A positive photoresist composition, a preparation method thereof, and a photoresist pattern forming method

Abstract

The present application relates to photoresist technical field, more particularly, the present application relates to a kind of positive photoresist composition and preparation method and photoresist pattern forming method.The present application provides a rectangular topography with small film thickness loss in unexposed area, high degree of vertical, also simultaneously with high sensitivity, high contrast and high resolution positive resist composition;By adding a small amount of modified phenolic resin B containing specific substituted phenol monomer, and conventional phenolic resin A jointly, the positive photoresist composition obtained can significantly improve the vertical photoresist topography in the case of high sensitivity, so that the photoresist topography changes from 70° positive trapezoidal to rectangular topography above 80°, so that the photoresist can meet the demand of fine line width processing, and the inventor finds that adding perfluoroalkyl acrylate E as photoresist additive can significantly improve the unexposed film thickness loss of photoresist, significantly improve the contrast of photoresist.

Description

Technical Field

[0001] This invention relates to the field of photoresist technology, and more specifically, to a positive photoresist composition, its preparation method, and its photoresist patterning method. Background Technology

[0002] Photolithography essentially involves using photosensitive materials and controlled exposure to create three-dimensional patterns on a substrate surface. It's the process of precisely transferring circuit patterns from a photomask to a photoresist film on the substrate surface. Photoresist, also known as photoresist, is a commonly used functional material in the photolithography process in the electronics industry. Its chemical and physical properties directly affect its performance in large-scale integrated circuits. Based on their chemical reaction mechanisms and development principles, photoresists can be classified into positive and negative photoresists. Positive photoresists, under the irradiation of an energy beam (light beam, electron beam, ion beam, etc.), primarily undergo degradation reactions, replicating the same pattern from the photomask to the substrate surface. Negative photoresists, under the irradiation of an energy beam (light beam, electron beam, ion beam, etc.), primarily undergo cross-linking reactions, replicating the opposite pattern from the photomask to the silicon wafer surface. As the market demands higher density integration of integrated circuits, device feature sizes are continuously decreasing, and processing lines are becoming increasingly finer, placing higher demands on the resolution of photoresists. Generally, finer linewidths require thinner photoresist films. However, besides balancing resolution, the choice of photoresist also requires sufficient thickness to block etching. Photoresist thickness significantly impacts resolution, manifesting as a limit to the aspect ratio. Specifically, after development, the photoresist itself is prone to collapse due to its inability to support narrow and high lines. Therefore, the aspect ratio of photoresist generally does not exceed 5:1, and in process technology, it often does not exceed 3:1. Positive photoresist has a higher aspect ratio than negative photoresist, allowing for thicker photoresist films in fine-linewidth processes. On the other hand, during development, as the developer solvent penetrates the photoresist, most negative photoresist undergoes deformation and swelling, altering the pattern size and limiting the resolution of negative photoresist. In process technologies with feature sizes smaller than 3μm, the feature size will significantly differ from the specified size. In summary, compared with negative photoresist, positive photoresist has a higher aspect ratio and less expansion, which can be used for thicker photoresist protective layers. It is beneficial to provide better step coverage and defect protection, as well as greater dry etching resistance, and can provide the same resolution. Therefore, positive photoresist is more suitable for large-scale integrated circuits.

[0003] Ideally, exposure processes deliver exposure radiation only to the photoresist area where the pattern will be formed. However, in actual exposure processes, due to diffraction and scattering, energy propagates divergently, resulting in a specific distribution of irradiation received by the photoresist. The contrast and sensitivity of the photoresist are typically measured by exposing a certain thickness of photoresist at different exposure doses. Figure 4As shown, the vertical axis represents the film thickness remaining after photoresist development, and the horizontal axis represents the exposure dose. D0 is the minimum unexposed dose required to start the photochemical reaction, and D100 is the minimum unexposed dose required for full photoresist exposure.

[0004] For positive photoresist, during development, the photoresist at exposure energy greater than D100 completely dissolves, while areas with exposure energy less than D100 but greater than D0 undergo localized dissolution (the transition zone shown in the image). Therefore, the developed photoresist cross-section has a certain angled slope. The steepness of the transition from the exposed to the unexposed area is not the ideal 90°. A less perpendicular photoresist cross-section will lead to wider lines being etched on the etched layer, reducing resolution. The contrast of the photoresist can also be measured by the contrast of its thickness change during development. The smaller the thickness loss of the unexposed area after development, the better the contrast. Contrast is the steepness of the photoresist from the exposed to the unexposed area. Generally, the more perpendicular the cross-section of the developed photoresist, the higher its contrast and resolution. High contrast, resulting in vertical photoresist sidewalls, is ideal. Furthermore, since dry etching processes typically corrode the photoresist material to some extent, severe thickness loss in the unexposed area during development leads to less residual thickness in the unexposed area after development, resulting in poor etching resistance and difficulty in protecting the pattern during subsequent etching processes.

[0005] In photolithography, conventional positive photoresist compositions mainly consist of photosensitive phenolic varnish resin and quinone-azide-containing compounds as photosensitizers. This type of positive photoresist composition is suitable for practical applications in the manufacture of semiconductor devices and TFT-LCD display elements. However, high-sensitivity positive photoresist compositions can suffer from significant thickness losses in unexposed areas. Furthermore, the resulting pattern after exposure tends to be a trapezoid rather than a highly vertical rectangle. In processing with fine linewidths (<1μm) or thin films with resist thicknesses of 1.5μm or less, the patterns formed by these conventional positive photoresist compositions can lead to processing defects during ion implantation or plasma etching. Attached Figure Description

[0006] Figure 1 The angle formed between the bevel of the photoresist pattern prepared by the photoresist composition provided in Example 3 and the silicon wafer.

[0007] Figure 2 The angle formed between the bevel of the photoresist pattern prepared by the photoresist composition provided in Example 6 and the silicon wafer.

[0008] Figure 3 The angle formed between the bevel of the photoresist pattern prepared by the photoresist composition provided in Example 4 and the silicon wafer.

[0009] Figure 4 This is a graph showing the relationship between photoresist exposure and photoresist residue. Summary of the Invention

[0010] To address the aforementioned problems, a first aspect of the present invention provides a positive photoresist composition, wherein the raw materials for preparing the photoresist composition, by weight percentage, comprise:

[0011] 50–95 wt% solvent D;

[0012] 5–50 wt% solids content;

[0013] The solid components, by weight percentage, include:

[0014] 30–90 wt% of phenolic varnish resin A with a weight-average molecular weight of 3,000–20,000;

[0015] 5–30 wt% of modified phenolic varnish resin B with a weight average molecular weight of 5000–25000;

[0016] 4–40 wt% of compound C containing quinone azide groups.

[0017] As a preferred embodiment of the present invention, the modified phenolic varnish resin B is obtained by the condensation of phenol and aldehyde, wherein the phenol includes substituted phenols, and the structural formula of the substituted phenols is shown in Formula 1:

[0018]

[0019] R1 is selected from phenyl, CH3, CH2CH3 or H, R2 is selected from H, CH3 or CH2CH3, and R3 is selected from H, CH3 or CH2CH3.

[0020] As a preferred embodiment of the present invention, the phenol further includes one or more of o-butylphenol, m-butylphenol, p-butylphenol, p-methylphenol, and m-methylphenol.

[0021] As a preferred technical solution of the present invention, the molar ratio of p-methylphenol, m-methylphenol and substituted phenol is (27-61):(37-102):(1-21).

[0022] As a preferred embodiment of the present invention, the solid component further includes perfluoroalkyl acrylate E.

[0023] As a preferred embodiment of the present invention, the number of carbon atoms in the perfluoroalkyl group of the perfluoroalkyl acrylate E is greater than or equal to 5.

[0024] As a preferred embodiment of the present invention, the perfluoroalkyl acrylate E accounts for 0.01 to 5 wt% of the solid content.

[0025] As a preferred embodiment of the present invention, the compound C containing quinone azide is at least one of a complete esterification, partial esterification, amidation, or partial amidation of a polyhydroxyphenyl compound and a sulfonic acid compound containing quinone diazide.

[0026] A second aspect of the present invention provides a method for preparing the positive photoresist composition as described above, comprising the following steps:

[0027] The solid component is added to solvent D and mixed to obtain the photoresist composition.

[0028] A third aspect of the present invention provides a method for forming a photoresist pattern, comprising the following steps: coating a positive photoresist composition as described above onto a substrate surface, drying, exposing, developing, and cleaning to obtain the photoresist pattern.

[0029] Compared with the prior art, the present invention has the following beneficial effects: The present invention provides a positive photoresist composition with small film thickness loss in the unexposed area, high verticality, and a rectangular morphology, while also possessing high sensitivity, high contrast, and high resolution; by adding a small amount of modified phenolic varnish resin B containing a specific substituted phenolic monomer, and working together with conventional phenolic varnish resin A, the obtained positive photoresist composition can still significantly improve the vertical morphology of the photoresist under high sensitivity, changing the photoresist morphology from a 70° trapezoidal shape to a rectangular morphology of more than 80°, enabling the photoresist to meet the requirements of fine linewidth processing. Furthermore, the inventors have discovered that adding perfluoroalkyl acrylate E as a photoresist additive can significantly improve the film thickness loss in the unexposed area of ​​the photoresist, giving the photoresist strong etching resistance, thereby preventing processing defects during photoresist pattern etching and significantly improving the contrast of the photoresist. Detailed Implementation

[0030] The invention will be more readily understood by referring to the following detailed description of preferred embodiments and included examples. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. In case of conflict, the definitions in this specification shall prevail.

[0031] As used herein, the terms “prepared from” and “comprising” are synonymous. 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 composition, step, method, article, or apparatus.

[0032] The conjunction "composed of..." excludes any unspecified elements, steps, or components. If used in a claim, this phrase makes the claim closed, excluding materials other than those described, except for associated conventional impurities. When the phrase "composed of..." appears in a clause of the body of a claim rather than immediately following it, it limits only the elements described in that clause; other elements are not excluded from the claim as a whole.

[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 to 5” is disclosed, the described range should be interpreted as including the ranges “1 to 4”, “1 to 3”, “1 to 2”, “1 to 2 and 4 to 5”, “1 to 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] The singular form includes the plural objects of discussion unless the context clearly indicates otherwise. "Optional" or "any one" means that the matter or event described thereafter may or may not occur, and the description includes both the possibility that the event occurs and the possibility that the event does not occur.

[0035] Approximate terms used in the specification and claims to modify quantities indicate that the invention is not limited to that specific quantity, but also includes acceptable modifications close to that quantity that do not alter the relevant essential function. Correspondingly, the use of "about," "approximately," etc., to modify a numerical value means that the invention is not limited to that precise value. In some instances, approximate terms may correspond to the precision of the instrument used to measure the value. In this application's specification and claims, scope definitions can be combined and / or interchanged, unless otherwise stated, these scopes include all subscopes contained therein.

[0036] Furthermore, the indefinite articles “a” and “an” preceding the elements or components of this invention do not impose any limitation on the quantity requirement (i.e., the number of times) of the elements or components. Therefore, “an” or “a” should be interpreted as including one or at least one, and the singular form of an element or component also includes the plural form, unless the quantity clearly refers to the singular form.

[0037] The present invention will be described below through specific embodiments, but is not limited to the specific embodiments given below.

[0038] The first aspect of this invention provides a positive photoresist composition, wherein the raw materials for preparing the photoresist composition, by weight percentage, comprise:

[0039] 50–95 wt% solvent D;

[0040] 5–50 wt% solids content.

[0041] Solvent D

[0042] Solvent D is mainly used to disperse the photoresist, enabling coating and improving coating uniformity. Examples of solvents include, but are not limited to, propylene glycol alkyl ether acetate, ethyl lactate (EL), propylene glycol monomethyl ether (PGME), ethyl 3-ethoxypropionate, diethylene glycol monobutyl ether, benzyl alcohol, and one or more combinations thereof. The solvent D of this invention constitutes 50-95 wt% of the composition. As an example, the weight percentage of the solvent in the composition can be 50 wt%, 55 wt%, 60 wt%, 65 wt%, 70 wt%, 75 wt%, 80 wt%, 85 wt%, 90 wt%, or 95 wt%, preferably 65-89 wt%.

[0043] Considering storage stability, biosafety, and good solubility, the solvent D in this invention is selected from at least one of propylene glycol methyl ether acetate (PGMEA), EL, PGME, ethyl 3-ethoxypropionate, diethylene glycol monobutyl ether, and benzyl alcohol. Among these, PGMEA, EL, and PGME are low-boiling-point solvents (high volatility), while ethyl 3-ethoxypropionate, diethylene glycol monobutyl ether, and benzyl alcohol are high-boiling-point solvents (low volatility). For excellent coating uniformity and flowability, in a preferred embodiment, the solvent in this invention is selected from the group consisting of at least one of PGMEA, EL, and PGME, and at least one of ethyl 3-ethoxypropionate, diethylene glycol monobutyl ether, and benzyl alcohol.

[0044] [Solid Content]

[0045] Solid components refer to all other components besides the solvent. The solid components of the present invention account for 5 to 50 wt% of the composition. As an example, the weight percentage of the solid components of the present invention in the composition can be 10 wt%, 15 wt%, 20 wt%, 25 wt%, 30 wt%, 35 wt%, 40 wt%, 45 wt%, 50 wt%, etc., preferably 10 to 40 wt%.

[0046] In one embodiment, the solid components of the present invention, by weight percentage, comprise:

[0047] 30–90 wt% of phenolic varnish resin A with a weight-average molecular weight of 3,000–20,000;

[0048] 5–30 wt% of modified phenolic varnish resin B with a weight average molecular weight of 3000–20000;

[0049] 4–40 wt% of compound C containing quinone azide groups.

[0050] Phenolic varnish resin A

[0051] The phenolic varnish resin A used in this invention can be understood as a phenolic varnish resin well known in the art, which can be obtained by condensation of phenol and aldehyde in the presence of a catalyst, mainly providing good film-forming and developing properties. As an example, the phenols that can be used include phenol, o-methylphenol, m-methylphenol, p-methylphenol, o-ethylphenol, m-ethylphenol, p-ethylphenol, o-butylphenol, m-butylphenol, p-butylphenol, 2,3-xylenol, 2,4-xylenol, 2,5-xylenol, 2,6-xylenol, 3,4-xylenol, 3,5-xylenol, 2,3,5-trimethylphenol, 3,4,5-trimethylphenol, catechol, resorcinol, 1,2,3-phenylpyrogallol, α-naphthol, and β-naphthol; exemplary aldehydes include formaldehyde, oligooxymethylene, acetaldehyde, and benzaldehyde.

[0052] In a preferred embodiment, the phenolic varnish resin A of the present invention is obtained by condensation of m-methylphenol, p-methylphenol and formaldehyde.

[0053] In a preferred embodiment, the molar ratio of m-methylphenol to p-methylphenol in the raw materials for preparing the phenolic varnish resin A of the present invention is (3-8):(3-8).

[0054] In a preferred embodiment, the phenolic varnish resin A used in this invention accounts for 30-90 wt% of the solid content. As an example, the weight percentage of the phenolic varnish resin A in the solid content can be 30 wt%, 35 wt%, 40 wt%, 45 wt%, 50 wt%, 55 wt%, 60 wt%, 65 wt%, 70 wt%, 75 wt%, 80 wt%, 85 wt%, 90 wt%, etc., preferably 50-80 wt%.

[0055] Modified phenolic varnish resin B

[0056] When only phenolic varnish resin A is used, the developed photoresist cross-section is a slope with low verticality. The inventors found that adding modified phenolic varnish resin B can improve the sidewall morphology of the photoresist, making it form a rectangle with high verticality after exposure and development. In one embodiment, the modified phenolic varnish resin B of the present invention is obtained by condensation of phenol and aldehyde, wherein the phenol includes substituted phenol, and the structural formula of the substituted phenol is shown in formula (1):

[0057]

[0058] R1 is selected from phenyl, CH3, CH2CH3 or H, R2 is selected from H, CH3 or CH2CH3, and R3 is selected from H, CH3 or CH2CH3. It should be noted that, in order to avoid the structure of substituted phenols being the same as that of m-methylphenol and p-methylphenol, when R1 and R2 are hydrogen atoms, R3 is selected from H or CH2CH3; when R1 and R3 are hydrogen atoms, R2 is selected from H or CH2CH3.

[0059] In a preferred embodiment, the phenol in the raw material for preparing the phenolic varnish resin B of the present invention further includes one or more of o-butylphenol, m-butylphenol, p-butylphenol, p-methylphenol, and m-methylphenol.

[0060] The inventors discovered that modified phenolic varnish resin B can more rapidly undergo a coupling and cross-linking reaction with diazo compounds containing azido groups, resulting in a denser coating that effectively prevents the developer from dissolving and penetrating. When combined with the phenolic varnish resin A mentioned above, it results in a faster alkali dissolution rate of the photoresist in the exposed area after exposure, leading to better development performance. At the same time, the photoresist surface in the low-exposure area is less prone to development, thereby improving the morphology of the photoresist pattern.

[0061] In a preferred embodiment, the phenols in the raw materials for preparing the modified phenolic varnish resin B of the present invention include p-methylphenol, m-methylphenol and substituted phenols, with a molar ratio of (27-61):(37-102):(1-21).

[0062] The molecular weight distribution coefficient (MGC) is defined as the ratio of weight-average molecular weight to number-average molecular weight. An excessively high MGC results in uneven development. In a preferred embodiment, the MGC of the modified phenolic varnish resin B is between 2 and 5.

[0063] In a preferred embodiment, the modified phenolic varnish resin B of the present invention accounts for 5 to 30 wt% of the solid content. As an example, the weight percentage of the modified phenolic varnish resin B of the present invention in the solid content can be 5 wt%, 8 wt%, 10 wt%, 12 wt%, 15 wt%, 18 wt%, 20 wt%, 22 wt%, 25 wt%, 28 wt%, 30 wt%, preferably 10 to 20 wt%.

[0064] Furthermore, the inventors discovered that selecting appropriate molecular weights for phenolic varnish resin A and modified phenolic varnish resin B is beneficial for forming good photoresist patterns. In a preferred embodiment, the weight-average molecular weight of phenolic varnish resin A is 3000–20000, and the weight-average molecular weight of modified phenolic varnish resin B is 5000–25000. Excessively high resin molecular weight leads to poor resin alkali solubility, requiring higher exposure doses to ensure complete photoresist reaction, resulting in longer exposure times, impacting production efficiency and limiting capacity. Conversely, excessively low resin molecular weight leads to excessively high resin alkali dissolution rates, resulting in poor photoresist resistance and ion implantation resistance. This makes it difficult to protect the pattern in subsequent etching processes, and the addition of photosensitive materials results in poor solubility. Unexposed portions of the photoresist layer have excessively high solubility in the developer, leading to significant thickness loss in unexposed areas and difficulty in forming highly vertical rectangular photoresist patterns. Furthermore, excessively rapid resin alkali dissolution rates also reduce process tolerance, affecting process stability. As an example, the weight-average molecular weight of the phenolic varnish resin A described in this invention can be 3000, 4000, 5000, 6000, 7000, 8000, 9000, 10000, 11000, 12000, 13000, 14000, 15000, 16000, 17000, 18000, 19000, 20000, etc., preferably 8000 to 15000; as ... The weight-average molecular weight of the modified phenolic varnish resin B can be 5000, 6000, 7000, 8000, 9000, 10000, 11000, 12000, 13000, 14000, 15000, 16000, 17000, 18000, 19000, 20000, 21000, 22000, 23000, 24000, 25000, etc., preferably 9000 to 20000.

[0065] Compound C containing quinone azide group

[0066] The azido-containing compound C described in this invention is a photosensitive material. The inventors discovered that the aforementioned azido-containing compound can be added to phenolic resin as a dissolution inhibitor, reducing the alkaline dissolution rate of the phenolic resin and creating a solubility barrier. During exposure, the photosensitive material undergoes photochemical decomposition to produce carboxylic acids, which can improve the solubility of the phenolic resin in the exposed area of ​​the photoresist. Therefore, the azido-containing compound described in this invention can achieve the basic requirement that positive photoresists are difficult to dissolve in the developing solution before exposure and easily soluble after exposure.

[0067] In a preferred embodiment, the quinone-containing compound of the present invention is selected from at least one of the following: a complete esterification, a partial esterification, an amidation, or a partial amidation of a polyhydroxyphenyl compound and a quinone-containing sulfonic acid compound.

[0068] In a preferred embodiment, the compound C containing a quinone azide group of the present invention is a partial esterification of a polyhydroxyphenyl compound and a sulfonic acid compound containing a quinone diazide group.

[0069] In a preferred embodiment, the polyhydroxyphenyl compound of the present invention is selected from one of polyhydroxybenzophenone compounds, bis[(poly)hydroxyphenyl]alkyl compounds, tri(hydroxyphenyl)methanes or their methyl derivatives, bis(cyclohexylhydroxyphenyl)(hydroxyphenyl)methanes or their methyl derivatives; the polyhydroxybenzophenone compound is selected from 2,3,4-trihydroxybenzophenone, 2,4,4'-trihydroxybenzophenone, 2,4,6-trihydroxybenzophenone, 2,3,6-trihydroxybenzophenone, and 2,3,4-trihydroxy-2'-methylbenzophenone. At least one of 2,3,4,4'-tetrahydroxybenzophenone, 2,2',4,4'-tetrahydroxybenzophenone, 2,3',4,4',6-pentahydroxybenzophenone, 2,2',3,4,4'-pentahydroxybenzophenone, 2,2',3,4,5-pentahydroxybenzophenone, 2,3',4,4',5',6-hexahydroxybenzophenone, and 2,3,3',4,4',5'-hexahydroxybenzophenone; the bis[(poly)hydroxyphenyl]alkyl compound is selected from bis(2,4-dihydroxyphenyl)methane and bis(2,3,4-trihydroxyphenyl)methane. At least one of 2-(4-hydroxyphenyl)-2-(4'-hydroxyphenyl)propane, 2-(2,4-dihydroxyphenyl)-2-(2',4'-dihydroxyphenyl)propane, 2-(2,3,4-trihydroxyphenyl)-2-(2',3',4'-trihydroxyphenyl)propane, 4,4'-{1-[4-[2-(4-hydroxyphenyl)-2-propyl]phenyl]ethylidene}bisphenol, and 3,3'-dimethyl-{1-[4-[2-(3-methyl-4-hydroxyphenyl)-2-propyl]phenyl]ethylidene}bisphenol; said tri(hydroxyphenyl)propane The alkane or its methyl-substituted derivative is selected from at least one of tris(4-hydroxyphenyl)methane, bis(4-hydroxy-3,5-dimethylphenyl)-4-hydroxyphenylmethane, bis(4-hydroxy-2,5-dimethylphenyl)-4-hydroxyphenylmethane, bis(4-hydroxy-3,5-dimethylphenyl)-2-hydroxyphenylmethane, bis(4-hydroxy-2,5-dimethylphenyl)-2-hydroxyphenylmethane, bis(4-hydroxy-2,5-dimethylphenyl)-3,4-dihydroxyphenylmethane, and bis(4-hydroxy-3,5-dimethylphenyl)-3,4-dihydroxyphenylmethane;The bis(cyclohexylhydroxyphenyl)(hydroxyphenyl)methanes or their methyl derivatives are selected from bis(3-cyclohexyl-4-hydroxyphenyl)-3-hydroxyphenylmethane, bis(3-cyclohexyl-4-hydroxyphenyl)-2-hydroxyphenylmethane, bis(3-cyclohexyl-4-hydroxyphenyl)-4-hydroxyphenylmethane, bis(5-cyclohexyl-4-hydroxy-2-methylphenyl)-2-hydroxyphenylmethane, bis(5-cyclohexyl-4-hydroxy-2-methylphenyl)-3-hydroxyphenylmethane, bis(5-cyclohexyl-4-hydroxy-2-methylphenyl)-4-hydroxyphenylmethane, bis(3-cyclohexyl-2-hydroxy ... At least one of the following: bis(5-cyclohexyl-4-hydroxy-3-methylphenyl)-4-hydroxyphenylmethane, bis(5-cyclohexyl-4-hydroxy-3-methylphenyl)-3-hydroxyphenylmethane, bis(5-cyclohexyl-4-hydroxy-3-methylphenyl)-2-hydroxyphenylmethane, bis(3-cyclohexyl-2-hydroxyphenyl)-4-hydroxyphenylmethane, bis(3-cyclohexyl-2-hydroxyphenyl)-2-hydroxyphenylmethane, bis(5-cyclohexyl-2-hydroxy-4-methylphenyl)-2-hydroxyphenylmethane, and bis(5-cyclohexyl-2-hydroxy-4-methylphenyl)-4-hydroxyphenylmethane.

[0070] In a preferred embodiment, the quinone-diazido-containing sulfonic acid compound of the present invention is selected from naphthoquinone-1,2-diazido-5-sulfonic acid or naphthoquinone-1,2-diazido-4-sulfonic acid, o-anthraquinone diazidosulfonic acid, and other sulfonic acids having a quinone diazido-group.

[0071] The compound C containing azido groups described in this invention accounts for 4-40 wt% of the solid components. Insufficient photosensitive material will fail to effectively inhibit the solubility of the photoresist, leading to excessive solubility in the unexposed portion of the resist layer, severe film thickness loss, and poor etching resistance, making it difficult to protect the pattern in subsequent etching processes. Conversely, excessive material will require an exposure dose far exceeding the acceptable dosage for the photolithography process, yet still fail to ensure the resin dissolves in the alkaline developer after exposure. In fact, the photolysis and rearrangement of the photosensitive material involves a side reaction that does not produce carboxylic acids but releases nitrogen gas, which can cause resin cracking during exposure. The amount of photosensitive material used in this invention ensures that the photoresist is poorly soluble in the developer before exposure, achieving sufficient solubility at the acceptable exposure dose for the photolithography process. As an example, the weight percentage of the compound C containing azido group in the solid components of the present invention can be 4 wt%, 10 wt%, 15 wt%, 10 wt%, 15 wt%, 20 wt%, 25 wt%, 30 wt%, 35 wt%, 40 wt%, etc., preferably 15 to 30 wt%.

[0072] In a preferred embodiment, the solid component of the present invention further includes perfluoroalkyl acrylate E.

[0073] Perfluoroalkyl acrylate E

[0074] While using component C and resin alone can suppress the dissolution of resin in alkaline developer in low-exposure areas to some extent, the film thickness loss in unexposed areas is still significant. The inventors discovered that when perfluoroalkyl acrylate is added to the photoresist composition, it reacts with other components to float on the surface after film formation and bond with the surface photoresist to form a thin film. This improves the leveling properties of the composition and enhances its coating performance. Furthermore, its fluorine content makes the surface relatively difficult to wet, and the film bonded to the unexposed photoresist increases its resistance to alkaline developer, thereby reducing the film thickness loss in unexposed areas without affecting the development speed in exposed areas.

[0075] In a preferred embodiment, the perfluoroalkyl group in the perfluoroalkyl acrylate E of the present invention has a carbon number greater than or equal to 5.

[0076] In a preferred embodiment, the number of carbon atoms in the perfluoroalkyl group of the perfluoroalkyl acrylate E is less than or equal to 20;

[0077] In a preferred embodiment, the number of carbon atoms in the perfluoroalkyl group of the perfluoroalkyl acrylate E is 5 to 15.

[0078] In a preferred embodiment, the perfluoroalkyl acrylate E is selected from at least one of perfluorodecylethyl acrylate, perfluorooctylethyl acrylate, and perfluorooctylpropyl acrylate. This invention does not specifically limit the structure of the acrylate in the perfluoroalkyl acrylate E; examples include perfluoromethyl acrylate and perfluoroethyl acrylate.

[0079] In a preferred embodiment, the perfluoroalkyl acrylate E of the present invention accounts for 0.01 to 5 wt% of the solid content. Excessive perfluoroalkyl acrylate will absorb exposure energy, leading to increased demand for exposure dose and consequently longer exposure times, resulting in lower production efficiency. Insufficient perfluoroalkyl acrylate content will prevent adequate improvement in film thickness loss in unexposed areas. As an example, the weight percentage of perfluoroalkyl acrylate E in the solid content can be 0.01 wt%, 0.05 wt%, 0.1 wt%, 0.5 wt%, 1 wt%, 1.5 wt%, 2 wt%, 2.5 wt%, 3 wt%, 3.5 wt%, 4 wt%, 4.5 wt%, 5 wt%, etc., preferably 0.05 to 0.5 wt%.

[0080] A second aspect of the present invention provides a method for preparing the positive photoresist composition as described above, comprising the following steps:

[0081] The solid component is added to solvent D and mixed to obtain the photoresist composition.

[0082] Specifically, the preparation method of the positive photoresist composition of the present invention comprises the following steps: adding 30-90 wt% of phenolic varnish resin A, 5-30 wt% of modified varnish phenolic resin B, 4-40 wt% of compound C containing azido groups, and 0.01-5 wt% of perfluorodecyl acrylate to solvent D, and stirring to obtain the photoresist composition. The solvent D constitutes 50-95 wt% of the photoresist composition by weight.

[0083] A third aspect of this invention provides a method for forming a photoresist pattern, comprising the following steps: coating a positive photoresist composition as described above onto a substrate surface, drying, exposing, developing, and cleaning to obtain the photoresist pattern. The coating method of this invention can be performed by spin coating or the like, with a coating speed of 1000–2000 rpm; the drying time is 40–120 s and the drying temperature is 80–120°C; the exposure energy is 40–60 mJ; after exposure, drying is performed at 100–130°C for 50–80 s; and the developing temperature is 20–30°C and the developing time is 50–80 s.

[0084] Example

[0085] The present invention will now be described in detail through embodiments. It should be noted that the following embodiments are only for further illustration of the present invention and should not be construed as limiting the scope of protection of the present invention. Non-essential improvements and adjustments made by those skilled in the art based on the above description of the present invention still fall within the scope of protection of the present invention.

[0086] Phenolic varnish resin A

[0087] A1: A linear phenolic varnish resin obtained by condensation of m-methylphenol and p-methylphenol with formaldehyde in a molar ratio of 6:4, with a weight-average molecular weight of 8000.

[0088] A2: A linear phenolic varnish resin obtained by condensation of m-methylphenol and p-methylphenol with formaldehyde in a molar ratio of 6:4, with a weight-average molecular weight of 11080.

[0089] A3: A linear phenolic varnish resin obtained by condensation of m-methylphenol and p-methylphenol with formaldehyde in a molar ratio of 4:6, with a weight-average molecular weight of 9500.

[0090] A4: A linear phenolic varnish resin obtained by condensation of m-methylphenol and p-methylphenol with formaldehyde in a molar ratio of 6:4, with a weight-average molecular weight of 10550.

[0091] A5: A linear phenolic varnish resin obtained by condensation of m-methylphenol and p-methylphenol with formaldehyde in a molar ratio of 5:5, with a weight-average molecular weight of 13020.

[0092] A6: A linear phenolic varnish resin obtained by condensation of m-methylphenol and p-methylphenol with formaldehyde in a molar ratio of 5:5, with a weight-average molecular weight of 12550.

[0093] A7: A linear phenolic varnish resin obtained by condensation of m-methylphenol and p-methylphenol with formaldehyde in a molar ratio of 6:4, with a weight-average molecular weight of 14450.

[0094] A8: A linear phenolic varnish resin obtained by condensation of m-methylphenol and p-methylphenol with formaldehyde in a molar ratio of 6:4, with a weight-average molecular weight of 8500.

[0095] Modified phenolic varnish resin B

[0096] B1: A linear phenolic varnish resin obtained by condensation of p-methylphenol, m-methylphenol and substituted phenols with formaldehyde in a molar ratio of 31:73:18, with a weight-average molecular weight of 13406.

[0097] The structural formula of the substituted phenol is:

[0098]

[0099] R1 is H, R2 is CH3, and R3 is CH3.

[0100] B2: A linear phenolic varnish resin obtained by condensation of p-methylphenol, m-methylphenol and substituted phenol with formaldehyde in a molar ratio of 46:80:4, with a weight-average molecular weight of 14060.

[0101] The structural formula of the substituted phenol is:

[0102]

[0103] R1 is phenyl, R2 is H, and R3 is H.

[0104] B3: A linear phenolic varnish resin obtained by condensation of p-methylphenol, m-methylphenol and substituted phenols with formaldehyde in a molar ratio of 32:37:13, with a weight-average molecular weight of 9015.

[0105] The structural formula of the substituted phenol is:

[0106]

[0107] R1 is H, R2 is CH3, and R3 is CH3.

[0108] B4: A linear phenolic varnish resin obtained by condensation of p-methylphenol, m-methylphenol and substituted phenol with formaldehyde in a molar ratio of 44:74:21, with a weight-average molecular weight of 15280.

[0109] The structural formula of the substituted phenol is:

[0110]

[0111] R1 is H, R2 is CH3, and R3 is CH3.

[0112] B5: A linear phenolic varnish resin obtained by condensation of p-methylphenol, m-methylphenol and substituted phenols with formaldehyde in a molar ratio of 31:73:18, with a weight-average molecular weight of 11037.

[0113] The structural formula of the substituted phenol is:

[0114]

[0115] R1 is H, R2 is CH3, and R3 is CH2CH3.

[0116] B6: A linear phenolic varnish resin obtained by condensation of p-methylphenol, m-methylphenol and substituted phenols with formaldehyde in a molar ratio of 31:73:18, with a weight-average molecular weight of 11037.

[0117] The structural formula of the substituted phenol is:

[0118]

[0119] R1 is H, R2 is H, and R3 is H.

[0120] Compound C containing quinone azide group

[0121] C1: 2,3,4,4'-Tetrahydroxybenzophenone-1,2-diazidonaphthoquinone-5-sulfonate.

[0122] C2: 2,3,4-Trihydroxybenzophenone-1,2-diazidonaphthalene-5-sulfonate.

[0123] Solvent D

[0124] D1: Propylene glycol methyl ether acetate.

[0125] D2: Benzyl alcohol.

[0126] Perfluoroalkyl acrylate E

[0127] E1: Perfluorodecyl ethyl acrylate (CAS No.: 17741-60-5).

[0128] E2: Perfluorooctyl ethyl acrylate (CAS No.: 27905-45-9).

[0129] E3: Perfluorooctylpropyl acrylate (CAS No.: 1652-60-4).

[0130] E4: 2-(perfluorobutyl)ethyl acrylate (CAS No.: 52591-27-2).

[0131] The following is a description of the components used in the examples and comparative examples, in parts by weight, as shown in Table 1.

[0132] Table 1

[0133]

[0134] The present invention also provides a method for preparing the compositions provided in the embodiments and comparative examples as described above, comprising the following steps:

[0135] The raw materials for the preparation of the composition are mixed to obtain the photoresist composition.

[0136] Performance Evaluation

[0137] The positive photoresist compositions provided in the examples and comparative examples were spin-coated onto the surface of a 12-inch silicon wafer at 1500 rpm, dried at 100°C for 60 seconds, exposed using an I-Line stepper at 50 mJ, and then baked after exposure at 110°C for 60 seconds. The silicon wafer was then immersed in a 2.38% tetramethylammonium hydroxide aqueous solution for development at 23°C for 60 seconds, and rinsed with deionized water. Film thickness was then measured in the unexposed areas. After completion, the silicon wafer was sliced ​​and observed under SEM, and the unexposed film thickness loss and photoresist wall angle after development were calculated.

[0138] (1) The film thickness before and after development was measured using a Filmetrics F50 optical film thickness gauge. The film thickness loss of the unexposed part Δt = film thickness before development - film thickness of the unexposed part after development.

[0139] (2) Measurement of the photoresist pattern angle: After slicing the silicon wafer, a cross-sectional image was taken using a Hitachi SU8100 microscope. The image was magnified 50,000 times, and the angle was measured using SDM software. The measurement location was the angle formed by the inclined surface of the photoresist pattern and the silicon wafer. Three angles were measured, and their average value was calculated as the final angle θ formed by the inclined surface of the photoresist pattern and the substrate. Figure 1 , Figure 2 , Figure 3The angles formed between the inclined plane of the photoresist pattern prepared by the photoresist compositions provided in Examples 3, 6, and 4 and the silicon wafer can be seen. It can be seen that in different pattern structures, whether it is a line structure with a line / blank ratio of 1:1, a single line, or a large area blank at the interface with the photoresist, the angle is greater than 85°.

[0140] The results are shown in Table 2.

[0141] Table 2 Performance Characterization Tests

[0142]

[0143]

[0144] As shown in Table 2, the positive photoresist composition provided by the present invention can be used to prepare photoresist patterns. Under high sensitivity, it can still significantly improve the vertical morphology of the photoresist, enabling the photoresist to meet the requirements of fine linewidth processing. It can also significantly improve the film thickness loss of the photoresist in the unexposed area, giving the photoresist strong etching resistance, thereby preventing processing defects during photoresist pattern etching and significantly improving the contrast of the photoresist.

[0145] The foregoing examples are merely illustrative, used to explain some features of the method described in this invention. The appended claims are intended to claim the broadest possible scope, and the embodiments presented herein are merely illustrative of selected implementations based on combinations of all possible embodiments. Therefore, the applicant intends that the appended claims are not limited by the selection of examples illustrating the features of the invention. Some numerical ranges used in the claims also include sub-ranges within them, and variations within these ranges should also be interpreted as being covered by the appended claims where possible.

Claims

1. A positive photoresist composition, characterized in that, The raw materials for preparing the photoresist composition, by weight percentage, include: 50–95 wt% solvent D; 5–50 wt% solids content; The solid components, by weight percentage, include: 30–90 wt% of phenolic varnish resin A with a weight-average molecular weight of 3,000–20,000; 5–30 wt% of modified phenolic varnish resin B with a weight-average molecular weight of 5000–25000; 4–40 wt% of compounds containing quinone azide groups (C); 0.01–5 wt% perfluoroalkyl acrylate E; The number of carbon atoms in the perfluoroalkyl group of the perfluoroalkyl acrylate E is greater than or equal to 5. The modified phenolic varnish resin B is obtained by condensation of phenol and aldehyde, wherein the phenol includes p-methylphenol, m-methylphenol and substituted phenol, and the molar ratio of p-methylphenol, m-methylphenol and substituted phenol is (27-61):(37-102):(1-21); The structural formula of the substituted phenol is shown in Formula 1: 1； R1 is selected from phenyl, CH3, CH2CH3 or H, R2 is selected from H, CH3 or CH2CH3, and R3 is selected from H, CH3 or CH2CH3.

2. The positive photoresist composition according to claim 1, characterized in that, The compound C containing a quinone azide group is at least one of a complete esterification, partial esterification, amidation, or partial amidation of a polyhydroxyphenyl compound and a sulfonic acid compound containing a quinone diazide group.

3. A method for preparing a positive photoresist composition according to any one of claims 1 to 2, characterized in that, Includes the following steps: The solid component is added to solvent D and mixed to obtain the photoresist composition.

4. A method for forming a photoresist pattern, characterized in that, The process includes the following steps: coating the positive photoresist composition according to any one of claims 1 to 2 onto the surface of a substrate, drying, exposing, developing, and cleaning to obtain the photoresist pattern.

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