Chip cleaning agent and production method thereof
By forming a complexing system under near-neutral conditions using tartaric acid complexing agents and pH-adjusting components, combined with a brushing process, the problem of difficult removal of copper oxide residues is solved, achieving efficient cleaning and protection of copper surfaces and reducing cleaning defects and corrosion risks.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- JUFENGTAI TECHNOLOGY (DONGGUAN) CO LTD
- Filing Date
- 2026-01-31
- Publication Date
- 2026-05-08
AI Technical Summary
In the copper interconnect process of integrated circuit chips, existing technologies are difficult to effectively remove copper oxide residues after chemical mechanical planarization, and strong acid and alkali cleaning can easily cause corrosion. It is difficult to achieve both decontamination and low damage by relying solely on chemical or brushing methods.
A complexing system is formed under near-neutral conditions using tartaric acid complexing agents and pH adjusting components. Combined with a brushing process, the copper oxide is dissolved by complexation and copper dissolution is inhibited. A polyvinyl alcohol brush is then used for dynamic brushing to achieve thorough cleaning of the copper surface.
It efficiently removes copper oxide residues under mild conditions, inhibits excessive copper dissolution and redeposition, reduces cleaning defects, and balances cleaning efficiency with environmental friendliness.
Smart Images
Figure CN121991771A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of cleaning agent technology, and in particular to a chip cleaning agent and its production method. Background Technology
[0002] In the copper interconnect process of integrated circuit chips, post-cleaning after chemical mechanical planarization is used to remove residues on the copper surface to avoid affecting subsequent processes and device reliability. Existing post-cleaning formulations and research mainly focus on the removal of abrasive particles and organic residues, while relatively little attention is paid to copper oxide residues (and the complex residues formed by their co-adsorption with organic inhibitors / complexing agents) that are easily introduced or amplified during the post-cleaning process and can induce secondary defects. At the same time, the synergistic mechanism between mechanical brushing (such as polyvinyl alcohol brushing) and solution chemistry in post-cleaning is complex. Conventional electrochemical evaluations conducted only under brushless conditions are difficult to reflect the decontamination behavior and redeposition risk of the actual brushing cleaning interface, resulting in biases in formulation selection and mechanism determination. Summary of the Invention
[0003] In view of the above technical problems, the present invention provides a chip cleaning agent and its production method, aiming to solve the problems that residual oxides and their co-adsorbed residues on copper surfaces are difficult to remove efficiently under mild conditions, strong acid and strong alkali cleaning is prone to corrosion / defects, and chemical or brushing alone is difficult to achieve both decontamination and low damage. The present invention provides a chip cleaning agent and its production method that still has the ability to remove oxides under near-neutral conditions and can inhibit copper dissolution and redeposition, and adapts it to brushing cleaning scenarios to obtain a more stable comprehensive cleaning effect.
[0004] Other features and advantages of this disclosure will become apparent from the following detailed description, or may be learned in part from practice of this disclosure.
[0005] According to one aspect of the present invention, a chip cleaning agent is provided, which is an aqueous cleaning agent for cleaning copper-containing chip surfaces after chemical mechanical planarization, the chip cleaning agent comprising: a tartaric acid complexing agent and a pH adjusting component; wherein: The tartaric acid complexing agent is a complexing agent containing tartaric acid and tartrate salts that can provide tartrate ions in an aqueous system; the pH adjustment component is used to adjust the chip cleaning agent to a near-neutral working pH, which is a pH range in which the tartaric acid complexing agent is mainly in the form of deprotonated tartrate ions and can achieve complex dissolution of copper oxides without relying on strong acid or strong base conditions, while inhibiting the spontaneous dissolution of substrate copper. The tartrate ions are configured to complex with copper ions dissolved or migrated to the liquid phase during the cleaning process to form soluble copper. Tartaric acid complexes are used to inhibit the hydrolytic deposition of copper ions on the surface of the copper-containing chip and reduce the secondary formation of copper oxides; tartaric acid complexes are also used to react with residual copper oxides on the surface of the copper-containing chip, converting the residual copper oxides into soluble complexes that are carried away by the liquid phase; and the tartaric acid ions can be adsorbed on the surface of the copper-containing chip to form an adsorption layer, thereby inhibiting the excessive dissolution of the substrate copper and reducing the copper oxide concentration during the cleaning process. The redeposition of tartaric acid complexes on the surface of the copper-containing chip.
[0006] Furthermore, the tartaric acid complexing agent includes tartaric acid, a racemic mixture of tartaric acid, an enantiomer of tartaric acid, a tartrate salt, or a combination thereof, wherein the tartrate salt is selected from ammonium salts, alkali metal salts, organic amine salts, or a combination thereof, so that the tartaric acid complexing agent provides multidentate coordinated tartrate ions at the near-neutral working pH and forms a complex capable of stabilizing copper ions.
[0007] Furthermore, the pH adjusting component is an alkaline adjusting component, which is selected from ammonium hydroxide, ammonia, alkali metal hydroxide, alkali metal carbonate, buffer amine or a combination thereof. The alkaline adjusting component is used to adjust and maintain the pH of the chip cleaning agent at the near-neutral working pH so that the tartrate ions remain in a deprotonated state and continuously provide complexation ability for copper ions during the cleaning process.
[0008] Furthermore, the chip cleaning agent is configured to remove residues formed and remaining on the surface of the copper-containing chip during the chemical mechanical planarization process, the residues including at least one of cuprous oxide and copper oxide, and surface complexes or adsorption films co-adsorbed with at least one of cuprous oxide and copper oxide. The surface complex or the adsorption film comprises copper formed from a nitrogen-containing heterocyclic corrosion inhibitor. Inhibitor complexes, copper formed by amino acid complexing agents Amino acid complexes, and combinations thereof, enable the chip cleaning agent to synergistically remove the surface complexes or the adsorbed film by preferentially complexing and dissolving at least one of the cuprous oxide and the copper oxide, and reduce its surface masking effect on subsequent processes.
[0009] Furthermore, the chip cleaning agent is used in conjunction with a brushing process, which employs a polyvinyl alcohol brush or a porous elastic polymer brush to dynamically brush the surface of the copper-containing chip, thereby creating localized hydrodynamic shearing and friction between the brush bristles and the surface of the copper-containing chip; under this dynamic brushing action, the copper... The tartaric acid complex and the adsorption layer exist in a weak adsorption state and are mechanically peeled off and carried away with the liquid phase, so that the copper-containing chip surface can achieve a residue removal effect in the brushing area and its adjacent area.
[0010] According to a second aspect of this disclosure, a method for producing a chip cleaning agent is provided. The chip cleaning agent is an aqueous cleaning agent used for cleaning copper-containing chip surfaces after chemical mechanical planarization, and the chip cleaning agent includes at least a tartaric acid complexing agent and a pH adjusting component. The production method includes: Water is provided as a solvent; The tartaric acid complexing agent is added to the solvent and mixed to dissolve the tartaric acid complexing agent to obtain a tartaric acid solution. The pH adjusting component is added to the tartaric acid solution and adjusted to a near-neutral working pH, so that the tartaric acid complexing agent forms a complexing system in the tartaric acid solution with tartrate ions as the main form. The adjusted solution is purified to remove particles and insoluble matter; and the purified solution is sealed and packaged to obtain the chip cleaning agent.
[0011] Furthermore, in the step of providing water as a solvent, the water is deionized water, distilled water, or water that has undergone multi-stage purification; the step of adding the tartaric acid complexing agent to the solvent and mixing includes at least one of stirring, circulating mixing, or ultrasonic dispersion until the tartaric acid complexing agent forms a homogeneous solution in the solvent; the step of adding the pH adjusting component and adjusting it to the near-neutral working pH includes adding the pH adjusting component gradually while simultaneously monitoring pH changes, so that the tartaric acid complexing agent in the resulting solution is mainly in the form of tartrate ions and forms the complexing system.
[0012] Furthermore, the purification process includes filtration to remove particles and insoluble matter, the filtration including at least one of membrane filtration, microfiltration, or depth filtration, to reduce secondary defects caused by particulate contamination introduced during the use of the chip cleaning agent.
[0013] Furthermore, the sealed packaging includes dispensing the chip cleaning agent into a sealed packaging container in a clean environment and labeling it. The sealed packaging container is a polymer material container or an inert metal material container that is chemically inert to the chip cleaning agent. The label includes that the chip cleaning agent is applicable to copper-containing chip surfaces after chemical mechanical planarization and that the applicable process is at least one of static immersion cleaning and dynamic brush cleaning.
[0014] The technical solution disclosed herein has the following beneficial effects: A chip cleaning agent system based on tartaric acid / tartrate salts is adopted. In a near-neutral aqueous environment, copper ions are complexed and stabilized to form a reversible adsorption layer on the copper surface. This achieves the dissolution and removal of copper oxide residues while inhibiting excessive dissolution and corrosion defects of the substrate copper. Furthermore, when the cleaning agent is combined with brushing / hydrodynamic action, it can more thoroughly remove the complexed weakly adsorbed residues and their co-adsorbed organic residues from the surface, reducing the probability of redeposition under closed or localized retention conditions. This results in a smoother and more uniform copper surface after cleaning, balancing cleaning efficiency, defect control, and environmental friendliness. Attached Figure Description
[0015] Figure 1 This is a flowchart of a chip cleaning agent production method according to an embodiment of this specification. Detailed Implementation
[0016] Example embodiments will now be described more fully with reference to the accompanying drawings. However, example embodiments can be implemented in many forms and should not be construed as limited to the examples set forth herein; rather, these embodiments are provided to make this disclosure more comprehensive and complete, and to fully convey the concept of example embodiments to those skilled in the art. The described features, structures, or characteristics may be combined in any suitable manner in one or more embodiments. In the following description, numerous specific details are provided to give a full understanding of embodiments of this disclosure. However, those skilled in the art will recognize that the technical solutions of this disclosure may be practiced with one or more of these specific details omitted. In other instances, well-known technical solutions are not shown or described in detail to avoid obscuring various aspects of this disclosure.
[0017] Furthermore, the accompanying drawings are merely illustrative of this disclosure. The same reference numerals in the drawings denote the same or similar parts, and therefore, repeated descriptions of them will be omitted.
[0018] A chip cleaning agent, an aqueous cleaning agent for cleaning copper-containing chip surfaces after chemical mechanical planarization, comprises: a tartaric acid complexing agent and a pH adjusting component; wherein: Tartaric acid complexing agents are complexing agents containing tartaric acid and tartrate salts that can provide tartrate ions in aqueous systems; pH adjustment components are used to adjust the chip cleaning agent to a near-neutral working pH. The near-neutral working pH is the pH range in which the tartaric acid complexing agent is mainly in the form of deprotonated tartrate ions, and achieves complexation and dissolution of copper oxides without relying on strong acid or strong base conditions, while inhibiting the spontaneous dissolution of substrate copper. Tartrate ions are configured to complex with copper ions dissolved or migrated to the liquid phase during the cleaning process to form soluble copper. Tartaric acid complexes are used to inhibit the hydrolytic deposition of copper ions on the surface of copper-containing chips and reduce the secondary formation of copper oxides; they also undergo a complexation and dissolution reaction with residual copper oxides on the surface of copper-containing chips, converting the residual copper oxides into soluble complexes that are carried away by the liquid phase; furthermore, tartrate ions can adsorb onto the surface of copper-containing chips to form an adsorption layer, thereby inhibiting excessive dissolution of the substrate copper and reducing copper oxide concentration during the cleaning process. Redeposition of tartaric acid complexes on the surface of copper-containing chips.
[0019] Near-neutral working pH refers to the pH range within which tartaric acid complexing agents exist primarily in the form of deprotonated tartrate ions, capable of complexing and dissolving copper oxides while inhibiting the spontaneous dissolution of the substrate copper, without the need for strong acids or bases. During the cleaning process, tartrate ions play a crucial role: they complex with copper ions dissolved or migrating to the liquid phase during cleaning, forming soluble copper-tartaric acid complexes, preventing hydrolytic deposition of these copper ions on the copper-containing chip surface and reducing the secondary formation of copper oxides; they also complex and dissolve residual copper oxides (such as cuprous oxide and copper oxide) on the copper-containing chip surface, converting solid copper oxides into soluble complexes that are carried away by the cleaning solution; simultaneously, tartrate ions can adsorb onto the copper-containing chip surface, forming an adsorption layer that inhibits excessive dissolution of the substrate copper during cleaning and reduces the re-deposition of the already formed copper-tartaric acid complexes on the copper-containing chip surface. Through the above-described effects, the chip cleaning agent of this embodiment effectively removes oxides and metal ion residues from the copper surface while maintaining a mild and near-neutral condition, thus protecting the substrate copper from corrosion.
[0020] In one embodiment, the tartaric acid complexing agent includes tartaric acid, a racemic mixture of tartaric acid, an enantiomer of tartaric acid, a tartrate salt, or a combination thereof, wherein the tartrate salt is selected from ammonium salts, alkali metal salts, organic amine salts, or a combination thereof, so that the tartaric acid complexing agent provides multidentate coordinated tartrate ions at a near-neutral working pH and forms a complex capable of stabilizing copper ions.
[0021] The tartaric acid complexing agent used in the chip cleaning agent can include tartaric acid and its various forms. For example, the complexing agent can be tartaric acid itself, a racemic mixture of tartaric acid (a racemic mixture of tartaric acid containing equal proportions of levorotatory and dextrorotatory tartaric acid), an enantiomer of tartaric acid (optically pure levorotatory or dextrorotatory tartaric acid), and tartrate salts or combinations thereof. The tartrate salt can be selected from ammonium salts (such as ammonium tartrate), alkali metal salts (such as sodium tartrate, potassium tartrate, etc.), organic amine salts (salts formed by tartaric acid and organic amines), or combinations thereof. Using any of the above-mentioned forms of tartaric acid complexing agents can provide multidentate coordinated tartrate ions at near-neutral working pH and form stable complexes with copper ions. This means that regardless of the form of tartaric acid used, under near-neutral conditions, the tartrate anions can be fully released to complex copper ions, thereby ensuring the cleaning agent's complexing ability and stability towards copper ions.
[0022] In one embodiment, the pH adjusting component of the chip cleaning agent is an alkaline adjuster to adjust and maintain the solution within a near-neutral working pH range. This alkaline pH adjusting component can be selected from various common bases, such as ammonium hydroxide, ammonia (an aqueous solution containing ammonia), alkali metal hydroxides (e.g., sodium hydroxide, potassium hydroxide), alkali metal carbonates (e.g., sodium carbonate, potassium carbonate), and buffer amines, or combinations thereof. By adding the above-mentioned alkaline component, the acidity in the solution can be effectively neutralized, maintaining the pH of the cleaning agent at a near-neutral level (e.g., around 6-8). Within this pH range, tartrate ions remain in a deprotonated state, thus continuously providing complexation capacity for copper ions during the cleaning process. Simultaneously, maintaining a near-neutral pH avoids the use of strong acids or strong bases, resulting in better material compatibility with the chip surface and reducing the risk of corrosion to the environment and equipment.
[0023] In one embodiment, the chip cleaning agent is configured to remove residues formed and remaining on the surface of a copper-containing chip during the chemical mechanical planarization process, the residues including at least one of cuprous oxide and copper oxide, and surface complexes or adsorption films co-adsorbed with at least one of cuprous oxide and copper oxide. Surface complexes or adsorbed films include copper formed from nitrogen-containing heterocyclic corrosion inhibitors. Inhibitor complexes, copper formed by amino acid complexing agents Amino acid complexes, and combinations thereof, enable chip cleaning agents to synergistically remove surface complexes or adsorbed films by preferentially complexing and dissolving at least one of cuprous oxide and copper oxide, and reduce their surface masking effect on subsequent processes.
[0024] After chemical mechanical planarization (CMP) processes, various residues often remain on the surface of copper-containing chips. The chip cleaning agent of this embodiment is formulated to effectively remove these residues. These residues mainly include monovalent and divalent copper oxides, namely cuprous oxide and copper oxide (at least one of which is present), as well as certain complexes or adsorbed films co-adsorbed on the surface with these oxides. These surface complexes or adsorbed films may originate from corrosion inhibitors added to the polishing solution, such as "copper-corrosion inhibitor" complexes formed by nitrogen-containing heterocyclic corrosion inhibitors (e.g., a complexed protective layer formed on the copper surface by nitrogen-containing heterocyclic compounds such as benzotriazole), or "copper-amino acid" complexes formed by amino acid-based complexing agents. These complexes adhering to the copper surface can cause surface masking effects in subsequent processes, affecting the efficiency of cleaning and processing. Using the chip cleaning agent of this embodiment, the aforementioned cuprous oxide and / or copper oxide residues can be preferentially complexed and dissolved. This selective dissolution of copper oxides removes the copper-corrosion inhibitor complexes and copper-amino acid complexes adhering to them from the surface, achieving a synergistic removal effect and significantly reducing the interference of residual complexes or adsorbed films on subsequent processes.
[0025] In one embodiment, the chip cleaning agent is used in conjunction with a brushing process, which employs a polyvinyl alcohol brush or a porous elastic polymer brush to dynamically brush the surface of the copper-containing chip, thereby creating localized hydrodynamic shearing and friction between the brush bristles and the copper-containing chip surface; under the dynamic brushing action, the copper... Tartaric acid complexes and adsorption layers exist in a weakly adsorbed state and are mechanically peeled off and carried away with the liquid phase, so that the copper-containing chip surface can achieve a residue removal effect in the brushing area and its adjacent area.
[0026] In the dynamic brushing cleaning process, brushes made of materials such as polyvinyl alcohol (PVA) or porous elastic polymers are used to mechanically scrub the surface of the copper-containing chip. When the brush bristles move in contact with the chip surface, hydrodynamic shear forces and friction are generated locally. This mechanical action, combined with the chemical action of the cleaning agent, keeps the copper-tartaric acid complex and the aforementioned protective layer adsorbed on the surface in a weakly adsorbed state. In other words, when brushing is performed, these complexes and adsorbed films are easily agitated and peeled off. Once detached from the surface, they are immediately carried away by the cleaning solution. Through the combined action of brushing and the cleaning solution, the brushed area and adjacent areas of the copper-containing chip surface are thoroughly cleaned, and there are no longer obvious oxides and organic complex residues on the surface, thus providing a clean copper surface for subsequent processes.
[0027] In one implementation, such as Figure 1As shown, a method for producing a chip cleaning agent is provided. The chip cleaning agent is an aqueous cleaning agent used for cleaning the surface of copper-containing chips after chemical mechanical planarization, and the chip cleaning agent includes at least a tartaric acid complexing agent and a pH adjusting component. The production method includes steps S1-S4: In step S1, water is provided as a solvent; In step S2, a tartaric acid complexing agent is added to the solvent and mixed to dissolve the tartaric acid complexing agent and obtain a tartaric acid solution. In step S3, a pH adjustment component is added to the tartaric acid solution and adjusted to a near-neutral working pH, so that the tartaric acid complexing agent forms a complexing system in the tartaric acid solution with tartrate ions as the main form. In step S4, the adjusted solution is purified to remove particles and insoluble matter; and the purified solution is sealed and packaged to obtain the chip cleaning agent.
[0028] The step of providing water as a solvent involves using deionized water, distilled water, or water that has undergone multi-stage purification. The step of adding tartaric acid complexing agents to the solvent and mixing includes at least one of stirring, circulating mixing, or ultrasonic dispersion until the tartaric acid complexing agent forms a homogeneous solution in the solvent. The step of adding pH adjustment components and adjusting to a near-neutral working pH includes adding the pH adjustment components gradually while simultaneously monitoring pH changes, so that the tartaric acid complexing agent in the resulting solution is mainly in the form of tartrate ions and forms a complex system.
[0029] The purification process includes filtration to remove particles and insoluble matter. The filtration includes at least one of membrane filtration, microfiltration, or depth filtration to reduce secondary defects caused by particulate contamination introduced during the use of the chip cleaning agent.
[0030] The sealed packaging includes dispensing the chip cleaning agent into sealed packaging containers in a clean environment and labeling them. The sealed packaging containers are made of polymer materials or inert metal materials that are chemically inert to the chip cleaning agent. The labeling includes that the chip cleaning agent is applicable to copper-containing chip surfaces after chemical mechanical planarization and that the applicable process is at least one of static immersion cleaning and dynamic brush cleaning.
[0031] In summary, this chip cleaning agent is used for cleaning the surface of copper-containing chips after chemical mechanical planarization, and contains at least a tartaric acid complexing agent and a pH adjusting component. The production method includes the following steps: First, water is provided as a solvent. The water used can be deionized water, distilled water, or pure water that has undergone multi-stage purification to ensure the purity of the solvent. Then, the tartaric acid complexing agent is added to the solvent and mixed until the tartaric acid complexing agent is completely dissolved to form a homogeneous tartaric acid solution. During the mixing process, one or more methods such as stirring, circulating mixing, or ultrasonic dispersion can be used to accelerate dissolution and ensure the homogeneity of the solution. Next, the pH adjusting component is gradually added to the obtained tartaric acid solution, while simultaneously monitoring the pH change of the solution, and slowly adjusting it to a near-neutral working pH range. By gradually adding the alkaline pH adjusting agent, it is ensured that the tartaric acid complexing agent exists mainly in the form of tartrate ions in the solution, thereby forming a complex system with tartrate ions as the main ligands. Subsequently, the pH-adjusted solution is purified to remove any particles and insoluble matter that may be present. Purification can be achieved through filtration methods such as membrane filtration, microfiltration, or depth filtration to effectively trap particulate impurities and reduce the risk of secondary defects caused by particulate contamination during chip cleaning agent use. Finally, the purified solution is dispensed into chemically inert, sealed containers in a clean environment and stored. The containers can be made of polymer materials or inert metals that do not absorb or dissolve the solution, preventing changes in composition or contamination of the cleaning agent during storage. Labels or markings should be affixed to the containers, indicating the applicable objects and processes for the chip cleaning agent, such as its suitability for cleaning copper-containing chip surfaces after chemical mechanical planarization, and its applicability to static immersion cleaning or dynamic brushing cleaning processes. By following these steps, a stable and effective chip cleaning agent product can be obtained.
[0032] In a pilot implementation, triple-distilled water was used as the solvent, and reagent-grade chemicals with a purity of 95% were selected to prepare the cleaning solution system. The aim was to obtain an aqueous chip cleaner for cleaning copper-containing chip surfaces after chemical mechanical planarization, enabling it to synergistically remove copper oxides and protect the copper substrate in a near-neutral environment. First, the post-cleaning solution was prepared by dissolving DL-tartaric acid (TA) in water as a tartaric acid complexing agent. DL-tartaric acid has the molecular formula C4H6O6, the acid formula H2T, and pKa values of 2.89 and 4.40. After TA dissolved, ammonium hydroxide was used as a pH adjusting component to adjust the solution to a pH of 6.99, thus obtaining a near-neutral TA aqueous cleaning solution. This TA cleaning solution is used as a post-cleaning solution after chemical mechanical planarization (CMP). Under these pH conditions, TA can undergo deprotonation and participate in the complexation and dissolution of copper ions and copper oxide residues in its deprotonated form. Simultaneously, the near-neutral environment reduces the risk of corrosion defects that may be caused by strong acid or alkali cleaning. Furthermore, the deprotonated form of TA in solution can stabilize copper ions in the solution through multidentate coordination, reducing the tendency for copper ion redeposition and secondary oxide formation on the surface, thus achieving a balance between oxide removal and inhibition of excessive dissolution of the substrate copper. As a probe electrolyte for evaluating the post-cleaning effect, a pH-neutral detection solution was further prepared. The detection solution was a 0.1 MkNO3 aqueous solution, with the pH adjusted to 7.00 using KOH. This detection solution was used to determine the residual removal efficiency (RRE) in subsequent evaluations. This ensured that the detection solution was electrochemically non-reactive to CMP residues and only weakly reactive to the cleaned copper surface, thereby reflecting changes in residual coverage through differences in polarization resistance. CMP refers to chemical mechanical planarization, which involves smoothing the wafer / chip surface and removing excess metal or dielectric layers to achieve the desired surface flatness. The components and conditions of the above cleaning and evaluation system include: the cleaning solution after chemical mechanical planarization contains 0.1 MDL-TA and is adjusted to pH 6.99 with ammonium hydroxide; the detection solution is 0.1 MkNO3 and is adjusted to pH 7.00 with KOH.
[0033] To ensure the post-cleaning surface exhibits typical CMP residue characteristics, a CMP pretreatment was performed to generate copper oxides and their co-adsorbed residues. The CMP pretreatment employed a non-abrasive system to highlight the formation and removal mechanisms of the oxides and co-adsorbates. Copper samples were immersed in a CMP solution at pH 6 for 1 min, followed by rinsing with distilled water and drying. The CMP solution contained H2O2 as an oxidant, glycine as a surface modifier, and benzotriazole as a dissolution inhibitor, specifically composed of 0.01 wt.% H2O2, 1 mM BTA, and 0.1 wt.% H2O2. The H2O2 content was kept low to reduce the likelihood of H2O2-related surface defects. This non-abrasive formulation was used to form representative oxide / co-adsorbed residues without introducing a cumulative abrasive removal effect, facilitating observation of post-cleaning removal behavior.
[0034] In CMP solution, the oxidation of H2O2 is associated with an electrochemical reduction process. The cathodic electroreduction reaction of H2O2 is: H2O2 + 2e- +2H+=2H2O. This cathode process is coupled with the anodic oxidation step of copper, and the oxidation of copper can produce cuprous oxide and copper oxide through the following reaction: 2Cu + H₂O = Cu₂O + 2H⁺ + 2e⁻; Cu₂O + H₂O = 2CuO + 2H⁺ + 2e⁻
[0035] The two reactions described above together lead to the formation of Cu2O / CuO oxide species on the copper surface during the CMP process, and form a net reaction with the cathodic electroreduction reaction of H2O2 in a mixed potential mode, which can be represented as follows: 2Cu + H₂O₂ = Cu₂O + H₂O; Cu + H₂O₂ = CuO + H₂O; This results in the formation of a residual oxide layer on the copper surface, primarily composed of Cu2O with some CuO present, providing a basis for subsequent complexation and dissolution removal by the TA cleaning solution.
[0036] Copper samples pretreated with CMP are introduced into a brushed post-cleaning device for chemical mechanical planarization (CMP) cleaning. The post-cleaning device is equipped with a polyvinyl alcohol (PVA) brush that rotates during cleaning, with an example operating speed of 60 RPM. The TA cleaning solution also serves as the electrolyte medium in this device. The sample is immersed in the TA cleaning solution for 1 minute, and the brush operation can be selectively turned on or off during cleaning to create both brushless static cleaning and brushed dynamic cleaning conditions. Through dynamic brushing, localized hydrodynamic shearing and friction are generated between the brush bristles and the copper surface, making it easier to agitate and remove surface oxides and their co-adsorbed residues. Simultaneously, under near-neutral conditions, TA complexes and dissolves oxide residues in a deprotonated form and stabilizes copper ions in the solution, thereby reducing the risk of copper ion hydrolysis deposition on the surface and the resulting formation of secondary oxides. The sample processing path corresponding to this combination of conditions may include: CMP immersion only to form residue; CMP immersion followed by cleaning in TA cleaning solution; and cleaning directly in TA cleaning solution to reflect the effect of cleaning solution and brushing on cleaning the copper surface. All of the above cleaning can be performed under brushed or brushless conditions.
[0037] In the post-cleaning process, the dissolution of copper and the behavior of dissolution products under near-neutral conditions must also be considered. Based on the electrochemical dissolution characteristics of copper at pH < 7, Cu²⁺ may be present in the solution, and its formation reaction can be expressed as: Cu = Cu²⁺ + 2e⁻. The generated Cu²⁺ exists in a hydrated form, denoted as [Cu(H₂O)n]²⁺, where n is usually 6. These hydrated copper ions may deposit and cause particulate or oxide contamination when interfacial conditions change. TA cleaning solution uses tartrate to complex and stabilize Cu²⁺, helping to inhibit further deposition of hydrated Cu²⁺ ions on the surface and reducing the tendency for secondary CuO / Cu₂O contamination caused by deposition and transformation. This, combined with the mechanical stripping effect of brushing, allows for a more thorough removal of residues from the brushed area and its adjacent areas.
[0038] Other embodiments of this disclosure will readily occur to those skilled in the art upon consideration of the specification and practice of the invention disclosed herein. This application is intended to cover any variations, uses, or adaptations of this disclosure that follow the general principles of this disclosure and include common knowledge or customary techniques in the art not disclosed herein. The specification and embodiments are to be considered exemplary only, and the true scope and spirit of this disclosure are indicated by the claims.
[0039] It should be understood that this disclosure is not limited to the precise structures described above and shown in the accompanying drawings, and various modifications and changes can be made without departing from its scope. The scope of this disclosure is limited only by the appended claims.
Claims
1. A chip cleaning agent, characterized in that, The chip cleaning agent is an aqueous cleaning agent used for cleaning the surface of copper-containing chips after chemical mechanical planarization. The chip cleaning agent comprises: a tartaric acid complexing agent and a pH adjusting component; wherein: The tartaric acid complexing agent is a complexing agent containing tartaric acid and tartrate salts that can provide tartrate ions in an aqueous system; the pH adjustment component is used to adjust the chip cleaning agent to a near-neutral working pH, which is a pH range in which the tartaric acid complexing agent is mainly in the form of deprotonated tartrate ions and can achieve complex dissolution of copper oxides without relying on strong acid or strong base conditions, while inhibiting the spontaneous dissolution of substrate copper. The tartrate ions are configured to complex with copper ions dissolved or migrated to the liquid phase during the cleaning process to form soluble copper. Tartaric acid complexes are used to inhibit the hydrolytic deposition of copper ions on the surface of the copper-containing chip and reduce the secondary formation of copper oxides; tartaric acid complexes are also used to react with residual copper oxides on the surface of the copper-containing chip, converting the residual copper oxides into soluble complexes that are carried away by the liquid phase; and the tartaric acid ions can be adsorbed on the surface of the copper-containing chip to form an adsorption layer, thereby inhibiting the excessive dissolution of the substrate copper and reducing the copper oxide concentration during the cleaning process. The redeposition of tartaric acid complexes on the surface of the copper-containing chip.
2. The chip cleaning agent according to claim 1, characterized in that, The tartaric acid complexing agent includes tartaric acid, a racemic mixture of tartaric acid, an enantiomer of tartaric acid, a tartrate salt, or a combination thereof, wherein the tartrate salt is selected from ammonium salts, alkali metal salts, organic amine salts, or a combination thereof, so that the tartaric acid complexing agent provides a multidentate coordinated tartrate ion at the near-neutral working pH and forms a complex capable of stabilizing copper ions.
3. The chip cleaning agent according to claim 1, characterized in that, The pH adjusting component is an alkaline adjusting component, which is selected from ammonium hydroxide, ammonia, alkali metal hydroxide, alkali metal carbonate, buffer amine or a combination thereof. The alkaline adjusting component is used to adjust and maintain the pH of the chip cleaning agent at the near-neutral working pH so that the tartrate ions remain in a deprotonated state and continuously provide complexation ability for copper ions during the cleaning process.
4. The chip cleaning agent according to claim 1, characterized in that, The chip cleaning agent is configured to remove residues formed and remaining on the surface of the copper-containing chip during the chemical mechanical planarization process. The residues include at least one of cuprous oxide and copper oxide, as well as surface complexes or adsorption films co-adsorbed with at least one of cuprous oxide and copper oxide. The surface complex or the adsorption film comprises copper formed from a nitrogen-containing heterocyclic corrosion inhibitor. Inhibitor complexes, copper formed by amino acid complexing agents Amino acid complexes, and combinations thereof, enable the chip cleaning agent to synergistically remove the surface complexes or the adsorbed film by preferentially complexing and dissolving at least one of the cuprous oxide and the copper oxide, and reduce its surface masking effect on subsequent processes.
5. The chip cleaning agent according to claim 1, characterized in that, The chip cleaning agent is used in conjunction with a brushing process, which employs a polyvinyl alcohol brush or a porous elastic polymer brush to dynamically brush the surface of the copper-containing chip, thereby creating localized hydrodynamic shearing and friction between the brush bristles and the surface of the copper-containing chip; under this dynamic brushing action, the copper... The tartaric acid complex and the adsorption layer exist in a weak adsorption state and are mechanically peeled off and carried away with the liquid phase, so that the copper-containing chip surface can achieve a residue removal effect in the brushing area and its adjacent area.
6. A method for producing a chip cleaning agent, characterized in that, The chip cleaning agent is an aqueous cleaning agent used for cleaning the surface of copper-containing chips after chemical mechanical planarization, and the chip cleaning agent includes at least a tartaric acid complexing agent and a pH adjusting component; the production method includes: Water is provided as a solvent; The tartaric acid complexing agent is added to the solvent and mixed to dissolve the tartaric acid complexing agent to obtain a tartaric acid solution. The pH adjusting component is added to the tartaric acid solution and adjusted to a near-neutral working pH, so that the tartaric acid complexing agent forms a complexing system in the tartaric acid solution with tartrate ions as the main form. The adjusted solution is purified to remove particles and insoluble matter; and the purified solution is sealed and packaged to obtain the chip cleaning agent.
7. The method for producing chip cleaning agent according to claim 6, characterized in that, The water used as a solvent in the step of providing water is deionized water, distilled water, or water that has undergone multi-stage purification; the step of adding the tartaric acid complexing agent to the solvent and mixing it includes at least one of stirring, circulating mixing, or ultrasonic dispersion until the tartaric acid complexing agent forms a homogeneous solution in the solvent; the step of adding the pH adjusting component and adjusting it to the near-neutral working pH includes adding the pH adjusting component gradually and monitoring the pH change simultaneously, so that the tartaric acid complexing agent in the resulting solution is mainly in the form of tartaric acid ions and forms the complexing system.
8. The method for producing chip cleaning agent according to claim 6, characterized in that, The purification process includes filtration to remove particles and insoluble matter, and the filtration includes at least one of membrane filtration, microfiltration, or deep filtration to reduce secondary defects caused by particulate contamination introduced during the use of the chip cleaning agent.
9. The method for producing a chip cleaning agent according to claim 6, characterized in that, The sealed packaging includes dispensing the chip cleaning agent into a sealed packaging container in a clean environment and labeling it. The sealed packaging container is a polymer material container or an inert metal material container that is chemically inert to the chip cleaning agent. The label includes that the chip cleaning agent is applicable to the surface of copper-containing chips after chemical mechanical planarization and that the applicable process is at least one of static immersion cleaning and dynamic brush cleaning.