Photoresist, preparation method and photoetching method

Abstract

The invention belongs to the technical field of semiconductor manufacturing, and relates to photoresist, a preparation method and a photoetching method. The photoresist comprises a solvent, matrix resin, a photosensitizer and an additive, the photosensitizer comprises a first photosensitive component, the first photosensitive component comprises a nano-cluster containing sulfonium salt and / or iodonium salt, and the additive comprises a fluorocarboxylic acid surfactant. According to the method, the additive is added into the photoresist, so that the surface tension of the photoresist solution can be reduced, and the photoresist is changed from hydrophobicity to hydrophilicity, so that the photoresist can be better attached to the surface of the target test piece; when the electron beam acts, the nano-cluster containing sulfonium salt and / or iodonium salt in the photosensitizer generates a secondary electron multiplication effect, so that the exposure dose demand is reduced, and the sensitivity of the photoresist is improved; during development, the nano-cluster containing sulfonium salt and / or iodonium salt in the photoresist and the fluorine element in the additive are directionally migrated to the edge of the photoetching pattern, so that the line edge roughness of the photoetching pattern can be effectively improved.

Description

Technical Field

[0001] This application relates to the field of semiconductor manufacturing technology, specifically to a photoresist, its preparation method, and a photolithography method. Background Technology

[0002] Electron beam lithography, a key technology in semiconductor manufacturing, relies on the performance of its core material, electron beam photoresist, which determines the processing limits and production efficiency of devices. However, existing electron beam photoresists have consistently faced technical bottlenecks such as low sensitivity and high line edge roughness in their pursuit of higher resolutions and more advanced process nodes, thus limiting their application in semiconductor manufacturing.

[0003] There is an inherent trade-off between high resolution and high sensitivity. Taking traditional polymethyl methacrylate (PMMA) photoresist as an example, while it can achieve a high resolution of approximately 10 nm, it typically requires an exposure dose exceeding 500 μC / cm². Such a high dose requirement significantly reduces the electron beam writing speed, resulting in extremely low production throughput and failing to meet the demands of large-scale or high-efficiency fabrication. Therefore, developing photoresist materials that combine high sensitivity and high resolution has become a goal pursued by the industry.

[0004] As feature sizes shrink to below 20 nm, line edge roughness becomes a critical factor affecting device performance and uniformity. Studies have shown that when fabricating patterns with linewidths less than 20 nm, the line edge roughness of widely used chemically amplified resistive (HSQ) adhesives is typically greater than 3 nm. Excessively high line edge roughness introduces additional resistance variations, carrier scattering, and electrical instability, which can fatally impact the performance of nanoelectronic devices.

[0005] In summary, existing electron beam photoresist technology has obvious shortcomings, and there is an urgent need in this field to develop a novel electron beam photoresist with high sensitivity and low line edge roughness to promote the further development of nanofabrication technology. Summary of the Invention

[0006] In view of the shortcomings of the prior art described above, the purpose of this application is to provide a photoresist, a preparation method and a photolithography method, which can improve the sensitivity of the photoresist, reduce the exposure dose requirement, improve the edge roughness of the photolithographic pattern, and at the same time reduce the environmental risks of special solvents in the developer.

[0007] On one hand, this application provides a photoresist, including a solvent, a host resin, a photosensitizer, and additives, wherein the photosensitizer includes a first photosensitizing component, and the first photosensitizing component includes nanoclusters containing sulfonium salt and / or iodonium salt.

[0008] In an optional embodiment, the solvent accounts for 54wt%-89wt% of the photoresist and includes propylene glycol-based solvents.

[0009] In an optional embodiment, the host resin accounts for 10wt%-40wt% of the photoresist and includes epoxy-containing acrylic copolymers.

[0010] In an optional embodiment, the nanoclusters are silica nanoclusters with a particle size of 5 nm to 10 nm.

[0011] In an optional embodiment, the nanoclusters constitute 10wt%-20wt% of the photosensitizer.

[0012] In an optional embodiment, the photosensitizer accounts for 1wt%-6wt% of the photoresist.

[0013] In an optional embodiment, the photosensitizer further includes a second photosensitizing component comprising trimethylsulfur hexafluoride.

[0014] In an optional embodiment, the additive constitutes less than 1 wt% of the photoresist and includes a fluorocarboxylic acid surfactant.

[0015] On the other hand, this application provides a method for preparing photoresist, comprising the following steps: The main resin is dissolved in a solvent to obtain a mixed solution; A photosensitizer is added to the mixed solution and then ultrasonically dispersed. Additives are added to the ultrasonically dispersed mixture, and the mixture is stirred and aged.

[0016] This application also provides a photolithography method, which uses the photoresist described in any of the foregoing embodiments to perform the photolithography process, including the following steps: Photoresist is applied to the surface of the target specimen to form a photoresist coating on the surface of the target specimen; The target specimen coated with photoresist is pre-baked; The photoresist coating after pre-baking is exposed and developed.

[0017] As described above, compared with the prior art, the photoresist, preparation method, and photolithography method provided in this application have at least the following beneficial effects: Adding additives to photoresist can reduce the surface tension of the photoresist solution, changing the photoresist from hydrophobic to hydrophilic, thus enabling it to adhere better to the target sample surface. During electron beam irradiation, the nanoclusters containing sulfonium salts and / or iodonium salts in the photosensitizer generate a secondary electron multiplication effect, reducing the exposure dose requirement and effectively improving the sensitivity of the photoresist. The nanoclusters containing sulfonium salts and / or iodonium salts, as well as the additives containing fluorinated carboxylic acid surfactants, contain fluorine elements. During development, the fluorine elements in the nanoclusters and additives migrate directionally to the edges of the photolithographic pattern, which can effectively improve the line edge roughness of the photolithographic pattern.

[0018] The preparation method of this application is used to prepare the above-mentioned photoresist, and the photolithography method uses the above-mentioned photoresist to perform the photolithography process, thus also having the above-mentioned beneficial effects. Attached Figure Description

[0019] To more clearly illustrate the technical solutions of the embodiments of this application, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of this application and should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0020] Figure 1 The diagram shown is a flowchart of a photoresist preparation method provided in Embodiment 2 of this application.

[0021] Figure 2 The diagram shown is a schematic flowchart of a photolithography method provided in Embodiment 3 of this application. Detailed Implementation

[0022] To make the technical objectives, technical solutions, and technical effects of this application clearer, the technical solutions in this application will be clearly and completely described below in conjunction with embodiments. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. The components of the embodiments of this application described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0023] Therefore, the following detailed description of embodiments of this application is not intended to limit the scope of the claimed application, but merely to illustrate selected embodiments of the application. All other embodiments obtained by those skilled in the art based on the embodiments of this application without inventive effort are within the scope of protection of this application. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0024] In the description of this application, it should be noted that the terms "center", "longitudinal", "lateral", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", and "outer" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this application.

[0025] In the description of this application, unless otherwise expressly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly, for example, referring to both fixed connections and detachable connections. Furthermore, the descriptions using terms such as "one embodiment," "some embodiments," "illustrative embodiment," "example," "specific example," or "some examples" indicate that a specific feature, structure, material, or characteristic described in connection with an implementation or example is included in at least one implementation or example of this application. In this specification, illustrative expressions of the above terms do not necessarily refer to the same implementation or example. Moreover, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more implementations or examples.

[0026] Example 1 To address the problems of low sensitivity and high line edge roughness in the existing photoresist described above, this embodiment provides a photoresist that is used in the photolithography process for fabricating semiconductor devices. The photoresist includes a solvent, a host resin, a photosensitizer, and additives. The photosensitizer includes a first photosensitizing component, which comprises nanoclusters containing sulfonium salt and / or iodonium salt.

[0027] In practical applications, when subjected to electron beam, the nanoclusters containing sulfonium salt and / or iodonium salt in the photosensitive agent can generate a secondary electron multiplication effect, thereby reducing the exposure dose requirement and effectively improving the sensitivity of the photoresist. The nanoclusters containing sulfonium salt and / or iodonium salt contain fluorine elements. During development, the fluorine elements in the nanoclusters migrate directionally to the edge of the photolithographic pattern, which can effectively improve the line edge roughness of the photolithographic pattern.

[0028] In this embodiment, the solvent is used to make the photoresist flowable. The solvent can be one or more of ester solvents, ether solvents, or other suitable solvents. Optionally, the solvent is a propylene glycol methyl ether solvent. Preferably, the solvent can be, for example, propylene glycol methyl ether acetate.

[0029] In an optional embodiment, the solvent accounts for 54wt%-89wt% of the photoresist, where "wt%" represents the mass percentage and is used to describe the mass proportion of a component in the mixture. Specifically, the solvent accounts for 54wt%, 65wt%, 75wt%, 80wt%, 89wt% or other suitable values ​​in the photoresist. Further, the solvent accounts for, for example, 60wt% of the photoresist.

[0030] In this embodiment, the main resin is the main component of the photoresist, which can polymerize other components together to give the photoresist mechanical and chemical properties. When not exposed, the main resin is hydrophobic and insoluble in the developer. After exposure, it becomes hydrophilic and soluble in the developer.

[0031] In optional embodiments, the main resin may be one or more of phenolic resin, chemically amplified resin, cyclic olefin copolymer, or other suitable resin materials. Optionally, the main resin is an epoxy-containing acrylic copolymer. Preferably, the main resin is a glycidyl methacrylate-styrene copolymer with a molecular weight of 20k-50k. Specifically, the molecular weight of the glycidyl methacrylate-styrene copolymer may be 20k, 30k, 40k, 50k, or other suitable values. Further, the molecular weight of the glycidyl methacrylate-styrene copolymer is 40k.

[0032] In an optional embodiment, the proportion of the main resin in the photoresist is 10wt%-40wt%. Specifically, the proportion of the main resin in the photoresist can be 10wt%, 20wt%, 30wt%, 40wt%, or other suitable values.

[0033] Photosensitizers include photosensitive compounds and other suitable auxiliary compounds that enable them to react under light of a specific wavelength to alter the solubility of the photoresist.

[0034] In this embodiment, the photosensitizer includes a first photosensitizing component, which includes nanoclusters containing sulfonium salt and / or iodonium salt, wherein the sulfonium salt and / or iodonium salt contains fluorine, which migrates directionally to the edge of the photolithographic pattern during development, thereby helping to reduce the roughness of the line edges of the photolithographic pattern.

[0035] In an optional embodiment, the first photosensitive component may be a sulfonium-containing nanocluster, or the first photosensitive component may be an iodonium-containing nanocluster, or the first photosensitive component may be a nanocluster containing both sulfonium and iodonium.

[0036] In an optional embodiment, the nanoclusters may be silica nanoclusters. Further, the silica nanoclusters containing sulfonium salts and / or iodonium salts have a particle size of 5 nm-10 nm. Specifically, the particle size of the silica nanoclusters containing sulfonium salts and / or iodonium salts may be 5 nm, 6 nm, 7 nm, 9 nm, 10 nm, or other suitable values. Preferably, the particle size of the silica nanoclusters containing sulfonium salts and / or iodonium salts is 5 nm-8 nm.

[0037] In an optional embodiment, the proportion of nanoclusters in the photosensitizer is 10wt%-20wt%. Specifically, the proportion of nanoclusters in the photosensitizer can be 10wt%, 12wt%, 14wt%, 16wt%, 18wt%, 20wt% or other suitable values. Further, the proportion of nanoclusters in the photosensitizer is 15wt%.

[0038] In this embodiment, the photosensitizer further includes a second photosensitizing component, which comprises trimethylsulfur hexafluoride. Specifically, the trimethylsulfur hexafluoride is a photoacid-generating agent. Further, the proportion of trimethylsulfur hexafluoride in the photosensitizer is 80wt%-90wt%, specifically, the proportion of trimethylsulfur hexafluoride in the photosensitizer can be 80wt%, 82wt%, 84wt%, 86wt%, 88wt%, 90wt%, or other suitable values. Further, the proportion of trimethylsulfur hexafluoride in the photosensitizer is 85wt%.

[0039] In this embodiment, the second photosensitive component is used as a photosensitive compound, and the first photosensitive component is used as an auxiliary compound. By controlling the content of the first and second photosensitive components in the photosensitizer, as well as the particle size of the silicon dioxide nanoclusters in the first photosensitive component, it is possible to ensure that the exposure dose requirement is reduced while preventing the effect on the subsequent photolithography process.

[0040] In an optional embodiment, the proportion of photosensitizer in the photoresist is 1wt%-6wt%. Specifically, the proportion of photosensitizer in the photoresist can be, for example, 1wt%, 2wt%, 4wt%, 6wt% or other suitable values.

[0041] In the prior art, the exposure dose range during electron beam lithography is generally 1500-3000 μC / cm². However, in this embodiment, the iodonium salt can absorb photons and generate a strong acid when the electron beam is applied. The nanoclusters containing sulfonium salt and / or iodonium salt generate a secondary electron multiplication effect when the electron beam is applied. Through experimental verification of the photoresist described in this embodiment, the results show that the photoresist of this embodiment can reduce the exposure dose requirement to 700-1200 μC / cm².

[0042] In this embodiment, the additive may be one or more of plasticizers, stabilizers, surfactants, or other suitable additives. Optionally, the additive is a surfactant, preferably a fluorocarboxylic acid surfactant. Specifically, the fluorocarboxylic acid surfactant can reduce the surface tension of the photoresist solution, changing the photoresist from hydrophobic to hydrophilic, thereby improving the wettability of the photoresist and allowing it to better adhere to the surface of the target sample. Further, the fluorocarboxylic acid surfactant contains fluorine, which migrates directionally to the edge of the photolithographic pattern during development, thereby improving the roughness of the photolithographic pattern line edges.

[0043] In an optional embodiment, the additive accounts for less than 1 wt% of the photoresist. Specifically, the additive accounts for 0 wt%, 0.2 wt%, 0.4 wt%, 0.6 wt%, 0.9 wt% or other suitable values. Preferably, the additive accounts for 0.8 wt% of the photoresist.

[0044] Example 2 This embodiment provides a method for preparing photoresist, which can be used to prepare any of the photoresists in Embodiment 1.

[0045] Reference Figure 1 The photoresist preparation method provided in this embodiment includes the following steps: S101. Dissolve the main resin in a solvent to obtain a mixed solution; S102. Add a photosensitizer to the mixed solution and disperse it ultrasonically; S103. Add additives to the ultrasonically dispersed mixed solution and stir and age it.

[0046] In step S101, the main resin may be one or more of phenolic resin, chemically amplified resin, cyclic olefin copolymer or other suitable resin materials. Optionally, the main resin may be an epoxy-containing acrylic copolymer. Specifically, the main resin may be, for example, glycidyl methacrylate-styrene copolymer.

[0047] In step S101, the solvent can be one or more of ester solvents, ether solvents, or other suitable solvents. Optionally, the solvent is a propylene glycol methyl ether solvent, specifically, propylene glycol methyl ether acetate.

[0048] In step S101 of this embodiment, glycidyl methacrylate-styrene copolymer with a molecular weight of 40k can be dissolved in propylene glycol methyl ether acetate to obtain a mixed solution, and the propylene glycol methyl ether acetate accounts for 60% of the mass of the mixed solution.

[0049] In step S102, the photosensitizer includes a first photosensitizing component and a second photosensitizing component. The first photosensitizing component includes nanoclusters containing sulfonium salts and / or iodonium salts. Specifically, the first photosensitizing component can be nanoclusters containing sulfonium salts, or nanoclusters containing iodonium salts, or nanoclusters containing both sulfonium salts and iodonium salts. The nanoclusters can be, for example, silica nanoclusters. The second photosensitizing component may include trimethylsulfur hexafluoride, which is a photoacid-generating agent.

[0050] The photosensitizer can react under light of a specific wavelength to change the solubility of the photoresist. By adding silica nanoclusters containing sulfonium salt and / or iodonium salt to the photosensitizer, and the silica nanoclusters containing sulfonium salt and / or iodonium salt containing fluorine, the fluorine migrates directionally to the edge of the photolithographic pattern during development, which can effectively reduce the line edge roughness of the photolithographic pattern.

[0051] In an optional embodiment, the step of adding a photosensitizer to the mixed solution includes sulfonium-containing silica nanoclusters and trimethylsulfur hexafluoride. The particle size of the sulfonium-containing silica nanoclusters can be, for example, 5 nm-8 nm, and the proportion of the sulfonium-containing silica nanoclusters in the photosensitizer can be, for example, 15 wt%, while the proportion of trimethylsulfur hexafluoride in the photosensitizer can be, for example, 85 wt%. Subsequently, the mixed solution is transferred to an ultrasonic dispersion device, where high-frequency ultrasonic vibrations achieve a uniform mixing effect.

[0052] In step S103, the additive may be one or more of plasticizers, stabilizers, surfactants, or other suitable additives. Optionally, the additive is a surfactant, specifically, the additive may be, for example, a fluorocarboxylic acid surfactant.

[0053] In an optional embodiment, in the step of adding additives to the ultrasonically dispersed mixed solution, a fluorocarboxylic acid surfactant is added to the ultrasonically dispersed mixed solution and stirred and aged, while controlling the aging time to be greater than or equal to 12 hours, specifically, the aging time can be, for example, 24 hours.

[0054] Example 3 This embodiment provides a photolithography method that can perform photolithography on at least any of the photoresists in Embodiment 1.

[0055] Reference Figure 2 The photolithography method provided in this embodiment includes the following steps: S201. Apply photoresist to the surface of the target specimen to form a photoresist coating on the surface of the target specimen; S202. Pre-baking the target sample coated with photoresist; S203. Expose and develop the photoresist coating after pre-baking.

[0056] In step S201, the target specimen can be a substrate, an epitaxial material, or other suitable device structure. Specifically, the target specimen can be, for example, a sapphire substrate.

[0057] In an optional embodiment, in the step of applying photoresist to the surface of the target specimen, the photoresist is taken out of the container and sprayed onto the surface of the target specimen in the coating machine. Then, the target specimen is driven to rotate, for example, at a speed of 3000 rpm, so that the photoresist flows to the edge under the action of centrifugal force to form a photoresist coating on the surface of the target specimen and make the thickness of the photoresist coating reach a preset thickness, for example, the spin coating thickness of the photoresist can be controlled to be 80 nm.

[0058] In step S202, drying equipment or other suitable methods can be used to pre-dry the target specimen. The specific process parameters during the pre-drying process can be set according to actual needs.

[0059] In an optional embodiment, for example, the target sample coated with photoresist can be placed on a hot plate for pre-baking treatment, and the hot plate temperature is set to 110°C and the pre-baking time is 90s, so that the solvent in the photoresist evaporates and the film stress is reduced.

[0060] In step S203, the photoresist coating can be exposed and developed using an exposure device and a development device, respectively. Optionally, during the exposure of the target sample after pre-baking, the exposure dose is 700-1200 μC / cm², specifically, for example, 700 μC / cm², 800 μC / cm², 900 μC / cm², 1000 μC / cm², 1100 μC / cm², 1200 μC / cm², or other suitable values.

[0061] In an optional embodiment, in the step of exposing the pre-baked target specimen, the target specimen is placed in the exposure device, the focal length is adjusted to 1.0, and the exposure energy is controlled to 700 μC / cm. 2 The photoresist coating on the surface of the target sample after pre-baking is selectively irradiated, causing the photosensitizer in the photoresist coating to undergo a photochemical reaction, thereby changing the chemical properties of the irradiated area of ​​the photoresist coating.

[0062] In an optional embodiment, in the step of developing the target sample after pre-baking, the target sample is placed in a developing device, and a developing solution is applied to the exposed photoresist coating surface to develop the photoresist coating. The process parameters in the developing operation can be set according to actual needs.

[0063] In an optional embodiment, the developer may be, for example, a tetramethylammonium hydroxide solution with a concentration of 2.38%, a developing temperature of 23°C, and a developing time of 60 seconds. The developing process allows the photoresist regions whose chemical composition has changed during exposure to dissolve in the developer, thereby revealing the pattern in the photoresist layer.

[0064] In summary, the photolithography method of this embodiment, through four steps of spin coating, pre-baking, exposure, and development, can utilize at least any of the photoresists in Embodiment 1 to carry out the photolithography process, and therefore also has the beneficial effects of Embodiment 1.

[0065] The above description is only a partial preferred embodiment of this application and is not intended to limit this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A photoresist, characterized in that, include: Solvents, main resins, photosensitizers, and additives; The photosensitizer includes a first photosensitizing component, which comprises nanoclusters containing sulfonium salt and / or iodonium salt.

2. The photoresist according to claim 1, characterized in that, The solvent accounts for 54wt%-89wt% of the photoresist and includes propylene glycol-based solvents.

3. The photoresist according to claim 1, characterized in that, The main resin accounts for 10wt%-40wt% of the photoresist and includes epoxy-containing acrylic copolymers.

4. The photoresist according to claim 1, characterized in that, The nanoclusters are silicon dioxide nanoclusters, and the particle size of the silicon dioxide nanoclusters is 5nm-10nm.

5. The photoresist according to claim 1, characterized in that, The nanoclusters account for 10wt%-20wt% of the photosensitizer.

6. The photoresist according to claim 1, characterized in that, The photosensitizer accounts for 1wt%-6wt% of the photoresist.

7. The photoresist according to claim 1, characterized in that, The photosensitizer further includes a second photosensitizing component, which includes trimethylsulfur hexafluoride.

8. The photoresist according to claim 1, characterized in that, The additives constitute less than 1 wt% of the photoresist and include fluorocarboxylic acid surfactants.

9. A method for preparing photoresist, characterized in that, Includes the following steps: The main resin is dissolved in a solvent to obtain a mixed solution; A photosensitizer is added to the mixed solution and then ultrasonically dispersed. Additives are added to the ultrasonically dispersed mixture, and the mixture is stirred and aged.

10. A photolithography method, comprising performing a photolithography process using the photoresist according to any one of claims 1-8, characterized in that, Includes the following steps: Photoresist is applied to the surface of the target specimen to form a photoresist coating on the surface of the target specimen; The target specimen coated with photoresist is pre-baked; The photoresist coating after pre-baking is exposed and developed.

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