Positive photoresist composition and use thereof

Abstract

This invention provides a positive photoresist composition and its application. The positive photoresist composition, by weight percentage, comprises: 20-35% cresol phenolic resin A, 3-15% cresol phenolic resin B, 5-10 wt% photosensitizer, 0.01-2% additives, and 50-70 wt% solvent. The weight-average molecular weight of cresol phenolic resin A is 15,000-30,000, and the weight-average molecular weight of cresol phenolic resin B is 5,000-10,000. The photosensitizer is an aromatic compound with a main absorption wavelength in the range of 365-436 nm and an absorption intensity of not less than 14 L / g·cm. The photoresist composition can adapt to different processing techniques for G-lines, H-lines, and I-lines. When the film thickness reaches 10-20 μm, it exhibits high chemical resistance and steepness, with a side morphology tilt angle of not less than 83° and a pattern resolution of 5-10 μm; it also has excellent electroplating resistance.

Description

Technical Field

[0001] This invention relates to the field of photoresist technology in advanced packaging, and more specifically, to a positive photoresist composition and its application. Background Technology

[0002] In advanced semiconductor packaging, the Re-Distribution Layer (RDL) is a core technology in wafer-level packaging, playing a crucial role in extending and interconnecting the XY plane electrical connections. The essence of RDL technology is adding one or more layers to the original wafer: first, a copper seed layer is deposited on the substrate; then, a layer of photoresist is coated onto this structure; next, it is patterned using photolithography; finally, an electroplating system deposits a copper metallization layer to form the final RDL. In semiconductor manufacturing, photoresist is one of the more expensive materials. In conventional front-end processes, photoresist thickness is typically kept within 1 μm. However, in back-end packaging processes like RDL, the copper line height is generally 5-10 μm, corresponding to a photoresist thickness of 10-15 μm. Therefore, photoresist used in RDL needs to achieve high thickness while possessing excellent performance indicators such as high chemical resistance and high steepness. Furthermore, the application of such photoresist involves high film thickness and large usage, placing certain requirements on the cost of its use.

[0003] Based on their different exposure principles, photoresists are mainly divided into two categories: positive photoresists and negative photoresists. Positive photoresists are those where the exposed areas dissolve more easily in the developer, leaving the unexposed areas as a barrier layer or mask. Their working principle involves ultraviolet light irradiating the exposed areas, causing a chemical reaction in the photoresist that reduces the resin's molecular weight or reverses its polarity, accelerating resin dissolution. The unexposed areas contain poorly soluble polymer resins. Negative photoresists, on the other hand, undergo a cross-linking reaction in the exposed areas to form a three-dimensional network structure, exhibiting stronger etching resistance. The unexposed areas are etched away by the developer, thus forming the pattern. Based on their specific reaction principles, positive and negative photoresists are further subdivided into different technical systems.

[0004] Based on their chemical reaction principles, photoresists can be broadly classified into two categories: chemically amplified and non-chemically amplified. Chemically amplified photoresists involve adding a photoacid-generating agent to the photoresist. Under ultraviolet light irradiation, the agent decomposes to release acid. In the post-baking process, the acid acts as a catalyst, catalyzing the removal of protecting groups from the film-forming resin. Furthermore, after the removal reaction, the acid can be released again to continue its catalytic effect. The presence or absence of protecting groups alters the photoresist's dissolution rate in the developer, thus forming a pattern. The advantages of this type of photoresist are low energy requirements, steep morphology, and high photosensitivity. The disadvantages are the high cost of the photoacid-generating agent and the resin with protecting groups, the need for a post-exposure baking (PEB) process, and its high temperature sensitivity. It is typically used for photoresists with a film thickness of less than 1 μm. Non-chemically amplified photoresists are further subdivided into main chain fragmentation type and polarity-change type. Main chain fragmentation type photoresists, under EUV irradiation, decompose polycarbonate polymers into CO2, CO, and many low-molecular-weight fragments, which significantly increase their solubility in the developer. The advantages of this type of photoresist are high resolution and strong photosensitivity. The disadvantages are the requirement for an EUV extreme ultraviolet light source, high resin cost, and high environmental cleanliness requirements; it is often used in front-end processes. The most widely used formulation system for polarity-change type photoresists is a phenolic resin and diazonaphthoquinone (PAC) type photosensitizer system. The principle is that after the photoresist is irradiated with mercury lamp ultraviolet light, the diazonaphthoquinone (DNQ) units of the diazonaphthoquinone type photosensitive compound (PAC) are converted into enones, which are further converted into indenecarboxylic acid in water. This promotes the dissolution of phenolic resin in the developer, while the DNQ in the unexposed areas inhibits the dissolution of phenolic resin in the alkaline developer, thereby achieving patterning.

[0005] In recent years, photoresist materials have been widely used in the actual manufacturing process of advanced packaging. Their main function is to provide patterned transfer for copper electroplating in RDL process. The selection of materials and structures are also diverse. A high-performance thick-film positive photoresist should meet the following performance requirements: high film thickness, excellent film thickness uniformity, high resolution, high steepness and high chemical resistance. However, there are many shortcomings of the thick-film photoresists on the market: (1) The cost of chemically amplified positive photoresists in the current thick-film photoresist market is relatively high, and it is necessary to add PEB process (which is not available in many applications); (2) The positive photoresists of phenolic resin and photosensitive agent (PAC) system on the market cannot have high resolution and high steepness while meeting the requirement of 10-20μm thickness. During the exposure process, if the photoresist film is too thick, the light absorption of the bottom photoresist will be low and the steepness will be insufficient, thus forming a positive trapezoidal morphology, which will also affect the resolution. Summary of the Invention

[0006] To address the problems in the prior art, the present invention provides a positive photoresist composition that is applicable to G, H, and I line processes and can be used in advanced packaging technology. While meeting the requirements of a film thickness of 10-20 μm, it can maintain high resolution and steepness, and has excellent electroplating tolerance in acidic and inorganic acid copper plating solutions.

[0007] The positive photoresist composition of the present invention comprises, by weight percentage, the following components: 20-35% cresol phenolic resin A, 3-15% cresol phenolic resin B, 5-10 wt% photosensitizer, 0.01-2% additives, and 50-70 wt% solvent.

[0008] During the experiments, the inventors discovered that if the weight-average molecular weight of the cresol phenolic resin was too low, the viscosity of the resulting positive photoresist composition would be low, making it impossible to achieve the required 10-20 μm film thickness after processing. Furthermore, the development rate would be faster, and its tolerance in the developer would be worse. Ultimately, after forming, the top of the photoresist side morphology would show rounded corners, and the middle would show indentations. Conversely, if the weight-average molecular weight of the cresol phenolic resin was too high, the viscosity of the photoresist composition would increase significantly, affecting the applicable film thickness. Simultaneously, the development rate of the photoresist composition would be slower, and under the processing conditions provided by this invention, the photoresist would fail to open after development. Therefore, the inventors selected a combination of cresol phenolic resin A and cresol phenolic resin B, adjusting the mass ratio of the two resins to stabilize the development rate of the photoresist composition within an appropriate range. Therefore, in this embodiment of the invention, the weight-average molecular weight of cresol phenolic resin A is 15,000-30,000, and the weight-average molecular weight of cresol phenolic resin B is 5,000-10,000. The mass ratio of cresol phenolic resin A to cresol phenolic resin B is 9-6:1-4, and the specific ratio can be 9:1, 8:2, 7:3, 6:4, etc.

[0009] In some embodiments of the present invention, the raw materials for preparing the cresol phenolic resin include m-cresol phenolic resin and p-cresol phenolic resin, and can be carried out according to the following steps: In a suitable reaction vessel, appropriate amounts of cresol and phenolic resin are added and mixed according to the required ratio (usually 1:1.2 to 1:1.5). Then, under stirring, an acidic catalyst (such as hydrochloric acid) is slowly added for catalysis. The amount of catalyst added is usually 1% to 5% of the total weight of the reactants. During the acid-catalyzed condensation reaction, the reaction temperature is usually between 70°C and 100°C, and the reaction time can be adjusted according to actual needs, usually ranging from two hours to tens of hours. After the reaction is completed, heating is stopped and the reaction solution is cooled to room temperature. After obtaining the crude cresol phenolic resin, it can be purified by filtration, washing, and drying to finally obtain the desired product.

[0010] In some embodiments of the present invention, the primary absorption wavelength of the photosensitizer is between 365-436 nm. This is because lithography machines for advanced semiconductor packaging use mercury lamps as excitation light sources, and the peak energy bands of mercury lamps are concentrated in three bands: 365 nm, 405 nm, and 436 nm. These correspond to the processing wavelengths of G-line lithography machines (around 436 nm), H-line lithography machines (around 405 nm), and I-line lithography machines (around 365 nm), respectively. To ensure that the thick-film photoresist composition can achieve good photochemical reactions within the aforementioned wavelength range, the photosensitizer used in the present invention is preferably a polymer with an absorption wavelength between 365-436 nm.

[0011] Considering the properties of polarity-changing photoresists, the positive photoresist composition of this invention utilizes the photoreaction principle of polarity-changing photoresists. In some embodiments of this invention, the photosensitizer is at least one of 2,1,4-diazonaphthoquinone sulfonates and 2,1,5-diazonaphthoquinone sulfonates. Preferably, the diazonaphthoquinone derivative includes at least one of 2,1,5-diazonaphthoquinone sulfonyl chloride and 2,1,4-diazonaphthoquinone sulfonyl chloride, and the naphthol derivative includes 2,3,4-trihydroxydinazine, 2,4,4′- At least one of trihydroxydinane, 2,2′,4-trihydroxydinane, 2,3,4,4′-tetrahydroxydinane, 2,2′,3,4-tetrahydroxydinane, 2,4,2′,4′-tetrahydroxydinane, 2,3,4-trihydroxynaphthyl ethyl ketone, and 2,4-dihydroxynaphthyl ethyl ketone, as an example, the photosensitizer is selected from at least one of 2,3,4,4-tetracarboxybenzophenone-1,2-diazidonaphthoquinone-5-sulfonate and 2,3,4,4-tetracarboxybenzophenone-1,2-diazidonaphthoquinone-4-sulfonate.

[0012] In some embodiments of the present invention, the raw materials for preparing the photosensitizer include diazonaquinone sulfonyl chloride, hydroxybenzophenone, dioxane, triethylamine, etc., and can be carried out according to the following steps: In a suitable reaction vessel, excess dioxane is added as a solvent background, and appropriate amounts of hydroxybenzophenone and diazonaquinone sulfonyl chloride are added according to the required ratio (usually 1:2 to 1:3) and mixed. Then, under stirring, the mixture is heated to 40°C to dissolve. Over 1 hour, triethylamine in an equimolar amount of diazonaquinone sulfonyl chloride is gradually added dropwise. After reacting for half an hour, the reaction phenomenon and solution color are observed. After the pH is detected to be between 6 and 8, TCL detection is performed. The solution is then dispersed in an aqueous phase at a ratio of 1:4, rapidly stirred and dispersed for 5 hours, precipitated, filtered, washed with water, and dried to obtain the corresponding photosensitizer.

[0013] In this invention, the development principle of the positive photoresist composition is as follows: the diazonoquinone structure of the photosensitizer is transformed into an enone after ultraviolet light irradiation, and the enone is further transformed into indene carboxylic acid in water. The appearance of indene carboxylic acid promotes the dissolution of cresol phenolic resin in the developer, while the photosensitizer in the unexposed area inhibits the dissolution of cresol phenolic resin in the alkaline developer, thus ultimately achieving patterning. During the experimental phase, the inventors discovered that if the amount of photosensitizer in the positive photoresist composition is too high, on the one hand, the excess photosensitizer at the top absorbs most of the light energy, preventing ultraviolet light from reaching the bottom. This results in insufficient exposure of the positive photoresist composition at the bottom layer, ultimately forming a trapezoidal pattern with a narrow top and wide bottom, or even the bottom failing to dissolve, leading to film failure. On the other hand, when the diazonaphthoquinone structure in the positive photoresist composition is exposed and developed under alkaline conditions, the excess photosensitizer undergoes large-scale diazo coupling, resulting in an eagle-shaped top in the final pattern cross-section. Furthermore, since the photosensitizer releases a small amount of N2 during exposure, the positive photoresist composition may experience film cracking under high film thickness and high photosensitizer content. If the amount of photosensitizer is too low, the resistance of the non-exposed area to the developer will decrease, the formed pattern will be concave in the middle, and the actual processing exposure will be too high relative to the exposure required by the thick film positive photoresist composition. This will cause the photoresist in the non-exposed area to be passively affected by the exposure, and the final colloid linewidth will be narrower, which will not match the expected linewidth, thus affecting the stability of the process.

[0014] In summary, in some embodiments of the present invention, the amount of the photosensitizer is preferably 5-10 wt%, more preferably 7-9 wt%.

[0015] In some embodiments of the present invention, the solvent is a commonly used solvent in the art, which serves to dissolve and disperse the resin, achieve the coating function, and improve the uniformity of the photoresist. It can be selected from polar and non-polar organic solvents. Preferably, the solvent is at least one of propylene glycol methyl ether acetate, propylene glycol methyl ether, ethyl lactate, propylene carbonate, benzyl alcohol, and ethane-3-ethoxypropionate. More preferably, the solvent is at least one of propylene glycol methyl ether acetate, propylene glycol methyl ether, ethyl lactate, and propylene carbonate.

[0016] In some embodiments of the present invention, depending on the type of photosensitizer, the solvent is selected as a mixture of propylene glycol methyl ether acetate and propylene glycol methyl ether in any proportion, and the mixing ratio of the two can be adaptively adjusted according to the characteristics of other components.

[0017] In some embodiments of the present invention, the first additive is a low-molecular-weight polyhydroxy aromatic compound, which improves the photosensitivity of the photoresist, regulates the development and dissolution rate of the phenolic resin, and increases the contrast in dissolution rates between the exposed and non-exposed areas, thereby effectively improving resolution. During the experimental phase, the inventors discovered that if the amount of the first additive in the positive photoresist composition is too high, the small-molecule compound will simultaneously increase the overall dissolution rate of both the exposed and non-exposed areas, increasing film loss in the non-exposed areas of the photoresist in the developer, thus failing to achieve the corresponding preset film thickness and affecting subsequent processes. If the amount of the first additive is too low, it will not achieve the effect of increasing the contrast in dissolution rates between the exposed and non-exposed areas. The first additive is preferably bisphenol A, 4,4'-(1-methylethylidene)bis(2-methylphenol), 4-(2-phenylprop-2-yl)phenyl-1,3-diol, 4-[(4-hydroxy-3,5-dimethylphenyl)-(2-hydroxyphenyl)methyl]-2,6-dimethylphenol, 4-[(4-hydroxy-2,5-dimethylphenyl)-(2-hydroxyphenyl)methyl]-2,5-dimethylphenol, 4,4-methylenebis(2,6-dimethylphenol), etc. More preferably, it is at least one of 4,4-methylenebis(2,6-dimethylphenol) and 4,4'-(1-methylethylidene)bis(2-methylphenol).

[0018] In some embodiments of the present invention, the second additive is a long-chain substituted secondary alcohol or a fluorinated long-chain acrylic acid. Its function is to improve the leveling and film uniformity of the photoresist, reduce the surface tension of the photoresist, improve wettability and solid dispersion, and prevent streaks from forming during the photoresist homogenization process. During the experimental stage, the inventors found that if the amount of the second additive in the positive photoresist composition is too high, on the one hand, the second additive is expensive, significantly increasing the cost; on the other hand, excessive second additive will accumulate on the surface of the photoresist layer, affecting the optical path during the exposure process and thus affecting the morphology of the photoresist. If the amount of the first additive is too low, it will not achieve the effect of improving the leveling and film uniformity of the photoresist. Preferably, it is an ethoxylated C12-14-secondary alcohol, α-[3,5-dimethyl-1-(2-methylpropyl)hexyl]-w-hydroxy poly(oxo-1,2-ethylenediyl), partially fluorinated alcohol-substituted ethylene glycol, or a copolymer of perfluoroalkyl sulfinyl acrylate and polyalkylene acrylate. More preferably, it is a copolymer of perfluoroalkyl sulfinylamino acrylate and polyalkylene acrylate, or at least one of partially fluorinated alcohols replacing ethylene glycol.

[0019] The positive photoresist composition described above in this invention is applicable to advanced packaging technology and is suitable for G-line, H-line, and I-line lithography machines.

[0020] In some embodiments of the present invention, when the positive photoresist composition is applied in advanced packaging technology, the film thickness after the photochemical reaction is 10-20 μm. This is because in the electroplating process of RDL, metal is grown by chemical deposition from the electroplating solution into the gaps of the patterned photoresist. The electroplating process requires the photoresist layer height to be at least 2-3 μm higher than the grown metal layer to ensure the morphology of the electroplated metal lines and prevent newly formed metal from protruding from the photoresist layer and forming metal connections, which could lead to short circuits in subsequent device testing. In advanced packaging technology, the height of the copper wires used is generally 5-10 μm. To cover the copper wire layer deposited in the photoresist, the resulting photoresist film thickness should not be less than the height of the copper wire layer. In the present invention, after the positive photoresist composition completes the photoreaction and is patterned under light source irradiation, in order to obtain a high resolution (below 10 μm) while also achieving a high aspect ratio (the ratio of film thickness to resolution), the film thickness formed by the positive photoresist composition needs to be controlled between 10-20 μm.

[0021] In some embodiments of the present invention, the positive photoresist composition may also contain other specific additives, which may be, but are not limited to, imidazole-based ultraviolet absorbers, siloxane-based adhesives, etc. In order to improve the substrate adhesion and product stability of the positive photoresist in actual processes, the type of additive may be selected according to the situation, and the amount of the additive may be adjusted by increasing or decreasing the amount of solvent. In the present invention, no strict limitation is imposed.

[0022] Beneficial Effects: Compared with existing technologies, this invention adjusts the film thickness and development rate of the positive photoresist composition in the developer by selecting cresol phenolic resin A and cresol phenolic resin B, their weight-average molecular weights, and their usage ratio, thereby increasing the contrast between exposed and unexposed areas and achieving the purpose of morphology adjustment. Based on the weight-average molecular weights and amounts of the cresol phenolic resin A and cresol phenolic resin B, the amount of the photosensitizer is optimally adjusted and used in combination with the cresol phenolic resin A and cresol phenolic resin B, making the photoresist composition suitable for advanced packaging technology processes. Ultimately, it achieves the following: while maintaining a film thickness of 10-20 μm, film thickness uniformity is less than 5%, reaching approximately 3%; pattern resolution reaches 5-10 μm, with an aspect ratio of at least 2:1; the steepness of the pattern side morphology reaches 83° or higher; and it exhibits excellent electroplating tolerance in inorganic acid copper plating solutions. Attached Figure Description

[0023] Figure 1 Line width morphology of the photoresist obtained in Example 1;

[0024] Figure 2 Line width morphology of the photoresist obtained in Example 2;

[0025] Figure 3 Line width morphology of the photoresist obtained in Example 3;

[0026] Figure 4 Linearity morphology of the photoresist obtained in Comparative Example 1;

[0027] Figure 5 Linearity morphology of the photoresist obtained in Comparative Example 2;

[0028] Figure 6 Linearity morphology of the photoresist obtained in Comparative Example 3;

[0029] Figure 7 Linearity morphology of the photoresist obtained in Comparative Example 4;

[0030] Figure 8 Line width morphology of the photoresist obtained in Comparative Example 5. Detailed Implementation

[0031] The invention will be more readily understood by referring to the following detailed description of preferred embodiments and included examples. Unless otherwise specified, the technical and scientific terms used herein have the same common meaning in the field to which this invention pertains.

[0032] The terms “comprising,” “including,” “having,” etc., as used herein, or other variations, 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 requirements inherent to such composition, step, method, article, or apparatus.

[0033] The equivalents, concentrations, or other values ​​or parameters described herein are all ranges formed by any pairing of a range, a preferred range, or a series of upper and lower preferred values ​​with any lower limit 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 2”, “1 to 3”, “1 to 4”, “1 to 2” and “2 to 4”, 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] Unless otherwise stated, the singular form includes the plural objects of discussion. "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] In the specification and claims, approximate terms are used to modify quantities, indicating 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...

[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 refers only to the singular form.

[0037] The present invention is described below through specific embodiments, but the present invention is not limited to the specific embodiments given below. Table 1 shows the raw materials and their proportions of the positive photoresist compositions described in Examples 1-6 and Comparative Examples 1-7:

[0038] Table 1. Raw materials and their proportions in the photoresist compositions of Examples 1-6 and Comparative Examples 1-7.

[0039]

[0040]

[0041]

[0042]

[0043] After mixing the above Examples 1-6 and Comparative Examples 1-7 according to the formulas given in Table 1, they were processed into patterns. The specific operation process is as follows:

[0044] 1. The positive photoresist compositions obtained in Examples 1-6 and Comparative Examples 1-7 above are coated on a 4-inch PVD sputtered copper sheet. A suitable spin coating speed is selected and adjusted. For example, the positive photoresist composition is first spread out at a speed of 800 rpm / 5s, and then 1200 rpm / 60s is used as the main speed to adjust the photoresist film thickness to 15 μm.

[0045] 2. Place the PVD Cu wafer with the photoresist film on a contact hot plate for soft baking at 100℃ for 300s. Measure the film thickness using a film thickness gauge. Adjust the spin speed to ensure the dry film thickness of the photoresist is 15.0±0.5μm. Randomly select several different locations on the entire photoresist wafer and test the film thickness at the selected locations. Calculate the uniformity (uniformity%) of the photoresist film thickness = (maximum film thickness - minimum film thickness) / (average film thickness * 2). If uniformity% < 5%, the film thickness uniformity is considered good. Compare the photoresists obtained from the formulations of Examples 1-6 and Comparative Examples 1-7 with those obtained from photolithography tests.

[0046] 3. The PVD Cu wafer coated with photoresist was exposed in a G, H, I-Line Stepper lithography machine (SSB 500 / 40M) at an energy intensity of 1000 mJ / cm². 2 Let stand for about 30 minutes, then develop using a Mark 8 device, continuously spraying 2.38% TMAH for 480 seconds;

[0047] 4. Slice the photoresist and use a Thermo Fisher Scientific Verios 5XHR SEM to measure the side tilt angle (photoresist sidewall morphology) of the photoresist samples prepared in Examples 1-6 at a film thickness of 15 μm, and the top and bottom line widths of the photoresist samples prepared in Comparative Examples 1-7 at a film thickness of 15 μm. Observe the minimum line CD (Critical Dimension, abbreviated as CD), which is regarded as the photoresist resolution. The aspect ratio is obtained by dividing the film thickness by the resolution. Repeat the test 3 times for each formulation.

[0048] The sidewall morphology of the positive photoresist compositions described in the above embodiments and comparative examples after photochemical reaction is shown in Table 2. Figure 1-8 :

[0049] Table 2. Photoresist film thickness uniformity, resolution, and corresponding morphology obtained in Examples 1-6 and Comparative Examples 1-7.

[0050]

[0051] As shown in Table 2 and the corresponding side morphology images, the positive photoresists prepared using the formulations of the positive photoresist compositions described in Examples 1-6, with a film thickness of 15 μm, exhibit the following characteristics: film thickness uniformity is less than 5%, with a minimum of 2.6%; the resulting pattern resolution is 6-7 μm; and the linewidth steepness is not less than 83°. Specifically, the sidewall steepness of the photoresist obtained in Example 1 is 90° (see Table 2 for details). Figure 1 The steepness of the photoresist sidewall morphology obtained in Example 2 is 86° (see reference). Figure 2The steepness of the photoresist sidewall morphology obtained in Example 3 is 83° (see reference). Figure 3 The steepness of the photoresist sidewall morphology obtained in Example 4 was 89°, in Example 5 it was 84°, and in Example 6 it was 87°. (The SEM images obtained in Examples 4-6 are extremely similar to those obtained in Examples 1-3, therefore they are shown in the figures as follows.) Figure 1-3 (This is a representative illustration of the sidewall morphology obtained in Examples 4-6).

[0052] In Comparative Example 1, compared to Example 1, the weight-average molecular weight of the cresol resin A used was lower (Mw = 12000). Although the resulting photoresist exhibited good film thickness uniformity and resolution, the linewidth of the sidewall morphology was narrower (see reference). Figure 4 This is because the low weight-average molecular weight of the cresol-phenolic resin reduces the tolerance of the positive photoresist composition obtained in Comparative Example 1 to the developer, leading to overdevelopment. Furthermore, the low molecular weight of cresol-phenolic resin A results in a faster development rate, and the photoresist in non-exposed areas is also corroded by the developer, ultimately leading to narrower line widths.

[0053] In Comparative Example 2, compared to Example 1, the weight-average molecular weight of the cresol phenolic resin A used was higher (Mw = 40,000), resulting in poorer uniformity of the final photoresist film thickness. Furthermore, the photoresist composition at the bottom did not open up, failing to form a clear pattern (see [reference]). Figure 5 The photoresist composition obtained in Comparative Example 2 was not developed, meaning the resolution was 0. This is because the high weight-average molecular weight of the cresol phenolic resin significantly increased the resistance of the positive photoresist composition to the developer, resulting in a slower development speed in the developer. Under the processing energy and development time provided by this invention, the photoresist composition at the bottom could not be developed to the bottom, thus preventing the formation of the film.

[0054] In Comparative Example 3, compared to Example 1, the mass ratio of cresol phenolic resin A to cresol phenolic resin B used was less than 1:1, meaning the amount of cresol phenolic resin B was greater than the amount of cresol phenolic resin A. Although the resulting photoresist exhibited good film thickness uniformity and pattern resolution, the top of the linewidth side profile showed rounded corners (see [reference]). Figure 6 This is because cresol resin B dissolves faster than cresol resin A. A high proportion of cresol resin B accelerates the development rate of the positive photoresist composition obtained in Comparative Example 3 during exposure and development. Within the same development time, the photoresist in the unexposed top layer is etched by the developer for a longer period, thus forming rounded corners.

[0055] In Comparative Example 4, the amount of photosensitive agent used was lower (3wt%) compared to Example 1. Although the resulting photoresist had good film thickness uniformity and resolution, careful observation revealed that the resolution still showed an increasing trend of 1-2 μm compared to Examples 1-6, and the side profile of the linewidth was concave in the middle (see reference). Figure 7 This is because the positive photoresist composition in Comparative Example 4 exhibits reduced resistance to the developer in the non-exposed areas, and the processing exposure provided by this invention is far greater than the exposure required by the photosensitizer contained in the positive photoresist composition of Comparative Example 4. Therefore, the photoresist in the non-exposed areas is passively affected by the exposure, resulting in a narrower linewidth. The slight difference in resolution is due, on the one hand, to inappropriate photosensitizer dosage, and on the other hand, possibly to fluctuations in various processing factors. Furthermore, the results obtained in Comparative Example 6 are similar to those in Comparative Example 4.

[0056] In Comparative Example 5, compared to Example 1, the amount of the photosensitizer was higher (12 wt%), resulting in a photoresist with good film thickness uniformity and resolution. However, the linewidth morphology was narrower at the top and wider at the bottom, exhibiting a trapezoidal shape (see reference). Figure 8 This is because the excess photosensitizer at the top of the photoresist absorbs most of the light energy, preventing ultraviolet light from reaching the bottom as ideally as possible, resulting in insufficient exposure of the photoresist composition at the bottom.

[0057] In Comparative Example 7, compared to Example 4, the amount of photosensitizer was too high (14 wt%). The resulting positive photoresist composition exhibited good film thickness uniformity, but the bottom layer failed to open, resulting in poor sidewall morphology. This result was very similar to Comparative Example 2. This is because the excess photosensitizer at the top of the photoresist absorbed most of the light energy, preventing ultraviolet light from reaching the bottom as ideally as possible. Consequently, the photoresist composition at the bottom received too low an exposure, and under the same development time conditions, the photoresist could not develop and open. Furthermore, combining Comparative Example 7 and Comparative Example 2, it was found that the molecular weights of the cresol phenolic resin A and cresol phenolic resin B in this application, as well as the amount of photosensitizer, have equally important effects on the sidewall morphology of the positive photoresist composition. Changes in either parameter will severely affect the exposure level of the positive photoresist composition, resulting in poor sidewall morphology of the obtained photoresist.

[0058] Analysis of the results from Comparative Examples 1-7 reveals that both the cresol resin and the photosensitizer in the positive photoresist of this invention significantly influence the sidewall morphology of the formed photoresist. Changes in the parameters of either component can lead to undesirable changes in the sidewall morphology. Furthermore, when the parameters of the photosensitizer remain constant, changes in the resin ratio of cresol resin A and cresol resin B will result in a decrease in the uniformity of the photoresist film thickness and its resolution. When the resin ratio of cresol resin A and cresol resin B remains constant, changes in the amount of photosensitizer may lead to a decrease in photoresist resolution, but the effect on film thickness uniformity is negligible.

[0059] In summary, by adjusting the weight-average molecular weight and mass ratio of the cresol phenolic resin A and cresol phenolic resin B, the amount of the photosensitizer, and the amount of the additives, the positive photoresist composition can be adapted to lithography machines with mixed G, H, and I-Line light sources. Under special advanced packaging technology conditions and while ensuring a film thickness of 10-20 μm, it achieves film thickness uniformity of less than 5%, pattern resolution of 5-10 μm, an aspect ratio of not less than 2:1, and a line width side morphology steepness of 83° or higher. Furthermore, it exhibits excellent electroplating tolerance in inorganic acid copper electroplating solutions.

[0060] The above description is merely an embodiment of the present invention and is not intended to limit the present invention in any way. Although the present invention has been disclosed above by way of embodiment, it is not intended to limit the present invention. Any person skilled in the art can make some modifications or alterations to the methods and techniques disclosed above without departing from the scope of the present invention to create equivalent embodiments. Any simple modifications, equivalent changes and alterations made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the scope of the present invention.

Claims

1. A positive photoresist composition, characterized in that, By weight percentage, it contains the following components: 20-35% cresol phenolic resin A, 3-15% cresol phenolic resin B, 5-10 wt% photosensitizer, 0.01-2 wt% additives and 50-70 wt% solvent. The weight-average molecular weight of the cresol phenolic resin A is 15,000-28,000, and the weight-average molecular weight of the cresol phenolic resin B is 5,000-10,000. The additives include a first additive and a second additive; The first additive is selected from at least one of bisphenol A, 4,4'-(1-methylethylidene)bis(2-methylphenol), 4-(2-phenylprop-2-yl)phenyl-1,3-diol, 4-[(4-hydroxy-3,5-dimethylphenyl)-(2-hydroxyphenyl)methyl]-2,6-dimethylphenol, 4-[(4-hydroxy-2,5-dimethylphenyl)-(2-hydroxyphenyl)methyl]-2,5-dimethylphenol, and 4,4-methylenebis(2,6-dimethylphenol); The second additive is selected from ethoxylated... C12 14 Secondary alcohols, a [3,5] dimethyl 1 (2 [methylpropyl)hexyl] w Hydroxypoly(oxygenated) 1,2 At least one of the copolymers of ethylene glycol (ethylene glycol), partially fluorinated alcohol-substituted ethylene glycol, and perfluoroalkyl sulfinylamino acrylate polyalkylene acrylate.

2. The positive photoresist composition according to claim 1, characterized in that, The mass ratio of cresol resin A to cresol resin B is greater than 1:

1.

3. The positive photoresist composition according to claim 2, characterized in that, The mass ratio of cresol phenolic resin A to cresol phenolic resin B is 9-6:1-4.

4. The positive photoresist composition according to claim 1, characterized in that, The absorption wavelength of the photosensitizer is between 365-436 nm.

5. The positive photoresist composition according to claim 4, characterized in that, The photosensitizer is at least one of 2,1,4-diazonaphthoquinone sulfonate compounds and 2,1,5-diazonaphthoquinone sulfonate compounds.

6. The positive photoresist composition according to claim 5, characterized in that, The amount of the photosensitizer used is 7-9 wt%.

7. The positive photoresist composition according to claim 1, characterized in that, The solvent is at least one of propylene glycol methyl ether acetate, propylene glycol methyl ether, ethyl lactate, and propylene carbonate.

8. The positive photoresist composition according to claim 7, characterized in that, The solvent is a mixture of propylene glycol methyl ether acetate and propylene glycol methyl ether in any proportion.

9. The application of the positive photoresist composition according to any one of claims 1-8 in the field of advanced packaging technology.

10. The application of the positive photoresist composition according to claim 9 in the field of advanced packaging technology, characterized in that, The resulting photoresist film is 10-20 μm thick.

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