Gas-distributed electrode etching method

Abstract

This disclosure provides a method for etching a gaseous distributed electrode, comprising: fixing a gaseous distributed electrode in a first orientation to a fixture, wherein the gaseous distributed electrode has two opposing feature surfaces and a plurality of micropores penetrating the two feature surfaces, and in the first orientation, the axis of the micropores extends along a first direction; placing the fixture with the gaseous distributed electrode fixed in a bath containing an etching solution, so that the gaseous distributed electrode is completely immersed in the etching solution; while the gaseous distributed electrode remains completely immersed, driving the gaseous distributed electrode to perform a reciprocating motion along a second direction by the fixture, wherein the second direction forms a first angle with the first direction, so that the etching solution alternately penetrates the micropores under the reciprocating motion of the gaseous distributed electrode, and forms eddies inside the micropores and at the orifice openings, thereby solving the problems of uneven etching and particle residue in deep holes in traditional gaseous distributed electrode micropore methods.

Description

Technical Field

[0001] This disclosure relates to the field of semiconductor processing technology, and more specifically to a method for etching gaseous distributed electrodes. Background Technology

[0002] In semiconductor manufacturing processes, the gaseous distribution electrode is a core component within the reaction chamber. Its surface is densely covered with penetrating micropores for uniformly injecting precursors or reactant gases into the chamber. Because micro-stress damage layers, remelted layers, and debris particles inevitably remain on the hole walls during mechanical drilling or laser drilling, a thorough cleaning and aperture correction process is necessary to prevent residual particles from detaching and contaminating the underlying wafer in subsequent processing.

[0003] Traditional techniques typically employ a horizontally placed, unidirectional co-current etching method, where the etching solution is injected from above the electrode and allowed to flow downwards through the micropores by gravity. However, due to the extremely high aspect ratio of the micropores, the etching solution easily forms a stable laminar flow within the pore, creating a very thick fluid boundary layer at the pore walls. This prevents effective renewal of the reaction solution deep within the micropores, making the removal of the inner wall damage layer and microparticles extremely difficult. Simultaneously, the pressure drop of the fluid along the depth of the pore leads to asymmetric etching, easily corroding the micropores into non-uniform conical or hourglass-shaped deformed holes, severely disrupting the uniformity of subsequent airflow distribution. Furthermore, attempts to forcibly break the stagnant boundary layer using high-frequency ultrasound can generate cavitation micro-explosions, which can easily cause irreversible lattice damage and microcracks to hard and brittle electrode substrates such as silicon or anodic alumina. Therefore, existing etching methods face insurmountable technical bottlenecks in achieving improvements in fluid displacement efficiency within the pores, ensuring the uniformity of micropore geometry, and avoiding physical damage to brittle materials.

[0004] It should be noted that the above description of the technical background is only for the purpose of providing a clear and complete explanation of the technical solutions of the present invention and facilitating understanding by those skilled in the art. It should not be assumed that the above technical solutions are known to those skilled in the art simply because they have been described in the background section of this invention. Summary of the Invention

[0005] In view of the above problems, this disclosure provides a gaseous distribution electrode etching method, which solves the problems of uneven etching and particle residue in deep holes in the traditional gaseous distribution electrode micro-hole method.

[0006] This disclosure provides an embodiment of a gaseous distribution electrode etching method, the method comprising: fixing a gaseous distribution electrode in a first orientation to a fixture, wherein the gaseous distribution electrode has two opposing feature surfaces and a plurality of micropores penetrating the two feature surfaces, wherein in the first orientation, the axis of the micropores extends along a first direction; placing the fixture on which the gaseous distribution electrode is fixed into a bath containing an etching solution, so that the gaseous distribution electrode is completely immersed in the etching solution; while the gaseous distribution electrode remains completely immersed, driving the gaseous distribution electrode to perform a reciprocating motion along a second direction by means of the fixture, wherein the second direction forms a first angle with the first direction, so that the etching solution alternately penetrates the micropores under the reciprocating motion of the gaseous distribution electrode, and forms eddies inside the micropores and at the orifice opening.

[0007] In some exemplary embodiments, the gaseous distribution electrode is a reciprocating motion along the second direction with a reciprocating frequency and a reciprocating amplitude as the amplitude frequency, wherein the reciprocating frequency and the reciprocating amplitude are configured such that the etching fluid forms an oscillating flow field within the micropore, the Strouhal number of the oscillating flow field being greater than or equal to the eddy current threshold.

[0008] In some exemplary embodiments, the reciprocating frequency is 1 Hz to 10 Hz, the reciprocating amplitude is 5 mm to 100 mm, and the reciprocating frequency, the reciprocating amplitude, and the aperture of the micropore are configured such that the Strouhal number of the oscillating flow field is greater than or equal to 0.05 and less than or equal to 0.2.

[0009] In some exemplary embodiments, placing the fixture with the gaseous distribution electrode fixed thereon into a bath containing etching solution in a first immersion manner specifically includes: controlling the fixture to descend along the direction of gravity at a preset descent rate to immerse the gaseous distribution electrode into the etching solution, wherein the preset descent rate is configured to cause the etching solution to displace the gas in the micropores under capillary action.

[0010] In some exemplary embodiments, the preset descent rate is less than or equal to 1 cm / min.

[0011] In some exemplary embodiments, the angle between the first direction and the vertical direction is any angle between 30° and 90°.

[0012] In some exemplary embodiments, the first included angle is a non-zero included angle.

[0013] In some exemplary embodiments, the first included angle is any angle between 30° and 90°.

[0014] In some exemplary embodiments, the gaseous distribution electrode is a silicon-based electrode, and the etching solution is a mixture of alkaline etching solution and anionic surfactant, wherein the concentration of the anionic surfactant is 0.01% to 0.5%.

[0015] In some exemplary embodiments, the gaseous distribution electrode is an anodic aluminum oxide-based electrode, and the etching solution is an acidic etching solution. Attached Figure Description

[0016] The foregoing contents, as well as other objects, features, and advantages of this disclosure, will become clearer from the following description of embodiments with reference to the accompanying drawings, in which:

[0017] Figure 1 This schematic diagram illustrates the structure of the conventional gas-distributed electrode etching method in the first process.

[0018] Figure 2 This schematic diagram illustrates the structure of the conventional gas-distributed electrode etching method in the second process.

[0019] Figure 3 A schematic diagram of the structure of the gaseous distributed electrode etching method according to an embodiment of the present disclosure during the etching process;

[0020] Figure 4 A flowchart of a gaseous distribution electrode etching method according to an embodiment of the present disclosure. Detailed Implementation

[0021] To enable those skilled in the art to better understand the technical solutions in this disclosure, the technical solutions in the embodiments of this disclosure will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this disclosure, and not all embodiments. Based on the embodiments in this disclosure, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of this disclosure.

[0022] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit this disclosure. The terms “comprising,” “including,” etc., as used herein indicate the presence of the stated features, steps, operations, and / or components, but do not exclude the presence or addition of one or more other features, steps, operations, or components.

[0023] All terms used herein (including technical and scientific terms) have the meanings commonly understood by those skilled in the art, unless otherwise defined. It should be noted that the terms used herein are to be interpreted in a manner consistent with the context of this specification, and not in an idealized or overly rigid way.

[0024] When using expressions such as "at least one of A, B, and C," the meaning should generally be interpreted according to the understanding of someone skilled in the art. For example, "a system having at least one of A, B, and C" should include, but is not limited to, systems having A alone, having B alone, having C alone, having A and B, having A and C, having B and C, and / or having A, B, and C. Similarly, when using expressions such as "at least one of A, B, or C," the meaning should generally be interpreted according to the understanding of someone skilled in the art. For example, "a system having at least one of A, B, or C" should include, but is not limited to, systems having A alone, having B alone, having C alone, having A and B, having A and C, having B and C, and / or having A, B, and C.

[0025] In the highly precise semiconductor manufacturing process that is constantly evolving towards nanometer nodes, the reaction chamber is the core hardware device for constructing the microstructure of integrated circuits. At the top of these reaction chambers, a gas distribution electrode is typically installed. The gas distribution electrode is a disc-shaped or plate-shaped precision mechanical component, usually made of high-purity silicon or anodized aluminum with a barrier layer on its surface. From an overall physical structure perspective, the gas distribution electrode mainly consists of a first surface facing the gas inlet, a second surface facing the plasma reaction region, and thousands of micropores densely penetrating these two surfaces. In semiconductor dry processing or thin film deposition, this electrode assembly acts like a showerhead, uniformly and stably injecting the precursor gas or reactant gas into the reaction chamber below through these numerous micropores, forming a highly uniform plasma field under the excitation of a radio frequency power supply. Therefore, the geometric consistency, inner wall roughness, and physicochemical purity of these micropores directly determine the uniformity of the gas flow distribution on the silicon wafer surface below, thus profoundly affecting the processing yield and final electrical performance of semiconductor devices.

[0026] In existing technologies, gaseous distribution electrodes must undergo rigorous etching processes during initial manufacturing or later maintenance and refurbishment. This is because the densely packed micropores on the gaseous distribution electrodes are typically fabricated using high-precision mechanical drilling or high-energy laser spiral drilling. Both mechanical stress and laser thermal ablation inevitably leave microscopic damage on the inner walls of the micropores. Laser drilling creates a remelted layer on the hole surface, accompanied by microcracks and a heat-affected zone, while mechanical drilling leaves a physical stress damage layer as well as imperceptible microparticles and debris. If these processing residues are not thoroughly removed, these damaged layers are highly susceptible to peeling off in the high vacuum and strong plasma environment of subsequent semiconductor manufacturing. The resulting particles can fall directly onto the underlying wafer, causing fatal transistor defects. Therefore, the gaseous distribution electrode must be etched. Its core function is to use the corrosiveness of the chemical liquid to completely remove the microscopic damage layer, remelting layer and attached debris from the inner wall of the micropore, so that the inner wall of the micropore is restored to an ideal state with extremely smooth surface and high lattice integrity, while ensuring that the pore size of all micropores is precisely widened to the designed standard tolerance range.

[0027] See also Figure 1 and Figure 2 As shown, to achieve the above objectives, traditional etching methods for gaseous distribution electrodes primarily rely on horizontally placed unidirectional co-current etching. In the specific process, the gaseous distribution electrode is typically placed horizontally on a support fixture at the bottom of the etching bath, with the first surface A facing upwards and the second surface B facing downwards. Then, a prepared chemical etching solution is continuously injected from above the electrode. Driven directly by gravity, the etching solution enters each micropore from the upward-facing first surface A, flows downwards along the micropore axis, chemically erodes the inner walls of the micropores, and finally flows out from the downward-facing second surface B into a waste liquid collection tank. Because the gravitational flow of the etching solution is unidirectional, this method usually requires a step-by-step approach: after completing the co-current etching of the first surface A, the entire gaseous distribution electrode must be lifted from the bath, mechanically rotated 180 degrees, repositioned horizontally, and then the etching solution is injected downwards from the second surface B for secondary processing. This is to compensate for the uneven corrosion of the upper and lower pore diameters caused by the unidirectional flow as much as possible. In addition, to accelerate the removal of contaminants from the holes, some existing processes also use megasonic waves or high-frequency vibration generators during the aforementioned co-current etching process, attempting to enhance the cleaning effect through high-frequency energy transfer.

[0028] However, the gaseous electrode etching method in the aforementioned traditional technology faces extremely difficult-to-overcome physical bottlenecks in practical applications, and various attempts to improve the traditional process have all fallen into irreconcilable technical contradictions. First, from a microfluidic perspective, due to the extremely high aspect ratio of the micropores in the gaseous electrode, when the etching solution flows downward through the micropores under gravity, the fluid forms an extremely stable parabolic laminar flow within the pores. In this laminar flow state, the fluid velocity near the inner wall of the micropore is almost zero, forming an extremely thick fluid concentration boundary layer. This means that the reaction solution deep within the micropores can hardly be effectively physically replaced, and the etching reaction completely degenerates into an extremely slow natural molecular diffusion process, making it extremely difficult to remove particles and damage layers deep within the pores. Second, if attempts are made to break this stagnant boundary layer by increasing the static water pressure of the etching solution above or by using an external pump to force pressurization, the fluid pressure drop decreases exponentially along the depth of the pore, inevitably resulting in a flow velocity and local pressure at the upper inlet of the micropore being much greater than at the bottom outlet. This unidirectional asymmetric pressure field leads to severe non-uniform etching, easily corroding the originally straight cylindrical micropores into funnel-shaped conical pores that are wider at the top and narrower at the bottom, completely destroying the uniformity of airflow distribution. Even using a double-sided etching method with flipped electrodes only transforms the unidirectional conical pores into hourglass-shaped malformed pores that are wider at both ends and narrower in the middle, failing to achieve axial uniformity of the micropores. Furthermore, in order to break the dead zones within the micropores, traditional techniques attempt to introduce high-frequency vibration or ultrasound for assistance. However, there is a fatal materials science contradiction here: gaseous distribution electrodes (such as silicon or anodic aluminum oxide) are typical hard and brittle materials. Although the cavitation bubble micro-explosion effect induced by high-frequency vibration in the liquid can dislodge impurities from the inner wall of the pore, the extreme transient impact force released will inevitably cause secondary physical damage to the extremely fragile edges of the micropores, and may even induce new lattice micro-pits and cracks. If high-frequency vibration is not used, the dead zones within the pores cannot be eliminated; once high-frequency vibration is used, new structural damage will occur. In summary, traditional etching systems are caught in a multi-dimensional contradiction between "flow field displacement efficiency," "aperture geometric uniformity," and "damage prevention for brittle materials." Any attempt to optimize a local area without altering the existing unidirectional flow or static immersion framework will immediately trigger deterioration in other dimensions, leading to a technical deadlock where any change in the structure and methodology of the existing etching process has far-reaching consequences, making substantial optimization extremely difficult.

[0029] like Figure 3 and Figure 4 As shown, this disclosure provides a gaseous distribution electrode etching method, including: operations S100 to S300.

[0030] Operation S100: Fix the gaseous distribution electrode to the fixture in a first orientation, wherein the gaseous distribution electrode has two opposing feature surfaces and a plurality of micropores penetrating the two feature surfaces, and in the first orientation, the axis of the micropores extends along a first direction.

[0031] Operation S200: The fixture with the gaseous distribution electrode fixed thereon is placed into a bath containing etching solution so that the gaseous distribution electrode is completely immersed in the etching solution.

[0032] Operation S300: With the gaseous distribution electrode fully submerged, the clamp drives the gaseous distribution electrode to perform reciprocating motion along the second direction, wherein the second direction forms a first angle with the first direction, so that the etching solution alternately penetrates the micropore under the reciprocating motion of the gaseous distribution electrode and forms eddies inside the micropore and at the opening.

[0033] Specifically, in operation S100, the actuator applies clamping force to the non-porous region of the gaseous distribution electrode through the mechanical clamping structure of the fixture, stabilizing and fixing it in a preset spatial shape. The overall structure of the gaseous distribution electrode is generally a solid part with a certain thickness, with its two ends defined as the two opposing feature surfaces. These two feature surfaces typically correspond to the surface on the gas inlet side and the reaction side surface facing the interior of the process chamber, respectively. Within the solid structure of the gaseous distribution electrode, there are thousands of micropores extending from one feature surface to the other, forming physical channels for the flow of process gas. Since stress damage layers, remelted layers, and particulate debris inevitably remain on the inner walls of the micropores during the initial forming process such as mechanical drilling or laser ablation, subsequent etching and cleaning are required. The first orientation refers to the overall orientation and spatial arrangement of the gaseous distribution electrode in three-dimensional space after the fixture clamps and fixes it. The first direction refers to the geometric extension vector direction in space along the central axis of the micropores penetrating the two feature surfaces, defined by the first orientation. By adjusting the clamping angle or assembly method of the fixture, the axis of the micro-hole can be directed to any set vector direction in space, thereby ensuring that the gaseous distribution electrode enters the subsequent etching process in the expected spatial orientation, laying the foundation for subsequent changes in the internal hydrodynamic state of the micro-hole.

[0034] Specifically, in operation S200, the transmission mechanism drives the fixture, which is fixed with the gaseous distribution electrode, to move spatially into the bath until the highest physical point of the gaseous distribution electrode is completely lowered below the liquid surface inside the bath, thus achieving complete immersion of the gaseous distribution electrode. The etching solution is a pre-prepared chemical reaction solvent stored in the bath. Its chemical composition is configured to undergo a controllable chemical corrosion reaction with the substrate of the gaseous distribution electrode, thereby dissolving and peeling off the processing damage layer on the inner wall of the micropores and disrupting the bonding force between the adhering particles and the inner wall. The bath is a container made of corrosion-resistant material with sufficient three-dimensional volume. This volume not only holds enough etching solution to completely submerge the gaseous distribution electrode but also provides ample fluid flow space and mechanical movement stroke for the gaseous distribution electrode to perform subsequent mechanical movements while fully immersed. By completely immersing the gaseous distribution electrode in the etching solution, the traditional fluid supply method of injecting liquid downward from a single surface is changed. This allows the two opposite feature surfaces of the gaseous distribution electrode to establish a direct solid-liquid contact interface with the etching solution, which has the same initial physicochemical state, providing the necessary fluid environment for subsequent bi-directional symmetrical etching.

[0035] Specifically, in operation S300, while ensuring that the gaseous distribution electrode does not detach from the etching solution surface, the drive system outputs periodic mechanical kinetic energy to the fixture, causing the fixture and the gaseous distribution electrode to reciprocate along the set second direction. Because the second direction and the first direction extending from the micro-orifice axis exist at the first angle, this spatial motion trajectory causes the feature surface of the gaseous distribution electrode to exert continuous compression and shearing action on the relatively stationary or semi-stationary etching solution during macroscopic movement. Specifically, the reciprocating motion of the gaseous distribution electrode generates localized high-pressure dynamic water at the feature surface in front of its movement and localized low-pressure dynamic water at the feature surface behind its movement. Due to the periodic reversal of the reciprocating motion direction, the pressure field at the two feature surfaces also undergoes periodic high-low pressure alternation. This alternating dynamic water pressure difference directly acts on the two ends of the micro-orifice, forcibly driving the etching solution to overcome the fluid resistance inside the micro-orifice, forming a periodically changing flow field within the micro-orifice. More importantly, when the etching solution flows at high speed through the micropore opening driven by alternating dynamic water pressure differences, the macroscopic fluid flow is physically and geometrically cut by the micropore edges. The fluid boundary layer undergoes intense morphological stripping and flow separation at the opening, thereby generating high-intensity micro-eddies in the internal extension section of the micropore and the external region of the opening. These eddies, as a form of energy dissipation in fluid mechanics, can completely disrupt the laminar flow state that is easily formed inside the micropore due to its high aspect ratio, forcibly stripping away the extremely thick fluid concentration boundary layer adhering to the inner wall of the micropore. The strong fluid disturbance and radial convection brought about by the eddies accelerate the mass transfer process of fresh etching solution into the depth of the micropore, and entrain chemical byproducts generated by the etching reaction and detached microparticles from the depth of the micropore to the outside, achieving active renewal of the fluid inside the micropore.

[0036] By operating from S100 to S300, the traditional static etching paradigm relying on unidirectional gravity flow was transformed. Firstly, by using a preset initial orientation and complete immersion, the uneven etching across the aperture caused by unidirectional gravity flow was eliminated, removing the tedious and time-consuming process of mid-process electrode flipping, thus improving process efficiency and ensuring the symmetry of the etching environment. Secondly, macroscopic mechanical reciprocating motion was introduced into the flow field control, using motion in a specific direction to generate alternating pressure differences at the aperture, thereby inducing micro-vortices. These micro-vortices broke through the laminar flow dead zone and mass transfer bottleneck deep within the micropores, allowing each micro-region of the high aspect ratio micropore inner wall to receive uniform and sufficient chemical fluid renewal, thereby achieving the peeling off of the damaged layer on the micropore inner wall and the complete removal of particles. Furthermore, this method utilizes the sweeping effect of pure water dynamics to achieve cleaning, effectively avoiding the lattice damage and microcrack risks that may be caused to hard and brittle electrode substrates by cavitation micro-explosions generated by traditional high-frequency ultrasound or megasonic waves in liquids. While ensuring the geometric uniformity of micropores, it improves the yield and final physical properties of gaseous distributed electrodes.

[0037] In some exemplary embodiments, the operation S300 of driving the gaseous distribution electrode to perform reciprocating motion along the second direction by means of the clamp specifically includes: driving the gaseous distribution electrode along the second direction by means of the clamp, performing reciprocating motion with a reciprocating frequency and a reciprocating amplitude as the amplitude frequency, wherein the reciprocating frequency and the reciprocating amplitude are configured such that the etching solution forms an oscillating flow field in the micropore, and the Strouhal number of the oscillating flow field is greater than or equal to the eddy current threshold.

[0038] In some specific embodiments, reciprocating motion using reciprocating frequency and amplitude as the amplitude frequency refers to the driving mechanism applying a periodic mechanical driving force to the fixture and its fixed gaseous distribution electrode. The reciprocating frequency defines the number of periodic reciprocations per unit time, while the reciprocating amplitude defines the maximum spatial geometric displacement of the gaseous distribution electrode from its equilibrium position. These two kinematic parameters jointly determine the macroscopic kinetic energy input characteristics of the gaseous distribution electrode as it moves in the etching fluid. The oscillating flow field refers to the dynamic fluid dynamics state in which the flow velocity and direction of the etching fluid inside the micropores change periodically with time due to the continuous pressure difference caused by alternating dynamic water pressure during the periodic change of the gaseous distribution electrode's direction of motion. Compared to traditional steady-state laminar flow, the fluid particles in the oscillating flow field are in a state of continuous alternating acceleration and deceleration. The Strouhal number is a core dimensionless parameter in fluid mechanics used to characterize non-steady oscillating flow mechanisms. Physically, it reflects the ratio of local transient inertial force to convective inertial force in the flow field, quantifying the intrinsic coupling relationship between fluid vortex shedding frequency, equipment mechanical motion frequency, and flow field characteristic velocity. Because a very thick fluid concentration boundary layer, hindering mass exchange, easily forms inside micropores with high aspect ratios, simple low-speed reciprocating flow can only cause the fluid as a whole to translate like a piston, failing to break this boundary layer. Setting the Strouhal number of the oscillating flow field to be greater than or equal to the eddy threshold allows for flow separation at the inlet and outlet of the micropore when the spatiotemporal parameters of macroscopic mechanical motion match the spatial scale of the micropore diameter to a value above this dimensionless threshold. This induces microscopic eddies at the ends and interior of the micropore. This eddy current has radial disturbance capability, which can forcibly peel off the concentration boundary layer of the hole wall, so that the depleted etching solution containing damaged layer debris and particles is quickly carried out of the hole and fresh etching solution is introduced, thus completely solving the technical bottleneck of limited mass transfer in deep holes from the physical underlying mechanism.

[0039] In some exemplary embodiments, the reciprocating frequency is from 1 Hz to 10 Hz, the reciprocating amplitude is from 5 mm to 100 mm, and the reciprocating frequency, the reciprocating amplitude, and the aperture of the microvia are configured such that the Strouhal number of the oscillating flow field is greater than or equal to 0.05 and less than or equal to 0.2. In some specific embodiments, the reciprocating frequency is strictly limited to 1 Hz to 10 Hz, and the reciprocating amplitude is limited to 5 mm to 100 mm. Simultaneously, the aperture of the microvia is adjusted so that the Strouhal number of the oscillating flow field is within a precise range of 0.05 to 0.2, resulting in better etching performance and substrate protection. Firstly, the combination of low frequencies (1Hz to 10Hz) and large amplitudes (5mm to 100mm) explicitly eliminates the high-frequency micro-amplitude oscillation mode used in traditional mega-sonic or ultrasonic cleaning techniques. This low-frequency, large-amplitude macroscopic mechanical sweeping motion provides sufficient macroscopic kinetic energy to the etching solution to form a "fluid piston effect" that penetrates the entire depth of the micropore, while completely avoiding the cavitation bubble micro-explosion phenomenon caused by high-frequency sound waves in the liquid. Since gaseous distributed electrodes (such as high-purity silicon or materials with an oxide layer on the surface) are mostly typical hard and brittle substrates, avoiding cavitation micro-explosions can directly prevent micro-pits, lattice damage, and crack propagation caused by high transient impact forces at the micropore edges. Secondly, configuring the Strouhal number in the range of 0.05 to 0.2 is the optimal hydrodynamic range for achieving efficient fluid displacement within the micropores. If the value is below 0.05, the intensity of the eddy currents generated by the dynamic water pressure difference is insufficient, and the eddy current shedding phenomenon is extremely weak, making it impossible to effectively penetrate deep into the micropores to peel off the boundary layer. If the value is above 0.2, it means that the direction of mechanical motion is switched too frequently, and the fluid is forced to reverse before a fully developed through-flow eddy current is formed inside the micropore, resulting in a fluid stagnation dead zone in the middle section of the micropore, and the etching solution cannot achieve complete physical replacement. Therefore, setting the Strouhal number in the range of 0.05 to 0.2 ensures that the micro-eddy currents can fully develop and sweep across the entire inner wall of the micropore, while maintaining a good reaction solution renewal rate. This achieves uniform etching on both sides without dead corners, while maximizing the protection of the structural integrity of the electrode substrate.

[0040] In some exemplary embodiments, the step of operating S200, which involves placing the fixture with the gaseous distribution electrode fixed thereon into a bath containing etching solution in a first immersion manner, specifically includes: controlling the fixture to descend along the direction of gravity at a preset descent rate to immerse the gaseous distribution electrode into the etching solution, wherein the preset descent rate is configured to cause the etching solution to displace the gas in the micropores under capillary action.

[0041] In some specific embodiments, because the gaseous distribution electrode has a high-density micropore array, and these micropores typically have a large aspect ratio, if the gaseous distribution electrode is rapidly pressed into or submerged in the etching solution, the air inside the micropores cannot be expelled in time due to the rapid blockage by the external liquid, thus forming highly compressed microscopic cavities inside the micropores. These cavities completely block the solid-liquid contact between the etching solution and the inner wall of the micropores, leading to severe yield problems such as no etching or extremely uneven etching in some areas. Configuring the preset descent rate to allow the etching solution to displace the gas inside the micropores under capillary action essentially involves using a mechanical transmission system to control the spatial displacement of the gaseous distribution electrode along the direction of gravity during liquid entry. When the descent rate is precisely controlled, at the instant the etching solution contacts the lower end of the micropore opening, the capillary climb force formed by the surface tension of the liquid on the inner wall of the micropore will dominate. At this time, the surface of the etching solution will form a stable meniscus inside the micropore and smoothly advance upwards through capillary action. Since the rate of increase in external hydraulic pressure caused by mechanical descent does not exceed the rate of internal capillary climbing and venting, the gas inside the micropores can be slowly and completely squeezed out from the upper orifice. By utilizing the microscopic physical properties of the fluid itself and intervening through macroscopic rates, the hidden danger of gas residue in the micropores is completely eliminated, ensuring that the inner walls of all micropores can be wetted by liquid after immersion, laying the foundation for providing an extremely uniform initial etching reaction interface.

[0042] In some exemplary embodiments, the preset descent rate is less than or equal to 1 cm / min. In some specific embodiments, precisely limiting the preset descent rate to less than or equal to 1 cm / min further ensures effective gas removal from micropores with extremely high aspect ratios. In the actual operating conditions of semiconductor-grade gaseous distribution electrodes, the pore size of the micropores is typically extremely small, resulting in significant flow resistance of the etching solution within this microscale space, and it is highly susceptible to dynamic contact angle hysteresis. If the descent rate exceeds the critical threshold of 1 cm / min, the rate of establishment of external hydrostatic pressure will be faster than the rate of liquid surface rise driven by surface tension inside the micropore, causing fluid interface instability and closure before the pore walls are fully wetted, thereby forcibly sealing the air bubbles in the middle of the micropore. Strictly controlling the descent rate to 1 cm / min or below provides sufficient time margin for the dynamic replacement of the gas and liquid phases inside the micropore. At this extremely low rate, even when facing complex micropores with varying internal pore wall roughness, local microscopic obstructions, or differences in surface energy in different regions, the capillary tip can maintain absolutely stable and continuous unidirectional ascent. The specific range setting completely blocks the hydrodynamic conditions for cavitation generation, ensuring from the source of the process that the tens of thousands of micropores of the entire gaseous distribution electrode can achieve degassing and wetting during the liquid entry process, thereby improving the yield of the final product.

[0043] In some exemplary embodiments, the angle between the first direction and the vertical direction is any angle between 30° and 90°.

[0044] In some specific embodiments, in conventional etching processes, the axis of the microvia is typically parallel to the vertical direction (i.e., the angle is 0°), causing the etching solution to flow unidirectionally downwards under gravity. The resulting axial hydrostatic pressure difference leads to severely uneven corrosion rates at the upper and lower ends of the microvia, easily forming non-uniform conical hole defects. When the angle between the first direction and the vertical direction is limited to the aforementioned range, the component of the gravity vector along the microvia axis is significantly weakened or even completely eliminated. This change in spatial orientation removes gravity's dominance over the fluid trajectory within the hole, allowing subsequently applied mechanical kinetic energy to act uniformly and symmetrically on both ends of the microvia, thereby ensuring the overall dimensional uniformity of the etching. For example, when the gaseous distribution electrode is held at a 90-degree angle (i.e., the first orientation is a completely perpendicular orientation where the characteristic surface of the gaseous distribution electrode is parallel to the vertical direction), the direction of gravity is completely perpendicular to the axis of the microvia. At this point, the distribution and movement of the etching solution inside the micropore are no longer subject to the unidirectional pull of gravitational potential drop, and the force state at both ends of the hole achieves perfect physical symmetry. In this vertical orientation, combined with the aforementioned reciprocating motion, a cylindrical channel with a consistent diameter from inlet to outlet can be fabricated within the micropore in a single operation, completely eliminating the cumbersome process of lifting and flipping the electrode midway in the traditional horizontal placement method to compensate for unidirectional etching defects.

[0045] In some exemplary embodiments, the first included angle is a non-zero included angle.

[0046] In some specific embodiments, the first included angle is defined as a non-zero included angle, introducing a completely different three-dimensional hydrodynamic disturbance mechanism. If the included angle is zero degrees, the gaseous distribution electrode simply performs a simple piston-like insertion and withdrawal motion along the axis of the micropore. Although this forward motion can drive the fluid in and out, the fluid inside the micropore still tends to maintain a stable laminar flow state and cannot effectively disrupt the fluid boundary layer tightly attached to the pore wall. When the first included angle is a non-zero included angle, the macroscopic motion trajectory of the gaseous distribution electrode intersects with the extension direction of the micropore. In this intersecting motion state, the physical structure of the gaseous distribution electrode exerts physical compression and lateral shearing on the front side of its motion, while forming a fluid wake suction zone on the back side. This lateral shearing force across the feature surface not only creates a large alternating pressure gradient at the two ends of the micropore, but more importantly, when the fluid with a lateral velocity component is forced to sweep across the edge of the micropore, it will trigger a severe fluid boundary layer separation phenomenon at the pore opening. For example, by setting a non-zero angle between the first and second directions, the gaseous distribution electrode performs a transverse sweeping motion in the etching solution. When the transversely flowing etching solution passes through the micro-geometric abrupt change in the micro-pore, the streamlines are forcibly bent and separated, thereby inducing high-intensity rotating vortices at the inlet and outlet of the micro-pore. This vortex system can penetrate deep into the micro-pore and forcibly peel off the concentration boundary layer and attached damage debris on the pore wall in a helical propulsion manner, with a fluid displacement efficiency exceeding that of axial piston motion.

[0047] In some exemplary embodiments, the gaseous distribution electrode is a silicon-based electrode, and the etching solution is a mixture of an alkaline etching solution and an anionic surfactant, wherein the concentration of the anionic surfactant is 0.01% to 0.5%.

[0048] In some specific embodiments, taking into account the material characteristics of silicon-based electrodes, a combination system of alkaline etching solution and anionic surfactant of a specific concentration is used to stimulate a synergistic mechanism of electrostatic repulsion and chemical cleaning at the microscopic level in a macroscopic alternating flow field. When silicon-based materials undergo chemical etching in an alkaline environment, silicate byproducts and detached microscopic silicon particles are inevitably generated. In the high retention environment of deep holes, these microscopic particles are easily affected by van der Waals forces or local electrostatic attraction, and re-attach to the newly cleaned inner wall of the micropore, causing fatal secondary contamination. By introducing 0.01% to 0.5% anionic surfactant into the alkaline system, the anionic groups of the surfactant can be rapidly and directionally adsorbed on the surface of the silicon substrate on the inner wall of the micropore and on the surface of the free byproduct particles. This bidirectional adsorption effect causes the pore wall and particles to simultaneously acquire extremely strong surface potentials of the same polarity (negative potential). For example, when etching with an alkaline solution containing 0.1% anionic surfactant, the reciprocating motion of the electrode generates strong intrapore eddies. The mechanical shearing force of the eddy current first peels away the silicon particles from the inner wall of the micropores. Subsequently, the anionic surfactant rapidly encapsulates these free particles and the substrate of the pore wall. Based on the electrostatic law of like charges repelling each other, the peeled particles are pushed away from the inner wall of the micropores by a strong surface repulsive force. At the same time, the alternating and penetrating dynamic flow field prevents these suspended and repelled particles from settling inside the pores. Instead, they are immediately entrained by the eddy current and completely discharged from the pores, thus completely eliminating the risk of secondary particle adhesion within the deep pores from both chemical and fluid dynamic perspectives.

[0049] In some exemplary embodiments, the gaseous distribution electrode is an anodic aluminum oxide-based electrode, and the etching solution is an acidic etching solution.

[0050] In some specific embodiments, for anodic aluminum oxide-based electrodes, the etching solution is limited to an acidic etching solution to ensure the physicochemical integrity of the substrate surface microstructure while achieving deep cleaning. The surface of the anodic aluminum oxide electrode is covered with an extremely dense and structurally fragile anodic oxide barrier layer, which is the core defensive structure preventing the electrode from being broken down or excessively consumed in the subsequent high-energy plasma environment. If conventional alkaline etching solutions are used, the strongly alkaline environment will trigger a violent chemical deliquescence reaction, destroying or even completely dissolving this oxide barrier layer, leading to the direct scrapping of the electrode. Limiting the use to an acidic etching solution allows for the targeted dissolution of deadly contaminants such as metal impurities and environmental chlorides remaining in the micropores due to machining, without causing destructive chemical degradation of the aluminum substrate's oxide barrier layer. For example, for anodic aluminum oxide-based gaseous distribution electrodes with a dense oxide film on the surface, a weakly acidic etching solution such as dilute nitric acid is used for cleaning. Under the forced convection effect of mechanical reciprocating motion and microscopic eddies within the micropores, the acidic etching solution is repeatedly forced into and out of the depths of the micropores. This rapid mass transfer process driven by fluid dynamics ensures that acidic molecules can fully displace impurities deep within the micropores, while the waste liquid after the reaction is immediately swept out of the pores. This dynamic process avoids acid enrichment and over-corrosion caused by prolonged retention of the etching solution in localized areas, thus achieving high-purity cleaning of the micropore inner walls while preserving the integrity of the natural barrier layer of the anodic alumina.

[0051] The embodiments of this disclosure have been described above. However, these embodiments are for illustrative purposes only and are not intended to limit the scope of this disclosure. Although various embodiments have been described above, this does not mean that the measures in the various embodiments cannot be used advantageously in combination. Various substitutions and modifications can be made by those skilled in the art without departing from the scope of this disclosure, and all such substitutions and modifications should fall within the scope of this disclosure.

Claims

1. A method for etching a gaseous distributed electrode, characterized in that, The method includes: A gaseous distribution electrode is fixed to a fixture in a first orientation, wherein the gaseous distribution electrode has two opposing feature surfaces and a plurality of micropores penetrating the two feature surfaces, and in the first orientation, the axis of the micropores extends along a first direction. The fixture with the gaseous distribution electrode fixed thereon is placed into a bath containing etching solution so that the gaseous distribution electrode is completely submerged in the etching solution. With the gaseous distribution electrode fully submerged, the clamp drives the gaseous distribution electrode to perform reciprocating motion along the second direction, wherein the second direction forms a first angle with the first direction, so that the etching solution alternately penetrates the micropores under the reciprocating motion of the gaseous distribution electrode, and forms eddies inside the micropores and at the opening.

2. The method according to claim 1, characterized in that, The clamp drives the gaseous distribution electrode to reciprocate along the second direction, specifically including: The clamp drives the gaseous distribution electrode along the second direction to perform reciprocating motion with a reciprocating frequency and a reciprocating amplitude as the amplitude frequency, wherein the reciprocating frequency and the reciprocating amplitude are configured such that the etching solution forms an oscillating flow field in the micropore, and the Strouhal number of the oscillating flow field is greater than or equal to the eddy threshold.

3. The method according to claim 2, characterized in that, The reciprocating frequency is from 1 Hz to 10 Hz, the reciprocating amplitude is from 5 mm to 100 mm, and the reciprocating frequency, the reciprocating amplitude, and the aperture of the micropore are configured such that the Strouhal number of the oscillating flow field is greater than or equal to 0.05 and less than or equal to 0.

2.

4. The method according to claim 1, characterized in that, The step of placing the fixture on which the gaseous distribution electrode is fixed into a bath containing etching solution in a first immersion manner specifically includes: The fixture is controlled to descend along the direction of gravity at a preset descent rate to immerse the gaseous distribution electrode into the etching solution, wherein the preset descent rate is configured to cause the etching solution to displace the gas in the micropores under capillary action.

5. The method according to claim 4, characterized in that, The preset descent rate is less than or equal to 1 cm / min.

6. The method according to claim 1, characterized in that, The angle between the first direction and the vertical direction is any angle between 30° and 90°.

7. The method according to claim 6, characterized in that, The first included angle is a non-zero included angle.

8. The method according to claim 7, characterized in that, The first included angle is any angle between 30° and 90°.

9. The method according to claim 1, characterized in that, The gaseous distribution electrode is a silicon-based electrode, and the etching solution is a mixture of alkaline etching solution and anionic surfactant, wherein the concentration of the anionic surfactant is 0.01% to 0.5%.

10. The method according to claim 1, characterized in that, The gaseous distribution electrode is an anodic aluminum oxide-based electrode, and the etching solution is an acidic etching solution.

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