CN109786416A - Back side illumination image sensor and its manufacturing method - Google Patents
Back side illumination image sensor and its manufacturing method Download PDFInfo
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- CN109786416A CN109786416A CN201910226210.5A CN201910226210A CN109786416A CN 109786416 A CN109786416 A CN 109786416A CN 201910226210 A CN201910226210 A CN 201910226210A CN 109786416 A CN109786416 A CN 109786416A
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Abstract
The present invention relates to technical field of manufacturing semiconductors more particularly to a kind of back side illumination image sensor and its manufacturing methods.The back side illumination image sensor includes substrate and multiple pixel regions for being located at substrate surface and being arranged in array, and the pixel region includes dark pixel layer, light shield layer and the photosensitive pixel layer being sequentially stacked along the direction perpendicular to the substrate；The dark pixel layer is used to calibrate the dark current of the photosensitive pixel layer for generating the first electric signal, first electric signal；The light shield layer is for electrically isolating the dark pixel layer and the photosensitive pixel layer；The photosensitive pixel layer is for receiving external optical signals and being converted into the second electric signal.The present invention can expand the ratio in photosensitive pixel region, improve photoelectric conversion efficiency, improve image quality while realizing to dark current accurate alignment.
Description
Technical field
The present invention relates to technical field of manufacturing semiconductors more particularly to a kind of back side illumination image sensor and its manufacturers
Method.
Background technique
So-called imaging sensor refers to the device for converting optical signals to electric signal.It is different according to the principle of its foundation, it can
To divide into CCD (Charge Coupled Device, charge coupled cell) imaging sensor and CMOS
(Complementary Metal-Oxide Semiconductor, metal oxide semiconductor device) imaging sensor.Due to
Cmos image sensor is made of traditional cmos circuit technique, therefore can will be outer required for imaging sensor and its
It encloses circuit to be integrated, so that cmos image sensor has wider array of application prospect.
According to the difference for the position for receiving light, cmos image sensor can be divided into imaging sensor front-illuminated and back-illuminated
Formula (Back Side Illumination, BSI) imaging sensor.Wherein, compared with imaging sensor front-illuminated, back-illuminated type figure
As being exactly to change the structure inside element in place of the maximum optimization of sensor, i.e., the element input path of photosensitive layer is turned
Light can be entered from back side direct projection, avoids in imaging sensor front-illuminated, light will receive lenticule and photoelectricity for direction
The influence of structure and thickness between diode, improves the efficiency of light receiver.CMOS back side illumination image sensor has work
Skill is simple, be easy to integrated other devices, small in size, light-weight, small power consumption and it is at low cost the advantages that.Therefore, with image sensing
The development of technology, CMOS back side illumination image sensor replace CCD back side illumination image sensor to be applied to all kinds of electricity more and more
In sub- product.Currently, CMOS back side illumination image sensor has been widely used for static digital camera, DV, medical treatment
With photographic device and automobile-used photographic device etc..
The signal accurately exported on each pixel for expressing light absolutely power is back side illumination image sensor
One key index.But the presence of dark current will affect the image quality of imaging sensor, especially low irradiance image
Resolution ratio and contrast also will affect the dynamic range of image device.It in order to solve this problem, is currently mostly using in picture
Photosensitive pixel part and dark pixel part is arranged simultaneously in plain region, the calibration dark current signals generated by means of dark pixel part
The dark current component of photosensitive pixel part is eliminated, to realize the calibration to dark current.
But current photosensitive pixel part is to be arranged in pixel region along the direction of parallel substrate with dark pixel part, because
And cause in pixel region of the same area, area ratio shared by photosensitive pixel part reduces, and reduces photoelectric conversion
Efficiency has seriously affected picture quality.Therefore, real how while increasing pixel region photosensitive pixel area ratio
Now to the real time calibration of image, improves image displaying quality, be a technical problem to be solved urgently.
Summary of the invention
The present invention provides a kind of back side illumination image sensor and its manufacturing method, passes for solving existing back side illumination image
The problem of photosensitive pixel area reduces caused by setting of the sensor because dark pixel part is arranged, to improve light utilization
Rate improves image displaying quality.
To solve the above-mentioned problems, the present invention provides a kind of back side illumination image sensor, including substrate and it is located at lining
Bottom surface and the multiple pixel regions being arranged in array, the pixel region include successively folding along the direction perpendicular to the substrate
Dark pixel layer, light shield layer and the photosensitive pixel layer set；
The dark pixel layer is for generating the first electric signal, and first electric signal is for calibrating the photosensitive pixel layer
Dark current；
The light shield layer is for electrically isolating the dark pixel layer and the photosensitive pixel layer；
The photosensitive pixel layer is for receiving external optical signals and being converted into the second electric signal.
Preferably, the pixel region includes:
Accumulation layer between the substrate and the dark pixel layer, the accumulation layer includes floating diffusion region；
First transmission channel is electrically connected the dark pixel layer and the floating diffusion region, is used for first electric signal
It is transmitted to the floating diffusion region；
Second transmission channel is electrically connected the photosensitive pixel layer and the floating diffusion region, is used for second telecommunications
Number it is transmitted to the floating diffusion region.
Preferably, the light shield layer includes:
The first metal layer；
The first medium layer of the first metal layer is coated, the first medium layer is for electrically isolating the dark pixel layer
With the first metal layer and the photosensitive pixel layer and the first metal layer.
Preferably, the pixel region includes multiple pixel units；
Adjacent pixel unit, which passes through, runs through the dark pixel layer, the light shield layer and institute along the direction perpendicular to the substrate
The isolation grid structure for stating photosensitive pixel layer is mutually isolated.
Preferably, the isolation grid structure includes:
Second metal layer；
The second dielectric layer of the second metal layer is coated, the second dielectric layer electrically isolates the dark pixel layer and institute
State second metal layer and the photosensitive pixel layer and the second metal layer.
To solve the above-mentioned problems, the present invention also provides a kind of manufacturing methods of back side illumination image sensor, including such as
Lower step:
One substrate is provided；
The multiple pixel regions being arranged in array are formed in the substrate surface, the pixel region includes along perpendicular to institute
State dark pixel layer, light shield layer and photosensitive pixel layer that the direction of substrate is sequentially stacked；The dark pixel layer is for generating the first electricity
Signal, first electric signal are used to calibrate the dark current of the photosensitive pixel layer, and the light shield layer is described for electrically isolating
Dark pixel layer and the photosensitive pixel layer, the photosensitive pixel layer is for receiving external optical signals and being converted into the second telecommunications
Number.
Preferably, form the multiple pixel regions being arranged in array includes: in the specific steps of the substrate surface
Form accumulation layer, dark pixel layer, sacrificial layer and the photosensitive pixel being sequentially stacked along the direction perpendicular to the substrate
Layer in the substrate surface, the accumulation layer includes floating diffusion region, the dark pixel layer by the first transmission channel with it is described
Floating diffusion region electrical connection, the photosensitive pixel layer are electrically connected by the second transmission channel with the floating diffusion region；
The sacrificial layer is removed, the cavity between the dark pixel layer and the photosensitive pixel layer is formed；
First medium layer material is deposited in the cavity, forms the first medium layer for being covered in the cavity sidewalls surface；
First metal layer material is deposited in the cavity, formation is covered in the first medium layer surface and filling is full described
The first metal layer of cavity.
Preferably, the pixel region includes multiple pixel units；Removing the sacrificial layer further includes before following steps:
It is formed and sequentially passes through the photosensitive pixel layer, the sacrificial layer and described photosensitive along the direction perpendicular to the substrate
The groove of pixel layer；
Second medium layer material is deposited along the groove, forms the second dielectric layer for covering the recess sidewall surface；
Along the groove depositing second metal layer material, formation is covered in the second medium layer surface and filling is full described
The second metal layer of groove.
Preferably, the specific steps for removing the sacrificial layer include:
Photosensitive pixel layer described in etched portions forms the opening of sacrificial layer described in expose portion；
The sacrificial layer is etched along the opening, forms the cavity.
Preferably, the material of the sacrificial layer is SiGe.
Back side illumination image sensor provided by the invention and its manufacturing method will be used to generate the dark picture of calibration dark current
Plain layer is stacked with the photosensitive pixel layer for receiving external optical signals along the direction perpendicular to substrate, compared to the prior art
In horizontally disposed mode, the present invention realize to dark current accurate alignment while, the ratio in photosensitive pixel region can be expanded
Example, improves photoelectric conversion efficiency；In addition, the setting of light shield layer, avoids mutual between dark pixel layer and shading pixel layer
Interference, improves the image quality of back side illumination image sensor.
Detailed description of the invention
Attached drawing 1 is the structural schematic diagram of back side illumination image sensor in the specific embodiment of the invention；
Attached drawing 2 is the manufacturing method flow chart of back side illumination image sensor in the specific embodiment of the invention；
Attached drawing 3A-3J is the specific embodiment of the invention main technique during manufacturing back side illumination image sensor
Schematic cross-section.
Specific embodiment
With reference to the accompanying drawing to the specific embodiment of back side illumination image sensor provided by the invention and its manufacturing method
It elaborates.
Present embodiment provides a kind of back side illumination image sensor, and attached drawing 1 is in the specific embodiment of the invention
The structural schematic diagram of back side illumination image sensor.As shown in Figure 1, the back side illumination image sensor packet that present embodiment provides
Include substrate 10 and positioned at 10 surface of substrate and multiple pixel regions for being arranged in array, the pixel region include along perpendicular to
Dark pixel layer 11, light shield layer 12 and the photosensitive pixel layer 13 that the direction of the substrate 10 is sequentially stacked；
The dark pixel layer 11 is for generating the first electric signal, and first electric signal is for calibrating the photosensitive pixel layer
13 dark current；
The light shield layer 12 is for electrically isolating the dark pixel layer 11 and the photosensitive pixel layer 13；
The photosensitive pixel layer 13 is for receiving external optical signals and being converted into the second electric signal.
Specifically, the pixel region includes multiple pixel units, such as red pixel cell R, green pixel cell
G, blue pixel cells B, multiple in white pixel unit, present embodiment includes three pixels with the pixel region
It is illustrated for unit, i.e. green pixel cell G, red pixel cell R and blue pixel cells B.The dark pixel layer 11
In have and three one-to-one three first sensor devices 111 of pixel unit；Correspondingly, the photosensitive pixel layer 13
In have and three one-to-one three second sensor devices 131 of pixel unit.First sensor devices 111 are used for
Under the control of extraneous control signal, first electric signal is generated, it is photosensitive to eliminate or offset corresponding described second
Dark current component in device 131 improves dark current to complete the real time calibration of dark current inside the pixel unit
The accuracy of calibration.Meanwhile in present embodiment, in same pixel unit, the second sensor devices 131 are along perpendicular to institute
The direction for stating substrate 10 is stacked and placed on first sensor devices 111, i.e., in same pixel region, the photosensitive pixel layer
13 are stacked and placed on the dark pixel layer 11 along the direction perpendicular to the substrate 10, increase photosensitive pixel part in entire picture
Shared area ratio, improves photoelectric conversion efficiency, improves the image quality of back side illumination image sensor in plain region.
It further include that photosensitive transmission transistor, photosensitive reset transistor and photosensitive source follow crystal in the photosensitive pixel layer 13
Pipe；The dark pixel layer 11 further includes shading transmission transistor, shading reset transistor and shading follow transistor.The sense
Light pixel layer 13 and the dark pixel layer 11 use identical voltage and timing control, and what the photosensitive pixel layer 13 generated has light
No light conditions current signal that environment current signal (i.e. described second electric signal) and the dark pixel layer 11 generate (i.e. described the
One electric signal) be linked into the both ends of subtraction circuit in the pixel region simultaneously, come realize it is described have luminous environment electric signal and
Subtraction and dark current calibration between no light conditions electric signal.It is carried out secretly in present embodiment by setting dark pixel
The specific control method of correcting current, it is same as the prior art, it repeats no more again.
As shown in Figure 1, the pixel region further includes the filter layer 14 being covered on the photosensitive layer and is covered in institute
State the microlens layer on filter layer 14.It include the green filter in the green pixel cell G in the filter layer 14
Piece 141, the Red lightscreening plate 142 in the red pixel cell R and the blue filter in the blue pixel cells
Mating plate 143；Include in the microlens layer and one-to-one three lenticules 141 of three pixel units.Ambient is successively
The photosensitive pixel layer 13 is injected, and completes light in the photosensitive pixel layer 13 for lens jacket, the filter layer 14 through described
Conversion of the signal to the second electric signal.
First sensor devices 111 and second sensor devices 131 in present embodiment can be light
Electric diode, and the size relative size of first sensor devices 111 and second sensor devices 131, art technology
Personnel can select according to actual needs.
Preferably, the pixel region includes:
Accumulation layer 15 between the substrate 10 and the dark pixel layer 11, the accumulation layer 15 include floating diffusion
Area 151；
First transmission channel 171 is electrically connected the dark pixel layer 11 and the floating diffusion region 151, for by described the
One electric signal transmission is to the floating diffusion region 151；
Second transmission channel 172 is electrically connected the photosensitive pixel layer 13 and the floating diffusion region 151, and being used for will be described
Second electric signal transmission is to the floating diffusion region 151.
Specifically, the back side illumination image sensor further includes the gold between the accumulation layer 15 and the substrate
Belong to interconnection layer 16.The accumulation layer 15 has and multiple pixel units multiple storage regions correspondingly, each storage
It include that there is the floating diffusion region 151, source electrode, the transistor of drain electrode and first transmission channel 171 in region.It is described
First transmission channel 171 is located in the accumulation layer 15.First sensor devices 111 in each pixel unit pass through
The transmission of first transmission channel 171 and transistor in respective memory regions, stores to the floating diffusion region.Described second
Transmission channel 172 sequentially passes through the light shield layer 12, the dark pixel layer 11 until prolonging along the direction perpendicular to the substrate 10
It extends in the accumulation layer 15, to be electrically connected with the transistor in the accumulation layer 15.
In order to avoid second transmission channel 172 is during transmitting the second electric signal, by the light shield layer 12
With the influence of the dark pixel layer 11, it is preferred that first transmission channel 172 includes conductive layer and is covered in the conductive layer
The insulating layer of sidewall surfaces electrically isolates the conductive layer and the light shield layer 12 and the conduction by the insulating layer
Layer and the dark pixel layer 11.Wherein, the material of the conductive layer is preferably tungsten.Further, it is also possible in the conductive layer and institute
State the diffusion barrier layer that setting is constituted using Ti TiN material between insulating layer.The material of the insulating layer can be oxidation
Object material (such as silica) or nitride material (such as silicon nitride).
Preferably, the light shield layer 12 includes:
The first metal layer 122；
The first medium layer 121 of the first metal layer is coated, the first medium layer 121 is described dark for electrically isolating
Pixel layer 11 and the first metal layer 122 and the photosensitive pixel layer 13 and the first metal layer 122.
Specifically, the light shield layer 12 including the first medium layer 121 and is located in the first medium layer 121
In the first metal layer 122.The setting of the first metal layer 122, on the one hand can be enhanced the reflecting properties of light, mentions
The utilization rate of high 13 light of photosensitive pixel layer；On the other hand, the sense can be effectively isolated in the first metal layer 122
Light pixel layer 13 and the dark pixel layer 11, realize effective shading to the dark pixel layer 11；In addition, the first medium
The setting of layer 121, also achieve the dark pixel layer 11 and the first metal layer 122, the photosensitive pixel layer 13 with it is described
Being electrically insulated between the first metal layer 122.The material of the first metal layer 122 is preferably tungsten.The first medium layer 121
Material can be oxide material (such as silica) or nitride material (such as silicon nitride).In order to enhance the screening
The screening effect of photosphere 12, can also be arranged between the first medium layer 121 and the first metal layer 122 Ti or
The anti-reflecting layer that TiN material is constituted.
Preferably, the pixel region includes multiple pixel units；
Adjacent pixel unit, which passes through, runs through the dark pixel layer 11, the light shield layer along the direction perpendicular to the substrate 10
12 and the photosensitive pixel layer 13 isolation grid structure 18 it is mutually isolated.
It is furthermore preferred that the isolation grid structure 18 includes:
Second metal layer；
Coat the second dielectric layer of the second metal layer, the second dielectric layer electrically isolate the dark pixel layer 11 with
The second metal layer and the photosensitive pixel layer 13 and the second metal layer.
Specifically, the isolation grid structure 18 runs through the filter layer 14, institute along the direction perpendicular to the substrate 10
Photosensitive pixel layer 13, the light shield layer 12, the dark pixel layer 11 are stated until extending to 10 surface of substrate.The isolated gate
Structure 18 includes second dielectric layer and the second metal layer being located in the second dielectric layer.Due to second gold medal
The high reflectivity and opaqueness for belonging to layer, can isolate adjacent pixel unit, avoid the crosstalk between adjacent pixel unit, from
And effectively increase picture quality.The material of the second metal layer is preferably tungsten.The material of the second dielectric layer can be
Oxide material (such as silica) or nitride material (such as silicon nitride).In order to enhance the isolation grid structure 18
The anti-of Ti TiN material composition can also be arranged in isolation effect between the second dielectric layer and the second metal layer
Reflecting layer.
Moreover, present embodiment additionally provides a kind of manufacturing method of back side illumination image sensor, and attached drawing 2 is
The manufacturing method flow chart of back side illumination image sensor in the specific embodiment of the invention, attached drawing 3A-3J are of the invention specific real
Mode main technique schematic cross-section during manufacturing back side illumination image sensor is applied, present embodiment manufacture
The structure of back side illumination image sensor can be found in Fig. 1.As shown in Figure 1, Figure 2 and shown in Fig. 3 A- Fig. 3 J, what present embodiment provided
The manufacturing method of back side illumination image sensor includes the following steps:
Step S21 provides a substrate 10；
Step S22 forms the multiple pixel regions being arranged in array in 10 surface of substrate, and the pixel region includes
Dark pixel layer 11, light shield layer 12 and the photosensitive pixel layer 13 being sequentially stacked along the direction perpendicular to the substrate 10；The dark picture
For plain layer 11 for generating the first electric signal, first electric signal is used to calibrate the dark current of the photosensitive pixel layer 13, described
Light shield layer 12 is for electrically isolating the dark pixel layer 11 and the photosensitive pixel layer 13, and the photosensitive pixel layer 13 is for receiving
External optical signals are simultaneously converted into the second electric signal.
Preferably, forming specific steps of the multiple pixel regions being arranged in array in 10 surface of substrate includes:
Form the accumulation layer 15 being sequentially stacked along the direction perpendicular to the substrate 10, dark pixel layer 11,31 and of sacrificial layer
Photosensitive pixel layer 13 includes floating diffusion region 151 in 10 surface of substrate, the accumulation layer 15, and the dark pixel layer 11 passes through
First transmission channel 171 is electrically connected with the floating diffusion region 151, and the photosensitive pixel layer 13 passes through the second transmission channel 172
It is electrically connected with the floating diffusion region 151, as shown in Figure 3 C；
The sacrificial layer 31 is removed, the cavity between the dark pixel layer 11 and the photosensitive pixel layer 13 is formed
36, as shown in Figure 3 G；
First medium layer material is deposited in the cavity 36, forms the first medium for being covered in 36 sidewall surfaces of cavity
Layer 121；
First metal layer material is deposited in the cavity 36, formation is covered in 121 surface of first medium layer and filling
The first metal layer 122 of the full cavity 36, as shown in Fig. 3 H, Fig. 3 I, Fig. 3 I is the overlooking structure diagram of Fig. 3 H.
Specifically, the specific steps for forming structure as shown in Figure 3 C include: firstly, provide a support substrate 30, and
The photosensitive pixel layer 13, the sacrificial layer 31, the dark pixel layer being sequentially stacked are formed in 30 surface of support substrate
11 and accumulation layer 15 (for example, by using single crystal silicon material formed accumulation layer)；Then, using photoetching, etching technics, second is formed
Through-hole is transmitted, it is straight that the second transmission through-hole sequentially passes through the device substrate layer, the dark pixel layer 11, the sacrificial layer 31
Deviate from the surface of the support substrate 30 to the photosensitive pixel layer 13；Then, along the second transmission through-hole depositing insulating layer
Material forms the insulating layer for being covered in the second transmission through-hole side wall and bottom wall surface；Next, being covered in removal described
The insulating layer of second transmission through-hole bottom wall surface is sequentially depositing Ti or TiN after opening the bottom that described second transmits through-hole
Material, conductive form second transmission channel 172, as shown in Figure 3A in the second transmission through-hole.Later,
Being formed in the accumulation layer 15 has floating diffusion region 151, first transmission channel 171, the first fleet plough groove isolation structure
32 and second fleet plough groove isolation structure 33, as shown in Figure 3B.Wherein, first fleet plough groove isolation structure 32 is adjacent for being isolated
Transistor, second fleet plough groove isolation structure 33 for it is subsequent limit isolation grid structure position.In this specific embodiment party
In formula, first transmission channel 171 and the floating diffusion region 151 can using identical technique synchronize formed, such as adopt
It is synchronized to be formed with ion implantation procedure.Metal interconnecting layer 16 is formed away from the surface of the support substrate 30 in the accumulation layer 15
Later, it is bonded the metal interconnecting layer 16 and the substrate 10, finally overturns semiconductor structure and removing that above-mentioned steps are formed
The support substrate 30, obtains structure as shown in Figure 3 C.
Preferably, the material of the sacrificial layer 31 is SiGe.
Preferably, the pixel region includes multiple pixel units；Removing the sacrificial layer 31 further includes before walking as follows
It is rapid:
It is formed and sequentially passes through the photosensitive pixel layer 13, the sacrificial layer 12 and institute along the direction perpendicular to the substrate 10
State the groove of dark pixel layer 11；
Second medium layer material is deposited along the groove, forms the second dielectric layer for covering the recess sidewall surface；
Along the groove depositing second metal layer material, formation is covered in the second medium layer surface and filling is full described
The second metal layer of groove.
Specifically, it after obtaining structure as shown in Figure 3 C, is covered on the photosensitive pixel layer firstly, being formed
Hard mask layer 35, etch the photosensitive pixel layer 13, the sacrificial layer 12 and the dark pixel layer 11, formed along perpendicular to institute
The direction for stating substrate 10 extends to the groove on 33 surface of the second fleet plough groove isolation structure；Then, using atomic layer deposition
Product technique sequentially forms the Ti for being covered in the second dielectric layer of the groove surfaces, being covered in the second medium layer surface
Material layer or TiN material layer, the second metal layer for being covered in the Ti material layer or TiN material surface are formed
Grid structure 18 is isolated, as shown in Figure 3D.The pixel region is divided into multiple mutually independent pictures by the isolation grid structure 18
Plain unit.
Preferably, the specific steps for removing the sacrificial layer 31 include:
Photosensitive pixel layer 13 described in etched portions forms the opening of sacrificial layer 31 described in expose portion；
The sacrificial layer 31 is etched along the opening, forms the cavity 36, as shown in Figure 3 G.
Fig. 3 E is the overlooking structure diagram of Fig. 3 D.Specifically, in the obtained structure as shown in Fig. 3 D, Fig. 3 E,
The isolation grid structure 18 extends along the y axis, is still mask with the hard mask layer 35, on 35 surface of hard mask layer
Photoresist is coated, and defines the position of the opening in the photoresist.Later, the etching removal of the first etching technics is first passed through
The part photosensitive pixel layer 13, forms the opening extended along the x axis in Yu Suoshu photosensitive pixel layer 13, described in expose portion
Sacrificial layer 31；Then, the second etching technics (such as dry etch process) is carried out along the opening, removes the exposed sacrifice
31 part of layer, and dark pixel layer 11 described in expose portion, as illustrated in Figure 3 F；Finally, carrying out third etching industry along the opening
With (such as wet-etching technology), the entire sacrificial layer 31 is removed, forms the cavity 36, as shown in Figure 3 G.
After forming the structure as shown in Fig. 3 H, Fig. 3 I, the hard mask layer 25 is removed, being formed includes green color filter
141, the filter layer 14 of Red lightscreening plate 142 and blue color filter 143；It is formed and multiple pictures in 14 surface of filter layer later
Plain unit multiple lenticules 191 correspondingly constitute lens jacket.
The back side illumination image sensor and its manufacturing method that present embodiment provides will be used to generate calibration with dark electricity
The dark pixel layer of stream is stacked with the photosensitive pixel layer for receiving external optical signals along the direction perpendicular to substrate, compared to
Horizontally disposed mode in the prior art, the present invention can expand photosensitive pixel while realizing to dark current accurate alignment
The ratio in region, improves photoelectric conversion efficiency；In addition, the setting of light shield layer, avoid dark pixel layer and shading pixel layer it
Between interfere with each other, improve the image quality of back side illumination image sensor.
The above is only a preferred embodiment of the present invention, it is noted that for the ordinary skill people of the art
Member, various improvements and modifications may be made without departing from the principle of the present invention, these improvements and modifications also should be regarded as
Protection scope of the present invention.
Claims (10)
1. a kind of back side illumination image sensor, which is characterized in that including substrate and be located at substrate surface and be arranged in array
Multiple pixel regions, the pixel region include dark pixel layer, the light shield layer being sequentially stacked along the direction perpendicular to the substrate
With photosensitive pixel layer；
The dark pixel layer is used to calibrate the dark electricity of the photosensitive pixel layer for generating the first electric signal, first electric signal
Stream；
The light shield layer is for electrically isolating the dark pixel layer and the photosensitive pixel layer；
The photosensitive pixel layer is for receiving external optical signals and being converted into the second electric signal.
2. back side illumination image sensor according to claim 1, which is characterized in that the pixel region includes:
Accumulation layer between the substrate and the dark pixel layer, the accumulation layer includes floating diffusion region；
First transmission channel is electrically connected the dark pixel layer and the floating diffusion region, is used for first electric signal transmission
To the floating diffusion region；
Second transmission channel is electrically connected the photosensitive pixel layer and the floating diffusion region, for passing second electric signal
Transport to the floating diffusion region.
3. back side illumination image sensor according to claim 1, which is characterized in that the light shield layer includes: the first metal
Layer；
The first medium layer of the first metal layer is coated, the first medium layer is for electrically isolating the dark pixel layer and institute
State the first metal layer and the photosensitive pixel layer and the first metal layer.
4. back side illumination image sensor according to claim 1, which is characterized in that the pixel region includes multiple pixels
Unit；
Adjacent pixel unit, which passes through, runs through the dark pixel layer, the light shield layer and the sense along the direction perpendicular to the substrate
The isolation grid structure of light pixel layer is mutually isolated.
5. back side illumination image sensor according to claim 4, which is characterized in that the isolation grid structure includes:
Second metal layer；
Coat the second dielectric layer of the second metal layer, the second dielectric layer electrically isolates the dark pixel layer and described the
Two metal layers and the photosensitive pixel layer and the second metal layer.
6. a kind of manufacturing method of back side illumination image sensor, which comprises the steps of:
One substrate is provided；
The multiple pixel regions being arranged in array are formed in the substrate surface, the pixel region includes along perpendicular to the lining
Dark pixel layer, light shield layer and the photosensitive pixel layer that the direction at bottom is sequentially stacked；The dark pixel layer is used to generate the first electric signal,
First electric signal is used to calibrate the dark current of the photosensitive pixel layer, and the light shield layer is for electrically isolating the dark pixel
Layer and the photosensitive pixel layer, the photosensitive pixel layer is for receiving external optical signals and being converted into the second electric signal.
7. the manufacturing method of back side illumination image sensor according to claim 6, which is characterized in that formation is arranged in array
Multiple pixel regions include: in the specific steps of the substrate surface
Formed along the direction accumulation layer, dark pixel layer, sacrificial layer and the photosensitive pixel layer that are sequentially stacked perpendicular to the substrate in
The substrate surface, the accumulation layer include floating diffusion region, the dark pixel layer by the first transmission channel with it is described floating
Diffusion region electrical connection, the photosensitive pixel layer are electrically connected by the second transmission channel with the floating diffusion region；
The sacrificial layer is removed, the cavity between the dark pixel layer and the photosensitive pixel layer is formed；
First medium layer material is deposited in the cavity, forms the first medium layer for being covered in the cavity sidewalls surface；
First metal layer material is deposited in the cavity, formation is covered in the first medium layer surface and fills the full cavity
The first metal layer.
8. the manufacturing method of back side illumination image sensor according to claim 7, which is characterized in that the pixel region packet
Include multiple pixel units；Removing the sacrificial layer further includes before following steps:
It is formed and sequentially passes through the photosensitive pixel layer, the sacrificial layer and the photosensitive pixel along the direction perpendicular to the substrate
The groove of layer；
Second medium layer material is deposited along the groove, forms the second dielectric layer for covering the recess sidewall surface；
Along the groove depositing second metal layer material, formation is covered in the second medium layer surface and fills the full groove
Second metal layer.
9. the manufacturing method of back side illumination image sensor according to claim 7, which is characterized in that remove the sacrificial layer
Specific steps include:
Photosensitive pixel layer described in etched portions forms the opening of sacrificial layer described in expose portion；
The sacrificial layer is etched along the opening, forms the cavity.
10. the manufacturing method of back side illumination image sensor according to claim 6, which is characterized in that the sacrificial layer
Material is SiGe.
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| CN110545388A (en) * | 2019-08-28 | 2019-12-06 | 上海集成电路研发中心有限公司 | Device and method for removing image dark current |
| CN112002717A (en) * | 2020-07-31 | 2020-11-27 | 深圳奥比中光科技有限公司 | Image sensor pixel array structure and manufacturing method |
| CN112530983A (en) * | 2019-09-18 | 2021-03-19 | 力晶积成电子制造股份有限公司 | Image sensor |
| CN113471226A (en) * | 2020-03-31 | 2021-10-01 | 比亚迪半导体股份有限公司 | Image sensor and electronic equipment |
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| CN112002717A (en) * | 2020-07-31 | 2020-11-27 | 深圳奥比中光科技有限公司 | Image sensor pixel array structure and manufacturing method |
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