Optical detection device and electronic device

Abstract

An object of the present invention is to solve at least one of various problems of a 2PD type image sensor. There is provided a solid-state imaging device including a plurality of pixels, each of the plurality of pixels including a photoelectric conversion element formed on a silicon substrate. A part of the pixels is configured such that its photoelectric conversion elements are separated by a first type of separation region that extends in a flat plate shape in a direction along the thickness direction of the silicon substrate, and the other part of the pixels is configured such that its photoelectric conversion elements are separated by a second type of separation region formed of a material different from the first type of separation region, the second type of separation region extending in a flat plate shape in a direction along the thickness direction of the silicon substrate.

Description

[0001] This application is a divisional application of the patent application No. 201780061002.3, with the filing date of July 24, 2017 and the invention title of "Solid-state imaging element, method for manufacturing a solid-state imaging element, and electronic device". Technical Field

[0002] The present technology relates to a solid-state imaging element, a method for manufacturing a solid-state imaging element, and an electronic device. Background Art

[0003] There are roughly three types of autofocus (AF) methods for cameras: phase difference AF; contrast AF; and image plane phase difference AF. Image plane phase difference AF is the latest method and has been gradually developed in recent years. Since image plane phase difference AF has the function of a phase difference AF sensor incorporated in the pixels of the image sensor itself, image plane phase difference AF can achieve phase difference AF without the need for a separate lens and a phase difference AF sensor required for phase difference AF. In other words, similar to phase difference AF, image plane phase difference AF instantaneously measures the deviation amount of AF, so that the set lens can be focused very quickly.

[0004] Patent Document 1 discloses a light-shielding metal method, which is the mainstream of the pixel structure of image plane phase difference AF. In the light-shielding metal method, a plurality of pairs of pixels (pupil pixels) are provided, and in each pixel, approximately half is covered with a light-shielding metal so as to detect only the light passing through the exit pupil side of the set lens. The pupil pixels include: a first pixel including a first side of the pixel that is approximately half covered with a light-shielding metal; and a second pixel including a second side of the pixel that is approximately half covered with a light-shielding metal.

[0005] The first pixel and the second pixel are disposed at positions close to each other in the image sensor. Therefore, when the set lens is focused, the first received image obtained from the first pixel and the second received image obtained from the second pixel are the same. At the same time, when the set lens is not focused, an offset occurs between the first received image and the second received image, and the image switches between focusing on the near side and focusing on the far side. In this case, the focusing deviation of the set lens including the offset direction can be instantaneously measured.

[0006] Since the image plane phase difference pixels in the light-shielding metal method are defective pixels, and the output signals from the defective pixels cannot be used for image formation, there is a drawback that the image quality of the image sensor is lower than that of an image sensor that does not have image plane phase difference AF but has the same number of pixels.

[0007] As a solution to this drawback, for example, Patent Document 2 proposes the following method: in the case of two divided pixels formed by dividing a photodiode corresponding to an on-chip lens (hereinafter referred to as OCL: on-chip lens), ranging is performed using a first received image obtained from one divided pixel (first divided pixel) and a second received image obtained from the other divided pixel (second divided pixel), and the integration of the outputs of the two divided pixels generates the output of one pixel, which can be used for image formation (hereinafter referred to as the 2PD method). Needless to say, for example, Patent Document 3 proposes the concept of hybrid mounting of pixels dedicated to phase difference in the 2PD method and conventional pixels for image generation in the 1PD method.

[0008] Citation List

[0009] Patent Document

[0010] Patent Document 1: Japanese Patent Application Laid-Open No. 2012-182332

[0011] Patent Document 2: Japanese Patent Application Laid-Open No. 2001-250931

[0012] Patent Document 3: Japanese Patent Application Laid-Open No. 2015-65269 Summary of the Invention

[0013] Technical Problem to be Solved by the Present Technology

[0014] As described above, since the 2PD method allows dense layout of image plane phase difference pixels in addition to having no defective pixels, there is an advantage that the deviation of the center of gravity positions of the outputs of the first divided pixel and the second divided pixel can be accurately obtained, which can improve the AF accuracy.

[0015] At the same time, since the photodiode is divided into two, the overall volume of the photodiode is reduced by the separation part for pixel division, resulting in a drawback that the relative sensitivity is lower than that of an undivided pixel of the same OCL size (hereinafter referred to as the 1PD method). Note that as a method of separating phase difference pixels, metal implantation, oxide film implantation, and injection are known.

[0016] However, according to the prototype of the 2PD method image sensor actually manufactured by the present inventor, in addition to the reduction in the volume of the photodiode, various problems such as color mixing between divided pixels and occurrence of sensitivity loss in the separation part are also found.

[0017] In view of the above problems, the present technology is made, and the object of the present technology is to solve at least one of various problems of the 2PD method image sensor.

[0018] Solution to the technical problem

[0019] According to one aspect of the present technology, a solid-state imaging element is provided, which includes: a plurality of pixels, each of the plurality of pixels including a photoelectric conversion element formed on a silicon substrate, wherein a part of the plurality of pixels have the photoelectric conversion elements separated by a first-type separation region that extends in a flat plate shape in a direction along the thickness direction of the silicon substrate, and another part of the plurality of pixels have the photoelectric conversion elements separated by a second-type separation region formed of a material different from that of the first-type separation region, and the second-type separation region extends in a flat plate shape in the direction along the thickness direction of the silicon substrate.

[0020] According to another aspect of the present technology, a method for manufacturing a solid-state imaging element is provided, the solid-state imaging element including a plurality of pixels, each of the plurality of pixels including a photoelectric conversion element formed on a silicon substrate, the method including: a step of forming a first-type separation region that extends in a flat plate shape in a direction along the thickness direction of the silicon substrate, the first-type separation region separating the photoelectric conversion elements for a part of the plurality of pixels; and a step of forming a second-type separation region using a material different from that of the first-type separation region, the second-type separation region extending in a flat plate shape in the direction along the thickness direction of the silicon substrate, the second-type separation region separating the photoelectric conversion elements for another part of the plurality of pixels.

[0021] According to still another aspect of the present technology, an electronic device is provided, which includes a solid-state imaging element, the solid-state imaging element including: a plurality of pixels, each of the plurality of pixels including a photoelectric conversion element formed on a silicon substrate, wherein a part of the plurality of pixels have the photoelectric conversion elements separated by a first-type separation region that extends in a flat plate shape in a direction along the thickness direction of the silicon substrate, and another part of the plurality of pixels have the photoelectric conversion elements separated by a second-type separation region formed of a material different from that of the first-type separation region, and the second-type separation region extends in a flat plate shape in the direction along the thickness direction of the silicon substrate.

[0022] Note that the present technology also includes various aspects, such as: aspects of implementing the above solid-state imaging element by combining it in different devices; and aspects of implementing the above solid-state imaging element using different methods, etc. The present technology also includes various aspects, such as aspects of implementing the manufacturing method of the above solid-state imaging element as a part of other methods.

[0023] Advantageous effects of the present technology

[0024] According to the present technology, at least one of various problems of the image sensor of the 2PD method can be solved. Note that since the effects described in this specification are merely exemplary, the present technology is not limited thereto, and thus additional effects can be provided. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 is a plan view of a pixel arrangement of a solid-state imaging device according to a first embodiment.

[0026] Figure 2 is a schematic diagram of a cross-sectional structure of a solid-state imaging device according to a first embodiment.

[0027] Figure 3 Illustrates the result of an optical path simulation of incident light for a photoelectric conversion element separated by different separation films.

[0028] Figure 4 is a diagram illustrating the wavelength dependence of the light absorption rate (photoelectric conversion rate) in silicon.

[0029] Figure 5 is a diagram illustrating a comparison of light reception angle distribution characteristics between a first type of separation region formed by impurity ion implantation and a second type of separation region formed using an oxide film.

[0030] Figure 6 is a plot diagram illustrating the added value of output signals of a first part and a second part of each photoelectric conversion element applicable to the first type of separation region as the wavelength of incident light changes.

[0031] Figure 7 is a plot diagram illustrating the added value of output signals of a first part and a second part of each photoelectric conversion element applicable to the second type of separation region as the wavelength of incident light changes.

[0032] Figure 8 is an explanatory diagram for describing the optical path change caused by the film width of the second type of separation region.

[0033] Figure 9 is a diagram illustrating the simulation result of the relationship between the film width of the second type of separation region and the relative sensitivity.

[0034] Figure 10 is an explanatory diagram for explaining an exemplary manufacturing method of a solid-state imaging device.

[0035] Figure 11 is an explanatory diagram for explaining an exemplary manufacturing method of a solid-state imaging device.

[0036] Figure 12It is an explanatory diagram for an exemplary manufacturing method of a solid-state imaging device.

[0037] Figure 13 It is an explanatory diagram for an exemplary manufacturing method of a solid-state imaging device.

[0038] Figure 14 It is a block diagram of the configuration of an embodiment of an electronic device to which the present technology is applicable.

[0039] Figure 15 It is an explanatory diagram of an exemplary combination of pixels applicable to a first type of separation region and pixels applicable to a second type of separation region.

[0040] Figure 16 It is an explanatory diagram of an exemplary combination of pixels applicable to a first type of separation region and pixels applicable to a second type of separation region. Detailed Description

[0041] Hereinafter, the present technology will be described in the following order.

[0042] (A) First Embodiment:

[0043] (B) Second Embodiment:

[0044] (C) Third Embodiment:

[0045] (A) First Embodiment:

[0046] Figure 1 It is a plan view of the pixel arrangement of the solid-state imaging device according to the present embodiment, Figure 2 It is a schematic diagram of the cross-sectional structure of the solid-state imaging device according to the present embodiment. Note that although an exemplary back-illuminated solid-state imaging device will be used to describe the present embodiment, the present technology can also be implemented as a front-illuminated solid-state imaging device including a photoelectric conversion element PD described below.

[0047] The solid-state imaging device 100 includes a plurality of pixels, and each pixel includes a photodiode as an embedded photoelectric conversion element PD formed on a silicon semiconductor substrate 10.

[0048] The semiconductor substrate 10 is provided with an element separator 12 along the boundaries between the unit pixel regions of the plurality of pixels. The element separator 12 has a structure in which a silicon dioxide film is buried in a trench formed by engraving the semiconductor substrate 10; or a structure in which a silicon dioxide film and a metal are buried in a trench formed by engraving the semiconductor substrate 10. This arrangement can more effectively suppress color mixing between pixels than an element separator formed by impurity ion implantation.

[0049] In addition, for some of the plurality of pixels, a photoelectric conversion element PD formed in one of the unit pixel regions (regions respectively surrounded by the element separator 12) is also separated by a partition structure including a first type of separation region SP1 or a second type of separation region SP2.

[0050] Each of such pixels PX1 has a photoelectric conversion element PD separated into a first portion PD1 and a second portion PD2 by a first type of separation region SP1. The first type of separation region SP1 extends in a flat plate shape in the direction Dd along the thickness direction of the semiconductor substrate 10. Each of the other pixels PX2 has a photoelectric conversion element PD separated into a first portion PD1 and a second portion PD2 by a second type of separation region SP2. The second type of separation region SP2 extends in a flat plate shape in the direction Dd along the thickness direction of the semiconductor substrate 10.

[0051] The number of separated portions of the photoelectric conversion element PD in one unit pixel region separated by the first type of separation region SP1 or the second type of separation region SP2 needs to be two or more. For example, there are aspects where a separation film is formed in the photoelectric conversion element PD in one unit pixel region to divide the photoelectric conversion element PD into two; and aspects where two separation films intersecting in a cross shape in a plan view are formed in the photoelectric conversion element PD in one unit pixel region to divide the photoelectric conversion element PD into four. When the photoelectric conversion element PD formed in one unit pixel region is divided into two, a so-called two-photodiode (2PD) structure is obtained.

[0052] Both the first type of separation region SP1 and the second type of separation region SP2 include a silicon dioxide film or an impurity ion implantation region. Hereinafter, an exemplary case where the first type of separation region SP1 includes an impurity ion implantation region and the second type of separation region SP2 includes a silicon dioxide film will be mainly used to describe this embodiment.

[0053] In addition, in Figure 2 the example shown, a wiring layer 20 is stacked on the surface 10F side of the semiconductor substrate 10, and an insulating layer 30, a color filter layer 40 including a plurality of color filters 41 to 43, and an on-chip lens layer 50 including a plurality of on-chip lenses 51 to 53 are sequentially stacked on the back surface 10R side of the semiconductor substrate 10.

[0054] The wiring layer 20 is a so-called multi-layer wiring layer, which includes a plurality of wiring layers arranged via an interlayer insulating film. Since light does not enter the wiring layer side, the wiring layout can be flexibly designed.

[0055] The insulating layer 30 is formed with an antireflection coating, for example. The antireflection coating is formed with a plurality of films having different refractive indices, and for example, two films of hafnium dioxide (HfO2) film and silicon dioxide film are formed. A light-shielding film is provided on the insulating layer 30 along the position of the boundary portion between the unit pixel regions and in the shape of the boundary portion. The light-shielding film that needs to include a light-shielding material is preferably formed of a film of a metal such as aluminum (Al), tungsten (W), or copper (Cu) which has a strong light-shielding effect and can be finely processed by microfabrication, for example.

[0056] A planarization film is formed on the insulating layer 30 including the light-shielding film. Then, sequentially on the planarization film, a color filter layer 40 is formed, and an on-chip lens layer 50 is formed on the color filter layer 40. For example, the on-chip lenses 51 to 53 are formed of an organic material such as resin. For example, the planarization film can be formed of an organic material such as resin. For example, each of the on-chip lenses 51 to 53 has such a converging light characteristic that the beam waist of the converging light is formed within the thickness range of the semiconductor substrate 10.

[0057] The color filters 41 to 43 included in the color filter layer 40 selectively transmit any one of a plurality of mutually different colors (for example, red, green, and blue), and are, for example, color filters of a Bayer array. Hereinafter, the color of the color filter is described as the color of the pixel, where a pixel having a red color filter is a red pixel, a pixel having a green color filter is a green pixel, and a pixel having a blue color filter is a blue pixel. The incident light of the solid-state imaging device 100 is incident on the side of the on-chip lens layer 50, and each light beam that is converged by the on-chip lenses 51 to 53 and transmitted through the color filters 41 to 43 is received by the photoelectric conversion element PD.

[0058] The color filters 41 to 43 and the on-chip lenses 51 to 53 are provided at positions corresponding to their respective unit pixel regions. Another layer can be provided between the semiconductor substrate 10 and the wiring layer 20, and another layer can be provided between the semiconductor substrate 10, the insulating layer 30, the color filter layer 40, and the on-chip lens layer 50, respectively.

[0059] Figure 3 The result of the optical path simulation of the incident light for the photoelectric conversion element PD separated by different separation films is illustrated. Figure 3 (a) illustrates the separation film formed using the impurity ion implantation region in both cases, Figure 3 (b) illustrates the separation film formed using the silicon dioxide film in both cases. The values represented on the vertical axis and the horizontal axis are in units of 10 nm.

[0060] For the first type of separation region SP1 formed by impurity ion implantation ( Figure 3(a), the optical path is roughly similar to the case where the first type of separation region SP1 is not provided. This is because there is no difference in refractive index between the silicon that is the material of the semiconductor substrate 10 and the silicon dioxide film that is the material of each first type of separation region SP1. In other words, for each pixel separated by the first type of separation region SP1, the incident light that is aggregated by the on-chip lens and then incident on the back surface 10R of the semiconductor substrate 10 is incident on the approximate center of the photoelectric conversion element PD of the pixel. Then, the incident light travels in a direction substantially perpendicular to the substrate surface, and is reflected on the surface 10F of the semiconductor substrate 10, and travels in the opposite direction through substantially the same optical path.

[0061] Meanwhile, for each second type of separation region SP2 formed through an oxide film ( Figure 3 (b)), the optical path is branched to both sides of the second type of separation region SP2, and the light travels while being repeatedly reflected between the boundary of the element separator 12 that is the reflecting surface and the boundary of the second type of separation region SP2 that is the reflecting surface. This is because there is a difference in refractive index between the surrounding silicon that is the material of the semiconductor substrate 10 and the second type of separation region SP2.

[0062] Here, since each of the second type of separation regions SP2 is only formed to the middle of the depth of the semiconductor substrate 10 (in the Figure 3 longitudinal axis, the value is in the range of about 2 to 2.5 μm), there is a gap between the second type of separation region SP2 and the surface 10F of the semiconductor substrate 10 (in the Figure 3 longitudinal axis, the value is in the range of about 2.5 to 4 μm).

[0063] Therefore, when the light travels beyond the formation depth of the second type of separation region SP2, there is a possibility that the light that has traveled in the first part PD1 of the photoelectric conversion element PD separated by the second type of separation region SP2 travels reflectively to the adjacent second part PD2. Conversely, there is a possibility that the light that has traveled in the second part PD2 of the photoelectric conversion element PD separated by the second type of separation region SP2 travels reflectively to the adjacent first part PD1. In other words, there is a possibility of optical color mixing occurring on both sides of the second type of separation region SP2.

[0064] Figure 4It is a diagram showing the wavelength dependence of the light absorption rate (photoelectric conversion rate) in silicon. As shown in the figure, silicon has the tendency that for light with a shorter wavelength, the light absorption rate increases, and for light with a longer wavelength, the light absorption rate decreases. Therefore, light is more likely to travel to the surface 10F side with respect to the formation depth of the second type of separation region SP2 in the order of decreasing wavelength (red > green > blue), and for light with a shorter wavelength, optical color mixing is more likely to occur on both sides of the second type of separation region SP2.

[0065] Therefore, it can be understood that by adjusting the length in the depth direction of the second type of separation region SP2, the degree of suppression of color mixing of short-wavelength light can be adjusted. For example, a length of 0.5 μm or more in the depth direction of the second type of separation region SP2, more preferably a length of 1 μm, can suppress optical color mixing on both sides of the second type of separation region SP2 caused by light with a wavelength of 400 nm or less.

[0066] In addition, since the element separator 12 is only formed to the middle of the depth of the semiconductor substrate 10 (in Figure 3 on the vertical axis, the value is in the range of about 2 to 2.5 μm), a gap is formed between the second type of separation region SP2 and the surface 10F of the semiconductor substrate 10 (in Figure 3 on the vertical axis, the value is in the range of about 2.5 to 4 μm).

[0067] Therefore, when light travels beyond the formation depth of the element separator 12, there is a possibility that the light that has traveled in one pixel separated by the element separator 12 travels reflectively to other pixels. In other words, there is a possibility of color mixing occurring between adjacent pixels separated by the element separator 12.

[0068] In addition, light is more likely to travel to the surface 10F side with respect to the formation depth of the element separator 12 in the order of decreasing wavelength (red > green > blue), and for light with a shorter wavelength, color mixing is more likely to occur between adjacent pixels separated by the element separator 12.

[0069] Therefore, it can be understood that by adjusting the length in the depth direction of the element separator 12, the degree of suppression of color mixing of short-wavelength light can be adjusted. For example, a length of 0.5 μm or more in the depth direction of the second type of separation region SP2, more preferably a length of 1 μm, can suppress optical color mixing on both sides of the second type of separation region SP2 caused by light with a wavelength of 400 nm or less. More ideally, the element separator 12 is formed such that its length reaches the surface 10F of the semiconductor substrate 10.

[0070] Although the element separator 12 having a length reaching the surface 10F of the semiconductor substrate 10 can be formed from the back surface 10R side of the semiconductor substrate 10 as described above, the element separator 12 can also be formed using a structure in which a silicon dioxide film is buried in a groove formed from the surface 10F side of the semiconductor substrate 10; or formed using a structure in which a silicon dioxide film and a metal are buried in a groove formed from the surface 10F side of the semiconductor substrate 10.

[0071] By adopting the technique of forming the element separator 12 from the surface 10F side and forming the second type separation region SP2 from the back surface 10R side, there is no need to worry about the unevenness of the resist to be scanned caused by the previously formed groove recess. In addition, the second type separation region SP2 having a length that does not reach the surface 10F and formed from the back surface 10R side can allow the saturated and overflowing electrons to escape from one side to the other between the first part PD1 and the second part PD2 of the photoelectric conversion element PD separated by the second type separation region SP2.

[0072] Figure 5 It is a diagram showing a comparison of the light reception angle distribution characteristics between the first type separation region SP1 (implantation separation L and implantation separation R) formed by impurity ion implantation and the second type separation region SP2 (oxide film separation L and oxide film separation R) formed using an oxide film.

[0073] According to this figure, it can be understood that in terms of the occurrence of color mixing at the overall light reception angle, the second type separation region SP2 is lower than the first type separation region SP1. This is because, in the case of using the first type separation region SP1, in silicon, for example, light propagates on the first type separation region SP1, and the electrons generated by photoelectric conversion on the first type separation region SP1 having a potential higher than that of silicon move to the first part PD1 or the second part PD2 due to probabilistic behavior, resulting in deterioration of the separability of the light reception angle distribution.

[0074] Figure 6 It is a plotted diagram showing the added value of the output signals of the first part PD1 and the second part PD2 of each photoelectric conversion element PD applicable to the first type separation region SP1 as the wavelength of the incident light changes. Figure 7 It is a plotted diagram showing the added value of the output signals of the first part PD1 and the second part PD2 of each photoelectric conversion element PD applicable to the second type separation region SP2 as the wavelength of the incident light changes. When taking the peak of the output signal of the G pixel as the normalization factor (100%), along Figure 6 and 7 the relative spectral level represented by the vertical axis in represents the output signals of other pixels as a percentage.

[0075] AsFigure 6 As shown, each photoelectric conversion element PD to which the first type of separation region SP1 is applicable exhibits light reception characteristics substantially equivalent to those of each photoelectric conversion element PD without a separation film.

[0076] As Figure 7 shown, for the photoelectric conversion element PD to which the second type of separation region SP2 is applicable, optical color mixing occurs between the red pixel and the Gr pixel (green pixel adjacent to the red pixel), and optical color mixing occurs between the blue pixel and the Gb pixel (green pixel adjacent to the blue pixel), as compared with the photoelectric conversion element PD without a separation film. However, it is observed that at wavelengths less than 480 nm, each photoelectric conversion element PD has light reception characteristics substantially equivalent to those of each photoelectric conversion element PD without a separation film, and at wavelengths of 480 nm or more, each photoelectric conversion element PD has light reception characteristics different from those of each photoelectric conversion element PD without a separation film. In addition, at wavelengths of 600 nm or more, an offset occurs between the Gr pixel and the Gb pixel.

[0077] Figure 8 is an explanatory diagram for describing the change in the optical path caused by the film width of the second type of separation region SP2. Figure 8 The left figure in Figure 8 illustrates an optical path simulation in the case where the film width of the second type of separation region SP2 is 120 nm, and the right figure in

[0078] illustrates an optical path simulation in the case where the film width of the second type of separation region SP2 is 320 nm. According to this figure, it can be understood that, as compared with the case where the film width of the second type of separation region SP2 is 120 nm, in the case where the film width of the second type of separation region SP2 is 320 nm, the penetration depth of the light propagating inside the second type of separation region SP2 is longer, and the amount of light propagating inside the second type of separation region SP2 is larger. In other words, it can be understood that as the film width of the second type of separation region SP2 increases, the amount of light incident on the first part PD1 and the second part PD2 of the photoelectric conversion element PD decreases.

[0079] Figure 9 is a diagram showing the simulation results of the relationship between the film width of the second type of separation region SP2 and the relative sensitivity. The relative sensitivity shown in the figure is normalized by the sensitivity in the case where light at 400 nm is incident perpendicularly (0 degrees) on the photoelectric conversion element PD to which the first type of separation region SP1 is applicable. As shown, the relative sensitivity is approximately 1 when the film width of the second type of separation region SP2 is about 400 nm or less, and the relative sensitivity is about 0.8 or more when the film width of the second type of separation region SP2 is about 550 nm or less.

[0080] In other words, it can be understood that the second type of separation region SP2 having a film width equal to or less than the visible light wavelength suppresses light propagation inside the second type of separation region SP2 as quickly as possible. In addition, it can be understood that the second type of separation region SP2 having a film width equal to or less than the blue light wavelength can achieve a relative sensitivity of 0.9 or more. In addition, it can be understood that the second type of separation region SP2 having a film width equal to or less than the green light wavelength can achieve a relative sensitivity of 0.8 or more.

[0081] In view of this characteristic, it can be understood that the pixels PX1 applicable to the first type of separation region SP1 and the pixels PX2 applicable to the second type of separation region SP2 can be selected according to the use and in various combinations. This will be described below with reference to Figure 15 and 16 Exemplary specific combinations are described, but the variations of the combinations are not limited thereto.

[0082] An example of the first specific combination is the photoelectric conversion elements PD of the red pixels and green pixels to which the first type of separation region SP1 is applicable and the photoelectric conversion elements PD of the blue pixels to which the second type of separation region SP2 is applicable, as shown in Figure 15 (a).

[0083] Therefore, applying the second type of separation region SP2 to the photoelectric conversion element PD for photoelectric conversion of blue light with a short wavelength can achieve good separation of the light reception angle distribution for blue light, and applying the first type of separation region SP1 to the photoelectric conversion element PD for photoelectric conversion of green light or red light closer to the long wavelength can suppress color mixing caused by light reflected after reaching the vicinity of the surface 10F entering the adjacent region isolated by the separation film or the element separation region. At this time, the film width of the second type of separation region SP2 applied to the blue pixels is desirably a wavelength of blue light (about 400 nm) or less.

[0084] An example of the second specific combination is the case shown in Figure 15 (b), where the first type of separation region SP1 is applied to the photoelectric conversion element PD of the red pixels, and the second type of separation region SP2 is applied to the photoelectric conversion elements PD of the green pixels and blue pixels.

[0085] Therefore, applying the second type of separation region SP2 to the green pixels other than the blue pixels can achieve good separation of the light reception angle distribution for the green pixels, and can obtain the advantage that the autofocus accuracy using the image plane phase difference is improved when the subject has a contrast in the green wavelength region.

[0086] An example of the third specific combination is as shown in Figure 16The photoelectric conversion elements PD for Gb pixels and blue pixels applicable to the second type of separation region SP2 shown in (c) and the photoelectric conversion elements PD for Gr pixels and red pixels applicable to the first type of separation region SP1.

[0087] Therefore, applying the second type of separation region SP2 to blue pixels and Gb pixels and applying the first type of separation region SP1 to red pixels and Gr pixels can cause color mixing only in blue pixels due to light reflected after reaching near the surface 10F being incident on adjacent regions separated by the separation film or the element separation region, making this combination suitable for cases where red is considered important from viewpoints such as image formation. At this time, aligning the partition of the second type of separation region SP2 in a direction orthogonal to the direction in which Gb pixels and blue pixels are arranged in parallel has the advantage that it does not have an adverse effect on the calculation of the offset amount of the image plane phase difference for Gr pixels and Gb pixels with different types of separation films.

[0088] An example of the fourth specific combination is as Figure 16 the photoelectric conversion elements PD for red pixels and Gb pixels applicable to the first type of separation region SP1 and the photoelectric conversion elements PD for blue pixels and Gr pixels applicable to the second type of separation region SP2 shown in (d).

[0089] Therefore, applying the second type of separation region SP2 to blue pixels and Gr pixels and applying the first type of separation region SP1 to red pixels and Gb pixels can cause color mixing only in red pixels due to light reflected after reaching near the surface 10F being incident on adjacent regions separated by the separation film or the element separation region, making this combination suitable for cases where blue is considered important from viewpoints such as image formation. In addition, the partition direction of the second type of separation region SP2 (orthogonal to the direction in which Gr pixels and red pixels are arranged in parallel) has the advantage that it does not have an adverse effect on the calculation of the offset amount of the image plane phase difference for Gr pixels and Gb pixels with different types of separation films.

[0090] For example, the structure of the pixel transistor for outputting the charge accumulated in each photoelectric conversion element PD of the above-described solid-state imaging device can adopt, for example, the circuit structure described in Japanese Patent Application Laid-Open No. 2015-65269.

[0091] (B) Second Embodiment:

[0092] Next, an exemplary manufacturing method of the solid-state imaging device according to the first embodiment will be described with reference to Figures 10 to 13 this.

[0093] First, a photodiode serving as a photoelectric conversion element PD is formed by ion implantation from the surface 10F side of the semiconductor substrate 10 in a two-dimensional arrangement having a two-dimensional matrix. For example, in regions corresponding to respective photoelectric conversion elements PD on the surface 10F of the semiconductor substrate 10, a p-type semiconductor well region in contact with an element isolation region where an element separator is to be formed is formed, and a plurality of pixel transistors are formed in each p-type semiconductor well region. Each pixel transistor is formed with a source region, a drain region, a gate insulating film, and a gate electrode. Note that Figures 10 to 13 illustrations of the photoelectric conversion element PD and the pixel transistors are omitted.

[0094] Next, a resist mask R is formed on the surface 10F of the semiconductor substrate 10, and impurity ion implantation is performed from above the resist mask R. The resist mask R has an opening R1 in regions where the element separator 12, the first type separation region SP1, and the second type separation region SP2 are to be formed. Impurity ion regions Dp1 are formed in a predetermined depth range of the semiconductor substrate 10 by impurity ion implantation, and each impurity ion region Dp1 has a width corresponding to the opening R1.

[0095] Next, a wiring layer 20 is stacked on the surface 10F of the semiconductor substrate 10, and the wiring layer 20 includes a plurality of wiring layers disposed via an interlayer insulating film. An interlayer insulating film such as an SiO2 film is stacked on the wiring layer 20, and the interlayer insulating film is planarized by chemical mechanical polishing (CMP: chemical mechanical polishing) so that the surface of the wiring layer 20 is formed into a substantially flat surface.

[0096] Next, a support substrate SB is bonded to the substantially flat surface of the wiring layer 20 for reinforcement. For example, a semiconductor substrate such as bulk silicon is used for the support substrate SB. Note that in the case where part or all of the peripheral circuits are formed on a separately manufactured peripheral circuit substrate, the peripheral circuit substrate is bonded to the surface of the wiring layer 20, and the support substrate SB is bonded to the peripheral circuit substrate. Then, the semiconductor substrate 10 to which the support substrate SB is bonded is turned upside down so that the back surface 10R of the semiconductor substrate 10 is set as the upper surface.

[0097] Next, a removal process is performed from the back surface 10R of the semiconductor substrate 10 to the vicinity of the back surface of the photoelectric conversion element PD by grinding and polishing. Finally, the back surface 10R of the semiconductor substrate 10 is processed by CMP to make it substantially flat. Note that the final stage of the process can be performed by etching.

[0098] Next, a silica film HM is formed as a hard mask on the back surface 10R of the semiconductor substrate 10, and an opening HM1 is formed only at the position where the second type of isolation region SP2 is to be formed by photolithography and etching. For example, a silica film as a hard mask can be formed by high density plasma (HDP) or plasma tetraethyl oxysilane (P-TEOS).

[0099] Next, the back surface 10R of the semiconductor substrate 10 is subjected to anisotropic dry etching through the hard mask, thereby forming trenches T in the portion where the second type of isolation region SP2 is to be formed and included within the range of the impurity ion region Dp1. In other words, the entire wall surface of each trench T is covered in shape by the impurity ion region Dp1. After forming the trenches T, the hard mask is removed by, for example, wet etching.

[0100] Next, a negative fixed charge film is deposited on the back surface 10R of the semiconductor substrate 10 and the entire wall surface of each trench T. As the negative fixed charge film, a material that can generate fixed charges to enhance pinning due to deposition on a substrate such as silicon is preferably used, and a high refractive index material film or a high dielectric film having a negative charge can be used. As a specific material, for example, an oxide or nitride containing at least one element of hafnium (Hf), aluminum (Al), zirconium (Zr), tantalum (Ta), and titanium (Ti) can be applied. Examples of the deposition method include a chemical vapor deposition (hereinafter referred to as CVD) method, a sputtering method, and an atomic layer deposition (hereinafter referred to as ALD) method. Using the ALD method, a SiO2 film with a thickness of about 1 nm can be formed simultaneously, which reduces the interface state during deposition. In addition, examples of materials other than the above materials include oxides and nitrides containing at least one element of lanthanum (La), praseodymium (Pr), cerium (Ce), neodymium (Nd), promethium (Pm), samarium (Sm), europium (Eu), gadolinium (Gd), terbium (Tb), dysprosium (Dy), holmium (Ho), thulium (Tm), ytterbium (Yb), lutetium (Lu), and yttrium (Y). In addition, a hafnium oxynitride film or an aluminum oxynitride film can be used to form the fixed charge film. For each of the above materials of the fixed charge film, silicon (Si) or nitrogen (N) can be added to the film within the range that does not damage the insulating properties. Its concentration is appropriately determined within the range that does not damage the insulating properties of the film. Therefore, adding silicon (Si) or nitrogen (N) can improve the heat resistance of the film and the ability to block ion implantation during processing.

[0101] Next, the oxide film is buried in the trench T, and the oxide film F1 laminated on the back surface 10R of the semiconductor substrate 10 is removed by etch-back. At this time, a part of the oxide film F1 deposited on the back surface 10R of the semiconductor substrate 10 remains, forming a thin oxide film F2 covering the back surface 10R. Therefore, when the thin oxide film F2 is retained between the light-shielding film CM1 and the silicon of the semiconductor substrate 10, which will be described later, increasing the distance between the light-shielding film CM1 and the silicon of the semiconductor substrate 10 can improve the darkness characteristics.

[0102] Next, a barrier metal film and a metal film are deposited as the light-shielding film material layer CM1 on the oxide film F2 of the semiconductor substrate 10. The barrier metal film is formed using Ti, TiN, Ta, or TaN by, for example, sputtering or CVD. The metal is formed using Cu, W, or Al by, for example, electrolytic plating. Then, a resist mask is selectively formed on the light-shielding film material layer CM1. The resist mask is processed to remain on the regions protected from light, such as the regions for determining the black level, the peripheral circuit regions, and the regions along the pixel boundaries, etc. The light-shielding film material layer not covered by the resist mask is removed by photolithography and etching to form the light-shielding film CM2.

[0103] Next, next, a planarization film PF is formed on the light-shielding film CM2 to eliminate the height difference, and color filters 41 to 43 are sequentially formed on the planarization film. The planarization film PF is used to avoid unevenness that occurs in the spin-coating process of the color filters 41 to 43, but as long as the unevenness is acceptable, it is not necessary to eliminate the height difference. For example, although the planarization film PF can be deposited by spin-coating a resin material, an inorganic film such as SiO2 can be deposited and planarized by CMP. It is considered that, for example, for the color filters 41 to 43, pigments or dyes are spin-coated, and the color filters can be arranged in a Bayer array or the like. However, the arrangement of the color filters 41 to 43 is not limited thereto.

[0104] Next, on-chip lenses 51 to 53 are formed on color filters 41 to 43. Examples of the material of on-chip lenses 51 to 53 include styrenic resins, acrylic resins, styrene-acrylic copolymer resins, and siloxane-based resins as organic materials, but the material of on-chip lenses 51 to 53 is not limited thereto. For the formation of the lens shape, a photoresist (for example, a photosensitive material mainly composed of novolak resin) is patterned by photolithography. The patterned resist is subjected to heat treatment at a temperature higher than the heat softening point to form the lens shape. Using the lens-shaped resist as a mask, the lens shape pattern is pattern-transferred to the main lens material by dry etching, and lenses are formed for all pixels. However, the above formation is not limited to this technique. For example, a method can be used in which deposition, pre-baking, exposure, development, and bleach exposure processing of a lens material containing a photosensitive resin are performed in sequence, and then heat treatment is performed at a temperature not lower than the heat softening point of the photosensitive resin.

[0105] The solid-state imaging device according to the first embodiment described above can be manufactured using the manufacturing method described above.

[0106] (C) Third Embodiment:

[0107] Figure 14 is a block diagram of the configuration of an embodiment to which the electronic device of the present technology is applicable.

[0108] As Figure 14 shown, an imaging device 300 as an electronic device includes: an optical unit 311 including, for example, a lens group; a solid-state imaging element 312; and a digital signal processor (DSP) 313, which is a camera signal processing circuit. In addition, the imaging device 300 includes a frame memory 314, a display unit 315, a recording unit 316, an operation unit 317, a power supply unit 318, and a control unit 319. The DSP 313, the frame memory 314, the display unit 315, the recording unit 316, the operation unit 317, the power supply unit 318, and the control unit 319 are interconnected via a communication bus.

[0109] The optical unit 311 receives incident light (image light) from a subject to form an image on the imaging surface of the solid-state imaging device 312. The solid-state imaging device 312 converts the amount of incident light used by the optical unit 311 to form an image on the imaging surface into an electrical signal in units of pixels, and outputs color component signals for forming an image signal representing the subject image as pixel signals. In addition, the solid-state imaging device 312 outputs a phase difference detection signal to be used for phase difference autofocus (AF: auto focus) as a pixel signal. As the solid-state imaging device 312, a solid-state imaging device such as the solid-state imaging device 100 according to the above-described first embodiment can be used.

[0110] The display unit 315 includes, for example, a panel-type display device such as a liquid crystal panel or an organic electroluminescence (EL: electroluminescence) panel, and displays a still image or a moving image captured by the solid-state imaging device 312. The recording unit 316 records a still image or a moving image captured by the solid-state imaging device 312 in a recording medium such as a flash memory.

[0111] The operation unit 317 issues operation instructions for various functions included in the imaging device 300 according to a user's operation. The power supply unit 318 appropriately supplies various power supplies, which are operation power supplies for the DSP 313, the frame memory 314, the display unit 315, the recording unit 316, the operation unit 317, and the control unit 319, to objects to be supplied.

[0112] The control unit 319 controls the operations of the units of the imaging device 300. In addition, the control unit 319 uses the phase difference detection signal from the solid-state imaging device 312 to perform a predetermined calculation to calculate the amount of defocus, and controls the driving of the photographing lens included in the optical unit 311, for example, according to the amount of defocus to enter a focused state. This configuration allows performing in-plane phase difference AF to focus on the subject.

[0113] Note that the above-described embodiments have been exemplarily given in the case where the present technology is applied to a CMOS image sensor, which includes unit pixels arranged in a matrix, and each unit pixel is for detecting a signal charge corresponding to the amount of visible light as a physical quantity. However, the present technology is not limited to being applied to a CMOS image sensor, and thus, can be applied to a conventional solid-state imaging device having a photoelectric conversion element PD.

[0114] In addition, the present technology is not limited to a solid-state imaging device that detects the distribution of the incident light amount of visible light to capture an image. The present technology can be applied to such a solid-state imaging device: for example, capturing the incident amount of infrared rays, X-rays, or particles as an image; and such a conventional solid-state imaging device (physical quantity distribution detection device) in a broad sense: a fingerprint detection sensor that detects the distribution of different physical quantities such as pressure or electrostatic capacitance to capture an image.

[0115] Note that the present technology is not limited to the above-described embodiments, and for example, includes such a configuration: each configuration disclosed in the above-described embodiments is mutually replaced with each other, or changed and combined; and such a configuration: a well-known technology and each configuration disclosed in the above-described embodiments are mutually replaced, or changed and combined. In addition, the technical scope of the present technology is not limited to the above-described embodiments, but covers the content described in the scope of the claims and their equivalents.

[0116] In addition, the present technology can have the following configuration.

[0117] (1) A solid-state imaging device, comprising:

[0118] a plurality of pixels, each of the plurality of pixels including a photoelectric conversion element formed on a silicon substrate,

[0119] wherein, a part of the plurality of pixels has the photoelectric conversion element separated by a first type of separation region, the first type of separation region extending in a flat plate shape in a direction along the thickness direction of the silicon substrate, and

[0120] the other part of the plurality of pixels has the photoelectric conversion element separated by a second type of separation region formed of a material different from that of the first type of separation region, the second type of separation region extending in a flat plate shape in the direction along the thickness direction of the silicon substrate.

[0121] (2) The solid-state imaging device according to (1) above, wherein the pixels having the photoelectric conversion element separated by the first type of separation region and the pixels having the photoelectric conversion element separated by the second type of separation region are pixels of different colors.

[0122] (3) The solid-state imaging device according to (1) or (2) above, wherein the plurality of pixels include a combination of red pixels, blue pixels, and green pixels,

[0123] the pixels having the photoelectric conversion element separated by the second type of separation region include the blue pixels, and

[0124] the pixels having the photoelectric conversion element separated by the first type of separation region include the red pixels and the green pixels.

[0125] (4) The solid-state imaging device according to (1) or (2) above, wherein the flat plate-shaped second type separation region includes a silicon dioxide film, and the second type separation region has a flat plate thickness equal to or less than the wavelength of blue light.

[0126] (5) A method of manufacturing a solid-state imaging device, the solid-state imaging device including a plurality of pixels, each of the plurality of pixels including a photoelectric conversion element formed on a silicon substrate, the method including:

[0127] a step of forming a first type separation region that extends in a flat plate shape in a direction along the thickness direction of the silicon substrate, the first type separation region separating the photoelectric conversion elements for a part of the plurality of pixels; and

[0128] a step of forming a second type separation region using a material different from that of the first type separation region, the second type separation region extending in a flat plate shape in the direction along the thickness direction of the silicon substrate, the second type separation region separating the photoelectric conversion elements for other parts of the plurality of pixels.

[0129] (6) An electronic device, comprising:

[0130] a solid-state imaging device, the solid-state imaging device including: a plurality of pixels, each of the plurality of pixels including a photoelectric conversion element formed on a silicon substrate,

[0131] wherein, a part of the plurality of pixels has the photoelectric conversion elements separated by a first type separation region, the first type separation region extending in a flat plate shape in a direction along the thickness direction of the silicon substrate, and

[0132] other parts of the plurality of pixels have the photoelectric conversion elements separated by a second type separation region formed of a material different from that of the first type separation region, the second type separation region extending in a flat plate shape in the direction along the thickness direction of the silicon substrate.

[0133] List of reference numerals

[0134] 10 Semiconductor substrate

[0135] 10F Surface

[0136] 10R Back surface

[0137] 12 Element separator

[0138] 20 Wiring layer

[0139] 30 Insulating layer

[0140] 40 Color filter layer

[0141] 41 to 43 Color filters

[0142] 50 On-chip lens layer

[0143] 51 to 53 On-chip lenses

[0144] 100 Solid-state imaging device

[0145] 300 Imaging device

[0146] 311 Optical unit

[0147] 312 Solid-state imaging device

[0148] 313 Digital signal processor (DSP)

[0149] 314 Frame memory

[0150] 315 Display unit

[0151] 316 Recording unit

[0152] 317 Operation unit

[0153] 318 Power supply unit

[0154] 319 Control unit

[0155] CM1 Light-shielding film material layer

[0156] CM2 Light-shielding film

[0157] Dp1 Impurity ion region

[0158] F1 Oxide film

[0159] F2 Oxide film

[0160] HM Silicon dioxide film

[0161] HM1 Opening

[0162] PD Photoelectric conversion element

[0163] PF Planarization film

[0164] PD1 First part

[0165] PD2 Second part

[0166] PX1 Pixel

[0167] PX2 Pixel

[0168] R Resist mask

[0169] R1 opening

[0170] SB support substrate

[0171] SP1 first type of separation region

[0172] SP2 second type of separation region

[0173] T trench

Claims

1. An optical detection device, comprising: A first pixel, a second pixel, a third pixel, and a fourth pixel arranged adjacent to each other in a planar view, wherein the first pixel includes a first photoelectric conversion region and a second photoelectric conversion region, the second pixel includes a third photoelectric conversion region and a fourth photoelectric conversion region, the third pixel includes a fifth photoelectric conversion region and a sixth photoelectric conversion region, and the fourth pixel includes a seventh photoelectric conversion region and an eighth photoelectric conversion region; A first separation region arranged between the first photoelectric conversion region and the second photoelectric conversion region; A second separation region arranged between the third photoelectric conversion region and the fourth photoelectric conversion region; A third separation region arranged between the fifth photoelectric conversion region and the sixth photoelectric conversion region; and A fourth separation region arranged between the seventh photoelectric conversion region and the eighth photoelectric conversion region, wherein the second separation region, the third separation region, and the fourth separation region include the same material.

2. The optical detection device according to claim 1, wherein, The color of the first pixel is different from that of the second pixel, the third pixel, and the fourth pixel.

3. The optical detection device according to claim 1, wherein, The first pixel, the second pixel, the third pixel, and the fourth pixel are arranged as a Bayer array.

4. The optical detection device according to claim 1, wherein, The first separation region is formed by impurity ion implantation.

5. The optical detection device according to claim 4, wherein, For the first pixel, incident light is incident at the center of the region formed by the first photoelectric conversion region and the second photoelectric conversion region.

6. The optical detection device according to claim 1, wherein, The second separation region, the third separation region, and the fourth separation region are formed of an oxide film.

7. The optical detection device according to claim 6, wherein, For the second pixel, the third pixel, and the fourth pixel, incident light is respectively branched to both sides of the second separation region, the third separation region, and the fourth separation region.

8. The optical detection device according to claim 1, wherein, The second separation region, the third separation region, and the fourth separation region have a length of 0.5 μm or more in the depth direction.

9. The optical detection device according to claim 1, wherein, The flat second separation region, third separation region, and fourth separation region include a silicon dioxide film and have a width of 550 nm or less.

10. The optical detection device according to claim 1, wherein, The flat second separation region, third separation region, and fourth separation region include a silicon dioxide film and have a width equal to or less than the blue light wavelength.

11. The optical detection device according to claim 1, wherein, The first pixel is a red pixel, the second pixel and the third pixel are green pixels, and the fourth pixel is a blue pixel.

12. An electronic device, comprising the optical detection device according to any one of claims 1-11.

Images