A self-sensitizing negative polyimide precursor and its preparation method and application

Abstract

The present invention relates to the technical field of polymer materials, and in particular to a self-sensitizing negative polyimide precursor and a preparation method and application thereof. In the present invention, 4,4'-dinitro-1,1'-biphenyl-2,2'-dicarboxylic acid is used as a starting material and undergoes an acylation reaction with dithionyl chloride to obtain compound 1; then an esterification reaction is performed with hydroxyethyl methacrylate to obtain compound 2; then the nitro group is reduced to an amino group, and after purification, an intermediate of a self-sensitizing negative polyimide precursor is obtained. The intermediate and 3,3',4,4'-dibenzophenone tetraacid dianhydride are subjected to a polymerization reaction to obtain polyamic acid, i.e., a self-sensitizing negative polyimide precursor. In the present invention, the intermediate of the self-sensitizing negative polyimide precursor contains a benzophenone structure, and free radicals can be generated under ultraviolet light irradiation, thereby achieving the effect of a photoinitiator. The dual photosensitivity of the ketone carbonyl group and the double bond in the self-sensitizing negative polyimide precursor material provided by the present invention can improve the sensitivity of resin exposure.

Description

Technical Field

[0001] The invention relates to the technical field of polymer materials, and in particular to a self-sensitizing negative polyimide precursor and a preparation method and application thereof. Background Art

[0002] The information disclosed in this background technology section is only intended to enhance the understanding of the overall background of the invention, and should not necessarily be regarded as an admission or any form of suggestion that the information constitutes the prior art already known to a person skilled in the art.

[0003] Polyimide material is a functional material with extremely excellent performance, especially high temperature resistance, insulation and dielectric properties, so it is widely used in military and aerospace fields; as a civilian product, polyimide is widely used in the field of microelectronics, among which photosensitive polyimide (PSPI) is used as a buffer layer, passivation layer and alpha particle blocking layer of integrated circuits. Polyimide for photoresist has become one of the three main uses of polyimide, along with polyimide film and polyimide liquid crystal alignment agent.

[0004] According to the different solubility properties after exposure, polyimide is divided into negative polyimide and positive polyimide. After the positive polyimide is exposed through the mask through the photolithography process, the exposed area undergoes a photodecomposition reaction, which improves its solubility in the developer, so that it dissolves in the developer, and finally obtains the same pattern as the mask; negative polyimide is the opposite. After the photolithography process, after the mask is exposed, the exposed area undergoes a photochemical reaction, and the solubility is weakened. The unexposed area dissolves in the developer, and finally obtains a pattern opposite to the mask.

[0005] Negative polyimide is divided into ester type, ionic type and self-sensitizing type negative polyimide. Ester type and ionic type polyimide need to add photoinitiator to produce photochemical reaction, while self-sensitizing polyimide can produce cross-linking reaction by relying on its unique benzophenone structure, and can produce cross-linking reaction without initiator. No small molecule by-products are produced under high temperature curing, which effectively improves the volume shrinkage problem of ester type and ionic type photosensitive polyimide, and avoids the decrease of thermodynamic, mechanical and electrical properties of photosensitive polyimide caused by residual photoinitiator. Currently available negative self-sensitizing polyimide has two photochemical reaction mechanisms. One is that benzophenone cross-links with the methyl group ortho to the amino group. This polyimide requires the use of a monomer diamine containing two methyl groups ortho to the amino group. The monomer synthesis is very difficult and expensive, and this polyimide has poor photosensitivity. The other is that benzophenone initiates the cross-linking of methacrylic acid side chains. This has better photosensitivity, but its synthesis process requires the use of dimethyl sulfoxide or methacryloyl chloride, which produces chloride ions and acidic hydrogen ions, which reduce the electrical properties of the photoresist and corrode the substrate. Summary of the invention

[0006] In order to overcome the above problems, the present invention provides a self-sensitizing negative polyimide precursor and a preparation method and application thereof.

[0007] In order to achieve the above technical objectives, the present invention adopts the following technical solutions:

[0008] The first aspect of the present invention provides an intermediate of a self-sensitizing negative polyimide precursor, the structural formula of which is shown in formula (I):

[0009]

[0010] The second aspect of the present invention provides a method for preparing the intermediate of the self-sensitizing negative polyimide precursor, comprising:

[0011] (1) 4,4'-dinitro-1,1'-biphenyl-2,2'-dicarboxylic acid reacts with dithionyl chloride to obtain compound 1;

[0012] (2) dissolving compound 1 in organic solvent 1, adding hydroxyethyl methacrylate, and reacting to obtain compound 2;

[0013] (3) Compound 2 is dissolved in organic solvent 2, and reacted under the catalysis of a catalyst to obtain an intermediate of a self-sensitizing negative polyimide precursor;

[0014] The structural formula of compound 1 is shown in formula (II):

[0015]

[0016] The structural formula of compound 2 is shown in formula (III):

[0017]

[0018] The third aspect of the present invention provides use of the intermediate of the self-sensitizing negative polyimide precursor described in the first aspect in synthesizing a self-sensitizing negative polyimide precursor.

[0019] The fourth aspect of the present invention provides a self-sensitizing negative polyimide precursor, which is obtained by polymerizing an intermediate of the self-sensitizing negative polyimide precursor with 3,3',4,4'-dibenzophenone tetracarboxylic dianhydride; wherein the molar ratio of the intermediate of the self-sensitizing negative polyimide precursor to 3,3',4,4'-dibenzophenone tetracarboxylic dianhydride is 0.8 to 1.2:1, the reaction conditions are stirring reaction at room temperature, and the reaction time is 18 to 26 hours.

[0020] A fifth aspect of the present invention provides a method for preparing a self-sensitizing negative polyimide precursor, comprising stirring an intermediate of the self-sensitizing negative polyimide precursor and 3,3',4,4'-benzophenone tetracarboxylic dianhydride at room temperature to obtain a self-sensitizing negative polyimide precursor;

[0021] The molar ratio of the intermediate of the self-sensitizing negative polyimide precursor to 3,3',4,4'-dibenzophenone tetracarboxylic dianhydride is 0.8 to 1.2:1;

[0022] The stirring reaction time at room temperature is 18 to 26 hours.

[0023] The sixth aspect of the present invention provides the use of the self-sensitizing negative polyimide precursor in the preparation of a negative photoresist.

[0024] The beneficial effects of the present invention are:

[0025] (1) In the present invention, 4,4'-dinitro-1,1'-biphenyl-2,2'-dicarboxylic acid is used as a starting material and undergoes an acylation reaction with dichlorothionyl to obtain compound 1; the product is not separated, and pyridine is used as a catalyst to undergo an esterification reaction with hydroxyethyl methacrylate to obtain compound 2; iron and hydrochloric acid are then used as catalysts to reduce the nitro group to an amino group, and after purification, an intermediate of a self-sensitizing negative polyimide precursor is obtained. The intermediate of the self-sensitizing negative polyimide precursor is polymerized with 3,3',4,4'-dibenzophenone tetracarboxylic dianhydride to obtain polyamic acid, i.e., a self-sensitizing negative polyimide precursor. In the present invention, a cross-linking group (methacrylate) is introduced in advance into the intermediate of the self-sensitizing negative polyimide precursor, so that the synthesis process of the polymer is shorter and greener, and the self-sensitizing negative polyimide precursor can be formed by simply stirring and polymerizing the two monomers in a solvent, without purification, and the reaction solution is directly used for photolithography.

[0026] (2) The intermediate of the self-sensitizing negative polyimide precursor in the present invention contains a benzophenone structure, which can generate free radicals under ultraviolet light irradiation, thereby achieving the effect of a photoinitiator. The dual photosensitivity of the ketone carbonyl group and the double bond in the self-sensitizing negative polyimide precursor material provided by the present invention can improve the sensitivity of resin exposure. At the same time, the present invention first synthesizes the self-sensitizing negative polyimide precursor material at low temperature, and uses the benzophenone structure and side chain methacrylate contained in the main chain to cross-link at low temperature, thereby avoiding problems such as wafer warping caused by high-temperature imidization.

[0027] (3) When the self-sensitizing negative polyimide precursor prepared by the present invention is used as a photoresist, an alkaline solution can be used for development, thereby avoiding environmental pollution caused by organic solvents. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] The accompanying drawings in the specification, which constitute a part of the present invention, are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute improper limitations on the present invention.

[0029] Figure 1 It is a synthetic route of the intermediate of the self-sensitizing negative polyimide precursor in the present invention;

[0030] Figure 2 The hydrogen nuclear magnetic resonance spectrum of the intermediate of the self-sensitizing negative polyimide precursor;

[0031] Figure 3 The nuclear magnetic resonance hydrogen spectrum and signal attribution of the self-sensitizing negative polyimide precursor and the self-sensitizing negative polyimide in the present invention;

[0032] Figure 4 This is the infrared spectrum of the intermediate of the self-sensitizing negative polyimide precursor;

[0033] Figure 5 It is the infrared spectrum of the self-sensitizing negative polyimide precursor (polyamidoamine);

[0034] Figure 6 This is the infrared spectrum of the polyimide synthesized by ring formation of the self-sensitized negative polyimide precursor;

[0035] Figure 7 This is a metallographic microscope photo of the self-sensitized negative polyimide precursor after photolithography development;

[0036] Figure 8 These are scanning electron microscope images of the self-sensitizing negative polyimide precursor after photolithography development. a to d are the morphologies of line widths of 10 μm, 20 μm, 40 μm, and 80 μm, respectively. DETAILED DESCRIPTION

[0037] It should be noted that the following detailed descriptions are exemplary and are intended to provide further explanation of the present invention. Unless otherwise specified, all technical and scientific terms used in the present invention have the same meanings as those commonly understood by those skilled in the art to which the present invention belongs.

[0038] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit exemplary embodiments according to the present invention. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "comprising" and / or "including" are used in this specification, it indicates the presence of features, steps, operations, devices, components and / or combinations thereof.

[0039] The first typical embodiment of the present invention provides an intermediate of a self-sensitizing negative polyimide precursor, the structural formula of which is shown in formula (I):

[0040]

[0041] A second typical embodiment of the present invention provides a method for preparing an intermediate of the self-sensitizing negative polyimide precursor, comprising:

[0042] (1) 4,4'-dinitro-1,1'-biphenyl-2,2'-dicarboxylic acid reacts with dithionyl chloride to obtain compound 1;

[0043] (2) dissolving compound 1 in organic solvent 1, adding hydroxyethyl methacrylate, and reacting to obtain compound 2;

[0044] (3) Compound 2 is dissolved in organic solvent 2, and reacted under the catalysis of a catalyst to obtain an intermediate of a self-sensitizing negative polyimide precursor;

[0045] The structural formula of compound 1 is shown in formula (II):

[0046]

[0047] The structural formula of compound 2 is shown in formula (III):

[0048]

[0049] In one or more embodiments, the reaction in step (1) is carried out under inert gas conditions.

[0050] In one or more embodiments, in step (1), the molar ratio of 4,4'-dinitro-1,1'-biphenyl-2,2'-dicarboxylic acid to thionyl chloride is 1:(95-133), preferably 1:133.

[0051] In one or more embodiments, in step (1), the reaction temperature is 75 to 90° C., preferably 80° C.; the reaction time is 1.5 to 3 h, preferably 2 h.

[0052] In one or more embodiments, in step (2), compound 1 is dissolved in organic solvent 1, hydroxyethyl methacrylate is added, and the mixture is reacted under the catalysis of pyridine to obtain compound 2.

[0053] Preferably, the organic solvent 1 comprises acetone.

[0054] Preferably, the molar ratio of compound 1 to hydroxyethyl methacrylate is 1:(2-3), preferably 1:2.

[0055] Preferably, the molar ratio of compound 1 to pyridine is 1:(1-2), preferably 1:1.

[0056] Preferably, the reaction temperature is 95-105° C., preferably 100° C.; the reaction time is 2-5 h.

[0057] In one or more embodiments, in step (3), compound 2 is dissolved in organic solvent 2, and reacted under the catalysis of iron powder and hydrochloric acid to obtain an intermediate of a self-sensitizing negative polyimide precursor.

[0058] Preferably, the organic solvent 2 comprises a mixed solution of isopropanol and water, and the volume ratio of the isopropanol to water is 3.5 to 5:1, preferably 4:1.

[0059] Preferably, the molar ratio of compound 2 to iron powder is 1:8-12, preferably 1:10.

[0060] Preferably, the molar ratio of compound 2 to hydrochloric acid is 6 to 10:1, preferably 8.3:1.

[0061] Preferably, the reaction temperature is 95-105° C., preferably 100° C.; the reaction time is 1-3 h.

[0062] A third typical embodiment of the present invention provides use of the intermediate of the self-sensitizing negative polyimide precursor described in the first aspect in synthesizing a self-sensitizing negative polyimide precursor.

[0063] A fourth typical embodiment of the present invention provides a self-sensitizing negative polyimide precursor, wherein the self-sensitizing negative polyimide precursor is obtained by polymerizing an intermediate of the self-sensitizing negative polyimide precursor with 3,3',4,4'-dibenzophenone tetracarboxylic dianhydride; wherein the molar ratio of the intermediate of the self-sensitizing negative polyimide precursor to 3,3',4,4'-dibenzophenone tetracarboxylic dianhydride is 0.8 to 1.2:1, the reaction conditions are stirring reaction at room temperature, and the reaction time is 18 to 26 hours.

[0064] In one or more embodiments, the self-sensitizing negative polyimide precursor is obtained by polymerizing an intermediate of the self-sensitizing negative polyimide precursor and 3,3',4,4'-benzophenone tetracarboxylic dianhydride in an organic solvent under an inert gas atmosphere.

[0065] Preferably, the organic solvent comprises N-methylpyrrolidone.

[0066] In one or more embodiments, the molar ratio of the intermediate of the self-sensitizing negative polyimide precursor to 3,3',4,4'-benzophenone tetracarboxylic dianhydride is 1:1.

[0067] In one or more embodiments, the reaction time is 20 hours.

[0068] A fifth typical embodiment of the present invention provides a method for preparing a self-sensitizing negative polyimide precursor, comprising stirring an intermediate of the self-sensitizing negative polyimide precursor and 3,3',4,4'-benzophenone tetracarboxylic dianhydride at room temperature to obtain a self-sensitizing negative polyimide precursor;

[0069] The molar ratio of the intermediate of the self-sensitizing negative polyimide precursor to 3,3',4,4'-dibenzophenone tetracarboxylic dianhydride is 0.8 to 1.2:1;

[0070] The stirring reaction time at room temperature is 18 to 26 hours.

[0071] In one or more embodiments, the intermediate of the self-sensitizing negative polyimide precursor and 3,3',4,4'-benzophenone tetracarboxylic dianhydride are stirred in an organic solvent under an inert gas atmosphere to obtain a self-sensitizing negative polyimide precursor.

[0072] Preferably, the organic solvent comprises N-methylpyrrolidone.

[0073] In one or more embodiments, the molar ratio of the intermediate of the self-sensitizing negative polyimide precursor to 3,3',4,4'-benzophenone tetracarboxylic dianhydride is 1:1.

[0074] In one or more embodiments, the reaction time is 20 hours.

[0075] The sixth aspect of the present invention provides the use of the self-sensitizing negative polyimide precursor in the preparation of a negative photoresist.

[0076] In order to enable those skilled in the art to more clearly understand the technical solution of the present invention, the technical solution of the present invention will be described in detail below in conjunction with specific embodiments.

[0077] The chemical raw materials used in the embodiments of the present invention are all commercially available products.

[0078] Figure 1 The synthetic route of the intermediate of the self-sensitizing negative polyimide precursor in the present invention is as follows: Figure 1 , synthesize self-sensitizing negative polyimide precursor.

[0079] Example 1

[0080] 4,4'-Dinitro-1,1'-biphenyl-2,2'-dicarboxylic acid (5.0 g, 15 mmol) was added to an excess of thionyl chloride (150 mL) and heated to reflux at 80°C for 2 hours under nitrogen. After the reaction was completed, the mixture was cooled to room temperature, concentrated under reduced pressure, and used directly in the next step. The product compound 1 was a white solid with a yield of 95%.

[0081] The NMR data are as follows: 1 H NMR (400MHz, CDCl3) δ9.19 (d, J = 2.2Hz, 1H), 8.57 (dd, J = 8.4, 2.2Hz, 1H), 7.44 (d, J = 8.4Hz, 1H).

[0082] 13 C NMR (100MHz, CDCl3) δ166.30,147.98,145.94,133.50,131.12,128.61,128.20.

[0083] Embodiment 2:

[0084] At 0°C, compound 1 (2, 5.5 g, 15 mmol), acetone (7.2 mL), pyridine (1.2 mL, 15 mmol) were added to the reaction bottle in sequence, and hydroxyethyl methacrylate (3.7 mL, 30 mmol) was slowly added dropwise, and the reaction mixture was refluxed at 100°C for 2 hours. After the reaction was completed, it was cooled to room temperature and water was added to quench the reaction. The reaction mixture was extracted with dichloromethane 3 times, dried over anhydrous sodium sulfate, and the solvent was removed by a rotary evaporator. The residue was purified by silica gel column chromatography using petroleum ether / ethyl acetate (5:1) as the eluent. Compound 2 is a light yellow viscous liquid with a yield of 80%.

[0085] The NMR data are as follows:

[0086] 1 H NMR (400MHz, CDCl3) δ8.92 (d, J = 2.3Hz, 2H), 8.43 (dd, J = 8.4, 2.3Hz, 2H), 7.40 (d, J = 8. 4Hz,2H),6.08(s,2H),5.61(s,2H),4.41-4.38(m,4H),4.28–4.26(m,4H),1.93(s,6H).

[0087] 13 C NMR (100MHz, CDCl3) δ166.81,163.85,147.66,147.41,135.69,130.78,129.86,126.45,126.25,125.49,63.50,61.86,18.13.

[0088] HRMS(ESI):calculated for C 26 H 24 N 2 O 12 [M+Na] +:579.1227,found:579.1226.

[0089] Example 3

[0090] Compound 2 (3, 3.9 g, 7 mmol), iron powder (3.9 g, 70 mmol, 100 mesh), concentrated hydrochloric acid (commercial hydrochloric acid mass fraction of 37%, 70 μL), isopropanol (11.2 mL) and primary water (2.8 mL) were added to the reaction flask in sequence. After reflux at 100 ° C for 15 minutes, iron powder (3.9 g, 70 mmol, 100 mesh) and hydrochloric acid (70 μL) were added to the reaction flask, and refluxed at 100 ° C for 1 hour. After the reaction was completed, it was cooled to room temperature, filtered to remove excess iron powder, and washed with dichloromethane. The filtrate was extracted with dichloromethane three times, dried over anhydrous sodium sulfate, and the solvent was removed by rotary evaporator. The residue was purified by silica gel column chromatography using petroleum ether / ethyl acetate (1:1) as the eluent. The intermediate of the self-sensitizing negative polyimide precursor is a yellow viscous liquid with a yield of 76%.

[0091] The NMR data are as follows:

[0092] 1 H NMR (400MHz, CDCl3) δ7.25(d,J=2.3Hz,2H),6.95(d,J=8.1Hz,2H),6.77(dd,J=8.1,2.4Hz,2H ),6.07(s,2H),5.57(s,2H),4.26–4.22(m,4H),4.07-4.03(m,4H),3.78(s,4H),1.92(s,6H).

[0093] 13 C NMR (100MHz, CDCl3) δ167.13,166.96,145.24,135.91,133.28,131.63,130.15,125.89,118.05,116.07,62.35,62.05,18.20.

[0094] HRMS(ESI):calculated for C 26 H 28 N 2 O 8 [M+Na] + :519.1744,found:519.1741.

[0095] Figure 2 This is the hydrogen nuclear magnetic resonance spectrum of the intermediate of the self-sensitizing negative polyimide precursor.

[0096] Figure 4This is the infrared spectrum of the intermediate of the self-sensitizing negative polyimide precursor.

[0097] Example 4

[0098] Under nitrogen conditions, the intermediate of the self-sensitizing negative polyimide precursor (4, 3.0 g, 6 mmol) and ultra-dry N-methylpyrrolidone (20 mL) were added to the reaction bottle in sequence, and the reaction mixture was stirred at 10-15 ° C for 30 minutes to obtain a transparent solution. Then 3,3',4,4'-dibenzophenone tetracarboxylic dianhydride (5, 2.0 g, 6 mmol) and another ultra-dry N-methylpyrrolidone (7.6 mL) were added to the reaction solution to obtain a reaction mixture with a solid content of 15 wt%. The reaction temperature was raised to room temperature, and the polymerization system was stirred at room temperature for 20 hours to obtain a high viscosity solution, the composition of which was a self-sensitizing negative polyimide precursor (polyamic acid). Acetic anhydride (2.8 mL, 30 mmol) and pyridine (1.9 mL, 24 mmol) dried over molecular sieves were added to the solution, followed by ultra-dry N-methylpyrrolidone (60 mL) and the system was heated to 50 ° C and stirred for 24 hours to obtain a polyimide solution. The uniform polyimide solution was poured into an ethanol aqueous solution (150 mL, 75 vol%) and filtered to obtain a light yellow solid, which was washed with methanol three times and transferred to a vacuum drying oven and dried at 50 ° C overnight to obtain a light yellow solid polyimide. The NMR data of polyamidoamine and polyimide are as follows:

[0099] Self-sensitizing negative polyimide precursor (polyamic acid):

[0100] 1 H NMR(400MHz,DMSO)δ13.56(s,2H),10.84(s,2H),8.36-8.32(m,3H),8.17-8.04(m,2H),8.07-8.00(m, 2H),7.94-7.90(m,3H),7.25(s,2H),6.04(s,2H),5.72(s,2H),4.31(s,4H),4.15(s,4H),1.89(s,6H).

[0101] Self-sensitizing negative polyimide:

[0102] 1 H NMR (400MHz, DMSO) δ8.42–8.02(m,4H),7.79(d,J=8.2Hz,1H),7.50(d,J=7. 6Hz,1H),5.96(s,1H),5.64(s,1H),4.28(s,2H),4.13(s,2H),1.81(s,3H).

[0103] Figure 3The invention discloses the hydrogen nuclear magnetic resonance spectrum and signal attribution of the self-sensitizing negative polyimide precursor and the self-sensitizing negative polyimide.

[0104] from Figure 3 It can be seen that the common parts of polyimide and precursor are: the multiple peaks of 7.2-8.5ppm are hydrogen on the benzene ring of the polymer, the two peaks of 5.6-6.0ppm are hydrogen of olefin on the side chain, the two peaks of 4.1-4.3ppm are hydrogen of two methylene groups on the side chain, and 1.8ppm is hydrogen of methyl on the side chain. The parts that are different between polyimide and precursor are: two signals on the precursor, 13.5ppm is hydrogen of the carboxyl group of the precursor, and 10.8ppm is hydrogen on the amide. After the polyimide is cyclized, these two peaks disappear. In addition, polyimide is a symmetrical structure, and the integral of the nuclear magnetic hydrogen spectrum is half.

[0105] The above NMR analysis showed that polyimide and precursor were successfully synthesized.

[0106] Figure 5 This is the infrared spectrum of the self-sensitized negative polyimide precursor. Figure 6 This is the infrared spectrum of the polyimide synthesized by ring formation of self-sensitizing negative polyimide precursor.

[0107] The molecular structure of the self-sensitizing negative polyimide precursor is shown in formula (IV);

[0108]

[0109] The final polyimide molecular structure is shown in formula (V);

[0110]

[0111] Since the self-sensitizing negative polyimide precursor molecule shown in formula (IV) contains too many carboxyl groups, its molecular weight cannot be directly measured. It is further cyclized to synthesize the polyimide molecule shown in formula (V). The molecular weight Mn of the polyimide molecule shown in formula (V) is measured to be 4395 Daltons, and the dispersion coefficient Mw / Mn is 1.67.

[0112] Experimental Example 1

[0113] The performance of the self-sensitizing negative polyimide precursor was tested.

[0114] The self-sensitizing negative polyimide precursor was dissolved in N-methylpyrrolidone, the mass fraction of the self-sensitizing negative polyimide precursor in the mixed solution was 10%, and it was completely dissolved by ultrasonic treatment for 1 hour, and the insoluble matter was filtered with a filter membrane with a pore size of 0.45 micron to obtain a uniform solution.

[0115] The obtained solution was applied to a 4-inch silicon wafer by spin coating at a speed of 1000r for 20s, and then dried at 100°C for 3min to obtain a pre-baked silicon wafer assembly with a thickness of 0.68μm. Next, the i-ray (365nm) of a mercury lamp was used to expose it through a mask, and then a developing device was used to develop the film using Na 2 CO 3 The exposed part is removed by the developer (mass fraction is 1%), and a resin pre-baked film with a specific pattern is obtained. Figure 7 As shown, the scanning electron microscope image of the self-sensitizing negative polyimide precursor after photolithography development is as follows Figure 8 As shown, a mask plate containing different slit line widths was used to carry out photolithography testing, and the scanning electron microscope was used to observe the graphic morphologies of different line widths formed after exposure and development. a to d are the morphologies of line widths of 10μm, 20μm, 40μm and 80μm, respectively. It can be seen that the morphology is still good when the line width is reduced to 10μm, and the photoresist resolution is 10μm.

[0116] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. An intermediate of a self-sensitizing negative polyimide precursor, characterized in that: Its structural formula is shown in formula (I):

2. The method for preparing the intermediate of the self-sensitizing negative polyimide precursor according to claim 1, characterized in that: include: (1) 4,4'-dinitro-1,1'-biphenyl-2,2'-dicarboxylic acid reacts with dithionyl chloride to obtain compound 1; (2) dissolving compound 1 in organic solvent 1, adding hydroxyethyl methacrylate, and reacting to obtain compound 2; (3) Compound 2 is dissolved in organic solvent 2, and reacted under the catalysis of iron powder and hydrochloric acid to obtain an intermediate of a self-sensitizing negative polyimide precursor; The structural formula of compound 1 is shown in formula (II): The structural formula of compound 2 is shown in formula (III):

3. The preparation method according to claim 2, characterized in that: The reaction of step (1) is carried out under inert gas conditions; Or, in step (1), the molar ratio of 4,4'-dinitro-1,1'-biphenyl-2,2'-dicarboxylic acid to thionyl chloride is 1:(95-133); Alternatively, in step (1), the reaction temperature is 75 to 90° C. and the reaction time is 1.5 to 3 h.

4. The preparation method according to claim 3, characterized in that: In step (1), the molar ratio of 4,4'-dinitro-1,1'-biphenyl-2,2'-dicarboxylic acid to thionyl chloride is 1:133; In step (1), the reaction temperature is 80° C. and the reaction time is 2 h.

5. The preparation method according to claim 2, characterized in that: In step (2), compound 1 is dissolved in organic solvent 1, hydroxyethyl methacrylate is added, and the mixture is reacted under the catalysis of pyridine to obtain compound 2; The organic solvent 1 comprises acetone; The molar ratio of compound 1 to hydroxyethyl methacrylate is 1:(2-3); The molar ratio of compound 1 to pyridine is 1:(1-2); The reaction temperature is 95-105°C; the reaction time is 2-5h.

6. The preparation method according to claim 5, characterized in that: The molar ratio of compound 1 to hydroxyethyl methacrylate is 1:2; The molar ratio of compound 1 to pyridine is 1:1; The reaction temperature was 100°C.

7. The preparation method according to claim 2, characterized in that: In step (3), The organic solvent 2 comprises a mixed solution of isopropanol and water, wherein the volume ratio of the isopropanol to water is 3.5 to 5:1; The molar ratio of compound 2 to iron powder is 1:8-12; The molar ratio of compound 2 to hydrochloric acid is 6 to 10:1; The reaction temperature is 95-105°C; the reaction time is 1-3h.

8. The preparation method according to claim 7, characterized in that: The volume ratio of isopropanol to water is 4:1; The molar ratio of compound 2 to iron powder is 1:10; The molar ratio of compound 2 to hydrochloric acid is 8.3:1; The reaction temperature was 100°C.

9. Use of the intermediate of the self-sensitizing negative polyimide precursor according to claim 1 in the synthesis of a self-sensitizing negative polyimide precursor.

10. A self-sensitizing negative polyimide precursor, characterized in that: The self-sensitizing negative polyimide precursor is obtained by polymerizing the intermediate of the self-sensitizing negative polyimide precursor according to claim 1 with 3,3',4,4'-dibenzophenone tetracarboxylic dianhydride; wherein the molar ratio of the intermediate of the self-sensitizing negative polyimide precursor to 3,3',4,4'-dibenzophenone tetracarboxylic dianhydride is 0.8 to 1.2:1, the reaction conditions are stirring reaction at room temperature, and the reaction time is 18 to 26 hours.

11. The self-sensitizing negative polyimide precursor according to claim 10, characterized in that: The self-sensitizing negative polyimide precursor is obtained by polymerizing the intermediate of the self-sensitizing negative polyimide precursor and 3,3',4,4'-dibenzophenone tetracarboxylic dianhydride in an organic solvent under an inert gas atmosphere; The organic solvent includes N-methylpyrrolidone; Or, the molar ratio of the intermediate of the self-sensitizing negative polyimide precursor to 3,3',4,4'-benzophenone tetracarboxylic dianhydride is 1:1; Or, the reaction time is 20h.

12. The method for preparing the self-sensitizing negative polyimide precursor according to claim 10, characterized in that: The method comprises stirring the intermediate of the self-sensitizing negative polyimide precursor according to claim 1 and 3,3',4,4'-dibenzophenone tetracarboxylic dianhydride at room temperature to obtain a self-sensitizing negative polyimide precursor; Wherein, the molar ratio of the intermediate of the self-sensitizing negative polyimide precursor to 3,3',4,4'-dibenzophenone tetracarboxylic dianhydride is 0.8 to 1.2:1; The stirring reaction time at room temperature is 18 to 26 hours.

13. Use of the self-sensitizing negative polyimide precursor according to claim 10 in preparing negative photoresist.

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