A processing method for reducing post-etch particle defects on a wafer

Abstract

This application provides a method for reducing particle defects after wafer etching, comprising: sequentially treating the etched wafer with a first treatment solution, a second treatment solution, and a third treatment solution, followed by rinsing with water and drying; wherein the first treatment solution comprises a hydroxycarboxylic acid complexing agent, an amino acid-based corrosion inhibitor, and water; the second treatment solution comprises a polycarboxylic acid polymer, a surfactant, and water; and the third treatment solution comprises a polycarboxylic acid polymer and water at a concentration lower than that of the second treatment solution. This application reduces particle residue and redeposition on the wafer surface after etching by sequentially weakening particle bridging adsorption, forming a hydrated and dispersed particle state, and performing a low-concentration polycarboxylic acid transition treatment, thereby reducing particle defects after wafer etching.

Description

Technical Field

[0001] This application relates to the field of wafer processing technology, and specifically to a method for reducing particle defects after wafer etching. Background Technology

[0002] Wafer etching is a crucial step in semiconductor device manufacturing, typically used to transfer photolithographic patterns to dielectric, metal, hard mask, or semiconductor material layers. During etching, factors such as plasma bombardment, reaction byproduct generation, consumption of photoresist or mask materials, exposure of metals or inorganic materials, and particle shedding from the equipment cavity can all lead to particle contamination on the wafer surface. If particle residue remains on the wafer surface after etching, it can easily cause pattern defects, localized short circuits or open circuits, abnormal contacts, uneven film deposition, and amplification of defects in subsequent processes.

[0003] The composition of particulate contaminants after etching is usually quite complex, and may include photoresist decomposition products, organic polymer residues, metal particles, metal oxides, inorganic salts, dielectric material fragments, hard mask residues, and microparticles from the etching cavity. Due to the differences in composition, particle size, surface properties, and adhesion states among different types of particulate contaminants, the removal of particulate contaminants after etching is quite challenging.

[0004] Existing post-etching cleaning or post-processing techniques typically employ acidic cleaning solutions, alkaline cleaning solutions, oxidizing cleaning solutions, complexing agents, surfactants, corrosion inhibitors, and ultrapure water rinsing to remove etching residues and particulate contamination. Complexing agents reduce residual metal ions or metal oxides, surfactants improve the wettability of the processing solution, corrosion inhibitors reduce the corrosive effect of the processing solution on the metal layer or sensitive material layer, and ultrapure water rinsing removes processing solution residues and migratable contaminants. While these methods can remove some post-etching particulate contamination, in processes with low particle tolerance, the particle defects on the post-processed wafer remain difficult to consistently reduce.

[0005] Furthermore, existing cleaning systems typically need to simultaneously address requirements such as particle removal, metal residue control, material compatibility, and low chemical residue. If the cleaning or complexing effect of the system is too strong, it may increase the corrosion risk of the metal layer or sensitive material layer; if the dosage of dispersing or wetting components is high, it may increase the difficulty of subsequent removal or introduce organic residue risks; if the treatment system is too mild, it may be insufficient to adequately reduce particle defects. Therefore, existing post-etching treatment methods still face challenges in achieving a balance between particle defect control, material compatibility, and low residue control.

[0006] Therefore, existing wafer etching post-processing methods still need improvement, especially a method that can reduce post-etching particle defects while taking into account material compatibility and low residue requirements. Summary of the Invention

[0007] This application provides a method for reducing particle defects after wafer etching, which solves the problem that existing wafer post-etching processing methods do not sufficiently remove residual particles after etching, resulting in high particle defects on the wafer surface.

[0008] In a first aspect, this application provides a method for reducing particle defects after wafer etching, comprising the following steps: S1: The etched wafer is treated with a first treatment solution, which includes a hydroxycarboxylic acid complexing agent, an amino acid-type corrosion inhibitor and water. The hydroxycarboxylic acid complexing agent reduces the bridging adsorption of metal ions, metal oxides or inorganic salts on the surface of the etched wafer between the particles and the wafer surface, thus obtaining a wafer treated with the first treatment solution. S2: The wafer treated with the first processing solution is treated with a second processing solution, which includes a polycarboxylic acid polymer, a surfactant and water, so that the polycarboxylic acid polymer binds to the surface of the particles on the wafer to form a hydration layer, and the wafer is treated with the second processing solution. S3: The wafer treated with the second processing solution is treated with a third processing solution, which includes a polycarboxylic acid polymer and water. The concentration of the polycarboxylic acid polymer dispersant in the third processing solution is lower than that in the second processing solution. This removes particles from the wafer surface, resulting in a wafer treated with the third processing solution. S4: The wafer treated with the third processing solution is rinsed with water and dried to obtain a low-particle-defect wafer.

[0009] According to this application, by sequentially processing the etched wafer with a first processing solution, a second processing solution, and a third processing solution, the re-attachment and re-deposition of residual particles after etching during post-processing and rinsing can be reduced, thereby reducing particle defects after wafer etching.

[0010] Specifically, the inventors discovered that particle defects on the surface of an etched wafer depend not only on whether the particles can be loosened during the initial cleaning stage, but also on the state changes of the particles during post-processing solution switching, rinsing, and drying. For etched wafers, some particles may form bridged adsorptions with the wafer surface through metal ions, metal oxides, or inorganic salts. If these bridged adsorptions are not effectively weakened, the particles are unlikely to enter a disperseable and carry-away state from the wafer surface. Even after initial loosening, if the surface lacks stable hydration and dispersion, the particles may re-adhere to or deposit on the wafer surface during subsequent water rinsing or drying, resulting in a still high level of particle defects on the final wafer surface.

[0011] Based on the above understanding, this application first uses a first treatment solution comprising a hydroxycarboxylic acid complexing agent and an amino acid-based etching inhibitor to treat the etched wafer. The hydroxycarboxylic acid complexing agent can complex with metal ions, metal oxides, or inorganic salts that may be present on the etched wafer surface, thereby reducing the bridging adsorption formed between the particles and the wafer surface, transforming the originally strongly adhered particles into a state that is more easily loosened or more readily acted upon by the subsequent treatment solution. The amino acid-based etching inhibitor helps to reduce the adverse effects of the first treatment solution on the metal or sensitive material areas of the wafer surface during the bridging adsorption process, keeping the treatment process relatively mild.

[0012] After treatment with the first processing solution, the adhesion of particles to the etched wafer surface is weakened, but the particles are not necessarily completely removed. If water rinsing is performed directly at this point, the loosened particles may re-adhere to the wafer surface due to a lack of stable dispersion. Therefore, this application further employs a second processing solution comprising a polycarboxylate polymer, a surfactant, and water. The polycarboxylate polymer can bind to the particle surface to form a hydration layer, maintaining a better dispersion of the particles in the processing solution and reducing the tendency for particles to re-adhere to the wafer surface. The surfactant can improve the wetting effect of the second processing solution on the wafer surface and the area where the particles are located, allowing the second processing solution to more fully contact the particles loosened by the first processing solution and facilitating the migration of particles from the wafer surface into the processing solution.

[0013] Furthermore, the inventors discovered that while the polycarboxylate polymer and surfactant in the second treatment solution help disperse and carry away particles, if the particles are directly rinsed with water after treatment with the second treatment solution, the dispersion environment around the particles will change significantly, and the established hydration and dispersion state may weaken, posing a risk of particles redepositing on the wafer surface. Based on this, this application employs a third treatment solution after the second treatment solution. The third treatment solution includes a polycarboxylate polymer and water, and the concentration of the polycarboxylate polymer dispersant in the third treatment solution is lower than that in the second treatment solution. Because the third treatment solution still contains polycarboxylate polymer, it can maintain a certain hydration and dispersion state on the particle surface after treatment with the second treatment solution; simultaneously, its lower polycarboxylate polymer concentration facilitates a gradual transition of the wafer surface from a treatment environment with a higher dispersant concentration to a water rinsing environment, reducing the impact of changes in the treatment solution system on the particle dispersion state, thereby reducing the re-attachment or re-deposition of particles during subsequent water rinsing and drying processes.

[0014] Therefore, the first, second, and third processing solutions in this application have a sequential working relationship. The first processing solution is used to weaken the bridging adsorption that may exist between the etched particles and the wafer surface, changing the particles from a strongly adhered state to a loosely movable state. The second processing solution is used to form a hydration layer on the surface of the loosened particles, so that the particles are in a more stable dispersed state. The third processing solution continues this hydration and dispersion state at a lower polycarboxylate polymer concentration and smoothly transitions the particle dispersion environment to the subsequent water rinsing process. Through the above treatment, the re-attachment and re-deposition of particles during the processing and rinsing process after etching can be reduced, thereby reducing particle defects on the final wafer surface.

[0015] In some embodiments, in step S1, the mass concentration of the hydroxycarboxylic acid complexing agent in the first treatment solution is 0.04% to 0.5%, the mass concentration of the amino acid corrosion inhibitor is 0.005% to 0.05%, and the pH is 5.4 to 6.2.

[0016] In some of the above embodiments, by controlling the concentrations of the hydroxycarboxylic acid complexing agent and the amino acid-based corrosion inhibitor, as well as the pH, in the first treatment solution within the aforementioned ranges, it is beneficial to weaken the bridging adsorption formed between the particles and the wafer surface by metal ions, metal oxides, or inorganic salts after etching under relatively mild conditions. If the concentration of the hydroxycarboxylic acid complexing agent is too low, its weakening effect on the metal-related bridging structure is insufficient, and the particles are not easily able to enter the subsequent dispersible state; if the concentration of the hydroxycarboxylic acid complexing agent is too high, it may increase the impact of the treatment solution on the metal or sensitive material areas of the wafer surface. The addition of the amino acid-based corrosion inhibitor helps to reduce the risk of material damage during the first treatment process, enabling the first treatment solution to balance bridging adsorption weakening and treatment mildness. When the pH is controlled at 5.4 to 6.2, the first treatment solution is in the weakly acidic to near-neutral range, which is beneficial for the hydroxycarboxylic acid complexing agent to exert its effect on metal-related residues, while avoiding the risk of excessive corrosion caused by a strongly acidic system.

[0017] In some embodiments, the hydroxycarboxylic acid complexing agent comprises citric acid and gluconic acid, wherein the mass ratio of citric acid to gluconic acid is 1:(1.5 to 2.5).

[0018] In some of the above embodiments, the inventors found that when the hydroxycarboxylic acid complexing agent includes citric acid and gluconic acid, and the mass ratio of citric acid to gluconic acid is 1:(1.5 to 2.5), the particle residue on the wafer surface after etching can be further reduced. The possible reason is that this compounding ratio allows the first processing solution to be better adapted to the step-by-step processing of this application.

[0019] Specifically, the first treatment solution does not forcefully peel off the particles in one go, but rather weakens the bridging adsorption formed between the particles and the wafer surface by metal ions, metal oxides, or inorganic salts. This transforms the particles from a strongly adhered state to a state that is more easily dispersed and stabilized by the subsequent second treatment solution. Citric acid has a strong metal complexing ability, which is beneficial for weakening metal-related bridging adsorption; gluconic acid has a relatively mild complexing effect and good aqueous compatibility, which helps to make the process of regulating metal-related residues around the particles by the first treatment solution more gradual.

[0020] When the mass ratio of citric acid to gluconic acid is 1:(1.5–2.5), the first treatment solution effectively weakens metal-related bridging adsorption without causing excessive disturbance to the metal oxide sites, inorganic salt sites, and local ionic environment on and around the particle surface due to excessive complexation. Therefore, the particle surface treated with the first treatment solution more easily retains a relatively gentle polar environment and surface sites available for polycarboxylic acid polymer adsorption, making it easier for the polycarboxylic acid polymer in the second treatment solution to form a relatively uniform and continuous hydration layer on the particle surface. Simultaneously, it also helps the low concentration of polycarboxylic acid polymer in the third treatment solution to maintain the particle dispersion state, reducing the risk of particle redeposition during subsequent rinsing and drying processes.

[0021] If the proportion of citric acid is too high, the complexing effect of the first treatment solution will be too strong, which may cause metal-related residues to rapidly complex and migrate in the first treatment stage. This will lead to excessively rapid changes in the particle surface and its surrounding environment, which is not conducive to the formation of a stable hydrated dispersion layer of polycarboxylic acid polymers. If the proportion of gluconic acid is too high, the overall complexing effect of the first treatment solution will be too weak, which may result in insufficient weakening of metal-related bridging adsorption, and the particles will still be difficult to fully transform into a dispersible state. Therefore, controlling the mass ratio of citric acid to gluconic acid at 1:(1.5~2.5) is beneficial to achieving a better balance between weakening of bridging adsorption, smooth particle surface state, and subsequent formation of hydrated dispersion layer, thereby further reducing particle defects on the wafer surface.

[0022] In some embodiments, the amino acid-type corrosion inhibitor includes at least one of histidine, cysteine, glycine, and glutamic acid.

[0023] In some of the above embodiments, histidine, cysteine, glycine, and glutamic acid are all water-soluble amino acid compounds, which can provide some protection to the metal or sensitive material areas that may be exposed on the wafer surface during the first treatment process. The combined use of these amino acid corrosion inhibitors with hydroxycarboxylic acid complexing agents helps to reduce the risk of material corrosion or surface damage while weakening metal-related bridging adsorption.

[0024] In some embodiments, in step S2, the mass concentration of the polycarboxylic acid polymer in the second treatment solution is 0.005% to 0.015%, the mass concentration of the surfactant is 0.005% to 0.03%, and the pH is 6.4 to 7.2.

[0025] The concentration of polycarboxylate polymer in the second treatment solution is controlled at 0.005%–0.015%. This facilitates the full binding of the polycarboxylate polymer to the surface of the particles loosened by the first treatment solution, forming a hydration layer and maintaining good dispersion of the particles in the treatment solution. If the polycarboxylate polymer concentration is too low, the hydration and dispersion effect on the particle surface will be insufficient; if the concentration is too high, it may increase the burden on subsequent rinsing. When the surfactant concentration is controlled at 0.005%–0.03%, it can improve the wetting effect of the second treatment solution on the wafer surface and particle-contaminated areas, facilitating the contact and movement of the second treatment solution with the particles loosened by the first treatment solution, while avoiding the risk of foaming or residue caused by excessive surfactant. The pH of the second treatment solution is controlled at 6.4–7.2, which helps maintain the appropriate ionization state of the carboxyl groups in the polycarboxylate polymer, thereby enhancing the hydration and dispersion effect on the particle surface.

[0026] In some embodiments, the polycarboxylic acid polymer includes at least one of polyaspartic acid and polyglutamic acid; the surfactant includes at least one of alkyl glycosides and betaine surfactants.

[0027] In some of the above embodiments, both polyaspartic acid and polyglutamic acid contain multiple carboxyl groups, which can bind to the particle surface and form a hydration layer, thereby improving the dispersion stability of the particles in the second treatment solution. Alkyl glycosides and betaine surfactants have good water solubility and wetting properties, which can improve the contact effect of the treatment solution on the particle-contaminated areas on the wafer surface. The combined use of the above-mentioned polycarboxylic acid polymers and surfactants helps to transform the particles loosened by the first treatment solution into a more stable dispersion state, providing a basis for reducing the risk of redeposition in the subsequent third treatment solution.

[0028] In some embodiments, in step S3, the mass concentration of the polycarboxylate polymer in the third treatment solution is 5% to 15% of that in the second treatment solution.

[0029] In some of the above embodiments, retaining a low concentration of polycarboxylate polymer in the third treatment solution helps maintain a certain hydration and dispersion state on the particle surface after treatment with the second treatment solution. This prevents the particles from re-attaching or depositing on the wafer surface due to rapid changes in the treatment environment before subsequent water rinsing. When the concentration of polycarboxylate polymer in the third treatment solution is 5% to 15% of that in the second treatment solution, it can, on the one hand, continue the particle hydration and dispersion effect formed by the second treatment solution, reducing the tendency for particle redeposition; on the other hand, the concentration of polycarboxylate polymer is significantly lower than that in the second treatment solution, which helps reduce the burden of subsequent water rinsing and reduces the risk of polymer residue. Thus, the third treatment solution can play a good transitional role between maintaining the particle dispersion state and subsequent low-residue rinsing.

[0030] In some embodiments, the polycarboxylic acid polymers in the second and third treatment solutions are both polyaspartic acid with a weight-average molecular weight of 2000-6000 Da.

[0031] In some of the above embodiments, the second and third treatment solutions use the same polycarboxylic acid polymer, which is beneficial for the third treatment solution to maintain the hydration and dispersion state formed by the second treatment solution on the particle surface. Polyaspartic acid has multiple carboxyl groups, which can form a hydration layer on the particle surface, reducing the tendency of particles to re-attach to the wafer surface. Controlling the weight-average molecular weight of polyaspartic acid between 2000 and 6000 Da is beneficial for balancing particle surface adhesion and subsequent rinsing removal: if the molecular weight is too low, the hydration and dispersion provided by the polymer chain segments may be insufficient; if the molecular weight is too high, it can easily increase the system's adhesion and the burden of subsequent rinsing. Using polyaspartic acid within the above molecular weight range allows the second treatment solution to better establish the particle dispersion state and allows the third treatment solution to maintain this state at a lower concentration, thereby reducing particle redeposition during subsequent water rinsing and drying processes.

[0032] In some embodiments, the water in steps S1, S2, S3, and S4 is ultrapure water with a resistivity of not less than 18 MΩ·cm.

[0033] In some of the above embodiments, using ultrapure water with a resistivity of not less than 18 MΩ·cm as the water for preparing the treatment solution and rinsing can reduce secondary contamination of the wafer surface by ionic impurities and particles in the water, which is beneficial to ensuring the stability of particle defect test results and reducing the risk of introducing new particles or ions into the process.

[0034] In some implementations, the following steps are included: S1: Immerse the etched wafer in the first processing solution and process it at 20-40℃ for 30-90 seconds to obtain the wafer treated with the first processing solution. S2: Immerse the wafer treated with the first processing solution in the second processing solution and treat it at 20-40℃ for 30-90 seconds to obtain the wafer treated with the second processing solution. S3: Immerse the wafer treated with the second processing solution in the third processing solution and treat it at 20-40℃ for 30-90 seconds to obtain the wafer treated with the third processing solution. S4: Immerse the wafer treated with the third processing solution in water, treat it at 20-40℃ for 60-150s, and dry it to obtain a low-particle-defect wafer.

[0035] In some of the above embodiments, the immersion treatment method allows the etched wafer to fully contact the various processing solutions. This facilitates the first processing solution to weaken the bridging adsorption between particles and the wafer surface, the second processing solution to form a hydration layer on the particle surface, and the third processing solution to maintain the particle dispersion. The processing temperature for each step is controlled between 20 and 40°C, eliminating the need for high-temperature conditions and ensuring a relatively gentle process. The processing times for the first, second, and third processing solutions are controlled between 30 and 90 seconds, ensuring that each processing solution performs its corresponding function while avoiding excessive processing time that could reduce process efficiency or increase the risk of residue. The water rinsing time is controlled between 60 and 150 seconds, which is beneficial for removing residual third processing solution and particulate contaminants, and, in conjunction with subsequent drying, yields a wafer with low particle defects.

[0036] Compared with the prior art, the beneficial effects of this application are at least as follows: This application sequentially processes the etched wafer with a first processing solution, a second processing solution, and a third processing solution, so that the residual particles after etching undergo bridging adsorption weakening, surface hydration dispersion, and low-concentration polycarboxylic acid treatment processes in sequence, thereby reducing the residue and redeposition of particles on the wafer surface and reducing particle defects after wafer etching.

[0037] The first treatment solution contains a hydroxycarboxylic acid complexing agent that reduces the bridging adsorption of metal ions, metal oxides, or inorganic salts between the particles and the wafer surface, making the strongly attached particles easier to be acted upon by the subsequent treatment solution. The second treatment solution contains a polycarboxylic acid polymer that can bind to the particle surface to form a hydration layer, allowing the particles to maintain a good dispersion state in the treatment solution. The third treatment solution contains a polycarboxylic acid polymer at a lower concentration than the second treatment solution, which can continue to maintain the hydration and dispersion state of the particles before subsequent water rinsing, reducing the tendency of particles to reattach or redeposit.

[0038] Therefore, this application does not simply rely on a single cleaning solution to remove particles, but improves the adequacy of removing residual particles after etching and reduces particle defects on the final wafer surface through the continuous coordination of multiple processing steps. Detailed Implementation

[0039] The various embodiments or implementation schemes in this specification are described in a progressive manner, with each embodiment focusing on the differences from other embodiments.

[0040] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "illustrative embodiment," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with an embodiment or example is included in at least one embodiment or example of this application. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0041] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this application, "multiple" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0042] In this specification, unless otherwise specified, "parts" refers to "parts by weight".

[0043] The following describes embodiments of this application. The embodiments described below are exemplary and are only used to explain this application, and should not be construed as limiting this application. Where specific techniques or conditions are not specified in the embodiments, they are performed according to the techniques or conditions described in the literature in this field or according to the product instructions. Reagents or instruments used, unless otherwise specified, are all conventional products that can be obtained commercially.

[0044] Etched wafers: Silicon wafers from the same batch that have undergone dry etching are selected as wafers to be processed; Polyaspartic acid: with a weight-average molecular weight of 4000 Da, it is used as a polycarboxylic acid polymer; Ultrapure water: resistivity of not less than 18 MΩ·cm at 25℃.

[0045] Example 1 A method for reducing particle defects after wafer etching Preparation of the first treatment solution: Weigh 0.05g citric acid, 0.10g gluconic acid and 0.02g histidine, add them to about 90g ultrapure water and stir until completely dissolved; adjust the pH of the first treatment solution to 5.8, and then weigh it to 100g with ultrapure water to obtain the first treatment solution.

[0046] In the first treatment solution, the mass ratio of citric acid to gluconic acid is 1:2; the total mass concentration of the hydroxycarboxylic acid complexing agent is 0.15%; and the mass concentration of histidine is 0.02%.

[0047] Preparation of the second treatment solution: Weigh 0.010g of polyaspartic acid and 0.015g of alkyl glycoside, add them to about 90g of ultrapure water, and stir until completely dissolved; adjust the pH of the second treatment solution to 6.8, and then weigh it to 100g with ultrapure water to obtain the second treatment solution.

[0048] In the second treatment solution, the mass concentration of polyaspartic acid is 0.01%, and the mass concentration of alkyl glycoside is 0.015%.

[0049] Preparation of the third treatment solution: Weigh 0.001g of polyaspartic acid and add it to approximately 90g of ultrapure water. Stir until completely dissolved. Adjust the pH of the third treatment solution to 6.8 and then weigh it to 100g with ultrapure water to obtain the third treatment solution.

[0050] In the third treatment solution, the mass concentration of polyaspartic acid is 0.001%, which is 10% of the mass concentration of polyaspartic acid in the second treatment solution.

[0051] Wafer processing: The etched wafer is placed in the first processing solution and immersed at 25°C for 60 seconds. After the processing is completed, the wafer is removed, and the wafer treated with the first processing solution is obtained.

[0052] The wafer treated with the first processing solution was placed in the second processing solution and immersed at 25°C for 60 seconds. After the processing was completed, the wafer was removed, and the wafer treated with the second processing solution was obtained.

[0053] The wafer treated with the second processing solution was placed in the third processing solution and immersed at 25°C for 60 seconds. After the processing was completed, the wafer was removed, and the wafer treated with the third processing solution was obtained.

[0054] The wafer treated with the third processing solution was placed in ultrapure water and rinsed at 25°C for 90 seconds to remove processing solution residue and particulate contaminants from the wafer surface. After rinsing, it was dried with nitrogen gas to obtain a wafer with low particle defects.

[0055] Example 2 A method for reducing particle defects after wafer etching It is largely the same as Example 1, except that the first treatment solution is different, specifically: Preparation of the first treatment solution: Weigh 0.075g citric acid, 0.075g gluconic acid and 0.02g histidine, add them to about 90g of ultrapure water and stir until completely dissolved; adjust the pH of the first treatment solution to 5.8, and then weigh it to 100g with ultrapure water to obtain the first treatment solution.

[0056] In the first treatment solution, the mass ratio of citric acid to gluconic acid is 1:1; the total mass concentration of the hydroxycarboxylic acid complexing agent is 0.15%; and the mass concentration of histidine is 0.02%.

[0057] Example 3 A method for reducing particle defects after wafer etching It is largely the same as Example 1, except that the first treatment solution is different, specifically: Preparation of the first treatment solution: Weigh 0.15g of citric acid and 0.02g of histidine, add them to approximately 90g of ultrapure water, and stir until completely dissolved; adjust the pH of the first treatment solution to 5.8, and then weigh it to 100g with ultrapure water to obtain the first treatment solution.

[0058] In the first treatment solution, the total mass concentration of the hydroxycarboxylic acid complexing agent is 0.15%; the mass concentration of histidine is 0.02%.

[0059] Example 4 A method for reducing particle defects after wafer etching It is largely the same as Example 1, except that the first treatment solution is different, specifically: Preparation of the first treatment solution: Weigh 0.15g of gluconic acid and 0.02g of histidine, add them to about 90g of ultrapure water, and stir until completely dissolved; adjust the pH of the first treatment solution to 5.8, and then weigh it to 100g with ultrapure water to obtain the first treatment solution.

[0060] In the first treatment solution, the total mass concentration of the hydroxycarboxylic acid complexing agent is 0.15%; the mass concentration of histidine is 0.02%.

[0061] Comparative Example 1 A method for reducing particle defects after wafer etching Preparation of the first treatment solution: Weigh 0.05g citric acid, 0.10g gluconic acid, 0.010g polyaspartic acid, 0.015g alkyl glycoside and 0.02g histidine, add them to about 90g of ultrapure water and stir until completely dissolved; adjust the pH of the first treatment solution to 5.8, and then weigh it to 100g with ultrapure water to obtain the first treatment solution.

[0062] In the first treatment solution, the mass ratio of citric acid to gluconic acid is 1:2; the total mass concentration of hydroxycarboxylic acid complexing agent is 0.15%; the mass concentration of histidine is 0.02%; the mass concentration of polyaspartic acid is 0.01%; and the mass concentration of alkyl glycoside is 0.015%.

[0063] Wafer processing: The etched wafer is placed in the first processing solution and immersed at 25°C for 120 seconds. After the processing is completed, the wafer is removed, and the wafer treated with the first processing solution is obtained.

[0064] The wafer treated with the first processing solution was placed in ultrapure water and rinsed at 25°C for 90 seconds to remove processing solution residue and particulate contaminants from the wafer surface. After rinsing, it was dried with nitrogen gas to obtain a wafer with low particle defects.

[0065] Comparative Example 2 A method for reducing particle defects after wafer etching Preparation of the first treatment solution: Weigh 0.05g citric acid, 0.10g gluconic acid, 0.010g polyaspartic acid, 0.015g alkyl glycoside and 0.02g histidine, add them to about 90g of ultrapure water and stir until completely dissolved; adjust the pH of the first treatment solution to 5.8, and then weigh it to 100g with ultrapure water to obtain the first treatment solution.

[0066] In the first treatment solution, the mass ratio of citric acid to gluconic acid is 1:2; the total mass concentration of hydroxycarboxylic acid complexing agent is 0.15%; the mass concentration of histidine is 0.02%; the mass concentration of polyaspartic acid is 0.01%; and the mass concentration of alkyl glycoside is 0.015%.

[0067] Preparation of the second treatment solution: Weigh 0.001g of polyaspartic acid and add it to approximately 90g of ultrapure water. Stir until completely dissolved. Adjust the pH of the second treatment solution to 6.8 and then weigh it to 100g with ultrapure water to obtain the second treatment solution.

[0068] In the third treatment solution, the mass concentration of polyaspartic acid is 0.001%, which is 10% of the mass concentration of polyaspartic acid in the first treatment solution.

[0069] Wafer processing: The etched wafer is placed in the first processing solution and immersed at 25°C for 120 seconds. After the processing is completed, the wafer is removed, and the wafer treated with the first processing solution is obtained.

[0070] The wafer treated with the first processing solution was placed in the second processing solution and immersed at 25°C for 60 seconds. After the processing was completed, the wafer was removed, and the wafer treated with the second processing solution was obtained.

[0071] The wafer treated with the second processing solution was placed in ultrapure water and rinsed at 25°C for 90 seconds to remove processing solution residue and particulate contaminants from the wafer surface. After rinsing, it was dried with nitrogen gas to obtain a wafer with low particle defects.

[0072] Comparative Example 3 Preparation of the first treatment solution: Weigh 0.05g citric acid, 0.10g gluconic acid and 0.02g histidine, add them to about 90g ultrapure water and stir until completely dissolved; adjust the pH of the first treatment solution to 5.8, and then weigh it to 100g with ultrapure water to obtain the first treatment solution.

[0073] In the first treatment solution, the mass ratio of citric acid to gluconic acid is 1:2; the total mass concentration of the hydroxycarboxylic acid complexing agent is 0.15%; and the mass concentration of histidine is 0.02%.

[0074] Preparation of the second treatment solution: Weigh 0.010g of polyaspartic acid and 0.015g of alkyl glycoside, add them to about 90g of ultrapure water, and stir until completely dissolved; adjust the pH of the second treatment solution to 6.8, and then weigh it to 100g with ultrapure water to obtain the second treatment solution.

[0075] In the second treatment solution, the mass concentration of polyaspartic acid is 0.01%, and the mass concentration of alkyl glycoside is 0.015%.

[0076] Wafer processing: The etched wafer is placed in the first processing solution and immersed at 25°C for 60 seconds. After the processing is completed, the wafer is removed, and the wafer treated with the first processing solution is obtained.

[0077] The wafer treated with the first processing solution was placed in the second processing solution and immersed at 25°C for 60 seconds. After the processing was completed, the wafer was removed, and the wafer treated with the second processing solution was obtained.

[0078] The wafer treated with the second processing solution was placed in ultrapure water and rinsed at 25°C for 90 seconds to remove processing solution residue and particulate contaminants from the wafer surface. After rinsing, it was dried with nitrogen gas to obtain a wafer with low particle defects.

[0079] Test section Particulate Residue Test Method The wafers processed in the examples and comparative examples were used as test samples. Before testing, the wafers were placed in a clean environment and left to stand for 5 minutes to avoid external dust affecting the test results. A laser scattering wafer surface defect detector was used to detect particles on the wafer surface. The particle size threshold was set to be no less than 0.1 μm, and the scanning area was the effective area on the front side of the wafer.

[0080] During testing, the wafer to be tested was placed on the testing stage, and the entire wafer surface was scanned according to the equipment's preset program. The number of particles detected on the wafer surface was recorded. The results are shown in Table 1.

[0081] Table 1 According to Table 1, Examples 1-4 all exhibit a lower number of residual particles on the wafer surface compared to Comparative Examples 1-3, indicating that the segmented processing method provided in this application can effectively reduce residual particles on the wafer surface after etching, thereby reducing particle defects after wafer etching. The possible reason is that this application sequentially uses a first processing solution, a second processing solution, and a third processing solution, causing the residual particles after etching to undergo bridging adsorption weakening, surface hydration dispersion, and low-concentration polycarboxylate transition treatment in sequence, thereby reducing particle residue and subsequent redeposition.

[0082] In Comparative Example 1, the wafer was treated with a mixture of hydroxycarboxylic acid complexing agent, polyaspartic acid, alkyl glycoside, and histidine in the same treatment solution. After treatment, it was directly rinsed with water. The number of residual particles on the wafer surface was 248 per wafer, which was higher than in the examples, indicating that the blending treatment could not fully exert the continuous effect of the segmented treatment. In Comparative Example 2, although a low-concentration polyaspartic acid treatment was used after the blending treatment, the number of residual particles on the wafer surface was reduced to 226 per wafer, but it was still higher than in the examples. This indicates that the improvement effect of low-concentration polycarboxylic acid treatment is limited when the preceding treatment has not sufficiently established the hydration and dispersion of particles. In Comparative Example 3, the wafer was directly rinsed with water after treatment with the first and second treatment solutions without the third treatment solution. The number of residual particles on the wafer surface was 164 per wafer, which was higher than in the examples. This indicates that the third treatment solution can play a transitional role between the second treatment solution and water rinsing, which is beneficial to reduce the redeposition of particles during rinsing and drying.

[0083] As shown in Examples 1-4, the type and ratio of the hydroxycarboxylic acid complexing agent in the first treatment solution have a certain impact on the number of residual particles on the wafer surface. Under the same conditions of the second and third treatment solutions and processing conditions, Example 1 used a mixture of citric acid and gluconic acid at a mass ratio of 1:2 as the hydroxycarboxylic acid complexing agent, resulting in a wafer surface particle count of 86 particles / wafer, lower than in Examples 2-4. This indicates that when using a certain proportion of citric acid and gluconic acid as the hydroxycarboxylic acid complexing agent, the first treatment solution is more suitable for the segmented processing of this application, and can further improve the reduction effect of residual particles on the wafer surface after etching.

[0084] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application.

Claims

1. A method for reducing particle defects after wafer etching, characterized in that, Includes the following steps: S1: The etched wafer is treated with a first treatment solution, which includes a hydroxycarboxylic acid complexing agent, an amino acid-type corrosion inhibitor and water. The hydroxycarboxylic acid complexing agent reduces the bridging adsorption of metal ions, metal oxides or inorganic salts on the surface of the etched wafer between the particles and the wafer surface, thus obtaining a wafer treated with the first treatment solution. S2: The wafer treated with the first processing solution is treated with a second processing solution, which includes a polycarboxylic acid polymer, a surfactant and water, so that the polycarboxylic acid polymer binds to the surface of the particles on the wafer to form a hydration layer, and the wafer is treated with the second processing solution. S3: The wafer treated with the second processing solution is treated with a third processing solution, which includes a polycarboxylic acid polymer and water. The concentration of the polycarboxylic acid polymer dispersant in the third processing solution is lower than that in the second processing solution. This removes particles from the wafer surface, resulting in a wafer treated with the third processing solution. S4: The wafer treated with the third processing solution is rinsed with water and dried to obtain a low-particle-defect wafer.

2. The processing method according to claim 1, characterized in that, In step S1, the mass concentration of the hydroxycarboxylic acid complexing agent in the first treatment solution is 0.04% to 0.5%, the mass concentration of the amino acid corrosion inhibitor is 0.005% to 0.05%, and the pH is 5.4 to 6.

2.

3. The processing method according to claim 2, characterized in that, The hydroxycarboxylic acid complexing agent includes citric acid and gluconic acid, wherein the mass ratio of citric acid to gluconic acid is 1:(1.5-2.5).

4. The processing method according to claim 2, characterized in that, The amino acid-based corrosion inhibitor includes at least one of histidine, cysteine, glycine, and glutamic acid.

5. The processing method according to claim 1, characterized in that, In step S2, the mass concentration of the polycarboxylic acid polymer in the second treatment solution is 0.005% to 0.015%, the mass concentration of the surfactant is 0.005% to 0.03%, and the pH is 6.4 to 7.

2.

6. The processing method according to claim 5, characterized in that, The polycarboxylic acid polymer includes at least one of polyaspartic acid and polyglutamic acid; the surfactant includes at least one of alkyl glycosides and betaine surfactants.

7. The processing method according to claim 1, characterized in that, In step S3, the mass concentration of the polycarboxylic acid polymer in the third treatment solution is 5% to 15% of that in the second treatment solution.

8. The processing method according to claim 1, characterized in that, The polycarboxylic acid polymers in the second and third treatment solutions are both polyaspartic acid with a weight-average molecular weight of 2000-6000 Da.

9. The processing method according to claim 1, characterized in that, In steps S1, S2, S3, and S4, the water used is ultrapure water with a resistivity of not less than 18 MΩ·cm.

10. The processing method according to any one of claims 1 to 9, characterized in that, Includes the following steps: S1: Immerse the etched wafer in the first processing solution and process it at 20-40℃ for 30-90 seconds to obtain the wafer treated with the first processing solution. S2: Immerse the wafer treated with the first processing solution in the second processing solution and treat it at 20-40℃ for 30-90 seconds to obtain the wafer treated with the second processing solution. S3: Immerse the wafer treated with the second processing solution in the third processing solution and treat it at 20-40℃ for 30-90 seconds to obtain the wafer treated with the third processing solution. S4: Immerse the wafer treated with the third processing solution in water, treat it at 20-40℃ for 60-150s, and dry it to obtain a low-particle-defect wafer.

Images