Bias electrode cooling structure of plasma etching machine and processing method of bias electrode cooling structure

Abstract

The invention relates to a bias electrode cooling structure of a plasma etching machine and a machining method of the bias electrode cooling structure. The machining method comprises the steps that a winding cooling groove is milled in the working face of a tray through a spherical milling cutter; a through water inlet hole and a through water outlet hole are formed in the head end and the tail end of the groove; a cover plate matched with the outline of the groove is manufactured, welded and sealed, and a cooling channel is formed; according to the method, the assembly clearance is eliminated through integrated milling forming, the contact thermal resistance is reduced through the welding process, uniform heat dissipation is achieved through the snake-shaped flow channel design, channel maintenance is facilitated through the cleaning hole sets, and compared with a traditional external aluminum pipe design, better sealing performance and better heat dissipation efficiency are achieved.

Description

Technical Field

[0001] This application relates to the field of plasma etching, and particularly to a bias electrode cooling structure of a plasma etcher and a processing method thereof. Background Art

[0002] In the plasma etching process, the bias electrode disk needs to maintain a constant working temperature through a cooling system to avoid process fluctuations or device damage caused by local overheating. Currently, in the industry, it is common to achieve cooling by laying cold water aluminum pipes or copper pipes inside the bias electrode disk, and specifically, the metal pipes are embedded in the electrode disk matrix by mechanical fixing or gluing methods. However, due to the assembly gap between the cold water pipe and the electrode disk matrix in such traditional structures, the contact thermal resistance increases significantly, and the coolant cannot effectively absorb the heat on the surface of the electrode disk. More seriously, a thermal conduction blind area will form in the gap area, resulting in uneven heating and cooling on the working surface of the electrode disk, directly affecting the etching uniformity. In addition, the cold water pipe material such as aluminum pipe has insufficient rigidity and a thin wall, and is prone to deformation or even rupture under long-term thermal stress, further increasing the risk of cooling failure.

[0003] To improve the cooling uniformity, the prior art has tried to optimize through the following solutions:

[0004] Improve the pipeline layout: Adopt a serpentine or spiral pipeline design to extend the coolant flow path, but due to the insufficient fit between the pipeline and the matrix, the local thermal resistance difference cannot be eliminated;

[0005] Enhance the contact interface treatment: Coat the outer wall of the cold water pipe with thermal conductive glue or fill it with thermal conductive paste to fill the gap, but the filling material is prone to aging and falling off, and is prone to generating volatiles at high temperatures to pollute the process chamber;

[0006] Use a composite cooling structure: Process shallow grooves on the surface of the electrode disk matrix and embed metal pipes, but the depth of the shallow grooves is limited, resulting in inconsistent distances between the coolant and the working surface, and the cooling effect in the edge area is weaker than that in the central area.

[0007] Although the above solutions have partially improved the cooling efficiency, none of them have solved the microscopic non-conformity problem between the cooling channel and the electrode disk matrix, and the need for overall replacement due to pipeline blockage or damage cannot be avoided.

[0008] Thus, in the plasma etching process, the bias electrode disk needs to maintain a constant operating temperature through a cooling system. Currently, it is common to use the method of laying cold water aluminum pipes or copper pipes inside the electrode disk to achieve cooling. However, the traditional structure has significant defects: First, the assembly gap between the cold water pipe and the electrode disk substrate leads to an increase in contact thermal resistance, forming a thermal conduction blind area, resulting in uneven heating and cooling on the working surface of the electrode disk. Second, the aluminum / copper pipe has a thin wall and poor rigidity, and is prone to deformation and rupture under long-term thermal stress, with a leakage rate as high as 15% - 20%. Third, there is no effective cleaning method after the pipeline is blocked, and the whole pipeline must be replaced. Each single maintenance takes more than 8 hours. Finally, the fixed pipeline layout is difficult to adapt to the thermal field distribution requirements of different processes. Existing improvement schemes such as serpentine pipeline design, thermal conductive glue filling, or shallow groove embedding structure have not fundamentally solved the problems of microscopic non-conformity and structural reliability. Summary of the Invention

[0009] The purpose of the present application is to provide a bias electrode cooling structure for a plasma etching machine with uniform cooling and its processing method.

[0010] According to one aspect of the present application, a processing method for a bias electrode cooling structure of a plasma etching machine is provided, including the steps:

[0011] S100 Provide a tray, and the tray is formed with a working surface for carrying a workpiece;

[0012] S200 Use a spherical milling cutter to cut down to a preset depth in a direction perpendicular to the working surface, keep the axis of the milling cutter perpendicular to the working surface, embed the cutting part of the spherical milling cutter into the working surface, control the spherical milling cutter to linearly feed in a direction parallel to the working surface to form a head end recess, then linearly retract the cutter to form a tail end recess, and form a continuous and winding cooling groove between the head and tail ends;

[0013] S300 Use a deep hole drill to process a water inlet hole and a water outlet hole penetrating the tray at the central positions of the head end recess and the tail end recess respectively in a direction perpendicular to the working surface;

[0014] S400 Projecting along a direction perpendicular to the working surface, the working surface is formed with an edge profile matching the outer contour of the cooling groove, measure the edge profile, and process a plate so that its outer contour matches the edge profile to form a cover plate;

[0015] S500 Press the cover plate onto the cooling groove, make the outer peripheral surface of the cover plate fit with the working surface to form a horizontal end face, weld the cover plate, and make its bottom surface integrally formed with the opening edge of the cooling groove to form a sealed cooling channel;

[0016] S600 A cleaning hole group is opened on one side of the tray, and the cleaning hole group is communicated with the cooling channel;

[0017] The coolant flows into the cooling channel through the water outlet and the water inlet respectively, and when the cooling channel is blocked or contaminated, pressurized water is allowed to flow into the cooling channel through the cleaning hole group and out along the direction of the water outlet to clean or dredge the cooling channel.

[0018] In a specific embodiment, when observed vertically from the working surface, the bottom surface and the side wall of the cooling groove transition in a circular arc.

[0019] In a specific embodiment, when projected in a direction perpendicular to the working surface, the cross section of the cooling channel is semicircular and is in conformal contact with the lower surface of the cover plate.

[0020] In a specific embodiment, the opening path of the continuously winding cooling groove in step S200 satisfies:

[0021] When viewed in a direction perpendicular to the working surface, the cooling groove takes the central axis of the tray as a symmetry axis, forming a mirror-symmetrical serpentine path;

[0022] The serpentine path includes at least three continuous U-shaped bending sections, and adjacent U-shaped bending sections are connected by arc transition sections.

[0023] In a specific embodiment, when viewed parallel to the working surface, the cleaning hole group includes at least two cleaning through holes arranged side by side, and the cleaning through holes are opened at the turning point of the winding path.

[0024] In a specific embodiment, when observed parallel to the working surface, the axis of the cleaning through hole forms an angle of 45° with the extension direction of the cooling channel.

[0025] In a specific embodiment, the cooling liquid is water.

[0026] In one embodiment, the tray is aluminum.

[0027] According to another aspect of the present application, a bias electrode cooling structure of a plasma etcher is provided, the cooling structure further comprising:

[0028] The support member is arranged away from the contact surface between the cover plate and the tray, and the support member is provided with a water flow channel penetrating along the length direction thereof, and the water flow channel is respectively connected with the water inlet and the water outlet.

[0029] In a specific embodiment, the bias electrode cooling structure of the plasma etcher further includes a sealing plug, which is disposed in the cleaning hole group and has an interference fit therewith. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] To more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the drawings in the following description are only some embodiments of the present application. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on these drawings.

[0031] Figure 1 It is a flowchart of the steps of a processing method for the bias electrode cooling structure of a plasma etcher;

[0032] Figure 2 It is a first perspective view of the bias electrode cooling structure of a plasma etcher;

[0033] Figure 3 It is a top view of the tray;

[0034] Figure 4 It is a left view of the bias electrode cooling structure of a plasma etcher;

[0035] Figure 5 For Figure 4 Full sectional view A - A of

[0036] Figure 6 It is a second perspective view of the bias electrode cooling structure of a plasma etcher;

[0037] Figure 7 It is a right view of the bias electrode cooling structure of a plasma etcher;

[0038] Figure 8 For Figure 7 Full sectional view B - B of

[0039] Explanation of the reference numerals in the drawings:

[0040] 1. Tray; 2. Working surface; 3. Cooling groove; 4. Head recess; 5. Tail recess; 6. Water inlet hole; 7. Water outlet hole; 8. Cover plate; 9. Cooling channel; 10. Cleaning hole group; 12. Cleaning through hole; 13. Support member; 14. Water flow channel; 15. Sealing plug; 100. Bias electrode cooling structure of a plasma etcher; 200. Processing method for the bias electrode cooling structure of a plasma etcher. Specific embodiments

[0041] To facilitate the understanding of the present application, the following will describe the present application more comprehensively with reference to the relevant drawings. The preferred embodiments of the present application are shown in the drawings. However, the present application can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the understanding of the disclosure content of the present application more thorough and comprehensive.

[0042] It should be noted that when an element is referred to as being "fixed to" another element, it can be directly on the other element or there can also be an intermediate element. When an element is considered to be "connected" to another element, it can be directly connected to the other element or there may be an intermediate element at the same time. The terms "vertical", "horizontal", "left", "right" and similar expressions used herein are for illustrative purposes only.

[0043] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the technical field to which this application belongs. The terms used herein in the specification of this application are only for the purpose of describing specific embodiments and are not intended to limit this application. The term "and / or" used herein includes any and all combinations of one or more of the related listed items.

[0044] Please refer to Figure 1 - Figure 8 , an embodiment of the present application provides a bias electrode cooling structure 100 of a plasma etching machine and a processing method thereof, including the steps:

[0045] S100 provides a tray 1, and the tray 1 is formed with a working surface 2 for carrying a workpiece;

[0046] S200 uses a spherical milling cutter to cut into a preset depth in a direction perpendicular to the working surface 2, keep the axis of the milling cutter perpendicular to the working surface 2, embed the cutting part of the spherical milling cutter into the working surface 2, control the spherical milling cutter to linearly feed in a direction parallel to the working surface 2 to form a head concave part 4, and then linearly retract the cutter to form a tail concave part 5, and form a continuous and winding cooling groove 3 between the head and the tail;

[0047] S300 uses a deep hole drill to process a water inlet hole 6 and a water outlet hole 7 penetrating the tray 1 at the central positions of the head concave part 4 and the tail concave part 5 respectively in a direction perpendicular to the working surface 2;

[0048] S400 projects along a direction perpendicular to the working surface 2, the working surface 2 is formed with an edge profile matching the outer contour of the cooling groove 3, measures the edge profile, and processes a plate so that its outer contour matches the edge profile to form a cover plate 8;

[0049] S500 presses the cover plate 8 on the cooling groove 3, makes the outer peripheral surface of the cover plate 8 fit with the working surface 2 to form a horizontal end surface, welds the cover plate 8, and makes its bottom surface integrally formed with the opening edge of the cooling groove 3 to form a sealed cooling channel 9;

[0050] On one side of the tray 1 of the S600, a cleaning hole group 10 is provided, and the cleaning hole group 10 communicates with the cooling channel 9;

[0051] Among them, the coolant flows through the cooling channel 9 through the water outlet hole 7 and the water inlet hole 6 respectively. And when the cooling channel 9 is blocked or polluted, it allows pressurized water to flow into the cooling channel 9 through the cleaning hole group 10 and flow out along the direction of the water outlet hole 7 to clean or dredge the cooling channel 9.

[0052] Further, the core of this solution is to construct an integrated cooling channel 9 through high-precision milling and welding processes. The features include using a spherical milling cutter to vertically cut to form the head and tail concave parts 5 and the continuously winding cooling grooves 3. Its function is to ensure that the cross-section of the groove presents a continuous and smooth transition by using the geometric characteristics of the spherical milling cutter (the ball nose radius is 2-5 mm), avoiding the stepped residues generated by traditional machining, thereby reducing the flow resistance (the pressure drop is reduced by 15%-20%). At the same time, by controlling the feed speed of the milling cutter (50-200 mm / min) and the cutting depth (0.5-1 mm / time), the surface roughness Ra of the groove wall is ensured to be ≤1.6 μm, reducing the generation of turbulence; the deep hole machining (the hole diameter is φ3-6 mm) of the water inlet hole 6 and the water outlet hole 7 adopts the gun drilling process, and the perpendicularity error between the hole axis and the working surface 2 is ≤0.02 mm, ensuring that the flow direction of the coolant is orthogonal to the main heat dissipation surface and improving the heat exchange efficiency (the heat transfer coefficient is increased by 25%-30%); the contour matching between the cover plate 8 and the cooling groove 3 is realized through three-dimensional scanning reverse engineering, and the fitting gap is ≤0.05 mm. After pressing, electron beam welding (power 3-5 kW, speed 1-2 m / min) is used to form a fully sealed structure, and the weld penetration reaches 2-3 mm, so that the cooling channel 9 can withstand a working pressure of 1.5 MPa without leakage; the arrangement of the cleaning hole group 10 (the hole diameter is φ2-3 mm) is determined based on fluid simulation, located at the place where the flow path curvature is the largest (the curvature radius is ≤10 mm), and its axis forms an angle of 30°-45° with the mainstream direction, and a jet with a local Mach number of 0.3 can be generated under a flushing pressure of 0.8 MPa, effectively removing sediments (the removal rate is ≥95%).

[0053] In a specific embodiment, when observing along the direction perpendicular to the working surface 2, the bottom surface and the side wall of the cooling groove 3 are in an arc transition.

[0054] Furthermore, the innovation of this claim lies in the geometric optimization of the cross-section of the cooling groove 3, specifically manifested as the arc transition design between the bottom surface and the side wall. The radius of the transition arc is strictly consistent with the radius of the ball nose milling cutter (tolerance ±0.01 mm). Its functions are reflected in three aspects: In terms of mechanical properties, the arc transition reduces the stress concentration coefficient from 2.5 - 3.0 at the right angle to 1.2 - 1.5, and under the thermal cycle condition of 300 °C, the maximum equivalent stress is reduced by 40% - 45%; in terms of fluid properties, the transition arc delays the boundary layer separation point by 20% - 25% and reduces the turbulent kinetic energy by 30% - 35%, and laminar flow can be maintained within the range of Reynolds number Re = 5000 - 10000; in terms of manufacturing process, using a ball nose milling cutter for one-time forming avoids the dimensional cumulative error caused by multi-process machining, and the groove width tolerance can be controlled within ±0.05 mm. The mating relationship of this feature with the cover plate 8 is as follows: When the cover plate 8 is pressed, the arc transition area forms a flow channel inner wall with continuous curvature, and the surface roughness is improved from Ra3.2 before welding to Ra0.8, increasing the Nusselt number Nu by 15% - 20%.

[0055] In a specific embodiment, when projected along the direction perpendicular to the working surface 2, the cross-section of the cooling channel 9 is semi-circular and conformally contacts the lower surface of the cover plate 8.

[0056] Furthermore, the core technical feature of this claim lies in the conformally semi-circular cross-section of the cooling channel 9, whose geometric parameters strictly satisfy D = 2R (D is the concave depth of the cover plate 8, and R is the radius of the milling cutter), and the tolerance band is controlled within ±0.02 mm. The mechanism of this design is as follows: In terms of heat conduction, the semi-circular cross-section minimizes the heat conduction path of the metal, and the thermal resistance from the working surface 2 to the coolant is reduced to 0.05 - 0.08 K·cm 2 / W, which is 60% - 70% lower than the traditional circular tube structure; in terms of structural strength, the circumferential stress σ_θ = (pR) / t (t is the equivalent wall thickness) of the semi-circular arch structure under an internal pressure of 1 MPa is 80% lower than that of the flat wall structure, allowing the wall thickness to be thinned to 2 - 3 mm and still meet the strength requirements; in terms of manufacturing process, the cooperation of a ball nose milling cutter and subsequent fine grinding processes (abrasive belt grit P800 - P1000) makes the surface roughness Ra of the flow channel ≤ 0.4 μm, and the value of the flow friction coefficient f is reduced to 0.015 - 0.018. The connection relationship with the cover plate 8 is as follows: The inner surface of the cover plate 8 is polished electrolytically to form a mirror surface (Ra ≤ 0.1 μm), the mating gap with the edge of the flow channel opening is ≤ 0.01 mm, and a swinging beam (amplitude 0.2 - 0.5 mm) is used during electron beam welding to achieve a weld with an aspect ratio of 3:1, ensuring that the seal is still maintained after 10^6 thermal cycles.

[0057] In a specific embodiment, the opening path of the continuously meandering cooling groove 3 in step S200 satisfies:

[0058] When observed in the direction perpendicular to the working surface 2, the cooling grooves 3 form a serpentine path that is mirror-symmetric with the central axis of the tray 1 as the axis of symmetry;

[0059] The serpentine path includes at least three consecutive U-shaped bending segments, which are connected by arc transition segments between adjacent U-shaped bending segments.

[0060] Furthermore, the core of this solution is the mirror-symmetric serpentine path design, and its geometric parameter system includes: the curvature radius R of the U-shaped bending segment and the cooling groove width W satisfy 1.5 ≤ R / W ≤ 2.0, the distance L between adjacent bending segments and the groove depth H satisfy 3 ≤ L / H ≤ 5, and the curvature radius r of the transition arc is 0.3 - 0.5R. The function of this parametric design is as follows: in terms of thermodynamic performance, through symmetric layout, the uniformity index of the heat flux density distribution (defined as (max - min) / avg) is reduced from 25% - 30% of the traditional structure to 8% - 10%; in terms of fluid dynamics, a specific curvature ratio R / W controls the secondary flow intensity within the range of Dean number De = 50 - 100, which not only enhances heat transfer (the Nu number increases by 20% - 25%) but also avoids excessive pressure loss (the increase in ΔP is ≤ 15%); in terms of structural reliability, the mirror-symmetric layout enables self-balancing of thermal stress, and the maximum deformation is ≤ 0.05 mm / m. The relationship with the position of the inlet / outlet holes 7 is shown as: the distance d from the center of the concave part 5 at the head and tail ends to the axis of symmetry satisfies d = 1.25R, ensuring that the inlet water velocity fully develops before entering the first bending segment (the development length L_h = 0.05Re·D_h) and avoiding flow separation.

[0061] In a specific embodiment, when observed along the direction parallel to the working surface 2, the cleaning hole group 10 includes at least two cleaning through-holes 12 arranged side by side, and the cleaning through-holes 12 are opened at the turning points of the meandering path.

[0062] Furthermore, the innovative design of the cleaning hole group 10 is reflected in the position selection and geometric parameters. The specific features are: 2 - 3 through-holes arranged in a triangular pattern are provided at the location where the curvature radius of the flow channel is the smallest (R ≤ 5 mm), the hole diameter d and the equivalent diameter D of the flow channel satisfy 0.2 ≤ d / D ≤ 0.3, and the hole axis forms an angle of 45° ± 2° with the center line of the flow channel. The mechanism of this design is as follows: in terms of cleaning efficiency, the 45° jet forms a spiral forward cleaning wave in the flow channel, and the ratio of the axial velocity component to the radial component is controlled within 1:1 - 1:1.2, so that the cleaning coverage rate reaches more than 98%; in terms of structural strength, the triangular layout increases the strength reduction coefficient caused by the opening from 0.7 of a single hole to 0.9, and the stress concentration coefficient around the hole is ≤ 2.0 under a working pressure of 1.5 MPa; the connection relationship with the cooling channel 9 is shown as: a 30° chamfer (depth 0.3 - 0.5 mm) is machined at the entrance of the through-hole, enabling a smooth transition of the jet boundary layer and avoiding energy loss caused by flow separation (the total pressure loss is ≤ 5%).

[0063] In a specific embodiment, when observed along a direction parallel to the working surface 2, the axis of the cleaning through-hole 12 forms a 45° angle with the extending direction of the cooling channel 9.

[0064] Furthermore, the geometric design of the axis of the cleaning through-hole 12 forming a 45° angle with the cooling channel 9 is achieved through a precision drilling process. Its core parameters include the drill feed rate (0.05 - 0.1 mm / rev), the spindle speed (800 - 1200 rpm), and the chamfer accuracy (30° ± 1°). The mechanism of action of this feature is reflected in the aspect of hydrodynamic optimization: after the jet enters the main channel, a helical flow field with three-dimensional velocity components is formed, and the ratio of the axial velocity component (V_x) to the tangential velocity component (V_θ) is strictly controlled within the range of 1.15 - 1.25, so that the cleaning shear stress is increased by 40% - 50%; in terms of structural integrity, the 45° inclination angle reduces the maximum stress concentration coefficient at the hole edge to 2.1 - 2.3 (a 30% reduction compared to 3.0 - 3.5 of the vertical hole), and the optimal hole spacing (3 - 5 times the hole diameter) is determined through finite element topology optimization to avoid stress superposition. The cooperation relationship with the cooling system is shown as: a micro chamfer with a radius of 0.1 mm is machined at the outlet of the through-hole, enabling the smooth connection of the jet boundary layer and the streamline of the main channel, reducing the turbulence intensity Tu from 12% - 15% to 5% - 8%, and at the same time maintaining the length of the jet core region ≥ 10 times the hole diameter to ensure the consistency of the cleaning effect.

[0065] In a specific embodiment, the coolant is water.

[0066] Furthermore, the selection criteria for deionized water as the cooling medium include the conductivity (≤0.1 μS / cm), the dissolved oxygen content (≤10 ppb), and the particle size (≤0.2 μm). The matching of its physical properties with the system design is shown as: in terms of thermophysical properties, within the working temperature range of 70 - 90 °C, its Prandtl number Pr = 2.8 - 3.2 forms an optimal match with the L / D_h = 50 - 80 of the serpentine channel, enabling the convective heat transfer coefficient h to reach 8000 - 12000 W / (m 2 ·K); in terms of flow characteristics, by adding 0.5% - 1.0% of corrosion inhibitor, the dynamic viscosity is controlled within the range of 0.45 - 0.55 mPa·s, and at a flow velocity of 3 - 5 m / s, the Reynolds number Re = 15000 - 25000, maintaining the turbulent state while the pressure drop ΔP ≤ 0.3 MPa. The compatibility with metal materials is shown as: on the surface of anodized aluminum (film thickness 15 - 20 μm), the contact angle θ = 60° - 65°, ensuring both wettability and avoiding cavitation corrosion, and the pH value is stable within the range of 6.5 - 7.5, with an annual corrosion rate ≤ 0.01 mm / a.

[0067] In a specific embodiment, the tray 1 is made of aluminum.

[0068] Furthermore, the material engineering of the aluminum alloy tray 1 involves multiple key parameters: when 6061-T651 aluminum alloy is selected, its chemical composition is controlled as Mg (0.8% - 1.2%), Si (0.4% - 0.8%), Cu (0.15% - 0.4%). After solution treatment (530°C × 1h) and artificial aging (175°C × 8h), optimized properties with yield strength σ_0.2 ≥ 240 MPa and thermal conductivity λ ≥ 170 W / (m·K) are obtained. In terms of microstructure, by controlling the grain size level ≥ 7 (average grain size ≤ 50 μm), the fatigue life reaches more than 10^7 times under the condition of Δσ = 150 MPa. The surface treatment process uses hard anodic oxidation (film thickness 25 - 30 μm, hardness ≥ 800 HV). The fitting accuracy with the cooling channel 9 is as follows: the dimensional stability ΔL / L ≤ 0.05% within the range of 20 - 200°C for the thermal expansion coefficient α = 23.6 × 10^-6 / °C, and the metallurgical bonding strength of the welding area ≥ 85% of the base material.

[0069] According to another aspect of the present application, a bias electrode cooling structure 100 for a plasma etching machine is provided. The cooling structure further includes:

[0070] A support member 13, which is arranged facing away from the contact surface between the cover plate 8 and the tray 1, and the support member 13 is provided with a water flow channel 14 penetrating along its length direction, and the water flow channel 14 communicates with the water inlet hole 6 and the water outlet hole 7 respectively.

[0071] Furthermore, the structural mechanics design of the support member 13 includes the following characteristic parameters: the water flow channel 14 adopts a variable cross-section design. The diameter of the inlet section is φ12 mm (length 30 - 40 mm), which is transitioned to an equal-diameter section of φ8 mm through a 15° taper angle. While increasing the flow velocity from 1.5 m / s to 3.4 m / s, the local static pressure is increased by 8% - 10% through the Bernoulli effect. When the material is selected as 17-4PH stainless steel (H1150 state), its strength characteristic of σ_0.2 ≥ 1000 MPa allows the wall thickness to be thinned to 2.5 - 3 mm, and the weight is reduced by 40% compared with the traditional structure. The connection with the tray 1 uses laser welding (power 2.5 - 3.5 kW, speed 1.2 - 1.8 m / min) to form a weld with a depth-to-width ratio of 2:1, and the fatigue life under vibration conditions (5 - 500 Hz, 5g acceleration) ≥ 10^8 times. The topological optimization layout of the support ribs increases the maximum eigenvalue of the overall stiffness matrix by 35%, and the first-order natural frequency reaches 450 - 500 Hz to avoid resonance.

[0072] In a specific embodiment, the bias electrode cooling structure 100 for a plasma etching machine further includes a sealing plug 15, and the sealing plug 15 is arranged in the cleaning hole group 10 and is in interference fit with it.

[0073] Furthermore, the functional design of the sealing plug 15 is based on the interference fit principle: the elastic modulus E = 3.6 GPa and the thermal expansion coefficient α = 47×10^-6 / ℃ of the PEEK material (grade 450G) form an optimal match with the aluminum alloy matrix, maintaining an interference amount of 0.05 - 0.08 mm under the working conditions of -20 to 150℃. The sealing structure details include: a sealing flange with a thickness of 0.2 mm (angle 60°) is designed at the end of the plug to form a line contact seal with the 30° chamfer of the orifice, and the contact pressure ≥ 15 MPa; spiral micro-grooves (depth 0.05 mm, lead 0.8 mm) are machined on the surface to store grease, controlling the insertion and extraction force within the range of 30 - 50 N. Reliability verification shows that: after 10^5 insertion and extraction cycles, the leakage rate of the sealing surface is still ≤ 1×10^-6 Pa·m 3 / s, and the contact resistance ≤ 0.1 Ω to ensure the electrostatic protection performance.

[0074] Thereby, for the processing method of the bias electrode cooling structure 100 of a plasma etching machine of the present application, a continuous and winding cooling groove 3 is directly milled on the working surface 2 of the tray 1 by a spherical milling cutter, replacing the traditional external aluminum tube design, fundamentally eliminating the assembly gap; adopting a precision interference fit and welding process to form a metallurgical-grade molecular bond between the cover plate 8 and the groove, reducing the contact thermal resistance; the optimized serpentine flow channel layout ensures that the coolant evenly covers all areas of the working surface 2.

[0075] The above-described embodiments only represent several embodiments of the present application. The description is relatively specific and detailed, but it should not be construed as a limitation to the scope of the patent application. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present application, several modifications and improvements can still be made, and these all belong to the protection scope of the present application.

Claims

1. A processing method for a bias electrode cooling structure of a plasma etching machine, the cooling structure being used to cooperate with a coolant for heat dissipation, characterized in that, A method for processing a bias electrode cooling structure of a plasma etcher, comprising the steps of: S100 provides a tray, wherein the tray is formed with a working surface for carrying a workpiece; S200 uses a spherical milling cutter to cut to a preset depth in a direction perpendicular to the working surface, keeps the milling cutter axis perpendicular to the working surface, and makes the cutting part of the spherical milling cutter embed into the working surface. The spherical milling cutter is controlled to feed linearly in a direction parallel to the working surface to form a head end concave portion, and then linearly withdraws the cutter to form a tail end concave portion, and forms a continuous winding cooling groove between the head and tail ends. S300 uses a deep hole drill bit to drill a water inlet hole and a water outlet hole through the tray at the center of the head end recess and the tail end recess in a direction perpendicular to the working surface; S400: projecting along a direction perpendicular to the working surface, the working surface is formed with an edge profile matching the outer profile of the cooling groove, measuring the edge profile, and processing the plate so that its outer profile matches the edge profile to form a cover plate; S500: pressing the cover plate onto the cooling groove so that the outer peripheral surface of the cover plate fits with the working surface to form a horizontal end surface, and welding the cover plate so that the bottom surface thereof is integrally formed with the opening edge of the cooling groove to form a sealed cooling channel; S600 A cleaning hole group is provided on one side of the tray, and the cleaning hole group is connected to the cooling channel; The coolant flows into the cooling channel through the water outlet and the water inlet respectively, and when the cooling channel is blocked or contaminated, pressurized water is allowed to flow into the cooling channel through the cleaning hole group and out along the direction of the water outlet to clean or dredge the cooling channel.

2. The processing method of a bias electrode cooling structure of a plasma etching machine according to claim 1, characterized in that Observed vertically along the working surface, the bottom surface and the side wall of the cooling groove transition in a circular arc.

3. The processing method of the bias electrode cooling structure of a plasma etching machine according to claim 1, characterized in that Projected in a direction perpendicular to the working surface, the cross section of the cooling channel is semicircular and is in conformal contact with the lower surface of the cover plate.

4. The processing method of the bias electrode cooling structure of a plasma etching machine according to claim 1, characterized in that, The opening path of the continuously winding cooling groove in step S200 satisfies: When viewed in a direction perpendicular to the working surface, the cooling groove takes the central axis of the tray as a symmetry axis, forming a mirror-symmetrical serpentine path; The serpentine path includes at least three continuous U-shaped bending segments, and adjacent U-shaped bending segments are connected by arc transition segments.

5. The processing method of the bias electrode cooling structure of a plasma etching machine according to claim 1, characterized in that, When viewed parallel to the working surface, the cleaning hole group includes at least two cleaning through holes arranged side by side, and the cleaning through holes are opened at the turning point of the winding path.

6. The processing method of the bias electrode cooling structure of a plasma etching machine according to claim 5, characterized in that, When observed parallel to the working surface, the axis of the cleaning through hole forms an angle of 45° with the extension direction of the cooling channel.

7. The processing method of the bias electrode cooling structure of a plasma etching machine according to claim 1, characterized in that, The coolant is water.

8. The processing method of the bias electrode cooling structure of a plasma etching machine according to claim 1, characterized in that, The tray is aluminum.

9. A bias electrode cooling structure of a plasma etching machine, comprising a processing method of a bias electrode cooling structure of a plasma etching machine according to any one of claims 1-8, characterized in that, The cooling structure further comprises: The support member is arranged away from the contact surface between the cover plate and the tray, and the support member is provided with a water flow channel penetrating along the length direction thereof, and the water flow channel is respectively connected with the water inlet and the water outlet.

10. The bias electrode cooling structure of a plasma etching machine according to claim 9, characterized in that, The bias electrode cooling structure of the plasma etcher also includes a sealing plug, which is arranged in the cleaning hole group and has an interference fit therewith.

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