Semiconductor image sensor

Abstract

BSI image sensor (100) comprising: a substrate (102) comprising a front (102F) and a back (102B) opposite the front (102F), a pixel sensor (110) in the substrate (102), an insulating structure (120) surrounding the pixel sensor (110) in the substrate (102), a dielectric layer (136) over the pixel sensor (110) on the front (102F) of the substrate (102), and several conductive structures (142) arranged in the dielectric layer (136) and designed to be aligned with and in contact with the insulating structure (120).

Description

PRIORITY DATA

[0001] This patent claims priority from the preliminary US patent application serial no. 62 / 579,461, which was filed on October 31, 2017, the entire disclosure of which is incorporated herein by cross-reference. STATE OF THE ART

[0002] Digital cameras and other imaging devices use image sensors. Image sensors convert optical images into digital data that can be represented as digital images. An image sensor comprises an array of pixel sensors and supporting logic circuitry. The pixel sensors in the array are unit devices for measuring incident light, and the supporting logic circuitry facilitates the readout of the measurements. One type of image sensor commonly used in optical imaging devices is a back-illuminated (BSI) image sensor. Fabrication of a BSI image sensor can be integrated into conventional semiconductor processes for low cost, small size, and high integration. Furthermore, BSI image sensors exhibit low operating voltage, low power consumption, high quantum efficiency, low readout noise, and allow for random and intermittent access. List of characters

[0003] Aspects of this disclosure are best understood from the detailed description below, when read together with the accompanying figures. It should be noted that, in accordance with industry standard practice, various features are not drawn to scale. Rather, the dimensions of the various features may have been enlarged or reduced as appropriate for clarity of discussion. Fig. Figure 1 is a top view of a pixel sensor of a BSI image sensor according to aspects of the present disclosure in one or more embodiments. Fig. Figure 2 is a top view of a pixel sensor of a BSI image sensor according to aspects of the present disclosure in one or more embodiments. Fig. Figure 3 is a top view of a pixel sensor of a BSI image sensor according to aspects of the present disclosure in one or more embodiments. Fig. 4 is one along the line A-A' from Fig. 1 to Fig. 3. Drawn cross-sectional view of the pixel sensor of the BSI image sensor. Fig. Figure 5 is a cross-sectional view of a section of the BSI image sensor according to aspects of the present disclosure in some embodiments. Fig. Figure 6 is a top view of a pixel sensor of a BSI image sensor according to aspects of the present disclosure in one or more embodiments. Fig. Figure 7 is a top view of a pixel sensor of a BSI image sensor according to aspects of the present disclosure in one or more embodiments. Fig. Figure 8 is a top view of a pixel sensor of a BSI image sensor according to aspects of the present disclosure in one or more embodiments. Fig. 9 is one along the line B-B' from Fig. 6 to Fig. 8. Drawn cross-sectional view of the pixel sensor of the BSI image sensor. Fig. Figure 10 is a cross-sectional view of a section of the BSI image sensor according to aspects of the present disclosure in some embodiments. DETAILED DESCRIPTION

[0004] The following disclosure provides many different embodiments, or examples, for implementing various features of the present subject matter. Specific examples of elements and arrangements are described below to simplify the present disclosure. These are, of course, merely examples and are not intended to be limiting. For example, forming a first feature over or on top of a second feature in the description below may include embodiments in which the first and second features are formed in direct contact, and may also include embodiments in which additional features may be formed between the first and second features, so that the first and second features may not be in direct contact. Furthermore, the present disclosure may repeat reference numbers and / or letters in the various examples.This repetition is done for the sake of simplicity and clarity and does not in itself prescribe any relationship between the various designs and / or configurations discussed.

[0005] Furthermore, terms relating to spatial relativity, such as "below," "under," "lower," "above," "upper," "on," and the like, may be used herein for the convenience of discussion to describe the relationship of one element or feature to another element or feature (or other elements or features), as illustrated in the figures. The terms relating to spatial relativity are intended to encompass various orientations of the apparatus used or operated in addition to the orientation illustrated in the figures. The apparatus may be oriented in a different way (rotated by 90 degrees or otherwise), and the terms relating to spatial relativity used herein may likewise be interpreted accordingly.

[0006] As used here, terms such as "first," "second," and "third" describe different elements, components, areas, layers, and / or sections. These elements, components, areas, layers, and / or sections should not be limited by these terms. These terms can only be used to distinguish one element, component, area, layer, or section from another. The terms such as "first," "second," and "third," when used here, do not imply any sequence or order unless clearly indicated by the context.

[0007] As used here, the terms "approximately," "essentially," "significantly," and "about" are used to describe and account for small variations. When used in conjunction with an event or circumstance, these terms can refer to instances where the event or circumstance occurs precisely, as well as instances where the event or circumstance occurs approximately. For example, when used in conjunction with a numerical value, these terms can refer to a range of variation that is less than or equal to ±10% of the numerical value, such as less than or equal to ±5%, less than or equal to ±4%, less than or equal to ±3%, less than or equal to ±2%, less than or equal to ±1%, less than or equal to ±0.5%, less than or equal to ±0.1%, or less than or equal to ±0.05%.For example, two numerical values ​​can be considered "essentially" identical or the same if the difference between them is less than or equal to ±10% of an average of the values, such as less than or equal to ±5%, less than or equal to ±4%, less than or equal to ±3%, less than or equal to ±2%, less than or equal to ±1%, less than or equal to ±0.5%, less than or equal to ±0.1%, or less than or equal to ±0.05%. For example, "essentially parallel" can refer to a range of angular variation relative to 0° that is less than or equal to ±10°, such as less than or equal to ±5°, less than or equal to ±4°, less than or equal to ±3°, less than or equal to ±2°, less than or equal to ±1°, less than or equal to ±0.5°, less than or equal to ±0.1°, or less than or equal to ±0.05°. For example, “essentially” perpendicular can refer to a range of angular variation relative to 90° that is less than or equal to ±10°, such as…less than or equal to ±5°, less than or equal to ±4°, less than or equal to ±3°, less than or equal to ±2°, less than or equal to ±1°, less than or equal to ±0.5°, less than or equal to ±0.1° or less than or equal to ±0.05°.

[0008] A back-mounted image sensor (BSI) comprises an array of pixel sensors. Typically, BSI image sensors include an integrated circuit with a semiconductor substrate and light-sensing devices, such as photodiodes, corresponding to the pixel sensors on the substrate. They also include a back-end-of-line (BEOL) metallization of the integrated circuits, located on the front side of the substrate, and an optical stack comprising color filters and microlenses, corresponding to the pixel sensors on the back side of the substrate. As the size of BSI image sensors has decreased, they face a number of challenges. One such challenge is crosstalk between adjacent pixel sensors. With the increasingly smaller size of BSI image sensors, the distance between adjacent pixel sensors becomes smaller, increasing the likelihood of crosstalk.Another challenge with BSI image sensors is light collection. As image sensors become increasingly smaller, the area available for light collection also decreases, reducing the sensitivity of pixel sensors. This becomes problematic in low-light environments. Therefore, there is a need to reduce crosstalk and increase the absorption efficiency of the pixel sensors to improve the performance and sensitivity of BSI image sensors.

[0009] The present disclosure therefore provides a BSI image sensor comprising a reflective grid that surrounds and separates the pixel sensors. As a result, light is directed onto and reflected by the pixel sensor instead of reaching neighboring pixel sensors. In other words, crosstalk is reduced and light is trapped within the pixel sensors, thereby improving both the performance and sensitivity of the pixel sensors.

[0010] Fig. 1 to Fig. 3 are top views of a pixel sensor 110 a BSI image sensor 100 according to aspects of the present disclosure in some embodiments, Fig. 4 is one along the line A-A' from Fig. 1 to Fig. 3. Drawn cross-sectional view of the pixel sensor 110 the BSI image sensor 100 , and Fig. Figure 5 is a cross-sectional view of a section of the BSI image sensor. 100according to aspects of the present disclosure in some embodiments. It is understood that the same elements in Fig. 1 to Fig. 5 are marked with the same reference numerals. As in Fig. 1 to Fig. As shown in section 4, an image sensor is included. 100 a substrate 102 , and the substrate 102 This includes, for example, a bulk semiconductor substrate, such as a bulk silicon (Si) substrate or an SOI substrate (silicon on an insulator), but is not limited to these. The substrate 102 has a front 102F and one of the front 102F opposite reverse 102B on. The BSI image sensor 100 includes multiple pixel sensors 110 , which are typically arranged within an array, and each of the pixel sensors 110 includes a light detection device, such as a photodiode 112 , which are in the substrate 102is arranged. In other words, the BSI image sensor includes 100 several photodiodes 112 , which the pixel sensors 110 correspond. The photodiodes 112 are in rows and columns in the substrate 102 They are arranged and designed to collect charge (e.g., electrons) from incident photons. Furthermore, logic devices, such as transistors, can be used. 114 , above the substrate 102 on the front 102F arranged and designed in such a way that they allow the photodiodes to be read out 112 enable. The pixel sensors 110 They are arranged to receive light with a specific wavelength. Accordingly, the photodiodes can 112 In some embodiments, they are operated to detect visible light from the incident light. Or the photodiodes 112In some embodiments, they can be operated to detect infrared (IR) and / or near-infrared (NIR) of the incident light.

[0011] An isolation structure 120 , such as a DTI structure (deep trench insulation) is embedded in the substrate 102 arranged as in Fig. 1A and Fig. 1B is shown. In some embodiments, the DTI structure can 130 The following operations are used to train the skills. For example, an initial etching from the back side is performed. 102B of the substrate 102 carried out. The first etching results in several deep trenches (not shown) that define the easy detection areas. 112The deep trenches are surrounded by and located between them. An insulating material, such as silicon dioxide (SiO₂), is then formed to fill the deep trenches using any suitable deposition technique, such as chemical vapor deposition (CVD). In some embodiments, at least the sidewalls of the deep trenches are coated with a material. 122 (shown in Fig. 4) lined, and the deep trenches are filled with an insulating material 124 replenished (shown in Fig. 4) The coating 122 The disclosure may include a metal, such as tungsten (W), copper (Cu), or aluminum-copper (AlCu), or an antireflective material having a refractive index (n) lower than that of silicon, but the disclosure is not limited thereto. In some embodiments, the insulating material may be 124, which fills the deep trenches and includes the low-n insulation material. Planarization is then carried out to remove excess insulation material, so that the substrate area 102 on the back 102B is exposed, and the DTI structure 120 , which the photodiodes 112 surrounding and located between them, is achieved as in Fig. 1 to Fig. 5. The DTI structure is shown. 120 represents an optical separation between adjacent pixel sensors 110 and photodiodes 112 ready, thus serving as a substrate isolation grid and reducing crosstalk.

[0012] A back-end-of-line metallization stack (BEOL metallization stack) 130 is above the substrate 102 on the front 102F arranged. The BEOL metallization stack 130 It comprises several metallization layers that provide conductive contacts / vias132 and leaders 134 , which are located in a dielectric intermediate layer (ILD) 136 are stacked, includes (all in Fig. 4 to Fig. 5 shown). One or more contacts 132 of the BEOL metallization stack 130 are electrically connected to the logic devices, and one or more conductive vias 132 will be with the ladders 134 Different layers are electrically connected. In some embodiments, the ILD layer can be 136 The disclosure may include a low-k dielectric material (i.e., a dielectric material with a dielectric constant less than 3.9) or an oxide, but it is not limited to these. The multiple metallization layers 132 / 134The disclosure may include a metal, such as Cu, W, or Al, but it is not limited to such metals. In some embodiments, another substrate (not shown) may be interposed between the metallization structure. 130 and external connectors, such as a ball grid array (BGA) (not shown). And the BSI image sensor 100 It is electrically connected to other devices or circuits via the external connectors, but the disclosure is not limited to this.

[0013] With reference to Fig. 1 to Fig. Each pixel sensor contains 4 pixels. 110 the BSI image sensor 100 several conductive structures 142 The conductive structures 142 are located in the dielectric layer 136 the connection structure 130 arranged. The conductive structures 142 are arranged in such a way that they rest on the insulation structure 120are aligned. For example, the conductive structures overlap. 142 the insulation structure 120 in a top view, as in Fig. 1 to Fig. Figure 3 shows that in some embodiments the conductive structures overlap. 142 the entire insulation structure 120 , as in Fig. 1 to Fig. Figure 4 shows that in some embodiments, at least one section of the conductive structures overlaps. 142 the insulation structure 120 In some embodiments, the conductive structures comprise 142 conductive contacts, and the conductive contacts and the conductive contacts 132 the connection structure 130 are formed in the same layer. In some embodiments, the conductive structures can 142 and those conductive contacts 132the same material, but the disclosure is not limited to it. In some embodiments, these conductive contacts 132 in the lowest section of the dielectric layer 136 trained and equipped with the pixel sensors 110 electrically connected, therefore these conductive contacts 132 as the zeroth vias (Vo) in the interconnect structure 130 This is referred to as... Therefore, the conductive structures... 142 In some embodiments, these are referred to as the Vo vias, but the disclosure is not limited thereto. In some embodiments, the conductive structures are 142 on the insulation structure 120 arranged and we are standing with the isolation structure 120 in contact, as in Fig. 4 shown.

[0014] With reference to Fig. 1 and Fig. 4 in some embodiments comprise the conductive structures 142 discrete point-like structures 142a , which are in the connection structure 130 are arranged as in Fig. 1 shown. In some embodiments, each of the point-like conductive structures comprises 142a a diameter D , and the diameter D is smaller than a width Wd of the insulation structure 104 , as in Fig. 4 shown. For example, but not as a limitation, the diameter is D the point-like conductive structures 142a between approximately 0.05 micrometers (µm) and approximately 0.1 µm. Furthermore, the point-like conductive structures are 142a from each other through the dielectric layer 136 spaced apart, and a spacing distance S is between the adjacent conductive structures. 142adefined. In some embodiments, a ratio of the spacing distance is specified. S diameter D of the point-like conductive structures 142a between 1.5 and 2.5, but the revelation is not limited to that. Furthermore, as mentioned above, the pixel sensor 110 arranged to receive light with a predetermined wavelength, and the spacing distance S is less than half the predetermined wavelength. When the pixel sensor 110 When operated to detect NIR of the incident light, which has a wavelength in the range of approximately 0.75 µm to 1.4 µm, the spacing distance can be, for example, but not as a limitation, S in a range of approximately 0.11 µm to 0.7 µm. In some embodiments, the spacing distance can be S approximately 0.5 µm, but the revelation is not limited to that.

[0015] With reference to Fig. 2 and Fig. 4 in some embodiments comprise the conductive structures 142 discrete rod-shaped structures 142b , which are in the connection structure 130 are arranged as in Fig. 2 shown. In some embodiments, each of the rod-shaped conductive structures comprises 172b a width W1 , and the width W1 is smaller than the width Wd of the insulation structure 120 , as in Fig. 4 shown. In some embodiments, the width W1 the rod-shaped conductive structures 142b greater than 0.05 µm. In some embodiments, the width is W1 the rod-shaped conductive structures 142b between approximately 0.05 µm and approximately 0.2 µm, but the revelation is not limited to this. Furthermore, the rod-shaped conductive structures 142b through the dielectric layer 136spaced apart from each other, and a spacing distance S is between the adjacent conductive structures. 142b defined. As mentioned above, the pixel sensor 110 arranged to receive light of a predetermined wavelength, and the spacing distance S is smaller than half the specified wavelength. If the pixel sensor 110 When operated to detect NIR of the incident light, the spacing distance S can, for example, but is not limited to, be in a range of approximately 0.11 µm to 0.7 µm. In some embodiments, the spacing distance S can be approximately 0.5 µm, but the disclosure is not limited thereto. Furthermore, the rod-shaped conductive structures can 142b encompass a length, and the length is smaller than a length of the insulation structure 120 in top view, as in Fig. 2 shown.

[0016] With reference to Fig. 3 and Fig. 4 in some embodiments comprise the conductive structures 142 rod-shaped structures that are in the connecting structure 130 are arranged. Furthermore, the conductive structures are 142 in contact with each other to form a frame-shaped structure 142c to form, as in Fig. Figure 3. In some embodiments, the frame-shaped structure comprises 142c a width W1 , and the width W1 is smaller than the width Wd of the insulation structure 120 , as in Fig. 4 shown. In some embodiments, a width W1 the frame-shaped conductive structures 142b greater than 0.05 µm. In some embodiments, the width is W1 the frame-shaped conductive structures 142c between approximately 0.05 µm and approximately 0.2 µm, but the revelation is not limited to this.

[0017] With further reference to Fig. 1 to Fig. Each of the pixel sensors comprises 4. 110 furthermore a ladder 144 , which is in the dielectric layer 136 the connection structure 130 is arranged. In some embodiments, the conductor 144 arranged in such a way that it rests on the insulation structure 120 is aligned. As in Fig. 1 to Fig. As shown in 3, the ladder 144 in a top view both the conductive structures 142 as well as the insulation structure 120 overlap. In some embodiments, the conductor overlaps. 144 completely the conductive structures 142 and the insulation structure 120 , as in Fig. 1 to Fig. Figure 4 shows that in some embodiments, at least one section of the conductor overlaps. 144 the conductive structures 142 and the insulation structure 120In some embodiments, the conductor 144 and some of the leaders 134 the connection structure 130 formed in the same layer. In some embodiments, the conductor can 144 and the ladder 134 They comprise the same material, but the disclosure is not limited to it. In some embodiments, those conductors 134 the lower features are directly above the Vo vias and electrically connected to the Vo vias, therefore those conductors 134 as the first metal features ( M1 -features) in the connection structure 130 designated. Therefore, the conductor 144 in some embodiments these are referred to as the M1 features, but the disclosure is not limited thereto. The conductor 144 encompasses a width W2 , and the width W2It can be between approximately 0.03 µm and approximately 0.1 µm, but the revelation is not limited to this.

[0018] As in Fig. As shown in section 4, all of the conductive structures are 142 between the insulation structure 120 and the leader 144 ordered. More importantly, that the leader 144 and the conductive structures 142 a first reflective structure 140 form, which are in the connection structure 130 is arranged. The first reflective structure 140 is arranged in such a way that it rests on the insulation structure 120 is aligned, as in Fig. 1 to Fig. 4 shown. For example, but not limited to, in some embodiments the first reflective structure 140 the insulation structure 120 They completely overlap in the top view. Since the diameter D or the width W1the conductive structures 142 smaller than the width W2 the leader 144 , is also the width of the first reflective structure 140 smaller than the width Wd of the insulation structure 120 In some embodiments, the first reflective structure 140 electrically separated from other elements, but the revelation is not limited to that.

[0019] In some embodiments, each of the pixel sensors includes 110 multiple microstructures 116 , which are above the back 102B of the substrate 102 are arranged as in Fig. 4 shown. In some embodiments, the microstructures 116 The following operations are used to form a mask layer (not shown) over the surface of the substrate. 102 on the back 102Barranged, followed by the formation of a structured photoresist (not shown) over the mask layer. The substrate 102 is then protected from the back by the structured photoresist and the mask layer. 102B etched and therefore the multiple microstructures 116 over the back 102B of the substrate 102 within each of the pixel sensors 110 The structured photoresist and mask layer are then removed. In some embodiments, further operations, such as wet forming, can be performed. Consequently, the upper and lower sections of the microstructures are formed. 116 tapered or rounded to create a wave-like structure, as in Fig. 4 shown. In some embodiments, the microstructures 116 be continuous structures and include a wave profile, as in Fig. 4 shown. In some embodiments, the microstructures116 comprise discrete structures that pass through the substrate 102 are spaced apart from each other.

[0020] In some embodiments, an anti-reflective coating (ARC) is used. 118a and a dielectric layer 118b over the microstructures 130 on the back 102B of the substrate 102 arranged. As in Fig. As shown in 4, the surfaces of the microstructures are depicted. 116 with the compliantly trained ARC 118a lined. The dielectric layer 118b fills spaces between microstructures 116 and represents an essentially flat surface over the back 102B of the substrate 102 ready. In some embodiments, the dielectric layer 118b for example, an oxide such as silicon dioxide, but the disclosure is not limited to that.

[0021] In some embodiments, several color filters are used.150 (shown in Fig. 4), which are the pixel sensors 110 correspond to the pixel sensors 110 on the back 102B of the substrate 102 arranged. In addition, in some embodiments a low-n structure 160 is arranged between the color filters. 150 arranged. In some embodiments, the low-n structure comprises 160 a grid structure and the color filters 160 are arranged within the lattice. Therefore, the low-n structure surrounds 160 every color filter 150 and separates the color filters 150 from each other, as in Fig. Figure 4 shows the low-n structure 160, which can be a composite structure comprising layers with a refractive index lower than that of the color filters. 150 In some embodiments, the low-n structure can 160 comprise a composite stack that includes at least one metal layer 162and a dielectric layer arranged above the metal layer 164 includes. In some embodiments, the metal layer 142 include W, Cu, or AlCu. The dielectric layer 164 includes a material with a refractive index that is smaller than the refractive index of the color filter 150 , or a material with a refractive index smaller than that of Si, but the disclosure is not limited thereto. Due to the low refractive index, the low-n structure serves 160 as a light guide to direct light to the color filters 150 to direct or reflect. Consequently, the low-n structure increases 160 effectively reduces the amount of the color filter 150 incident light. Due to its low refractive index, the Low-n structure 160 also provides optical isolation between adjacent color filters. 150 ready.

[0022] Each of the color filters 150is above each of the corresponding photodiodes 112 arranged. The color filters 150 are assigned to corresponding colors or wavelengths of light and are designed to filter out all colors or wavelengths of light except those assigned. In some embodiments, the assignments of the color filters change. 150 between red, green and blue light, so that the color filters 150 The red color filters, green color filters, and blue color filters are included. The red color filters, green color filters, and blue color filters are arranged in a Bayer or other mosaic structure in those embodiments in which the photodiode 112 It is operated to capture visible light from incident light. In some embodiments, the color filters 150 assigned infrared radiation when the photodiode 112 It is operated to detect IR and / or NIR of the incident light.

[0023] In some versions, multiple microlenses are used. 152 , which the pixel sensors 110 correspond to the color filters 150 arranged. It should be easy to understand that the positions and areas of each microlens 152 those of the color filters 150 correspond, as in Fig. 4 shown.

[0024] With reference to Fig. 4 and Fig. 5 includes the BSI image sensor in some embodiments. 100 the multiple pixel sensors 110 , as mentioned above. More importantly, the first reflective structure 140 (the conductive structure(s)) 142 and the conductive feature 144 includes), the insulation structure 120 and the low-n structure 160 a reflective lattice 180 form, and the reflective grid penetrates the substrate 102 from the front 102F to the back 102B , as in Fig. 4 and Fig. 5 shown. The pixel sensors 110 are within the reflecting grating 180 arranged and through the reflective grid 180 The light is separated from each other. Accordingly, the incident light is refracted through the microlenses. 152 above each color filter 150 collected and then to the color filter 150 This is further enhanced by the color filter. 150 diffusing incident light using the low-n structure 160 of the reflecting grating 180 to the pixel sensor 110 directed or reflected back, the incident light that passes through the substrate 102 The process is carried out by the insulation structure. 120 of the reflecting grating 180 to the photodiode 112 directed or reflected back, and the incident light passing through the connecting structure 130 The process is characterized by the first reflective structure 140of the reflecting grating 180 to the pixel sensor 110 directed or reflected back. In other words, light escaping to neighboring pixel sensors is prevented. 110 blocked, and as a result, crosstalk occurs between neighboring pixel sensors. 110 mitigated.

[0025] Fig. 6 to Fig. 8 are top views of a pixel sensor 110 a BSI image sensor 100a according to aspects of the present disclosure in some embodiments, Fig. 9 is one along the line B-B' from Fig. 6 to Fig. 8. Drawn cross-sectional view of the pixel sensor 110 the BSI image sensor 110a , and Fig. Figure 10 is a cross-sectional view of a section of the BSI image sensor. 100a according to aspects of the present disclosure in some embodiments. It is understood that the same elements in Fig. 1 to Fig. 10 are identified by the same reference symbols; details of these identical elements have been omitted for brevity. As in Fig. 6 to Fig. As shown in 9, the BSI image sensor includes 100a a substrate 102 , and the substrate 102 has a front 102F and one of the front 102F opposite reverse 102B on. The BSI image sensor 100 includes multiple pixel sensors 110 , which are typically arranged within an array. Each of the pixel sensors 110 includes a light detection device, such as a photodiode 112 , which is designed to collect charge (e.g., electrons) from incident photons. Furthermore, logic devices, such as transistors, can be used. 114 , above the substrate 102 on the front 102F arranged and designed in such a way that they allow the photodiodes to be read out 112enable the pixel sensor 110 It is arranged to receive light with a predetermined wavelength. Therefore, the photodiode 112 In some embodiments, it is operated to detect visible light from the incident light. Or the photodiode. 112 In some embodiments, it is operated to detect infrared (IR) and / or near-infrared (NIR) of the incident light.

[0026] An isolation structure 120 , such as a DTI structure, is formed in the substrate 102 arranged as in Fig. 6 to Fig. 9 shown. In some embodiments, the insulation structure 120 a coating 122 (shown in Fig. 9) and an insulating material 124 (shown in Fig. 9) include. The insulation structure 120 represents an optical separation between adjacent pixel sensors 110 and photodiodes 112ready, thus acting as a substrate isolation grid and reducing crosstalk. A BEOL metallization stack 130 is above the substrate 102 on the front 102F arranged. The BEOL metallization stack 130 It comprises several metallization layers that provide conductive contacts / vias 132 and conductive features 134 , which are in an ILD layer 136 are stacked, includes (all in Fig. 9 to Fig. 10 shown). One or more contacts 132 of the BEOL metallization stack 130 are electrically connected to the logic devices, and have one or more conductive vias. 132 are with the conductive features 134 different layers are electrically connected.

[0027] With reference to Fig. 6 to Fig. Each of the pixel sensors comprises 9. 110 the BSI image sensor 100aseveral conductive structures 142 , which are in the dielectric layer 136 the connection structure 130 are arranged. The conductive structures 142 are arranged in such a way that they rest on the insulation structure 120 are aligned. As mentioned above, the conductive structures can 142 the insulation structure 120 completely overlap in a top view, as in Fig. 6 to Fig. Figure 8 is shown, but the revelation is not limited to this. The conductive structures 142 They include conductive contacts and, in some embodiments, can be referred to as the Vo vias. In some embodiments, the conductive structures are 142 with the insulation structure 120 in contact, as in Fig. 9 shown. With reference to Fig. 6 and Fig. In some embodiments, the conductive structures comprise 9. 142discrete point-like structures 142a , which are in the connection structure 130 are arranged and along the insulation structure 120 are arranged in a top view, as in Fig. Figure 6 is shown. It is understood that the parameters of the point-like structures 142a They may be the same as those described above; therefore, those details are omitted for the sake of simplicity. With reference to Fig. 7 and Fig. In some embodiments, the conductive structures comprise 9. 142 discrete rod-shaped structures 142b , which are in the connection structure 130 are arranged as in Fig. Figure 7 is shown. It is understood that the parameters of the rod-shaped structures 142b They may be the same as those described above; therefore, those details are omitted for the sake of simplicity. With reference to Fig. 8 and Fig. In some embodiments, the conductive structures comprise 9. 142 Rod-shaped structures and the rod-shaped structures are in contact with each other to form a frame-shaped structure. 142c to form, as in Fig. Figure 8 is shown. It is understood that the parameters of the frame-shaped structures 142c They may be the same as those described above, therefore those details are omitted for the sake of simplicity.

[0028] With further reference to Fig. 6 to Fig. Each of the pixel sensors comprises 9. 110 furthermore a ladder 144 , which is in the dielectric layer 136 the connection structure 130 is ordered. The leader 144 is set up in such a way that it rests on the isolation structure 120 is aligned. As mentioned above, the leader can 144 both the conductive structures 142 as well as the insulation structure120 completely overlap in a top view, as in Fig. 6 to Fig. 8 is shown, but the revelation is not limited to that. The leader 144 In some embodiments, this may be referred to as the M1 feature, but the disclosure is not limited to this. Furthermore, as described in Fig. 9 shows all of the conductive structures 142 between the insulation structure 120 and the leader 144 ordered. More importantly, that the leader 144 and the conductive structures 142 a first reflective structure 140 form, which are in the connection structure 130 is arranged. And the first reflective structure 140 is arranged in such a way that it rests on the insulation structure 120 is aligned, as in Fig. 6 to Fig. 9 is shown. For example, the first reflective structure can 140 the insulation structure 120completely overlap, but the revelation is not limited to that. Since the diameter D or the width W1 the conductive structures 142 is smaller than a width W2 of the conductive feature 144 , is the width of the first reflecting structure 140 smaller than the width Wd of the insulation structure 120 In some embodiments, the first reflective structure 140 electrically separated from other elements, but the revelation is not limited to that.

[0029] In some embodiments, each of the pixel sensors includes 110 furthermore, a second reflective structure 170 , which are in the connection structure 130 above the front 102F is arranged, and which includes at least one section of the pixel sensor 110 overlaps. As in Fig. 6 to Fig. As shown in 9, the second reflective structure overlaps.170 at least the photodiode 112 of the pixel sensor 110 In some embodiments, the second reflective structure can 170 This will be the M1 feature. In other words, the second reflective structure will be... 170 and the conductive feature 144 the first reflective structure 140 They are formed in the same layer and can comprise the same material. However, the first reflective structures are 140 from the second reflective structure 170 electrically insulated, as in Fig. 6 to Fig. 9 is shown. In some embodiments, the second reflective structure 170 not only from the first reflective structure 170 , but also electrically insulated from other elements. However, in some embodiments, the second reflective structure 170 through the connection structure 130 electrically grounded, as in Fig. 10 shown.

[0030] As mentioned above, each of the pixel sensors includes 110 multiple microstructures 116 , which are above the substrate 102 on the back 102B are arranged as in Fig. 9 is shown. In some embodiments, an ARC is used. 118a and a dielectric layer 118b over the microstructures 130 on the back 102B of the substrate 102 arranged. In some embodiments, several color filters are used. 150 (shown in Fig. 9), which are the pixel sensors 110 correspond to the pixel sensors 110 on the back 102B of the substrate 102 arranged. In addition, in some embodiments a low-n structure 160 is arranged between the color filters. 150 arranged. As mentioned above, the Low-n structure 160 comprises a grid structure and the color filters. 150are arranged within the grid. Therefore, the low-n structure surrounds each color filter. 150 and separates the color filters 150 from each other, as in Fig. Figure 9 shows the low-n structure 160, which can be a composite structure comprising layers with a refractive index lower than that of the color filters. 150 In some embodiments, the low-n structure 160 can comprise a composite stack containing at least one metal layer. 162 and a dielectric layer arranged above the metal layer 164 includes.

[0031] In some embodiments, several microlenses are used. 152 , which the pixel sensors 110 correspond to the color filters 150 arranged. It should be easy to understand that the positions and areas of each microlens 152 those of the color filters 150 correspond, as in Fig. 9 shown.

[0032] With reference to Fig. 9 and Fig. In some embodiments, the BSI image sensor is included in section 10. 100a the multiple pixel sensors 110 , as mentioned above. More importantly, the first reflective structure 140 (the conductive structure(s)) 142 and the conductive feature 144 includes), the insulation structure 120 and the low-n structure 160 a reflective lattice 180 form, and the reflective grid the substrate 102 from the front 102F to the back 102B penetrates, as in Fig. 9 and Fig. 10 are shown. The pixel sensors 110 are within the reflecting grating 180 arranged and through the reflective grid 180 The light is separated from each other. Accordingly, the incident light is refracted through the microlenses. 152 above each color filter 150 collected and then added to the color filter 150This is further enhanced by the color filter. 150 diffusing incident light using the low-n structure 160 of the reflecting grating 180 to the pixel sensor 110 directed or reflected back, the incident light that passes through the substrate 102 The process is carried out by the insulation structure. 120 of the reflecting grating 180 to the photodiode 112 directed or reflected back, and the incident light passing through the connecting structure 130 The process is characterized by the first reflective structure 140 of the reflecting grating 180 to the pixel sensor 110 directed or reflected back. In other words, light escaping to neighboring pixel sensors is prevented. 110 blocked, and as a result, crosstalk occurs between neighboring pixel sensors. 110 It is also reduced. Furthermore, the incident light, which affects the connecting structure, is softened. 130achieved, further through the second reflective structure 170 back to the light detection area 112 reflected, and therefore more light can pass through the photodiode. 112 are absorbed. Accordingly, light is absorbed in the pixel sensors. 110 captured and therefore the quantum efficiency ( QE ) improved.

[0033] In the present disclosure, a BSI image sensor comprising a reflective grating is provided. The reflective grating can include the low-n structure that separates the color filters and the isolation structure that separates the light-sensing areas. More importantly, the reflective grating includes the first reflective structure and the second reflective structure formed in the interconnection structure. The first reflective structure reduces light reaching an adjacent pixel sensor, and the second reflective structure reflects the light back to the photodiode. Accordingly, crosstalk is reduced and the sensitivity of the pixel sensor is improved.Since the first reflective structures and the second reflective structures can be formed in the connection structure, the provided BSI image sensor is also compatible with existing CIS manufacturing without requiring additional operations.

[0034] In some embodiments, a BSI image sensor is provided. The BSI sensor comprises a substrate having a front and a back opposite the front, a pixel sensor arranged in the substrate, an insulating structure surrounding the pixel sensor and arranged in the substrate, a dielectric layer arranged over the pixel sensor on the front of the substrate, and several conductive structures arranged in the dielectric layer and configured to align with the insulating structure.

[0035] In some embodiments, a BSI image sensor is provided. The BSI sensor comprises a substrate having a front and a back opposite the front, a pixel sensor arranged in the substrate, an isolation structure surrounding the pixel sensor and arranged in the substrate, a connecting structure arranged above the substrate on the front, and a first reflective structure arranged in the connecting structure and aligned with the isolation structure.

[0036] In some embodiments, a BSI image sensor is provided. The BSI image sensor comprises a substrate having a front and a back opposite the front, multiple pixel sensors arranged in the substrate, and a reflective grid penetrating the substrate from the front to the back. The pixel sensors are arranged within the reflective grid and separated from each other by the reflective grid.

[0037] The foregoing outlines features of several embodiments so that a person skilled in the art can better understand the aspects of the present disclosure. A person skilled in the art should recognize that they can readily use the present disclosure as a basis for designing or modifying other processes and structures to accomplish the same tasks and / or achieve the same advantages as the embodiments presented herein. A person skilled in the art should also understand that such equivalent embodiments do not deviate from the inventive concept and scope of the present disclosure, and that they can make various changes, substitutions, and modifications here without deviating from the inventive concept and scope of the present disclosure.

Claims

[1] Back-illuminated image sensor (BSI image sensor), comprising: a substrate comprising a front side and a back side opposite the front side, a pixel sensor in the substrate, an isolation structure that surrounds the pixel sensor in the substrate, a dielectric layer over the pixel sensor on the front of the substrate, and several conductive structures arranged in the dielectric layer and designed to be aligned with the insulation structure. [2] BSI image sensor according to claim 1, wherein the pixel sensor is arranged to receive light with a predetermined wavelength. [3] BSI image sensor according to claim 2, wherein the conductive structures are spaced apart from each other by the dielectric layer, and a spacing distance between the conductive structures is less than half of the specified wavelength. [4] BSI image sensor according to claim 3, wherein the spacing distance is less than 0.5 micrometers (µm). [5] BSI image sensor according to claim 3 or 4, wherein each of the conductive structures comprises a diameter, and the diameter is between approximately 0.05 µm and approximately 0.2 µm. [6] BSI image sensor according to any one of the preceding claims 3 to 5, wherein each of the conductive structures comprises a rod-shaped structure spaced apart from each other by the dielectric layer. [7] BSI image sensor according to one of the preceding claims, wherein the conductive structures are in contact with each other to form a frame-shaped structure in the dielectric layer. [8] Back-illuminated image sensor (BSI image sensor), comprising: a substrate comprising a front side and a back side opposite the front side, a pixel sensor in the substrate, an isolation structure that surrounds the pixel sensor in the substrate, a connecting structure above the substrate on the front side, and a first reflective structure that is arranged in the connecting structure and aligned with the isolation structure. [9] BSI image sensor according to claim 8, wherein a width of the first reflective structure is smaller than a width of the isolation structure. [10] BSI image sensor according to claim 8 or 9, wherein the first reflective structure comprises several first conductive contacts and a first conductor, and the first conductive contacts are arranged between the first conductor and the insulation structure. [11] BSI image sensor according to claim 10, wherein a width of the first reflective contacts is smaller than a width of the first conductor. [12] BSI image sensor according to claim 10 or 11, wherein the first conductive contacts are in contact with the insulation structure. [13] BSI image sensor according to any one of the preceding claims 8 to 12, further comprising a second reflective structure arranged in the interconnection structure and overlapping at least one section of the pixel sensor. [14] BSI image sensor according to claim 13, wherein the first reflective structures are electrically isolated from the second reflective structure. [15] BSI image sensor according to one of the preceding claims 13 or 14, wherein the second reflective structure is electrically grounded. [16] BSI image sensor according to any one of the preceding claims 8 to 15, wherein the connection structure further comprises several second conductive contacts and several second conductive features. [17] Back-illuminated image sensor (BSI image sensor), comprising: a substrate comprising a front side and a back side opposite the front side, multiple pixel sensors in the substrate, and a reflective grid that penetrates the substrate from the front to the back, wherein the pixel sensors are arranged within the reflective grid and separated from each other by the reflective grid. [18] BSI image sensor according to claim 17, wherein the reflective grid comprises: a substrate isolation structure that surrounds and is located between the pixel sensors in the substrate, a first reflective structure, which is arranged above the substrate on the front and aligned with the insulation structure, and a low-n structure that is positioned above the substrate on the back side and aligned with the insulation structure. [19] BSI image sensor according to claim 18, further comprising several color filters arranged within the low-n structure above the substrate on the back side. [20] BSI image sensor according to any one of the preceding claims 17 to 19, further comprising several second reflective structures arranged over the pixel sensors on the front side, and each of the second reflective structures overlapping at least one section of each pixel sensor.