Photoresist and its preparation method and application

Abstract

The present invention relates to a photoresist and its preparation method and application. The photoresist comprises: a photosensitizer, an indicator, a resin material and an organic solvent dispersant; the photosensitizer can be decomposed under the action of light to produce an intermediate product or a final product with an enone structure; the indicator is an organic substance containing a nitrosopyrrole structure. The technical problem to be solved is how to provide a photoresist that can change color during the exposure process in the photolithography process so that the exposure effect can be monitored in real time, and the photoresist has good stability under high temperature conditions to avoid excessive quality loss during the baking process.

Description

Technical Field

[0001] The invention belongs to the field of semiconductor technology, and in particular relates to a photoresist and a preparation method and application thereof. Background Art

[0002] In the semiconductor manufacturing process, the photolithography process is the key to the precise manufacturing of integrated circuits. The photolithography process usually includes: coating photoresist, pre-baking, exposure, development, post-baking, and etching. Among them, the exposure process refers to projecting the pattern on the mask plate onto the substrate coated with photoresist through light, causing a chemical reaction in the exposure area, and then removing the photoresist in the exposure area or the unexposed area through development, so that the pattern of the mask plate is effectively transferred to the photoresist, and finally the mask plate pattern is transferred to the substrate using etching technology. Based on the photolithography process, the performance of the photoresist is crucial to the precise manufacturing of integrated circuits. In the prior art, the photoresist needs to be developed after exposure to verify the exposure effect, which limits the real-time monitoring of the exposure effect. If the exposure effect drifts or the development parameters do not match, it may have an adverse effect on the device performance.

[0003] In the prior art, in order to improve the accuracy of photoresist pattern transfer, there are documents that design and prepare photoresists containing photosensitive agents that can change color, so that the prepared photoresist changes color during the exposure process to monitor the exposure effect in real time. However, photosensitive agents that can directly change color generally have poor stability and are easily decomposed in high temperature environments. Therefore, photosensitive agents that can directly change color have a lot of mass loss during baking (including pre-baking and post-baking), that is, the photoresist loses too much mass during the baking process, and excessive mass loss of the photoresist will affect the accuracy of pattern transfer and even cause pattern distortion. Summary of the invention

[0004] The purpose of the present invention is to provide a photoresist and a preparation method and application thereof. The technical problem to be solved is how to provide a photoresist that can change color during the exposure process in the photolithography process so that the exposure effect can be monitored in real time, and has good stability under high temperature conditions to avoid excessive quality loss during the baking process.

[0005] The purpose of the present invention and the technical problem solved are achieved by adopting the following technical solutions. A photoresist proposed in the present invention comprises: a photosensitizer, an indicator, a resin material and an organic solvent dispersant; the photosensitizer can be decomposed under the action of light to produce an intermediate product or a final product having an enone structure; the indicator is an organic substance containing a nitrosopyrrole structure.

[0006] The purpose of the present invention and the solution to its technical problems can be further achieved by adopting the following technical measures.

[0007] Preferably, in the aforementioned photoresist, the photosensitizer is an organic substance containing a diazonaphthoquinone structure.

[0008] Preferably, in the aforementioned photoresist, the indicator comprises a structure as shown in Formula 1:

[0009]

[0010] The R2 is a nitroso group;

[0011] The R1, R3, R4, and R5 are selected from any one of a hydrogen group, an alkyl group, an aromatic group, an alkoxy group, an aromatic oxy group, and a halogen group; and the alkyl group is a straight chain or branched chain alkyl group.

[0012] Preferably, in the aforementioned photoresist, trifluoromethyl and tert-butyl groups are introduced into the nitrosopyrrole structure contained in the indicator.

[0013] Preferably, in the aforementioned photoresist, the indicator is 2-nitroso-1-methylpyrrole, and its structure is shown in Formula 2:

[0014]

[0015] Preferably, in the aforementioned photoresist, the indicator structure is as shown in Formula 3:

[0016]

[0017] Preferably, the aforementioned photoresist, wherein, by mass percentage, comprises: 10-20% photosensitizer; 20-40% resin material; 0.01-5% indicator; 35-55% organic solvent dispersant; the resin material is a mixture of any one or more of phenolic resin, polyimide resin, polyester resin, epoxy resin, and polyvinyl alcohol.

[0018] Preferably, in the aforementioned photoresist, the organic solvent dispersant is a mixture of any one or more of ethyl lactate, 2-heptanone, and propylene glycol monomethyl ether.

[0019] Preferably, the aforementioned photoresist further comprises an additive, wherein the additive is a mixture of any one or more of a dissolution promoter, a surfactant, an adhesion promoter, an ultraviolet absorber, a light stabilizer, and a plasticizer; and the mass percentage of the additive in the photoresist is ≤2%.

[0020] Preferably, in the aforementioned photoresist, the content of heavy metals in the indicator is less than 0.01% and the content of polynitroso organic matter is less than 2% by weight.

[0021] The purpose of the present invention and the technical problem to be solved are also achieved by adopting the following technical solutions. According to a method for preparing a photoresist proposed by the present invention, it comprises the following steps:

[0022] 1) Adding the photosensitizer and the resin material into the organic dispersant, stirring and ultrasonically treating in sequence to form a uniform mixed solution A;

[0023] 2) Add the indicator to the mixed solution A, and perform stirring, ultrasonic treatment, and impurity removal treatment in sequence to form a uniform photoresist;

[0024] The photoresist includes, by mass percentage: 10-20% photosensitizer; 20-40% resin material; 0.01-5% indicator; 35-55% organic solvent dispersant; the photosensitizer can be decomposed under the action of light to produce an intermediate product or final product with an enone structure; the indicator is an organic substance containing a nitrosopyrrole structure.

[0025] The purpose of the present invention and the technical problem to be solved are also achieved by the following technical solutions. According to the above-mentioned technical solution of the present invention, the method for transferring the pattern of the photoresist comprises the following steps:

[0026] 1) coating a photoresist on a substrate to form a photoresist film; the thickness of the photoresist film is 300-1000 nm;

[0027] 2) Bake the substrate with the photoresist film at 85-95°C for 80-100 seconds;

[0028] 3) Use ultraviolet light with a wavelength of 350~380nm to pattern the photoresist on the substrate; the exposure dose is 43.75~200mJ / cm²;

[0029] 4) After the photoresist is exposed, it is baked, developed, and dried with inert gas in sequence to obtain a photoresist structure with a specific pattern.

[0030] The purpose of the present invention and the technical problem solved are also achieved by the following technical solutions: The photoresist described in the above technical solution of the present invention is applied to the fields of micro-electromechanical systems, nanotechnology, biomedical engineering, optical devices or printed circuit board manufacturing.

[0031] By means of the above technical solution, the photoresist and the preparation method and application thereof proposed in the present invention have at least the following advantages:

[0032] 1. The photoresist provided by the present invention uses an organic substance that can decompose under the action of light to produce an intermediate product or a final product with an enone structure as a photosensitizer, and uses an organic substance containing a nitrosopyrrole structure as an indicator. After the prepared photoresist is exposed, the photosensitizer decomposes to produce an intermediate product or a final product with an enone structure, which can react with the indicator to develop a color. The technicians in this field can intuitively indicate the exposure effect through the color change of the photoresist, thereby realizing real-time monitoring of the exposure effect of the photoresist. The photoresist has good stability and little quality loss during the baking process of the photolithography process.

[0033] In addition, the color development reaction between the intermediate product or final product of the enone structure and the indicator is reversible under heating conditions. After the photoresist is exposed, the color development reaction is reversed in the baking stage, and the baking time can be further accurately controlled by the change in the color of the photoresist; and after the color development reaction between the intermediate product or final product of the enone structure and the indicator is reversed, during development, the organic matter containing the enone structure in the exposure area is converted into a carboxylic acid structure in the developer, thereby improving the solubility of the photoresist in the exposure area. It is precisely because of this special reaction between the enone structure substance and the nitrosopyrrole structure substance that the baking effect of the photoresist prepared by the present invention on the exposed photoresist can also be monitored in real time, and the development effect is good, thereby helping to improve the accuracy of the photoresist pattern transfer.

[0034] Further preferably, in the above scheme, an organic substance containing a diazonaphthoquinone structure is used as a photosensitizer, which has good stability in a high temperature environment and the prepared photoresist has little mass loss during the baking process.

[0035] Further preferably, trifluoromethyl and tert-butyl groups are introduced into the nitrosopyrrole structure contained in the indicator, wherein the trifluoromethyl group (-CF3) can increase the stability and hydrophobicity of the nitrosopyrrole structure, and prevent the nitrosopyrrole structure contained in the indicator from reacting with the diazonaphthoquinone structure contained in the photosensitizer. The tert-butyl group (-C(CH3)3) can increase the steric hindrance and thermal stability of the nitrosopyrrole structure, thereby enhancing the stability of the indicator in the alkaline developer, and does not affect the color development reaction of the indicator with the enone structure, and does not interfere with the reaction of the enone structure in the developer, thereby ensuring the development effect.

[0036] The above description is only an overview of the technical solution of the present invention. In order to more clearly understand the technical means of the present invention and implement it according to the contents of the specification, the following is a detailed description of the preferred embodiments of the present invention in conjunction with the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 This is a developing effect diagram of Example 1;

[0038] Figure 2 This is the development effect diagram of Comparative Example 1. DETAILED DESCRIPTION

[0039] In order to further explain the technical means and effects adopted by the present invention to achieve the predetermined invention purpose, the photoresist and its preparation method and application proposed by the present invention are described in detail below in combination with the accompanying drawings and preferred embodiments. Its specific implementation method, structure, characteristics and effects are described in detail as follows.

[0040] The present invention provides a photoresist, which includes: a photosensitizer, an indicator, a resin material and an organic solvent dispersant; the photosensitizer can be decomposed under the action of light to produce an intermediate product or a final product with an enone structure; in some embodiments, the photosensitizer is a mixture of any one or more of an organic matter containing a diazonaphthoquinone structure and an organic matter containing a naphthone structure; the indicator is an organic matter containing a nitrosopyrrole structure, and nitrosopyrrole substances are stable at high temperatures, and nitrosopyrrole substances can react with substances with an enone structure to form a compound with a significant color (such as red, brown or purple).

[0041] The photoresist provided by the aforementioned technical party of the present invention can be detected by the technicians in this field in real time through the color change of the photoresist. And the photosensitizer described in the present invention has good stability in a high temperature environment, so the photoresist has little mass loss during the baking process, which helps to improve the accuracy of the photoresist pattern transfer. Further, the color development reaction between the nitrosopyrrole substance and the substance with the enone structure can reversibly restore the substance with the enone structure under heating conditions, so the baking effect after exposure can be monitored in real time, which helps to accurately control the baking effect and reduce the mass loss of the photoresist during the baking process. Further, the substance with the enone structure generates carboxylic acid after contacting water and dissolves in an alkaline solution, which helps to increase the solubility of the photoresist during the development process, thereby accelerating the development process and helping to reduce the mass loss of the photoresist. Based on the above, the photoresist prepared by the present invention can not only monitor the exposure effect in real time, but also has little mass loss of the photoresist during the photolithography process, which helps to improve the accuracy of the photoresist pattern transfer.

[0042] In some embodiments, the photoresist preferably uses an organic substance containing a diazonaphthoquinone structure as a photosensitizer, and the organic substance containing a diazonaphthoquinone structure may be diazonaphthoquinone (DNQ) or a derivative thereof. After being exposed to ultraviolet light, the organic substance containing a diazonaphthoquinone structure can quickly form an intermediate or final product having an enone structure; and at high temperatures, nitrosopyrrole substances do not react with diazonaphthoquinone organic substances, diazonaphthoquinone organic substances have good stability, and the photoresist has little mass loss during the baking process.

[0043] In some embodiments, in order to improve the color change sensitivity of the nitrosopyrrole structure and the enone structure contained in the indicator, the photoresist of the present invention preferably has a nitrosopyrrole structure as the indicator, in which the nitroso group is directly connected to the carbon atom on the pyrrole ring; further preferably, in some embodiments, the indicator comprises a structure as shown in Formula 1:

[0044]

[0045] Wherein, R2 is a nitroso group;

[0046] In order to reduce the interference of the dispersant solvent on the performance of the photoresist, improve the uniformity and stability of the photoresist, and ensure the resolution of the photoresist, R1, R3, R4, and R5 are preferably any one of hydrogen, alkyl, aromatic, alkoxy, aromatic oxy, and halogen groups. The solubility of the indicator in the solvent can be improved to make it more soluble, and steric hindrance can be provided to enhance the thermal stability, chemical resistance, thermal stability, and reaction selectivity of the indicator.

[0047] In some embodiments, preferably, the alkyl group is a straight chain or branched alkyl group; further preferably, the alkyl group contains 1 to 6 carbon atoms; further preferably, the alkyl group contains 1 to 4 carbon atoms, and selecting a smaller molecular structure substituent helps to improve the resolution of the photoresist; in some embodiments, the alkyl group is methyl (-CH3), ethyl (-CH2CH3), propyl (-CH2CH2CH3), tert-butyl (-C(CH3)3); further preferably, the alkyl group is a fluoroalkyl group, and in some embodiments, the fluoroalkyl group is trifluoromethyl (-CF3) or trifluoroethyl. Fluorinated alkyl groups help to improve the stability of the compound, improve solubility, increase contrast, and increase reactivity.

[0048] In some embodiments, R1, R3, R4, and R5 are substituted with aromatic groups, including phenyl (-C6H5), naphthyl (-C 10 H8).

[0049] In some embodiments, it is further preferred that R1, R3, R4, and R5 are substituted with trifluoromethoxy (-OCF3): the substituent provides additional electronic effects, which helps to improve the solubility of the indicator and the film-forming properties of the photoresist.

[0050] In some embodiments, it is further preferred that R1, R3, R4, and R5 are methoxy groups (-OCH3), and the ether groups contained therein help to improve the solubility and chemical stability of the indicator.

[0051] In some embodiments, it is further preferred that R1, R3, R4, and R5 are halogen groups, such as fluorine (-F) and chlorine (-Cl): the halogen group can provide an electronic effect, which helps to improve the chemical stability and solubility of the indicator.

[0052] In some embodiments, it is further preferred that, in the photoresist, the heavy metal content in the indicator is less than 0.01% by mass percentage; and the polynitroso organic matter content is less than 2%. The present invention strictly limits the heavy metal content in the indicator to avoid problems such as incomplete development of the prepared photoresist or large roughness of the edge of the exposed pattern line, which helps to improve the chemical stability and corrosion resistance of the photoresist; strictly limits the polynitroso organic matter content to avoid undesirable side reactions in the photoresist, which helps to improve the chemical stability and solubility of the photoresist, and the development performance stability is good.

[0053] In some embodiments, it is further preferred that, in order to improve the chemical stability of the photoresist, trifluoromethyl and tert-butyl groups are introduced into the nitrosopyrrole structure of the indicator to avoid the reaction between the nitrosopyrrole structure contained in the indicator and the diazonaphthoquinone structure contained in the photosensitive agent, thereby reducing the influence of the indicator on the exposure color sensitivity, contrast and other properties of the photoresist.

[0054] In some embodiments, in order to further improve the sensitivity of the color development reaction between the indicator and the photosensitizer, it is further preferred that the indicator is 2-nitroso-1-methylpyrrole, and its structural formula is shown in Formula 2:

[0055]

[0056] In some embodiments, in order to further reduce the influence of the indicator on the performance of the photoresist such as exposure color sensitivity and contrast, it is further preferred that after the trifluoromethyl group and tert-butyl group are introduced into the nitrosopyrrole structure contained in the indicator, its structural formula is as shown in Formula 3:

[0057]

[0058] In some embodiments, the organic substance containing a nitrosopyrrole structure (such as N-nitrosopyrrolidine) is usually sold as a chemical reagent or standard in the market, and organic substances having a nitrosopyrrole structure with a trifluoromethyl group and a tert-butyl group are also sold in the market. Based on this, the indicator having a nitrosopyrrole structure and the indicator having a trifluoromethyl group and a tert-butyl group used in the present invention can be directly purchased from the market or prepared by oneself.

[0059] In some embodiments of the present invention, further preferably, the photoresist comprises the following components:

[0060] Calculated by mass percentage, it includes: 10-20% photosensitizer, 20-40% resin material, 0.01-5% indicator, and 35-55% organic solvent dispersant.

[0061] In some embodiments, it is further preferred that the photosensitizer is an organic substance containing a diazonaphthoquinone structure, which is a compound diazonaphthoquinone (DNQ) or a diazonaphthoquinone derivative compound; the molecular formula of DNQ is C 15 H 12 N2O4; the purity of the diazonaphthoquinone or its derivative is ≥95%, further preferably, the purity of the diazonaphthoquinone or its derivative is ≥97%, further preferably, the purity of the diazonaphthoquinone or its derivative is ≥98%, and the prepared photoresist has good sensitivity and good stability.

[0062] In some embodiments, the resin material is a mixture of any one or more of phenolic resin, polyimide resin, polyester resin, epoxy resin, and polyvinyl alcohol. In order to improve the stability and sensitivity of the photoresist, it is further preferred that the resin material is a phenolic resin; it is further preferred that the purity of the phenolic resin is >90%, it is further preferred that the purity of the phenolic resin is >92%, it is further preferred that the purity of the phenolic resin is >95%. In some embodiments, the phenolic resin is preferably a cresol resin; in other embodiments, it is further preferred that the phenolic resin is a hydroquinone formaldehyde resin, the molecular formula of which is (C7H8O·CH2O) n , n is the degree of polymerization, which ranges from 50 to 300.

[0063] In some embodiments, in order to improve the uniformity and stability of the photoresist, the present invention preferably uses the organic solvent dispersant as a mixture of any one or more of ethyl lactate, 2-heptanone, and propylene glycol monomethyl ether; preferably, in some embodiments, the organic solvent dispersant includes 30-80% ethyl lactate (C5H 10 O3), 10~40% 2-heptanone (C7H 14 O), 10~40% propylene glycol monomethyl ether (C4H 10 O2).

[0064] In some embodiments, in order to further improve the stability of the photoresist, the corrosion resistance stability, the photoresist of the present invention preferably adds an additive. In certain embodiments, the additive is any one or more of a dissolution promoter, a surfactant, an adhesion promoter, an ultraviolet light absorber, a light stabilizer, and a plasticizer. The aforementioned additive can be any product suitable for resin film sold on the market.

[0065] In some embodiments, in order to enable the additive to exert its characteristics and not affect the effects of other functional components of the photoresist, the dissolution promoter is a thiourea promoter. The surfactant is preferably a non-ionic surfactant, such as fatty acid glycerides, fatty acid sorbitan (Span), polysorbate (Tween); further, the surfactant is preferably polysorbate (Tween); further preferably, in some embodiments, the surfactant is polyoxyethylene sorbitan monolaurate (Polyoxyethylene Sorbitan Monolaurate, referred to as "PSMO"), also known as Tween 20. The adhesion promoter is preferably a silane coupling agent. The ultraviolet absorber is preferably a substance containing benzophenone or acetophenone; further, the ultraviolet absorber is preferably a substance containing methyl benzophenone or methyl acetophenone; in some embodiments, the ultraviolet absorber is preferably 2-hydroxy-4-methoxyacetophenone. The light stabilizer is preferably a light stabilizer of the ultraviolet absorber type; further preferably, the light stabilizer is o-hydroxybenzophenone or benzotriazole; further preferably, the light stabilizer is benzotriazole; in some embodiments, the light stabilizer is UV-326. The plasticizer is preferably phthalate esters (including phthalate esters, terephthalate esters), polybenzoate esters, and benzoate esters; further, the plasticizer is preferably phthalate esters; further, the plasticizer is preferably phthalate esters; further, in some embodiments, the plasticizer is di(2-ethylhexyl)phthalate.

[0066] In order to avoid the added additives affecting the exposure efficiency and resolution of the photoresist, which may cause unclear or incomplete pattern transfer and fail to achieve the desired preparation of fine structures; or to avoid the additives affecting the fluidity and adhesion of the photoresist, resulting in uneven coating, or peeling / residue during the development process, in some embodiments, the mass percentage of the additives added to the photoresist is preferably ≤2%; further preferably, the mass percentage of the additives is ≤1%; further preferably, in some embodiments, the additive components include: by mass percentage, 0~0.15% solubility promoter, 0~0.1% surfactant, 0~0.6% adhesion promoter, 0~0.15% UV absorber, 0~0.3% light stabilizer, and 0~0.5% plasticizer.

[0067] The present invention also provides a method for preparing a photoresist, which is as follows:

[0068] 1) Preparation of organic dispersant

[0069] In some embodiments, ethyl lactate, 2-heptanone and propylene glycol monomethyl ether are mixed under yellow light irradiation and room temperature; preferably, in the formed mixed solution, the ethyl lactate is 30-80%, the 2-heptanone is 10-40%, and the propylene glycol monomethyl ether is 10-40%, by weight percentage; a magnetic stirrer is used to stir and mix at a stirring speed of 300-600 rpm for 10 minutes, and then ultrasonically dispersed to make it uniform, the ultrasonic frequency is 40-70 Hz, preferably the ultrasonic frequency is 40-60 Hz, and the ultrasonic time is more than 20 minutes, and finally a uniform mixed solvent is obtained.

[0070] 2) Preparation of photoresist

[0071] In some embodiments, the photosensitizer and the resin are sequentially added to the organic dispersant prepared by the aforementioned scheme, stirred for 10 min using a magnetic stirrer at a stirring speed of 300-600 rpm, and then ultrasonically dispersed to make them uniform, with an ultrasonic frequency of 40-70 Hz; preferably, the ultrasonic frequency is 40-60 Hz; the ultrasonic time is more than 20 min, and finally a uniform mixed solution A is obtained.

[0072] The indicator is added to the mixed solution A, and the stirring is continued at a speed of 300-600 rpm until it is evenly dispersed to form a photoresist. The photoresist includes, by mass percentage: 10-20% photosensitizer; 20-40% resin; 0.01-5% indicator; 35-55% organic solvent dispersant; the photosensitizer can be decomposed under the action of light to produce an intermediate product or final product with an enone structure; the indicator is an organic substance containing a nitrosopyrrole structure.

[0073] Preferably, in the aforementioned scheme, in some embodiments, the prepared photoresist comprises, by mass percentage, 10~20% of organic matter containing a diazonaphthoquinone structure; 20~40% of resin material; 0.01~5% of organic matter containing a nitrosopyrrole structure; and 35~55% of an organic solvent dispersant; the resin material is selected from any one or more mixtures of phenolic resin, polyimide resin, polyester resin, epoxy resin, and polyvinyl alcohol.

[0074] In some embodiments, in order to further stabilize and improve the performance of the photoresist, in the process of preparing the photoresist in the above scheme, the organic matter containing the nitrosopyrrole structure is added and uniformly dispersed under stirring, and then the additive is added, and the added additive is as described above. Continue stirring for 10 minutes, the stirring speed is 300~600rpm, and then ultrasonically disperse it evenly, the ultrasonic frequency is 40~70Hz, preferably the ultrasonic frequency is 40~60Hz, the ultrasonic time is more than 20min, preferably the ultrasonic time is 20~30min, and the efficiency is improved under the premise of obtaining a uniform mixed solution.

[0075] 3) Filter impurities from the photoresist using a microporous filter membrane, wherein the pore size of the microporous filter membrane is ≤1 μm; dispense into light-proof containers and refrigerate at 0-4°C.

[0076] The present invention further provides, in some embodiments, a method for transferring a pattern of the photoresist described in the aforementioned solution, which is specifically as follows:

[0077] First, the prepared photoresist is coated on the substrate to form a photoresist film on the substrate; in some embodiments, the substrate can be any one of silicon wafer, glass, metal, ceramic, quartz, sapphire, organic polymer, or composite material substrate. In order to improve the stability and sensitivity of the photoresist film, preferably, the thickness of the photoresist film is 300-1000nm; further preferably, the thickness of the photoresist film is 400-800nm; further preferably, the thickness of the photoresist film is 500-700nm. Then the substrate coated with the photoresist is baked at 85-95°C for 80-100s.

[0078] The photoresist is patterned and exposed using ultraviolet light with a wavelength of 350-380 nm. In order to change the color of the photoresist in the exposed area, in some embodiments, the exposure time is 25-40 s and the light intensity is 1.75-5 mW / cm 2 , that is, the exposure dose is 43.75~200mJ / cm²; further, in order to make the photoresist color change effect in the exposed area reliable and sensitive, the exposure time is 30~35s, and the light intensity is 2.5~4.5mW / cm 2 , that is, the exposure dose is 75~157.5mJ / cm².

[0079] The discoloration effect is observed through a high-power microscope and color measuring instruments. The uniformity of the UV light field, the exposure effect (whether it is overexposed or underexposed) and the size of the exposure defect are analyzed based on the degree of discoloration, consistency of the discoloration area, color uniformity, etc., to determine whether the substrate needs to be de-bonded and reprocessed, and whether the development process needs to be adjusted based on the exposure effect.

[0080] Furthermore, when the exposure effect reaches the expected value, the substrate is quickly baked at 110-130°C for 110-130s, and the exposed area restores the color before exposure. In actual operation, the baking time can be adjusted in time according to the color recovery of the exposed area to accurately control the baking process to avoid the production of by-products in the photoresist due to too long baking time, or the reversible reaction of nitrosopyrrole compounds and enone compounds is not completely completed due to too short baking time. Strictly controlling the baking time can further help reduce the quality loss of the photoresist during the baking process, thereby helping to improve the accuracy of the photoresist pattern transfer.

[0081] The substrate is immersed in a developer for development; the developer is an alkaline developer, and the developer may be a sodium hydroxide (NaOH) or potassium hydroxide (KOH) solution, a sodium carbonate or sodium phosphate solution; preferably, in some embodiments, the developer is a tetramethylammonium hydroxide (TMAH) solution; further preferably, the molar concentration of the tetramethylammonium hydroxide (TMAH) solution is 0.25-0.28 mol / L; soaking for 30-60 seconds.

[0082] After the developed photoresist is taken out, it is dried with an inert gas, wherein the inert gas is a mixture of any one or more of nitrogen, argon, and helium. Preferably, in some embodiments, nitrogen is used for drying to obtain a photoresist structure with a specific pattern.

[0083] The photoresist described in the above scheme of the present invention can be used in the fields of micro-electromechanical systems, nanotechnology, biomedical engineering, optical devices or printed circuit board manufacturing.

[0084] The present invention will be further described below in conjunction with specific embodiments, but this should not be construed as limiting the scope of protection of the present invention. Some non-essential improvements and adjustments made to the present invention by technicians in this field based on the above-mentioned contents of the present invention still fall within the scope of protection of the present invention.

[0085] Unless otherwise specified, the materials, reagents, etc. involved below are all commercially available products well known to those skilled in the art; unless otherwise specified, the methods described are all methods well known in the art. Unless otherwise defined, the technical terms or scientific terms used should have the common meanings understood by ordinary technicians in the field to which the present invention belongs.

[0086] The purity of the photosensitizer and indicator used in this embodiment and comparative example is ≥95%. The structure of 2-nitroso-1-methylpyrrole used in this embodiment and comparative example is shown in the above formula 2, and its purity is ≥95%; the structure of 2-nitroso-3-trifluoromethyl-4-tert-butyl-1-methylpyrrole is shown in the above formula 3.

[0087] Example 1 Preparation and Application of Photoresist

[0088] This embodiment provides a photoresist and a preparation method and application method thereof, using 2-nitroso-1-methylpyrrole as an indicator, hydroquinone formaldehyde resin as a film-forming material, and a photosensitizer of 1,2-diazonaphthoquinone-5-sulfonate. The heavy metal content of the indicator 2-nitroso-1-methylpyrrole impurities is less than 0.0025%; the content of polynitroso byproducts is less than 1%. The details are as follows:

[0089] 1) Preparation of organic solvent dispersants

[0090] Under yellow light irradiation and room temperature, ethyl lactate, 2-heptanone and propylene glycol monomethyl ether were mixed to form a mixed solution in which, by weight percentage, ethyl lactate was 50%, 2-heptanone was 25%, and propylene glycol monomethyl ether was 25%; a magnetic stirrer was used for stirring for 10 minutes at a stirring speed of 500 rpm, and ultrasonic dispersion (ultrasonic frequency of 50 Hz) was performed for 20 minutes to fully mix the mixture until a uniform mixed solvent was formed.

[0091] 2) Preparation of photoresist

[0092] 1,2-diazonaphthoquinone-5-sulfonate (C 10 H6N2O2) and phenolic resin are added to the above mixed solvent, stirred at room temperature for 10 minutes, and then ultrasonically dispersed for 20 minutes (ultrasonic frequency is 50Hz) until completely dissolved. Nitrosopyrrole compounds are added to the above solution and stirred until uniformly dispersed. Further, dissolution promoter (thiourea), surfactant (PSMO), adhesion promoter (silane coupling agent Si-69), ultraviolet absorber (2-hydroxy-4-methoxyacetophenone), light stabilizer (UV-326), plasticizer (di(2-ethylhexyl)phthalate) are added, stirred for 10 minutes, stirring speed is 300rpm, ultrasonic for 20 minutes (ultrasonic frequency is 50Hz), and impurities are filtered using a microporous filter membrane with a pore size of 0.1μm. The filtered photoresist is divided into light-proof containers and stored in a refrigerator at 4℃. The contents of the components in the photoresist are as described in Table 1, specifically as follows: 15% 1,2-diazonaphthoquinone-5-sulfonate, 30% hydroquinone formaldehyde resin, 0.04% nitrosopyrrole compound, 53.7% organic solvent dispersant, 0.15% dissolution promoter (thiourea), 0.06% surfactant (PSMO), 0.2% adhesion promoter (silane coupling agent Si-69), 0.15% UV absorber (2-hydroxy-4-methoxyacetophenone), 0.2% light stabilizer (UV-326), 0.5% plasticizer (di(2-ethylhexyl)phthalate).

[0093] The photoresist was subjected to the following tests:

[0094] Photoresist photosensitivity test:

[0095] The photoresist prepared in this embodiment is uniformly coated on multiple quartz sheets of the same size and absorbance using uniform process parameters (rotation speed, time, and amount of glue dripping) to form a uniform thickness (film thickness The samples coated with the photoresist are numbered sequentially.

[0096] Bake the numbered samples under the same conditions (temperature 60-100°C, time 60-90s) to remove the solvent and cure the photoresist. Expose the samples with ultraviolet light of constant intensity (such as 365nm), and the exposure time increases or decreases with the sample number (for example, film 1 is exposed for 10 seconds, film 2 is exposed for 15 seconds, and film 3 is exposed for 20 seconds). Use a spectrophotometer to measure and record the light absorption changes of each sample, including the absorbance before exposure (A1) and the absorbance after exposure (A2), and calculate the absorbance change ( ). Plot the relationship between absorbance change (ΔA) and exposure time (t). Determine the relationship between ΔA and t through linear regression analysis, and calculate the slope to determine the exposure sensitivity (S). The larger the slope, the faster the photoresist responds to exposure, that is, the better the photosensitivity. Observe the inflection point or minimum detectable change on the ΔA vs. t graph to determine the minimum exposure dose D min (In the actual use of photoresist, the exposure dose should not be less than D min ). (The exposure dose used in the embodiment should be higher than D min , if the exposure dose is 90 mJ / cm², then D min Should not exceed 90 mJ / cm²).

[0097] b. Thermal stability test

[0098] The photoresist prepared in this embodiment is spin-coated on a silicon wafer to form a photoresist film having a thickness of 600 nm. Then, the silicon wafer coated with the photoresist is baked at 90° C. for 90 seconds. A thermogravimetric analysis (TGA) instrument is used to test the mass loss of the photoresist before and after baking, and the thermal stability of the photoresist is analyzed. If the mass loss before and after baking is less than 1%, the thermal stability is considered to be good, otherwise, the thermal stability is considered to be poor.

[0099] 3) Photoresist application

[0100] The photoresist prepared in this embodiment was spin-coated on a silicon wafer to form a photoresist film having a thickness of 600 nm. Then, the silicon wafer coated with the photoresist was baked at 90° C. for 90 seconds. Further, the photoresist was pattern-exposed using 365 nm wavelength ultraviolet light for 30 seconds at a light intensity of 3 mW / cm 2 , that is, the exposure dose is 90mJ / cm², and the photoresist in the exposed area changes color. Use the image acquisition system to capture images of multiple areas on the silicon wafer, and use the color analysis tool to collect the color information of the image area, and perform the following tests on the photoresist:

[0101] a. Color change uniformity test

[0102] The image and color information of the exposure areas at different positions are collected, and the color difference values ​​(ΔE) of these areas are calculated using the color difference formula such as CIEDE2000 to evaluate the uniformity of color change. ΔE<1 means that the color difference is almost imperceptible to the naked eye and the uniformity is good; ΔE<3 means acceptable color difference and good uniformity; ΔE≥3 means uneven color change.

[0103] b. Exposure pattern clarity test

[0104] The image was analyzed by image processing software, the average brightness value L1 of the exposed area and the average brightness value L2 of the unexposed area were extracted, and the contrast (C) was calculated: When C>3, the exposure pattern is relatively clear; when C≤3, the exposure pattern has poor clarity.

[0105] The silicon wafer was baked at 120°C for 120 seconds, and the exposed area restored its color before exposure. The silicon wafer was immersed in a 0.26 mol / L tetramethylammonium hydroxide (TMAH) solution for 50 seconds, taken out, and dried with nitrogen to obtain a photoresist structure with a specific pattern. A scanning electron microscope (SEM) was used to measure the structure size, structure consistency, and line edge roughness.

[0106] The test results of various indicators in this embodiment are shown in Table 2.

[0107] Pattern transfer Figure 1 shown.

[0108] Example 2 Preparation and Application of Photoresist

[0109] This embodiment provides a photoresist and a preparation method and application method thereof. The photoresist is prepared using 1,2-diazonaphthoquinone-5-sulfonate as a photosensitizer, hydroquinone formaldehyde resin is used as a film-forming material, and 2-nitroso-1-methylpyrrole is used as an indicator. The difference is that the content of each component in the photoresist is as shown in Table 1; and during the preparation process, the process parameters are adjusted as follows:

[0110] 1) Preparation of organic solvent dispersants

[0111] Under yellow light irradiation and room temperature, ethyl lactate, 2-heptanone and propylene glycol monomethyl ether were mixed to form a mixed solution in which, by weight percentage, ethyl lactate accounted for 80%, 2-heptanone accounted for 10%, and propylene glycol monomethyl ether accounted for 10%. A magnetic stirrer was used for stirring for 15 minutes at a stirring speed of 600 rpm, and ultrasonic dispersion (ultrasonic frequency 60 Hz) was performed for 20 minutes to fully mix the mixture until a uniform mixed solvent was formed.

[0112] 2) Preparation of photoresist

[0113] Add the photosensitive agent and resin material to the dispersant, stir at room temperature for 10 minutes, and then perform ultrasonic dispersion for 20 minutes (ultrasonic frequency is 60Hz) until completely dissolved. Add the indicator to the above solution and continue stirring until uniformly dispersed. Further, add a dissolution promoter (thiourea), a surfactant (PSMO), an adhesion promoter (silane coupling agent Si-69), an ultraviolet absorber (2-hydroxy-4-methoxyacetophenone), a light stabilizer (UV-326), and a plasticizer (di(2-ethylhexyl)phthalate), stir for 10 minutes at a stirring speed of 300rpm, and ultrasonicate for 20 minutes (ultrasonic frequency is 60Hz). Use a microporous filter membrane with a pore size of 0.1μm to filter impurities. The filtered photoresist is divided into light-proof containers and stored in a refrigerator at 4°C.

[0114] 3) Photoresist application

[0115] The photoresist prepared in this embodiment was spin-coated on a silicon wafer to form a photoresist film having a thickness of 600 nm. Then, the silicon wafer coated with the photoresist was baked at 90° C. for 90 seconds. Further, the photoresist was pattern-exposed using 365 nm wavelength ultraviolet light for 30 seconds at a light intensity of 3 mW / cm 2 , that is, the exposure dose is 90mJ / cm², and the photoresist in the exposed area changes color. The silicon wafer is baked at 120℃ for 120s, and the exposed area restores the color before exposure. The silicon wafer is immersed in 0.26mol / L tetramethylammonium hydroxide (TMAH) solution, taken out after soaking for 50s, and dried with nitrogen to obtain a photoresist structure with a specific pattern.

[0116] The detection indexes and methods are the same as those in Example 1, and the results are shown in Table 2.

[0117] Example 3 Preparation and Application of Photoresist

[0118] The present embodiment provides a photoresist and a preparation method and an application method thereof. The photoresist is prepared using 1,2-diazonaphthoquinone-5-sulfonate as a photosensitizer, hydroquinone formaldehyde resin is used as a film-forming material, and 2-nitroso-1-methylpyrrole is used as an indicator. The difference lies in that: the components of the photoresist are as shown in Table 1; in the organic solvent dispersant, the ethyl lactate is 30%, the 2-heptanone is 30%, and the propylene glycol monomethyl ether is 40%, calculated by mass percentage.

[0119] The detection indexes and methods are the same as those in Example 1, and the results are shown in Table 2.

[0120] Example 4 Preparation and Application of Photoresist

[0121] This embodiment provides a photoresist and a preparation method and application method thereof. The photoresist is prepared using 1,2-diazonaphthoquinone-5-sulfonate as a photosensitizer, hydroquinone formaldehyde resin as a film-forming material, and 2-nitroso-1-methylpyrrole as an indicator. The difference is that:

[0122] The content of heavy metals in the indicator 2-nitroso-1-methylpyrrole impurities is not higher than 0.02%; the content of polynitroso byproducts is not higher than 2.5%.

[0123] The detection indexes and methods are the same as those in Example 1, and the results are shown in Table 2.

[0124] Example 5 Preparation and Application of Photoresist

[0125] The present embodiment provides a photoresist and a preparation method and an application method thereof. The present embodiment uses hydroquinone formaldehyde resin as a film-forming material, and the photosensitizer is 1,2-diazonaphthoquinone-5-sulfonate. The main difference between the present embodiment and the embodiment 1 is that the indicator is 2-nitroso-3-trifluoromethyl-4-tert-butyl-1-methylpyrrole, and the content of each component of the photoresist is as shown in Table 1.

[0126] The detection indexes and methods are the same as those in Example 1, and the results are shown in Table 2.

[0127] Example 6 Preparation and Application of Photoresist

[0128] This embodiment provides a photoresist and a preparation method and application method thereof. The preparation process and method are basically the same as those in Example 3. 2-nitroso-1-methylpyrrole is used as an indicator and the photosensitizer is 1,2-diazonaphthoquinone-5-sulfonate to prepare the photoresist. The difference is that cresol resin is used as a film-forming material. The components of the photoresist are shown in Table 1.

[0129] The detection indexes and methods are the same as those in Example 1, and the results are shown in Table 2.

[0130] Example 7 Preparation and Application of Photoresist

[0131] The present embodiment provides a photoresist and a preparation method and an application method thereof. The preparation process and method are basically the same as those of Example 3. 2-nitroso-1-methylpyrrole is used as an indicator, and the photosensitizer is 1,2-diazonaphthoquinone-5-sulfonate to prepare the photoresist. Hydroquinone formaldehyde resin is used as a film-forming material. The difference is that no additives are added to the photoresist, and the content of each component is as described in Table 1, that is, it only contains 1,2-diazonaphthoquinone-5-sulfonate, hydroquinone formaldehyde resin, 2-nitroso-3-trifluoromethyl-4-tert-butyl-1-methylpyrrole, and an organic solvent dispersant. The specific content is shown in Table 1.

[0132] The detection indexes and methods are the same as those in Example 1, and the results are shown in Table 2.

[0133] Example 8 Preparation and Application of Photoresist

[0134] This embodiment provides a photoresist and a preparation method and application method thereof. The preparation process and method are basically the same as those in Example 3. 2-nitroso-1-methylpyrrole is used as an indicator and the photosensitizer is 1,2-diazonaphthoquinone-5-sulfonate to prepare the photoresist. The difference is that polyimide resin is used as a film-forming material. The components of the photoresist are shown in Table 1.

[0135] The detection indexes and methods are the same as those in Example 1, and the results are shown in Table 2.

[0136] Example 9 Preparation and Application of Photoresist with Color Changing Properties

[0137] This embodiment provides a photoresist and a preparation method and application method thereof, wherein the nitrosopyrrole compound prepared in Example 1, namely 2-nitroso-1-methylpyrrole, is used as an indicator and hydroquinone formaldehyde resin is used as a film-forming material. The difference is that the photosensitizer is 1-hydroxy-1-(4-nitrophenyl)-2-naphthone, C 16 H 14 NO3.

[0138] The detection indexes and methods are the same as those in Example 1, and the results are shown in Table 2.

[0139] Comparative Example 1

[0140] The difference between this comparative example and Example 1 is that the resin used in the photoresist of the present invention is polyacrylic acid resin.

[0141] The detection index and method are the same as those in Example 1. The results are shown in Table 2. The pattern transfer is shown in Figure 2 .

[0142]

[0143]

[0144] Combining Table 2 and Figure 1It can be seen that the photoresist provided by the embodiment of the present invention has good exposure and development effects, and the transfer accuracy of the photoresist pattern is high. This is mainly because the photoresist prepared by the present invention can observe the discoloration effect and make appropriate adjustments through a high-power microscope and a color measuring instrument during the exposure process, and the exposure accuracy is good; the prepared photoresist is heated after exposure, and the color development reaction is reversible, which further helps to grasp the accuracy of the baking time after exposure; and the photoresist has good solubility, fast development and good effect; the photoresist has little quality loss during the baking process. Further, during the exposure process, those skilled in the art can analyze the uniformity of the ultraviolet light field, the exposure effect (whether it is overexposed or underexposed) and the size of the exposure defect according to the degree of discoloration, consistency of the discoloration area, color uniformity, etc., and judge whether the substrate needs to be de-bonded and reprocessed, which is conducive to saving unnecessary time and waste of resources.

[0145] Further preferably, the technical scheme disclosed in the present invention is adopted, with the photosensitizer being an organic substance with a diazonaphthoquinone structure and the organic substance with a nitrosopyrrole structure being an indicator, and the prepared photoresist has a low exposure dose causing color change, good photosensitivity, and good photoresist stability.

[0146] Comparing Example 4 with Example 1, it can be seen that the heavy metal content in the indicator 2-nitroso-1-methylpyrrole impurities is high, and when the content of polynitroso by-products is too high, the performance of the prepared photoresist is poor. This is because the presence of heavy metals and polynitroso by-products may interfere with the color development reaction, affect the photosensitivity and development quality of the photoresist, and cause the chemical stability and solubility of the photoresist to decrease.

[0147] Comparing Example 5 with other examples, the photoresist prepared by using an organic substance having a nitrosopyrrole structure modified with trifluoromethyl and tert-butyl as an indicator has good thermal stability and color change uniformity. This is because the trifluoromethyl group (-CF3) can increase the stability and hydrophobicity of the nitrosopyrrole structure, avoiding adverse reactions between the indicator and the photosensitizer, while the tert-butyl group (-C(CH3)3) can increase the steric hindrance and thermal stability of the nitrosopyrrole structure, thereby enhancing the stability of the indicator in the alkaline developer, and does not affect the color change reaction between the indicator and the enone intermediate, does not interfere with the reaction of the enone intermediate in the developer, and ensures the development effect. Therefore, these modifications help to improve the performance of the photoresist during exposure and development, thereby obtaining a more uniform and precise pattern transfer.

[0148] Comparative Example 1, Example 6, and Example 8 show that compared with polyimide resin as a film-forming material, the photoresist prepared with phenolic resin as a film-forming material has good photosensitivity. Further preferably, the photoresist prepared with cresol resin in phenolic resin as a film-forming material has better photosensitivity. This is because cresol resin has good solubility and sensitivity to light, which can improve the photosensitivity of the photoresist, so that the photoresist can respond to light signals faster during exposure, and improve the efficiency and accuracy of the photolithography process. The molecular structure of cresol resin contains methyl groups, which helps to improve the chemical stability and corrosion resistance of the photoresist, thereby forming a clearer and more accurate pattern during the photolithography process.

[0149] By comparing Example 9 with other examples, it can be seen that the photoresist prepared by using an organic substance with a diazonaphthoquinone structure as a photosensitizer is superior to 1-hydroxy-1-(4-nitrophenyl)-2-naphthone in terms of photosensitivity and contrast. The reason is that the organic substance containing a diazonaphthoquinone structure can be rapidly decomposed under light to produce a compound with an enone structure, and this decomposition product can rapidly react with an indicator with a nitrosopyrrole structure to achieve real-time monitoring of the exposure effect. This rapid photochemical reaction makes the photoresist more sensitive to changes in exposure conditions, and improves the accuracy and resolution of the photolithography process. At the same time, the organic substance with a diazonaphthoquinone structure has good thermal stability and chemical stability, which helps to maintain the performance of the photoresist during the photolithography process, reduce the occurrence of side reactions, and thus improve the overall performance of the photoresist.

[0150] Combination Figure 2 Analysis of Comparative Example 1 shows that the developing effect is not good. The reason is that the photoresist prepared with polyacrylic acid resin as the film-forming agent has weak resistance to alkaline developer and may be excessively dissolved during the developing process, resulting in a significant decrease in contrast and even distortion of the exposed pattern.

[0151] The technical features in the claims and / or the specification of the present invention may be combined, and the combination is not limited to the combination obtained by reference in the claims. The technical solution obtained by combining the technical features in the claims and / or the specification is also within the protection scope of the present invention.

[0152] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any form. Any simple modification, equivalent change and modification made to the above embodiment according to the technical essence of the present invention still falls within the scope of the technical solution of the present invention.

Claims

1. A photoresist, characterized in that: It includes: A photosensitizer, an indicator, a resin material and an organic solvent dispersant; the photosensitizer can be decomposed under the action of light to produce an intermediate product or a final product having an enone structure; the indicator is an organic substance containing a nitrosopyrrole structure; The indicator comprises a structure as shown in Formula 1: ； The R2 is a nitroso group; The R1, R3, R4, and R5 are selected from any one of a hydrogen group, an alkyl group, an aromatic group, an alkoxy group, an aromatic oxy group, and a halogen group; the alkyl group is a straight chain or a branched chain alkyl group; The resin material is phenolic resin and / or polyimide resin.

2. The photoresist according to claim 1, characterized in that The photosensitizer is an organic substance containing a diazonaphthoquinone structure.

3. The photoresist according to claim 1, characterized in that The indicator is 2-nitroso-1-methylpyrrole, and its structure is shown in Formula 2: 。 4. The photoresist according to claim 1, characterized in that Calculated by mass percentage, it includes: 10-20% photosensitizer; 20-40% resin material; 0.01-5% indicator; 35-55% organic solvent dispersant.

5. The photoresist according to claim 1 or 4, characterized in that: The organic solvent dispersant is a mixture of any one or more of ethyl lactate, 2-heptanone, and propylene glycol monomethyl ether.

6. The photoresist according to claim 1, characterized in that The photoresist further comprises additives, wherein the additives are any one or more mixtures of a dissolution promoter, a surfactant, an adhesion promoter, an ultraviolet absorber, a light stabilizer, and a plasticizer; and the mass percentage of the additives in the photoresist is ≤2%.

7. The photoresist according to claim 1, characterized in that Calculated by mass percentage, the heavy metal content in the indicator is less than 0.01%; the polynitroso organic matter content is less than 2%.

8. A method for preparing a photoresist, characterized in that: It includes the following steps: 1) Adding the photosensitizer and the resin material into the organic solvent dispersant, stirring and ultrasonically treating in sequence to form a uniform mixed solution A; 2) Add the indicator to the mixed solution A, and perform stirring, ultrasonic treatment, and impurity removal treatment in sequence to form a uniform photoresist; The photoresist comprises, by mass percentage: 10-20% photosensitizer; 20-40% resin material; 0.01-5% indicator; 35-55% organic solvent dispersant; the photosensitizer can be decomposed under the action of light to produce an intermediate product or a final product having an enone structure; the indicator is an organic substance containing a nitrosopyrrole structure; The indicator comprises a structure as shown in Formula 1: ； The R2 is a nitroso group; The R1, R3, R4, and R5 are selected from any one of a hydrogen group, an alkyl group, an aromatic group, an alkoxy group, an aromatic oxy group, and a halogen group; the alkyl group is a straight chain or a branched chain alkyl group; The resin material is phenolic resin and / or polyimide resin.

9. A photoresist pattern transfer method, characterized in that: The method uses the photoresist according to any one of claims 1 to 7, and comprises the following steps: 1) coating a photoresist on a substrate to form a photoresist film; the thickness of the photoresist film is 300-1000 nm; 2) Bake the substrate with the photoresist film at 85-95°C for 80-100 seconds; 3) Use ultraviolet light with a wavelength of 350~380nm to pattern the photoresist on the substrate; the exposure dose is 43.75~200mJ / cm²; 4) After the photoresist is exposed, it is baked, developed, and dried with inert gas in sequence to obtain a photoresist structure with a specific pattern.

10. Use of the photoresist according to any one of claims 1 to 7 in the fields of micro-electromechanical systems, nanotechnology, biomedical engineering, optical devices or printed circuit board manufacturing.

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