阅读说明：本技术 一种双面微结构聚酰亚胺薄膜光学器件的制备方法 (Preparation method of polyimide film optical device with double-sided microstructure ) 是由 杨正 吴鹏 靳志伟 饶先花 尹韶云 于 2019-09-19 设计创作，主要内容包括：本发明公开一种双面微结构聚酰亚胺薄膜光学器件的制备方法,解决现有聚酰亚胺加工方法制作成本较高、工作环境难以实现等问题。本发明的制备方法具体包括以下步骤：(1)在衬底模具表面涂覆聚酰亚胺前驱液,并低温烘烤至凝胶状态；(2)在聚酰亚胺凝胶体表面叠印压印模具,并压印升温使所述聚酰亚胺凝胶体半固化；(3)剥离压印模具,得到半固态的聚酰亚胺结构,并烘烤至完全亚胺化；(4)剥离衬底模具,得到双面微结构聚酰亚胺薄膜光学器件。本发明利用涂胶、压印和梯度升温方法即可在聚酰亚胺薄膜两面同时获得微纳结构,方法简单快捷、普适性强,制备过程效率高、成本低,可用于制备复合功能薄膜光学器件。(The invention discloses a preparation method of a double-sided microstructure polyimide film optical device, which solves the problems that the existing polyimide processing method is high in manufacturing cost, difficult to realize working environment and the like. The preparation method specifically comprises the following steps: (1) coating a polyimide precursor solution on the surface of a substrate mould, and baking at a low temperature to a gel state; (2) overprinting an imprinting mould on the surface of the polyimide gel, and carrying out imprinting and heating to semi-solidify the polyimide gel; (3) stripping the imprinting mold to obtain a semi-solid polyimide structure, and baking to complete imidization; (4) and stripping the substrate die to obtain the double-sided microstructure polyimide film optical device. The method can simultaneously obtain the micro-nano structures on two sides of the polyimide film by using the gluing, stamping and gradient heating methods, has the advantages of simplicity, rapidness, strong universality, high efficiency of the preparation process and low cost, and can be used for preparing composite functional film optical devices.)

1. A mold for manufacturing a double-sided microstructure polyimide film optical device is characterized by comprising a substrate mold and an imprinting mold.

2. The mold of claim 1, wherein the substrate surface of the substrate mold comprises a complementary structure of a substrate micro-nano structure.

3. The mold of claim 1, wherein the surface of the imprinting mold comprises complementary structures of the imprinted micro-nano structure.

4. The preparation method of the double-sided microstructure polyimide film optical device by using the mold as claimed in claim 1, 2 or 3 is characterized by comprising the following steps:

(1) coating a polyimide precursor solution on the surface of a substrate mould, and baking at a low temperature to a gel state;

(2) overprinting an imprinting mould on the surface of the polyimide gel, and carrying out imprinting and heating to semi-solidify the polyimide gel;

(3) stripping the imprinting mold to obtain a semi-solid polyimide structure, and baking to complete imidization;

(4) and stripping the substrate die to obtain the double-sided microstructure polyimide film optical device.

5. The preparation method according to claim 4, wherein in the step (1), the polyimide precursor solution with viscosity is coated on the surface of the substrate mold, the polyimide precursor solution is coated on the surface of the substrate mold by adopting a spin coating and blade coating method according to the size of the substrate mold, and the coating thickness is adjusted and controlled by controlling the spin coating speed and the blade coating distance.

6. The production method according to claim 4, wherein in the step (2), the substrate of the imprint mold is a silicon or silicon dioxide sheet.

7. The preparation method according to claim 4, wherein in the step (3), the baking is performed by a gradient heating method, and the gradient heating sequence is as follows:

in the first stage, the temperature is 150-180 ℃/0.5-1 h; the second stage is 200-250 ℃/1-2 h; the third stage is 300-350 deg.c/0.5-1 hr.

8. The double-sided microstructured polyimide film optical device obtained by the method of any one of claims 4 to 7.

9. An optical system made with the double-sided microstructured polyimide film optical device of claim 8.

Technical Field

The invention belongs to the field of manufacturing of film optical devices, and particularly relates to a preparation method of a polyimide film optical device with a double-sided microstructure.

Background

Polyimide (PI) is widely used in the fields of aviation, aerospace, microelectronics, laser and the like due to its excellent physical, chemical, electrical and mechanical properties. The development of PI thin film optics has been hot since the use of polyimide thin film optics in space telescopes was proposed in the moiire project (MOIRE project) of the united states in 2010. With the different application requirements of the PI thin film optical device in different occasions, higher requirements are put forward on the device performance. For example, in the application of a thin film diffraction lens, the PI thin film needs to have not only a precise diffraction structure but also good light transmittance. By processing the sub-wavelength antireflection structure and the diffraction structure on the two surfaces of the film simultaneously, the film diffraction lens with low reflection and high hydrophobicity can be obtained. In addition, the PI film diffraction lens needs to correct chromatic aberration, and refraction and diffraction mixed chromatic aberration correction can be realized by preparing a refraction structure on the other surface of the diffraction structure. In the application of laser homogenization, the double-sided micro-lens array structure is adopted to effectively improve the laser homogenization effect. In general, the performance of the device can be effectively improved by designing the micro-optical structure with the required functions on both sides of the PI film optical device, and how to process the micro-structures on both sides of the PI film is the key to realize the improvement of the performance of the device.

The common processing methods of polyimide are three types: nano-imprinting, laser ablation and photoetching are difficult to realize because the PI has stable physical properties and the nano-imprinting needs to work at a super-vitrification temperature (300 ℃); however, the sub-wavelength structure is difficult to process by photoetching and laser ablation, and the manufacturing cost is high. In the prior art, high-precision micro-nano structures are difficult to process on two surfaces of a PI film simultaneously. In view of the problems, the invention provides a preparation method of a polyimide optical device with a double-sided microstructure, which can process high-precision micro-nano structures on two sides of a PI film simultaneously by gluing, stamping and gradient heating methods, and has the advantages of simplicity, rapidness, strong universality, high preparation process efficiency and low cost.

Disclosure of Invention

The invention aims to provide a mold for preparing a double-sided microstructure polyimide film optical device, which can be used for preparing a functional film optical device, and has the advantages of low manufacturing cost and easy realization.

In order to achieve the purpose, the technical scheme of the invention is as follows:

a mold for manufacturing a double-sided microstructure polyimide film optical device comprises a substrate mold and an imprinting mold. The substrate surface of the substrate mold comprises a complementary structure of a substrate micro-nano structure. The surface of the imprinting mold comprises a complementary structure of an imprinting micro-nano structure. The substrate micro-nano structure and the imprinting micro-nano structure can be appropriately selected according to the function of the polyimide film optical device with the double-sided microstructure as required.

The invention also aims to provide a preparation method of the double-sided microstructure Polyimide (PI) film optical device, which is simple and rapid, has strong universality, high preparation process efficiency and low cost.

In order to achieve the purpose, the technical scheme of the invention is as follows:

a preparation method of a double-sided microstructure polyimide film optical device specifically comprises the following steps:

(1) coating a polyimide precursor solution on the surface of a substrate mould, and baking at a low temperature to a gel state;

(2) overprinting an imprinting mould on the surface of the polyimide gel, and carrying out imprinting and heating to semi-solidify the polyimide gel;

(3) stripping the imprinting mold to obtain a semi-solid polyimide structure, and baking to complete imidization;

(4) and stripping the substrate die to obtain the double-sided microstructure polyimide film optical device.

Further, in the step (1), the substrate mold is made of high-temperature resistant optical base materials, such as silicon wafers, quartz, forged aluminum and the like. The surface of the substrate comprises a complementary structure of a specific functional micro-nano structure with a required optical device, wherein the micro-nano structure comprises a sub-wavelength anti-reflection structure with low reflection and high hydrophobicity, a diffraction structure and the like, and the PI precursor liquid is coated on the structural surface of the substrate mold.

Further, the specific method for coating the structural surface of the substrate mold with the PI precursor solution is as follows: according to the size of the substrate, the PI precursor solution is coated on the surface of the substrate by spin coating and blade coating, the coating thickness is regulated and controlled by controlling the spin coating speed and the blade coating distance, and meanwhile, the wettability of the substrate and the glue solution can be improved by properly reducing the viscosity of the glue solution, so that the pattern transfer precision is improved.

Further, the PI precursor liquid is baked at a low temperature of the substrate die coated with the PI precursor liquid to be in a gel state, and the volatilization speed of the solvent is regulated and controlled by controlling the baking temperature and time, so that surface defects such as bubbles and pits are prevented from being introduced into the gel state.

Further, the substrate of the stamping die in the step (2) is a silicon or silicon dioxide sheet, the surface of the substrate comprises a complementary structure of a micro-nano structure with a specific function of a required optical device, wherein the micro-nano structure comprises a sub-wavelength anti-reflection structure with low reflection and high hydrophobicity, a diffraction structure and the like, and the stamping die can be properly processed by a release agent to reduce the adhesive force between the die and the PI. The specific method comprises the following steps: and putting the substrate mould loaded with the PI gel into a stamping machine, covering the surface of the PI gel with the stamping mould, applying proper pressure, heating to 120 ℃, and baking the PI gel to be in a semi-solid state.

Further, the temperature rise in the step (3) is performed in a gradient manner, which is specifically referred to as: and (3) stripping the semi-solid PI micro-nano structure in the step (2) from the imprinting mold, then placing the stamping mold in an oven, heating to the maximum temperature of 300-350 ℃ in a gradient manner, controlling the imidization process by controlling the heating rate and the baking time, and avoiding the accumulation of internal stress in the film forming process of the PI precursor solution so as to cause structural deformation.

And (3) further, stripping the substrate in the step (4), putting the imidized PI structure obtained in the step (3) into a culture dish containing deionized water, treating for 10min by using an ultrasonic oscillator, and cleaning and drying after the film is stripped from the substrate die to obtain the double-sided microstructure polyimide film optical device.

The third purpose of the invention is to provide a double-sided microstructure polyimide film optical device obtained by the preparation method of any one of the two purposes, wherein high-precision micro-nano structures are processed on both sides of the optical device.

The fourth purpose of the invention is to provide an optical system made of the double-sided microstructure polyimide film optical device.

The invention has the beneficial effects

The invention has the following beneficial effects:

the invention provides a preparation method of a double-sided microstructure polyimide film optical device, which can simultaneously process high-precision micro-nano structures on two sides of a PI film by using common gluing and baking equipment and gradient temperature rise, so that the performance of the film optical device is improved, and the application range of the PI film optical device is greatly improved. Compared with the prior art, the method can simultaneously process the high-precision micro-nano structures on two sides of the PI film at one time, is simple and rapid, has strong universality, high efficiency of the preparation process and low cost, can be used for preparing a composite functional film device, and solves the problems that the existing polyimide processing method is difficult to realize in working environment, high in manufacturing cost and the like.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below. It is obvious that the drawings in the following description are some embodiments of the invention, and that for a person skilled in the art, other drawings can be derived from them without inventive exercise.

FIG. 1 is a flow chart of a method for manufacturing a double-sided microstructure polyimide film optical device according to the present invention;

FIG. 2 is a flow chart of a process for fabricating a double-sided microstructured polyimide film optical device in an embodiment of the present invention;

FIG. 3 is a schematic diagram of a substrate mold structure during fabrication of a low-reflectivity, highly hydrophobic polyimide film diffractive lens in an embodiment of the present invention;

FIG. 4 is a cross-sectional view of a substrate mold structure during fabrication of a low-reflective, highly hydrophobic polyimide film diffractive lens in one embodiment of the present invention;

FIG. 5 is a schematic diagram of an imprint mold structure during fabrication of a low-reflectivity, highly hydrophobic polyimide thin film diffractive lens in an embodiment of the present invention;

FIG. 6 is a partial cross-sectional view of an imprint mold structure during fabrication of a low-reflection, highly hydrophobic polyimide film diffractive lens in one embodiment of the invention.

Reference numerals:

5, polyimide, 6, a substrate mold, 7, an imprinting mold, 8, a polyimide film diffraction lens 9 and a sub-wavelength structure.

Detailed Description

In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention. It is to be understood that the embodiments described are only a few embodiments of the present invention, and not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

The examples are given for the purpose of better illustration of the invention, but the invention is not limited to the examples. Therefore, those skilled in the art should make insubstantial modifications and adaptations to the embodiments of the present invention in light of the above teachings and remain within the scope of the invention.

In the method for manufacturing a low-reflection and highly hydrophobic polyimide film diffraction lens provided in this embodiment, a sub-wavelength anti-reflection structure and a diffraction structure are simultaneously processed on two sides of a film, as shown in fig. 1, the method includes the following steps:

1. coating PI precursor liquid on the surface of a substrate mould, and baking at low temperature to a gel state:

in this embodiment, a 5-inch silicon wafer is used as a silicon wafer substrate mold 6, and a nanoporous array structure is prepared on the surface of the silicon wafer substrate mold 6 by using a PAA template method, wherein the substrate mold 6 has a subwavelength structure 9, and the schematic diagrams are shown in fig. 3 and 4; then, coating PI precursor liquid on the structural surface by adopting a spin coating method, wherein the rotating speeds are respectively as follows: the low speed is 300rpm/3S, the medium speed is 1000rpm/30S, and the high speed is 1500 rpm/5S. This step is performed in a fume hood.

And then, horizontally placing the silicon wafer substrate mold 6 coated with the PI precursor liquid on the surface of the electric heating plate, closing a glass door of a fume hood, adjusting the air speed of the fume hood to be the lowest, baking at a low temperature for 60min at the temperature of 90 ℃, and changing the PI precursor liquid into polyimide 5 in a gel state after baking.

2. Overprinting an imprinting mold on the surface of the polyimide gel, and imprinting and heating to semi-solidify the polyimide gel:

according to the method in step 2, in this embodiment, a 5-inch silicon wafer is selected as an imprinting mold 7, and a two-step negative complementary diffraction lens structure is prepared on the surface of the imprinting mold 7 by using a photolithography etching method, wherein the imprinting mold 7 has a diffraction structure, and schematic diagrams are shown in fig. 5 and 6; and then putting the substrate mold loaded with the PI5 in the gel state into a stamping machine, applying pressure of 30bar for stamping, simultaneously heating to 120 ℃ at a speed of 20 ℃/min, and continuously baking for 5min to semi-cure the polyimide 5 in the gel state in the step 1 to obtain the semi-solid polyimide 5.

3. And (3) stripping the stamping die to obtain a semi-solid polyimide structure, and baking until complete imidization:

demolding the stamping die 7 in the step 2 to obtain a semi-solid polyimide 5 diffraction lens structure, then transferring the semi-solid polyimide 5 diffraction lens structure into a baking oven, and completing imidization by using a three-step gradient heating method: in the first stage, the temperature is 150-180 ℃/0.5-1 h; the second stage is 200-250 ℃/1-2 h; the third stage is 300-350 deg.c/0.5-1 hr. The heating rate of the whole heating process is 5-10 ℃/min. After the temperature rise is finished, imidization is completed, and the polyimide 5 with structures on both sides in a film state is obtained.

4. And (3) stripping the substrate die to obtain the double-sided microstructure polyimide film optical device:

and (3) taking the polyimide 5 in the film state obtained in the step (3) out of the oven, naturally cooling to room temperature, then putting the silicon wafer loaded with the PI film 10 into a culture dish filled with deionized water, carrying out ultrasonic oscillation treatment for 10min, and cleaning and drying after the PI film 10 is separated from the substrate mould to obtain the polyimide film diffraction lens 10 with the double-sided microstructure.

The above embodiment is only a method for preparing a low-reflection and high-hydrophobicity polyimide film diffraction lens, and in other embodiments, the substrate mold 6 may be made of high-temperature resistant optical base materials such as silicon wafers, quartz, forged aluminum, and the like; the substrate of the imprinting mould 7 can be silicon or silicon dioxide slice; the surfaces of the substrate mould 6 and the impression mould 7 can be prepared into micro-nano structure complementary structures with other required functions. Thereby obtaining the double-sided microstructure polyimide film optical device with different functions.

While the present invention has been described with reference to the embodiments shown in the drawings, the present invention is not limited to the embodiments, which are illustrative and not restrictive, and it will be apparent to those skilled in the art that various changes and modifications can be made therein without departing from the spirit and scope of the invention as defined in the appended claims.