EUV Lithography Equipment and EUV Lithography Method

Abstract

The present invention provides an EUV lithography apparatus and an EUV lithography method. By condensing moisture on the surface of a photoresist layer on a wafer that has undergone a hydrophilic surface treatment, a thin water film is formed. Thus, by utilizing the characteristic that the refractive index of water is greater than that of air, the effect of shortening the effective wavelength is achieved, and further, the pattern resolution and contrast of EUV lithography are enhanced, which is beneficial for producing finer structures than in the past. The solution is simple and the equipment upgrade cost is low.

Description

Technical Field

[0001] The present invention relates to the field of integrated circuit manufacturing technology, and particularly to an EUV lithography apparatus and an EUV lithography method. Background Art

[0002] A lithography apparatus can project the circuit pattern on a photo mask onto a wafer for manufacturing an integrated circuit (IC) at a magnified or reduced ratio. Moreover, there is the following relationship (i.e., Rayleigh criterion) between the feature size of the circuit pattern on the wafer and the parameters of the lithography apparatus: CD = k1 * λ / NA. Wherein, λ is the wavelength of the exposure light source used in the lithography apparatus, NA is the numerical aperture of the projection system in the lithography apparatus, k1 is an adjustment factor related to the exposure process, also known as the Rayleigh constant, and CD is the feature size (or critical dimension) of the circuit pattern on the wafer.

[0003] With the rapid development of integrated circuit manufacturing technology, the feature size CD of integrated circuits has been continuously reduced, and the integration degree has been gradually improved. The wavelength λ of the exposure light source used in the lithography apparatus has also gradually decreased. The current mainstream lithography technology uses a laser with a wavelength of 193 nm (deep ultraviolet lithography, i.e., DUV) as the exposure light source. Based on the exposure processes (such as double exposure and multiple exposure, etc.) implemented by DUV lithography apparatuses, it has gradually approached the lithography limit that can be achieved by the DUV wavelength, and it is difficult to meet the further miniaturization requirements of the feature size CD of integrated circuits. Therefore, an extreme ultraviolet lithography apparatus (EUVL) using an extreme ultraviolet (EUV) with a wavelength of 13.5 nm has emerged, and it shows greater competitive advantages and has become the first choice for the next generation of lithography technology.

[0004] Among them, how to improve the pattern resolution of EUV lithography apparatuses and EUV lithography methods to produce finer structures than before is one of the hot issues concerned by those skilled in the art. Summary of the Invention

[0005] The purpose of the present invention is to provide an EUV lithography apparatus and an EUV lithography method, which can improve the pattern resolution of EUV lithography technology with a simpler solution and at a lower cost, and produce finer structures than before.

[0006] To achieve the above object, the present invention provides an EUV lithography apparatus, which includes an EUV light source, an illumination system, a mask stage, a projection system, and a wafer stage arranged in sequence along the optical path. Moreover, the EUV lithography apparatus further includes a gas supply system arranged around the wafer stage. The gas supply system is configured to supply water vapor to the hydrophilic surface of the photoresist layer on the wafer on the wafer stage before exposing the photoresist layer on the wafer, and at least part of the supplied water vapor condenses on the hydrophilic surface of the photoresist layer to form a water film.

[0007] Optionally, the gas supply system is opened during the movement of the wafer stage, and supplies water vapor to the hydrophilic surface of the photoresist layer on the wafer placed on the wafer stage through a carrier gas flow with a required humidity mixed with deionized water; and the gas supply system is closed during exposure.

[0008] Optionally, the carrier gas flow provided by the gas supply system includes nitrogen and / or inert gas.

[0009] Optionally, the required humidity is at least 60%.

[0010] Optionally, the thickness of the water film is at least λ / 2n nanometers, where λ is the wavelength of the EUV light source and n is the refractive index of water.

[0011] Optionally, the thickness of the water film is λ / 2n nanometers or a multiple of the optimal transmission coefficient of the projection system.

[0012] Optionally, the EUV lithography apparatus further includes a hydrophilic surface treatment system arranged around the wafer stage. The hydrophilic surface treatment system is configured to perform a hydrophilic surface treatment on the photoresist layer by a controllable plasma treatment process before the gas supply system supplies water vapor, so that the original hydrophobic surface of the photoresist layer becomes a hydrophilic surface or the hydrophilicity of the original hydrophilic surface of the photoresist layer is enhanced.

[0013] Optionally, the plasma used in the plasma treatment process includes at least one of N, O, and H.

[0014] Based on the same inventive concept, the present invention also provides an EUV lithography method, which includes the following steps:

[0015] Provide a wafer, on which a photoresist layer is formed;

[0016] Perform a hydrophilic surface treatment on the photoresist layer by a controllable plasma treatment process, so that the original hydrophobic surface of the photoresist layer becomes a hydrophilic surface or the hydrophilicity of the original hydrophilic surface of the photoresist layer is enhanced;

[0017] Water vapor is provided to the hydrophilic surface of the photoresist layer, and at least a part of the provided water vapor condenses on the hydrophilic surface of the photoresist layer to form a water film;

[0018] The pattern on the EUV photomask is exposed through the water film to the photoresist layer by using an EUV light source.

[0019] Optionally, the plasma used in the plasma treatment process includes at least one of N, O, and H.

[0020] Optionally, water vapor is provided to the hydrophilic surface of the photoresist layer through a carrier gas stream with a required humidity mixed with deionized water.

[0021] Optionally, the carrier gas stream includes nitrogen and / or an inert gas.

[0022] Optionally, the required humidity is at least 60%.

[0023] Optionally, the thickness of the water film is at least λ / 2n nanometers, where λ is the wavelength of the EUV light source and n is the refractive index of water.

[0024] Optionally, the thickness of the water film is λ / 2n nanometers, or a multiple of the optimal transmission coefficient of the projection system in the EUV lithography equipment.

[0025] Compared with the prior art, the technical solution of the present invention has at least one of the following beneficial effects:

[0026] 1. By condensing moisture on the surface of the photoresist layer that has undergone hydrophilic surface treatment to form a thin water film, the characteristic that the refractive index of water is greater than that of air is utilized to achieve the effect of shortening the effective wavelength, thereby further enhancing the pattern resolution and contrast of EUV lithography, which is beneficial for producing finer structures than before.

[0027] 2. Compared with the original EUV lithography equipment, a corresponding gas supply system is mainly added, and the structures of the original EUV light source, illumination system, mask stage, projection system, and wafer stage are not changed, and the equipment upgrade cost is low. Description of the Drawings

[0028] Figure 1 is a schematic structural diagram of an existing EUV lithography equipment.

[0029] Figure 2 is a schematic structural diagram of the EUV lithography equipment according to an embodiment of the present invention.

[0030] Figure 3 is a schematic cross-sectional structural diagram of the EUV photomask used in the EUV lithography equipment according to an embodiment of the present invention.

[0031] Figure 4 It is a schematic cross-sectional structure diagram of a photoresist layer and a water film on a wafer in an EUV lithography apparatus according to an embodiment of the present invention.

[0032] Figure 5 It is a schematic structural diagram of an EUV lithography apparatus according to another embodiment of the present invention.

[0033] Figure 6 It is a flowchart of an EUV lithography method according to an embodiment of the present invention. Detailed implementation manners

[0034] In the following description, numerous specific details are given to provide a more thorough understanding of the present invention. However, it is obvious to those skilled in the art that the present invention can be implemented without one or more of these details. In other instances, some well-known technical features are not described to avoid confusion with the present invention. It should be understood that the present invention can be implemented in different forms and should not be construed as limited to the embodiments presented herein. On the contrary, these embodiments are provided to make the disclosure thorough and complete, and to fully convey the scope of the present invention to those skilled in the art. In the drawings, for clarity, the dimensions and relative dimensions of layers and regions may be exaggerated. The same reference numerals denote the same elements throughout the drawings.

[0035] It should be understood that when an element or layer is referred to as "on" another element or layer, it can be directly on, adjacent to, connected to, or coupled to the other element or layer, or there may be intervening elements or layers. In contrast, when an element is referred to as "directly on" another element or layer, there are no intervening elements or layers. It should be understood that although the terms first, second, third, etc. may be used to describe various elements, components, regions, layers, parts, and / or processes, these elements, components, regions, layers, parts, and / or processes should not be limited by these terms. These terms are only used to distinguish one element, component, region, layer, part, and / or process from another element, component, region, layer, part, and / or process. Thus, without departing from the teachings of the present invention, the first element, component, region, layer, part, and / or process discussed below may be denoted as the second element, component, region, layer, part, and / or process.

[0036] Spatial relationship terms such as "under", "below", "underlying", "beneath", "above", "upper", "on the top surface", "on the bottom surface", "front", "back", etc. may be used herein for convenience of description to describe the relationship of one element or feature shown in the figure with other elements or features. It should be understood that, in addition to the orientations shown in the figure, the spatial relationship terms are also intended to include different orientations of the device in use and operation. For example, if the device in the attached drawing is flipped, then an element or feature described as "under other elements" or "beneath it" or "under it" or "on the bottom surface" or "on its back surface" will be oriented "above" or "on the top" or "front" of other elements or features. Thus, the exemplary terms "under", "beneath" and "on the back" can include both upper and lower orientations. The device may be otherwise oriented (rotated 90 degrees or other orientations) and the spatial descriptors used herein are accordingly interpreted.

[0037] The purpose of the terms used herein is only to describe specific embodiments and is not a limitation of the present invention. As used herein, the singular forms "a", "an" and "the" are also intended to include the plural forms unless the context clearly dictates otherwise. It should also be understood that the terms "comprising" and / or "including", when used in this specification, identify the presence of the stated features, integers, steps, operations, elements and / or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components and / or groups. As used herein, the term "and / or" includes any and all combinations of the related listed items.

[0038] As described in the background art, how to improve the pattern resolution of EUV lithography equipment and EUV lithography methods to produce finer structures than before is one of the hot issues concerned by those skilled in the art.

[0039] The current EUV lithography equipment is a dry lithography equipment, and its typical structure is as Figure 1 shown, including: an EUV light source 10, an illumination system 11, a mask stage 12 for placing an EUV mask 20, a projection system 13, and a wafer stage 14 for placing a wafer 30.

[0040] In the prior art, in order to improve the pattern resolution of EUV lithography equipment and its EUV lithography methods to produce finer structures than before to meet the requirement of further miniaturization of the feature size CD of integrated circuits (e.g., below 5 nm), it is generally achieved by upgrading the EUV lithography equipment, that is, improving the structures of the EUV light source, the illumination system 11, the projection system 13, etc. For example: developing a projection system with a higher image-side numerical aperture NA than before to further improve the resolution ability of the EUV lithography equipment. Obviously, this method has a higher cost.

[0041] Based on this, the present invention provides an EUV lithography apparatus and an EUV lithography method, which can form a thin water film on the hydrophilic surface of the photoresist layer on the wafer before exposure, and then utilize the characteristic that the effective wavelength becomes shorter in a water film during exposure to further enhance the pattern resolution and contrast of EUV lithography. Thus, with a simpler solution and at a lower cost, the effect of improving the pattern resolution of EUV lithography technology is achieved, and finer structures can be produced than before.

[0042] The following will Figure 2 - be Figure 6 described in detail in conjunction with the accompanying drawings

[0043] Please refer to Figure 2 , an EUV lithography apparatus provided by an embodiment of the present invention not only includes an EUV light source 10, an illumination system 11, a mask stage 12, a projection system 13, and a wafer stage 14 arranged in sequence along the optical path, but also includes a gas supply system 15 arranged outside the wafer stage 14.

[0044] Among them, the EUV light source 10 is configured to generate an EUV exposure beam with a wavelength λ of 5 nm to 30 nm (where the wavelength λ of 13.6 nm is the most commonly used). The EUV light source 10 can be a synchrotron radiation source such as a free electron laser (FEL), which can generate coherent radiation with very high spectral brightness.

[0045] The illumination system 11 is configured to adjust the angle, focal length, intensity, etc. of the EUV exposure beam emitted by the EUV light source 10, so that the EUV exposure beam emitted by the EUV light source 10 can be transmitted to the EUV photomask placed on the mask stage 12. The illumination system 11 may include various types of optical components for guiding, shaping, reflecting, or controlling the EUV exposure beam emitted by the EUV light source 10, such as refractive, reflective, magnetic, electromagnetic, electrostatic, or other types of optical components or any combination thereof.

[0046] The mask table 12 is configured to support the support structure of the reflective EUV photomask 20. It can use mechanical, vacuum, electrostatic or other clamping techniques, and accurately fix, move and position the reflective EUV photomask 20 according to certain parameters to ensure that the reflective EUV photomask 20 is in the required position relative to the projection system 13. The mask table 12 bears the weight of the reflective EUV photomask 20 and fixes the reflective EUV photomask 20 in a certain way, which depends on the orientation of the reflective EUV photomask 20, the design of the lithography equipment and other conditions, such as whether the reflective EUV photomask 20 is maintained in a vacuum environment. The mask table 12 can be a frame or a table, which can be fixed or movable according to requirements.

[0047] Wherein, please refer to Figure 3 , the blank body of the reflective EUV photomask 20 generally has a substrate (such as glass or quartz, etc.) 200, a reflective film stack layer (for example, formed by alternately stacking molybdenum Mo and silicon Si, also known as a reflective structure) 201, a capping layer 202 (for example, including at least one of ruthenium, ruthenium alloy, ruthenium oxide), and an absorption layer (which can be a single-layer film or a multi-layer film, for example, including at least one of cobalt, tellurium, hafnium, nickel, tantalum, chromium, tantalum-based materials, chromium-based materials, etc.) 203 stacked in sequence. The reflective film stack layer 201 is used to reflect the EUV exposure beam, and the absorption layer 203 is used to absorb the EUV exposure beam and will be etched into a specified pattern (i.e., a circuit pattern) 203a required for integrated circuit manufacturing. The absorption layer 203 has a low EUV reflectivity, for example, less than 3 - 5%. The reflective EUV photomask 20 also has a border pattern 204 passing through the absorption layer 203, the capping layer 202 and the reflective film stack layer 201, and a backside conductive layer 205 (for example, including at least one of chromium, chromium-based materials, tantalum or tantalum-based materials, etc.) on the back surface of the substrate 200.

[0048] Please refer to Figure 2 and Figure 4 , the wafer stage 14 is configured to fix the wafer 30, and it can accurately fix, move and position the wafer 30 according to certain parameters. Among them, a photoresist layer 31 is formed on the surface of the wafer 30.

[0049] The projection system 13 is configured to transmit an EUV exposure beam reflected by a reflective EUV photomask on the mask stage 12 to a wafer 30 placed on the wafer stage 14, and then expose the photoresist layer 31, whereby the pattern on the reflective EUV photomask is projected onto the photoresist layer 31 in the target area of the wafer 30. The projection system 13 of this embodiment should be broadly understood to include various types of projection systems, including refractive, reflective, catadioptric, magnetic, electromagnetic, and electrostatic optical systems or any combination thereof, which should be appropriately determined, for example, according to the exposure radiation used or other factors such as the use of immersion or the use of a vacuum.

[0050] Please refer to Figure 2 and Figure 4 , the gas supply system 15 is configured to supply water vapor to the hydrophilic surface of the photoresist layer 31 before exposing the photoresist layer 31 on the wafer 30 on the wafer stage 14, and at least part of the supplied water vapor condenses on the hydrophilic surface of the photoresist layer 31 to form a water film 32. The "water vapor" can be gaseous water or very small liquid water (such as liquid foggy water) that can be transported by a carrier gas (such as nitrogen and / or inert gas).

[0051] Optionally, the gas supply system 15 is opened during the movement of the wafer stage 14, and water vapor is supplied to the hydrophilic surface of the photoresist layer 31 on the wafer 30 placed on the wafer stage 14 through a carrier gas stream mixed with deionized water and having a required humidity (such as at least 60%); and the gas supply system 15 is closed during the exposure (i.e., during the exposure of the photoresist layer 31). Among them, the carrier gas stream can include nitrogen and / or inert gas, and the inert gas includes, for example, one or more mixtures of argon, helium, etc.

[0052] Among them, the fundamental reason why the water film 32 formed on the surface of the photoresist layer 31 can achieve a better lithography pattern resolution effect is that: the water film 32 is in close contact with the surface of the photoresist layer 31, and the refractive index n is greater than that of air (the refractive index is 1). When the wavelength of the EUV exposure beam emitted by the EUV light source 10 is λ, the wavelength in the water film becomes λ / n. Further, according to the Rayleigh criterion CD = k1*λ / NA, when the Rayleigh constant k1 and the numerical aperture NA of the projection system remain unchanged, the wavelength of light in the water film becomes shorter, which will cause the feature size CD of the pattern formed after the photoresist layer 31 is exposed to become smaller, and thus define a finer pattern. Therefore, adding this layer of water film 32 can achieve a better lithography pattern resolution effect. For example, when the refractive index n of the water film 32 = 1.33 and the wavelength λ of the EUV exposure beam emitted by the EUV light source 10 = 13.6 nanometers, the wavelength in the water film 32 is 13.6 / 1.33 ≈ 10 nm.

[0053] In addition, the thickness of the water film 32 depends on the hydrophilic ability of the hydrophilic surface of the photoresist layer 31, and is at least half the wavelength of the EUV beam in water, i.e., λ / 2n nanometers. Optionally, the thickness of the water film 32 formed on the surface of the photoresist layer 31 is at least λ / 2n nanometers and does not exceed 20 nanometers, where λ is the wavelength of the EUV light source and n is the refractive index of water. Preferably, the thickness of the water film 32 is λ / 2n nanometers or a multiple of the optimal transmission coefficient of the projection system 13. As an example, when n = 1.33 and λ = 13.6 nanometers, the thickness of the water film 32 is λ / 2n = 13.6 nanometers / (2 * 1.33) ≈ 5 nanometers.

[0054] It should be noted that the thickness of the water film 32 formed on the surface of the photoresist layer 31 should not be too thin (e.g., less than λ / 2n nanometers). Otherwise, on the one hand, under the action of surface tension, there is a water film 32 in some places on the surface of the photoresist layer 31 and no water film in other places, resulting in uneven thickness of the water film 32 formed on the surface of the photoresist layer 31 across the entire wafer 30, which affects the uniformity of the feature size after EUV lithography. On the other hand, insufficient thickness of the water film 32 causes part or all of it to evaporate naturally during exposure, thereby affecting the lithography effect.

[0055] At the same time, the thickness of the water film 32 formed on the surface of the photoresist layer 31 should not be too thick (e.g., greater than 20 nanometers). The upper surface of the water film 32 is bounded by air, and the lower surface is bounded by the upper surface of the photoresist layer 31, that is, the thickness of the water film 32 is not enough to contact the surface of the last objective lens in the projection system 13, and there is still an air gap between the water film 32 and the projection system 13. This is because, on the one hand, the EUV mask is reflective, and the light reflected into the projection system has a relatively large loss compared to the light emitted from the EUV light source. If the water film 32 on the photoresist layer 31 is too thick, it will absorb too much EUV light, resulting in insufficient exposure of the photoresist layer 31. On the other hand, if the water film 32 on the photoresist layer 31 is too thick, it will absorb too much EUV light and heat up, thereby causing the problem of thermal deformation of the photoresist layer 31, affecting the exposure effect.

[0056] In addition, when the original surface of the photoresist layer 31 (such as positive photoresist and chemically amplified resist (CAR)) coated on the wafer 30 is a hydrophobic surface, before it is placed in the EUV lithography equipment in this embodiment for exposure, it is necessary to pre-treat the hydrophobic surface of the photoresist layer 31 on the wafer 30 into a hydrophilic surface with strong hydrophilicity. This treatment (i.e., hydrophilic surface treatment) can be achieved by means of controllable plasma treatment (such as using at least one plasma of N, O, H, etc.). When the surface of the photoresist layer 31 (such as negative photoresist) coated on the wafer 30 is hydrophilic by itself, but its hydrophilicity is not high enough to meet the requirements of the exposure process in the EUV lithography process of this embodiment. Therefore, before it is placed in the EUV lithography equipment in this embodiment for exposure, it is also necessary to pre-treat the original hydrophilic surface of the photoresist layer 31 on the wafer 30 to enhance the hydrophilic ability of its hydrophilic surface. This pretreatment (i.e., hydrophilic surface treatment) can be achieved by means of controllable plasma treatment (such as using at least one plasma of N, O, H, etc.). Obviously, regardless of whether the original surface of the photoresist layer 31 on the wafer 30 is hydrophilic or hydrophobic, in this embodiment, before the wafer 30 is placed in the EUV lithography equipment for exposure, it is necessary to pre-treat the original surface of the photoresist layer 31 on the wafer 30 to enhance its hydrophilic surface treatment so that its surface can form a water film 32 with sufficient thickness, uniform thickness and can be maintained during exposure after absorbing water. Further, the hydrophilic ability of the surface of the photoresist layer 31 after treatment can not only maintain a certain thickness of the water film 32 during exposure, but also after all the target areas of the wafer are exposed, when the wafer is in a room temperature environment, the water film on the photoresist layer 31 can naturally evaporate completely after a time slightly longer than the time for exposing the entire wafer, without the need to pass through a drying device to dry the wafer surface, simplifying the process and saving costs.

[0057] Among them, positive photoresist, negative photoresist and chemically amplified resist (CAR) all include: resin (resin / polymer), as an adhesive for different materials in the photoresist, giving the mechanical and chemical properties of the photoresist (such as adhesion, film thickness, thermal stability, etc.); photosensitizer, the photosensitizer can undergo a photochemical reaction with light energy; solvent (Solvent), maintaining the liquid state of the photoresist and making it have good fluidity; additive (Additive), used to change certain characteristics of the photoresist, such as adding a dye to improve the reflection of the photoresist.

[0058] As an example, in a negative photoresist, the resin is polyisoprene (a natural rubber), the solvent is xylene, and the photosensitizer is a photosensitive agent that releases nitrogen after exposure. The generated free radicals form cross-links between rubber molecules, making it insoluble in the developer. The negative photoresist swells due to the solvent in the exposed area, and the photoresist easily reacts with nitrogen during exposure to inhibit cross-linking. In a positive photoresist, the resin is phenol formaldehyde of linear phenolic resin, which provides the adhesion and chemical resistance of the photoresist. When there is no dissolution inhibitor, the linear phenolic resin will dissolve in the developer. The photosensitizer is a photoactive compound (PAC), and the most common one is diazonaphthoquinone (DNQ). Before exposure, DNQ is a strong dissolution inhibitor that reduces the dissolution rate of the resin. After ultraviolet exposure, DNQ chemically decomposes in the photoresist and becomes a solubility enhancer, greatly increasing the solubility factor in the developer to 100 or higher. This exposure reaction produces carboxylic acid in DNQ, which has a high solubility in the developer. The positive photoresist has a good contrast, so the generated pattern has good resolution. In a chemically amplified photoresist (CAR), the resin is polyethylene (PHS) with chemically protected groups (t-BOC) and is insoluble in water (hydrophobic). The photosensitizer is a photoacid generator (PAG). After the photoresist is exposed, the PAG in the exposed area undergoes a photochemical reaction to produce an acid. When this acid is post-exposure baked (PEB), it acts as a chemical catalyst to remove the protecting groups on the resin, so that the photoresist in the exposed area changes from being insoluble in water to being highly soluble in a developer mainly composed of water (hydrophilic). The chemically amplified photoresist has a very fast exposure speed, about 10 times that of the DNQ linear phenolic resin photoresist, and has good optical sensitivity to short-wavelength light sources, can provide steep sidewalls, and has a high contrast, such as high resolution with dimensions of 0.25 μm and below.

[0059] Further, please combine with Figures 2 to 4 , the working process of the EUV lithography equipment in this embodiment includes:

[0060] First, fix the EUV mask 20 to the mask stage 12, and fix the wafer 30 with a photoresist layer to the wafer stage 14;

[0061] Then, before exposing the photoresist layer on the wafer 30, for example, during the process of controlling the wafer stage to move the target area of the wafer 30 to the exposure field of the projection system 13, the gas supply system 15 is turned on to supply water vapor to the hydrophilic surface of the photoresist layer on the wafer 30 placed on the wafer stage 14 through a carrier gas stream mixed with deionized water at a required humidity (for example, at least 60%), thereby forming a uniformly thick water film 32 on the global surface of the photoresist layer 31 on the wafer 30 due to water adsorption.

[0062] After that, the gas supply system 15 is turned off, and the EUV light source 10 is turned on. The EUV exposure beam emitted by it first passes through the illumination system 11 and is incident on the EUV mask 20 at the mask stage 12. After being reflected by the EUV mask 20, it is incident on the projection system 13. The projection system 13 focuses the beam through the water film 32 onto the target area of the photoresist layer 31 of the wafer 30 on the wafer stage 14 to complete one exposure.

[0063] It should be understood that in the EUV lithography apparatus of this embodiment, the EUV light source 10, the illumination system 11, the mask stage 12, the projection system 13, the wafer stage 14, and the gas supply system 15 can be integrated in the same frame housing, or at least one of them can be set up separately relative to other modules.

[0064] In addition, each subsystem of the EUV lithography apparatus described in this embodiment (i.e., the EUV light source 10, the illumination system 11, the mask stage 12, the projection system 13, the wafer stage 14, and the gas supply system 15) is only taken as a specific example, and does not mean that the EUV lithography apparatus of the present invention only has these subsystems. It can also include other subsystems in the existing EUV lithography apparatus, such as a coating system for forming a photoresist layer on the wafer surface, a measurement system for measuring corresponding parameters in the lithography process (including sensors, etc.), a development system for developing the photoresist layer 31 on the exposed wafer 30, a manipulator system for handling and replacing the wafer 30 and / or the mask 20, a cleaning system for cleaning the wafer 30 after development, a hydrophilic surface treatment system for performing hydrophilic surface treatment on the photoresist layer 31, etc., at least one of which.

[0065] For example, please refer to Figure 5, Another embodiment of the present invention provides an EUV lithography apparatus, which not only has an EUV light source 10, an illumination system 11, a mask stage 12, a projection system 13, a wafer stage 14, and a gas supply system 15, but also has a hydrophilic surface treatment system 16 disposed around the wafer stage 14. The hydrophilic surface treatment system 16 is used to perform a hydrophilic surface treatment on the photoresist layer on the wafer 30 by a controllable plasma treatment process before the gas supply system 15 supplies water vapor to the photoresist layer on the wafer 30, so that the original hydrophobic surface of the photoresist layer becomes a hydrophilic surface or the hydrophilicity of the original hydrophilic surface of the photoresist layer is enhanced. Among them, the thickness of the water film formed on the surface of the photoresist layer after the water supply system is opened is controlled by the hydrophilic level of the photoresist layer surface (i.e., the hydrophilic ability of the photoresist layer surface). The hydrophilic surface treatment system 16 can perform plasma treatment on the surface of the photoresist layer by using a plasma including at least one of N, O, and H, so that the original hydrophobic surface of the photoresist layer becomes a hydrophilic surface with sufficient hydrophilicity, or the hydrophilicity of the original hydrophilic surface of the photoresist layer is enhanced.

[0066] Optionally, the process pressure of the plasma treatment process for performing hydrophilic surface treatment on the photoresist layer surface is relatively low, for example, 10 mTorr to 100 mTorr. The lower process pressure facilitates improving the uniformity of the distribution of atoms such as N, O, and H on the surface of the photoresist layer 31 after the plasma treatment process, and further facilitates the formation of a water film with a uniform film thickness.

[0067] For another example, please refer to Figure 2 or Figure 5 , Another embodiment of the present invention provides an EUV lithography apparatus, which not only has an EUV light source 10, an illumination system 11, a mask stage 12, a projection system 13, at least two cascaded wafer stages 14, and a gas supply system 15 disposed around the corresponding wafer stage 14, but also has a robot system (not shown) for transporting the wafer 30. One or more of the wafer stages 14 can be used for steps other than exposing the wafer (such as plasma treatment, pre-cleaning, etc.), and one or more of the other wafer stages 14 are used for exposure.

[0068] In summary, the EUV lithography apparatus of the present invention can add a corresponding gas supply system relative to the original EUV lithography apparatus, and then condense moisture on the hydrophilic photoresist layer surface to form a thin layer of water film before exposing the photoresist layer on the wafer. Thus, the effect of shortening the effective wavelength is achieved by using the characteristic that the refractive index of water is greater than that of air, and further the pattern resolution and contrast of EUV lithography are enhanced. It does not change the structures of the original EUV light source, illumination system, mask stage, projection system, and wafer stage, the equipment upgrade cost is low, and it is beneficial to produce finer structures than before.

[0069] Based on the same inventive concept, the present invention also provides an EUV lithography method, which is preferably implemented by using the EUV lithography equipment of the present invention, or can also be implemented by using existing EUV lithography equipment supplemented with existing gas supply systems, hydrophilic surface treatment systems (such as some existing plasma treatment equipment), etc. Among them, please refer to Figure 6 and further in combination with Figures 2 to 5 , the EUV lithography method of this embodiment specifically includes the following steps:

[0070] S1, provide a wafer 30, on which a photoresist layer 31 is formed;

[0071] S2, perform a hydrophilic surface treatment on the photoresist layer 31 through a controllable plasma treatment process, so that the original hydrophobic surface of the photoresist layer 31 becomes a hydrophilic surface with sufficient hydrophilicity, or the hydrophilicity of the original hydrophilic surface of the photoresist layer 31 is enhanced. The plasma used in the plasma treatment process includes at least one of N, O, and H; among them, the principle of this step is: the surface layer of the photoresist combines with atoms such as N, O, and H in the corresponding plasma (including chemical reactions such as bonding), forming a thin hydrophilic layer rich in at least one of hydrophilic atoms, thereby changing the original hydrophobic surface of the photoresist layer into a hydrophilic surface with a sufficiently high hydrophilicity, or enhancing the hydrophilicity of the original hydrophilic surface of the photoresist layer.

[0072] Optionally, the process pressure of the plasma treatment process in step S2 is relatively low, for example, 10 mTorr to 100 mTorr. The relatively low process pressure is convenient for improving the uniformity of the distribution of atoms such as N, O, and H on the surface of the photoresist layer 31 after the plasma treatment process, and further facilitates the formation of a water film with a uniform film thickness in step S3.

[0073] S3, provide water vapor to the hydrophilic surface of the photoresist layer 31, and at least part of the provided water vapor condenses on the hydrophilic surface of the photoresist layer 31 to form a water film 32. Among them, water vapor can be provided to the hydrophilic surface of the photoresist layer 31 through a carrier gas flow with a required humidity mixed with deionized water. Optionally, the carrier gas flow includes nitrogen and / or inert gas, the required humidity is at least 60%, and the thickness of the water film 32 is at least λ / 2n nanometers. λ / 2n is the half-wavelength of the EUV light beam in water, where λ is the wavelength of the EUV light source and n is the refractive index of water; preferably, the thickness of the water film 32 is λ / 2n nanometers or a multiple of the optimal transmission coefficient of the projection system 13;

[0074] S4, use the EUV light source 10 to expose the pattern on the EUV photomask 20 through the water film 32 onto the photoresist layer 31.

[0075] Subsequently, after the exposure is completed, the wafer 30 can be transferred to a developing system to perform developing and other remaining process steps on the exposed photoresist layer.

[0076] In summary, in the EUV lithography method of the present invention, before exposure, moisture is condensed on the surface of the photoresist layer that has undergone hydrophilic surface treatment to form a thin water film. Thus, by utilizing the property that the refractive index of water is greater than that of air, the effect of shortening the effective wavelength is achieved, and further, the pattern resolution and contrast of EUV lithography are enhanced, which is beneficial for producing finer structures than before. The method is simple and has low cost.

[0077] It should be understood that when the EUV lithography method of the present invention is applied to the manufacturing method of a corresponding semiconductor device, it can complete the EUV lithography process required for the EUV photoresist layer coated on the wafer, and the pattern on the corresponding EUV photomask can be exposed on the EUV photoresist layer on the wafer surface with the effects of both enhanced pattern resolution and contrast. After developing the exposed photoresist layer, a patterned photoresist layer can be formed on the wafer. Then, using this patterned EUV photoresist layer as a mask, after etching the corresponding film layer in the wafer, corresponding patterns (such as circuit patterns and border patterns, etc.) can be fabricated on the wafer.

[0078] Moreover, since the manufacturing method of the semiconductor device applies the EUV lithography method of the present invention, it is beneficial to manufacture finer structures in the wafer than before.

[0079] The above description is only a description of the preferred embodiments of the present invention and does not limit the scope of the present invention in any way. Any changes and modifications made by those of ordinary skill in the art of the present invention based on the above disclosure are within the scope of the technical solution of the present invention.

Claims

1. An EUV lithography device, comprising an EUV light source, an illumination system, a mask stage, a projection system, and a wafer stage arranged in sequence along an optical path, characterized in that, The EUV lithography equipment further includes a gas supply system disposed around the wafer stage. The gas supply system is used to provide water vapor to the hydrophilic surface of the photoresist layer on the wafer on the wafer stage before exposing the photoresist layer, and at least part of the provided water vapor condenses on the hydrophilic surface of the photoresist layer to form a water film.

2. The EUV lithography device according to claim 1, characterized in that, The gas supply system is opened during the movement of the wafer stage and provides water vapor to the hydrophilic surface of the photoresist layer on the wafer placed on the wafer stage through a carrier gas flow with a required humidity mixed with deionized water; and the gas supply system is closed during exposure.

3. The EUV lithography device according to claim 2, characterized in that, The carrier gas flow provided by the gas supply system includes nitrogen and / or inert gas.

4. The EUV lithography device according to claim 2, characterized in that, The required humidity is at least 60%.

5. The EUV lithography device according to claim 1, characterized in that, The thickness of the water film is at least λ / 2n nanometers, where λ is the wavelength of the EUV light source and n is the refractive index of water.

6. The EUV lithography device according to claim 5, characterized in that, The thickness of the water film is λ / 2n nanometers or a multiple of the optimal transmission coefficient of the projection system.

7. The EUV lithography device according to any one of claims 1-6, characterized in that, It further includes a hydrophilic surface treatment system disposed around the wafer stage. The hydrophilic surface treatment system is used to perform a hydrophilic surface treatment on the photoresist layer through a controllable plasma treatment process before the gas supply system provides water vapor, so that the original hydrophobic surface of the photoresist layer becomes a hydrophilic surface or enhances the hydrophilicity of the original hydrophilic surface of the photoresist layer.

8. The EUV lithography device according to claim 7, characterized in that, The plasma used in the plasma treatment process includes at least one of N, O, and H.

9. An EUV lithography method, characterized in that, It includes the following steps: Provide a wafer on which a photoresist layer is formed; Perform a hydrophilic surface treatment on the photoresist layer through a controllable plasma treatment process, so that the original hydrophobic surface of the photoresist layer becomes a hydrophilic surface or enhances the hydrophilicity of the original hydrophilic surface of the photoresist layer; Provide water vapor to the hydrophilic surface of the photoresist layer, and at least part of the provided water vapor condenses on the hydrophilic surface of the photoresist layer to form a water film; Use an EUV light source to expose the pattern on the EUV photomask through the water film onto the photoresist layer.

10. The EUV lithography method according to claim 9, characterized in that, The plasma used in the plasma treatment process includes at least one of N, O, and H.

11. The EUV lithography method according to claim 9, characterized in that, The process conditions of the plasma treatment process include: the process pressure is 10 mTorr to 100 mTorr.

12. The EUV lithography method according to claim 9, characterized in that, Provide water vapor to the hydrophilic surface of the photoresist layer through a carrier gas flow with a required humidity mixed with deionized water.

13. The EUV lithography method according to claim 12, characterized in that, The carrier gas flow includes nitrogen and / or inert gas.

14. The EUV lithography method according to claim 12, characterized in that, The required humidity is at least 60%.

15. The EUV lithography method according to claim 9, characterized in that, The thickness of the water film is at least λ / 2n nanometers, where λ is the wavelength of the EUV light source and n is the refractive index of water.

16. The EUV lithography method according to claim 15, characterized in that, The thickness of the water film is λ / 2n nanometers, or a multiple of the optimal transmission coefficient of the projection system in the EUV lithography equipment.

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