CN115000113B - Backside illuminated image sensor and manufacturing method thereof - Google Patents
Backside illuminated image sensor and manufacturing method thereof Download PDFInfo
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- CN115000113B CN115000113B CN202210745442.3A CN202210745442A CN115000113B CN 115000113 B CN115000113 B CN 115000113B CN 202210745442 A CN202210745442 A CN 202210745442A CN 115000113 B CN115000113 B CN 115000113B
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- 238000004519 manufacturing process Methods 0.000 title claims abstract description 27
- 229910052751 metal Inorganic materials 0.000 claims abstract description 148
- 239000002184 metal Substances 0.000 claims abstract description 148
- 238000002955 isolation Methods 0.000 claims abstract description 90
- 239000010410 layer Substances 0.000 claims description 288
- 229920002120 photoresistant polymer Polymers 0.000 claims description 91
- 239000007769 metal material Substances 0.000 claims description 79
- 239000000758 substrate Substances 0.000 claims description 63
- 238000005530 etching Methods 0.000 claims description 29
- 239000000463 material Substances 0.000 claims description 22
- 238000000034 method Methods 0.000 claims description 19
- 239000011241 protective layer Substances 0.000 claims description 17
- 238000000059 patterning Methods 0.000 claims description 11
- WFKWXMTUELFFGS-UHFFFAOYSA-N tungsten Chemical compound [W] WFKWXMTUELFFGS-UHFFFAOYSA-N 0.000 claims description 8
- 229910052721 tungsten Inorganic materials 0.000 claims description 8
- 239000010937 tungsten Substances 0.000 claims description 8
- 229910052782 aluminium Inorganic materials 0.000 claims description 7
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 claims description 7
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 claims description 6
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 claims description 6
- 229910052710 silicon Inorganic materials 0.000 claims description 6
- 239000010703 silicon Substances 0.000 claims description 6
- 229910052814 silicon oxide Inorganic materials 0.000 claims description 6
- 229910052581 Si3N4 Inorganic materials 0.000 claims description 3
- HQVNEWCFYHHQES-UHFFFAOYSA-N silicon nitride Chemical compound N12[Si]34N5[Si]62N3[Si]51N64 HQVNEWCFYHHQES-UHFFFAOYSA-N 0.000 claims description 3
- 230000000903 blocking effect Effects 0.000 abstract description 9
- 230000003287 optical effect Effects 0.000 abstract description 8
- 238000005229 chemical vapour deposition Methods 0.000 description 4
- 238000005240 physical vapour deposition Methods 0.000 description 4
- JBRZTFJDHDCESZ-UHFFFAOYSA-N AsGa Chemical compound [As]#[Ga] JBRZTFJDHDCESZ-UHFFFAOYSA-N 0.000 description 2
- 229910001218 Gallium arsenide Inorganic materials 0.000 description 2
- 238000000231 atomic layer deposition Methods 0.000 description 2
- 229910052732 germanium Inorganic materials 0.000 description 2
- GNPVGFCGXDBREM-UHFFFAOYSA-N germanium atom Chemical compound [Ge] GNPVGFCGXDBREM-UHFFFAOYSA-N 0.000 description 2
- 239000012212 insulator Substances 0.000 description 2
- 229910000530 Gallium indium arsenide Inorganic materials 0.000 description 1
- KXNLCSXBJCPWGL-UHFFFAOYSA-N [Ga].[As].[In] Chemical compound [Ga].[As].[In] KXNLCSXBJCPWGL-UHFFFAOYSA-N 0.000 description 1
- 230000004075 alteration Effects 0.000 description 1
- 230000000295 complement effect Effects 0.000 description 1
- 150000001875 compounds Chemical class 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 238000007772 electroless plating Methods 0.000 description 1
- 238000009713 electroplating Methods 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 229910000449 hafnium oxide Inorganic materials 0.000 description 1
- WIHZLLGSGQNAGK-UHFFFAOYSA-N hafnium(4+);oxygen(2-) Chemical compound [O-2].[O-2].[Hf+4] WIHZLLGSGQNAGK-UHFFFAOYSA-N 0.000 description 1
- 229910044991 metal oxide Inorganic materials 0.000 description 1
- 150000004706 metal oxides Chemical class 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
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- 238000007254 oxidation reaction Methods 0.000 description 1
- TWNQGVIAIRXVLR-UHFFFAOYSA-N oxo(oxoalumanyloxy)alumane Chemical compound O=[Al]O[Al]=O TWNQGVIAIRXVLR-UHFFFAOYSA-N 0.000 description 1
- BPUBBGLMJRNUCC-UHFFFAOYSA-N oxygen(2-);tantalum(5+) Chemical compound [O-2].[O-2].[O-2].[O-2].[O-2].[Ta+5].[Ta+5] BPUBBGLMJRNUCC-UHFFFAOYSA-N 0.000 description 1
- 239000004065 semiconductor Substances 0.000 description 1
- HBMJWWWQQXIZIP-UHFFFAOYSA-N silicon carbide Chemical compound [Si+]#[C-] HBMJWWWQQXIZIP-UHFFFAOYSA-N 0.000 description 1
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- 239000002356 single layer Substances 0.000 description 1
- 229910001936 tantalum oxide Inorganic materials 0.000 description 1
Classifications
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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
- H01L27/14636—Interconnect structures
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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
- H01L27/1463—Pixel isolation structures
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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
- H01L27/1464—Back illuminated imager structures
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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
- H01L27/14683—Processes or apparatus peculiar to the manufacture or treatment of these devices or parts thereof
Abstract
The invention provides a back-illuminated image sensor and a manufacturing method thereof, which improve the light blocking performance of a metal grating by forming a connected structure of a deep trench isolation structure and the metal grating, further improve the optical crosstalk problem of the back-illuminated image sensor and improve the performance of the back-illuminated image sensor. Meanwhile, the metal grating is connected with the metal pad through the grating pad connecting layer, the connected metal pad can be freely selected, can be grounded, and can be connected with potential, so that potential adjustment can be carried out on the metal grating, and the performance of the back-illuminated image sensor is further improved.
Description
Technical Field
The invention relates to the technical field of integrated circuits, in particular to a back-illuminated image sensor and a manufacturing method thereof.
Background
There is some degree of electronic and optical crosstalk between pixels of CMOS (Complementary Metal Oxide Semiconductor ) image sensors. The electronic crosstalk is caused by electrons diffusing or drifting to other pixels, and the optical crosstalk is mainly caused by light incident on adjacent pixels. For optical crosstalk, the prior art backside illuminated image sensor technology is generally improved by using a deepened isolation trench and a metal grid.
In the existing backside illuminated image sensor, after tungsten is filled in a deep isolation trench to form a deep trench isolation structure, an oxide layer is deposited to cover the deep trench isolation structure, and then an aluminum layer is deposited to etch to form a metal grid.
Disclosure of Invention
The invention aims to provide a back-illuminated image sensor and a manufacturing method thereof, which improve the light blocking performance of a metal grating, further improve the optical crosstalk problem of the back-illuminated image sensor and improve the performance of the back-illuminated image sensor.
In order to solve the technical problems, the invention provides a manufacturing method of a backside illuminated image sensor, comprising the following steps:
providing a substrate, wherein the substrate comprises a pixel area and a non-pixel area, and a plurality of pixel electrodes positioned in the pixel area and a plurality of metal interconnection layers positioned in the non-pixel area are formed in the substrate;
Forming a plurality of deep isolation trenches in a pixel region of the substrate, and forming a plurality of first openings in a non-pixel region of the substrate, the deep isolation trenches being located above the pixel electrode, the first openings being located above the metal interconnection layer;
Forming a second opening at the bottom of the first opening, wherein the second opening exposes a part of the metal interconnection layer;
Sequentially forming a first metal material layer and a second metal material layer, wherein the first metal material layer fills the deep isolation groove and the second opening, fills the side wall and the bottom of the first opening and covers the substrate, and the second metal material layer covers the first metal material layer;
Etching the second metal material layer, and forming a metal bonding pad in the first opening; and
Etching the first metal material layer, forming a deep trench isolation structure and a metal grating which is positioned above the deep trench isolation structure and connected with the deep trench isolation structure in the pixel region, reserving the first metal material layer in the non-pixel region as a grating pad connecting layer, connecting the metal grating close to the non-pixel region with the metal pad through the grating pad connecting layer, and connecting the metal pad with the metal interconnection layer through the grating pad connecting layer.
Optionally, forming a plurality of deep isolation trenches in a pixel region of the substrate, and forming a plurality of first openings in a non-pixel region of the substrate includes:
Forming a first photoresist layer on the substrate, and patterning the first photoresist layer to form a patterned first photoresist layer;
Etching part of the substrate by taking the patterned first photoresist layer as a mask, and forming a plurality of first openings in the non-pixel area, wherein each first opening is positioned above each metal interconnection layer;
Removing the patterned first photoresist layer;
Forming a second photoresist layer, wherein the second photoresist layer covers the substrate and fills the first opening; patterning the second photoresist layer to form a patterned second photoresist layer;
etching part of the substrate by taking the patterned second photoresist layer as a mask, and forming a plurality of deep isolation trenches in the pixel region, wherein each deep isolation trench is positioned above each pixel electrode; and
And removing the patterned second photoresist layer.
Optionally, after forming the first opening and the deep isolation trench, before forming the second opening, the manufacturing method further includes:
forming a dielectric layer which covers the first opening and the side wall and the bottom of the deep isolation trench and covers the substrate; and
A protective layer is formed on the dielectric layer, the protective layer covering sidewalls and bottoms of the first opening and the deep isolation trench.
Optionally, the method for forming the metal pad in the first opening by etching the second metal material layer includes:
Forming a third photoresist layer on the second metal material layer, and patterning the third photoresist layer to form a patterned third photoresist layer, wherein the patterned third photoresist layer exposes a part of the second metal material layer in the first opening; and
And etching the second metal material layer by taking the patterned third photoresist layer as a mask to form the metal bonding pad, wherein a space is reserved between the side wall of the metal bonding pad and the first metal material layer on the side wall of the first opening.
Optionally, after etching the second metal material layer, before etching the first metal material layer, the method further includes:
And forming a hard mask layer, wherein the hard mask layer covers the first metal material layer and the metal bonding pad.
Optionally, the method of forming the deep trench isolation structure and the metal grid comprises:
Forming a fourth photoresist layer on the hard mask layer, and patterning the fourth photoresist layer to form a patterned fourth photoresist layer, wherein the patterned fourth photoresist layer exposes areas between adjacent shallow isolation trenches;
Etching the hard mask layer by taking the patterned fourth photoresist layer as a mask to form a patterned hard mask layer;
Removing the patterned fourth photoresist layer; and
And etching the first metal material layer by taking the patterned hard mask layer as a mask until the protective layer is exposed, so as to form a deep trench isolation structure and a metal grid which is positioned above the deep trench isolation structure and connected with the deep trench isolation structure in the pixel region.
Optionally, after forming the deep trench isolation structure and the metal grid, the method further comprises:
forming a fifth photoresist layer, wherein the fifth photoresist layer covers the patterned hard mask layer and the exposed protective layer;
patterning the fifth photoresist layer to form a patterned fifth photoresist layer, wherein the patterned fifth photoresist layer exposes a region where the metal pad is located;
etching the patterned hard mask layer by taking the patterned fifth photoresist layer as a mask so as to expose the metal bonding pad; and
And removing the patterned fifth photoresist layer.
Optionally, the material of the first metal material layer includes tungsten, the material of the second metal material layer includes aluminum, the material of the dielectric layer includes a high dielectric constant material, the material of the protective layer includes silicon oxide, and the material of the hard mask layer includes silicon oxide, silicon nitride, silicon oxynitride, or a combination thereof.
Optionally, after forming the deep isolation trench structure, the metal grid, and the grid pad connection layer, the manufacturing method further includes: and forming a color filter film in the pixel area, wherein the color filter film is positioned between the metal grids and covers the metal grids.
Correspondingly, the invention also provides a back-illuminated image sensor which is manufactured by adopting the manufacturing method of the back-illuminated image sensor.
According to the back-illuminated image sensor and the manufacturing method thereof, the integrated structure that the deep groove isolation structure is connected with the metal grating is formed, so that the light blocking performance of the metal grating is improved, the optical crosstalk problem of the back-illuminated image sensor is further improved, and the performance of the back-illuminated image sensor is improved. Meanwhile, the metal grating is connected with the metal pad through the grating pad connecting layer, the connected metal pad can be freely selected, can be grounded, and can be connected with potential, so that potential adjustment can be carried out on the metal grating, and the performance of the back-illuminated image sensor is further improved.
Further, tungsten is adopted as the metal grid, and compared with aluminum adopted as the metal grid in the prior art, the light blocking performance of the metal grid is further improved, so that the performance of the back-illuminated image sensor is further improved.
Drawings
It will be appreciated by those skilled in the art that the drawings are provided for a better understanding of the invention and do not constitute any limitation on the scope of the invention.
Fig. 1 is a flowchart of a method for manufacturing a backside illuminated image sensor according to an embodiment of the present invention.
Fig. 2 to 11 are schematic structural diagrams illustrating steps of a method for manufacturing a backside illuminated image sensor according to an embodiment of the invention.
Fig. 12 is a top view of a backside illuminated image sensor according to an embodiment of the present invention.
Reference numerals:
100-a substrate; 101-pixel electrodes; 102-a metal interconnect layer; 103—a first opening; 104-deep isolation trenches; 105-a dielectric layer; 106-a protective layer; 107-a second opening; 108-a first metal material layer; 109-a layer of a second metal material; 110-metal pads; 111-a hard mask layer; 112-deep trench isolation structures; 113-a metal grid; 114-a patterned hard mask layer; 115-a third opening; 116-a grid pad connection layer; 117-colour filters.
Detailed Description
The invention will be described in further detail with reference to the drawings and the specific embodiments thereof in order to make the objects, advantages and features of the invention more apparent. It should be noted that the drawings are in a very simplified form and are not drawn to scale, merely for convenience and clarity in aiding in the description of embodiments of the invention. Furthermore, the structures shown in the drawings are often part of actual structures. In particular, the drawings are shown with different emphasis instead being placed upon illustrating the various embodiments.
As used in this disclosure, the singular forms "a," "an," and "the" include plural referents, the term "or" are generally used in the sense of comprising "and/or" and the term "several" are generally used in the sense of comprising "at least one," the term "at least two" are generally used in the sense of comprising "two or more," and the term "first," "second," and "third" are used for descriptive purposes only and are not to be construed as indicating or implying any relative importance or number of features indicated. Thus, a feature defining "a first", "a second", and "a third" may include one or at least two of the feature, either explicitly or implicitly, unless the context clearly dictates otherwise.
Fig. 1 is a flowchart of a method for manufacturing a backside illuminated image sensor according to an embodiment of the present invention.
As shown in fig. 1, the method for manufacturing the back-illuminated image sensor includes the following steps:
S1: providing a substrate, wherein the substrate comprises a pixel area and a non-pixel area, and a plurality of pixel electrodes positioned in the pixel area and a plurality of metal interconnection layers positioned in the non-pixel area are formed in the substrate;
S2: forming a plurality of deep isolation trenches in a pixel region of the substrate, and forming a plurality of first openings in a non-pixel region of the substrate, the deep isolation trenches being located above the pixel electrode, the first openings being located above the metal interconnection layer;
S3: forming a second opening at the bottom of the first opening, wherein the second opening exposes a part of the metal interconnection layer;
S4: sequentially forming a first metal material layer and a second metal material layer, wherein the first metal material layer fills the deep isolation groove and the second opening, fills the side wall and the bottom of the first opening and covers the substrate, and the second metal material layer covers the first metal material layer;
s5: etching the second metal material layer, and forming a metal bonding pad in the first opening;
S6: etching the first metal material layer, forming a deep trench isolation structure and a metal grating which is positioned on the deep trench isolation structure and connected with the deep trench isolation structure in the pixel region, reserving the first metal material layer of the non-pixel region as a grating pad connecting layer, connecting the metal grating close to the non-pixel region with the metal pad through the grating pad connecting layer, and connecting the metal pad with the metal interconnection layer through the grating pad connecting layer.
Fig. 2 to 11 are schematic views illustrating steps of a method for manufacturing a backside-illuminated image sensor according to an embodiment of the present invention, and fig. 12 is a top view of the backside-illuminated image sensor according to an embodiment of the present invention. Next, a method for manufacturing a backside-illuminated image sensor according to an embodiment of the present invention will be described in detail with reference to fig. 1 and fig. 2 to 12.
In step S1, referring to fig. 2, a substrate 100 is provided, wherein the substrate 100 includes a pixel region a and a non-pixel region B, and a plurality of pixel electrodes 101 located in the pixel region a and a plurality of metal interconnection layers 102 located in the non-pixel region B are formed in the substrate 100.
The material of the substrate 100 may be silicon, germanium, silicon carbide, gallium arsenide, indium gallium arsenide, or the like, or may be silicon on insulator, germanium on insulator; or may be other materials such as III-V compounds such as gallium arsenide. In this embodiment, the material of the substrate 100 is preferably silicon.
The substrate 100 includes a pixel region a and a non-pixel region B surrounding the pixel region a (see fig. 12). A plurality of pixel electrodes 101 and a plurality of metal interconnect layers 102 are formed in the substrate 100, the pixel electrodes 101 are located in the pixel region a, the metal interconnect layers 102 are located in the non-pixel region B, and only one of the metal interconnect layers 102 is shown in fig. 2 to 11. The pixel electrode 101 and the metal interconnection layer 102 may be formed by a manufacturing method known to those skilled in the art, which is not described in detail in the present invention.
In step S2, referring to fig. 3, a plurality of deep isolation trenches 104 are formed in the pixel region a of the substrate 100, a plurality of first openings 103 are formed in the non-pixel region B of the substrate 100, the deep isolation trenches 104 are located above the pixel electrodes 101, and the first openings 103 are located above the metal interconnection layer 102.
Specifically, first, a plurality of first openings 103 are formed in the non-pixel region B of the substrate 100. Referring to fig. 2, the first opening 103 is formed in the non-pixel region B of the substrate 100. Illustratively, first, a first photoresist layer (not shown) is formed on the substrate 100, the first photoresist layer is patterned, for example, the first photoresist layer is exposed and developed, a patterned first photoresist layer is formed, and the patterned first photoresist layer exposes a region where the first opening 103 is predetermined to be formed. Next, a portion of the substrate 100 is etched using the patterned first photoresist layer as a mask, and a plurality of first openings 103 are formed in the non-pixel region B, where each of the first openings 103 is located above each of the metal interconnection layers 102, that is, the first openings 103 are in one-to-one correspondence with the metal interconnection layers 102. Finally, the patterned first photoresist layer is removed.
A plurality of deep isolation trenches 104 are then formed within the pixel region a of the substrate 100. Referring to fig. 3, first, a second photoresist layer (not shown) is formed, the second photoresist layer covers the substrate 100 and fills the first opening 103, the second photoresist layer is patterned, for example, the second photoresist layer is exposed and developed to form a patterned second photoresist layer, and the patterned second photoresist layer exposes a region where the deep isolation trench 104 is predetermined to be formed. Next, etching a portion of the substrate 100 with the patterned second photoresist layer as a mask, and forming a plurality of deep isolation trenches 104 in the pixel region a, wherein each deep isolation trench 104 is located above each pixel electrode 101, that is, the deep isolation trenches 104 are in one-to-one correspondence with the pixel electrodes 101. Finally, the patterned second photoresist layer is removed.
In this embodiment, the first opening 103 is formed first, and then the deep isolation trench 104 is formed. In other embodiments, the deep isolation trench 104 may be formed first and then the first opening 103 may be formed, or the first opening 103 and the deep isolation trench 104 may be formed in other manners, which is not limited in the present invention.
Next, referring to fig. 4, a dielectric layer 105 is formed, and the dielectric layer 105 covers the sidewalls and bottom of the first opening 103 and the deep isolation trench 104, and covers the substrate 100. In this embodiment, the material of the dielectric layer 105 includes a high dielectric constant material, such as hafnium oxide, aluminum oxide or tantalum oxide, and the dielectric layer 105 may be formed by Chemical Vapor Deposition (CVD), physical Vapor Deposition (PVD), atomic Layer Deposition (ALD), thermal oxidation, electroplating, electroless plating, or a combination thereof.
A protective layer 106 is then formed on the dielectric layer 105, the protective layer 106 covering the dielectric layer 105, and the protective layer 106 covering only the sidewalls and bottom of the first opening 103 and the isolation trench 104. In this embodiment, the material of the protection layer 106 includes silicon oxide, and chemical vapor deposition, physical vapor deposition, and other methods may be used to form the protection layer 106.
In step S3, as shown in fig. 5, a second opening 107 is formed at the bottom of the first opening 103, and a portion of the metal interconnection layer 102 is exposed by the second opening 107.
Specifically, a mask layer (e.g., a photoresist layer) may be formed on the protective layer 106, and the mask layer may be patterned to expose a region of the protective layer 106 where the second opening is to be formed. Next, the patterned mask layer is used as a mask to etch the protection layer 106, the dielectric layer 105 and the substrate 100 in sequence until the metal interconnection layer 102 is exposed. And finally, removing the patterned mask layer.
The second opening 107 is located at the bottom of the first opening 103, and the cross-sectional width of the second opening 107 is much smaller than the cross-sectional width of the first opening 103.
In step S4, referring to fig. 6, a first metal material layer 108 and a second metal material layer 109 are formed, the first metal material layer 108 fills the deep isolation trench 104 and the second opening 107, fills the sidewall and the bottom of the first opening 103, and covers the substrate 100, and the second metal material layer 109 covers the first metal material layer 108.
The material of the first metal material layer 108 includes tungsten, the material of the second metal material layer 109 includes aluminum, and the first metal material layer 108 and the second metal material layer 109 may be formed by chemical vapor deposition, physical vapor deposition, or the like.
In step S5, referring to fig. 7, the second metal material layer 109 is etched, and a metal pad 110 is formed in the first opening 103.
Specifically, a third photoresist layer (not shown) is formed on the second metal material layer 109, and the third photoresist layer is patterned to form a patterned third photoresist layer, where the patterned third photoresist layer exposes a portion of the second metal layer in the first opening 103. Next, the patterned third photoresist layer is used as a mask to etch the second metal material layer 109 to form the metal pad 110, where a space is formed between the sidewall of the metal pad 110 and the first metal material layer 108 on the sidewall of the first opening 103, that is, only the bottom of the metal pad 110 is connected to the first metal material layer 108.
Next, referring to fig. 8, a hard mask layer 111 is formed, the hard mask layer 111 covers the first metal material layer 108 and the metal pad 110, and the hard mask layer 111 also fills the gap between the sidewall of the metal pad 110 and the first metal material layer 108. In this embodiment, the material of the hard mask layer 111 includes silicon oxide, silicon nitride, silicon oxynitride or a combination thereof, and the hard mask layer 111 may be a single layer or multiple layers.
In step S6, referring to fig. 11, the first metal material layer 108 is etched, a deep trench isolation structure 112 and a metal grid 113 located above the deep trench isolation structure 112 and connected to the deep trench isolation structure 112 are formed in the pixel region a, the first metal material layer 108 of the non-pixel region B is reserved as a grid pad connection layer 116, the metal grid 113 adjacent to the non-pixel region B is connected to the metal pad 110 through the grid pad connection layer 116, and the metal pad 110 is connected to the metal interconnection layer 102 through the grid pad connection layer 116.
Specifically, first, referring to fig. 9, a fourth photoresist layer (not shown) is formed on the hard mask layer 111, and the fourth photoresist layer is patterned to form a patterned photoresist layer, wherein the patterned fourth photoresist layer exposes a region between adjacent shallow isolation trenches 104; etching the hard mask layer 110 with the patterned fourth photoresist layer as a mask to form a patterned hard mask layer 114; then, removing the patterned fourth photoresist layer; then, the patterned hard mask layer 114 is used as a mask to etch the first metal material layer 108 until the protection layer 106 is exposed, so as to form a deep trench isolation structure 112 and a metal grid 113 located above the deep trench isolation structure 112 and connected to the deep trench isolation structure 112 in the pixel region a.
Next, referring to fig. 10, a fifth photoresist layer (not shown) is formed, and covers the patterned hard mask layer 114 and the exposed protective layer 106; patterning the fifth photoresist layer to form a patterned fifth photoresist layer, wherein the patterned fifth photoresist layer exposes a region where the metal pad 110 is located; etching the patterned hard mask layer 114 to form a third opening 115 by using the patterned fifth photoresist layer as a mask, wherein the third opening 115 exposes the metal pad 110; and finally, removing the patterned fifth photoresist layer.
The first metal material layer 108 fills the deep isolation trench 104 and covers the deep isolation trench 104, forming a deep trench isolation structure 112 and a metal grid 113 located above the deep trench isolation structure 112 and connected to the deep trench isolation structure 112. The invention forms an integrated structure that the deep trench isolation structure 112 is connected with the metal grating 113, improves the light blocking performance of the metal grating 113, further improves the optical crosstalk problem of the back-illuminated image sensor, and improves the performance of the back-illuminated image sensor. Further, the material of the first metal material layer 108 includes tungsten, and tungsten is used as the metal grid 113 and the deep trench isolation structure 112, so that the light blocking performance of the metal grid 113 is further improved, and the performance of the backside illuminated image sensor is further improved, compared with the prior art that aluminum is used as the metal grid.
In step S6, only a portion of the hard mask layer 111 of the pixel region B and the first metal material layer 108 and a portion of the patterned hard mask layer 114 of the non-pixel region B are etched, the first metal material layer 108 in the remaining region remains as a grating pad connection layer 116, the metal grating 113 adjacent to the non-pixel region B is connected to the metal pad 110 through the grating pad connection layer 116, and the metal pad 110 is connected to the metal interconnection layer 102 through the grating pad connection layer 116.
Next, as shown in fig. 11, a color filter 117 is formed in the pixel area a, and the color filter 117 is located between the metal grids 113 and covers the metal grids 113. The color filter 117 can effectively improve the light blocking performance of the metal grid 113, thereby further improving the performance of the back-illuminated image sensor.
Referring to fig. 12, a plurality of metal pads 110 are formed in the non-pixel region B, and the metal grid 113 may be connected to one or more of the metal pads 110 through a grid pad connection layer 116. The metal pad 110 connected to the metal grid 113 may be grounded or may be electrically connected, so that the metal grid 113 may be electrically potential-adjusted, thereby improving the performance of the back-illuminated image sensor.
In the backside illuminated image sensor and the manufacturing method thereof provided by the invention, a substrate 100 comprises a pixel area A and a non-pixel area B, and a plurality of pixel electrodes 101 positioned in the pixel area A and a plurality of metal interconnection layers 102 positioned in the non-pixel area B are formed in the substrate 100; forming a plurality of deep isolation trenches 104 in a pixel region a of the substrate 100, forming a plurality of first openings 103 in a non-pixel region B of the substrate 100, the deep isolation trenches 104 being located above the pixel electrodes 101, the first openings 103 being located above the metal interconnection layer 102; forming a second opening 107 at the bottom of the first opening 103, wherein the second opening 107 exposes a part of the metal interconnection layer 102; sequentially forming a first metal material layer 108 and a second metal material layer 109, wherein the first metal material layer 108 fills the deep isolation trench 104 and the second opening 107, fills the sidewall and the bottom of the first opening 103, and covers the substrate 100, and the second metal material layer 109 covers the first metal material layer 108; etching the second metal material layer 109 to form a metal pad 110 in the first opening 103; and etching the first metal material layer 108, forming a deep trench isolation structure 112 and a metal grid 113 positioned above the deep trench isolation structure 112 and connected with the deep trench isolation structure 112 in the pixel region B, and reserving the first metal material layer 108 in the non-pixel region B as a grid pad connecting layer 116, wherein the metal grid 113 close to the non-pixel region B is connected with the metal pad 110 through the grid pad connecting layer 116, and the metal pad 110 is connected with the metal interconnection layer 102 through the grid pad connecting layer 116.
The invention forms an integrated structure that the deep trench isolation structure 112 is connected with the metal grating 113, improves the light blocking performance of the metal grating 113, further improves the optical crosstalk problem of the back-illuminated image sensor, and improves the performance of the back-illuminated image sensor.
Meanwhile, the metal grid 113 is connected with the metal pad 110 through the grid pad connecting layer 116, the connected metal pad 110 can be freely selected, the grounded metal pad 110 can be also the potential-connected metal pad 110, and therefore potential adjustment can be carried out on the metal grid 113, and the performance of the back-illuminated image sensor is further improved.
Further, the tungsten is used as the metal grid 113, and compared with the aluminum used as the metal grid in the prior art, the light blocking performance of the metal grid 113 is further improved, so that the performance of the back-illuminated image sensor is further improved.
Correspondingly, the invention also provides a back-illuminated image sensor which is manufactured by adopting the manufacturing method of the back-illuminated image sensor. Referring to fig. 11 and 12, the back-illuminated image sensor includes:
A substrate 100, wherein the substrate 100 comprises a pixel area A and a non-pixel area B, and a plurality of pixel electrodes 101 positioned in the pixel area A and a plurality of metal interconnection layers 102 positioned in the non-pixel area B are formed in the substrate 100;
A deep trench isolation structure 112 located within the substrate 100 of the pixel region a, the deep trench isolation structure 112 being located above the pixel electrode 101;
A metal grid 113 on the substrate 100 of the pixel region a, the metal grid 113 being located above the deep trench isolation structure 112 and connected to the deep trench isolation structure 112;
A metal pad 110 located in the substrate 100 of the non-pixel region B, the metal pad 110 being located above the metal interconnection layer 102, the metal pad 110 being connected to the metal interconnection layer 102 through the grid pad connection layer 116, and the metal grid 113 adjacent to the non-pixel region B being connected to the metal pad 110 through the grid pad connection layer 116.
The above description is only illustrative of the preferred embodiments of the present invention and is not intended to limit the scope of the present invention, and any alterations and modifications made by those skilled in the art based on the above disclosure shall fall within the scope of the appended claims.
Claims (10)
1. The manufacturing method of the back-illuminated image sensor is characterized by comprising the following steps of:
providing a substrate, wherein the substrate comprises a pixel area and a non-pixel area, and a plurality of pixel electrodes positioned in the pixel area and a plurality of metal interconnection layers positioned in the non-pixel area are formed in the substrate;
Forming a plurality of deep isolation trenches in a pixel region of the substrate, and forming a plurality of first openings in a non-pixel region of the substrate, the deep isolation trenches being located above the pixel electrode, the first openings being located above the metal interconnection layer;
Forming a second opening at the bottom of the first opening, wherein the second opening exposes a part of the metal interconnection layer;
Sequentially forming a first metal material layer and a second metal material layer, wherein the first metal material layer fills the deep isolation groove and the second opening, fills the side wall and the bottom of the first opening and covers the substrate, and the second metal material layer covers the first metal material layer;
Etching the second metal material layer, and forming a metal bonding pad in the first opening; and
Etching the first metal material layer, forming a deep trench isolation structure and a metal grating which is positioned above the deep trench isolation structure and connected with the deep trench isolation structure in the pixel region, reserving the first metal material layer in the non-pixel region as a grating pad connecting layer, connecting the metal grating close to the non-pixel region with the metal pad through the grating pad connecting layer, and connecting the metal pad with the metal interconnection layer through the grating pad connecting layer.
2. The method of fabricating a backside illuminated image sensor according to claim 1, wherein the forming a plurality of deep isolation trenches in the pixel region of the substrate and a plurality of first openings in the non-pixel region of the substrate comprises:
Forming a first photoresist layer on the substrate, and patterning the first photoresist layer to form a patterned first photoresist layer;
Etching part of the substrate by taking the patterned first photoresist layer as a mask, and forming a plurality of first openings in the non-pixel area, wherein each first opening is positioned above each metal interconnection layer;
Removing the patterned first photoresist layer;
Forming a second photoresist layer, wherein the second photoresist layer covers the substrate and fills the first opening; patterning the second photoresist layer to form a patterned second photoresist layer;
etching part of the substrate by taking the patterned second photoresist layer as a mask, and forming a plurality of deep isolation trenches in the pixel region, wherein each deep isolation trench is positioned above each pixel electrode; and
And removing the patterned second photoresist layer.
3. The method of fabricating a backside illuminated image sensor according to claim 1, wherein after forming the first opening and the deep isolation trench, before forming the second opening, the method further comprises:
forming a dielectric layer which covers the first opening and the side wall and the bottom of the deep isolation trench and covers the substrate; and
A protective layer is formed on the dielectric layer, the protective layer covering sidewalls and bottoms of the first opening and the deep isolation trench.
4. The method of fabricating a backside illuminated image sensor according to claim 3, wherein the etching the second metal material layer, the method of forming a metal pad in the first opening comprises:
Forming a third photoresist layer on the second metal material layer, and patterning the third photoresist layer to form a patterned third photoresist layer, wherein the patterned third photoresist layer exposes a part of the second metal material layer in the first opening; and
And etching the second metal material layer by taking the patterned third photoresist layer as a mask to form the metal bonding pad, wherein a space is reserved between the side wall of the metal bonding pad and the first metal material layer on the side wall of the first opening.
5. The method of fabricating a backside illuminated image sensor according to claim 4, wherein after etching the second metal material layer, before etching the first metal material layer, the method further comprises:
And forming a hard mask layer, wherein the hard mask layer covers the first metal material layer and the metal bonding pad.
6. The method of fabricating a backside illuminated image sensor according to claim 5, wherein the method of forming a deep trench isolation structure and the metal grid comprises:
Forming a fourth photoresist layer on the hard mask layer, and patterning the fourth photoresist layer to form a patterned fourth photoresist layer, wherein the patterned fourth photoresist layer exposes areas between adjacent shallow isolation trenches;
Etching the hard mask layer by taking the patterned fourth photoresist layer as a mask to form a patterned hard mask layer;
Removing the patterned fourth photoresist layer; and
And etching the first metal material layer by taking the patterned hard mask layer as a mask until the protective layer is exposed, so as to form a deep trench isolation structure and a metal grid which is positioned above the deep trench isolation structure and connected with the deep trench isolation structure in the pixel region.
7. The method of claim 6, wherein after forming the deep trench isolation structure and the metal grid, the method further comprises:
forming a fifth photoresist layer, wherein the fifth photoresist layer covers the patterned hard mask layer and the exposed protective layer;
patterning the fifth photoresist layer to form a patterned fifth photoresist layer, wherein the patterned fifth photoresist layer exposes a region where the metal pad is located;
etching the patterned hard mask layer by taking the patterned fifth photoresist layer as a mask so as to expose the metal bonding pad; and
And removing the patterned fifth photoresist layer.
8. The method of claim 5, wherein the material of the first metal material layer comprises tungsten, the material of the second metal material layer comprises aluminum, the material of the dielectric layer comprises a high dielectric constant material, the material of the protective layer comprises silicon oxide, and the material of the hard mask layer comprises silicon oxide, silicon nitride, silicon oxynitride, or a combination thereof.
9. The method of manufacturing a backside illuminated image sensor of claim 1, wherein after forming the deep isolation trench structure, the metal grid, and the grid pad connection layer, the method further comprises: and forming a color filter film in the pixel area, wherein the color filter film is positioned between the metal grids and covers the metal grids.
10. A backside-illuminated image sensor manufactured by the manufacturing method of the backside-illuminated image sensor according to any one of claims 1 to 9.
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