A photolithography method for improving the resolution of positive photoresist thick films

Abstract

The invention discloses a photolithography method for improving the resolution of a thick film of a positive photoresist, and belongs to the technical field of photoresist exposure and development process. The process is based on improving the resolution of thick film (>20 μm) photoresist, by adding a dissolving agent during the exposure and development process to inhibit the dissolution of the unexposed area, thereby enhancing the dissolution contrast between the exposed area and the unexposed area, and then combining the process of multiple exposure / multiple development. The method can reduce the exposure time, reduce the film thickness loss, and improve the film retention rate and pattern resolution.

Description

Technical Field

[0001] The invention belongs to the technical field of photoresist development process, and in particular relates to a photolithography method for improving the resolution of a positive photoresist thick film. Background Art

[0002] The photolithography process is the most important step in the entire microelectronic integrated circuit manufacturing process. The photolithography process mainly includes: photoresist coating, pre-baking, exposure, development and other process flows. As the wafer size increases and the requirements for the resolution of the photolithography pattern increase, higher requirements are placed on the development process.

[0003] In the era of rapid development of 5G and 6G communications, the number of electronic components carried by mobile terminals such as electronic devices is increasing due to the need for high-speed and large-capacity data communications. At the same time, more sophisticated processing requirements are put forward for photosensitive coating liquid materials used in the insulating layer of electronic components. Positive photosensitive polybenzoxazole (PSPBO) and positive photosensitive polyimide (PSPI) coating materials with good lithography resolution and excellent thermal and mechanical properties are widely used in the insulating layer.

[0004] Due to the reason of light transmittance, when the thickness increases to more than 20 μm, the UV light transmittance will decrease, so that fine processing can no longer be carried out. In order to obtain patterns with higher resolution, many experimental researchers adopt the method of increasing exposure time and developing time, resulting in extremely high exposure energy of positive photoresist thick film. In addition, when the photoresist is too thick, it is difficult to contact the developer below the exposed photoresist. If you want to obtain a complete photolithography pattern, you need to increase the long developing time, which leads to a large loss of film thickness and a very low film retention rate (40-60%). Using this method at the same time seriously reduces the life of the light source of the exposure machine, which is not suitable for industrial mass production. Therefore, the photolithography process for thick film has always been an important direction that needs to be overcome in this field. Summary of the invention

[0005] In order to overcome the above-mentioned deficiencies in the prior art, the object of the present invention is to provide a lithography method for improving the resolution of positive photoresist thick films, which can reduce exposure time, reduce film thickness loss, and improve film retention rate and pattern resolution.

[0006] In order to achieve the above object, the technical solution adopted by the present invention is as follows:

[0007] A photolithography method for improving the resolution of a positive photoresist thick film adopts a process method of multiple exposures, development combined with adding a solvent inhibitor to obtain a thick film pattern with high resolution.

[0008] The photolithography method for improving the resolution of a positive photoresist thick film provided by the present invention specifically comprises the following steps:

[0009] 1) Spreading: coating the positive photoresist liquid on the wafer, spreading the photoresist, pre-baking, and obtaining a positive photoresist thick film;

[0010] 2) Exposure: Exposure is performed using a 1 / n film thickness exposure process, where n represents the number of repeated exposures;

[0011] 3) Development: Developing is performed using a 1 / n film thickness development process to obtain a photolithography pattern after the first exposure and development, where n represents the number of repeated exposures;

[0012] 4) Spraying solvent: spray a layer of solvent on the surface of the wafer at a suitable speed and bake;

[0013] 5) Continue to repeat the above exposure, development, and resist solvent spraying steps on the wafer (the last exposure and development does not require resist solvent spraying) until the final photolithography pattern is obtained.

[0014] In step 1) of the above method, the positive photoresist solution is a positive photosensitive polybenzoxazole (PSPBO) resin composition glue solution and / or a positive photosensitive polyimide (PSPI) resin composition glue solution;

[0015] The viscosity of the positive photoresist liquid is preferably above 5000 cP;

[0016] The glue spreading is achieved by using a glue spreading unit of a 12-inch Track device;

[0017] The glue spinning speed can be 1000rpm*30s-3000rpm*30s;

[0018] The pre-baking is carried out on a constant temperature hot bench;

[0019] The pre-baking temperature can be 110-120°C and the time can be 3-5 minutes;

[0020] The thickness of the obtained thick film is above 20 μm, and can be specifically 30 μm;

[0021] In step 2), the exposure equipment may be a 12-inch photolithography machine Canon FPA-5520iV;

[0022] The exposure energy of the exposure can be 300mj-2000mj / cm 2 , specifically 600-1500mj / cm 2 、600-1000mj / cm 2 、800mj / cm 2 or 900mj / cm 2 ; No requirements for exposure masks;

[0023] In step 3), the development is performed using a development unit of a 12-inch Track device;

[0024] The development operation is as follows: maintaining the wafer rotation speed at 200-500rpm (specifically 300rpm), spraying the developer for 5-13s, at which time the wafer surface is full of the developer, and the static development time is 50-300s; then spraying deionized water to remove residues, and drying the wafer at a rotation speed of 2000-3000rpm;

[0025] The developer may be a 2.38% TMAH alkaline developer (purchased from Suzhou Ruicai Semiconductor Co., Ltd.);

[0026] The operation of step 4) is: reduce the rotation speed to 200-500 rpm, use a nozzle containing a solvent inhibitor to evenly spray from one side of the wafer to the other side of the wafer for 5-10 seconds, and then place the wafer in a constant temperature hot plate for baking.

[0027] The baking temperature is consistent with the pre-baking temperature (110-120°C), and the baking time can be 20-50s;

[0028] The dissolution inhibitor is prepared by dissolving a diazonaphthoquinone sulfonate compound in an organic solvent;

[0029] Among them, the diazonaphthoquinone sulfonate compounds include but are not limited to the following compounds: 2,3,4-trihydroxybenzophenone 1,2-diazide naphthoquinone-5-sulfonate, 2,3,4,4'-tetrahydroxybenzophenone 1,2-diazide naphthoquinone-5-sulfonate, 2,3,4-trihydroxybenzophenone-2,1,4-diazide naphthoquinone sulfonate, 2,3,4,4'-tetrahydroxybenzophenone-2,1,4-diazide naphthoquinone sulfonate, etc.

[0030] The organic solvent is consistent with the solvent used to prepare the glue solution in step 1).

[0031] In the dissolution inhibitor, the mass concentration of the diazonaphthoquinone sulfonate compound is 30%-90%.

[0032] The photoresist thick film prepared by the above method also belongs to the protection scope of the present invention.

[0033] The film retention rate of the photoresist thick film is greater than 75%, and the pattern resolution is less than or equal to 10 μm.

[0034] The present invention sprays a blocking solvent after each development to prevent the loss of film thickness caused by repeated development. The addition of the blocking solvent can reduce the solubility of the photoresist in the developer in the unexposed area, while not affecting the exposure reaction of the exposed area. In the process of multiple exposure and development (number n≥2) of the present invention, the exposure and development process selects the optimal process conditions when the film thickness is 1 / n.

[0035] In order to better describe the above preparation method, the examples and drawings in the present invention are all illustrated by taking development n=3 times as an example. In addition, the photosensitive resin composition used in the present invention is as follows. It should be noted that the resin precursors and additives used in the present invention are selected to better introduce the technology in the present invention. Therefore, the technology of the present invention is not limited to the following resin compositions and additives.

[0036] A positive photosensitive resin composition: containing (A) a polyhydroxyamide containing a polybenzoxazole precursor, (B) a photosensitizer, (C) an acid generator, (D) a crosslinking agent, (E) a coupling agent, and (F) an organic solvent. The resin composition comprises 100 parts by mass of a positive photosensitive polyhydroxyamide resin, 1-50 parts by mass of a photosensitizer, 1-30 parts by mass of an acid generator, 1-50 parts by mass of a crosslinking agent, 1-30 parts by mass of a coupling agent, and 100-1000 parts by mass of an organic solvent.

[0037] (A) Polyhydroxyamide with polybenzoxazole precursor: synthesized from dicarboxylic acids and diamines, the present invention does not require its specific structure. The following general structural formula (1) can be cited: Y is preferably -O-, a divalent organic group, or a fluorine-containing group, and X is preferably an aromatic structural group. The hydroxyl group and amide group bonded to the same benzene ring in the structural unit are converted into an oxazole ring by heating and dehydration ring closure.

[0038]

[0039] (B) Photosensitizer: The present invention does not limit the type of photosensitizer, but preferably uses a photoacid generator that generates acid under the action of light, and preferably uses a diazonaphthoquinone ester type compound. For example: 2,3,4-trihydroxybenzophenone-1,2-diazonaphthoquinone-5-sulfonate, 2,3,4,4-tetrahydroxybenzophenone-1,2-naphthoquinonediazide-5-sulfonate, 2,3,4-trihydroxybenzophenone-2,1,4-diazonaphthoquinone sulfonate, 2,3,4,4'-tetrahydroxybenzophenone-2,1,4-diazonaphthoquinone sulfonate, etc.

[0040] (C) Acid generator: The present invention does not limit the type of acid generator, but preferably uses aromatic group-containing sulfonic acids such as p-toluenesulfonic acid and benzenesulfonic acid. Studies have shown that these acids act as effective catalysts in the dehydration reaction of polyhydroxyamide structures.

[0041] (D) Crosslinking agent: The component is not particularly limited as long as it is a compound that is crosslinked or polymerized in the heat treatment step, and is preferably a compound having an alkoxyalkyl group such as a hydroxymethyl group or an alkoxymethyl group, an epoxy group, an oxetane group, or a vinyl ether group. Examples thereof include 4,4'-(1-phenylethylene)bis[2,6-bis(hydroxymethyl)phenol], 1,3,4,6-tetrakis(methoxymethyl)glycoluril, 4,4'-methylenebis(2-methyl-6-hydroxymethylphenol), and 2,2-bis(4-glycidyloxyphenyl)propane.

[0042] (E) Coupling agent: There is no limitation on the type of coupling agent, and conventional binders in the art may be used as long as the purpose of the present invention can be achieved, for example: γ-aminopropyltrimethoxysilane, γ-aminopropyltriethoxysilane, γ-glycidyloxypropyltrimethoxysilane, γ-glycidyloxypropyltriethoxysilane, 3-ureidopropyltrimethoxysilane, 3-ureidopropyltriethoxysilane, 3-isocyanatetrimethoxysilane, 3-isocyanatetriethoxysilane, 3-mercaptopropyltrimethoxysilane, 3-mercaptopropyltriethoxysilane, etc.

[0043] (F) Organic solvent: The present application does not limit the type of organic solvent, and conventional organic solvents in the art can be used as long as the purpose of the present invention can be achieved. The organic solvent can be selected from at least one of N-methylpyrrolidone, N,N'-dimethylacetamide, N,N'-dimethylformamide, γ-butyrolactone, ethyl acetate, butyl acetate, n-propyl acetate, methyl lactate, ethyl lactate, propyl lactate, butyl lactate, diacetone alcohol, ethylene glycol monomethyl ether acetate, ethylene glycol monoethyl ether acetate, propylene glycol monomethyl ether, propylene alcohol monoethyl ether, and propylene glycol monomethyl ether acetate. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] Figure 1 A schematic diagram of the developing unit used in the process of the present invention is given. A 12-inch wafer is placed on a wafer stage, and a program can be set to rotate the wafer. Each nozzle can translate over the wafer and spray the corresponding solution.

[0045] Figure 2 A schematic diagram of photoresist exposure and development during the specific implementation process is given. DETAILED DESCRIPTION

[0046] The present invention is further described in detail below in conjunction with specific embodiments, and the examples provided are only for illustrating the present invention, rather than for limiting the scope of the present invention. The examples provided below can be used as a guide for further improvements by those of ordinary skill in the art, and do not constitute a limitation of the present invention in any way.

[0047] The experimental methods in the following examples, unless otherwise specified, are all conventional methods, and are performed according to the techniques or conditions described in the literature in the field or according to the product instructions. The materials, reagents, etc. used in the following examples, unless otherwise specified, can all be obtained from commercial channels.

[0048] Embodiment 1,

[0049] The specific implementation steps are as follows:

[0050] Step 1: Place 170 g of N-methylpyrrolidone in a 1L flask equipped with a stirrer, a thermometer, and a nitrogen protection device, add 25.10 g of 2,2-bis(3-amino-4-hydroxyphenyl)propane, and stir to dissolve. Then, cool the mixed diamine solution to below 10°C using an ice-water bath, add 30.3 g of 4,4'-diacyl chloride diphenyl ether dropwise over 20 minutes, and continue stirring the solution in the flask for 6 hours. Pour the above solution into 5 liters of water, recover the precipitate, wash it 3 times with pure water, filter it, and vacuum dry it to obtain a polyhydroxyamide solid resin (referred to as polymer I).

[0051] In a Class 1000 clean room equipped with a yellow light, in a 500 ml flask equipped with a stirrer and a nitrogen protection device, 50 g of the above polymer I, 7.5 g of 2,3,4-trihydroxybenzophenone-1,2-diazonaphthoquinone-5-sulfonate, 2 g of p-toluenesulfonic acid, 2.5 g of 1,3,4,6-tetrakis(methoxymethyl)glycoluril, and 3 g of 3-isocyanatetrimethoxysilane were added to 73 g of γ-butyrolactone in sequence, and stirred at room temperature for 6 h to form a homogeneous positive photosensitive polyhydroxyamide resin composition glue.

[0052] Step 2: Use a coating machine with a main speed of 1500rpm*30s to coat the glue on a 12-inch wafer, bake it in a constant temperature hot plate at 120℃ for 4 minutes, and use a Nanospec film thickness meter to measure the film thickness to be 30μm.

[0053] Step 3: Use the glue obtained in the first step, change the main speed of the glue spreading machine to 5500rpm*30s, bake it in a constant temperature hot plate at 120℃ for 3min, measure and obtain a 10μm glue film, do multiple groups of exposure and development comparison experiments, and get the best process conditions: Exposure energy: 800-1000mj / cm 2 , development time 60s, film retention rate 80%, graphic resolution ≤10μm.

[0054] Step 4: For the 30μm thick film obtained in step 2, use 800-1000mj / cm 2After exposure with exposure energy of 1000 rpm, the 12-inch wafer with photoresist film is placed in the developing unit, the wafer is rotated at 300 rpm, and alkaline developer (2.38% TMAH) is sprayed for 10 seconds to make the wafer surface completely covered with developer, and the static development time is 60 seconds; then deionized water is sprayed to remove the residual developer and reaction residues, and the rotation speed is increased to 3000 rpm to spin dry the wafer to obtain the pattern corresponding to Figure 2 Schematic diagram of the photolithography pattern after the first exposure and development.

[0055] Step 5: Keep the wafer rotation speed at 300 rpm, spray a layer of solvent inhibitor (2,3,4-trihydroxybenzophenone-1,2-diazonaphthoquinone-5-sulfonate 40wt%, γ-butyrolactone as solvent) on the surface of the wafer for 8 seconds, and bake in a constant temperature hot plate at 110°C for 30 seconds.

[0056] Step 6: Repeat the exposure, development and spraying of solvent in steps 4 and 5 to obtain the corresponding pattern. Figure 2 The pattern after the second exposure in the schematic diagram.

[0057] Step 7: Repeat the exposure and development method in step 4 to obtain the corresponding pattern Figure 2 The pattern after the third exposure in the schematic diagram.

[0058] The best photolithography conditions for the 30 μm thick film obtained in Example 1 are: exposure energy 900 mj / cm 2 , development time 60s, film retention rate > 75%, graphic resolution ≤ 10μm.

[0059] Embodiment 2,

[0060] The specific implementation steps are as follows:

[0061] Step 1: Place 185g of N-methylpyrrolidone in a 1L flask equipped with a stirrer, a thermometer, and a nitrogen protection device, add 36.23g of 2,2-bis(3-amino-4-hydroxyphenyl)hexafluoropropane, and stir to dissolve. Then, cool the mixed diamine solution to below 10°C in an ice-water bath, add 30.3g of 4,4'-diacyl chloride diphenyl ether dropwise over 20 minutes, and continue to stir the solution in the flask for 6 hours. Pour the above solution into 5 liters of water, recover the precipitate, wash it 3 times with pure water, filter it, and vacuum dry it to obtain a polyhydroxyamide solid resin (referred to as polymer II).

[0062] In a Class 1000 clean room equipped with a yellow light, in a 500 ml flask equipped with a stirrer and a nitrogen protection device, 50 g of the above polymer II, 10 g of 2,3,4-trihydroxybenzophenone-1,2-diazonaphthoquinone-5-sulfonate, 2.5 g of p-toluenesulfonic acid, 4 g of 1,3,4,6-tetrakis(methoxymethyl)glycoluril, and 2 g of 3-isocyanatetrimethoxysilane were added to 75 g of γ-butyrolactone in sequence, and stirred at room temperature for 6 h to form a homogeneous positive photosensitive polyhydroxyamide resin composition glue.

[0063] Step 2: Use a coating machine with a main speed of 1500rpm*30s to coat the glue on a 12-inch wafer, bake it in a constant temperature hot plate at 120℃ for 4 minutes, and use a Nanospec film thickness meter to measure the film thickness to be 30μm.

[0064] Step 3: Use the glue obtained in the first step, change the main speed of the glue spreading machine to 5500rpm*30s, bake in a constant temperature hot plate at 120℃ for 3min, measure and obtain a 10μm glue film, do multiple exposure and development comparison experiments, and get the best process conditions: Exposure energy: 700-900mj / cm 2 , development time 60s, film retention rate > 75%, graphic resolution < 10μm.

[0065] Step 4: For the 30μm thick film obtained in step 2, use 700-900mj / cm 2 After exposure with exposure energy of 1000 rpm, the 12-inch wafer with photoresist film is placed in the developing unit, the wafer is rotated at 300 rpm, and alkaline developer (2.38 TMAH) is sprayed for 10 seconds to make the wafer surface completely covered with developer, and the static development time is 60 seconds; then deionized water is sprayed to remove residual developer and reaction residues, and the rotation speed is increased to 3000 rpm to spin dry the wafer to obtain the pattern corresponding to Figure 2 Schematic diagram of the photolithography pattern after the first exposure and development.

[0066] Step 5: Keep the wafer rotation speed at 300 rpm, spray a layer of solvent inhibitor (40% 2,3,4-trihydroxybenzophenone-1,2-diazonaphthoquinone-5-sulfonate, γ-butyrolactone as solvent) on the surface of the wafer for 8 seconds, and bake in a constant temperature hot plate at 110°C for 30 seconds.

[0067] Step 6: Repeat the exposure, development and spraying of solvent in steps 4 and 5 to obtain the corresponding pattern. Figure 2 The pattern after the second exposure in the schematic diagram.

[0068] Step 7: Repeat the exposure and development method in step 4 to obtain the corresponding pattern Figure 2 The pattern after the third exposure in the schematic diagram.

[0069] The best photolithography conditions for obtaining a 30 μm thick film in Example 2 are: exposure energy 800 mj, development time 60 s, film retention rate > 70%, and graphic resolution ≤ 10 μm.

[0070] Comparative Example 1

[0071] Step 1 and Step 2: Repeat Step 1 and Step 2 in Example 1, using the same glue solution, the same glue leveling and pre-baking conditions to obtain a 30 μm thick film.

[0072] Step 3: The 30μm thick film obtained in step 2 is exposed using the same exposure machine with an exposure energy of 3000-5000mj / cm 2 Then, the exposed 12-inch wafer was placed in the developing unit, and the alkaline developer (2.38% TMAH) was sprayed for 10 seconds while the rotation speed was maintained at 300 rpm, and the static development time was 180-300 seconds. Deionized water was then sprayed to remove the residual developer and reaction residues, and the wafer was dried at a rotation speed of 3000 rpm to obtain the photolithography pattern.

[0073] Table 1: Comparison of different photolithography process results in Comparative Example 1

[0074] Test 1 Test 2 Test 3 Test 4 Test 5 <![CDATA[Exposure energy (mj / cm 2 )]]> 3000 4000 4500 5000 5000 Development time(s) 300 240 240 240 200 Film retention rate (%) 38 50 48 45 59 Resolution(μm) / / ≥20 ≥10 ≥10

[0075] Note: “ / ” in the table means: no pattern is photolithographically formed after development, and development is incomplete.

[0076] The third step is to expose and develop the film. The results are shown in Table 1. As can be seen from the table, Experiment 4 and Experiment 5 can obtain a photolithography pattern with a resolution of 10 μm. The best condition is Experiment 5: the development time is 200 s, the film retention rate is low (59%), but a high exposure energy of 5000 mj / cm is required. 2 .

[0077] The best photolithography conditions for obtaining a 30 μm thick film in Comparative Example 1 are: exposure energy 5000 mj, development time 200-240 s, film retention rate <60%, and graphic resolution ≥10 μm.

[0078] Comparative Example 2

[0079] Step 1 and Step 2: Repeat Step 1 and Step 2 in Example 2, using the same glue solution, the same glue leveling and pre-baking conditions to obtain a 30 μm thick film.

[0080] Step 3: The 30μm thick film obtained in step 2 is exposed using the same exposure machine with an exposure energy of 3000-5000mj / cm 2Then, the exposed 12-inch wafer is placed in the developing unit, and the alkaline developer is sprayed for 10 seconds while the rotation speed is maintained at 300 rpm, and the static development time is 180-300 seconds. Deionized water is then sprayed to remove the residual developer and reaction residues, and the wafer is dried at a rotation speed of 3000 rpm to obtain the photolithography pattern.

[0081] Table 2: Comparison of different photolithography process results in comparative example 2

[0082] Test 1 Test 2 Test 3 Test 4 Test 5 <![CDATA[Exposure energy (mj / cm 2 )]]> 3000 4000 4000 4500 5000 Development time(s) 300 300 240 240 180 Film retention rate (%) 30 28 42 39 52 Resolution(μm) / ≥40 / ≥10 ≥10

[0083] Note: “ / ” in the table means: no pattern is photolithographically formed after development, and development is incomplete.

[0084] The third step is to expose and develop the film. The following experiments are shown in Table 2. It can be seen from the table that experiments 4 and 5 can obtain a photolithography pattern with a resolution of 10 μm. The lower exposure energy is preferred to obtain the best condition. Experiment 4: The exposure energy is about 4500 mj / cm 2 , development time 240s, film retention rate is very low 39%; shorter development time is preferred to obtain the best condition test 5: development time 180s, film retention rate is low 52%, but requires a very high exposure energy of 5000mj / cm 2 .

[0085] The best photolithography conditions for obtaining a 30 μm thick film in Comparative Example 2 are: exposure energy 4500-5000 mj, development time 180-240 s, film retention rate ≤52%, and graphic resolution ≥10 μm.

[0086] By comparing the data of the embodiment and the comparative example, it is concluded that by utilizing the exposure and development process of the present invention, a higher resolution photolithography pattern can be obtained even with lower exposure energy and less development time, and the film retention rate is higher.

[0087] Comparative Example 3

[0088] The first to third steps in Example 1 were repeated.

[0089] Step 4: For the 30μm thick film obtained in step 2, use 800-1000mj / cm 2 After exposure with exposure energy of ; then place the 12-inch wafer with photoresist film in the developing unit, rotate the wafer at 300rpm, spray 2.38% TMAH alkaline developer for 10s, so that the wafer surface is completely covered with developer, and the static development time is 60s; then spray deionized water to remove residual developer and reaction residues, increase the rotation speed to 3000rpm to spin dry the wafer.

[0090] Step 5: Repeat the exposure and development method in step 4 for the wafer to obtain a pattern after the second exposure and development.

[0091] Step 6: Repeat the exposure and development method in step 4 to obtain the pattern after the third exposure and development.

[0092] The best photolithography conditions for obtaining a 30 μm thick film in Comparative Example 3 are: exposure energy 800-1000 mj / cm 2 , development time 60s, film retention rate > 60%, graphic resolution ≤ 10μm.

[0093] The present invention has been described in detail above. For those skilled in the art, without departing from the purpose and scope of the present invention, and without the need to carry out unnecessary experimental conditions, the present invention can be implemented in a wide range under equivalent parameters, concentrations and conditions. Although the present invention provides specific embodiments, it should be understood that the present invention can be further improved. In a word, according to the principles of the present invention, the application is intended to include any changes, uses or improvements to the present invention, including departure from the disclosed scope in the application, and changes made with conventional techniques known in the art.

Claims

1. A photolithography method for improving the resolution of a positive photoresist thick film, characterized in that: The photolithography method comprises the following steps: 1) Spreading: Coating positive photoresist liquid on the wafer, spreading the photoresist, pre-baking, and obtaining a positive photoresist thick film; The thickness of the obtained thick film is above 20 μm; 2) Exposure: Exposure is performed using an exposure process of 1 / n film thickness, where n represents the number of repeated exposures; 3) Development: Use a 1 / n film thickness development process to develop and obtain the photolithography pattern after the first exposure and development, where n represents the number of repeated exposures; 4) Spraying solvent: spray a layer of solvent on the surface of the wafer at a suitable speed and bake; 5) Repeat the above exposure, development, and resist solvent spraying steps on the wafer until the final photolithography pattern is obtained. The last exposure and development does not require resist solvent spraying; The dissolution inhibitor is prepared by dissolving a diazonaphthoquinone sulfonate compound in an organic solvent.

2. The method according to claim 1, characterized in that: In step 1), the positive photoresist solution is a positive photosensitive polybenzoxazole resin composition glue solution and / or a positive photosensitive polyimide resin composition glue solution; The viscosity of the positive photoresist liquid is above 5000 cP; The rotation speed of the glue spinning is 1000rpm*30s-3000rpm*30s; The pre-baking temperature is 110-120° C. and the time is 3-5 minutes.

3. The method according to claim 1 or 2, characterized in that: The exposure energy of the exposure is 300mj-2000mj / cm 2 .

4. The method according to claim 1 or 2, characterized in that: The development operation is as follows: maintaining the wafer rotation speed at 200-500 rpm, spraying the developer for 5-13 seconds, and static development time for 50-300 seconds; then spraying deionized water to remove residues, and drying the wafer at a rotation speed of 2000-3000 rpm; The developer is a 2.38% TMAH alkaline developer.

5. The method according to claim 1 or 2, characterized in that: The operation of step 4) is: setting the rotation speed to 200-500 rpm, spraying the solvent-blocking agent from one side of the wafer to the other side of the wafer with a nozzle for 5-10 seconds, and then baking the wafer; The baking temperature is 110-120° C., and the baking time is 20-50 seconds.

6. The method according to claim 1 or 2, characterized in that: The naphthoquinone diazosulfonate compound may specifically be: 2,3,4-trihydroxybenzophenone 1,2-diazide naphthoquinone-5-sulfonate, 2,3,4,4'-tetrahydroxybenzophenone 1,2-diazide naphthoquinone-5-sulfonate, 2,3,4-trihydroxybenzophenone-2,1,4-diazide naphthoquinone sulfonate, 2,3,4,4'-tetrahydroxybenzophenone-2,1,4-diazide naphthoquinone sulfonate, or a mixture of several thereof; In the dissolution inhibitor, the mass concentration of the diazonaphthoquinone sulfonate compound is 30%-90%.

7. A photoresist thick film obtained by the method according to any one of claims 1 to 6.

8. The photoresist thick film according to claim 7, characterized in that: The film retention rate of the photoresist thick film is greater than 75%, and the graphic resolution is less than or equal to 10 μm.

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