Semiconductor device, and method for manufacturing semiconductor device

Abstract

To provide a technology for improving the sensitivity of a photoelectric conversion devices with DTI.SOLUTION: A semiconductor device comprises a plurality of photoelectric conversion sections and a pixel separation section of a DTI structure separating each of the plurality of photoelectric conversion sections, the pixel separation section comprises a plurality of protrusions extending from the photoelectric conversion section toward the inner side of the trench of the DTI structure and a dielectric arranged inside the trench so as to contact the plurality of protrusions, and the plurality of protrusions and the dielectric have different refractive indices for incident light.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to improving the sensitivity of a photoelectric conversion device, which is a semiconductor device. [Background technology]

[0002] Patent Document 1 discloses a solid-state imaging device having an inter-pixel separator having a protrusion that protrudes toward a photoelectric conversion section. Patent Document 1 also discloses deep trench isolation (hereinafter referred to as DTI) as an example of a pixel separator. Furthermore, Patent Document 2 discloses an example in which Poly-Si is used for the DTI portion. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent Publication No. 2021-197401 [Patent Document 2] US Patent Application Publication No. 2013 / 0307040 Summary of the Invention [Problem to be solved by the invention]

[0004] The DTI disclosed in Patent Document 1 may not necessarily be optimal in terms of sensitivity to incident light in a photoelectric conversion device. Therefore, a technology to improve the sensitivity of photoelectric conversion devices with DTI has been desired. [Means for solving the problem]

[0005] A first aspect of the present invention is a semiconductor device comprising a plurality of photoelectric conversion units and a pixel separation unit of a DTI structure that separates each of the plurality of photoelectric conversion units, wherein the pixel separation unit comprises a plurality of convex portions that protrude from the side of the photoelectric conversion units toward the inside of the trench of the DTI structure, and a dielectric arranged inside the trench so as to contact the plurality of convex portions, and wherein the plurality of convex portions and the dielectric have different refractive indices for incident light.

[0006] In addition, a second aspect of the present invention is a method for manufacturing a semiconductor device, comprising the steps of forming a plurality of photoelectric conversion units on a semiconductor substrate and forming a pixel isolation unit with a DTI structure that isolates each of the plurality of photoelectric conversion units, wherein the step of forming the pixel isolation unit comprises the steps of forming trenches between the plurality of photoelectric conversion units, forming a plurality of convex portions that protrude from the side surfaces of the trenches toward the inside of the trenches, and arranging a dielectric inside the trench so as to contact the plurality of convex portions, and wherein the plurality of convex portions are made of a material that has a refractive index for incident light different from that of the dielectric. [Effects of the Invention]

[0007] According to the present invention, it is possible to provide a technique for improving the sensitivity of a photoelectric conversion device having DTI. [Brief explanation of the drawings]

[0008] [Figure 1] 1 is a schematic cross-sectional view illustrating a cross section of a part of a photoelectric conversion device according to Embodiment 1, taken in a direction perpendicular to the light-receiving surface of a photoelectric conversion element 100. FIG. [Figure 2] FIG. 4 is a schematic cross-sectional view for explaining that the pixel separating portion of the photoelectric conversion device according to the embodiment has a function of scattering obliquely incident light. [Figure 3] FIG. 4 is a schematic diagram showing the surface of a trench in a first pixel isolation portion. [Figure 4] 10A is a schematic diagram illustrating an example of a cross section of a first pixel isolation section, and FIG. 10B is a schematic diagram illustrating another example of a cross section of a first pixel isolation section. [Figure 5] FIG. 10 is a schematic diagram showing a modified example of the surface of the trench in the first pixel isolation portion. [Figure 6] FIG. 6 is a schematic diagram showing a cross section taken along line AA' in FIG. 5. [Figure 7] FIG. 4 is a schematic plan view of a light receiving surface showing an example of the arrangement of a first pixel separating portion. [Figure 8] FIG. 10 is a schematic plan view of the light receiving surface showing another example of the arrangement of the first pixel separating portion. [Figure 9] FIG. 4 is a schematic partial cross-sectional view showing the sensor substrate before a first pixel separating portion is formed. [Figure 10] FIG. 10 is a schematic partial cross-sectional view showing a stage in which a trench for a first pixel separating portion is formed. [Figure 11] FIG. 10 is a schematic partial cross-sectional view showing a stage in which an impurity layer that becomes a second P-type semiconductor region is formed. [Figure 12] FIG. 10 is a schematic partial cross-sectional view showing the stage where an HSG-Si layer is formed on the inner surface of a trench. [Figure 13] FIG. 10 is a schematic partial cross-sectional view showing a stage in which a second dielectric layer has been deposited in the trench. [Figure 14] FIG. 10 is a schematic partial cross-sectional view showing a stage where layers deposited above the sensor substrate have been removed. [Figure 15] 4 is a schematic partial cross-sectional view showing a stage in which a first P-type semiconductor region, a second N-type semiconductor region, and a first N-type semiconductor region are formed. FIG. [Figure 16] FIG. 10 is a schematic partial cross-sectional view showing the stage where an interlayer insulating film, a substrate connecting plug, and metal wiring are formed. [Figure 17] FIG. 1 is a schematic partial cross-sectional view showing a circuit board on which a semiconductor element is formed. [Figure 18] FIG. 10 is a schematic partial cross-sectional view showing the stage where the sensor substrate and the circuit substrate are pasted and joined together. [Figure 19] FIG. 10 is a schematic partial cross-sectional view showing a stage in which the sensor substrate is thinned and a third P-type semiconductor region is formed. [Figure 20] 10 is a schematic partial cross-sectional view showing the stage where a light-shielding layer, a passivation layer, and an inner lens are formed. FIG. [Figure 21] FIG. 10 is a schematic partial cross-sectional view showing a stage in which the sensor substrate and the circuit substrate are pasted and joined together in the second embodiment. [Figure 22] FIG. 10 is a schematic partial cross-sectional view showing a stage in which trenches for creating second pixel separating portions are formed in the light incident surface. [Figure 23] 1 is a schematic partial cross-sectional view showing a stage where a pinning film has been deposited around the trench and a dielectric has been deposited on the top surface in and around the trench. [Figure 24] FIG. 10 is a schematic partial cross-sectional view showing a stage in which a light-shielding layer for shielding the second pixel separating portion from light, a passivation film, and an inner lens are formed. [Figure 25] (a) A schematic diagram for explaining an apparatus according to embodiment 3. (b) A schematic diagram showing an example of a photoelectric conversion system according to embodiment 3. (c) A schematic diagram showing an example of an in-vehicle photoelectric conversion system according to embodiment 3. DETAILED DESCRIPTION OF THE INVENTION

[0009] The photoelectric conversion device according to the embodiment of the present invention will be described with reference to the drawings. The embodiment described below is merely an example, and those skilled in the art can appropriately modify and implement the detailed configuration without departing from the spirit and scope of the present invention.

[0010] In the drawings referred to in the following description of the embodiments, elements denoted by the same reference numerals have the same functions unless otherwise specified. When a plurality of identical elements are arranged in a drawing, the reference numerals and their descriptions may be omitted.

[0011] In addition, because the drawings may be represented schematically for the convenience of illustration and explanation, the shape, size, and arrangement of elements depicted in the drawings may not strictly correspond to the actual objects. Furthermore, the descriptions "XX or more and YY or less" and "XX to YY" that represent a numerical range mean a numerical range including the endpoints XX (lower limit) and YY (upper limit), unless otherwise specified. When a numerical range is described in stages, the upper and lower limits of each numerical range can be arbitrarily combined.

[0012] [Embodiment 1] (Structure of photoelectric conversion device) The structure of a photoelectric conversion device according to embodiment 1 will be described with reference to the drawings. FIG. 1 is a schematic cross-sectional view showing a part of the photoelectric conversion device according to embodiment 1 cut in a direction perpendicular to the light-receiving surface of a photoelectric conversion element 100. The photoelectric conversion device includes a plurality of photoelectric conversion elements 100, and FIG. 1 shows the vicinity of one of the elements. The plurality of photoelectric conversion elements 100 are separated from each other by a first pixel separation portion 106.

[0013] The photoelectric conversion element 100 is composed of an N-type semiconductor 101 that functions as a photoelectric conversion region, a first P-type semiconductor region 102, a second N-type semiconductor region 103, a first N-type semiconductor region 104, a second P-type semiconductor region 105, etc., and is formed in a Si single crystal layer.

[0014] The first pixel separating section 106 is made up of an HSG-Si layer 107 (Hemi-Spherical-Grained-Poly-Si Layer), a first dielectric layer 108 which is a pinning layer, and a second dielectric layer 109. The HSG-Si layer 107 refers to a Poly-Si layer having hemispherical grain protrusions, but as will be described later, the shape of the protrusions of the HSG-Si layer 107 is not necessarily hemispherical.

[0015] In this example, the pinning layer is made of a dielectric, but it need not be disposed if it can be substituted, for example, by the characteristics of the second P-type semiconductor region 105. The photoelectric conversion element 100 and the first pixel separating portion 106 are disposed on the substrate connecting plug 110 and the metal wiring 112, with an interlayer insulating film 111 sandwiched therebetween.

[0016] Furthermore, a light-shielding layer 113 is disposed above the first pixel separation section 106 on the side where incident light 115 is incident. The photoelectric conversion element 100 and the first pixel separation section 106 are protected from the external environment by a passivation layer 114. In FIG. 1 , incident light 115 is illustrated as being incident perpendicular to the light-receiving surface, but in reality, it may be incident from a direction other than perpendicular to the light-receiving surface.

[0017] FIG. 2 is a schematic cross-sectional view illustrating the function of the pixel separator of the photoelectric conversion device according to this embodiment, which scatters obliquely incident light. In the figure, incident light 116 is incident at an angle from the photoelectric conversion unit side. This incident light 116 is incident on the boundary between the HSG-Si layer 107 of the first pixel separator 106 and the first and second dielectric layers 108 and 109. Because there is a large difference in refractive index between the HSG-Si layer 107 and the first dielectric layer 108, which serves as a pinning layer, the incident light 116 is scattered at this interface, as shown in FIG. 2. Without the first dielectric layer 108, which serves as a pinning layer, the incident light 116 would be scattered at the boundary between the HSG-Si layer 107 and the second dielectric layer 109. In this embodiment, the HSG-Si layer 107 is formed with randomly arranged irregularities during its formation. This means that the scattered light 117 is scattered in no particular direction and is not biased in any particular direction. From a macroscopic perspective, the scattered light is homogenized and scattered in all directions.

[0018] Here, assuming that the incident light is visible light, if the main component of the first dielectric layer 108, which is the pinning layer, is Al2O3, the refractive index of the incident light is 1.6. If the main component of the second dielectric layer 109 is a silicon dioxide film, the refractive index is 1.46. The HSG-Si layer 107 is formed of a poly-Si material and has a refractive index of approximately 4.0. It is preferable that the refractive index of the multiple convex portions (HSG-Si layer) for the incident light is 2.0 or more higher than the refractive index of the dielectric abutting on the opposite side of the photoelectric conversion portion.

[0019] Figure 3 is a schematic diagram showing the surface of the trench in the first pixel separation portion 106. Figure 3 is a view of the wall surface from the center of the trench, as seen from the direction of the arrows in Figures 4(a) and 4(b), which will be described later. As shown in Figure 3, the HSG-Si layer 107 has grain protrusions of approximately the same size that are distributed randomly and without regularity on the wall surface due to its characteristics.

[0020] 4(a) and 4(b) are schematic diagrams showing a cross section of the first pixel separating section 106 taken along line A-A' shown in FIG. 3. Depending on the conditions of the formation process, the HSG-Si layer 107 deposited on the surface (side surface) of the single-crystal region of the photoelectric conversion section 119 forms mushroom-shaped protrusions 118 shown in FIG. 4(a) and hemispherical protrusions 118 shown in FIG. 4(b). The HSG-Si layer 107 is made of poly-Si and is polycrystalline. When the crystalline structure of the cross section is observed using a TEM or the like, the boundary between the Si single-crystal layer that constitutes the photoelectric conversion section 119 and the Si polycrystalline layer that constitutes the HSG-Si layer 107 can be seen.

[0021] The deep trench of the first pixel separating section 106 is opened using a dry etching method, but in many cases it is processed using a repetitive process called the Bosch method. During this process, unevenness perpendicular to the depth direction (parallel to the incident light plane) may be repeatedly and periodically generated along the depth direction in the trench. In this case, the trench side surface 120 of the single crystal region that constitutes the photoelectric conversion section 119 is processed into a wavy shape.

[0022] As a result, the HSG-Si layer 107 and the convex portions 118 of the grain protrusions are formed in a form distributed on the processed surface that undulates periodically in the depth direction. When the pixel isolation region is observed from the light incident surface, the width of the isolation region in the depth direction appears to periodically widen and narrow depending on the depth. FIG. 5 is a schematic diagram of the surface of the trench in the first pixel isolation region 106 illustrating this state, and FIG. 6 is a schematic diagram showing a cross section taken along line A-A' in FIG. 5. The convex portions of the HSG-Si layer 107 are not concentrated on a part of the inner surface of the trench, but rather convex portions of similar size are distributed irregularly (randomly) in the depth direction and circumferential direction of the trench.

[0023] 7 and 8 are schematic diagrams of the light receiving surface viewed from the direction in which incident light 115 is incident, illustrating different arrangements of the first pixel separation portion 106 that separates the photoelectric conversion elements 100. The first pixel separation portion 106 may be formed in a lattice pattern so as to surround the periphery of each photoelectric conversion element 100, as shown in Fig. 7, or may be formed along a part of each photoelectric conversion element 100, as shown in Fig. 8.

[0024] As described above, the photoelectric conversion device according to this embodiment includes a DTI for separating pixels. The DTI contains an interface between materials with different refractive indices, and the interface has an irregular, uneven shape. Because a scattering surface is formed within the DTI, light incident on the DTI is scattered and reaches the photoelectric conversion region of the pixel. This allows the photoelectric conversion device according to this embodiment to achieve high sensitivity.

[0025] The semiconductor device according to this embodiment has the following features. The semiconductor device includes a plurality of photoelectric conversion units and a pixel isolation unit with a DTI structure that isolates each of the plurality of photoelectric conversion units. The pixel isolation unit includes a plurality of protrusions that protrude from the photoelectric conversion unit side toward the inside of a trench with the DTI structure, and a dielectric disposed inside the trench so as to contact the plurality of protrusions. The plurality of protrusions and the dielectric have different refractive indices for incident light.

[0026] Preferably, the refractive index of the material forming the plurality of convex portions is greater than that of the dielectric, and at least a portion of the incident light that is obliquely incident from the photoelectric conversion portion to the pixel separating portion is scattered at the boundary between the plurality of convex portions and the dielectric, and directed toward the photoelectric conversion portion.

[0027] Preferably, the plurality of protrusions are formed of, for example, polysilicon. Preferably, the surface of the layer on which the plurality of protrusions are arranged facing the photoelectric conversion section has a higher smoothness than the surface on the side of the plurality of protrusions. Preferably, the dielectric contains, as a main component, either Al2O3 or silicon dioxide.

[0028] Preferably, the plurality of protrusions includes at least one hemispherical protrusion or at least one mushroom-shaped protrusion. However, the plurality of protrusions may have other shapes as long as they can scatter incident light obliquely incident on the DTI from the photoelectric conversion unit side and return it to the photoelectric conversion unit efficiently. Preferably, the plurality of protrusions are irregularly arranged along the inner surface of the trench.

[0029] The pixel separating unit may be arranged so as to surround each of the plurality of photoelectric conversion units. Alternatively, the pixel separating unit may be arranged along a portion of each of the plurality of photoelectric conversion units. Each of the plurality of photoelectric conversion units may include a photodiode, and the photodiode may be an avalanche photodiode.

[0030] (Method of manufacturing a photoelectric conversion device) A method for manufacturing a photoelectric conversion device according to this embodiment will be described with reference to the schematic partial cross-sectional views shown in Figures 9 to 20. First, a method for forming a sensor substrate including photoelectric conversion elements will be described with reference to Figures 9 to 16.

[0031] 9 is a single crystal silicon substrate or a silicon substrate with an epitaxial layer. A photoresist mask 2004 is used to pattern an oxide film 2002 or a nitride film 2003 by dry etching to form a hard mask layer.

[0032] 10, a pixel separating portion is patterned by photolithography using a hard mask formed of an oxide film 2002 and a nitride film 2003. That is, a trench 2005 for the first pixel separating portion 106 is formed by dry etching using process conditions such as the Bosch method.

[0033] 11, an impurity layer 2006 that will become the second P-type semiconductor region 105 is formed on the side surface of the trench 2005 by using a method such as ion implantation, plasma doping, or solid phase diffusion. However, the impurity doping into the sensor substrate 2001 may not be performed at this stage and may be performed in a later process.

[0034] Next, as shown in FIG. 12, an HSG-Si layer 2007, which will become the HSG-Si layer 107, is formed on the inner surface of the trench 2005. For example, this can be done as follows: First, an amorphous silicon layer is deposited on the inner surface of the trench 2005 to a thickness of 100 to 300 nm at a process temperature of 590°C. The surface of the amorphous silicon layer is then subjected to an HF cleaning process to remove any native oxide film and clean the surface. This is followed by a Si nucleation process, followed by a heat treatment at a temperature of 580 to 700°C for several to several hundred seconds. The shape, size, and density of the grains (protrusions) of the HSG-Si layer 2007 can be adjusted by adjusting the heat treatment temperature, time, and other conditions of the nucleation process. For example, the size of the grains (protrusion height) may be greater than 3 nm and less than 300 nm.

[0035] As noted in the explanation of Figure 11, after the formation of the HSG-Si layer 2007, an impurity layer 2006 that will become the second P-type semiconductor region 105 may be formed on the single-crystal wall surface of the trench 2005 using an ion implantation method, a solid-phase diffusion method, a plasma doping method, or the like.

[0036] 13, an HSG-Si layer 2007 is formed, and a dielectric layer 2008 that will become the second dielectric layer 109 is deposited in the trench 2005 to form a pixel isolation structure. The dielectric layer 2008 may be made up of multiple layers, and may be made of any of Al2O3, SiO2, Ta2O5, TiN, SiN, SiON, etc.

[0037] Next, as shown in FIG. 14, the layers deposited above the sensor substrate 2001 are removed by a method such as dry etch-back, wet etching, or CMP.

[0038] 15, a region 2009 that will become the first P-type semiconductor region 102 in the pixel region, a region 2010 that will become the second N-type semiconductor region 103, a region 2011 that will become the first N-type semiconductor region 104, etc. are formed. These regions can be formed by forming a photoresist mask by photography and using an ion implantation method or the like. Alternatively, they may be formed using other methods, such as poly deposition, poly etching, thermal oxidation, CVD, or ALD.

[0039] 16, an insulating film 2012 that will become the interlayer insulating film 111, a plug 2013 that will become the substrate connection plug 110, a wiring layer 2014 that will become the metal wiring 112, and the like are formed to constitute a sensor substrate 2100 on which a semiconductor element is formed. The laminated structure of the insulating film 2012 and the wiring layer 2014 may be multiple layers. The insulating film 2012 may be made of SiO2, SiON, SiN, a low-K film, or the like, and the plug 2013 substrate and the wiring layer 2014 may be made of a material such as Al, Cu, W, or Co. The top surface of the wiring layer will become a bonding surface 2020 on the sensor substrate side, as will be described later.

[0040] 17 shows a circuit board 3100 on which a semiconductor element is formed. The circuit board 3100 may be formed using a process similar to that used to form the sensor substrate, or may be formed using a different method. The circuit board 3100 on which a semiconductor element is formed includes a semiconductor substrate 3001 and a wiring structure.

[0041] A transistor 3002 including a first element isolation portion 3003, a source / drain region 3004, a polysilicon gate 3005, etc. is formed on a semiconductor substrate 3001 by a combination of photolithography and ion implantation.

[0042] The wiring structure is composed of a multi-layer metal wiring layer 3009 consisting of a substrate connection plug 3007, an interlayer insulating film 3006, and a plurality of metal wirings 3008. The top surface of the wiring layer becomes a bonding surface 3020 on the circuit board side, as will be described later.

[0043] Once the sensor substrate 2100 and the circuit substrate 3100 are prepared, they are bonded together. Fig. 18 is a schematic diagram showing the state in which the sensor substrate 2100 on which semiconductor elements are formed and the circuit substrate 3100 on which semiconductor elements are formed are bonded together. A portion 2101 that will become the first pixel separation section 106 is formed on the sensor substrate 2100.

[0044] At the illustrated bonding surface 4001, the bonding surface 2020 on the sensor substrate side and the bonding surface 3020 on the circuit board side are bonded together. The bonding surfaces 2020 and 3020 are aligned and bonded together so that the insulating films and metal films of each are bonded together, thereby establishing electrical continuity between the sensor substrate 2100 and the circuit substrate 3100. The circuit substrate 3100 serves as a support substrate.

[0045] Next, the back surface of the sensor substrate 2100 is thinned to enable the photoelectric conversion region to function. The thickness of the sensor substrate is preferably, for example, approximately 300 nm to 5000 nm. Because the thinned surface of the sensor substrate can cause dark current, as shown in FIG. 19 , after thinning, a third P-type semiconductor region 4004 can be formed using plasma doping or ion implantation. Alternatively, a pinning layer can be deposited to enable the third P-type semiconductor region 4004 to function effectively. When using ion implantation, ion implantation may be performed in advance to a depth where the third P-type semiconductor region 4004 will be formed before bonding. Note that FIG. 19 shows a structure in which the sensor substrate 2100 is thinned to a thickness smaller than the depth of the previously formed portion 2101.

[0046] Furthermore, as shown in Figure 20, a layer 4005 that will become the light-shielding layer 113 that shields the first pixel separation portion 106, a layer 4006 that will become the passivation layer 114, an inner lens 4007, etc. are formed on the upper part of the light incident surface 4003, and the photoelectric conversion device is completed.

[0047] The method for manufacturing a semiconductor device according to this embodiment has the following features. The method for manufacturing a semiconductor device includes the steps of forming a plurality of photoelectric conversion units on a semiconductor substrate and forming a pixel isolation unit with a DTI structure that isolates each of the plurality of photoelectric conversion units. The step of forming the pixel isolation unit includes the steps of forming trenches between the plurality of photoelectric conversion units, forming a plurality of protrusions that protrude from the side surfaces of the trenches toward the inside of the trenches, and arranging a dielectric inside the trench so as to contact the plurality of protrusions. The plurality of protrusions are made of a material that has a refractive index for incident light different from that of the dielectric.

[0048] Preferably, the material for forming the plurality of convex portions has a refractive index greater than that of the dielectric material. Preferably, the plurality of convex portions are formed of polysilicon. Preferably, the surface of the layer on which the plurality of convex portions are arranged, facing the photoelectric conversion portion, has a higher smoothness than the surface on the side of the plurality of convex portions.

[0049] Preferably, in the step of forming the plurality of protrusions, an amorphous silicon layer is formed on the inner surface of the trench, followed by a Si nucleation treatment and a heat treatment. Preferably, the dielectric is formed mainly from either Al2O3 or silicon dioxide. Preferably, the formed plurality of protrusions includes at least one hemispherical protrusion or at least one mushroom-shaped protrusion. Preferably, the plurality of protrusions are irregularly arranged along the inner surface of the trench.

[0050] [Embodiment 2] Embodiment 2 will be described with reference to the schematic partial cross-sectional views of FIGS. 21 to 24. Descriptions of matters common to Embodiment 1 will be simplified or omitted. The photoelectric conversion device according to this embodiment includes a DTI for separating pixels, and an interface between materials with different refractive indices is formed inside the DTI, and this interface has an irregular, uneven shape. Because a scattering surface is formed inside the DTI, light incident on the DTI is scattered and reaches the photoelectric conversion region of the pixel. Therefore, the photoelectric conversion device according to this embodiment can achieve high sensitivity.

[0051] In the manufacturing method of the semiconductor device according to this embodiment, the same process as in embodiment 1 is used, up to the stage of thinning the sensor substrate 2100 after bonding together a sensor substrate 2100 on which a semiconductor element is formed and a circuit substrate 3100 on which a semiconductor element is formed.

[0052] However, while Figure 19, which was referred to in the explanation of embodiment 1, shows a case where the thickness of the sensor substrate 2100 after thinning is thinner than the depth of the previously formed portion 2101, this embodiment differs from this.

[0053] 21, in this embodiment, a sensor substrate 2100 on which a semiconductor element is formed and a circuit substrate 3100 on which a semiconductor element is formed are bonded together at a bonding surface 5001. The insulating films and metal films are aligned and bonded together, thereby establishing electrical continuity between the sensor substrate 2100 and the circuit substrate 3100.

[0054] The sensor substrate 2100 has a portion 5101 that will become the first pixel separation portion 106, and light is incident on the photoelectric conversion portion from a light incident surface 5002. The third P-type semiconductor region 5003 may be fabricated by thinning the sensor substrate 2100 and then forming a P-type region on the surface by plasma doping or ion implantation, as in the first embodiment. Alternatively, the third P-type semiconductor region 5003 may be fabricated by forming a P-type region at a depth where the third P-type semiconductor region 5003 will be formed before thinning.

[0055] Figure 21 shows a stage similar to Figure 19 in embodiment 1, but differs from embodiment 1 in that the thickness 5100H of the sensor substrate after thinning is greater than the thickness 5101H of the portion 5101 that becomes the first pixel separation portion 106.

[0056] In the portion 5101 that becomes the first pixel separation portion 106, the surface on the opposite side to the circuit board 3100 (the upper surface in FIG. 21) is located lower than the light incident surface 5002. For this reason, incident light may leak into the photoelectric conversion units of adjacent pixels through the gap between the light incident surface 5002 and the portion 5101 that becomes the pixel separation portion, possibly causing color mixing, for example.

[0057] Therefore, in this embodiment, as shown in FIG. 22, a photoresist mask 5004 and dry etching are used to form a trench 5005 on the light incident surface side for forming a second pixel separating portion.

[0058] 23, a pinning film 5006 made of, for example, Al2O3 may be deposited around the trench 5005, or other dielectric materials such as TiN, Ta2O5, SiN, SiON, or SiO2 may be deposited. Furthermore, a dielectric material 5007 is deposited in the trench 5005 and on the upper surface around the trench 5005. Materials such as SiO, SiN, and SiON may be used for the dielectric material 5007. In this manner, a second pixel isolation portion 5008 is formed.

[0059] Furthermore, as shown in Figure 24, a layer 5009 that will become the light-shielding layer 113 that shields the second pixel separation portion 5008, a layer 5010 that will become the passivation layer 114, an inner lens 5011, etc. are formed on the upper part of the light incident surface 5002, and the photoelectric conversion device is completed.

[0060] [Embodiment 3] As a third embodiment, a device including a semiconductor device (solid-state imaging device) according to any one of the above-described embodiments will be described. Fig. 25(a) is a schematic diagram for explaining a device 9191 including a semiconductor device 930 according to the above-described embodiment. The device 9191 including the semiconductor device 930 will be described in detail.

[0061] The semiconductor device 930 includes a semiconductor device 910 in which a first chip serving as a photoelectric conversion device and a second chip including at least one of a memory circuit and a logic circuit are integrated. The semiconductor device 930 can also include a package 920 that houses the semiconductor device 910, in addition to the semiconductor device 910. The package 920 can include a base to which the semiconductor device 910 is fixed, and a lid such as glass that faces the semiconductor device 910. The package 920 can further include bonding members such as bonding wires or bumps that connect terminals provided on the base to terminals provided on the semiconductor device 910.

[0062] The device 9191 can include at least one of an optical device 940, a control device 950, a processing device 960, a display device 970, a storage device 980, and a mechanical device 990. The optical device 940 is, for example, a lens, a shutter, or a mirror provided in correspondence with the semiconductor device 930. The control device 950 controls the semiconductor device 930. The control device 950 is, for example, a semiconductor device such as an ASIC.

[0063] The processing device 960 processes the signal output from the semiconductor device 930. The processing device 960 is a semiconductor device such as a CPU or ASIC for configuring an AFE (analog front end) or a DFE (digital front end). The display device 970 is an EL display device or a liquid crystal display device that displays information (images) obtained by the semiconductor device 930. The storage device 980 is a magnetic device or a semiconductor device that stores information (images) obtained by the semiconductor device 930. The storage device 980 is a volatile memory such as an SRAM or a DRAM, or a non-volatile memory such as a flash memory or a hard disk drive.

[0064] The mechanical device 990 has a moving part or a propulsion part such as a motor or an engine. In the device 9191, the signal output from the semiconductor device 930 is displayed on the display device 970, or transmitted to the outside by a communication device (not shown) provided in the device 9191. For this purpose, the device 9191 preferably further includes a memory device 980 and a processing device 960 in addition to the memory circuit and arithmetic circuit provided in the semiconductor device 930. The mechanical device 990 may be controlled based on the signal output from the semiconductor device 930.

[0065] The device 9191 is also suitable for electronic devices such as information terminals with a photographing function (for example, smartphones and wearable devices) and cameras (for example, interchangeable lens cameras, compact cameras, video cameras, and surveillance cameras). The mechanical device 990 in the camera can drive components of the optical device 940 for zooming, focusing, and shutter operation. Alternatively, the mechanical device 990 in the camera can move the semiconductor device 930 for vibration isolation operations.

[0066] The device 9191 may also be transportation equipment such as a vehicle, a ship, or an aircraft. The mechanical device 990 in the transportation equipment may be used as a moving device. The device 9191 as transportation equipment is suitable for transporting the semiconductor device 930 or for assisting and / or automating driving (piloting) using an imaging function. The processing device 960 for assisting and / or automating driving (piloting) can perform processing for operating the mechanical device 990 as a moving device based on information obtained by the semiconductor device 930. Alternatively, the device 9191 may be a medical device such as an endoscope, a measuring device such as a distance measuring sensor, an analytical device such as an electron microscope, an office machine such as a copier, or an industrial device such as a robot. The photoelectric conversion device according to the above-described embodiment can obtain high sensitivity, thereby making it possible to stably acquire images with excellent characteristics.

[0067] Therefore, if the semiconductor device 930 according to this embodiment is used in the equipment 9191, the value of the equipment can also be improved. For example, by installing the semiconductor device 930 in transportation equipment, excellent performance can be obtained when photographing the exterior of the transportation equipment or measuring the external environment. Therefore, when manufacturing and selling transportation equipment, deciding to install the semiconductor device according to this embodiment in the transportation equipment is advantageous in improving the performance of the transportation equipment itself. In particular, the semiconductor device 930 is suitable for transportation equipment that performs driving assistance and / or automatic driving using information obtained by the semiconductor device. Note that the application to vehicles, ships, aircraft, etc. is not limited to equipment used for transportation purposes, and can also be suitable for drones and the like that perform aerial photography for various purposes, including inspecting buildings and agricultural facilities and monitoring natural phenomena.

[0068] The photoelectric conversion system and moving object of this embodiment will be described with reference to FIGS. 25(b) and 25(c). FIG. 25(b) illustrates an example of a photoelectric conversion system related to an in-vehicle camera. The photoelectric conversion system 8 includes a photoelectric conversion device 80. The photoelectric conversion device 80 is the photoelectric conversion device serving as an electronic component described in the above embodiment. The photoelectric conversion system 8 includes an image processing unit 801 that performs image processing on multiple pieces of image data acquired by the photoelectric conversion device 80, and a parallax acquisition unit 802 that calculates parallax (phase difference between parallax images) from the multiple pieces of image data acquired by the photoelectric conversion system 8. The photoelectric conversion system 8 also includes a distance acquisition unit 803 that calculates the distance to an object based on the calculated parallax, and a collision determination unit 804 that determines whether or not there is a possibility of a collision based on the calculated distance. Here, the parallax acquisition unit 802 and the distance acquisition unit 803 are examples of distance information acquisition means that acquire distance information to an object. In other words, the distance information includes information related to the parallax, the amount of defocus, the distance to the object, etc. The collision determination unit 804 may determine the possibility of a collision using any of these distance information. The distance information acquisition means may be realized by dedicated hardware, or may be realized by a software module. It may also be realized by an FPGA (Field Programmable Gate Array), ASIC (Application Specific Integrated Circuit), or the like.

[0069] The photoelectric conversion system 8 is connected to a vehicle information acquisition device 810 and can acquire vehicle information such as vehicle speed, yaw rate, and steering angle. The photoelectric conversion system 8 is also connected to a control ECU 820, which is a control device that outputs a control signal to generate a braking force for the vehicle based on the determination result of the collision determination unit 804. The photoelectric conversion system 8 is also connected to an alarm device 830 that issues an alarm to the driver based on the determination result of the collision determination unit 804. For example, if the determination result of the collision determination unit 804 indicates a high possibility of a collision, the control ECU 820 performs vehicle control to avoid the collision and mitigate damage by applying the brakes, releasing the accelerator, suppressing engine output, etc. The alarm device 830 warns the user by sounding an alarm, displaying alarm information on a screen of a car navigation system, etc., or vibrating the seat belt or steering wheel.

[0070] In this embodiment, the photoelectric conversion system 8 captures an image of the surroundings of the vehicle, for example, the front or rear. Fig. 25(c) shows a photoelectric conversion system for capturing an image of the area in front of the vehicle (imaging range 850). A vehicle information acquisition device 810 sends instructions to the photoelectric conversion system 8 or the photoelectric conversion device 80. This configuration can further improve the accuracy of distance measurement.

[0071] Although the above describes an example of control to prevent collision with other vehicles, the present invention can also be applied to control of automatic driving by following other vehicles, control of automatic driving to prevent deviation from a lane, etc. Furthermore, the photoelectric conversion system is not limited to vehicles such as the subject vehicle, but can be applied to moving objects (moving devices) such as ships, aircraft, and industrial robots. In addition, the present invention can be applied not only to moving objects, but also to a wide range of devices that use object recognition, such as intelligent transport systems (ITS). According to the above-described embodiment, it is possible to stably acquire images with good characteristics.

[0072] [Other embodiments] The present invention is not limited to the above-described embodiments and examples, and many modifications are possible within the technical spirit of the present invention. For example, the above-described different embodiments may be combined in whole or in part.

[0073] The conductivity types of the semiconductor layers described in the embodiments are merely examples, and are not limited to the conductivity types described in the embodiments.

[0074] The semiconductor device described in each embodiment is not limited to a photoelectric conversion device for imaging. For example, it can also be applied to a distance measuring device (a device for measuring distance using focus detection or TOF (Time Of Flight)), a photometric device (a device for measuring the amount of incident light), etc. The photoelectric conversion device to which the present invention can be applied is not limited to a specific form, and for example, the image sensor portion may be either a front-illuminated type or a back-illuminated type. Furthermore, the photoelectric conversion unit provided in the image sensor may be an avalanche photodiode.

[0075] This specification discloses at least the following: [Matter 1] a plurality of photoelectric conversion units; and a pixel isolation unit having a DTI structure that isolates each of the plurality of photoelectric conversion units, the pixel separating section includes a plurality of protruding sections protruding from the photoelectric conversion section side toward an inside of the trench of the DTI structure, and a dielectric body arranged inside the trench so as to be in contact with the plurality of protruding sections; the plurality of protrusions and the dielectric have different refractive indices for incident light; A semiconductor device characterized by: [Matter 2] the refractive index of the material forming the plurality of protrusions is greater than that of the dielectric material with respect to incident light; 2. The semiconductor device according to item 1. [Matter 3] at least a part of incident light incident on the pixel separating portion is scattered at interfaces between the plurality of convex portions and the dielectric material and directed toward the photoelectric conversion portion; 3. The semiconductor device according to item 1 or 2. [Matter 4] the plurality of protrusions are formed of polysilicon; 4. The semiconductor device according to any one of items 1 to 3. [Matter 5] the surface of the layer on which the plurality of convex portions are arranged facing the photoelectric conversion portion has a higher smoothness than the surface on which the plurality of convex portions are disposed; 5. The semiconductor device according to any one of items 1 to 4. [Matter 6] The dielectric contains, as a main component, either Al2O3 or silicon dioxide. 6. The semiconductor device according to any one of items 1 to 5, [Matter 7] The plurality of protrusions include at least one hemispherical protrusion or at least one mushroom-shaped protrusion. 7. The semiconductor device according to any one of items 1 to 6, [Matter 8] the plurality of protrusions are irregularly arranged along the inner side surface of the trench; 8. The semiconductor device according to any one of items 1 to 7, characterized in that: [Matter 9] the pixel separating unit is arranged to surround each of the plurality of photoelectric conversion units, 9. The semiconductor device according to any one of items 1 to 8, characterized in that: [Matter 10] the pixel separating portion is disposed along a part of each of the plurality of photoelectric conversion portions, 9. The semiconductor device according to any one of items 1 to 8, characterized in that: [Matter 11] Each of the plurality of photoelectric conversion units includes a photodiode. 11. The semiconductor device according to any one of items 1 to 10. [Matter 12] The photodiode is an avalanche photodiode. 12. The semiconductor device according to item 11. [Matter 13] A method for manufacturing a semiconductor device, comprising: a step of forming a plurality of photoelectric conversion units on a semiconductor substrate; and a step of forming a pixel isolation unit having a DTI structure that isolates each of the plurality of photoelectric conversion units, The step of forming the pixel separating portion includes: forming trenches between the plurality of photoelectric conversion units; forming a plurality of protrusions protruding from the side surface of the trench toward the inside of the trench; and disposing a dielectric inside the trench so as to contact the plurality of protrusions, the plurality of convex portions are made of a material having a refractive index for incident light different from that of the dielectric material; 10. A method for manufacturing a semiconductor device comprising the steps of: [Matter 14] a material for forming the plurality of convex portions, the refractive index of which for incident light is greater than that of the dielectric; Item 14. The method for manufacturing a semiconductor device according to item 13. [Matter 15] The plurality of protrusions are formed of polysilicon. 15. The method for manufacturing a semiconductor device according to item 13 or 14. [Matter 16] the surface of the layer on which the plurality of convex portions are arranged facing the photoelectric conversion portion has a higher smoothness than the surface on which the plurality of convex portions are disposed; 16. A method for manufacturing a semiconductor device according to any one of items 13 to 15. [Matter 17] In the step of forming the plurality of convex portions, an amorphous silicon layer is formed on the inner surface of the trench, and then a Si nucleation treatment and a heat treatment are performed. 17. A method for manufacturing a semiconductor device according to any one of items 13 to 16. [Matter 18] The dielectric is formed mainly of either Al2O3 or silicon dioxide. 18. A method for manufacturing a semiconductor device according to any one of items 13 to 17. [Matter 19] The plurality of protrusions formed include at least one hemispherical protrusion or at least one mushroom-shaped protrusion. 19. A method for manufacturing a semiconductor device according to any one of items 13 to 18. [Matter 20] the plurality of protrusions are irregularly arranged along the inner side surface of the trench; 20. A method for manufacturing a semiconductor device according to any one of items 13 to 19. [Explanation of symbols]

[0076] 100: Photoelectric conversion element / 101: N-type semiconductor / 102: First P-type semiconductor region / 103: Second N-type semiconductor region / 104: First N-type semiconductor region / 105: Second P-type semiconductor region / 106: First pixel separation section / 107: HSG-Si layer / 108: First dielectric layer / 109: Second dielectric layer / 110: Substrate connection plug / 111: Interlayer insulating film / 112: Metal wiring / 113: Light-shielding layer / 114: Passivation layer / 115: Incident light / 116: Incident light / 117: Scattering Light / 118 ···Convex portion / 119 ···Photoelectric conversion portion / 120 ···Trench side surface / 2001 ···Sensor substrate / 2002 ···Oxide film / 2003 ···Nitride film / 2004 ···Photoresist mask / 2005 ···Trench / 2006 ···Impurity layer / 2007 ···HSG-Si layer / 2008 ···Dielectric layer / 2009 ···Region that will become the first P-type semiconductor region / 2010 ···Region that will become the second N-type semiconductor region / 2011 ···Region that will become the first N-type semiconductor region / 2012 ···Insulating film / 2013 ···Plug / 2014 ···Wiring layer / 2020···Bonding surface / 2100···Sensor substrate / 2101···Part that will become the first pixel isolation portion / 3001···Semiconductor substrate / 3002···Transistor / 3003···First element isolation portion / 3004···Source / drain region / 3005···POLY-Si gate / 3006···Interlayer insulating film / 3007···Substrate connection plug / 3008···Metal wiring / 3009···Layer metal wiring layer / 3020···Bonding surface / 3100···Circuit substrate 3 / 4001···Bonding surface / 4003···Light incident surface / 4004···Third P-type semiconductor region / 4005...Layer that will become the light-shielding layer / 4006...Layer that will become the passivation layer / 4007...Inner lens / 5001...Joint surface / 5002...Light incident surface / 5003...Third P-type semiconductor region / 5004...Photoresist mask / 5005...Trench / 5006...Pinning film / 5007...Dielectric / 5008...Second pixel separation section / 5009...Layer that will become the light-shielding layer / 5010...Layer that will become the passivation layer / 5011...Inner lens / 5101...Section that will become the first pixel separation section

Claims

1. a plurality of photoelectric conversion units; and a pixel separation unit having a DTI structure that separates each of the plurality of photoelectric conversion units, the pixel separating section includes a plurality of protruding sections protruding from the photoelectric conversion section side toward an inside of the trench of the DTI structure, and a dielectric body arranged inside the trench so as to be in contact with the plurality of protruding sections; the plurality of protrusions and the dielectric have different refractive indices for incident light; A semiconductor device characterized by:

2. the refractive index of the material forming the plurality of protrusions is greater than that of the dielectric material with respect to incident light; 2. The semiconductor device according to claim 1, wherein the semiconductor device is a semiconductor device having a first insulating layer.

3. at least a part of incident light incident on the pixel separating portion is scattered at interfaces between the plurality of convex portions and the dielectric material and directed toward the photoelectric conversion portion; 3. The semiconductor device according to claim 1, wherein the first insulating film is a semiconductor substrate.

4. the plurality of protrusions are formed of polysilicon; 3. The semiconductor device according to claim 1, wherein the first insulating film is a semiconductor substrate.

5. the surface of the layer on which the plurality of convex portions are arranged facing the photoelectric conversion portion has a higher smoothness than the surface on which the plurality of convex portions are disposed; 3. The semiconductor device according to claim 1, wherein the first insulating film is a semiconductor substrate.

6. The dielectric material contains Al as a main component. ２ O ３ , silicon dioxide, 3. The semiconductor device according to claim 1, wherein the first insulating film is a semiconductor substrate.

7. The plurality of protrusions include at least one hemispherical protrusion or at least one mushroom-shaped protrusion.

3. The semiconductor device according to claim 1, wherein the first insulating film is a semiconductor substrate.

8. the plurality of protrusions are irregularly arranged along the inner side surface of the trench; 3. The semiconductor device according to claim 1, wherein the first insulating film is a semiconductor substrate.

9. the pixel separating unit is arranged to surround each of the plurality of photoelectric conversion units, 3. The semiconductor device according to claim 1, wherein the first insulating film is a semiconductor substrate.

10. the pixel separating portion is disposed along a part of each of the plurality of photoelectric conversion portions, 3. The semiconductor device according to claim 1, wherein the first insulating film is a semiconductor substrate.

11. Each of the plurality of photoelectric conversion units includes a photodiode.

3. The semiconductor device according to claim 1, wherein the first insulating film is a semiconductor substrate.

12. The photodiode is an avalanche photodiode.

12. The semiconductor device according to claim 11.

13. A method for manufacturing a semiconductor device, comprising: a step of forming a plurality of photoelectric conversion units on a semiconductor substrate; and a step of forming a pixel isolation unit having a DTI structure that isolates each of the plurality of photoelectric conversion units, The step of forming the pixel separating portion includes: forming trenches between the plurality of photoelectric conversion units; forming a plurality of protrusions protruding from the side surface of the trench toward the inside of the trench; and disposing a dielectric inside the trench so as to contact the plurality of protrusions, the plurality of convex portions are made of a material having a refractive index for incident light different from that of the dielectric material; 10. A method for manufacturing a semiconductor device comprising the steps of:

14. a material for forming the plurality of convex portions, the refractive index of which for incident light is greater than that of the dielectric; 14. The method for manufacturing a semiconductor device according to claim 13.

15. The plurality of protrusions are formed of polysilicon.

15. The method for manufacturing a semiconductor device according to claim 13 or 14.

16. the surface of the layer on which the plurality of convex portions are arranged facing the photoelectric conversion portion has a higher smoothness than the surface on which the plurality of convex portions are disposed; 15. The method for manufacturing a semiconductor device according to claim 13 or 14.

17. In the step of forming the plurality of protrusions, an amorphous silicon layer is formed on the inner surface of the trench, and then a Si nucleation treatment and a heat treatment are performed.

15. The method for manufacturing a semiconductor device according to claim 13 or 14.

18. The dielectric is Al ２ O ３ , or silicon dioxide as a main component; 15. The method for manufacturing a semiconductor device according to claim 13 or 14.

19. The plurality of protrusions formed include at least one hemispherical protrusion or at least one mushroom-shaped protrusion.

15. The method for manufacturing a semiconductor device according to claim 13 or 14.

20. the plurality of protrusions are irregularly arranged along the inner side surface of the trench; 15. The method for manufacturing a semiconductor device according to claim 13 or 14.

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