CN111999912A - Refractive index tunable film structure and preparation method thereof - Google Patents
Refractive index tunable film structure and preparation method thereof Download PDFInfo
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- CN111999912A CN111999912A CN202010870803.8A CN202010870803A CN111999912A CN 111999912 A CN111999912 A CN 111999912A CN 202010870803 A CN202010870803 A CN 202010870803A CN 111999912 A CN111999912 A CN 111999912A
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- 238000002360 preparation method Methods 0.000 title abstract description 7
- 239000010408 film Substances 0.000 claims abstract description 74
- 230000000737 periodic effect Effects 0.000 claims abstract description 26
- 239000010410 layer Substances 0.000 claims abstract description 21
- 239000010409 thin film Substances 0.000 claims abstract description 20
- 239000000463 material Substances 0.000 claims abstract description 19
- 239000002356 single layer Substances 0.000 claims abstract description 15
- 238000005530 etching Methods 0.000 claims abstract description 13
- 229920002120 photoresistant polymer Polymers 0.000 claims abstract description 8
- 239000000758 substrate Substances 0.000 claims abstract description 6
- 238000004140 cleaning Methods 0.000 claims abstract description 4
- 238000005516 engineering process Methods 0.000 claims abstract description 4
- 238000010884 ion-beam technique Methods 0.000 claims abstract description 4
- 238000004528 spin coating Methods 0.000 claims abstract description 4
- 238000007747 plating Methods 0.000 claims abstract description 3
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 claims description 9
- 238000004364 calculation method Methods 0.000 claims description 4
- 239000012528 membrane Substances 0.000 claims description 4
- 238000004519 manufacturing process Methods 0.000 claims description 2
- 230000001276 controlling effect Effects 0.000 abstract description 4
- 238000000034 method Methods 0.000 abstract description 4
- 230000001105 regulatory effect Effects 0.000 abstract description 4
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N silicon dioxide Inorganic materials O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 7
- 229910052681 coesite Inorganic materials 0.000 description 4
- 229910052906 cristobalite Inorganic materials 0.000 description 4
- 238000013461 design Methods 0.000 description 4
- 230000003287 optical effect Effects 0.000 description 4
- 239000000377 silicon dioxide Substances 0.000 description 4
- 229910052682 stishovite Inorganic materials 0.000 description 4
- 229910052905 tridymite Inorganic materials 0.000 description 4
- 238000000151 deposition Methods 0.000 description 3
- CSCPPACGZOOCGX-UHFFFAOYSA-N Acetone Chemical compound CC(C)=O CSCPPACGZOOCGX-UHFFFAOYSA-N 0.000 description 2
- 238000011161 development Methods 0.000 description 2
- 238000010586 diagram Methods 0.000 description 2
- 239000012788 optical film Substances 0.000 description 2
- 238000007796 conventional method Methods 0.000 description 1
- 239000008367 deionised water Substances 0.000 description 1
- 229910021641 deionized water Inorganic materials 0.000 description 1
- 230000008021 deposition Effects 0.000 description 1
- 238000001035 drying Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 239000010453 quartz Substances 0.000 description 1
- 238000005201 scrubbing Methods 0.000 description 1
- 238000003980 solgel method Methods 0.000 description 1
- 238000005406 washing Methods 0.000 description 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Chemical compound O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 1
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- G—PHYSICS
- G02—OPTICS
- G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
- G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
- G02F1/0009—Materials therefor
- G02F1/0063—Optical properties, e.g. absorption, reflection or birefringence
-
- G—PHYSICS
- G02—OPTICS
- G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
- G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
- G02F1/01—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour
- G02F1/015—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour based on semiconductor elements having potential barriers, e.g. having a PN or PIN junction
-
- G—PHYSICS
- G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
- G03F—PHOTOMECHANICAL PRODUCTION OF TEXTURED OR PATTERNED SURFACES, e.g. FOR PRINTING, FOR PROCESSING OF SEMICONDUCTOR DEVICES; MATERIALS THEREFOR; ORIGINALS THEREFOR; APPARATUS SPECIALLY ADAPTED THEREFOR
- G03F7/00—Photomechanical, e.g. photolithographic, production of textured or patterned surfaces, e.g. printing surfaces; Materials therefor, e.g. comprising photoresists; Apparatus specially adapted therefor
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- Physics & Mathematics (AREA)
- Nonlinear Science (AREA)
- General Physics & Mathematics (AREA)
- Optics & Photonics (AREA)
- Micromachines (AREA)
- Surface Treatment Of Optical Elements (AREA)
- Diffracting Gratings Or Hologram Optical Elements (AREA)
Abstract
The invention discloses a refractive index tunable film structure and a preparation method thereof. The refractive index tunable film structure is formed by etching a periodic microstructure on the surface of a single-layer film, and the structure of the film structure is a compact film layer and a periodic microstructure film layer from bottom to top in sequence, wherein the refractive index of the compact film layer is equal to the refractive index of a film material, and the refractive index of the periodic microstructure film layer is related to microstructure parameters. The surface microstructure is equivalent to a medium layer with continuously changed refractive index, the equivalent refractive index of the medium layer is smaller than the refractive index of the film material, and the integral refractive index of the film can be regulated and controlled by regulating and controlling the equivalent refractive index of the medium layer. The preparation method comprises the following steps: (1) plating a film on the surface of the substrate; (2) cleaning the film surface, and spin-coating a photoresist on the film surface; (3) exposing the sample by adopting double-beam interference; (4) developing to obtain a required mask pattern; (5) transferring the mask pattern to the film by reactive ion beam etching technology; (6) the residues generated by etching are cleaned. The invention controls the proportion of air in the film by regulating the height and the duty ratio of the nano microstructure in the film, thereby realizing the regulation and control of the refractive index of the film material. The invention has extremely wide refractive index regulation range (from the refractive index of an air layer to the refractive index of the thin film material), and has simple process and strong repeatability.
Description
Technical Field
The invention belongs to the field of optical films, and particularly relates to a film structure with tunable refractive index and a preparation method thereof.
Background
Optical thin film technology has become an important ring in modern life, industrial development and advanced science through the development of more than two hundred years. The optical film can be functionally divided into an antireflection film, a high-reflection film, an optical filter, a light splitting film and the like, and structurally divided into a uniform dielectric film and a non-uniform dielectric film. However, the conventional optical thin film materials have certain refractive indexes and cannot be flexibly regulated and controlled. In the face of increasingly complex application environments, an optical thin film with a single refractive index cannot meet application requirements, for example, ideal reflection reduction of the surface of a substrate is achieved only by finding a material with a refractive index equal to the product of the refractive index of the substrate under the root and the refractive index of an incident medium, but the limited material types cannot well meet the requirements of all application scenes, and then a multilayer film structure formed by alternately depositing materials with high and low refractive indexes is required, but the multilayer film structure is complex and the design difficulty is high. The sol-gel method and the inclined deposition method are two conventional methods for preparing the refractive index tunable thin film, and the principle of the method is to reduce the refractive index of a single-layer film by preparing a loose porous film, but the two methods have a limited range for tuning the refractive index and have poor controllability of the refractive index.
Disclosure of Invention
In view of the above-mentioned shortcomings, the present invention provides a refractive index tunable thin film structure and a method for manufacturing the same, so as to solve the above-mentioned problems.
The technical scheme of the invention is as follows:
the invention provides a refractive index tunable film structure, which is formed by etching a periodic microstructure on the surface of a single-layer film, wherein the structure sequentially comprises a compact film layer and a periodic microstructure film layer from bottom to top, the refractive index of the compact film layer is equal to the refractive index of a film material, and the refractive index of the periodic microstructure film layer is related to microstructure parameters. The refractive index of the thin film structure can be adjusted from the refractive index of the air layer to the refractive index of the thin film material.
The periodic microstructure is cylindrical, conical, parabolic or pyramidal.
The microstructure height is less than or equal to the thickness of a single-layer film.
Duty cycle of the microstructure
The selection range is more than 0 and less than or equal to 1, wherein D is the side length of the periodic microstructure, and T is the period of the periodic microstructure.
The refractive index n of the film is fna+(1-f)ncWherein f is the volume ratio of air and ncAnd naRespectively representing the refractive index of the thin film material and the refractive index of the air layer.
Further, if the periodic structure is pyramidal, the refractive index of the film is expressed as
If the periodic structure is conical, the refractive index of the film is expressed as
If the periodic structure is parabolic, the refractive index of the film is expressed as
If the periodic structure is cylindrical, the refractive index of the film is expressed as
Where τ is the duty cycle of the periodic structure and ncAnd naRespectively representing the refractive index of the thin film material and the refractive index of the air layer.
A preparation method of a refractive index tunable film is characterized by comprising the following steps:
step 1): plating a single-layer film on the surface of the substrate;
step 2): and selecting a proper film material according to the required refractive index, and selecting a proper microstructure height and duty ratio according to a refractive index calculation formula.
Step 3): cleaning the membrane surface, and spin-coating a photoresist on the membrane surface, wherein the thickness of the photoresist is slightly larger than the height of the microstructure to be prepared;
step 4): exposing the sample by adopting double-beam interference;
step 5): placing the exposed single-layer film in 4 per mill NaOH solution for 10s-60s to develop to obtain a required mask pattern;
step 6): transferring the mask pattern to the single-layer film by adopting a reactive ion beam etching technology, and controlling the etching time to reach the height and the shape of the required microstructure;
step 7): the residues generated by etching are cleaned.
Compared with the prior art, the invention has the technical effects that:
the invention can regulate and control the refractive index of the film in a great range, has strong controllability of the refractive index, and can be suitable for different application environments.
Drawings
FIG. 1 is a front view of a refractive index tunable thin film structure according to the present invention.
FIG. 2 is a schematic diagram of a refractive index tunable thin film according to the present invention.
In the figure: d-side length of periodic structure, T-structure period, H-structure height and H-film thickness.
Detailed Description
The following detailed description of specific embodiments of the invention refers to the accompanying drawings.
FIG. 1 is a schematic diagram of the front side of a refractive index tunable film structure of the present invention, wherein D-periodic structure side length, T-structure period, H-structure height, and H-film thickness.
The first requirement of the embodiment is as follows: single layer SiO2The film refractive index was 1.1.
Adopting a cylindrical microstructure design scheme, and the film material is SiO2(n is 1.46), the microstructure height H is equal to the monolayer film thickness H for design convenience, and has a value of 200 nm. The diameter of the cylindrical microstructure is 200nm, the period is 400nm, so the duty ratio is 0.5, and the equivalent refractive index is about 1.1 according to a refractive index calculation formula.
Specifically, the preparation of this example includes the following steps:
(1) deposition of 200nm SiO on a Quartz substrate2Scrubbing the surface of the film system by using acetone, washing by using deionized water and drying;
(2) the positive photoresist is uniformly coated on the SiO by spin coating2The surface, photoresist thickness is 210 nm;
(3) carrying out first exposure by adopting double-beam interference exposure, then rotating the exposure surface of the film by 90 degrees, carrying out second exposure, and obtaining the period of the microstructure by adjusting the interference angle of the double beams;
(4) developing by adopting 4 per mill of NaOH solution, and controlling the developing time to obtain a mask pattern with the required duty ratio;
(5) transferring the prepared mask pattern to SiO by reactive ion beam etching2And controlling parameters such as etching time and the like to reach the required height and shape of the microstructure.
(6) And cleaning the residual photoresist on the surface to obtain the final structure.
The second embodiment requires: single layer SiO2The film refractive index was 1.30.
Adopts a pyramid-shaped microstructure design scheme, and the thin film material is SiO2(n-1.46), H-100 nm, and H-200 nm. The diameter of the pyramid-shaped microstructure is 200nm, the period is 200nm, so the duty ratio is 1, and the equivalent refractive index is about 1.30 according to a refractive index calculation formula.
The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents, improvements and the like that fall within the spirit and principle of the present invention are intended to be included therein.
Claims (6)
1. A refractive index tunable thin film structure is characterized in that a refractive index tunable thin film structure is formed by etching a periodic microstructure on the surface of a single-layer film, the structure sequentially comprises a compact film layer and a periodic microstructure film layer from bottom to top, the refractive index of the compact film layer is equal to the refractive index of a thin film material, and the refractive index of the periodic microstructure film layer is related to microstructure parameters.
2. The index tunable thin film structure of claim 1, wherein the thin film structure index of refraction n-fna+(1-f)ncWhere f is the volume ratio of air in the entire film structure, and ncAnd naRespectively representing the refractive index of the dense film material and the refractive index of the air layer.
3. The index tunable film structure of claim 1, wherein the periodic microstructure is cylindrical, conical, parabolic, or pyramidal;
if the periodic microstructure is pyramid-shaped, the refractive index of the film
If the periodic microstructure is conical, the refractive index of the film
If the periodic microstructure is parabolic, the refractive index of the film
If the periodic microstructure is cylindrical, the refractive index of the film
Where τ is the duty cycle of the periodic structure and ncAnd naRespectively representing the refractive index of the thin film material and the refractive index of the air layer.
4. The periodic microstructure of claim 1, wherein the microstructure height H is less than or equal to a monolayer film thickness H.
5. The periodic microstructure of claim 1, wherein the microstructure duty cycle (defined as the ratio of microstructure side length D to period T) is selected to be in a range of greater than 0 and equal to or less than 1.
6. The method of fabricating a refractive index tunable thin film structure of claim 1, comprising the steps of:
step 1): plating a single-layer film on the surface of the substrate;
step 2): selecting a suitable film material according to the required refractive index, and selecting a suitable microstructure height and duty ratio according to the refractive index calculation formula in claim 3.
Step 3): cleaning the membrane surface, and spin-coating a photoresist on the membrane surface, wherein the thickness of the photoresist is slightly larger than the height of the microstructure to be prepared;
step 4): exposing the sample by adopting double-beam interference;
step 5): placing the exposed single-layer film in 4 per mill NaOH solution for 10s-60s to develop to obtain a required mask pattern;
step 6): transferring the mask pattern to the single-layer film by adopting a reactive ion beam etching technology, and controlling the etching time to reach the height and the shape of the required microstructure;
step 7): the residues generated by etching are cleaned.
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| Application Number | Priority Date | Filing Date | Title |
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| CN202010870803.8A CN111999912A (en) | 2020-08-26 | 2020-08-26 | Refractive index tunable film structure and preparation method thereof |
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| Application Number | Priority Date | Filing Date | Title |
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| CN202010870803.8A CN111999912A (en) | 2020-08-26 | 2020-08-26 | Refractive index tunable film structure and preparation method thereof |
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Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN202041668U (en) * | 2011-04-28 | 2011-11-16 | 西北工业大学 | Zinc sulfide (ZnS) infrared optical window |
| CN108710164A (en) * | 2018-05-25 | 2018-10-26 | 中国科学院上海光学精密机械研究所 | Ultra-wideband anti-reflection micro-structure and preparation method thereof |
| CN110230096A (en) * | 2019-06-26 | 2019-09-13 | 中国科学院上海光学精密机械研究所 | Micro-structure and preparation method thereof that lithium triborate crystal surface is anti-reflection |
| CN111142178A (en) * | 2020-01-20 | 2020-05-12 | 中国科学院上海光学精密机械研究所 | Microstructure low-oscillation back coated chirped mirror and preparation method thereof |
-
2020
- 2020-08-26 CN CN202010870803.8A patent/CN111999912A/en active Pending
Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN202041668U (en) * | 2011-04-28 | 2011-11-16 | 西北工业大学 | Zinc sulfide (ZnS) infrared optical window |
| CN108710164A (en) * | 2018-05-25 | 2018-10-26 | 中国科学院上海光学精密机械研究所 | Ultra-wideband anti-reflection micro-structure and preparation method thereof |
| CN110230096A (en) * | 2019-06-26 | 2019-09-13 | 中国科学院上海光学精密机械研究所 | Micro-structure and preparation method thereof that lithium triborate crystal surface is anti-reflection |
| CN111142178A (en) * | 2020-01-20 | 2020-05-12 | 中国科学院上海光学精密机械研究所 | Microstructure low-oscillation back coated chirped mirror and preparation method thereof |
Non-Patent Citations (1)
| Title |
|---|
| 沈自才 等: "斜角入射沉积法制备渐变折射率薄膜的折射率分析", 《物理学报》 * |
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