CN101221358A - Fabrication method of multi-phase micro-optical elements on curved substrate based on flexible ultraviolet stamper - Google Patents

Abstract

The method of processing multi-phase micro-optical elements on a curved surface substrate based on a flexible ultraviolet stamper involves the production technology of micro-optical elements; this method adds a step of using a polymer structure as a mask and applying dry etching technology to obtain a relief structure on the substrate to complete the micro-optical element. The structure is transmitted to the surface of the hard substrate, and in the imprinting step, the soft imprinting mold is elastically deformed under the pre-pressure applied in the imprinting process and bent into a shape similar to the processed surface, and the amount of deformation is The size can be calculated by the method of finite element simulation. The shape and size of the microstructure on the surface of the stamper in the mother board production step need to be designed for the size of the deformation. The application of this method can realize the single material curved surface substrate Fabrication of micro-optical components of non-polymer hard optical materials.

Description

Fabrication method of multi-phase micro-optical elements on curved substrate based on flexible ultraviolet stamper

technical field

The invention belongs to a manufacturing method of a micro-optical element, and relates to a method for processing a multi-phase micro-optical element of a curved surface base based on a flexible ultraviolet pressure mold.

Background technique

Microstructured optical elements based on curved substrates have better optical imaging characteristics than diffractive optical elements based on planar substrates. The application of microstructured optics on curved substrates in optical systems can greatly improve the integration of optical systems and increase optical The design freedom of the system, the reduction of volume, the compression of cost, and the reduction of the difficulty of optical system design maximize the performance of the optical system.

The traditional optical lithography method is difficult to apply to the microstructure processing of curved substrates. At present, the processing of microstructured optical elements on curved substrates mainly adopts the method of laser direct writing, such as ① Daniela Radtke, Uwe D.Zeitner.Laser- lithography on non-planar surfaces. Optics Express. Vol.15: 1167～1174 (2007); ②Yoniun Xie, Zhenwu Lu, Fengyou Li, Jingli Zhao, ZhichengWeng. Vol.10: 1043~1047 (2002), etc., mainly through the high-precision control of the three-dimensional motion displacement of the workpiece, adjust the writing spot, and realize the processing and manufacturing of curved surface base diffractive optical elements by point-by-point exposure . This type of method relies on an extremely complex multi-degree-of-freedom high-precision motion control system, which is expensive, complex in mechanism, and has disadvantages such as low processing efficiency, slow speed, and not suitable for batch processing.

Ultraviolet imprinting technology based on flexible stamper is developed on the basis of soft lithography. In the process of nanoimprinting, flexible materials are used to make stampers, which can realize the processing of microstructures smaller than 30nm. The flexible stamper is an elastic gel-like substance that can be bent into any shape as required, such as a cylinder, a sphere or even an aspheric surface, making it possible to process the microstructure of non-planar substrates. Compared with the UV imprinting technology based on the rigid stamper, the flexible UV stamper has the advantages of low cost, easy production, long life, and fast speed. It can realize the processing and fabrication of microstructures on a substrate with a diameter of 150mm at one time without multiple times. Repeat imprint.

Currently, there are published methods for fabricating microstructured optical elements on curved substrates based on flexible stamper UV imprinting technology, such as ①Younan Xia, George M.Whitesides.Soft Lithography.Angew.Chem.Int.Ed.Vol 37:550～575( 1998) ②Xia YN, Kim E, Zhao XM, Rogers JA, Prentiss M, Whitesides GM. Complex optical surfaces formed by replica molding against elastomeric masters. SCIENCE 273(5273): 347～349(1996), etc., by using flexible stamping mold PDMS realizes microstructure processing such as blazed gratings on the photoresist polymer of the cylindrical substrate. This method cannot realize the processing of hard optical materials such as silicon and glass, and has great limitations in material selection. , the application is very limited.

At present, there is no research report on the application of flexible stamper UV imprinting technology to fabricate curved substrate micro-optical elements whose structural materials are silicon, quartz and other hard optical materials in visible light or infrared bands.

Contents of the invention

The purpose of the present invention is to design a method for processing multi-phase micro-optical elements on curved substrates based on a flexible ultraviolet stamper, using flexible ultraviolet stamper embossing technology, by bending the flexible stamper to the required shape, such as cylindrical surface, spherical surface As well as aspheric surface, it can realize the processing and production of curved surface substrate micro-optical elements.

The technical solution of the present invention is: a method for processing curved surface substrate multi-phase micro-optical elements based on flexible ultraviolet mode, which specifically includes the following steps: ① Applying micro-fabrication technology to prepare multi-phase or continuous relief structure micro-optics for processing curved surface substrates The microstructure stamper motherboard required by the component; ②Using injection molding replication technology to copy the relief structure on the surface of the motherboard to the surface of the soft embossing mold; ③Using ultraviolet imprinting technology to emboss the relief structure on the soft stamper to the curved substrate on the surface of the polymer; it is characterized in that the method also includes the following steps, ④using the polymer structure as a mask, applying dry etching technology to obtain a relief structure on the substrate, and completing the graphic transfer of the microstructure to the surface of the hard substrate , and in step ③, the soft embossing mold is elastically deformed under the pre-pressure applied during the imprinting process and bent into a shape similar to the processed surface, and the amount of deformation can be calculated by finite element simulation method , the shape and size of the microstructure on the surface of the stamper mother plate in step ① need to be designed according to the size of the deformation. The application of this method can realize the processing of micro-optical elements of non-polymer hard optical materials with a single material curved surface substrate make.

The method for processing multi-phase micro-optical elements on a curved substrate based on a flexible ultraviolet stamper is characterized in that the surface of the substrate to be processed is a curved structure such as a spherical surface, an aspheric surface, or a cylindrical surface.

The method for processing multi-phase micro-optical elements on a curved surface based on a flexible ultraviolet stamper is characterized in that the stamper material is a flexible stamper material that can transmit ultraviolet light, such as polydimethylsiloxane (PDMS).

The method for processing multi-phase micro-optical elements on a curved surface substrate based on a flexible ultraviolet stamper is characterized in that the micro-processing technology includes overlay technology, laser direct writing technology, and electron beam direct writing technology.

The method for processing the multi-phase micro-optical element of the curved surface base based on the flexible ultraviolet stamper is characterized in that the material of the micro-optic element includes glass, quartz (SiO ₂ ), silicon (Si), germanium (Ge), sapphire (Al ₂ O ₃ ), gallium arsenide (GaAs), magnesium fluoride (MgF ₂ ), lithium fluoride (LiF), barium fluoride (BaF ₂ ), calcite (CaCO ₃ ), zinc sulfide (ZnS).

The innovation of the present invention is:

The invention proposes a method for processing a multi-phase micro-optical element on a curved surface substrate based on a flexible ultraviolet pressure mold. The basic idea of this method is to use the elastic deformation of the flexible die to realize the imprint replication of the microstructure from the flat substrate to the curved substrate. The elastic deformation can be calculated and simulated by the Young's modulus of the die material. Compensation design about elastic deformation is carried out on the rigid die plate of plane base. Applying this method can avoid the dependence of traditional processing methods on multi-degree-of-freedom, high-precision and fast motion control systems. By making stamper master, generating flexible stamper, flexible stamper embossing, and combining dry etching, this method realizes the processing and fabrication of microstructured optical elements of hard optical materials on curved surface substrates. Compared with other methods, The process steps are simpler, the production is easier, the processing cost is lower, and it is easier to realize rapid batch processing and production.

The advantage of the present invention is:

1. The present invention can process microstructures with a characteristic size below 10nm, can meet the processing requirements of multi-scale and different resolution relief structures, and can realize the processing and production of surface relief structures on various curved substrates.

2. Compared with the traditional laser direct writing processing technology, the present invention has the advantages of simple processing technology, fast processing speed, good realizability, high precision, and low processing cost.

3. The present invention is not limited by the replication material, and the surface profile can be replicated into materials such as quartz, single crystal silicon and sapphire. Compared with polymers, such materials have the advantages of high strength, high hardness, high resistance to radiation damage threshold, high chemical stability, and wide transmission spectrum range.

4. The present invention has the advantages of simple process, fast speed, good repeatability, low cost, long life, high yield, etc., and can realize mass production.

Description of drawings

Figure 1 is a schematic diagram of the process flow for making a stamper master and a soft stamping mold.

(a) Electron beam direct write exposure;

(b) developing;

(c) dry etching;

(d) Injection molding replication.

Fig. 2 is a schematic diagram of a process flow for manufacturing a multi-step binary optical lens with a spherical substrate.

(a) Injection molding replication;

(b) Spherical surface coating;

(c) Spherical UV imprinting;

(d) demoulding;

(e) Dry etching.

FIG. 3 is a schematic diagram of the process flow for manufacturing a multi-step binary optical element with a cylindrical substrate.

(a) Injection molding replication;

(b) Cylinder surface gluing;

(c) Cylindrical UV imprinting;

(d) demoulding;

(e) Dry etching.

Fig. 4 is a schematic diagram of the process flow for making a continuously embossed Fresnel lens on an aspheric substrate.

(a) Injection molding replication;

(b) Aspheric coating;

(c) Aspheric UV imprinting;

(d) demoulding;

(e) Dry etching.

Detailed ways

Example 1:

As shown in Figure 2, the diffractive optical lens with spherical base multi-step micro-relief structure is made, the element material is glass, the stamper material is PDMS, and the polymer required for UV imprinting is UV-curable glue OG154. The specific process is as follows:

1. As shown in Figure 1, laser direct writing technology is used to produce a surface relief quartz master with the same structure as the target.

2. As shown in Figure 2(a), the microstructure injection molding replication technology is used to replicate the microstructure of the master plate to the surface of the PDMS material.

3. As shown in Figures 2(b) and 2(c), the PDMS stamper is used to perform UV imprinting on the spherical substrate, and the PDMS stamper is bent into a curved surface similar to the processed spherical surface under the action of external force.

4. As shown in Fig. 2(d), it is the spherical polymer micro-relief structure after demoulding.

5. As shown in FIG. 2(e), a multi-step micro-relief structure is obtained on the glass substrate by using reactive ion etching technology.

Example 2:

As shown in Figure 3, a binary optical element with a multi-step structure on a cylindrical base is fabricated. The material of the element is monocrystalline silicon, the material of the mold is PDMS, and the polymer is an ultraviolet organic photosensitive solvent PAK01. The specific process is as follows:

1. As shown in Figure 1, apply electron beam direct writing technology to make a quartz mother board with the same structure as the target.

2. As shown in Figure 3(a), the microstructure of the master plate is copied to the surface of the PDMS material by using the microstructure injection molding replication technology.

3. As shown in Figure 3(b) and 3(c), apply the PDMS stamper to implement UV imprinting on the cylindrical substrate, and the PDMS stamper is bent into a curved surface similar to the processed cylindrical surface under the action of external force shape.

4. As shown in Fig. 3(d), it is the columnar-based polymer micro-relief structure after demoulding.

5. As shown in FIG. 3(e), a multi-step micro-relief structure is obtained on the quartz substrate by applying dry etching technology.

Example 3:

As shown in Figure 4, the Fresnel lens with a continuous relief structure is produced, the element material is sapphire, the molding material is PDMS, and the polymer is selected from the ultraviolet organic photosensitive solvent PAK01. The specific process is as follows:

1. As shown in Figure 1, apply the electron beam direct writing technology to make a continuous relief structure quartz mother board with the same structure as the target.

2. As shown in Figure 4(a), the microstructure injection molding replication technology is used to replicate the microstructure of the master plate to the surface of the PDMS material.

3. As shown in Figure 4(b) and 4(c), UV imprinting is carried out on the aspheric substrate using the PDMS stamper, and the PDMS stamper is bent into a curved shape similar to the processed aspheric surface under the action of external force appearance.

4. As shown in Figure 4(d), it is the aspherical polymer micro-relief structure after demoulding.

5. As shown in FIG. 4(e), a multi-step micro-relief structure is obtained on the sapphire substrate by applying dry etching technology.

Claims (5)

1. the curved substrate multi-phase micro-optical element method for processing based on flexible ultraviolet mould specifically may further comprise the steps: 1. use the Micrometer-Nanometer Processing Technology preparation and be used for processing curve substrate multi-phase or the required microtexture pressing mold motherboard of continuous relief structure micro-optical element; 2. using the injection moulding reproduction technology copies to the motherboard surface relief structure on the soft making ide surface; 3. using the ultraviolet stamping technology is impressed into the embossment structure on the soft pressing mold on the polymkeric substance on curved substrate surface; It is characterized in that, this method is further comprising the steps of, 4. with the polymer architecture mask, use dry etching technology and on substrate, obtain embossment structure, finish the figure transmission of microtexture to the hard substrate surface, and step 3. in, elastic deformation takes place and bends to the shape close with surface to be machined in soft making ide under the precompression effect that moulding process added, and the big I of deflection calculates by the method for finite element simulation, the pattern of the pressing mold motherboard surface fine structure of step in 1. and size need be used the processing and fabricating that this method realizes homogenous material curved surface substrate non-polymer hard optical material micro optical element at the size of this deformation quantity to compensating design.

2. the curved substrate multi-phase micro-optical element method for processing based on flexible ultraviolet die mold according to claim 1 is characterized in that processed substrate surface is the curved-surface structure such as sphere, aspheric surface, cylinder.

3. the curved substrate multi-phase micro-optical element method for processing based on flexible ultraviolet die mold according to claim 1 is characterized in that the ultraviolet stamping die material is flexible die material, as dimethyl silicone polymer (PDMS).

4. the curved substrate multi-phase micro-optical element method for processing based on flexible ultraviolet die mold according to claim 1 is characterized in that Micrometer-Nanometer Processing Technology comprises cover lithography, laser direct-writing technology, direct electronic beam writing technology.

5. the curved substrate multi-phase micro-optical element method for processing based on flexible ultraviolet die mold according to claim 1 is characterized in that the micro optical element material comprises glass, quartz (SiO ₂), silicon (Si), germanium (Ge), sapphire (Al ₂O ₃), gallium arsenide (GaAs), magnesium fluoride (MgF ₂), lithium fluoride (LiF), barium fluoride (BaF ₂), kalzit (CaCO ₃), zinc sulphide (ZnS).

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