Image sensor

Abstract

An image sensor is disclosed. An image sensor according to at least one of various embodiments of the present disclosure comprises a pixel structure including: a lens part for receiving external light; and a body part including a plurality of backside scattering technology (BST) structures for scattering light that has passed through the lens part, a deep trench isolation (DTI) structure disposed outside of the outermost BST structure of the plurality of BST structures, and a Si substrate that absorbs light scattered through the plurality of BST structures and the DTI structure, wherein the length of the plurality of BST structures can be determined by considering a period indicating the interval between the BST structures.

Description

image sensor

[0001] The present disclosure relates to an image sensor, and more particularly, to an image sensor having improved at least one of quantum efficiency (QE) and optical efficiency (OE).

[0002] An image sensor is a device that reads information from a subject and converts it into an electrical image signal.

[0003] There are various types of image sensors, such as CCD (Charge Coupled Device) image sensors, CMOS (Complementary Metal Oxide Semiconductor) image sensors, and NIR (Near Infrared) image sensors.

[0004] As mentioned above, CCD image sensors and CMOS image sensors are devices that detect light, particularly visible light, entering through a lens and generate an electrical signal, such as an image (digital signal). An NIR image sensor is a device that detects light, particularly near-infrared light, entering through a lens and generates an electrical signal (image).

[0005] Meanwhile, light incident through the lens of the image sensor undergoes refractions, reflections, and scattering inside the lens after passing through the lens. Therefore, in order to increase the efficiency of the image sensor, research is needed on processing the light incident through the lens.

[0006] At least one of the various embodiments of the present disclosure is directed to providing an image sensor having improved at least one of quantum efficiency (QE) and optical efficiency (OE).

[0007] At least one of the various embodiments of the present disclosure further aims to provide various Backside Scattering Technology (BST) structures to improve the efficiency(s) of the image sensor.

[0008] The technical problems according to the present disclosure are not limited to those described in this article, but include those that can be understood through the description of the invention described below.

[0009] An image sensor according to at least one of various embodiments of the present disclosure includes a pixel structure including a lens unit that receives external light, a plurality of BST (Backside Scattering Technology) structures for scattering light passing through the lens unit, and a DTI (Deep Trench Isolation) structure arranged outside an outermost BST structure among the plurality of BST structures, and a body unit including a Si substrate that absorbs light scattered through the plurality of BST structures and the DTI structure, wherein the length of the plurality of BST structures can be determined in consideration of a period representing a gap between each of the BST structures.

[0010] According to at least one of the various embodiments of the present disclosure, the first BST structure among the plurality of BST structures may be formed in a closed loop structure to limit a scattering path of light entering through the lens unit.

[0011] According to at least one of the various embodiments of the present disclosure, at least one second BST structure among the plurality of BST structures may be formed inside the first BST structure.

[0012] According to at least one of the various embodiments of the present disclosure, some of the second BST structures may be formed in an area including a center point of the pixel structure.

[0013] According to at least one of the various embodiments of the present disclosure, the remainder of the second BST structure may be formed at a position at a predefined interval from a portion formed in an area including a center point of the pixel structure.

[0014] According to at least one of the various embodiments of the present disclosure, each of the BST structures may be formed in a peripheral area surrounding a center point of the pixel structure.

[0015] According to at least one of the various embodiments of the present disclosure, each of the BST structures may be formed in a cubic shape.

[0016] According to at least one of the various embodiments of the present disclosure, at least two faces of a cube forming each of the BST structures may overlap faces of a cube forming another BST structure.

[0017] According to at least one of the various embodiments of the present disclosure, the width of each BST structure can be determined by taking into consideration the refractive index of the coating layer and the Si substrate.

[0018] According to at least one of the various embodiments of the present disclosure, the spacing of each BST structure is determined by considering the diffraction effect of light entering through the lens unit, and may use an integer multiple of the wavelength sensed by the photodetector.

[0019] According to at least one of the various embodiments of the present disclosure,

[0020] First, there is an advantage in that it can provide an image sensor with improved at least one of quantum efficiency and optical efficiency.

[0021] Second, there is an advantage in that an image sensor can be provided with minimized crosstalk when light incident through the lens of the image sensor is scattered by the BST structure.

[0022] The technical effects of the embodiments are not limited to those described in this article, but include those that can be understood through the description of the invention.

[0023] FIG. 1 is a diagram illustrating a structure of a pixel included in an image sensor according to at least one of various embodiments of the present disclosure.

[0024] FIG. 2 is a drawing illustrating a method for manufacturing an image sensor according to at least one of various embodiments of the present disclosure.

[0025] FIGS. 3 and 4 are drawings illustrating a BST structure and a DTI structure according to embodiments of the present disclosure.

[0026] FIG. 5 is a drawing illustrating an example of detailed specifications of a BST structure according to an embodiment of the present disclosure.

[0027] FIG. 6 is a drawing illustrating the scattering effect of the BST structure in relation to the present disclosure.

[0028] FIGS. 7 and 8 are drawings illustrating characteristics and effects of each BST structure according to embodiments of the present disclosure.

[0029] FIGS. 9 and 10 are drawings illustrating characteristics and effects of each DTI structure according to embodiments of the present disclosure.

[0030] FIG. 11 is a diagram illustrating the light efficiency of an image sensor according to an embodiment of the present disclosure.

[0031] FIG. 12 is a drawing illustrating the shape of a BST structure according to another embodiment of the present disclosure.

[0032] FIG. 13 is a diagram illustrating the potential difference in the BST structure of FIG. 12, including the case where there is no BST structure.

[0033] FIG. 14 is a diagram illustrating the light efficiency of an image sensor according to an embodiment of the present disclosure.

[0034] Hereinafter, an invention according to an embodiment for solving the above problem will be described in more detail with reference to the drawings.

[0035] The suffixes "module" and "part" used in the following description are given solely for the convenience of writing this specification and do not impart any particularly significant meaning or role to the components themselves. Therefore, the terms "module" and "part" may be used interchangeably.

[0036] Terms that include ordinal numbers, such as first, second, etc., may be used to describe various components, but the components are not limited by these terms. These terms are used solely to distinguish one component from another.

[0037] Singular expressions include plural expressions unless the context clearly indicates otherwise.

[0038] In this application, it should be understood that terms such as “include,” “have,” or “comprising” are intended to specify the presence of a feature, number, step, operation, component, part, or combination thereof described in the specification, but do not preclude the possibility of the presence or addition of one or more other features, numbers, steps, operations, components, parts, or combinations thereof.

[0039] An image sensor according to various embodiments of the present disclosure is disclosed.

[0040] At this time, the present specification describes image sensors using CMOS (Complementary Metal Oxide Semiconductor) image sensors and NIR (Near-Infrared) image sensors as examples. However, the present disclosure is not limited thereto.

[0041] Meanwhile, in the above, the NIR image sensor is exemplified as a sensor using a wavelength of 940 nm. However, the present disclosure is not limited thereto.

[0042] In particular, the present specification describes a method for improving at least one of the quantum efficiency (QE) and optical efficiency (OE) of an image sensor according to various embodiments of the present disclosure using a pixel structure.

[0043] At this time, for the convenience of explanation, the pixel structure is disclosed using one pixel as an example, but is not limited thereto.

[0044] The aforementioned method for improving the efficiency of the image sensor can be determined by the pixel structure, particularly the Backside Scattering Technology (BST) and Deep Trench Isolation (DTI) structures. This specification primarily describes related content. Therefore, although included in the drawings, parts that are not described in detail or omitted may refer to known technologies.

[0045] In addition, the pixel structure included in the image sensor according to the present disclosure is exemplified by a structure in which a micro lens array (MLA) is employed and included, particularly in relation to the scattering effect according to the BST / DTI structure, but is not necessarily limited thereto.

[0046] In other words, the image sensor according to the present disclosure maximizes the scattering effect through the BST / DTI structure while simultaneously minimizing crosstalk caused by such scattering. To this end, the BST / DTI structure employed in conventional image sensors has suffered from problems such as low efficiency or crosstalk, and this specification proposes a solution to these problems.

[0047] FIG. 1 is a diagram illustrating a structure of a pixel included in an image sensor according to at least one of various embodiments of the present disclosure.

[0048] FIG. 2 is a drawing illustrating a method for manufacturing an image sensor according to at least one of various embodiments of the present disclosure.

[0049] An image sensor according to at least one of various embodiments of the present disclosure includes a pixel structure including a lens portion for receiving external light, a plurality of BST structures for scattering light passing through the lens portion, and a DTI structure disposed outside an outermost BST structure among the plurality of BST structures, and a body portion including a Si substrate for absorbing light scattered through the plurality of BST structures and the DTI structure, wherein the length of the plurality of BST structures can be determined in consideration of a period representing a gap between each of the BST structures.

[0050] Fig. 1 (a) is a side cross-sectional view of a single pixel (100) structure included in an image sensor, and Fig. 1 (b) is a side cross-sectional view enlarged of a portion including a BST structure, particularly, within the side cross-sectional view of Fig. 1 (a).

[0051] Here, the pixel structure illustrated in (a) of Fig. 1 is an example of the pixel structure of the NIR image sensor described above.

[0052] First, referring to (a) of Fig. 1, the pixels (100) included in the image sensor can be formed in a multi-layer structure.

[0053] The first layer (110) receives external light. At this time, the external light can pass through the lens (115) and enter the second layer (120).

[0054] As described above, the lens (115) included in the first layer (110) is preferably a micro lens or micro lens array (MLA) considering the scattering effect. However, the present disclosure is not limited thereto.

[0055] Meanwhile, the lower portion of the lens (115) of the first layer (110) may further include, for example, at least one of an optical flat layer, a color filter, and metal grids arranged between pixels on both sides of the color filter.

[0056] Next, the second layer (120) is a layer in which light received through the first layer (110) is transmitted. Meanwhile, information can be obtained from the transmitted light in the second layer (120).

[0057] The second layer (120) can be formed from a Si body.

[0058] However, for convenience of explanation, it can be divided into an area where light is spread among the Si body, i.e., an area where the BST structure and DTI structure are formed (hereinafter referred to as the '2-1 layer' for convenience of explanation) and another area, i.e., an Si substrate area (hereinafter referred to as the '2-2 layer' for convenience of explanation).

[0059] In the 2-1 layer, as light propagates through the BST structure and the DTI structure, at least one of reflection, absorption, and scattering may occur.

[0060] In particular, in relation to the present disclosure, the characteristics during the light propagation process, particularly the scattering characteristics, are mainly described.

[0061] For example, an image sensor can obtain more information from the received light or more information as the incident light is more scattered. Therefore, it is desirable to form a structure in the 2-1 layer that allows the received light to be scattered more.

[0062] These light scattering characteristics may be determined or related to the BST structure (130), DTI structure (140), etc. in the image sensor (100).

[0063] In (b) of Fig. 1, an enlarged cross-sectional view of the dotted box portion (125) indicated in the second layer (120) illustrated in (a) of Fig. 1 is shown.

[0064] A more detailed description of the BST structure (130) and the DTI structure (140) will be given later, and a method of forming the BST structure (130) and the DTI structure (140) from a Si body will be described first as follows.

[0065] Figures 2 (a) to (d) illustrate the process of forming a BST structure (130) and a DTI structure (140).

[0066] At this time, it is preferable that each process of (a) to (d) of Fig. 2 be performed sequentially. However, this is not necessarily limited to this.

[0067] The BST structure may have a groove, thereby providing a path for light received through the lens (115) of the first layer to travel. A silicon oxide series material may be applied along the path of light within the second layer (120). However, as mentioned above, the present disclosure is not limited to silicon oxide series materials.

[0068] Referring to (b) of FIG. 1, the BST structure or groove according to one embodiment of the present disclosure may be formed in a rectangular shape.

[0069] In another embodiment, although not shown, the BST structure or groove may be formed in a polygonal or geometrical shape other than a rectangle. For example, the BST structure or groove may be formed to have a wide upper surface and a narrow lower surface, and to have a predetermined slope.

[0070] Al2O3 may be applied to the upper surface of the BST structure. At this time, the Al2O3 has electrical insulation properties so that light passing through, for example, a silicon oxide series is not absorbed by the BST structure but is well reflected or scattered. However, the present disclosure is not limited to Al2O3 as a material applied to the upper surface of the BST structure.

[0071] The BST structure and DTI structure according to various embodiments of the present disclosure are described below.

[0072] Finally, the third layer (130) includes a Si layer.

[0073] The Si layer may include a substrate. The substrate may include various elements. Accordingly, the Si layer may extract and process various information from light received through the lens (115) of the first layer and scattered through the second layer (120).

[0074] Hereinafter, each process of (a) to (d) of FIG. 2 in relation to the formation of the BST structure (130) and the DTI structure (140) will be described as follows. However, in this specification, only the core contents of each process are described, and the rest can be referred to publicly known technologies.

[0075] First, referring to (a) of Fig. 2, a Si body is formed on a Si wafer through a bonding process, and the Si body is formed thinly through a thinning process using a method such as slicing or grinding.

[0076] Next, referring to (b) of Fig. 2, a BST structure (130) and a DTI structure (140) are formed.

[0077] At this time, the formation of the BST structure (130) and the DTI structure (140) can be performed simultaneously or sequentially.

[0078] Meanwhile, the BST structure (130) and the DTI structure (140) can each be formed through an etching process for the Si body.

[0079] In more detail, the DTI structure (140) can be formed on both sides of the pixel structure (100) by sequentially performing a DTI photo process, an etching process, and a photo register strip process.

[0080] In the above, the photo process may refer to a photopatterning process using a predefined mask pattern in relation to the DTI structure (140). The etching process is a process of etching to form the DTI structure (140) using the photopatterning performed on the Si body. The photoresist stripping process is a process of removing the photoresist used in the previous process.

[0081] According to one embodiment, as in (b) of FIG. 2, when there are multiple BST structures (130), a DTI structure (140) may be further formed between the BST structures.

[0082] Like the DTI structure (140), the BST structure (130) can also be formed within the pixel structure (100) by performing a BST photo process, an etching process, and a photoresist strip process.

[0083] According to an embodiment, a plurality of BST structures (130) may be formed.

[0084] Multiple BST structures can be arranged at predetermined intervals.

[0085] At this time, it is preferable that the BST structure (130) be formed so as to be placed between the DTI structures formed on both sides of the pixel structure (100).

[0086] Next, referring to (c) of FIG. 2, a process of depositing a first material (153) on the BST structure (130) and DTI structure (140) formed on the Si body through the process illustrated in (b) of FIG. 2 can be performed.

[0087] In the above, the first material (153) may include, for example, the aforementioned Al2O3. However, the first material (153) according to the present disclosure is not limited to Al2O3.

[0088] Finally, referring to (d) of FIG. 2, when a predetermined material is deposited on the Si body through the process illustrated in (c) of FIG. 2, a process of depositing a second material (154) can be performed.

[0089] In the above, the second material (154) may include silicon oxide (154). However, the second material (154) according to the present disclosure is not limited to silicon oxide.

[0090] Through the processes (a) to (d) of the above-described FIG. 2, a BST structure (130) and a DTI structure (140) are formed on the Si body within the pixel structure.

[0091] Meanwhile, the various examples of BST structures and DTI structures described below can also be formed through the processes of FIG. 2 described above. Therefore, the process descriptions for forming each BST structure and DTI structure described below refer to the above content, and any duplicate descriptions are omitted.

[0092] Referring again to the example illustrated in (b) of FIG. 1, a plurality of BST structures (131, 132) may be formed on a Si substrate (150).

[0093] At this time, the interval between each BST structure can be defined as a period. As mentioned above, the interval can refer to, for example, the distance between the center point of one BST structure and the center point of another adjacent BST structure. However, the definition of the interval is not limited to the above-described definition and can be defined in other ways.

[0094] Detailed specifications of the BST structure are described later in Fig. 5.

[0095] First, various examples of BST structures according to embodiments of the present disclosure are disclosed below.

[0096] FIGS. 3 and 4 are drawings illustrating a BST structure and a DTI structure according to embodiments of the present disclosure.

[0097] Figures 3 and 4 illustrate cross-sectional top views of examples of BST structures with pixel structures, respectively.

[0098] At this time, in order to more easily explain the BST structure, each pixel structure including the BST structure is illustrated in the form of a polygon (e.g., a square) in FIGS. 3 and 4, but is not limited thereto.

[0099] In addition, for convenience of explanation, as illustrated in Fig. 3, the upper part of the square of the pixel structure is described as top (T), the corresponding lower part is described as bottom (B), the left part is described as left (L), and the corresponding right part is described as right (R). However, the present disclosure is not limited thereto.

[0100] Referring to (e) of Fig. 3, the width and length of the BST structure are defined. For example, in Figs. 5 to 14 described below, the width and length of the BST structure can be any value, as a condition for achieving optimal performance (OE) under the same conditions, and can be changed as needed. Therefore, the present disclosure is not limited to these values.

[0101] According to at least one of the various embodiments of the present disclosure, the first BST structure among the plurality of BST structures may be formed in a closed loop structure to limit a scattering path of light entering through the lens unit.

[0102] According to at least one of the various embodiments of the present disclosure, at least one second BST structure among the plurality of BST structures may be formed inside the first BST structure.

[0103] According to at least one of the various embodiments of the present disclosure, some of the second BST structures may be formed in an area including a center point of the pixel structure.

[0104] According to at least one of the various embodiments of the present disclosure, the remainder of the second BST structure may be formed at a position at a predefined interval from a portion formed in an area including a center point of the pixel structure.

[0105] Meanwhile, it can be seen that FIGS. 3 and 4 illustrate the entire pixel structure illustrated in (a) of FIG. 1 described above. For example, in FIGS. 3 and 4, the lens and DTI structure are excluded for convenience of explanation. For example, in each of FIGS. 3 and 4, a DTI structure may be formed on the outside of the edge of the square (e.g., the left side of L and the right side of R). In this case, it is preferable that the formed DTI structure be spaced apart from the BST structure by a predefined distance. However, the present invention is not limited thereto.

[0106] However, for convenience of explanation, the following description will be given using the pixel structure.

[0107] First, in (a) of FIG. 3, a first BST structure (310) is illustrated. For convenience, this is called a line structure, but is not limited to this name.

[0108] The portion excluding the first BST structure (310) may represent, for example, a second material, i.e., silicon oxide. This also applies to the remaining portions of FIG. 3 (b) to (e) and FIG. 4 (a) to (c).

[0109] In (b) of Fig. 3, a second BST structure (320) is illustrated. (b) of Fig. 3 can also be named as a line structure, like (a) of Fig. 3.

[0110] However, in order to distinguish the BST structures (310, 320) of the line structures shown in (a) and (b) of FIG. 3, they can be described by naming them as the BST structure (310) of the first line structure and the BST structure (320) of the second line structure, respectively.

[0111] Referring to (a) and (b) of Fig. 3, it can be seen that three BST structures are formed on one pixel structure. Each BST structure can be formed in a line shape so as to be continuously connected from T to B. At this time, one BST structure can be placed in the central region within the pixel structure, and the remaining two BST structures can be placed in a line shape on the sides of the channel structure, i.e., L and R, respectively.

[0112] However, the difference between (a) and (b) of Fig. 3 is that the width of the line-shaped BST structures formed in Fig. 3 (b) is wider than that of the line-shaped BST structures formed in Fig. 3 (a).

[0113] Next, (c) to (e) of FIG. 3 can represent a pixel structure including a BST structure (330, 340, 350) formed in a kind of lattice shape.

[0114] First, (c) and (d) of Fig. 3 are the same in overall shape as (a) and (b) of Fig. 3, except that the width of the BST structure formed on the pixel structure is different.

[0115] On the other hand, (e) of Fig. 3 shows that the BST structure is formed in a cross structure like a window, although it is a lattice structure.

[0116] For example, the BST structure (350) formed in (e) of Fig. 3 has a BST structure formed along the entire edge of the square, and furthermore, a BST structure is formed in a direction from the center of each edge toward the center of the square. In this respect, the BST structure (350) formed in (e) of Fig. 3 is different from the BST structures (330, 340) formed in (c) and (d) of Fig. 3 described above.

[0117] Meanwhile, it is important to examine not only the simple top-view of each BST structure formed on the pixel structure illustrated in FIGS. 3 and 4, but also how the light incident through the lens (115) in the second layer (120) is scattered through the BST structure and what effect is generated through it. This will be described later in FIGS. 6 to 10.

[0118] Figures 4 (a) to (c) also show the shape of the BST structure formed on the pixel structure.

[0119] In the case of (a) of Fig. 4, it can be seen that the BST structure (410) is formed within the pixel structure in a shape similar to a honeycomb (i.e., honeycomb). In other words, single hexagonal BST structures are arranged adjacent to each other so that at least a plurality of faces are in contact with each other, thereby forming an overall honeycomb shape.

[0120] On the other hand, in (b) and (c) of Fig. 4, it can be seen that a BST structure is formed over the entire edge, as in (e) of Fig. 3.

[0121] In the case of (b) of Fig. 4, the BST structure (420) is largely divided into two BST structures, for example, a BST structure is formed in the entire edge and a central region, and thus can be expressed as a split shape. In this case, the split-shaped BST structure (420) of Fig. 4 (b) can be named a first split-shaped BST structure in order to distinguish it from the BST structure (430) of Fig. 4 (c) described later.

[0122] Meanwhile, each BST structure of Fig. 4 (b) may have a cross shape.

[0123] On the other hand, in the case of (c) of Fig. 4, the BST structure (430) is formed in the edge and inner region, as in the case of (b) of Fig. 4. However, in the case of (b) of Fig. 4, only one BST structure (420) is formed in the central region, whereas in (c) of Fig. 4, multiple BST structures are formed inside, including the central region. In addition, in (c) of Fig. 4, the multiple BST structures formed in the inner region may be formed in such a way that one is arranged in the central region, and the rest face each other with a predetermined interval. In this case, the predetermined interval may be the same interval.

[0124] Meanwhile, according to at least one of the various embodiments of the present disclosure, each BST structure may be formed in a peripheral area surrounding the center point of the pixel structure, as shown in FIGS. 11 and 12 described below.

[0125] According to at least one of the various embodiments of the present disclosure, each of the BST structures may be formed in a cubic shape.

[0126] According to at least one of the various embodiments of the present disclosure, at least two faces of a cube forming each of the BST structures may overlap faces of a cube forming another BST structure.

[0127] According to at least one of the various embodiments of the present disclosure, the width of each BST structure can be determined by taking into consideration the refractive index of the coating layer and the Si substrate.

[0128] According to at least one of the various embodiments of the present disclosure, the spacing of each BST structure is determined by considering the diffraction effect of light entering through the lens unit, and may use an integer multiple of the wavelength sensed by the photo detector.

[0129] FIG. 5 is a drawing illustrating the arrangement relationship and detailed specifications of the BST structure described above according to the present disclosure.

[0130] The size of the BST structure according to the present disclosure can be applied to a single width and length to secure the yield of the process illustrated in FIG. 2. However, the present disclosure is not limited thereto.

[0131] In relation to the present disclosure, when the pixel structure of the image sensor includes a micro lens array (MLA) as described above, the BST structure may be placed in the center region of the pixel, which is the focusing position. However, this is not limited thereto. In this case, in the present disclosure, for example, in the case of an image sensor that does not include a micro lens array (MLA), it is difficult to expect a scattering effect through the BST structure, so a detailed description thereof is omitted. However, it should not necessarily be interpreted as being limited thereto.

[0132] Meanwhile, in the present disclosure, in order to secure the performance of the image sensor, it is desirable to secure the amount of light at the lower portion of the Si layer (e.g., z is approximately 7.0 μm). For example, in order for the light incident on the inside of the pixel to be transmitted as a large number of electrons, it is desirable to secure optical power at the lower portion of the Si layer where the electrons are sensed.

[0133] When multiple BST structures are formed in a pixel structure, it is preferable that the spacing between each BST structure is defined so as to maximize efficiency, for example, by considering the diffraction effect. For example, the spacing between the BST structures is preferably 1.15*(n*λ / 2) > period > 0.85*(n*λ / 2) when 0 < BST_period < 3λ. In this case, the (n*λ) may represent, for example, an integer multiple of the wavelength (λ) sensed by a photo detector. This is because the definition of the spacing as described above may cause a decrease in optical power when the period deviates from the corresponding cycle due to, for example, an interference phenomenon of light. However, the present disclosure is not limited thereto.

[0134] It is preferable that the width of the BST structure be determined by considering the refractive index of the AR coating layer (e.g., silicon oxide series, etc.) and the Si layer. For example, the width of the BST structure is preferably 1.15*(n*λ / 2) > BST_width > 0.85*(n*λ / 2) when 0 < BST_period < 3λ. This is because if the thickness of the width of the BST structure exceeds the corresponding dimension, scattering may not occur effectively or may cause optical power to be reduced due to light interference. However, the present disclosure is not limited thereto.

[0135] Meanwhile, it is preferable that the length of the BST structure consider the period. For example, the length of the BST structure is preferably 1.15*(n*λ / 2) > BST_length > 0.85*(n*λ / 2) when 0 < BST_period < 3λ. This is because, for example, when the length of the BST structure is in the corresponding section, scattering can be effectively generated and the BST area can be minimized, thereby securing optical power. However, the present disclosure is not limited thereto.

[0136] Additionally, in connection with the present disclosure, the length of the DTI structure may be determined, for example, by considering the depth (deep) of the Si layer. For example, the length of the DTI structure may be DTI structure length > Si_layer_deep / 2. However, the present disclosure is not limited thereto.

[0137] Below, the layout and detailed specifications of the BST structure for specific embodiments are described. The definitions included in the specifications are explained based on the centerline of the BST structure. However, if this is not the case, a separate reference is provided.

[0138] Fig. 5 (a) illustrates the BST structure illustrated in Fig. 3 (e), Fig. 5 (b) illustrates the BST structure illustrated in Fig. 4 (b), and Fig. 5 (c) illustrates the BST structure illustrated in Fig. 4 (c).

[0139] First, referring to (a) of Fig. 5, a cross-shaped BST structure is illustrated.

[0140] As shown in (e) of Fig. 3 and (a) of Fig. 5, the pixel structure can be described by dividing it into a first BST structure and a second BST structure.

[0141] Here, the first BST structure may represent, for example, a BST structure positioned at an edge. Conversely, the second BST structure may be seen as originating from each edge, passing through the central region, and connecting to the opposite edge, forming a cross-section of two BST structures.

[0142] The width of the first BST structure and the width of the second BST structure may be, for example, 0.4 μm each, but is not limited thereto.

[0143] The horizontal and vertical lengths of the first BST structure may be, for example, 3.5 μm each. The horizontal length of the second BST structure may be, for example, 1.75 μm. On the other hand, the length between the first and second BST structures, i.e., the width of the second material, may be, for example, 1.35 μm.

[0144] In another embodiment, the width of the first BST structure may be different from the width of the second BST structure. For example, the width of the first BST structure may be narrower than the width of the second BST structure, or vice versa.

[0145] The width of the first BST structure in T and B and the width of the first BST structure in L and R may be the same. Depending on the embodiment, the width of the first BST structure in T and B and the width of the first BST structure in L and R may be different.

[0146] The width of the second BST structure formed between the TBs and the width of the second BST structure formed between the LRs may be the same. In some embodiments, the width of the second BST structure formed between the TBs and the width of the second BST structure formed between the LRs may be different. For example, the width of the second BST structure formed between the TBs may be wider than or opposite to the width of the second BST structure formed between the LRs.

[0147] The second BST structure formed between the TBs can be formed so that both ends are spaced apart from and do not touch at least one BST structure of T or B.

[0148] The second BST structure formed between LR can be formed such that at least one of the ends does not contact and is spaced apart from at least one BST structure of L or R.

[0149] Although in (a) of Fig. 5, the second BST structure is formed in a cross shape while passing through the central region based on the top view, this may not necessarily be limited to this. For example, at least one of the second BST structures may be formed in a cross shape without passing through the central region. Alternatively, at least one of the second BST structures may be formed in a non-perpendicular angle with respect to the first BST structure. Alternatively, the second BST structures may be formed in a parallel manner or without crossing each other.

[0150] Next, the specifications of the first split BST structure shown in (b) of Fig. 4 and (b) of Fig. 5 are described.

[0151] The first split BST structure is formed in the entire edge area, similar to the BST structure illustrated in (a) of Fig. 5, and the second BST structure is formed in the central area. In this case, unlike the BST structure illustrated in (a) of Fig. 5 described above, the second BST structure is formed so that both ends do not touch the edge.

[0152] As illustrated in (b) of Fig. 5, the width of the second BST structure is, for example, 0.4 um between TBs and, for example, 0.8 um between LRs. The gap between the BST structure formed between LRs and the inner surface of the first BST structure located at the edge is, for example, approximately 1.15 um.

[0153] Finally, the specifications of the second split BST structure shown in (c) of FIG. 4 and (c) of FIG. 5 are described.

[0154] The second split BST structure is similar to the BST structure illustrated in (a) of Fig. 5, in that the first BST structure is formed on the front edge and the second BST structure is formed in the inner region. In this case, unlike (a) and (b) of the aforementioned Figs. 5, the second BST structure may be formed by including a plurality of BST structures arranged at positions spaced apart from each other at a predetermined interval.

[0155] One of the plurality of second BST structures may be positioned in the central region. In this case, the distance between one side of the second BST structure positioned in the central region and the inner side of the first BST structure positioned at the edge may be, for example, approximately 1.35 μm.

[0156] Meanwhile, all of the second BST structures, except for one BST structure disposed in the central region, may be formed by being disposed in a region other than the central region. At this time, it can be seen that each second BST structure is disposed at an equal interval from each other. In addition, the second BST structures disposed in the inner region other than the central region may be disposed at a position equidistant from each of the second BST structures disposed in the central region. For example, the remaining second BST structures, except for the second BST structure disposed in the central region, may be disposed at an interval of, for example, 1.35 μm from each other. Two of them are disposed at a position close to, for example, T, and the remaining two are disposed at a position close to, for example, B. Meanwhile, the distance between the outer surface of the second BST structure disposed in the non-central region and the inner surface of the first BST structure may be, for example, about 0.475 μm.

[0157] However, the numerical values ​​mentioned or described in this disclosure are merely examples, and the disclosure is not limited thereto. For example, the numerical values ​​may be determined by considering the scattering effect described below.

[0158] FIG. 6 is a drawing illustrating the scattering effect of the BST structure in relation to the present disclosure.

[0159] FIG. 6 is a drawing illustrating the degree of the scattering effect in order to explain the scattering effect in the second layer (120) of light passing through the lens described later.

[0160] For example, Fig. 6 (a) shows a case where there is no scattering. Fig. 6 (a) shows a case where, for example, the pixel structure does not include a BST structure.

[0161] Next, Fig. 6 (b) and (c) each show cases where scattering occurs. However, Fig. 6 (b) shows a case where scattering occurs but is relatively weak, while Fig. 6 (c) shows a case where scattering occurs relatively heavily.

[0162] With respect to the degree of this relative scattering, for example, Fig. 6 (b) shows a case where the spacing of the BST structure is, for example, about 0.12 um, and Fig. 6 (c) shows a case where the spacing of the BST structure is, for example, 0.4 um.

[0163] FIGS. 7 and 8 are drawings illustrating characteristics and effects of each BST structure according to embodiments of the present disclosure.

[0164] Referring to FIG. 6, FIGS. 7 to 8 show the degree of scattering for each BST structure exemplified in FIGS. 3 to 4 described above.

[0165] Figures 7 and 8 illustrate simulation results for the scattering effect for each BST structure.

[0166] At this time, the above simulation is an example of a periodic structure simulation based on RCWA (Rigorous Coupled Wave Analysis) and an optical simulation based on FDTD (Finite-Difference Time-Domain) method.

[0167] For convenience of explanation, Figures 7 and 8 will be examined sequentially.

[0168] In the tables shown in Figures 7 to 8, the horizontal axis (row) represents each BST structure, and the vertical axis (column) represents the structure shape, simulation (scattering) results, Si absorption, power, and crosstalk in that order.

[0169] Meanwhile, in FIGS. 7 and 8, it is assumed that the inputs for each BST structure are the same. In addition, the Si absorption rate, power consumption, and crosstalk of each BST structure can all be expressed based on the case where the pixel structure does not include the BST structure.

[0170] In particular, in Fig. 7, BST (cross1_0.12) can be seen to have, for example, a Si absorption rate of 131%, a power consumption of 76%, and a crosstalk of 211% compared to the reference value (case without BST structure).

[0171] And in Fig. 7, BST (cross1_04) can be seen to have, for example, a Si absorption rate of 146%, a power consumption of 73%, and a crosstalk of 175% compared to the reference value (case without BST structure).

[0172] The two cases described above in Fig. 7 are excellent in that, for example, the Si absorption rate is increased and the power consumption is also reduced compared to the reference value, but a lot of crosstalk occurs.

[0173] Meanwhile, referring to Fig. 8, it can be seen that the BST structure (split1) has, for example, an increase in Si absorption rate to 160%, a slight increase in power consumption to 105%, and a slight increase in crosstalk to 121% compared to the reference value.

[0174] On the other hand, the BST structure (split2) showed, for example, an increase in Si absorption by 150% compared to the reference value, a decrease in power consumption by 84%, and a slight increase in crosstalk by 107%.

[0175] Finally, the BST structure (honeycomb) shows, for example, that Si absorption is increased by 130%, power consumption is reduced by 72%, and crosstalk is reduced by 86% compared to the reference value.

[0176] In summary, the present disclosure aims to control Si absorption, power consumption, and crosstalk items through scattering effects using various BST structures.

[0177] For example, as described above, the Si absorption rate from incident light is intended to be increased as much as possible through a pixel structure employing a BST structure according to the present disclosure. The BST structure included in the pixel structure with the highest Si absorption rate may be BST(split1).

[0178] In addition, the present disclosure aims to reduce power consumption from incident light through a pixel structure employing a BST structure. In cases where power consumption can be significantly reduced, the BST structure included in the pixel structure may be BST(honeycomb), BST(cross1_0.4), or BST(cross1_0.12).

[0179] In addition, it is intended to reduce, or prevent, crosstalk from incident light through a pixel structure employing a BST structure according to the present disclosure. In the case where crosstalk is most suppressed, the BST structure included in the pixel structure is a BST (honeycomb).

[0180] As another example, the present disclosure seeks to reduce power consumption while increasing Si absorption from incident light through a pixel structure employing a BST structure.

[0181] And in this disclosure, we aim to reduce power consumption from incident light while minimizing crosstalk through a pixel structure employing a BST structure.

[0182] In addition, the present disclosure seeks to increase Si absorption while preventing crosstalk from incident light through a pixel structure employing a BST structure.

[0183] According to another embodiment, the present disclosure aims to increase Si absorption from incident light, reduce power consumption, and simultaneously prevent crosstalk through a pixel structure employing a BST structure.

[0184] In summary, the various BST structures according to the present disclosure can secure an additional layer total absorption rate of about 50% or more compared to, for example, a reference value, i.e., a structure without BST application. This can contribute to improving the sensitivity of the image sensor.

[0185] Meanwhile, optical power loss at the photon sensing location can be minimized. For example, the BST structure of the present disclosure can secure performance equivalent to or higher than that of a structure without the BST structure.

[0186] Additionally, crosstalk caused by scattering in the BST structure can be reduced. This can also contribute to improving noise caused by crosstalk in structures without DTI.

[0187] FIGS. 9 and 10 are drawings illustrating characteristics and effects of each DTI structure according to embodiments of the present disclosure.

[0188] The simulation method of Figs. 9 and 10 is the same as that of Figs. 8 and 9 described above, and the basic contents thereof are used.

[0189] Unlike Figs. 7 and 8, Figs. 9 and 10 show simulation results for Si absorption according to the DTI structure.

[0190] The first column of Fig. 9 presents simulation results for Si absorption in the absence of a DTI structure. This is explained as a reference value for each DTI structure described below.

[0191] In Figures 9 and 10, it can be seen that the Si absorption rate increases sequentially as the height of the DTI structure increases.

[0192] Therefore, referring to FIGS. 6 to 10, considering at least one of increased Si absorption, reduced power consumption, and reduced crosstalk, it is desirable to select a structure related to the desired characteristics and include the BST structure in the pixel structure while making the height of the DTI structure as large as possible.

[0193] Meanwhile, considering various factors such as process complexity, efficiency, and the purpose of the image sensor, it is desirable to determine the shape of the BST structure and the height of the DTI structure that will maximize effectiveness. This decision process can be determined by the administrator, or, if the system's driver or processor (control unit or included) includes an AI engine, it can be determined based on learning results.

[0194] Following the improvement of quantum efficiency described above, a method for improving optical efficiency (OE) is disclosed below.

[0195] In relation to the improvement of this optical efficiency (OE), a CMOS image sensor is used as an example instead of the NIR sensor described above for convenience, but the present disclosure is not limited thereto.

[0196] In an image sensor, the optical efficiency (OE) can be calculated based on the Pointing Vector (P unit: W / m-2) trapped in the photo detector inside the pixel structure.

[0197] FIG. 11 is a diagram illustrating the light efficiency of an image sensor according to another embodiment of the present disclosure.

[0198] Fig. 11 (a) shows a top view of the pixel structure included in the image sensor, and Fig. 11 (b) shows a side cross-sectional view.

[0199] Referring to (a) of Fig. 11, four pixels are included in the image sensor, each pixel is separated from the other through a WRD grid, a BST structure is formed in the central area of ​​each pixel, and a color filter is provided around the periphery.

[0200] In more detail, referring to (b) of Fig. 11, it can be seen that a micro lens array, a color filter, an AR layer, a BST structure, a DTI structure, and a Si layer are formed from the top to the bottom.

[0201] The pixel structure of the image sensor of Fig. 11 is similar to the NIR sensor of the above-described embodiment, but may differ in the characteristics of the CMOS sensor.

[0202] Below, we describe the BST structure in a CMOS image sensor. The following description focuses on differences from the aforementioned NIR sensor, and assumes the same aspects unless specifically mentioned.

[0203] Figures 12 (a) to (d) illustrate the shape of a BST structure according to another embodiment.

[0204] First, it can be seen that the BST structure illustrated in (a) of Fig. 12 is not formed at the center point, but a BST structure of a predetermined width is formed surrounding the center point. Meanwhile, a BST structure may also be formed at the edge of Fig. 12 (a). However, the widths of the BST structure formed at the edge and the BST structure formed in the inner region may be different from each other.

[0205] The BST structure illustrated in (b) of Fig. 12 can be seen to be formed such that, for example, multiple BST structures have different angles (T, B, L, or R) around a central point, similar to (a) of Fig. 12. In this case, one end of each BST structure may overlap with the side surface of another BST structure. This overlapping may indicate that the structures are formed at different heights in the vertical direction. Meanwhile, the other end may be in contact with the inner surface of the BST structure formed at each edge.

[0206] The BST structure shown in (c) of Fig. 12, unlike that of (a) of Fig. 12, is a circular BST structure rather than a polygonal (rectangular) shaped BST structure.

[0207] Meanwhile, it can be seen that the BST structure illustrated in (d) of Fig. 12 further includes an additional BST structure with a larger diameter on the periphery of the circular BST structure (based on the top view) illustrated in (c) of Fig. 12. At this time, the width and diameter of the additional BST structure and the internal BST structure may be different from each other. In addition, as illustrated, the additional BST structure may not have an overlapping area with the internal BST structure or the BST structure formed at the edge. It is preferable that the diameter of the additional BST structure is smaller than the horizontal or vertical length of the BST structure formed at the edge.

[0208] However, the present disclosure is not limited to the BST structure illustrated in FIG. 12.

[0209] FIG. 13 is an image showing the electrical potential of each BST structure shown in (a) to (d) of FIG. 12, including the case where there is no BST structure.

[0210] In particular, (a) of Fig. 13 corresponds to a CMOS image sensor without a BST structure, and (b) to (e) of Fig. 13 correspond to (a) to (d) of Fig. 12, respectively.

[0211] FIG. 14 is a diagram illustrating the light efficiency of an image sensor according to an embodiment of the present disclosure.

[0212] Fig. 14 (a) is a graph showing simulation results to explain the optical efficiency (OE) of the image sensor according to the shape of the BST structure included in the image sensor of Figs. 12 and 13 described above, and Fig. 14 (b) is a table showing simulation result values ​​for the shape of each BST structure shown in the graph of Fig. 14 (a).

[0213] Meanwhile, in relation to the optical efficiency of the Si substrate shown in (a) of Fig. 14, simulations for the optical power change values ​​were performed using, for example, FDTD (Finite Difference Time Domain) simulations.

[0214] In relation to the graph of (a) and the table of (b) of Fig. 14, the following mathematical formula can be used, for example, to calculate the change value of optical power.

[0215] Mathematical expression 1 represents the time-dependent Maxwell-Boltzmann formula required for calculating the change value of optical power according to the present disclosure.

[0216]

[0217] Mathematical expression 2 shows a Poynting vector calculation formula required for calculating the change value of optical power according to the present disclosure.

[0218]

[0219] Mathematical expression 3 shows a formula for calculating the change value of optical power according to the present disclosure.

[0220]

[0221] The image sensor according to the present disclosure described above can be applied to various fields. For example, in order to improve the efficiency of image sensors used in various fields such as automobiles, robots, industrial automation, eXtended Reality, and environmental monitoring, the image sensor according to the present disclosure can be applied as is or with slight modifications that can be easily understood by those skilled in the art.

[0222] Although the present invention has been described above with reference to embodiments thereof, it will be readily understood by those skilled in the art that various modifications and changes may be made to the present invention without departing from the spirit and scope of the present invention as set forth in the claims below.

[0223] The present disclosure relates to an image sensor, and more particularly, to an image sensor in which a pixel structure employing various BST / DTI structures can be used to improve quantum efficiency (QE) or / and optical efficiency (OE), and thus can be utilized in image sensors applied to various systems, and thus has industrial applicability.

Claims

1. A lens section that receives external light, A pixel structure including a body including a plurality of BST (Backside Scattering Technology) structures so that light passing through the lens section is scattered and a DTI (Deep Trench Isolation) structure arranged outside the outermost BST structure among the plurality of BST structures, and a Si substrate that absorbs light scattered through the plurality of BST structures and the DTI structure, The length of the above multiple BST structures is, It is determined by considering the period representing the interval between each of the above BST structures. Image sensor.

2. In claim 1, Among the above multiple BST structures, the first BST structure is: It is formed as a closed loop structure to limit the scattering path of light passing through the above lens section. Image sensor.

3. In claim 2, Inside the above first BST structure, At least one second BST structure among the above multiple BST structures is formed, Image sensor.

4. In claim 3, Some of the above second BST structures, formed in an area including the center point of the above pixel structure, Image sensor.

5. In claim 4, The remainder of the above second BST structure, A part formed in an area including the center point of the above pixel structure and arranged at a position with a predefined interval, Image sensor.

6. In claim 1, Each of the above BST structures, formed in the peripheral area surrounding the center point of the above pixel structure, Image sensor.

7. In claim 6, Each of the above BST structures, Formed in the shape of a cube, Image sensor.

8. In claim 7, At least two faces of the hexahedron forming each of the above BST structures are, Overlapping with the faces of the hexahedron forming another BST structure, Image sensor.

9. In claim 1, The width of each BST structure above is, Determined by considering the refractive index of the coating layer and the Si substrate, Image sensor.

10. In claim 1, The spacing of each BST structure above is, It is determined by considering the diffraction effect of light passing through the above lens section. Using an integer multiple of the wavelength sensed by the photodetector, Image sensor.

Images