CN112558419A - Processing method of large-caliber flexible optical super-structure surface structure - Google Patents

Abstract

The invention discloses a processing method of a large-caliber flexible optical super-structure surface structure, which comprises the steps of exposing photoresist through a photoetching system and developing to prepare a designed large-caliber super-structure surface pattern; transferring the photoresist pattern onto a substrate material using the photoresist pattern as a mask and as a template; coating the ultraviolet curing adhesive mixed with the high-refractive-index nano particles on a template, covering a layer of flexible substrate, curing the ultraviolet curing adhesive by using an ultraviolet lamp exposure mode while applying mechanical pressure by using a roll shaft, and then demoulding and separating to obtain the large-caliber flexible optical super-structure surface structure. The method has the characteristics of simple process flow, high resolution, low cost, high preparation efficiency and the like, and is suitable for the field of processing of large-area flexible super-structure surface devices.

Description

Processing method of large-caliber flexible optical super-structure surface structure

Technical Field

The invention belongs to the technical field of processing of a super-structured surface device, and particularly relates to a processing method of a large-caliber flexible optical super-structured surface structure.

Background

The optical super-surface is an artificial two-dimensional structure composed of micro-nano units with the size of tens to hundreds of nanometers. Typical photolithography processes, which are commonly used for preparing a super surface, cannot provide sufficient pattern resolution due to diffraction limit, although they can rapidly reproduce a mask pattern. Electron Beam Lithography (EBL) and Focused Ion Beam (FIB) milling, while having high resolution, have low fabrication efficiency. Compared with the method, the nano-imprinting improves the preparation efficiency of the super surface, and the resolution ratio has no physical limit. The hot stamping is widely applied, but high requirements are provided for the low thermal expansion coefficient and the pressure contraction coefficient of the material, and high pressure and heating temperature are required in the stamping process, so that the pattern structures of the template and the adhesive layer are easily damaged. The ultraviolet nano-imprinting technology solves the problems existing in hot imprinting, but bubbles in ultraviolet curing glue are difficult to discharge, and defects can be caused to the micro-nano structure. According to the reel-to-reel nano-imprinting provided by the ultraviolet imprinting technology, the high-throughput preparation of the micro-nano structure is realized. However, the roll-to-roll imprinting template is fixed on the roll shaft in a bending way, so that the position accuracy of the nano structure on the template is reduced, and the optical performance of the surface of the imprinted optical super structure is affected. On the other hand, the template pattern can only be copied to the imprinting glue by the imprinting method, and the pattern structure of the imprinting glue does not generally have functions directly, so that the imprinting glue pattern needs to be transferred to other functional materials, thereby increasing the process steps and difficulty. In summary, the main difficulty of the existing super-surface preparation technology is to reduce the process complexity and improve the device preparation efficiency and the micro-nano structure pattern quality on the premise of meeting the performance requirements.

Disclosure of Invention

The technical problem to be solved by the invention is as follows: the defects of the prior art are overcome, the processing method of the large-caliber flexible optical super-structure surface structure is provided, and the high-efficiency and low-cost manufacturing of the large-area flexible optical super-structure surface is realized through a simple micro-nano structure copying technology of ultraviolet curing glue embedded with patterns through ultraviolet curing.

The technical scheme adopted by the invention for solving the technical problems is as follows: a processing method of a large-caliber optical flexible super-structure surface device comprises the following steps:

and (1) coating photoresist on the substrate template.

And (2) exposing through a photoetching system, and then developing.

And (3) transferring the pattern onto the substrate material and serving as a template.

And (4) coating the ultraviolet curing adhesive mixed with the high-refractive-index nano particles on the template, covering a layer of flexible substrate, and curing the ultraviolet curing adhesive by using an ultraviolet lamp exposure mode while applying mechanical pressure by using a roller shaft.

And (5) separating the flexible substrate from the template to prepare the large-caliber flexible optical super-structure surface structure.

Further, the photoresist in the step (1) is an electron beam photoresist and an ultraviolet photoresist.

Further, the lithography system in the step (2) is an electron beam lithography system, an ultraviolet super-resolution lithography system and an ultraviolet super-resolution direct writing system.

Further, the pattern transfer in the step (3) is stripping, metal-assisted chemical etching, gas-assisted ion beam etching and high-density plasma etching.

Further, in the step (4), the high-refractive-index nano-particles are titanium oxide, haar oxide, zirconium oxide, zinc oxide, cerium oxide and silicon, and the diameter of the high-refractive-index nano-particles is less than or equal to 50 nm.

Further, the flexible substrate material in the step (4) is optical transparent polymer and metal glass, and the thickness of the flexible substrate is less than or equal to 500 μm; the ultraviolet light source is a surface light source and a linear light source.

The principle of the invention is as follows:

the invention discloses a processing method of a large-caliber flexible optical super-structure surface structure, which comprises the steps of exposing photoresist through a photoetching system and developing to prepare a designed large-caliber super-structure surface pattern; transferring the photoresist pattern onto a substrate material using the photoresist pattern as a mask and as a template; coating the ultraviolet curing adhesive mixed with the high-refractive-index nano particles on a template, covering a layer of flexible substrate, curing the ultraviolet curing adhesive by using an ultraviolet lamp exposure mode while applying mechanical pressure by using a roll shaft, and then demoulding and separating to obtain the large-caliber flexible optical super-structure surface structure. The method has the characteristics of simple process flow, high resolution, low cost, high preparation efficiency and the like, and is suitable for the technical field of processing of large-area flexible super-structure surface devices.

Compared with the prior art, the invention has the following advantages:

(1) the defects of long preparation period and low efficiency of the traditional super-surface manufacturing method (such as electron beam lithography and focused ion beam milling) are overcome. The method adopts ultraviolet irradiation to cure the ultraviolet curing adhesive for filling the micro-nano structure to realize the preparation of the super-structure surface, and has short preparation period and high efficiency.

(2) The invention overcomes the defect that the warping of a template in a roll-to-roll nano-imprinting technology affects the position and the dimensional accuracy of a graph.

(3) The method overcomes the defect that the optical performance of the processed super-structure surface is low due to low refractive index of the ultraviolet curing adhesive, improves the equivalent refractive index of the super-structure surface structure by mixing the high-refractive-index nano particles with the ultraviolet curing adhesive, and reduces the processing difficulty of the original pattern depth of the template and the pattern damage during demoulding.

Drawings

FIG. 1 is a process diagram for preparing a flexible optical superstructure surface structure;

FIG. 2 is a schematic view of an underlying template spin-on resist;

FIG. 3 is a schematic view of a photoresist pattern after exposure by a lithography system;

FIG. 4 is a schematic view of a super-surface structure transferred to a template by etching;

FIG. 5 is a schematic view of applying a UV curable glue to a stencil and covering a layer of flexible substrate;

FIG. 6 is a schematic view of UV curing while flattening the UV curing adhesive using a roller;

FIG. 7 is a schematic view of the structure after completion of the UV cure;

FIG. 8 is a schematic diagram of the flexible substrate being separated from the template;

FIG. 9 is a schematic view of a finished flexible microstructured surface;

in the figure: 1. a flexible substrate; 2. ultraviolet curing glue; 3. high refractive index nanoparticles; 4. pressing the roll shaft; 5. photoresist; 6. and (5) template.

Detailed Description

The invention is described in detail below with reference to the figures and the detailed description. The scope of the invention is not limited to the following examples, but is intended to include the full scope of the claims.

Example 1, the invention was utilized to achieve the preparation of a flexible optical superstructure surface structure with a 200mm aperture.

(1) Spin-coating a layer of electron beam photoresist with the thickness of 200nm on a silicon substrate with the diameter of 200 mm;

(2) exposing a large-area super-structure surface pattern structure by adopting an electron beam lithography system, wherein the pattern caliber is 180mm, the pattern period is 420nm, the pattern line width is 130nm, and developing is carried out after exposure is finished;

(3) transferring the developed graph to a silicon substrate through reactive ion etching equipment to obtain a stamping mother board, wherein the etching power is 50W, the etching cavity pressure is 0.5Pa, the SF6 flow rate is 25SCCM, the CHF3 flow rate is 5SCCM, and the etching depth is 150 nm;

(4) coatingultraviolet curing glue 2 mixed with titanium dioxide nanoparticles 3 (with the particle size of 21nm) in a mass ratio of 1% on an imprinting mother board, covering a polyethylene terephthalate (PET) flexible substrate 1 (with the thickness of 100 mu m) on the surface of the imprinting mother board, flattening theultraviolet curing glue 2 through aroller shaft 4 at one side, irradiating and curing ultraviolet light at the other side to complete imprinting and curing of the whole caliber, and demolding to obtain a required large-caliber flexible optical super-structure surface structure; the ultraviolet light power is 124W, the moving speed of the roller shaft is 3.4mm/s, and the pressing pressure of the roller shaft is 0.2 MPa.

Embodiment 2, the invention is utilized to realize the preparation of the flexible optical super-structure surface structure with 8 inches of aperture.

(1) Plating a chromium layer with the thickness of 40nm on a silicon substrate with the diameter of 8 inches by magnetron sputtering equipment, wherein the power is 400W, and the cavity pressure is 1 mTorr;

(2) spin-coating an electron beam photoresist layer with the thickness of 80nm on a silicon substrate which is plated with a chromium layer with the thickness of 40nm and has the diameter of 8 inches;

(3) exposing a large-area super-structure surface pattern structure by adopting an electron beam lithography system, wherein the pattern aperture is 180mm, the pattern period is 450nm, the unit pattern width is 100nm, the unit pattern length is 330nm, and developing is carried out after exposure is finished;

(4) removing the exposed chromium layer by ion beam etching equipment, wherein the beam current is 150mA, and the inclination angle is 10 degrees;

(5) removing residual electron beam photoresist by reactive ion etching equipment, wherein the etching power is 5W, the etching cavity pressure is 1Pa, the O2 flow is 10SCCM, and the etching time is 5 min;

(6) transferring the graph to a silicon substrate through reactive ion etching equipment to obtain a stamping mother board, wherein the etching power is 100W, the etching cavity pressure is 0.5Pa, the SF6 flow rate is 25SCCM, the CHF3 flow rate is 5SCCM, and the etching depth is 720 nm;

(7) removing the chromium layer on the surface by wet etching of chromium removing liquid to obtain a stamping mother board;

(8) coatingultraviolet curing glue 2 mixed with titanium dioxide nanoparticles 3 (with the particle size of 21nm) accounting for 20 mass percent on an imprinting mother board, covering a polyethylene terephthalate (PET) flexible substrate 1 (with the thickness of 100 mu m) on the surface of the imprinting mother board, flattening the ultraviolet curing glue through aroller shaft 4 at one side, irradiating and curing ultraviolet light at the other side to complete imprinting and curing of the whole caliber, and obtaining a required large-caliber flexible optical super-structure surface structure after demoulding; the ultraviolet light power is 184W, the moving speed of the roller shaft is 3.4mm/s, and the pressing pressure of the roller shaft is 0.2 MPa.

Claims (6)

1. A processing method of a large-caliber flexible optical super-structure surface structure is characterized by comprising the following steps: the method comprises the following steps:

step (1), coating photoresist on a substrate template;

step (2), exposing through a photoetching system, and then developing;

transferring the pattern to a substrate material and using the pattern as a template;

step (4), coating the ultraviolet curing adhesive mixed with the high-refractive-index nano particles on a template, covering a layer of flexible substrate, and curing the ultraviolet curing adhesive by using an ultraviolet lamp exposure mode while applying mechanical pressure by using a roller;

and (5) separating the flexible substrate from the template to prepare the large-caliber flexible optical super-structure surface structure.

2. The method for processing the large-caliber flexible optical super-structure surface structure according to claim 1, wherein the method comprises the following steps: the photoresist in the step (1) is electron beam photoresist and ultraviolet photoresist.

3. The method for processing the large-caliber flexible optical super-structure surface structure according to claim 1, wherein the method comprises the following steps: the photoetching system in the step (2) is an electron beam photoetching system, an ultraviolet super-resolution photoetching system and an ultraviolet super-resolution direct writing system.

4. The method for processing the large-caliber flexible optical super-structure surface structure according to claim 1, wherein the method comprises the following steps: and (4) the pattern transfer in the step (3) comprises stripping, metal-assisted chemical corrosion, gas-assisted ion beam etching and high-density plasma etching.

5. The method for processing the large-aperture flexible optical super-structure surface device according to claim 1, wherein the method comprises the following steps: the high-refractive-index nano particles in the step (4) are titanium oxide, haar oxide, zirconium oxide, zinc oxide, cerium oxide and silicon, and the diameter of the high-refractive-index nano particles is less than or equal to 50 nm.

6. The method for processing the large-aperture flexible optical super-structure surface device according to claim 1, wherein the method comprises the following steps: the flexible substrate material in the step (4) is optical transparent polymer and metal glass, and the thickness of the flexible substrate is less than or equal to 500 mu m; the ultraviolet light source is a surface light source and a linear light source.

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