CN110112166A - A kind of inclination grid back-illuminated cmos image sensors - Google Patents
A kind of inclination grid back-illuminated cmos image sensors Download PDFInfo
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- CN110112166A CN110112166A CN201910432896.3A CN201910432896A CN110112166A CN 110112166 A CN110112166 A CN 110112166A CN 201910432896 A CN201910432896 A CN 201910432896A CN 110112166 A CN110112166 A CN 110112166A
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- H—ELECTRICITY
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- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L27/00—Devices consisting of a plurality of semiconductor or other solid-state components formed in or on a common substrate
- H01L27/14—Devices consisting of a plurality of semiconductor or other solid-state components formed in or on a common substrate including semiconductor components sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation
- H01L27/144—Devices controlled by radiation
- H01L27/146—Imager structures
- H01L27/14601—Structural or functional details thereof
- H01L27/14609—Pixel-elements with integrated switching, control, storage or amplification elements
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- H—ELECTRICITY
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- H01L27/14—Devices consisting of a plurality of semiconductor or other solid-state components formed in or on a common substrate including semiconductor components sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation
- H01L27/144—Devices controlled by radiation
- H01L27/146—Imager structures
- H01L27/14601—Structural or functional details thereof
- H01L27/14609—Pixel-elements with integrated switching, control, storage or amplification elements
- H01L27/14612—Pixel-elements with integrated switching, control, storage or amplification elements involving a transistor
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- H—ELECTRICITY
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- 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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Abstract
The invention discloses a kind of back-illuminated cmos image sensors, comprising: N number of photodiode；One transmission switch, the transmission switch include N number of channel region electrically isolated from one below a grid and the grid；And N number of floating node, wherein each of described N number of photodiode is connected to corresponding one in N number of floating node by a corresponding channel region for the transmission switch.
Description
Technical field
The present invention relates to semiconductor integrated circuit fields, specifically, the present invention relates to a kind of inclination grid back-illuminated types
Cmos image sensor.
Background technique
Cmos image sensor is a kind of imaging sensor based on CMOS technology manufacture, for converting analog optical signal
For digital electric signal.Image is converged to cmos image sensor photosensitive region pixel array by optical device by external light source
On.The optical signal received is converted analog electrical signal by pixel array, and by amplification, denoising be sent in analog-digital converter into
Digitized.Finally, digitized signal obtains a width clearly true image by picture processing chip operation.
Back-illuminated cmos image sensors are since with small power consumption, the advantages such as quantum efficiency height are widely used at present
In the equipment such as mobile phone, video camera.It is exactly to change the structure inside element in place of the maximum optimization of back-illuminated cmos image sensors
Become, i.e., the element of photosensitive layer is turned into direction, allowing luminous energy from the back side, direct projection is entered, and avoids conventional CMOS sensor structure
In, light will receive the influence of metallic circuit and transistor between lenticule and photodiode, to significantly improve light
Efficiency substantially improves the shooting effect under low-light conditions.
Traditional back-illuminated cmos image sensors product, essential structure include: lenticule, optical filter, two pole of photoelectricity
The structures such as pipe, metal layer.Fig. 1 shows the circuit diagram of the back-illuminated cmos image sensors of the prior art.Fig. 2 shows the prior arts
Photodiode cross-sectional view.Currently used cmos image sensor be 4T circuit, including transmission switch (TG,
Transfer Gate) 110, reset transistor (Rx, Reset) 120,130, selecting pipe source follower (Sx, Source Follower)
(Rs, Select) 140, photodiode (PD, Photo Diode) 150, floating node (FD, Floating Diffusion)
160 equal circuit structures.
Demand with people to the image sensor with high pixel is increasing, and the higher and higher chip of pixel is set
Meter and its manufacturing process needs are constantly modified.The 4T circuit used in current pixel unit, as depicted in figs. 1 and 2, transmission
The circuit structures such as switch 110, reset transistor 120, source follower 130, selecting pipe 140, photodiode 150, floating node 160 are all
It is integrated in pixel region, the corresponding TG of a PD occupies biggish pixel region area, reduces the area of photosensitive region,
Influence imaging effect.
Therefore this field needs a kind of novel back-illuminated cmos image sensors, by the structure or cloth that optimize each device
The overall performance of imaging sensor improves in office.
Summary of the invention
For the above-mentioned problems in the prior art, according to an aspect of the present invention, a kind of back-illuminated type CMOS is provided
Imaging sensor, comprising:
N number of photodiode；
One transmission switch, the transmission switch is including N number of electrically isolated from one below a grid and the grid
Channel region；And
N number of floating node, wherein each of described N number of photodiode passes through corresponding the one of the transmission switch
A channel region is connected to corresponding one in N number of floating node.
In one embodiment of the invention, back-illuminated cmos image sensors further include N number of signal transfer circuit, each
Signal transfer circuit is connected to corresponding one in N number of floating node, and each signal transfer circuit includes:
Reset transistor, the source level of the reset transistor are connected to one end of floating node, and the reset transistor drain electrode is connected to power supply；
Source follower, the grid of the source follower are connected to the source level of reset transistor, and the source follower drain electrode is connected to
Power supply；
Selecting pipe, the drain electrode of the selecting pipe are connected to the source electrode of source follower, and the source electrode of the selecting pipe is output end,
Wherein transmit switch, reset transistor, selecting pipe grid be connected to external control circuit.
In one embodiment of the invention, when carrying out signal processing, the transmission switch conduction, each two pole of photoelectricity
The charge of pipe is shifted by corresponding floating node, in output end output signal.
In one embodiment of the invention, back-illuminated cmos image sensors further include being formed in falling on front wafer surface
Terrace with edge groove, the chamfered edge platform top are flushed with front wafer surface, and the topside area of the chamfered edge platform is greater than the area of bottom, described
Chamfered edge platform has N number of inclined side that bottom is extended at the top of chamfered edge platform, each inclined side by isolated groove progress every
From the grid of the transmission switch is formed in chamfered edge platform groove, N number of channel region shape electrically isolated from one of the transmission switch
At on N number of inclined side of the chamfered edge platform.
In one embodiment of the invention, each photodiode includes clamper photodiode PPD, N-type photoelectricity two
The N-doped zone of pole pipe NPD and lower section, floating node and N-type photodiode are respectively formed at the inclined side of chamfered edge platform
Top and bottom, clamper photodiode are formed in the front face surface region of chip and adjacent with floating node, transmit switch
Channel region is arranged between floating node and N-type photodiode.
In another embodiment of the present invention, a kind of back-illuminated cmos image sensors array is provided, comprising:
According to multiple pixel units that matrix-style arranges, each pixel unit includes: 4 photodiodes；One biography
Switch is sent, the transmission switch includes 4 channel regions electrically isolated from one below a grid and the grid；And 4
A floating node, wherein a corresponding channel region of each of described 4 photodiodes by the transmission switch
Corresponding one be connected in 4 floating nodes；
4 signal transfer circuits are provided with around each pixel unit, each signal transfer circuit is connected to described 4 and floats
Corresponding one in empty node, each signal transfer circuit includes: reset transistor, and the source level of the reset transistor is connected to floating section
One end of point, the reset transistor drain electrode are connected to power supply；The grid of source follower, the source follower is connected to the source of reset transistor
Grade, the source follower drain electrode are connected to power supply；Selecting pipe, the drain electrode of the selecting pipe are connected to the source electrode of source follower, institute
The source electrode for stating selecting pipe is output end, wherein the grid of transmission switch, reset transistor, selecting pipe is connected to external control circuit.
In another embodiment of the present invention, adjacent pixel unit shares signal transfer circuit.
In another embodiment of the present invention, when carrying out signal processing, the transmission switch conduction of the first pixel unit,
The charge of each photodiode of first pixel unit is shifted by corresponding floating node, in output end output signal, so
Successively the transmission of the pixel unit in controlled level and vertical direction switchs afterwards, obtains complete picture signal.
In yet another embodiment of the present invention, a kind of manufacturing method of back-illuminated cmos image sensors is provided, comprising:
Dielectric layer is grown on chip, and is implanted into the area photodiode PD and the photodiode isolation region PDI；
Grow mask layer；
Photoresist is coated, keeps photoresist graphical by photoetching process, first mask layer is performed etching, then passes through wet etching
Mode carries out anisotropic etching, and chamfered edge platform groove is formed on front wafer surface；
Sacrificial layer is grown in wafer surface, carries out the implantation of P-well area；
Carry out the implantation of the area NPD；
Carry out the implantation of the area FD；
Carry out the implantation of the area PPD；
Thick silicon dioxide layer is grown as etching polysilicon barrier layer；
Photoresist is coated, keeps photoresist graphical by photoetching process, exposure grid groove region；
Remove the oxide layer in grid groove region；
Photoresist is removed, surface clean simultaneously grows gate oxide；
Undoped polysilicon layer is grown, then carries out surface doping by the way of ion implantation；
Photoresist PR is coated, keeps photoresist graphical by photoetching process, only retains the photoresist of gate polysilicon region；
Gate polycrystalline silicon etching is carried out, remaining photoresist is then removed；
Form dielectric layer；
Metal connecting hole etching and hole fill process are carried out, is formed at the grid of floating node and transmission switch external
Metal interconnection.
In yet another embodiment of the present invention, the area FD and the area NPD are formed in the upper end of the inclined side of chamfered edge platform under
End.
The present invention tilts grid, and common grid by design transmission switch, can promote photodiode to a certain extent
Region area improves image quality.And there are four reset transistor Rx, source follower Sx and selecting pipe Rs around a pixel unit
Circuit, is equivalent to 4 photodiode PD and 4 floating node FD shared 1 transmission switch TG, 2 reset transistor Rx, sources follow
Device Sx and selecting pipe Rs circuit, signal velocity are more fast again than traditional circuit signal transmitting, improve device performance.
Detailed description of the invention
For the above and other advantages and features for each embodiment that the present invention is furture elucidated, will be presented with reference to attached drawing
The more specific description of various embodiments of the present invention.It is appreciated that these attached drawings only describe exemplary embodiments of the invention, therefore
It is not to be regarded as being restriction on its scope.In the accompanying drawings, in order to cheer and bright, identical or corresponding component will use identical or class
As mark indicate.
Fig. 1 shows the circuit diagram of the back-illuminated cmos image sensors of the prior art.
Fig. 2 shows the cross-sectional views of the photodiode of the prior art.
Fig. 3 shows the front view of back-illuminated cmos image sensors 300 according to an embodiment of the invention.
Fig. 4 shows the sectional view of the AA line interception along back-illuminated cmos image sensors 300 shown in Fig. 3.
Fig. 5 shows the rear view of back-illuminated cmos image sensors 300 according to an embodiment of the invention.
Fig. 6 shows the circuit diagram of back-illuminated cmos image sensors 600 according to an embodiment of the invention.
Fig. 7 shows the top view of back-illuminated cmos image sensors array according to an embodiment of the invention.
Fig. 8 A to Fig. 8 P shows the manufacturing process of back-illuminated cmos image sensors according to an embodiment of the invention
Sectional view.
Specific embodiment
In the following description, with reference to each embodiment, present invention is described.However, those skilled in the art will recognize
Know can in the case where none or multiple specific details or with other replacements and/or addition method, material or component
Implement each embodiment together.In other situations, well known structure, material or operation are not shown or are not described in detail in order to avoid making this
The aspects of each embodiment of invention is obscure.Similarly, for purposes of explanation, specific quantity, material and configuration are elaborated, with
Comprehensive understanding to the embodiment of the present invention is just provided.However, the present invention can be implemented in the case where no specific detail.This
Outside, it should be understood that each embodiment shown in the accompanying drawings is illustrative expression and is not drawn necessarily to scale.
In the present specification, the reference of " one embodiment " or " embodiment " is meaned to combine embodiment description
A particular feature, structure, or characteristic is included at least one embodiment of the invention.Occur in everywhere in this specification short
Language " in one embodiment " is not necessarily all referring to the same embodiment.
During manufacturing back-illuminated cmos image sensors chip, the 4T circuit used in pixel unit includes transmission
The circuit structures such as switch, reset transistor, source follower, selecting pipe, photodiode, floating node.The embodiment of the present invention optimization
And design the layout of these circuit structures.
Fig. 3 shows the front view of back-illuminated cmos image sensors 300 according to an embodiment of the invention.Fig. 4
The sectional view of AA line interception along back-illuminated cmos image sensors 300 shown in Fig. 3 is shown.Fig. 5 shows according to the present invention one
The rear view of the back-illuminated cmos image sensors 300 of a embodiment.
Photon enters fastly behind the door, first passes around lenticule 360 and focuses in respective pixel, then passes through Bayer array 380
Optical filter 370 filter out unwanted color.Photon is injected by the device layer back side through substrate to N buried layer to clamper layer direction.Such as
Shown in Fig. 3 to 5, back-illuminated cmos image sensors 300 include that four photodiode 310-1 to 310-4 (are hereinafter collectively referred to as
Photodiode 310), four floating node 320-1 to 320-4 (being hereinafter collectively referred to as floating node 320), transmission switch
330.Four photodiode 310-1 to 310-4 share a transmission switch 330.Four photodiode 310-1 to 310-4
Four floating node 320-1 are connected into 320-4 corresponding one by transmitting switch 330.
Back-illuminated cmos image sensors 300 are formed on chip, including being formed in falling on front wafer surface by etching
Terrace with edge groove.It is square at the top and bottom of chamfered edge platform, topside area is greater than the area of bottom.There are four chamfered edge platform tools from chamfered edge
The inclined side of bottom is extended at the top of platform.Four inclined sides are isolated by isolated groove 340.Transmit switch 330
Grid is formed in chamfered edge platform groove, therefore there are four inclined sides for the grid tool of transmission switch 330.
Four inclined sides tool below the grid of switch 330 is transmitted there are four the channel region being separated, is controlled respectively
The conducting and disconnection of four photodiodes and corresponding floating node.Each photodiode 310 may include the clamper on surface
The N-doped zone of photodiode PPD 311, N-type photodiode NPD 312 and lower section.Floating node 320 and N-type photoelectricity
Diode 312 is respectively formed at the top and bottom of the inclined side of chamfered edge platform.Clamper photodiode 311 is formed in chip
Front is simultaneously adjacent with floating node 320.The channel region for transmitting switch 330 is arranged in floating node 320 and N-type photodiode
Between 312, by voltage at control grid, the conducting and disconnection of floating node 320 and N-type photodiode 312 are realized.
Specifically, forming P type trap zone, floating around the top of chamfered edge platform inclined side referring to sectional view shown in Fig. 4
320th area of node is formed in P type trap zone.N-type photodiode NPD 312 is formed in the lower end of P type trap zone, and including top
The N-doped zone of P-doped zone and lower part.Region between floating node 320 and N-type photodiode NPD 312 is transmission
The channel region of switch 330.
Cmos image sensor circuit disclosed in the embodiment of the present invention is using a kind of novel inclination grid.Cmos image
The area in sensor photodiode region directly determines that the size of full well capacity, the present invention pass through design transmission switch inclination grid
Pole, and common grid can promote photodiode area area to a certain extent, improve image quality.
Fig. 6 shows the circuit diagram of back-illuminated cmos image sensors 600 according to an embodiment of the invention.Such as Fig. 6
It is shown, in addition to photodiode 610 identical with structure shown in Fig. 3 to Fig. 5, floating node 620 and transmission switch 630, back-illuminated
Formula cmos image sensor 600 further includes reset transistor 640, source follower 650, selecting pipe 660.The source level of reset transistor 640 connects
To one end of floating node 620, drain electrode is connected to power vd D.The grid of source follower 650 is connected to the source of reset transistor 640
Grade, drain electrode are connected to power vd D.The drain electrode of selecting pipe 660 is connected to the source electrode of source follower 650, the source electrode of selecting pipe 660
For output end.Transmission switch 630, reset transistor 640, selecting pipe 660 grid be connected to external control circuit.
Fig. 7 shows the top view of back-illuminated cmos image sensors array according to an embodiment of the invention.Such as Fig. 7
Shown, illuminated cmos image sensor array may include the array of four rows, four column photodiode.Those skilled in the art answers
The understanding, array shown in Fig. 7 are only intended to the purpose schematically illustrated, and the image sensor array that the present invention is protected can be according to reality
Border is needed comprising any number of row and column.In the embodiment shown in fig. 7, four photoelectricity two of two adjacent rows and two column
Pole pipe PD shares a transmission and switchs, the corresponding floating node FD of each photodiode, therefore four photodiode PD,
Four floating node FD and a transmission switch TG form a pixel unit.Each floating node is connected to corresponding reset transistor
Rx, source follower Sx and selecting pipe Rs.As shown in fig. 7, being passed by the signal that reset transistor Rx, source follower Sx and selecting pipe Rs are formed
The surrounding of a pixel unit is arranged in power transmission road, i.e., there are four signal transfer circuits for the surrounding of each pixel unit, adjacent
Pixel unit can share signal transfer circuit.Therefore, there are four reset transistor Rx, source follower Sx and choosings around a pixel unit
Select pipe Rs circuit, be equivalent to 4 photodiode PD and 4 floating node FD share 1 transmission switch TG, 2 reset transistor Rx,
Source follower Sx and selecting pipe Rs circuit, signal velocity are more fast again than traditional circuit signal transmitting, improve device
Energy.
Specifically, Rx12 is connected with FD12 as shown in fig. 7, Rx11 is connected with FD11, Rx13 is connected with FD22, Rx32
It is connected with FD21, the rest may be inferred for connection type backward.When signal processing, TG11 is opened, and passes through FD11, FD12, FD22 respectively,
FD21 carries out the transfer of 4 PD charges, output signal.Then the successively switch of the TG in controlled level and vertical direction, obtains
Complete picture signal.
The area in the region cmos image sensor PD directly determines the size of full well capacity, and this patent passes through design TG inclination
Gate design, and common grid, it is possible to increase required CD line width width, and PD region area can be promoted, improve image quality.
The manufacturing method of cmos image sensor is described below with reference to Fig. 8 A to Fig. 8 P.Fig. 8 A to Fig. 8 P is shown according to this hair
The sectional view of the manufacturing process of the back-illuminated cmos image sensors of bright one embodiment.
Firstly, growing dielectric layer 801 on chip, and it is implanted into the area photodiode PD and photodiode isolation PDI
Region, as shown in Figure 8 A.Chip can be silicon wafer, be also possible to other semiconductor materials, such as silicon, germanium, GaAs, indium phosphide
Deng.The area PD is N-type lightly doped district.
Next, the mask layer SiO that regrows2802, film with good uniformity is obtained, as shown in Figure 8 B.
Next, coating photoresist PR, the techniques such as being exposed, develop keeps photoresist graphical, first performs etching to mask layer,
Then anisotropic etching is carried out by way of wet etching, chamfered edge platform groove is formed on front wafer surface, as shown in Figure 8 C.So
Photoresist and mask layer are removed afterwards.
Next, growing sacrificial layer in wafer surface, which can be SiO2, photoresist PR is coated, is exposed, shows
The techniques such as shadow keep photoresist graphical, then carry out the implantation of P-well area, as in fig. 8d.Photoresist is removed after completing the implantation of P-well area.
Next, coating photoresist PR, the techniques such as being exposed, develop keeps photoresist graphical, then carries out the implantation of the area NPD, such as
Shown in Fig. 8 E.Photoresist is removed after completing the implantation of the area NPD.
Next, coating photoresist PR, the techniques such as being exposed, develop keeps photoresist graphical, then carries out the implantation of the area FD, such as figure
Shown in 8F.Photoresist is removed after completing the implantation of the area FD.
Next, coating photoresist PR, the techniques such as being exposed, develop keeps photoresist graphical, then carries out the implantation of the area PPD, such as
Shown in Fig. 8 G.Photoresist is removed after completing the implantation of the area FD.
Next, growing thick silicon dioxide layer as etching polysilicon barrier layer, as illustrated in figure 8h.
Next, coating photoresist PR, the techniques such as being exposed, develop keeps photoresist graphical, exposed grid groove region, such as
Shown in Fig. 8 I.
Next, the oxide layer in removal grid groove region, as illustrated by figure 8j.Wet process can be used or dry etch process is gone
Except the oxide layer in grid groove region.
Next, removal photoresist, surface clean simultaneously grow gate oxide, as shown in figure 8k.
Next, growing undoped polysilicon layer, surface doping then is carried out by the way of ion implantation, such as Fig. 8 L
It is shown.
Next, coating photoresist PR, the techniques such as being exposed, develop keeps photoresist graphical, only reservation gate polycrystalline silicon area
Domain, as shown in Fig. 8 M.
Then, gate polycrystalline silicon etching is carried out, and removes remaining photoresist, as seen in fig. 8n.
Next, metallization medium layer；Then surface planarisation is carried out by the way of CMP, as shown in Fig. 8 O.The dielectric layer
It generally can be SiO2。
Next, carrying out metal connecting hole etching and hole fill process, the generally filling of W, MOCVD technique is such as schemed
Shown in 8P, external metal interconnection is formed at the grid of floating node and transmission switch.
1 transmission switch is shared in the above embodiment of the present invention with 4 photodiode PD and 4 floating node FD
It is described for TG, 2 reset transistor Rx, source follower Sx and selecting pipe Rs circuit, those skilled in the art should manage
Solution can design shared 1 transmission of N number of photodiode PD and N number of floating node FD and open in other embodiments of the invention
Close TG, M reset transistor Rx, source follower Sx and selecting pipe Rs circuit, M < N.
Although described above is various embodiments of the present invention, however, it is to be understood that they are intended only as example to present
, and without limitation.For those skilled in the relevant art it is readily apparent that various combinations, modification can be made to it
Without departing from the spirit and scope of the invention with change.Therefore, the width of the invention disclosed herein and range should not be upper
It states disclosed exemplary embodiment to be limited, and should be defined according only to the appended claims and its equivalent replacement.
Claims (10)
1. a kind of back-illuminated cmos image sensors, comprising:
N number of photodiode；
One transmission switch, the transmission switch include N number of ditch electrically isolated from one below a grid and the grid
Road area；And
N number of floating node, wherein a corresponding ditch of each of the described N number of photodiode by the transmission switch
Road area is connected to corresponding one in N number of floating node.
2. back-illuminated cmos image sensors as described in claim 1, which is characterized in that it further include N number of signal transfer circuit,
Each signal transfer circuit is connected to corresponding one in N number of floating node, and each signal transfer circuit includes:
Reset transistor, the source level of the reset transistor are connected to one end of floating node, and the reset transistor drain electrode is connected to power supply；
Source follower, the grid of the source follower are connected to the source level of reset transistor, and the source follower drain electrode is connected to power supply；
Selecting pipe, the drain electrode of the selecting pipe are connected to the source electrode of source follower, and the source electrode of the selecting pipe is output end, wherein
Transmission switch, reset transistor, selecting pipe grid be connected to external control circuit.
3. back-illuminated cmos image sensors as claimed in claim 2, which is characterized in that described when carrying out signal processing
Switch conduction is transmitted, the charge of each photodiode is shifted by corresponding floating node, in output end output signal.
4. back-illuminated cmos image sensors as described in claim 1, which is characterized in that further include being formed on front wafer surface
Chamfered edge platform groove, flushed with front wafer surface at the top of the chamfered edge platform, the topside area of the chamfered edge platform greater than bottom area,
The chamfered edge platform has N number of inclined side that bottom is extended at the top of chamfered edge platform, each inclined side by isolated groove into
The grid of row isolation, the transmission switch is formed in chamfered edge platform groove, N number of channel electrically isolated from one of the transmission switch
Area is formed on N number of inclined side of the chamfered edge platform.
5. back-illuminated cmos image sensors as claimed in claim 4, which is characterized in that each photodiode includes clamper
The N-doped zone of photodiode PPD, N-type photodiode NPD and lower section, floating node and N-type photodiode distinguish shape
At the top and bottom of the inclined side in chamfered edge platform, clamper photodiode be formed in the front face surface region of chip and with it is floating
Empty node is adjacent, and the channel region for transmitting switch is arranged between floating node and N-type photodiode.
6. a kind of back-illuminated cmos image sensors array, comprising:
According to multiple pixel units that matrix-style arranges, each pixel unit includes: 4 photodiodes；One transmission is opened
It closes, the transmission switch includes 4 channel regions electrically isolated from one below a grid and the grid；And 4 floating
Empty node, wherein corresponding channel region connection of each of described 4 photodiodes by the transmission switch
To corresponding one in 4 floating nodes；
4 signal transfer circuits are provided with around each pixel unit, each signal transfer circuit is connected to 4 floating sections
Corresponding one in point, each signal transfer circuit includes: reset transistor, and the source level of the reset transistor is connected to floating node
One end, the reset transistor drain electrode are connected to power supply；The grid of source follower, the source follower is connected to the source level of reset transistor,
The source follower drain electrode is connected to power supply；Selecting pipe, the drain electrode of the selecting pipe are connected to the source electrode of source follower, the choosing
The source electrode for selecting pipe is output end, wherein the grid of transmission switch, reset transistor, selecting pipe is connected to external control circuit.
7. back-illuminated cmos image sensors array as claimed in claim 6, which is characterized in that adjacent pixel unit shares letter
Number transmitting circuit.
8. back-illuminated cmos image sensors array as claimed in claim 6, which is characterized in that when carrying out signal processing,
The charge of the transmission switch conduction of first pixel unit, each photodiode of the first pixel unit passes through corresponding floating section
Point transfer, in output end output signal, then successively the transmission of the pixel unit in controlled level and vertical direction is switched, and is obtained
Complete picture signal.
9. a kind of manufacturing method of back-illuminated cmos image sensors, comprising:
Dielectric layer is grown on chip, and is implanted into the area photodiode PD and the photodiode isolation region PDI；
Grow mask layer；
Photoresist is coated, keeps photoresist graphical by photoetching process, first mask layer is performed etching, then by way of wet etching
Anisotropic etching is carried out, forms chamfered edge platform groove on front wafer surface；
Sacrificial layer is grown in wafer surface, carries out the implantation of P-well area；
Carry out the implantation of the area NPD；
Carry out the implantation of the area FD；
Carry out the implantation of the area PPD；
Thick silicon dioxide layer is grown as etching polysilicon barrier layer；
Photoresist is coated, keeps photoresist graphical by photoetching process, exposure grid groove region；
Remove the oxide layer in grid groove region；
Photoresist is removed, surface clean simultaneously grows gate oxide；
Undoped polysilicon layer is grown, then carries out surface doping by the way of ion implantation；
Photoresist PR is coated, keeps photoresist graphical by photoetching process, only retains the photoresist of gate polysilicon region；
Gate polycrystalline silicon etching is carried out, remaining photoresist is then removed；
Form dielectric layer；
Metal connecting hole etching and hole fill process are carried out, forms external metal at the grid of floating node and transmission switch
Interconnection.
10. the manufacturing method of back-illuminated cmos image sensors as claimed in claim 9, which is characterized in that the area FD and the area NPD
It is formed in the top and bottom of the inclined side of chamfered edge platform.
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