CN110085612A - Imaging sensor and forming method thereof - Google Patents
Imaging sensor and forming method thereof Download PDFInfo
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- CN110085612A CN110085612A CN201910360963.5A CN201910360963A CN110085612A CN 110085612 A CN110085612 A CN 110085612A CN 201910360963 A CN201910360963 A CN 201910360963A CN 110085612 A CN110085612 A CN 110085612A
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- H—ELECTRICITY
- H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
- H10F—INORGANIC SEMICONDUCTOR DEVICES SENSITIVE TO INFRARED RADIATION, LIGHT, ELECTROMAGNETIC RADIATION OF SHORTER WAVELENGTH OR CORPUSCULAR RADIATION
- H10F39/00—Integrated devices, or assemblies of multiple devices, comprising at least one element covered by group H10F30/00, e.g. radiation detectors comprising photodiode arrays
- H10F39/10—Integrated devices
- H10F39/12—Image sensors
- H10F39/18—Complementary metal-oxide-semiconductor [CMOS] image sensors; Photodiode array image sensors
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- H—ELECTRICITY
- H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
- H10F—INORGANIC SEMICONDUCTOR DEVICES SENSITIVE TO INFRARED RADIATION, LIGHT, ELECTROMAGNETIC RADIATION OF SHORTER WAVELENGTH OR CORPUSCULAR RADIATION
- H10F39/00—Integrated devices, or assemblies of multiple devices, comprising at least one element covered by group H10F30/00, e.g. radiation detectors comprising photodiode arrays
- H10F39/011—Manufacture or treatment of image sensors covered by group H10F39/12
- H10F39/014—Manufacture or treatment of image sensors covered by group H10F39/12 of CMOS image sensors
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- H—ELECTRICITY
- H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
- H10F—INORGANIC SEMICONDUCTOR DEVICES SENSITIVE TO INFRARED RADIATION, LIGHT, ELECTROMAGNETIC RADIATION OF SHORTER WAVELENGTH OR CORPUSCULAR RADIATION
- H10F39/00—Integrated devices, or assemblies of multiple devices, comprising at least one element covered by group H10F30/00, e.g. radiation detectors comprising photodiode arrays
- H10F39/80—Constructional details of image sensors
- H10F39/802—Geometry or disposition of elements in pixels, e.g. address-lines or gate electrodes
- H10F39/8027—Geometry of the photosensitive area
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Abstract
一种图像传感器及其形成方法，所述图像传感器包括：半导体衬底，所述半导体衬底具有光电感应单元；光电二极管组，位于所述光电感应单元内；控制栅极，位于所述光电感应单元，所述控制栅极自所述半导体衬底表面沿所述中心轴向所述半导体衬底内部延伸；多个第一浮置扩散区，所述第一浮置区域是指所述光电感应单元的围绕所述控制栅极的部分；多个第二浮置扩散区，所述第二浮置区域是指所述光电感应单元的围绕所述第一浮置区域的部分。本发明方案在减小器件面积和维持较高灵敏度的同时，可以通过利用第二浮置扩散区，有机会选择适当的浮置扩散区以改变总电容大小。
An image sensor and its forming method, the image sensor includes: a semiconductor substrate, the semiconductor substrate has a photoelectric sensing unit; a photodiode group, located in the photoelectric sensing unit; a control gate, located in the photoelectric sensing unit unit, the control gate extends from the surface of the semiconductor substrate along the central axis to the interior of the semiconductor substrate; a plurality of first floating diffusion regions, the first floating region refers to the photoelectric sensor A part of the unit surrounding the control gate; a plurality of second floating diffusion regions, the second floating region refers to the part of the photosensitive unit surrounding the first floating region. While reducing the device area and maintaining high sensitivity, the solution of the present invention can use the second floating diffusion region to have the opportunity to select an appropriate floating diffusion region to change the size of the total capacitance.
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, CIS) device as an example, since it is with low-power consumption and high noise
Than the advantages of, therefore be widely applied in various fields.
During forming existing CIS pixel device, photodiode is usually first formed in semiconductor substrate
(Photo Diode, PD) forms control grid (Gate) on the surface of semiconductor substrate, and then in the other side of control grid
Semiconductor substrate in formed floating diffusion region (Floating Diffusion, FD), wherein adjacent pixel device can be total to
With the floating diffusion region.
However, the area occupied of above-mentioned CIS is larger, and the limited area of floating diffusion region, cause production cost higher.
Summary of the invention
The technical problem to be solved by the present invention is to provide a kind of imaging sensor and forming method thereof, reduce device area and
While maintaining higher sensitivity, can by utilizing the second floating diffusion region, have an opportunity to select floating diffusion region appropriate with
Change total capacitance size.
In order to solve the above technical problems, the embodiment of the present invention provides a kind of imaging sensor, comprising: semiconductor substrate, institute
Semiconductor substrate is stated with optoelectronic induction unit；Photodiode group is located in the optoelectronic induction unit, and the photoelectricity two
Multiple photodiodes in pole pipe group are distributed around the central axis of the optoelectronic induction unit；Grid is controlled, the light is located at
Electric induction unit, the control grid prolong inside the central axial semiconductor substrate from the semiconductor substrate surface
It stretches；Multiple first floating diffusion regions are distributed in the first float zone around the central axis of the optoelectronic induction unit, the multiple
First floating diffusion region and the multiple photodiode correspond, and first float zone refers to the optoelectronic induction list
The part around the control grid of member；Multiple second floating diffusion regions surround the optoelectronic induction in the second float zone
The central axis of unit is distributed, and the multiple second floating diffusion region and the multiple first floating diffusion region correspond, described
Second float zone refers to the part around first float zone of the optoelectronic induction unit.
Optionally, described image sensor further include: multiple transmission grids, positioned at the surface of the semiconductor substrate, institute
It states multiple transmission grids and the multiple second floating diffusion region corresponds, each second floating diffusion region is located at corresponding biography
In the semiconductor substrate of defeated grid side, corresponding first floating diffusion region of each second floating diffusion region is located at corresponding transmission
In the semiconductor substrate of the other side of grid.
Optionally, the sum of area of first float zone and second float zone is less than or equal to the light inductance
The area on the surface of unit is answered, the surface of the optoelectronic induction unit is parallel to the surface of the semiconductor substrate.
Optionally, the top surface of the control grid is higher than or is flush to the surface of the semiconductor substrate.
Optionally, described image sensor further include: isolated area is located at first floating diffusion region and floats with described second
It sets between diffusion region.
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 optoelectronic induction unit；Two pole of photoelectricity is formed in the optoelectronic induction unit
Pipe group, multiple photodiodes in the photodiode group are distributed around the central axis of the optoelectronic induction unit；Institute
It states optoelectronic induction unit and forms control grid, the control grid is from the semiconductor substrate surface along described central axial described
Semiconductor substrate internal stretch；Form multiple first floating diffusion regions and multiple second floating diffusion regions, the multiple first
Floating diffusion region is distributed in the first float zone around the central axis of the optoelectronic induction unit, the multiple first floating diffusion
Area and the multiple photodiode correspond, and first float zone refers to that surrounding for the optoelectronic induction unit is described
The part of grid is controlled, the multiple second floating diffusion region surrounds the center of the optoelectronic induction unit in the second float zone
Axis distribution, the multiple second floating diffusion region and the multiple first floating diffusion region correspond, second floating region
Domain refers to the part around first float zone of the optoelectronic induction unit.
Optionally, the forming method of described image sensor further include: formed on the surface of the semiconductor substrate multiple
Grid is transmitted, the multiple transmission grid and the multiple second floating diffusion region correspond, each second floating diffusion region
In the semiconductor substrate of corresponding transmission grid side, each second floating diffusion region corresponding first floating diffusion region position
In in the semiconductor substrate of the other side of corresponding transmission grid.
Optionally, forming multiple transmission grids on the surface of the semiconductor substrate includes: in the semiconductor substrate
Surface forms transmission gate dielectric layer；Transmission gate material layers are formed on the surface of the transmission gate dielectric layer；To the biography
Defeated gate material layers and the transmission gate dielectric layer perform etching, to form the multiple transmission grid.
Optionally, forming control grid in the optoelectronic induction unit includes: that control is formed in the optoelectronic induction unit
Gate trench processed, the control gate trench is from the semiconductor substrate surface along the central axial semiconductor substrate
Portion extends, and the bottom-exposed of the control gate trench goes out one of each photodiode in the photodiode group
Point；Form isolated film in the control gate trench, the isolated film cover the control gate trench bottom and
Side wall；Gate material layers are formed on the surface of the isolated film and the surface of the semiconductor substrate；To the grid material
The bed of material and the isolated film are planarized, to form transmission grid and expose the surface of the semiconductor substrate, and
The surface of the transmission grid is flush to the surface of the semiconductor substrate.
Optionally, forming control grid in the optoelectronic induction unit includes: that control is formed in the optoelectronic induction unit
Gate trench processed, the control gate trench is from the semiconductor substrate surface along the central axial semiconductor substrate
Portion extends, and the bottom-exposed of the control gate trench goes out one of each photodiode in the photodiode group
Point；Form isolated film in the control gate trench, the isolated film cover the control gate trench bottom and
Side wall；Gate material layers are formed on the surface of the isolated film and the surface of the semiconductor substrate；To the grid material
The bed of material and the isolated film perform etching, to form transmission grid and expose the surface of the semiconductor substrate, and institute
The surface for stating transmission grid is higher than the surface of the semiconductor substrate.
Optionally, multiple first floating diffusion regions of the formation and multiple second floating diffusion regions include: described half
The surface of conductor substrate forms patterned first mask layer, first mask layer expose first floating diffusion region with
And second floating diffusion region, and block the isolation between first floating diffusion region and second floating diffusion region
Area；Using first mask layer as exposure mask, the first ion implanting is carried out to the semiconductor substrate, it is floating to form described first
Diffusion region and second floating diffusion region.
Optionally, multiple first floating diffusion regions of the formation and multiple second floating diffusion regions include: described half
The surface of conductor substrate forms patterned second mask layer, second mask layer expose first floating diffusion region,
Second floating diffusion region and its between isolated area；Using second mask layer as exposure mask, to the semiconductor substrate into
The second ion implanting of row, to form initial floating diffusion region；Patterned third is formed on the surface of the semiconductor substrate to cover
Film layer, the third mask layer expose the isolated area between first floating diffusion region and second floating diffusion region；
Using the third mask layer as exposure mask, third ion implanting is carried out to the semiconductor substrate, to form ion implanting isolated area.
Compared with prior art, the technical solution of the embodiment of the present invention has the advantages that
In embodiments of the present invention, by multiple first floating diffusion regions for being arranged in the first float zone and
Multiple second floating diffusion regions in two float zones, since the first float zone surrounds the control grid, the second floating region
Domain surrounds first float zone, compared with the prior art in, the other side that floating diffusion region is located at control grid is partly led
In body substrate, the area by photodiode is limited, it is difficult to which enlarged-area is had an opportunity using the scheme of the embodiment of the present invention
Expand the area of floating diffusion region while reducing the gross area of imaging sensor, and since the floating diffusion of two parts is arranged
Area can have an opportunity to select floating diffusion region appropriate total to change by utilizing the second floating diffusion region when needed
Capacitance size.
Further, described image sensor further includes multiple transmission grids, the multiple transmission grid and the multiple the
Two floating diffusion regions correspond, and each second floating diffusion region is located in the semiconductor substrate of corresponding transmission grid side,
Corresponding first floating diffusion region of each second floating diffusion region is located at the semiconductor substrate of the other side of corresponding transmission grid
It is interior, using the scheme of the embodiment of the present invention, grid can be transmitted by control, the first floating diffusion region is used only in selection, quite
In utilizing lesser floating diffusion region capacitor, less carrier is stored in dim light, thus imaging effect when improving dim light；
Grid can also be transmitted by control, select while using the first floating diffusion region and the second floating diffusion region, be equivalent to benefit
With biggish floating diffusion region capacitor, more carrier is stored in strong light, thus imaging effect when improving strong light.Namely
The dynamic range (Dynamic Range) of imaging sensor is effectively improved by variable floating diffusion region total capacitance.
Further, the sum of area of first float zone and second float zone is less than or equal to the light inductance
The area for answering the surface of unit helps to make the pixel device comprising including photodiode, control grid and floating diffusion region
The area of part is contracted to the sectional area of optoelectronic induction unit, effectively further reduces device area.
Detailed description of the invention
Fig. 1 is a kind of top view of imaging sensor in the prior art；
Fig. 2 is a kind of top view of imaging sensor in the embodiment of the present invention；
Fig. 3 is a kind of bottom view of imaging sensor in the embodiment of the present invention；
Fig. 4 is a kind of device profile structural schematic diagram of imaging sensor in the embodiment of the present invention；
Fig. 5 is a kind of flow chart of the forming method of imaging sensor in the embodiment of the present invention；
Fig. 6 to Figure 11 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；
Figure 12 is the corresponding device profile structural schematic diagram of forming method of another isolated area in the embodiment of the present invention；
Figure 13 is the top view of another imaging sensor in the embodiment of the present invention.
Specific embodiment
In existing CIS formation process, photodiode is first usually formed in semiconductor substrate, in semiconductor substrate
Surface formed control grid, and then control grid the other side semiconductor substrate in form floating diffusion region, lead to CIS
Area occupied it is larger.
Referring to Fig.1, Fig. 1 is a kind of top view of imaging sensor in the prior art.Described image sensor may include
Semiconductor substrate 100, multiple photodiodes 110, area of isolation 120, control grid 130 and floating diffusion region 140.
Wherein, photodiode group can be located in the semiconductor substrate 100, multiple in the photodiode group
There is area of isolation 120 between photodiode 110.
The surface that grid 130 can be located at the semiconductor substrate 100 is controlled, the photodiode 110 is located at described
Control one side of grid 130.
The floating diffusion region 140 can be located in the semiconductor substrate 100, and be located at the control grid 130
Another side.
Wherein, the control grid 130 is used for when powering on, and makes the channel (Channel) of 130 lower section of control grid
It opens, so that the photo-generated carrier that the photodiode 110 is formed can be moved to floating diffusion region 140 and be deposited
Storage.
It should be pointed out that in imaging sensor shown in fig. 1, in order to reduce area, not in each optoelectronic induction
Single photodiode, floating diffusion region and transmission grid are set in unit, but two adjacent photodiodes are set
Share a floating diffusion region 140.Wherein, the optoelectronic induction unit can indicate the minimum repetitive unit of CIS, for realizing
Photo-generated carrier is transmitted to corresponding floating diffusion region 140 from photodiode 110.
The present inventor has found that in the prior art, the area of described image sensor is larger after study, however
Scaled down directly is carried out to the area of imaging sensor, it is too small to will lead to 140 area of floating diffusion region, influences photoproduction current-carrying
The full well capacity of son, the reduced performance of sensor.Specifically, the floating diffusion region 140 is located at the another of control grid 130
In the semiconductor substrate 100 of side, namely there are the regions of photodiode 110, and floating diffusion region 140 cannot be arranged, and causes to float
The area that diffusion region 140 is set by photodiode 110 is limited, it is difficult to enlarged-area.In the feelings that the single pixel gross area is constant
Under condition, if the area that the area for increasing floating diffusion region 140 will lead to photodiode 110 reduces, lead to photoproduction current-carrying
The full-well capacity of son is restricted.
In embodiments of the present invention, by multiple first floating diffusion regions for being arranged in the first float zone and
Multiple second floating diffusion regions in two float zones, by the first float zone refer to the optoelectronic induction unit around institute
The part of control grid is stated, the second float zone refers to the portion around first float zone of the optoelectronic induction unit
Point, compared with the prior art in, floating diffusion region be located at control grid the other side semiconductor substrate in, by two pole of photoelectricity
The area of pipe limits, it is difficult to which enlarged-area is had an opportunity using the scheme of the embodiment of the present invention in the total face for reducing imaging sensor
Expand the area of floating diffusion region while product, and since two parts floating diffusion region is arranged, can pass through when needed
Using the second floating diffusion region, have an opportunity to select floating diffusion region appropriate to change total capacitance size.
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.
In conjunction with referring to Fig. 2, Fig. 3 and Fig. 4, Fig. 2 is a kind of top view of imaging sensor, Fig. 3 in the embodiment of the present invention
It is a kind of bottom view of imaging sensor in the embodiment of the present invention, Fig. 4 is a kind of device of imaging sensor in the embodiment of the present invention
Part the schematic diagram of the section structure.
Described image sensor may include multiple photodiodes that semiconductor substrate 200, photodiode group include
210, grid 230 and floating diffusion region 240 are controlled, can also include area of isolation and transmission grid 202.
Wherein, the floating diffusion region 240 may include multiple first floating diffusion regions 241 and multiple second floating expansions
Dissipate area 242.
Wherein, the area of isolation may include the first isolated area 221, the second isolated area 244 and isolated film 232.
Wherein, first isolated area 221 can be used for that adjacent photodiode 210 is isolated, second isolated area 244
It can be used for that the first floating diffusion region 241 and the second floating diffusion region 242 is isolated, the isolated film 232 can be with
Gate dielectric layer as the control grid 230.
It should be pointed out that can have multiple optoelectronic induction units (Cell) in the semiconductor substrate 200, Fig. 2 and
Imaging sensor shown in Fig. 3 can be considered as single optoelectronic induction unit.Wherein, the optoelectronic induction unit can indicate to scheme
As the minimum repetitive unit of sensor, photo-generated carrier is transmitted to corresponding floating diffusion for realizing from photodiode 210
Area.
In specific implementation, the photodiode group can be located in the optoelectronic induction unit, and the photoelectricity two
Multiple photodiodes 210 in pole pipe group are distributed around the central axis of the optoelectronic induction unit.
It should be pointed out that example is carried out using four photodiodes 210 in Fig. 2, however in the embodiment of the present invention
In, the quantity of photodiode 210 is not limited.
Further, the photodiode 210 can be uniformly distributed around the central axis of the optoelectronic induction unit, from
And keeping the area of each photodiode, floating diffusion region uniform, raising forms photo-generated carrier and storage photo-generated carrier
Uniformity, to improve image quality.
In specific implementation, the control grid 230 can be located at the optoelectronic induction unit, the control grid 230
From 200 surface of semiconductor substrate along central axial 200 internal stretch of semiconductor substrate.In specific implementation,
It can be provided with isolated film 232 between control grid 230 and semiconductor substrate 200, the grid as the control grid 230
Dielectric layer, so that the control grid 230 is contacted with the isolated film 232, the isolated film 232 and the photoelectricity
Diode 210 contacts.
It should be pointed out that as shown in figure 4, the bottom of the control grid 230 and first isolated area 221 form ditch
The threshold voltage in road is Vt2, the threshold voltage of the side wall and the semiconductor substrate 200 formation channel of the control grid 230
For Vt1, the Vt2> Vt1。
In embodiments of the present invention, by the way that Vt is arranged2> Vt1, can be to avoid by controlling the unlatching photoelectricity two of grid 230
When channel between pole pipe 210 and floating diffusion region, as long as meeting smaller value Vt1It can open, avoid result in photodiode
Channel between 210, which is opened by mistake, to be opened, and electrical cross talk is caused.
Multiple first floating diffusion regions 241, in the first float zone A around the central axis point of the optoelectronic induction unit
Cloth, the multiple first floating diffusion region 241 are corresponded with the multiple photodiode 210, the first float zone A
Refer to the part around the control grid 230 of the optoelectronic induction unit.
Multiple second floating diffusion regions 242, in the second float zone B around the central axis point of the optoelectronic induction unit
Cloth, the multiple second floating diffusion region 242 are corresponded with the multiple first floating diffusion region 241, and described second is floating
Region B refers to the part around the first float zone A of the optoelectronic induction unit.
In embodiments of the present invention, by multiple first floating diffusion regions 241 for being arranged in the first float zone A and
Multiple second floating diffusion regions 242 in the second float zone B, since the first float zone A surrounds the control grid
230, the second float zone B surround the first float zone A, compared with the prior art in, floating diffusion region is located at control gate
In the semiconductor substrate of the other side of pole, the area by photodiode is limited, it is difficult to which enlarged-area is implemented using the present invention
The scheme of example has an opportunity to expand the area of floating diffusion region while reducing the gross area of imaging sensor, and due to setting
Two parts floating diffusion region can have an opportunity to select appropriate by utilizing the second floating diffusion region 242 when needed
Floating diffusion region is to change total capacitance size.
It should be pointed out that in the prior art, it is difficult to realize high dynamic range while not reducing sensitivity
(Higher Dynamic Range).Specifically, conventionally, as the size of floating diffusion region is often unified
, it is fixed for causing the size of total capacitance to also tend to.
Further, in embodiments of the present invention, the imaging sensor can also include multiple transmission grids 202,
Positioned at the surface of the semiconductor substrate 200, the transmission grid 202 is corresponded with second floating diffusion region 242, often
A second floating diffusion region 242 is located in the semiconductor substrate 200 of corresponding transmission 202 side of grid, each second floating expansion
In the semiconductor substrate 200 for dissipating the other side that corresponding first floating diffusion region 241 in area 242 is located at corresponding transmission grid 202.
Wherein, the transmission grid 202 is used for when powering on, and makes first floating diffusion region 241 and corresponding second
Channel between floating diffusion region 242 is opened.
In embodiments of the present invention, grid 202 can be transmitted by control, the first floating diffusion region 241 is used only in selection,
It is equivalent to using lesser floating diffusion region capacitor, less photo-generated carrier is stored in dim light, thus when improving dim light
Imaging effect；Grid 202 can also be transmitted by control, selected while floating using the first floating diffusion region 241 and second
Diffusion region 242 is equivalent to using biggish floating diffusion region capacitor, more photo-generated carrier is stored in strong light, to mention
Imaging effect when high-strength smooth, namely total floating diffusion region capacitor by can be changed effectively improve the dynamic of imaging sensor
Range.
Further, the sum of the area of the first float zone A and the second float zone B can be less than or equal to institute
The area on the surface of optoelectronic induction unit is stated, the surface of the optoelectronic induction unit is parallel to the table of the semiconductor substrate 200
Face.
In embodiments of the present invention, the first float zone A is set and the sum of the area of the second float zone B can
To be less than or equal to the area on the surface of the optoelectronic induction unit, help to make comprising photodiode 210, control grid 230
And the area of the pixel device including floating diffusion region 240 is contracted to the sectional area of optoelectronic induction unit, so that photoelectricity
The sectional area of sensing unit is only related with the area of photodiode group, and the area of floating diffusion region 240 no longer influences light inductance
Unit is answered, to effectively further reduce device area.
Further, the top surface of the control grid 230 can be higher than or be flush to the semiconductor substrate 200
Surface.
Specifically, the control grid 230 can be formed using etching technics or flatening process, so that the control
The top surface of grid 230 can be higher than or be flush to the surface of the semiconductor substrate 200.
In embodiments of the present invention, institute can be selected according to other of specific requirements and described image sensor device
The height at the top of control grid 230 is stated, to facilitate the design complexities and technology difficulty of reduction imaging sensor.
Further, described image sensor further include: the second isolated area 244 is located at first floating diffusion region 241
Between second floating diffusion region 242.
It specifically, can be using semiconductor substrate 200 as first floating diffusion region 241 and the described second floating expansion
The isolation between area 242 is dissipated, can also be adopted after forming the first floating diffusion region 241 and second floating diffusion region 242
Second isolated area 244 is formed with the method for ion implanting.
More specifically, using semiconductor substrate 200 as first floating diffusion region 241 and the described second floating diffusion
Isolation between area 242 helps to reduce process complexity, however needs the first floating diffusion region 241 and described second floating
There is enough distances between diffusion region 242；Second isolated area 244 is formed using the method for ion implanting, is facilitated
It is lesser to realize preferable isolation effect apart from interior, however increase process costs.
In embodiments of the present invention, according to specific accuracy requirement and technique complexity can select which kind of is used
Mode realizes being isolated between the first floating diffusion region 241 and second floating diffusion region 242, to help reducing work
Seek to balance between skill difficulty and raising isolation effect.
The embodiment of the invention also discloses a kind of forming methods of imaging sensor.
Referring to Fig. 5, Fig. 5 is a kind of flow chart of the forming method of imaging sensor in the embodiment of the present invention.Described image
The forming method of sensor may include step S21 to step S24:
Step S21: semiconductor substrate is provided, there is optoelectronic induction unit in the semiconductor substrate；
Step S22: forming photodiode group in the optoelectronic induction unit, multiple in the photodiode group
Photodiode is distributed around the central axis of the optoelectronic induction unit；
Step S23: control grid is formed in the optoelectronic induction unit, the control grid is from the semiconductor substrate table
Face is along the central axial semiconductor substrate internal stretch；
Step S24: multiple first floating diffusion regions and multiple second floating diffusion regions are formed, the multiple first is floating
Diffusion region the first float zone around the optoelectronic induction unit central axis be distributed, the multiple first floating diffusion region with
The multiple photodiode corresponds, first float zone refer to the optoelectronic induction unit around the control
The part of grid, the multiple second floating diffusion region is in the second float zone around the central axis point of the optoelectronic induction unit
Cloth, the multiple second floating diffusion region and the multiple first floating diffusion region correspond, and second float zone is
Refer to the part around first float zone of the optoelectronic induction unit.
Above-mentioned each step is illustrated below with reference to Fig. 6 to Figure 11.
Fig. 6 to Figure 11 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. 6, semiconductor substrate 200 is provided, there is optoelectronic induction unit in the semiconductor substrate 200, described
Photodiode group is formed in optoelectronic induction unit, includes multiple photodiodes 210 in the photodiode group, and institute
The central axis that multiple photodiodes are stated around the optoelectronic induction unit is distributed.
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 is exposure mask with first mask layer 261, in the light inductance it is possible to further form the first mask layer 261
It answers and forms photodiode group in unit.
Wherein, first mask layer 261 exposes the region of photodiode to be formed, and blocks multiple two poles of photoelectricity
Region to be isolated between pipe.
It should be pointed out that in another specific embodiment of the embodiment of the present invention, it can also be described to be isolated
The Doped ions of photodiode are injected in region together.First mask layer 261 can expose two pole of photoelectricity to be formed
Then in the subsequent process region to be isolated between the region of pipe and multiple photodiodes passes through the side of ion implanting
Formula forms isolated area in the photodiode.
Preferably, the injection ion of the photodiode 210 can be N-type ion, such as can be selected from: P, As and
Sb。
In embodiments of the present invention, it is N-type ion by the injection ion that photodiode 210 is arranged, figure can be set
As the principal carrier of sensor is electronics, raising arithmetic speed.
Referring to Fig. 7, the second mask layer 262 is formed, is exposure mask with second mask layer 262, using ion implantation technology,
The first isolated area 221 is formed in the optoelectronic induction unit.
In another specific embodiment of the embodiment of the present invention, the isolated area 221 can also use (Deep
Trench Isolation, DTI) structure.Specifically, deep trench first can be formed using etching technics, then using deposition work
Skill filled media layer into the deep trench, to form the DTI structure.
It should be pointed out that in another specific embodiment of the embodiment of the present invention, in the semiconductor substrate 200
Be previously implanted with the different types of Doped ions of the photodiode 210, therefore have isolation effect, can be set at this time
Only to form photodiode 210 by ion implanting, and use between adjacent photodiode 210 with isolation effect
Semiconductor substrate 200 is isolated, it is to be understood that needs to retain between photodiode 210 safety of pre-determined distance
Region.
Referring to Fig. 8, control gate trench 231 is formed in the optoelectronic induction unit, the control gate trench 231 is certainly
200 surface of semiconductor substrate is along central axial 200 internal stretch of semiconductor substrate, and the control grid ditch
The bottom-exposed of slot 231 goes out a part of each photodiode 210 in the photodiode group.
Referring to Fig. 9, isolated film 232, the isolated film are formed in the control gate trench 231 (referring to Fig. 8)
The bottom and side wall of the 232 coverings control gate trench 231 forms control grid on the surface of the isolated film 232
230。
In a kind of specific embodiment of the embodiment of the present invention, first on the surface of the isolated film 232 and described
The surface of semiconductor substrate 200 forms gate material layers, then carries out to the gate material layers and the isolated film 232
Planarization, to form control grid 230 and expose the surface of the semiconductor substrate 200, and the table of the control grid 230
Face is flush to the surface of the semiconductor substrate 200.
In another specific embodiment of the embodiment of the present invention, first surface and institute in the isolated film 232
The surface for stating semiconductor substrate 200 forms gate material layers, then to the gate material layers and the isolated film 232 into
Row etching, to form control grid 230 and expose the surface of the semiconductor substrate 200, and the table of the control grid 230
Face is higher than the surface of the semiconductor substrate 200.
In embodiments of the present invention, institute can be selected according to other of specific requirements and described image sensor device
The height at the top of control grid 230 is stated, to facilitate the design complexities and technology difficulty of reduction imaging sensor.
Referring to Fig.1 0, patterned third mask layer 263, the third are formed on the surface of the semiconductor substrate 200
Mask layer 263 exposes the first floating diffusion region, second floating diffusion region, and the isolated area between blocking.Then with institute
Stating third mask layer 263 is exposure mask, carries out third ion implanting to the semiconductor substrate 200, to form initial floating diffusion
Area 246.Referring to Fig.1 1, patterned 4th mask layer 264 is formed on the surface of the semiconductor substrate 200, the described 4th covers
Film layer 264 exposes the isolated area between first floating diffusion region 241 and second floating diffusion region 242, with described
4th mask layer 264 is exposure mask, carries out the 4th ion implanting to the semiconductor substrate 200, in the initial floating diffusion
Ion implanting isolated area namely the second isolated area 244 are formed in area 246.
It should be pointed out that in the forming method shown in Figure 10 to 11, inject that form first floating using single ion
Diffusion region 241 and the second floating diffusion region 242 help to reduce process complexity and production cost.It is understood that described
Certain safe distance should be provided between first floating diffusion region 241 and the second floating diffusion region 242.
Further, multiple transmission grids 202 are formed on the surface of the semiconductor substrate 200, to obtain shown in Fig. 4
Imaging sensor.
With continued reference to Fig. 4, can wrap in the step of surface of the semiconductor substrate 200 forms multiple transmission grid 202
It includes: forming transmission gate dielectric layer on the surface of the semiconductor substrate 200；It is formed on the surface of the transmission gate dielectric layer
Transmit gate material layers；The transmission gate material layers and the transmission gate dielectric layer are performed etching, described in being formed
Multiple transmission grids 202.Namely in the device shown in Fig. 4, the transmission grid 202 also includes and the semiconductor substrate
Transmission gate dielectric layer between 200.
2, Figure 12 is the corresponding device profile structure of forming method of another isolated area in the embodiment of the present invention referring to Fig.1
Schematic diagram.
On the basis of the imaging sensor shown in Fig. 9, patterned is formed on the surface of the semiconductor substrate 200
Five mask layers 265, the 5th mask layer 265 expose first floating diffusion region 341 and the second floating diffusion
Area 342, and block the region to be isolated between first floating diffusion region 341 and second floating diffusion region 342 (i.e.
Isolated area), with the 5th mask layer 265 for exposure mask, the first ion implanting is carried out to the semiconductor substrate 200, to be formed
First floating diffusion region 341 and second floating diffusion region 342.
Further, multiple transmission grids 202 are formed on the surface of the semiconductor substrate 200.
3, Figure 13 is the top view of another imaging sensor in the embodiment of the present invention referring to Fig.1.The first floating expansion
The shape for dissipating area 441 and second floating diffusion region 442 can be annular, and transmission grid 402 is floating with the multiple second
The one-to-one correspondence of diffusion region 442 is set, each second floating diffusion region 442 is located at the semiconductor lining of corresponding transmission 402 side of grid
In bottom 200, corresponding first floating diffusion region 441 of each second floating diffusion region 442 is located at the another of corresponding transmission grid 402
In the semiconductor substrate 200 of side.
It should be pointed out that by using the first floating diffusion region 441 and second floating diffusion region of annular
442, compared to using edge to have in Fig. 2 for the first floating diffusion region 241 of rectangle and second floating diffusion region 242
Help reduce edge effect.
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 (12)
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US12166049B2 (en) | 2021-03-22 | 2024-12-10 | Samsung Electronics Co., Ltd. | Image sensor having a gate electrode on a semiconductor pattern side wall |
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| CN101609837A (en) * | 2008-06-09 | 2009-12-23 | 索尼株式会社 | Solid photographic device, its driving method and the electronic installation that uses it |
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