A preparation method of a MIL-101-acrylate monomer composite-based negative photoresist

Abstract

The application provides a preparation method of a MIL-101-acrylate monomer compound for a negative photoresist, mainly comprising the following steps: the compound is prepared by the following method: under a nitrogen environment, MIL-101, polymethylphenylsiloxane, an acrylate monomer (such as hydroxyethyl acrylate) and dipropylene glycol methyl ether acetate are blended and then heated, and the MIL-101-acrylate monomer compound is successfully prepared. The MIL-101-acrylate monomer compound prepared by the application is used as a modified component of a negative photoresist, and the resolution and overall photoetching performance of a traditional photoresist resin are improved. The method provides a new idea for the design of a resin modified component of a negative photoresist.

Description

Technical Field

[0001] The present invention relates to the fields of semiconductor chips and chemical industry, and in particular to a MIL-101-acrylate monomer complex, a negative photoresist and a preparation method thereof. Background Art

[0002] Photoresists can be divided into two types: positive and negative, depending on how the exposed areas are treated during the development process. Positive photoresists transfer the pattern to the photoresist layer under ultraviolet light. The exposed areas decompose and become soluble in the developer, while the unexposed areas remain insoluble and therefore retained. The advantages of this type of photoresist are higher resolution and resistance to swelling. In contrast, negative photoresists undergo cross-linking after ultraviolet light exposure, becoming insoluble in the developer in the exposed areas, while the unexposed areas can be dissolved. This type of photoresist has good heat resistance and is suitable for the manufacture of high-power and specialty devices. It is often used in the final packaging stage of chips to provide insulation and protection. However, negative photoresists are difficult to remove, and due to the uneven molecular weight distribution of the resin, they have poor uniformity and stability, resulting in lower resolution.

[0003] To improve the performance of negative photoresists, some technologies have employed single-molecule solid epoxy resins or small-molecule resins to enhance the sensitivity and development speed of photocuring. However, these resins are expensive to process and difficult to formulate into high-viscosity liquids, which can lead to photoresist peeling and loss, impacting the overall quality of the chip. Previous research has required resin modification for photoresist preparation, but the polymerization reaction during the modification process is difficult to control, potentially producing byproducts and polymer chain entanglement. Furthermore, the modified epoxy resins readily crosslink under light, causing photoresist inactivation and increasing storage difficulties. Under photosensitive reaction conditions, crosslinking uniformity is also difficult to ensure, potentially resulting in reduced edge cleanliness and increased defective rates. Finally, because negative photoresists require multiple exposures, they place high demands on adhesion, which modified small-molecule resins may not meet. Therefore, designing a photoresist with clean edges, high resolution, and certain self-healing properties is crucial. Summary of the Invention

[0004] This invention aims to address the shortcomings of existing negative photoresists and introduces a negative photoresist product that features clean edges, high resolution, self-healing capabilities, and topological identification marking, improving the success rate of photolithography while avoiding the process challenges associated with resin modification.

[0005] The present invention provides a method for preparing a negative photoresist based on a MIL-101-acrylate monomer complex, which is characterized by comprising the following steps:

[0006] Preparation of MIL-101-acrylate monomer complex:

[0007] S1. Dissolve chromium nitrate nonahydrate (Cr(NO₃)₃·9H₂O) and terephthalic acid (C₃H₂O) in deionized water at a 1:1 molar ratio. Add hydrofluoric acid and stir thoroughly to form a mixed solution. Next, transfer the mixed solution to a polytetrafluoroethylene-lined stainless steel reactor and conduct a hydrothermal reaction at 220°C for 9 hours. After the reaction, allow the reactor to cool naturally to room temperature. After centrifugation, washing, and drying, MIL-101 is obtained.

[0008] S2. MIL-101, polymethylphenylsiloxane, and acrylate monomers are mixed in a ratio of 1:0.1:10, and one or more solvents are added under a nitrogen atmosphere, and stirred at a speed of 500-1000 rpm. The solvents are dipropylene glycol methyl ether acetate, propylene glycol phenyl ether acetate, and ethylene glycol ethyl ether acetate;

[0009] S3, then reacting in a sealed manner at a high temperature of 120°C for 4 hours, filtering and vacuum drying to obtain a MIL-101-acrylate monomer complex;

[0010] Preparation of MIL-101-acrylate monomer complex modified photoresist:

[0011] S4. Under nitrogen protection, the MIL-101-acrylate monomer complex, epoxy resin, dye, photoinitiator, leveling agent and solvent were mixed in a certain proportion and stirred at 500 rpm for 1 hour;

[0012] S5. Further add the mixed product into the remaining solvent dipropylene glycol methyl ether acetate, and stir and mix at a speed of 600 rpm for 30 minutes to obtain the final photoresist.

[0013] As a preferred solution, the components of the negative photoresist (by weight ratio) can be adjusted as follows:

[0014] 1. 10-30 parts of MIL-101-acrylate monomer complex;

[0015] 2. Epoxy resin (Su-8 epoxy resin) 20-40 parts;

[0016] 3. Dye (phthalocyanine) 1-5 parts

[0017] 4. Photoinitiator (benzoin dimethyl ether) 1-2 parts

[0018] 5. Leveling agent (polymethylphenylsiloxane) 0.1-0.5 parts

[0019] 6. Solvent (dipropylene glycol methyl ether acetic acid) 20-50 parts.

[0020] Compared with the prior art, the advantages of the present invention are:

[0021] 1. The MIL-101 in the present invention is not a traditional MOF metal framework compound. It has extremely high flexibility and a "breathing" effect between two different configurations of large pores (lp) and narrow pores (np) during the adsorption process. The volume change can be as high as 40%, and the prepared composite also has a large volume tolerance.

[0022] 2. By combining epoxy resin with components such as a MIL-101-acrylate monomer complex, this invention introduces a topologically structured metal framework compound. This not only helps resolve the entanglement problem of the resin molecular chains but also brings potential for product identification, authentication, and barcode anchoring. Furthermore, by coupling biotin or peptides, the photoresist can also possess biorecognition properties, adding a new dimension to chip functionality.

[0023] Beneficial effects:

[0024] The present invention simplifies some of the preparation processes, eliminating the need for strict control of the epoxy resin's molecular weight and uniformity, and eliminating the need for further polymerization modification of the epoxy resin. This improvement avoids a series of problems that may arise from the modification process, making the production process more efficient and reliable.

[0025] Through these innovative preparation methods, the present invention also improves the storage stability of the photoresist, which is crucial for ensuring the quality of the product during storage and transportation.

[0026] In addition, the present invention also expands the application scope of epoxy resin in negative photoresist, improves the resolution and overall photolithography performance of traditional photoresist resin, and significantly improves the accuracy and performance of the final product. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 This is a flow chart for preparing the MIL-101-acrylate monomer complex and the negative photoresist in the present invention. DETAILED DESCRIPTION

[0028] The following describes the embodiments of the present invention through specific examples. Those skilled in the art will readily understand the other advantages and benefits of the present invention from the disclosure herein. The present invention may also be implemented or applied through various other specific embodiments, and the details in this specification may be modified or altered based on different viewpoints and applications without departing from the spirit of the present invention.

[0029] Example:

[0030] Preparation of MIL-101-acrylate monomer complex:

[0031] Chromium nitrate nonahydrate (Cr(NO₃)₃·9H₂O) and terephthalic acid (C₃H₂O₄) were dissolved in deionized water at a molar ratio of 1:1. Hydrofluoric acid was added and stirred to form a mixed solution. The mixed solution was then transferred to a stainless steel reactor lined with polytetrafluoroethylene and subjected to a hydrothermal reaction at 220°C for 9 hours. After the reaction, the reactor was allowed to cool to room temperature. MIL-101 was obtained through post-processing steps including centrifugation, washing, and drying. MIL-101, polymethylphenylsiloxane, and an acrylate monomer were mixed at a ratio of 1:0.1:10 and stirred at 500-1000 rpm under a nitrogen atmosphere. The solvents were dipropylene glycol methyl ether acetate, propylene glycol phenyl acetate, and ethylene glycol ethyl acetate. The reaction was then carried out in a sealed container at 120°C for 4 hours. The product was filtered and dried under vacuum to obtain the product.

[0032] Preparation of MIL-101-acrylate monomer complex modified photoresist: MIL-101-acrylate monomer complex, epoxy resin, dye, photoinitiator, leveling agent, and solvent are stirred and mixed in a certain proportion. The further mixed product is then added to the remaining solvent to obtain the final photoresist.

[0033] Example 1

[0034] The formula and preparation method of Example 1 are as follows:

[0035] Formula: 20 parts of Su-8 epoxy resin, 10 parts of hydroxyethyl acrylate, 1 part of MIL-101, 1 part of phthalocyanine, 1 part of benzoin dimethyl ether, 0.1 part of polymethylphenylsiloxane, and 20 parts of dipropylene glycol methyl ether acetate.

[0036] Preparation method:

[0037] 1. Mixing: Under nitrogen, add 1 part MIL-101, 0.1 part polymethylphenylsiloxane, 10 parts hydroxyethyl acrylate, and 10 parts dipropylene glycol methyl ether acetate to a reaction vessel all at once. Heat to 120°C and stir at 500 rpm for 4 hours. Filter and vacuum dry to obtain the MIL-101-acrylate monomer complex.

[0038] 2. Add the remaining components: Under nitrogen, add 20 parts of Su-8 epoxy resin, 1 part of phthalocyanine, and 1 part of benzoin dimethyl ether to the mixture in step 1. Continue stirring at 500 rpm for 1 hour, then filter to remove undispersed particles and dry under vacuum.

[0039] 3. Final mixing: Add the complex obtained in step 2 to the remaining dipropylene glycol methyl ether acetate, and stir and mix at a speed of 600 rpm for 30 minutes to obtain the final photoresist.

[0040] 4. Photolithography: Use a 2 μm scraper to evenly coat the photoresist on the pretreated silicon wafer, bake it for 10 minutes, expose it to ultraviolet light, and then develop it with 0.2% sodium carbonate developer. Finally, wash it with pure water and remove the glue with sodium hydroxide to obtain the photolithography pattern.

[0041] Example 2

[0042] The formulation and preparation method of Example 2 are similar to those of Example 1, but differ in the component proportions and the solvents used: 40 parts of Su-8 epoxy resin, 30 parts of hydroxyethyl acrylate, 5 parts of MIL-101, 2 parts of phthalocyanine, 2 parts of benzoin dimethyl ether, 0.5 parts of polymethylphenylsiloxane, and 50 parts of dipropylene glycol methyl ether acetate.

[0043] Example 3

[0044] The formulation and preparation method of Example 3 are similar to those of Example 1, but differ in the component proportions and the solvents used: 30 parts of Su-8 epoxy resin, 20 parts of hydroxyethyl acrylate, 3 parts of MIL-101, 1.5 parts of phthalocyanine, 1.5 parts of benzoin dimethyl ether, 0.3 parts of polymethylphenylsiloxane, and 35 parts of dipropylene glycol methyl ether acetate.

[0045] Comparative Example 1

[0046] The formulation and preparation method of Comparative Example 1 are similar to those of Example 1, except that the formulation does not contain MIL-101.

[0047] Comparative Example 2

[0048] The formulation and preparation method of Comparative Example 1 are similar to those of Example 1, except that polymethyl methacrylate is used instead of epoxy resin.

[0049] Comparative Example 3

[0050] The formulation and preparation method of Comparative Example 1 are similar to those of Example 1, except that the formulation does not contain polymethylphenylsiloxane.

[0051] Control Example

[0052] The control example used a negative photoresist product containing SU-8 resin sold on the market.

[0053] The test method is as follows: First, the resolution is tested according to the GB / T29556-2013 standard, and the smoothness and verticality of the photoresist edge are observed using an optical microscope. The results show that Examples 1-3 have better edge verticality than the control, representing better resolution. Then, the developed product is tested using the projection chrome plate method to detect pinhole density to evaluate product quality. The test is carried out after 2 minutes and 1 hour to verify the self-repair function of the photoresist.

[0054] Table 1: Sensitivity and pinhole density ratio of different photoresists (60 min: 2 min)

[0055] characteristic Sensitivity <![CDATA[针孔密度(p / cm 2 )60min:2min]]> Example 1 high <1 Example 2 high <1 Example 3 Higher <1 Comparative Example 1 generally >1 Comparative Example 2 Higher >1 Comparative Example 3 generally >1 Control Example generally >1

[0056] In addition, accelerated aging tests were conducted to evaluate the stability of the photoresist products in the above examples. 10 grams of each example product was weighed and diluted with the solvent in the respective formulation to prepare 100 ml of diluted solution. These diluted samples were placed in identical light-shielded bottles and stored in a 35°C light-incubator for 3 to 7 days. The clarity and color changes of each sample dilution were compared with those of the refrigerated sample dilutions, and the results were recorded.

[0057] The test results showed that the samples of Examples 1 to 3 and Comparative Example 3 did not change in appearance. Comparative Examples 1 and 4 began to show yellowing and decreased clarity after 3 days of storage. Comparative Example 2 and the control example showed a significant decrease in clarity after 7 days. These test results indicate that the photoresist compositions of Examples 1 to 3 have high resolution and sensitivity. These products have neatly arranged topological structures, orderly molecules, clear edges, and high verticality, making them suitable for thick-film processes. Furthermore, the topological structures can be used to add labeling substances to expand biometric recognition functions.

[0058] In stability testing, negative photoresists containing a MIL-101-acrylate monomer complex exhibited improved stability and shelf life. Photoresists containing other MIL products, however, exhibited poor shelf life, likely due to the unique variable structure of MIL-101. Furthermore, Comparative Example 3 (a photoresist composition that was simply mixed without forming a complex) exhibited a shorter shelf life and poorer stability. This may be due to the metal oxide's increased absorption and scattering of light, leading to increased photosensitivity during storage. In contrast, Examples 1 to 3 of the present invention were able to more stably accommodate the photoinitiator under normal storage conditions. Pinhole density testing also revealed that the products of the present invention possess certain self-healing properties, which facilitate subsequent photolithography processes and positively impact the quality and wear resistance of the photoresist. Therefore, they possess broad research value and application prospects.

[0059] Unless otherwise specified, all percentages in the present invention represent weight percentages. Unless otherwise specified, the solutions in the present invention refer to aqueous solutions. The numerical ranges in this application are approximate values. The specific examples are only for enumeration. All possible combinations between the lowest value and the highest value listed are considered to be included in this application. With respect to the use of chemical compounds, unless expressly stated otherwise, the singular form includes all isomeric forms, and nouns modified by adjectives such as "a" or "the" also include plural forms.

[0060] The above embodiments are merely illustrative of the principles and effects of the present invention and are not intended to limit the present invention. Anyone skilled in the art may modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by one of ordinary skill in the art without departing from the spirit and technical principles disclosed herein are intended to be covered by the claims of the present invention.

Claims

1. A method for preparing a negative photoresist based on a MIL-101-acrylate monomer complex, characterized in that The following steps are involved: S1. Chromium nitrate nonahydrate (Cr(NO3)3·9H2O) and terephthalic acid (C8H6O4) were dissolved in deionized water at a molar ratio of 1:1, and hydrofluoric acid was added and stirred to form a mixed solution. The mixed solution was then transferred to a stainless steel reactor lined with polytetrafluoroethylene and subjected to a hydrothermal reaction at 220°C for 9 hours. After the reaction was completed, the reactor was allowed to cool naturally to room temperature. After centrifugation, washing, and drying, MIL-101 was finally obtained. S2. MIL-101, polymethylphenylsiloxane, and acrylate monomer are mixed in a ratio of 1:0.1:10, and one or more solvents are added under a nitrogen atmosphere, and the mixture is stirred at a speed of 500-1000 rpm. The solvent is dipropylene glycol methyl ether acetate, propylene glycol phenyl ether acetate, or ethylene glycol ethyl ether; S3, then reacting in a sealed container at a high temperature of 120°C for 4 hours, filtering and vacuum drying to obtain a MIL-101-acrylate monomer complex; Preparation of MIL-101-acrylate monomer complex modified photoresist: S4. Under nitrogen protection, the MIL-101-acrylate monomer complex, epoxy resin, dye, photoinitiator, leveling agent and solvent were mixed in a certain proportion and stirred at 500 rpm for 1 hour; S5. Further add the mixed product into the remaining solvent dipropylene glycol methyl ether acetate, and stir and mix at a speed of 600 rpm for 30 minutes to obtain the final photoresist.

2. The preparation method according to claim 1, wherein: In step S2, the mass ratio of MIL-101, polymethylphenylsiloxane, and acrylate monomer is 1:0.1:

10.

3. The preparation method according to claim 1, wherein: The acrylic acid ester monomer in step S2 is selected from one or more of hydroxyethyl acrylate, tripropylene glycol diacrylate, trimethylolpropane triacrylate, and methyl acrylate.

4. The preparation method according to claim 1, wherein: The following components are included in step S4 by weight: 20-40 parts of epoxy resin, 10-30 parts of MIL-101-acrylate monomer complex, 1-5 parts of dye, 1-2 parts of photoinitiator, 0.1-0.5 parts of leveling agent, and 20-50 parts of solvent.

5. A negative photoresist prepared by the method according to any one of claims 1 to 4, characterized in that: Acrylate monomers and MIL-101 are used to form a composite.

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