A high refractive index negative OC photoresist without undercuts, a method for preparing and applying a photocured pattern

Abstract

The application belongs to the technical field of high polymer materials, and relates to a high-refractive negative OC photoresist without undercut, a preparation method of a photocured pattern and application. The high-refractive negative OC photoresist comprises the following raw materials in parts by weight: high-refractive nanoparticles 10-35 parts, photocurable monomers 1-10 parts, alicyclic epoxy monomers 1-10 parts, a photoinitiator 1.5-4 parts, a surfactant 0.01-0.5 parts and a solvent 25-75 parts. By adding the alicyclic epoxy monomers to replace the acrylic monomers in the formula, the alicyclic epoxy monomers can be chemically bonded with the photocurable monomers and the high-refractive nanoparticles to form a network structure between molecules; the alicyclic epoxy monomers can also form hydrogen bond interaction with the silanol groups on the surface of a substrate, so that the adhesion of the film layer is improved, the heat resistance of the film layer is improved, the undercut caused by the internal stress of the square island pattern is effectively resisted by increasing the adhesion, and the integrity of the pattern is improved.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of high polymer materials, and relates to a high-refractive negative OC photoresist without undercut, a preparation method of a photocured pattern, and application. BACKGROUND

[0002] The micro lens array MLA is applied to an organic light emitting diode OLED, can improve light extraction efficiency and thus improve screen brightness, and the principle is that a low-refractive OC (Over Coating) photoresist and a high-refractive OC photoresist form an optical structure with periodic refractive index changes through a photolithography process, so that light can converge from both sides to the central light emission, thereby improving the forward light extraction efficiency.

[0003] The existing MLA structure mainly includes the following two structures: ① low-refractive photoresist patterning, high-refractive OC photoresist full-area coating on the patterned low-refractive OC photoresist, but the high-refractive OC film with full-area coating has a large internal stress, which is prone to breakage when bending, and cannot be applied to a folding screen. ② high-refractive OC photoresist patterning, low-refractive OC photoresist full-area coating, which can relieve stress, be applied to a folding screen, and has higher light extraction efficiency. However, when the high-refractive negative OC photoresist is made into a square island pattern, undercut phenomenon (bottom Peeling) usually occurs at both sides of the bottom, a bevel or arc is formed on the side of the bottom metal film layer, the undercut affects the repeatability of the process, reduces the light extraction efficiency, and is also prone to cause Peeling of the subsequent Normal OC film layer, thereby affecting the product yield.

[0004] To this end, the existing Chinese patent document (publication number: CN107446452A, publication date: December 8, 2017) discloses a composition for forming an organic antireflection coating suitable for negative development, which not only enhances the adhesion to photoresist while having high refractive index and high etching rate, but also improves the pattern profile such as undercut. However, the composition contains isocyanurate compounds, which are prone to yellowing when high-temperature baking, and will release toxic caprolactam gas, and also has deficiencies in mechanical properties and heat resistance.

[0005] In view of this, the present application is proposed. SUMMARY

[0006] The present application aims to overcome the shortcomings of the prior art, and provides a high-refractive negative OC photoresist without undercut, a preparation method of a photocured pattern, and application.

[0007] To achieve the above-mentioned purpose, the present application provides the following technical solutions:

[0008] In a first aspect, the present application provides a high refractive index negative OC photoresist without undercut, comprising the following raw materials in parts by weight: high refractive index nanoparticles 10-35 parts, photocurable monomers 1-10 parts, alicyclic epoxy monomers 1-10 parts, photoinitiators 1.5-5 parts, surfactants 0.01-0.5 parts, and solvents 25-75 parts.

[0009] Preferably, the high refractive index negative OC photoresist without undercut comprises the following raw materials in parts by weight: high refractive index nanoparticles 10-25 parts, photocurable monomers 4-8 parts, alicyclic epoxy monomers 5-8 parts, photoinitiators 2-4 parts, surfactants 0.1-0.3 parts, and solvents 25-75 parts.

[0010] Specifically, the high refractive index nanoparticles are selected from one or two of SnO2, In2O3, TiO2, ZrO2, Al2O3, and ZnO; when two of the high refractive index nanoparticles are used, the mass ratio of the two is 1:1. Preferably, the high refractive index nanoparticles are 10-15 parts.

[0011] Specifically, the high refractive index nanoparticles in the present application are modified by ligands, and the surface is connected with acrylate ligands, which are purchased from JSR, Japan Catalyst and the like. Further, the median particle size (D50) of the high refractive index nanoparticles is 5-22 nm, and the refractive index is 1.8-2.0. It should be noted that, on the one hand, the high refractive index nanoparticles can increase the refractive index of the photoresist, and also affect the progress and mechanism of the polymerization or curing reaction, thereby indirectly adjusting the internal stress. On the other hand, the high refractive index nanoparticles will have a strong induced polarization effect on the surrounding hybrid, causing a significant change in the dissolution behavior, thereby achieving high photosensitivity and high-resolution photoetching effect.

[0012] Specifically, the photocurable monomers include monofunctional (meth)acrylate monomers and bifunctional (meth)acrylate monomers.

[0013] Preferably, the viscosity of the monofunctional (meth)acrylate monomers is 1-20 cps, and the glass transition temperature Tg is -60-110℃, including one or more of tetrahydrofurfuryl acrylate, cyclotrimethylolpropane formal acrylate, ethoxyethoxyethyl acrylate, 3,3,5-trimethylcyclohexyl acrylate, lauryl acrylate, tetrahydrofurfuryl methacrylate, lauryl methacrylate, cyclohexyl methacrylate, isobornyl acrylate, isobornyl methacrylate, isodecyl acrylate, iso-octyl acrylate, isodecyl methacrylate, and lauryl methacrylate.

[0014] Preferably, the viscosity of the monofunctional (meth)acrylate monomer is 3-18 cps, and the glass transition temperature Tg is -60-15℃; more preferably, the viscosity of the monofunctional (meth)acrylate monomer is 3-10 cps, and the Tg is -60--15℃, the monofunctional (meth)acrylate monomer in this viscosity range and this Tg range is selected, which has the characteristics of low curing shrinkage, good weather resistance, good flexibility, good water resistance, etc., can adjust the too large Tg of the formula caused by the addition of high refractive nanoparticles, and can adjust the viscosity and refractive index, and improve the flexibility.

[0015] Preferably, the viscosity of the difunctional (meth)acrylate monomer at room temperature is 10-150 cps, and it can be selected from one or more of polyethylene glycol acrylate, polyethylene glycol (200) dimethacrylate, polyethylene glycol (400) dimethacrylate, polyethylene glycol (300) dimethacrylate, polyethylene glycol (600) dimethacrylate, polyethylene glycol (200) dimethacrylate, polyethylene glycol (400) dimethacrylate, polyethylene glycol (600) dimethacrylate.

[0016] It needs to be emphasized that the present application adds monofunctional (meth)acrylate monomer and difunctional (meth)acrylate monomer with specific content and mass ratio in the raw material, so that the photoresist has better wettability and flowability while maintaining strong cohesion, so that the glue layer is fully filled to the recesses and / or gaps on the surface of the layer (silicon nitride) it adheres to, improving the engagement and inlay effect, thereby improving the contact area between the glue layer and the layer it adheres to, and achieving the improvement of adhesion.

[0017] Specifically, the alicyclic epoxy monomer is an alicyclic epoxy monomer containing an unsaturated double bond and an epoxy group, wherein the unsaturated double bond specifically refers to the double bond in the acrylate functional group, and the epoxy group specifically refers to a cyclohexyl three-membered epoxy group; the alicyclic epoxy monomer containing an unsaturated double bond and an epoxy group is specifically at least one of the structures shown in formula (1) to formula (5):

[0018]

[0019]

[0020] Among them, some functional groups (such as ether bond, epoxy group) in the alicyclic epoxy monomer can form hydrogen bonds with the carboxyl group in the acrylic monomer, which can form a network structure between molecules, in addition, it can also form hydrogen bonds with the silicon alcohol group on the surface of the substrate, thereby significantly improving the adhesion of the film layer, and improving the heat resistance of the film layer; by increasing the adhesion, the undercut caused by the internal stress of the square island pattern can be effectively resisted, and the integrity of the pattern is improved. In addition, the epoxy group (-O-) on the alicyclic epoxy monomer can form a covalent bond with the oxygen ion (O 2-) to form a more stable connection, increasing the cohesion of the film layer and making it less prone to peeling. The oxygen atoms in the epoxy groups can bond with the vacant positions on the surface of zirconium oxide, forming covalent bonds or hydrogen bonds. This reaction increases the adhesion between the film layer and the substrate, reducing the phenomenon of detachment caused by thermal stress, mechanical stress, etc., thereby achieving physical and chemical adsorption between the two. This reaction mechanism significantly improves the adhesion of the photocured pattern.

[0021] Further, the mass ratio of the monofunctional (meth)acrylate monomer, the difunctional (meth)acrylate monomer, and the alicyclic epoxy monomer is (2-3):(3-5):(5-8). The present inventors have found that, under the above specific mass ratio, not only can the volume shrinkage caused by the decrease in intermolecular distance during the curing process of the photoresist be offset, but also the dispersibility of the high-refractive nanoparticles in the photoresist can be improved. Since the alicyclic epoxy resin has a compact rigid molecular structure and a high crosslinking density after curing, the film layer can have excellent tensile strength and stability. At the same time, the oxygen atoms of the alicyclic epoxy monomer can form hydrogen bonds with the hydroxyl groups on the surface of the zirconium oxide nanoparticles, which can enhance the dispersibility of the nanoparticles. These non-covalent interactions can improve the adhesion between the film layer and the substrate, thereby improving the adhesion of the photocured pattern.

[0022] However, these forces are usually weaker than covalent bonds, and since the crosslinking density of the alicyclic epoxy monomer is high, the cured product is prone to be brittle and have poor toughness. Therefore, by introducing specific monofunctional (meth)acrylate and difunctional (meth)acrylate with low viscosity and low Tg into the formulation of the photoresist, the flexibility of the film layer can be improved, the internal stress caused by curing shrinkage can be reduced, the curing rate can be improved, the ability of the photocured film to resist temperature and humidity (85℃, 85%) can be enhanced, the storage stability can be improved, and problems such as peeling of the cured film can be avoided.

[0023] Specifically, the raw material of the present application is an acrylic system, which does not need to add a cationic photoinitiator, but only needs to add a free radical initiator. Therefore, the photoinitiator includes a free radical photoinitiator, such as an oxime ester photoinitiator, including one or more of 1-(4-phenylthiophenyl)-octane-1,2-dione-2-benzoic acid oxime ester (OXE-01), 1-[9-ethyl-6-(2-methylbenzoyl)-9H-carbazol-3-yl]ethanone 1-(O-acetyloxime) (OXE-02), OXE-E12, and OXPI-405.

[0024] Further, in the present application, only a radical initiator is added without adding a cationic photoinitiator, so as to avoid ring-opening reaction and polymerization of the alicyclic epoxy monomer, and the main polymerization reaction in the system is the photocuring reaction of the monofunctional (meth)acrylate monomer and the bifunctional (meth)acrylate monomer, thereby forming a polymer. In this way, the alicyclic epoxy monomer can more chemically bond with the oxygen ions (O 2- ) on the surface of the high-refractive nanoparticles to form a stable connection and increase the adhesion.

[0025] Specifically, the surfactant includes F-114, F-553, F-562 or F-570 of DIC Corporation, FC-135 or FC-170C manufactured by 3M Corporation, S-211, S-221, S-231 or S-242 manufactured by AGC Corporation, and BYK-300, BYK-301, BYK-368P, BYK-302, BYK-306, BYK-310, BYK-313, BYK-320, BYK-370, BYK-377, BYK-378 or BYK-394 manufactured by BYK Corporation. The above surfactants help to reduce the surface tension and surface tension gradient of the film layer, thereby improving the wettability and adhesion of the film layer on the substrate.

[0026] Specifically, the solvent is 3-methoxy-1-butanol, diacetone alcohol, cyclohexanone, N-methyl-2-pyrrolidone, diethylene glycol ethyl methyl ether, propylene glycol methyl ether, dipropylene glycol monomethyl ether, dipropylene glycol monoethyl ether, triethylene glycol monomethyl ether, triethylene glycol monoethyl ether, ethyl acetate, butyl acetate, ethyl lactate, 3-methoxybutyl acetate, 3-methoxy-3-butyl acetate or propylene glycol methyl ether acetate.

[0027] In a second aspect, the present application further provides a photocured pattern formed by the above-mentioned high-refractive negative OC photoresist without underfill, which can be applied to, but not limited to, a microlens array, an array planarization film pattern, a protective film pattern, an insulating film pattern and the like, and is particularly suitable for a microlens array.

[0028] Specifically, the preparation of the above-mentioned photocured pattern is prepared by coating the above-mentioned photoresist material on a substrate, and then exposing and developing to prepare a photocured pattern. The specific preparation method is as follows:

[0029] Step 1, coating the above-mentioned high-refractive negative OC photoresist on a substrate; wherein the coating method is spin coating, flow coating, roll coating, slot coating or other coating methods, and the slot coating is preferred;

[0030] Step 2, after coating, the film is heated and dried to remove volatile components to obtain a smooth film; wherein the heating temperature is 70-90°C.

[0031] Step 3, the obtained adhesive film is irradiated with ultraviolet light through a mask plate, the adhesive film cured by ultraviolet irradiation is contacted with a developing solution to dissolve the unexposed area for development; after development, the pattern is washed with water, dried with nitrogen, and then post-baked at a temperature of 70-100℃ for 10-100min to obtain a photocured pattern with a thickness of 2-6μm. Preferably, the thickness of the photocured pattern is 2-3μm.

[0032] Finally, the present application also provides an image display device comprising the above-mentioned photocured pattern, which includes a liquid crystal display screen, an organic light-emitting diode, a flexible display, etc., but is not limited thereto, and can also include all known image display devices applicable to the technical field.

[0033] Compared with the prior art, the technical scheme provided by the present application has the following beneficial effects:

[0034] 1) The present application can form a network structure between molecules by adding an aliphatic epoxy monomer to replace an acrylic monomer in the formula, which can form hydrogen bonds with the light-curable monomer and high-refractive nanoparticles; in addition, the aliphatic epoxy monomer can also form hydrogen bonds with the silicon alcohol groups on the surface of the substrate, thereby significantly improving the adhesion of the film layer and the heat resistance of the film layer; by increasing the adhesion, the undercut caused by the internal stress of the square island pattern can be effectively resisted, and the integrity of the pattern is improved.

[0035] 2) By adjusting the weight proportions of the raw materials, under a specific weight ratio, the mass ratio of monofunctional (methyl) acrylate, difunctional (methyl) acrylate and alicyclic epoxy monomer is (2-3):(3-5):(5-8), which not only offsets the volume shrinkage of the photoresist due to the reduction of intermolecular distance during the curing process, but also improves the dispersibility of high-refractive nanoparticles in the photoresist; due to the tight rigid molecular structure of the alicyclic epoxy monomer, the crosslinking density after curing is large, which can make the film layer have excellent tensile strength and stability; at the same time, the oxygen atom of the alicyclic epoxy monomer forms a hydrogen bond with the hydroxyl group on the surface of the zirconia nanoparticles, which can enhance the dispersibility of the nanoparticles. These non-covalent interactions can improve the adhesion between the photoresist and the substrate, thereby improving the adhesion of the film layer. In summary, the high-refractive negative OC photoresist provided by the present application has low cost, stable performance, simple preparation method, strong operability, good repeatability, and wide application prospect. BRIEF DESCRIPTION OF DRAWINGS

[0036] The accompanying drawings, which are incorporated into and form a part of the specification, are used to explain the principles of the present application together with the specification.

[0037] In order to more clearly illustrate the technical solutions of the embodiments of the present application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiments or the prior art description. Obviously, for those skilled in the art, other drawings can also be obtained from these drawings without any creative effort.

[0038] Figure 1 A flow chart of a preparation method of a high-refractive negative OC photoresist based on undercut-free photo-cured pattern is provided in the present application.

[0039] Figure 2 A square island pattern without undercut in the embodiments 1-6 of the present application.

[0040] Figure 3 A square island pattern with undercut in the comparative examples 1-4 of the present application. DETAILED DESCRIPTION

[0041] The exemplary embodiments will be described in detail herein below, and the embodiments described in the following exemplary embodiments do not represent all the embodiments consistent with the present application. Rather, they are merely examples of some aspects of the present application as detailed in the appended claims.

[0042] In order for those skilled in the art to better understand the technical solutions of the present application, the present application will be further described in detail below in combination with the drawings and embodiments.

[0043] Embodiment 1

[0044] The present embodiment provides a high-refractive negative OC photoresist (I) without undercut, which comprises the following raw materials in parts by weight:

[0045] High-refractive nanoparticles 10 parts, photo-curable monomer 5 parts, alicyclic epoxy monomer 5 parts, photoinitiator 2 parts, surfactant 0.1 part, solvent 50 parts. Among them:

[0046] The high-refractive nanoparticles are ZrO2 with a median particle size of 5 nm and a refractive index of 1.8.

[0047] The photo-curable monomer comprises 2 parts of tetrahydrofurfuryl acrylate and 3 parts of polyethylene glycol acrylate.

[0048] The alicyclic epoxy monomer is 3,4-epoxycyclohexylmethyl methacrylate (i.e. the structure shown in formula 1), the photoinitiator is 1-(4-phenylthiophenyl)-octane-1,2-dione-2-benzene carboxylic hydroxylamine ester (OXE-01), the surfactant is BYK-313 manufactured by BYK Company, and the solvent is 3-methoxybutyl acetate (CAS number: 4435-53-4).

[0049] Further, the mass ratio of the above-mentioned monofunctional (meth)acrylate monomer, i.e. tetrahydrofurfuryl acrylate, difunctional (meth)acrylate monomer, i.e. polyethylene glycol acrylate, and alicyclic epoxy monomer is 2:3:5.

[0050] Example 2

[0051] The present example provides a high refractive index negative OC photoresist (two) without undercuts, which comprises the following raw materials in parts by weight:

[0052] High refractive index nanoparticles 10 parts, photocurable monomer 4 parts, alicyclic epoxy monomer 5 parts, photoinitiator 5 parts, surfactant 0.1 parts, solvent 50 parts. Among them:

[0053] The high refractive index nanoparticles are a mixture of SnO2 and TiO2, and the mass ratio of the two is 1:1, the median particle size is 15 nm, and the refractive index is 2.0.

[0054] The photocurable monomer includes 2 parts of ethoxyethoxyethyl acrylate and 2 parts of polyethylene glycol acrylate.

[0055] The alicyclic epoxy monomer is 3,4-epoxycyclohexylmethyl methacrylate (i.e. the structure shown in formula 1), the photoinitiator is 1-(4-phenylthiophenyl)-octane-1,2-dione-2-benzene hydroxamic acid ester (OXE-01), the surfactant is BYK-313 manufactured by BYK Company, and the solvent is 3-methoxybutyl acetate (CAS number: 4435-53-4).

[0056] Further, the mass ratio of the above-mentioned monofunctional (meth)acrylate monomer, i.e. ethoxyethoxyethyl acrylate, difunctional (meth)acrylate monomer, i.e. polyethylene glycol acrylate, and alicyclic epoxy monomer is 2:3:5.

[0057] Example 3

[0058] The present example provides a high refractive index negative OC photoresist (three) without undercuts, which comprises the following raw materials in parts by weight:

[0059] High refractive index nanoparticles 15 parts, photocurable monomer 6 parts, alicyclic epoxy monomer 6 parts, photoinitiator 5 parts, surfactant 0.2 parts, solvent 50 parts. Among them:

[0060] The high refractive index nanoparticles are SnO2 with a median particle size of 10 nm, and the refractive index is 2.2.

[0061] The photocurable monomer includes 2 parts of lauryl acrylate and 4 parts of polyethylene glycol (200) diacrylate.

[0062] The alicyclic epoxy monomer is shown in the structure of formula 2, the photoinitiator is 1-(4-phenylthiophenyl)-octane-1,2-dione-2-benzene carboxylic hydroxime ester (OXE-01), the surfactant is BYK-313 manufactured by BYK Company, and the solvent is 3-methoxybutyl acetate (CAS number: 4435-53-4).

[0063] Further, the mass ratio of the above-mentioned monofunctional (meth) acrylic ester monomer, i.e. lauryl acrylate, difunctional (meth) acrylic ester monomer, i.e. polyethylene glycol (200) diacrylate, and alicyclic epoxy monomer is 2:4:6.

[0064] Example 4

[0065] The present example provides a high refractive index negative OC photoresist (four) without undercut, which comprises the following raw materials in parts by weight:

[0066] The high refractive index nanoparticle is ZrO2 with a median particle size of 12 nm and a refractive index of 1.8.

[0067] The high refractive index nanoparticle is ZrO2 with a median particle size of 12 nm and a refractive index of 1.8.

[0068] The photocurable monomer comprises 2 parts of tetrahydrofurfuryl acrylate and 4 parts of polyethylene glycol (200) diacrylate.

[0069] The alicyclic epoxy monomer is shown in the structure of formula 2, the photoinitiator is 1-(4-phenylthiophenyl)-octane-1,2-dione-2-benzene carboxylic hydroxime ester (OXE-01), the surfactant is BYK-313 manufactured by BYK Company, and the solvent is 3-methoxybutyl acetate (CAS number: 4435-53-4).

[0070] Further, the mass ratio of the above-mentioned monofunctional (meth) acrylic ester monomer, i.e. tetrahydrofurfuryl acrylate, difunctional (meth) acrylic ester monomer, i.e. polyethylene glycol (200) diacrylate, and alicyclic epoxy monomer is 2:4:6.

[0071] Example 5

[0072] The present example provides a high refractive index negative OC photoresist (five) without undercut, which comprises the following raw materials in parts by weight:

[0073] The high refractive index nanoparticle is ZrO2 with a median particle size of 12 nm and a refractive index of 1.8.

[0074] The high refractive index nanoparticle is ZrO2 with a median particle size of 12 nm and a refractive index of 1.8.

[0075] The photocurable monomer includes 3 parts of lauryl methacrylate and 5 parts of polyethylene glycol (200) diacrylate.

[0076] The alicyclic epoxy monomer is shown in formula 4, the photoinitiator is 1-(4-phenylthiophenyl)-octane-1,2-dione-2-benzoic acid oxime ester (OXE-01), the surfactant is BYK-310 manufactured by BYK Company, and the solvent is diacetone alcohol (CAS number: 123-42-2).

[0077] Further, the mass ratio of the above-mentioned monofunctional (meth)acrylate monomer, i.e. lauryl methacrylate, difunctional (meth)acrylate monomer, i.e. polyethylene glycol (200) diacrylate, and alicyclic epoxy monomer is 3:5:8.

[0078] Example 6

[0079] The present example provides a high refractive index negative OC photoresist (six) without undercut, which comprises the following raw materials in parts by weight:

[0080] The high refractive index nanoparticle is ZrO2 with a median particle size of 5 nm and a refractive index of 1.8.

[0081] The photocurable monomer includes 3 parts of lauryl methacrylate and 5 parts of polyethylene glycol (200) diacrylate.

[0082] The photocurable monomer includes 3 parts of lauryl methacrylate and 5 parts of polyethylene glycol (200) diacrylate.

[0083] The alicyclic epoxy monomer is shown in formula 5, the photoinitiator is 1-(4-phenylthiophenyl)-octane-1,2-dione-2-benzoic acid oxime ester (OXE-01), the surfactant is BYK-310 manufactured by BYK Company, and the solvent is propylene glycol methyl ether acetate (CAS number: 108-65-6).

[0084] Further, the mass ratio of the above-mentioned monofunctional (meth)acrylate monomer, i.e. lauryl methacrylate, difunctional (meth)acrylate monomer, i.e. polyethylene glycol (200) diacrylate, and alicyclic epoxy monomer is 3:5:8.

[0085] Comparative Example 1

[0086] On the basis of Example 1, the difference between Example 1 and Comparative Example 1 is that the amount of high refractive index nanoparticle used in Comparative Example 1 is 40 parts, which exceeds the aforementioned weight fraction range of 10-35 parts.

[0087] Comparative Example 2

[0088] On the basis of Example 1, different from Example 1 is that the amount of high refractive nanoparticles in Comparative Example 2 is 5 parts, i.e. not falling into the range of 10-35 parts by weight.

[0089] Comparative Example 3

[0090] On the basis of Example 1, different from Example 1 is that the amount of alicyclic epoxy monomer in Comparative Example 3 is 2 parts, i.e. the mass ratio of monofunctional (meth)acrylate monomer i.e. tetrahydrofurfuryl acrylate, difunctional (meth)acrylate monomer i.e. polyethylene glycol acrylate, alicyclic epoxy monomer is 2:3:2.

[0091] Comparative Example 4

[0092] On the basis of Example 1, different from Example 1 is that the alicyclic epoxy monomer in Comparative Example 4 is 3,4-epoxycyclohexyl carboxylic acid-3',4'-epoxycyclohexyl methyl ester (CAS: 2386-87-0).

[0093] Here, the applicant needs to explain that the preparation method of the undercut high refractive negative OC photoresist in the present application is: the above-mentioned raw materials are added into a sample bottle according to the corresponding weight fraction, mixed and stirred uniformly, and filtered, to obtain the high refractive negative OC photoresist.

[0094] Referring to Figure 1 , the preparation method of the photo-cured pattern based on the above-mentioned high refractive negative OC photoresist is:

[0095] Step 1, the above-mentioned high refractive negative OC photoresist is coated on a substrate; wherein the coating method adopts spin coating method, flow coating method, roll coating method, slot coating method and other coating methods, preferably slot coating method;

[0096] Step 2, after coating, the film is heated and dried to remove volatile components, to obtain a smooth film; wherein the heating temperature is 70-90°C;

[0097] Step 3, the obtained film is irradiated with ultraviolet light through a mask plate, the film cured by ultraviolet irradiation is contacted with a developing solution to dissolve the unexposed area for development; after development, the pattern is washed with water, dried with nitrogen, and then post-baked at a temperature of 70-100°C for 10-100 min to obtain a photo-cured pattern with a thickness of 2-6 μm.

[0098] Preferably, the thickness of the photo-cured pattern is 2-3 μm.

[0099] Performance test

[0100] ①Adhesion: The film was cut into a hundred squares using a hundred squares cutting sheet and a knife. A 3M transparent tape was adhered to the cut squares and pressed firmly to the film surface and the cut square area. The peeling phenomenon and degree of the film on the substrate were observed to determine its ASTM grade. The ASTM grade is as follows: 5B - the cut edge is smooth and the grid edge has no peeling; 4B - the peeling area in the grid area is ≤5%; 3B - the peeling area in the grid area is greater than 5% to 15%; 2B - the peeling area in the grid area is greater than 15% to 35%; IB - the peeling area in the grid area is greater than 35% to 65%; 0B - the peeling area in the grid area is greater than 65%.

[0101] ②Undercut width: The square island patterned sample prepared by photolithography was cut into small pieces, and then the undercut width l of the single side of the square island pattern with a 15 μm CD value was observed using SEM after cutting with FIB, with the unit being μm.

[0102] ③Refractive index:

[0103] A 5 cm x 5 cm x 1.5 μm (width x length x thickness) adhesive film was formed on the surface of a silicon nitride substrate, except that a mask plate was not used, the rest was prepared according to the method for forming a cured pattern, tested and fitted using an ellipsometer, and the refractive index value corresponding to a wavelength of 550 nm was selected.

[0104] ④Transmittance:

[0105] Except that a mask plate was not used, the rest was prepared according to the method for forming a cured pattern, and the transmittance of the cured film in the visible light range of 380 nm to 800 nm was measured by a UV-visible spectrophotometer (U-3900 Hitachi).

[0106] ⑤Curing rate:

[0107] The high refractive index negative OC photoresist without undercut was inkjet printed on a glass substrate, and was subjected to UV curing for 5.5 s at 20 mW / cm 2 to produce a sample with a size of 3 cm x 7.5 cm x 18 μm (width x length x thickness), and then FT-IR (Nicolet iS50, Thermo-Fisher) was used to measure the absorption peak area of the ink before curing and the organic thin film after curing at 1635 cm -1 (C=C) and 1720 cm -1 (C=O).

[0108] Photocuring rate (%) = |1-(F / S)| x 100;

[0109] wherein F is the absorption peak area of the organic thin film after curing at 1635 cm-1 the ratio of the peak area of the absorption peak near 1720 cm -1 the ratio of the peak area of the absorption peak near 1635 cm -1 the ratio of the peak area of the absorption peak near 1720 cm -1 the ratio of the peak area of the absorption peak near 1635 cm

[0110] 6. Storage stability:

[0111] The obtained high-refractive-index negative OC photoresist in Examples 1-6 and Comparative Examples 1-5 without undercut was stored under a storage condition of -15±5℃ for 120 days, and then warmed to room temperature, and the viscosity change was tested;

[0112] <evaluation criteria>

[0113] ◎ less than or equal to 0.1 cps;

[0114] O greater than 0.1 cps and less than or equal to 0.2 cps;

[0115] X greater than 0.2 cps;

[0116] 6. Double 85 test conditions:

[0117] Temperature 85℃, relative humidity 85%, 240h to observe whether the film peels off or cracks, and if no peeling phenomenon occurs, it is qualified.

[0118] To further verify the effectiveness of the technical solutions provided by the present application, the performance of the photo-cured patterns formed by Examples 1-6 and Comparative Examples 1-4 was tested, and the results are shown in Table 1 below:

[0119] Table 1 Test results of photo-cured patterns formed by Examples 1-6 and Comparative Examples 1-4

[0120]

[0121] As can be seen from Table 1 above, the photo-cured patterns corresponding to Examples 1-6 have high adhesion, light transmittance, refractive index and curing rate; after 240h of double 85 aging, there is no obvious abnormal change, effectively reducing the deformation and cracking of the photoresist film, avoiding the warping and deformation of the product, etc.; the storage stability is excellent, which can ensure that the photoresist pattern has high precision and integrity. At the same time, the high-refractive-index negative OC photoresist prepared by Examples 1-6 has no undercut phenomenon in the corresponding photo-cured pattern square island, as shown in Figure 2 .

[0122] Comparative Examples 1-4 have poor adhesion, and the square island pattern has undercut phenomenon at the bottom, and the undercut width is as high as 1.53μm, as shown in Figure 3 . The overall performance is not good. The reason is that:

[0123] The amount of high refractive nanoparticles in Comparative Example 1 and Comparative Example 2 is not within the range of 10-35 parts by weight as required. In Comparative Example 1, the amount of high refractive nanoparticles is too large, and the stress in the cured film is too large, resulting in poor adhesion, large undercut, and peeling during double 85 aging. In addition, the amount of high refractive nanoparticles is too large, which causes the scattering of visible light by the cured film to be strong, resulting in low light transmittance. In Comparative Example 2, the amount of high refractive nanoparticles is too small, and the monomer is too much, which causes insufficient curing, resulting in poor adhesion of the film and large undercut (the pattern bottom is washed away by the developer due to insufficient curing), and peeling during double 85 aging.

[0124] In Comparative Example 3, the mass ratio of monofunctional (meth)acrylate monomer, difunctional (meth)acrylate monomer, and alicyclic epoxy monomer (2:3:2) is not within the range of (2-3):(3-5):(5-8) as required, i.e., the content of alicyclic epoxy monomer is low, which cannot effectively offset the internal stress generated by the shrinkage of the photoresist during curing, resulting in poor adhesion of the single film. Cracking occurs at 96 h during double 85 aging, and the width of the undercut increases significantly. In addition, the low content of alicyclic epoxy monomer is also not conducive to the dispersibility of high refractive nanoparticles in the photoresist, resulting in decreased storage stability.

[0125] In Comparative Example 4, the alicyclic epoxy monomer is 3,4-epoxycyclohexyl-3',4'-epoxycyclohexyl carboxylate, which does not contain an acrylate functional group and cannot participate in the main crosslinking reaction, but instead has an adverse effect, resulting in peeling at 48 h during double 85 aging.

[0126] The above description is merely a specific implementation of the present application, which enables those skilled in the art to understand or implement the present application. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present application.

[0127] It should be understood that the present application is not limited to the above-described embodiments, and various modifications and changes can be made without departing from the scope thereof. The scope of the present application is limited only by the appended claims.

Claims

1. A high refractive index negative OC photoresist with no undercut, characterized in that, The high-refractive nano-particles are selected from one or two of SnO2, In2O3, TiO2, ZrO2, Al2O3, and ZnO, the median particle size of the high-refractive nano-particles is 5-22 nm, and the refractive index is 1.8-2.

0. Formula (1) Formula (2) Formula (3) Formula (4) Formula (5); The high-refractive nano-particles are selected from one or two of SnO2, In2O3, TiO2, ZrO2, Al2O3, and ZnO, the median particle size of the high-refractive nano-particles is 5-22 nm, and the refractive index is 1.8-2.

0. The photo-curable monomers include monofunctional (meth)acrylate monomers and difunctional (meth)acrylate monomers, and the mass ratio of the monofunctional (meth)acrylate monomers, the difunctional (meth)acrylate monomers, and the alicyclic epoxy monomers is (2-3):(3-5):(5-8).

2. The high refractive negative OC photoresist with no undercut according to claim 1, wherein, The photo-curable monomers include monofunctional (meth)acrylate monomers and difunctional (meth)acrylate monomers, and the mass ratio of the monofunctional (meth)acrylate monomers, the difunctional (meth)acrylate monomers, and the alicyclic epoxy monomers is (2-3):(3-5):(5-8).

3. The high refractive negative OC photoresist with no undercut according to claim 1, wherein, The photo-initiator includes oxime ester photo-initiators.

4. A method for forming a photocured pattern based on the high refractive index negative OC photoresist according to any one of claims 1 to 3, characterized by, The preparation method comprises the following steps: Step 1, coating the high-refractive negative OC photoresist on a substrate; Step 2, heating and drying the film to remove volatile components to obtain a smooth glue film; Step 3, irradiating the obtained glue film with ultraviolet light through a mask plate, contacting the glue film cured by ultraviolet irradiation with a developing solution to dissolve the unexposed area for development, thereby completing the preparation of the required photo-cured pattern.

5. The use of a high refractive index negative OC photoresist based on no undercut for forming a photocured pattern, characterized in that, The photo-cured pattern is prepared by the preparation method of claim 4, and can be applied to a microlens array, a planarization film pattern, a protective film pattern, or an insulating film pattern.

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