Chemical polishing liquid as well as preparation method and application thereof

Abstract

The invention belongs to the technical field of cleaning of chemical vapor deposition devices, and relates to a chemical polishing liquid as well as a preparation method and application thereof. The technical problems that in the renovating and regenerating process of a diffuser in the prior art, local excessive corrosion can be caused by chemical cleaning liquid medicine, the hole diameter expansion amount is increased, the size and the shape in a hole are easily changed through mechanical grinding, all parts in the hole are difficult to cover, and the roughness in the hole cannot be reduced are solved. The invention provides a chemical polishing solution which comprises the following components in percentage by mass: 55-60% of phosphoric acid, 13-15% of sulfuric acid, 2.5-5% of a brightener, 0.3-1.5% of a corrosion inhibitor, 0.1-0.5% of copper sulfate and the balance of water. According to the invention, the hole diameter expansion amount of the diffuser is reduced, the roughness in the hole of the diffuser is reduced, the flow characteristic of reaction gas in the chemical vapor deposition process is improved, the uniformity and quality of film deposition are improved, the arc discharge phenomenon is prevented, and the hole diameter expansion amount is ensured to be less than 0.02 mm. The invention further provides a preparation method of the chemical polishing liquid medicine and application of the chemical polishing liquid medicine in cleaning of the gas diffuser.

Description

Technical Field

[0001] This invention belongs to the field of chemical vapor deposition (CVD) equipment cleaning technology, specifically relating to a chemical polishing solution, its preparation method, and its application. Background Technology

[0002] In the display panel manufacturing process, chemical vapor deposition (CVD) is used to deposit various thin films, such as silicon dioxide (SiO2) and silicon nitride (Si3N4). The diffuser's function is to uniformly deliver the reactant gases into the reaction chamber, such as... Figure 1 As shown, however, during use, the diffuser pores are easily clogged by contaminants such as reaction byproducts and unreacted precursor particles. Here are some common solutions:

[0003] (1) Chemical Cleaning: This method uses suitable chemical reagents to remove impurities from the diffuser orifices. Its advantages include good cleaning effect; appropriate chemical cleaning agents can be selected based on the type and nature of the dirt. For stubborn organic and inorganic dirt, such as metal oxides, metal salts, photoresist residues, and organic polymers, chemical reactions can dissolve, decompose, or transform them into easily removable substances, achieving a better cleaning effect and effectively restoring the patency and surface cleanliness of the diffuser orifices. Furthermore, the operation is relatively simple, requiring no complex equipment. Multiple diffusers or large diffusers can be simultaneously immersed in the cleaning solution for cleaning, making it suitable for large-scale production cleaning needs, improving cleaning efficiency, and reducing cleaning costs. However, corrosion may occur during cleaning. If the concentration, temperature, and cleaning time of the chemical cleaning agent are not properly controlled, it may corrode the diffuser material, especially for diffusers with high precision and high performance requirements. Even slight corrosion can affect their performance and service life, such as changing the orifice size and roughness.

[0004] (2) Mechanical Grinding: For issues such as roughness and burrs on the inner surface of diffuser holes, mechanical grinding is used. Theoretically, while removing dirt, it can also polish and micro-machine the inner surface of the hole to a certain extent, making the inner surface smoother and reducing surface roughness. However, in practice, this method can easily affect the size and shape of the hole. Furthermore, mechanical grinding is difficult for diffusers with small apertures. For diffuser holes with complex shapes and irregular internal structures, mechanical grinding cannot completely cover all parts of the hole, resulting in uneven cleaning, dead zones, and incomplete removal of dirt.

[0005] In the current process of refurbishing and regenerating diffusers, chemical cleaning solutions can cause excessive local corrosion and increase the pore size expansion. Mechanical grinding can easily change the size and shape of the pores and is difficult to cover all parts of the pores, thus failing to reduce the roughness inside the pores. Therefore, there is an urgent need for a cleaning solution for gas diffusers in chemical vapor deposition that can reduce the roughness inside the pores while ensuring minimal changes in pore size expansion. Summary of the Invention

[0006] 1. The problem to be solved

[0007] In existing diffuser refurbishment and regeneration processes, chemical cleaning solutions can cause excessive localized corrosion and increased pore size expansion. Mechanical polishing, on the other hand, can easily alter the internal dimensions and shape of the pores and is insufficient to cover all areas within the pores, failing to reduce internal roughness. This application provides a chemical polishing solution that reduces internal roughness, thereby improving the flow characteristics of reactant gases in chemical vapor deposition (CVD) processes, enhancing the uniformity and quality of thin film deposition, preventing arcing, and ensuring that pore size expansion is less than 0.02 mm. This application also provides a method for preparing the chemical polishing solution. Furthermore, this application provides the use of the chemical polishing solution in cleaning gas diffusers.

[0008] 2. Technical Solution

[0009] To achieve the above objectives, the provided technical solution is as follows:

[0010] A chemical polishing solution, by mass concentration, contains 55%–60% phosphoric acid, 13%–15% sulfuric acid, 2.5%–5% brightener, 0.3%–1.5% corrosion inhibitor, and 0.1%–0.5% copper sulfate, with the balance being water.

[0011] Furthermore, the brightener comprises polyferric sulfate and N-methylpyrrolidone; in the chemical polishing solution, the polyferric sulfate is 0.5% to 2% and the N-methylpyrrolidone is 2% to 3% by mass concentration.

[0012] Furthermore, the corrosion inhibitor comprises sodium molybdate.

[0013] A method for preparing a chemical polishing solution includes the following steps:

[0014] Slowly add sulfuric acid to phosphoric acid and water, allow to mature, and cool to room temperature to obtain an acid solution;

[0015] Polyferric sulfate, sodium molybdate, and copper sulfate are mixed and dissolved to obtain a mixed solution;

[0016] The mixture is added to the acid solution and stirred until clear. Then N-methylpyrrolidone is added to obtain a chemical polishing solution.

[0017] Furthermore, the phosphoric acid has a purity of ≥85wt%; the sulfuric acid is concentrated sulfuric acid with a purity of ≥98wt%.

[0018] Furthermore, during the preparation of the chemical polishing solution, the pH is controlled to be ≥2.

[0019] An application of a chemical polishing solution, wherein the chemical polishing solution is used in the preparation of a cleaning solution for a gas diffuser in chemical vapor deposition.

[0020] Furthermore, the cleaning of the gas diffuser includes the following steps:

[0021] The gas diffuser is subjected to degreasing, water washing, alkaline etching, water washing, neutralization, water washing, immersion in chemical polishing solution, and water washing in sequence; the immersion time in the chemical polishing solution is 3 min to 7 min, and the immersion temperature is 80℃ to 100℃.

[0022] Furthermore, the degreasing is carried out using an alkaline degreasing agent with a pH value of 8 to 15 at a temperature of 45°C to 65°C;

[0023] The alkaline etching process uses an alkaline etchant and involves immersing the sample in an alkaline solution at a temperature of 35°C to 55°C for 3 to 15 minutes.

[0024] The neutralization is performed using a nitric acid solution, soaking for 5 to 20 minutes at a temperature of 25°C to 45°C.

[0025] 3. Beneficial effects

[0026] Compared with existing known technologies, the technical solution provided by this invention has the following beneficial effects:

[0027] (1) A chemical polishing solution of the present invention, by mass concentration, comprises 55%–60% phosphoric acid, 13%–15% sulfuric acid, 2.5%–5% brightener, 0.3%–1.5% corrosion inhibitor, and 0.1%–0.5% copper sulfate, with the balance being water. This chemical polishing solution can prevent localized excessive corrosion, reduce the roughness inside the pores, thereby improving the flow characteristics of the reactive gases in the chemical vapor deposition (CVD) process, enhancing the uniformity and quality of thin film deposition, preventing the occurrence of arcing, and ensuring that the pore size expansion is less than 0.02 mm.

[0028] (2) A method for preparing a chemical polishing solution according to the present invention involves slowly adding sulfuric acid to phosphoric acid and water, aging the solution, and cooling it to room temperature to obtain an acid solution. Slow addition of sulfuric acid and low-temperature control avoid violent exothermic reactions, reduce the thermal decomposition of phosphoric acid, lower the risk of side reactions, and improve reaction stability. Further aging ensures a more complete reaction. Polyferric sulfate, sodium molybdate, and copper sulfate are mixed and dissolved to obtain a mixed solution. If the three salts are added separately, they are prone to precipitating copper molybdate and ferric hydroxide due to excessively high local concentrations. Co-dissolving them first allows the formation of homogeneous complex ions. The mixed solution is added to the aged acid solution and stirred until clear. Then, N-methylpyrrolidone is added to obtain the chemical polishing solution. Because N-methylpyrrolidone has limited thermal stability and is easily volatilized at temperatures above 95°C, its addition at the end avoids the aging stage, maximizing the preservation of its functionality. This preparation method is simple to operate and easy to control.

[0029] (3) An application of the chemical polishing solution of the present invention is used in the preparation of a cleaning solution for a gas diffuser in chemical vapor deposition. The cleaning of the gas diffuser includes the following steps: the gas diffuser is sequentially subjected to degreasing, water washing, alkaline etching, water washing, neutralization, water washing, immersion in the chemical polishing solution, and water washing; the immersion time in the chemical polishing solution is 3 min to 7 min, and the immersion temperature is 80℃ to 100℃. Through the selective corrosion effect of the chemical polishing solution, the roughness inside the pores (Φ0.500mm) caused by the product's fine pores (Φ0.500mm) during the refurbishment and regeneration cleaning process is reduced, and the problem of localized excessive corrosion and increased pore size caused by existing chemical cleaning solutions is solved. After treatment, the diffuser surface is smoother and the pores are more unobstructed, enabling more uniform gas diffusion in the diffuser. This is crucial for the uniform distribution of reactant gases in the chemical vapor deposition (CVD) process, and helps to improve the quality and performance of the thin film. In the chemical vapor deposition (CVD) process for preparing thin films, the use of a treated diffuser can improve the uniformity of the distribution of reactive gases, thereby resulting in better uniformity of the deposited film thickness and more stable electrical properties. Attached Figure Description

[0030] Figure 1 This is a schematic diagram of a chemical vapor deposition (CVD) component.

[0031] Figure 2 This is a flow chart of the gas diffuser cleaning process.

[0032] Figure 3 Comparison images of the sandblasted test block before and after immersion in chemical polishing solution;

[0033] Figure 4 Comparison of chemical polishing solution immersion process before and after for perforated gas diffuser test blocks

[0034] Figure 5Microscopic comparison images of the planes and holes before and after chemical polishing solution treatment for Examples 2 (F1-F4), Comparative Examples 1 (H1-H4), Comparative Examples 2 (I1-I4), Comparative Examples 4 (J1-J4), and Comparative Examples 5 (K1-K4); Microscopic images of the planes and holes without chemical polishing solution treatment (G1, G2). Detailed Implementation

[0035] To further understand the content of this invention, the invention will be described in detail with reference to the embodiments.

[0036] The present application will be further described below with reference to specific embodiments.

[0037] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains; the term “and / or” as used herein includes any and all combinations of one or more of the associated listed items.

[0038] Unless otherwise specified in the examples, the procedures should be performed under standard conditions or conditions recommended by the manufacturer. Reagents or instruments whose manufacturers are not specified are all commercially available products.

[0039] As used herein, the term “about” is used to provide for the flexibility and imprecision associated with a given term, measure, or value. Those skilled in the art can readily determine the degree of flexibility for a particular variable.

[0040] As used herein, the term “at least one of…” is intended to be synonymous with “one or more of…”. For example, “at least one of A, B, and C” explicitly includes only A, only B, only C, and combinations thereof.

[0041] Concentration, amount, and other numerical data may be presented in range format herein. It should be understood that such range format is used solely for convenience and brevity and should be flexibly interpreted to include not only the values ​​explicitly stated as the limits of the range, but also all individual values ​​or subranges encompassed within the range, as if each value and subrange were explicitly stated. For example, a range of values ​​from about 1 to about 4.5 should be interpreted to include not only the explicitly stated limits of 1 to 4.5, but also individual numbers (such as 2, 3, 4) and subranges (such as 1 to 3, 2 to 4, etc.). The same principle applies to ranges that describe only a single value, such as “less than about 4.5,” which should be interpreted to include all the aforementioned values ​​and ranges. Furthermore, this interpretation should apply regardless of the breadth of the range or characteristic described.

[0042] The composition, proportion, and function of the chemical polishing solution in the following examples are shown in Table 1:

[0043] Table 1. Composition, proportion, and effects of chemical polishing solutions

[0044] Drug components Mass concentration of each component in the liquid medicine effect Phosphoric acid 55％～60％ Film formation and leveling sulfuric acid 13％～15％ Strong acid dissolution and activation Polyferric sulfate 0.5％～2％ Oxidative strengthening Sodium molybdate 0.3％～1.5％ Corrosion Inhibitor Copper sulfate 0.1％～0.5％ Catalytic oxidation N-Methylpyrrolidone 2～3％ organic solvents

[0045] Example 1

[0046] This embodiment describes a method for preparing a chemical polishing solution, comprising the following steps:

[0047] Add phosphoric acid (85wt%) and ultrapure water sequentially to the PP reaction tank, start the stirrer, slowly add concentrated sulfuric acid (98wt%), let it mature, and cool to room temperature to obtain an acid solution. Maturation means letting it stand for a period of time (30min) to allow the sulfuric acid, phosphoric acid and water to mix thoroughly and evenly, avoiding local concentrations that are too high or too low. Due to the intense exothermic reaction, it needs to be placed at room temperature before use.

[0048] Polyferric sulfate, sodium molybdate, and copper sulfate were pre-dissolved in hot water at 60°C to obtain a mixed solution;

[0049] The mixture is then added dropwise to the acid solution above, stirred until clear, and then N-methylpyrrolidone and deionized water are added to obtain the chemical polishing solution.

[0050] Precautions: The preparation of chemical polishing solutions must be carried out in a well-ventilated environment. Concentrated sulfuric acid must be added slowly to prevent bumping. Sodium molybdate will be ineffective at pH < 2, so the pH needs to be controlled at ≥ 2 during the preparation process. N-methylpyrrolidone is volatile at high temperatures (> 95℃).

[0051] The chemical polishing solution, by mass concentration, consists of 55% phosphoric acid, 13% sulfuric acid, 0.5% polyferric sulfate, 0.3% sodium molybdate, 0.1% copper sulfate, and 2% N-methylpyrrolidone, with the balance being water.

[0052] Example 2

[0053] The preparation method of the chemical polishing solution in this embodiment is basically the same as that in Example 1, except that the composition of the chemical polishing solution, calculated by mass concentration, is 60% phosphoric acid, 13% sulfuric acid, 0.5% polyferric sulfate, 0.3% sodium molybdate, 0.1% copper sulfate, and 2% N-methylpyrrolidone, with the balance being water.

[0054] Example 3

[0055] The preparation method of the chemical polishing solution in this embodiment is basically the same as that in Example 1, except that the composition of the chemical polishing solution is as follows: 60% phosphoric acid, 15% sulfuric acid, 0.5% polyferric sulfate, 0.3% sodium molybdate, 0.1% copper sulfate, and 2% N-methylpyrrolidone, with the remainder being water.

[0056] Example 4

[0057] The preparation method of the chemical polishing solution in this embodiment is basically the same as that in Example 1, except that the composition of the chemical polishing solution is as follows: 60% phosphoric acid, 15% sulfuric acid, 2% polyferric sulfate, 0.3% sodium molybdate, 0.1% copper sulfate, and 2% N-methylpyrrolidone, with the remainder being water.

[0058] Example 5

[0059] The preparation method of the chemical polishing solution in this embodiment is basically the same as that in Example 1, except that the composition of the chemical polishing solution, calculated by mass concentration, is 60% phosphoric acid, 15% sulfuric acid, 2% polyferric sulfate, 1.5% sodium molybdate, 0.1% copper sulfate, and 2% N-methylpyrrolidone, with the remainder being water.

[0060] Example 6

[0061] The preparation method of the chemical polishing solution in this embodiment is basically the same as that in Example 1, except that the composition of the chemical polishing solution is as follows: 60% phosphoric acid, 15% sulfuric acid, 2% polyferric sulfate, 1.5% sodium molybdate, 0.5% copper sulfate, and 2% N-methylpyrrolidone, with the remainder being water.

[0062] Example 7

[0063] The preparation method of the chemical polishing solution in this embodiment is basically the same as that in Example 1, except that the composition of the chemical polishing solution is as follows: 60% phosphoric acid, 15% sulfuric acid, 2% polyferric sulfate, 1.5% sodium molybdate, 0.5% copper sulfate, and 3% N-methylpyrrolidone, with the remainder being water.

[0064] Table 2 Summary of the chemical polishing solution composition in Examples 1-7

[0065]

[0066] Comparative Example 1

[0067] The preparation method of the chemical polishing solution in this embodiment is basically the same as that in Example 1, except that the composition of the chemical polishing solution is as follows: 50% phosphoric acid, 13% sulfuric acid, 0.5% polyferric sulfate, 0.3% sodium molybdate, 0.1% copper sulfate, and 2% N-methylpyrrolidone, with the remainder being water.

[0068] Comparative Example 2

[0069] The preparation method of the chemical polishing solution in this embodiment is basically the same as that in Example 1, except that the composition of the chemical polishing solution is as follows: 65% phosphoric acid, 13% sulfuric acid, 0.5% polyferric sulfate, 0.3% sodium molybdate, 0.1% copper sulfate, and 2% N-methylpyrrolidone, with the remainder being water.

[0070] Comparative Example 3

[0071] This comparative example describes a method for preparing a chemical polishing solution, comprising the following steps: adding phosphoric acid (85 wt% purity) and ultrapure water to a PP reaction tank, starting the stirrer, and adding concentrated sulfuric acid (98 wt% purity) dropwise in batches due to the vigorous reaction. After the solution has matured and slowly cooled to room temperature, the chemical polishing solution is obtained. The composition of the chemical polishing solution, calculated by mass concentration, is 70% phosphoric acid, 20% sulfuric acid, and the remainder is water.

[0072] Comparative Example 4

[0073] This comparative example describes a method for preparing a chemical polishing solution, comprising the following steps: adding phosphoric acid (85 wt% purity) to a PP reaction tank, starting the stirrer, and adding concentrated sulfuric acid (98 wt% purity) dropwise in batches due to the vigorous reaction. After the solution has matured and slowly cooled to room temperature, the chemical polishing solution is obtained. The composition of the chemical polishing solution, calculated by mass concentration, is 75% phosphoric acid and 25% sulfuric acid.

[0074] Comparative Example 5

[0075] This comparative example describes a method for preparing a chemical polishing solution, comprising the following steps: adding phosphoric acid (85 wt% purity) to a PP reaction tank, starting the stirrer, and adding concentrated sulfuric acid (98 wt% purity) dropwise in batches due to the vigorous reaction. After the solution has matured and slowly cooled to room temperature, the chemical polishing solution is obtained. The composition of the chemical polishing solution, calculated by mass concentration, is 50% phosphoric acid and 50% sulfuric acid.

[0076] Table 3 Summary of the chemical polishing solutions used in Comparative Examples 1–5

[0077]

[0078] Phosphoric acid (H3PO4): Phosphoric acid is a moderately strong acid that reacts with the metal surface in chemical polishing solutions to form a phosphate protective film. This film helps control the dissolution rate of the metal, making the polishing process more uniform. Simultaneously, phosphoric acid has a certain viscosity, which allows the polishing solution to adhere better to the surface being polished, prolonging the reaction time between the polishing solution and the metal surface, thus contributing to a smoother surface. Overall, the core functions of phosphoric acid are film formation and leveling. It can react with metal to form a dense phosphate passivation film, improving reflectivity, while its high viscosity can inhibit over-corrosion in recessed areas and preferentially dissolve raised areas.

[0079] Sulfuric acid (H₂SO₄): Sulfuric acid is a strong acid with strong oxidizing and corrosive properties. In chemical polishing solutions, sulfuric acid provides an acidic environment (pH 2–5), accelerating the oxidation process on metal surfaces and making metal atoms more easily oxidized into metal oxides, thereby promoting the polishing process. It can also react with metal oxides, dissolving them and helping to remove the oxide layer and impurities from the surface. It is often combined with phosphoric acid to control the reaction rate and prevent hydrogen embrittlement.

[0080] Polyferric sulfate (PFS): Primarily used as an oxidant and etching promoter in chemical polishing solutions. In acidic environments, PFS can release Fe... 3+ and sulfate, Fe 3+ It dissolves metal surfaces (such as copper and aluminum) by oxidizing them, forming a smooth surface. It also promotes uniform surface dissolution, and its polymeric structure stabilizes the pH of the chemical polishing solution, reducing localized over-etching and improving surface finish.

[0081] Sodium molybdate (Na2MoO4): Sodium molybdate reacts with free MoO4 on the surface of aluminum metal. 2- Ionic reactions generate a dense molybdate passivation film, inhibiting excessive metal dissolution and preventing pitting or roughening: Al + MoO4 2- +H₂O→Al₂O₃·MoO₃+OH - In acidic chemical polishing solutions, MoO4 2- It can be reduced to low-valence molybdenum (such as Mo). 4+ At the same time, it oxidizes aluminum metal, promoting controlled dissolution. The redox buffering effect of sodium molybdate can stabilize the potential of the polishing solution and avoid uneven polishing caused by rapid decomposition of oxidant. When compounded with phosphates, silicates, etc., sodium molybdate can enhance the stability of passivation film and extend the life of polishing solution.

[0082] Copper sulfate (CuSO4): Copper sulfate is an important additive in chemical polishing solutions, playing a crucial role, especially in the chemical polishing of copper, brass, aluminum, and their alloys. Its main functions include oxidation etching, catalytic promotion, and surface smoothing, with oxidation etching being the primary function. Copper sulfate dissociates into Cu upon dissolving in water. 2+ In acidic polishing solutions, Cu 2+ Al that can replace aluminum surface 3+ This triggers a localized micro-battery reaction, accelerating the uniform dissolution of aluminum and forming a smooth surface: 2Al + 3Cu 2+ →2Al 3+ +3Cu↓. Additionally, Cu... 2+ It can catalyze the decomposition of oxidants, improving polishing efficiency, Cu 2+Adsorbed on active sites on the metal surface (such as grain boundaries or defects), it selectively inhibits etching of the metal surface, preferentially dissolves protrusions, and reduces surface roughness (Ra).

[0083] N-Methylpyrrolidone (C5H9NO): Abbreviated as NMP, NMP can effectively remove residual grease, organic films, or polishing byproducts (such as resins and waxes) during aluminum alloy polishing due to its strong dissolving ability, thus avoiding surface defects. It can also promote the partial dissolution or loosening of the Al2O3 oxide layer, resulting in more uniform subsequent etching. The polar molecular structure of NMP can significantly reduce the surface tension of the polishing solution, allowing it to spread more evenly on the aluminum alloy surface and reducing uneven polishing or streaking. In acidic polishing solutions, NMP can inhibit the retention of hydrogen (H2) bubbles on the aluminum surface, preventing localized corrosion or pitting. In polishing solutions containing phosphoric acid or sulfuric acid, NMP can optimize the etching rate of aluminum by the acid and improve the gloss.

[0084] As shown in Examples 1-7, and in conjunction with Tables 4 and 5 of the performance tests, the chemical polishing solution formed by combining phosphoric acid (H3PO4), sulfuric acid (H2SO4), polyferric sulfate (PFS), sodium molybdate (Na2MoO4), copper sulfate (CuSO4), and N-methylpyrrolidone (NMP) has synergistic effects, reduces roughness of planes and holes, reduces pore size expansion, slows down corrosion and controls the rate of corrosion, preferentially dissolves protruding parts, reduces local over-etching, improves surface smoothness, increases gloss, and stabilizes the lifespan of the chemical polishing solution.

[0085] By adjusting the proportions of the raw materials in the test chemical polishing slurry, calculated by mass concentration, it contains 55%–60% phosphoric acid, 13%–15% sulfuric acid, 0.5%–2% polyferric sulfate, 0.3%–1.5% sodium molybdate, 0.1%–0.5% copper sulfate, and 2%–3% N-methylpyrrolidone. Excessive polyferric sulfate content leads to surface roughness, while excessive copper sulfate content leads to Cu precipitation and black spots. By testing reaction time conditions, a chemical polishing slurry was developed that can reduce the roughness inside the diffuser pores while maintaining the pore size expansion within an allowable range.

[0086] As shown in Comparative Examples 1 and 2, when the phosphoric acid content is below 55%, the reaction with the metal surface in the chemical polishing solution results in an incomplete phosphate protective film, leading to localized corrosion of the metal surface and an insignificant effect on reducing roughness. When the phosphoric acid content is above 60%, it disrupts the synergistic effect with other components, resulting in a generally weak effect on reducing roughness and a large variation in pore size expansion.

[0087] As can be seen from Comparative Examples 3 to 5, although the combination of phosphoric acid and sulfuric acid can dissolve the oxides on the metal surface and thus remove the tiny protrusions on the surface, these two acids alone may not be able to effectively form a uniform viscous film, resulting in poor surface leveling and little change in roughness. When only phosphoric acid and sulfuric acid are used, the reaction rate is difficult to control precisely, and over-corrosion or insufficient dissolution is likely to occur.

[0088] Example 8

[0089] This embodiment describes the application of a chemical polishing solution in the cleaning of a gas diffuser, such as... Figure 2 As shown, it includes the following steps:

[0090] The product is subjected to degreasing, water washing, alkaline etching, water washing, neutralization, water washing, immersion in chemical polishing solution, and water washing in sequence.

[0091] Degreasing: Use an alkaline degreasing agent with pH 12±0.5 at a temperature of 45℃~65℃ to thoroughly remove oil, grease, rust-preventive oil, dust and processing residues (such as stamping oil and cutting fluid) from the aluminum alloy surface.

[0092] Alkaline etching: Using an alkaline etchant, the product is immersed in the solution for 3 to 15 minutes at a temperature of 35 to 55°C. The purpose is to remove the natural oxide film on the surface of the aluminum alloy and to perform micro-etching on the surface of the aluminum alloy to prepare for the subsequent adhesion of the oxide film.

[0093] Neutralization: Use nitric acid solution to soak the product for 5 to 20 minutes at a temperature of 25 to 45°C. This is done to neutralize the residual alkali solution from the previous alkaline etching process and prevent continued corrosion. It is also to remove the gray-black "ash" residue that adheres to the surface after alkaline etching. The main components of this residue are insoluble intermetallic compounds such as Al, Si, Fe, and Cu.

[0094] Chemical polishing solution immersion: Immersion time is 3 min, 5 min and 7 min respectively, immersion temperature is 90℃; after the neutralization process, the chemical polishing solution immersion process and water washing can significantly remove dirt in the diffuser hole, reduce the occurrence of small particles; and reduce the roughness in the hole, so that the gas diffusion is more uniform and smooth.

[0095] Water washing: This is a crucial operation that runs through every step of the process. Ultrapure water is used to soak the product to prevent cross-contamination caused by the previous step's solution being carried into the next process tank.

[0096] Finally, the functional membrane is regenerated through anodizing and cleaning.

[0097] The chemical polishing solutions used in this embodiment were prepared in Examples 1 to 7, respectively.

[0098] Comparative Example 6

[0099] The application of a chemical polishing solution in the cleaning of a gas diffuser in this comparative example is basically the same as in Example 8, except that:

[0100] The chemical polishing solutions used in this comparative example were prepared in Comparative Examples 1 to 5, respectively.

[0101] Comparative Example 7

[0102] The gas diffuser cleaning process in this comparative example is basically the same as in Example 8, except that:

[0103] The process of soaking in chemical polishing solution after neutralization and rinsing with water is removed.

[0104] Performance testing

[0105] I. The average roughness change and average pore size expansion of the gas diffusers in Example 8 (using the chemical polishing solutions prepared in Examples 1-7) and Comparative Example 6 (using the chemical polishing solutions prepared in Comparative Examples 1-5) before and after immersion in the chemical polishing solutions, as well as the average roughness change and average pore size expansion of the gas diffuser in Comparative Example 7 (without using chemical polishing solutions), are shown in Table 4:

[0106] Table 4 Experimental Data of Chemical Polishing Solution

[0107]

[0108]

[0109] Note: Ra reflects the change in the average level of the overall surface roughness, Rz measures the change in the intensity of local surface undulations, and Ry represents the change in the maximum local height difference of the surface.

[0110] Table 4 shows the experimental data for Example 8, Comparative Example 6, and Comparative Example 7. Based on the data, it is necessary to ensure that the pore size expansion (pore size after cleaning - pore size before cleaning) is less than 0.020 mm. Comparative Examples 3 and 5 did not meet this requirement, while the pore size expansion of the other comparative examples and examples met the requirement. Next, we consider the roughness. The target roughness value, Ra, is set as the integer of the maximum roughness change value in Table 4. 目标值 The value is 1, Rz. 目标值 The value is 8, Ry. 目标值 The roughness is 9. In this application, the roughness is precisely controlled using a weighting ratio of 70% Ra. / Ra. 目标值 +15% Rz / Rz. 目标值 +15%Ry. / Ry. 目标值 The optimal conditions for each set of examples and comparative examples were selected, and the data were normalized and simplified to obtain Table 5:

[0111] Table 5. Roughness Normalization Data

[0112]

[0113]

[0114] Comparative Example 7, which was not immersed in chemical polishing solution, showed zero average roughness change and zero average pore size expansion, requiring no normalization. The data analysis table indicates that Example 2 represents the optimal condition parameters. In this application scenario, the change in aluminum roughness and the pore size expansion are equally important. Roughness is crucial for the surface cleanliness, brightness, and subsequent processes, thus affecting yield. Pore size expansion is important because excessive expansion can lead to uneven flow / optical path distribution and rejection issues during customer installation. Based on the overall roughness score, Example 2 showed significantly better roughness change under 7-minute conditions compared to other examples and the comparative example. Therefore, the optimal process parameters are those provided in Example 2.

[0115] II. Comparison of test samples before and after immersion in chemical polishing solution

[0116] Example 8 describes the application of a chemical polishing solution in the cleaning of a gas diffuser. Macroscopic and microscopic images of the product after soaking in the chemical polishing solution prepared in Example 2 for 7 minutes are shown below. Figure 3 and Figure 4 As shown:

[0117] (1) Sandblasted test block: from Figure 3 Test block A was initially unsoaked and Figure 3 The macroscopic comparison image of the B test block after immersion shows that the sandblasted surface has a visibly improved brightness and a smoother surface. Under a microscope at 60x magnification, as shown... Figure 3 The initial blasting surface of a and Figure 3 After being heated and soaked in the chemical polishing solution for 7 minutes, the surface of the test block became brighter and smoother, indicating a reduction in roughness.

[0118] (2) Perforated gas diffuser test block: from Figure 4 Test block D was not soaked and Figure 4 The macroscopic comparison images of the E-type test block after soaking show that the overall test block is brighter. The internal pores of the perforated gas diffuser test block are magnified 60 times under a microscope, while the horn-shaped holes of the perforated gas diffuser test block are magnified 100 times under a microscope. Figure 4 d shows the microscopic images of the inside of the holes and the horn-shaped holes of the initially unsoaked test block. Figure 4e shows a microscopic image of the inside of the hole and the horn hole of the test block after being heated and soaked for 7 minutes. It can be seen that after soaking in the chemical polishing solution, the original screw-like patterns inside the hole of the perforated gas diffuser test block became smoother and almost disappeared; the pits left by sandblasting in the horn hole also became smoother, which has the effect of reducing roughness.

[0119] Observe and compare the microscopic images of the gas diffuser test blocks before and after treatment (immersion) with the chemical polishing solution prepared in Example 2, Comparative Example 1, Comparative Example 2, Comparative Example 4, and Comparative Example 5, such as... Figure 5 As shown:

[0120] Specifically, the microscopic comparison images of the gas diffuser test block before and after treatment with the chemical polishing solution prepared in Example 2 for 7 minutes (e.g.) Figure 5 F1, 4F2); Microscopic comparison images inside the hole (e.g.) Figure 5 F3, F4);

[0121] Microscopic comparison of the gas diffuser specimen before and after treatment with the chemical polishing solution prepared in Comparative Example 1 for 5 minutes (e.g.) Figure 5 H1, H2); Microscopic comparison images of the inside of the pores (e.g., H1, H2); Figure 5 H3, H4);

[0122] Microscopic comparison of the gas diffuser specimen before and after treatment with the chemical polishing solution prepared in Comparative Example 2 for 5 minutes (e.g.) Figure 5 I1, I2); Microscopic comparison images of the inside of the pores (e.g.) Figure 5 I3, I4);

[0123] Microscopic comparison of the gas diffuser specimen before and after treatment with the chemical polishing solution prepared in Comparative Example 4 for 5 minutes (e.g.) Figure 5 J1, J2); Microscopic comparison images of the inside of the holes (e.g., J1, J2); Figure 5 J3, J4);

[0124] Microscopic comparison of the gas diffuser specimen before and after treatment with the chemical polishing solution prepared in Comparative Example 5 for 5 minutes (e.g.) Figure 5 K1, K2); Microscopic comparison images inside the holes (e.g., K1, K2); Figure 5 K3, K4);

[0125] Comparative Example 7: A flat surface not treated with chemical polishing solution (e.g.) Figure 5 G1) and inside the hole (such as G1) Figure 5 Microscopic diagram of G2);

[0126] from Figure 5The comparison images of the gas diffuser test blocks before and after treatment with the chemical polishing solution prepared in Examples 2, 1, 2, 4, and 5 show that the chemical polishing solution in Example 2 has the best effect on reducing surface and hole roughness, and the hole diameter expansion is less than 0.02. The roughness of the gas diffuser test block in Comparative Example 7, which was not treated with the chemical polishing solution, did not change.

[0127] The embodiments described above are merely preferred embodiments of the present invention, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that those skilled in the art can make various modifications, improvements, and substitutions without departing from the concept of the present invention, and these all fall within the scope of protection of the present invention. Therefore, the scope of protection of this patent should be determined by the appended claims.

Claims

1. A chemical polishing solution, characterized in that: Based on mass concentration, it contains 55%–60% phosphoric acid, 13%–15% sulfuric acid, 2.5%–5% brightener, 0.3%–1.5% corrosion inhibitor, and 0.1%–0.5% copper sulfate, with the balance being water.

2. The chemical polishing solution according to claim 1, characterized in that: The brightener comprises polyferric sulfate and N-methylpyrrolidone; the chemical polishing solution contains, by mass concentration, 0.5% to 2% polyferric sulfate and 2% to 3% N-methylpyrrolidone.

3. The chemical polishing solution according to claim 1, characterized in that: The corrosion inhibitor contains sodium molybdate.

4. A method for preparing a chemical polishing solution according to any one of claims 1-3, characterized in that: Includes the following steps: Slowly add sulfuric acid to phosphoric acid and water, allow to mature, and cool to room temperature to obtain an acid solution; Polyferric sulfate, sodium molybdate, and copper sulfate are mixed and dissolved to obtain a mixed solution; The mixture is added to the acid solution and stirred until clear. Then N-methylpyrrolidone is added to obtain a chemical polishing solution.

5. The method for preparing a chemical polishing solution according to claim 4, characterized in that: The phosphoric acid has a purity of ≥85wt%; the sulfuric acid is concentrated sulfuric acid with a purity of ≥98wt%.

6. The method for preparing a chemical polishing solution according to claim 4, characterized in that: During the preparation of the chemical polishing solution, the pH is controlled to be ≥2.

7. The application of a chemical polishing solution, characterized in that, The chemical polishing solution described in claim 1 is used in the preparation of a cleaning solution for a gas diffuser in chemical vapor deposition.

8. The application of the chemical polishing solution according to claim 7, characterized in that, The cleaning of the gas diffuser includes the following steps: The gas diffuser is subjected to degreasing, water washing, alkaline etching, water washing, neutralization, water washing, immersion in chemical polishing solution, and water washing in sequence; the immersion time in the chemical polishing solution is 3 min to 7 min, and the immersion temperature is 80℃ to 100℃.

9. The application of the chemical polishing solution according to claim 8, characterized in that: The degreasing is carried out using an alkaline degreasing agent with a pH value of 8 to 15 at a temperature of 45°C to 65°C. The alkaline etching process uses an alkaline etchant and involves immersing the sample in an alkaline solution at a temperature of 35°C to 55°C for 3 to 15 minutes. The neutralization is performed using a nitric acid solution, soaking for 5 to 20 minutes at a temperature of 25°C to 45°C.

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