Dry film preparation method based on polyimide system

Abstract

The dry film preparation method based on the polyimide system comprises the following steps: S1, preparing raw materials; s2, preparing a polyimide precursor solution; s3, adding and mixing an additive; s4, coating and forming; s5, surface drying and pre-drying; s6, carrying out post-treatment; and S7, using the dry film. According to the method, the dry film material with excellent performance can be prepared, the high requirement of a semiconductor manufacturing process on the dry film material is met, meanwhile, the preparation process is simplified, and the production cost is reduced.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of material preparation, in particular to a preparation method of dry film material based on a polyimide system, mainly applied in the fields of electronic circuit board manufacturing and semiconductor packaging. BACKGROUND

[0002] In the process of electronic circuit board manufacturing and semiconductor manufacturing, dry film material as a key material for photolithography process, its performance has a crucial influence on the precision, reliability and cost of chip manufacturing. With the development of semiconductor industry towards higher integration and smaller feature size, the performance requirements of dry film material are increasingly stringent.

[0003] In modern electronic manufacturing industry, the quality and performance of dry film material directly affect the production quality and efficiency of electronic products. Traditional dry film material gradually exposes many problems when facing the increasingly fine and high-performance electronic manufacturing demands. In terms of resolution, as the line spacing of electronic circuit board is continuously reduced, traditional dry film is difficult to meet the high-resolution imaging requirements, resulting in rough line edges, poor precision, and affecting the electrical performance of electronic products. In terms of adhesion, the adaptability of traditional dry film to different substrate materials is limited, and delamination and layering phenomena easily occur, reducing the reliability and stability of products. In high-temperature processes, ordinary dry film is prone to thermal decomposition and deformation, leading to decreased pattern precision and affecting the performance and yield of chips.

[0004] At the same time, traditional dry film lacks chemical corrosion resistance, and in etching, developing and other process links, some dry films lack resistance to etching solution, may dissolve or swell, and are difficult to meet the needs of fine line production. Therefore, it is of great practical significance to develop a dry film material preparation method that can overcome the above defects and has high resolution, strong adhesion and excellent chemical corrosion resistance.

[0005] Polyimide is a high-performance polymer material with excellent heat resistance, chemical stability, mechanical properties and insulation performance. Applying polyimide to the preparation of dry film material is expected to solve the above problems of traditional dry film and provide better material selection for semiconductor manufacturing. However, the preparation technology of dry film material based on polyimide system is not mature at present, and there are problems such as complex preparation process, high cost, unstable product performance, etc., which limit its wide application in the semiconductor industry. SUMMARY

[0006] To solve the above technical problems, the purpose of the present application is to provide a preparation method of dry film material based on a polyimide system for the fields of electronic circuit board manufacturing and semiconductor packaging, which can prepare dry film material with excellent performance, meet the high requirements of semiconductor manufacturing process on dry film material, and simplify the preparation process and reduce production cost.

[0007] To achieve the above technical purposes, achieve the above technical effects, the present application is realized by the following technical solutions, mainly including the following steps:

[0008] S1, raw material preparation

[0009] (1) diamine and dianhydride: select diamine and dianhydride monomers that can prepare polyimide with flexibility and thermal stability; wherein, the diamine can select aromatic diamine, such as 4,4'-diamino diphenyl ether (ODA) and the like as diamine monomer. The dianhydride can select rigid aromatic dianhydride, such as pyromellitic dianhydride (PMDA).

[0010] (2) solvent: composed of high boiling point solvent and low boiling point solvent mixed in a certain proportion. High boiling point solvents include but are not limited to N-methyl pyrrolidone (NMP), N,N-dimethylformamide (DMF), N,N-dimethylacetamide (DMAC) and dimethyl sulfoxide (DMSO) and the like, low boiling point solvents include but are not limited to methanol, ethanol, n-hexane, isopropanol and tetrahydrofuran and the like. The high boiling point solvent part is mixed by one or more of the high boiling point solvents, and the low boiling point solvent part is mixed by one or more of the low boiling point solvents. The mixed solvent has good solubility and volatility, which can ensure the sufficient reaction of diamine monomer and dianhydride monomer, and also facilitate the volatilization of solvent and the formation of dry film during the preparation of dry film.

[0011] (3) filler: nano-silicon dioxide with a particle size of 5-10um is selected as the filler, which is added after surface treatment by silane coupling agent KH-570, and the addition amount is 2~5% of the total mass of diamine and dianhydride, which can improve the hardness, wear resistance and dimensional stability of the dry film.

[0012] (4) adhesion promoter: silane coupling agent KH-560 containing epoxy group is selected as the adhesion promoter, and the addition amount is 3% of the mass of the photosensitive resin, which can improve the adhesion between the dry film and the substrate material.

[0013] S2, preparation of polyimide precursor solution

[0014] The dianhydride monomer and the diamine monomer are dissolved in an organic solvent according to a certain molar ratio, stirred at room temperature for a certain time under inert gas protection, and a polyimide precursor solution is obtained. The dianhydride monomer can be selected from pyromellitic dianhydride, biphenyl tetracarboxylic dianhydride, etc.; the diamine monomer can be selected from p-phenylenediamine, m-phenylenediamine, etc.; and the organic solvent can be selected from low-boiling mixed solvents such as a methanol-tetrahydrofuran mixed solvent, an ethanol-tetrahydrofuran mixed solvent, etc. In this embodiment, the dianhydride monomer is pyromellitic dianhydride, the diamine monomer is p-phenylenediamine, the organic solvent is a methanol-tetrahydrofuran mixed solvent (weight ratio 3:1), the molar ratio of the dianhydride monomer to the diamine monomer is 1:1, the reaction temperature is controlled at 20-25°C, and the reaction time is 12-18 hours.

[0015] S3, addition and mixing of additives

[0016] Additives such as tackifiers, plasticizers, and stabilizers are added to the above polyimide precursor solution, which is stirred uniformly at room temperature to make the additives fully dispersed in the solution. The tackifier can be selected from hydrocarbon resins, phenolic resins, and polyamide resins, etc.; the plasticizer can be selected from dibutyl phthalate, dioctyl sebacate, etc.; and the stabilizer can be selected from hindered phenols and phosphite esters, etc. In this embodiment, the tackifier is polyamide resin, the plasticizer is dibutyl phthalate, and the stabilizer is 2,6-di-tert-butyl-p-cresol, and their added amounts are 2%, 5%, and 1% of the mass of the polyimide precursor, respectively. It should be noted that the tackifier added in this part needs to be resistant to high temperature, such as rosin and its derivatives, terpene resins, hydrocarbon resins, phenolic resins, and polyamide resins, etc.

[0017] S4, film forming

[0018] The uniformly mixed dry film slurry is coated on a carrier film (PET film) using a precision coater, and the coating thickness is controlled at 20-50 um according to the actual application requirements. During the coating process, the coating environment temperature is controlled at 20-25°C and the humidity is controlled at 40%-60% to ensure the uniformity and stability of the coating film. After the coating is completed, the coating film is preliminarily leveled at room temperature for 10-15 minutes. The coating process can be performed by spin coating, blade coating, or roller coating, etc., and in this embodiment, the blade coating method is selected.

[0019] S5, tack dry and pre-drying

[0020] Put the wet film coated carrier film into natural surface drying (about 20 min) at room temperature, remove most of the organic solvent, and make the coating film preliminary solidification; then increase the temperature to perform pre-drying treatment to obtain a composite film body, and the pre-drying temperature is set to 60-80℃, and the time is 1-2 hours. The oven temperature is increased to 100-120℃, and heat curing is performed for 1-2 hours to fully perform crosslinking reaction, and a dry film material with a stable three-dimensional network structure is formed. During the heat curing process, the crosslinking density and performance of the dry film are optimized by controlling the heating rate and curing time.

[0021] S6, post-treatment

[0022] After curing, the dry film is taken out of the oven and cooled to room temperature. A surface treatment device is used to slightly polish and clean the surface of the dry film, remove impurities and small particles that may exist on the surface, and improve the flatness and smoothness of the surface of the dry film. The composite film body is bonded to another carrier film (PET film) at a certain temperature and pressure to form a dry film material with a "sandwich" structure. Finally, according to the actual use specification requirements, cutting and packaging are performed to obtain the finished dry film material.

[0023] S7, dry film use

[0024] The prepared "sandwich" structure first carrier film (PET film) is separated from the polyimide dry film layer, and the polyimide dry film layer is bonded to a sample (such as a wafer, glass, etc.) on a vacuum film press; under the action of a certain temperature and pressure of the vacuum film press, the polyimide dry film is tightly combined with the sample. After the "sandwich" structure second carrier film (PET film) is separated from the polyimide dry film layer, the polyimide dry film is subjected to imidization treatment by stepwise heating, and the specific heating process is: 100℃ / 30min, 150℃ / 30min, 150℃ / 30min, 200℃ / 30min, 250℃ / 30min, 300℃ / 120min. The crosslinking reaction is fully carried out to form a dry film material with a stable three-dimensional network structure. During the heat curing process, the crosslinking density and performance of the dry film are optimized by controlling the heating rate and curing time.

[0025] The polyimide system-based dry film material prepared by the present application has the following beneficial effects:

[0026] (1) Excellent solvent: the blended solvent obtained by mixing high-boiling point solvent and low-boiling point solvent has good solubility and volatility, which not only ensures the sufficient reaction of diamine monomer and dianhydride monomer, but also facilitates the volatilization of solvent and the formation of dry film during the preparation process of dry film.

[0027] (2) Excellent heat resistance: The high thermal stability of polyimide itself enables the dry film to maintain good physical and chemical properties during high-temperature processing in semiconductor manufacturing, effectively preventing thermal decomposition and deformation problems, ensuring pattern accuracy, and improving chip yield.

[0028] (3) Strong adhesion: The added adhesion promoter chemically reacts with the substrate surface to form chemical bonds, effectively improving the adhesion of the dry film to various substrate materials such as copper foil and ceramic substrates, with adhesion strength reaching 5-7 N / cm, effectively preventing film peeling and delamination.

[0029] (4) Excellent chemical corrosion resistance: The highly cross-linked network structure and stable chemical composition enable the dry film to exhibit excellent resistance to various etching solutions and other chemical reagents, with no significant swelling or dissolution of the film layer during etching and wet processing, ensuring the accuracy of pattern transfer and improving product yield.

[0030] (5) Simplified preparation process and reduced cost: By optimizing reaction conditions and process flow, unnecessary steps and complex operations are reduced, ensuring product performance while reducing production costs and improving production efficiency, which is beneficial to large-scale industrial production. BRIEF DESCRIPTION OF DRAWINGS

[0031] Figure 1 Schematic diagram of the structure of the "sandwich" structure limited imine dry film material.

[0032] Figure 2 Chemical structures of several common diamine monomers and dianhydride monomers. DETAILED DESCRIPTION

[0033] The present application will be further described below in conjunction with the accompanying drawings Figure 1 / 2 and examples.

[0034] (1) Preparation of polyimide precursor solution

[0035] In a dry reaction vessel, nitrogen gas was introduced for inert gas protection. 20g of phthalic anhydride was slowly added to 100ml of N-methyl pyrrolidone, and stirred until completely dissolved. Then 10.8g of p-phenylenediamine was added to the above solution, and stirred at room temperature for 12 hours to obtain a light yellow transparent polyimide precursor solution. During the reaction, the system viscosity was monitored every 60 minutes, and when the viscosity reached the expected range, the reaction was stopped to obtain the polyimide precursor solution.

[0036] (2) Addition and mixing of additives

[0037] To the prepared polyimide precursor solution, 0.4 g of benzoin ether, 1.0 g of dibutyl phthalate and 0.2 g of 2,6-di-tert-butyl-p-cresol were added in turn, and stirred at room temperature for 1 hour to make the additives uniformly dispersed in the solution.

[0038] (3) Film forming

[0039] A clean polyester film was selected as the carrier film, and the uniformly mixed solution was poured into a doctor blade mold to uniformly coat the carrier film by doctor blade method, with the wet film thickness controlled at 25 μm. The coating workshop environment temperature was controlled at 22°C and the humidity was 50%. After coating, the coated film was placed on a clean platform and left at room temperature for 12 minutes.

[0040] (4) Drying and curing

[0041] The carrier film coated with the wet film was placed in an oven, pre-dried at 70°C for 1.5 hours, and then the oven temperature was raised to 120°C for 1.5 hours to fully carry out the crosslinking reaction, forming a dry film material with a stable three-dimensional network structure. During the temperature rising process, the temperature was slowly raised at a rate of 2°C / min to ensure uniform curing of the dry film.

[0042] (5) Post-processing

[0043] The imidized dry film was taken out of the oven and placed in a well-ventilated place to cool to room temperature. The surface of the dry film was lightly sanded with sandpaper, and then the surface was wiped with alcohol using a dust-free cloth to obtain a dry film material based on the polyimide system with a smooth surface and excellent performance. Another polyester film was used as a carrier film to cover the prepared polyimide dry film layer to form a "sandwich" structure. The schematic diagram of the dry film structure is shown in Figure 1 .

[0044] (6) Sub-packaging

[0045] According to customer requirements, the dry film was cut into a roll with a width of 300 mm and a length of 50 m, and vacuum packaged with an aluminum foil bag to complete the preparation of the "sandwich" structure dry film material.

[0046] As a high-performance polymer material, the performance of the polyimide film is highly dependent on the selection of diamine and dianhydride monomers. The classification and typical representatives of the diamine monomers and dianhydride monomers commonly used for preparing polyimide are shown in Table 1 and Table 2. The diamine monomers and dianhydride monomers covered by the present patent include but are not limited to those listed in Table 1 and Table 2. The chemical structures of several common diamine monomers (ODA, PDA, BAPP) and dianhydride monomers (BPDA, ODPA, PMDA) are shown in Figure 2 .

[0047] Table 1. Classification and typical representatives of diamine monomers commonly used to prepare polyimides

[0048]

[0049] Table 2. Classification and typical representatives of dianhydride monomers commonly used to prepare polyimides

[0050]

[0051] It is apparent that a person skilled in the art can achieve the present patent in other concrete forms without departing from the spirit or the fundamental characteristics of the present patent, and that the embodiments described above are to be considered in all respects as illustrative and not restrictive, the scope of the present patent being defined by the claims hereafter rather than that which has been described above, and therefore all changes falling within the meaning and the range of equivalency of the claims are therefore to be embraced therein. Any reference signs in the claims should not be construed as limiting the claims concerned.

Claims

1. A method for preparing a dry film based on a polyimide system, characterized in that, Includes the following steps: S1, Raw Material Preparation (1) Diamine and dianhydride: Diamine and dianhydride monomers for preparing polyimides with flexibility and thermal stability are selected; wherein, the diamine is selected as an aromatic diamine and the dianhydride is selected as a rigid aromatic dianhydride; (2) Solvent: A mixed solvent is composed of a high-boiling-point solvent and a low-boiling-point solvent mixed in a certain proportion; (3) Filler: Nano silica with a particle size of 5-10 μm is selected as filler. It is added after surface treatment with silane coupling agent KH-570. The amount added is 2-5% of the total mass of diamine and dianhydride to improve the hardness, wear resistance and dimensional stability of the dry film. (4) Adhesion promoter: KH-560, a silane coupling agent containing epoxy groups, was selected as the adhesion promoter. The amount added was 3% of the mass of the photosensitive resin to improve the adhesion between the dry film and the substrate material. S2, Preparation of polyimide precursor solution The dianhydride monomer and the diamine monomer were dissolved in an organic solvent at a certain molar ratio, and the mixture was stirred and reacted at room temperature for a certain time under inert gas protection to obtain a polyimide precursor solution. S3, Additives and Mixing Add tackifier, plasticizer and stabilizer to the above polyimide precursor solution, and stir evenly at room temperature to ensure that the additives are fully dispersed in the solution; S4, Coating Forming A precision coating machine is used to coat the uniformly mixed dry film slurry onto the carrier film, and the coating thickness is controlled between 20-50 μm according to the actual application requirements. S5, surface drying and pre-drying The carrier film coated with wet film is placed in the room temperature for natural surface drying to remove most of the organic solvent and allow the coating to initially cure; then the temperature is raised for pre-drying treatment to obtain the composite film. The pre-drying temperature is set at 60-80℃ and the time is 1-2 hours. S6, Post-processing Remove the cured dry film from the oven and allow it to cool to room temperature; S7, Dry Film Use The prepared "sandwich" structure first carrier film is peeled off from the polyimide dry film layer, and the polyimide dry film layer and the sample are pressed together on a vacuum laminator; under the action of a certain temperature and pressure of the vacuum laminator, the polyimide dry film and the sample will be tightly bonded.

2. The method for preparing dry films based on a polyimide system according to claim 1, characterized in that: In S1, the high-boiling-point solvents include N-methylpyrrolidone (NMP), N,N-dimethylformamide (DMF), N,N-dimethylacetamide (DMAC), and dimethyl sulfoxide (DMSO), and the low-boiling-point solvents include methanol, ethanol, n-hexane, isopropanol, and tetrahydrofuran; wherein the high-boiling-point solvent portion is composed of one or more of the high-boiling-point solvents, and the low-boiling-point solvent portion is composed of one or more of the low-boiling-point solvents.

3. The method for preparing dry films based on a polyimide system according to claim 1, characterized in that: The mixed solvent has good solubility and volatility, which not only ensures the full reaction of the diamine monomer and dianhydride monomer, but also facilitates the evaporation of the solvent and the formation of the dry film during the dry film preparation process.

4. The method for preparing a dry film based on a polyimide system according to claim 1, characterized in that: In S2, the dianhydride monomer is selected from pyromellitic dianhydride and / or biphenyltetracarboxylic dianhydride; the diamine monomer is selected from p-phenylenediamine and / or m-phenylenediamine; the organic solvent is a low-boiling-point mixed solvent, which is a mixture of methanol and tetrahydrofuran or a mixture of ethanol and tetrahydrofuran. The dianhydride monomer used is pyromellitic dianhydride, the diamine monomer used is p-phenylenediamine, the organic solvent is a mixture of methanol and tetrahydrofuran in a weight ratio of 3:1, the molar ratio of dianhydride monomer to diamine monomer is 1:1, the reaction temperature is controlled at 20~25℃, and the reaction time is 12-18 hours.

5. The method for preparing a dry film based on a polyimide system according to claim 1, characterized in that: In S3, the tackifier is selected from one or more of hydrocarbon resins, phenolic resins, and polyamide resins; the plasticizer is selected from one or more of dibutyl phthalate and dioctyl sebacate; and the stabilizer is selected from one or more of hindered phenols and phosphites.

6. The method for preparing a dry film based on a polyimide system according to claim 5, characterized in that: The tackifier is polyamide resin, the plasticizer is dibutyl phthalate, and the stabilizer is 2,6-di-tert-butyl-p-cresol, with addition amounts of 2%, 5%, and 1% of the mass of the polyimide precursor, respectively. The tackifier added in this part must be heat resistant.

7. The method for preparing a dry film based on a polyimide system according to claim 1, characterized in that: In S4, during the coating process, the coating environment temperature is controlled at 20-25℃ and the humidity at 40%-60% to ensure the uniformity and stability of the coating film. After coating, the film is left to stand at room temperature for 10-15 minutes to allow it to level initially. The coating process can be spin coating, scraping coating, or roller coating.

8. The method for preparing a dry film based on a polyimide system according to claim 1, characterized in that: In S5, the oven temperature is raised to 100-120℃ and heat-cured for 1-2 hours to allow the cross-linking reaction to proceed fully and form a dry film material with a stable three-dimensional network structure. During the heat curing process, the cross-linking density and performance of the dry film are optimized by controlling the heating rate and curing time.

9. The method for preparing a dry film based on a polyimide system according to claim 1, characterized in that: In S6, a surface treatment device is used to lightly polish and clean the surface of the dry film to remove any impurities and tiny particles that may be present on the surface, thereby improving the smoothness and gloss of the dry film surface. The composite film body is then bonded to another carrier film under certain temperature and pressure to form a "sandwich" structure dry film material. Finally, the dry film material is cut and packaged according to the actual usage specifications to obtain the finished dry film material.

10. The method for preparing a dry film based on a polyimide system according to claim 1, characterized in that: In step S7, after the "sandwich" structured second carrier film is peeled off from the polyimide dry film layer, the polyimide dry film is subjected to imidization treatment by step-by-step heating. The specific heating process is: 100℃ / 30min, 150℃ / 30min, 150℃ / 30min, 200℃ / 30min, 250℃ / 30min, 300℃ / 120min; this allows the crosslinking reaction to proceed fully, forming a dry film material with a stable three-dimensional network structure. During the thermosetting process, the crosslinking density and performance of the dry film are optimized by controlling the heating rate and curing time.

Images