CN117341370B - Preparation method of soft photolithography stamp capable of fitting curved surface object without external force, product and application thereof - Google Patents

Abstract

The invention discloses a preparation method of a soft lithography seal attached to a curved object without external force, which comprises the following steps: (1) Synthesizing a cross-linked polymer material containing a photosensitive structure and a metal ion coordination structure at the same time, and swelling in a solvent; (2) The surface of the crosslinked polymer material is covered with an optical mask plate with a specific light transmission pattern, and the chemical structure of the region is changed under illumination, so that the microstructure appears on the surface of the crosslinked polymer material, and the soft lithography seal is obtained. The invention also discloses a soft lithography seal prepared by the method and application of the soft lithography seal in soft lithography, microstructural re-lithography of high polymer resin or regional etching of the surface of a curved object. The method directly uses ultraviolet light to trigger and does not need external force to obtain the soft lithography seal, and the obtained soft lithography seal can be reused and can be applied to curved surface micromachining.

Description

A method for preparing a soft photolithography stamp that can fit a curved surface object without external force, and its products and applications

Technical Field

The invention relates to the field of manufacturing soft photolithography stamps, and in particular to a preparation method of a soft photolithography stamp capable of fitting a curved surface object without external force, and a product and application thereof.

Background technique

Microstructure processing technology is the foundation of modern high-end manufacturing and is in great demand in aerospace, microelectronics, computer chips, optical instruments and other fields.

At present, photolithography is a commonly used micro-machining technology with the advantages of high precision and high throughput. Its process flow generally includes: (1) photoresist spin coating; (2) exposure of the area under the mask; (3) development with developer. For example, Chinese patent No. CN116136651A discloses a method for improving photoresist bleaching in wafer development, which includes the following steps: (1) placing the wafer in an oven with HMDS atmosphere to form an HMDS film with a thickness of 5 to 30 nanometers on the surface of the wafer to serve as a photoresist adhesion promoter; (2) spin coating a photoresist film on the HMDS film formed on the surface of the wafer, and then drying and curing it; (3) exposing the photoresist film with a step-and-scan I-line lithography machine; (4) rotating and washing the wafer surface with water, rotating the developer to cover the surface of the photoresist film and soak it, rotating to remove the developer, and rotating and washing again; repeating steps (1) and (4). This multi-step process often takes a long time. At the same time, photoresist is difficult to flow on a three-dimensional curved surface, which makes photolithography only suitable for microstructure processing of flat objects. More importantly, the development process requires the use of developer to continuously rinse the photolithography surface to wash away excess photoresist, which inevitably produces a large amount of wastewater, has a negative impact on the environment, and does not meet the requirements of ecological civilization construction. Therefore, how to achieve microstructure processing of three-dimensional curved surfaces without using photoresist has become a research focus.

Soft lithography is an emerging microstructure processing technology. Its material basis is a cross-linked silicone rubber (polydimethylsiloxane) stamp containing a microstructure. The stamp can be attached to the surface of a target object, or injected with a target resin liquid to achieve the microstructure manufacturing of the material. For example, the Chinese patent with publication number CN1686781A discloses a method for preparing an epoxy resin microstructure device, which uses silicone rubber (PDMS) elastic material as a micro-replication mold, and uses its reversible and repeated deformation without permanent damage to replicate the microstructure with high fidelity: first, ultraviolet lithography, silicon deep reactive ion etching technology or electroforming process are used to transfer the microstructure pattern on the mask to a photoresist substrate, silicon or metal to obtain a micro-replication template, and then the silicone rubber and the cross-linking agent are mixed in proportion, and the microstructure pattern on the template is copied to the silicone rubber sheet using the micro-replication technology, and then the epoxy resin prepolymer and the cross-linking agent are mixed and poured onto the silicone rubber mold to complete the replication of the epoxy resin microstructure.

It can be found that this technology no longer requires liquid photoresist and does not require development. At the same time, by utilizing the elasticity of silicone rubber, the stamp can be attached to the surface of a curved object under the action of external force, realizing the microstructure manufacturing of a non-planar substrate. However, once the external force is removed, the elastic stamp will quickly recover due to the entropy driving force, resulting in the need to continuously apply external force throughout the process. On the other hand, the elastic stamp needs to be obtained by pouring, curing, and peeling off the silicone rubber synthetic liquid on a microstructured master.

However, the manufacture of the master plate depends on photolithography technology, so soft lithography is considered a derivative process of existing photolithography technology and cannot truly overcome the shortcomings of photolithography. Therefore, how to overcome the dependence of the preparation of elastic stamps on photolithography technology and make soft lithography an independent micro-machining method is a technical problem that needs to be solved in this field.

Summary of the invention

The purpose of the present invention is to provide a preparation method of a soft lithography stamp that can fit a curved surface object without external force, and a product and application thereof. The method directly uses ultraviolet light to initiate and obtains the soft lithography stamp without the need for external force. The obtained soft lithography stamp can be reused and can be applied to curved surface micromachining.

The present invention provides the following technical solutions:

A method for preparing a soft photolithography stamp capable of fitting a curved surface object without external force, the method comprising the following steps:

(1) synthesizing a cross-linked polymer material containing both a photosensitive structure and a metal ion coordination structure, and swelling it in a solvent;

(2) The surface of the cross-linked polymer material is covered with an optical mask with a specific light-transmitting pattern, which causes regional chemical structure changes under light, resulting in microstructures on the surface of the cross-linked polymer material, thereby obtaining a soft lithography stamp.

The main principle of the present invention is as follows: a cross-linked polymer material containing both a photosensitive structure and a metal ion coordination structure is used. Regional illumination causes changes in the internal photosensitive structure, resulting in a rearrangement of the internal network topology of the material, a decrease in the cross-linking density and osmotic pressure, and inducing the surrounding liquid to migrate and enrich to the exposure area, thereby bulging to produce a microstructure (that is, the microstructure on the surface of the seal comes from the migration of the liquid inside the material under light induction). The entire process does not require the use of a photolithography master, and there is no external additive or waste, showing the characteristics of high efficiency and greenness.

In step (1), the cross-linked polymer material contains both a photosensitive structure and a metal ion coordination structure, wherein the photosensitive structure can be selected from one or more of a disulfide bond, an allyl sulfide bond, and an o-nitrobenzene bond; and the metal ion coordination structure can be selected from one or more of a carboxyl group, a terpyridine group, and a thiol group.

Preferably, the synthetic raw materials containing the photosensitive structure may be selected from, but not limited to, N,N'-bisacryloylcystine, 2-methyl-propane-1,3-bis(thioethyl acrylate), and o-nitrobenzyl acrylate.

Preferably, the materials used for the synthesis of the metal ion coordination structure may be selected from, but not limited to, acrylic acid, terpyridyl acryloyl polycaprolactone, and mercaptoethyl acrylate.

In step (1), the solvent may be selected from water or a non-aqueous solvent.

Preferably, water, dimethyl sulfoxide, ethyl acetate, N,N-dimethylformamide, and glycerol can be selected.

In step (2), the wavelength of the light is selected from the ultraviolet band of 200-380 nm, the intensity of the light is greater than 10 mW/cm ² , and the time of the light is greater than 5 s.

Preferably, the wavelength of the light can be 254-365 nm, the intensity of the light can be 20-50 mW/cm ² , and the time of the light can be 0.5-1 min.

In step (2), light can cause changes in the photosensitive structure within the cross-linked polymer material. The mechanisms for different photosensitive structures are as follows: disulfide bonds or allyl sulfide bonds undergo covalent bond rearrangement under light; o-nitrophenyl undergoes isomeric dissociation under light. The changes in the photosensitive structure contained in the cross-linked polymer material under light can induce the internal liquid to migrate to the illuminated area, thereby bulging and generating microstructures.

The method for preparing a soft lithography stamp that can fit a curved object without external force provided by the present invention has an efficient process and is green and environmentally friendly, and provides a new idea for soft lithography on the surface of a curved object.

The invention also provides a soft photolithography stamp obtained according to the preparation method.

An application of the soft lithography stamp obtained by the above preparation method in soft lithography, wherein the soft lithography method is:

According to the surface morphology of the target object, the initial shape of the soft lithography stamp is deformed into a matching three-dimensional shape, and the shape is fixed by immersing it in a metal ion solution. At this time, the soft lithography stamp can adhere to the surface of the target object without external force, realizing curved surface structural processing.

Furthermore, the metal ions are selected from one or more of iron ions, zinc ions, cobalt ions, nickel ions or zirconium ions.

Preferably, the salt containing metal ions can be selected from one or more of iron sulfate, zinc sulfate, cobalt chloride, nickel nitrate, and zirconium oxychloride. Further preferably, the concentration of the salt solution can be selected from 0.001-0.1 mol/L.

Furthermore, the soft lithography stamp with a fixed shape can be restored to its original shape after being immersed in a solution containing a chelating agent.

Furthermore, the chelating agent is selected from one or both of ethylenediaminetetraacetic acid and sodium citrate.

More preferably, the concentration of the chelating agent solution may be selected from 0.01-1 mol/L.

In response to the demand for micro-machining of curved objects, the soft lithography method provided by the present invention can attach a soft lithography stamp containing a microstructure to the surface of a target object, immerse it in a salt solution containing metal ions, and use coordination to fix the soft lithography stamp into a shape that matches the surface of the target object, so that the alignment and soft lithography of the curved object can be achieved without external force. Moreover, after the soft lithography stamp with a fixed specific shape/deformation is immersed in a solution containing a chelating agent, it can be restored to its original shape before fixation due to the destruction of the coordination bond, so that it can be repeatedly used for soft lithography/micro-machining of objects with different surface morphologies.

The present invention also provides an application of the soft photolithography stamp obtained by the preparation method in microstructure replication of polymer resin.

The present invention also provides an application of the soft photolithography stamp obtained by the preparation method in regional etching on the surface of a curved object.

The present invention utilizes a cross-linked polymer material containing a photosensitive structure and a metal ion coordination structure to cause a change in the internal topological structure of the material under the action of ultraviolet light, thereby preparing a soft lithography stamp. The shape of the soft lithography stamp can be further fixed by soaking in metal ions, and the fixed soft lithography stamp can be restored by soaking in a chelating solution for chelation. The method provided by the present invention does not require external force, does not require a photolithography master, and the process is simple, easy to operate, and is environmentally friendly.

Compared with the prior art, the benefits of the present invention are:

(1) The elastic stamp (soft lithography stamp) of the present invention can be directly obtained by ultraviolet light initiation without the need for external force, and the process is simple;

(2) Since the cross-linked polymer material used in the present invention contains both a photosensitive structure and a metal ion coordination structure, the soft lithography stamp prepared in the present invention can be reused through repeated interactions;

(3) In the present invention, the soft lithography stamp is obtained by self-growth of microstructures, does not rely on other types of replication or lithography, and avoids the shortcomings of lithography itself.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG1 is a schematic diagram of a method for preparing a soft lithography stamp that can fit a curved surface object without external force according to the present invention;

FIG2 is a macroscopic schematic diagram of a soft lithography stamp prepared in Example 1 of the present invention;

FIG3 is a three-dimensional white light interference micrograph of the surface microstructure of the soft lithography stamp prepared in Example 1 of the present invention;

FIG4 is a macroscopic image of the soft lithography stamp prepared in Example 1 of the present invention being attached to the surface of a glass product without external force;

FIG5 is a macroscopic picture of the soft lithography stamp prepared in Example 1 of the present invention being attached to the surface of a wooden product again without external force;

FIG6 is a macroscopic image of the soft lithography stamp prepared in Example 2 of the present invention being fixed into a specific three-dimensional shape and then restored;

FIG7 is a three-dimensional white light interference micrograph of the surface microstructure of the soft lithography stamp prepared in Example 2 of the present invention;

FIG8 is a three-dimensional white light interference micrograph of the surface microstructure of the soft lithography stamp prepared in Example 3 of the present invention;

FIG9 is a three-dimensional white light interference micrograph of the surface microstructure of the soft lithography stamp prepared in Example 4 of the present invention;

FIG10 is a three-dimensional white light interference micrograph of the surface microstructure of the soft lithography stamp prepared in Example 5 of the present invention;

FIG. 11 is a microstructure diagram of the soft lithography stamp prepared in Example 5 of the present invention to realize soft lithography of optically transparent resin.

Detailed ways

The present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be pointed out that the embodiments described below are intended to facilitate the understanding of the present invention and do not have any limiting effect on the present invention.

As shown in Figure 1, the key to the preparation of the soft lithography stamp that can fit the curved surface without external force provided by the present invention is that the cross-linked polymer material network used contains both a photosensitive structure and a metal ion coordination structure. From the basic principle, it can be seen that the prepared cross-linked polymer material contains a photosensitive structure, which causes the internal chemical topological structure of the material to be rearranged under the stimulation of an external light source, thereby affecting the cross-linking density and osmotic pressure of the exposed area of the material, causing the liquid to migrate to the illuminated area to produce a microstructure, and obtain the desired soft lithography stamp. In addition, due to the presence of the metal ion coordination structure in the cross-linked polymer material, the prepared elastic stamp can repeatedly fit objects with different surface morphologies without external force, thereby achieving the goal of soft lithography.

Example 1 (disulfide bond system + carboxylic acid coordination)

First, a polymer cross-linking agent containing a disulfide bond, N,N'-bisacryloylcystine sodium, was prepared. The raw materials used are shown in Table 1:

Table 1 Raw materials used in the preparation of disulfide bond crosslinking agents

raw material Supply Company Sodium hydroxide Sinopharm Group L-Cystine Aladdin Corporation Methanol Sinopharm Group Acryloyl chloride Merrill Ether Sinopharm Group

Preparation:

Step 1: Dissolve 10 g of sodium hydroxide in 350 mL of methanol to obtain an alkaline methanol solution;

Step 2: Dissolve 13.5 g of L-cystine in alkaline methanol and stir thoroughly to dissolve;

Step 3: In an ice water bath, add 11 mL of acryloyl chloride dropwise to the alkaline solution containing L-cystine for 20 min or more;

Step 4: The reaction was continued for 12 hours, and the solid byproducts were removed by centrifugation, and the transparent solution was retained;

Step 5: Precipitate the transparent solution in anhydrous ether, centrifuge the obtained solid precipitate from the solution, and place it in a vacuum oven and dry it at room temperature for one day to obtain the desired substance - sodium N,N'-bisacryloylcystine.

The molecular formula of N,N'-bisacryloylcystine sodium (BISS) is as follows:

Table 2 Raw materials for preparing cross-linked polymers in Example 1

Preparation:

Step 1: Dissolve 2.5 g acrylamide and 1 g BISS in 25 mL deionized water;

Step 2: Add 500 μL of 4% APS aqueous solution and 50 μL of TEMED to the solution, stir evenly, quickly transfer to the mold, and react at room temperature for 24 hours to completely cross-link it to obtain a cross-linked polymer material.

Step 3: Take out the obtained cross-linked polymer material, soak it in deionized water for one day to remove the unreacted substances, and then soak it in a 1 mg/mL 2-hydroxy-4'-(2-hydroxyethoxy)-2-methylpropiophenone (I2959) aqueous solution for storage.

Step 4: Cover the surface of the cross-linked polymer material with an optical mask with a specific light-transmitting pattern and irradiate it under ultraviolet light for 2 minutes to cause regional chemical structure changes, resulting in microstructures on the surface of the material, thereby obtaining a soft lithography stamp.

Step 5: The soft stamp is attached to the surface of the target object, deformed into a matching three-dimensional shape, and fixed by soaking in a 0.01 mol/L ferric chloride solution. It can be attached to the surface of the glass product without external force to achieve soft lithography;

Step 6: Soak the used soft stamp in 0.01 mol/L sodium citrate solution for 24 hours to restore the soft stamp to its original shape. Through ion fixation again, it can be attached to the surface of the wood product again to achieve soft lithography.

The soft lithography stamp prepared in Example 1 is shown in Figure 2. The optical mask used to prepare the soft lithography stamp is a grid structure. The lines used in the grid are opaque, the cross-regions are transparent, and microstructures grow by themselves after ultraviolet light. The three-dimensional white light interference micrograph of the surface microstructure of the soft lithography stamp prepared in Example 1 is shown in Figure 3. The optical mask used to prepare the soft lithography stamp is equidistant stripes. The soft lithography stamp prepared in Example 1 is attached to the surface of the glass product without external force as shown in Figure 4. The left side is the prepared soft lithography stamp. The stamp is attached to the surface of the glass product and the whole is immersed in a ferric chloride solution for 24 hours, which can achieve the fixation of the soft lithography stamp on the right. The fixed soft lithography stamp in Figure 4 is immersed in a sodium citrate solution for 24 hours, and the soft lithography stamp can be restored to the initial state. As shown in Figure 5, the soft lithography stamp restored to the initial state is attached to the surface of the wood product again without external force and can be fixed again.

Example 2 (allyl sulfide system + carboxylic acid coordination)

This example prepares a cross-linked polymer material containing an allyl sulfide structure, and the raw materials used are shown in Table 3:

Table 3 Raw materials for preparing cross-linked polymers in Example 2

The molecular formula of pentaerythritol tetrakis (3-mercaptopropionate) (PETMP) is as follows:

The molecular formula of ethylene glycol dimercaptopropionate (EGDMP) is as follows:

The molecular formula of 2-methylene-propane-1,3-bis(thioethyl acrylate) (MBTA) is as follows:

Preparation:

Step 1: Dissolve 10 g PETMP and 30 g EGDMP in 100 mL glycerol, and dissolve 0.5 g I819 and 1 g I651 in the above solution, add 8.5 g MBTA and 10 g sodium acrylate to obtain a homogeneous organic solution;

Step 2: Add 5 g of triethylamine to the above homogeneous organic solution, stir evenly, place in a glass slide mold, and cure for 24 hours to obtain a cross-linked polymer;

Step 3: The obtained cross-linked polymer was fully swollen in a 1 mg/mL glycerol solution of I819;

Step 4: placing an optical mask with a specific light-transmitting pattern on the surface of the obtained cross-linked polymer and irradiating it with an ultraviolet mercury lamp for 10 minutes to obtain a soft lithography stamp with a certain surface microstructure through internal liquid migration;

Step 5: The obtained soft lithography stamp is deformed into a specific shape and immersed in a zinc sulfate glycerol solution for fixation, and it can be deformed into a three-dimensional shape.

Among them, the soft lithography stamp prepared in Example 2 is fixed to a specific three-dimensional shape and restored as shown in Figure 6. First, the soft lithography stamp is cut into rectangular strips and bent into a "6" shape. It is immersed in a zinc sulfate glycerol solution to fix the shape, and the shape can be further restored to its initial state by a chelating solution. The three-dimensional white light interference micrograph of the surface microstructure of the soft lithography stamp prepared in Example 2 is shown in Figure 7. The optical mask used to prepare the soft lithography stamp is an equidistant stripe. .

Example 3 (Disulfide bond system + terpyridine coordination)

This example prepares a cross-linked polymer material containing a terpyridine coordination group, and the raw materials used are shown in Table 4:

Table 4 Raw materials for preparing cross-linked polymers in Example 3

Preparation:

Step 1: 20 g of ε-caprolactone, 2 g of 1,5,7-triazabicyclo[4.4.0]dec-5-ene, and 20 g of terpyridine were reacted at 120° C. in a nitrogen atmosphere for 10 h, the polymer was easily dissolved in toluene and precipitated in cold methanol, and the obtained product was vacuum dried at room temperature overnight to obtain polycaprolactone with terpyridine terminal groups;

Step 2: Dissolve 20 g of the terpyridine-terminated polycaprolactone obtained in step 1, 1.08 g of acryloyl chloride, and 1.22 g of triethylamine in 100 mL, and react at 80° C. for 20 h. Precipitate the mixed solution after the reaction in cold ethanol, and dry the obtained solid under vacuum at room temperature for 24 h to obtain the desired polymerizable monomer TPyA containing a terpyridine group. The reaction equation is as follows;

Step 3: 0.5 g TPyA, 10.0 g isopropylacrylamide, and 0.1 g BISAC were dissolved in 10 g DMF, followed by the addition of 0.1 g BPO and the reaction was carried out at 80 °C for 10 h.

The molecular formula of N,N'-bisacryloylcystine (BISAC) is as follows:

Step 4: The obtained cross-linked polymer was fully swollen in DMF containing 1 mg/mL I819;

Step 5: Place a mask with a certain light-transmitting pattern on the polymer and irradiate it with ultraviolet light for 1 minute to obtain a soft lithography template.

The three-dimensional white light interference micrograph of the surface microstructure of the soft lithography stamp prepared in Example 3 is shown in FIG8 . The optical mask used to prepare the soft lithography stamp is an opaque circular shape.

Example 4 (o-nitrobenzene system + carboxylic acid coordination)

This example prepares a cross-linked polymer material containing an o-nitrobenzene photosensitive structure, and the raw materials used are shown in Table 5:

Table 5 Raw materials for preparing cross-linked polymers in Example 4

Preparation:

Step 1: Dissolve 15 g of o-nitrobenzyl alcohol and 10 g of sodium acrylate in 150 mL of dichloromethane, add 14.4 mL of triethylamine, the reaction solution becomes clear and is cooled to 10°C;

Step 2: 8.5 mL of acryloyl chloride was added dropwise to the clear solution obtained in step 1, and the reaction was stirred at room temperature for 24 h. After filtering the solid byproducts, the clear solution was washed with deionized water and brine respectively, and the excess water was absorbed with anhydrous magnesium sulfate. The clear solution was filtered to obtain a final light yellow product (NA) by evaporating the solvent. The molecular formula is as follows;

Step 3: 1 g NA, 5 g N,N-dimethylacrylamide, 100 mg ethylene glycol dimethacrylate, 100 mg I819 and 1.6 mg light absorber carmine were mixed thoroughly and cured under visible light for 5 min, and then the obtained solid polymer was swollen in dimethyl sulfoxide for 24 h to remove unreacted components and swell the cross-linked polymer.

Step 4: Place the cross-linked polymer under a photomask with a certain pattern and irradiate with ultraviolet light for 30 minutes. Due to the increase in osmotic pressure in the exposed area, the surrounding liquid migrates to this area, and finally a soft lithography stamp is obtained.

The three-dimensional white light interference micrograph of the surface microstructure of the soft lithography stamp prepared in Example 4 is shown in FIG9 . The optical mask used to prepare the soft lithography stamp is “S-S”.

Example 5 (Disulfide bond system + thiol coordination)

This example prepares a cross-linked polymer material containing a thiol coordination structure, and the raw materials used are shown in Table 6:

Table 6 Raw materials for preparing cross-linked polymers in Example 5

Preparation:

Step 1: Add 25 g HEA, 2.5 g mercaptoethyl acrylate, 0.25 g BISAC, and 0.25 g AIBN into a beaker and stir well;

Step 2: Pour the mixed solution into a mold and polymerize at 70°C for 5 hours;

Step 3: demoulding to obtain the cross-linked polymer, and immersing it in liquid paraffin containing 2 mg/mL I819 for 48 h;

Step 4: Place a photomask with a certain pattern on the surface of the swollen cross-linked polymer and irradiate with ultraviolet light for 60 minutes to obtain a soft photolithography template with a microstructure.

Step 5: Coat the surface of the obtained soft lithography stamp with an optically transparent resin precursor solution (formula: 16 g of isobornyl acrylate, 8 g of 2-phenoxyethyl acrylate, 0.5 g of 1,6-hexanediol diacrylate, and 0.75 g of 2,4,6-trimethylbenzoyl-diphenylphosphine), irradiate with ultraviolet light for 2 minutes, and peel off to obtain an optically transparent resin with a specific microstructure on the surface, which can realize the manufacture of a microlens array.

The three-dimensional white light interference micrograph of the surface microstructure of the soft lithography stamp prepared in Example 5 is shown in FIG10 . The soft lithography template is prepared by superimposing two stripes, indicating that the materials used in the present invention can be superimposed and used. The microstructure of the soft lithography stamp prepared in Example 5 for optically transparent resin soft lithography is shown in FIG11 . The left side is a soft lithography stamp with a hexagonal honeycomb structure grown by self-growth through an optical mask, and the right side is a soft lithography material obtained by casting an optical resin on the stamp, curing it, and peeling it off.

Claims (11)

1. A method for preparing a soft lithography stamp that can fit a curved surface object without external force, characterized in that the preparation method comprises the following steps: (1) synthesizing a cross-linked polymer material containing both a photosensitive structure and a metal ion coordination structure, and swelling it in a solvent; (2) The surface of the cross-linked polymer material is covered with an optical mask with a specific light-transmitting pattern, and the regional chemical structure changes under light, so that a microstructure appears on the surface of the cross-linked polymer material, thereby obtaining a soft lithography stamp; In step (1), the cross-linked polymer material contains both a photosensitive structure and a metal ion coordination structure, wherein the photosensitive structure can be selected from one or more of a disulfide bond, an allyl sulfide bond, and an o-nitrobenzene bond; and the metal ion coordination structure can be selected from one or more of a carboxyl group, a terpyridine group, and a thiol group. 2. The method for preparing a soft lithography stamp capable of conforming to a curved surface object without external force according to claim 1, characterized in that in step (2), the wavelength of the illumination is selected from the ultraviolet band of 200-380nm, the intensity of the illumination is greater than 10mW/ ^cm2 , and the illumination time is greater than 5s. 3. A soft lithography stamp obtained by the preparation method according to any one of claims 1-2. 4. Use of the soft photolithography stamp according to claim 3 in microstructure replication of polymer resin. 5. Use of the soft lithography stamp according to claim 3 for etching a region on the surface of a curved object. 6. An application of a soft lithography stamp in soft lithography, characterized in that the soft lithography method is: According to the surface morphology of the target object, the initial shape of the soft lithography stamp is transformed into a matching three-dimensional shape, and the shape is fixed by immersing it in a metal ion solution. At this time, the soft lithography stamp can adhere to the surface of the target object without external force, realizing the structural processing of the curved surface; The method for preparing the soft lithography stamp comprises the following steps: (1) synthesizing a cross-linked polymer material containing both a photosensitive structure and a metal ion coordination structure, and swelling it in a solvent; (2) The surface of the cross-linked polymer material is covered with an optical mask with a specific light-transmitting pattern, which causes regional chemical structure changes under light, resulting in microstructures on the surface of the cross-linked polymer material, thereby obtaining a soft lithography stamp. 7. The use of the soft lithography stamp according to claim 6, characterized in that the metal ions are selected from one or more of iron ions, zinc ions, cobalt ions, nickel ions or zirconium ions. 8 . The use of the soft lithography stamp according to claim 6 , wherein the shape-fixed soft lithography stamp can be restored to its original shape after being immersed in a solution containing a chelating agent. 9 . The use of a soft lithography stamp according to claim 8 , wherein the chelating agent is selected from one or both of ethylenediaminetetraacetic acid and sodium citrate. 10. The use of a soft lithography stamp according to claim 6, characterized in that in step (1), the cross-linked polymer material contains both a photosensitive structure and a metal ion coordination structure, wherein the photosensitive structure can be selected from one or more of a disulfide bond, an allyl sulfide bond, and an o-nitrobenzene bond; and the metal ion coordination structure can be selected from one or more of a carboxyl group, a terpyridine group, and a thiol group. 11. The use of a soft lithography stamp according to claim 6, characterized in that in step (2), the wavelength of the light is selected from the ultraviolet band of 200-380nm, the intensity of the light is greater than 10mW/ ^cm2 , and the time of the light is greater than 5s.