CN107946330A - Imaging sensor and forming method thereof - Google Patents
Imaging sensor and forming method thereof Download PDFInfo
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- CN107946330A CN107946330A CN201711146920.4A CN201711146920A CN107946330A CN 107946330 A CN107946330 A CN 107946330A CN 201711146920 A CN201711146920 A CN 201711146920A CN 107946330 A CN107946330 A CN 107946330A
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- 238000000034 method Methods 0.000 title claims abstract description 60
- 238000003384 imaging method Methods 0.000 title claims abstract description 29
- 239000000758 substrate Substances 0.000 claims abstract description 94
- 238000002955 isolation Methods 0.000 claims abstract description 89
- 239000004065 semiconductor Substances 0.000 claims abstract description 81
- 229910052751 metal Inorganic materials 0.000 claims abstract description 43
- 239000002184 metal Substances 0.000 claims abstract description 43
- 239000010410 layer Substances 0.000 claims description 217
- 230000004888 barrier function Effects 0.000 claims description 22
- 239000011241 protective layer Substances 0.000 claims description 22
- 239000000463 material Substances 0.000 claims description 15
- 238000005137 deposition process Methods 0.000 claims description 9
- NRTOMJZYCJJWKI-UHFFFAOYSA-N Titanium nitride Chemical compound [Ti]#N NRTOMJZYCJJWKI-UHFFFAOYSA-N 0.000 claims description 8
- 230000015572 biosynthetic process Effects 0.000 claims description 7
- 238000005229 chemical vapour deposition Methods 0.000 claims description 7
- WFKWXMTUELFFGS-UHFFFAOYSA-N tungsten Chemical compound [W] WFKWXMTUELFFGS-UHFFFAOYSA-N 0.000 claims description 7
- 229910052721 tungsten Inorganic materials 0.000 claims description 7
- 239000010937 tungsten Substances 0.000 claims description 7
- 229910021420 polycrystalline silicon Inorganic materials 0.000 claims description 6
- 229920005591 polysilicon Polymers 0.000 claims description 6
- 229910003074 TiCl4 Inorganic materials 0.000 claims description 4
- 230000005622 photoelectricity Effects 0.000 claims description 2
- PCHJSUWPFVWCPO-UHFFFAOYSA-N gold Chemical compound [Au] PCHJSUWPFVWCPO-UHFFFAOYSA-N 0.000 claims 2
- 239000010931 gold Substances 0.000 claims 2
- 229910052737 gold Inorganic materials 0.000 claims 2
- 230000008569 process Effects 0.000 abstract description 13
- 238000012545 processing Methods 0.000 abstract description 4
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 19
- 238000005530 etching Methods 0.000 description 17
- 238000000059 patterning Methods 0.000 description 13
- 238000009792 diffusion process Methods 0.000 description 11
- 229910052581 Si3N4 Inorganic materials 0.000 description 10
- HQVNEWCFYHHQES-UHFFFAOYSA-N silicon nitride Chemical compound N12[Si]34N5[Si]62N3[Si]51N64 HQVNEWCFYHHQES-UHFFFAOYSA-N 0.000 description 10
- BOTDANWDWHJENH-UHFFFAOYSA-N Tetraethyl orthosilicate Chemical compound CCO[Si](OCC)(OCC)OCC BOTDANWDWHJENH-UHFFFAOYSA-N 0.000 description 8
- 229920002120 photoresistant polymer Polymers 0.000 description 8
- 239000000377 silicon dioxide Substances 0.000 description 7
- 235000012431 wafers Nutrition 0.000 description 7
- 229910052814 silicon oxide Inorganic materials 0.000 description 5
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- 238000000231 atomic layer deposition Methods 0.000 description 2
- 239000003795 chemical substances by application Substances 0.000 description 2
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- 229910052732 germanium Inorganic materials 0.000 description 2
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- GYHNNYVSQQEPJS-UHFFFAOYSA-N Gallium Chemical compound [Ga] GYHNNYVSQQEPJS-UHFFFAOYSA-N 0.000 description 1
- 229910001218 Gallium arsenide Inorganic materials 0.000 description 1
- 229910000577 Silicon-germanium Inorganic materials 0.000 description 1
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Classifications
-
- 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
- H01L27/14643—Photodiode arrays; MOS imagers
-
- 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
Abstract
A kind of imaging sensor and forming method thereof, comprises the following steps：Semiconductor substrate is provided, there is photodiode active layer in the Semiconductor substrate；Sacrifice layer is formed on the surface of the Semiconductor substrate；The sacrifice layer and the Semiconductor substrate are etched, to form deep trench, the deep trench at least runs through a part for the photodiode active layer；Deep trench isolation layer is formed, the deep trench isolation layer covers the inner wall of the deep trench；Metal is filled into the deep trench, to form metallic grid.The present invention program can efficiently reduce processing step, reduce process complexity and cost.
Description
Technical field
The present invention relates to field of semiconductor manufacture, more particularly to a kind of imaging sensor and forming method thereof.
Background technology
In the manufacturing process of cmos image sensor (CMOS Image Sensors, CIS) device, to reduce different figures
The optical crosstalk of the incident light received as senser element on the surface of Semiconductor substrate, it is necessary to form metallic grid (Metal
Grid) to isolate incident light；To prevent the photo-generated carrier of different zones to be diffused into adjacent area, it is necessary in Semiconductor substrate
It is internally formed deep trench isolation (Deep Trench Isolation, DTI) structure.
In the prior art, deep groove isolation structure and metallic grid are to carry out patterning formation respectively.
Specifically, after the crystal face Semiconductor substrate of device wafers (Device Wafer) forms active device, in institute
State in the brilliant back of the body Semiconductor substrate of device wafers and form deep groove isolation structure.More specifically, the patterning brilliant back of the body semiconductor lining
Bottom is to form groove, then fill insulant (such as can include silica or silicon nitride), Ran Houping in the groove
The smoothization brilliant back of the body Semiconductor substrate and the insulating materials.
Further, substrate protective layer, barrier layer, metal layer etc. are sequentially formed on the surface of brilliant back of the body Semiconductor substrate, schemed
Case simultaneously etches the substrate protective layer, barrier layer, metal layer to form the metallic grid.
The process complexity and cost of existing formation deep groove isolation structure and metallic grid are higher, and processing step is more.
The content of the invention
The technical problem to be solved by the present invention is to provide a kind of imaging sensor and forming method thereof, can efficiently reduce work
Skill step, reduces process complexity and cost.
In order to solve the above technical problems, the embodiment of the present invention provides a kind of forming method of imaging sensor, including it is following
Step：Semiconductor substrate is provided, there is photodiode active layer in the Semiconductor substrate；In the table of the Semiconductor substrate
Face forms sacrifice layer；The sacrifice layer and the Semiconductor substrate are etched, to form deep trench, the deep trench at least runs through
A part for the photodiode active layer；Deep trench isolation layer is formed, the deep trench isolation layer covers the interior of the deep trench
Wall；Metal is filled into the deep trench, to form metallic grid.
Optionally, the forming method of described image sensor further includes：Remove the sacrifice layer；Grid protective layer is formed,
The grid protective layer covers metallic grid, the deep trench isolation layer and the Semiconductor substrate；In adjacent metal
Filter is set between grid.
Optionally, the removal sacrifice layer includes：Planarize the sacrifice layer, the deep trench isolation layer and described
Metallic grid；Remove the sacrifice layer after planarization.
Optionally, the formation deep trench isolation layer includes：The deep trench isolation layer is formed using atom layer deposition process.
Optionally, before the surface of the Semiconductor substrate forms sacrifice layer, the forming method of described image sensor
Further include：Form substrate protective layer；Wherein, the sacrifice layer is stacked in the substrate protective layer.
Optionally, the material of the sacrifice layer includes polysilicon.
Optionally, before filling metal into the deep trench, the forming method of described image sensor further includes：Formed
Barrier layer, the barrier layer cover the surface of the deep trench isolation layer.
Optionally, the material on the barrier layer includes titanium nitride, wherein, the titanium nitride is to use TiCl4Formed.
Optionally, metal is filled into the deep trench includes：Using chemical vapor deposition method, into the deep trench
Fill tungsten.
In order to solve the above technical problems, the embodiment of the present invention provides a kind of imaging sensor, including：Semiconductor substrate, institute
Stating in Semiconductor substrate has photodiode active layer；Sacrifice layer, positioned at the surface of the Semiconductor substrate；Deep trench, position
In in the sacrifice layer and the Semiconductor substrate, the deep trench at least runs through one of the photodiode active layer
Point；Deep trench isolation layer, the deep trench isolation layer cover the inner wall of the deep trench；Metallic grid, the metallic grid are filled in
In the deep trench.
Compared with prior art, the technical solution of the embodiment of the present invention has the advantages that：
In embodiments of the present invention, there is provided Semiconductor substrate, the Semiconductor substrate is interior to have photodiode active layer；
Sacrifice layer is formed on the surface of the Semiconductor substrate；The sacrifice layer and the Semiconductor substrate are etched, to form zanjon
Groove, the deep trench at least run through a part for the photodiode active layer；Form deep trench isolation layer, the deep trench isolation
Layer covers the inner wall of the deep trench；Metal is filled into the deep trench, to form metallic grid.Using the above scheme, lead to
Cross and form sacrifice layer on the surface of Semiconductor substrate, and then deep trench is formed in the sacrifice layer and Semiconductor substrate, so that
By forming the deep trench isolation layer for the inner wall for covering the deep trench, and metal is filled into the deep trench, can be in shape
After wrinkling separation layer without again patterning can form metallic grid, compared with the prior art in pass through double patterning work
Skill forms deep groove isolation structure and metallic grid respectively, and technique step can be efficiently reduced using the scheme of the embodiment of the present invention
Suddenly, process complexity and cost are reduced.Further, since the metal of metallic grid is to fill to be formed into the deep trench
, compared with the prior art in by etch formed, it is possible to prevente effectively from the problem of metal in etching process collapses or peels off.
Further, what is filled in deep groove isolation structure of the prior art is insulating layer, when deep groove isolation structure is damaged
Carrier diffusion may occur to adjacent area, and in embodiments of the present invention, due to being filled with metal in deep trench isolation layer,
When deep trench isolation layer is damaged, carrier can be exported with the wiring of metal, reduce diffusion harmfulness.
Further, in embodiments of the present invention, the deep trench isolation layer can be formed using atom layer deposition process.Due to
Atom layer deposition process is commonly used in carrying out the controllable film growth of atomic scale, and the uniformity control to deep trench isolation layer is more
It is good, also, since atom layer deposition process is to deposit to form film in layer with monatomic form membrane, compared to other depositions
Technique, has stronger gap filling ability, can meet the demand of the depth-to-width ratio in deep trench.
Further, in embodiments of the present invention, using chemical vapor deposition method, tungsten, phase are filled into the deep trench
Than in physical gas-phase deposition, there is stronger gap filling ability, can meet the demand of the depth-to-width ratio in deep trench.
Brief description of the drawings
Fig. 1 to Fig. 5 is a kind of section of the corresponding device of each step in forming method of imaging sensor in the prior art
Structure diagram；
Fig. 6 is a kind of flow chart of the forming method of imaging sensor in the embodiment of the present invention；
Fig. 7 to Figure 14 is the corresponding device of each step in a kind of forming method of imaging sensor in the embodiment of the present invention
Cross-sectional view.
Embodiment
, it is necessary to form metallic grid and depth on the surface of Semiconductor substrate in the manufacturing process of existing CIS devices
Recess isolating structure.
Specifically, after capturing incident light by camera lens (Microlens), filter (Colour can be used
Filter) filtered to remove irrelevant light, form monochromatic light and be absorbed incident photon arrival photodiode region.
Before monochromatic light reaches photodiode, due to the difference of incident angle, it may occur that crosstalk phenomenon.For solve it is above-mentioned enter
The optical crosstalk problem of light is penetrated, it is necessary in different pixels (pixel) region, increases metallic grid, so as to utilize the stronger of metal
Reflecting effect, enables to the monochromatic light of offset point, by the reflex of metal, specific region is fixed on, without going here and there
Adjacent pixel region is disturbed, so that quantum efficiency is significantly improved, and improves sensitivity and the figure of imaging sensor
The quality of picture.
Photodiode area in Semiconductor substrate, in order to prevent the photo-generated carrier of different zones be diffused into adjacent
Region, the problem of causing image fault, can form deep trench isolation in Semiconductor substrate, help avoid in different pixels area
The problem of photo-generated carrier diffusion occurs between domain.
More specifically, for back-illuminated cmos image sensors (Backside Illumination-CMOS Image
Sensors, BSI-CIS) device, metallic grid can be formed on the surface of the Semiconductor substrate of wafer rear, in wafer rear
Semiconductor substrate be internally formed deep groove isolation structure；For preceding illuminated cmos image sensor (Front-side
Illumination-CMOS Image Sensors, FSI-CIS) device, it can be served as a contrast in the semiconductor of wafer frontside selection region
The surface at bottom forms metallic grid, and deep groove isolation structure is internally formed in the Semiconductor substrate of wafer rear.
Specifically, deep groove isolation structure and metallic grid are to carry out patterning formation respectively.
Fig. 1 to Fig. 5 is a kind of section of the corresponding device of each step in forming method of imaging sensor in the prior art
Structure diagram.Specifically, deep groove isolation structure is formed in the step of Fig. 1 is shown to Fig. 2, and then shown in Fig. 3 to Fig. 5
Metallic grid is formed in step.
With reference to Fig. 1, there is provided Semiconductor substrate 100, the Semiconductor substrate is interior to have photodiode active layer 101, schemes
Semiconductor substrate 100 described in case and by etching form groove 112.
Specifically, the Semiconductor substrate 100 can be silicon substrate, or the material of the Semiconductor substrate 100 may be used also
Think germanium, SiGe, carborundum, GaAs or gallium indium, the Semiconductor substrate 100 can also be the silicon substrate on insulator
Or the germanium substrate on insulator, or grow the substrate for having epitaxial layer (Epitaxy layer, Epi layer).
In the photodiode active layer 101, can have the first active layer and the first conduction of the first electric conductivity
Property opposite the second electric conductivity the second active layer and by the separated intrinsic layer (not shown) of the first and second active layers, with
Photodiode is formed in the Semiconductor substrate 100.
The step of patterning Semiconductor substrate 100 is to form groove 112 can include：Served as a contrast in the semiconductor
The surface at bottom 100 forms patterned deep trench isolation photoresist layer 111, with the patterned deep trench isolation photoresist layer 111
It is Semiconductor substrate described in mask etching 100 to obtain groove 112.
It is understood that the depth of the groove 112 can be deeper than the photodiode active layer 101, so as to obtain
More preferable isolation effect is obtained, avoids the problem that photo-generated carrier diffusion occurs between different pixels region.
With reference to Fig. 2, remove the deep trench isolation photoresist layer 111, then in the groove 112 fill insulant with
Deep trench isolation layer 110 is formed, and then the Semiconductor substrate 100 and the deep trench isolation layer 110 are planarized.
Wherein, silica or silicon nitride can for example be included by forming the insulating materials of the deep trench isolation layer 110.
With reference to Fig. 3, substrate protective layer 122, barrier layer 124, metal layer are formed on the surface of the Semiconductor substrate 100
126th, dielectric layer 128, ethyl orthosilicate (TEOS) layer 129, and then form patterned metallic grid photoresist layer 131.
Wherein, the substrate protective layer 122 can include silica and silicon nitride, or can also include silica；
The material on the barrier layer 124 can include titanium nitride；The packing material of the metal layer 126 can include tungsten；It is described
The material of dielectric layer 128 can include silicon nitride.
It is mask with patterned metallic grid photoresist layer 131 with reference to Fig. 4, to barrier layer 124, metal layer 126, is situated between
Matter layer 128 and ethyl orthosilicate (TEOS) layer 129 perform etching, to form groove 149.
Specifically, at least three etch steps can be used to form groove 149.First with patterned metallic grid photoetching
Glue-line 131 is mask, using appropriate etching agent and etching technics to ethyl orthosilicate (TEOS) layer 129 and dielectric layer
128 perform etching, and secondly carry out metal etch to metal layer 126, finally using appropriate etching agent and etching technics to resistance
Barrier 124 performs etching.
It is pointed out that barrier layer 124, metal layer 126, dielectric layer 128 and ethyl orthosilicate after etching
(TEOS) layer 129 is collectively forming metallic grid.
With reference to Fig. 5, form grid protective layer 142, and filter 150 is set between adjacent metallic grid.
Wherein, the material of the grid protective layer 142 can include silica or silicon nitride.
The present inventor has found by research, in the prior art, depth is formed respectively using double patterning technique
Recess isolating structure and metallic grid, process complexity and cost are higher, and processing step is more, further, due to metallic grid
Critical size (Critical Dimension, CD) very little, by etching technics formed metallic grid during, metal grid
Grid easily cave in and peel off (Peeling), and easily damage the substrate protective layer below metallic grid, influence photoelectricity and turn
Change efficiency, namely the technology difficulty for causing increase to form substrate protective layer.
In embodiments of the present invention, there is provided Semiconductor substrate, the Semiconductor substrate is interior to have photodiode active layer；
Sacrifice layer is formed on the surface of the Semiconductor substrate；The sacrifice layer and the Semiconductor substrate are etched, to form zanjon
Groove, the deep trench at least run through a part for the photodiode active layer；Form deep trench isolation layer, the deep trench isolation
Layer covers the inner wall of the deep trench；Metal is filled into the deep trench, to form metallic grid.Using the above scheme, lead to
Cross and form sacrifice layer on the surface of Semiconductor substrate, and then deep trench is formed in the sacrifice layer and Semiconductor substrate, so that
By forming the deep trench isolation layer for the inner wall for covering the deep trench, and metal is filled into the deep trench, can be in shape
After wrinkling separation layer without again patterning can form metallic grid, compared with the prior art in, pass through double patterning
Technique forms deep groove isolation structure and metallic grid respectively, using the scheme of the embodiment of the present invention, can efficiently reduce technique
Step, reduces process complexity and cost.Further, since the metal of metallic grid is to fill to be formed into the deep trench
, compared with the prior art in by etch formed, it is possible to prevente effectively from the problem of metal in etching process collapses or peels off.
Further, what is filled in deep groove isolation structure of the prior art is insulating layer, when deep groove isolation structure is damaged
Carrier diffusion may occur to adjacent area, and in embodiments of the present invention, due to being filled with metal in deep trench isolation layer,
When deep trench isolation layer is damaged, carrier can be exported with the wiring of metal, reduce diffusion harmfulness.
It is understandable to enable above-mentioned purpose, feature and the beneficial effect of the present invention to become apparent, below in conjunction with the accompanying drawings to this
The specific embodiment of invention is described in detail.
With reference to Fig. 6, Fig. 6 is a kind of flow chart of the forming method of imaging sensor in the embodiment of the present invention.Described image
The forming method of sensor can include step S21 to step S25：
Step S21：Semiconductor substrate is provided, there is photodiode active layer in the Semiconductor substrate；
Step S22：Sacrifice layer is formed on the surface of the Semiconductor substrate；
Step S23：The sacrifice layer and the Semiconductor substrate are etched, to form deep trench, the deep trench is at least
Through a part for the photodiode active layer；
Step S24：Deep trench isolation layer is formed, the deep trench isolation layer covers the inner wall of the deep trench；
Step S25：Metal is filled into the deep trench, to form metallic grid.
Above-mentioned each step is illustrated with reference to Fig. 7 to Figure 14.
Fig. 7 to Figure 14 is the corresponding device of each step in a kind of forming method of imaging sensor in the embodiment of the present invention
Cross-sectional view.
With reference to Fig. 7, there is provided Semiconductor substrate 200, the Semiconductor substrate 200 is interior to have photodiode active layer 201,
Substrate protective layer is could be formed with the surface of the Semiconductor substrate 200, is stacked with the surface of the substrate protective layer sacrificial
Domestic animal layer 225.
Wherein, the substrate protective layer can include silica (Oxide) layer 222 and silicon nitride (SiN) layer 223, or
Person can also only include silicon oxide layer 222.
The material of the sacrifice layer 225 can include polysilicon (Poly).Since polysilicon is nonmetallic materials, can keep away
Exempt from metallic pollution, and price is appropriate, better economy.Certainly, the material of the sacrifice layer 225 can also be that other are appropriate
Material.
The photodiode active layer 201 can include the p-type doped layer and n-type doping layer stacked, therebetween also
There can be intrinsic semiconductor layer.
Further, patterned metallic grid photoresist layer 231 is formed on the surface of the sacrifice layer 225.
Be mask with patterned metallic grid photoresist layer 231 with reference to Fig. 8, to sacrifice layer 225, silicon nitride layer 223,
Silicon oxide layer 222 and Semiconductor substrate 200 perform etching, and to form deep trench 211, the deep trench 211 at least runs through institute
State a part for photodiode active layer 201.
Specifically, multiple etch steps can be used, appropriate etchant sacrifice layer 225, silicon nitride is respectively adopted
Layer 223, silicon oxide layer 222 and Semiconductor substrate 200, to form deep trench 211.Wherein, deep trench 211 can run through whole
Photodiode active layer 201, can also be only a part of therethrough, such as through p-type doped layer or n-type doping layer.
In embodiments of the present invention, can be by the way of single patterning technique, namely only with patterned metal grid
Grid photoresist layer 231 is mask, you can the deep trench 211 for accommodating deep trench isolation layer and metallic grid is formed, compared to existing
Need to form deep groove isolation structure and metallic grid respectively by double patterning technique in technology, technique can be efficiently reduced
Step, reduces process complexity and cost.
It is understood that the depth of the deep trench 211 can it is deeper than the photodiode active layer 201 (that is,
Through whole photodiode active layer 201), so as to obtain more preferable isolation effect, avoid sending out between different pixels region
The third contact of a total solar or lunar eclipse gives birth to the problem of carrier diffusion.
With reference to Fig. 9, deep trench isolation layer 242 is formed, the deep trench isolation layer 242 covers the inner wall of the deep trench 211.
Wherein, the material of the deep trench isolation layer 242 can include silica or silicon nitride.
The thinner thickness of the deep trench isolation layer 242, as a nonrestrictive example, can set deep trench isolation layer
242 thickness is 20 nanometers to 200 nanometers.
Specifically, the formation process of the deep trench isolation layer 242 can use atom layer deposition process (Atomic Layer
Deposition, ALD), fluid chemistry vapour deposition, plasma activated chemical vapour deposition, sub- aumospheric pressure cvd or low
Pressure chemical vapor deposition.
In embodiments of the present invention, it is preferable that the deep trench isolation layer 242 can be formed using atom layer deposition process.
Since atom layer deposition process is commonly used in carrying out the controllable film growth of atomic scale, the uniformity of deep trench isolation layer is controlled
More preferably, it is heavy compared to other also, since atom layer deposition process is to deposit to form film in layer with monatomic form membrane
Product technique, has stronger gap filling ability, can meet the demand of the depth-to-width ratio in deep trench.
With reference to Figure 10, barrier layer 244 is formed, the barrier layer 244 covers the surface of the deep trench isolation layer 242.
Specifically, the material on the barrier layer 244 can include titanium nitride (TiN), and the titanium nitride can be prevented rear
The tungsten filled in continuous technique is spread, and the accessory substance of generation produces shadow to deep trench isolation layer 242 or Semiconductor substrate 200
Ring.
Further, the titanium nitride can use TiCl4Formed.Specifically, using TiCl4The reactant of formation
Filling capacity is preferable, in the higher deep trench 211 of depth-to-width ratio numerical value, helps to reach more preferable filling effect.
With reference to Figure 11, metal is filled into the deep trench 211, to form metallic grid 226.
Specifically, chemical vapor deposition (Chemical Vapor Deposition, CVD) technique can be used, to described
Filling tungsten (W) in deep trench 211.Using W-CVD techniques, in the higher deep trench 211 of depth-to-width ratio numerical value, contribute to more
It is filled well.
In embodiments of the present invention, using chemical vapor deposition method, tungsten is filled into the deep trench, compared to physics
Gas-phase deposition, has stronger gap filling ability, can meet the demand of the depth-to-width ratio in deep trench.
In embodiments of the present invention, since the metal of metallic grid 226 is to fill to be formed into the deep trench 211,
Formed in compared with the prior art by etching, it is possible to prevente effectively from the problem of metal in etching process collapses or peels off.
Further, what is filled in deep groove isolation structure of the prior art is insulating layer, when deep groove isolation structure is subject to
Carrier diffusion may occur during damage to adjacent area, and in embodiments of the present invention, due to being filled in deep trench isolation layer
There is metal, when deep trench isolation layer is damaged, carrier can be exported with the wiring of metal, reduce diffusion harmfulness.
With reference to Figure 12, the sacrifice layer 225, the deep trench isolation layer 242, barrier layer 244 and the metal are planarized
Grid 226.
Specifically, chemically mechanical polishing (Chemical Mechanical Polishing, CMP) technique can be used to put down
The smoothization sacrifice layer 225, the deep trench isolation layer 242, barrier layer 244 and the metallic grid 226.
With reference to Figure 13, the sacrifice layer 225 after planarization is removed.
Specifically, the sacrifice layer 225 after planarization can be removed by the way of conventional removal polysilicon,
In the embodiment of the present invention, the specific method for removing polysilicon is not restricted.
With reference to Figure 14, grid protective layer 246 is formed, the grid protective layer 246 covers the metallic grid 226, described
Deep trench isolation layer 242, barrier layer 244 and the Semiconductor substrate 200.
Specifically, after using flatening process, the sacrifice layer 225, the deep trench isolation layer 242, barrier layer 244 with
, can be to the sacrifice and the top of the metallic grid 226 is exposed, and is covered using grid protective layer 246
Layer 225, the deep trench isolation layer 242, the top of barrier layer 244 and the metallic grid 226 are effectively protected.
If more specifically, the surface of the Semiconductor substrate 200 is formed with silicon oxide layer 222, the grid protection
The covering of layer 246 metallic grid 226, the deep trench isolation layer 242, barrier layer 244 and the silicon oxide layer 222.
Further, filter 252 is set between adjacent metallic grid 246.Using filter 252 can to incident light into
Row filtering forms appropriate monochromatic light to remove irrelevant light.
In embodiments of the present invention, by forming sacrifice layer on the surface of Semiconductor substrate, so in the sacrifice layer and
Deep trench is formed in Semiconductor substrate, so that the deep trench isolation layer by forming the inner wall for covering the deep trench, and to institute
Filling metal in deep trench is stated, metallic grid can be formed without patterning again after deep trench isolation layer is formed, compare
In in the prior art, deep groove isolation structure and metallic grid are formed by double patterning technique respectively, implemented using the present invention
The scheme of example, can efficiently reduce processing step, reduce process complexity and cost.Further, due to metallic grid
Metal be into the deep trench fill formed, compared with the prior art in by etch formed, it is possible to prevente effectively from etching
During metal the problem of collapsing or peeling off.Further, what is filled in deep groove isolation structure of the prior art is exhausted
Edge layer, carrier diffusion may occur when deep groove isolation structure is damaged to adjacent area, and in the embodiment of the present invention
In, due to being filled with metal in deep trench isolation layer, when deep trench isolation layer is damaged, carrier can be led with the wiring of metal
Go out, reduce diffusion harmfulness.
Other principles, specific implementation and beneficial effect on the forming method of the imaging sensor shown in Fig. 7 to Figure 14
Refer to above and shown in Fig. 1 to Fig. 5 on the forming method of imaging sensor and its corresponding device profile knot of each step
The associated description of structure, details are not described herein again.
In embodiments of the present invention, a kind of imaging sensor is additionally provided, with reference to Figure 12, which can wrap
Include：Semiconductor substrate 200, the Semiconductor substrate 200 is interior to have photodiode active layer 201；Sacrifice layer 225, positioned at institute
State the surface of Semiconductor substrate 200；Deep trench, in the sacrifice layer 225 and the Semiconductor substrate 200, the zanjon
Groove at least runs through a part for the photodiode active layer 201；Deep trench isolation layer 242, the deep trench isolation layer 242 cover
The inner wall of the deep trench；Metallic grid 226, the metallic grid 226 are filled in the deep trench.
It refer on the principle of the imaging sensor, specific implementation and beneficial effect above and shown in Fig. 6 to Figure 14
On the associated description of the forming method of imaging sensor, details are not described herein again.
Although present disclosure is as above, the present invention is not limited to this.Any those skilled in the art, are not departing from this
In the spirit and scope of invention, it can make various changes or modifications, therefore protection scope of the present invention should be with claim institute
Subject to the scope of restriction.
Claims (10)
1. a kind of forming method of imaging sensor, it is characterised in that comprise the following steps：
Semiconductor substrate is provided, there is photodiode active layer in the Semiconductor substrate；
Sacrifice layer is formed on the surface of the Semiconductor substrate；
The sacrifice layer and the Semiconductor substrate are etched, to form deep trench, the deep trench at least runs through the photoelectricity
A part for diode active layer；
Deep trench isolation layer is formed, the deep trench isolation layer covers the inner wall of the deep trench；
Metal is filled into the deep trench, to form metallic grid.
2. the forming method of imaging sensor according to claim 1, it is characterised in that further include：
Remove the sacrifice layer；
Form grid protective layer, the grid protective layer covers the metallic grid, the deep trench isolation layer and described partly leads
Body substrate；
Filter is set between adjacent metallic grid.
3. the forming method of imaging sensor according to claim 2, it is characterised in that described to remove the sacrifice layer bag
Include：
Planarize the sacrifice layer, the deep trench isolation layer and the metallic grid；
Remove the sacrifice layer after planarization.
4. the forming method of imaging sensor according to claim 1, it is characterised in that the formation deep trench isolation layer bag
Include：
The deep trench isolation layer is formed using atom layer deposition process.
5. the forming method of imaging sensor according to claim 1, it is characterised in that in the table of the Semiconductor substrate
Face is formed before sacrifice layer, is further included：
Form substrate protective layer；
Wherein, the sacrifice layer is stacked in the substrate protective layer.
6. the forming method of imaging sensor according to claim 1, it is characterised in that
The material of the sacrifice layer includes polysilicon.
7. the forming method of imaging sensor according to claim 1, it is characterised in that gold is filled into the deep trench
Before category, further include：
Barrier layer is formed, the barrier layer covers the surface of the deep trench isolation layer.
8. the forming method of imaging sensor according to claim 7, it is characterised in that
The material on the barrier layer includes titanium nitride, wherein, the titanium nitride is to use TiCl4Formed.
9. the forming method of imaging sensor according to claim 1, it is characterised in that gold is filled into the deep trench
Category includes：
Using chemical vapor deposition method, tungsten is filled into the deep trench.
A kind of 10. imaging sensor, it is characterised in that including：
Semiconductor substrate, the Semiconductor substrate is interior to have photodiode active layer；
Sacrifice layer, positioned at the surface of the Semiconductor substrate；
Deep trench, in the sacrifice layer and the Semiconductor substrate, the deep trench at least runs through the photodiode
A part for active layer；
Deep trench isolation layer, the deep trench isolation layer cover the inner wall of the deep trench；
Metallic grid, the metallic grid are filled in the deep trench.
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