Photoresist coating method

Abstract

The invention relates to a photoresist coating method, and belongs to the technical field of semiconductors. The coating method comprises the following steps: S1, coating the surface of a silicon wafer with a slow release agent to form a protective layer; s2, coating liquid is sprayed on the surface of the protective layer, and a first photoresist layer and a second photoresist layer are formed in sequence; the coating liquid is obtained by diluting photoresist with a diluent and carrying out centrifugal degassing; the thickness of the first photoresist layer is 0.1 mu m to 0.2 mu m, and the thickness of the second photoresist layer is 1 mu m to 5 mu m; and S3, the sprayed silicon wafer is dried in stages, and coating is completed. The coating method provided by the invention can effectively improve the surface bubbles frequently appearing in the photoresist coating thick film, and improve the uniformity and surface cleanliness of the photoresist after coating.

Description

Technical Field

[0001] The invention belongs to the technical field of semiconductors, and in particular relates to a photoresist coating method. Background Art

[0002] Photolithography is a key process step in the semiconductor production process. The minimum line width that a photolithography machine can achieve will directly determine the performance and cost of the chip. In order to reduce production costs, photolithography engineers are constantly working to reduce the line width. At present, the process node that can be reached is 7nm and below. In order to meet this process node and try to continue to reduce the line width, it is necessary to ensure the uniformity and surface cleanliness of the photoresist after coating in the patterning process.

[0003] In the past semiconductor processes, the most common method is to coat thin films with a thickness of less than 1μm. In the field of solar cell manufacturing, in order to improve the subsequent process effect, attempts are made to coat adhesive films with a thickness of 10μm-25μm. However, during the photoresist coating process, in addition to the bubbles inside the adhesive, the adhesive itself is prone to produce a large number of bubbles during the coating process. This problem is not obvious during the thin film coating process, but during the thick film coating process, the problem worsens, resulting in a large number of bubbles remaining on the surface of the silicon wafer, affecting the uniformity and surface cleanliness of the photoresist after coating, and further affecting the subsequent photolithography effect.

[0004] Therefore, how to alleviate the large amount of bubbles remaining on the surface of the silicon wafer during the coating process is an urgent problem to be solved. Summary of the invention

[0005] In order to solve the above technical problems, the present invention provides a photoresist coating method, which comprises the following steps: diluting the photoresist with a diluent, and then centrifugally degassing the diluted photoresist with a centrifuge to obtain a coating liquid; coating a sustained-release agent solution on the surface of a silicon wafer to form a protective layer; then spraying the coating liquid on the surface of the silicon wafer with a coating machine to form a thin photoresist layer and a thick photoresist layer, and finally drying the sprayed silicon wafer in stages to obtain a photoresist film layer with good uniformity, no defects and a clean surface.

[0006] The object of the present invention is to provide a method for coating a photoresist, comprising the following steps:

[0007] S1, coating the sustained-release agent on the surface of the silicon wafer to form a protective layer;

[0008] S2, spraying a coating liquid on the surface of the protective layer to sequentially form a first photoresist layer and a second photoresist layer; the coating liquid is obtained by diluting the photoresist with a diluent and degassing by centrifugation; the thickness of the first photoresist layer is 0.1 μm-0.2 μm, and the thickness of the second photoresist layer is 1 μm-5 μm;

[0009] S3. Dry the sprayed silicon wafer in stages to complete the coating; the staged drying includes two stages, the first stage is to keep warm at 30℃-50℃ for 1min-2min; the second stage is to keep warm at 90℃-110℃ for 3min-5min; the staged drying method can prevent the diluent of the photoresist from generating voids when it is separated from the photoresist film layer, thereby affecting the surface morphology of the dried film and affecting the subsequent exposure process, thereby improving the coating process effect.

[0010] In one embodiment of the present invention, in S1, the sustained-release agent is selected from one or more of mercaptobenzothiazole, benzotriazole, methylbenzotriazole, propylene glycol monomethyl ether and propylene glycol monomethyl ether acetate. The sustained-release agent is spread on the surface of the silicon wafer to form a wetting film, which increases the wettability of the substrate surface while protecting the copper seed layer on the substrate surface, improving the wetting effect of the photoresist on the silicon wafer surface, and helping to eliminate bubbles inside the photoresist.

[0011] In one embodiment of the present invention, in S2, the photoresist comprises, by weight: 30-60 parts of a binder polymer, 10-45 parts of a photoreactive monomer, and 1-5 parts of a photoinitiator; the binder polymer is obtained by free radical polymerization of acrylic acid, isoprene, methacrylic acid, hexafluoroisopropyl methacrylate, and glycidyl methyl isopropylate in the presence of an initiator and a solvent; the molar ratio of the acrylic acid, isoprene, methacrylic acid, hexafluoroisopropyl methacrylate, and glycidyl methyl isopropylate is 1:(1-1.2):(0.8-1.1):(0.9-1.1):(1-1.2), and the weight average molecular weight of the binder polymer is greater than 6000. This photoresist is suitable for solar cell glue and is easy to coat. After development, the morphology steepness of the photoresist can reach more than 80°, and the later film removal effect is good, which is beneficial to the preparation of solar cells.

[0012] Further, the photoreactive monomer is selected from one or more of methyl acrylate, ethyl acrylate, propyl acrylate, butyl acrylate, pentyl acrylate, hexyl acrylate, 2-hydroxymethyl acrylate, 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate and 2-hydroxybutyl acrylate.

[0013] The photoinitiator and the initiator are independently selected from one or more of benzoin compounds, benzoin ether compounds, benzophenone compounds, Michler's ketone compounds, acetophenone compounds, acridine compounds, anthraquinone compounds, ketal compounds, organic halide compounds, diazonaphthoquinone compounds, organic peroxide compounds, thiol compounds, thiazolone compounds, phenylphosphine oxide compounds, hexaarylimidazole compounds, coumarin compounds, oxazole compounds, pyrazoline compounds and triarylamine compounds;

[0014] The solvent is selected from one or more of methanol, ethanol, propanol, butanol, acetone, butanone, N-methyl 2-pyrrolidone, methyl ethyl ketone, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monopropyl ether, ethylene glycol monobutyl ether, toluene, N,N'-dimethylformamide, propylene glycol monomethyl ether, dimethyl sulfoxide, diethyl sulfoxide, phenol, o-cresol, m-cresol, p-cresol, xylenol, halogenated phenol, catechol, tetrahydrofuran, dioxane, dioxolane, cyclopropylene glycol methyl ether, tetraethylene glycol dimethyl ether, γ-butyrolactone, hexamethyl o-amide, and propylene glycol methyl ether acetate.

[0015] In one embodiment of the present invention, in S2, the diluent is selected from propylene glycol methyl ether acetate and / or acetone; the dilution ratio is 1:(3-7).

[0016] In one embodiment of the present invention, in S2, the viscosity of the photoresist is 500cp-700cp.

[0017] In one embodiment of the present invention, in S2, the viscosity of the coating liquid is 1 cp-20 cp.

[0018] In one embodiment of the present invention, in S2, the dilution is carried out by stirring with a magnetic stirrer at a speed of 200 rpm-500 rpm for 1 min-20 min to ensure that the coating liquid does not stratify under static conditions and has no sediment.

[0019] In one embodiment of the present invention, in S2, the centrifugal degassing is performed by a centrifuge at a speed of 500 rpm-2000 rpm for 1 min-20 min. The centrifugal degassing can eliminate bubbles inside the photoresist and reduce bubbles during the coating process. The speed of the centrifuge should not be too fast to avoid stratification and precipitation of the coating solution.

[0020] In one embodiment of the present invention, in S2, the spraying method is ultrasonic atomization or slit coating; the process parameters of the slit coating are: liquid supply speed is 0.03mL / s-30mL / s, coating speed is 1mm / s-200mm / s, and the gap between the coating head and the substrate is 10μm-100μm.

[0021] Furthermore, the spraying method is ultrasonic atomization, the coating liquid is ultrasonically converted into small liquid particles, and then atomized by a carrier gas to form spray droplets.

[0022] In one embodiment of the present invention, in S2, the ultrasonic atomization process parameters of the first photoresist layer are: frequency of 90kHz-95kHz, power of 8W-10W;

[0023] The ultrasonic atomization process parameters of the second photoresist layer are: frequency of 115kHz-121kHz, power of 12W-16W, and the distributed coating method of thin layer first and thick layer later makes the coating liquid fully level on the surface of the substrate, especially the thin layer coating, which effectively fills the undulating points on the surface of the silicon wafer and improves the flatness of the surface of the substrate silicon wafer, so that the diluted photoresist mixed liquid can be fully leveled during thick layer coating, and the bubbles generated during the coating process are effectively discharged to avoid the bubbles in the mixed liquid from covering the surface of the substrate during the spraying process, and at the same time ensure production efficiency.

[0024] The technical solution of the present invention has the following advantages over the prior art:

[0025] The coating method of the present invention can effectively improve the surface bubbles that often appear in the thick film of photoresist coating, and improve the uniformity and surface cleanliness of the photoresist after coating. By centrifuging the prepared coating liquid, the bubbles in the coating liquid are reduced, the slow-release agent is added, and the substrate surface with good wettability is provided, while the copper seed layer is protected; the coating is first thinly coated and then thickly coated in steps, so that during spraying, the coating liquid can be fully leveled, the uniformity of the film thickness is improved, and the bubbles generated during the coating process are discharged, while taking into account the production efficiency, and avoiding the bubbles in the coating liquid from covering the silicon wafer surface during spraying; the drying process is optimized, so that when the diluent is separated from the photoresist film layer, no voids are generated, which affects the morphology of the silicon wafer and causes the subsequent exposure process to be affected. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] In order to make the content of the present invention more clearly understood, the present invention is further described in detail below according to specific embodiments of the present invention in conjunction with the accompanying drawings, wherein:

[0027] Figure 1 This is an electron microscope image of the silicon wafer surface after coating in Example 1 of the present invention;

[0028] Figure 2 This is an electron microscope image of the silicon wafer surface after coating in Comparative Example 1 of the present invention;

[0029] Figure 3 This is an electron microscope image of the silicon wafer surface after coating in Comparative Example 2 of the present invention;

[0030] Figure 4 This is an electron microscope image of the silicon wafer surface after coating in Comparative Example 3 of the present invention;

[0031] Figure 5 This is an electron microscope image of the silicon wafer surface after coating in Comparative Example 4 of the present invention. DETAILED DESCRIPTION

[0032] The present invention is further described below in conjunction with specific embodiments so that those skilled in the art can better understand the present invention and implement it. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. It should be understood that the specific embodiments are only used to explain the present invention, but the embodiments are not intended to limit the present invention.

[0033] In the present invention, unless otherwise explained, technical and scientific terms used in the present invention have the same meanings as commonly understood by those skilled in the art to which the present invention belongs.

[0034] In the present invention, unless otherwise stated, the term "and / or" used in the present invention includes any and all combinations of one or more of the associated listed items.

[0035] In the present invention, unless otherwise stated, the experimental methods used in the embodiments of the present invention are conventional methods unless otherwise stated, and the materials, reagents, etc. used are all commercially available unless otherwise stated.

[0036] In the present invention, unless otherwise specified, the preparation of the photoresist used in the embodiments of the present invention specifically includes the following steps: adding acrylic acid, isoprene, methacrylic acid, hexafluoroisopropyl methacrylate and glycidyl methacrylate in a molar ratio of 1:1.1:1:1:1.1 to a reactor, adding propylene glycol methyl ether acetate to the reactor, and then adding propylene glycol methyl ether acetate dissolved with azobisisobutyronitrile dropwise to the reactor, stirring and reacting at 80° C. for 8 hours to obtain a binder polymer with a weight average molecular weight of about 7000; subsequently, mixing 49 g of the binder polymer with 15 g of methyl acrylate, 15 g of 2-hydroxymethyl acrylate, 1 g of photoinitiator benzophenone, 4 g of photoinitiator 2,2-dimethoxy-2-phenylacetophenone, 3 g of cross-linking agent ethylene glycol dimethacrylate, 2 g of leveling agent Digo 4100, and 180 g of solvent propylene glycol methyl ether acetate and stirring evenly to obtain a photoresist with a viscosity of about 600 cp.

[0037] Example 1

[0038] The photoresist coating method of this embodiment specifically comprises the following steps:

[0039] S1. Transfer the photoresist and the diluent glycol methyl ether acetate to a beaker in sequence according to a dilution ratio of 1:7, place a magnetic stirrer in the beaker, place the beaker on a magnetic stirrer, start the magnetic stirrer, and stir at a speed of 200 rpm for 3 min to fully mix the liquid in the beaker; then transfer the mixed solution to a centrifuge tube, place the centrifuge tube inside a centrifuge, start the centrifuge, and degas the mixture at a speed of 500 rpm for 3 min to obtain a coating solution with a viscosity of about 1 cp;

[0040] S2. Place the silicon wafer on a spin coater, drop about 2 mL of the sustained-release agent propylene glycol monomethyl ether at the center, start the spin coating, and under the force of rotation, the sustained-release agent is spread on the surface of the silicon wafer to form a protective layer;

[0041] S3, connect the coating liquid to the glue pump pipeline of the coating machine, turn on the nitrogen (nitrogen is used as the carrier gas in the coating process) and the air compressor, start the operating program of the coating machine, and spray the coating liquid on the surface of the protective layer in the order of first coating a thin layer and then coating a thick layer to form a thin photoresist layer and a thick photoresist layer in sequence; wherein, the ultrasonic atomization frequency of the thin layer coating is 93kHz, the power is 9W, the coating liquid is ultrasonically atomized according to the set program, and a thin photoresist layer with a thickness of about 0.15μm is coated on the surface of the protective layer; the ultrasonic atomization frequency of the thick layer coating is 118kHz, the power is 14W, the coating liquid is ultrasonically atomized according to the set program, and a thick photoresist layer with a thickness of about 3μm is coated on the surface of the thin photoresist layer;

[0042] S4. Place the sprayed silicon wafer on a heating plate and dry it in stages from low temperature to high temperature to complete the coating; the low temperature stage is kept at 40°C for 1.5 minutes; the second stage is kept at 100°C for 4 minutes.

[0043] Comparative Example 1

[0044] The method is basically the same as Example 1, except that the protective layer is not prepared, and specifically includes the following steps:

[0045] S1. Transfer the photoresist and the diluent glycol methyl ether acetate to a beaker in sequence according to a dilution ratio of 1:7, place a magnetic stirrer in the beaker, place the beaker on a magnetic stirrer, start the magnetic stirrer, and stir at a speed of 200 rpm for 3 min to fully mix the liquid in the beaker; then transfer the mixed solution to a centrifuge tube, place the centrifuge tube inside a centrifuge, start the centrifuge, and degas the mixture at a speed of 500 rpm for 3 min to obtain a coating solution with a viscosity of about 1 cp;

[0046] S2, connect the above-mentioned coating liquid to the glue pump pipeline of the coating machine, turn on the nitrogen (nitrogen is used as the carrier gas in the coating process) and the air compressor, start the operating program of the coating machine, and spray them on the surface of the silicon wafer in the order of first coating a thin layer and then coating a thick layer to form a thin photoresist layer and a thick photoresist layer in sequence; wherein, the ultrasonic atomization frequency of the thin layer coating is 93kHz, the power is 9W, and the coating liquid is ultrasonically atomized according to the set program, and a thin photoresist layer with a thickness of about 0.15μm is coated on the surface of the silicon wafer; the ultrasonic atomization frequency of the thick layer coating is 118kHz, the power is 14W, and the coating liquid is ultrasonically atomized according to the set program, and a thick photoresist layer with a thickness of about 3μm is coated on the surface of the thin photoresist layer;

[0047] S3. Place the sprayed silicon wafer on a heating plate and dry it in stages from low temperature to high temperature to complete the coating; the low temperature stage is kept at 40°C for 1.5 minutes; the second stage is kept at 100°C for 4 minutes.

[0048] Comparative Example 2

[0049] The method is basically the same as Example 1, except that the thin photoresist layer is not prepared, and specifically includes the following steps:

[0050] S1. Transfer the photoresist and the diluent glycol methyl ether acetate to a beaker in sequence according to a dilution ratio of 1:7, place a magnetic stirrer in the beaker, place the beaker on a magnetic stirrer, start the magnetic stirrer, and stir at a speed of 200 rpm for 3 min to fully mix the liquid in the beaker; then transfer the mixed solution to a centrifuge tube, place the centrifuge tube inside a centrifuge, start the centrifuge, and degas the mixture at a speed of 500 rpm for 3 min to obtain a coating solution with a viscosity of about 1 cp;

[0051] S2. Place the silicon wafer on a spin coater, drop about 2 mL of a sustained-release agent, propylene glycol monomethyl ether, on the center, start the spin coating, and under the force of rotation, the sustained-release agent is spread out on the surface of the silicon wafer to form a protective layer;

[0052] S3, connect the coating liquid to the glue pump pipeline of the coating machine, turn on the nitrogen (nitrogen is used as the carrier gas in the coating process) and the air compressor, start the operating program of the coating machine, the ultrasonic atomization frequency of the photoresist layer is 118kHz, the power is 14W, and the coating liquid is ultrasonically atomized according to the set program to coat a photoresist layer with a thickness of about 3μm on the surface of the protective layer;

[0053] S4. Place the sprayed silicon wafer on a heating plate and dry it in stages from low temperature to high temperature to complete the coating; the low temperature stage is kept at 40°C for 1.5 minutes; the second stage is kept at 100°C for 4 minutes.

[0054] Comparative Example 3

[0055] The method is basically the same as Example 1, except that centrifugal degassing is not performed, and specifically comprises the following steps:

[0056] S1. Transfer the photoresist and the diluent glycol methyl ether acetate to a beaker in sequence according to a dilution ratio of 1:7, place a magnetic stir bar in the beaker, and place the beaker on a magnetic stirrer. Start the magnetic stirrer and stir at a speed of 200 rpm for 3 minutes to fully mix the liquid in the beaker to obtain a coating liquid with a viscosity of about 1 cp;

[0057] S2. Place the silicon wafer on a spin coater, drop about 2 mL of a sustained-release agent, propylene glycol monomethyl ether, on the center, start the spin coating, and under the force of rotation, the sustained-release agent is spread out on the surface of the silicon wafer to form a protective layer;

[0058] S3, connect the coating liquid to the glue pump pipeline of the coating machine, turn on the nitrogen (nitrogen is used as the carrier gas in the coating process) and the air compressor, start the operating program of the coating machine, and spray the coating liquid on the surface of the protective layer in the order of first coating a thin layer and then coating a thick layer to form a thin photoresist layer and a thick photoresist layer in sequence; wherein, the ultrasonic atomization frequency of the thin layer coating is 93kHz, the power is 9W, the coating liquid is ultrasonically atomized according to the set program, and a thin photoresist layer with a thickness of about 0.15μm is coated on the surface of the protective layer; the ultrasonic atomization frequency of the thick layer coating is 118kHz, the power is 14W, the coating liquid is ultrasonically atomized according to the set program, and a thick photoresist layer with a thickness of about 3μm is coated on the surface of the thin photoresist layer;

[0059] S4. Place the sprayed silicon wafer on a heating plate and dry it in stages from low temperature to high temperature to complete the coating; the low temperature stage is kept at 40°C for 1.5 minutes; the second stage is kept at 100°C for 4 minutes.

[0060] Comparative Example 4

[0061] The method is basically the same as Example 1, except that the drying is not performed in stages, and specifically comprises the following steps:

[0062] S1. Transfer the photoresist and the diluent glycol methyl ether acetate to a beaker in sequence according to a dilution ratio of 1:7, place a magnetic stirrer in the beaker, place the beaker on a magnetic stirrer, start the magnetic stirrer, and stir at a speed of 200 rpm for 3 min to fully mix the liquid in the beaker; then transfer the mixed solution to a centrifuge tube, place the centrifuge tube inside a centrifuge, start the centrifuge, and degas the mixture at a speed of 500 rpm for 3 min to obtain a coating solution with a viscosity of about 1 cp;

[0063] S2, connect the above-mentioned coating liquid to the glue pump pipeline of the coating machine, turn on the nitrogen (nitrogen is used as the carrier gas in the coating process) and the air compressor, start the operating program of the coating machine, and spray them on the surface of the silicon wafer in the order of first coating a thin layer and then coating a thick layer to form a thin photoresist layer and a thick photoresist layer in sequence; wherein, the ultrasonic atomization frequency of the thin layer coating is 93kHz, the power is 9W, and the coating liquid is ultrasonically atomized according to the set program, and a thin photoresist layer with a thickness of about 0.15μm is coated on the surface of the silicon wafer; the ultrasonic atomization frequency of the thick layer coating is 118kHz, the power is 14W, and the coating liquid is ultrasonically atomized according to the set program, and a thick photoresist layer with a thickness of about 3μm is coated on the surface of the thin photoresist layer;

[0064] S3. Place the sprayed silicon wafer on a heating plate and keep it at 100°C for 5 minutes to complete the coating.

[0065] Test Example 1

[0066] The surfaces of the silicon wafers after coating in Example 1 and Comparative Examples 1-4 were observed using a microscope. The results are as follows: Figure 1-Figure 5 As shown. Figure 1 It can be seen that the surface of the silicon wafer after coating is smooth and has no obvious defects. This shows that the coating method of the embodiment can effectively improve the surface bubbles after the photoresist is coated on the silicon wafer, and improve the uniformity and surface cleanliness after the photoresist is coated. Figure 2-Figure 3 It can be seen that without the coating of the protective layer and the thin photoresist layer, more irregular bubbles appear on the surface, and the bubbles are easy to agglomerate, resulting in more defects. Figure 4 It can be seen that without the centrifugal coating process, there are a lot of bubbles on the surface of the silicon wafer after coating, and the surface is relatively rough. Figure 5 It can be seen that step-by-step drying was not carried out, and holes appeared on the surface due to the rapid drying temperature increase.

[0067] Obviously, the above embodiments are merely examples for clear explanation and are not intended to limit the implementation methods. For those skilled in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the implementation methods here. The obvious changes or modifications derived from these are still within the protection scope of the invention.

Claims

1. A method for coating a photoresist, characterized in that: The following steps are involved: S1, coating the sustained-release agent on the surface of the silicon wafer to form a protective layer; S2, spraying a coating liquid on the surface of the protective layer to sequentially form a first photoresist layer and a second photoresist layer; the coating liquid is obtained by diluting the photoresist with a diluent and degassing by centrifugation; the thickness of the first photoresist layer is 0.1 μm-0.2 μm, and the thickness of the second photoresist layer is 1 μm-5 μm; S3, drying the sprayed silicon wafers in stages to complete the coating; the staged drying includes two stages, the first stage is to keep the temperature at 30℃-50℃ for 1min-2min; the second stage is to keep the temperature at 90℃-110℃ for 3min-5min.

2. The photoresist coating method according to claim 1, characterized in that: In S1, the sustained-release agent is selected from one or more of mercaptobenzothiazole, benzotriazole, methylbenzotriazole, propylene glycol monomethyl ether and propylene glycol monomethyl ether acetate.

3. The photoresist coating method according to claim 1, characterized in that: In S2, the photoresist comprises, by weight: 30-60 parts of a binder polymer, 10-45 parts of a photoreactive monomer, and 1-5 parts of a photoinitiator; the binder polymer is obtained by free radical polymerization of acrylic acid, isoprene, methacrylic acid, hexafluoroisopropyl methacrylate, and glycidyl methyl isopropylate in the presence of an initiator and a solvent; the molar ratio of the acrylic acid, isoprene, methacrylic acid, hexafluoroisopropyl methacrylate, and glycidyl methyl isopropylate is 1:(1-1.2):(0.8-1.1):(0.9-1.1):(1-1.2), and the weight average molecular weight of the binder polymer is greater than 6000.

4. The method for coating a photoresist according to claim 1, characterized in that: In S2, the diluent is selected from propylene glycol methyl ether acetate and / or acetone; the dilution ratio is 1:(3-7).

5. The method for coating a photoresist according to claim 1, characterized in that: In S2, the viscosity of the photoresist is 500cp-700cp.

6. The method for coating a photoresist according to claim 1, characterized in that: In S2, the viscosity of the coating liquid is 1 cp-20 cp.

7. The photoresist coating method according to claim 1, characterized in that: In S2, the dilution is carried out by stirring with a magnetic stirrer at a rotation speed of 200 rpm-500 rpm for 1 min-20 min.

8. The method for coating a photoresist according to claim 1, characterized in that: In S2, the centrifugal degassing is performed by centrifuging at a speed of 500 rpm to 2000 rpm for 1 min to 20 min.

9. The photoresist coating method according to claim 1, characterized in that: In S2, the spraying method is ultrasonic atomization or slit coating; the process parameters of the slit coating are: liquid supply speed is 0.03mL / s-30mL / s, coating speed is 1mm / s-200mm / s, and the gap between the coating head and the substrate is 10μm-100μm.

10. The photoresist coating method according to claim 9, characterized in that: In S2, the ultrasonic atomization process parameters of the first photoresist layer are: frequency of 90kHz-95kHz, power of 8W-10W; The ultrasonic atomization process parameters of the second photoresist layer are: frequency of 115kHz-121kHz, power of 12W-16W.

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