Acid etching liquid composition, etching method and application

Abstract

The invention provides an acidic etching liquid composition, which is prepared from the following components in percentage by weight: 60 to 80 percent of nitric acid, 10 to 20 percent of hydrofluoric acid and 10 to 20 percent of acetic acid on the basis of the total mass. The invention further provides an etching method for removing the drilling damage of the gas injection hole, application of the acid etching liquid composition and an electrode for a plasma etching system.

Description

Technical Field

[0001] This application relates to etching solutions and the field of etching, and particularly to an acidic etching solution composition, etching method, and application. Background Technology

[0002] In semiconductor manufacturing, the plasma etching (ETCH) system is the core equipment for wafer pattern transfer and material removal. The key component mounted on top of the ETCH system, responsible for the uniform jetting of process gases, is called the electrode. The electrode typically has numerous micro-gas injection holes running through its thickness direction, used to distribute the process gases into the reaction chamber to create a uniform plasma distribution. To ensure plasma density stability and etching uniformity, the gas injection holes need to have consistent aperture, morphology, and aspect ratio, and the interior of the holes must be free of mechanical damage or particulate contamination caused by drilling.

[0003] However, since electrode materials typically include high-hardness materials such as quartz, ceramics, or composite oxides, these micropores need to be shaped through high-speed drilling or laser processing. During this process, damage layers, microcracks, and crushed particles inevitably occur on the hole walls. If these damages are not effectively removed, they will lead to particle detachment, abnormal plasma distribution, and even process contamination in subsequent etching processes. Therefore, the industry usually needs to use chemical etching equipment to dissolve and remove drilling damage and carry away residual particles by allowing the etching solution to flow along the direction of the micropores and fully contact the inner walls of the holes.

[0004] Therefore, an etching solution composition suitable for treating the interior of electrode holes is needed. This composition should not only effectively remove the damaged layer but also have a sufficiently fast etching rate to shorten processing time, improve production efficiency, and enhance the repair effect on the sidewalls of gas jet holes. Especially in deep holes and high aspect ratio structures, conventional etching solutions exhibit problems such as insufficient reaction at the bottom of the hole, uneven etching, and bubble retention. Therefore, it is necessary to optimize the composition and ratio of the etching solution to achieve rapid, uniform, and efficient repair of the entire hole wall.

[0005] Currently, some solutions disclose mixed acid systems with nitric acid, hydrofluoric acid, and organic acids as the main components, such as combinations of nitric acid, hydrofluoric acid, and organic acids, achieving simultaneous etching of thin film stacks by adjusting their proportions. However, these solutions primarily target planar thin film structures, emphasizing film selectivity and surface micro-roughness control. Their etching targets are nanoscale thin layers, not millimeter-scale deep holes. Furthermore, the disclosed proportions of nitric acid and hydrofluoric acid are far below the range required for deep hole damage repair, failing to meet the requirements for rapid deep etching inside high aspect ratio micro-gas jet holes. In addition, none of these solutions address the drilling damage removal mechanism inside the electrode micro-gas jet holes, which is inconsistent with key requirements such as optimizing deep fluid exchange, reducing bubble retention, and improving deep hole etching efficiency.

[0006] Other solutions also use nitric acid and hydrofluoric acid as etching systems, but they are mainly aimed at immersion etching processes on glass substrates. Their composition systems contain phosphoric acid, hydrochloric acid and anionic surfactants, which do not meet the requirements of deep hole etching processes. Furthermore, their etching targets are planar substrates, and they do not solve engineering problems such as the removal of damage to the inner wall of high aspect ratio channels, uneven etching at the bottom of the holes, and rapid peeling off of damaged layers.

[0007] Therefore, existing technologies cannot meet the special requirements of ETCH electrode micropore repair in terms of etching solution system composition, component ratio, process method and etching object, especially in terms of high etching rate, deep hole uniformity and sidewall smoothness.

[0008] It should be noted that the information disclosed in this section is only used for understanding the background of the inventive concept of this application. Therefore, the above information may include information that does not constitute prior art. Summary of the Invention

[0009] In view of this, this application provides an acidic etching solution composition, etching method and application, which aims to significantly improve the morphology and dimensional uniformity of the inner wall of the gas jet hole while achieving high-speed etching, thereby reducing the risk of particulate contamination, extending electrode life and improving the overall line yield.

[0010] The first aspect of this application provides an acidic etching solution composition comprising, by weight: 60-80 wt% nitric acid, 10-20 wt% hydrofluoric acid, and 10-20 wt% acetic acid.

[0011] According to embodiments of this application, the acidic etching solution composition further includes water and / or additional components, wherein the additional components are one or more of wetting agents, corrosion inhibitors, and surfactants.

[0012] According to an embodiment of this application, the acidic etching solution composition comprises, by total mass: 65-75 wt% nitric acid, 12-18 wt% hydrofluoric acid, 12-18 wt% acetic acid, and the balance being water.

[0013] According to embodiments of this application, the acidic etching solution composition further includes 0.01–5 wt% of a wetting agent and / or 0.01–5 wt% of a surfactant.

[0014] The second aspect of this application provides an etching method for removing drilling damage from gas jet holes, the etching method comprising: mounting an electrode having a plurality of gas jet holes in an etching apparatus such that the axial direction of the gas jet holes is substantially along the direction of gravity; introducing an acidic etching solution composition according to the first aspect into the etching apparatus such that the acidic etching solution composition flows downward through the inner wall of the gas jet holes; and maintaining the downward flow of the acidic etching solution composition while etching the electrode for 3.8 to 4.2 minutes.

[0015] According to embodiments of this application, the average etching rate of the acidic etching solution composition on the electrode is 12.6 to 12.9 μm / min.

[0016] According to an embodiment of this application, the step of causing the acidic etching solution composition to flow downward through the inner wall of the gas injection hole includes: adjusting the etching solution flow rate and supply pressure to cause the acidic etching solution composition to form a continuous downward flow on the inner wall of the gas injection hole.

[0017] A third aspect of this application provides an application of an acidic etching composition, said acidic etching composition being the acidic etching composition according to the first aspect, said acidic etching composition being used to remove drilling damage and residual particles from the inner wall of a gas jet hole in an electrode used in a plasma etching system.

[0018] According to an embodiment of this application, the gas injection hole is a micropore extending through the thickness direction of the electrode; under the conditions of etching temperature of 20-40°C and etching time of 3.8-4.2 minutes, by allowing the acidic etching solution composition to flow through the inner wall of the gas injection hole in a downward flow manner, the etching removal amount of the inner wall of the gas injection hole is 50-52 μm.

[0019] The fourth aspect of this application provides an electrode for a plasma etching system, wherein a plurality of gas injection holes are formed inside the electrode, which penetrate the electrode thickness direction, and the electrode is obtained by etching according to the etching method described in the second aspect.

[0020] The principle of this application is as follows:

[0021] (1) In this application, nitric acid is used as a strong oxidizing component to oxidize and activate the metal impurities, organic contaminants, and broken layers on the electrode substrate surface and in the drilled damage layer, making it easier for the glass phase, ceramic phase, and residual metal on the inner wall surface to be dissolved and removed by subsequent chemical reactions. Limiting the nitric acid content to the range of 60-80 wt% can ensure sufficient oxidation driving force and reaction rate on the one hand; on the other hand, it avoids that too low a nitric acid content will lead to a significant decrease in the etching rate, or that too high a nitric acid content will cause excessive and violent reactions in the system, making it difficult to control the morphology and increasing safety risks.

[0022] (2) Hydrofluoric acid is mainly used to dissolve the silica-based network structure in electrode materials and the amorphous / crack-rich regions formed in the drilling damage layer. Hydrofluoric acid and nitric acid work synergistically to preferentially dissolve and passivate the crushed layer, microcrack tips, and residual glass fragments in the gaps formed during drilling. The reason for limiting the hydrofluoric acid content to 10-20 wt% is as follows: when the hydrofluoric acid content is below 10 wt%, the dissolution rate of the deep hole inner wall damage layer is significantly reduced, making it difficult to remove the approximately 50 μm damage layer within 3.8-4.2 minutes; when the hydrofluoric acid content is above 20 wt%, adverse conditions such as local over-etching, orifice expansion, and increased sidewall roughness are likely to occur.

[0023] (3) Acetic acid, as an organic acid component, can, on the one hand, mitigate the violent reaction of the nitric acid / hydrofluoric acid system under high acidity by adjusting the local pH environment and coordination ability of the solution, thus keeping the etching rate controllable near the high value; on the other hand, acetic acid is beneficial to improving the wettability and wetting depth of the etching solution on the inner wall of the gas jet hole, reducing the adhesion of bubbles and the discontinuity of the liquid film on the inner wall of the deep hole, thereby improving the etching uniformity in high aspect ratio holes. The reason for limiting the acetic acid content to 10-20 wt% is as follows: when the acetic acid content is below 10 wt%, the system's buffering and wetting abilities are insufficient, which easily leads to insufficient etching or local residues in the lower part of the deep hole; an excessively high proportion of acetic acid will reduce the relative content of the effective oxidation / complexing active components in the system, thereby reducing the etching rate.

[0024] (4) By combining nitric acid, hydrofluoric acid, and acetic acid within the above concentration range, the etching solution maintains good reaction controllability under high acidity and high activity conditions. Experiments show that when treating electrodes with high aspect ratio gas jet holes under the above ratio conditions, an average etching rate of 12.6–12.9 μm / min can be achieved with an etching time of 3.8–4.2 minutes and an average etching removal of approximately 50 μm on the inner wall, while maintaining good hole morphology and size uniformity.

[0025] (5) In this application, by installing an electrode with multiple gas injection holes in an etching device, the axial direction of the gas injection holes is arranged basically along the direction of gravity, and an acidic etching solution composition is introduced in a downward flow manner, so that the etching solution forms a continuous downward flow inside the gas injection holes. Compared with the traditional immersion or non-directional flow method, the downward flow is beneficial to use gravity and pressure difference to continuously replenish fresh etching solution to the bottom of the deep hole, while timely carrying out the bubbles and dissolution products generated by the reaction out of the channel, thereby improving the problem of "over-etching in the hole opening area and insufficient etching in the hole bottom area", and achieving a more consistent etching removal amount along the axial direction in the hole with a high aspect ratio.

[0026] (6) By selectively adding 0.01 to 5 wt% of wetting agent and / or 0.01 to 5 wt% of surfactant to the acidic etching solution composition, the surface tension of the inner wall of the gas jet hole can be further reduced, the probability of bubble adhesion and liquid retention in the deep hole can be reduced, and the ability of the etching solution to spread and renew in the micro-channel can be enhanced. Thus, while maintaining a high etching rate, the etching uniformity between and within the hole can be further improved, and the risk of local residual damage layer or particles after etching can be reduced.

[0027] It should be noted that the wetting agent / surfactant is preferably a type that is resistant to strong acids and strong oxidation systems, and its addition amount is limited to not causing significant foaming or affecting continuous downward flow.

[0028] According to embodiments of this application, by constructing an acidic etching solution composition of 60-80 wt% nitric acid, 10-20 wt% hydrofluoric acid, and 10-20 wt% acetic acid, the morphology and dimensional uniformity of the gas jet hole inner wall are significantly improved while achieving high-speed etching. Compared with existing etching solution systems, after treatment with the acidic etching solution composition of this application, the crushed layer, scratch texture, and attached particles formed by drilling on the inner wall of the gas jet hole are more fully removed, resulting in a straighter and more continuous sidewall contour and a finer surface texture. When the target dimensions (e.g., aperture) of multiple gas jet holes in the same batch are statistically analyzed, the standard deviation is significantly lower than that of traditional etching processes, the inter-hole size fluctuation is reduced, and the overall consistency of the hole array is significantly improved, which is beneficial for ensuring the uniform distribution of plasma on the electrode surface and the repeatability of the etching process.

[0029] Furthermore, by mounting the electrodes in a gas jet orifice axially aligned substantially with the direction of gravity and introducing the acidic etching solution composition in a downward flow manner, a stable downward flow is formed within the high aspect ratio micro-channels. This improves the renewal of the etching solution and the removal of reaction products within the deep holes, effectively alleviating the etching unevenness problems caused by insufficient etching at the bottom of deep holes, over-etching in the orifice area, and localized bubble retention in traditional immersion processes. Therefore, this application not only helps reduce the risk of particle contamination caused by residual drilling damage layers and particles within the gas jet orifice, but also helps extend the service life of the electrodes, reduce the frequency of maintenance and replacement, and comprehensively improve the stability and overall yield of the plasma etching system, demonstrating significant industrial application value. Attached Figure Description

[0030] The above and other objects, features and advantages of this application will become clearer from the following description of embodiments with reference to the accompanying drawings, in which:

[0031] Figure 1 The image schematically shows a scanning electron microscope (SEM) image of the inner wall morphology of the gas jet hole after treatment with a comparative etchant system.

[0032] Figure 2 The diagram illustrates a scanning electron microscope image of the inner wall morphology of a gas jet hole after treatment with the etching solution system according to an embodiment of this application. Detailed Implementation

[0033] The embodiments of this application will now be described with reference to the accompanying drawings. However, it should be understood that these descriptions are exemplary only and are not intended to limit the scope of this application. In the following detailed description, numerous specific details are set forth to provide a thorough understanding of the embodiments of this application for ease of explanation. However, it will be apparent that one or more embodiments may be implemented without these specific details. Furthermore, descriptions of well-known structures and technologies are omitted in the following description to avoid unnecessarily obscuring the concepts of this application.

[0034] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the scope of this application. 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.

[0035] 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.

[0036] When using expressions such as "at least one of A, B and C", they should generally be interpreted in accordance with the meaning that is commonly understood by those skilled in the art (e.g., "a system having at least one of A, B and C" should include, but is not limited to, a system having A alone, a system having B alone, a system having C alone, a system having A and B, a system having A and C, a system having B and C, and / or a system having A, B and C, etc.).

[0037] Electrodes mounted on the top of the ETCH system typically introduce process gas into the reaction chamber through multiple through-hole gas injection ports. The port size distribution, port shape accuracy, and surface quality of the port inner walls directly affect the uniformity of plasma distribution and process stability within the chamber. To obtain sufficient flux and good jet characteristics, numerous micro-gas injection ports with large depth-to-width ratios are often arranged inside the electrodes. These micro-holes are usually formed by mechanical drilling on brittle materials such as quartz, glass, glass ceramics, or alumina-based ceramics / ceramic composites containing silica-oxygen glass phases. However, drilling inevitably creates crushed layers, microcracks, scratches, and residual cutting chips on the inner walls of the holes. These damaged areas can easily become sources of particle detachment and discharge anomalies during subsequent plasma processing, introducing particle contamination, reducing product yield, and potentially shortening the electrode's lifespan.

[0038] The applicant's research revealed that a common wet etching method in some existing technologies employs a mixed acid system primarily composed of ammonium nitrate, ammonium bifluoride, and sulfuric acid, etching the entire electrode through immersion or simple circulation. While this type of etching solution can dissolve surface damage layers generated during drilling to some extent and reduce the depth of some scratches and microcracks, it still has significant limitations. On one hand, to avoid over-etching and morphological collapse in the borehole area, the effective acidity in existing mixed acid systems is limited, resulting in a limited amount of etching removal per unit time, which is insufficient to meet the maintenance time and equipment uptime requirements of high-cycle production lines. On the other hand, after processing with existing etching processes, the inner wall of the gas jet borehole still shows a significant amount of residual drilling crushed layer, scratch texture, and attached particles. The borehole sidewall contour exhibits obvious undulations and local pits, and the damage removal at the bottom of high aspect ratio boreholes is even more inadequate, indicating that the traditional mixed acid system is still insufficient in terms of repair capabilities and morphological control within deep holes.

[0039] The applicant further investigated existing technologies that improve etching performance by adjusting the ratio of hydrofluoric acid to nitric acid, introducing acetic acid or other organic acids, and employing methods such as impregnation and spraying to improve etching uniformity. However, if a low hydrofluoric acid content is maintained to reduce morphological risks, the dissolution rate of the damaged layer inside the hole is significantly low, making it difficult to complete effective repair within the allowed process time. If the concentrations of hydrofluoric acid and nitric acid are simply increased to pursue a higher etching rate, problems such as over-corrosion, abnormal hole diameter enlargement, and deterioration of sidewall roughness are likely to occur at the hole opening and upper region, and even local "biting" or shape collapse may occur, resulting in unsatisfactory overall performance. In addition, traditional impregnation or non-directional liquid flow methods cannot guarantee fluid renewal inside high aspect ratio channels. Bubbles and reaction products are prone to stagnation inside the hole, leading to uneven axial etching, insufficient etching at the bottom of the hole, and relative over-etching near the hole opening, thus creating a contradiction between high-speed etching and high surface quality.

[0040] Based on this, embodiments of this application provide an acidic etching solution composition comprising, by weight: 60-80 wt% nitric acid, 10-20 wt% hydrofluoric acid, and 10-20 wt% acetic acid. Embodiments of this application also provide an etching method for removing drilling damage from gas jet holes. The etching method includes: mounting an electrode having a plurality of gas jet holes in an etching apparatus, such that the axial direction of the gas jet holes is substantially along the direction of gravity, wherein the electrode is used in a plasma etching system; introducing the acidic etching solution composition into the etching apparatus, such that the acidic etching solution composition flows downward through the inner wall of the gas jet holes; and maintaining the downward flow of the acidic etching solution composition while etching the electrode for 3.8-4.2 minutes.

[0041] According to the embodiments of this application, at least the following beneficial effects are achieved: First, by controlling the concentrations of nitric acid, hydrofluoric acid, and acetic acid within specific concentration ranges of 60-80 wt%, 10-20 wt%, and 10-20 wt%, respectively, the removal of the drilling damage layer on the inner wall of the electrode gas jet hole can be completed in only 3.8-4.2 minutes while achieving an etching removal amount of approximately 50 μm. This significantly shortens the maintenance cycle and improves the effective uptime of the equipment. Second, by installing the electrode with the gas jet hole axially arranged basically along the direction of gravity and using a downward flow method to allow the acidic etching solution composition to flow through the inner wall of the gas jet hole, fresh etching solution can be continuously replenished into the high aspect ratio channel. At the same time, it is beneficial to the timely discharge of reaction products and bubbles, thereby alleviating the traditional problems of insufficient etching at the bottom of deep holes, over-etching in the hole opening area, and local residues. This achieves a relatively consistent etching removal amount and excellent sidewall morphology in the axial direction within the hole, which helps to reduce the risk of particle peeling, extend the electrode lifespan, and improve the overall yield and process stability of the plasma etching system.

[0042] It should be noted that the total amount of nitric acid, hydrofluoric acid and acetic acid in the acidic etching solution composition is 80-100 wt%, with the balance being water and / or additional components; the additional components may include wetting agents, corrosion inhibitors and / or surfactants to improve the wetting and defoaming performance in the micropores; in addition, the etching removal amount refers to the average material removal thickness along the normal direction of the inner wall of the gas jet hole.

[0043] The following will illustrate the implementation of this application through several embodiments. However, those skilled in the art should understand that these embodiments are merely illustrative and not intended to limit the scope of this application. Those skilled in the art can refer to the content of this document to appropriately improve the process parameters. It should be particularly noted that all similar substitutions and modifications are obvious to those skilled in the art and are considered to be included within this application. As for reagents or equipment that do not specify a brand or manufacturer, they are standard products readily available on the market.

[0044] It should be noted that the mass percentages of each component mentioned below are based on the mass of the added raw material; if the raw material is an aqueous solution of an acid (e.g., 70wt% nitric acid aqueous solution, 40-49wt% hydrofluoric acid aqueous solution), then the mass percentage is the mass fraction of the raw material solution in the etching solution composition. The sum of the mass fractions of each component is 100wt%. Furthermore, unless otherwise specified, "etching removal amount" mentioned below refers to the average increase in the diameter of the gas jet orifice ΔD (unit: μm), which corresponds to an equivalent removal thickness on one side of approximately ΔD / 2.

[0045] Comparative Example

[0046] The acidic etching solution composition of this comparative example comprises the following components by total mass: 5-15 wt% ammonium nitrate, 5-15 wt% ammonium bifluoride, 45-70 wt% sulfuric acid, <1 wt% inhibitor, and the balance being deionized water.

[0047] The specific preparation method is as follows: add a predetermined amount of deionized water to an acid-resistant stirred tank, slowly add sulfuric acid and stir evenly. After the temperature stabilizes at about 25°C, add ammonium nitrate, ammonium bifluoride and inhibitor in sequence, and continue stirring for 30 minutes to fully dissolve and mix the components evenly to obtain a comparative etching solution.

[0048] A quartz electrode used in a plasma etching system was selected as the object to be processed. This electrode was 20 mm thick and had numerous gas injection holes machined throughout its thickness, with a diameter of approximately 0.46 mm and an aspect ratio of not less than 10. The electrode was mounted in the etching equipment, with the gas injection holes aligned approximately along the direction of gravity. The electrode was etched using an immersion + weak circulation method, with the etching temperature controlled at 25 ± 2℃ and the etching time at 7 minutes.

[0049] After etching, the electrode was removed, rinsed with deionized water and dried, and the cross-section of the gas jet hole was observed and statistically measured under a microscope.

[0050] Figure 1 The diagram illustrates scanning electron microscope (SEM) images of the inner wall morphology of the gas jet orifice before and after treatment with a comparative etchant system.

[0051] Before etching, the cross-section of the gas injection hole, which had only undergone mechanical drilling, was observed using a scanning electron microscope. Figure 1 As shown in the left figure, a large area of ​​crushed layer and tearing scratches can be clearly seen on the inner wall of the hole. The surface of the hole wall is covered with a lot of flaky and blocky drill cuttings and particles, and the local edges are serrated or irregularly protruding, indicating that the drilling process has formed a thick damage layer and obvious morphological defects on the inner wall of the hole.

[0052] Subsequently, the electrode was treated with the etching solution composition of this comparative example at 25±2℃ for 7 minutes. After etching, the electrode was removed, rinsed with deionized water, and dried. The cross-section of the gas injection hole was then observed and statistically measured again under a microscope. Figure 1 As shown in the right figure, the thickness of the damaged layer on the inner wall of the gas jet hole has been reduced, and some of the attached particles have been dissolved and removed. The overall outline is slightly smoother than before etching, but obvious residual drilling and crushing layers, banded scratch textures, and unevenly distributed particle attachments can still be observed. The damage removal at the bottom of the high aspect ratio hole is particularly insufficient, and undulations and local pits still exist on the hole sidewall. The measurement results show that within a processing time of 7 minutes, the average etching removal amount (average hole diameter increment ΔD) on the inner wall of the gas jet hole is approximately 50 μm, corresponding to an average etching rate of 6–7 μm / min.

[0053] Furthermore, this comparative example performs a statistical analysis on the target dimensions (e.g., aperture) of multiple gas injection holes in the same batch, as shown in Table 1 below. The standard deviation is approximately 0.0017, indicating that the dimensional uniformity between holes is still limited under this etching condition.

[0054] Table 1. Comparison of aperture before and after etching (unit: mm)

[0055]

[0056] Example 1

[0057] The acidic etching solution composition of this embodiment comprises, by total mass, the following components: 60-80 wt% nitric acid, 10-20 wt% hydrofluoric acid, and 10-20 wt% acetic acid. The sum of the mass fractions of all components is 100 wt%.

[0058] The specific preparation method is as follows: A predetermined amount of concentrated nitric acid (e.g., 70 wt% nitric acid aqueous solution) is added to an acid-resistant stirred tank. Hydrofluoric acid aqueous solution is then slowly added under stirring conditions until the mixture is fully homogeneous. Glacial acetic acid is then added, and stirring continues for 30 minutes to obtain a transparent and homogeneous acidic etching solution composition. During the preparation process, the system temperature is controlled to not exceed 30°C to reduce volatilization and localized violent reactions.

[0059] A quartz electrode with the same structure and size as Comparative Example 1 was selected as the object to be processed. The electrode was installed in the etching equipment, with the axial direction of the gas injection hole basically along the direction of gravity. An etching solution preparation tank and a supply pipeline were set above the electrode, so that the acidic etching solution composition was introduced from above the electrode, flowed downward through the gas injection hole, and was recovered from the bottom, realizing a closed-loop circulation.

[0060] In this embodiment, the etching temperature was controlled at 25±2℃. By adjusting the etching solution flow rate and supply pressure, the acidic etching solution composition was made to form a stable and continuous downward flow on the inner wall of the gas injection hole. Under these conditions, etching was maintained for 4 minutes. After etching, the electrode was removed, rinsed with plenty of deionized water, and dried. The cross-section of the gas injection hole was then observed and its dimensions were measured under a microscope.

[0061] Test results show that under the conditions of this embodiment, the average etching removal amount (average aperture increment ΔD) of the gas jet hole inner wall is approximately 50 μm, corresponding to an average etching rate of approximately 12.6–12.9 μm / min, which is significantly higher than the 6–7 μm / min of Comparative Example 1. Under the premise of the same target etching depth (based on the same ΔD), the etching time is reduced from 7 minutes in the comparative example to 4 minutes.

[0062] Figure 2 The diagram illustrates a scanning electron microscope image of the inner wall morphology of a gas jet hole after treatment with the etching solution system according to an embodiment of this application.

[0063] like Figure 2 As shown in the left image, the inner wall of the gas jet hole, which has only undergone drilling, exhibits relatively obvious surface roughness and machining texture. Discontinuous undulations and locally attached microparticles / debris are visible at the hole wall edge, indicating that the inner wall still retains the characteristics of the damage layer formed during drilling. In contrast, as... Figure 2 As shown in the right figure, after treatment with the acidic etching solution composition and downward flow etching process in this embodiment, the inner wall contour of the gas jet hole is more straight and continuous, the surface texture is significantly weakened, the attached particles are significantly reduced, and the hole wall as a whole presents a more uniform gray level and a more continuous boundary. This indicates that the drilling crushing layer and most of the scratch texture are effectively removed, and no obvious over-corrosion, hole collapse or severe roughness or other unfavorable morphology is observed.

[0064] In addition, statistical analysis was performed on the target dimensions (e.g., aperture) of multiple gas injection holes in the same batch, as shown in Table 2 below. The standard deviation was approximately 0.0009, which was significantly lower than that of Comparative Example 1, indicating a significant improvement in the uniformity of hole dimensions.

[0065] Table 2 Comparison of aperture before and after etching in Example 1 (Unit: mm)

[0066]

[0067] Compared to Comparative Example 1, this embodiment achieves an etching removal amount of approximately 50 μm (based on the average aperture increment ΔD), while increasing the etching rate by approximately 2 times and significantly shortening the etching time. It also takes into account the damage removal effect and dimensional uniformity of the inner wall of the high aspect ratio gas jet hole, demonstrating the comprehensive advantages of the acidic etching solution composition and etching process of this application embodiment.

[0068] Example 2

[0069] The acidic etching solution composition of this embodiment comprises, by total mass, the following components: 60-80 wt% nitric acid, 10-20 wt% hydrofluoric acid, 10-20 wt% acetic acid, with the balance being water and / or additional components, wherein the additional components are one or more of wetting agents, corrosion inhibitors, and surfactants.

[0070] For example, in one specific formulation of this embodiment, the total mass includes: 70 wt% nitric acid, 15 wt% hydrofluoric acid, 14 wt% acetic acid, 0.8 wt% deionized water, and 0.2 wt% wetting agent. In another specific formulation, the total mass includes: 68 wt% nitric acid, 16 wt% hydrofluoric acid, 14 wt% acetic acid, 1.5 wt% deionized water, and 0.5 wt% corrosion inhibitor.

[0071] During preparation, a predetermined amount of nitric acid is first added to an acid-resistant stirred tank and stirred. Then, an aqueous solution of hydrofluoric acid is slowly added to ensure thorough mixing. Acetic acid is then added and stirring continues. After the solution temperature stabilizes, the additional components are added, and stirring continues until a transparent and homogeneous acidic etching solution composition is obtained. It is preferable to control the system temperature to not exceed 30°C during the preparation process.

[0072] Example 3

[0073] The acidic etching solution composition of this embodiment comprises the following components by total mass: 65-75 wt% nitric acid, 12-18 wt% hydrofluoric acid, 12-18 wt% acetic acid, and the balance being water.

[0074] For example, in a specific formulation of this embodiment, the total mass includes: 72 wt% nitric acid, 14 wt% hydrofluoric acid, 13 wt% acetic acid, and the balance being deionized water.

[0075] Example 4

[0076] The acidic etching solution composition of this embodiment comprises, by total mass, the following components: 60-80 wt% nitric acid, 10-20 wt% hydrofluoric acid, 10-20 wt% acetic acid, 0.01-5 wt% wetting agent and / or 0.01-5 wt% surfactant.

[0077] For example, in a specific formulation of this embodiment, the total mass includes: 68 wt% nitric acid, 16 wt% hydrofluoric acid, 15 wt% acetic acid, 0.5 wt% wetting agent, and the balance being deionized water.

[0078] In some embodiments of this application, to ensure that the acidic etching solution composition can fully renew and stably act on the inner wall of the gas injection orifice with a high aspect ratio, the flow rate and supply pressure of the etching solution can be adjusted to create a continuous downward flow of the acidic etching solution composition on the inner wall of the gas injection orifice. Specifically, the etching equipment may include a supply unit, a pressure regulating unit, and a recovery unit. The supply unit is used to introduce the acidic etching solution composition from above the electrode. The pressure regulating unit is used to perform closed-loop control of the supply pressure to create a stable pressure difference at the inlet of the gas injection orifice, thereby driving the etching solution to flow from top to bottom along the orifice axis and form a continuous liquid film on the inner wall. The recovery unit is used to collect the outflow liquid below the electrode and return it to the supply unit to form a cycle. To improve the flow distribution when multiple orifices are connected in parallel, a flow equalization structure (e.g., a distribution chamber / throttling component) can be provided on the supply side, and a filtration and degassing / degassing structure can be provided in the circulation loop to reduce the risk of local blockage or uneven etching caused by particles and bubbles.

[0079] In this process, the target flow range can be set according to the diameter, number of holes, and aspect ratio of the gas injection holes. Stable hydraulic pressure output can be achieved by adjusting the pump speed, valve opening, or pressure stabilizing device, ensuring the liquid inside the hole is in a continuous downward flow rather than intermittent dripping or localized stagnation. Because the continuous downward flow continuously replenishes fresh etching solution and promptly removes dissolved products, microparticles, and bubbles generated during the reaction, it reduces the risk of uneven etching caused by local concentration gradients and bubble adhesion within the hole. This improves the etching synchronization between the hole opening and bottom, facilitating the uniform removal of the drilling damage layer within a shorter etching time and obtaining a relatively straight and continuous hole wall morphology.

[0080] In some embodiments of this application, the use of acidic etchant compositions is provided for removing drilling damage and residual particles from the inner walls of gas jet holes in electrodes used in plasma etching systems.

[0081] Specifically, the electrode is positioned at the top of the ETCH system and performs the function of injecting process gas. It contains numerous penetrating micro-gas injection holes. Since these gas injection holes are often formed through mechanical drilling, residual particles such as crushed layers, microcracks, scratches, and cutting chips easily accumulate on the inner walls. These defects can become sources of particle detachment or discharge anomalies during subsequent plasma etching, thus affecting the uniformity of gas distribution and etching stability. Therefore, using an acidic etching solution composition to treat the inner walls of the gas injection holes allows for the chemical removal of the drilling damage layer without altering the overall electrode structure. This also allows the adhered particles to be expelled with the etchant, achieving cleaning and repair of the inner walls of the gas injection holes. This application effectively reduces the risk of particle contamination caused by residual defects on the inner walls, improves the dimensional consistency and inner wall morphology quality of the gas injection holes, and consequently extends the electrode's lifespan and improves the process repeatability and overall line yield of the plasma etching system.

[0082] In some embodiments of this application, electrodes for plasma etching systems are provided, which are obtained by etching using the aforementioned etching method. Specifically, the electrodes can be mounted in an etching apparatus with the axial direction of the gas jet holes substantially aligned with the direction of gravity. The acidic etching solution composition of Examples 2-4 of this application is introduced, allowing it to flow continuously downwards through the inner wall of the gas jet holes, and the inner wall is etched in a controlled manner for a processing time of 3.8-4.2 minutes. This etching process effectively removes the drilling damage layer and residual particles from the inner wall of the gas jet holes while maintaining the overall electrode structure, resulting in a straighter and more continuous inner wall profile, significantly reduced particle adhesion, and improved dimensional consistency of the hole array. The resulting electrodes are more suitable for long-term stable use in ETCH systems, reducing the risk of particle detachment, extending electrode lifespan, and improving the repeatability of the plasma etching process.

[0083] It should be noted that the nitric acid content in the embodiments of this application is controlled within the range of 60-80 wt%. Compared with acidic systems with lower nitric acid content, the use of the above-mentioned higher nitric acid content not only leads to an increase in etching rate, but also exhibits a more prominent comprehensive improvement effect in the repair of the inner wall of high aspect ratio gas jet holes. This is because: nitric acid provides a stronger and more continuous oxidizing environment in the system, making the surface chemical state of the hole wall more consistent before and after the action of hydrofluoric acid, reducing the difference of "hole opening priority and hole bottom insufficiency" caused by local reaction lag; at the same time, the higher nitric acid content helps to reduce the local reaction discontinuity caused by processing residues and microparticle shielding in the hole. Combined with the improvement of wetting and debubbling of the hole wall by wetting agents / surfactants, it can reduce the local etching obstruction caused by bubble adhesion and dissolution product retention, thereby making the etching reaction more continuous and stable throughout the entire length of the channel. Furthermore, under high nitric acid content conditions, the drilling damage layer and attached particles remaining on the borehole wall are more easily transformed and peeled off during the cycle renewal process, reducing secondary adhesion and local "masking effect", thereby reducing the probability of pitting defects and uneven morphology such as gray scale mottled.

[0084] The embodiments of this application have been described above; however, these embodiments are merely illustrative and not intended to limit the scope of this application. 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 application, and all such substitutions and modifications should fall within the scope of this application.

Claims

1. An acidic etching solution composition, characterized in that, The acidic etching solution composition comprises, by total mass: 60-80 wt% nitric acid, 10-20 wt% hydrofluoric acid, and 10-20 wt% acetic acid.

2. The acidic etching solution composition according to claim 1, wherein the acidic etching solution composition further comprises water and / or additional components, wherein, The additional components are one or more of wetting agents, corrosion inhibitors, and surfactants.

3. The acidic etching solution composition according to claim 1 or 2, characterized in that, The acidic etching solution composition comprises, by total mass: 65-75 wt% nitric acid, 12-18 wt% hydrofluoric acid, 12-18 wt% acetic acid, and the balance being water.

4. The acidic etching solution composition according to claim 1 or 2, characterized in that, The acidic etching solution composition further includes 0.01 to 5 wt% of a wetting agent and / or 0.01 to 5 wt% of a surfactant.

5. An etching method for removing drilling damage from gas jet holes, characterized in that, The etching method includes: An electrode with multiple gas injection holes is mounted in an etching apparatus, such that the axial direction of the gas injection holes is arranged substantially along the direction of gravity, wherein the electrode is used in a plasma etching system; The acidic etching solution composition according to any one of claims 1 to 4 is introduced into the etching apparatus, such that the acidic etching solution composition flows downward through the inner wall of the gas injection orifice; and The acidic etching solution composition is kept flowing downwards, and the electrode is etched for 3.8 to 4.2 minutes.

6. The etching method according to claim 5, characterized in that, The average etching rate of the electrode by the acidic etching solution composition is 12.6 to 12.9 μm / min.

7. The etching method according to claim 5, characterized in that, The process of allowing the acidic etching solution composition to flow downwards through the inner wall of the gas injection hole includes: By adjusting the flow rate and supply pressure of the etching solution, the acidic etching solution composition is made to form a continuous downward flow on the inner wall of the gas injection hole.

8. The application of an acidic etching solution composition, characterized in that, The acidic etching solution composition is the acidic etching solution composition according to any one of claims 1 to 4, and the acidic etching solution composition is used to remove drilling damage and residual particles from the inner wall of the gas jet hole in the electrode used in the plasma etching system.

9. The application of the acidic etching solution composition according to claim 8, characterized in that, The gas injection hole is a micropore extending through the thickness direction of the electrode; under the conditions of etching temperature of 20-40℃ and etching time of 3.8-4.2 minutes, by allowing the acidic etching solution composition to flow through the inner wall of the gas injection hole in a downward manner, the etching removal amount of the inner wall of the gas injection hole is 50-52 μm.

10. An electrode for a plasma etching system, characterized in that, The electrode has multiple gas injection holes that penetrate the thickness direction of the electrode, and the electrode is obtained by etching according to any one of claims 5 to 7.

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