CN109524429A - Imaging sensor and forming method thereof - Google Patents
Imaging sensor and forming method thereof Download PDFInfo
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- CN109524429A CN109524429A CN201811426907.9A CN201811426907A CN109524429A CN 109524429 A CN109524429 A CN 109524429A CN 201811426907 A CN201811426907 A CN 201811426907A CN 109524429 A CN109524429 A CN 109524429A
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- 238000003384 imaging method Methods 0.000 title claims abstract description 36
- 238000000034 method Methods 0.000 title claims abstract description 27
- 239000000758 substrate Substances 0.000 claims abstract description 94
- 239000004065 semiconductor Substances 0.000 claims abstract description 90
- 238000005530 etching Methods 0.000 claims description 39
- 239000007789 gas Substances 0.000 claims description 28
- 239000000463 material Substances 0.000 claims description 21
- NBVXSUQYWXRMNV-UHFFFAOYSA-N fluoromethane Chemical compound FC NBVXSUQYWXRMNV-UHFFFAOYSA-N 0.000 claims description 8
- 229910052751 metal Inorganic materials 0.000 claims description 7
- 239000002184 metal Substances 0.000 claims description 7
- 230000008569 process Effects 0.000 claims description 7
- 238000000992 sputter etching Methods 0.000 claims description 4
- 239000004020 conductor Substances 0.000 claims description 3
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 claims 1
- 229910052799 carbon Inorganic materials 0.000 claims 1
- 238000003682 fluorination reaction Methods 0.000 claims 1
- 230000003287 optical effect Effects 0.000 abstract description 10
- 230000011514 reflex Effects 0.000 description 5
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 description 4
- 238000010586 diagram Methods 0.000 description 4
- 230000000694 effects Effects 0.000 description 4
- 229910052710 silicon Inorganic materials 0.000 description 4
- 239000010703 silicon Substances 0.000 description 4
- WFKWXMTUELFFGS-UHFFFAOYSA-N tungsten Chemical compound [W] WFKWXMTUELFFGS-UHFFFAOYSA-N 0.000 description 4
- 229910052721 tungsten Inorganic materials 0.000 description 4
- 239000010937 tungsten Substances 0.000 description 4
- PCHJSUWPFVWCPO-UHFFFAOYSA-N gold Chemical compound [Au] PCHJSUWPFVWCPO-UHFFFAOYSA-N 0.000 description 3
- 239000010931 gold Substances 0.000 description 3
- 229910052737 gold Inorganic materials 0.000 description 3
- 150000002500 ions Chemical class 0.000 description 3
- 230000005622 photoelectricity Effects 0.000 description 3
- 230000009286 beneficial effect Effects 0.000 description 2
- 239000011248 coating agent Substances 0.000 description 2
- 238000000576 coating method Methods 0.000 description 2
- 238000009792 diffusion process Methods 0.000 description 2
- 238000005516 engineering process 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
- 238000004519 manufacturing process Methods 0.000 description 2
- 239000000203 mixture Substances 0.000 description 2
- JBRZTFJDHDCESZ-UHFFFAOYSA-N AsGa Chemical compound [As]#[Ga] JBRZTFJDHDCESZ-UHFFFAOYSA-N 0.000 description 1
- GYHNNYVSQQEPJS-UHFFFAOYSA-N Gallium Chemical compound [Ga] GYHNNYVSQQEPJS-UHFFFAOYSA-N 0.000 description 1
- 229910001218 Gallium arsenide Inorganic materials 0.000 description 1
- 229910000577 Silicon-germanium Inorganic materials 0.000 description 1
- 230000004888 barrier function Effects 0.000 description 1
- 230000005540 biological transmission Effects 0.000 description 1
- 238000006243 chemical reaction Methods 0.000 description 1
- 239000008358 core component Substances 0.000 description 1
- 230000005516 deep trap Effects 0.000 description 1
- 235000013399 edible fruits Nutrition 0.000 description 1
- 238000000407 epitaxy Methods 0.000 description 1
- 230000006870 function Effects 0.000 description 1
- 229910052733 gallium Inorganic materials 0.000 description 1
- 238000005286 illumination Methods 0.000 description 1
- 239000007943 implant Substances 0.000 description 1
- 229910052738 indium Inorganic materials 0.000 description 1
- APFVFJFRJDLVQX-UHFFFAOYSA-N indium atom Chemical compound [In] APFVFJFRJDLVQX-UHFFFAOYSA-N 0.000 description 1
- 239000004615 ingredient Substances 0.000 description 1
- 238000002347 injection Methods 0.000 description 1
- 239000007924 injection Substances 0.000 description 1
- 238000005468 ion implantation Methods 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000001028 reflection method Methods 0.000 description 1
- 229910010271 silicon carbide Inorganic materials 0.000 description 1
- HBMJWWWQQXIZIP-UHFFFAOYSA-N silicon carbide Chemical compound [Si+]#[C-] HBMJWWWQQXIZIP-UHFFFAOYSA-N 0.000 description 1
- 239000000243 solution Substances 0.000 description 1
- 229910001930 tungsten 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
- H01L27/14625—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
- H01L27/14601—Structural or functional details thereof
- H01L27/14625—Optical elements or arrangements associated with the device
-
- 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
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- Physics & Mathematics (AREA)
- Engineering & Computer Science (AREA)
- Power Engineering (AREA)
- Electromagnetism (AREA)
- Condensed Matter Physics & Semiconductors (AREA)
- General Physics & Mathematics (AREA)
- Computer Hardware Design (AREA)
- Microelectronics & Electronic Packaging (AREA)
- Solid State Image Pick-Up Elements (AREA)
Abstract
A kind of imaging sensor and forming method thereof, described image sensor includes: semiconductor substrate, has photodiode in the semiconductor substrate；Latticed metallic grid, the metallic grid include main part and base portion, and the base portion is located at the surface of the semiconductor substrate, and the main part is fixed in the base portion；Filter structure, in the opening of the metallic grid；Wherein, closer to the surface of the semiconductor substrate, the area of the cross section of the base portion is bigger, wherein the cross section is parallel to the surface of the semiconductor substrate.The present invention program can be effectively reduced the problem of optical crosstalk.
Description
Technical field
The present invention relates to technical field of manufacturing semiconductors more particularly to a kind of imaging sensor and forming method thereof.
Background technique
Imaging sensor is the core component of picture pick-up device, realizes image taking function by converting optical signals into electric signal
Energy.By taking cmos image sensor (CMOS Image Sensors, abbreviation CIS) device as an example, since it is with low-power consumption and height
The advantages of signal-to-noise ratio, therefore be widely applied in various fields.
For later illuminated (Back-side Illumination, BSI) CIS, in existing manufacturing process, first half
Logical device, pixel device and metal interconnection structure are formed in conductor substrate, then using carrying wafer and the semiconductor
Substrate front bonding, and then the back of semiconductor substrate is carried out it is thinned, semiconductor substrate the back side formed CIS it is subsequent
Technique, such as dielectric layer, latticed metallic grid (Grid) are formed at the semiconductor substrate back side of the pixel device, in institute
It states and forms filter structure (Color Filter), lens arrangement (Micro-Lens) etc. in the grid between metallic grid.
In the image sensor, it after lens arrangement captures incident light, by filter structured filter, removes irrelevant
Light forms monochromatic light, and incident photon reaches semiconductor substrate and absorbed by pixel device, generates photo-generated carrier.Due to being arrived in light
Up to before silicon substrate, being easy to happen optical crosstalk causes to influence imaging effect, it is therefore desirable to be formed on the surface of semiconductor substrate
Metallic grid is to be isolated incident light.
However in the prior art, there is interval between metallic grid and photodiode, for example, can for dielectric layer and
A part of semiconductor substrate is easy to cause light to inject adjacent photoelectricity two when light propagates to the edge of filter structure
Pole pipe generates optical crosstalk.
Summary of the invention
The technical problem to be solved by the present invention is to provide a kind of imaging sensors and forming method thereof, can be effectively reduced light
The problem of learning crosstalk.
In order to solve the above technical problems, the embodiment of the present invention provides a kind of imaging sensor, comprising: semiconductor substrate, institute
Stating has photodiode in semiconductor substrate；Latticed metallic grid, the metallic grid include main part and bottom
Seating portion, the base portion are located at the surface of the semiconductor substrate, and the main part is fixed in the base portion；
Filter structure, in the opening of the metallic grid；Wherein, closer to the surface of the semiconductor substrate, the base portion
The area for the cross section divided is bigger, wherein the cross section is parallel to the surface of the semiconductor substrate.
Optionally, the shape of the longitudinal section of the base portion is trapezoidal, and the longitudinal section is served as a contrast perpendicular to the semiconductor
The surface at bottom.
Optionally, the area of the cross section of the base portion is greater than the area of the cross section of the main part.
Optionally, the main part includes base portion and the top on the base portion, the cross section at the top
Area is less than the area of the cross section of the base portion, and further away from the surface of the semiconductor substrate, the cross section at the top
Area it is smaller.
Optionally, the shape of the longitudinal section at the top is triangle or trapezoidal, and the longitudinal section is partly led perpendicular to described
The surface of body substrate.
In order to solve the above technical problems, the embodiment of the present invention provides a kind of forming method of imaging sensor, comprising: provide
Semiconductor substrate, the semiconductor substrate is interior to have photodiode；It is formed on the surface of the semiconductor substrate latticed
Metallic grid, the metallic grid include main part and base portion, and the base portion is located at the semiconductor substrate
Surface, the main part is fixed on the base portion；Filter structure is formed in the opening of the metallic grid；Its
In, closer to the surface of the semiconductor substrate, the area of the cross section of the base portion is bigger, wherein the cross section
It is parallel to the surface of the semiconductor substrate.
Optionally, forming latticed metallic grid on the surface of the semiconductor substrate includes: to serve as a contrast in the semiconductor
The surface at bottom forms metallic grid material layer；Patterned mask layer is formed on the surface of the metallic grid material layer；With institute
It states mask layer and the first preset thickness of the metallic grid material layer is etched, to be formed using the first etching technics for exposure mask
State the main part of metallic grid；Using the mask layer as exposure mask, using the second etching technics, the metallic grid material is etched
Layer, to form the base portion of the metallic grid.
Optionally, first etching technics is plasma etch process, the etching gas of first etching technics
Including SF6And Ar；Second etching technics is plasma etch process, the etching gas packet of second etching technics
Include fluorocarbon gas, SF6And Ar；Wherein, the fluorocarbon gas is CF4、C4F8And C4F6In single gas
Body, or be CF4、C4F8And C4F6In multiple gases mixed gas.
Optionally, the main part includes base portion and the top on the base portion, in opening for the metallic grid
It is formed before filter structure in mouthful, the forming method of the imaging sensor further include: use third etching technics, etch institute
Top is stated, so that the area of the cross section at the top is less than the area of the cross section of the base portion, and is partly led further away from described
The area on the surface of body substrate, the cross section at the top is smaller.
Optionally, the third etching technics is sputter etching craft.
Compared with prior art, the technical solution of the embodiment of the present invention has the advantages that
In embodiments of the present invention, imaging sensor includes: semiconductor substrate, has photoelectricity two in the semiconductor substrate
Pole pipe；Latticed metallic grid, the metallic grid include main part and base portion, and the base portion is located at institute
The surface of semiconductor substrate is stated, the main part is fixed in the base portion；Filter structure is located at the metallic grid
Opening in；Wherein, closer to the surface of the semiconductor substrate, the area of the cross section of the base portion is bigger, wherein
The cross section is parallel to the surface of the semiconductor substrate.Using the above scheme, it is served as a contrast by being arranged closer to the semiconductor
The area on the surface at bottom, the cross section of the base portion of metallic grid is bigger, can be formed and is similar in the bottom of metallic grid
The pattern on slope, thus when light propagates to the edge of filter structure, by the reflex of the bottom ramp of metallic grid,
Filter inside configuration is reflected light back into, so that light be avoided to inject adjacent photodiode, is effectively reduced optical crosstalk
The problem of.
Further, include base portion and the top on the base portion by the way that the main part of metallic grid is arranged, and push up
The area of the cross section in portion is less than the area of the cross section of the base portion, can form the pattern similar to wedge angle at top, from
And after forming filter structure, increase the area of the cross section on filter structural top surface, help to enter more incident lights,
To help to improve picture quality.
Further, the shape of the longitudinal section at the top is triangle or trapezoidal, can expose to the metal in light
When the top of grid, there is probability to reflex to filter inside configuration by triangle or trapezoidal bevel edge, compared with the prior art middle gold
The top surface of possessive case grid is plane, when light exposes to the top surface of metallic grid, meeting nothing by the plane reflection
Method enters in filter structure, using the scheme of the embodiment of the present invention, is conducive to enter more incident lights, to facilitate into one
Step improves picture quality.
Detailed description of the invention
Fig. 1 is a kind of the schematic diagram of the section structure of imaging sensor in the prior art；
Fig. 2 is a kind of flow chart of the forming method of imaging sensor in the embodiment of the present invention；
Fig. 3 to Fig. 7 is that the corresponding device of each step cuts open in a kind of forming method of imaging sensor in the embodiment of the present invention
Face structural schematic diagram.
Specific embodiment
In existing imaging sensor, optical signal reaches lens arrangement 108 by lens module and is focused, and then leads to
It crosses after filter 106 filters and reaches independent pixel (for example including photodiode) progress photoelectric conversion.Wherein, when lens arrangement is caught
After grasping incident light, by filter structured filter, irrelevant light is removed, forms monochromatic light, incident photon reaches semiconductor lining
Bottom is absorbed by pixel device, generates photo-generated carrier.Since before light reaches silicon substrate, being easy to happen optical crosstalk leads to shadow
Ring imaging effect, it is therefore desirable to form metallic grid on the surface of semiconductor substrate incident light is isolated.
Referring to Fig.1, Fig. 1 is a kind of the schematic diagram of the section structure of imaging sensor in the prior art.
In existing imaging sensor, semiconductor substrate 100 can be provided, is formed on the surface of semiconductor substrate 100
Metallic grid 104, and then filter 106 is formed in the opening between metallic grid 104, and then on the surface of the filter 106
Form lens arrangement 108.
Wherein, logical device, pixel device and metal interconnection structure 110 are formed in the semiconductor substrate 100,
The pixel device can wrap containing photodiode 102.
Specifically, the metallic grid 104 avoids generation optical crosstalk from causing to influence imaging effect for stopping incident light
Fruit, the filter 106 can cover the top of the metallic grid 104, the top surface of the filter 106 can also with it is described
The top of metallic grid 104 flush or lower than metallic grid 104 top.
The present inventor has found that in the prior art, the longitudinal section of metallic grid 104 is often rectangle after study
(surface of the longitudinal section perpendicular to the semiconductor substrate), due to having between metallic grid 104 and photodiode 102
Interval, such as can be easy to lead when light propagates to the edge of filter 106 for a part of dielectric layer and semiconductor substrate
It causes light to inject adjacent photodiode 102, generates optical crosstalk.
The route a and route b shown referring to Fig.1 is easy to cause since metallic grid 104 is difficult to block to light
Light injects adjacent photodiode 102.
In embodiments of the present invention, imaging sensor includes: semiconductor substrate, has photoelectricity two in the semiconductor substrate
Pole pipe；Latticed metallic grid, the metallic grid include main part and base portion, and the base portion is located at institute
The surface of semiconductor substrate is stated, the main part is fixed in the base portion；Filter structure is located at the metallic grid
Opening in；Wherein, closer to the surface of the semiconductor substrate, the area of the cross section of the base portion is bigger, wherein
The cross section is parallel to the surface of the semiconductor substrate.Using the above scheme, it is served as a contrast by being arranged closer to the semiconductor
The area on the surface at bottom, the cross section of the base portion of metallic grid is bigger, can be formed and is similar in the bottom of metallic grid
The pattern on slope, thus when light propagates to the edge of filter structure, by the reflex of the bottom ramp of metallic grid,
Filter inside configuration is reflected light back into, so that light be avoided to inject adjacent photodiode, significantly reduces optics string
The problem of disturbing.
It is understandable to enable above-mentioned purpose of the invention, feature and beneficial effect to become apparent, with reference to the accompanying drawing to this
The specific embodiment of invention is described in detail.
Referring to Fig. 2, Fig. 2 is a kind of flow chart of the forming method of imaging sensor in the embodiment of the present invention.It is described to state figure
As the forming method of sensor may include step S21 to step S23:
Step S21: semiconductor substrate is provided, there is photodiode in the semiconductor substrate；
Step S22: latticed metallic grid is formed on the surface of the semiconductor substrate, the metallic grid includes master
Body portion and base portion, the base portion are located at the surface of the semiconductor substrate, and the main part is fixed on institute
State base portion, wherein closer to the surface of the semiconductor substrate, the area of the cross section of the base portion is bigger；
Step S23: filter structure is formed in the opening of the metallic grid.
Wherein, the cross section is parallel to the surface of the semiconductor substrate.
Above-mentioned each step is illustrated below with reference to Fig. 3 to Fig. 7.
Fig. 3 to Fig. 7 is that the corresponding device of each step cuts open in a kind of forming method of imaging sensor in the embodiment of the present invention
Face structural schematic diagram.
Referring to Fig. 3, semiconductor substrate 200 is provided, can have photodiode 202 in the semiconductor substrate 200, also
It could be formed with metal interconnection structure 210, metallic grid material layer 221 can be formed on the surface of the semiconductor substrate 200.
In specific implementation, the semiconductor substrate 200 can be silicon substrate or the material of the semiconductor substrate 200
Material can also be the materials appropriate applied to imaging sensor such as germanium, SiGe, silicon carbide, GaAs or gallium indium, described
Semiconductor substrate 200 can also have outside for the silicon substrate of insulator surface or the germanium substrate of insulator surface, or growth
Prolong the substrate of layer (Epitaxy layer, Epi layer).Preferably, the semiconductor substrate 200 can be half be lightly doped
Conductor substrate, and doping type is opposite with drain region.Specifically, can by the semiconductor substrate 200 carry out ion implanting,
Realize deep trap doping (Deep Well Implant).
It should be pointed out that could be formed with logical device and pixel device, the picture in the semiconductor substrate 200
Plain device can wrap containing photodiode 202.
Specifically, the photodiode 202 can generate photoproduction current-carrying in the case where being excited by extraneous light intensity
Son, i.e. electronics.The photodiode 202 can be formed by ion implantation technology, moreover, passing through the energy of control ion implanting
Amount and concentration can control the depth and injection range of ion implanting, to control the depth and thickness of photodiode 202.
The logical device may include the device of the transistors such as gate structure and source and drain doping area.It may be noted that
Be, in embodiments of the present invention, for specific logical device composition with no restriction.
The pixel device may include photodiode 202 and pixel circuit, wherein the pixel circuit can wrap
It includes to form selection transistor, reset transistor and source with the device of the various transistors appropriate such as transistor, such as can wrap
Include transmission grid (Transfer Gate, TG) and floating diffusion region (Floating Diffusion, FD).It may be noted that
Be, in embodiments of the present invention, for specific pixel circuit composition with no restriction.
It should be pointed out that in order to avoid generating damage to semiconductor substrate 200 when forming metallic grid and filter, also
It can be initially formed dielectric layer (not shown) on the surface of semiconductor substrate 200, then form metallic grid on the surface of dielectric layer
Material layer 221.
Further, the material of the metallic grid material layer 221 can be tungsten (W), also to use in prior art
When tungsten, the suitability with prior art is improved.
Referring to Fig. 4, patterned mask layer 261 is formed on the surface of the metallic grid material layer 221, with the exposure mask
Layer 261 etches the first preset thickness of the metallic grid material layer 221, using the first etching technics for exposure mask to be formed
State the main part of metallic grid.
In specific implementation, first etching technics can be plasma etch process, first etching technics
Etching gas may include SF6And Ar.It should be pointed out that the routine of metallic grid can also be used to etch using other
Etching technics, in the embodiment of the present invention with no restriction to this.
It should be pointed out that in embodiments of the present invention, since the cross-sectional area of the base portion of metallic grid is larger,
Therefore the width that the main part of metallic grid can be set is less than the width of metallic grid in the prior art.
It is understood that the width of the main part of the metallic grid should not be excessive, the otherwise cross of base portion
The area in section is excessive, influences the amount light through filter；The width of the main part of the metallic grid should not be too small, no
It then influences the light crosstalk between adjacent metal grid and increases technology difficulty.In a specific embodiment of the prior art
In, the width of the longitudinal section of the metallic grid is that then in embodiments of the present invention the metallic grid can be set in 130nm
Main part longitudinal section width be 60nm to 100nm.Preferably, the main part of the metallic grid can be set
The width of longitudinal section is 80nm.
Further, the material of the mask layer 261 can be KrF or ArF.
Preferably, KrF can be used as the mask layer 261, since KrF coating can form thicker thickness, from
And realize the etching to metallic grid material layer 221.
Preferably, can be set the KrF coating with a thickness of 520nm.
Referring to Fig. 5, it is exposure mask with the mask layer 261, using the second etching technics, etches the metallic grid material layer
221, to form the base portion of the metallic grid.
In specific implementation, second etching technics can be plasma etch process, second etching technics
Etching gas may include fluorocarbon gas, SF6And Ar.Wherein, the fluorocarbon gas can be CF4、
C4F8And C4F6In single gas, can also be CF4、C4F8And C4F6In multiple gases mixed gas.It needs to refer to
Out, the specific ingredient of the fluorocarbon gas can be not limited to above-mentioned gas.
In embodiments of the present invention, by using including fluorocarbon gas, SF6And the gas including Ar forms gold
The base portion of possessive case grid can form the pattern similar to slope in the bottom of metallic grid, to propagate to filter in light
When the edge of mirror structure, by the reflex of the bottom ramp of metallic grid, filter inside configuration is reflected light back into, thus
The problem of avoiding light from injecting adjacent photodiode, significantly reducing optical crosstalk.
Further, by adjusting the flow of fluorocarbon gas, ratio, various sizes of base portion can be formed
Point, meet the needs of more Alternative.
It should be pointed out that the base portion can be set in a kind of specific embodiment of the embodiment of the present invention
Cross section area be all larger than main part cross section area, to be fixed on the base portion in the main part
In the case where point, structure is more firm, and light reflecting effect is more preferable.
Further, the height of the base portion can account for the 1% to 15% of the height of the metallic grid 220.
It should be pointed out that the height of the base portion should not be excessive, the space of filter structure otherwise can be occupied, is led
Cause the undersized of filter structure；The height of the base portion should not be too small, and it is too small otherwise to will lead to the slope to be formed, difficult
To carry out effective baffle to light by reflection.
Referring to Fig. 6, removal mask layer 261 (referring to Fig. 6) etches the top of metallic grid 220 using third etching technics
Portion so that the area of the cross section at the top is less than the area of the cross section of the base portion, and is served as a contrast further away from the semiconductor
The area on the surface at bottom, the cross section at the top is smaller.
Wherein, the metallic grid 220 includes main part and base portion, and the main part includes base portion and position
Top on the base portion.
In embodiments of the present invention, by be arranged metallic grid 220 main part include base portion and be located at the base portion
On top, and the area of the cross section at top be less than the base portion cross section area, can top formed be similar to
The pattern of wedge angle, to increase the area of the cross section on filter structural top surface after forming filter structure, help to make more
More incident lights enter, to help to improve picture quality.
Further, the shape of the longitudinal section at the top can be triangle or trapezoidal, and the longitudinal section is perpendicular to institute
State the surface of semiconductor substrate.
In embodiments of the present invention, the shape of the longitudinal section at the top is triangle or trapezoidal, can be irradiated in light
To the metallic grid 220 top when, there is probability to reflex to filter inside configuration by triangle or trapezoidal bevel edge, compared to
The top surface of metallic grid 220 is plane in the prior art, can be by institute when light exposes to the top surface of metallic grid
It states plane reflection and cannot be introduced into filter structure, using the scheme of the embodiment of the present invention, be conducive to enter more incident lights,
To help to further increase picture quality.
Further, the third etching technics can be sputter etching craft.
In embodiments of the present invention, by using sputter etching craft, anisotropic etching is helped to realize, to be formed
The lesser structure of the area of the cross section at top.
Further, the etching gas of the third etching technics may include SF6And Ar, to realize to metal grid
The etching of grid, it should be pointed out that can also be used to etch the conventional etching process of metallic grid 220, the present invention using other
In embodiment with no restriction to this.
Preferably, the etching gas of the third etching technics may include SF6, Ar and O2, wherein the O2It helps
In the side wall and bottom surface of protection metallic grid 220.Specifically, the O2Material (such as tungsten) with metallic grid can be anti-
Tungsten oxide should be formed, to protect to tungsten.
Referring to Fig. 7, filter structure 206 is formed in the opening of the metallic grid 220, in the filter structure 206
Surface forms lens arrangement 208.
Referring to route A and route B, since the light of oblique fire can be effectively performed in the bottom part of metallic grid 220
Reflection, to realize barrier, helps avoid light and injects adjacent photodiode 202.
Facilitate referring to route C since the inclined-plane at the top of metallic grid 220 can reflect the light of direct projection
So that some light is entered filter structure 206, namely increase the uptake of incident light, to help to improve picture quality.
In embodiments of the present invention, a kind of imaging sensor is also provided, referring to Fig. 7, described image sensor may include:
Semiconductor substrate 200, the semiconductor substrate 200 is interior to have photodiode 202；Latticed metallic grid 220, the gold
Possessive case grid 220 include main part and base portion, and the base portion is located at the surface of the semiconductor substrate 200, institute
Main part is stated to be fixed in the base portion；Filter structure 206, in the opening of the metallic grid 220；Wherein,
Closer to the surface of the semiconductor substrate 200, the area of the cross section of the base portion is bigger, wherein the cross section
It is parallel to the surface of the semiconductor substrate 200.
Further, the shape of the longitudinal section of the base portion is trapezoidal, and the longitudinal section is perpendicular to the semiconductor
The surface of substrate 200.
Further, the area of the cross section of the base portion is greater than the area of the cross section of the main part.
Further, the main part includes base portion and the top on the base portion, the cross section at the top
Area be less than the base portion cross section area, and further away from the surface of the semiconductor substrate 200, the cross at the top
The area in section is smaller.
Further, the shape of the longitudinal section at the top is triangle or trapezoidal, and the longitudinal section is perpendicular to described
The surface of semiconductor substrate 200.
The pass above and shown in Fig. 2 to Fig. 7 is please referred to about the principle of the imaging sensor, specific implementation and beneficial effect
In the associated description of the forming method of imaging sensor, details are not described herein again.
Although present disclosure is as above, present invention is not limited to this.Anyone skilled in the art are not departing from this
It in the spirit and scope of invention, can make various changes or modifications, therefore protection scope of the present invention should be with claim institute
Subject to the range of restriction.
Claims (10)
1. a kind of imaging sensor characterized by comprising
Semiconductor substrate, the semiconductor substrate is interior to have photodiode；
Latticed metallic grid, the metallic grid include main part and base portion, and the base portion is located at institute
The surface of semiconductor substrate is stated, the main part is fixed in the base portion；
Filter structure, in the opening of the metallic grid；
Wherein, closer to the surface of the semiconductor substrate, the area of the cross section of the base portion is bigger, wherein described
Cross section is parallel to the surface of the semiconductor substrate.
2. imaging sensor according to claim 1, which is characterized in that the shape of the longitudinal section of the base portion is ladder
Shape, surface of the longitudinal section perpendicular to the semiconductor substrate.
3. imaging sensor according to claim 1, which is characterized in that the area of the cross section of the base portion is greater than
The area of the cross section of the main part.
4. imaging sensor according to claim 1, which is characterized in that the main part includes base portion and is located at described
Top on base portion, the area of the cross section at the top are less than the area of the cross section of the base portion, and further away from described half
The area on the surface of conductor substrate, the cross section at the top is smaller.
5. imaging sensor according to claim 4, which is characterized in that the shape of the longitudinal section at the top is triangle
Or trapezoidal, surface of the longitudinal section perpendicular to the semiconductor substrate.
6. a kind of forming method of imaging sensor characterized by comprising
Semiconductor substrate is provided, there is photodiode in the semiconductor substrate；
Latticed metallic grid is formed on the surface of the semiconductor substrate, the metallic grid includes main part and bottom
Seating portion, the base portion are located at the surface of the semiconductor substrate, and the main part is fixed on the base portion；
Filter structure is formed in the opening of the metallic grid；
Wherein, closer to the surface of the semiconductor substrate, the area of the cross section of the base portion is bigger, wherein described
Cross section is parallel to the surface of the semiconductor substrate.
7. the forming method of imaging sensor according to claim 6, which is characterized in that in the table of the semiconductor substrate
Face forms latticed metallic grid
Metallic grid material layer is formed on the surface of the semiconductor substrate；
Patterned mask layer is formed on the surface of the metallic grid material layer；
Using the mask layer as exposure mask, using the first etching technics, the first preset thickness of the metallic grid material layer is etched,
To form the main part of the metallic grid；
Using the mask layer as exposure mask, using the second etching technics, the metallic grid material layer is etched, to form the metal
The base portion of grid.
8. the forming method of imaging sensor according to claim 7, which is characterized in that
First etching technics is plasma etch process, and the etching gas of first etching technics includes SF6And
Ar；
Second etching technics is plasma etch process, and the etching gas of second etching technics includes that carbon fluorination is closed
Object gas, SF6And Ar；
Wherein, the fluorocarbon gas is CF4、C4F8And C4F6In single gas, or be CF4、C4F8And C4F6
In multiple gases mixed gas.
9. the forming method of imaging sensor according to claim 6, which is characterized in that the main part includes base portion
With the top being located on the base portion, formed before filter structure in the opening of the metallic grid, further includes:
Using third etching technics, the top is etched, so that the area of the cross section at the top is less than the cross of the base portion
The area in section, and further away from the surface of the semiconductor substrate, the area of the cross section at the top is smaller.
10. the forming method of imaging sensor according to claim 9, which is characterized in that the third etching technics is
Sputter etching craft.
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| CN116053288A (en) * | 2023-01-28 | 2023-05-02 | 合肥晶合集成电路股份有限公司 | Image sensor and manufacturing method thereof |
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Application publication date: 20190326 |