Chemically amplified photoresist, method of making and photolithography process

Abstract

This invention provides a chemically amplified photoresist and its preparation method and photolithography process. The photoresist includes upconversion nanoparticles, a resin matrix, a photoacid generator, and a solvent. The upconversion nanoparticles are fluoride nanocrystals doped with sensitizers and activators, capable of converting infrared light of a first wavelength into ultraviolet light of a second wavelength. The upconversion nanoparticles introduce polymerizable double bonds through ligand exchange, and the resin matrix contains copolymerizable active sites. The upconversion nanoparticles and the resin matrix form covalent bonds through the reaction of the polymerizable double bonds with the copolymerizable active sites. This invention can improve ultraviolet lithography sensitivity, improve linewidth roughness, stabilize defect density, improve product yield, reduce ultraviolet lithography dosage, reduce the operating cost of ultraviolet equipment, and reduce energy consumption and heavy metal pollution risks.

Description

Technical Field

[0001] This invention relates to the field of photolithography, and in particular to a chemically amplified photoresist, its preparation method, and photolithography process. Background Technology

[0002] In recent years, with the continuous miniaturization of semiconductor manufacturing processes, chemically amplified photoresist (CAR) technology has faced increasingly severe challenges. Traditional CAR systems exhibit insufficient sensitivity and limited resolution when dealing with ultraviolet (UV) lithography. To address these issues, researchers have explored various nanomaterial doping schemes, but these approaches have significant limitations and urgently require breakthrough innovation.

[0003] Specifically, existing chemically amplified photoresist technology still faces challenges in practical applications, including the difficulty in balancing lithographic sensitivity and resolution, the complexity of multi-wavelength lithography processes, poor dispersion of nanomaterials, and insufficient environmental friendliness. Based on this, existing approaches to improving the performance of chemically amplified photoresists (mainly categorized into three types: high atomic number nanoparticle doping systems, quantum dot sensitization systems, and novel photoresponsive systems), while conceptually novel, face significant industrialization obstacles (such as poor compatibility with existing semiconductor processes, high material costs, and narrow, uncontrollable process windows). Through extensive experimental research and theoretical analysis, the underlying reasons for these problems are revealed as follows: First, existing technologies focus too much on improving single performance indicators while neglecting the synergistic effects of the material system. The interface between nanomaterials and resin is crucial in determining performance, but existing technologies lack precise control over interfacial interactions (such as interfacial binding energy, charge distribution, and mass transfer characteristics). Second, photoresist development is disconnected from photolithography processes. Many materials perform well in the laboratory but cannot adapt to actual process conditions. Summary of the Invention

[0004] The purpose of this invention is to provide a chemically amplified photoresist and its preparation method and photolithography process, so as to solve one or more of the problems existing in the prior art, such as the difficulty in achieving both photolithography sensitivity and resolution, the complexity of multi-wavelength photolithography processes, the poor dispersibility of nanomaterials, and insufficient environmental friendliness.

[0005] To achieve the above objectives, the present invention provides the following technical solution: a chemically amplified photoresist comprising upconversion nanoparticles, a resin matrix, a photoacid generator, and a solvent; wherein the upconversion nanoparticles are fluoride nanocrystals doped with sensitizers and activators, and the upconversion nanoparticles are capable of converting infrared light of a first wavelength into ultraviolet light of a second wavelength; the upconversion nanoparticles introduce polymerizable double bonds through ligand exchange, the resin matrix contains copolymerizable active sites, and the upconversion nanoparticles and the resin matrix form covalent bonds through the reaction of the polymerizable double bonds with the copolymerizable active sites.

[0006] Optionally, the core of the upconversion nanoparticles is NaYF4:Yb. 3+ / Tm 3+ The particle size is 6 nanometers to 10 nanometers.

[0007] Optionally, the ligand includes acrylic acid or methacrylic acid; the resin matrix uses methacrylate-styrene copolymer as the main resin, and the glass transition temperature of the methacrylate-styrene copolymer is in the range of 120℃~150℃.

[0008] Optionally, the first wavelength is 808 nanometers or 980 nanometers, and the second wavelength is 365 nanometers.

[0009] Optionally, the absorption wavelength of the photoacid generator is matched with the second wavelength of ultraviolet light emitted by the upconversion nanoparticles.

[0010] Optionally, the photoacid generator includes any one of thionium salt, iodonium salt, or ferrocene salt.

[0011] Optionally, the solvent includes a mixed solution of propylene glycol methyl ether acetate and γ-butyrolactone; wherein the molar ratio of propylene glycol methyl ether acetate to γ-butyrolactone is (2~8):(2~8).

[0012] Optionally, in the chemically amplified photoresist, by mass percentage, the upconversion nanoparticles are 0.05%~1%, the resin matrix is ​​5%~15%, the photoacid generator is 0.1%~2%, and the solvent is 80%~95%.

[0013] To achieve the above objectives, the present invention also provides a method for preparing a chemically amplified photoresist as described in any of the preceding claims, comprising:

[0014] The upconversion nanoparticles coated with oleylamine were synthesized by thermal decomposition. Acrylic acid or methacrylic acid was stirred with the upconversion nanoparticles at a mass ratio of (2~10):1 for 2 hours to 48 hours under nitrogen protection at 60℃~120℃ to obtain the modified upconversion nanoparticles.

[0015] The modified upconversion nanoparticles, the resin matrix, the photoacid generator, and the solvent are mixed in a mass percentage ratio of (0.05%~1%): (5%~15%): (0.1%~2%): (80%~95%) to obtain a mixture.

[0016] The mixture is ultrasonically dispersed for 0.5 to 4 hours at a temperature of 20°C to 80°C, and then filtered to obtain the chemically amplified photoresist.

[0017] To achieve the above objectives, the present invention also provides a photolithography process using the chemically amplified photoresist described in any of the preceding claims, wherein the photolithography process includes: during exposure processing:

[0018] Pre-exposure is performed using an infrared light source of the first wavelength to excite the upconversion nanoparticles in the chemically amplified photoresist to emit ultraviolet light of the second wavelength;

[0019] The main exposure is performed using the second wavelength of ultraviolet light source to complete the patterning.

[0020] Compared with existing technologies, the chemically amplified photoresist, its preparation method, and photolithography process provided by this invention have the following beneficial effects:

[0021] The chemically amplified photoresist provided by this invention includes upconversion nanoparticles, a resin matrix, a photoacid generator, and a solvent; wherein, the upconversion nanoparticles are fluoride nanocrystals doped with sensitizers and activators, and the upconversion nanoparticles are capable of converting infrared light of a first wavelength into ultraviolet light of a second wavelength; the upconversion nanoparticles introduce polymerizable double bonds through ligand exchange, the resin matrix contains copolymerizable active sites, and the upconversion nanoparticles and the resin matrix form covalent bonds through the reaction of the polymerizable double bonds with the copolymerizable active sites. Therefore, the chemically amplified photoresist provided by this invention introduces upconversion nanoparticles, specifically fluoride nanocrystals doped with sensitizers and activators, which can convert infrared light of a first wavelength into ultraviolet light of a second wavelength. This allows the chemically amplified photoresist to utilize the strong penetrability and low scattering effect of infrared light as an excitation source. By generating ultraviolet light in situ within the chemically amplified photoresist through the upconversion nanoparticles, it can not only significantly reduce light scattering interference during the photolithography process and greatly improve photolithography resolution, but also ensure sufficient excitation of the photoacid generator by utilizing the efficient energy transfer of the upconversion nanoparticles. Thus, while reducing the ultraviolet photolithography dose, it can achieve a synergistic improvement in photolithography sensitivity and resolution. Furthermore, upconversion nanoparticles introduce polymerizable double bonds through ligand exchange, and the resin matrix contains copolymerizable active sites. The upconversion nanoparticles and the resin matrix form covalent bonds through the reaction of the polymerizable double bonds with the copolymerizable active sites, firmly "anchoring" the upconversion nanoparticles within the three-dimensional network of the resin matrix, making them part of the polymer chain. This solves the problems of easy agglomeration and sedimentation of nanoparticles in solvents and resins, achieving molecular-level uniform dispersion of nanomaterials in the resin matrix. This significantly improves the film quality of the photoresist and effectively reduces the linewidth roughness of the pattern. The chemically amplified photoresist provided by this invention supports a novel photolithography process that combines infrared and ultraviolet light exposure. Technically, it improves ultraviolet lithography sensitivity, reduces linewidth roughness, stabilizes defect density, and increases product yield. Economically, it reduces dependence on ultraviolet lithography dosage, effectively lowering the cost of ultraviolet equipment. Socially, by using low-energy, high-penetration infrared light as one of the excitation sources, it reduces the use of high-energy ultraviolet light, effectively reducing energy consumption and the risk of heavy metal pollution.

[0022] Since the preparation method and photolithography process of the chemically amplified photoresist provided by this invention belong to the same inventive concept as the chemically amplified photoresist provided by this invention, they possess at least all the advantages of the chemically amplified photoresist provided by this invention. For details regarding the advantages of the preparation method and photolithography process, please refer to the relevant descriptions of the beneficial effects of the chemically amplified photoresist provided by this invention; they will not be repeated here. Furthermore, the photolithography process provided by this invention is compatible with the chemically amplified photoresist provided by this invention. By first using an infrared light source for pre-exposure to excite the upconversion nanoparticles in the chemically amplified photoresist to emit ultraviolet light of a second wavelength, and then using an ultraviolet light source for main exposure, the linewidth roughness of the pattern can be reduced while lowering the ultraviolet lithography dose. Attached Figure Description

[0023] Figure 1 This is a schematic diagram of the structure of an upconversion nanoparticle provided in Embodiment 1 of the present invention;

[0024] Figure 2 for Figure 1 The image shown is a transmission electron microscope image of the upconversion nanoparticles.

[0025] Figure 3 This is a schematic diagram of energy level transitions of upconversion nanoparticles under 980 nm infrared light excitation, provided in Embodiment 1 of the present invention.

[0026] Figure 4 This is a schematic flowchart of a method for preparing a chemically amplified photoresist according to Embodiment 2 of the present invention. Detailed Implementation

[0027] The following detailed description, in conjunction with the accompanying drawings and specific embodiments, further illustrates the chemically amplified photoresist, its preparation method, and photolithography process proposed in this invention. The advantages and features of this invention will become clearer from the following description. It should be noted that the drawings are all in a very simplified form and use non-precise proportions, used only to facilitate and clarify the illustration of the embodiments of this invention. Please refer to the drawings to make the objectives, features, and advantages of this invention more apparent and understandable. It should be understood that the structures, proportions, sizes, etc., depicted in the accompanying drawings are only for the purpose of assisting those skilled in the art in understanding and reading the content disclosed in the specification, and are not intended to limit the implementation conditions of this invention. Any modifications to the structure, changes in proportions, or adjustments to the size, provided that the effects and objectives achieved by this invention are the same or similar, should still fall within the scope of the technical content disclosed in this invention. Specific design features of the invention disclosed herein, including, for example, specific dimensions, orientations, positions, and shapes, will be determined in part by the specific application and usage environment. Furthermore, in the embodiments described below, the same reference numerals are sometimes used across different drawings to denote the same parts or parts having the same function, omitting repeated descriptions.

[0028] It should be understood that, unless specifically stated or obvious from the context, the term “about” as used herein is understood to mean within the normal tolerance range in the field, such as within 2 standard deviations of the mean. “About” can be understood as within 10%, 9%, 8%, 7%, 6%, 5%, 4%, 3%, 2%, 1%, 0.5%, 0.1%, 0.05%, or 0.01% of the stated value. Unless otherwise specified from the context, all numerical values ​​provided herein are modified by the term “about”.

[0029] Example 1

[0030] This embodiment provides a chemically amplified photoresist. Specifically, the chemically amplified photoresist includes upconversion nanoparticles, a resin matrix, a photoacid generator, and a solvent; wherein, the upconversion nanoparticles are fluoride nanocrystals doped with sensitizers and activators, and the upconversion nanoparticles are capable of converting infrared light of a first wavelength into ultraviolet light of a second wavelength; the upconversion nanoparticles introduce polymerizable double bonds through ligand exchange, the resin matrix contains copolymerizable active sites, and the upconversion nanoparticles and the resin matrix form covalent bonds through the reaction of the polymerizable double bonds with the copolymerizable active sites.

[0031] Therefore, the chemically amplified photoresist provided in this embodiment, by introducing upconversion nanoparticles, specifically fluoride nanocrystals doped with sensitizers and activators, can convert infrared light of the first wavelength into ultraviolet light of the second wavelength. This allows the chemically amplified photoresist to utilize the strong penetrability and low scattering effect of infrared light as an excitation source. By generating ultraviolet light in situ within the chemically amplified photoresist through the upconversion nanoparticles, it can not only significantly reduce light scattering interference during the photolithography process and greatly improve photolithography resolution, but also ensure sufficient excitation of the photoacid generator by utilizing the efficient energy transfer of the upconversion nanoparticles. Thus, while reducing the ultraviolet photolithography dose, it can achieve a synergistic improvement in photolithography sensitivity and resolution. Furthermore, upconversion nanoparticles introduce polymerizable double bonds through ligand exchange. The resin matrix contains copolymerizable active sites, and the upconversion nanoparticles and resin matrix form covalent bonds through the reaction of polymerizable double bonds with copolymerizable active sites. This firmly "anchors" the upconversion nanoparticles within the three-dimensional network of the resin matrix, making them part of the polymer chain. This solves the problems of easy agglomeration and sedimentation of nanoparticles in solvents and resins, achieving molecular-level uniform dispersion of nanomaterials in the resin matrix. This significantly improves the film quality of photoresist and effectively reduces the linewidth roughness of the pattern. The chemically amplified photoresist provided in this embodiment supports a novel photolithography process that uses infrared and ultraviolet light for synergistic exposure. In terms of technical performance, it can improve ultraviolet lithography sensitivity, improve linewidth roughness, stabilize defect density, and increase product yield. In terms of economics, it can effectively reduce the cost of ultraviolet equipment by reducing dependence on ultraviolet lithography dosage. In terms of social benefits, by using low-energy, high-penetration infrared light as one of the excitation sources, it reduces the use of high-energy ultraviolet light, effectively reducing energy consumption and the risk of heavy metal pollution.

[0032] Preferably, the core of the upconversion nanoparticles is NaYF4:Yb. 3+ / Tm 3+ The particle size is 6-10 nanometers. Therefore, the core is NaYF4:Yb 3+ / Tm 3+ The upconversion nanoparticles can convert 980 nanometer infrared light into 365 nanometer ultraviolet light.

[0033] Furthermore, the ligand includes acrylic acid or methacrylic acid; the resin matrix uses methacrylate-styrene copolymer as the main resin, and the glass transition temperature of the methacrylate-styrene copolymer ranges from 120℃ to 150℃. Thus, upconversion nanoparticles can achieve polymerizable functionalization through modification with acrylic acid or methacrylic acid; using methacrylate-styrene copolymer as the main resin matrix ensures film stability and compatibility with post-exposure baking processes.

[0034] For example, please see Figure 1 and Figure 2 , Figure 1 This is a schematic diagram of the structure of the upconversion nanoparticles provided in this embodiment; Figure 2 for Figure 1 The transmission electron microscope image of the upconversion nanoparticles shown is at a scale bar of 100 nanometers. Figure 1 As shown, in some embodiments, the core of the upconversion nanoparticles is β-NaYF4:Yb. 3+ / Tm 3+ Its core structure is a hexagonal (β phase) NaYF4 matrix, doped with 20% sensitizer Yb. 3+ and 0.5% activator Tm 3+ The surface of the upconversion nanoparticles is functionalized through modification with acrylic acid (AA) ligands, enabling them to covalently bond with methacrylate-styrene copolymers (P(MMA-co-St)). Figure 2 As shown, the upconversion nanoparticles have a particle size of approximately 6 nanometers.

[0035] It should be noted that the above is merely an exemplary description of the upconversion nanoparticles and not a limitation thereof. Exemplarily, in some other embodiments, the core of the upconversion nanoparticles is not limited to NaYF4:Yb. 3+ / Tm 3+ For example, NaYF4:Yb can also be used. 3+ / Tm 3+ Y in 3+ Replace with Gd 3+ La 3+ Or Lu 3+ As an inert shell, the sensitizer Yb is placed inside. 3+ Replace with Nd 3+ Activator Tm 3+ Replace with Er 3+ Ho 3+ Or Eu 3+ .

[0036] Furthermore, it should be noted that the present invention does not impose excessive limitations on the type of resin matrix. Exemplarily, in some other embodiments, the resin matrix may also be a polyhydroxystyrene-acrylate copolymer or a cycloolefin-maleic anhydride copolymer, capable of forming covalent bonds and strong hydrogen bonds with the acrylic ligands on the surface of the upconversion nanoparticles.

[0037] Preferably, the first wavelength is 808 nanometers or 980 nanometers, and the second wavelength is 365 nanometers.

[0038] For example, please see Figure 3 , Figure 3 This is a schematic diagram illustrating the energy level transitions of upconversion nanoparticles under 980 nm infrared light excitation, as provided in this embodiment. From... Figure 3 It can be seen that 980 nm infrared light excites Yb 3+ Then, energy is transferred to Tm. 3+ It produces 365 nanometer ultraviolet light.

[0039] Furthermore, the absorption wavelength of the photoacid generator matches the second wavelength of ultraviolet light emitted by the upconversion nanoparticles. This allows the ultraviolet light generated by the upconversion nanoparticles to be efficiently absorbed by the photoacid generator and converted into photoacid, avoiding energy loss due to spectral mismatch. Thus, while ensuring photoacid yield, the dependence on the external ultraviolet light source dosage can be significantly reduced, achieving a synergistic improvement in lithography sensitivity and resolution.

[0040] Exemplarily, in some embodiments, the photoacid generator includes any one of thionium salt, iodonium salt, or ferrocene salt.

[0041] For example, in one specific example, the photoacid generator may be triphenylsulfonate perfluorobutylsulfonate (TPS-Nf), whose decomposition threshold matches the 365 nm ultraviolet light generated by the upconversion nanoparticles.

[0042] It should be noted that the present invention does not impose too many restrictions on the specific type of solvent, as long as the solvent is sufficient to completely dissolve the upconversion nanoparticles, the resin matrix, and the photoacid generator.

[0043] Exemplarily, in some embodiments, the solvent comprises a mixed solution of propylene glycol methyl ether acetate and γ-butyrolactone; wherein the molar ratio of propylene glycol methyl ether acetate to γ-butyrolactone is (2~8):(2~8). This allows for a balance between solubility and evaporation rate.

[0044] For example, in one specific example, the molar ratio of propylene glycol methyl ether acetate to γ-butyrolactone may be 7:3.

[0045] For example, in some other embodiments, the solvent is not limited to a mixed solution of propylene glycol methyl ether acetate and γ-butyrolactone. For instance, the propylene glycol methyl ether acetate can be replaced by ethoxyethyl acetate (ECA) or propylene glycol methyl ether (PGME); the γ-butyrolactone can be replaced by ethyl lactate (EL) or cyclohexanone. The solvent after the above substitutions still maintains the form of a two-component mixture, and the preferred ratio of each substitution combination can be adjusted according to the actual solubility and evaporation rate.

[0046] Preferably, in the chemically amplified photoresist, the upconversion nanoparticles account for 0.05% to 1% by mass, the resin matrix accounts for 5% to 15%, the photoacid generator accounts for 0.1% to 2%, and the solvent accounts for 80% to 95%. Thus, by precisely controlling the proportions of each component, an optimal balance between photolithography sensitivity, pattern quality, and film formation performance can be achieved.

[0047] It should be noted that the present invention does not impose excessive limitations on the specific mass percentage values ​​of each component in the chemically amplified photoresist. For example, in some embodiments, the chemically amplified photoresist contains, by mass percentage, 0.05% upconversion nanoparticles, 5% resin matrix, 0.1% photoacid generator, and 94.85% solvent; in other embodiments, the chemically amplified photoresist contains, by mass percentage, 1% upconversion nanoparticles, 15% resin matrix, 2% photoacid generator, and 82% solvent; and in still other embodiments, the chemically amplified photoresist contains, by mass percentage, 0.5% upconversion nanoparticles, 10% resin matrix, 1% photoacid generator, and 88.5% solvent.

[0048] Example 2

[0049] This embodiment provides a method for preparing chemically amplified photoresist as described in any of the above embodiments. For details, please refer to... Figure 4 , Figure 4 This is a schematic flowchart illustrating the preparation method of the chemically amplified photoresist provided in this embodiment. From... Figure 4 It can be seen that the preparation method includes:

[0050] S100: The upconversion nanoparticles coated with oleylamine were synthesized by thermal decomposition, and acrylic acid or methacrylic acid was stirred with the upconversion nanoparticles at a mass ratio of (2~10):1 for 2 hours to 48 hours under nitrogen protection at 60℃~120℃ to obtain the modified upconversion nanoparticles.

[0051] S200: The modified upconversion nanoparticles, the resin matrix, the photoacid generator, and the solvent are mixed in a mass percentage ratio of (0.05%~1%): (5%~15%): (0.1%~2%): (80%~95%) to obtain a mixture.

[0052] S300: The mixture is ultrasonically dispersed for 0.5 to 4 hours at a temperature of 20°C to 80°C, and then filtered to obtain the chemically amplified photoresist.

[0053] Since the preparation method of the chemically amplified photoresist provided in this embodiment belongs to the same inventive concept as the chemically amplified photoresist provided in any of the above embodiments, the preparation method of the chemically amplified photoresist provided in this embodiment has at least all the advantages of the chemically amplified photoresist provided in the above embodiments. For the advantages of the preparation method of the chemically amplified photoresist provided in this embodiment, please refer to the relevant description of the beneficial effects of the chemically amplified photoresist provided in the above embodiments, which will not be repeated here.

[0054] To better understand this invention, the process of preparing chemically amplified photoresist using the method provided by this invention is illustrated below.

[0055] First, oleylamine-coated upconversion nanoparticles β-NaYF4:Yb were synthesized using a thermal decomposition method. 3+ / Tm 3+ The upconversion nanoparticles, with a particle size of 6-10 nm, were stirred for 12 hours at a mass ratio of 10:1 under nitrogen protection at 80 °C. After centrifugation and purification, modified upconversion nanoparticles were obtained. Meanwhile, methacrylate-styrene copolymer (P(MMA-co-St)) was selected as the resin matrix, with a weight-average molecular weight of 12000 g / mol and a glass transition temperature of 130 °C. Triphenylsulfonate perfluorobutyl sulfonate (TPS-Nf) with a purity of not less than 99% was selected as the photoacid generator. A mixed solution of propylene glycol methyl ether acetate and γ-butyrolactone prepared at a molar ratio of 7:3 was selected as the solvent.

[0056] Then, the modified upconversion nanoparticles, the resin matrix, the photoacid generator, and the solvent were mixed in a mass percentage ratio of 0.8%:12%:1.5%:85.7% to obtain a mixture.

[0057] Next, the mixture was ultrasonically dispersed at 50°C for 1 hour.

[0058] Finally, the aggregates were removed by filtration through a 0.1 μm PTFE membrane to obtain the chemically amplified photoresist.

[0059] Example 3

[0060] This embodiment provides a photolithography process using the chemically amplified photoresist described in any of the above embodiments. Specifically, the photolithography process includes: during the exposure process:

[0061] Pre-exposure is performed using an infrared light source of the first wavelength to excite the upconversion nanoparticles in the chemically amplified photoresist to emit ultraviolet light of the second wavelength;

[0062] The main exposure is performed using the second wavelength of ultraviolet light source to complete the patterning.

[0063] Since the photolithography process provided in this embodiment belongs to the same inventive concept as the chemically amplified photoresist provided in any of the above embodiments, the photolithography process provided in this embodiment has at least all the advantages of the chemically amplified photoresist provided in the above embodiments. For the advantages of the photolithography process provided in this embodiment, please refer to the relevant descriptions of the beneficial effects of the chemically amplified photoresist provided in the above embodiments, which will not be repeated here. In addition, the photolithography process provided in this embodiment can be adapted to the chemically amplified photoresist provided in the above embodiments. By first using an infrared light source for pre-exposure to excite the upconversion nanoparticles in the chemically amplified photoresist to emit ultraviolet light of a second wavelength, and then using an ultraviolet light source for main exposure, it is possible to reduce the ultraviolet lithography dose while reducing the linewidth roughness of the pattern.

[0064] For example, in some embodiments, during the exposure process, a pre-exposure is first performed using an 808 nm or 980 nm infrared light source for 0.5 to 2 seconds to excite the upconversion nanoparticles in the chemically amplified photoresist to emit 365 nm ultraviolet light; then, a 365 nm ultraviolet light source is used for the main exposure, with an ultraviolet dose of 5 mJ / cm². 2 ~15mJ / cm 2 Complete the patterning.

[0065] To better understand the present invention, the overall process of the photolithography process provided by the present invention will be described by way of example below.

[0066] First, before exposure: the silicon wafer is pretreated with hexamethyldisilazane (HMDS) for adhesion enhancement at a temperature of 110°C for 1 minute; then the chemical amplification photoresist provided by this invention is spin-coated at a speed of 3000 rpm and a layer thickness of 100 nanometers; after spin-coating, a pre-baking treatment is performed at a temperature of 100°C for 1 minute.

[0067] Then, the silicon wafer undergoes exposure processing: first, pre-exposure is performed using a 980 nm infrared light source (power density of 50 mW / cm²). 2 An exposure time of 1 second was used to excite the upconversion nanoparticles in the chemically amplified photoresist to emit 365 nm ultraviolet light; then, a 365 nm ultraviolet light source was used for the main exposure, with an ultraviolet dose of 10 mJ / cm². 2 Complete the patterning.

[0068] Finally, post-processing is performed: first exposure followed by baking at 110°C for 1 minute; then, a 2.38% (w / w) tetramethylammonium hydroxide (TMAH) aqueous solution is used as the developer to develop the chemically amplified photoresist for 30 seconds; finally, it is rinsed with deionized water and dried with N2.

[0069] In summary, the chemically amplified photoresist and its preparation method and photolithography process provided by the present invention have the following advantages: The chemically amplified photoresist provided by the present invention includes upconversion nanoparticles, a resin matrix, a photoacid generator, and a solvent; wherein, the upconversion nanoparticles are fluoride nanocrystals doped with sensitizers and activators, and the upconversion nanoparticles can convert infrared light of a first wavelength into ultraviolet light of a second wavelength; the upconversion nanoparticles introduce polymerizable double bonds through ligand exchange, the resin matrix contains copolymerizable active sites, and the upconversion nanoparticles and the resin matrix form covalent bonds through the reaction of the polymerizable double bonds with the copolymerizable active sites. Therefore, the chemically amplified photoresist provided by this invention introduces upconversion nanoparticles, specifically fluoride nanocrystals doped with sensitizers and activators, which can convert infrared light of a first wavelength into ultraviolet light of a second wavelength. This allows the chemically amplified photoresist to utilize the strong penetrability and low scattering effect of infrared light as an excitation source. By generating ultraviolet light in situ within the chemically amplified photoresist through the upconversion nanoparticles, it can not only significantly reduce light scattering interference during the photolithography process and greatly improve photolithography resolution, but also ensure sufficient excitation of the photoacid generator by utilizing the efficient energy transfer of the upconversion nanoparticles. Thus, while reducing the ultraviolet photolithography dose, it can achieve a synergistic improvement in photolithography sensitivity and resolution. Furthermore, upconversion nanoparticles introduce polymerizable double bonds through ligand exchange, and the resin matrix contains copolymerizable active sites. The upconversion nanoparticles and the resin matrix form covalent bonds through the reaction of the polymerizable double bonds with the copolymerizable active sites, firmly "anchoring" the upconversion nanoparticles within the three-dimensional network of the resin matrix, making them part of the polymer chain. This solves the problems of easy agglomeration and sedimentation of nanoparticles in solvents and resins, achieving molecular-level uniform dispersion of nanomaterials in the resin matrix. This significantly improves the film quality of the photoresist and effectively reduces the linewidth roughness of the pattern. The chemically amplified photoresist provided by this invention supports a novel photolithography process that combines infrared and ultraviolet light exposure. Technically, it improves ultraviolet lithography sensitivity, reduces linewidth roughness, stabilizes defect density, and increases product yield. Economically, it reduces dependence on ultraviolet lithography dosage, effectively lowering the cost of ultraviolet equipment. Socially, by using low-energy, high-penetration infrared light as one of the excitation sources, it reduces the use of high-energy ultraviolet light, effectively reducing energy consumption and the risk of heavy metal pollution.

[0070] Since the preparation method and photolithography process of the chemically amplified photoresist provided by this invention belong to the same inventive concept as the chemically amplified photoresist provided by this invention, they possess at least all the advantages of the chemically amplified photoresist provided by this invention. For details regarding the advantages of the preparation method and photolithography process, please refer to the relevant descriptions of the beneficial effects of the chemically amplified photoresist provided by this invention; they will not be repeated here. Furthermore, the photolithography process provided by this invention is compatible with the chemically amplified photoresist provided by this invention. By first using an infrared light source for pre-exposure to excite the upconversion nanoparticles in the chemically amplified photoresist to emit ultraviolet light of a second wavelength, and then using an ultraviolet light source for main exposure, the linewidth roughness of the pattern can be reduced while lowering the ultraviolet lithography dose.

[0071] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention.

Claims

1. A chemically amplified photoresist, characterized in that, The system comprises upconversion nanoparticles, a resin matrix, a photoacid generator, and a solvent; wherein the upconversion nanoparticles are fluoride nanocrystals doped with sensitizers and activators, and the upconversion nanoparticles are capable of converting infrared light of a first wavelength into ultraviolet light of a second wavelength; the upconversion nanoparticles introduce polymerizable double bonds through ligand exchange, the resin matrix contains copolymerizable active sites, and the upconversion nanoparticles and the resin matrix form covalent bonds through the reaction of the polymerizable double bonds with the copolymerizable active sites.

2. The chemically amplified photoresist as described in claim 1, characterized in that, The core of the upconversion nanoparticles is NaYF4:Yb. 3+ / Tm 3+ The particle size is 6 nanometers to 10 nanometers.

3. The chemically amplified photoresist as described in claim 1, characterized in that, The ligand includes acrylic acid or methacrylic acid; the resin matrix uses methacrylate-styrene copolymer as the main resin, and the glass transition temperature of the methacrylate-styrene copolymer is in the range of 120℃~150℃.

4. The chemically amplified photoresist as described in claim 1, characterized in that, The first wavelength is 808 nanometers or 980 nanometers, and the second wavelength is 365 nanometers.

5. The chemically amplified photoresist as described in claim 1, characterized in that, The absorption wavelength of the photoacid generator matches the second wavelength of ultraviolet light emitted by the upconversion nanoparticles.

6. The chemically amplified photoresist as described in claim 1, characterized in that, The photoacid generator includes any one of thionium salt, iodonium salt, or ferrocene salt.

7. The chemically amplified photoresist as described in claim 1, characterized in that, The solvent includes a mixed solution of propylene glycol methyl ether acetate and γ-butyrolactone; wherein the molar ratio of propylene glycol methyl ether acetate to γ-butyrolactone is (2~8):(2~8).

8. The chemically amplified photoresist as described in claim 1, characterized in that, In the chemically amplified photoresist, by mass percentage, the upconversion nanoparticles are 0.05%~1%, the resin matrix is ​​5%~15%, the photoacid generator is 0.1%~2%, and the solvent is 80%~95%.

9. A method for preparing a chemically amplified photoresist as described in any one of claims 1 to 8, characterized in that, The preparation method includes: The upconversion nanoparticles coated with oleylamine were synthesized by thermal decomposition. Acrylic acid or methacrylic acid was stirred with the upconversion nanoparticles at a mass ratio of (2~10):1 for 2 hours to 48 hours under nitrogen protection at 60℃~120℃ to obtain the modified upconversion nanoparticles. The modified upconversion nanoparticles, the resin matrix, the photoacid generator, and the solvent are mixed in a mass percentage ratio of (0.05%~1%): (5%~15%): (0.1%~2%): (80%~95%) to obtain a mixture. The mixture is ultrasonically dispersed for 0.5 to 4 hours at a temperature of 20°C to 80°C, and then filtered to obtain the chemically amplified photoresist.

10. A photolithography process, characterized in that, Using the chemically amplified photoresist as described in any one of claims 1 to 8, the photolithography process includes: during the exposure process: Pre-exposure is performed using an infrared light source of the first wavelength to excite the upconversion nanoparticles in the chemically amplified photoresist to emit ultraviolet light of the second wavelength; The main exposure is performed using the second wavelength of ultraviolet light source to complete the patterning.

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