CN110211980A - A kind of imaging sensor and preparation method thereof - Google Patents
A kind of imaging sensor and preparation method thereof Download PDFInfo
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- CN110211980A CN110211980A CN201910500462.2A CN201910500462A CN110211980A CN 110211980 A CN110211980 A CN 110211980A CN 201910500462 A CN201910500462 A CN 201910500462A CN 110211980 A CN110211980 A CN 110211980A
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Classifications
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L27/00—Devices consisting of a plurality of semiconductor or other solid-state components formed in or on a common substrate
- H01L27/14—Devices consisting of a plurality of semiconductor or other solid-state components formed in or on a common substrate including semiconductor components sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation
- H01L27/144—Devices controlled by radiation
- H01L27/146—Imager structures
- H01L27/14601—Structural or functional details thereof
- H01L27/14603—Special geometry or disposition of pixel-elements, address-lines or gate-electrodes
- H01L27/14605—Structural or functional details relating to the position of the pixel elements, e.g. smaller pixel elements in the center of the imager compared to pixel elements at the periphery
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L27/00—Devices consisting of a plurality of semiconductor or other solid-state components formed in or on a common substrate
- H01L27/14—Devices consisting of a plurality of semiconductor or other solid-state components formed in or on a common substrate including semiconductor components sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation
- H01L27/144—Devices controlled by radiation
- H01L27/146—Imager structures
- H01L27/14601—Structural or functional details thereof
- H01L27/14609—Pixel-elements with integrated switching, control, storage or amplification elements
- H01L27/1461—Pixel-elements with integrated switching, control, storage or amplification elements characterised by the photosensitive area
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L27/00—Devices consisting of a plurality of semiconductor or other solid-state components formed in or on a common substrate
- H01L27/14—Devices consisting of a plurality of semiconductor or other solid-state components formed in or on a common substrate including semiconductor components sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation
- H01L27/144—Devices controlled by radiation
- H01L27/146—Imager structures
- H01L27/14601—Structural or functional details thereof
- H01L27/14609—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
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L27/00—Devices consisting of a plurality of semiconductor or other solid-state components formed in or on a common substrate
- H01L27/14—Devices consisting of a plurality of semiconductor or other solid-state components formed in or on a common substrate including semiconductor components sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation
- H01L27/144—Devices controlled by radiation
- H01L27/146—Imager structures
- H01L27/14683—Processes or apparatus peculiar to the manufacture or treatment of these devices or parts thereof
- H01L27/14687—Wafer level processing
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Abstract
This application involves a kind of imaging sensors and preparation method thereof.Described image sensor includes: semiconductor substrate；Epitaxial layer is located at the semiconductor substrate surface；Photosensitive element, the photosensitive element include that the first photosensitive element being located in the semiconductor substrate and the second photosensitive element in the epitaxial layer, second photosensitive element extend to the first photosensitive element.The application passes through grown epitaxial layer on a semiconductor substrate, and the first photosensitive element and the second photosensitive element are formed in semiconductor substrate and epitaxial layer respectively, avoid single production photosensitive element by technique limited, increase the longitudinal size of photosensitive element, the full-well capacity of each pixel unit is improved, on the other hand, the transistor of image sensor pixel cells is formed on epitaxial layer, the lateral dimension of photosensitive element is increased, the full-well capacity of each pixel unit is improved.
Description
Technical field
This application involves the manufacturing fields of semiconductor devices, more particularly to a kind of imaging sensor and preparation method thereof.
Background technique
Imaging sensor is a kind of device that optical imagery is converted into electric signal.With the hair of computer and communications industry
Exhibition, the demand to high-performance image sensors constantly increase, these high-performance image sensors are widely used in such as Digital photographic
The various necks of machine, camcorders, PCS Personal Communications System (PCS), game machine, security monitoring video camera, medical miniature camera etc
Domain.
In the development field of current imaging sensor, the factor for determining its advantage is mainly the quantity of pixel and each
The full-well capacity of pixel, how to improve the full-well capacity of single pixel is the direction highly studied.Expire in current
In the raising scheme of trap capacity, the face for expanding the side junction capacity of single pixel is mainly reached by raising ion implantation energy
Product is to improve full-well capacity, but this scheme is largely limited by ion implantation energy.On the other hand, some
In technological design, usually the 4T transistor of pixel unit is made in the isolated area between photosensitive element, the pass of such isolated area
Key size is necessarily done bigger, and the lateral dimension of photosensitive element can have been tied up, and is influenced the light-receiving area of photosensitive element, is unfavorable for
Promote full-well capacity.
It is therefore desirable to develop new imaging sensor of one kind and preparation method thereof in view of the above problems to hold to improve full trap
Amount.
Summary of the invention
The promotion that the application limits single pixel unit full-well capacity for ion implantation energy in the prior art is asked
Topic provides a kind of imaging sensor and preparation method thereof, and the full-well capacity of each pixel unit in imaging sensor can be improved.
The one aspect of the application provides a kind of imaging sensor, comprising: semiconductor substrate；Epitaxial layer is located at described half
Conductor substrate surface；Photosensitive element, the photosensitive element include the first photosensitive element in the semiconductor substrate and
The second photosensitive element in the epitaxial layer, second photosensitive element extend to the first photosensitive element；Isolation structure, institute
Isolation structure is stated for the photosensitive element to be isolated, including the first isolation structure being located in the semiconductor substrate and is located at institute
The second isolation structure in epitaxial layer is stated, second isolation structure extends to first isolation structure.
In some embodiments of the present application, described image sensor further include: floating diffusion region is located at the epitaxial layer
In；The transistor of described image sensor pixel unit is located on the epitaxial layer.
In some embodiments of the present application, the transistor of described image sensor pixel unit is four transistor pixels lists
Member.
In some embodiments of the present application, first photosensitive element with a thickness of 2 to 3.5 microns.
In some embodiments of the present application, the thickness of second photosensitive element is less than 3 microns.
Further aspect of the application provides a kind of production method of imaging sensor, comprising: semiconductor substrate is provided,
The first photosensitive element and the first isolation structure for first photosensitive element to be isolated are formed in the semiconductor substrate；?
The semiconductor substrate surface forms epitaxial layer；The second photosensitive element is formed in the epitaxial layer and for being isolated described
Second isolation structure of two photosensitive elements, wherein second photosensitive element extends to the first photosensitive element, second isolation
Structure extends to first isolation structure.
In some embodiments of the present application, the method also includes: in the epitaxial layer floating diffusion region is formed,
The transistor of described image sensor pixel unit is formed on the epitaxial layer.
In some embodiments of the present application, the method for forming first photosensitive element includes: to serve as a contrast in the semiconductor
The first ion implanting is carried out in bottom.
In some embodiments of the present application, the method for forming second photosensitive element includes: in the epitaxial layer
Carry out the second ion implanting, wherein the first ion implanting is identical with the injection ionic type of the second ion implanting.
In some embodiments of the present application, after carrying out the second ion implanting in the epitaxial layer, annealing.
In some embodiments of the present application, first photosensitive element with a thickness of 2 to 3.5 microns.
In some embodiments of the present application, the thickness of second photosensitive element is less than 3 microns.
A kind of imaging sensor provided by the present application and preparation method thereof, it is described by growing on the semiconductor substrate
Epitaxial layer, and first photosensitive element and second sense are formed in the semiconductor substrate and the epitaxial layer respectively
Optical element, avoid single production photosensitive element by technique limited, moreover, by first photosensitive element and described second
Photosensitive element collectively forms the photosensitive element of described image sensor, increases the longitudinal size of the photosensitive element, improves
The full-well capacity of each pixel unit.On the other hand, the transistor of the described image sensor pixel unit is formed in institute
It states on epitaxial layer, increases the lateral dimension of the photosensitive element, improve the full-well capacity of each pixel unit.
Detailed description of the invention
Exemplary embodiment disclosed in this application is described in detail in the following drawings.Wherein identical appended drawing reference is in attached drawing
Several views in indicate similar structure.Those of ordinary skill in the art will be understood that these embodiments be non-limiting,
Exemplary embodiment, the purpose that attached drawing is merely to illustrate and describes, it is no intended to it limits the scope of the present disclosure, other modes
Embodiment may also similarly complete the intention of the invention in the application.It should be appreciated that the drawings are not drawn to scale.Wherein:
Fig. 1 is a kind of circuit diagram of imaging sensor of the embodiment of the present application.
Fig. 2 to Fig. 8 is the cross section structure schematic diagram of each step of imaging sensor production method in the embodiment of the present application.
Fig. 9 (a) and Fig. 9 (b) is the structural schematic diagram and a kind of prior art diagram of the embodiment of the present application imaging sensor
As the comparison of the structural schematic diagram of sensor.
Specific embodiment
Following description provides the specific application scene of the application and requirements, it is therefore an objective to those skilled in the art be enable to make
It makes and using the content in the application.To those skilled in the art, to the various partial modifications of the disclosed embodiments
Be it will be apparent that and without departing from the spirit and scope of the disclosure, the General Principle that will can be defined here
Applied to other embodiments and application.Therefore, the embodiment the present disclosure is not limited to shown in, but it is consistent most wide with claim
Range.
Technical solution of the present invention is described in detail below with reference to embodiment and attached drawing.
The embodiment of the present application provides a kind of imaging sensor, is a kind of electricity of cmos image sensor with reference to shown in attached drawing 1
Lu Tu, more specifically, the circuit diagram of four transistor pixel cells (4T pixel) for described image sensor.The electricity
Road includes: photodiode (Photodiode) PD, transmission transistor (Transfer Gate) Tx, floating diffusion region FD
(Floating Diffusion), reset transistor (Reset Gate) Rx, source follower Sx (Source Follower),
And row gate tube Rs (Row Selector).Wherein, the photodiode PD can absorb after receiving light irradiation
The light of the photodiode is incident on to generate optical charge.The transmission transistor Tx will be from the optical charge of photodiode PD
It is transferred to floating diffusion region FD.Reset transistor Rx can control optical charge for resetting the floating diffusion region FD
It is mobile.Source follower Sx amplifies and buffers for realizing to signal, for improving the noise problem of dot structure.
When circuit shown in attached drawing 1 works, the photodiode PD starts to generate optical charge, and reset transistor Rx is opened,
The floating diffusion region FD is reset to high level, row gate tube Rs is opened, at this time via source follower Sx Hyblid Buffer Amplifier after
Pixel read-out voltage is resetting voltage, is denoted as Vblk.Then, transmission transistor Tx is opened, optical charge starts to described floating
Diffusion region transfer after a period of time, reads pixel output voltage signal stable at this time, is denoted as Vsig.By the pixel list
The double sampling voltage of member is made the difference, and has just obtained eliminating the voltage signal Vout after steady noise mode.Such as publicity institute
Show:
(Vblk-Vsig) Gpixel=Vout
Wherein, Gpixel is source follower Sx gain amplifier, and value is generally between 0.8 to 0.9.
The circuit structure can reduce the dark current of imaging sensor, improve the charge transport properties of imaging sensor.
The embodiment of the present application provides a kind of production method of imaging sensor, with reference to figs. 2 to shown in attached drawing 8, comprising: mention
For semiconductor substrate 110, the first photosensitive element 131 is formed in the semiconductor substrate 110 and for being isolated described first
First isolation structure 141 of photosensitive element 131；Epitaxial layer 120 is formed on 110 surface of semiconductor substrate；In the extension
The second photosensitive element 132 and the second isolation structure 142 for second photosensitive element 132 to be isolated are formed in layer 120,
In, second photosensitive element 132 extends to the first photosensitive element 131, and second isolation structure 142 extends to described first
Isolation structure 141.
It is carried out further below with reference to the production method of Fig. 2 to Fig. 8 imaging sensor described in the embodiment of the present application
It is described in detail.
Refering to what is shown in Fig. 2, providing semiconductor substrate 110, the semiconductor substrate 110 can be silicon substrate, or be exhausted
Silicon substrate on edge body.
In some embodiments of the present application, the semiconductor substrate 110 is P-type silicon, and the P-type silicon in silicon by serving as a contrast
P-type doping is carried out in bottom realizes all doping to realize, such as using ion implanting or the technique of diffusion.Execute doping process
When, the energy and doping concentration of Doped ions can be selected according to the prior art.The Doped ions are, for example, B,
BF2, the combination of one or more of gallium ion and indium ion, Doped ions concentration range is, for example, 1E14~1E16/cm3.This
Field technical staff should be understood that the requirement according to technological design, and the semiconductor substrate can also use other doping types,
The embodiment of the present application is only described by taking the semiconductor substrate of p-type doping as an example.
With continued reference to Fig. 2, the first photosensitive element 131 and described for being isolated is formed in the semiconductor substrate 110
First isolation structure 141 of the first photosensitive element 131.
First photosensitive element 131 described in the embodiment of the present application is, for example, photodiode, in each pixel region, institute
It states photodiode to arrange in the form of an array, for the optical signal received to be converted to electric signal.Such as: the photoelectricity two
Pole pipe with Bayer (Bayer) array arrangement, also can according to need in the semiconductor substrate and be arranged to other any arrays.In order to
Meet the requirement of the overall thickness thinning of the semiconductor substrate 110, each photodiode is in the semiconductor substrate 110
In be located substantially on same depth.
In some embodiments of the present application, the method for forming first photosensitive element 131 includes: in the semiconductor
The first ion implanting is carried out in substrate 110.In embodiments herein, first photosensitive element 131 can be by half
It is formed in conductor substrate 110 by the first ion implantation technology of execution more than once.It is injected in first photosensitive element 131
The type of the first ion and the type of Doped ions in the semiconductor substrate 110 on the contrary, for example, working as the semiconductor substrate
110 for p-type when adulterating, and the first ion injected in the first photosensitive element 131 is n-type doping ion.In some realities of the application
It applies in example, the n-type doping ion includes phosphorus, and one or more of As and antimony ion are combined wherein, the n-type doping
The dopant magnitude range of ion is 1E11~5E13/cm2.Due to being limited by ion implantation energy, first ion
Injection depth in the semiconductor substrate 110 is typically not greater than 3.5 microns, therefore the thickness of the photodiode is general
Less than 3.5 microns, therefore, the full-well capacity that imaging sensor is improved by way of improving ion implantation energy has centainly
Limitation.
In some embodiments of the present application, first photosensitive element 131 with a thickness of 2 to 3.5 microns.
With continued reference to Fig. 2, first isolation structure 141 for realizing between active area of semiconductor device electricity every
From, such as the electric isolution between first photosensitive element 131.The forming method of first isolation structure 141 is, described
Third ion implantation technology more than once is executed in semiconductor substrate 110.The third injected in first isolation structure 141
The type of ion is identical as the type of Doped ions in the semiconductor substrate 110, for example, when the semiconductor substrate 110 is P
When type adulterates, the third ion injected in the first isolation structure 141 is p-type Doped ions.
In embodiments herein, the semiconductor substrate 110 is P-type silicon, and the third ion is, for example, B, BF2、
The combination of one or more of gallium ion and indium ion, the dopant magnitude range of the third ion are 1E11~1E13/
cm2.Inject n-type doping ion in first photosensitive element 131, first isolation structure 141 with described first photosensitive yuan
The contact surface of part 131 forms PN junction, and the PN junction realizes the electric isolution between the first photosensitive element 131.
With reference to Fig. 3, form epitaxial layer 120 on 110 surface of semiconductor substrate, the epitaxial layer it is micro- with a thickness of 1 to 3
Rice.The technique for forming the epitaxial layer 120 is, for example, epitaxial growth technology, and the material of the epitaxial layer is silicon.It is set according to technique
The needs of meter also may include certain density Doped ions in the epitaxial layer, and the doping type of the Doped ions is in institute
The doping type for stating Doped ions in semiconductor substrate is identical.
In some embodiments of the present application, the epitaxial layer 120 is P-type silicon, and the P-type silicon can be by described outer
Prolong and carry out p-type doping in layer 120 to realize, such as is realized using ion implanting or the technique of diffusion and all adulterated.Described mixes
Heteroion is, for example, B, BF2, one or more of gallium ion and indium ion combination, Doped ions concentration range be, for example,
1E14~1E16/cm3。
With reference to Fig. 4, the second photosensitive element 132 and photosensitive for being isolated described second is formed in the epitaxial layer 120
Second isolation structure 142 of element 132, wherein second photosensitive element 132 extends to the first photosensitive element 131, and described
Two isolation structures 142 extend to first isolation structure 141.
Second photosensitive element 132 described in the embodiment of the present application is, for example, photodiode.In some implementations of the application
In example, the method for forming second photosensitive element 132 includes: to carry out the second ion implanting in the epitaxial layer 120.At this
In some embodiments of application, second photosensitive element 132 can be executed more than once by passing through in epitaxial layer 120
Second ion implantation technology is formed.
The type of the second ion injected in second photosensitive element 132 is obtained with Doped ions in the epitaxial layer 120
Type injects to obtain the second ion in second photosensitive element 132 on the contrary, for example, when the epitaxial layer 120 is that p-type is adulterated
For n-type doping ion.In some embodiments of the present application, the dopant magnitude range of the n-type doping ion be 1E11~
5E13/cm2, the n-type doping ion includes phosphorus, one or more of As and antimony ion combination.
Injection depth of second ion in the epitaxial layer 120 is less than 3 microns, therefore second photosensitive element
132 thickness is less than 3 microns.
In embodiments herein, the first ion for being injected in first photosensitive element 131 and described second photosensitive
The injection type of the second ion injected in element 132 is identical, further, first injected in the first photosensitive element 131 from
It is sub identical with the second ion that is being injected in second photosensitive element 132.
In embodiments herein, due to first photosensitive element 131 and the common structure of second photosensitive element 132
At the photosensitive element 130 of one pixel unit of described image sensor, therefore, second photosensitive element 132 extends to described
First photosensitive element 131.Moreover, the bottom of second photosensitive element 132 (close to one end of first photosensitive element 131)
There should be joint face as big as possible with first photosensitive element 131.In some embodiments of the present application, in the epitaxial layer
It carries out making the second injection ion by annealing process after the second ion implanting forms second photosensitive element 132 in 120
And the first injection uniform ion diffusion in the semiconductor substrate, especially make first photosensitive element 131 and the second sense
First injection ion of the joint face of optical element 132 and the second injection ion are further uniformly spread, and make described first photosensitive yuan
Part 131 and the second photosensitive element 132 constitute the photosensitive element 130.The annealing process be, for example, rapid thermal annealing or
Spike annealing process.
With continued reference to Fig. 4, second isolation structure 142 is for the electric isolution between second photosensitive element 132.
The forming method of second isolation structure 142 is that the 4th ion implanting work more than once is executed in the epitaxial layer 120
Skill.The type phase of the type of the 4th ion injected in second isolation structure 142 and Doped ions in the epitaxial layer 120
Together, for example, when the epitaxial layer 120 is that p-type is adulterated, the 4th ion injected in the second isolation structure 142 be p-type adulterate from
Son.
In embodiments herein, the epitaxial layer is P-type silicon, and the 4th ion is, for example, B, BF2, gallium ion and
The combination of one or more of indium ion, the dopant magnitude range of the 4th ion are 1E11~1E13/cm2.It is described
Injecting p-type Doped ions in second photosensitive element 132, second isolation structure 142 connect with second photosensitive element 132
Contacting surface forms PN junction, and the PN junction realizes the electric isolution between the second photosensitive element 132.
Second isolation structure 142 extends to first isolation structure 141.Further, second isolation
142 position of structure is corresponding with the position of first isolation structure 141, described second isolation structure 142 with described first every
It is located on same vertical plane from structure 141.Second isolation structure 142 extend to first isolation structure 141 and with
First isolation structure 141 collectively forms isolation structure 140.The isolation structure 140 realize the sensor devices 130 it
Between electric isolution.
The production method of imaging sensor provided in this embodiment, described in being grown in the semiconductor substrate 110
Epitaxial layer 120, and first photosensitive element 131 is formed in the semiconductor substrate 110 and the epitaxial layer 120 respectively
With second photosensitive element 132, avoid single production photosensitive element by technique limited, moreover, being felt by described first
Optical element 131 and second photosensitive element 132 collectively form the photosensitive element 130 of described image sensor, increase described
The longitudinal size of photosensitive element 130 improves the full-well capacity of each pixel unit.
With reference to Fig. 5, method described in the present embodiment further include: floating diffusion region 150 is formed in the epitaxial layer 120,
And the transistor 160 of described image sensor pixel unit.
Form the method for the floating diffusion region 150 for example are as follows: in the epitaxial layer 120 set depth carry out third from
Son injection.In some embodiments of the present application, when the epitaxial layer 120 is that p-type is adulterated, the floating diffusion region 150 is N
Type doping.In the specific embodiment of the application, the epitaxial layer 120 is p-type doping, and the floating diffusion region 150 is N
Type doping, when executing floating diffusion region doping process, the energy range for carrying out n-type doping is 5Kev to 50Kev, Doped ions agent
Magnitude range is 1E14 to 1E15/cm2。
In some embodiments of the present embodiment, the transistor 160 of described image sensor pixel unit is that 4T pixel is brilliant
Body pipe, comprising: transmission transistor 161, reset transistor 162, source follower 163 and row gate tube 164.The figure
As the circuit diagram of each pixel unit of sensor 4T pixel transistor is as shown in Figure 1.
Each crystal with reference to attached drawing 5, in the reset transistor 162, source follower 163 and row gate tube 164
Pipe all include positioned at the epi-layer surface gate structure and source region and drain region in epitaxial layer, it should be noted that
It is not draw the reset transistor 162, source follower 163 and row gating for purposes of brevity, in attached drawing
The detailed construction of pipe 164, only schematically with square replace indicate the reset transistor 162, source follower 163, with
And the position of row gate tube 164.
In some embodiments of the present application, the transistor 160 of described image sensor pixel unit can also be other
Structure, such as 5T dot structure or 6T dot structure etc..
The production method of imaging sensor provided in this embodiment, by the transistor of described image sensor pixel unit
160, from being transferred on the epitaxial layer 120 in isolation structure, to reduce the size of imaging sensor isolation structure, increase
The size in the region of photosensitive element 130 can be made in semiconductor substrate, that is to say, that increase the transverse direction of photosensitive element 130
Size improves the full-well capacity of each image sensor pixel cells.
With reference to Fig. 6, the surface in the another side of the semiconductor substrate 110, that is, far from the epitaxial layer 120 is formed
Insulation system, the insulation system include one layer or more of dielectric layer, that is to say, that the insulation system is multilayer dielectricity
The stack architecture that layer is formed.It is formed refering to what is shown in Fig. 6, schematically depicting by the first insulating layer 170 and second insulating layer 171
Insulation system, wherein first insulating layer 170 may include high dielectric constant material layer, anti-reflecting layer or adherency
Layer in any one or it is a variety of.The second insulating layer 171 also may include high dielectric constant material layer, anti-reflecting layer
Either any one in adhesion layer or a variety of.
With reference to Fig. 7, colour filter 180, the colour filter are formed in the second insulating layer 171 for constituting insulation system
180 is corresponding with the position of the photosensitive element 130, for the light by particular range of wavelengths, makes the particular range of wavelengths
Light enter photosensitive element 130.In some embodiments of the present application, the colour filter 180 be can permit through feux rouges, indigo plant
Light or green light.In some embodiments of the present application, the colour filter 180 is with the internal resin for being added with organic pigment
It is formed.In addition, the colour filter 180 can also be made of other materials, such as the light of specific wavelength can be reflected away
Reflectorized material etc..
With continued reference to Fig. 7, photomask 181 is formed between the colour filter 180, the photomask 181 is for being isolated
The colour filter 180 makes the light in different pixels region not enter the photodiode of other pixel ranges.
The photomask 181 can be made of metal or light absorbing black filter layer.The material of photomask 181 is excellent
It is selected as the metal material with shaded effect, such as tungsten, aluminium or copper etc., the technique for forming photomask 181 is, for example, chemical gaseous phase
Deposition shading membrane material simultaneously carries out selective etch, then removes part shading membrane material corresponding with photodiode positions, shape
At the photomask 181.
With reference to Fig. 8, lenticule 190 is formed on the colour filter 180.The lenticule 190 is used to be directed to each pixel
Unit assembles light, and material is, for example, that the copolymer resin of polystyrene resin, acrylic resin or these resins is formed.Shape
It can be any one existing lenticule manufacture craft at the technique of the lenticule, be not described in detail herein.
The embodiment of the present application also provides a kind of imaging sensor, and structure shown in Fig. 8 is image described in the embodiment of the present application
The structural schematic diagram of sensor, comprising: semiconductor substrate 110；Epitaxial layer 120 is located at 110 surface of semiconductor substrate；Sense
Optical element 130, the photosensitive element 130 include the first photosensitive element 131 in the semiconductor substrate 110 and are located at
The second photosensitive element 132 in the epitaxial layer 120, second photosensitive element 132 extend to the first photosensitive element 131；Every
From structure 140, the isolation structure 140 is used to be isolated the photosensitive element 130, including is located in the semiconductor substrate 110
The first isolation structure 141 and the second isolation structure 142 in the epitaxial layer 120, second isolation structure 142 prolong
Extend to first isolation structure 141.
With reference to Fig. 8, the photosensitive element 130 include the first photosensitive element 131 in the semiconductor substrate 110 with
And the second photosensitive element 132 in the epitaxial layer 120, second photosensitive element 132 extend to the first photosensitive element
131。
First photosensitive element 131 and the second photosensitive element 132 is all, for example, photodiode.Described first
Photosensitive element 131 and the second photosensitive element 132 collectively form the photosensitive element 140 of described image sensor.In each pixel
Region, the photosensitive element 140 are arranged in the form of an array, for the optical signal received to be converted to electric signal.
In some embodiments of the present application, first photosensitive element 131 is formed in the semiconductor substrate 110,
It is formed by carrying out the first ion implanting in the semiconductor substrate 110.First injected in first photosensitive element 131
The type of Doped ions is on the contrary, for example, when the semiconductor substrate 110 is P in the type of ion and the semiconductor substrate 110
When type adulterates, the first ion injected in the first photosensitive element 131 is n-type doping ion.
In some embodiments of the present application, first photosensitive element 131 with a thickness of 2 to 3.5 microns.
With continued reference to Fig. 8, the epitaxial layer 120 is located at 110 surface of semiconductor substrate, the epitaxial layer with a thickness of
1 to 3 micron.In some embodiments of the present application, the epitaxial layer 120 is P-type silicon, and the P-type silicon can be by described
P-type doping is carried out in epitaxial layer 120 to realize.The Doped ions are, for example, B, BF2, one of gallium ion and indium ion
Or multiple combinations, Doped ions concentration range are, for example, 1E14~1E16/cm3。
Second photosensitive element 132 is formed in the epitaxial layer 120, and second photosensitive element 132 extends
To first photosensitive element 131.In some embodiments of the present application, the method packet of second photosensitive element 132 is formed
It includes: carrying out the second ion implanting in the epitaxial layer 120.
Doped ions in the type of the second ion injected in second photosensitive element 132 and the epitaxial layer 120
Type is on the contrary, for example, when the epitaxial layer 120 is that p-type is adulterated, the second ion for injecting in second photosensitive element 132
For n-type doping ion.In some embodiments of the present application, the dose value range of the n-type doping ion is 1E11~5E13/
cm2, the n-type doping ion includes phosphorus, one or more of As and antimony ion combination.
Injection depth of second ion in the epitaxial layer 120 is less than 3 microns, therefore second photosensitive element
132 thickness is less than 3 microns.
In embodiments herein, the first ion for being injected in first photosensitive element 131 and described second photosensitive
The injection type of the second ion injected in element 132 is identical, further, first injected in the first photosensitive element 131 from
It is sub identical with the second ion that is being injected in second photosensitive element 132.
In embodiments herein, due to first photosensitive element 131 and the common structure of second photosensitive element 132
At the photosensitive element 130 of one pixel unit of described image sensor, therefore, second photosensitive element 132 extends to described
First photosensitive element 131.Moreover, the bottom of second photosensitive element 132 (close to one end of first photosensitive element 131)
There should be joint face as big as possible with first photosensitive element 131.
In some embodiments of the present application, floating diffusion region 150 and described is also formed in the epitaxial layer 120
The transistor 160 of image sensor pixel cells.
In the present embodiment, the transistor 160 is 4T pixel transistor, comprising: transmission transistor 161, resetting crystal
Pipe 162, source follower 163 and row gate tube 164.The each pixel unit of imaging sensor 4T pixel transistor
Circuit diagram it is as shown in Figure 1.
Each crystal with reference to attached drawing 8, in the reset transistor 162, source follower 163 and row gate tube 164
Pipe all includes the grid positioned at the epi-layer surface and source region and drain region in epitaxial layer, it should be noted that is gone out
The reset transistor 162, source follower 163 and row gate tube 164 are not drawn in succinct purpose, attached drawing
Detailed construction, only schematically with square replace indicate the reset transistor 162, source follower 163 and row choosing
The position of siphunculus 164.
In some embodiments of the present application, the transistor 160 of described image sensor pixel unit can also be other
Structure, such as 5T dot structure or 6T dot structure etc..
In order to which the beneficial effect of the application is more clearly understood, Fig. 9 (a) and Fig. 9 (b) provide the embodiment of the present application image
The structural schematic diagram of sensor and a kind of comparison of the structural schematic diagram of prior art image sensor.Fig. 9 (a) is the application
A kind of structural schematic diagram for imaging sensor that embodiment provides, structure are described in detail in front, herein no longer
It repeats.Fig. 9 (b) is a kind of structural schematic diagram of prior art image sensor, wherein (T) represents described image sensor isolation
The top view (Top view) of 140 part of structure, (S) represent the sectional view (Sectional view) of the structural schematic diagram,
Described image sensor includes semiconductor substrate 110, is formed with photosensitive element 130 and isolation junction in the semiconductor substrate 110
Structure 140 and floating diffusion region 150, wherein the isolation structure 140 is passed for the photosensitive element 130, described image to be isolated
Sensor further includes the transmission transistor 161 being formed in the semiconductor substrate 110, and the reset transistor 162, source electrode follow
Device 163 and row gate tube 164 are formed on isolation structure 140, therefore the critical size of the isolation structure 140 is relatively
Greatly, to tie up the area of photosensitive element 130.
Comparison diagram 9 (a) and Fig. 9 (b), compared with prior art image sensor, one kind provided by the embodiments of the present application
Imaging sensor and preparation method thereof on the one hand by growing the epitaxial layer 120 in the semiconductor substrate 110, and divides
First photosensitive element 131 and described second photosensitive is not formed in the semiconductor substrate 110 and the epitaxial layer 120
Element 132, avoid single production photosensitive element by technique limit, increase the longitudinal size of photosensitive element 130, promotion
On the other hand the transistors 160 of image sensor pixel cells is formed in described outer by the full-well capacity of each pixel unit
Prolong on layer 120, increase the lateral dimension of photosensitive element 130, improves the full-well capacity of each pixel unit.
In conclusion after reading this detailed disclosures, it will be understood by those skilled in the art that aforementioned detailed disclosure
Content can be only presented in an illustrative manner, and can not be restrictive.Although not explicitly described or shown herein, this field skill
Art personnel are understood that improve and modify it is intended to include the various reasonable changes to embodiment.These change, improve and
It modifies and is intended to be proposed by the disclosure, and in the spirit and scope of the exemplary embodiment of the disclosure.
It should be appreciated that term that the present embodiment uses " and/or " it include associated listing one or more of project
It is any or all combination.It, can be with it should be appreciated that when an element is referred to as " connection " or " coupling " to another element
It is directly connected or is coupled to another element, or there may also be intermediary elements.
Similarly, it should be understood that when the element of such as layer, region or substrate etc is referred to as in another element " upper "
When, it can directly on the other element, or there may also be intermediary elements.In contrast, term " directly " indicates
There is no intermediary element.Term " including ", " including ", " including " and/or " including " are also understood that, herein in use, referring to
Bright there are documented feature, entirety, step, operation, element and/or component, but presence or one or more additional is not precluded
Other a features, entirety, step, operation, element, component and/or their group.
It is also understood that although term first, second, third, etc. can be used herein to describe various elements, these
Element should not be limited by these terms.These terms are only used to distinguish an element with another element.Therefore, exist
In the case where not being detached from the teachings of the present invention, first element in some embodiments can be referred to as in other embodiments
Second element.Identical reference label or identical reference designator indicate identical element throughout the specification.
In addition, by reference to as Utopian graphical representation of exemplary cross sectional view and/or plane diagram example is described
Property embodiment.Therefore, because with the shape illustrated not being both foreseeable caused by such as manufacturing technology and/or tolerance.Cause
Exemplary embodiment, should not be interpreted as being limited to the shape in region out shown here, but should include by for example making by this
The deviation in shape caused by making.For example, the etching area for being shown as rectangle would generally have circular or curved spy
Sign.Therefore, region shown in figure is substantially schematical, and shape is not configured to show the practical shape in the region of device
Shape is also not to limit the range of exemplary embodiment.
Claims (12)
1. a kind of imaging sensor characterized by comprising
Semiconductor substrate；
Epitaxial layer is located at the semiconductor substrate surface；
Photosensitive element, the photosensitive element include the first photosensitive element in the semiconductor substrate and are located at described outer
Prolong the second photosensitive element in layer, second photosensitive element extends to the first photosensitive element；
Isolation structure, the isolation structure is for being isolated the photosensitive element, including first in the semiconductor substrate
Isolation structure and the second isolation structure in the epitaxial layer, second isolation structure extend to first isolation junction
Structure.
2. imaging sensor as described in claim 1, which is characterized in that further include:
Floating diffusion region is located in the epitaxial layer；
The transistor of described image sensor pixel unit is located on the epitaxial layer.
3. imaging sensor as claimed in claim 2, which is characterized in that the transistor of described image sensor pixel unit is
Four transistor pixel cells.
4. imaging sensor as described in claim 1, which is characterized in that first photosensitive element it is micro- with a thickness of 2 to 3.5
Rice.
5. imaging sensor as described in claim 1, which is characterized in that the thickness of second photosensitive element is less than 3 microns.
6. a kind of production method of imaging sensor characterized by comprising
Semiconductor substrate is provided, forms the first photosensitive element and photosensitive for being isolated described first in the semiconductor substrate
First isolation structure of element；
Epitaxial layer is formed in the semiconductor substrate surface；
The second photosensitive element and the second isolation structure for second photosensitive element to be isolated are formed in the epitaxial layer,
Wherein, second photosensitive element extends to the first photosensitive element, and second isolation structure extends to first isolation junction
Structure.
7. method as claimed in claim 6, which is characterized in that the method also includes: it is formed in the epitaxial layer floating
Diffusion region forms the transistor of described image sensor pixel unit on said epitaxial layer there.
8. method as claimed in claim 6, which is characterized in that the method for forming first photosensitive element includes: described
The first ion implanting is carried out in semiconductor substrate.
9. method according to claim 8, which is characterized in that the method for forming second photosensitive element includes: described
The second ion implanting is carried out in epitaxial layer, wherein the first ion implanting is identical with the injection ionic type of the second ion implanting.
10. method as claimed in claim 9, which is characterized in that after carrying out the second ion implanting in the epitaxial layer, move back
Fire.
11. imaging sensor as claimed in claim 6, which is characterized in that first photosensitive element with a thickness of 2 to 3.5
Micron.
12. imaging sensor as claimed in claim 6, which is characterized in that the thickness of second photosensitive element is micro- less than 3
Rice.
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Application publication date: 20190906 |