter the distance from the metal-based particle aggregate 20, the sensitivity of the entire component can be easily improved.

[0201] For example, the electromagnetic waves received by the photodiodes PD1 , PD2 , and PD3 may be green light, blue light, and red light, respectively.

[0202] (16) Twelfth embodiment of solid-state imaging element

[0203] Figure 14 This is a cross-sectional view schematically showing a pixel included in the solid-state imaging element according to the twelfth embodiment, and shows only the photodiode PD and its surroundings. Figure 14The pixel shown is the same as that of the eleventh embodiment, and has three photodiodes PD1 ( Figure 14 PD2, PD3, and PD1 are organic photodiodes. However, the number of photodiodes is not limited to three. PD1 can be formed of an organic material. Photodiode PD2 is formed in the second semiconductor region 103b, and photodiode PD3 is formed in the third semiconductor region 103c. However, the materials of each photodiode are not limited to those described above.

[0204] This embodiment is characterized by placing metal-based particle aggregates near each photodiode PD. The first metal-based particle aggregate 20a serves as an electromagnetic wave absorption efficiency enhancement component for PD1, the second metal-based particle aggregate 20b serves as an electromagnetic wave absorption efficiency enhancement component for PD2, and the third metal-based particle aggregate 20c serves as an electromagnetic wave absorption efficiency enhancement component for PD3. For example, the electromagnetic waves received by photodiodes PD1, PD2, and PD3 can be green, blue, and red light, respectively.

[0205] The first metal-based particle aggregate 20a, the second metal-based particle aggregate 20b, and the third metal-based particle aggregate 20c are preferably plasmon structures, more preferably satisfying any one of the structural features selected from the above [A] and [B], and further preferably satisfying both of the above [A] and [B].

[0206] like Figure 14 As shown, when each metal-based particle assembly is arranged below the corresponding photodiode PD, the first metal-based particle assembly 20a and the second metal-based particle assembly 20b are preferably transparent to a specific wavelength range. For example, when the electromagnetic waves received by the photodiodes PD1, PD2, and PD3 are green light, blue light, and red light, respectively, the first metal-based particle assembly 20a is preferably transparent to blue light and red light, so that PD2 and PD3 can receive blue light and red light, respectively. In addition, the second metal-based particle assembly 20b is preferably transparent to red light, so that PD3 can receive red light.

[0207] The wavelength region in which the metal-based particle aggregates can be transparent is not limited to the case where the electromagnetic waves received by each photodiode PD as described above are visible light. For example, if a metal-based particle aggregate that absorbs ultraviolet light and transmits near-infrared light is used, photoelectric conversion of near-infrared light can be performed in the photodiode PD arranged below the metal-based particle aggregate. In addition, if a metal-based particle aggregate that absorbs visible light and transmits electromagnetic waves in the terahertz band is used, photoelectric conversion of electromagnetic waves in the terahertz band can be performed in the photodiode PD arranged below the metal-based particle aggregate. Alternatively, the metal-based particle aggregate can also transmit visible light and absorb infrared light such as ultraviolet light and / or near-infrared light.

[0208] Examples of metal-based particle aggregates that transmit visible light and absorb infrared light such as ultraviolet light and / or near-infrared light include aggregates formed from metal-based particles containing at least one selected from the group consisting of transparent conductive oxides having a plasmon peak in the infrared region, copper sulfide, copper phosphide, copper telluride, copper selenide, ruthenium oxide, rhenium oxide, molybdenum oxide, tungsten oxide, tungsten bronze, and Delafossite-type copper oxide.

[0209] Examples of transparent conductive oxides having a plasmon peak in the infrared region include tin-doped indium oxide, aluminum-doped indium oxide, cerium-doped indium oxide, aluminum-doped zinc oxide, gallium-doped zinc oxide, indium-doped zinc oxide, indium-doped cadmium oxide, fluorine-doped indium cadmium oxide, fluorine-doped cadmium oxide, chlorine-doped cadmium oxide, bromine-doped cadmium oxide, cesium-doped molybdenum oxide, antimony-doped tin oxide, fluorine-doped tin oxide, and titanium oxide.

[0210] Electronic equipment

[0211] The electronic device of the present invention includes the solid-state imaging element of the present invention. The electronic device can be any electronic device with an imaging function, such as a mobile terminal such as a smartphone or mobile phone; a mobile object such as a vehicle; a digital camera, a video camera, a microscope, a fingerprint authentication device, and the like.

[0212] <Experimental Example>

[0213] (1) Experimental Example 1

[0214] (1-1) Preparation of Metal-Based Particle Aggregates

[0215] Reference Figure 15 Using a DC magnetron sputtering device, silver particles were grown extremely slowly on a support substrate 110 made of soda glass under the following conditions, forming a metallic particle aggregate 20 over the entire surface of the support substrate 110. This metallic particle aggregate is hereinafter referred to as "metallic particle aggregate A."

[0216] Using gas: Argon

[0217] Chamber pressure (sputtering gas pressure): 10Pa

[0218] Distance between support substrate and target: 100mm

[0219] Sputtering power: 4W

[0220] Average particle size growth rate (average particle size / sputtering time): 1.2 nm / min

[0221] Average height growth rate (= average deposition rate = average height / sputtering time): 0.28 nm / min Support substrate temperature: 300°C

[0222] Support substrate size and shape: square with a side length of 5 cm

[0223] The average particle size, average interparticle distance and its standard deviation, average height, and aspect ratio (average particle size / average height) of the silver particles constituting the metallic particle aggregate A, measured using the aforementioned method, are as follows. Measurements were made using a JEOL Ltd. scanning electron microscope "JSM-5500" to obtain SEM images, and AFM images (image size: 5 μm × 5 μm) were obtained using a KEYENCE Corporation "VN-8010" microscope.

[0224] Average particle size: 416nm

[0225] Average inter-particle distance: 10.9 nm

[0226] Standard deviation of the average interparticle distance: 1.67 nm

[0227] Average height: 102.0nm

[0228] Aspect ratio (average particle diameter / average height): 4.09

[0229] Furthermore, a tester [multimeter ("E2378A" manufactured by Hewlett-Packard Company)] was connected to the surface of the metal-based particle aggregate A on the support substrate 110 to check the electrical conductivity. As a result, it was confirmed that the surface had no electrical conductivity.

[0230] (1-2) Fabrication of Light Absorbing Element 1

[0231] Silver particles were grown under the same conditions as in (1-1) above, thereby forming a metallic particle aggregate A on a supporting substrate 110 comprising soda glass having a thickness of 1.0 mm. Immediately thereafter, an SOG solution was spin-coated on the metallic particle aggregate A and baked at 550° C. in the atmosphere, thereby laminating a covering layer 30 having an average thickness of 30 nm. The SOG solution used was obtained by diluting "OCD T-7 5500T" manufactured by Tokyo Ohka Kogyo Co., Ltd., which is an organic SOG material, with ethanol. The "average thickness" refers to the average thickness when formed on a metallic particle aggregate having surface irregularities, and is measured as the thickness when the SOG solution is directly spin-coated on the supporting substrate 110 (the same applies to the following experimental examples).

[0232] Next, a light-absorbing layer solution was spin-coated at 2500 rpm onto the outermost surface of the metallic particle aggregate A having the cover layer 30, forming a 25 nm-thick light-absorbing layer 120, thereby obtaining a light-absorbing element 1. The light-absorbing layer solution was a 1 mass % P3HT solution prepared by dissolving P3HT (poly(3-hexylthiophene-2,5-diyl) from Luminescence Technology Co., Ltd.) in chlorobenzene.

[0233] (2) Experimental Example 2

[0234] (2-1) Preparation of Metal-Based Particle Aggregates

[0235] A metal-based particle assembly 20 was formed on the entire surface of the support substrate 110 in the same manner as in Experimental Example 1, except that the sputtering time in the DC magnetron sputtering method was changed. This metal-based particle assembly is hereinafter referred to as "metal-based particle assembly B." Metal-based particle assembly B had substantially the same particle shape, aspect ratio, and average inter-particle distance as those of metal-based particle assembly A, except that the average height of the silver particles was approximately 5.0 nm.

[0236] (2-2) Fabrication of Light Absorbing Element 2

[0237] Silver particles were grown under the same conditions as in (2-1) above, thereby forming a metallic particle aggregate B on a supporting substrate 110 composed of 1.0 mm thick soda glass. Subsequently, the same light-absorbing layer solution as used in Experimental Example 1 was spin-coated at 2500 rpm on the metallic particle aggregate B to form a 25 nm thick light-absorbing layer 120, thereby obtaining a light-absorbing element 2. The light-absorbing element 2 did not include a cover layer 30.

[0238] (3) Experimental Example 3

[0239] (3-1) Preparation of Metal-Based Particle Aggregates

[0240] A metallic particle aggregate 20 was formed on the entire surface of the support substrate 110 in the same manner as in Experimental Example 1, except that the sputtering time in the DC magnetron sputtering method was changed. This metallic particle aggregate is hereinafter referred to as "metallic particle aggregate C." Metallic particle aggregate C had substantially the same particle shape, aspect ratio, and average inter-particle distance as metallic particle aggregate A, except that the average height of the silver particles was approximately 310.9 nm.

[0241] (3-2) Fabrication of Light Absorbing Element 3

[0242] Silver particles were grown under the same conditions as in (3-1) above, thereby forming a metallic particle aggregate C on a supporting substrate 110 made of 1.0 mm thick soda glass. Immediately thereafter, an SOG solution was spin-coated on the metallic particle aggregate C and calcined at 550° C. in the atmosphere.

[0243] In this manner, a cap layer 30 having an average thickness of 80 nm was deposited. As the SOG solution, "OCD T-7 5500T" manufactured by Tokyo Ohka Kogyo Co., Ltd., which is an organic SOG material, was diluted with ethanol.

[0244] Next, the same light absorbing layer solution as used in Experimental Example 1 was spin-coated at 2500 rpm on the outermost surface of the metal-based particle aggregate C having the cover layer 30 to form a light absorbing layer 120 with a thickness of 25 nm, thereby obtaining a light absorbing element 3 .

[0245] (4) Experimental Example 4

[0246] A light absorbing element 4 was obtained in the same manner as in Experimental Example 3 except that the firing atmosphere was nitrogen and the firing temperature was 200°C.

[0247] [Evaluation of light absorption rate]

[0248] use Figure 16 The optical system is used to measure and evaluate the light absorption rate of the light absorbing element. The details are as follows. First, use Figure 16 Using an optical system, the SCI reflectance (%) of a measurement sample consisting of a light absorbing element 300 superimposed on a barium sulfate plate 301 was measured. The light source 303 attached to the integrating sphere 302 was the DH-2000-BAL from Ocean Optics. The detector 304 attached to the integrating sphere 302 was the MCPD-3000 from Otsuka Electronics Co., Ltd. The integrating sphere 302 was the ISP-REF from Ocean Photonics. Based on the SCI reflectance values obtained for each wavelength, the light absorption (%) of the light absorbing element at each wavelength was calculated using the following formula.

[0249] Light absorption rate of the light absorbing element at each wavelength (%) = 100 - SCI reflectivity at each wavelength

[0250] Table 1 shows the light absorptivity of light absorbing elements 1 to 4 at wavelengths of 550 nm, 690 nm, and 800 nm. Light absorbing elements 1, 3, and 4 were observed to have higher light absorptivity at wavelengths of 550 nm and 690 nm, corresponding to visible light wavelengths, than light absorbing element 2, with this tendency being particularly pronounced in light absorbing element 1. Furthermore, light absorbing elements 3 and 4 were observed to have higher light absorptivity at 800 nm, corresponding to near-infrared to infrared wavelengths, than light absorbing elements 1 and 2. Furthermore, light absorbing element 3, calcined at a temperature of 550°C, was observed to have higher light absorptivity at wavelengths of 550 nm, 690 nm, and 800 nm than light absorbing element 4, calcined at a temperature of 200°C.

[0251] [Table 1]

[0252]

[0253] Description of Reference Numerals

[0254] 10 substrate, 20 metal-based particle aggregate, 20a first metal-based particle aggregate, 20b second metal-based particle aggregate, 20c third metal-based particle aggregate, 21 metal-based particles, 30 covering layer, 31 first surface, 71 first reflecting film, 72 second reflecting film, 73 first scattering portion, 74 second scattering portion, 75 first reflecting portion, 76 second reflecting portion, 77 third reflecting portion, 78 separation region, 79 opening, 100 on-chip lens, 101 wavelength-selective absorption layer, 102 multilayer wiring layer, 102a interlayer insulating film, 102b wiring layer, 103 semiconductor substrate, 103a first semiconductor region, 103b second semiconductor region, 103c third semiconductor region, 104 supporting substrate, 105 insulating layer, 106 anti-reflection part, 107 pinning layer, 108 shading part, 109 avalanche structure, 110 supporting substrate, 120 light absorption layer, 200, 201 organic PD, 300 light absorption element, 301 barium sulfate plate, 302 integrating sphere, 303 light source, 304 detector.

Claims

1. A solid-state imaging element comprising a photoelectric conversion unit for performing photoelectric conversion, The solid-state imaging element includes a metal-based particle aggregate in which a plurality of metal-based particles are arranged separately from each other. In the metal-based particle aggregate, the plurality of metal-based particles are arranged such that an average distance between adjacent metal-based particles is 1 nm or more and 25 μm or less, and a standard deviation of the average distance is 10 μm or less.

2. A solid-state imaging element comprising a photoelectric conversion unit for performing photoelectric conversion, The solid-state imaging element includes a metal-based particle aggregate in which a plurality of metal-based particles are arranged separately from each other. The plurality of metal-based particles have an average particle size of 200 nm to 600 μm, an average height of 3.0 nm to 150 μm, and an aspect ratio defined as a ratio of the average particle size to the average height of 1 to 8. In the metal-based particle aggregate, the plurality of metal-based particles are arranged such that an average distance between adjacent metal-based particles is 1 nm or more and 25 μm or less.

3. The solid-state imaging element according to claim 1 or 2, wherein The metal-based particles contain a noble metal.

4. The solid-state imaging element according to claim 1 or 2, wherein The precious metal is silver or gold. 5 . The solid-state imaging element according to claim 1 , further comprising a covering layer covering the metal-based particle aggregate.

6. The solid-state imaging element according to claim 5, wherein The covering layer is a silicon-containing layer having a first surface, The signal intensity of carbon atoms on the first surface of the covering layer measured by X-ray photoelectron spectroscopy is 20.0 atomic % or less.

7. The solid-state imaging element according to claim 1 or 2, wherein The electromagnetic waves photoelectrically converted by the photoelectric conversion section include electromagnetic waves having a maximum wavelength of 200 nm to 3 mm. 8 . An electronic device comprising the solid-state imaging element according to claim 1 .

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