CN108598100B - Global pixel structure for reducing light leakage of storage node and manufacturing method - Google Patents

Global pixel structure for reducing light leakage of storage node and manufacturing method Download PDF

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CN108598100B
CN108598100B CN201810622082.1A CN201810622082A CN108598100B CN 108598100 B CN108598100 B CN 108598100B CN 201810622082 A CN201810622082 A CN 201810622082A CN 108598100 B CN108598100 B CN 108598100B
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storage node
layer
contact hole
light leakage
substrate
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CN108598100A (en
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顾学强
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Shanghai Weijing Electronic Technology Co ltd
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L27/00—Devices consisting of a plurality of semiconductor or other solid-state components formed in or on a common substrate
    • H01L27/14—Devices consisting of a plurality of semiconductor or other solid-state components formed in or on a common substrate including semiconductor components sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation
    • H01L27/144—Devices controlled by radiation
    • H01L27/146—Imager structures
    • H01L27/14601—Structural or functional details thereof
    • H01L27/14609—Pixel-elements with integrated switching, control, storage or amplification elements
    • H01L27/14612—Pixel-elements with integrated switching, control, storage or amplification elements involving a transistor
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L27/00—Devices consisting of a plurality of semiconductor or other solid-state components formed in or on a common substrate
    • H01L27/14—Devices consisting of a plurality of semiconductor or other solid-state components formed in or on a common substrate including semiconductor components sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation
    • H01L27/144—Devices controlled by radiation
    • H01L27/146—Imager structures
    • H01L27/14601—Structural or functional details thereof
    • H01L27/1462—Coatings
    • H01L27/14623—Optical shielding
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L27/00—Devices consisting of a plurality of semiconductor or other solid-state components formed in or on a common substrate
    • H01L27/14—Devices consisting of a plurality of semiconductor or other solid-state components formed in or on a common substrate including semiconductor components sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation
    • H01L27/144—Devices controlled by radiation
    • H01L27/146—Imager structures
    • H01L27/14601—Structural or functional details thereof
    • H01L27/14625—Optical elements or arrangements associated with the device
    • H01L27/14629—Reflectors
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L27/00—Devices consisting of a plurality of semiconductor or other solid-state components formed in or on a common substrate
    • H01L27/14—Devices consisting of a plurality of semiconductor or other solid-state components formed in or on a common substrate including semiconductor components sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation
    • H01L27/144—Devices controlled by radiation
    • H01L27/146—Imager structures
    • H01L27/14643—Photodiode arrays; MOS imagers
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L27/00—Devices consisting of a plurality of semiconductor or other solid-state components formed in or on a common substrate
    • H01L27/14—Devices consisting of a plurality of semiconductor or other solid-state components formed in or on a common substrate including semiconductor components sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation
    • H01L27/144—Devices controlled by radiation
    • H01L27/146—Imager structures
    • H01L27/14683—Processes or apparatus peculiar to the manufacture or treatment of these devices or parts thereof
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L27/00—Devices consisting of a plurality of semiconductor or other solid-state components formed in or on a common substrate
    • H01L27/14—Devices consisting of a plurality of semiconductor or other solid-state components formed in or on a common substrate including semiconductor components sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation
    • H01L27/144—Devices controlled by radiation
    • H01L27/146—Imager structures
    • H01L27/14683—Processes or apparatus peculiar to the manufacture or treatment of these devices or parts thereof
    • H01L27/14685—Process for coatings or optical elements

Abstract

The invention discloses a global pixel structure for reducing light leakage of a storage node, which comprises a photodiode, a transmission tube, a reset tube and the storage node, wherein the photodiode, the transmission tube and the reset tube are arranged on a substrate, and the storage node is formed between the transmission tube and the reset tube and is arranged on the substrate; the storage node is provided with a storage node, a transmission pipe, a reset pipe and an insulation reflection layer, wherein the transmission pipe, the reset pipe and the storage node are covered with metal masking layers, the storage node is connected with a contact hole, the contact hole penetrates through the metal masking layers and forms a gap with the metal masking layers, the gap is filled with the insulation reflection layer, and a light leakage gap between the metal masking layers and the contact hole is filled with the insulation reflection layer, so that incident light cannot enter a charge storage area of the storage node, the light leakage problem of the storage node of the global pixel unit of the CMOS image sensor is reduced, and meanwhile, the electrical isolation between the metal masking layers and the contact hole is guaranteed. The invention also discloses a manufacturing method of the global pixel structure for reducing light leakage of the storage node.

Description

Global pixel structure for reducing light leakage of storage node and manufacturing method
Technical Field
The invention relates to the technical field of CMOS image sensors, in particular to a CMOS image sensor global pixel structure capable of reducing light leakage of a storage node and a manufacturing method thereof.
Background
An image sensor refers to a device that converts an optical signal into an electrical signal, and image sensor chips generally used in large-scale commercial applications include two major types, a Charge Coupled Device (CCD) and a Complementary Metal Oxide Semiconductor (CMOS) image sensor chip.
Compared with the traditional CCD sensor, the CMOS image sensor has the characteristics of low power consumption, low cost, compatibility with the CMOS process and the like, so that the CMOS image sensor is more and more widely applied. CMOS image sensors are now used in consumer electronics, such as digital compact cameras (DSCs), cell phone cameras, video cameras and Digital Single Lens Reflex (DSLR), but also in automotive electronics, surveillance, biotechnology and medicine.
The pixel unit of the CMOS image sensor is a core device of the image sensor for realizing light sensing, and the most commonly used pixel unit is an active pixel structure including one photodiode and four transistors. In these devices, the photodiode is a light sensing unit, which realizes collection of light and photoelectric conversion; other MOS transistors are control units, and mainly realize the control of the selection, the reset, the signal amplification and the reading of the photodiode. The number of MOS transistors in a pixel unit determines the area occupied by the non-photosensitive area. The pixel structure including four transistors described above is generally referred to as a 4T pixel cell.
In digital cameras there are generally two shutter control methods, namely mechanical shutter and electronic shutter. The mechanical shutter controls the exposure time through the opening and closing of a mechanical piece arranged in front of the CMOS image sensor; the electronic shutter changes the integration time through the time sequence control of the pixel unit, thereby achieving the purpose of controlling the exposure time. Since the mechanical shutter requires a mechanical member, it occupies the area of the digital camera, and thus is not suitable for a portable digital camera. For video surveillance applications, an electronic shutter is typically used to control the exposure time, since video acquisition is typically performed. The electronic shutter is divided into two types: namely rolling shutter and global exposure. Exposure time between each row of the rolling electronic shutter is inconsistent, and a smear phenomenon is easily caused when a high-speed object is shot; and each row of the global exposure type electronic shutter is exposed at the same time, then the charge signals are stored in the storage nodes of the pixel units at the same time, and finally the signals of the storage nodes are output row by row. The global exposure type electronic shutter does not cause the smear phenomenon because all the rows are exposed at the same time.
With the increasingly widespread use of CMOS image sensors in industry, vehicle-mounted, road surveillance, and high-speed cameras, the demand for image sensors that can capture images of moving objects at high speeds has increased further. In order to monitor a high-speed object, the CMOS image sensor needs to use a globally exposed pixel unit (referred to as a global pixel for short), and a parasitic response of a storage node for storing a charge signal in the globally exposed pixel unit to a light source is a very important index. In practical applications, there are 4T, 5T, 6T, 8T, 12T, etc. of globally exposed pixel cells, depending on the number of transistors used per pixel cell.
Referring to fig. 1, fig. 1 is a layout structure of a 5T global exposure pixel unit in the prior art. As shown in fig. 1, the charge storage node 12 in a 5T global exposure pixel cell is the junction capacitance between the transfer transistor 11 and the reset transistor 13. The parasitic light response of the storage node refers to the parasitic response of the storage node capacitance due to light leakage, for the pixel unit, the light incident on the surface of the pixel unit cannot be completely focused on the surface of the photodiode 10 due to refraction and scattering, a part of the light may be incident on the storage node 12, and the storage node 12 can also generate the photoelectric response like the photodiode 10 under the irradiation of the incident light. The charge generated on the storage node 12 due to the illumination of the incident light affects the voltage signal generated by the photodiode 10 originally stored on the storage node 12, causing signal distortion. In order to reduce the parasitic response of the storage node, a completely opaque metal shielding layer is required to prevent the influence of incident light.
Referring to fig. 2, fig. 2 is a cross-sectional view of the global pixel structure along a direction a-B in fig. 1. As shown in fig. 2, the conventional global pixel unit is provided with an additionally formed metal masking layer 17 in the interlayer dielectric 16 in order to prevent parasitic photo-response of the global pixel, as compared to the general CMOS process. The metal mask layer 17 is usually made of a metal such as tungsten, aluminum, or copper, or a metal compound material such as tantalum nitride or tantalum nitride, which is opaque. Since the metal masking layer 17 covers the transmission tube 11, the reset tube 13 and the storage node 12 in a large area, in order to avoid mutual crosstalk among the transmission tube 11, the reset tube 13 and the storage node 12 in the pixel working process, all the metal masking layers 17 are finally grounded through metal interconnection; meanwhile, the storage node 12 is connected to the metal interconnection layer 14 through the contact hole 15.
In the global pixel structure, since the storage node 12 is a dynamic signal which changes continuously during operation, the contact hole 15 and the metal mask layer 17 on the storage node 12 cannot be connected, and must be kept at a certain distance. A leakage gap 18 is thus formed on the storage node 12. There is no coverage of the metal mask layer 17 or the contact hole 15 at the position of the light leakage gap 18, so that the incident light can directly pass through the light leakage gap 18 to reach the storage node 12, causing distortion of the global picture element storage signal and degradation of image quality.
Disclosure of Invention
The invention aims to overcome the defects in the prior art and provides a global pixel structure for reducing light leakage of a storage node and a manufacturing method thereof.
In order to achieve the purpose, the technical scheme of the invention is as follows:
the invention provides a global pixel structure for reducing light leakage of a storage node, which comprises a photodiode, a transmission tube, a reset tube and the storage node, wherein the photodiode, the transmission tube and the reset tube are arranged on a substrate, and the storage node is formed between the transmission tube and the reset tube and on the substrate; the storage node is connected with a contact hole, the contact hole penetrates through the metal masking layer, a gap is formed between the contact hole and the metal masking layer, and the gap is filled with an insulating reflecting layer.
Further, the insulating reflecting layer is a composite insulating reflecting layer structure formed by stacking a plurality of layers of insulating media on each other.
Further, the refractive index between any two adjacent layers of insulating media in the composite insulating and reflecting layer is different.
Furthermore, the materials between any two adjacent layers of insulating media in the composite insulating reflecting layer are different.
Further, the metal masking layer is of a single-layer structure or a multi-layer composite structure.
The invention also provides a manufacturing method of the global pixel structure for reducing light leakage of the storage node, which comprises the following steps:
providing a substrate, forming a photodiode, a transmission tube and a reset tube on the substrate, and forming a storage node on the substrate between the transmission tube and the reset tube;
depositing a metal masking layer material on the surface of the substrate in a whole piece, removing the metal masking layer material above the photodiode, and forming a metal masking layer opening above the storage node to form a metal masking layer;
depositing an insulating reflecting layer material on the surface of the substrate in a whole piece, filling the opening of the metal masking layer, and forming an insulating reflecting layer pattern above the storage node to enable the size of the insulating reflecting layer pattern to be larger than that of the opening of the metal masking layer;
depositing interlayer dielectric on the surface of the substrate in a whole piece manner to form a contact hole pattern which penetrates through the insulating reflecting layer pattern and is connected with the storage node;
and filling the contact hole, forming the contact hole, and forming a subsequent metal interconnection layer connected with the contact hole.
Further, the substrate is an N-type or P-type silicon substrate.
Further, the metal masking layer is a single-layer structure or a multi-layer composite structure formed by one or more of titanium, titanium nitride, tungsten, aluminum, copper, cobalt and nickel.
Further, the insulating reflecting layer is a composite insulating reflecting layer structure formed by stacking at least two of silicon nitride, silicon dioxide, silicon oxynitride and nitrogen-containing silicon carbide.
Furthermore, the material or refractive index between any two adjacent layers in the composite insulating reflecting layer is different.
According to the technical scheme, the insulating reflecting layer is inserted between the metal masking layer and the contact hole of the conventional global pixel unit, so that a light leakage gap between the metal masking layer and the contact hole is filled by the insulating reflecting layer, the composite insulating reflecting layer is formed by stacking more than two insulating medium films with different materials or refractive indexes, and incident light is reflected, so that the incident light cannot enter a charge storage region of a storage node, the light leakage problem of the storage node of the global pixel unit of the CMOS image sensor is reduced, and meanwhile, the electrical isolation between the metal masking layer and the contact hole is ensured, so that the accuracy of signals in the storage capacitor of the global exposure pixel unit is effectively ensured, the distortion of output signals is avoided, and the image sensor can finally obtain high-quality images.
Drawings
FIG. 1 is a schematic diagram of a layout structure of a conventional 5T global exposure pixel unit;
FIG. 2 is a cross-sectional view of the global pixel structure along the direction A-B in FIG. 1;
FIG. 3 is a diagram illustrating a global pixel structure for reducing light leakage from a storage node according to a preferred embodiment of the present invention;
fig. 4-12 are schematic process steps of a method for manufacturing a global pixel structure with reduced light leakage from a storage node according to a preferred embodiment of the invention.
Detailed Description
The following describes embodiments of the present invention in further detail with reference to the accompanying drawings.
In the following detailed description of the embodiments of the present invention, in order to clearly illustrate the structure of the present invention and to facilitate explanation, the structure shown in the drawings is not drawn to a general scale and is partially enlarged, deformed and simplified, so that the present invention should not be construed as limited thereto.
In the following detailed description of the present invention, please refer to fig. 3, fig. 3 is a schematic diagram of a global pixel structure for reducing light leakage of a storage node according to a preferred embodiment of the present invention. As shown in fig. 3, a global pixel structure for reducing storage node light leakage according to the present invention includes a photodiode 21, a transfer transistor 23, and a reset transistor 27 disposed on a substrate 20, and a storage node 29 formed on the substrate 20 between the transfer transistor 23 and the reset transistor 27. Where charge storage node 29 is the junction capacitance between transfer tube 23 and reset tube 27. An interlayer dielectric 22 may be disposed on the substrate 20; the interlayer medium 22 covers the transfer tube 23 and the reset tube 27 therein.
Please refer to fig. 3. A metal masking layer 24 is disposed in the interlayer dielectric 22; metal masking layer 24 overlies transfer tubes 23, reset tubes 27 and storage nodes 29.
A contact hole 25 is connected to the storage node 29; contact hole 25 is disposed through metal masking layer 24 and forms a gap 30 with metal masking layer 24. This gap 30 constitutes a light leakage gap (see light leakage gap 18 in fig. 2) between metal masking layer 24 and contact hole 25 on storage node 29 in a conventional global pixel cell, and thus it is desirable to eliminate this light leakage gap 30 to prevent incident light from entering the charge storage region of storage node 29 through light leakage gap 30.
Please continue to refer to fig. 3. Since there is no electrical connection between the metal mask layer 24 and the contact hole 25 of the global pixel unit, the conventional metal layer cannot be used in the light leakage gap 30 to shield incident light. The present invention isolates incident light by filling (or inserting or embedding) the insulating reflective layer 28 in the gap 30.
The insulating reflective layer 28 may be a composite insulating reflective layer 28 structure formed by stacking a plurality of insulating dielectrics on each other. Conventional single-layer insulating media are typically transparent to light, but multiple layers of insulating dielectric films stacked on top of each other can achieve reflection of a large fraction of incident light. The reflection of the composite insulating dielectric film to incident light depends on the difference of refractive indexes between the dielectric films, the larger the difference of the refractive indexes of the two dielectric films is, the higher the reflection of the two dielectric films to the incident light is, for example, when a silicon nitride film and an oxide film are used, the larger the difference of the refractive indexes of the two dielectric films is, and the composite film formed by the two dielectric films can greatly reflect the incident light. Other insulating dielectric films such as silicon carbide, silicon oxynitride, and the like may also be used.
Therefore, the refractive index is different between any two adjacent insulating media in the composite insulating and reflecting layer 28. Alternatively, the material of any two adjacent insulating mediums in the composite insulating reflective layer 28 is different. By stacking several insulating films with different refractive indexes or different materials, incident light can be greatly reflected, and the problem of light leakage of the global pixel storage node 29 is reduced.
After the composite insulating reflective layer 28 is inserted into the light leakage gap 30 between the metal mask layer 24 and the contact hole 25 of the conventional global pixel unit, not only most of incident light is reflected in the composite insulating layer, but also the electrical isolation between the contact hole 25 and the metal mask layer 24 on the storage node 29 is ensured.
The metal masking layer 24 may be formed of an opaque metal or metal compound to form a single layer structure or a multi-layer composite structure. Metal masking layer 24 may ultimately be grounded through a metal interconnect layer. The storage node 29 may be connected to the metal interconnection layer 26 through the contact hole 25. The contact hole 25 is also filled with a metal that is opaque to light.
The structure of the invention can be used in 4T, 5T, 6T, 8T, 12T and other global pixel structures which need storage capacitance.
The following describes in detail a method for manufacturing a global pixel structure for reducing light leakage of a storage node according to the present invention with reference to the following detailed description and accompanying drawings.
Referring to fig. 4-12, fig. 4-12 are schematic process steps of a method for manufacturing a global pixel structure with reduced light leakage from a storage node according to a preferred embodiment of the invention. As shown in fig. 4 to 12, the method for manufacturing a global pixel structure with reduced light leakage from a storage node according to the present invention can be used for manufacturing the above global pixel structure with reduced light leakage from a storage node, and can include the following steps:
as shown in fig. 4, a substrate 20, which may be an N-type or P-type silicon substrate 20, for example, is first provided. Forming a photodiode 21, a transfer transistor 23, and a reset transistor 27 on an N-type or P-type silicon substrate 20 using a conventional CMOS image sensor process, and forming a storage node 29 on the substrate 20 between the transfer transistor 23 and the reset transistor 27; including gate oxide, poly gate, and sidewalls to form conventional transfer tubes 23 and reset tubes 27.
Next, as shown in FIG. 5, a metal mask layer 24' is deposited over the entire surface of the silicon substrate 20. The metal mask layer material 24' may be formed using a metal or metal compound material that is conventional in CMOS processes, including one or more of titanium, titanium nitride, tungsten, aluminum, copper, cobalt, and nickel, forming a single layer structure or a multi-layer composite structure.
The total thickness of the metal masking layer material 24' deposition may be between 10 angstroms and 10000 angstroms.
Again as shown in fig. 6, metal mask layer patterning is performed by photolithography and etching to remove metal mask layer material 24' over photodiode 21 while forming metal mask layer openings 31 over storage nodes 29.
Next, as shown in FIG. 7, a blanket deposition of insulating reflective layer material 28 'is performed on the surface of the silicon substrate 20, such as a composite insulating reflective layer material 28' deposited on the entire silicon wafer substrate 20. The composite insulating reflecting layer can be formed by stacking at least two materials of silicon nitride, silicon dioxide, silicon oxynitride, nitrogen-containing silicon carbide and the like. And the materials or refractive indexes of any two adjacent layers in the formed composite insulating reflecting layer are different. By stacking two or more insulating dielectric films having a large difference in refractive index, incident light can be efficiently reflected.
The metal mask openings 31 are filled with the deposited composite insulating reflective layer material 28'.
The composite insulating reflective layer material 28' is then patterned by photolithography and etching to form a composite insulating reflective layer 28 over the storage nodes 29, as shown in fig. 8. The size of the composite insulating reflective layer 28 pattern remaining after etching is larger than the size of the metal mask opening 31 so as to completely close the metal mask opening 31.
Then, as shown in fig. 9, an interlayer dielectric 22 is deposited on the surface of the silicon substrate 20 in a full-wafer manner, for example, silicon dioxide, a low dielectric constant dielectric, etc. can be used as the interlayer dielectric 22, so that the device structures such as the transmission tube 23, the reset tube 27, and the composite insulating reflective layer 28 are completely covered therein.
Subsequently, as shown in fig. 10, photolithography and etching of the contact hole are performed, and the composite insulating reflective layer material 28 ' under the contact hole is removed by the contact hole etching, leaving the composite insulating reflective layer material 28 ' between the contact hole 25 and the metal mask layer 24, forming a pattern of contact hole openings 25 ' through the pattern of insulating reflective layer 28 and connecting the storage nodes 29.
Finally, the conventional CMOS process is performed, as shown in fig. 11, the contact hole is filled by deposition and chemical mechanical polishing, the material for filling the contact hole can be opaque metal and metal compound such as titanium, titanium nitride and tungsten, and the contact hole 25 'is formed after the contact hole opening 25' is filled with metal or metal compound.
As can be seen in connection with fig. 3, the gap 30, which originally existed between the metal mask layer 24 and the contact hole 25, is no longer present due to the filling of the composite insulating reflective layer material 28' in the metal mask layer opening 31.
As shown in fig. 12, a metal interconnection material, such as metal copper, is deposited on the interlayer dielectric 22, and then a subsequent metal interconnection layer 26 connected to the contact hole 25 is formed by photolithography and etching, thereby forming the global pixel structure of fig. 3 that reduces light leakage of the storage node.
In summary, the insulating reflective layer is inserted between the metal masking layer and the contact hole of the conventional global pixel unit, so that the light leakage gap between the metal masking layer and the contact hole is filled by the insulating reflective layer, and the composite insulating reflective layer is formed by stacking more than two insulating dielectric films with different materials or refractive indexes to reflect incident light, so that the incident light cannot enter the charge storage region of the storage node, the light leakage problem of the storage node of the global pixel unit of the CMOS image sensor is reduced, and the electrical isolation between the metal masking layer and the contact hole is ensured, so that the accuracy of signals in the storage capacitor of the global exposure pixel unit is effectively ensured, the distortion of output signals is avoided, and the image sensor can finally obtain high-quality images.
The above description is only a preferred embodiment of the present invention, and the embodiments are not intended to limit the scope of the present invention, so that all equivalent structural changes made by using the contents of the specification and the drawings of the present invention should be included in the scope of the present invention.

Claims (10)

1. The global pixel structure is characterized by comprising a photodiode, a transmission tube and a reset tube which are arranged on a substrate, and a storage node formed between the transmission tube and the reset tube and on the substrate; the storage node is connected with a contact hole, the contact hole penetrates through the metal masking layer, a gap is formed between the contact hole and the metal masking layer, and the gap is filled with an insulating reflecting layer.
2. The global pixel structure of reducing light leakage from storage nodes of claim 1, wherein the insulating reflective layer is a composite insulating reflective layer structure formed by stacking a plurality of insulating dielectrics on top of each other.
3. The global pixel structure for reducing light leakage of a storage node according to claim 2, wherein a refractive index between any two adjacent insulating mediums in the composite insulating reflective layer is different.
4. The global pixel structure capable of reducing light leakage of the storage node according to claim 2, wherein a material between any two adjacent insulating mediums in the composite insulating reflective layer is different.
5. The global pixel structure for reducing light leakage from storage nodes of claim 1, wherein the metal masking layer is a single-layer structure or a multi-layer composite structure.
6. A manufacturing method of a global pixel structure for reducing light leakage of a storage node is characterized by comprising the following steps:
providing a substrate, forming a photodiode, a transmission tube and a reset tube on the substrate, and forming a storage node on the substrate between the transmission tube and the reset tube;
depositing a metal masking layer material on the surface of the substrate in a whole piece, removing the metal masking layer material above the photodiode, and forming a metal masking layer opening above the storage node to form a metal masking layer;
depositing an insulating reflecting layer material on the surface of the substrate in a whole piece, filling the opening of the metal masking layer, and forming an insulating reflecting layer pattern above the storage node to enable the size of the insulating reflecting layer pattern to be larger than that of the opening of the metal masking layer;
depositing interlayer dielectric on the surface of the substrate in a whole piece manner to form a contact hole pattern which penetrates through the insulating reflecting layer pattern and is connected with the storage node;
and filling the contact hole, forming the contact hole, and forming a subsequent metal interconnection layer connected with the contact hole.
7. The method of claim 6, wherein the substrate is an N-type or P-type silicon substrate.
8. The method for manufacturing the global pixel structure capable of reducing light leakage of the storage node, according to claim 6, wherein the metal masking layer is a single-layer structure or a multi-layer composite structure formed by one or more of titanium, titanium nitride, tungsten, aluminum, copper, cobalt, and nickel.
9. The method for manufacturing the global pixel structure capable of reducing light leakage of the storage node according to claim 6, wherein the insulating reflective layer is a composite insulating reflective layer structure formed by stacking at least two of silicon nitride, silicon dioxide, silicon oxynitride and nitrogen-containing silicon carbide.
10. The method of claim 9, wherein the composite insulating reflective layer has a different material or refractive index between any two adjacent layers.
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