CN103000647A - Optical enhancement structure of CMOS (complementary metal oxide semiconductor transistor) image sensor and method for manufacturing optical enhancement structure - Google Patents
Optical enhancement structure of CMOS (complementary metal oxide semiconductor transistor) image sensor and method for manufacturing optical enhancement structure Download PDFInfo
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- CN103000647A CN103000647A CN 201210414607 CN201210414607A CN103000647A CN 103000647 A CN103000647 A CN 103000647A CN 201210414607 CN201210414607 CN 201210414607 CN 201210414607 A CN201210414607 A CN 201210414607A CN 103000647 A CN103000647 A CN 103000647A
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Abstract
The invention discloses an optical enhancement structure of a CMOS (complementary metal oxide semiconductor transistor) image sensor and a method for manufacturing the optical enhancement structure. The structure comprises a silicon substrate, a photosensitive element and a standard CMOS multilayer structure. The photosensitive element and the standard CMOS multilayer structure are arranged on the silicon substrate, and a deep groove which forms light transmission space is arranged on the photosensitive element and is surrounded by metal reflecting layers, so that incident light of the metal reflecting layers can be reflected. The optical enhancement structure and the method have the advantages that each thin metal reflecting layer is formed on the corresponding side wall of the deep groove formed on the photosensitive element, so that the incident light is completely reflected onto the photosensitive element, optical crosstalk among adjacent pixels is shielded, the intensity of incident light on the photosensitive element is enhanced, and the optical sensitivity of the CMOS image sensor and the performance and the reliability of a chip are improved.
Description
Technical field
The present invention relates to CMOS image sensor technical field, relate in particular to a kind of CMOS image sensor optical enhancement structure and preparation method.
Background technology
The CMOS image sensor is because itself and CMOS process compatible, thereby is rapidly developed.With respect to CCD technique, its technique fully and the CMOS process compatible, it is by being made in photodiode and CMOS treatment circuit on the silicon substrate together, thus on the basis of guaranteed performance decrease cost, simultaneously can increase substantially integrated level, make the higher product of pixel.
The traditional cmos image sensor is the method for using the front lighting photograph, photodiode and CMOS treatment circuit are made in the same level realization of use on the silicon substrate together, chip interconnects then is manufactured on the CMOS treatment circuit, does not carry out row's step of interconnection line on the photodiode for passing through of light.Yet the light transmission of conventional semi-conducting material is relatively poor, therefore need to all remove the medium level above the photodiode, and fill light transmissive material, to strengthen its light absorption.
Meanwhile, along with pixel dimension reduces, the spacing between the adjacent picture elements is also along with sharply reducing, and incident ray may just can enter adjacent pixel through superrefraction and Multi reflection, cause the generation of optical crosstalk, just can cause decrease resolution, the chip performance variation of pixel.Therefore, be one of technological difficulties of this area such as the amount that how to reduce optical crosstalk between the adjacent picture elements, strengthens incident light to improve pixel resolution and sensitivity.
Summary of the invention
The object of the invention is to remedy above-mentioned the deficiencies in the prior art, a kind of CMOS image sensor optical enhancement structure and preparation method are provided.
CMOS image sensor optical enhancement structure of the present invention, comprise silicon substrate and on light-sensitive element and standard CMOS sandwich construction, this light-sensitive element top has the deep trench that forms the printing opacity space, this deep trench sidewall by metallic reflector around, to be reflected into the light that is mapped to this metallic reflector.
Wherein, this sandwich construction comprises standard CMOS polysilicon layer, contact hole layer, metal interconnecting layer, via layer and connected medium layer.
Further, also have metallic reflector on the top layer of this sandwich construction, and the top layer of this sandwich construction is dielectric layer, in order to the metal interconnecting layer in the sandwich construction and metallic reflector is isolated.The purpose that metallic reflector also is set at the sandwich construction top layer is that reflection is incided the light of sandwich construction inside from the sandwich construction top, and further avoids light to the optical crosstalk of adjacent picture elements.
Further, this metallic reflection layer material comprises metal material and laminated composite materials thereof commonly used in the CMOS techniques such as Al, Cu, Pt, Ru, TaN, Ta, Ti, TiN, as Ti TiN the Al composition metal, and the thickness of this metallic reflector is 50A-5000A, it is by the PVD(physical vapour deposition (PVD), Physical Vapor Deposition), CVD(chemical vapour deposition (CVD), Chemical Vapor Deposition), the ALD(ald, Atomic Layer Deposition) etc. film technique prepare.
Further, fill transparent material in this deep trench to form light penetrating object.
Further, the formed light penetrating object of this transparent material also covers the metallic reflector of this sandwich construction top layer, and the upper surface of transparent material also is disposed with chromatic filter layer (colorfilter) and lenticule (microlens) in deep trench.
Further, this transparent material is the transparent resin material of carbon containing, hydrogen, oxygen.
Further, this light-sensitive element is photodiode.
The preparation method of CMOS image sensor optical enhancement structure of the present invention may further comprise the steps:
Step S01: utilize standard CMOS process at silicon substrate preparation light-sensitive element and be used for the sandwich construction of cmos device;
Step S02: chemical wet etching is removed the dielectric layer of light-sensitive element top, forms to have the deep trench in printing opacity space;
Step S03: utilize film-forming process to silicon chip surface plated metal reflector;
Step S04: remove the metallic reflector except the deep trench sidewall in the deep trench;
Step S05: in deep trench, fill transparent material, and realize the silicon chip planarization;
Step S06: the upper surface of transparent material is made chromatic filter layer and lenticule successively in deep trench.
Further, also comprise the step S011 that removes the passivation layer on the pixel array region that is formed by several light-sensitive elements between step S01 and the step S02, this passivation layer is the laminated construction that comprises the SiN of lower floor layer (thickness is 1000A-2000A) and upper strata SiO2 layer, and this step S011 comprises removal SiO2 layer and rests on the SiN layer and remove the SiN layer.
Further, film-forming process comprises the techniques such as PVD, CVD, ALD among the step S03.
Wherein, because step S04 need to remove the metallic reflector on a plurality of elevation plane, comprise the zone except the deep trench sidewall in deep trench bottom, the deep trench, even the top of area of isolation between the deep trench, and pixel array perimeter, therefore, this step comprises the repeatedly exposure technique of different focal planes of single or multiple photoetching.
Particularly, step S04 comprises: realize first the exposure of deep trench bottom section, expose the metallic reflector that needs etching to remove; Realize again the exposure in isolated area top metal reflector between the deep trench, expose the metallic reflector that needs etching to remove; Realize at last the metallic reflector exposure on the passivation layer of pixel array perimeter, expose the metallic reflector that needs etching to remove; Remove at last the metallic reflector of above-mentioned zone by etching.
In addition, also can be by the metallic reflector on the large tracts of land etching removal silicon chip surface plane, this is because the metallic reflector of deep trench sidewall is vertically highly very high, namely very thick, therefore, can be retained lower after etching.
In the prior art, because the dielectric layer rete of photosensitive element region top is more and complicated, simultaneously very thick, the distance of namely light arrival light-sensitive element is long, in the light transmission, have inevitable loss like this, this loss is directly proportional with the light transmission distance; Simultaneously, in the light transmission process, have the light of certain angle can incide on the deep trench sidewall, certain refraction, transmission and absorption can occur in this part light, cause crosstalking and light losing between the adjacent picture elements.
Therefore, the deep trench sidewall that optical enhancement structure of the present invention forms on light-sensitive element forms the thin metallic reflector of one deck, make incident ray reflex on the light-sensitive element fully, shielded the optical crosstalk between the adjacent picture elements, strengthened the light intensity that incides on the light-sensitive element, thereby improved the optical sensitivity of CMOS image sensor, promoted the Performance And Reliability of chip; In addition, can remove by large tracts of land the passivation layer in photoarray zone, reduce the length in light transmission path, it is larger that incident angle also becomes; Simultaneously, because light-sensitive element shortens to chromatic filter layer and lenticular distance, can accept the more incident ray of wide-angle, improve light absorpting ability.
Description of drawings
For can clearer understanding purpose of the present invention, characteristics and advantage, below with reference to accompanying drawing preferred embodiment of the present invention is described in detail, wherein:
Fig. 1 is the cutaway view of first embodiment of the invention CMOS image sensor optical enhancement structure;
Fig. 2 is the cutaway view of second embodiment of the invention CMOS image sensor optical enhancement structure;
Fig. 3 a and Fig. 3 b are the effect schematic diagrames that has or not passivation layer in the optical enhancement structure of the present invention;
Fig. 4 is the cutaway view of photodiode arrangement of the present invention zone before the preparation metallic reflector;
Fig. 5 is the cutaway view of Fig. 4 after preparation metallic reflector and other levels.
Embodiment
See also Fig. 1, among the first embodiment, the pixel structure of CMOS image sensor comprises photodiode 10 and the sandwich construction (level that is used for the standard CMOS device) on the silicon substrate 1, in the present embodiment, also has one deck grid oxic horizon 2 in the present embodiment between silicon substrate 1 and the sandwich construction, wherein, sandwich construction comprise from bottom to top polysilicon layer 3, tungsten contact hole layer 4, copper metal interconnecting layer 5 with and on other via layer, metal interconnecting layer and connected medium layer.Photodiode 10 tops have the deep trench 7 that forms the printing opacity space, deep trench 7 sidewalls by metallic reflector 6 around, to be reflected into the light that is mapped to this metallic reflector 6.Metallic reflector 6 is aluminum, and thickness is 100A, prepares by the PVD film technique.
Wherein, the interior filling transparent materials of deep trench 7 form light penetrating objects 71, and the formed light penetrating object 71 of transparent material also covers the top layer of sandwich construction, once are provided with chromatic filter layer 8 and lenticule 9 at the upper surface of deep trench 7 interior transparent materials.
The present invention comprises with the manufacture method of the pixel array that a plurality of CMOS image sensor optical enhancement structures among the first embodiment form:
Step S01: utilize standard CMOS process at silicon substrate preparation photodiode 10 and be used for the sandwich construction of cmos device, remove the passivation layer of pixel array region, this passivation layer is to comprise the SiN of lower floor layer and upper strata SiO
2The laminated construction of layer, the step of removing passivation layer comprise removes SiO
2Layer also rests on the SiN layer and removes the SiN layer;
Step S02: chemical wet etching is removed the dielectric layer of photodiode 10 tops, forms to have the deep trench 7 in printing opacity space;
Step S03: utilize the PVD film-forming process to silicon chip surface plated metal reflector 6;
Step S04: remove the metallic reflector 6 except the deep trench sidewall in the deep trench 7;
Step S05: to deep trench 7 interior filling transparent materials, and realize the silicon chip planarization;
Step S06: make successively chromatic filter layer 8 and lenticule 9 at the upper surface of deep trench 7 interior transparent materials.
Wherein, step S04 comprises: realize first the exposure of deep trench 7 bottom sections, expose the metallic reflector that needs etching to remove; Realize again the exposure in isolated area top metal reflector between the deep trench 7, expose the metallic reflector that needs etching to remove; Realize at last the metallic reflector exposure on the passivation layer of pixel array perimeter, expose the metallic reflector that needs etching to remove; Remove at last the metallic reflector of above-mentioned zone by etching.
Please continue to consult Fig. 2, among the second embodiment, the pixel structure of CMOS image sensor comprises photodiode 10 and the sandwich construction (level that is used for the standard CMOS device) on the silicon substrate 1, in the present embodiment, also has one deck grid oxic horizon 2 in the present embodiment between silicon substrate 1 and the sandwich construction, wherein, sandwich construction comprise from bottom to top polysilicon layer 3, tungsten contact hole layer 4, copper metal interconnecting layer 5 with and on other via layer, metal interconnecting layer and connected medium layer.Photodiode 10 tops have the deep trench 7 that forms the printing opacity space, deep trench 7 sidewalls by metallic reflector 6 around, to be reflected into the light that is mapped to this metallic reflector 6; Also prepare layer of metal reflector 6 on the top layer of sandwich construction, incide the light of sandwich construction inside in order to reflection from the sandwich construction top, and further avoid light to the optical crosstalk of adjacent picture elements.Metallic reflector 6 is the titanium material, and thickness is 500A, prepares by the PVD film technique.
Wherein, the interior filling transparent materials of deep trench 7 form light penetrating objects 71, and the formed light penetrating object 71 of transparent material also covers the top layer of sandwich construction, once are provided with chromatic filter layer 8 and lenticule 9 at the upper surface of deep trench 7 interior transparent materials.
Please consult simultaneously Fig. 3 a and 3b, the sandwich construction among Fig. 3 a has been Duoed one deck passivation layer 11 than the sandwich construction of Fig. 3 b, as seen, remove passivation layer after, the light A incident angle of pixel becomes larger, light distance B then becomes shorter, can improve the Optical Absorption ability.
Then, please consult simultaneously Fig. 4 and Fig. 5.
Among Fig. 4, the passivation layer 12 of photodiode arrangement zone C-C is removed first, and wherein, passivation layer 12 comprises the SiN of lower floor layer and the upper strata SiO that successively generates
2The laminated construction of layer, this removal passivation layer step comprise removes SiO
2Layer also rests on the SiN layer and removes the SiN layer; At all levels being omitted of then preparing the sandwich construction 31 between pixel among the deep trench 7(figure above each photodiode 10 drawn).
Among Fig. 5, photodiode arrangement zone C-C has prepared light penetrating object, metallic reflector 6, chromatic filter layer 8 and lenticule 9.As seen from the figure, the top layer of sandwich construction 31 is dielectric layer 14, and purpose is for the metal interconnecting layer in the sandwich construction and metallic reflector 6 are spaced from each other and protect; Simultaneously, isolated area top metal reflector 6 also is removed a part between the deep trench 7, and purpose is to avoid the series connection between adjacent picture elements to disturb.
Wherein, the transparent material of above-described embodiment is selected the transparent resin material of this area carbon containing commonly used, hydrogen, oxygen.
Claims (12)
1. CMOS image sensor optical enhancement structure, it is characterized in that: it comprise silicon substrate and on light-sensitive element and standard CMOS sandwich construction, this light-sensitive element top has the deep trench that forms the printing opacity space, this deep trench sidewall by metallic reflector around, to be reflected into the light that is mapped to this metallic reflector.
2. CMOS image sensor optical enhancement structure according to claim 1, it is characterized in that: this sandwich construction comprises standard CMOS polysilicon layer, contact hole layer, metal interconnecting layer, via layer and connected medium layer.
3. CMOS image sensor optical enhancement structure according to claim 1, it is characterized in that: also have metallic reflector on the top layer of this sandwich construction, and the top layer of this sandwich construction is dielectric layer, in order to the metal interconnecting layer in the sandwich construction and metallic reflector is isolated.
4. CMOS image sensor optical enhancement structure according to claim 3, it is characterized in that: this metallic reflection layer material comprises Al, Cu, Pt, Ru, TaN, Ta, Ti, TiN and laminated composite materials thereof, and the thickness of this metallic reflector is 50A-5000A.
5. CMOS image sensor optical enhancement structure according to claim 3 is characterized in that: fill transparent material in this deep trench to form light penetrating object.
6. CMOS image sensor optical enhancement structure according to claim 5, it is characterized in that: the formed light penetrating object of this transparent material also covers the metallic reflector of this sandwich construction top layer, and the upper surface of transparent material also is disposed with chromatic filter layer and lenticule in deep trench.
7. CMOS image sensor optical enhancement structure according to claim 6, it is characterized in that: this transparent material is the transparent resin material of carbon containing, hydrogen, oxygen, and this light-sensitive element is photodiode.
8. the preparation method of the described CMOS image sensor of claim 1 an optical enhancement structure is characterized in that, may further comprise the steps:
Step S01: utilize standard CMOS process at silicon substrate preparation light-sensitive element and be used for the sandwich construction of cmos device;
Step S02: chemical wet etching is removed the dielectric layer of light-sensitive element top, forms to have the deep trench in printing opacity space;
Step S03: utilize film-forming process to silicon chip surface plated metal reflector;
Step S04: remove the metallic reflector except the deep trench sidewall in the deep trench;
Step S05: in deep trench, fill transparent material, and realize the silicon chip planarization;
Step S06: the upper surface of transparent material is made chromatic filter layer and lenticule successively in deep trench.
9. the preparation method of CMOS image sensor optical enhancement structure according to claim 8, it is characterized in that: also comprise the step S011 that removes the passivation layer on the pixel array region that is comprised of several light-sensitive elements between step S01 and the step S02, this passivation layer is to comprise the SiN of lower floor layer and upper strata SiO
2The laminated construction of layer, this step S011 comprise removes SiO
2Layer also rests on the SiN layer and removes the SiN layer.
10. the preparation method of CMOS image sensor optical enhancement structure according to claim 8, it is characterized in that: film-forming process comprises PVD, CVD, ALD among the step S03.
11. the preparation method of CMOS image sensor optical enhancement structure according to claim 8 is characterized in that: step S04 comprises the repeatedly exposure technique of different focal planes of single or multiple photoetching.
12. the preparation method of CMOS image sensor optical enhancement structure according to claim 11, it is characterized in that: step S04 comprises the exposure that realizes first the deep trench bottom section, exposes the metallic reflector that needs etching to remove; Realize again the exposure in isolated area top metal reflector between the deep trench, expose the metallic reflector that needs etching to remove; Realize at last the metallic reflector exposure on the passivation layer of pixel array perimeter, expose the metallic reflector that needs etching to remove; Remove at last the metallic reflector of above-mentioned zone by etching.
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN103066089A (en) * | 2012-12-26 | 2013-04-24 | 上海集成电路研发中心有限公司 | Complementary metal oxide semiconductor (COMS) image sensor pixel structure and manufacturing method thereof |
| CN110112152A (en) * | 2018-02-01 | 2019-08-09 | 力晶科技股份有限公司 | Image Sensor with class photoconductive tube structure |
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| JP4123060B2 (en) * | 2003-06-11 | 2008-07-23 | ソニー株式会社 | Solid-state imaging device and manufacturing method thereof |
| CN100524786C (en) * | 2005-08-18 | 2009-08-05 | 联华电子股份有限公司 | Image sensor from CMOS transistors, and manufacturing method |
| CN100495715C (en) * | 2006-08-25 | 2009-06-03 | 联华电子股份有限公司 | Image sensing device and manufacturing method thereof |
| CN102593138B (en) * | 2012-01-19 | 2014-09-17 | 北京思比科微电子技术股份有限公司 | CMOS image sensor and manufacturing method thereof |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN103066089A (en) * | 2012-12-26 | 2013-04-24 | 上海集成电路研发中心有限公司 | Complementary metal oxide semiconductor (COMS) image sensor pixel structure and manufacturing method thereof |
| CN103066089B (en) * | 2012-12-26 | 2018-08-28 | 上海集成电路研发中心有限公司 | CMOS image sensor pixel structure and its manufacturing method |
| CN110112152A (en) * | 2018-02-01 | 2019-08-09 | 力晶科技股份有限公司 | Image Sensor with class photoconductive tube structure |
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