A thick positive photoresist, a photoresist layer and a preparation method thereof

Abstract

The application provides a thick positive photoresist, a photoresist layer and a preparation method thereof, and relates to the technical field of photoetching machines. The thick positive photoresist comprises, in parts by mass, 30-70 parts of phenolic resin, 20-40 parts of a silicon-containing copolymer film-forming resin, 10-20 parts of a photosensitive compound, 0.01-1 part of a leveling agent and 80-150 parts of a solvent. The structure of the silicon-containing copolymer film-forming resin comprises: wherein R is selected from H or C1-C5 alkyl. By adding the silicon-containing copolymer film-forming resin to the phenolic resin, the adhesion, flexibility, thermal stability and mechanical strength of the photoresist layer are improved by using the thermal stability, high-temperature resistance, mechanical properties and corrosion resistance of the film-forming resin, and the photoresist layer is prevented from cracking, pattern deformation and even peeling off.

Description

Technical Field

[0001] This application relates to the field of photoresist technology, and in particular to a thick positive photoresist, a photoresist layer, and a method for preparing the same. Background Technology

[0002] In advanced interconnect technologies, photoresist layers are needed for current transmission in wafer-level chip-scale packaging, including solder bumps, gold bumps, copper pillars, and copper wires. These layers are then electroplated to form the final metal structure. Thick-film photoresist is a crucial material in these packaging processes. For example, solder bumps typically have a pitch of only 150µm, requiring a photoresist thickness between 50 and 100µm. Gold bumps, mainly used in TAB and COG technologies, have a pitch as low as 40µm, sometimes as low as 10µm. However, the precision and sidewall angle of the photoresist layer are extremely important, as the shape of the photoresist layer determines the final shape of the metal bumps.

[0003] However, as the thickness of the photoresist layer increases, the photolithography process requires not only sufficient photosensitivity but also that the film remain undeformed and crack-free during electroplating and etching, meaning it must possess good adhesion, resistance to electroplating, and resistance to etching. Commonly used negative ultraviolet photoresists, due to their highly cross-linked molecular chains being extremely rigid, are prone to internal stress during photolithography, leading to pattern deformation, film cracking, and even detachment, thus failing to meet process requirements. Summary of the Invention

[0004] The purpose of this application is to provide a thick-film positive photoresist, a photoresist layer and a method for preparing the same. By adding a silicon-containing copolymer film-forming resin to a phenolic resin, the adhesion and flexibility of the film-forming agent are improved, so that the sidewall verticality of the photoresist meets the requirements of thick-film photoresist, and the film is not easy to crack.

[0005] To achieve the above objectives, the technical solution of this application is as follows:

[0006] This application provides a thick positive photoresist, the raw material components of which, by mass parts, include:

[0007] 30-70 parts of phenolic resin, 20-40 parts of silicone copolymer film-forming resin, 10-20 parts of photosensitive compound, 0.01-1 part of leveling agent and 80-150 parts of solvent;

[0008] The silicon-containing copolymer film-forming resin has a structure as shown in formula (I):

[0009]

[0010] In the formula, R is selected from H or C1-C5 alkyl groups.

[0011] Preferably, the phenolic resin is prepared by polycondensation reaction of methylphenol and formaldehyde;

[0012] The average molecular weight of the phenolic resin is 7000-29000.

[0013] Preferably, the average molecular weight of the silicon-containing copolymer film-forming resin is 10,000-80,000, and the molecular weight distribution is 2.3-2.6.

[0014] Preferably, the silicon-containing copolymer film-forming resin is prepared by copolymerization of allyl ether, vinylpentamethyldisiloxane and monomers conforming to general chemical formula (II) in the presence of an initiator;

[0015]

[0016] In the formula, R1 is selected from H or C1-C5 alkyl groups.

[0017] More preferably, the initiator includes at least one of azo initiators and organic peroxide initiators.

[0018] Preferably, the photosensitive compound includes a diazonoquinone photosensitive compound.

[0019] Preferably, the leveling agent includes at least one of MEGAFACE F-563, polymethylphenylsiloxane, and polydimethylsiloxane.

[0020] Preferably, the solvent includes at least one selected from propylene glycol methyl ether acetate, dimethylacetamide, xylene, anisole, propylene glycol monomethyl ether, propylene glycol monoethyl ether, propylene glycol methyl ether acetate, diethylene glycol methyl ether, diethylene glycol ethyl ether, propylene glycol methyl ether acetate, butyl acetate, ethyl acetate, ethyl lactate, γ-butyrolactone, and N-methylpyrrolidone.

[0021] This application also provides a photoresist layer, which is formed by curing the above-mentioned thick positive photoresist.

[0022] The method for preparing the photoresist layer includes: mixing the raw material components of the thick positive photoresist to prepare a photoresist solution;

[0023] The photoresist layer is obtained by homogenizing the photoresist solution on a substrate, pre-baking, exposing, post-baking, and developing.

[0024] The beneficial effects of this application are:

[0025] In addition to using phenolic resin as a raw material, the thick-film positive photoresist of this application also contains a silicon-containing copolymer film-forming resin, which increases the adhesion, flexibility, sidewall perpendicularity, and mechanical properties of the film-forming agent, and also prevents film cracking, peeling, and image distortion. Specifically, the silicon-containing copolymer film-forming resin of this application has high thermal stability and high-temperature resistance, which enhances the heat resistance of the photoresist and keeps it stable under high-temperature conditions; it also has good mechanical properties, which enhances the mechanical strength and tensile strength of the photoresist and reduces damage to the photoresist film during development and cleaning; the silicon-containing copolymer film-forming resin has low chemical corrosivity, which improves the chemical resistance of the photoresist, reduces the reaction with chemicals such as developers and cleaning solutions, and improves the stability and service life of the photoresist; the silicon-containing copolymer film-forming resin can form a thin non-adhesive silicon oxide layer between the photoresist and the mask, reducing the adhesion between the photoresist and the mask, which helps to improve the resolution and replication accuracy of the pattern. Attached Figure Description

[0026] To more clearly illustrate the technical solutions of the embodiments of this application, the accompanying drawings used in the embodiments will be briefly described below. It should be understood that the following drawings only show some embodiments of this application and should not be regarded as a limitation on the scope of this application.

[0027] Figure 1 The image obtained under an optical microscope after the thick positive photoresist layer prepared for Example 1 was removed from the electroplating solution;

[0028] Figure 2 The image obtained under an optical microscope after the thick positive photoresist layer prepared in Example 2 was removed from the electroplating solution;

[0029] Figure 3 The image of the photoresist layer prepared for Comparative Example 1 after it was removed from the electroplating solution is obtained under an optical microscope.

[0030] Figure 4 The image shown is obtained under an optical microscope after the photoresist layer prepared for Comparative Example 2 was removed from the electroplating solution. Detailed Implementation

[0031] As used in this article:

[0032] "Prepared from" is synonymous with "comprising". The terms "comprising", "including", "having", "containing", or any other variations thereof as used herein are intended to cover non-exclusive inclusion. For example, a composition, step, method, article, or apparatus that includes the listed elements is not necessarily limited to those elements, but may include other elements not expressly listed or elements inherent to such a composition, step, method, article, or apparatus. The conjunction "composed of" excludes any unnamed elements, steps, or components.

[0033] When a quantity, concentration, or other value or parameter is expressed as a range, a preferred range, or a range defined by a series of upper and lower preferred values, this should be understood as specifically disclosing all ranges formed by any pair of any upper or preferred value with any lower or preferred value, regardless of whether the range is disclosed individually. For example, when the range “1–5” is disclosed, the described range should be interpreted as including ranges “1–4”, “1–3”, “1–2”, “1–2 and 4–5”, “1–3 and 5”, etc. When numerical ranges are described herein, unless otherwise stated, the range is intended to include its endpoints and all integers and fractions within that range.

[0034] In these embodiments, unless otherwise specified, the portions and percentages are all by weight.

[0035] "Parts by mass" refers to the basic unit of measurement that expresses the mass ratio of multiple components. One part can represent any unit mass, such as 1g or 2.689g. If we say that component A has "a" parts by mass and component B has "b" parts by mass, it means the ratio of the mass of component A to the mass of component B is a:b. Alternatively, it can mean that the mass of component A is aK and the mass of component B is bK (K is any number representing a multiplier). It is important to understand that, unlike the number of parts by mass, the sum of the mass parts of all components is not limited to 100 parts.

[0036] "And / or" is used to indicate that one or both of the described situations may occur, for example, A and / or B includes (A and B) and (A or B).

[0037] This application provides a thick positive photoresist, the raw material components of which, by mass parts, include:

[0038] 30 to 70 parts of phenolic resin, for example, it can be 30, 40, 50, 55, 60, 70 parts or any value between 30 and 70 parts;

[0039] 20 parts to 40 parts of a silicone copolymer film-forming resin, for example, 20 parts, 25 parts, 30 parts, 35 parts, 40 parts, or any value between 20 and 40 parts;

[0040] 10 to 20 parts of the photosensitizing compound, for example, 10, 12, 15, 18, 20 parts or any value between 10 and 20 parts;

[0041] 0.01 to 1 part of leveling agent, for example, can be 0.01, 0.05, 0.1, 0.3, 0.5, 1 part or any value between 0.01 and 1 part;

[0042] The second solvent is 80 to 150 parts, for example, it can be 80, 90, 100, 120, 140, 150 parts or any value between 80 and 150 parts.

[0043] Among them, the silicon-containing copolymer film-forming resin has the structure shown in formula (Ⅰ):

[0044]

[0045] In the formula, R is selected from H or C1-C5 alkyl groups.

[0046] This silicon-containing copolymer film-forming resin possesses high thermal stability, high-temperature resistance, and good mechanical properties. Its addition enhances the heat resistance, mechanical strength, and tensile strength of the photoresist. Simultaneously, the silicon-containing copolymer film-forming resin exhibits low chemical corrosivity, improving the photoresist's chemical resistance, reducing reactions with developers, cleaning solutions, and other chemicals, and thus improving the photoresist's stability and lifespan. Furthermore, this silicon-containing copolymer film-forming resin can form a thin, non-adhesive silicon oxide layer between the photoresist and the mask (the template for the pattern on the photoresist), reducing the adhesion between the photoresist and the mask and contributing to improved pattern resolution and replication accuracy.

[0047] In a preferred embodiment of this application, the phenolic resin is prepared by a polycondensation reaction of methylphenol and formaldehyde. Specifically, m-cresol, p-cresol, and formaldehyde can be used for the polycondensation reaction; m-cresol, o-cresol, and formaldehyde can be used for the polycondensation reaction; or m-cresol, o-cresol, p-cresol, and formaldehyde can be used for the polycondensation reaction, etc.

[0048] In a preferred embodiment of this application, the average molecular weight of the phenolic resin is 7000-29000.

[0049] In a preferred embodiment of this application, the average molecular weight of the silicon-containing copolymer film-forming resin is 10,000-80,000, and the molecular weight distribution is 2.3-2.6.

[0050] In a preferred embodiment of this application, the silicon-containing copolymer film-forming resin is prepared by copolymerization of allyl ether, vinylpentamethyldisiloxane and monomers conforming to general chemical formula (II) in the presence of an initiator;

[0051]

[0052] In the formula, R1 is selected from H or C1-C5 alkyl groups.

[0053] It should be noted that this silicon-containing copolymer film-forming resin can be purchased as a finished product or synthesized chemically from purchased raw materials. For example, when R1 is selected from H, the chemical reaction formula of this silicon-containing copolymer film-forming resin is:

[0054]

[0055] In a preferred embodiment of this application, the initiator required for the copolymerization reaction includes at least one of azo initiators and organic peroxide initiators.

[0056] In a preferred embodiment of this application, the photosensitive compound in the thick positive photoresist includes a diazonoquinone photosensitive compound; the leveling agent includes at least one of MEGAFACE F-563, polymethylphenylsiloxane, and polydimethylsiloxane; and the solvent includes at least one of propylene glycol methyl ether acetate, dimethylacetamide, xylene, anisole, propylene glycol monomethyl ether, propylene glycol monoethyl ether, propylene glycol methyl ether acetate, diethylene glycol methyl ether, diethylene glycol ethyl ether, propylene glycol methyl ether acetate, butyl acetate, ethyl acetate, ethyl lactate, γ-butyrolactone, and N-methylpyrrolidone.

[0057] This application also provides a photoresist layer, the preparation method of which includes:

[0058] S1. Mix the raw material components of the thick positive photoresist to prepare a photoresist solution;

[0059] S2. The adhesive solution is homogenized, pre-baked, exposed, post-baked, and developed on the substrate to obtain a photoresist layer.

[0060] It should be noted that when preparing the adhesive solution, the well-stirred solution generally needs to be filtered through a 2μm filter membrane to ensure a smoother membrane surface during subsequent homogenization.

[0061] The implementation schemes of this application will be described in detail below with reference to specific embodiments. However, those skilled in the art will understand that the following embodiments are only for illustrating this application and should not be regarded as limiting the scope of this application. Unless otherwise specified in the embodiments, conventional conditions or conditions recommended by the manufacturer shall apply. Reagents or instruments used without specified manufacturers are all conventional products that can be purchased commercially.

[0062] Example 1

[0063] This embodiment provides a thick-film positive photoresist, which, by weight, comprises the following components: 65 parts phenolic resin, 20 parts silicon-containing copolymer film-forming resin, 14 parts photosensitive compound (2,3,4-trihydroxybenzophenone-4-DNQ sulfonate), 1 part leveling agent (MEGAFACE F-563), and 120 parts solvent (propylene glycol methyl ether acetate PGMEA).

[0064] The phenolic resin and the silicon-containing copolymer film-forming resin were prepared in the laboratory, while the other raw materials were purchased from the market.

[0065] The preparation method of phenolic resin includes: weighing 100 g (0.93 mol) of m-cresol, 150 g (1.39 mol) of p-cresol, 150 g (37 wt%) of formaldehyde aqueous solution (1.85 mol), and 3.2 g of oxalic acid, placing them in a stirred container, starting stirring and heating to 90℃-95℃, maintaining the reaction at this temperature for 3 hours. Then, slowly increasing the temperature and distilling off unreacted cresol, formaldehyde, and water under normal pressure until reaching 120℃-130℃; then performing vacuum distillation, achieving a vacuum pressure of 30 mmHg-60 mmHg and a temperature of 180℃, holding for 30 minutes, and finally continuing to increase the temperature to 200℃-220℃, holding for 15 minutes, stopping heating, and removing the vacuum. The obtained phenolic resin product is cooled and solidified, and then the cooled product is pulverized to obtain powdered phenolic resin with an average molecular weight of 7000-29000.

[0066] The preparation method of the silicon-containing copolymer film-forming resin includes: weighing 50 g of allyl ether, 90 g of α-methylstyrene, 10 g of vinylpentamethyldisiloxane and 300 g of methanol, placing them in a stirred container, stirring continuously and purging with nitrogen for 5 minutes. Then heating to 65℃-70℃, and continuing to add a mixture of 3.0 g of azobisisobutyronitrile (AIBN) and 50 g of methanol to the stirred container, reacting under reflux for 16-20 h. After the reaction is complete, the cooled reaction solution is slowly added dropwise to heptane under stirring, filtered, and the white solid precipitate is collected. This white solid is then dissolved in 300 mL of acetone to form a transparent solution, and this transparent solution is then added dropwise to heptane to form a precipitate. The precipitate is filtered, collected, and dried under vacuum at 45℃ to obtain 115 g of the silicon-containing copolymer film-forming resin product, with a yield of approximately 76%. Gel permeation chromatography analysis showed that the average molecular weight of the copolymer was 50,000, and the molecular weight distribution was 2.5.

[0067] Example 2

[0068] The thick positive photoresist provided in this embodiment comprises the following components by weight: 53 parts phenolic resin, 30 parts silicon-containing copolymer film-forming resin, 16 parts photosensitive compound (polyphenolic-5-DNQ sulfonate), 1 part leveling agent (MEGAFACE F-563), and 120 parts solvent (propylene glycol methyl ether acetate PGMEA).

[0069] The preparation methods of the phenolic resin and the silicon-containing copolymer film-forming resin in this embodiment are the same as in Example 1.

[0070] Example 3

[0071] The thick positive photoresist provided in this embodiment is the same as that in Example 1, except that the preparation method of the silicon-containing copolymer film-forming resin is different from that in Example 1. Specifically, 90 grams of α-methylstyrene is replaced with 90 grams of 4-methyl-α-methylstyrene, and the average molecular weight of the silicon-containing copolymer film-forming resin obtained is 50,000, with a molecular weight distribution of 2.4.

[0072] The chemical reaction equation for this silicon-containing copolymer film-forming resin is as follows:

[0073]

[0074] Comparative Example 1

[0075] The thick-film positive photoresist of this comparative example comprises the following components by weight: 85 parts phenolic resin, 14 parts photosensitizer (2,3,4-trihydroxybenzophenone-4-DNQ sulfonate), 1 part leveling agent (MEGAFACE F-563), and 120 parts solvent (propylene glycol methyl ether acetate PGMEA).

[0076] The preparation method of the phenolic resin in this comparative example is the same as that in Example 1.

[0077] Comparative Example 2

[0078] The thick-film positive photoresist of this comparative example comprises the following components by mass: 83 parts phenolic resin, 16 parts photosensitizer (polyphenolic-5-DNQ sulfonate), 1 part leveling agent (MEGAFACE F-563), and 120 parts solvent (propylene glycol methyl ether acetate PGMEA).

[0079] The preparation method of the phenolic resin in this comparative example is the same as that in Example 1.

[0080] Comparative Example 3

[0081] The thick positive photoresist of this comparative example comprises the following components by mass parts: 83 parts of silicon-containing copolymer film-forming resin, 16 parts of photosensitizer polyphenolic aldehyde-5-DNQ sulfonate, 1 part of leveling agent F-563, and 120 parts of propylene glycol methyl ether acetate (PGMEA) solvent.

[0082] The preparation method of the silicon-containing copolymer film-forming resin in this comparative example is the same as that in Example 1.

[0083] Photoresist layers were prepared using the photoresist formulations of the above embodiments and comparative examples, and the specific preparation methods included:

[0084] (1) Prepare the raw material components in the photoresist formulation into a solution, shake it on a shaker for more than 48 hours, and filter it through a 2μm filter membrane;

[0085] (2) On a 4-inch silicon wafer substrate, the filtered adhesive solution is homogenized using a main speed of 500rpm-1000rpm and baked at a temperature of 90℃-120℃.

[0086] (3) Use I-line proximity exposure with an energy of 100 mJ / cm². 2 -400mJ / cm 2 The gap is 10μm-20μm; then it is developed with 2.38% TMAH for 60s-120s.

[0087] The resolution, morphology, cracking, and adhesion to the substrate of the photolithographic pattern after development were tested. The developed pattern of the sample was placed in Au electroplating solution and soaked at room temperature for 2 hours. The morphology was observed under an optical microscope to check for changes and cracks on the electroplated surface. The perpendicularity of the sidewalls was also tested. The test results are shown in Table 1.

[0088] Table 1. Test results of photoresist layers in each embodiment and comparative example.

[0089]

[0090] Based on the test data in Table 1, and combined with Figure 1 , Figure 2 , Figure 3 , Figure 4 It can be seen that: after adding silicon-containing copolymer film-forming resin to the thick positive photoresist provided in the embodiments of this application, the photoresist layer has better adhesion, and no cracks appear on the surface of the photoresist layer after immersion in electroplating solution.

[0091] Therefore, it can be seen that the addition of silicon-containing copolymer film-forming resin to the thick positive photoresist of this application can increase the adhesion, flexibility, and sidewall verticality of the film-forming agent, and prevent the film from cracking, deforming, or even falling off.

[0092] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application.

[0093] Furthermore, those skilled in the art will understand that although some embodiments herein include certain features included in other embodiments but not others, combinations of features from different embodiments are intended to be within the scope of this application and form different embodiments. For example, any of the embodiments claimed above can be used in any combination. The information disclosed in this background section is intended only to enhance the understanding of the general background of this application and should not be construed as an admission or in any way implying that such information constitutes prior art known to those skilled in the art.

Claims

1. A thick-film positive photoresist, characterized in that, The raw material components of the thick positive photoresist, by weight, include: 30-70 parts of phenolic resin, 20-40 parts of silicone copolymer film-forming resin, 10-20 parts of photosensitive compound, 0.01-1 part of leveling agent and 80-150 parts of solvent; The silicon-containing copolymer film-forming resin has a structure as shown in formula (I): In the formula, R is selected from H or C1-C5 alkyl groups.

2. The thick-film positive photoresist as described in claim 1, characterized in that, The phenolic resin is prepared by polycondensation reaction of methylphenol and formaldehyde. The average molecular weight of the phenolic resin is 7000-29000.

3. The thick-film positive photoresist as described in claim 1, characterized in that, The average molecular weight of the silicon-containing copolymer film-forming resin is 10,000-80,000, and the molecular weight distribution is 2.3-2.

6.

4. The thick-film positive photoresist as described in claim 1, characterized in that, The silicon-containing copolymer film-forming resin is prepared by copolymerization of allyl ether, vinylpentamethyldisiloxane and monomers conforming to general chemical formula (II) in the presence of an initiator. In the formula, R1 is selected from H or C1-C5 alkyl groups.

5. The thick-film positive photoresist as described in claim 4, characterized in that, The initiator includes at least one of azo initiators and organic peroxide initiators.

6. The thick-film positive photoresist as described in claim 1, characterized in that, The photosensitive compounds include diazonoquinone photosensitive compounds.

7. The thick-film positive photoresist as described in claim 1, characterized in that, The leveling agent includes at least one of MEGAFACE F-563, polymethylphenylsiloxane, and polydimethylsiloxane.

8. The thick-film positive photoresist according to any one of claims 1-7, characterized in that, The solvent includes at least one of propylene glycol methyl ether acetate, dimethylacetamide, xylene, anisole, propylene glycol monomethyl ether, propylene glycol monoethyl ether, propylene glycol methyl ether acetate, diethylene glycol methyl ether, diethylene glycol ethyl ether, propylene glycol methyl ether acetate, butyl acetate, ethyl acetate, ethyl lactate, γ-butyrolactone, and N-methylpyrrolidone.

9. A photoresist layer, characterized in that, It is formed by curing the thick positive photoresist according to any one of claims 1-8.

10. A method for preparing a photoresist layer as described in claim 9, characterized in that, include: The raw material components of the thick positive photoresist are mixed to form a photoresist solution; The photoresist layer is obtained by homogenizing the photoresist solution on a substrate, pre-baking, exposing, post-baking, and developing.

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