CN117554290A - High-sensitivity micro-ring sensing chip and preparation method thereof - Google Patents
High-sensitivity micro-ring sensing chip and preparation method thereof Download PDFInfo
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- CN117554290A CN117554290A CN202311528405.8A CN202311528405A CN117554290A CN 117554290 A CN117554290 A CN 117554290A CN 202311528405 A CN202311528405 A CN 202311528405A CN 117554290 A CN117554290 A CN 117554290A
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- 238000002360 preparation method Methods 0.000 title description 2
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 claims abstract description 48
- 238000005253 cladding Methods 0.000 claims abstract description 33
- 229910052581 Si3N4 Inorganic materials 0.000 claims abstract description 29
- HQVNEWCFYHHQES-UHFFFAOYSA-N silicon nitride Chemical compound N12[Si]34N5[Si]62N3[Si]51N64 HQVNEWCFYHHQES-UHFFFAOYSA-N 0.000 claims abstract description 29
- 230000035945 sensitivity Effects 0.000 claims abstract description 25
- 235000012239 silicon dioxide Nutrition 0.000 claims abstract description 24
- 239000000377 silicon dioxide Substances 0.000 claims abstract description 24
- 230000010287 polarization Effects 0.000 claims abstract description 19
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 claims abstract description 16
- 229910052710 silicon Inorganic materials 0.000 claims abstract description 16
- 239000010703 silicon Substances 0.000 claims abstract description 16
- 230000003287 optical effect Effects 0.000 claims abstract description 10
- 239000000758 substrate Substances 0.000 claims abstract description 9
- 238000000034 method Methods 0.000 claims description 24
- 230000008569 process Effects 0.000 claims description 17
- 238000004519 manufacturing process Methods 0.000 claims description 10
- 238000001039 wet etching Methods 0.000 claims description 7
- 238000001259 photo etching Methods 0.000 claims description 6
- 238000005530 etching Methods 0.000 claims description 3
- 238000001514 detection method Methods 0.000 description 11
- 230000008859 change Effects 0.000 description 9
- 239000000126 substance Substances 0.000 description 7
- 238000005516 engineering process Methods 0.000 description 4
- 230000003993 interaction Effects 0.000 description 3
- 230000008878 coupling Effects 0.000 description 2
- 238000010168 coupling process Methods 0.000 description 2
- 238000005859 coupling reaction Methods 0.000 description 2
- 239000000463 material Substances 0.000 description 2
- 239000004038 photonic crystal Substances 0.000 description 2
- 239000002156 adsorbate Substances 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 238000003745 diagnosis Methods 0.000 description 1
- 238000006073 displacement reaction Methods 0.000 description 1
- 238000009826 distribution Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 230000010354 integration Effects 0.000 description 1
- 238000004377 microelectronic Methods 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000001228 spectrum Methods 0.000 description 1
Classifications
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
- G01N21/01—Arrangements or apparatus for facilitating the optical investigation
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
- G01N21/17—Systems in which incident light is modified in accordance with the properties of the material investigated
- G01N21/41—Refractivity; Phase-affecting properties, e.g. optical path length
- G01N21/4133—Refractometers, e.g. differential
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P70/00—Climate change mitigation technologies in the production process for final industrial or consumer products
- Y02P70/50—Manufacturing or production processes characterised by the final manufactured product
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- Physics & Mathematics (AREA)
- Health & Medical Sciences (AREA)
- Life Sciences & Earth Sciences (AREA)
- Chemical & Material Sciences (AREA)
- Analytical Chemistry (AREA)
- Biochemistry (AREA)
- General Health & Medical Sciences (AREA)
- General Physics & Mathematics (AREA)
- Immunology (AREA)
- Pathology (AREA)
- Investigating Or Analysing Materials By Optical Means (AREA)
- Optical Integrated Circuits (AREA)
Abstract
The invention relates to a high-sensitivity micro-ring sensing chip, which comprises: the silicon substrate is used for epitaxially growing a silicon dioxide layer to serve as a lower cladding layer of the waveguide, the lower cladding layer is provided with a removing area, a waveguide layer is epitaxially grown again on the basis of the lower cladding layer, and a grating coupler, a micro-ring resonant cavity and a silicon nitride straight waveguide for optical input and output interfaces are prepared on the waveguide layer. According to the invention, through partial removal of the lower cladding, the TM polarization state micro-ring resonant cavity suspended up and down is prepared, so that the light waves are fully contacted with the object to be detected, and the sensitivity is improved.
Description
Technical Field
The invention relates to the technical field of biosensing detection, in particular to a control method of a cascade dual-ring resonant cavity sensor based on temperature control.
Background
The optical sensor is a device for detecting based on the change of an optical signal, has the advantages of no mark, non-contact property, high sensitivity and the like, is widely applied to the fields of medical diagnosis, food detection, environment detection and the like, wherein the micro-ring sensor is a device based on waveguide evanescent wave sensing, the energy is highly concentrated near a waveguide and air interface, the optical signal is particularly sensitive to the disturbance of the refractive index of the surface of the device, the detection of the tiny change of an adsorbate can be realized, and the micro-ring sensor of the silicon-based substrate has the advantages of high integration level, small size, compatibility with a microelectronic process, small sample amount, high sensitivity, strong anti-interference capability, capability of realizing the real-time quantitative detection of the detection object and the like, and shows great commercial value.
The prior art scheme is as follows: patent application number: the sensitivity of the CN101706424B, CN107727611B micro-ring sensor is mainly determined by the waveguide structure, and since the lower cladding layer formed by the low refractive index medium (such as silicon dioxide) is usually arranged below the micro-ring, only the upper part of the micro-ring can be contacted with the measured substance, and the sensing sensitivity is limited. Complex designs are often required to increase the sensitivity of the micro-loop sensor.
In CN101706424B, the situation of cascaded micro-rings is adopted, and by means of vernier effect, the displacement of the resonance peak caused by the change of the refractive index of the environment is amplified, so that the sensitivity of the whole sensing chip is improved. In CN107727611B, by fabricating a one-dimensional photonic crystal in the waveguide, the interaction of the light wave in the waveguide with the surrounding environment is enhanced, and the sensing sensitivity is improved.
However, the above schemes all require an increase in the complexity of the chip: the number of micro-ring resonant cavities is increased in CN101706424B, and the radius difference of two micro-rings is required to be accurately designed; the one-dimensional photonic crystal is added in CN107727611B, and a high-precision micro-nano processing technology is required. These factors all lead to increased costs and reduced reliability.
Disclosure of Invention
Technical problem to be solved
The invention is based on the silicon light technology, a silicon dioxide layer is epitaxially grown on a silicon substrate as a lower cladding layer of a waveguide, and then a silicon nitride layer is epitaxially grown as a waveguide layer. And manufacturing a micro-ring resonator serving as a core sensing device on the waveguide layer, manufacturing a polarization-sensitive grating coupler, and coupling the light waves in the TM polarization state into the waveguide.
And the wet etching technology is adopted to remove the silicon dioxide lower cladding layer below the micro-ring resonant cavity, so that the interaction between the light wave in the micro-ring waveguide and substances around the waveguide is improved, and the sensing sensitivity is further improved.
Technical proposal
In order to achieve the purpose of the invention, the technical scheme adopted by the invention is as follows: a high sensitivity micro-ring sensing chip comprising: the silicon substrate is used for epitaxially growing a silicon dioxide layer to serve as a lower cladding layer of the waveguide, the lower cladding layer is provided with a removing area, a waveguide layer is epitaxially grown again on the basis of the lower cladding layer, and a grating coupler, a micro-ring resonant cavity and a silicon nitride straight waveguide for optical input and output interfaces are prepared on the waveguide layer.
Preferably, the waveguide layer is a silicon nitride layer.
Preferably, the grating couplers are all TM polarization state grating couplers.
Preferably, the micro-ring resonator is a micro-ring resonator supporting TM polarization, and the micro-ring resonator is formed of an asymmetric waveguide.
Preferably, a method for preparing a high-sensitivity micro-ring sensing chip comprises the following steps:
preparing a silicon wafer;
preparing a silicon dioxide layer on the silicon wafer through an epitaxial growth process;
preparing a silicon nitride layer on the silicon dioxide layer through an epitaxial growth process;
preparing a grating coupler, a straight waveguide and a micro-ring resonant cavity on the surface of the silicon nitride layer through a photoetching process, wherein the etching depth is smaller than the thickness of the silicon nitride layer;
removing residual silicon nitride at the inner ring of the micro-ring resonant cavity through a photoetching process to expose a silicon dioxide layer at the lower layer;
and selectively removing silicon dioxide below the micro-ring resonant cavity through a wet etching process, and completing local removal of the lower cladding and chip manufacturing.
Preferably, the waveguide section of the micro-ring resonant cavity is of an asymmetric structure, one side of the micro-ring resonant cavity is not etched completely, a thinner silicon nitride flat plate is reserved, and the other side is etched completely until the lower cladding is exposed.
Compared with the prior art, the invention has the beneficial effects that:
1. according to the invention, through partial removal of the lower cladding, the TM polarization state micro-ring resonant cavity suspended up and down is prepared, so that the light waves are fully contacted with the object to be detected, and the sensitivity is improved.
The effective refractive index of a light wave in the tm polarization state is more susceptible to change by the influence of the refractive index above and below the waveguide than the TE polarization state.
3. The waveguide section of the micro-ring resonant cavity is of an asymmetric structure, one side of the micro-ring resonant cavity is not etched completely, a thin silicon nitride flat plate is reserved, and the other side of the micro-ring resonant cavity is etched completely until the lower cladding layer is exposed, so that the silicon nitride flat plate on one side is reserved for providing mechanical support for the micro-ring resonant cavity.
4. The wet etching process is adopted to partially remove the silicon dioxide below the micro-ring resonant cavity, so that the silicon dioxide below the micro-ring resonant cavity is removed, the upper surface and the lower surface of the waveguide can be contacted with the solution of the object to be detected, and the sensitivity is improved.
Drawings
FIG. 1 is a top view and a cross-sectional view of a high sensitivity micro-ring sensor chip of the present invention;
FIG. 2 is a flow chart of a method for manufacturing a high-sensitivity micro-ring sensor chip according to the present invention;
FIG. 3 is a graph of the asymmetric micro-ring waveguide TM polarization state optical field profile of a high sensitivity micro-ring sensor chip of the present invention.
In the figure: 11. a silicon substrate; 12. a lower cladding layer; 13. a grating coupler; 14. a silicon nitride straight waveguide; 15 micro-ring resonant cavity; 16. the region is removed.
Detailed Description
The following description of the embodiments of the present invention will be made clearly and completely with reference to the accompanying drawings, in which it is apparent that the embodiments described are only some embodiments of the present invention, but not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.
As shown in fig. 1, the present invention provides a technical solution: a high sensitivity micro-ring sensing chip comprising: the silicon substrate 11, the silicon substrate 11 epitaxially grows a silicon dioxide layer as the lower cladding layer 12 of the waveguide, the lower cladding layer 12 is provided with a removal region 16, the waveguide layer is epitaxially grown again on the basis of the lower cladding layer 12, and the waveguide layer adopts a silicon nitride layer.
Grating couplers 13 for optical input and output interfaces, micro-ring resonators 15, and silicon nitride straight waveguides 14 are prepared in the waveguide layer.
The grating couplers 13 are all TM polarization grating couplers, and the effective refractive index of the TM polarization light wave is more easily changed by the influence of the refractive index above and below the waveguide than the TE polarization.
The micro-ring resonator 15 is a micro-ring resonator supporting TM polarization, and the micro-ring resonator 15 is composed of an asymmetric waveguide.
A silicon dioxide layer is epitaxially grown on a silicon substrate 11 as a lower cladding layer 12 of the waveguide, and a silicon nitride layer is again epitaxially grown as a waveguide layer.
And manufacturing a micro-ring resonant cavity 15 serving as a core sensing device on the waveguide layer, manufacturing a polarization-sensitive grating coupler 13, and coupling the light waves in the TM polarization state into the waveguide.
The wet etching technology is adopted to remove the silicon dioxide lower cladding 12 below the micro-ring resonant cavity 15, so that the interaction between the light wave in the micro-ring waveguide and the substances around the waveguide is improved, and the sensing sensitivity is further improved.
Incident light is coupled into the chip through the grating coupler 13, propagates in the TM polarization state in a straight waveguide, propagates to the location of the micro-ring resonator 15, and is coupled into the micro-ring resonator 15.
Light of a wavelength satisfying the resonance condition resonates in the micro-ring resonator 15, and shows a resonance peak in the spectrum. The final light wave is coupled out of the chip through an output interface.
The position of the resonance peak is directly related to the effective refractive index of the optical field in the micro-ring waveguide, and the effective refractive index is determined by the material, structure, upper and lower cladding refractive indexes and other factors of the waveguide.
When the solution of the target detection substance is added to the sensing chip, substances of the upper and lower cladding layers of the micro-ring resonant cavity 15 in the chip change, so that the refractive indexes of the upper and lower cladding layers change, the resonant peak moves along with the change, the movement quantity is directly related to the refractive index change quantity, and the refractive index change quantity is related to the concentration of the target detection substance, thereby realizing the sensing detection function of the substance.
Because the lower part of the waveguide of the micro-ring resonant cavity 15 is removed in the sensing chip, after the solution of the detection object is added, the upper and lower cladding layers of the waveguide are the solution, and the light field in the waveguide can be fully interacted with the detection object, so that the sensitivity of the micro-ring sensing chip is improved.
The distribution of the optical field in the TM polarization asymmetric waveguide is shown in fig. 3, and it can be seen that the light intensity is mainly distributed at the upper and lower interfaces of the waveguide, so that the light intensity can more fully act with the surrounding materials of the waveguide.
As shown in fig. 2, a method for manufacturing a micro-ring sensor chip for high sensitivity includes:
preparing a silicon wafer;
preparing a silicon dioxide layer on a silicon wafer through an epitaxial growth process, wherein the thickness of the silicon dioxide layer is greater than 4 microns;
and preparing a silicon nitride layer on the silicon dioxide layer through an epitaxial growth process, wherein the thickness is determined by the working wavelength of the chip and the waveguide parameters.
Preparing a grating coupler, a straight waveguide and a micro-ring resonant cavity on the surface of the silicon nitride layer through a photoetching process, wherein the etching depth is smaller than the thickness of the silicon nitride layer;
removing residual silicon nitride at the inner ring of the micro-ring resonant cavity through a photoetching process to expose a silicon dioxide layer at the lower layer;
and selectively removing silicon dioxide below the micro-ring resonant cavity through a wet etching process, and completing local removal of the lower cladding and chip manufacturing.
The waveguide section of the micro-ring resonant cavity is of an asymmetric structure, one side of the micro-ring resonant cavity does not etch silicon nitride completely, a thin silicon nitride flat plate is reserved, and the other side of the micro-ring resonant cavity is etched completely until the lower cladding is exposed.
When the micro-ring resonator and the lower cladding are removed by wet etching, a silicon nitride plate is left on one side to provide mechanical support for the micro-ring resonator.
By introducing the lower cladding partial removal method, the lower part of the micro-ring resonant cavity is hollowed, so that the solution of the object to be detected can flow into the cavity below, the upper part and the lower part of the micro-ring resonant cavity are ensured to be covered with the solution of the object to be detected, the light waves and the solution of the object to be detected can interact more fully, and the sensing sensitivity is improved.
The embodiments of the present invention are disclosed as preferred embodiments, but not limited thereto, and those skilled in the art will readily appreciate from the foregoing description that various extensions and modifications can be made without departing from the spirit of the present invention.
Claims (6)
1. A high sensitivity micro-ring sensing chip, comprising: the silicon substrate is used for epitaxially growing a silicon dioxide layer to serve as a lower cladding layer of the waveguide, the lower cladding layer is provided with a removing area, a waveguide layer is epitaxially grown again on the basis of the lower cladding layer, and a grating coupler, a micro-ring resonant cavity and a silicon nitride straight waveguide for optical input and output interfaces are prepared on the waveguide layer.
2. The high sensitivity micro-ring sensor chip of claim 1, wherein the waveguide layer is a silicon nitride layer.
3. The high sensitivity micro-ring sensor chip of claim 1, wherein the grating couplers are all TM polarization grating couplers.
4. The high sensitivity micro-ring sensor chip of claim 1, wherein the micro-ring resonator is a micro-ring resonator supporting TM polarization, the micro-ring resonator being composed of an asymmetric waveguide.
5. A method for manufacturing a high sensitivity micro-ring sensor chip according to any one of claims 1 to 4, comprising:
preparing a silicon wafer;
preparing a silicon dioxide layer on the silicon wafer through an epitaxial growth process;
preparing a silicon nitride layer on the silicon dioxide layer through an epitaxial growth process;
grating coupler, straight waveguide and micro-ring resonant cavity are prepared on the surface of the silicon nitride layer by photoetching process, the etching depth is smaller than the thickness of the silicon nitride layer,
removing residual silicon nitride at the inner ring of the micro-ring resonant cavity through a photoetching process to expose a silicon dioxide layer at the lower layer;
and selectively removing silicon dioxide below the micro-ring resonant cavity through a wet etching process, and completing local removal of the lower cladding and chip manufacturing.
6. The method for fabricating a high sensitivity micro-ring sensor chip according to claim 5, wherein the waveguide section of the micro-ring resonator is of an asymmetric structure, one side of the micro-ring resonator is not etched completely, a thin silicon nitride plate is left, and the other side is etched completely until the lower cladding is exposed.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202311528405.8A CN117554290A (en) | 2023-11-16 | 2023-11-16 | High-sensitivity micro-ring sensing chip and preparation method thereof |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202311528405.8A CN117554290A (en) | 2023-11-16 | 2023-11-16 | High-sensitivity micro-ring sensing chip and preparation method thereof |
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| Publication Number | Publication Date |
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| CN117554290A true CN117554290A (en) | 2024-02-13 |
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| Application Number | Title | Priority Date | Filing Date |
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| CN202311528405.8A Pending CN117554290A (en) | 2023-11-16 | 2023-11-16 | High-sensitivity micro-ring sensing chip and preparation method thereof |
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| Country | Link |
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| CN (1) | CN117554290A (en) |
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- 2023-11-16 CN CN202311528405.8A patent/CN117554290A/en active Pending
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