CN117950265A - Lithium niobate nano structure and preparation method and application thereof - Google Patents
Lithium niobate nano structure and preparation method and application thereof Download PDFInfo
- Publication number
- CN117950265A CN117950265A CN202410024781.1A CN202410024781A CN117950265A CN 117950265 A CN117950265 A CN 117950265A CN 202410024781 A CN202410024781 A CN 202410024781A CN 117950265 A CN117950265 A CN 117950265A
- Authority
- CN
- China
- Prior art keywords
- lithium niobate
- etching
- photoresist
- layer
- nanostructure
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Pending
Links
- GQYHUHYESMUTHG-UHFFFAOYSA-N lithium niobate Chemical compound [Li+].[O-][Nb](=O)=O GQYHUHYESMUTHG-UHFFFAOYSA-N 0.000 title claims abstract description 171
- 239000002086 nanomaterial Substances 0.000 title claims abstract description 109
- 238000002360 preparation method Methods 0.000 title description 4
- 238000005530 etching Methods 0.000 claims abstract description 120
- 238000000034 method Methods 0.000 claims abstract description 70
- 229920002120 photoresistant polymer Polymers 0.000 claims abstract description 48
- 239000000758 substrate Substances 0.000 claims abstract description 13
- 238000006243 chemical reaction Methods 0.000 claims abstract description 11
- VNWKTOKETHGBQD-UHFFFAOYSA-N methane Chemical compound C VNWKTOKETHGBQD-UHFFFAOYSA-N 0.000 claims description 30
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 claims description 21
- FAQYAMRNWDIXMY-UHFFFAOYSA-N trichloroborane Chemical compound ClB(Cl)Cl FAQYAMRNWDIXMY-UHFFFAOYSA-N 0.000 claims description 21
- 239000007789 gas Substances 0.000 claims description 20
- 238000009616 inductively coupled plasma Methods 0.000 claims description 16
- 239000000460 chlorine Substances 0.000 claims description 15
- 229910052801 chlorine Inorganic materials 0.000 claims description 15
- ZAMOUSCENKQFHK-UHFFFAOYSA-N Chlorine atom Chemical compound [Cl] ZAMOUSCENKQFHK-UHFFFAOYSA-N 0.000 claims description 13
- 239000001257 hydrogen Substances 0.000 claims description 11
- 229910052739 hydrogen Inorganic materials 0.000 claims description 11
- 239000010409 thin film Substances 0.000 claims description 8
- 238000010894 electron beam technology Methods 0.000 claims description 7
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 claims description 6
- 239000011248 coating agent Substances 0.000 claims description 6
- 238000000576 coating method Methods 0.000 claims description 6
- 239000000463 material Substances 0.000 claims description 6
- 238000005566 electron beam evaporation Methods 0.000 claims description 5
- 229920003229 poly(methyl methacrylate) Polymers 0.000 claims description 5
- 239000004926 polymethyl methacrylate Substances 0.000 claims description 5
- 239000013078 crystal Substances 0.000 claims description 4
- 238000005086 pumping Methods 0.000 claims description 4
- 238000001755 magnetron sputter deposition Methods 0.000 claims description 3
- 229910052757 nitrogen Inorganic materials 0.000 claims description 3
- 230000005693 optoelectronics Effects 0.000 claims description 3
- 238000002207 thermal evaporation Methods 0.000 claims description 3
- 229920001486 SU-8 photoresist Polymers 0.000 claims description 2
- 239000010410 layer Substances 0.000 description 49
- 238000001878 scanning electron micrograph Methods 0.000 description 22
- 230000000052 comparative effect Effects 0.000 description 21
- 229920001940 conductive polymer Polymers 0.000 description 15
- KZBUYRJDOAKODT-UHFFFAOYSA-N Chlorine Chemical compound ClCl KZBUYRJDOAKODT-UHFFFAOYSA-N 0.000 description 8
- 238000001312 dry etching Methods 0.000 description 8
- CSCPPACGZOOCGX-UHFFFAOYSA-N Acetone Chemical compound CC(C)=O CSCPPACGZOOCGX-UHFFFAOYSA-N 0.000 description 6
- KFZMGEQAYNKOFK-UHFFFAOYSA-N Isopropanol Chemical compound CC(C)O KFZMGEQAYNKOFK-UHFFFAOYSA-N 0.000 description 6
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 5
- 238000000151 deposition Methods 0.000 description 5
- 239000003921 oil Substances 0.000 description 5
- 229910052814 silicon oxide Inorganic materials 0.000 description 5
- 230000008021 deposition Effects 0.000 description 4
- 239000010408 film Substances 0.000 description 4
- 230000000694 effects Effects 0.000 description 3
- 238000005516 engineering process Methods 0.000 description 3
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 3
- 238000001039 wet etching Methods 0.000 description 3
- NTIZESTWPVYFNL-UHFFFAOYSA-N Methyl isobutyl ketone Chemical compound CC(C)CC(C)=O NTIZESTWPVYFNL-UHFFFAOYSA-N 0.000 description 2
- 239000012790 adhesive layer Substances 0.000 description 2
- 239000006227 byproduct Substances 0.000 description 2
- 125000001309 chloro group Chemical group Cl* 0.000 description 2
- 238000004140 cleaning Methods 0.000 description 2
- 239000008367 deionised water Substances 0.000 description 2
- 229910021641 deionized water Inorganic materials 0.000 description 2
- 238000000609 electron-beam lithography Methods 0.000 description 2
- 239000003292 glue Substances 0.000 description 2
- 230000003287 optical effect Effects 0.000 description 2
- 230000000737 periodic effect Effects 0.000 description 2
- 238000001020 plasma etching Methods 0.000 description 2
- VEXZGXHMUGYJMC-UHFFFAOYSA-M Chloride anion Chemical compound [Cl-] VEXZGXHMUGYJMC-UHFFFAOYSA-M 0.000 description 1
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 description 1
- 238000009825 accumulation Methods 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 238000005229 chemical vapour deposition Methods 0.000 description 1
- 230000001419 dependent effect Effects 0.000 description 1
- 150000002431 hydrogen Chemical class 0.000 description 1
- 238000010884 ion-beam technique Methods 0.000 description 1
- 239000007788 liquid Substances 0.000 description 1
- 238000003754 machining Methods 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 238000005459 micromachining Methods 0.000 description 1
- 238000002161 passivation Methods 0.000 description 1
- 238000000059 patterning Methods 0.000 description 1
- 230000005622 photoelectricity Effects 0.000 description 1
- 239000002994 raw material Substances 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- 238000010897 surface acoustic wave method Methods 0.000 description 1
Landscapes
- Drying Of Semiconductors (AREA)
Abstract
The invention provides a method for preparing a lithium niobate nanostructure, which comprises the following steps: (1) Forming a photoresist layer on the lithium niobate layer with the substrate, and then exposing, developing and fixing the photoresist layer to form a photoresist layer with a desired pattern structure; (2) forming a mask layer on the structure obtained in the step (1); (3) Photoresist stripping is carried out on the structure obtained in the step (2) to obtain a mask layer with a desired pattern structure; (4) And (3) placing the structure obtained in the step (3) in etching equipment, and etching lithium niobate by using a mixed atmosphere to prepare the lithium niobate nano structure. The invention also provides a lithium niobate nano structure and application of the lithium niobate nano structure prepared by the method in a nonlinear frequency conversion device, a photoelectric device or a lens of lithium niobate. The method can prepare the lithium niobate nano structure with high sharpness and high aspect ratio.
Description
Technical Field
The invention belongs to the micro-nano processing and photoelectric field. In particular, the invention relates to lithium niobate nanostructures, and a preparation method and application thereof.
Background
The lithium niobate monocrystal material has unique photoelectric, piezoelectric, ferroelectric and other characteristics, and has wide application in surface acoustic wave device, photoelectric modulator, nonlinear frequency conversion and other fields. Compared with a film lithium niobate material without etching, the etching of the surface of the lithium niobate film into a nano structure has better nonlinear frequency conversion enhancement capability, and the higher the inclination angle of the super surface side edge is, the better the nonlinear efficiency is. But the processing of lithium niobate nanostructures with high tilt angles remains an international challenge.
For the fabrication of lithium niobate nanostructures in general, micromachining, laser machining etching, dry etching, wet etching may be used. Among them, wet etching and dry etching are two methods which are relatively commonly used in optics, but wet etching has poor anisotropy and etching rate is slow. Conventional dry etching such as focused ion beam etching can only be performed for small area processing preparation and control of the processing process is difficult. This limits the wide range of applications of lithium niobate nanostructures.
As one of the raw materials of the nonlinear frequency conversion device, the etching angle of lithium niobate has a great influence on the performance of the device. Therefore, a method for etching a lithium niobate nanostructure is urgently needed at present, which can etch a lithium niobate pattern with steep and smooth side wall and high depth-to-width ratio.
Disclosure of Invention
The invention aims to provide a method for preparing a lithium niobate nano structure, which can etch a lithium niobate graph with steep and smooth side wall and high depth-to-width ratio.
It is another object of the present invention to provide the use of the lithium niobate nanostructures prepared by the method of the present invention in nonlinear frequency conversion devices, optoelectronic devices or lenses of lithium niobate.
The above object of the present invention is achieved by the following means.
In the context of the present invention, the term "size of the lithium niobate nanostructure" refers to the distance between two furthest points in the cross section of the lithium niobate nanostructure.
In the context of the present invention, the term "aspect ratio" refers to the ratio of the height of the lithium niobate nanostructure to the size of the lithium niobate nanostructure.
In the context of the present invention, the term "tilt angle" refers to the degree of the angle θ of the side wall to the bottom wall of the lithium niobate nanostructure, as shown in fig. 2.
In the context of the present invention, the term "stopping the etching apparatus" means stopping the passage of all gases including chlorine, boron trichloride, hydrogen and auxiliary gases, but other parameters of the apparatus (such as etching temperature, etching pressure, radio frequency power and ICP power) remain unchanged at the original desired operating values.
In a first aspect, the present invention provides a method for preparing lithium niobate nanostructures, comprising the steps of:
(1) Forming a photoresist layer on the lithium niobate layer with the substrate, and then exposing, developing and fixing the photoresist layer to form a photoresist layer with a desired pattern structure;
(2) Forming a mask layer on the structure obtained in the step (1);
(3) Photoresist stripping is carried out on the structure obtained in the step (2) to obtain a mask layer with a desired pattern structure;
(4) Placing the structure obtained in the step (3) in etching equipment, and etching lithium niobate by using mixed atmosphere to prepare a lithium niobate nano structure;
Wherein the mixed atmosphere comprises chlorine, boron trichloride, hydrogen and an auxiliary gas; the auxiliary gas is methane and/or nitrogen.
The inventors of the present application have unexpectedly found that a lithium niobate pattern having steep and smooth side walls can be etched when the etching atmosphere is a multicomponent mixed atmosphere including chlorine gas, boron trichloride, hydrogen gas and an assist gas. Without wishing to be bound by theory, this may be because the chloride ion concentration may be reduced after adding boron trichloride to the etching gas chlorine, thereby achieving an effect of reducing the reaction rate; meanwhile, the byproducts generated by the reaction of lithium niobate and chlorine can be reduced by hydrogen, so that the hydrogen introduced in the etching process can remove the byproducts. In addition, in consideration of the problem of sidewall roughness, the methane or nitrogen introduced in the application can perform sidewall passivation, thereby reducing the roughness. By the organic combination of the four gases, the application etches the high-quality lithium niobate nano-structure array.
In the invention, the specific pattern of the pattern structure further formed by exposing, developing and fixing the photoresist layer does not influence the etching of the high-quality lithium niobate nanostructure array by the method. That is, the technical effects (such as steep sidewall and high aspect ratio) of the present invention are not relevant to the specific pattern structure, and are more dependent on the control of parameters (such as etching gas) during etching. Therefore, the process of forming the pattern structure of the photoresist is not particularly limited in the present invention, and exposure, development and fixing methods conventional in the art may be employed.
Preferably, in the method according to the present invention, in the case where the volume flow units of the respective gases are identical, the ratio of the volume flows (sccm) of the chlorine gas, the boron trichloride, the hydrogen gas and the auxiliary gas is chlorine gas: boron trichloride: hydrogen gas: assist gas= (4-6): (12-20): (6-11): (2-8).
Preferably, in the method of the present invention, the etching of lithium niobate in step (4) using a mixed atmosphere is performed under the following conditions:
The etching temperature is-20-40 ℃, the etching pressure is 5-20 millitorr, the radio frequency power is 40-80W and the ICP power is 400-1000W.
The method optimizes various conditions including etching temperature, etching pressure, radio frequency power and ICP power, and further improves the etching dip angle so as to improve parameters such as depth-to-width ratio and the like.
Preferably, in the method of the present invention, the etching of lithium niobate in the step (4) using a mixed atmosphere is performed by a method comprising the steps of:
(4-1) coating a pumping oil layer on the bottom of the substrate of the structure obtained in the step (3), then placing the substrate in etching equipment, and introducing mixed atmosphere into the etching equipment for etching, wherein the etching is performed intermittently;
(4-2) after the etching is completed, removing the residual mask layer.
In the etching process, the etching equipment is intermittently stopped, for example, the etching equipment is stopped for 2-6 minutes after 1-3 minutes of etching.
The method of the invention can selectively and intermittently stop the operation of equipment in the dry etching process, thus effectively controlling the etching speed, effectively improving the selection ratio and reducing the roughness. The method can use chemical solution to clean and remove the residual mask layer on the surface of the sample. The cleaning of the residual mask may be performed using a dedicated etching solution for the corresponding mask, such as a Cr removing solution for removing Cr mask exclusively, a BOE solution for removing silicon oxide exclusively, or the like.
Preferably, in the method of the present invention, the lithium niobate is selected from a lithium niobate single crystal, a lithium niobate thin film, a MgO-, mn 2O5 -, or Fe 2O3 -doped lithium niobate single crystal, or a MgO-, mn 2O5 -, or Fe 2O3 -doped lithium niobate thin film.
Preferably, in the method of the present invention, the photoresist is an electron beam photoresist or an ultraviolet photoresist.
Preferably, in the method of the present invention, the electron beam photoresist is PMMA glue or Zep glue.
Preferably, in the method of the present invention, the ultraviolet photoresist is AZ photoresist or SU8 photoresist.
Preferably, in the method of the present invention, the mask layer is made of one or more materials selected from Al, cr, siO 2 or Mo.
Preferably, in the method of the present invention, the thickness of the mask layer is10 nm to 600nm.
Preferably, in the method of the present invention, the ratio of the thickness of the lithium niobate layer to the thickness of the mask layer is the lithium niobate layer: mask layer= (1-8): 1.
Preferably, in the method of the present invention, the forming of the mask layer in the step (2) is performed by an electron beam evaporation method, a magnetron sputtering method, or a thermal evaporation method.
Preferably, in the method of the present invention, the etching apparatus is an inductively coupled plasma etching apparatus.
Preferably, in the method of the present invention, the aspect ratio of the lithium niobate nanostructure is (1 to 5): 1, a step of; more preferably, the aspect ratio of the lithium niobate nanostructure is (4-5): 1.
Preferably, in the method of the present invention, the inclination angle of the lithium niobate nanostructure is 80 to 90 °; more preferably, the tilt angle of the lithium niobate nanostructure is 85 to 90 °.
In a second aspect, the present invention provides a lithium niobate nanostructure prepared by the method of the present invention.
In a third aspect, the present invention provides an application of the lithium niobate nanostructure prepared by the method of the present invention in a nonlinear frequency conversion device, an optoelectronic device or a lens of lithium niobate.
In a specific embodiment of the invention, the optical exposure is performed on the surface of lithium niobate, comprising the following steps:
(1) Sequentially cleaning the surface of the lithium niobate for 3 minutes by using acetone, alcohol and water;
(2) Coating a layer of photoresist on the washed lithium niobate material;
(3) Exposing the sample by using an exposure device to obtain a periodically arranged structure;
The exposure mode includes but is not limited to electron beam exposure technology, ultraviolet exposure technology and other laser direct writing technology.
In a specific embodiment of the invention, preparing the mask layer comprises the steps of: depositing a mask layer using a deposition apparatus; wherein the deposition device is selected from an electron beam evaporation device or a chemical vapor deposition device, such as a magnetron sputtering deposition device or a thermal evaporation deposition device.
In a specific embodiment of the present invention, the etching of lithium niobate in a mixed atmosphere to produce lithium niobate nanostructures comprises the steps of:
(1) Coating a layer of pumping oil on the bottom of a sample, and firstly, enabling etching equipment to run for ten minutes in an idle procedure to enable atmosphere in the equipment to be active;
(2) Putting a pre-etched sample lithium niobate to perform one round of multi-component gas etching;
(3) Putting a formal sample into the container, and performing formal multi-component gas etching;
the oil pumping is used for conducting heat, so that the etching selectivity is not deteriorated due to temperature accumulation in the etching process. In addition, the equipment is stopped intermittently during the etching process, so that the temperature is not accumulated too high, and thus a good etching morphology is maintained.
The invention has the following beneficial effects:
The method can prepare the lithium niobate nano structure with high sharpness and high aspect ratio. The lithium niobate nanostructures of the present invention may be used in photonic applications such as electrodeless resonance to improve nonlinear efficiency. The method has great significance for improving the performance of devices such as nanometer processing and photoelectricity based on lithium niobate materials.
Drawings
Embodiments of the present invention are described in detail below with reference to the attached drawing figures, wherein:
FIG. 1 shows a flow chart of a method for etching lithium niobate nanostructures, according to one particular embodiment of the invention;
Fig. 2 shows an SEM image of a high-steep lithium niobate nanostructure prepared according to example 1 of the present invention;
Fig. 3A shows an SEM image of the lithium niobate nanostructure prepared in comparative example 1;
fig. 3B shows an SEM image of the high-steep lithium niobate nanostructure prepared according to example 2 of the present invention;
FIG. 4A shows an SEM image of a lithium niobate nanostructure prepared by etching chlorine gas, boron trichloride, and hydrogen gas as a multicomponent mixed atmosphere;
FIG. 4B shows an SEM image of a lithium niobate nanostructure prepared by etching chlorine gas, boron trichloride, and methane as a multicomponent mixed atmosphere;
FIG. 4C shows an SEM image of a lithium niobate nanostructure prepared by etching chlorine, methane and hydrogen as a multicomponent mixed atmosphere;
FIG. 5 shows an SEM image of a lithium niobate nanostructure prepared with a gas ratio outside this range;
FIG. 6A shows SEM images of lithium niobate nanostructures prepared at different etching temperatures;
FIG. 6B shows SEM images of lithium niobate nanostructures prepared at different etching ICP powers;
FIG. 6C shows SEM images of lithium niobate nanostructures prepared at different etching RF powers;
fig. 6D shows SEM images of the lithium niobate nanostructures prepared at different etching pressures.
Detailed Description
The following detailed description of the invention is provided in connection with the accompanying drawings that are presented to illustrate the invention and not to limit the scope thereof.
Example 1
Fig. 1 shows a flow chart of a method for etching lithium niobate nanostructures according to embodiment 1 of the invention. The lithium niobate selected in this example is an X-cut lithium niobate thin film having a silicon oxide substrate, wherein the thickness of the lithium niobate thin film is 300nm.
First, electron beam resist PMMA was spin-coated on a lithium niobate film having a silicon oxide substrate to form a resist layer having a thickness of 200nm. After coating, the samples were baked. To prevent charging, a conductive polymer layer, i.e., a water-soluble conductive paste, is spin-coated on the photoresist layer. The pattern was exposed using an e-beam lithography system, after which the sample was rinsed with deionized water to remove the water-soluble conductive adhesive layer, then developed in an organic developer MIBK: ipa=1:3 and fixed in isopropyl alcohol, resulting in a hole structure with a periodic arrangement, as shown in fig. 1 a-b. The period of the cylindrical hole is 500nm, the diameter is 300nm, and the height is 200nm.
Thereafter, cr having a thickness of 60nm was deposited on the surface by electron beam evaporation as a mask layer, as shown in fig. 1 c. Subsequently, acetone is used for stripping, so that a patterned mask layer is obtained, as shown in fig. 1 d.
Finally, dry etching was performed in an ICP-RIE system with a multicomponent mixed atmosphere to etch lithium niobate, as shown in FIG. 1 e. The multi-component mixed atmosphere comprises chlorine, boron trichloride, hydrogen and methane; wherein the ratio of the volume flow rates (sccm) of chlorine, boron trichloride, hydrogen and methane is chlorine: boron trichloride: hydrogen gas: methane=4: 15:10:4. the etching is performed under the following conditions: the etching temperature was-20 ℃, the etching pressure was 10 millitorr, the Radio Frequency (RF) power was 40W and the ICP power was 500W. The dry etching includes the steps of: (i) Firstly, the etching equipment runs for a period of time to activate the equipment, so that the equipment can stably run; (ii) pre-etching: the clean lithium niobate sample is used for pre-etching, and the bottom of the sample (namely the bottom of the substrate) needs to be coated with pump oil to dissipate heat of the sample, so that higher roughness caused by overhigh temperature is avoided; (iii) formal etching: and etching the lithium niobate structure by adopting the multicomponent mixed atmosphere, wherein the speed is 30nm/min. To obtain a lithium niobate pattern with a depth of about 300nm, the total etching time was 10min. However, in consideration of the problem that the temperature is accumulated during the reaction process to cause the roughness to be too high, the embodiment operates the program according to one minute of etching and two minutes of stopping the etching equipment. Thus, a complete set of procedures takes 30 minutes. Finally, the mask is removed with a Cr-removing solution to obtain the final sample, as shown in fig. 1 f.
Fig. 2 shows an SEM image of a high-steep lithium niobate nanostructure prepared according to example 1 of the present invention. Fig. 2 shows that the aspect ratio of the lithium niobate nanostructure is 1:1, the tilt angle θ of the lithium niobate nanostructure is 85 °.
Example 2
The lithium niobate selected in this example is an X-cut lithium niobate thin film having a silicon oxide substrate, wherein the thickness of the lithium niobate thin film is 300nm.
First, electron beam resist PMMA was spin-coated on a lithium niobate film having a silicon oxide substrate to form a resist layer having a thickness of 300nm. After coating, the samples were baked. To prevent charging, a conductive polymer layer, i.e., a water-soluble conductive paste, is spin-coated on the photoresist layer. The pattern was exposed using an electron beam lithography system, after which the sample was rinsed with deionized water to remove the water-soluble conductive adhesive layer, then developed in an organic developer MIBK: ipa=1:3 and fixed in isopropyl alcohol, resulting in a hollow hexagonal structure with a periodic arrangement. The diameter of the holes of the structure is 100nm, the width of the outer hexagon is 100nm, the total diameter of the hexagon is 500nm, and the height is 300nm.
Thereafter, cr having a thickness of 70nm was deposited as a mask layer on the surface by electron beam evaporation. And then, carrying out stripping by adopting acetone to obtain the patterned mask layer.
Finally, dry etching was performed in an ICP-RIE system with a multicomponent mixed atmosphere to etch lithium niobate. The multi-component mixed atmosphere comprises chlorine, boron trichloride, hydrogen and methane; wherein the ratio of the volume flow rates (sccm) of chlorine, boron trichloride, hydrogen and methane is chlorine: boron trichloride: hydrogen gas: methane=6: 15:7:5. the etching is performed under the following conditions: the etching temperature was 10deg.C, etching pressure was 5 mTorr, radio frequency power was 50W, and ICP power was 700W. The dry etching includes the steps of: (i) Firstly, the etching equipment runs for a period of time to activate the equipment, so that the equipment can stably run; (ii) pre-etching: the clean lithium niobate sample is used for pre-etching, and the bottom of the sample (namely the bottom of the substrate) needs to be coated with pump oil to dissipate heat of the sample, so that higher roughness caused by overhigh temperature is avoided; (iii) formal etching: and etching the lithium niobate structure by adopting the multicomponent mixed atmosphere, wherein the speed is 30nm/min. To obtain a lithium niobate pattern with a depth of about 300nm, the total etching time was 10min. However, in consideration of the problem that the temperature is accumulated during the reaction process to cause the roughness to be too high, the embodiment operates the program according to one minute of etching and two minutes of stopping the etching equipment. Thus, a complete set of procedures takes 30 minutes. Finally, removing the mask by using Cr removing liquid to obtain a final sample.
Fig. 3B shows an SEM image of the high-steep lithium niobate nanostructure prepared according to example 2 of the present invention. Fig. 3 shows that the aspect ratio of the lithium niobate nanostructure is 4:1, the tilt angle θ of the lithium niobate nanostructure is 85 °.
Example 3
Exploring the influence of etching temperature on lithium niobate nano structure
The procedure of this example was the same as in example 1, except that the pattern structure formed by exposing, developing and fixing the photoresist layer was different from example 1, and three etching temperatures (0 ℃, 20 ℃ and 50 ℃ respectively) were investigated in this example. Specifically, the pattern structure formed on the photoresist layer in this embodiment is a hollow hexagon, wherein the circle diameter of the center is 200nm, the side length of the hexagon is 200nm, the width is 100nm, and the period is 600nm.
Fig. 6A shows SEM images of the lithium niobate nanostructures prepared at 0 ℃, 20 ℃ and 50 ℃, respectively. Specifically, fig. 6A shows: when the etching temperature is 0 ℃, the depth-to-width ratio of the lithium niobate nano structure is 2:1, the inclination angle theta of the lithium niobate nano structure is 82 degrees; when the etching temperature is 20 ℃, the depth-to-width ratio of the lithium niobate nano structure is 2:1, the inclination angle theta of the lithium niobate nano structure is 80 degrees; and when the etching temperature is 50 ℃, the aspect ratio of the lithium niobate nano structure is 2:1, the tilt angle θ of the lithium niobate nanostructure is only 75 °. It can be seen that lithium niobate nanostructures of high aspect ratio and high sharpness can be obtained when the etching temperature is within the range required by the present invention (i.e., -20-40 ℃). And when the etching temperature is too high, such as 50 ℃, the etching dip angle becomes small, which can affect the performance of the lithium niobate optical device.
Example 4
Exploring the influence of etching ICP power on lithium niobate nano structure
The procedure of this example was the same as in example 1, except that the pattern structure formed by exposing, developing and fixing the photoresist layer was different from example 1, and four ICP powers (400W, 600W, 800W and 1200W, respectively) were investigated in this example. Specifically, the pattern structure formed on the photoresist layer in this embodiment is petal-shaped. Wherein, the long half shaft of the petal ellipse is 400nm, the short half shaft is 200nm, and the period is 1500nm.
Fig. 6B shows SEM images of the lithium niobate nanostructures prepared at 400W, 600W, 800W, and 1200W, respectively. Specifically, fig. 6B shows: when the ICP power is 400W, the aspect ratio of the lithium niobate nanostructure is 1:1, the inclination angle theta of the lithium niobate nano structure is 82 degrees; when the ICP power is 600W, the aspect ratio of the lithium niobate nanostructure is 1:1, the inclination angle theta of the lithium niobate nano structure is 80 degrees; when the ICP power is 800W, the aspect ratio of the lithium niobate nano structure is 1:1, the tilt angle θ of the lithium niobate nanostructure is 82 °. It can be seen that lithium niobate nanostructures of high aspect ratio and high sharpness can be obtained when the ICP power is within the range required by the present invention (i.e., 400-1000W). And when the etching ICP power is too high, such as 1200W, the etching selectivity becomes poor, and it is difficult to perform deep etching.
Example 5
Exploring the influence of etching RF power on lithium niobate nanostructure
The procedure of this example was the same as in example 1, except that the pattern structure formed by exposing, developing and fixing the photoresist layer was different from example 1, and this example explored three kinds of RF power (40W, 60W and 120W, respectively). Specifically, the pattern structure formed on the photoresist layer in this embodiment is rectangular, where the length of the pattern structure is 800nm, the width is 400nm, and the period is 1000nm.
Fig. 6C shows SEM images of the lithium niobate nanostructures prepared at 40W, 60W, and 120W, respectively. Specifically, fig. 6C shows: at an RF power of 40W, the aspect ratio of the lithium niobate nanostructure is 1:1, the inclination angle theta of the lithium niobate nano structure is 82 degrees; at an RF power of 60W, the aspect ratio of the lithium niobate nanostructure is 1:1, the inclination angle theta of the lithium niobate nano structure is 84 degrees; at an RF power of 120W, the aspect ratio of the lithium niobate nanostructure is 1:1, the tilt angle θ of the lithium niobate nanostructure is 76 °. It can be seen that lithium niobate nanostructures of high aspect ratio and high sharpness can be obtained when RF power is within the range required by the present invention (i.e., 40-80W). And when the etching RF is too high, such as 120W, the etching selectivity becomes poor, and it is difficult to perform deep etching.
Example 6
Exploring the influence of etching pressure on lithium niobate nano structure
The procedure of this example was the same as in example 1, except that the pattern structure formed by exposing, developing and fixing the photoresist layer was different from example 1, and four etching pressures (5 mtorr, 10 mtorr, 15 mtorr and 30 mtorr, respectively) were investigated. Specifically, the pattern structure formed on the photoresist layer in this embodiment is petal-shaped. Wherein, the long half shaft of the petal ellipse is 400nm, the short half shaft is 200nm, and the period is 1500nm.
Fig. 6D shows SEM images of the prepared lithium niobate nanostructures at 5 mtorr, 10 mtorr, 15 mtorr, and 30 mtorr, respectively. Specifically, fig. 6D shows: the aspect ratio of the lithium niobate nanostructure is 1 when the etching pressure is 5 millitorr: 1, the tilt angle θ of the lithium niobate nanostructure is only 85 °; the aspect ratio of the lithium niobate nanostructure is 1 when the etching pressure is 10 millitorr: 1, the tilt angle θ of the lithium niobate nanostructure is only 83 °; the aspect ratio of the lithium niobate nanostructure was 1 at an etching pressure of 15 mtorr: the tilt angle θ of the lithium niobate nanostructure is only 82 °. It can be seen that lithium niobate nanostructures of high aspect ratio and high sharpness can be obtained when the etching pressure is within the range required by the present invention (i.e., 5-20 millitorr). When the etching pressure is too high, such as 30 millitorr, the directionality of the etching may be deteriorated due to the increase of the chamber pressure, and the final effect may be deteriorated.
Comparative example 1
The procedure of this comparative example was the same as in example 1, except that the patterning structure formed by etching lithium niobate and exposing, developing and fixing the photoresist layer using Ar and SF 6 as a multicomponent mixed atmosphere was also different from example 1. Specifically, the pattern structure formed on the photoresist layer in this comparative example was an equilateral triangle with a side length of 300nm and a period of 600nm.
Fig. 3A shows an SEM image of the lithium niobate nanostructure prepared in comparative example 1. Fig. 3A shows that the aspect ratio of the lithium niobate nanostructure is only 1:2, and the tilt angle θ of the lithium niobate nanostructure is only 60 °.
Comparative example 2
The procedure of this comparative example was the same as in example 1 except that methane was reduced in the etching atmosphere, i.e., lithium niobate was etched in a multi-component mixed atmosphere of chlorine gas, boron trichloride and hydrogen gas, and the photoresist layer was exposed, developed and fixed to form a pattern structure, which was also different from example 1. Specifically, the pattern structure formed on the photoresist layer in this comparative example was rectangular, wherein the rectangle was 600nm long, 300nm wide, 500nm short side period, and 900nm long side period.
Fig. 4A shows an SEM image of the lithium niobate nanostructure prepared in comparative example 2. Fig. 4A shows that the aspect ratio of the lithium niobate nanostructure is 1:2, and the tilt angle θ of the lithium niobate nanostructure is only 45 °.
Comparative example 3
The procedure of this comparative example was the same as in example 1 except that hydrogen gas was reduced in the etching atmosphere, i.e., lithium niobate was etched in a multi-component mixed atmosphere of chlorine gas, boron trichloride and methane, and the photoresist layer was exposed, developed and fixed to form a pattern structure, which was also different from example 1. Specifically, the pattern structure formed on the photoresist layer in this comparative example is an equilateral triangle, wherein the triangle has a side length of 500nm and a period of 700nm.
Fig. 4B shows an SEM image of the lithium niobate nanostructure prepared in comparative example 3. Fig. 4B shows that the aspect ratio of the lithium niobate nanostructure is 1:2, and the tilt angle θ of the lithium niobate nanostructure is only 60 °.
Comparative example 4
The procedure of this comparative example was the same as in example 1 except that boron trichloride was reduced in the etching atmosphere, i.e., lithium niobate was etched with chlorine gas, methane gas and hydrogen gas as a multicomponent mixed atmosphere, and the photoresist layer was exposed, developed and fixed to form a pattern structure, which was also different from example 1. Specifically, the pattern structure formed on the photoresist layer in this comparative example is a diagonal rectangular structure placed in pairs, wherein the rectangle is 400nm long, 200nm wide, and the period is 800nm.
Fig. 4C shows an SEM image of the lithium niobate nanostructure prepared in comparative example 4. Fig. 4C shows that the aspect ratio of the lithium niobate nanostructure is 1:1, and the tilt angle θ of the lithium niobate nanostructure is only 45 °.
Comparative example 5
The procedure of this comparative example was the same as in example 1, except that the gas ratio in the multicomponent mixed atmosphere was selected as chlorine: boron trichloride: hydrogen gas: methane=5: 10:4:10 and the pattern structure formed by exposing, developing and fixing the photoresist layer are also different from embodiment 1. Specifically, the pattern structure formed on the photoresist layer in this comparative example is a hollow hexagon, wherein the circle diameter of the center is 200nm, the side length of the hexagon is 200nm, the width is 100nm, and the period is 600nm.
Fig. 5 shows an SEM image of the lithium niobate nanostructure prepared in comparative example 5. Fig. 5 shows that the aspect ratio of the lithium niobate nanostructure is 1:1, and the tilt angle θ of the lithium niobate nanostructure is only 50 °.
Claims (10)
1. A method for preparing lithium niobate nanostructures, comprising the steps of:
(1) Forming a photoresist layer on the lithium niobate layer with the substrate, and then exposing, developing and fixing the photoresist layer to form a photoresist layer with a desired pattern structure;
(2) Forming a mask layer on the structure obtained in the step (1);
(3) Photoresist stripping is carried out on the structure obtained in the step (2) to obtain a mask layer with a desired pattern structure;
(4) Placing the structure obtained in the step (3) in etching equipment, and etching lithium niobate by using mixed atmosphere to prepare a lithium niobate nano structure;
Wherein the mixed atmosphere comprises chlorine, boron trichloride, hydrogen and an auxiliary gas; the auxiliary gas is methane and/or nitrogen.
2. The method of claim 1, wherein the ratio of the volumetric flows of chlorine, boron trichloride, hydrogen and auxiliary gases is chlorine: boron trichloride: hydrogen gas: assist gas= (4-6): (12-20): (6-11): (2-8).
3. The method of claim 1, wherein etching lithium niobate in step (4) using a mixed atmosphere is performed under the following conditions:
The etching temperature is-20-40 ℃, the etching pressure is 5-20 millitorr, the radio frequency power is 40-80W and the ICP power is 400-1000W.
4. The method of claim 1, wherein the etching of lithium niobate in step (4) using a mixed atmosphere is performed by a method comprising the steps of:
(4-1) coating a pumping oil layer on the bottom of the substrate of the structure obtained in the step (3), then placing the substrate in etching equipment, and introducing mixed atmosphere into the etching equipment for etching, wherein the etching is performed intermittently;
(4-2) after the etching is completed, removing the residual mask layer.
5. The method of claim 1, wherein the lithium niobate is selected from a lithium niobate single crystal, a lithium niobate thin film, a MgO-, mn 2O5 -, or Fe 2O3 -doped lithium niobate single crystal, or a MgO-, mn 2O5 -, or Fe 2O3 -doped lithium niobate thin film.
6. The method of claim 1, wherein the photoresist is an electron beam photoresist or an ultraviolet photoresist;
preferably, the electron beam photoresist is PMMA (polymethyl methacrylate) or Zep photoresist;
preferably, the ultraviolet photoresist is AZ photoresist or SU8 photoresist.
7. The method of claim 1, wherein the mask layer is composed of one or more materials selected from Al, cr, siO 2 or Mo;
preferably, the thickness of the mask layer is 10nm-600nm.
8. The method of claim 1, wherein the ratio of the thickness of the lithium niobate layer to the mask layer is a lithium niobate layer: mask layer= (1-8): 1, a step of;
preferably, the forming of the mask layer in the step (2) is performed by an electron beam evaporation method, a magnetron sputtering method or a thermal evaporation method;
Preferably, the etching device is an inductively coupled plasma etching device;
preferably, the aspect ratio of the lithium niobate nanostructure is (1-5): 1, a step of;
Preferably, the tilt angle of the lithium niobate nanostructure is 80 to 90 °.
9. A lithium niobate nanostructure prepared by the method of any one of claims 1-8.
10. Use of the lithium niobate nanostructure prepared by the method of any one of claims 1 to 8 in a nonlinear frequency conversion device, an optoelectronic device or a lens of lithium niobate.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202410024781.1A CN117950265A (en) | 2024-01-08 | 2024-01-08 | Lithium niobate nano structure and preparation method and application thereof |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202410024781.1A CN117950265A (en) | 2024-01-08 | 2024-01-08 | Lithium niobate nano structure and preparation method and application thereof |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN117950265A true CN117950265A (en) | 2024-04-30 |
Family
ID=90793660
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202410024781.1A Pending CN117950265A (en) | 2024-01-08 | 2024-01-08 | Lithium niobate nano structure and preparation method and application thereof |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN117950265A (en) |
-
2024
- 2024-01-08 CN CN202410024781.1A patent/CN117950265A/en active Pending
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| US8734659B2 (en) | Process for structuring silicon | |
| CN111505767B (en) | Preparation method of lithium niobate photonic chip based on silicon oxide mask | |
| CN113687466B (en) | Lithium niobate thin film photon chip based on metal hard mask and processing method thereof | |
| CN112596160B (en) | Preparation method of high-quality thin-film lithium niobate micro-nano grating | |
| Benchabane et al. | Highly selective electroplated nickel mask for lithium niobate dry etching | |
| CN117950265A (en) | Lithium niobate nano structure and preparation method and application thereof | |
| CN111916330A (en) | Method for deep etching of grating | |
| Chang et al. | A parametric study of ICP-RIE etching on a lithium niobate substrate | |
| CN115356806A (en) | Etching method capable of controlling inclination angle of side wall of lithium niobate waveguide | |
| CN112071740B (en) | Method for preparing silicon carbide structure by picosecond laser irradiation | |
| EP1845562B1 (en) | Manufacturing method for an anti-reflective substrate | |
| CN104991356B (en) | A kind of MZ type acousto-optic modulators based on SOI | |
| CN110211922A (en) | The etching method for forming through hole of monocrystal thin films on a kind of substrate | |
| CN115417372A (en) | Processing method of three-dimensional quartz structure | |
| Chang et al. | Optimized DRIE etching of ultra-small quartz resonators | |
| Queste et al. | DRIE of non-conventional materials: first results | |
| CN111675191B (en) | Method for producing three-dimensional nanostructures with continuously adjustable height | |
| JP4273778B2 (en) | Processing method of high dielectric material | |
| Shifat et al. | Etching of scandium-doped aluminum nitride using inductively coupled plasma dry etch and tetramethyl ammonium hydroxide | |
| CN117865218A (en) | Dry deep etching process for thin film lithium niobate | |
| CN117446747A (en) | Lithium niobate micro-nano structure, dry etching method for forming lithium niobate micro-nano structure and application of lithium niobate micro-nano structure | |
| CN111439720B (en) | Method for preparing variable-diameter nano structure | |
| CN114815025B (en) | Preparation method of large-duty-ratio sub-wavelength period grating | |
| Chien et al. | Controlling the etch selectivity of silicon using low-RF power HBr reactive ion etching | |
| JP2014022411A (en) | Etching method using near-field light |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination |