CN118866928B - Image sensor and manufacturing method thereof - Google Patents
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Abstract
本发明公开了一种图像传感器及其制作方法，属于半导体技术领域，所述图像传感器包括：衬底；底部隔离层，设置在所述衬底中，所述底部隔离层与所述衬底一表面贴合；多层材料层，设置在所述底部隔离层上，在所述材料层的生长方向上，相邻两层所述材料层交迭设置；深沟槽隔离结构，设置在所述材料层中，所述深沟槽隔离结构将所述材料层隔离成多种类型的光电感应区；格栅，设置在所述深沟槽隔离结构上；以及彩色滤光片，设置在所述光电感应区上。通过本发明提供的一种图像传感器及其制作方法，提高图像传感器的性能并简化制成。
The present invention discloses an image sensor and a manufacturing method thereof, belonging to the field of semiconductor technology, wherein the image sensor comprises: a substrate; a bottom isolation layer, arranged in the substrate, the bottom isolation layer being bonded to a surface of the substrate; a plurality of material layers, arranged on the bottom isolation layer, and two adjacent material layers being arranged overlappingly in the growth direction of the material layers; a deep trench isolation structure, arranged in the material layers, the deep trench isolation structure isolating the material layers into various types of photoelectric sensing regions; a grid, arranged on the deep trench isolation structure; and a color filter, arranged on the photoelectric sensing region. The image sensor and the manufacturing method thereof provided by the present invention can improve the performance of the image sensor and simplify the manufacturing process.
Description
Technical Field
The invention belongs to the technical field of semiconductors, and particularly relates to an image sensor and a manufacturing method thereof.
Background
The image sensor is a device for converting an optical signal into an electrical signal, and is widely used in fields such as photography and security systems, smart phones, facsimile machines, scanners, and medical electronics.
The photoelectric sensing area of the image sensor can sense the optical signal and convert the optical signal into an electric signal. However, the formation of the photo-sensing region requires high energy ion implantation, which causes damage to the substrate. And electron holes are easily generated in the photoelectric sensing region formed by the damaged substrate, and electrons flow to the photoelectric sensing region or other structural layers through the peripheral damaged region. Thus, crosstalk is generated between adjacent photo-sensing regions and between the photo-sensing regions and other structural layers. In addition, for some image sensors, it is necessary to form electrical signals of different intensities. At this time, the intensity of the optical signal of each photoelectric sensing area needs to be adjusted to meet the requirement of the image sensor on the intensity of the electrical signal, which has a great influence on the manufacture of the image sensor.
Disclosure of Invention
The invention aims to provide an image sensor and a manufacturing method thereof, which can improve the performance of the image sensor, reduce leakage current, reduce signal crosstalk and form electric signals with different intensities.
In order to solve the technical problems, the invention is realized by the following technical scheme:
the present invention provides an image sensor including:
A substrate;
The bottom isolation layer is arranged in the substrate and is attached to one surface of the substrate;
The multi-layer material layers are arranged on the bottom isolation layer, and two adjacent material layers are overlapped in the growth direction of the material layers;
the deep groove isolation structure is arranged in the material layer and isolates the material layer into a plurality of types of photoelectric sensing areas;
a grating disposed on the deep trench isolation structure, and
And the color filter is arranged on the photoelectric sensing area.
In an embodiment of the present invention, the multiple material layers include a first material layer disposed on the bottom isolation layer, and a first groove is disposed in the first material layer, and the first groove exposes the bottom isolation layer.
In one embodiment of the present invention, the multi-layer material layer comprises:
A second material layer disposed on the first material layer and covering the first material layer and the first groove, a second groove formed in the second material layer and located on the first groove, and
And the third material layer is arranged on the second material layer and covers the second material layer.
In an embodiment of the present invention, the plurality of types of photo-sensing regions include a first type of photo-sensing region, the first type of photo-sensing region includes the first material layer, the second material layer, and the third material layer, and the second material layer is located on the first material layer, and the third material layer is located on the second material layer.
In an embodiment of the present invention, the multiple types of photo-sensing regions include a second type of photo-sensing region, where the second type of photo-sensing region includes the first material layer, the second material layer, and the third material layer, and a portion of the second material layer is located on the first material layer, a portion of the second material layer is located in the first groove, a portion of the third material layer is located on the second material layer, and the third material layer fills the second groove.
In an embodiment of the present invention, the plurality of types of photo-sensing regions include a third type of photo-sensing region, the third type of photo-sensing region includes the second material layer and the third material layer, the second material layer is located on the bottom isolation layer, and the third material layer is located on the second material layer.
In an embodiment of the invention, the image sensor includes a top isolation layer, and the top isolation layer is located on the surface of the photo-sensing region.
In an embodiment of the present invention, the grid includes a high dielectric constant material layer, an aluminum metal layer and a titanium nitride layer, wherein the high dielectric constant material layer is located on the deep trench isolation structure, the aluminum metal layer is located on the high dielectric constant material layer, and the titanium nitride layer is located on the aluminum metal layer.
The invention also provides a manufacturing method of the image sensor, which comprises the following steps:
A substrate is provided and a substrate is provided,
Forming a bottom isolation layer in the substrate, wherein the bottom isolation layer is attached to one surface of the substrate;
Forming a plurality of material layers on the bottom isolation layer, wherein two adjacent material layers are overlapped in the growth direction of the material layers;
forming a deep trench isolation structure in the material layer, wherein the deep trench isolation structure isolates the material layer into a plurality of types of photoelectric sensing areas;
Forming a grating on the deep trench isolation structure, and
And forming a color filter on the photoelectric sensing region.
In one embodiment of the present invention, forming the plurality of types of photo-sensing regions includes the steps of:
forming a first material layer on the bottom isolation layer, and forming a first groove in the first material layer;
forming a second material layer on the first material layer, wherein the second material layer covers the first material layer, and a second groove is formed in the second material layer;
Forming a third material layer on the second material layer;
forming a top isolation layer and a hard mask layer on the third material layer;
Patterning the hard mask layer and etching the top isolation layer, the third material layer, the second material layer, the first material layer and a portion of the bottom isolation layer not covered by the hard mask layer to form a deep trench, and
And depositing a medium in the deep groove to form a deep groove isolation structure, wherein the deep groove isolation structure isolates the first material layer, the second material layer and the third material layer into a plurality of types of photoelectric sensing areas.
In summary, the image sensor and the manufacturing method thereof provided by the present application have the unexpected effect that the multi-layer material layer is used to form the photo-sensing region, so as to increase the electron concentration in the photo-sensing region, and further increase the strength of the generated electrical signal. Meanwhile, the material layer is formed in a layer-by-layer growth mode, so that electron holes are not easy to generate in the formed photoelectric sensing areas, and crosstalk generated between adjacent photoelectric sensing areas and between the photoelectric sensing areas and other structural layers is improved. In addition, by forming different types of photoelectric sensing areas, the application can generate electric signals with different intensities for the same optical signal, thereby meeting the requirements of some image sensors for forming electric signals with different intensities. In addition, the grid formed in the application comprises a high dielectric constant material layer, an aluminum metal layer and a titanium nitride layer, so that not only can the adjacent photoelectric sensing areas be well isolated, but also the light shielding effect can be well achieved, and the generation of dark current can be reduced.
Of course, it is not necessary for any one product to practice the invention to achieve all of the advantages set forth above at the same time.
Drawings
In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings that are needed for the description of the embodiments will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and that other drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.
Fig. 1 is a schematic structure of a shallow trench isolation structure according to an embodiment.
FIG. 2 is a schematic diagram of a structure for forming a bottom isolation layer in an embodiment.
FIG. 3 is a schematic diagram of a structure for forming a removed portion of a substrate in one embodiment.
Fig. 4 is a schematic structural diagram illustrating formation of a first material layer according to an embodiment.
FIG. 5 is a schematic diagram illustrating a structure of forming a photoresist layer according to an embodiment.
Fig. 6 is a schematic structural diagram of forming a first groove in an embodiment.
Fig. 7 is a schematic structural diagram illustrating formation of a second material layer according to an embodiment.
Fig. 8 is a schematic structural diagram illustrating formation of a third material layer according to an embodiment.
FIG. 9 is a schematic diagram of a planarization structure for forming a third material layer in an embodiment.
FIG. 10 is a schematic diagram of a structure for forming a top isolation layer and a hard mask layer in one embodiment.
FIG. 11 is a schematic diagram of a structure for forming a patterned hard mask layer in an embodiment.
Figure 12 is a schematic diagram of a structure for forming deep trenches in one embodiment.
Figure 13 is a schematic diagram of a structure for forming deep trench isolation structures in one embodiment.
FIG. 14 is a schematic diagram of a structure of forming a high-k material layer, an aluminum metal layer, and a titanium nitride layer according to an embodiment.
FIG. 15 is a schematic view of a structure for forming a grating in an embodiment.
Fig. 16 is a schematic diagram of a structure of a color filter according to an embodiment.
Description of the reference numerals:
100. The semiconductor device comprises a substrate, a shallow trench isolation structure, 102, an etching stop layer, 103, a metal interconnection layer, 104, a bottom isolation layer, 105, a first material layer, 1051, a first groove, 106, a photoresist layer, 1061, a first opening, 107, a second material layer, 1071, a second groove, 108, a third material layer, 109, a top isolation layer, 110, a hard mask layer, 1101, a second opening, 111, a deep trench, 112, a deep trench isolation structure, 113, a grid, 1131, a high dielectric constant material layer, 1132, an aluminum metal layer, 1133, a titanium nitride layer, 114 and a color filter.
Detailed Description
Other advantages and effects of the present invention will become apparent to those skilled in the art from the following disclosure, which describes the embodiments of the present invention with reference to specific examples. The invention may be practiced or carried out in other embodiments that depart from the specific details, and the details of the present description may be modified or varied from the spirit and scope of the present invention.
It should be noted that, the illustrations provided in the present embodiment merely illustrate the basic concept of the present invention by way of illustration, and only the components related to the present invention are shown in the drawings and are not drawn according to the number, shape and size of the components in actual implementation, and the form, number and proportion of the components in actual implementation may be arbitrarily changed, and the layout of the components may be more complex.
In the present application, it should be noted that, as terms such as "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc., appear, the indicated orientation or positional relationship is based on that shown in the drawings, only for convenience of description and simplification of the description, and does not indicate or imply that the apparatus or element in question must have a specific orientation, be constructed and operated in a specific orientation, and thus should not be construed as limiting the application. Furthermore, the terms "first," "second," and the like, as used herein, are used for descriptive and distinguishing purposes only and are not to be construed as indicating or implying a relative importance.
The image sensor includes a pixel array and a logic control region. The pixel array is provided with a plurality of photoelectric sensing areas which are arranged in an array, each photoelectric sensing area forms a pixel unit, the plurality of photoelectric sensing areas form the pixel array, a scene is focused on the pixel array of the image sensor through the imaging lens, and the photoelectric sensing areas can convert optical signals on the surface of the scene into electric signals. The logic control area comprises a plurality of logic control devices, and the plurality of logic control devices can control the photoelectric sensing area to perform photoelectric conversion to form an electric signal, quantize the electric signal through analog-to-digital conversion and read out the converted digital signal.
Referring to fig. 1 to 15, in an embodiment of the invention, an image sensor includes a substrate 100, and the substrate 100 has a first surface and a second surface opposite to each other. In the substrate 100, and on the side near the first surface, a bottom isolation layer 104 is provided. On the first surface of the substrate 100, a plurality of material layers are provided. In the multi-layer material layer, a deep trench isolation structure 112 is provided, and the deep trench isolation structure 112 isolates the multi-layer material layer into a plurality of photo-sensing regions. On the deep trench isolation structure 112, a grating 113 is provided. On the photo-sensing region, a color filter 114 is provided. In the substrate 100, and on a side close to the second surface, a plurality of shallow trench isolation structures 101 are provided. On the second surface of the substrate 100, an etch stop layer 102 and a metal interconnection layer 103 are provided. Wherein the etch stop layer 102 is located on the second surface of the substrate 100, and the metal interconnection layer 103 is located on the etch stop layer 102.
The first surface and the second surface are two surfaces for distinguishing the substrate, wherein the first surface is a surface of the image sensor receiving the incident light, and the second surface is opposite to the first surface.
Specifically, referring to fig. 1, in an embodiment of the present application, the substrate 100 may be any suitable semiconductor material, such as silicon, silicon carbide (SiC), gallium nitride (GaN), aluminum nitride (AlN), indium nitride (InN), germanium silicide (GeSi), etc., and may also include a stacked structure formed by these semiconductors, or be silicon on insulator, silicon germanium on insulator, etc. In this embodiment, the substrate 100 is, for example, a silicon substrate. In the present application, the thickness of the substrate 100 is, for example, 3um.
Referring to fig. 1, in an embodiment of the present invention, a shallow trench isolation structure 101 is disposed in a substrate 100. The shallow trench isolation structure 101 is located on one side of the substrate 100 and on a side close to the second surface. In this embodiment, the shallow trench isolation structure 101 extends from the second surface of the substrate 100 into the substrate 100. Specifically, a photoresist layer (not shown) may be formed on the second surface of the substrate 100, and a patterned photoresist layer (not shown) may be formed by exposing and developing, etc., where the patterned photoresist layer may define the locations of the shallow trenches. And quantitatively removing part of the substrate 100 under the patterned photoresist layer by using the patterned photoresist layer as a mask and adopting etching modes such as dry etching, wet etching or combination of the dry etching and the wet etching to obtain the shallow trench. After the shallow trench is formed, an isolation medium, such as an insulating material such as silicon oxide, is deposited in the shallow trench. And a planarization process such as chemical mechanical Polishing (CHEMICAL MECHANICAL CMP) is performed to planarize the top of the isolation medium, thereby forming a plurality of shallow trench isolation structures 101.
Referring to fig. 1, in an embodiment of the present invention, after forming a shallow trench isolation structure 101, an etching stop layer 102 is formed on a second surface of a substrate 100, and a metal interconnection layer 103 is formed on the etching stop layer 102. Specifically, a chemical vapor deposition (Chemical Vapor Deposition, CVD) process may be used to deposit silicon oxide (SiO 2) or silicon carbonitride (SiCN) as the etch stop layer 102 on the second surface of the substrate 100 and the surface of the shallow trench isolation structure 101. A silicon oxide dielectric is then deposited over the etch stop layer 102, a plurality of openings are formed in the silicon oxide dielectric, and a conductive material is deposited within the openings to form a metal interconnect layer 103. The metal interconnection layer 103 can output an electric signal formed in the photoelectric sensing region.
Referring to fig. 1 to 2, in an embodiment of the present application, after forming the metal interconnection layer 103, ions are implanted into the substrate 100 on the first surface of the substrate 100 to form the bottom isolation layer 104. Specifically, boron ions may be implanted into the substrate 100 to form the bottom spacer 104. In the present application, the bottom isolation layer 104 is located in the substrate 100, and one side of the bottom isolation layer 104 is in contact with the shallow trench isolation structure 101. After the bottom isolation layer 104 is formed, the substrate 100 on the bottom isolation layer 104 is etched away, so that the other side of the bottom isolation layer 104 is bonded to the surface of the etched substrate 100. As shown in connection with fig. 3, after forming the bottom isolation layer 104, the substrate 100 on the bottom isolation layer 104 may be removed using a planarization process by chemical mechanical polishing or the like.
Referring to fig. 4 to 13, in an embodiment of the present application, after forming the bottom isolation layer 104 and removing the substrate 100 on the bottom isolation layer 104, a multi-layer material layer is formed on the bottom isolation layer 104, and a deep trench isolation structure 112 is formed in the material layer, wherein the deep trench isolation structure 112 isolates the multi-layer material layer into a plurality of photo sensing regions. In the present application, three material layers are provided on the bottom spacer layer 104. In other embodiments, four, five, or more layers of material are provided on the bottom spacer layer 104. Wherein the material layer is formed using a compound of a group VA element and silicon. The group VA element comprises nitrogen (N), phosphorus (P), arsenic (As), antimony (Sb), bismuth (Bi), and molybdenum (Mc), and the material layer can be silicon phosphide, silicon arsenide or silicon antimonide. In the present application, the closer to the surface of the photo-sensing region, the greater the mass of the material layer. Because the material layer is doped by using the VA group element, the material layer with larger mass is arranged at the position close to the surface of the image sensor, the doping concentration of the center position of the photoelectric sensing area can be improved, the problem that the doping concentration of the surface of the photoelectric sensing area is smaller when the material layer is formed by using one compound is avoided, and further, the material layers with different thicknesses in the photoelectric sensing area all have higher doping concentrations, so that the quality of the image sensor is improved.
Referring to fig. 4 to 8, in an embodiment of the present invention, three material layers are disposed on the bottom isolation layer 104. I.e. on the bottom spacer layer 104, a first material layer 105, a second material layer 107 and a third material layer 108 are provided. The first material layer 105 is located on the bottom isolation layer 104, the second material layer 107 is located on the first material layer 105, the third material layer 108 is located on the second material layer 107, the first material layer 105 is a silicon phosphide layer, the second material layer 107 is a silicon arsenide layer, and the third material layer 108 is a silicon antimonide layer. And the first material layer 105, the second material layer 107, and the third material layer 108 may be deposited by chemical vapor deposition.
Referring to fig. 4 to fig. 6, in an embodiment of the invention, the first material layer 105 is located on the bottom isolation layer 104, and a plurality of first grooves 1051 are disposed in the first material layer 105, and the positions of the first grooves 1051 may be set according to the requirements of the type of the photo-sensing region. When forming the first material layer 105, a silicon source gas and a phosphorus source gas are introduced into the heated reaction chamber, hydrogen is used as a carrier gas, the silicon source gas and the phosphorus source gas react at a high temperature, and silicon phosphide is generated on the surface of the bottom isolation layer 104 as the first material layer 105. A photoresist layer 106 is then formed on the first material layer 105, and a first opening 1061 is formed on the photoresist layer 106, the first opening 1061 being used to define a location of the first recess 1051. Then, the first material layer 105 is dry etched using the photoresist layer 106 as a mask, and a first trench 1051 is formed in the first material layer 105. Wherein the first recesses 1051 expose the bottom spacer layer 104 at the bottom of the first material layer 105.
Referring to fig. 6 to 7, in an embodiment of the present invention, after forming the first material layer 105, the second material layer 107 is formed on the first material layer 105. A plurality of second grooves 1071 are also provided in the second material layer 107, the second grooves 1071 being located on the first grooves 1051, and the depth of the second grooves 1071 being less than the depth of the first grooves 1051. In forming the second material layer 107, a silicon source gas and an arsenic source gas are introduced into the heated reaction chamber, and hydrogen gas is used as a carrier gas, and the silicon source gas and the arsenic source gas react at a high temperature to generate silicon arsenide as the second material layer 107 on the surface of the first material layer 105 and in the first grooves 1051. In forming the second material layer 107, since the first groove 1051 is deeper, the second material layer 107 located on the surface of the first material layer 105 is higher than the second material layer 107 located in the first groove 1051, and thus the second groove 1071 is formed in the second material layer 107, and the second groove 1071 is located on the first groove 1051.
Referring to fig. 7 to 9, in an embodiment of the present invention, after forming the second material layer 107, a third material layer 108 is formed on the second material layer 107. And the surface of the third material layer 108 is ground to form a third material layer 108 with a flat surface. In forming the third material layer 108, a silicon source gas and an antimony source gas are introduced into the heated reaction chamber, and hydrogen is used as a carrier gas, and the silicon source gas and the antimony source gas react at a high temperature to generate silicon antimonide on the surface of the bottom isolation layer 104 as the third material layer 108. Shallow grooves may also be present on the surface of the deposited third material layer 108. After the third material layer 108 is deposited, the surface of the third material layer 108 may be subjected to chemical mechanical polishing to form a third material layer 108 with a flat surface.
Referring to fig. 9 to 11, in an embodiment of the present invention, after forming the third material layer 108, a top isolation layer 109 and a hard mask layer 110 are deposited on the third material layer 108, and the top isolation layer 109 is located on the third material layer 108, and the hard mask layer is located on the top isolation layer 109. Specifically, a layer of tantalum pentoxide with a high dielectric constant may be deposited on the third material layer 108 as the top isolation layer 109, and then a layer of nitride may be deposited as the hard mask layer 110. Thereafter, the hard mask layer 110 is etched, and a second opening 1101 is formed on the hard mask layer 110. Wherein the second opening 1101 is used to define the location of the deep trench isolation structure 112.
Referring to fig. 11 to 13, after forming the second opening 1101 on the hard mask layer 110, a deep trench 111 is formed in the bottom portion of the second opening 1101 by etching the top isolation layer 109, the third material layer 108, the second material layer 107, the first material layer 105 and a portion of the bottom isolation layer 104, wherein the deep trench 111 extends from the top isolation layer 109 to the bottom isolation layer 104. A dielectric is then deposited in the deep trenches 111 to form deep trench isolation structures 112. In this embodiment, the medium deposited in the deep trench 111 is, for example, silicon oxide (SiO 2). After forming the deep trench isolation structure 112, chemical mechanical polishing is performed on top of the deep trench isolation structure 112, thereby removing the hard mask layer 110 and making the deep trench isolation structure 112 flush with the top isolation layer 109.
Referring to fig. 4 to 13, in an embodiment of the present invention, by forming the first groove 1051 in the first material layer 105, the second material layer 107 and the first material layer 105 overlap in the growth direction, and the second groove 1071 is formed in the second material layer 107 above the first groove 1051. And since the second groove 1071 is formed in the second material layer 107, the third material layer 108 and the second material layer 107 overlap in the growth direction. Then, the first material layer 105, the second material layer 107, and the third material layer 108 are separated into a plurality of types of photo sensing regions by isolation of the deep trench isolation structures 112.
Referring to fig. 13, in an embodiment of the present invention, the deep trench isolation structure 112 isolates the first material layer 105, the second material layer 107 and the third material layer 108 into three types of photo sensing regions. The first type of photo-sensing region includes a first material layer 105, a second material layer 107, and a third material layer 108, where the second material layer 107 is located on the first material layer 105 and the third material layer 108 is located on the second material layer 107. The second type of photo-sensing region includes a first material layer 105 and a second material layer 107, with a portion of the second material layer 107 being located on the first material layer 105, a portion of the second material layer 107 being located in the first recess 1051, a third material layer 108 being located on the second material layer 107, and the third material layer 108 filling the second recess 1071. The third type of photo-sensing region includes a second material layer 107 and a third material layer 108, and the second material layer 107 is located on the isolation layer, and the third material layer 108 is located on the second material layer 107.
Referring to fig. 13, in the present application, since the material layers forming the photo-sensing regions are different in type or structure, the electrons generated by the photo-sensing regions of different types are different for the same optical signal, so as to generate electrical signals with different intensities. In this embodiment, for the same optical signal, the number of electrons generated by the first type of photo-sensing region is greater than the number of electrons generated by the second type of photo-sensing region, which generates a greater number of electrons than the third type of photo-sensing region. Thus, in forming the image sensor, for the different types of photo sensing regions that need to be formed, the different types of photo sensing regions can be formed by providing the location of the first recesses 1051 and the location of the deep trench isolation structures 112.
Referring to fig. 4 to 13, in the application, a layer-by-layer growth method is used to form multiple material layers, so that electron holes are not easy to generate in the formed photo-sensing regions, and crosstalk between adjacent photo-sensing regions and between the photo-sensing regions and other structural layers is improved. Meanwhile, the deep trench isolation structure 112 and the bottom isolation layer 104 surround the photoelectric sensing regions, so that crosstalk between adjacent photoelectric sensing regions is further reduced. Furthermore, the application forms the photoelectric sensing area by using a plurality of material layers, which can increase the electron concentration in the photoelectric sensing area, thereby increasing the intensity of the generated electric signal. Meanwhile, by forming different types of photoelectric sensing areas, the application can generate electric signals with different intensities for the same optical signal, so that the same image sensor is provided with the photoelectric sensing areas for generating various electric signals.
Referring to fig. 14 to 15, in one embodiment of the present application, after forming the material layer and the deep trench isolation structure 112, a grating 113 is formed on the deep trench isolation structure 112. The grid 113 is located on the deep trench isolation structure 112, and an orthographic projection of the grid 113 on the material layer covers the deep trench isolation structure 112. In the present application, the grating 113 includes a high dielectric constant material layer 1131, an aluminum metal layer 1132, and a titanium nitride layer 1133.
Referring to fig. 14 to 15, in an embodiment of the present invention, a layer of tantalum pentoxide may be deposited on the material layer and the deep trench isolation structure 112 as the high dielectric constant material layer 1131, then a layer of metal aluminum is deposited on the high dielectric constant material layer 1131 to form an aluminum metal layer 1132, and finally titanium nitride is deposited on the aluminum metal layer 1132 to form a titanium nitride layer 1133. Wherein the thickness of the aluminum metal layer 1132 is much greater than the thickness of the high dielectric constant material layer 1131 and the titanium nitride layer 1133. Then, photoresist is spin-coated on the titanium nitride layer 1133 to form a photoresist layer. Then, the photoresist layer is processed by exposure and development to form a patterned photoresist layer. And etching the titanium nitride layer 1133, the aluminum metal layer 1132 and the high dielectric constant material layer 1131 by using the patterned photoresist layer as a mask to form the grating 113. The high dielectric constant material layer 1131 in the grid 113 can better isolate adjacent photoelectric sensing areas, the aluminum metal layer 1132 can play a better role in shading, and the titanium nitride layer 1133 not only has higher stability, but also has high reflectivity and anti-reflection performance, can reflect incident light at the grid 113, and enables the grid 113 to be more stable. The formed grid 113 has a light shielding effect and can reduce the generation of dark current.
Referring to fig. 15, in an embodiment of the present invention, symmetry axes of the grating 113 and the deep trench isolation structure 112 in the growth direction are located on the same line.
Referring to fig. 16, in an embodiment of the invention, after forming the grids 113, a filter is formed between adjacent grids 113, and the filter is located on the photo-sensing region. In the present embodiment, the Filter is a Color Filter 114 (CF). The color filters 114 respectively filter monochromatic light of different spectrums, for example, red light, orange light, yellow light, green light, blue light and purple light. The photo sensing region, the deep trench isolation structure 112, the grating 113 and the color filter 114 form a pixel unit. After the incident light is focused and screened by the optical filter, the light with the set wavelength passes through the optical filter and reaches the photoelectric sensing area. Wherein the grating 113 and the deep trench isolation structure 112 can avoid mutual crosstalk of optical signals of different channels. The photoelectric sensing area receives the light signal energy of the incident light ray to form photo-generated current. The invention omits electrical connection structures such as pads, plugs, through silicon vias, and the like. The photo-generated current is transmitted to the logic control region through the electrical connection structure. Various image processing results are formed through the processing of the logic control region.
In summary, the image sensor provided by the present invention includes a substrate having a first surface and a second surface opposite to the first surface. In the substrate, shallow trench isolation structures are provided that extend from the second surface into the substrate. An etch stop layer and a metal layer interconnect layer are also disposed on the second surface of the substrate. On the first surface side of the substrate, a bottom isolation layer is provided. On the bottom spacer layer, a plurality of material layers are provided. In the material layer, a deep trench isolation structure is provided, which isolates the material layer into various types of photoelectric sensing regions. On the deep trench isolation structure, a grating is also provided. The photoelectric sensing area is arranged on the top isolation layer, is positioned between adjacent grids and is also provided with a color filter.
In summary, the image sensor and the manufacturing method thereof provided by the present application have the unexpected effect that the multi-layer material layer is used to form the photo-sensing region, so as to increase the electron concentration in the photo-sensing region, and further increase the strength of the generated electrical signal. Meanwhile, the material layer is formed in a layer-by-layer growth mode, so that electron holes are not easy to generate in the formed photoelectric sensing areas, and crosstalk generated between adjacent photoelectric sensing areas and between the photoelectric sensing areas and other structural layers is improved. In addition, by forming different types of photoelectric sensing areas, the application can generate electric signals with different intensities for the same optical signal, thereby meeting the requirements of some image sensors for forming electric signals with different intensities. In addition, the grid formed in the application comprises a high dielectric constant material layer, an aluminum metal layer and a titanium nitride layer, so that not only can the adjacent photoelectric sensing areas be well isolated, but also the light shielding effect can be well achieved, and the generation of dark current can be reduced.
The embodiments of the invention disclosed above are intended only to help illustrate the invention. The examples are not intended to be exhaustive or to limit the invention to the precise forms disclosed. Obviously, many modifications and variations are possible in light of the above teaching. The embodiments were chosen and described in order to best explain the principles of the invention and the practical application, to thereby enable others skilled in the art to best understand and utilize the invention. The invention is limited only by the claims and the full scope and equivalents thereof.
Claims (7)
1. An image sensor, comprising at least:
A substrate;
The bottom isolation layer is arranged in the substrate and is attached to one surface of the substrate;
The multi-layer material layers are arranged on the bottom isolation layer, and two adjacent material layers are overlapped in the growth direction of the material layers;
the deep groove isolation structure is arranged in the material layer and isolates the material layer into a plurality of types of photoelectric sensing areas;
a grating disposed on the deep trench isolation structure, and
The color filter is arranged on the photoelectric sensing area;
wherein the multi-layer material layer comprises:
A first material layer disposed on the bottom isolation layer, and having a first recess disposed therein, the first recess exposing the bottom isolation layer;
A second material layer disposed on the first material layer and covering the first material layer and the first groove, a second groove formed in the second material layer and located on the first groove, and
And the third material layer is arranged on the second material layer and covers the second material layer.
2. The image sensor of claim 1, wherein the plurality of types of photo-sensing regions comprise a first type of photo-sensing region comprising the first material layer, the second material layer, and the third material layer, and wherein the second material layer is located on the first material layer and the third material layer is located on the second material layer.
3. The image sensor of claim 1, wherein the plurality of types of photo-sensing regions comprise a second type of photo-sensing region comprising the first material layer, the second material layer, and the third material layer, and wherein a portion of the second material layer is located on the first material layer, a portion of the second material layer is located in the first recess, and wherein the third material layer is located on the second material layer, and wherein the third material layer fills the second recess.
4. The image sensor of claim 1, wherein the plurality of types of photo-sensing regions comprise a third type of photo-sensing region comprising the second material layer and the third material layer, the second material layer being on the bottom isolation layer, the third material layer being on the second material layer.
5. The image sensor of claim 1, wherein the image sensor comprises a top spacer layer, the top spacer layer being located on the photo-sensing region surface.
6. The image sensor of claim 1, wherein the grid comprises a high dielectric constant material layer on the deep trench isolation structure, an aluminum metal layer on the high dielectric constant material layer, and a titanium nitride layer on the aluminum metal layer.
7. A method for manufacturing an image sensor, comprising the steps of:
A substrate is provided and a substrate is provided,
Forming a bottom isolation layer in the substrate, wherein the bottom isolation layer is attached to one surface of the substrate;
Forming a plurality of material layers on the bottom isolation layer, wherein two adjacent material layers are overlapped in the growth direction of the material layers;
forming a deep trench isolation structure in the material layer, wherein the deep trench isolation structure isolates the material layer into a plurality of types of photoelectric sensing areas;
Forming a grating on the deep trench isolation structure, and
Forming a color filter on the photo-sensing region, and
The formation of the plurality of types of photo-sensing regions includes the steps of:
forming a first material layer on the bottom isolation layer, and forming a first groove in the first material layer;
forming a second material layer on the first material layer, wherein the second material layer covers the first material layer, and a second groove is formed in the second material layer;
Forming a third material layer on the second material layer;
forming a top isolation layer and a hard mask layer on the third material layer;
Patterning the hard mask layer and etching the top isolation layer, the third material layer, the second material layer, the first material layer and a portion of the bottom isolation layer not covered by the hard mask layer to form a deep trench, and
And depositing a medium in the deep groove to form a deep groove isolation structure, wherein the deep groove isolation structure isolates the first material layer, the second material layer and the third material layer into a plurality of types of photoelectric sensing areas.
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