CN114975500A

CN114975500A - Pixel unit, image sensor, camera assembly and electronic equipment

Info

Publication number: CN114975500A
Application number: CN202210654541.0A
Authority: CN
Inventors: 祁春超; 孙鹏飞; 王保宁
Original assignee: Hangzhou Hikvision Digital Technology Co Ltd
Current assignee: Hangzhou Hikvision Digital Technology Co Ltd
Priority date: 2022-06-10
Filing date: 2022-06-10
Publication date: 2022-08-30

Abstract

The invention discloses a pixel unit, an image sensor, a camera assembly and electronic equipment, relates to the technical field of image sensors, and solves the technical problems that in the related art, the absorption rate of the pixel unit to incident light with longer wavelength is low, and optical crosstalk is easy to occur between two adjacent pixel units. The pixel unit includes a semiconductor substrate, a light sensitive element, and a metal wiring layer. The metal wiring layer is arranged on one side of the semiconductor substrate far away from the light receiving surface of the photosensitive element. The metal wiring layer includes an interlayer dielectric, a multi-layer metal wiring, and a dimming structure. The multilayer metal wiring is embedded in the interlayer dielectric and electrically connected to the photosensitive element. The dimming structure is embedded in the interlayer medium. The vertical projection of the light-modulating structure on the semiconductor substrate overlaps at least part of the vertical projection of the light-sensitive element on the semiconductor substrate. The light adjusting structure is used for gathering at least part of light irradiated to the light adjusting structure to the photosensitive element. The pixel unit provided by the invention is used for converting an optical signal into an electric signal.

Description

Pixel unit, image sensor, camera assembly and electronic equipment

Technical Field

The present invention relates to the field of image sensors, and in particular, to a pixel unit, an image sensor, a camera assembly, and an electronic device.

Background

The image sensor comprises a plurality of pixel units, wherein photosensitive elements are arranged in the pixel units, so that the pixel units can convert received optical signals into electric signals, and the image sensor can realize an image acquisition function.

In the related art, the pixel units have relatively low absorption efficiency for incident light of long wavelength, such as near infrared light or infrared light, causing difficulty in near infrared imaging, and optical crosstalk easily occurs between adjacent two pixel units, reducing the reliability of use of the image sensor.

Disclosure of Invention

In order to solve the technical problems that the absorption efficiency of a pixel unit for incident light with a long wavelength is low and crosstalk between two adjacent pixel units is easy to occur in the related art, embodiments of the present invention provide a pixel unit, an image sensor, a camera assembly and an electronic device.

In order to achieve the above purpose, the embodiment of the invention adopts the following technical scheme:

in a first aspect, embodiments of the present invention provide a pixel cell including a semiconductor substrate, a photosensitive element, and a metal wiring layer. At least part of the photosensitive element is embedded within the semiconductor substrate. The photosensitive element is provided with a light receiving surface, and the metal wiring layer is arranged on one side of the semiconductor substrate far away from the light receiving surface. The metal wiring layer comprises an interlayer medium, a plurality of layers of metal wirings and a dimming structure. A plurality of metal wirings are embedded in the interlayer dielectric, and the plurality of metal wirings are electrically connected to the photosensitive element. The dimming structure is embedded in the interlayer medium. The vertical projection of the light-modulating structure on the semiconductor substrate overlaps at least part of the vertical projection of the light-sensitive element on the semiconductor substrate. The light adjusting structure is used for gathering at least part of light irradiated to the light adjusting structure to the photosensitive element.

According to the embodiment of the invention, the dimming structure is embedded in the interlayer medium, and the vertical projection of the dimming structure on the semiconductor substrate is overlapped with at least part of the vertical projection of the photosensitive element on the semiconductor substrate, that is, the setting position of the dimming structure corresponds to the setting position of the photosensitive element, so that when light with longer wavelength (such as infrared light or near infrared light and the like) passes through the photosensitive element and irradiates on the dimming structure, the light can be reflected by the dimming structure and gathered to the corresponding photosensitive element, the absorptivity of the photosensitive element on the light (especially light with longer wavelength, such as near infrared light or infrared light) is improved, the quantum efficiency of the light with longer wavelength is enhanced, the near infrared imaging quality is improved, and the service performance of the pixel unit is improved.

Meanwhile, the light passing through the photosensitive elements is reflected to the corresponding photosensitive elements by the arrangement of the dimming structure, the intensity of the light entering the interlayer medium can be reduced, and the light is prevented from irradiating other photosensitive elements under the reflection action of metal wiring or other structures in the interlayer medium, so that the light crosstalk generated between two adjacent photosensitive elements is reduced, namely the light crosstalk between two adjacent pixel units is reduced, and the use reliability of the image sensor is improved.

Optionally, the surface of the metal wiring layer close to the semiconductor substrate is provided with an accommodating hole. The dimming structure includes a blocking layer and a dimming part. The barrier layer covers an inner wall of the accommodation hole. The light adjusting part is embedded in the accommodating hole. The optical refractive index of the light modulation part is not more than that of the semiconductor substrate and is more than that of the interlayer medium. The light refractive index of the light adjusting part is larger than that of the interlayer medium, so that light rays passing through the photosensitive element and irradiating the light adjusting part can be totally reflected on a contact surface of the light adjusting part and the interlayer medium. And, because the optical refractive index of the light modulation part is not more than the optical refraction of the semiconductor substrate, the light in the light modulation part can irradiate into the semiconductor substrate again, namely the light passing through the photosensitive element can irradiate to the photosensitive element again and be absorbed, the absorptivity of the photosensitive element to the light (especially the light with longer wavelength, such as near infrared light or infrared light) is improved, and the quantum efficiency of the light with longer wavelength is enhanced. Meanwhile, light can be prevented from being reflected to other photosensitive elements by structures such as metal wiring in the metal wiring layer, so that optical crosstalk between two adjacent photosensitive elements is reduced, namely optical crosstalk between two adjacent pixel units is reduced, and the use reliability of the image sensor is improved.

In addition, set up the inner wall that the barrier layer covers the accommodation hole for the barrier layer can be located between light modulation portion and the interlaminar medium, plays the effect that blocks through the barrier layer to light, has avoided light to pass in light modulation portion illumination enters into the interlaminar medium, has further reduced the optical crosstalk that produces between two adjacent pixel units, has ensured pixel unit's use reliability.

Optionally, the inner wall of the receiving hole includes a side wall and a bottom wall, and the barrier layer covers at least one of the side wall and the bottom wall. Due to the arrangement, the use flexibility of the pixel unit is improved, and different use requirements are met.

Optionally, the barrier layer is made of a metal material, and when the barrier layer covers the bottom wall, the barrier layer and the metal wiring are made of the same material on the same layer. So set up, ensured the barrier layer to the effect that blocks of light to improved image sensor's processing convenience, shortened pixel unit's process time, reduced pixel unit's manufacturing cost.

Optionally, a portion of one side of the dimming structure close to the semiconductor substrate is exposed from the metal wiring layer. According to the arrangement, the light intensity irradiated to the dimming structure is increased, the light intensity irradiated into the interlayer medium is reduced, the crosstalk between two adjacent pixel units is reduced, and the use reliability of the pixel units is improved. In addition, the surface of the dimming structure close to the semiconductor substrate is flush with the surface of the metal wiring layer close to the semiconductor substrate, the processing convenience of the pixel unit can be improved, and the production cost is reduced.

Optionally, the longitudinal section of the dimming structure is trapezoidal or rectangular, and the longitudinal section of the dimming structure is perpendicular to the semiconductor substrate and the metal wiring layer. So set up, can satisfy the demand of gathering together to the light of different incident angles and different wavelength, improved pixel element's use flexibility.

Optionally, when the longitudinal section of the dimming structure is trapezoidal, the trapezoid includes an upper base and a lower base, the upper base is parallel to the lower base, the length of the upper base is smaller than that of the lower base, the upper base is far away from the semiconductor substrate, and the lower base is flush with the surface of the metal wiring layer on the side close to the semiconductor substrate. So set up, increased the area that the structure of adjusting luminance is close to photosensitive element one side, further ensured that light can shine to the structure of adjusting luminance after passing photosensitive element, increased the intensity that enters into the structure of adjusting luminance internal light to reduce the optical crosstalk who produces between two adjacent pixel units, improve image sensor's use reliability. And, can also make the area that the light modulation structure kept away from light sensitive element one side can be less than the area that the light modulation structure is close to light sensitive element one side, improved the reflection effect of light modulation structure to light, increase shines the light intensity to corresponding light sensitive element again, improved the quantum efficiency of the longer light of wavelength.

Optionally, the pixel unit further includes a filter and a microlens. The optical filter is arranged on one side of the semiconductor substrate close to the light receiving surface and covers the light receiving surface. The micro lens is arranged on one side of the optical filter far away from the semiconductor substrate. So set up for different colours's light can shine to photosensitive element, thereby makes electronic equipment can produce colored image, has improved pixel cell's performance. In addition, the intensity of light irradiating the light receiving surface of the photosensitive element can be improved, so that the pixel unit can normally work in an environment with poor light, and the applicability of the pixel unit is improved.

Optionally, the photosensitive element is a photodiode. By the arrangement, the photoelectric conversion reliability of the photosensitive element is improved, so that the use reliability of the pixel unit is improved.

In a second aspect, embodiments of the present invention provide an image sensor. The image sensor includes a plurality of pixel units as described above in the first aspect, the plurality of pixel units being arranged in an array.

An image sensor provided by an embodiment of the present invention includes the pixel unit of the first aspect, and therefore, all the advantages of the first aspect are achieved, and details are not repeated herein.

Optionally, the image sensor further includes a spacer disposed between the at least two pixel units. By the arrangement, optical crosstalk generated between two adjacent pixel units is further reduced, and the use reliability of the image sensor is improved.

In a third aspect, embodiments of the present invention provide a camera head assembly comprising a lens assembly and an image sensor as described above in the second aspect. The image sensor is arranged on the light-emitting side of the lens component.

The camera head assembly provided by the embodiment of the present invention includes the image sensor of the second aspect, so that all the advantages of the second aspect are achieved, and details are not repeated herein.

In a fourth aspect, embodiments of the present invention provide an electronic device comprising a housing and a camera assembly as in the third aspect above. The shell is provided with a first through hole, and at least part of the camera assembly is embedded in the first through hole.

An electronic device provided by an embodiment of the present invention includes the camera head assembly according to the third aspect, and therefore, all the advantages of the third aspect are provided, and details are not described herein again.

Optionally, the housing is further provided with a second through hole. The electronic device further comprises an emitter, and the emitter is arranged in the second through hole. The emitter is used for emitting light to the object to be measured, and the camera assembly is used for receiving the light reflected by the object to be measured. So set up, further improved camera subassembly to object identification or the accuracy that detects for electronic equipment can realize near-infrared formation of image, thereby improves electronic equipment's use reliability.

Drawings

FIG. 1 is a schematic structural diagram of an electronic device according to an embodiment of the invention;

FIG. 2 is a schematic structural diagram of a camera assembly according to an embodiment of the present invention;

FIG. 3 is a schematic structural diagram of an electronic device according to another embodiment of the invention;

FIG. 4 is a schematic diagram of an image sensor according to an embodiment of the present invention;

FIG. 5 is a schematic cross-sectional view of the image sensor of FIG. 4 along A-A;

FIG. 6 is another schematic cross-sectional view of the image sensor of FIG. 4 taken along the A-A direction;

FIG. 7 is another schematic cross-sectional view of the image sensor of FIG. 4 taken along the A-A direction;

FIG. 8 is a schematic vertical projection of an embodiment of the present invention;

FIG. 9 is a schematic vertical projection view of another embodiment of the present invention;

FIG. 10 is another schematic cross-sectional view of the image sensor of FIG. 4 taken along the A-A direction;

FIG. 11 is another cross-sectional view of the image sensor of FIG. 4 taken along the line A-A;

FIG. 12 is another schematic cross-sectional view of the image sensor of FIG. 4 taken along the A-A direction;

FIG. 13 is another schematic cross-sectional view of the image sensor of FIG. 4 taken along the A-A direction;

FIG. 14 is another schematic cross-sectional view of the image sensor of FIG. 4 taken along the A-A direction;

FIG. 15 is another cross-sectional view of the image sensor of FIG. 4 taken along the line A-A;

FIG. 16 is another schematic cross-sectional view of the image sensor of FIG. 4 taken along the line A-A;

fig. 17 is a flowchart illustrating a method for manufacturing a dimming structure according to an embodiment of the invention.

Detailed Description

Embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

In the description of the present invention, it is to be understood that the terms "center", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc. indicate orientations or positional relationships based on those shown in the drawings, and are merely for convenience of description and simplicity of description, and do not indicate or imply that the devices or elements referred to must have a particular orientation, be constructed in a particular orientation, and be operated, and thus, are not to be construed as limiting the present invention.

The terms "first", "second" and "first" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of the present invention, "a plurality" means two or more unless otherwise specified.

In the description of the present invention, it should be noted that, unless otherwise explicitly specified or limited, the terms "mounted," "connected," and "connected" are to be construed broadly, e.g., as meaning either a fixed connection, a removable connection, or an integral connection; they may be connected directly or indirectly through intervening media, or they may be interconnected between two elements. The specific meanings of the above terms in the present invention can be understood in specific cases to those skilled in the art.

As shown in fig. 1, an embodiment of the present application provides an electronic device 300, where the electronic device 300 may include an electronic product with an image acquisition function, such as a mobile phone (mobile phone), a tablet computer (pad), an intelligent access control, a product detection instrument, a television, an intelligent wearable product (e.g., a smart watch, a smart bracelet), a Virtual Reality (VR) terminal device, an augmented reality (augmented reality AR) terminal device, and the like. The embodiment of the present application does not particularly limit the specific form of the electronic device 300, and the following description is provided for convenience.

In some embodiments, as shown in fig. 1, the electronic device 300 may be a mobile phone or a tablet computer having a face recognition function and a photographing function. Specifically, electronic device 300 includes a housing 310 and a camera assembly 200, it being understood that camera assembly 200 is used to capture image information.

As shown in fig. 2, camera assembly 200 may include a lens assembly 210 and an image sensor 400. In some embodiments, lens assembly 210 may be a combination of convex and concave lenses. The lens assembly 210 includes a light entry side and a light exit side. As shown by the arrows in FIG. 2, light strikes the lens assembly 210 from the light entrance side of the lens assembly 210 and exits from the light exit side of the lens assembly 210. The image sensor 400 is disposed on the light emitting side of the lens assembly 210, so that light emitted from the light emitting side of the lens assembly 210 can be irradiated to the image sensor 400 and converted into an electrical signal by the image sensor 400. Thus, by obtaining the electrical signal converted by the image sensor 400, the image information corresponding to the object to be detected can be obtained, thereby realizing the functions of photographing or face recognition.

As shown in fig. 3, in some implementations, the electronic device 300 can also include a transmitter 320. It is understood that the emitter 320 may be used to emit visible light rays, and may also be used to emit invisible light rays. In particular, when the electronic device 300 needs to perform face recognition, the transmitter 320 may be used to emit invisible light, such as infrared light or near-infrared light. The image sensor 400 receives light reflected by the object to be detected, and realizes near-infrared imaging of the object to be detected. When the electronic device 300 needs to take a picture, the emitter 320 may be used to emit visible light, such as soft light for photography. The visible light emitted by the emitter 320 supplements light to the object to be detected, so that the image sensor 400 can collect images in an environment with poor light, and the use performance of the electronic device 300 is improved.

As can be seen from the above, the image sensor 400 can acquire an image of an object to be detected. In some embodiments, the image sensor 400 may be a Complementary Metal-Oxide Semiconductor (CMOS) image sensor.

The structure of the image sensor 400 will be described below by way of example. As shown in fig. 4, the image sensor 400 includes a plurality of pixel units 100, and it is understood that a photosensitive element, such as a photodiode or a phototransistor, is disposed in the pixel unit 100.

In some examples, the plurality of pixel units 100 are arranged in an array, and for example, as shown in fig. 4, the plurality of pixel units 100 are arranged in a matrix. In other examples, the plurality of pixel units 100 may be arranged in other forms, such as a triangular form or a polygonal form. In still other examples, the plurality of pixel units 100 may be arranged in a scattered manner.

As can be understood, the arrangement of the plurality of pixel units 100 in an array can improve the arrangement regularity of the plurality of pixel units 100, reduce the occupied space of the plurality of pixel units 100, improve the number of the pixel units 100 that can be placed in a unit volume, and facilitate the miniaturization of the image sensor 400.

Specifically, as shown in fig. 5 (fig. 5 is a schematic cross-sectional view of the image sensor along a-a direction in fig. 4), the pixel unit 100 includes a semiconductor substrate 110, and in some embodiments, the material of the semiconductor substrate 110 may be a silicon substrate, a germanium substrate, a silicon-on-insulator substrate, a silicon carbide substrate, or other suitable semiconductor material. At least part of the photosensitive element 120 is embedded within the semiconductor substrate 110. It is to be understood that the photosensor 120 can convert an optical signal into an electrical signal, so that the pixel unit 100 can implement a photoelectric conversion function. It is understood that the photosensor 120 can convert an optical signal of visible light into an electrical signal, and can also convert an optical signal of invisible light into an electrical signal.

The photosensor 120 includes a light-receiving surface 122, and it is understood that the light-receiving surface 122 faces the direction of the external light as shown by the arrow in fig. 5 (fig. 5 is a cross-sectional view of the image sensor along the direction a-a in fig. 4). The photosensor 120 can convert light irradiated to the light receiving surface 122 into an electrical signal. The optical signal irradiated to the other surface can be converted into an electric signal.

With such an arrangement, by obtaining the electrical signals converted by the photosensitive elements 120 of different pixel units 100 and then performing analog-to-digital conversion or amplification and other processing on the electrical signals, light information corresponding to different pixel units 100 can be obtained, thereby realizing an image acquisition function.

In some embodiments, the photosensitive element 120 may be a photodiode. The photoelectric conversion principle of the photosensitive element 120 will be described below by taking a photodiode as an example. In some embodiments, a P-type doped portion and an N-type doped portion are formed in the semiconductor substrate 110, and the P-type doped portion and the N-type doped portion form a PN junction. When light irradiates the photodiode, photons carrying energy enter the PN junction, the energy is transferred to bound electrons on the covalent bonds, and partial electrons break away from the covalent bonds, so that electrons and holes are generated, namely photon-generated carriers. The electrons move to the N-type doped portion and the holes move to the P-type doped portion, so that the photodiode can convert an optical signal into an electrical signal.

In some embodiments, the P-type and N-type dopants may be formed by doping different elements into the semiconductor substrate 110, such as a trivalent boron element and a pentavalent phosphorous element. In some embodiments, the P-type and N-type dopants may also include an I-type semiconductor (i.e., an intrinsic layer semiconductor) therebetween.

In some embodiments, the photosensors 120 of different pixel cells 100 are configured to receive light of different wavelengths, such as red, green, and blue light, and to convert the light signals of different wavelengths into electrical signals.

In some examples, as shown in fig. 5, the pixel unit 100 further includes a circuit structure layer 130, the circuit structure layer 130 includes an interlayer dielectric 132, and a plurality of metal wires 134 are embedded in the interlayer dielectric 132. As shown by the arrow in fig. 5 (fig. 5 is a schematic cross-sectional view of the image sensor in a-a direction in fig. 4), when a light beam with a longer wavelength (e.g., near infrared light or infrared light) is irradiated onto the photosensitive element 120, a portion of the light beam is absorbed by the photosensitive element 120 and converted into an electrical signal, and another portion of the light beam (shown by the dashed arrow in fig. 5) can pass through the photosensitive element 120a and irradiate onto the metal wire 134a, and is reflected by the metal wire 134a to the adjacent photosensitive element 120b, so that optical crosstalk is generated between the adjacent two photosensitive elements 120 (the photosensitive element 120a and the photosensitive element 120b), that is, between the adjacent two pixel units 100 (the pixel unit 100a and the pixel unit 100 b). The reliability of use of the pixel cell 100 is reduced.

It is understood that the pixel unit 100a and the pixel unit 100b may have the same structure or different structures. The pixel unit 100a and the pixel unit 100b in the embodiment of the invention are only for convenience of describing two adjacently disposed pixel units 100, and are not further limited.

As can be seen from the above, the photosensor 120 can convert the optical signal into an electrical signal. As shown in fig. 6 (fig. 6 is another schematic cross-sectional view of the image sensor in fig. 4 along the a-a direction), the metal wiring layer 130 is disposed on the side of the semiconductor substrate 110 away from the light receiving surface 122. Specifically, as shown in fig. 7 (fig. 7 is another schematic cross-sectional view of the image sensor along the a-a direction in fig. 4), the metal wiring layer 130 includes an interlayer dielectric 132, and in some embodiments, the interlayer dielectric 132 may be an insulating material such as silicon oxide or nitrogen oxide, and plays a role in isolating the multilayer metal wiring 134.

A plurality of metal wires 134 are embedded in the interlayer dielectric 132, and the metal wires 134 are electrically connected to the light sensitive element 120, so that the electrical signal converted by the light sensitive element 120 can be transmitted to the outside of the pixel unit 100 through the metal wires 134. In some embodiments, the material of the metal wire 134 may be copper or aluminum, which ensures the electrical conductivity of the metal wire 134. It is understood that the material between the metal wires 134 may be the same or different. In some embodiments, the multi-layer metal wiring 134 may be embedded within the interlayer dielectric 132 by etching.

By disposing the metal wiring layer 130 on the side of the semiconductor substrate 110 away from the light receiving surface 122, the circuit structures such as the metal wiring 134 in the metal wiring layer 130 are prevented from blocking the external light, so that the intensity of the light irradiated to the light sensitive element 120 is ensured, and the performance of the pixel unit 100 is improved. Specifically, the image sensor 400 in which the metal wiring layer 130 is provided on the side of the semiconductor substrate 110 away from the light receiving surface 122 may be referred to as a back-illuminated image sensor.

In some embodiments, as shown in fig. 6 (fig. 6 is another schematic cross-sectional view of the image sensor along the a-a direction in fig. 4), the pixel unit 100 may further include a transfer gate 176. The transfer gate 176 is a Complementary metal Oxide Semiconductor Field Effect transistor (CMOS transistor).

The transfer gate 176 includes a signal receiving terminal, a signal input terminal, and a signal output terminal. The signal receiving terminal is used for receiving the trigger signal, the signal input terminal is electrically connected to the photosensitive element 120, and the signal output terminal is electrically connected to other circuit structures, such as the metal wiring 134. When the signal receiving terminal of the transfer gate 176 receives the trigger signal, conduction between the signal input terminal and the signal output terminal is enabled, so that the electrical signal generated by the light sensitive element 120 can be transmitted out of the light sensitive element 120 through the transfer gate 176.

In some embodiments, as shown in fig. 6 (fig. 6 is another schematic cross-sectional view of the image sensor along the a-a direction in fig. 4), the pixel unit 100 may further include a processing circuit 190, and the processing circuit 190 may include an analog-to-digital conversion circuit 192 and an amplification circuit 194. The processing circuit 190 is electrically connected to the metal wiring 134, so that the processing circuit 190 can receive the electrical signal from the metal wiring 134 and perform analog-to-digital conversion or amplification on the electrical signal.

In order to reduce the crosstalk generated between two adjacent pixel units 100, as shown in fig. 7 (fig. 7 is another schematic cross-sectional view of the image sensor in the a-a direction in fig. 4), the pixel unit 100 provided by the embodiment of the invention may further include a light adjusting structure 136. The light-adjusting structure 136 is embedded in the interlayer medium 132, and it is understood that the light-adjusting structure 136 is used for gathering light, and the cross section of the light-adjusting structure 136 may be trapezoidal or rectangular, etc.

In some embodiments, the inner wall surface of the light modulating structure 136 may be smooth and planar and coated with a reflective coating to achieve a reflective bunching effect on the light. In other embodiments, the light adjusting structure 136 may also be made of a material with a relatively large light refractive index, so that the light can be totally reflected on the inner wall surface of the light adjusting structure 136, thereby achieving the gathering effect on the light.

It will be appreciated that the light modulating structure 136 is capable of changing the direction of illumination of the light. As shown in fig. 8, the vertical projection of the light-adjusting structure 136 on the semiconductor substrate 110 overlaps at least a portion of the vertical projection of the light-sensitive element 120 on the semiconductor substrate 110 (D region in fig. 8), i.e. the setting position of the light-adjusting structure 136 corresponds to the setting position of the light-sensitive element 120. As shown by the direction of the dotted arrow in fig. 7 (fig. 7 is another schematic cross-sectional view of the image sensor in the a-a direction in fig. 4), when light passes through the light sensitive elements 120 and irradiates the light adjusting structure 136, since the set position of the light adjusting structure 136 corresponds to the set position of the light sensitive elements 120, the light adjusting structure 136 can gather at least part of the light irradiating the light adjusting structure 136 to the corresponding light sensitive elements 120.

In some embodiments, as shown in fig. 9, the vertical projection of the light sensor 120 on the semiconductor substrate 110 falls within the vertical projection of the light adjusting structure 136 on the semiconductor substrate 110, further improving the gathering effect of the light adjusting structure 136.

In some embodiments, as shown in fig. 10 (fig. 10 is another cross-sectional view of the image sensor along the a-a direction in fig. 4), the shapes of the dimming structures 136 between the plurality of pixel units 100 may be the same. In other embodiments, as shown in fig. 7 (fig. 7 is another cross-sectional view of the image sensor along the a-a direction in fig. 4), the shape of the light adjusting structure 136 may be different between the plurality of pixel units 100.

As can be seen from the above description, since the light-adjusting structure 136 is embedded in the interlayer medium 132, and the vertical projection of the light-adjusting structure 136 on the semiconductor substrate 110 overlaps at least a portion of the vertical projection of the light-sensitive element 120 on the semiconductor substrate 110, that is, the setting position of the light-adjusting structure 136 corresponds to the setting position of the light-sensitive element 120, so that when light with a longer wavelength (e.g., infrared light or near-infrared light, etc.) passes through the light-sensitive element 120 and irradiates the light-adjusting structure 136, as shown by the direction of the dotted arrow in fig. 10 (fig. 10 is another cross-sectional view of the image sensor in the a-a direction in fig. 4), light with a longer wavelength can be reflected by the light-adjusting structure 136 and gathered to the corresponding light-sensitive element 120, so as to improve the absorption rate of the light-sensitive element 120 for light (especially, light with a longer wavelength, e.g., near-infrared light or infrared light), and enhance the quantum efficiency of light with a longer wavelength, the near infrared imaging quality is improved, and therefore the service performance of the pixel unit 100 is improved.

Meanwhile, the light passing through the photosensitive elements 120 is reflected to the corresponding photosensitive elements 120 by the arrangement of the dimming structure 136, so that the intensity of the light entering the interlayer medium 132 can be reduced, and the light is prevented from irradiating the rest of the photosensitive elements 120 under the reflection action of the metal wiring 134 or other structures in the interlayer medium 132, so that the optical crosstalk generated between two adjacent photosensitive elements 120 (the photosensitive element 120a and the photosensitive element 120b) is reduced, that is, the optical crosstalk between two adjacent pixel units 100 (the pixel unit 100a and the pixel unit 100b) is reduced, and the use reliability of the image sensor 400 is improved.

As can be seen from the above, the dimming structure 136 is embedded in the interlayer dielectric 132. Alternatively, as shown in fig. 11 (fig. 11 is another schematic cross-sectional view of the image sensor along the a-a direction in fig. 4), the surface of the metal wiring layer 130 near the semiconductor substrate 110 has an accommodating hole 138.

It is understood that the receiving hole 138 may have a circular truncated cone shape, a cylindrical shape, or the like, and the shape of the receiving hole 138 is adapted to the shape of the light adjusting structure 136. The accommodation hole 138 is free from the metal wiring 134, so that the influence of the accommodation hole 138 on the transmission of the electric signal is avoided, and the use reliability of the pixel unit 100 is improved.

In some embodiments, as shown in fig. 11 (fig. 11 is another schematic cross-sectional view of the image sensor along the a-a direction in fig. 4), the depth of the receiving hole 138 may be the same as the thickness of the metal wiring layer 130, that is, the receiving hole 138 penetrates through the metal wiring layer 130. In other embodiments, the extension of the receiving hole 138 may be smaller than the thickness of the metal wiring layer 130. It is understood that the depth of the receiving hole 138 may be the same or different between different pixel units 100.

As shown in fig. 12 (fig. 12 is another schematic cross-sectional view of the image sensor along a-a direction in fig. 4), the dimming structure 136 includes a blocking layer 142 and a dimming portion 144. The barrier layer 142 covers the inner wall 152 of the receiving hole 138. The light-adjusting portion 144 is inserted into the receiving hole 138. The optical refractive index of the light adjusting portion 144 is not greater than the optical refractive index of the semiconductor substrate 110 and is greater than the optical refractive index of the interlayer medium 132.

It will be appreciated that the blocking layer 142 acts to block light. In some embodiments, the blocking layer 142 may be made of a metal material, which ensures a light blocking effect. In other embodiments, the barrier layer 142 may also be a non-metallic material, such as rubber or plastic.

The barrier layer 142 covers the inner wall 152 of the receiving hole 138, and it is understood that in some embodiments, as shown in fig. 12 (fig. 12 is another cross-sectional view of the image sensor along the direction a-a in fig. 4), the barrier layer 142 may cover a portion of the inner wall 152, and in other embodiments, as shown in fig. 13 (fig. 13 is another cross-sectional view of the image sensor along the direction a-a in fig. 4), the barrier layer 142 may cover the entire inner wall 152.

The light modulation part 144 is embedded in the accommodation hole 138, and the optical refractive index of the light modulation part 144 is not greater than the optical refractive index of the semiconductor substrate 110 and is greater than the optical refractive index of the interlayer medium 132. That is, the optical refractive index of the dimming part 144 is greater than the optical refractive index of the interlayer medium 132 and less than or equal to the optical refractive index of the semiconductor substrate 110. Understandably, as shown in fig. 12 (fig. 12 is another cross-sectional view of the image sensor along the a-a direction in fig. 4), the optical refractive index of the semiconductor substrate 110 is β 1, the optical refractive index of the light adjusting part 144 is β 2, and the optical refractive index of the interlayer dielectric 132 is β 3, β 3 < β 2 ≦ β 1.

As shown by the direction of the dotted arrow in fig. 12 (fig. 12 is another schematic cross-sectional view of the image sensor in the a-a direction in fig. 4), after the light (e.g., near infrared light or infrared light) passing through the light sensor 120 is irradiated to the light adjusting portion 144, since the light refractive index β 2 of the light adjusting portion 144 is greater than the light refractive index β 3 of the interlayer medium 132, the light can be totally reflected at the contact surface between the light adjusting portion 144 and the interlayer medium 132. Moreover, since the optical refractive index β 2 of the light modulation part 144 is not greater than the optical refractive index β 1 of the semiconductor substrate 110, the light in the light modulation part 144 can be irradiated into the semiconductor substrate 110 again, so that the light passing through the light sensitive element 120 can be irradiated onto the light sensitive element 120 again and absorbed, the absorption rate of the light sensitive element 120 for the light (especially, light with a longer wavelength, such as near infrared light or infrared light) is improved, and the quantum efficiency of the light with the longer wavelength is enhanced. Meanwhile, light can be prevented from being reflected to other photosensitive elements 120 by the metal wiring 134 in the metal wiring layer 130, so that optical crosstalk between two adjacent photosensitive elements 120 is reduced, that is, optical crosstalk between two adjacent pixel units 100 is reduced, and the use reliability of the image sensor 400 is improved.

It is understood that some of the light can pass through the dimming part 144 due to the difference of the incident angle of the light. Therefore, the barrier layer 142 is disposed to cover the inner wall 152 of the accommodating hole 138, so that the barrier layer 142 can be located between the light-adjusting portion 144 and the interlayer medium 132, and the barrier layer 142 can block light.

It can be understood that at least a portion of the light irradiated to the blocking layer 142 can be blocked and reflected by the blocking layer 142, so as to further prevent the light from being irradiated into the interlayer medium 132 through the light-adjusting portion 144, further reduce the optical crosstalk generated between two adjacent pixel units 100, and ensure the reliability of the use of the pixel units 100.

As can be seen from the above, the optical refractive index of the light adjusting portion 144 is not greater than the optical refractive index of the semiconductor substrate 110 and is greater than the optical refractive index of the interlayer medium 132. The material of the light adjuster 144 will be described below. Taking semiconductor substrate 110 as a silicon substrate and interlayer dielectric 132 as silicon dioxide, the optical refractive index of semiconductor silicon (chemical formula is Si) is about 3.42, and the optical refractive index of silicon dioxide (chemical formula is SiO) ₂ ) The optical refractive index of the dimming part 144 is greater than 1.45 and not greater than 3.42, if the optical refractive index of the dimming part is about 1.45.

In some embodiments, the dimming part 144 may be a metal oxide, such as iron sesquioxide (chemical formula is Fe) ₂ O ₃ Optical refractive index of about 2.9), titanium dioxide (chemical formula of TiO) ₂ Optical refractive index of about 2.55) and magnesium oxide (chemical formula MgO, optical refractive index of about 1.76). In other embodiments, the light adjusting part 144 is also a non-metal compound, such as calcium oxide (with a chemical formula of CaO and an optical refractive index of about 1.83), optical glass (with an optical refractive index of about 1.64), and calcium carbide (with a chemical formula of CaC) ₂ The optical refractive index is about 1.75). In other embodiments, the light adjusting unit 144 may be a metal carbide, a compound or a mixture having a refractive index satisfying a condition.

As can be seen from the above, the barrier layer 142 covers the inner wall 152 of the receiving hole 138. Alternatively, as shown in fig. 14 (fig. 14 is another cross-sectional view of the image sensor of fig. 4 taken along the direction a-a), the inner wall 152 of the receiving hole 138 includes a side wall 154 and a bottom wall 156. The barrier layer 142 covers at least one of the sidewalls 154 and the bottom wall 156.

It is understood that the side wall 154 of the receiving hole 138 is connected to the surface of the metal wiring layer 130 on the side close to the semiconductor substrate 110, and the bottom wall 156 of the receiving hole 138 is distant from the semiconductor substrate 110. As shown in fig. 15 (fig. 15 is another schematic cross-sectional view of the image sensor of fig. 4 taken along the direction a-a), the barrier layer 142 may cover the sidewalls 154. As shown in fig. 16 (fig. 16 is another schematic cross-sectional view of the image sensor of fig. 4 along the direction a-a), the blocking layer 142 may also cover the bottom wall 156. As shown in fig. 13 (fig. 13 is another schematic cross-sectional view of the image sensor along the a-a direction in fig. 4), the blocking layer 142 may also cover the sidewall 154 and the bottom wall 156, so as to ensure the light blocking effect of the blocking layer 142 and improve the flexibility of the pixel unit 100.

In some embodiments, as shown in fig. 16 (fig. 16 is another schematic cross-sectional view of the image sensor in the direction a-a in fig. 4), when the depth of the receiving hole 138 is the same as the depth of the metal wiring layer 130, the surface of the blocking layer 142 covering the bottom wall 156 on the side away from the semiconductor substrate 110 is flush with the surface of the metal wiring layer 130 on the side away from the semiconductor substrate 110, so that the structural regularity of the pixel unit 100 is improved.

Optionally, the barrier layer 142 is made of a metal material. When the barrier layer 142 covers the bottom wall 156, the barrier layer 142 and the metal wire 134 are the same material in the same layer.

The blocking layer 142 is made of a metal material, so that the light blocking effect of the blocking layer 142 is further ensured.

It is understood that the same layer refers to a layer structure formed by forming a film layer for forming a specific pattern using the same film forming process and then performing a patterning process using the same mask plate. Depending on the specific pattern, the same patterning process may include multiple exposure, development or etching processes, and the specific pattern in the formed layer structure may be continuous or discontinuous, and the specific patterns may be at different heights or have different thicknesses.

When the barrier layer 142 covers the bottom wall 156, the barrier layer 142 and the metal wiring 134 are made of the same material, so that the processing convenience of the pixel unit 100 is improved, the processing time of the pixel unit 100 is shortened, and the production cost of the pixel unit 100 is reduced.

As can be seen from the above, the dimming structure 136 is embedded in the interlayer dielectric 132. Alternatively, as shown in fig. 12 (fig. 12 is another schematic cross-sectional view of the image sensor along the a-a direction in fig. 4), a portion of one side of the dimming structure 136 close to the semiconductor substrate 110 is exposed from the metal wiring layer 130.

It can be understood that a portion of the dimming structure 136 close to the semiconductor substrate 110 is exposed from the metal wiring layer 130, that is, a side of the dimming portion 144 close to the semiconductor substrate 110 is flush or approximately flush with the metal wiring layer 130, so that light passing through the light sensitive element 120 can irradiate the dimming structure 136 and re-irradiate the light sensitive element 120 under the reflection action of the dimming structure 136, thereby increasing the intensity of light irradiating the dimming structure 136, reducing the intensity of light irradiating the interlayer medium 132, reducing crosstalk between two adjacent pixel units 100, and improving the reliability of the use of the pixel units 100.

Moreover, the surface of the dimming structure 136 close to the semiconductor substrate 110 is flush with the surface of the metal wiring layer 130 close to the semiconductor substrate 110, so that the processing convenience of the pixel unit 100 can be improved, and the production cost can be reduced.

Alternatively, as shown in fig. 7 (fig. 7 is another schematic cross-sectional view of the image sensor in fig. 4 along the direction a-a), the dimming structure 136 has a trapezoidal or rectangular longitudinal section. The longitudinal section of the dimming structure 136 is perpendicular to the semiconductor substrate 110 and the metal wiring layer 130. It is understood that the longitudinal section of the dimming structure 136 may be completely perpendicular to the semiconductor substrate 110 and the metal wiring layer 130, or may be approximately perpendicular.

The cross section of the light adjusting structure 136 is perpendicular to the semiconductor substrate 110 and the metal wiring layer 130, that is, the cross section of the light adjusting structure 136 along the direction from the semiconductor substrate 110 to the metal wiring layer 130 is trapezoidal or rectangular, so that the reflection requirements for light rays with different incident angles and different wavelengths can be met, and the use flexibility of the pixel unit 100 is improved.

In some embodiments, when the cross-section of the light adjusting structure 136 is a trapezoid, the light adjusting structure 136 may have a circular truncated cone shape or a truncated pyramid shape. When the cross-section of the light adjusting structure 136 is rectangular, the light adjusting structure 136 may be a rectangular parallelepiped, a cylinder, or the like.

In some embodiments, when the cross-section of the light adjusting structure 136 is a trapezoid, the area of the trapezoid between the plurality of pixel units 100 may be the same or different. When the cross-section of the light adjusting structure 136 is rectangular, the areas of the rectangles between the plurality of pixel units 100 may be the same or different.

Alternatively, as shown in fig. 10 (fig. 10 is another schematic cross-sectional view of the image sensor in the a-a direction of fig. 4), in the case that the longitudinal section of the light adjusting structure 136 is a trapezoid, the trapezoid includes an upper base and a lower base, and the upper base is parallel to the lower base. It will be appreciated that the upper base and the lower base may be approximately parallel or completely parallel. The length of the upper bottom is less than that of the lower bottom. The upper base is away from the semiconductor substrate 110, and the lower base is flush with the surface of the metal wiring layer 130 on the side close to the semiconductor substrate 110.

It can be understood that the bottom of the trapezoid is flush with the surface of the metal wiring layer 130 close to the semiconductor substrate 110, so that the area of the side of the light-adjusting structure 136 close to the light-sensitive element 120 is increased, it is further ensured that light can irradiate the light-adjusting structure 136 after passing through the light-sensitive element 120, and the intensity of light entering the light-adjusting structure 136 is increased, so as to reduce crosstalk generated between two adjacent light-sensitive elements 120, and improve the reliability of the use of the pixel unit 100.

Moreover, the trapezoidal upper bottom is arranged to be far away from the semiconductor substrate 110, so that the area of one side, away from the photosensitive element 120, of the dimming structure 136 can be smaller than the area of one side, close to the photosensitive element 120, of the dimming structure 136, the gathering effect of the dimming structure 136 on light is improved, the intensity of light re-irradiated to the corresponding photosensitive element 120 is increased, and the quantum efficiency of light with longer wavelength is improved.

As can be seen from the above, the pixel unit 100 can convert the received optical signal into an electrical signal. As shown in fig. 16 (fig. 16 is another schematic cross-sectional view of the image sensor along a-a direction in fig. 4), the pixel unit 100 further includes a filter 162 and a microlens 164. The filter 162 is disposed on the light receiving surface 122 side of the semiconductor substrate 110, and covers the light receiving surface 122. The microlens 164 is disposed on a side of the filter 162 away from the semiconductor substrate 110.

In some embodiments, the optical filters 162 between the plurality of pixel units 100 are used to filter light of different wavelengths, respectively. Specifically, the plurality of pixel units 100 may include filters 162 for filtering red light, green light, and blue light, respectively, so that the red light, the green light, and the blue light can be irradiated to different photosensitive elements 120, respectively, thereby realizing the synthesis of light of a plurality of different colors, so that the electronic device 300 can generate a colored image.

It can be understood that the micro-lens 164 is used to gather light, so as to increase the intensity of the light irradiated to the light receiving surface 122 of the photosensor 120, so that the pixel unit 100 can operate normally in a poor light environment, and the applicability of the pixel unit 100 is improved.

In some embodiments, the number of microlenses 164, the number of photosensors 120, and the number of filters 162 may be the same or different. In some embodiments, the micro lenses 164 may be a combination of various lenses such as a spherical lens, an aspherical lens, a cylinder lens, and a prism, which ensures the light-condensing performance of the micro lenses 164.

As can be seen from the above, the photosensor 120 is used to convert the optical signal into an electrical signal. Optionally, the photosensitive element 120 is a photodiode.

It can be appreciated that by providing the photosensor 120 as a photodiode, the reliability of the photoelectric conversion of the photosensor 120 is improved, thereby improving the reliability of use of the pixel cell 100.

In a second aspect, as shown in fig. 4, an embodiment of the invention provides an image sensor 400, where the image sensor 400 includes a plurality of pixel units 100 as described above, and the plurality of pixel units 100 are arranged in an array.

The image sensor 400 provided by the embodiment of the invention includes a plurality of pixel units 100 as described above, so that all the above advantages are achieved, and the details are not repeated herein.

In some embodiments, image sensor 400 is a back-illuminated image sensor.

As can be seen from the above description, the light adjusting structure 136 can reduce crosstalk between two adjacent pixel units 100. Optionally, as shown in fig. 11 (fig. 11 is another schematic cross-sectional view of the image sensor along the a-a direction in fig. 4), the pixel unit 100 may further include a spacer 166. The spacers 166 are disposed at least between the pixel units 100.

It is understood that the spacers 166 are used to isolate light, so that crosstalk of light generated between adjacent pixel units 100 can be further reduced, and reliability of the image sensor 400 can be improved. In some embodiments, the spacer 166 may be a metal or a non-metal.

In some embodiments, as shown in fig. 11 (fig. 11 is another cross-sectional view of the image sensor along the a-a direction of fig. 4), the spacers 166 include a first spacer 172 and a second spacer 174. The first spacer 172 is disposed between the two filters 162 and functions to block light. Specifically, the first separator 172 may be a metal grid. The second spacer 174 is disposed between the two photosensors 120 and functions to block or reflect light. Specifically, a deep trench isolation trench may be opened in the semiconductor substrate 110 between two photosensors 120, and the second spacer 174 may be embedded in the deep trench isolation trench. In some embodiments, the second spacer 174 may be a metal, a compound or a combination of reflective materials, or the like.

In a third aspect, as shown in FIG. 2, embodiments of the present invention provide a camera assembly 200. Camera head assembly 200 includes lens assembly 210 and image sensor 400 as described above. The image sensor 400 is disposed on the light exit side of the lens assembly 210.

The camera assembly 200 provided by the embodiment of the invention includes the image sensor 400, so that all the above advantages are provided, and the detailed description is omitted.

It will be appreciated that the camera assembly 200 is used to take pictures or video and the lens assembly 210 is a combination of convex and concave lenses. The lens assembly 210 includes a light entry side and a light exit side, and light enters the lens assembly 210 from the light entry side of the lens assembly 210 and exits from the light exit side of the lens assembly 210. The image sensor 400 is disposed on the light-emitting side of the lens assembly 210, and converts the optical signal into an electrical signal.

In some embodiments, the number of the image sensors 400 may be one or more. The number of image sensors 400 and the number of lens assemblies 210 may be the same or different.

In a fourth aspect, as shown in fig. 1, an embodiment of the invention provides an electronic device 300. Electronic device 300 includes a housing 310 and a camera assembly 200. The housing 310 defines a first through-hole, and at least a portion of the camera assembly 200 is inserted into the first through-hole.

The electronic device 300 according to the embodiment of the present invention includes the camera assembly 200, so that all the above advantages are achieved, and are not described herein again.

In some embodiments, the electronic device 300 may be a mobile phone, a computer, or a digital camera. The number of the camera head assemblies 200 may be one or more, and the number of the first through holes is the same as the number of the camera head assemblies 200.

It will be appreciated that at least a portion of the camera assembly 200 is embedded within the first through hole such that light can illuminate the image sensor 400 through the first through hole to effect conversion of the optical signal to an electrical signal.

Optionally, as shown in fig. 3, the housing 310 is further provided with a second through hole. The electronic device 300 further comprises a transmitter 320. The emitter 320 is disposed in the second through hole, the emitter 320 is configured to emit light to the object to be measured, and the camera assembly 200 is configured to receive the light reflected by the object to be measured.

In some embodiments, the emitter 320 is configured to emit invisible light with longer wavelengths, such as near-infrared light or infrared light. The invisible light is received by the camera assembly 200 under the reflection action of the object to be detected, so that the object is identified or detected, the problem that the object cannot be accurately identified or detected under the condition that the light rays of the camera assembly 200 are poor is avoided, the accuracy of the camera assembly 200 in identifying or detecting the object is further improved, and the use reliability of the electronic equipment 300 is improved.

In some embodiments, the number of the emitters 320 may be one or more, and the number of the second through holes is the same as the number of the emitters 320. The number of the emitters 320 is multiple, invisible light is emitted to the object to be detected at different positions, and the identification or detection accuracy of the object to be detected is improved. It will be appreciated that the number of camera head assemblies 200 and emitters 320 may be the same or different.

In one embodiment, as shown in fig. 12, an image sensor 400 is provided, the image sensor 400 being a back-illuminated CMOS image sensor.

The image sensor 400 includes a plurality of pixel units 100 arranged in an array, as shown in fig. 7 (fig. 7 is another schematic cross-sectional view of the image sensor along the a-a direction in fig. 4), the pixel units 100 include a semiconductor substrate 110, and the semiconductor substrate 110 is a silicon substrate. The photosensor 120 is disposed within a silicon substrate, and specifically, the photosensor 120 is a PN-type photodiode. The metal wiring layer 130 is disposed on a side of the photosensor 120 away from the light receiving surface 122. Metal wiring layer 130 includes interlayer dielectric 132, and interlayer dielectric 132 is silicon oxide. Metal wiring 134 is embedded in interlayer dielectric 132 by etching. The light sensing element 120 is electrically connected to the metal wiring 134 so that an electrical signal generated by the light sensing element 120 can be transmitted to the outside through the metal wiring 134.

The pixel cell 100 further includes a transfer gate 176, and the transfer gate 176 is a CMOS transistor. The signal receiving terminal of the transfer gate 176 is used for receiving a trigger signal, the signal input terminal is electrically connected to the light sensitive element 120, and the signal output terminal is electrically connected to the metal wiring 134. When the signal receiving terminal of the transfer gate 176 receives the trigger signal, the signal input terminal and the signal output terminal are connected, and the electrical signal generated by the photosensitive element 120 under illumination is transmitted to the metal wiring 134 through the transfer gate 176 and is transmitted to the outside of the pixel unit 100 through the metal wiring 134.

The dimming structure 136 is embedded within the interlayer dielectric 132, and the dimming structure 136 is disposed opposite the photosensor 120. Specifically, as shown in fig. 11 (fig. 11 is another schematic cross-sectional view of the image sensor along the a-a direction in fig. 4), the metal wiring layer 130 has an accommodating hole 138 formed in a surface thereof near the silicon substrate, and as shown in fig. 12 (fig. 12 is another schematic cross-sectional view of the image sensor along the a-a direction in fig. 4), the light adjusting structure 136 includes a blocking layer 142 and a light adjusting portion 144. The barrier layer 142 is made of metal, and the barrier layer 142 covers the bottom wall 156 of the accommodation hole 138. The light adjusting part 144 is embedded in the accommodating hole 138, and the surface of the light adjusting part 144 close to the silicon substrate is flush with the surface of the metal wiring layer 130 close to the silicon substrate.

Specifically, as shown in fig. 12, a part of the light irradiated to the photosensor 120 is absorbed and converted into an electric signal, and is transmitted to the outside of the pixel unit 100 through the metal wiring 134. And another part of the light (as indicated by the dotted arrow in fig. 12) can pass through the photosensor 120 into the dimming portion 144 due to the longer wavelength, such as near infrared light or infrared light. Since the optical refractive index of the light modulation part 144 is greater than that of the interlayer medium 132, light can be totally reflected on the contact surface between the light modulation part 144 and the interlayer medium 132, and the optical refractive index of the light modulation part 144 is not greater than that of the silicon substrate, and the light can be re-irradiated to the corresponding photosensitive element 120 under the reflection action of the light modulation part 144. The blocking layer 142 covers the bottom wall 156, and can block light, thereby further preventing light in the light adjusting portion 144 from entering the interlayer medium 132.

By providing the light-adjusting part 144 and the blocking layer 142, the absorption efficiency of the light-sensitive element 120 for long-wavelength light (such as near-infrared light or infrared light) is improved, so that the quantum efficiency of light with longer wavelength is improved, the near-infrared imaging quality is improved, and the usability of the pixel unit 100 is ensured.

Moreover, by providing the light-adjusting portion 144 and the blocking layer 142, the intensity of light incident into the interlayer medium 132 can be reduced, light is prevented from being incident into other photosensitive elements 120 under the reflection action of the metal wiring 134 or other circuit structures in the interlayer medium 132, optical crosstalk between two adjacent photosensitive elements 120 is reduced, that is, optical crosstalk between two adjacent pixel units 100 is reduced, and the use reliability of the pixel units 100 is improved.

One surface of the light modulation part 144 close to the silicon substrate is flush with one surface of the metal wiring layer 130 close to the silicon substrate, so that the phenomenon that the distance between the light modulation part 144 and the light sensitive element 120 is too large is avoided, light cannot enter the light modulation part 144 after passing through the light sensitive element 120, the intensity of the light entering the interlayer medium 132 is further reduced, and the optical crosstalk between two adjacent pixel units 100 is reduced.

It is understood that the light adjusting part 144 may be a metal oxide, a non-metal oxide, a metal nitride, a non-metal compound, or a mixture thereof, which improves the flexibility of the pixel unit 100.

As shown in fig. 12 (fig. 12 is another schematic cross-sectional view of the image sensor in fig. 4 along the a-a direction), the cross-section of the light-adjusting structure 136 along the direction from the silicon substrate to the metal wiring layer 130 is a trapezoid, the lower bottom of the trapezoid is flush with one surface of the metal wiring layer 130 close to the silicon substrate, and the upper bottom of the trapezoid is far away from the silicon substrate, so that the intensity of light entering the light-adjusting structure 136 is further increased, the reflection effect of the light-adjusting structure 136 on the light is improved, the optical crosstalk between two adjacent pixel units 100 is reduced, and the reliability of the use of the pixel units 100 is improved.

The method of fabricating the light-modulating structure 136 is illustrated below. In some embodiments, as shown in fig. 17, the method for manufacturing the light adjusting structure 136 includes steps S1 to S4:

step S1, forming a plurality of metal wirings and an interlayer medium between two adjacent metal wirings;

specifically, a layer of interlayer dielectric 132 may be formed first, and then a layer of metal may be laid on the interlayer dielectric 132. Next, a metal wiring 134 is formed by removing a portion of the metal through an etching process. By repeating the above steps, a plurality of metal wires 134 and an interlayer dielectric 132 between two adjacent metal wires 134 can be formed. In addition, a via hole penetrating the interlayer dielectric 132 may be formed on the interlayer dielectric 132, and the via hole may electrically connect the adjacent metal wirings 134.

Step S2, forming an accommodating hole at one side of the structure formed in the step S1, which is close to the semiconductor substrate;

specifically, the receiving hole 138 may be opened in the structure formed in step S1 by etching. As can be appreciated, the accommodation hole 138 is devoid of the metal wiring 134.

Step S3, coating a barrier layer on the inner wall of the accommodating hole;

in step S4, the light control unit is fitted into the accommodation hole.

After the etching of the multiple layers of metal wires 134 is completed, the accommodating hole 138 is formed in the surface of the metal wire layer 130 close to the semiconductor substrate 110, so that the influence of the etching of the metal wires 134 on the light-adjusting structure 136 is avoided, and the use reliability of the pixel unit 100 is further improved.

As shown in fig. 16 (fig. 16 is another schematic cross-sectional view of the image sensor along the a-a direction in fig. 4), the pixel unit 100 further includes an optical filter 162 and a microlens 164. The filter 162 is provided on one side of the light receiving surface 122 and covers the light receiving surface 122. Specifically, the image sensor 400 includes a plurality of filters 162, and the plurality of filters 162 are respectively used for filtering light of different wavelengths, so that red light, filtered light, and blue light can be irradiated to the photosensitive element 120 through the filters 162, respectively. The micro-lenses 164 are disposed on a side of the optical filter 162 away from the silicon substrate, and the micro-lenses 164 are used to focus light.

As shown in fig. 11 (fig. 11 is another cross-sectional view of the image sensor along the a-a direction in fig. 4), the image sensor 400 further includes a first spacer 172 and a second spacer 174. Specifically, the first spacer 172 is a metal grid disposed between the two optical filters 162, and reduces optical crosstalk between the two optical filters 162. A back deep trench isolation trench is formed in the silicon substrate between the two photosensors 120, and the second spacer 174 is embedded in the back deep trench isolation trench to reduce crosstalk between the two photosensors 120, thereby further improving the reliability of the image sensor 400. Specifically, the second spacer 174 is made of metal.

In the description herein, particular features, structures, materials, or characteristics may be combined in any suitable manner in any one or more embodiments or examples.

The above description is only for the specific embodiments of the present invention, but the scope of the present invention is not limited thereto, and any person skilled in the art can easily conceive of the changes or substitutions within the technical scope of the present invention, and all the changes or substitutions should be covered within the scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the protection scope of the appended claims.

Claims

1. A pixel unit is characterized by comprising a semiconductor substrate, a photosensitive element and a metal wiring layer, wherein at least part of the photosensitive element is embedded in the semiconductor substrate; the photosensitive element is provided with a light receiving surface; the metal wiring layer is arranged on one side, away from the light receiving surface, of the semiconductor substrate;

wherein the metal wiring layer includes:

an interlayer dielectric;

a plurality of metal wirings embedded in the interlayer dielectric, the plurality of metal wirings being electrically connected to the photosensitive element;

a light modulating structure embedded within the interlayer dielectric, a vertical projection of the light modulating structure on the semiconductor substrate overlapping at least a portion of a vertical projection of the light sensitive element on the semiconductor substrate; the light adjusting structure is used for gathering at least part of light irradiated to the light adjusting structure to the photosensitive element.

2. The pixel unit according to claim 1, wherein a surface of the metal wiring layer adjacent to the semiconductor substrate has an accommodating hole, and the light adjusting structure comprises:

a barrier layer covering an inner wall of the accommodation hole;

and the light adjusting part is embedded in the accommodating hole, and the optical refractive index of the light adjusting part is not more than that of the semiconductor substrate and is more than that of the interlayer medium.

3. The pixel cell of claim 2, wherein the inner wall of the receiving hole includes a sidewall and a bottom wall, and the barrier layer covers at least one of the sidewall and the bottom wall.

4. The pixel unit of claim 3, wherein the blocking layer is made of a metal material, and when the blocking layer covers the bottom wall, the blocking layer and the metal wiring are made of the same material in the same layer.

5. The pixel unit of claim 1, wherein a portion of a side of the dimming structure adjacent to the semiconductor substrate is exposed from the metal wiring layer.

6. The pixel unit according to claim 5, wherein the dimming structure has a trapezoidal or rectangular longitudinal cross section, and the longitudinal cross section of the dimming structure is perpendicular to the semiconductor substrate and the metal wiring layer.

7. The pixel unit according to claim 6, wherein in a case that a longitudinal section of the dimming structure is a trapezoid, the trapezoid includes an upper base and a lower base, the upper base is parallel to the lower base, a length of the upper base is smaller than a length of the lower base, the upper base is far away from the semiconductor substrate, and the lower base is flush with a surface of the metal wiring layer on a side close to the semiconductor substrate.

8. The pixel cell of claim 1, further comprising:

the optical filter is arranged on one side, close to the light receiving surface, of the semiconductor substrate and covers the light receiving surface;

and the micro lens is arranged on one side of the optical filter, which is far away from the semiconductor substrate.

9. The pixel cell of any one of claims 1-8, wherein the photosensitive element is a photodiode.

10. An image sensor comprising a plurality of pixel cells according to any one of claims 1 to 9, the plurality of pixel cells being arranged in an array.

11. The image sensor of claim 10, further comprising:

and the separator is arranged between at least two pixel units.

12. A camera head assembly, comprising:

a lens assembly;

the image sensor of claim 10 or 11, disposed on a light exit side of the lens assembly.

13. An electronic device, comprising:

the shell is provided with a first through hole;

a camera assembly according to claim 12, at least part of the camera assembly being embedded within the first through-hole.

14. The electronic device of claim 13, wherein the housing further defines a second through hole, the electronic device further comprising:

the emitter is arranged in the second through hole and used for emitting light to an object to be detected, and the camera assembly is used for receiving the light reflected by the object to be detected.