Solid-state imaging device

Abstract

A solid-state imaging device according to an exemplary embodiment of the present disclosure includes a pixel array in which a plurality of pixels and one or more phase difference detection pixels are arranged in a matrix, wherein the phase difference detection pixels include a photodiode, an on-chip lens, an on-chip lens, an anti-reflective layer, a light-transmitting layer separation wall, a pixel separation wall, a boundary separation wall, and a light separation wall disposed between the on-chip lens and the photodiode, and the light separation wall may be disposed parallel to the extension direction of the boundary separation wall in a planar direction orthogonal to the stacking direction in the phase difference detection pixels.

Description

Technology Field

[0001] The present disclosure relates to a solid-state imaging device. Background Technology

[0002] Electronic devices with imaging capabilities, such as digital cameras or smartphones, use solid-state imaging devices such as CMOS image sensors.

[0003] A solid-state imaging device may include a phase difference detection pixel capable of detecting an image plane phase difference separately from a pixel that generates an electrical signal according to incident light, as illustrated in, for example, Patent Document 1.

[0004] In phase difference detection pixels, the separation ratio, which is an indicator of AF (Auto-Focus) performance, may decrease due to the diffraction limit of incident light accompanying the miniaturization of the pixel array. In addition, in phase difference detection pixels, light scattering occurs due to the interaction between the pixel separation wall and the incident light at the incident surface of the incident light in the photoelectric conversion unit, which may result in an increase in mixed colors or a decrease in sensitivity (decrease in QE (Quantum Efficiency)). Prior art literature

[0005] Patent Document 1: Japanese Patent Publication No. 2015-12127 The problem to be solved

[0006] The problem that the technical concept of the present disclosure aims to solve is to provide a solid-state imaging device capable of improving the separation ratio of incident light to a phase difference detection pixel. means of solving the problem

[0007] A solid-state imaging device according to an exemplary embodiment of the present disclosure is a solid-state imaging device having a plurality of pixels that generate an image signal according to incident light and a pixel array in which one or more phase difference detection pixels are arranged in a matrix, wherein the phase difference detection pixels comprise a photoelectric conversion unit, an on-chip lens disposed on the incident side of the incident light in the photoelectric conversion unit, a light-transmitting layer that transmits light of a specific wavelength in the incident light, an anti-reflection layer laminated on the photoelectric conversion unit, a light-transmitting layer separation wall disposed between the light-transmitting layer and the light-transmitting layer of another pixel adjacent to each other, a pixel separation wall disposed between the photoelectric conversion unit and the photoelectric conversion unit of another pixel adjacent to each other, a boundary separation wall that separates the photoelectric conversion unit surrounded by the pixel separation wall into a plurality of parts, and a light separation wall disposed between the on-chip lens and the photoelectric conversion unit, wherein the light separation wall may be disposed parallel to the extension direction of the boundary separation wall in a plane direction orthogonal to the stacking direction in the phase difference detection pixel.

[0008] A solid-state imaging device according to an exemplary embodiment of the present disclosure includes a pixel array comprising a plurality of phase difference detection pixels, and each of the plurality of phase difference detection pixels may include an on-chip lens that collects received light, a light-transmitting layer that transmits light of a specific wavelength among incident light transmitted through the on-chip lens, a photodiode that converts transmitted light transmitted through the light-transmitting layer into photoelectric, an anti-reflection layer stacked between the light-transmitting layer and the photodiode, a light-transmitting layer separator disposed between the light-transmitting layer and the light-transmitting layer of another pixel adjacent thereto, a pixel separator disposed between the photodiode and the photodiode of another pixel adjacent thereto, a light-separating wall that separates the light-transmitting layer into at least two parts, and a boundary separator that separates the photodiode into at least two parts. Effects of the invention

[0009] According to the solid-state imaging device of the embodiment of the present disclosure, the separation ratio of incident light of the phase difference detection pixel can be improved. Brief explanation of the drawing

[0010] FIG. 1 is a block diagram illustrating a solid-state imaging device according to an exemplary embodiment of the present disclosure. FIG. 2 is a partially enlarged plan view of a solid-state imaging device according to an exemplary embodiment of the present disclosure. Figure 3 is a schematic cross-sectional view taken along the line A1-A1 shown in Figure 2. Figure 4 is a schematic cross-sectional view taken along the line A2-A2 shown in Figure 2. Figure 5 is a schematic cross-sectional view taken along the line A3-A3 shown in Figure 3. Figure 6 is a schematic cross-sectional view taken along the line A4-A4 shown in Figure 3. Figure 7 is a schematic cross-sectional view taken along the line A5-A5 shown in Figure 3. FIG. 8a is a schematic diagram illustrating the state in which incident light is incident on a solid-state imaging device according to an exemplary embodiment of the present disclosure. Figure 8b is a schematic diagram showing the light intensity distribution of incident light incident on a light-transmitting layer cut along the line B1-B1 of Figure 8a. FIG. 8c is a schematic diagram showing the light intensity distribution of incident light incident on a photoelectric converter cut along the B2-B2 line of FIG. 8a. FIG. 9a illustrates an example configuration of a phase difference detection pixel according to an exemplary embodiment of the present disclosure, partial figure (a) is a schematic diagram of a light-transmitting layer, and partial figure (b) is a schematic diagram of a photoelectric conversion unit. FIG. 9b illustrates an example configuration of a phase difference detection pixel according to an exemplary embodiment of the present disclosure, wherein partial figure (a) is a schematic diagram of a light-transmitting layer and partial figure (b) is a schematic diagram of a photoelectric conversion unit. FIG. 9c illustrates an example configuration of a phase difference detection pixel according to an exemplary embodiment of the present disclosure, wherein partial view (a) is a schematic diagram of a light-transmitting layer and partial view (b) is a schematic diagram of a photoelectric conversion unit. FIG. 9d illustrates an example configuration of a phase difference detection pixel according to an exemplary embodiment of the present disclosure, wherein partial figure (a) is a schematic diagram of a light-transmitting layer and partial figure (b) is a schematic diagram of a photoelectric conversion unit. FIG. 9e illustrates an example configuration of a phase difference detection pixel according to an exemplary embodiment of the present disclosure, wherein partial figure (a) is a schematic diagram of a light-transmitting layer and partial figure (b) is a schematic diagram of a photoelectric conversion unit. FIG. 9f illustrates an example configuration of a phase difference detection pixel according to an exemplary embodiment of the present disclosure, wherein partial figure (a) is a schematic diagram of a light-transmitting layer and partial figure (b) is a schematic diagram of a photoelectric conversion unit. FIG. 10a is a schematic diagram of a phase difference detection pixel positioned at the center of a pixel array according to an exemplary embodiment of the present disclosure. FIG. 10b is a schematic diagram of a phase difference detection pixel disposed on the peripheral side of a pixel array according to an exemplary embodiment of the present disclosure. FIG. 11a is a schematic cross-sectional view of a solid-state imaging device having a light separation wall according to an exemplary embodiment of the present disclosure. Figure 11b is a schematic cross-sectional view taken along the line C1-C1 of Figure 11a. FIG. 11c is a schematic cross-sectional view taken along the line C2-C2 of FIG. 11b. FIG. 12a is a schematic cross-sectional view of a solid-state imaging device having a light separation wall according to an exemplary embodiment of the present disclosure. Figure 12b is a schematic cross-sectional view taken along the line D1-D1 of Figure 12a. FIG. 12c is a schematic cross-sectional view taken along the line D2-D2 of FIG. 12b. FIG. 13a is a schematic cross-sectional view of a solid-state imaging device having a light separation wall according to an exemplary embodiment of the present disclosure. Figure 13b is a schematic cross-sectional view taken along the line E1-E1 of Figure 13a. FIG. 13c is a schematic cross-sectional view taken along the line E2-E2 of FIG. 13b. FIG. 14a is a schematic cross-sectional view of a solid-state imaging device having a light separation wall according to an exemplary embodiment of the present disclosure. FIG. 14b is a schematic cross-sectional view of a solid-state imaging device cut along the line F1-F1 of FIG. 14a. FIG. 15 is a schematic cross-sectional view of a phase difference detection pixel according to an exemplary embodiment of the present disclosure. Figure 16 is a schematic cross-sectional view of a phase difference detection pixel according to a comparative example. FIG. 17 is a graph showing the simulation results of a phase difference detection pixel according to an exemplary embodiment of the present disclosure and a phase difference detection pixel according to a comparative example. Specific details for implementing the invention

[0011] Hereinafter, embodiments of the present invention will be described in detail with reference to the attached drawings. In the drawings below, like reference numerals indicate like components, and the size of each component in the drawings may be exaggerated for clarity and convenience of explanation. Furthermore, the embodiments described below are merely illustrative, and various modifications are possible from such embodiments.

[0013] We will now describe the configuration of a solid imaging device (1) according to one embodiment of the present invention.

[0014] Here, for convenience of explanation, an XYZ orthogonal coordinate system is established in the solid imaging device (1). The direction parallel to the X-axis within a predetermined plane is designated as the X-axis direction. The direction parallel to the Y-axis, which is orthogonal to the X-axis within a predetermined plane, is designated as the Y-axis direction. The direction parallel to the Z-axis, which is orthogonal to each of the X-axis and Y-axis, is designated as the Z-axis direction. In this embodiment, the predetermined plane is parallel to the horizontal plane in the XY plane, and the Z-axis is a vertical direction orthogonal to the predetermined plane. Accordingly, the Z-axis direction corresponds to the stacking direction (thickness direction) of each element constituting the solid imaging device (1), and the X-axis direction and Y-axis direction correspond to the plane direction orthogonal to the stacking direction.

[0015] The solid-state imaging device (1) may include a pixel (10), a phase difference detection pixel (20), and a chip substrate (100). The solid-state imaging device (1) may be composed of a CMOS image sensor.

[0016] A solid-state imaging device (1) may include a plurality of pixels (10) that output a pixel signal (e.g., an image signal) on a chip substrate (10) as illustrated in FIG. 1, and a pixel array (110) that includes one or more phase difference detection pixels (20) capable of detecting a phase difference on the upper surface. The structure of the pixels (10) and the phase difference detection pixels (20) may be different. In some embodiments, the pixel array (110) includes a plurality of phase difference detection pixels (20) excluding the pixels (10), and the plurality of phase difference detection pixels (20) may detect a phase difference on the upper surface and also output an image signal. A solid-state imaging device (1) includes a control circuit (120) that generates an operation signal for operating each part, a vertical driving circuit (130) that can scan in a vertical direction (Y-axis direction in the drawing) which is a second direction orthogonal to the first direction of each pixel (10) and controls the output of a pixel signal according to the amount of light received by each pixel (10), a horizontal driving circuit (140) that outputs a scanning pulse in a horizontal direction (X-axis direction in the drawing) which is a first direction, a column signal processing circuit (150) that processes a pixel signal output from each pixel (10) to generate an image signal, a vertical signal line (160) that transmits a pixel signal generated from each pixel (10) to the column signal processing circuit (150), a horizontal signal line (170) that outputs an image signal from the column signal processing circuit (150), and an output circuit (180) that processes the image signal received through the horizontal signal line (170) and outputs a signal after processing. In addition, in FIG. 1, the area enclosed by the thick line within the pixel array (110) represents the phase difference detection pixel (20).

[0017] Also, the center (110a) of the pixel array (110) refers to a predetermined range extending from the center of the pixel array (110) toward the outer edge as shown in FIG. 1, and the peripheral part (110B) of the pixel array (110) refers to a predetermined range extending from the outermost edge of the pixel array (110) toward the center.

[0018] A chip substrate (100) is formed of silicon (Si) or the like, and a pixel (10) and a phase difference detection pixel (20) are formed on the substrate. The chip substrate (100) comprises a photoelectric conversion unit of the pixel (10) and a photoelectric conversion unit (25) of the phase difference detection pixel (20). On the chip substrate (100), a pixel transistor or a wiring layer is formed on the opposite side from the incident surface of light (hereinafter also referred to as "incident light (L)") incident on the solid-state imaging device (1). The chip substrate (100) outputs a pixel signal, which is converted into an electrical signal from the incident light (L) received from the pixel (10) and the phase difference detection pixel (20), to a control circuit (120), etc.

[0019] In addition, regarding components other than the phase difference detection pixel (20) formed in the pixel array (110), the solid-state imaging device (1) may arbitrarily and selectively adopt configurations known in the technical field of solid-state imaging devices. Accordingly, in this specification, the description of components other than the phase difference detection pixel (20) is appropriately omitted.

[0020] FIG. 2 shows an enlarged plan view of a portion of the solid imaging device (1) of the present embodiment cut in the horizontal direction (cut in the XY plane). FIG. 3 shows a schematic cross-sectional view of the solid imaging device (1) cut along the line A1-A1 shown in FIG. 2.

[0021] The pixel (10) may include a red pixel (10R), a green pixel (10G), and a blue pixel (10B) as illustrated in FIG. 2. The pixel (10) is arranged in a two-dimensional shape (e.g., in a matrix shape) on a chip substrate (100). The pixel array (110) may arrange the pixel (10) and the phase difference detection pixel (20) in a Bayer pattern. However, this is exemplary and may include a yellow filter, a magenta filter, and a cyan filter. Also, the arrangement position of the pixel (10) and the phase difference detection pixel (20) in the pixel array (110) or the number of each pixel can be arbitrarily set.

[0022] FIG. 4 shows a schematic cross-sectional view of a solid imaging device (1) cut along the line A2-A2 shown in FIG. 2. The phase difference detection pixel (20) may include an on-chip lens (21), a flattening layer (22), a light-transmitting layer (23), an anti-reflection layer (24), a photoelectric conversion unit (25), a light-transmitting layer separation wall (30), a pixel separation wall (40), and a light separation wall (50), as shown in FIG. 3 and FIG. 4. The phase difference detection pixel (20) is partitioned by the light-transmitting layer separation wall (30) or the pixel separation wall (40) and is separated independently from each of the adjacent pixels (10) or phase difference detection pixels (20).

[0023] The phase difference detection pixel (20) has a structure in which the photoelectric conversion unit (25) is divided into multiple parts by a boundary separation wall (41). The phase difference detection pixel (20) can detect a phase difference from the difference of pixel signals based on the amount of charge generated by the multiple photoelectric conversion units (25). Based on the detected phase difference, the amount of focus deviation is calculated, and autofocus can be realized by moving the camera lens based on the result of this calculation. Therefore, the imaging device equipped with the solid-state imaging device (1) does not require a mechanism dedicated to autofocus and can focus on the subject based on the phase difference of the light incident on the phase difference detection pixel (20).

[0024] The on-chip lens (21) is formed on the flattening layer (22). The on-chip lens (21) is arranged in correspondence with each phase difference detection pixel (20). For example, the on-chip lens (21) is arranged two-dimensionally in a plane (for example, in a matrix shape). The on-chip lens (21) has a convex shape and a predetermined radius of curvature so that incident light (IL) is concentrated at the photoelectric conversion unit (25). The on-chip lens (21) can be formed using an organic material such as, for example, a styrene-based resin, an acrylic-based resin, a styrene-acrylic copolymer resin, or a siloxane-based resin.

[0025] A flattening layer (22) is formed between the on-chip lens (21) and the light-transmitting layer (23). The flattening layer (22) has a high transmittance for incident light (L) to the photoelectric conversion unit (25) and provides a flat surface with respect to the on-chip lens (21). The flattening layer (22) may be formed from an organic material, such as a resin, for example.

[0026] The light-transmitting layer (23) is positioned between the flattening layer (22) and the photoelectric conversion unit (25) and arranged two-dimensionally (e.g., in a matrix shape) to correspond to each unit pixel. The light-transmitting layer (23) can be formed by including a pigment or dye of a desired color in a resin with low light absorption. The refractive index of the light-transmitting layer (23) can be 1.6 or higher and 1.8 or lower.

[0027] The light-transmitting layer (23) has the function of transmitting light of a specific wavelength in the visible light region. The light-transmitting layer (23) can function as a color filter that transmits one of red light, green light, or blue light as light of a specific wavelength and absorbs other light. In addition, the light-transmitting layer (23) can function as a so-called white filter that transmits light of approximately the entire visible light region as light of a specific wavelength.

[0028] A light-blocking light-transmitting layer separation wall (30) is disposed at the boundary between the light-transmitting layer (23) and another adjacent light-transmitting layer (23). As a result, the light-transmitting layer (23) is separated pixel by pixel from adjacent pixels (10) or phase difference detection pixels (20).

[0029] The anti-reflection layer (24) is disposed between the light-transmitting layer (23) and the photoelectric conversion unit (25). The anti-reflection layer (24) is formed by alternately stacking a high-refractive-index layer (24a) made of a high-refractive-index material (e.g., silicon nitride (SiN), hafnium oxide (HfO), tantalum oxide (TaO), titanium oxide (TiO), etc.) and a low-refractive-index layer (24b) made of a low-refractive-index material (silicon oxide (SiO2), aluminum oxide (AlO), etc.).

[0030] The anti-reflection layer (24) can be formed by alternately stacking a low refractive index layer (24b) and a high refractive index layer (24a) from the incident side of the incident light (L), as shown in FIGS. 3 and 4. The high refractive index layer (24a) can be formed from the same material or a different material in each stacked layer. The low refractive index layer (24b) can be formed from the same material or a different material in each stacked layer. The anti-reflection layer (24) shown in FIG. 3 has a stacked structure formed in order from the incident side of the incident light (L) to the low refractive index layer (24b), the high refractive index layer (24a), and the low refractive index layer (24b). Additionally, the anti-reflection layer (24) has no limit on the number of stacked high refractive index layers (24a) and low refractive index layers (24b), but at least the top and bottom layers may be low refractive index layers (24b).

[0031] The photoelectric conversion unit (25) converts the transmitted light of the photoelectric conversion target that has traveled to the photoelectric conversion unit (25) among the incident light (L) into an electrical signal. The photoelectric conversion unit (25) has a structure in which the photoelectric conversion unit (25) is divided into multiple parts by a boundary separation wall (41). The photoelectric conversion unit (25) may include, for example, at least one of a photodiode, a phototransistor, a photogate, a pinned photodiode, an organic photodiode, a quantum dot, and combinations thereof, but is not limited thereto.

[0032] The light-transmitting layer separation wall (30) is formed to surround the light-transmitting layer (23) among the phase difference detection pixels (20). The light-transmitting layer separation wall (30) is arranged in a grid pattern when viewed from a plane and forms a boundary between adjacent pixels (10) to divide and separate each layer into a predetermined size. The light-transmitting layer separation wall (30) has the function of preventing vignetting of incident light (L) incident on the phase difference detection pixels (20) and the function of blocking incoming light from adjacent pixels (10). Accordingly, the light-transmitting layer separation wall (30) can be formed to have a height and width that satisfy these functions. The light-transmitting layer separation wall (30) can be composed of a dielectric material with low light absorption, such as silicon oxide (SiO2) or silicon nitride (SiN).

[0033] A light-blocking portion (31) may be formed between the light-transmitting layer separation wall (30) and the anti-reflection layer (24). The light-blocking portion (31) may be formed to surround the light-transmitting layer (23). By placing the light-blocking portion (31) between adjacent pixels (10) or phase difference detection pixels (20), crosstalk between adjacent pixels can be suppressed, thereby further improving the precision during phase difference detection. The light-blocking portion (31) may be formed from a metal material including, for example, titanium nitride (TiN), titanium (Ti), tungsten (W), aluminum (Al), molybdenum (Mo), nickel (Ni), etc.

[0034] The pixel separation wall (40) can be formed as a Deep Trench Isolation (DTI). As shown in FIGS. 2, 3, and 4, the pixel separation wall (40) is formed to surround the photoelectric conversion unit (25) of the phase difference detection pixel (20) by being positioned between the photoelectric conversion unit (25) of the phase difference detection pixel (20) and the photoelectric conversion unit (25) of another pixel adjacent to it. In this way, the photoelectric conversion unit (25) of the phase difference detection pixel (20) is separated individually for each pixel.

[0035] The pixel separation wall (40) may have a boundary separation wall (41) that separates the photoelectric conversion unit (25) into multiple parts. The boundary separation wall (41) separates the photoelectric conversion unit (25) into a predetermined number of parts so that the photoelectric conversion unit (25) can detect the upper surface phase difference within the phase difference detection pixel (20).

[0036] In the solid-state imaging element (1) according to the present embodiment, as shown in FIGS. 3 and 4, a light separation wall (50) is formed between the on-chip lens (21) and the photoelectric conversion unit (25).

[0037] The light separation wall (50) separates the light-transmitting layer (23) according to the number of divisions of the photoelectric conversion unit (25). The light separation wall (50) is laminated on the anti-reflection layer (24) as shown in FIGS. 3 and 4 and can be arranged parallel to the boundary separation wall (41) in a planar direction. To clarify the configuration of the light separation wall (50), dotted lines are drawn at the boundary positions with the light-transmitting layer separation wall (30) in each drawing as needed, but the light-transmitting layer separation wall (30) and the light separation wall (50) can be formed as a single unit.

[0038] FIG. 5 shows a plan view of a solid imaging device (1) cut along the line A3-A3 shown in FIG. 3. FIG. 6 shows a plan view of a solid imaging device (1) cut along the line A4-A4 shown in FIG. 3. FIG. 7 shows a plan view of a solid imaging device (1) cut along the line A5-A5 shown in FIG. 3. The light separation wall (50) is formed from the anti-reflection layer (24) side of the light-transmitting layer (23) toward the on-chip lens (21) as shown in FIG. 5 and FIG. 6. The light separation wall (50) can be formed along the formation position of the boundary separation wall (41) of the photoelectric conversion unit (25) as shown in FIG. 5, FIG. 6 and FIG. 7.

[0039] The light separation wall (50) can be formed from a dielectric material such as SiO2 (silicon oxide) which has a lower amount of light absorption than the light-transmitting layer (23). Here, an indicator of "amount of light absorption" can be, for example, an attenuation coefficient. An attenuation coefficient is a value indicating how much light is absorbed when light is incident on a material; the larger this value, the greater the light absorption and the stronger the incident light is attenuated.

[0040] As shown in FIGS. 4 and 5, the light separation wall (50) is divided at the center of the phase difference detection pixel (20) so as not to obstruct the optical path of the incident light (L) incident on the center of the phase difference detection pixel (20). That is, the light separation wall (50) may not be formed at the center of the phase difference detection pixel (20). Thus, the incident light (L) incident on the center of the phase difference detection pixel (20) is directly incident on the light-transmitting layer (23).

[0041] The solid-state imaging device (1) has a light separation wall (50) that partitions a light-transmitting layer (23) between an on-chip lens (21) and a photoelectric conversion unit (25). The light-transmitting layer (23) with a high refractive index, the light-transmitting layer separation wall (30) with a low refractive index, and the light separation wall (50) form an optical waveguide structure that guides incident light (L) to the photoelectric conversion unit (25) as shown in FIG. 8a. The optical waveguide structure can guide the optical path of the incident light (L) to one of the separated photoelectric conversion units (25) before the incident light (L) is incident on the photoelectric conversion unit (25).

[0042] FIG. 8b is a schematic diagram illustrating the light intensity distribution of incident light (L) incident on a light-transmitting layer (23) cut along the line B1-B1 of FIG. 8a. FIG. 8c is a schematic diagram illustrating the light intensity distribution of incident light (L) incident on a photoelectric conversion unit (25) cut along the line B2-B2 of FIG. 8a. In FIG. 8b and FIG. 8c, the light intensity distribution is represented by an ellipse with dot hatching, and the shade of the dots indicates the degree of light intensity. Also, for convenience of explanation, cross-sectional hatching in each figure has been omitted.

[0043] The solid-state imaging device (1) can skew the light intensity distribution to the photoelectric conversion unit (25) by means of an optical waveguide structure as shown in FIG. 8b and FIG. 8c. Accordingly, the separation ratio in the phase difference detection pixel (20) of the solid-state imaging device (1) is improved.

[0044] FIGS. 9a to 9f illustrate configuration examples of a phase difference detection pixel (20). FIGS. 9f and 9f illustrate a light-transmitting layer (23) ((a) in the drawings) and a photoelectric conversion unit (25) ((b) in the drawings) in an orderly fashion so that the structure of the phase difference detection pixel (20) becomes clear. Additionally, the phase difference detection pixel (20) may adopt a configuration other than that shown in FIGS. 9a to 9f. In each embodiment shown in FIGS. 9a to 9f, the X-axis direction may be the second direction and the Y-axis direction may be the first direction.

[0045] The light separation wall (50) can be formed to follow the boundary separation wall (41) in the case where the photoelectric conversion unit (25) is divided into two upper and lower sections in the first direction (X-axis direction) as shown in FIG. 9a.

[0046] The light separation wall (50) can be formed to follow the boundary separation wall (41) in the case where the photoelectric conversion unit (25) is divided into two parts, left and right, in the vertical direction (Y-axis direction) which is the second direction, as shown in FIG. 9b.

[0047] The light separation wall (50) can be formed to follow the boundary separation wall (41) in the case of a structure that divides the photoelectric conversion unit (25) into four parts in the first direction (X-axis direction) and the second direction (Y-axis direction), as shown in FIG. 9c.

[0048] As illustrated in FIG. 9d, when the phase difference detection pixel (20) has a length corresponding to one pixel (10) in the horizontal direction (X-axis direction) which is the first direction (e.g., 1 times the pixel pitch), and a region having a length corresponding to two pixels in the vertical direction which is the second direction (e.g., 2 times the pixel pitch), the light separation wall (50) can be formed along the pixel separation wall (40) to fit the size of the photoelectric conversion unit (25).

[0049] As illustrated in FIG. 9e, when the phase difference detection pixel (20) has a length corresponding to two pixels (10) in the horizontal direction (X-axis direction) which is the first direction and a length corresponding to one pixel (10) in the vertical direction (Y-axis direction) which is the second direction, the light separation wall (50) can be formed along the pixel separation wall (40) to match the size of the photoelectric conversion unit (25).

[0050] The light separation wall (50) can be formed along the pixel separation wall (40) to match the size of the photoelectric conversion unit (25) when the phase difference detection pixel (20) has a length corresponding to two pixels (10) in the horizontal direction (X-axis direction) which is the first direction as shown in FIG. 9f and a region (pixel size) having a length corresponding to two pixels (10) in the vertical direction (Y-axis direction) which is the second direction.

[0051] The light separation wall (50) illustrated in FIGS. 9a to 9c is formed to be shorter than the boundary separation wall (41) when viewed from a planar perspective, assuming that the light intensity distribution when passing through the light transmission layer is wider than the light intensity distribution at the surface of the photoelectric conversion unit (25) of the light collected by the on-chip lens (21). However, depending on the length of the boundary separation wall (41), the length of the light separation wall (50) and the length of the boundary separation wall (41) may be the same.

[0052] FIG. 10a is a schematic diagram of a phase difference detection pixel (20a) positioned at the center side of a pixel array according to an exemplary embodiment of the present disclosure, and FIG. 10b is a schematic diagram of a phase difference detection pixel (20b) positioned at the peripheral side of a pixel array according to an exemplary embodiment of the present disclosure.

[0053] The phase difference detection pixels (20a, 20b) have different pupil correction amounts at the center (110a) and peripheral (110b) sides of the pixel array (110). Accordingly, the placement, width, height, etc., of the light separation walls (50a, 50b) within the pixels can be appropriately changed according to the pupil correction amount, as illustrated in FIG. 10a and FIG. 10b. At least one of the height and width of the light separation walls (50a, 50b) can be formed differently depending on the angle of incidence of light. Additionally, the placement position of the light separation walls (50a, 50b) within the phase difference detection pixels (20a, 20b) can be formed differently depending on the angle of incidence of light.

[0054] In some embodiments, in a phase difference detection pixel (20a) positioned at the center (110a) of the pixel array (110), the height of the light separation wall (50a) is equal to the height of the light-transmitting layer separation wall (30), and in a phase difference detection pixel (20b) positioned at the periphery (110b) of the pixel array (110), the height of the light separation wall (50b) may be lower than the height of the light-transmitting layer separation wall (30). In some embodiments, the height of the light separation walls (50a, 50b) may decrease as the position of the phase difference detection pixel (20a, 20b) moves further away from the center (110a) of the pixel array (110).

[0055] In some embodiments, in a phase difference detection pixel (20a) positioned at the center (110a) of the pixel array (110), the width of the light separation wall (50a) is equal to the width of the light-transmitting layer separation wall (30), and in a phase difference detection pixel (20b) positioned at the periphery (110b) of the pixel array (110), the width of the light separation wall (50b) may be narrower than the width of the light-transmitting layer separation wall (30). In some embodiments, the width of the light separation walls (50a, 50b) may become narrower as the position of the phase difference detection pixel (20a, 20b) moves further away from the center (110a) of the pixel array (110).

[0056] In some embodiments, in a phase difference detection pixel (20a) positioned on the central side (110a) of the pixel array (110), the light separation wall (50a) is positioned at the center of the pixel, and in a phase difference detection pixel (20b) positioned on the peripheral side (110b) of the pixel array (110), the light separation wall (50b) may be positioned slightly offset from the center of the pixel towards the center of the pixel array (110). In some embodiments, the position of the light separation wall (50a, 50b) may be positioned further offset toward the center of the pixel array (110) as the position of the phase difference detection pixel (20a, 20b) moves further away from the central side (110a) of the pixel array (110).

[0057] As illustrated in FIG. 10b, the height of the light separation wall (50b) can be formed lower than that of the light-transmitting layer separation wall (30) based on the pupil correction amount. Additionally, the width of the light separation wall (50b) can be formed narrower than that of the light-transmitting layer separation wall (30), so that the light separation wall (50b) can be positioned slightly to the left (center side of the pixel array (110)) in accordance with the pupil correction amount of the on-chip lens (21). In addition, in FIG. 10a and FIG. 10b, the height of the light separation wall (50a, 50b) is the thickness of the light separation wall (50a, 50b) indicated by the arrow (A1) in the drawing, and the width of the light separation wall (50a, 50b) is the width in the direction orthogonal to the extension direction of the light separation wall (50a, 50b) indicated by the arrow (A2) in the drawing. In this way, the light separation wall (50) is formed to match the image height (e.g., radius from the center of the pixel array (110)) or pupil correction amount of the phase difference detection pixel (20) in the solid imaging device (1), so that the light separation wall (50) becomes an optimal structure for the incident angle of the incident light (L) and can effectively improve the separation ratio.

[0058] Hereinafter, embodiments of the light separation wall (50) will be described. The embodiments described below may be appropriately combined within the scope of the technical concept of the present disclosure.

[0059] FIGS. 11a to 11c illustrate a solid imaging device (1) equipped with a light separation wall (50A) according to an exemplary embodiment of the present disclosure. FIG. 11a is a schematic cross-sectional view of a solid imaging device (1) equipped with a light separation wall (50A) according to an exemplary embodiment of the present disclosure. FIG. 11b is a schematic cross-sectional view of a solid imaging device (1) cut along the line C1-C1 of FIG. 11a. FIG. 11c is a schematic cross-sectional view of a solid imaging device (1) cut along the line C2-C2 of FIG. 11b. Additionally, FIG. 11c omits the illustration of a configuration positioned below the light separation wall (50A) for convenience of explanation.

[0060] If the height of the light separation wall (50) is formed at a height where light collection by the on-chip lens (21) is not sufficiently achieved, there is a possibility that the incident light (L) may be obstructed. To prevent this, as shown in FIG. 11a, the height of the light separation wall (50A) may be lower than the height of the light-transmitting layer separation wall (30). Additionally, as shown in FIG. 11b and FIG. 11c, the light separation wall (50A) is formed in a divided form at the center of the phase difference detection pixel (20), thereby suppressing the blockage of the optical path of the incident light (L) incident on the center of the pixel. By employing the light separation wall (50A) of this embodiment, the solid-state imaging device (1) can improve the separation ratio while suppressing the reduction in sensitivity caused by the light separation wall (50A).

[0061] FIGS. 12a to 12c illustrate a solid imaging device (1) equipped with a light separation wall (50B) according to an exemplary embodiment of the present disclosure. FIG. 12a is a schematic cross-sectional view of a solid imaging device (1) equipped with a light separation wall (50B) according to an exemplary embodiment of the present disclosure. FIG. 12b is a schematic cross-sectional view of a solid imaging device (1) cut along the line D1-D1 of FIG. 12a. FIG. 12c is a schematic cross-sectional view of a solid imaging device (1) cut along the line D2-D2 of FIG. 12b. Additionally, FIG. 12c omits the illustration of a configuration positioned below the light separation wall (50B) for convenience of explanation.

[0062] The height of the light separation wall (50B) may be lower than the height of the light-transmitting layer separation wall (30) as shown in FIG. 12a. Additionally, as shown in FIG. 12b and FIG. 12c, if the height of the light separation wall (50B) is sufficiently low so as not to block the optical path of the incident light (L), the light separation wall (50B) may be formed continuously without being divided at the pixel center of the phase difference detection pixel (20). That is, the light separation wall (50B) has a structure that terminates the phase difference detection pixel (20) as shown in FIG. 12b and FIG. 12c. By employing the light separation wall (50B) of this embodiment, the solid-state imaging device (1) can improve the separation ratio while suppressing the reduction in sensitivity caused by the light separation wall (50B).

[0063] FIGS. 13a to 13c illustrate a solid imaging device (1) equipped with a light separation wall (50C) according to an exemplary embodiment of the present disclosure. FIG. 13a is a schematic cross-sectional view of a solid imaging device (1) equipped with a light separation wall (50C) according to an exemplary embodiment of the present disclosure. FIG. 13b is a schematic cross-sectional view of a solid imaging device (1) cut along the line E1-E1 of FIG. 13a. FIG. 13c is a schematic cross-sectional view of a solid imaging device (1) cut along the line E2-E2 of FIG. 13b. Additionally, FIG. 13c omits the illustration of a configuration positioned below the light separation wall (50C) for convenience of explanation.

[0064] The light separation wall (50C) of the present embodiment is a modified example of the light separation wall (50B) of FIGS. 12a to 12c, and as shown in FIGS. 13a and 13b, the width of the light separation wall (50C) may be narrower than the width of the light-transmitting layer separation wall (30). Also, as shown in FIG. 13a, the height of the light separation wall (50C) may be lower than the height of the light-transmitting layer separation wall (30). Additionally, as shown in FIG. 13b and 13c, the light separation wall (50C) may be formed continuously without being divided at the pixel center of the phase difference detection pixel (20). The width of the light separation wall (50) may be appropriately set according to the specifications of the solid-state imaging device (1), such as the pixel size of the phase difference detection pixel (20) or the image height from the center of the pixel array (110). The solid imaging device (1) can improve the separation ratio while suppressing the decrease in sensitivity caused by the light separation wall (50C) by employing the light separation wall (50C) of the present embodiment.

[0065] FIGS. 14a and FIGS. 14b illustrate a solid imaging device (1) equipped with a light separation wall (50D) according to an exemplary embodiment of the present disclosure. FIG. 14a is a schematic cross-sectional view of a solid imaging device (1) equipped with a light separation wall (50D) according to an exemplary embodiment of the present disclosure. FIG. 14b is a schematic cross-sectional view of a solid imaging device (1) cut along the line F1-F1 of FIG. 14a.

[0066] In the solid-state imaging device (1), the light-transmitting layer separation wall (30) and the light-separating wall (50D) can be formed using a cavity. The cavity has a lower refractive index than the light-transmitting layer (23) and can be formed as an air layer or a vacuum layer with a refractive index of 1. The solid-state imaging device (1) can form an optical waveguide structure by means of the light-transmitting layer (23) with a high refractive index and the light-transmitting layer separation wall (30) or light-separating wall (50D) with a low refractive index, thereby trapping incident light (L) within the light-transmitting layer (23). The solid-state imaging device (1) can improve the separation ratio by employing the light-separating wall (50D) of this embodiment.

[0067] As described above, a solid-state imaging device (1) according to embodiments of the present disclosure is a device having a plurality of pixels (10) that generate an electrical signal according to incident light (L), and a pixel array (110) in which one or more phase difference detection pixels (20) are arranged in a matrix. The phase difference detection pixel (20) comprises a photoelectric conversion unit (25), an on-chip lens (21) disposed on the incident side of the incident light (L) in the photoelectric conversion unit (25), a light-transmitting layer (23) that transmits light of a specific wavelength in the incident light (L), an anti-reflection layer (24) laminated on the photoelectric conversion unit (25), a light-transmitting layer separation wall (30) disposed between the light-transmitting layer (23) of another pixel adjacent to the light-transmitting layer (23), a pixel separation wall (40) disposed between the photoelectric conversion unit (25) of another pixel adjacent to the photoelectric conversion unit (25), and a photoelectric element surrounded by the pixel separation wall (40). A boundary separation wall (41) that separates the conversion unit (25) into multiple parts, and a light separation wall (50) disposed between the on-chip lens (21) and the photoelectric conversion unit (25), wherein the light separation wall (50) is disposed parallel to the extension direction of the boundary separation wall (41) in a planar direction orthogonal to the stacking direction in the phase difference detection pixel (20).

[0068] With this configuration, the solid imaging device (1) is provided with a light separation wall (50) to form an optical waveguide structure that guides incident light (L) to a photoelectric conversion unit (25) from a light-transmitting layer (23) with a high refractive index, a light-transmitting layer separation wall (30) with a low refractive index, and a light separation wall (50). Accordingly, the solid imaging device (1) appropriately distributes the optical path of the incident light (L) before it enters the photoelectric conversion unit (25) by the aforementioned optical waveguide structure, thereby improving the separation ratio.

[0069] Hereinafter, simulation results evaluating the separation ratio of phase difference detection pixels of a solid-state imaging device according to an exemplary embodiment of the present disclosure and a solid-state imaging device according to a comparative example are described. For the simulation, the quantum efficiency within the photoelectric conversion unit of the green pixel was calculated by the Finite-Difference Time-Domain method (FDTD) using Rsoft (manufactured by Synopsys). The wavelength of the incident light was 530 nm, and it was incident at an incident angle of 10°.

[0070] As illustrated in FIG. 15, the phase difference detection pixel (20) according to an embodiment of the present disclosure includes a light separation wall (50) disposed on an anti-reflection layer (24). The height of the light separation wall (50) is lower than half the height of the light-transmitting layer separation wall. The widths of the light separation wall (50) and the light-transmitting layer separation wall (30) are each set to a length of one-tenth of the pixel size. The light separation wall (50) is disposed parallel to the boundary separation wall (41) in a plane direction orthogonal to the stacking direction.

[0071] The phase difference detection pixel (20') according to the comparative example does not include a light separation wall (50) as shown in FIG. 16. The other structure of the phase difference detection pixel (20') according to the comparative example is the same as the phase difference detection pixel (20) according to the embodiment of the present disclosure.

[0072] FIG. 17 shows a graph representing the simulation results of the separation ratio of a phase difference detection pixel (20) according to an embodiment of the present disclosure and a phase difference detection pixel (20') according to a comparative example. As shown in FIG. 17, it was confirmed that the separation ratio of the embodiment in which a light separation wall is formed is improved compared to the comparative example in which a light separation wall is not formed.

[0073] From the above results, if a light separation wall is formed between the on-chip lens of the phase difference detection pixel and the photoelectric converter in a solid-state imaging device, the optical path of the incident light can be appropriately distributed before the incident light enters the photoelectric converter. Therefore, the light separation wall is effective in improving the separation ratio in the phase difference detection pixel. Explanation of the symbols

[0074] 1 solid-state imaging device, 10 pixels, 10R red pixel, 10G green pixel, 10B blue pixels, 20 phase detection pixels, 21 On-chip lens, 22 Planarization layer, 23 Light-transmitting layer, 24 Anti-reflective layer, 24a high refractive index layer, 24b low refractive index layer, 25 Photoelectric conversion unit, 30 Light-transmitting layer separation wall, 31 light-blocking section, 40 pixel separation wall, 41 boundary partition, 50, 50A, 50B, 50C, 50D, 50E optical partition, 100 chip substrates, 110 pixel arrays, The center of the 110a pixel array, the periphery of the 110b pixel array, 120 control circuit, 130 vertical drive circuit, 140 Horizontal driving circuit, 150 Column signal processing circuit, 160 vertical signal line, 170 horizontal signal line, 180 output circuit, L incident light.

Claims

Claim 1 A solid-state imaging device comprising a plurality of pixels that generate an image signal according to incident light, and a pixel array in which one or more phase difference detection pixels are arranged in a matrix, wherein the phase difference detection pixels include: a photoelectric conversion unit; an on-chip lens disposed on the incident side of the incident light in the photoelectric conversion unit; a light-transmitting layer that transmits light of a specific wavelength in the incident light; an anti-reflection layer laminated on the photoelectric conversion unit; a light-transmitting layer separation wall disposed between the light-transmitting layer and the light-transmitting layer of another pixel adjacent to each other; a pixel separation wall disposed between the photoelectric conversion unit and the photoelectric conversion unit of another pixel adjacent to each other; a boundary separation wall that separates the photoelectric conversion unit surrounded by the pixel separation wall into a plurality of parts; and a light separation wall disposed between the on-chip lens and the photoelectric conversion unit, wherein the light separation wall is disposed parallel to the extension direction of the boundary separation wall on a plane orthogonal to the stacking direction of the phase difference detection pixel. Claim 2 A solid-state imaging device according to claim 1, wherein the light separation wall is composed of a dielectric or cavity having a light absorption amount less than that of the light-transmitting layer. Claim 3 A solid-state imaging device according to claim 1, wherein the light separation wall is composed of a material with a lower refractive index than the light-transmitting layer. Claim 4 A solid-state imaging device according to claim 1, wherein the height of the light separation wall is lower than the height of the light-transmitting layer separation wall. Claim 5 A solid-state imaging device according to claim 1, wherein the light separation wall is divided at the pixel center of the phase difference detection pixel. Claim 6 A solid-state imaging device according to claim 1, wherein the light separation wall terminates the light-transmitting layer on the plane, and the height of the light separation wall is lower than the height of the light-transmitting layer separation wall. Claim 7 A solid-state imaging device according to claim 1, wherein the width of the light separation wall is narrower than the width of the light-transmitting layer separation wall. Claim 8 A solid-state imaging device according to claim 1, wherein at least one of the height and width of the light separation wall differs depending on the angle of incidence of light. Claim 9 A solid-state imaging device according to claim 1, wherein the position of the light separation wall within the phase difference detection pixel varies depending on the angle of incidence of light. Claim 10 A solid-state imaging device according to claim 1, wherein the size of the area of ​​the phase difference detection pixel is the same as the size of the area of ​​the pixel.

Images