Hilmewton-level two-phase flow-induced vibration suppression method based on hydrophilic spine

Abstract

The invention discloses a method for suppressing milli-Newton-level two-phase flow-induced vibration based on a hydrophilic spine in the technical field of chip manufacturing, the method is applied to an immersion flow field of an immersion lithography machine, and the method comprises the following steps: arranging a spine structure along the axial direction of a gas-liquid two-phase flow negative pressure recovery microchannel, the length is matched with that of the micro-channel; the surface of the spine is treated into a hydrophilic surface, so that the spine has the characteristics of high surface energy and low contact angle; the liquid phase and the gas phase simultaneously flow into the negative pressure recovery micro-channel, and gas-liquid two-phase opposite impingement is formed in the micro-channel and is mixed to move upwards. By means of hydrophilic wetting and interface anchoring effects of the hydrophilic spine, random rupture and aggregation of a liquid phase under a gas phase shearing effect are limited, so that a stable thin liquid film or liquid bridge structure is formed on the surface of the spine, and pressure fluctuation and momentum oscillation caused by instability of a gas-liquid interface are avoided; and further, the problem of flow-induced vibration caused by instability of a two-phase flow interface in the negative pressure recovery micro-channel is inhibited.

Description

Technical Field

[0001] This invention relates to the field of chip manufacturing technology, specifically a method for suppressing millinewton-level two-phase flow-induced vibrations based on a hydrophilic spine. Background Technology

[0002] With the exposure wavelength unchanged, immersion improvement can be achieved simply by filling the space between the lithography machine's projection lens and the semiconductor silicon wafer with liquid instead of the original air. This significantly improves exposure resolution and depth of focus, making it one of the key technologies for the domestic manufacturing of high-end process chips. However, the dynamic sealing of the immersion flow field requires the use of an air knife to achieve gas-liquid two-phase recovery. Instability at the gas-liquid "opposition" interface will cause a very prominent two-phase flow-induced vibration problem, which will affect the motion accuracy of the dual-stage, the flatness of the silicon wafer, and the pose control of the immersion unit. This will lead to defects such as image defocusing, overlapping and interlacing of exposure lines, and reduced yield. Therefore, research on effective suppression of two-phase flow-induced vibration inside the immersion unit is of great practical significance.

[0003] Existing methods for suppressing flow-induced vibration can be divided into two categories based on the controlled object: one is the direct structural vibration suppression method, which acts directly on the vibrating system itself, reducing the vibration amplitude of the solid structure by enhancing structural damping or adjusting the system's natural frequency to avoid the resonance range; the other is the flow suppression method, whose core idea is to reduce the vibration effect by intervening in the flow state and separation process of the fluid, thereby changing the coupling between the fluid and the solid structure. However, both of these methods suffer from instability at the two-phase flow interface within microscale pipes in practical applications. Summary of the Invention

[0004] The purpose of this invention is to provide a method for suppressing millinewton-level two-phase flow-induced vibration based on hydrophilic spines. By axially setting hydrophilic spines on the inner wall of the gas phase side of a two-phase flow pipeline, the hydrophilic spines exert an adsorption force on the liquid through hydrophilic wetting and interfacial anchoring, forming a physical anchoring point at the gas-liquid interface. This limits the range of interfacial fluctuations, enhances the stability of the gas-liquid interface, and suppresses interfacial fluctuations, thereby suppressing millinewton-level two-phase flow vibrations in micron-scale pipelines. This solves the aforementioned problem of instability at the microscale two-phase flow interface in pipes and improves system reliability.

[0005] To achieve the above objectives, the present invention provides the following technical solution: A method for suppressing millinewton-level two-phase flow-induced vibrations based on a hydrophilic spine is applied to the immersion flow field of an immersion lithography machine. The method includes: The immersion unit between the objective lens and the silicon wafer is equipped with microchannels for liquid injection, gas injection, and negative pressure recovery. The liquid and gas phases are mixed and offset, forming a gas-liquid interface within the negative pressure recovery microchannel; A hydrophilic spine is provided along the axial direction of the inner wall of the negative pressure recovery microchannel, wherein the hydrophilic spine is made of the same material as the negative pressure recovery microchannel; The surface of the hydrophilic spine is treated to be a hydrophilic surface; Based on the liquid phase flowing in from the liquid inlet of the immersion unit and the gas phase flowing in from the gas inlet of the immersion unit, the inlet is kept at positive pressure and the outlet of the two-phase flow recovery microchannel is kept at negative pressure. The liquid phase and the gas phase form gas-liquid opposition in the two-phase flow recovery microchannel in the immersion unit to obtain a mixed upward two-phase fluid. The two-phase fluids form a gas-liquid interface within the recovery microchannel, and the hydrophilic spine anchors the gas-liquid interface.

[0006] As a further aspect of the present invention, the method further includes setting the height of the hydrophilic spine to one-third to two-thirds of the diameter of the negative pressure recovery microchannel.

[0007] As a further aspect of the present invention, the method further includes setting the height of the hydrophilic spine to extend to the interface between the two phases when the two-phase fluid flow is stable, and the length of the hydrophilic spine is equal to the inner wall of the two-phase flow pipeline.

[0008] As a further aspect of the present invention: the hydrophilic spine is a rectangular, trapezoidal, or triangular hydrophilic spine.

[0009] As a further aspect of the present invention, the method further includes: The inner diameter of the two-phase flow pipeline is set to the micrometer level, and the width of the hydrophilic spine along the gas-liquid two-phase flow direction is set to the micrometer level.

[0010] As a further aspect of the present invention: the surface treatment of the hydrophilic spine to a hydrophilic surface includes: The surface of the hydrophilic spine is subjected to hot-dip galvanizing treatment to obtain a hot-dip galvanized surface; The hot-dip galvanized surface is then subjected to electroplating treatment to obtain an electroplated surface; The electroplated surface is subjected to physical vapor deposition treatment to obtain a physical vapor deposition surface; A hydrophilic surface is obtained by chemical vapor deposition treatment of a physical vapor deposition surface.

[0011] As a further aspect of the present invention: the injection of gas and liquid into the gas-liquid injection port, respectively, and the gas and liquid phases forming gas-liquid counterflow within the negative pressure recovery microchannel in the immersion unit, comprising: It promotes spontaneous wetting and surface tension of the liquid phase on hydrophilic surfaces, forming a physical adsorption force on the interface between the two phases; The solid structure of the hydrophilic spine is determined as the swing anchor point of the two-phase interface. The lateral swing range of the two-phase interface is restricted to obtain the position of the two-phase interface.

[0012] As a further aspect of the present invention: the two-phase interface is a gas-liquid interface.

[0013] As a further aspect of the present invention, the selection criteria for the hydrophilic spine material include a contact angle range of 30° to 60°.

[0014] Compared with the prior art, the beneficial effects of the present invention are: 1. This invention provides a hydrophilic spine on the inner wall of a two-phase flow recovery microchannel, which is the same length as the gas-liquid interface and extends to the point where the flow is stable. This spine enhances the stability of the gas-liquid interface through the anchoring and wetting effect of the two-phase interface, reduces interface fluctuations, and effectively suppresses millinewton-level flow-induced vibrations. The invention is simple in structure, convenient in process, and economical. It can also suppress two-phase flow vibrations in micron-level microchannels.

[0015] 2. This invention provides a hydrophilic spine along the axial direction on the inner wall of the gas phase side of the two-phase flow pipeline. No additional external components or complex structural modifications are required. The hydrophilic spine can be integrally formed with the pipeline through micro-machining technology, avoiding post-assembly errors. The size and shape of the hydrophilic spine are adapted to the microchannel space, avoiding increased flow resistance, and have a significant effect on reducing the vibration amplitude of microscale two-phase flow.

[0016] 3. This invention, through an integrated design based on a hydrophilic spine, eliminates the need for complex external devices. The hydrophilic spine can be formed synchronously with the pipe body through micro-machining technologies such as photolithography and etching, reducing manufacturing costs and improving durability. Furthermore, it causes minimal disturbance to the original flow field of the pipeline and can be directly adapted to existing micro-scale flow channel designs without the need for large-scale equipment modifications. It has the advantages of simple structure, easy processing, and superior economy.

[0017] 4. The hydrophilic spine in this invention acts directly on the gas-liquid interface, suppressing interface fluctuations through a combination of physical anchoring and surface adsorption. This provides more precise control than traditional methods. By stabilizing the gas-liquid interface, it effectively avoids pressure pulsations caused by interface instability, reduces vibration interference to the precision components of the dual workpiece stage and immersion unit, effectively improves the yield of chip lithography, and significantly enhances the stability of high-end chip manufacturing. Attached Figure Description

[0018] Figure 1 (a) is a schematic diagram of the immersion unit of the present invention; Figure 1 (b) is a cross-sectional schematic diagram of the hydrophilic spine of the present invention; Figure 2 This is a schematic diagram of the top distribution of gas and liquid phases in a microscale pipeline without a hydrophilic spine. Figure 3 This is a schematic diagram of the top of the rectangular hydrophilic spine inside the micro-scale pipeline of the present invention; Figure 4This is a schematic diagram of the top of the trapezoidal hydrophilic spine inside the microscale pipeline of the present invention; Figure 5 This is a schematic diagram of the top of the triangular hydrophilic spine inside the microscale pipeline of the present invention; Figure 6 This is a diagram illustrating the method steps of the present invention. Detailed Implementation

[0019] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0020] Please see Figures 1-6 This invention provides a method for suppressing millinewton-level two-phase flow-induced vibrations based on a hydrophilic spine, applied to the immersion flow field of an immersion lithography machine. The method includes the following steps: S1: Liquid injection, gas injection, and negative pressure recovery microchannels are provided in the immersion unit between the objective lens and the silicon wafer; S2: Liquid and gas phases are mixed and offset to form a gas-liquid interface in the negative pressure recovery microchannel; S3: A hydrophilic spine is provided along the axial direction of the inner wall of the negative pressure recovery microchannel, wherein the hydrophilic spine is made of the same material as the negative pressure recovery microchannel. S4: Treat the surface of the hydrophilic spine to be a hydrophilic surface; S5: Based on the liquid phase flowing in from the liquid injection port in the immersion unit and the gas phase flowing in from the gas injection port in the immersion unit, the injection port is kept at positive pressure and the outlet of the two-phase flow recovery microchannel is at negative pressure. The liquid phase and the gas phase form gas-liquid opposition in the two-phase flow recovery microchannel in the immersion unit to obtain a mixed upward two-phase fluid. S6: The two-phase fluid forms a gas-liquid interface in the recovery microchannel, and the hydrophilic spine anchors the gas-liquid interface.

[0021] Preferably, the liquid phase is an immersed liquid, the two-phase interface is a gas-liquid interface, both the liquid phase flow pipe and the gas phase flow pipe are horizontal pipes, and the two-phase flow pipe, the liquid phase flow pipe and the gas phase flow pipe form an inverted T-shaped structure. The horizontal pipe is a straight channel formed by the collinearity of the liquid phase flow pipe and the gas phase flow pipe. The liquid phase fluid and the gas phase fluid enter the two-phase flow pipe from the liquid phase pipe and the gas phase pipe respectively, and merge in the pipe to form a gas-liquid two-phase flow. The two-phase flow pipe extends upward perpendicular to the midpoint of the straight channel. The size of the hydrophilic spine can be dynamically adjusted according to the flow rate and pipe diameter requirements. The thickness of the hydrophilic spine is 30μm, and the height of the hydrophilic spine extends to the gas-liquid interface when the two-phase flow is stable. Thus, the hydrophilic spine applies an anchoring effect to the gas-liquid interface, making the interface position stable and ensuring structural strength and flow channel occupancy.

[0022] Preferably, the method further includes: The height of the hydrophilic spine is set to extend to the interface between the two phases when the two-phase fluid flow is stable. The length of the hydrophilic spine is equal to the inner wall of the two-phase flow pipeline. The inner diameter of the two-phase flow pipeline is set to be in the micrometer range. The width of the hydrophilic spine along the gas-liquid two-phase flow direction is set to be in the micrometer range.

[0023] Preferably, by setting the height of the hydrophilic spine to extend to the interface between the two phases when the two-phase fluid flow is stable, the direct anchoring effect on the interface can be ensured. By setting the hydrophilic spine to be the same length as the inner wall of the two-phase flow pipeline, the hydrophilic spine can be used for two-phase interface regulation.

[0024] Preferred methods for fabricating hydrophilic surfaces include: hot-dip galvanizing, electroplating, physical vapor deposition, and chemical vapor deposition.

[0025] Preferably, based on a horizontal pipeline, a two-phase flow pipeline, and a hydrophilic spine, the liquid phase and the gas phase are respectively fed into the two-phase flow pipeline through the horizontal pipeline. This includes: promoting spontaneous wetting and surface tension of the liquid phase on the hydrophilic surface to form a physical adsorption force on the two-phase interface; determining the solid structure of the hydrophilic spine as the swing anchor point of the two-phase interface, limiting the lateral swing range of the two-phase interface, and obtaining the position of the two-phase interface.

[0026] Preferably, determining the solid structure of the hydrophilic spine as the swing anchor point of the two-phase interface, limiting the lateral swing range of the two-phase interface, and obtaining the position of the two-phase interface also includes: using the hydrophilic spine to reduce the irregular vibration of the two-phase interface caused by flow velocity fluctuations and pressure pulsations, fundamentally weakening the energy transfer of pressure fluctuations to the pipeline structure, suppressing pressure fluctuations and flow-induced vibrations caused by the two-phase interface, and controlling the contact angle of the hydrophilic spine material at 30°, which can enhance the interface anchoring effect on the liquid through hydrophilic adsorption.

[0027] like Figure 1As shown in (a), to achieve stable exposure, the immersion unit needs to achieve a stable and uniform flow field with uniform velocity and pressure distribution to maintain dynamic stability and dynamic sealing of the immersion flow field, while rapidly eliminating liquid from the flow field after exposure. The area within the red box is the hydrophilic spine action area of ​​this invention, and a partial enlarged cross-sectional view of the action area is shown below. Figure 1 As shown in (b), its core consists of a liquid flow pipeline, a gas flow pipeline, a two-phase flow pipeline and a hydrophilic spine. As a whole, it serves as a physical model for the study of microscale gas-liquid two-phase flow-induced vibration suppression, and can accurately simulate the gas-liquid recovery flow field characteristics in the immersion unit of an immersion lithography machine.

[0028] Specifically, in terms of spatial layout, the liquid flow pipeline and the gas flow pipeline are arranged collinearly along the horizontal direction. The liquid phase enters from the horizontal pipeline on the left, and the gas phase enters from the horizontal pipeline on the right. The two-phase flow pipeline extends vertically upwards perpendicular to this horizontal line, forming a vertical channel. Together, these three constitute a typical inverted T-shaped flow channel structure. The liquid and gas phases merge in the vertical pipeline to form an upward two-phase flow. The two-phase flow pipeline serves as the core area for gas-liquid mixing and flow, forming a mixed fluid in which the gas and liquid phases coexist, i.e., a two-phase fluid.

[0029] To drive stable fluid flow and achieve effective gas-liquid mixing, the inlet ends of the liquid phase flow pipeline and the gas phase flow pipeline are maintained at a stable positive pressure by a pressure stabilizing device, while the outlet end of the two-phase flow pipeline is maintained at a moderate negative pressure by a negative pressure pump. Under the combined action of the thrust of the positive inlet pressure and the pull of the negative outlet pressure, the liquid phase fluid flows uniformly from the left liquid phase flow pipeline to the junction of the two horizontal pipelines, while the gas phase fluid flows synchronously from the right gas phase flow pipeline to the junction point. After entering the two-phase flow pipeline, the two undergo gas-liquid collision and merging, ultimately forming a stable rising gas-liquid two-phase fluid in the vertical channel.

[0030] The hydrophilic spine is integrally connected to the inner wall of the pipeline, fitting tightly along the gas-phase side inner wall of the two-phase flow pipeline. The hydrophilic spine is not a separate component, but rather made of the same material as the pipeline body, formed synchronously with the pipeline using micromachining technology. Its length is completely consistent with the inner wall of the two-phase flow pipeline, enabling full interface control from the gas-liquid inlet junction to the pipeline outlet, ensuring that the gas-liquid interface at any point within the pipeline can be acted upon by the hydrophilic spine.

[0031] like Figure 3 The diagram shows the top of the gas and liquid phase distribution in a microscale pipeline without a hydrophilic spine, illustrating the state of the gas and liquid phase distribution at the top of the microscale pipeline without the use of a hydrophilic spine structure.

[0032] like Figures 3-5 The diagram shown is a top view of a hydrophilic spine structure used in a microscale pipeline. Based on the shape of the hydrophilic spine, the present invention is divided into three embodiments: a rectangular hydrophilic spine, a trapezoidal hydrophilic spine, and a triangular hydrophilic spine.

[0033] Example 1: like Figure 3 The diagram shows a top view of the rectangular spine. In this embodiment, the hydrophilic spine is tightly fitted along the inner wall of the gas phase side of the two-phase flow pipeline. The cross-section is a standard rectangle, and the thickness is uniformly set to 30μm. Under the hydrophilic effect of the spine, the rectangular ridge plane contacts the gas-liquid interface. Its size ensures the mechanical strength of the structure itself to withstand the impact of the fluid inside the pipe, while also reducing the flow channel occupancy rate and avoiding additional resistance to the gas-liquid two-phase flow.

[0034] Example 2: like Figure 4 The diagram shows a top view of the trapezoidal spine. In this embodiment, the hydrophilic spine has an isosceles trapezoidal cross-section, with a lower base length of 40 μm adhering to the gas phase wall inside the pipeline and an upper base length of 20 μm facing the gas-liquid interface. The trapezoidal spine structure is suitable for applications with higher gas-liquid velocities, and the thickened lower base further strengthens the structural strength of the spine and enhances the connection stability with the pipeline inner wall.

[0035] Example 3: like Figure 5 The diagram shows a view from the top of the triangular spine. In this embodiment, the hydrophilic spine has an isosceles triangle cross-section, with a lower base length of 40 μm that fits against the gas phase wall inside the pipeline, and the apex is embedded into the liquid phase for a certain distance. The isosceles triangular spine structure further optimizes the flow channel occupancy rate and minimizes flow resistance.

[0036] In terms of achieving hydrophilic properties, the contact angle of the spinal surface is strictly controlled within the range of 30~60°. This contact angle range is the key to balancing hydrophilic adsorption force and interface stability: a contact angle less than 30° can easily lead to excessive liquid spreading and interface adhesion, while a contact angle greater than 60° will result in insufficient hydrophilic adsorption force and inability to effectively anchor the interface.

[0037] From the perspective of its mechanism of action, the hydrophilic spine exhibits a "dual regulation" characteristic in stabilizing the gas-liquid interface: on the one hand, the hydrophilicity of the spine surface causes the liquid inside the tube to spontaneously wet under the action of surface tension, forming a continuous physical adsorption force that stabilizes and pulls the gas-liquid interface; on the other hand, the solid rectangular structure of the spine acts as a "rigid anchor point" for the interface, directly and physically limiting the lateral swing range of the gas-liquid interface and preventing the interface from shifting randomly due to flow velocity fluctuations and pressure pulsations. Under the synergistic effect of these two factors, the position of the gas-liquid interface is precisely locked, significantly reducing the amplitude of interface fluctuations and fundamentally suppressing millinewton-level two-phase flow-induced vibrations in the micron-level pipeline, ultimately meeting the stability requirements of the precision flow field within the immersion unit of the immersion lithography machine.

[0038] From an effectiveness perspective, in the original pipeline without a hydrophilic spine, the gas-liquid interface is prone to instability during the recovery process due to flow velocity fluctuations and pressure pulsations, leading to local pressure fluctuations within the pipe and thus vibration. Reducing the gas-liquid flow rate to alleviate interface instability would decrease gas-liquid recovery efficiency, failing to meet requirements. However, with the introduction of a hydrophilic spine, the gas-liquid interface achieves a relatively stable state due to the spine's hydrophilic adsorption effect: the hydrophilic spine maintains consistent stability of the gas-liquid interface axially throughout the two-phase flow pipeline, and its radial anchoring effect effectively reduces interface fluctuations. Furthermore, the spine itself absorbs some energy, thus suppressing vibration. Compared to the original pipeline, stability can be achieved without reducing the gas-liquid flow rate, ensuring gas-liquid recovery efficiency.

[0039] The above are merely preferred embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A method for suppressing millinewton-level two-phase flow-induced vibrations based on a hydrophilic spine, applied to the immersion flow field of an immersion lithography machine, characterized in that, The method includes: The immersion unit between the objective lens and the silicon wafer is equipped with microchannels for liquid injection, gas injection, and negative pressure recovery. The liquid and gas phases are mixed and offset, forming a gas-liquid interface within the negative pressure recovery microchannel; A hydrophilic spine is provided along the axial direction of the inner wall of the negative pressure recovery microchannel, wherein the hydrophilic spine is made of the same material as the negative pressure recovery microchannel; The surface of the hydrophilic spine is treated to be a hydrophilic surface; Based on the liquid phase flowing in from the liquid inlet of the immersion unit and the gas phase flowing in from the gas inlet of the immersion unit, the inlet is kept at positive pressure and the outlet of the two-phase flow recovery microchannel is kept at negative pressure. The liquid phase and the gas phase form gas-liquid opposition in the two-phase flow recovery microchannel in the immersion unit to obtain a mixed upward two-phase fluid. The two-phase fluids form a gas-liquid interface within the recovery microchannel, and the hydrophilic spine anchors the gas-liquid interface.

2. The method for suppressing millinewton-level two-phase flow-induced vibrations based on a hydrophilic spine according to claim 1, characterized in that, The method further includes: The height of the hydrophilic spine should be set to one-third to two-thirds of the diameter of the negative pressure recovery microchannel.

3. The method for suppressing millinewton-level two-phase flow-induced vibrations based on a hydrophilic spine according to claim 2, characterized in that, The method further includes: The height of the hydrophilic spine extends to the interface between the two phases when the two-phase flow is stable, and the length of the hydrophilic spine is equal to the inner wall of the two-phase flow pipeline.

4. The method for suppressing millinewton-level two-phase flow-induced vibrations based on a hydrophilic spine according to claim 3, characterized in that, The hydrophilic spine is rectangular, trapezoidal, or triangular.

5. The method for suppressing millinewton-level two-phase flow-induced vibrations based on a hydrophilic spine according to claim 4, characterized in that, The method further includes: The inner diameter of the two-phase flow pipeline is set to be in the micrometer range.

6. The method for suppressing millinewton-level two-phase flow-induced vibrations based on a hydrophilic spine according to claim 5, characterized in that, The method further includes: The width of the hydrophilic spine along the gas-liquid two-phase flow direction is set to be on the order of micrometers.

7. The method for suppressing millinewton-level two-phase flow-induced vibrations based on a hydrophilic spine according to claim 6, characterized in that, The process of treating the surface of a hydrophilic spine to be hydrophilic includes: The surface of the hydrophilic spine is subjected to hot-dip galvanizing treatment to obtain a hot-dip galvanized surface; The hot-dip galvanized surface is then subjected to electroplating treatment to obtain an electroplated surface; The electroplated surface is subjected to physical vapor deposition treatment to obtain a physical vapor deposition surface; A hydrophilic surface is obtained by chemical vapor deposition treatment of a physical vapor deposition surface.

8. The method for suppressing millinewton-level two-phase flow-induced vibrations based on a hydrophilic spine according to claim 7, characterized in that, The process involves injecting gas and liquid into the gas-liquid injection port, respectively, and the two phases of gas and liquid counteracting each other within the negative pressure recovery microchannel in the immersion unit, including: It promotes spontaneous wetting and surface tension of the liquid phase on hydrophilic surfaces, forming a physical adsorption force on the interface between the two phases; The solid structure of the hydrophilic spine is determined as the swing anchor point of the two-phase interface. The lateral swing range of the two-phase interface is restricted to obtain the position of the two-phase interface.

9. The method for suppressing millinewton-level two-phase flow-induced vibrations based on a hydrophilic spine according to claim 8, characterized in that, The two-phase interface is a gas-liquid interface.

10. The method for suppressing millinewton-level two-phase flow-induced vibrations based on a hydrophilic spine according to claim 9, characterized in that, The selection criteria for hydrophilic spine materials include a contact angle range of 30° to 60°.

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