阅读说明：本技术 一种光刻胶用酚醛树脂及其制备方法 (Phenolic resin for photoresist and preparation method thereof ) 是由 王富成 苏志强 赵鑫 马铮 于 2021-09-22 设计创作，主要内容包括：本发明提供了一种光刻胶用酚醛树脂,是以包括以下原料缩聚制备得到：对甲酚,间甲酚,二甲酚,3,3'-二甲基-4,4'-联苯二酚,2-羟基1-羟甲基萘,螺环二酚,甲醛和/或多聚甲醛。本发明光刻胶酚醛树脂中加入一定量的3,3'-二甲基-4,4'-联苯二酚,螺环二酚和2-羟基1-羟甲基萘,三者在一定比例范围内发挥协同作用,使所得酚醛树脂的耐热性,以及光刻胶的分辨率和感光性同时得到了改善。本发明以三段式的生产工艺制备酚醛树脂,通过控制投料顺序,反应温度,时间等工艺条件,得到了综合性能优异的酚醛树脂,经过测试,其软化温度在136℃左右,分子量分布窄,作为光刻胶的成膜树脂,性能优异。(The invention provides a phenolic resin for photoresist, which is prepared by polycondensation of the following raw materials: p-cresol, m-cresol, xylenol, 3,3 '-dimethyl-4, 4' -biphenol, 2-hydroxy-1-hydroxymethylnaphthalene, spirodiphenol, formaldehyde and/or paraformaldehyde. The photoresist phenolic resin is added with a certain amount of 3,3 '-dimethyl-4, 4' -biphenol, spirocyclic diphenol and 2-hydroxy 1-hydroxymethyl naphthalene which play a synergistic role in a certain proportion range, so that the heat resistance of the obtained phenolic resin, and the resolution and photosensitivity of the photoresist are improved simultaneously. The phenolic resin is prepared by a three-stage production process, the phenolic resin with excellent comprehensive performance is obtained by controlling the process conditions such as the feeding sequence, the reaction temperature, the time and the like, and the phenolic resin has the softening temperature of about 136 ℃ and narrow molecular weight distribution after being tested, and has excellent performance when being used as a film-forming resin of a photoresist.)

1. The phenolic resin for the photoresist is characterized by being prepared by polycondensation of the following raw materials: p-cresol, m-cresol, xylenol, 3,3 '-dimethyl-4, 4' -biphenol, 2-hydroxy-1-hydroxymethylnaphthalene, spirodiphenol, formaldehyde and/or paraformaldehyde.

2. The phenol resin for resist according to claim 1, wherein the xylenol is at least one selected from the group consisting of 2, 4-xylenol, 2, 6-xylenol, 2, 5-xylenol, 3, 5-xylenol, and 3, 4-xylenol.

3. The phenol resin for resists according to claim 2, wherein the xylenol is 3, 5-xylenol.

4. The phenolic resin for the photoresist according to claim 1, wherein the phenolic resin for the photoresist is prepared by polycondensation of the following raw materials in parts by weight: 45-55 parts of p-cresol, 50-60 parts of m-cresol, 8-12 parts of 2-hydroxy 1-hydroxymethyl naphthalene, 5-8 parts of xylenol, 4-8 parts of 3,3 '-dimethyl-4, 4' -biphenol, 3-5 parts of spirocyclic diphenol and 100 parts of formaldehyde and/or paraformaldehyde.

5. A process for producing a phenol resin for resists according to any one of claims 1 to 4, comprising the steps of:

(S1) adding p-cresol, 30-50% of the total amount of formaldehyde and alkali, heating to 50-55 ℃, reacting for 2-3h, adding dilute acid for neutralization, and washing the product to be neutral for later use;

(S2) mixing the product obtained in the step (S1), m-cresol, xylenol, 2-hydroxy 1-hydroxymethyl naphthalene, the rest formaldehyde, 70-95% of acid catalyst and solvent uniformly, and continuously heating to 80-90 ℃ for reaction for 1-3 h;

(S3) continuing to heat to 90-95 ℃, slowly adding 3,3 '-dimethyl-4, 4' -biphenol and the rest of acid catalyst, reacting for 2-3h, finally adding spirocyclic diphenol, continuing to react for 1-2h, finally washing the obtained product with water, and drying in vacuum to obtain the phenolic resin.

6. The method according to claim 5, wherein in the step (S2), the acidic catalyst is at least one of oxalic acid, trichloroacetic acid, benzenesulfonic acid, succinic acid, and acidic ion exchange resin, preferably oxalic acid.

7. The method of claim 5, wherein in the step (S3), the slowly adding step is to dissolve the remaining acidic catalyst of 3,3 '-dimethyl-4, 4' -biphenol in the solvent and add the solution in 0.5-1 h.

8. The method of claim 5, wherein the solvent of the steps (S2) and (S3) is at least one selected from the group consisting of ethylene glycol monomethyl ether, propylene glycol methyl ether acetate, petroleum ether, and n-heptane.

9. The production method according to claim 5, wherein in the step (S3), the water washing is to remove impurities, unreacted acid and phenol; the vacuum drying is carried out under 0.01-0.05MPa at 60-80 deg.C for 4-8 h.

10. A photoresist comprising the following components: the phenolic resin of any one of claims 1 to 4, a photosensitizer and a solvent.

Technical Field

The invention relates to the field of phenolic resin for photoresist, in particular to phenolic resin for photoresist and a preparation method thereof.

Background

The linear phenolic resin is the most common film-forming resin of G-line and I-line positive photoresists, the photoresists have good light transmittance, good adhesion with a substrate and strong dry method and wet method corrosion resistance, but the linear phenolic resin has lower glass transition temperature and insufficient heat resistance, in most of the microelectronic processing processes in the day, the photoresist needs to be baked at high temperature for many times, but the general linear phenolic resin has insufficient temperature resistance, the migration of a catalyst is increased during photoetching, the requirement for a circuit device with higher resolution cannot be met, and the photoetching pattern deformation can occur in the conventional phenolic resin at the temperature higher than 140 ℃ to influence the resolution of the photoresist.

In order to solve the problem of insufficient heat resistance of the linear phenolic resin, the prior art prepares pre-condensation of p-cresol and formaldehyde to obtain 2, 6-dihydroxy-p-cresol with bifunctionality, replaces part of p-cresol, can obtain the phenolic resin with high o-o' linking degree, and has good photoetching performance. However, the problem of heat resistance of the phenolic resin is not solved. It has also been reported that the incorporation of xylenols such as 2, 4-xylenol, 2, 6-xylenol, 2, 5-xylenol, 3,4, -xylenol into the system can improve heat resistance, but the resolution of the photoresist can be reduced. The molecular weight distribution also affects the heat resistance of the phenol novolac resin, and in order to obtain narrow molecular weight distribution, the prior art firstly dissolves the phenol novolac resin in a good solvent, and then precipitates the phenol novolac resin in water; or the low molecular weight fraction is reduced by means of steam distillation; or separating and purifying by silica gel chromatographic column to remove low molecular weight fraction. However, these post-treatment methods are not suitable for industrialization because the production cost of the phenolic resin is significantly increased.

The method in the prior art improves the heat resistance of the film forming material, namely the linear phenolic resin for the photoresist, and has high cost and difficult industrialization; or the resolution is lowered while the heat resistance is improved, which is not worth paying. It can be seen that, in the photoresist of the linear phenolic resin, it is difficult to improve the heat resistance and the resolution at the same time,

the inventor of the previous patent 202110890081.7 adds a certain proportion of 3,3 '-dimethyl-4, 4' -biphenol and 2-hydroxy-1-hydroxymethyl naphthalene and a small amount of phenolic polyhydroxy compound into the phenolic resin, and obtains the phenolic resin with narrow molecular weight distribution, good heat resistance and resolution of the prepared photoresist by regulating the raw material proportion and controlling the process. However, subsequent researches have found that the addition of 3,3 '-dimethyl-4, 4' -biphenol improves the heat resistance, so that the positive etching of the photoresist can be completed only under a strong exposure, and the photosensitivity of the photoresist needs to be enhanced.

Therefore, the research and development of the phenolic resin with high heat resistance, high resolution and excellent photosensitivity has important research significance and application prospect.

Disclosure of Invention

In order to overcome the defects that the resolution, heat resistance and photosensitivity of the conventional phenolic resin for the photoresist are difficult to improve simultaneously, the invention provides an improved phenolic resin for the photoresist and a preparation method thereof, a certain proportion of 3,3 '-dimethyl-4, 4' -biphenol, spirodiphenol and 2-hydroxy 1-hydroxymethyl naphthalene (CAS No 5386-25-4) are added into a basic formula of the phenolic resin, and the phenolic resin with narrow molecular weight distribution is obtained by optimizing the raw material proportion and controlling the process, so that the prepared photoresist has high resolution, good photosensitivity and excellent comprehensive performance.

In order to solve the technical problems, the invention provides the following technical scheme:

the phenolic resin for the photoresist is prepared by polycondensation of the following raw materials: p-cresol, m-cresol, xylenol, 3,3 '-dimethyl-4, 4' -biphenol, 2-hydroxy-1-hydroxymethylnaphthalene, spirodiphenol, formaldehyde and/or paraformaldehyde.

The xylenol is at least one selected from 2, 4-xylenol, 2, 6-xylenol, 2, 5-xylenol, 3, 5-xylenol and 3, 4-xylenol, preferably 3, 5-xylenol, and the 3, 5-xylenol is m-cresol, has high ortho-activity and is easy to form ortho-substitution reaction.

Further, the phenolic resin for the photoresist is prepared by polycondensation of the following raw materials in parts by weight: 45-55 parts of p-cresol, 50-60 parts of m-cresol, 8-12 parts of 2-hydroxy 1-hydroxymethyl naphthalene, 5-8 parts of xylenol, 4-8 parts of 3,3 '-dimethyl-4, 4' -biphenol, 3-5 parts of spirocyclic diphenol and 100 parts of formaldehyde and/or paraformaldehyde.

The inventor unexpectedly finds that the heat resistance, the photosensitivity and the resolution of the obtained phenolic resin are improved to different degrees simultaneously by replacing part of phenol with 3,3 '-dimethyl-4, 4' -biphenol, spirodiphenol and 2-hydroxy-1-hydroxymethyl naphthalene, and a certain synergistic effect can exist among the three. The added 3,3 '-dimethyl-4, 4' -biphenol and spirodiphenol have limited reactive sites, and form linear phenolic resin instead of a cross-linked structure, so that the photosensitivity is not adversely affected; the spiro diphenol is introduced into the terminal group position of the phenolic resin, so that a certain rigid structure is endowed to molecules, the heat resistance of the phenolic resin is improved, and the resolution of the obtained photoresist is not influenced. The dosage of the three is controlled in a certain proportion range, so that the prepared phenolic resin can be used as a film forming material of the photoresist, the heat resistance, the resolution and the photosensitivity of the photoresist are improved, and the comprehensive performance is excellent.

The invention also provides a preparation method of the phenolic resin for the photoresist, which comprises the following steps:

(S1) adding p-cresol, 30-50% of the total amount of formaldehyde and alkali, heating to 50-55 ℃, reacting for 2-3h, adding dilute acid for neutralization, and washing the product to be neutral for later use;

(S2) mixing the product obtained in the step (S1), m-cresol, xylenol, 2-hydroxy 1-hydroxymethyl naphthalene, the rest formaldehyde, 70-95% of acid catalyst and solvent uniformly, and continuously heating to 80-90 ℃ for reaction for 1-3 h;

(S3) continuing to heat to 90-95 ℃, slowly adding 3,3 '-dimethyl-4, 4' -biphenol and the rest of acid catalyst, reacting for 2-3h, finally adding spirocyclic diphenol, continuing to react for 1-2h, finally washing the obtained product with water, and drying in vacuum to obtain the modified phenolic resin.

In the above step, formaldehyde is added in the form of 30-40% formaldehyde aqueous solution.

Further, the step (S1) is intended to obtain a prepolymer of m-cresol and formaldehyde, and too high a reaction temperature or too long a reaction time may result in obtaining a prepolymer having a relatively large molecular weight, and a phenolic resin having a narrow molecular weight distribution as required in the present invention may not be obtained successfully. The base and the acid are not particularly limited, and examples of the base include sodium hydroxide, potassium hydroxide; examples of the acid include hydrochloric acid, sulfuric acid, oxalic acid, acetic acid, benzoic acid. In the step (S1), too low a formaldehyde content to accomplish an effective prepolymerization and too high a formaldehyde content may result in a broadening of the molecular weight distribution of the phenolic resin.

Further, in the step (S2), the acidic catalyst is at least one of oxalic acid, trichloroacetic acid, benzenesulfonic acid, succinic acid, and acidic ion exchange resin, and preferably oxalic acid. The oxalic acid has smooth reaction, which is beneficial to obtaining the polymer with narrow molecular weight distribution, and the oxalic acid can be decomposed and not remained in the subsequent processing. The amount of the acidic catalyst is 1-3 wt% of the total amount of formaldehyde.

Further, in the step (S3), the slow addition is made by dissolving 3,3 '-dimethyl-4, 4' -biphenol and the remaining acidic catalyst in a solvent and adding over 0.5-1 h.

The solvent used in the step (S2) and the step (S3) is not particularly limited, and may be one capable of sufficiently dispersing the respective materials, such as ethylene glycol monomethyl ether, propylene glycol methyl ether acetate, petroleum ether, and n-heptane.

In the step (S3), the water washing is to remove impurities, unreacted acid and phenol; the vacuum drying is carried out under 0.01-0.05MPa at 60-80 deg.C for 4-8 h.

The invention adopts a three-step method, although the method has one more step than the common two-step method in the prior art, the intermediate product does not need special treatment, only needs temperature control and material feeding, and still belongs to an industrially applicable continuous method. The molecular weight of the phenolic resin prepared by the specific steps of the invention is between 8000-12000, the molecular weight distribution is narrow, the Tg is higher than that of the conventional phenolic resin by about 10 ℃, and the prepared photoresist has high resolution and good photosensitivity.

The beneficial effects of the invention at least comprise:

firstly, when the phenolic resin is prepared by the method, the dosage of m-cresol, p-cresol and xylenol is controlled, and p-cresol and formaldehyde with weak reaction activity are prepared into prepolymer in advance, so that the o-o' linkage degree in the finally obtained phenolic resin is improved, and the molecular weight distribution is narrow.

Secondly, a certain amount of 3,3 '-dimethyl-4, 4' -biphenol, spirodiphenol and 2-hydroxy-1-hydroxymethyl naphthalene are added into the inventive photoresist phenolic resin, and the three exert synergistic action in a certain proportion range, so that the heat resistance of the obtained phenolic resin, the resolution and the photosensitivity of the obtained photoresist are simultaneously improved, and the defect that the performances are lost in the prior art is overcome.

The phenolic resin with excellent comprehensive performance is prepared by a three-section production process, the softening temperature is about 136 ℃, the weight average molecular weight is 8000-12000, the molecular weight distribution is narrow after testing, and the phenolic resin is used as the film-forming resin of the I-line photoresist, and the resolution and the photosensitivity of the photoresist are improved.

Drawings

FIG. 1 is a post exposure image of a photoresist obtained from the phenolic resin prepared in example 1;

FIG. 2 is a post exposure image of a photoresist from the phenolic resin made in example 2;

FIG. 3 is a post exposure image of a photoresist obtained from the phenolic resin prepared in comparative example 1;

FIG. 4 is a post exposure image of a photoresist obtained from the phenolic resin prepared in comparative example 2.

Detailed Description

The invention is further described with reference to the following examples, which are not intended to limit the scope of the invention.

The agents and instruments used in the examples of the present invention are conventional reagents and instruments commercially available in the art unless otherwise specified. In the examples of the present invention, "parts" are parts by mass unless otherwise specified, and "%" are mass percentages unless otherwise specified.

Example 1

(S1) adding 50 parts of p-cresol, 90 parts of 37% formaldehyde aqueous solution and 1g of sodium hydroxide into a reaction kettle, heating to 50 ℃ for reaction for 2 hours, adding dilute hydrochloric acid for neutralization, and washing a product to be neutral to obtain a prepolymer;

(S2) fully dissolving the prepolymer obtained in the step (S1), 55 parts of m-cresol, 8 parts of 3, 5-xylenol, 8 parts of 2-hydroxy 1-hydroxymethyl naphthalene, 180 parts of 37% formaldehyde and 0.9 part of oxalic acid by 500 parts of ethylene glycol monomethyl ether, uniformly stirring, and continuously heating to 90 ℃ for reaction for 2 hours;

(S3) continuing to heat to 95 ℃, slowly adding 40 parts of ethylene glycol monomethyl ether dissolved with 6 parts of 3,3 '-dimethyl-4, 4' -biphenol and 0.5 part of oxalic acid, reacting for 2 hours, finally adding 4 parts of spirocyclic diphenol, continuing to react for 2 hours, washing the final product for multiple times by using deionized water of which the amount is 3 times that of the product, and drying in vacuum for 5 hours at the temperature of 0.01MPa and 80 ℃ to obtain the modified phenolic resin.

Examples 2 to 11, comparative examples 1 to 3

The other conditions were the same as in example 1 except that the amount of the materials added was different, and the mass parts of the materials added in the examples are shown in table 1 below, to finally obtain a modified phenol resin.

TABLE 1

Example 12

The formulation is identical to that of example 3, except that instead of a four-stage stepwise reaction sequence, the entire batch is added in a one-pot process and reacted at 90 ℃ for 6 h.

Application example 1

The phenolic resins obtained in the above examples and comparative examples were subjected to the following performance tests, and the results are shown in Table 2:

1. the weight average molecular weight and molecular weight distribution were determined by GPC gel chromatography using a Waters 1515 gel chromatograph with tetrahydrofuran as the mobile phase and monodisperse polystyrene as the standard.

2. Testing of free aldehydes and free phenols was performed using shimadzu gas chromatography GC.

3. Softening temperature: according to GB/T8146-2003, the test result is obtained by a ring and ball method. Specifically, a resin sample is placed in a copper ring, the temperature is slowly increased, and the falling temperature of a steel ball is taken as the softening temperature. The steel ball has a diameter of 9.5mm, a weight of 3.5g and a non-rust surface.

TABLE 2

Application example 2

The phenolic resins of examples and comparative examples are used as film-forming resins of photoresists, and the specific components are that 100 parts of the phenolic resin prepared in the examples or the comparative examples is dissolved in 400 parts of electronic-grade Propylene Glycol Methyl Ether Acetate (PGMEA), 50 parts of butyl lactate, 15 parts of photosensitizer 2.3,4, 4' -tetrahydroxybenzophenone-1, 2-diazonaphthoquinone-4-sulfonate, 0.5 part of leveling agent F-563 and 0.5 part of crosslinking agent KF-54 are added, and after stirring and complete dissolution, the mixture is filtered by a 0.2 mu m filter to obtain the photoresist composition.

The resolution of the resulting photoresist was tested as follows: taking a wafer with the surface coated with silicon dioxide, spin-coating the photoresist obtained by the method on the surface of a silicon dioxide film, coating the photoresist with the thickness of 1.5 mu m, pre-baking the photoresist with a heating plate at 120 ℃ for 2min to volatilize a solvent, curing the photoresist to form a film, covering a mask with a certain micro pattern, irradiating the photoresist at 365nm for 30s, baking the photoresist at 120 ℃ for 60s, developing the photoresist with 2.38% tetramethylammonium hydroxide (TMAH) aqueous solution serving as a developer for 30s, washing the photoresist with deionized water, drying the photoresist to obtain a corresponding pattern, and testing the resolution of the micro pattern by using a scanning electron microscope. The photosensitivity test is based on the change of exposure energy, and the photosensitivity is determined by the energy of complete dissolution of the photoresist film layer at 23 +/-1 ℃. The results are shown in table 3 below:

TABLE 3